Experimental Investigation of Friction and Wear in Automotive Brake Pads: The Role of Load and Speed

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Essam, Mohamed M. Faragallah, Noha M. Abdeltawab, M. Ali This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7591285/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 13 Jan, 2026 Read the published version in Scientific Reports → Version 1 posted 13 You are reading this latest preprint version Abstract This study examines the frictional and abrasive wear characteristics of a semi-metallic brake pad composite under different applied loads, sliding velocities, and rotating speeds. The brake pad, consisting of 13 components including SiC, MgO, and 3-mm aramid fibers, was produced by powder metallurgy and assessed according to SAE J661 standard standards. The results indicated that the coefficient of friction (COF) rose from 0.697 at 5 N to 0.795 at 30 N, signifying enhanced interfacial resistance attributable to surface compaction and tribo-film stabilization. The specific wear rate increased with load, from 0.405 g/N at 5 N to 1.065 g/N at 30 N, indicating a compromise between friction and wear resistance. The sliding velocity demonstrated a dual effect: the (COF) rose from 0.663 at 0.4 m/s to 0.797 at 0.8 m/s, while the wear rate climbed from 0.47 g·s/m to 1.02 g·s/m, representing a 116% escalation. Increasing the RPM from 100 to 1000 resulted in a significant 64.5% reduction in the (COF), decreasing from 0.44 to 0.156, attributable to heat softening and surface deterioration. SEM research indicated a change in wear mechanisms from abrasive at 200 RPM to oxidative at 400 RPM, and severe adhesive wear at 800 RPM. These findings underscore the necessity of improving operational circumstances to reconcile friction performance with material durability in high-speed braking systems. Physical sciences/Engineering Physical sciences/Materials science Braking pads Coefficient of Friction Abrasive Wear Sliding Velocity Friction Materials Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1. Introduction The main purpose of braking pad is to transform kinetic energy into thermal energy via friction, therefore reducing or stopping a vehicle's speed [ 1 ]. This process entails intricate interactions between the brake pad and the disc rotor, which must endure severe circumstances, including high temperatures, substantial pressures, and repetitive mechanical stresses. The tribological properties specifically friction and wear resistance of brake pad materials are crucial for preserving braking efficiency and extending component lifespan [ 2 ]. Asbestos was historically utilized in brake pads because of its superior thermal stability, mechanical strength, and economic efficiency. Nonetheless, owing to its established health risks, including carcinogenic properties, its utilization has been prohibited or limited in numerous nations [ 3 ]. This has prompted substantial investigation into alternate materials, including non-asbestos organic (NAO) composites, semi-metallic formulations, and ceramic-based pads. These alternatives generally incorporate binders, fillers, friction modifiers, and reinforcements to get optimal performance attributes. Phenolic resins function as high-temperature binders, whilst copper and aramid fibers augment mechanical strength and thermal dissipation [ 3 ]. The wear characteristics of brake pads are affected by various operational aspects, such as sliding velocity, applied load, temperature, and the properties of the friction surface. Research, including Gawande et al., indicates that the wear rate escalates with increased applied stress, and materials such as CL3003 demonstrate markedly reduced wear compared to conventional asbestos-based pads under the same testing conditions [ 4 ]. Additionally, the thermal and mechanical properties of brake pads must be refined to mitigate noise, vibration, and particulate emissions, which are significant issues in urban and high-performance settings [ 5 ]. The ongoing progress in materials science and tribology is steering the creation of brake pads that are efficient, robust, and environmentally friendly. The automotive industry is advancing towards elevated safety and emissions regulations, making the selection and optimization of brake pad materials a prominent focus of research and innovation [ 5 ]. 2. Literature review The composition of a standard brake pad has four primary types of components: binders, fillers, reinforcements, and friction modifiers. The binder, often phenolic resin, offers thermal stability and mechanical integrity in high-temperature environments [ 6 ]. Fillers such baryte (BaSO₄), synthetic graphite, and alumina are incorporated to enhance volume, reduce costs, and modify certain characteristics such as compressibility or fade resistance. Reinforcements like copper and iron powders augment structural integrity and heat conductivity. Friction modifiers, such as abrasives and lubricants like silicon carbide and zinc, assist in regulating the (COF) while minimizing noise and vibrations [ 5 ]. Recent research highlights the tribological characteristics of alternate brake pad materials, evaluating their performance across different loads, sliding velocities, and thermal conditions. Gawande et al. discovered that non-asbestos materials, specifically CL3003, surpassed asbestos in terms of wear resistance and friction stability. Their investigations demonstrated that weight loss in asbestos pads could attain 8–10%, markedly exceeding that of their non-asbestos equivalents [ 5 ]. Kshirsagar and Khairnar investigated both analytical and experimental assessments of the coefficient of friction in brake disc-pad systems[ 3 ]. Employing the Greenwood-Williamson contact mechanics model and pin-on-disc testing, they documented a coefficient of friction range of 0.2–0.4, contingent upon load and velocity. Their findings corroborated the model and indicated that material surface roughness and interface pressure significantly affect braking efficiency [ 7 ]. Moreover, recent research has investigated bio-based fillers such as banana peels and carbonized organics as viable eco-friendly alternatives, demonstrating favorable outcomes regarding wear rate and environmental effects [ 8 ]. Researchers also investigate aramid fibers, steel wool, and synthetic rubbers to augment mechanical strength while minimizing noise and particulate emissions [ 9 ]. Metallic ingredients are commonly used in friction materials for automotive braking systems to increase thermal diffusivity, wear resistance and strength [ 10 ]. The (COF) between the brake pad and rotor surface is significantly affected by the applied load. As loads increase, the actual contact area between surfaces expands due to the deformation of asperities, leading to more equal contact and occasionally a reduced (COF) [ 11 ]. Sawczuk et al. noted that an increase in pad clamping force resulted in heightened frictional heating, causing softening at the contact surface and a decrease in the (COF) [ 12 ]. For example, at a clamping force of 13 kN, the (COF) was around 0.45; however, it decreased to about 0.38 at 19 kN due to thermally produced lubricious layers and diminished mechanical interlocking at elevated loads [ 13 ]. Panchenko et al. additionally showed that excessive loading diminished the (COF) and led to uneven pad degradation, hence undermining contact uniformity and friction stability over time [ 14 ]. The unequal pressure distribution during load application resulted in stress concentrations, facilitating the premature emergence of thermal cracks and localized delamination [ 15 ]. Sliding velocity has a dual impact on the (COF) beginning increments in speed may marginally elevate friction due to enhanced micro-ploughing, whereas extreme velocities generally diminish COF due to thermal effects [ 16 ]. Sawczuk et al. reported that the (COF) decreased from roughly 0.46 at 50 km/h to 0.37 at 200 km/h in a railway disc brake test apparatus [ 12 ]. This decline is ascribed to the thermal glazing of the pad surface and the loss of mechanical adhesion at elevated velocities [ 12 ]. Abrasive wear rate generally increases with applied load. In the same pin-on-disc tests, the wear volume of the specimen increased from 0.85 mm³ to 1.42 mm³ as the load rose from 30 N to 70 N, indicating higher energy dissipation and micro-cutting mechanisms at elevated loads [ 17 ]. The wear rate (calculated as volume loss per sliding distance) doubled under this load increment, signifying load sensitivity in abrasive conditions. This inverse relationship was further corroborated by a mid-band frequency vibration analysis, in which elevated sliding speed diminished signal amplitude due to decreased interfacial friction [ 18 ]. At elevated velocities, stick-slip transitions diminished, leading to a more stable yet lowered coefficient of friction profile [ 18 ]. The sliding velocity significantly influences the degree of abrasive wear, however the correlation may be non-linear [ 19 ]. As velocity escalates, surface temperature increases, affecting oxidation and microstructural alterations in the pad material. Sawczuk et al. (2022) indicated that wear escalated with velocity up to 120 km/h, reaching a maximum mass loss of 1.08 g, subsequently decreasing to 0.98 g at 160 km/h, implying the development of protective oxide layers at elevated temperatures [ 12 ]. Rotational speed (RPM), as a proxy for sliding velocity in rotating systems, also impacts the COF. As RPM increases, the surface temperature rises, which often leads to thermal degradation of the contact interface. In a disk brake test, increasing RPM from 300 to 800 led to a decrease in COF from 0.43 to 0.36 due to thermal softening and possible formation of third-body layers [ 20 ]. However, the effect plateaued beyond 800 RPM, suggesting a dynamic balance between heating and material adaptation [ 21 ]. This study aims to evaluate the effects of applied load, sliding velocity, and rotational speed on the coefficient of friction and wear rate of a semi-metallic brake pad composite, to optimize braking performance and material durability under varying operating conditions. 3. Experimental Work 3.1 Braking Pad Friction Materials This study involved the fabrication of semi-metallic brake pad compositions, consisting of thirteen constituents as detailed in Table 1 , utilizing a powder metallurgy approach. The manufacturing process adhered to a systematic sequence to guarantee optimal material properties and performance. The raw materials were blended in a rotating mixer at 90 rpm for 3 hours to ensure uniform distribution of the ingredients. A backing plate was prepared to ensure a stable substrate for the adhesion of composite materials. The mixed powder was subjected to perform compaction to attain initial densification. A hot compaction process was subsequently conducted using a hydraulic press within a die at a pressure of 20 MPa. In the process of hot compaction, the upper and lower molds were held at temperatures of 168°C and 177°C, respectively, for a duration of 6 minutes to facilitate robust interparticle bonding and improve mechanical integrity. A post-treatment was conducted at 170°C for 2 hours to enhance the stability of the thermoset matrix, thereby improving its toughness and thermal stability. The fabricated samples underwent a finishing process to enhance their surface and dimensional properties, ensuring adherence to rigorous quality and performance standards. The prototype, referred to as the tested sample, functions as a benchmark for comparative analysis and performance assessment. Figure 1 presents a schematic representation of the manufacturing process. Table 1 Formulation of chemical composition for the tested sample of friction material. Element Graphite Wire Rock wool Rubber Lime Barite Vermacult Resin Zirconium oxide Aramid fiber (3mm) SiC MgO Coke Weight % 5.5 5 5 7 5 26.5 6 11 4 7 3 7 8 3.2 Microstructure and Hardness Test Samples with dimensions the same as those prepared for microscopy were utilized to evaluate the hardness properties of the brake pad specimens. Rockwell C hardness measurements were conducted at room temperature utilizing a Zwick/Roell ZHR hardness tester (ZwickRoell Group, Ulm, Germany) at the Central Metallurgical Research and Development Institute (CMRDI), featuring a diamond indenter and a load of 150 kgf. Testing was performed over an area of 250 mm × 150 mm to verify spatial uniformity. The hardness value of each specimen was determined by averaging four independent measurements to ensure statistical reliability. Microstructural characterization utilized field emission scanning electron microscopy (FESEM; Carl Zeiss Sigma AG, Oberkochen, Germany) and laser scanning confocal microscopy (LSCM; VK-200, Keyence Ltd., Osaka, Japan). These techniques facilitated a comprehensive evaluation of surface morphology, grain structure, and phase distribution in the brake pad composites. The FESEM analysis yielded high-resolution insights into particle bonding and interfacial integrity, whereas LSCM enabled three-dimensional topographic mapping of the surface. These methodologies clarified essential connections among microstructure, mechanical performance, and compositional homogeneity. 3.3 Wear Test Measurements of wear and friction coefficients were performed following the Society of Automotive Engineers (SAE) J661 standard. In the testing phase, the brake pad sample was placed in contact with a rotating brake drum, which operated at incremental rotational velocities of 200, 300, 400, 500, 600, 700, 800, and 1000 rpm as shown in Fig. 2 . The test duration facilitated a comprehensive assessment of the material's tribological behavior, including friction and wear characteristics, as well as wear resistance under conditions that simulate real-world automotive applications. A pin-on-disc tribometer was utilized for supplemental analysis to measure wear rate and friction coefficient. Specimen pins with specified dimensions (6 mm in diameter and 18 mm in height) were fabricated and affixed to the machine. The testing parameters, such as applied load, sliding speed, and test duration, were meticulously regulated. The pin was applied to the rotating disc under specified conditions, and the instantaneous friction coefficient was documented at 20-second intervals throughout a 20-minute duration. This method guaranteed high-resolution observation of tribological dynamics during the test. All experimental procedures were conducted at the Mechanical Testing and Materials Characterization Laboratory of the at the Central Metallurgical Research and Development Institute (CMRDI), Egypt. 4. Results and Discussions 4.1 Microstructure Examination The supplied SEM micrographs depict the surface morphology of a brake pad composite material at a magnification of 250x. Figure 3 a presents an overview of the composite, emphasizing the uneven distribution of elements and the occurrence of microstructural flaws, including micro-cracks and voids. These characteristics indicate inhomogeneity within the matrix, perhaps resulting from inadequate mixing or insufficient adhesion between the reinforcement and the matrix. The coarse surface, along with observable fiber pull-outs and fragmented particles, indicates ongoing wear mechanisms, presumably a combination of abrasive and adhesive wear, prevalent in high-friction applications like braking systems [ 22 , 23 ]. The uneven configurations and dispersed characteristics of the implanted particles further suggest a multiphase material engineered to endure mechanical forces and thermal fluctuations during braking. Figure 3 b offers a detailed view with annotated sections delineating several phases within the composite. A fibrous structure is integrated in the matrix, indicating the reinforcement phase potentially organic or inorganic fibers included to enhance the mechanical strength and toughness of the brake pad. These fibers function to disperse stresses during braking and mitigate crack formation. A bright white inclusion described as magnesium oxide (MgO), a prevalent addition in friction materials, is also noted. Owing to its elevated atomic number, MgO exhibits increased brightness in backscattered electron microscopy and is commonly incorporated to enhance thermal conductivity, wear resistance, and frictional stability [ 24 ]. The well-dispersed presence indicates good integration into the matrix; however, perfect homogeneity may not be attained, as certain places exhibit clustering or uneven distribution. The composite's microstructure, as depicted in these SEM pictures, demonstrates a purposeful amalgamation of hard particles and fiber reinforcement within a polymer or resin matrix. The observable fissures and delamination in Fig. 3 a may signify areas of inadequate fiber-matrix adhesion, potentially undermining performance under severe thermal and mechanical stresses [ 24 ]. The inclusion of magnesium oxide and fiber in image (b) underscores the material's engineering design intended to optimize strength, frictional performance, and thermal dissipation. The SEM examination indicates that the brake pad sample has the characteristic structural complexity of a reinforced composite material, with microstructural characteristics that significantly affect its tribological performance and operational longevity [ 25 ]. 4.2 Hardness Measurements Figure 4 depicts the Rockwell Hardness (HRC) values of a brake pad formulation consisting of silicon carbide (SiC), 3-mm fibers, and magnesium oxide (MgO), assessed prior to and subsequent to tribological testing. The findings demonstrate a uniform rise in hardness throughout all areas of the material post-testing, signifying strain hardening due to frictional heating and mechanical stress encountered during braking. This behavior exemplifies work-hardening mechanisms typically seen in composite systems, where reinforcing elements like SiC and MgO are pivotal in improving wear resistance and structural integrity [ 26 ]. Before testing, the preliminary hardness measurements revealed regional discrepancies, with certain regions displaying reduced HRC values. This fluctuation is likely due to the irregular distribution of fibers and reinforcing particles inside the composite matrix. Subsequent to tribological testing, all assessed locations exhibited a notable and consistent enhancement in hardness, highlighting the material's capacity to endure wear and preserve mechanical performance under cyclic loading circumstances [ 27 ]. The enhancement in post-test hardness can be ascribed to a confluence of synergistic effects. Silicon carbide provides exceptional hardness and resistance to plastic deformation, hence improving the surface durability of the brake pad. Magnesium oxide enhances thermal stability and facilitates grain refinement, hence minimizing microstructural deterioration during high-temperature operation. Furthermore, the 3-mm fiber reinforcements facilitate the uniform distribution of applied stresses across the material, thereby alleviating localized wear and inhibiting crack formation and propagation [ 28 ]. The increase in hardness is associated with microstructural densification and the development of a friction-induced protective tribolayer on the contact surface, indicating the composite's adaptive response to challenging operational conditions. The findings underscore the substantial roles of SiC, MgO, and fiber reinforcement in enhancing the durability and reliability of brake pad materials, rendering this formulation exceptionally appropriate for high-performance braking systems that necessitate prolonged service life and wear resistance [ 28 ]. 4.3 Effect of Applied Load on Coefficient of Friction Figure 5 depicts the behavior of the (COF) for a brake pad composite material subjected to different applied normal loads of 5 N, 10 N, 20 N, and 30 N. The (COF) is an essential metric for assessing braking performance, as it indicates the material's capacity to withstand sliding under pressure; a higher COF typically corresponds to improved braking efficiency. The Fig. 5 presents the average COF values along with the associated error bars, indicating the standard deviation or variability in the measured values. At a load of 5 N, the composite demonstrates a coefficient of friction of 0.697, indicating the material's initial frictional performance under low contact pressure. This value is classified as moderately high, suggesting that the brake pad surface effectively resists sliding. This effectiveness is likely attributable to factors such as surface roughness, particle interactions, and the initial development of a tribolayer [ 29 ]. At 10 N, the coefficient of friction decreases marginally to 0.696, indicating negligible change. The observed minor difference indicates stability in contact conditions within this load range, suggesting that the brake pad material can sustain consistent performance under light to moderate loads. The minimal deviation indicates a stable interface, characterized by the absence of excessive wear or smearing at this stage, thereby maintaining the integrity of the contact surface [ 29 , 30 ]. With an increase in the applied load to 20 N, the (COF) increases markedly to 0.773. The increase indicates a change in the tribological behavior of the material, suggesting that more intense interfacial interactions are occurring. This may result from various phenomena: improved mechanical interlocking of surface asperities, heightened activation of reinforcing particles (e.g., SiC and MgO), and potentially the emergence of mild thermal effects that cause softening or flow of the matrix phase, thereby enhancing adhesion with the counter surface. This behavior indicates that the material transitions to a more effective frictional regime, enhancing its resistance to motion through optimized component engagement [ 30 ]. Under the maximum applied load of 30 N, the (COF) attains a maximum value of 0.795, signifying optimal frictional performance across all evaluated conditions. This trend indicates that the brake pad composite exhibits significant pressure sensitivity and reacts favorably to elevated normal loads, likely attributable to surface layer compaction, tribolayer stabilization, and the mitigation of micro-cracking or delamination under prolonged loading conditions [ 31 ]. The development of a stable, protective third-body layer from wear debris may enhance contact adhesion and decrease material loss. This finding is significant for practical braking applications, where materials experience repeated high loads and must reliably provide effective stopping power [ 32 ]. 4.4 Effect of Sliding Velocity on Coefficient of Friction Figure 6 demonstrates the variation of the (COF) for a brake pad composite in relation to sliding velocity, which spans from 0.4 m/s to 0.8 m/s. The data points indicate a clear increasing trend in COF with rising velocity, suggesting enhanced frictional performance at elevated operational speeds. Each data point includes error bars that indicate the variability or uncertainty in the measured values, thereby reflecting the reliability and repeatability of the test [ 33 ]. At a sliding velocity of 0.4 m/s, the (COF) is recorded at 0.663, representing the lowest value observed throughout the entire test range. The observed lower friction level can be ascribed to relatively mild interfacial contact, restricted thermal activation, and a less developed third-body layer formation. Furthermore, at this velocity, the kinetic energy applied is minimal, potentially resulting in inadequate engagement between the composite constituents and the counter surface, thereby diminishing frictional interaction. The error bar at this velocity is one of the largest, suggesting increased variability in frictional behavior, likely attributable to unstable contact or microstructural inconsistencies [ 34 ]. At a velocity of 0.5 m/s, the (COF) increases to 0.707, indicating a rise of approximately 6.6% relative to the value at 0.4 m/s. This increase indicates the emergence of a more stable tribological interaction between the brake pad and the sliding surface. The surface temperature at this velocity is likely adequate to induce mild softening or flow of the matrix, resulting in improved surface conformity and enhanced mechanical interlocking. At a velocity of 0.6 m/s, the (COF) attains a value of 0.758, representing a 7.2% increase compared to the value at 0.5 m/s. The ongoing upward trend can be linked to a more effective tribo-film formation on the contact surface, as the increase in temperature promotes plastic deformation and compaction of wear debris. This behavior generally leads to enhanced adhesion and shear strength at the interface, thereby increasing friction. The maximum (COF) is observed at a sliding velocity of 0.8 m/s, attaining a value of 0.797. This indicates a 20.2% increase relative to the initial coefficient of friction at 0.4 m/s. At this velocity, considerable thermal and mechanical stresses are exerted on the material. The brake pad composite exhibits interfacial stability, attributed to the synergistic effects of reinforcing phases including SiC, MgO, and fiber reinforcement. The microstructure of the composite likely enhances thermal conductivity and structural stability, thereby preventing degradation or smearing of the contact layer, which could otherwise result in reduced friction. The COF rises from 0.663 at 0.4 m/s to 0.797 at 0.8 m/s, marking an overall increase of 0.134 units or roughly 20.2%. This clear and consistent enhancement in COF with velocity demonstrates the composite’s robust frictional characteristics, its ability to form a stable contact layer, and its suitability for high-speed braking applications. These results support the material's potential in performance-critical systems that require both stability and efficiency under dynamic conditions. 4.5 Abrasive Wear Based on Applied Load Figure 7 illustrates the correlation between the applied normal load (N) and the specific wear rate of a brake pad composite, represented as m (g/N). The specific wear rate is a crucial parameter in tribological studies, quantifying material loss per unit load and serving as a key indicator for assessing the wear resistance of braking materials under different mechanical stress conditions [ 35 ]. At a load of 5 N, the wear rate recorded is 0.405 g/N, representing the minimum value observed in the experiment. This indicates that at low contact pressures, the material experiences minimal degradation, probably because of limited heat generation and decreased mechanical disruption at the friction interface. The error bar at this load is minimal, suggesting reliable test outcomes. With an increase in load to 10 N, the wear rate approximately doubles, reaching 0.740 g/N. This indicates an estimated increase of 82.7% relative to the wear observed at 5 N. The increase is due to elevated contact stresses, which cause more intense surface abrasion and the onset of microcracks, resulting in increased material removal. The increased wear rate at this stage may indicate the beginning of thermal softening or matrix degradation, which diminishes the composite's resistance to additional wear [ 36 ]. At a load of 20 N, the wear rate increases to 0.913 g/N, reflecting a 23.4% increase relative to the 10 N scenario. This trend indicates that material loss intensifies as load increases. The frictional heat and pressure may lead to partial degradation of the matrix or fiber-matrix interfaces, thereby diminishing the structural cohesion of the surface layer. The increased wear rate exhibits a slight deceleration, indicating potential surface compaction or the development of a protective third-body layer that intermittently mitigates further wear. At a maximum load of 30 N, the wear rate reaches 1.065 g/N, representing the highest value recorded in the study. This indicates a 16.7% increase relative to the 20 N result and a 162.7% increase in comparison to the wear observed at 5 N. The substantial error bar at this load signifies considerable variability in wear behavior, potentially resulting from uneven material removal, localized thermal damage, or inconsistent formation of the third-body layer. The ongoing increase in wear rate with load indicates that the brake pad composite becomes more vulnerable to degradation under higher mechanical stress, notwithstanding potential enhancements in frictional performance, as evidenced by the COF figures. The Fig. 7 demonstrates a direct correlation between applied load and wear rate, with specific wear increasing from 0.405 g/N at 5 N to 1.065 g/N at 30 N. The data suggests that although the composite may enhance frictional performance under elevated loads, this improvement is accompanied by greater material loss. The trade-off between friction and wear is a crucial factor in brake pad design. Optimizing material composition, including the balance of reinforcement content and matrix stability, is vital for ensuring long-term performance and durability in high-stress braking applications [ 36 ]. 4.6 Abrasive Wear Based on Sliding Velocity Figure 8 illustrates the correlation between sliding velocity (m/s) and the specific wear rate of a brake pad composite, quantified in grams per second per meter (g·s/m). The x-axis represents sliding velocity, varying from 0.4 m/s to 0.8 m/s, while the y-axis displays the specific wear rate values, quantitatively measuring material loss due to frictional motion at these velocities. The data incorporate error bars that indicate the experimental variability or standard deviation for each velocity measurement. At a velocity of 0.4 m/s, the specific wear rate is 0.47 g·s/m, representing the minimum value observed in this dataset. This indicates that at reduced sliding speeds, the brake pad surface experiences comparatively mild abrasion. Reduced frictional heat and diminished mechanical interaction between contact surfaces likely lead to a decrease in material detachment. This value demonstrates a minimal error bar, reflecting significant consistency and stability in the measurements at this velocity [ 1 ]. With an increase in sliding velocity to 0.5 m/s, the wear rate escalates to 0.62 g·s/m, reflecting an approximate increase of 31.9% relative to the wear rate at 0.4 m/s. The increase is due to enhanced surface interactions and the initiation of more severe micro-abrasive and fatigue wear. The rise in velocity results in enhanced frictional energy conversion into heat, which induces localized softening of the matrix and may expedite the removal of worn particles. At a velocity of 0.6 m/s, the specific wear rate increases, attaining a value of 0.721 g·s/m. This indicates a 16.3% increase relative to the value at 0.5 m/s, implying a steady advancement in wear severity. The moderate error bar indicates stable yet somewhat variable test conditions, likely resulting from dynamic changes at the friction interface, including the formation or disruption of tribological films. The maximum wear rate occurs at 0.8 m/s, recorded at 1.02 g·s/m, representing a 116% increase compared to the wear rate at 0.4 m/s. The notable increase indicates that high-speed sliding markedly enhances material loss. At this velocity, significant frictional heating occurs, potentially resulting in thermal degradation of the matrix and the failure of fiber–matrix bonding. The potential for thermal softening and oxidation increases, leading to the formation of unstable third-body layers and the generation of loose debris, which exacerbates wear [ 1 ]. 4.7 Effect of Different RPM on Coefficient of Friction Figure 9 demonstrates the relationship between rotational speed (RPM) and the (COF) for a brake pad composite. At a low speed of 100 RPM, the (COF) is 0.44, representing the maximum value recorded in the dataset. This indicates that at low-speed operation, the composite surface retains effective interfacial grip, probably owing to reduced heat generation and minimal surface softening or degradation. At an RPM of 200, the (COF) decreases marginally to 0.398, indicating a reduction of 9.5%. This suggests the onset of a declining trend, potentially attributable to initial thermal effects and alterations in the wear surface morphology, which begin to diminish the adhesion between the mating surfaces [ 29 ]. As the speed increases to 400 RPM, the (COF) declines significantly, reaching a value of 0.31. This represents a 22.1% decrease from the initial coefficient of friction at 100 RPM, indicating that frictional heating intensifies, leading to the softening or weakening of the tribological film, which subsequently diminishes braking efficiency [ 29 ]. At 500 RPM, the decrease to 0.289, maintaining the observed downward trend. This trend is particularly evident at 600 RPM, where the (COF) decreases to 0.215, reflecting a 51.1% reduction from the initial COF measured at 100 RPM. The significant decrease may result from a failure in surface integrity, leading to reduced surface resistance and diminished contact efficacy between the pad and the rotating surface. At 700 RPM, the (COF) increases slightly to 0.221, indicating a minor rebound effect. This may result from a temporary reformation of a tribolayer or a more stable compaction of wear particles at this speed, which temporarily enhances surface interaction. This increase is marginal and not sustained. At 800 RPM, the (COF) decreases to 0.19, and at the maximum tested speed of 1000 RPM, the COF attains its lowest value of 0.156, reflecting a 64.5% reduction from the value observed at 100 RPM. At elevated speeds, the surface is likely to undergo considerable thermal degradation, potential smearing of matrix material, and a reduction in mechanical interlocking, all of which contribute to decreased friction. 4.8 Worn Surface Morphology of Brake Pad Materials at Varying Rotational Speeds The SEM micrographs presented in Fig. 10 offer a comparative analysis of the worn surface morphology of a brake pad composite at different rotational speeds: (a) 200 RPM, (b) 400 RPM, and (c) 800 RPM. All images are captured at 1000× magnification, featuring a scale bar of 100 µm, which facilitates a detailed examination of the tribological behavior under varying dynamic conditions. The observations indicate distinct differences in wear mechanisms and surface evolution with increasing RPM [ 37 ]. Figure 10 a illustrates the worn surface at 200 RPM, characterized by a rough and heterogeneous morphology. The presence of sharp-edged reinforcement particles, some of which are partially extracted, in conjunction with grooves and micro-cracks, indicates that abrasive wear predominates at this low speed. The irregular distribution of wear debris and the absence of a continuous tribo-film suggest restricted thermal activation and mechanical energy input. The wear debris exhibits loose adhesion, and the lack of smeared areas indicates limited plastic deformation. The microstructure largely preserves its original characteristics, indicating mild wear accompanied by localized material detachment, likely caused by contact fatigue and mechanical interlocking among asperities [ 37 ]. Conversely, Fig. 10 b depicts the worn surface at 400 RPM, showing a markedly smoother and more compacted appearance. The wear track exhibits reduced particle pull-out and a lower incidence of cracks, along with the development of a more uniform and densified tribo-layer. This morphological transition indicates a change from abrasive to oxidative and adhesive wear mechanisms, facilitated by heightened frictional heat generation at this intermediate speed. The matrix phase seems to have initiated softening, which facilitates the smearing and bonding of fine wear debris into a semi-continuous protective layer. A tribological film protects the surface from additional damage and enhances the stability of the frictional interface. The wear is reduced in severity but increased in uniformity, indicating enhanced energy dissipation and a more stable sliding regime. At 800 RPM, as illustrated in Fig. 10 c, the surface morphology undergoes significant alterations, characterized by dense smearing, plastic flow, and pronounced structural deformation. The matrix exhibits significant softening, and the wear debris is consolidated into large, unstable agglomerates. Evidence of melting or thermal degradation is apparent, particularly in darker regions, indicating the significant heat produced at this elevated rotational speed. The distribution of reinforcement particles becomes unclear, as numerous particles are incorporated within the plastically deformed matrix. This suggests a prevalence of severe adhesive and fatigue wear, along with potential thermal wear mechanisms. The tribo-layer exhibits instability and may undergo delamination, leading to expedited surface failure. The wear observed at 800 RPM is the most pronounced, exhibiting evident surface deterioration, material flow, and a compromise of the composite's structural integrity. The transition from 200 to 800 RPM indicates a shift in wear behavior from mechanical abrasion to thermo-mechanical deformation and fatigue. At 200 RPM, wear is minimal and localized; at 400 RPM, the surface shows the formation of a protective tribo-film; and at 800 RPM, the surface experiences significant damage from excessive thermal and mechanical stress [ 38 ]. The findings underscore the significance of choosing operational speeds that enhance both friction and wear resistance in braking systems. Conclusions The experimental results indicate that the brake pad composite shows improved frictional performance as the applied load increases. The coefficient of friction (COF) rose from 0.697 at 5 N to 0.795 at 30 N, indicating a 14% enhancement. This results from increased surface compaction, enhanced interlocking among asperities, and tribo-film stabilization at elevated stresses. Nonetheless, this augmentation of friction results in heightened wear. The wear rate exhibited a notable increase with load, rising from 0.405 g/N at 5 N to 1.065 g/N at 30 N, indicating a 162.7% escalation. This indicates that while the material can sustain significant friction under load, it becomes increasingly vulnerable to matrix deterioration and microstructural damage, underscoring a compromise between performance and durability. The influence of sliding velocity demonstrated a dual trend: the (COF) rose from 0.663 at 0.4 m/s to 0.797 at 0.8 m/s, reflecting a 20.2% enhancement, presumably attributable to more effective tribo-layer development and increased shear strength at the interface. The wear rate increased from 0.47 to 1.02 g·s/m, or a 116% increase, which indicates enhanced surface softening and particle separation resulting from increasing thermal input at higher velocities. Elevating the rotational speed (RPM) from 100 to 1000 RPM resulted in a steady decrease in the (COF) from 0.44 to 0.156, representing a 64.5% reduction. This is mostly due to thermal softening, diminished mechanical interlocking, and the instability of the friction layer under elevated centrifugal forces. This deterioration emphasizes the RPM sensitivity of the composite, especially during high-speed braking circumstances. SEM micrographs validated a gradual shift in wear processes with varying RPM. At 200 RPM, the surface displayed abrasive wear characterized by micro-cracks, particle extraction, and debris accumulation. At 400 RPM, a smoother surface with a dense tribo-film indicated oxidative and adhesive wear resulting from moderate temperature input. At 800 RPM, the surface exhibited significant adhesive and fatigue wear, characterized by substantial plastic deformation, matrix spreading, and indications of thermal degradation. Hardness testing indicated strain hardening after testing, resulting in enhanced HRC values following tribological exposure. This resulted from localized work-hardening effects induced by frictional heat and cyclic mechanical stress. Reinforcements include SiC, MgO, and 3-mm aramid fibers synergistically enhanced wear resistance, thermal stability, and stress distribution. Abbreviations Symbol / Abbreviation Description Unit / Remarks COF Coefficient of Friction Dimensionless RPM Rotational Speed revolutions per minute (rpm) HRC Rockwell Hardness (C-scale) Hardness unit N Normal Load Newton (N) m Specific Wear Rate g/N or g·s/m SiC Silicon Carbide (reinforcing phase) — MgO Magnesium Oxide (reinforcing filler) — SEM Scanning Electron Microscope Imaging method FESEM Field Emission Scanning Electron Microscope High-resolution imaging LSCM Laser Scanning Confocal Microscopy Surface profiling technique SAE J661 Standard testing procedure for brake materials Society of Automotive Engineers g·s/m Specific wear rate per sliding distance and time grams per second per meter Declarations Author Contributions: Conceptualization, M.A.E., N.M.A. and M.M.F.; Methodology, M.A.E., N.M.A., M.M.F and M.A.; Validation, M.A.E., M.M.F and N.M.A.; Formal analysis, M.A.E., M.A.and M.M.F; Investigation, M.A.E., N.M.A.; Resources, M.A.; Writing—original draft, M.A.E.; Writing—review & editing, N.M.A., M.A.and M.M.F.; Visualization, M.A.E., N.M.A. and M.A.; Supervision, M.A.E., M.A. All authors have read and agreed to the published version of the manuscript. Data Availability: The datasets used and/or analysed during the current study available from the corresponding author on reasonable request. Funding: This research received no external funding. Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: References L. Ma, S. Ding, C. Zhang, Y. Huang, and X. Zhang, "Study on the wear performance of high-speed railway brake materials at low temperatures under continuous braking conditions," Wear, vol. 512, p. 204556, 2023. D. Wei, J. Song, Y. Nan, and W. Zhu, "Analysis of the stick-slip vibration of a new brake pad with double-layer structure in automobile brake system," Mechanical Systems and Signal Processing, vol. 118, pp. 305-316, 2019. M. P. Kshirsagar and H. P. Khairnar, "Comparison of the theoretical and experimental coefficient of friction for the brake disc-brake pad system," Tribol. Mater, vol. 2, pp. 78-87, 2023. S. Gawande, V. Raibhole, and A. Banait, "Study on tribological investigations of alternative automotive brake pad materials," Journal of Bio-and Tribo-Corrosion, vol. 6, pp. 1-10, 2020. S. H. Gawande, A. Banait, and K. Balashowry, "Study on wear analysis of substitute automotive brake pad materials," Australian Journal of Mechanical Engineering, vol. 21, pp. 144-153, 2023. W. Sawczuk, D. Ulbrich, J. Kowalczyk, and A. Merkisz-Guranowska, "Evaluation of wear of disc brake friction linings and the variability of the friction coefficient on the basis of vibroacoustic signals," Sensors, vol. 21, p. 5927, 2021. T. Peng, Q. Yan, X. Zhang, and Y. Zhuang, "Role of titanium carbide and alumina on the friction increment for Cu-based metallic brake pads under different initial braking speeds," Friction, vol. 9, pp. 1543-1557, 2021. U. Idris, V. Aigbodion, I. Abubakar, and C. Nwoye, "Eco-friendly asbestos free brake-pad: Using banana peels," Journal of King Saud University-Engineering Sciences, vol. 27, pp. 185-192, 2015. E. F. EL-kashif, S. A. Esmail, O. A. Elkady, B. Azzam, and A. A. Khattab, "Influence of carbon nanotubes on the properties of friction composite materials," Journal of Composite Materials, vol. 54, pp. 2101-2111, 2020. V. Kalhapure and H. Khairnar, "Taguchi method optimization of operating parameters for automotive disc brake pad wear," Appl. Eng. Lett, vol. 6, pp. 47-53, 2021. P. Gurunath and J. Bijwe, "Friction and wear studies on brake-pad materials based on newly developed resin," Wear, vol. 263, pp. 1212-1219, 2007. W. Sawczuk, A. Merkisz-Guranowska, A.-M. Rilo Cañás, and S. Kołodziejski, "New approach to brake pad wear modelling based on test stand friction-mechanical investigations," Eksploatacja i Niezawodność, vol. 24, 2022. G. Darius, M. Berhan, N. David, A. Shahrul, and M. Zaki, "Characterization of brake pad friction materials," Comput. Methods Exp. Mater. Charact. II, vol. 51, pp. 43-50, 2005. S. Panchenko, J. Gerlici, A. Lovska, V. Ravlyuk, J. Dižo, and M. Blatnický, "Analysis of Asymmetric Wear of Brake Pads on Freight Wagons despite Full Contact between Pad Surface and Wheel," Symmetry, vol. 16, p. 346, 2024. A. P. Irawan, D. F. Fitriyana, C. Tezara, J. P. Siregar, D. Laksmidewi, G. D. Baskara, M. Z. Abdullah, R. Junid, A. E. Hadi, and M. H. M. Hamdan, "Overview of the important factors influencing the performance of eco-friendly brake pads," Polymers, vol. 14, p. 1180, 2022. M. Eriksson and S. Jacobson, "Friction behaviour and squeal generation of disc brakes at low speeds," Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, vol. 215, pp. 1245-1256, 2001. G. Ingo, M. D’uffizi, G. Falso, G. Bultrini, and G. Padeletti, "Thermal and microchemical investigation of automotive brake pad wear residues," Thermochimica acta, vol. 418, pp. 61-68, 2004. V. Raghunathan, G. Sathyamoorthy, V. Ayyappan, R. Srisuk, D. L. Singaravelu, S. M. Rangappa, and S. Siengchin, "Advances in brake friction materials: A comprehensive review of ingredients, processing methods, and performance characteristics," Journal of Vinyl and Additive Technology, vol. 30, pp. 1396-1431, 2024. E. Denimal, J.-J. Sinou, and S. Nacivet, "Prediction of squeal instabilities of a finite element model automotive brake with uncertain structural and environmental parameters with a hybrid surrogate model," Journal of Vibration and Acoustics, vol. 144, p. 021006, 2022. M. P. Kshirsagar and H. Khairnar, "Investigation of Coefficient of Friction at The Interface of Automobile Brake Pads Using Greenwood-Williamson Contact Model and Novel Test Rig," FME Transactions, vol. 50, 2022. B. S. Joo, J. Gweon, J. Park, W. Song, and H. Jang, "The effect of the mechanical property and size of the surface contacts of the brake lining on friction instability," Tribology International, vol. 153, p. 106583, 2021. C. Dong, J. Deng, S. Fan, S. Kou, S. Yang, R. Huang, Y. Zhang, and Y. Mao, "Tribological performance and composition optimization of semi-metallic friction materials applied for carbon ceramic brake disc," Ceramics International, vol. 50, pp. 19660-19670, 2024. G. Sathyamoorthy, R. Vijay, and D. Lenin Singaravelu, "Brake friction composite materials: a review on classifications and influences of friction materials in braking performance with characterizations," Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, vol. 236, pp. 1674-1706, 2022. D. G. Solomon, "Case Studies on Characterization of Brake Pad Surfaces Using Scanning Electron Microscope," Malaysian Journal of Microscopy, vol. 17, 2021. G. Akıncıoğlu, S. Akıncıoğlu, H. Öktem, and İ. Uygur, "Brake pad performance characteristic assessment methods," International Journal of Automotive Science and Technology, vol. 5, pp. 67-78, 2021. H. Yavuz, "Friction, wear, and hardness properties of hybrid vehicle brake pads and effects on brake disc roughness," Materials Testing, vol. 66, pp. 1145-1152, 2024. B. Sugözü and İ. Sugözü, "Examination of the Tribological Properties of Brake Pads with Different Hardness Characteristics," Journal of Current Research on Engineering, vol. 7, pp. 219-224, 2021. M. Mulia, "Comparasion of composition of brake pad hardness and wearness," International Journal of Mechanical Computational and Manufacturing Research, vol. 12, pp. 59-68, 2023. A. Borawski, D. Szpica, G. Mieczkowski, M. M. Awad, R. M. Shalaby, and M. Sallah, "Simulation study of the vehicle braking process with temperature-dependent coefficient of friction between brake pad and disc," Heat Transfer Research, vol. 52, 2021. J. Chen, C. Yu, Q. Cheng, Y. Guan, Q. Zhang, W. Li, F. Ouyang, and Z. Wang, "Research on friction performance and wear rate prediction of high-speed train brake pads," Wear, vol. 514, p. 204564, 2023. M. Kanagaraj, S. Babu, and T. Christy, "The evaluation of friction and wear performances of commercial automotive brake friction polymer composites," Industrial Lubrication and Tribology, vol. 75, pp. 299-304, 2023. M. Naidu, A. Bhosale, Y. Munde, S. Salunkhe, and H. M. A. Hussein, "Wear and friction analysis of brake pad material using natural hemp fibers," Polymers, vol. 15, p. 188, 2022. P. Grzes and M. Kuciej, "Conversion of images of 3D friction maps to study the coupling between coefficient of friction, velocity and contact temperature of the disc brake," Mechanical Systems and Signal Processing, vol. 223, p. 111853, 2025. Z. Xiang, J. Zhang, S. Xie, J. Mo, S. Zhu, and C. Zhai, "Friction-induced vibration and noise characteristics, and interface tribological behavior during high-speed train braking: The effect of the residual height of the brake pad friction block," Wear, vol. 516, p. 204619, 2023. L. Barros, J. C. Poletto, G. Gehlen, G. Lasch, P. D. Neis, A. Ramalho, and N. Ferreira, "Transition in wear regime during braking applications: An analysis of the debris and surfaces of the brake pad and disc," Tribology International, vol. 189, p. 108968, 2023. P. T. Selvam, R. Pugazhenthi, C. Dhanasekaran, M. Chandrasekaran, and S. Sivaganesan, "Experimental investigation on the frictional wear behaviour of TiAlN coated brake pads," Materials Today: Proceedings, vol. 37, pp. 2419-2426, 2021. N. Stojanovic, A. Belhocine, O. I. Abdullah, and I. Grujic, "The influence of the brake pad construction on noise formation, people’s health and reduction measures," Environmental science and pollution research, vol. 30, pp. 15352-15363, 2023. P. D. Kumar and S. D. Gnanaraj, "Comparative tribological study of the material intended for a lightweight HAMNC brake rotor sliding against NAO brake pad material," Engineering Research Express, vol. 6, p. 045514, 2024. Additional Declarations No competing interests reported. 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(b) identified phases highlighting the embedded fiber and magnesium oxide (MgO) particle within the matrix.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/07fb5e01b903807d5aecd0c8.png"},{"id":91156763,"identity":"f1887273-3a03-4e6c-8f23-d1af43b52b33","added_by":"auto","created_at":"2025-09-12 08:15:52","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":92281,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHardness Distribution Before and After Testing Across Selected Points (a) show intersection points of measurements and (b) HRC values\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/45f842ba02eae0041626433d.png"},{"id":91155803,"identity":"80969e0b-f813-4f30-b608-59b31f60937b","added_by":"auto","created_at":"2025-09-12 08:07:52","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":14710,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCOF Behavior Under Different Normal Loads\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage41.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/6ab23d39eab6a09d7dc0746e.png"},{"id":91157784,"identity":"824ca5a7-7576-41a0-b920-21112e16b825","added_by":"auto","created_at":"2025-09-12 08:23:52","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":64937,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRelationship Between Sliding Velocity and Frictional Behavior\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/5f462d8c686f1d874bddfcb1.png"},{"id":91155825,"identity":"32eab2ad-d40a-416f-8af7-f7c2850da05d","added_by":"auto","created_at":"2025-09-12 08:07:52","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":79659,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInfluence of Load on Material Wear Performance\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/d742c909d8bac0e0e752c295.png"},{"id":91157782,"identity":"c4098633-8f8b-4d9d-9d2e-083064499f5e","added_by":"auto","created_at":"2025-09-12 08:23:52","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":86992,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRelationship Between Sliding Velocity and Specific Mass Loss\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/65b2cb1feaed3f4c9f88ae3b.png"},{"id":91157787,"identity":"f1f67ba2-fb4b-42b2-8bca-150086323404","added_by":"auto","created_at":"2025-09-12 08:23:52","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":63294,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFrictional Behavior of Material at Different RPM at 20 N load\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/45bf2d2a437c45d368629cf7.png"},{"id":91156777,"identity":"ec3beeb6-af12-4551-8b48-6b6d1b61c54e","added_by":"auto","created_at":"2025-09-12 08:15:52","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":287103,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM images of the worn surface morphology of a brake disc composite under different rotational speeds: (a) 200 RPM, (b) 400 RPM, and (c) 800 RPM\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/2abc9a2a4dc31add5189ffc0.png"},{"id":100614320,"identity":"943598dc-21f3-4b85-86e7-30b3b944e0cb","added_by":"auto","created_at":"2026-01-19 17:18:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2182591,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7591285/v1/361a2090-6cbc-4f81-b1ae-82d8f961d75b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Experimental Investigation of Friction and Wear in Automotive Brake Pads: The Role of Load and Speed","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe main purpose of braking pad is to transform kinetic energy into thermal energy via friction, therefore reducing or stopping a vehicle's speed [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. This process entails intricate interactions between the brake pad and the disc rotor, which must endure severe circumstances, including high temperatures, substantial pressures, and repetitive mechanical stresses. The tribological properties specifically friction and wear resistance of brake pad materials are crucial for preserving braking efficiency and extending component lifespan [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAsbestos was historically utilized in brake pads because of its superior thermal stability, mechanical strength, and economic efficiency. Nonetheless, owing to its established health risks, including carcinogenic properties, its utilization has been prohibited or limited in numerous nations [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. This has prompted substantial investigation into alternate materials, including non-asbestos organic (NAO) composites, semi-metallic formulations, and ceramic-based pads. These alternatives generally incorporate binders, fillers, friction modifiers, and reinforcements to get optimal performance attributes. Phenolic resins function as high-temperature binders, whilst copper and aramid fibers augment mechanical strength and thermal dissipation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe wear characteristics of brake pads are affected by various operational aspects, such as sliding velocity, applied load, temperature, and the properties of the friction surface. Research, including Gawande et al., indicates that the wear rate escalates with increased applied stress, and materials such as CL3003 demonstrate markedly reduced wear compared to conventional asbestos-based pads under the same testing conditions [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Additionally, the thermal and mechanical properties of brake pads must be refined to mitigate noise, vibration, and particulate emissions, which are significant issues in urban and high-performance settings [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe ongoing progress in materials science and tribology is steering the creation of brake pads that are efficient, robust, and environmentally friendly. The automotive industry is advancing towards elevated safety and emissions regulations, making the selection and optimization of brake pad materials a prominent focus of research and innovation [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e"},{"header":"2. Literature review","content":"\u003cp\u003eThe composition of a standard brake pad has four primary types of components: binders, fillers, reinforcements, and friction modifiers. The binder, often phenolic resin, offers thermal stability and mechanical integrity in high-temperature environments [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Fillers such baryte (BaSO₄), synthetic graphite, and alumina are incorporated to enhance volume, reduce costs, and modify certain characteristics such as compressibility or fade resistance. Reinforcements like copper and iron powders augment structural integrity and heat conductivity. Friction modifiers, such as abrasives and lubricants like silicon carbide and zinc, assist in regulating the (COF) while minimizing noise and vibrations [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eRecent research highlights the tribological characteristics of alternate brake pad materials, evaluating their performance across different loads, sliding velocities, and thermal conditions. Gawande et al. discovered that non-asbestos materials, specifically CL3003, surpassed asbestos in terms of wear resistance and friction stability. Their investigations demonstrated that weight loss in asbestos pads could attain 8\u0026ndash;10%, markedly exceeding that of their non-asbestos equivalents [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eKshirsagar and Khairnar investigated both analytical and experimental assessments of the coefficient of friction in brake disc-pad systems[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Employing the Greenwood-Williamson contact mechanics model and pin-on-disc testing, they documented a coefficient of friction range of 0.2\u0026ndash;0.4, contingent upon load and velocity. Their findings corroborated the model and indicated that material surface roughness and interface pressure significantly affect braking efficiency [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMoreover, recent research has investigated bio-based fillers such as banana peels and carbonized organics as viable eco-friendly alternatives, demonstrating favorable outcomes regarding wear rate and environmental effects [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Researchers also investigate aramid fibers, steel wool, and synthetic rubbers to augment mechanical strength while minimizing noise and particulate emissions [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Metallic ingredients are commonly used in friction materials for automotive braking systems to increase thermal diffusivity, wear resistance and strength [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe (COF) between the brake pad and rotor surface is significantly affected by the applied load. As loads increase, the actual contact area between surfaces expands due to the deformation of asperities, leading to more equal contact and occasionally a reduced (COF) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Sawczuk et al. noted that an increase in pad clamping force resulted in heightened frictional heating, causing softening at the contact surface and a decrease in the (COF) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. For example, at a clamping force of 13 kN, the (COF) was around 0.45; however, it decreased to about 0.38 at 19 kN due to thermally produced lubricious layers and diminished mechanical interlocking at elevated loads [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePanchenko et al. additionally showed that excessive loading diminished the (COF) and led to uneven pad degradation, hence undermining contact uniformity and friction stability over time [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The unequal pressure distribution during load application resulted in stress concentrations, facilitating the premature emergence of thermal cracks and localized delamination [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSliding velocity has a dual impact on the (COF) beginning increments in speed may marginally elevate friction due to enhanced micro-ploughing, whereas extreme velocities generally diminish COF due to thermal effects [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Sawczuk et al. reported that the (COF) decreased from roughly 0.46 at 50 km/h to 0.37 at 200 km/h in a railway disc brake test apparatus [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. This decline is ascribed to the thermal glazing of the pad surface and the loss of mechanical adhesion at elevated velocities [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAbrasive wear rate generally increases with applied load. In the same pin-on-disc tests, the wear volume of the specimen increased from 0.85 mm\u0026sup3; to 1.42 mm\u0026sup3; as the load rose from 30 N to 70 N, indicating higher energy dissipation and micro-cutting mechanisms at elevated loads [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The wear rate (calculated as volume loss per sliding distance) doubled under this load increment, signifying load sensitivity in abrasive conditions.\u003c/p\u003e\u003cp\u003eThis inverse relationship was further corroborated by a mid-band frequency vibration analysis, in which elevated sliding speed diminished signal amplitude due to decreased interfacial friction [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. At elevated velocities, stick-slip transitions diminished, leading to a more stable yet lowered coefficient of friction profile [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe sliding velocity significantly influences the degree of abrasive wear, however the correlation may be non-linear [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. As velocity escalates, surface temperature increases, affecting oxidation and microstructural alterations in the pad material. Sawczuk et al. (2022) indicated that wear escalated with velocity up to 120 km/h, reaching a maximum mass loss of 1.08 g, subsequently decreasing to 0.98 g at 160 km/h, implying the development of protective oxide layers at elevated temperatures [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eRotational speed (RPM), as a proxy for sliding velocity in rotating systems, also impacts the COF. As RPM increases, the surface temperature rises, which often leads to thermal degradation of the contact interface. In a disk brake test, increasing RPM from 300 to 800 led to a decrease in COF from 0.43 to 0.36 due to thermal softening and possible formation of third-body layers [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. However, the effect plateaued beyond 800 RPM, suggesting a dynamic balance between heating and material adaptation [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThis study aims to evaluate the effects of applied load, sliding velocity, and rotational speed on the coefficient of friction and wear rate of a semi-metallic brake pad composite, to optimize braking performance and material durability under varying operating conditions.\u003c/p\u003e"},{"header":"3. Experimental Work","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Braking Pad Friction Materials\u003c/h2\u003e\u003cp\u003eThis study involved the fabrication of semi-metallic brake pad compositions, consisting of thirteen constituents as detailed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, utilizing a powder metallurgy approach. The manufacturing process adhered to a systematic sequence to guarantee optimal material properties and performance. The raw materials were blended in a rotating mixer at 90 rpm for 3 hours to ensure uniform distribution of the ingredients. A backing plate was prepared to ensure a stable substrate for the adhesion of composite materials. The mixed powder was subjected to perform compaction to attain initial densification. A hot compaction process was subsequently conducted using a hydraulic press within a die at a pressure of 20 MPa. In the process of hot compaction, the upper and lower molds were held at temperatures of 168\u0026deg;C and 177\u0026deg;C, respectively, for a duration of 6 minutes to facilitate robust interparticle bonding and improve mechanical integrity.\u003c/p\u003e\u003cp\u003eA post-treatment was conducted at 170\u0026deg;C for 2 hours to enhance the stability of the thermoset matrix, thereby improving its toughness and thermal stability. The fabricated samples underwent a finishing process to enhance their surface and dimensional properties, ensuring adherence to rigorous quality and performance standards. The prototype, referred to as the tested sample, functions as a benchmark for comparative analysis and performance assessment. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents a schematic representation of the manufacturing process.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFormulation of chemical composition for the tested sample of friction material.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"14\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElement\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGraphite\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eWire\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRock wool\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRubber\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eLime\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eBarite\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eVermacult\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eResin\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eZirconium oxide\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eAramid fiber (3mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eSiC\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eMgO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eCoke\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWeight %\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e26.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Microstructure and Hardness Test\u003c/h2\u003e\u003cp\u003eSamples with dimensions the same as those prepared for microscopy were utilized to evaluate the hardness properties of the brake pad specimens. Rockwell C hardness measurements were conducted at room temperature utilizing a Zwick/Roell ZHR hardness tester (ZwickRoell Group, Ulm, Germany) at the Central Metallurgical Research and Development Institute (CMRDI), featuring a diamond indenter and a load of 150 kgf. Testing was performed over an area of 250 mm \u0026times; 150 mm to verify spatial uniformity. The hardness value of each specimen was determined by averaging four independent measurements to ensure statistical reliability.\u003c/p\u003e\u003cp\u003eMicrostructural characterization utilized field emission scanning electron microscopy (FESEM; Carl Zeiss Sigma AG, Oberkochen, Germany) and laser scanning confocal microscopy (LSCM; VK-200, Keyence Ltd., Osaka, Japan). These techniques facilitated a comprehensive evaluation of surface morphology, grain structure, and phase distribution in the brake pad composites. The FESEM analysis yielded high-resolution insights into particle bonding and interfacial integrity, whereas LSCM enabled three-dimensional topographic mapping of the surface. These methodologies clarified essential connections among microstructure, mechanical performance, and compositional homogeneity.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Wear Test\u003c/h2\u003e\u003cp\u003eMeasurements of wear and friction coefficients were performed following the Society of Automotive Engineers (SAE) J661 standard. In the testing phase, the brake pad sample was placed in contact with a rotating brake drum, which operated at incremental rotational velocities of 200, 300, 400, 500, 600, 700, 800, and 1000 rpm as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The test duration facilitated a comprehensive assessment of the material's tribological behavior, including friction and wear characteristics, as well as wear resistance under conditions that simulate real-world automotive applications.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eA pin-on-disc tribometer was utilized for supplemental analysis to measure wear rate and friction coefficient. Specimen pins with specified dimensions (6 mm in diameter and 18 mm in height) were fabricated and affixed to the machine. The testing parameters, such as applied load, sliding speed, and test duration, were meticulously regulated. The pin was applied to the rotating disc under specified conditions, and the instantaneous friction coefficient was documented at 20-second intervals throughout a 20-minute duration. This method guaranteed high-resolution observation of tribological dynamics during the test. All experimental procedures were conducted at the Mechanical Testing and Materials Characterization Laboratory of the at the Central Metallurgical Research and Development Institute (CMRDI), Egypt.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Results and Discussions","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e4.1 Microstructure Examination\u003c/h2\u003e\u003cp\u003eThe supplied SEM micrographs depict the surface morphology of a brake pad composite material at a magnification of 250x. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea presents an overview of the composite, emphasizing the uneven distribution of elements and the occurrence of microstructural flaws, including micro-cracks and voids. These characteristics indicate inhomogeneity within the matrix, perhaps resulting from inadequate mixing or insufficient adhesion between the reinforcement and the matrix. The coarse surface, along with observable fiber pull-outs and fragmented particles, indicates ongoing wear mechanisms, presumably a combination of abrasive and adhesive wear, prevalent in high-friction applications like braking systems [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The uneven configurations and dispersed characteristics of the implanted particles further suggest a multiphase material engineered to endure mechanical forces and thermal fluctuations during braking.\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb offers a detailed view with annotated sections delineating several phases within the composite. A fibrous structure is integrated in the matrix, indicating the reinforcement phase potentially organic or inorganic fibers included to enhance the mechanical strength and toughness of the brake pad. These fibers function to disperse stresses during braking and mitigate crack formation. A bright white inclusion described as magnesium oxide (MgO), a prevalent addition in friction materials, is also noted. Owing to its elevated atomic number, MgO exhibits increased brightness in backscattered electron microscopy and is commonly incorporated to enhance thermal conductivity, wear resistance, and frictional stability [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The well-dispersed presence indicates good integration into the matrix; however, perfect homogeneity may not be attained, as certain places exhibit clustering or uneven distribution.\u003c/p\u003e\u003cp\u003e The composite's microstructure, as depicted in these SEM pictures, demonstrates a purposeful amalgamation of hard particles and fiber reinforcement within a polymer or resin matrix. The observable fissures and delamination in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea may signify areas of inadequate fiber-matrix adhesion, potentially undermining performance under severe thermal and mechanical stresses [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The inclusion of magnesium oxide and fiber in image (b) underscores the material's engineering design intended to optimize strength, frictional performance, and thermal dissipation. The SEM examination indicates that the brake pad sample has the characteristic structural complexity of a reinforced composite material, with microstructural characteristics that significantly affect its tribological performance and operational longevity [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e4.2 Hardness Measurements\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e depicts the Rockwell Hardness (HRC) values of a brake pad formulation consisting of silicon carbide (SiC), 3-mm fibers, and magnesium oxide (MgO), assessed prior to and subsequent to tribological testing. The findings demonstrate a uniform rise in hardness throughout all areas of the material post-testing, signifying strain hardening due to frictional heating and mechanical stress encountered during braking. This behavior exemplifies work-hardening mechanisms typically seen in composite systems, where reinforcing elements like SiC and MgO are pivotal in improving wear resistance and structural integrity [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eBefore testing, the preliminary hardness measurements revealed regional discrepancies, with certain regions displaying reduced HRC values. This fluctuation is likely due to the irregular distribution of fibers and reinforcing particles inside the composite matrix. Subsequent to tribological testing, all assessed locations exhibited a notable and consistent enhancement in hardness, highlighting the material's capacity to endure wear and preserve mechanical performance under cyclic loading circumstances [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe enhancement in post-test hardness can be ascribed to a confluence of synergistic effects. Silicon carbide provides exceptional hardness and resistance to plastic deformation, hence improving the surface durability of the brake pad. Magnesium oxide enhances thermal stability and facilitates grain refinement, hence minimizing microstructural deterioration during high-temperature operation. Furthermore, the 3-mm fiber reinforcements facilitate the uniform distribution of applied stresses across the material, thereby alleviating localized wear and inhibiting crack formation and propagation [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The increase in hardness is associated with microstructural densification and the development of a friction-induced protective tribolayer on the contact surface, indicating the composite's adaptive response to challenging operational conditions. The findings underscore the substantial roles of SiC, MgO, and fiber reinforcement in enhancing the durability and reliability of brake pad materials, rendering this formulation exceptionally appropriate for high-performance braking systems that necessitate prolonged service life and wear resistance [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e4.3 Effect of Applied Load on Coefficient of Friction\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e depicts the behavior of the (COF) for a brake pad composite material subjected to different applied normal loads of 5 N, 10 N, 20 N, and 30 N. The (COF) is an essential metric for assessing braking performance, as it indicates the material's capacity to withstand sliding under pressure; a higher COF typically corresponds to improved braking efficiency. The Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e presents the average COF values along with the associated error bars, indicating the standard deviation or variability in the measured values.\u003c/p\u003e\u003cp\u003eAt a load of 5 N, the composite demonstrates a coefficient of friction of 0.697, indicating the material's initial frictional performance under low contact pressure. This value is classified as moderately high, suggesting that the brake pad surface effectively resists sliding. This effectiveness is likely attributable to factors such as surface roughness, particle interactions, and the initial development of a tribolayer [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. At 10 N, the coefficient of friction decreases marginally to 0.696, indicating negligible change. The observed minor difference indicates stability in contact conditions within this load range, suggesting that the brake pad material can sustain consistent performance under light to moderate loads. The minimal deviation indicates a stable interface, characterized by the absence of excessive wear or smearing at this stage, thereby maintaining the integrity of the contact surface [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eWith an increase in the applied load to 20 N, the (COF) increases markedly to 0.773. The increase indicates a change in the tribological behavior of the material, suggesting that more intense interfacial interactions are occurring. This may result from various phenomena: improved mechanical interlocking of surface asperities, heightened activation of reinforcing particles (e.g., SiC and MgO), and potentially the emergence of mild thermal effects that cause softening or flow of the matrix phase, thereby enhancing adhesion with the counter surface. This behavior indicates that the material transitions to a more effective frictional regime, enhancing its resistance to motion through optimized component engagement [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eUnder the maximum applied load of 30 N, the (COF) attains a maximum value of 0.795, signifying optimal frictional performance across all evaluated conditions. This trend indicates that the brake pad composite exhibits significant pressure sensitivity and reacts favorably to elevated normal loads, likely attributable to surface layer compaction, tribolayer stabilization, and the mitigation of micro-cracking or delamination under prolonged loading conditions [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The development of a stable, protective third-body layer from wear debris may enhance contact adhesion and decrease material loss. This finding is significant for practical braking applications, where materials experience repeated high loads and must reliably provide effective stopping power [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e4.4 Effect of Sliding Velocity on Coefficient of Friction\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e demonstrates the variation of the (COF) for a brake pad composite in relation to sliding velocity, which spans from 0.4 m/s to 0.8 m/s. The data points indicate a clear increasing trend in COF with rising velocity, suggesting enhanced frictional performance at elevated operational speeds. Each data point includes error bars that indicate the variability or uncertainty in the measured values, thereby reflecting the reliability and repeatability of the test [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAt a sliding velocity of 0.4 m/s, the (COF) is recorded at 0.663, representing the lowest value observed throughout the entire test range. The observed lower friction level can be ascribed to relatively mild interfacial contact, restricted thermal activation, and a less developed third-body layer formation. Furthermore, at this velocity, the kinetic energy applied is minimal, potentially resulting in inadequate engagement between the composite constituents and the counter surface, thereby diminishing frictional interaction. The error bar at this velocity is one of the largest, suggesting increased variability in frictional behavior, likely attributable to unstable contact or microstructural inconsistencies [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAt a velocity of 0.5 m/s, the (COF) increases to 0.707, indicating a rise of approximately 6.6% relative to the value at 0.4 m/s. This increase indicates the emergence of a more stable tribological interaction between the brake pad and the sliding surface. The surface temperature at this velocity is likely adequate to induce mild softening or flow of the matrix, resulting in improved surface conformity and enhanced mechanical interlocking.\u003c/p\u003e\u003cp\u003eAt a velocity of 0.6 m/s, the (COF) attains a value of 0.758, representing a 7.2% increase compared to the value at 0.5 m/s. The ongoing upward trend can be linked to a more effective tribo-film formation on the contact surface, as the increase in temperature promotes plastic deformation and compaction of wear debris. This behavior generally leads to enhanced adhesion and shear strength at the interface, thereby increasing friction.\u003c/p\u003e\u003cp\u003eThe maximum (COF) is observed at a sliding velocity of 0.8 m/s, attaining a value of 0.797. This indicates a 20.2% increase relative to the initial coefficient of friction at 0.4 m/s. At this velocity, considerable thermal and mechanical stresses are exerted on the material. The brake pad composite exhibits interfacial stability, attributed to the synergistic effects of reinforcing phases including SiC, MgO, and fiber reinforcement. The microstructure of the composite likely enhances thermal conductivity and structural stability, thereby preventing degradation or smearing of the contact layer, which could otherwise result in reduced friction.\u003c/p\u003e\u003cp\u003eThe COF rises from 0.663 at 0.4 m/s to 0.797 at 0.8 m/s, marking an overall increase of 0.134 units or roughly 20.2%. This clear and consistent enhancement in COF with velocity demonstrates the composite\u0026rsquo;s robust frictional characteristics, its ability to form a stable contact layer, and its suitability for high-speed braking applications. These results support the material's potential in performance-critical systems that require both stability and efficiency under dynamic conditions.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e4.5 Abrasive Wear Based on Applied Load\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e illustrates the correlation between the applied normal load (N) and the specific wear rate of a brake pad composite, represented as m (g/N). The specific wear rate is a crucial parameter in tribological studies, quantifying material loss per unit load and serving as a key indicator for assessing the wear resistance of braking materials under different mechanical stress conditions [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAt a load of 5 N, the wear rate recorded is 0.405 g/N, representing the minimum value observed in the experiment. This indicates that at low contact pressures, the material experiences minimal degradation, probably because of limited heat generation and decreased mechanical disruption at the friction interface. The error bar at this load is minimal, suggesting reliable test outcomes.\u003c/p\u003e\u003cp\u003eWith an increase in load to 10 N, the wear rate approximately doubles, reaching 0.740 g/N. This indicates an estimated increase of 82.7% relative to the wear observed at 5 N. The increase is due to elevated contact stresses, which cause more intense surface abrasion and the onset of microcracks, resulting in increased material removal. The increased wear rate at this stage may indicate the beginning of thermal softening or matrix degradation, which diminishes the composite's resistance to additional wear [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAt a load of 20 N, the wear rate increases to 0.913 g/N, reflecting a 23.4% increase relative to the 10 N scenario. This trend indicates that material loss intensifies as load increases. The frictional heat and pressure may lead to partial degradation of the matrix or fiber-matrix interfaces, thereby diminishing the structural cohesion of the surface layer. The increased wear rate exhibits a slight deceleration, indicating potential surface compaction or the development of a protective third-body layer that intermittently mitigates further wear.\u003c/p\u003e\u003cp\u003eAt a maximum load of 30 N, the wear rate reaches 1.065 g/N, representing the highest value recorded in the study. This indicates a 16.7% increase relative to the 20 N result and a 162.7% increase in comparison to the wear observed at 5 N. The substantial error bar at this load signifies considerable variability in wear behavior, potentially resulting from uneven material removal, localized thermal damage, or inconsistent formation of the third-body layer. The ongoing increase in wear rate with load indicates that the brake pad composite becomes more vulnerable to degradation under higher mechanical stress, notwithstanding potential enhancements in frictional performance, as evidenced by the COF figures.\u003c/p\u003e\u003cp\u003eThe Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e demonstrates a direct correlation between applied load and wear rate, with specific wear increasing from 0.405 g/N at 5 N to 1.065 g/N at 30 N. The data suggests that although the composite may enhance frictional performance under elevated loads, this improvement is accompanied by greater material loss. The trade-off between friction and wear is a crucial factor in brake pad design. Optimizing material composition, including the balance of reinforcement content and matrix stability, is vital for ensuring long-term performance and durability in high-stress braking applications [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e4.6 Abrasive Wear Based on Sliding Velocity\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e illustrates the correlation between sliding velocity (m/s) and the specific wear rate of a brake pad composite, quantified in grams per second per meter (g\u0026middot;s/m). The x-axis represents sliding velocity, varying from 0.4 m/s to 0.8 m/s, while the y-axis displays the specific wear rate values, quantitatively measuring material loss due to frictional motion at these velocities. The data incorporate error bars that indicate the experimental variability or standard deviation for each velocity measurement.\u003c/p\u003e\u003cp\u003eAt a velocity of 0.4 m/s, the specific wear rate is 0.47 g\u0026middot;s/m, representing the minimum value observed in this dataset. This indicates that at reduced sliding speeds, the brake pad surface experiences comparatively mild abrasion. Reduced frictional heat and diminished mechanical interaction between contact surfaces likely lead to a decrease in material detachment. This value demonstrates a minimal error bar, reflecting significant consistency and stability in the measurements at this velocity [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eWith an increase in sliding velocity to 0.5 m/s, the wear rate escalates to 0.62 g\u0026middot;s/m, reflecting an approximate increase of 31.9% relative to the wear rate at 0.4 m/s. The increase is due to enhanced surface interactions and the initiation of more severe micro-abrasive and fatigue wear. The rise in velocity results in enhanced frictional energy conversion into heat, which induces localized softening of the matrix and may expedite the removal of worn particles.\u003c/p\u003e\u003cp\u003eAt a velocity of 0.6 m/s, the specific wear rate increases, attaining a value of 0.721 g\u0026middot;s/m. This indicates a 16.3% increase relative to the value at 0.5 m/s, implying a steady advancement in wear severity. The moderate error bar indicates stable yet somewhat variable test conditions, likely resulting from dynamic changes at the friction interface, including the formation or disruption of tribological films.\u003c/p\u003e\u003cp\u003eThe maximum wear rate occurs at 0.8 m/s, recorded at 1.02 g\u0026middot;s/m, representing a 116% increase compared to the wear rate at 0.4 m/s. The notable increase indicates that high-speed sliding markedly enhances material loss. At this velocity, significant frictional heating occurs, potentially resulting in thermal degradation of the matrix and the failure of fiber\u0026ndash;matrix bonding. The potential for thermal softening and oxidation increases, leading to the formation of unstable third-body layers and the generation of loose debris, which exacerbates wear [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e4.7 Effect of Different RPM on Coefficient of Friction\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e demonstrates the relationship between rotational speed (RPM) and the (COF) for a brake pad composite. At a low speed of 100 RPM, the (COF) is 0.44, representing the maximum value recorded in the dataset. This indicates that at low-speed operation, the composite surface retains effective interfacial grip, probably owing to reduced heat generation and minimal surface softening or degradation.\u003c/p\u003e\u003cp\u003eAt an RPM of 200, the (COF) decreases marginally to 0.398, indicating a reduction of 9.5%. This suggests the onset of a declining trend, potentially attributable to initial thermal effects and alterations in the wear surface morphology, which begin to diminish the adhesion between the mating surfaces [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAs the speed increases to 400 RPM, the (COF) declines significantly, reaching a value of 0.31. This represents a 22.1% decrease from the initial coefficient of friction at 100 RPM, indicating that frictional heating intensifies, leading to the softening or weakening of the tribological film, which subsequently diminishes braking efficiency [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAt 500 RPM, the decrease to 0.289, maintaining the observed downward trend. This trend is particularly evident at 600 RPM, where the (COF) decreases to 0.215, reflecting a 51.1% reduction from the initial COF measured at 100 RPM. The significant decrease may result from a failure in surface integrity, leading to reduced surface resistance and diminished contact efficacy between the pad and the rotating surface.\u003c/p\u003e\u003cp\u003eAt 700 RPM, the (COF) increases slightly to 0.221, indicating a minor rebound effect. This may result from a temporary reformation of a tribolayer or a more stable compaction of wear particles at this speed, which temporarily enhances surface interaction. This increase is marginal and not sustained.\u003c/p\u003e\u003cp\u003eAt 800 RPM, the (COF) decreases to 0.19, and at the maximum tested speed of 1000 RPM, the COF attains its lowest value of 0.156, reflecting a 64.5% reduction from the value observed at 100 RPM. At elevated speeds, the surface is likely to undergo considerable thermal degradation, potential smearing of matrix material, and a reduction in mechanical interlocking, all of which contribute to decreased friction.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003e4.8 Worn Surface Morphology of Brake Pad Materials at Varying Rotational Speeds\u003c/h2\u003e\u003cp\u003eThe SEM micrographs presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e offer a comparative analysis of the worn surface morphology of a brake pad composite at different rotational speeds: (a) 200 RPM, (b) 400 RPM, and (c) 800 RPM. All images are captured at 1000\u0026times; magnification, featuring a scale bar of 100 \u0026micro;m, which facilitates a detailed examination of the tribological behavior under varying dynamic conditions. The observations indicate distinct differences in wear mechanisms and surface evolution with increasing RPM [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ea illustrates the worn surface at 200 RPM, characterized by a rough and heterogeneous morphology. The presence of sharp-edged reinforcement particles, some of which are partially extracted, in conjunction with grooves and micro-cracks, indicates that abrasive wear predominates at this low speed. The irregular distribution of wear debris and the absence of a continuous tribo-film suggest restricted thermal activation and mechanical energy input. The wear debris exhibits loose adhesion, and the lack of smeared areas indicates limited plastic deformation. The microstructure largely preserves its original characteristics, indicating mild wear accompanied by localized material detachment, likely caused by contact fatigue and mechanical interlocking among asperities [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eConversely, Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eb depicts the worn surface at 400 RPM, showing a markedly smoother and more compacted appearance. The wear track exhibits reduced particle pull-out and a lower incidence of cracks, along with the development of a more uniform and densified tribo-layer. This morphological transition indicates a change from abrasive to oxidative and adhesive wear mechanisms, facilitated by heightened frictional heat generation at this intermediate speed. The matrix phase seems to have initiated softening, which facilitates the smearing and bonding of fine wear debris into a semi-continuous protective layer. A tribological film protects the surface from additional damage and enhances the stability of the frictional interface. The wear is reduced in severity but increased in uniformity, indicating enhanced energy dissipation and a more stable sliding regime.\u003c/p\u003e\u003cp\u003eAt 800 RPM, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ec, the surface morphology undergoes significant alterations, characterized by dense smearing, plastic flow, and pronounced structural deformation. The matrix exhibits significant softening, and the wear debris is consolidated into large, unstable agglomerates. Evidence of melting or thermal degradation is apparent, particularly in darker regions, indicating the significant heat produced at this elevated rotational speed. The distribution of reinforcement particles becomes unclear, as numerous particles are incorporated within the plastically deformed matrix. This suggests a prevalence of severe adhesive and fatigue wear, along with potential thermal wear mechanisms. The tribo-layer exhibits instability and may undergo delamination, leading to expedited surface failure. The wear observed at 800 RPM is the most pronounced, exhibiting evident surface deterioration, material flow, and a compromise of the composite's structural integrity.\u003c/p\u003e\u003cp\u003eThe transition from 200 to 800 RPM indicates a shift in wear behavior from mechanical abrasion to thermo-mechanical deformation and fatigue. At 200 RPM, wear is minimal and localized; at 400 RPM, the surface shows the formation of a protective tribo-film; and at 800 RPM, the surface experiences significant damage from excessive thermal and mechanical stress [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. The findings underscore the significance of choosing operational speeds that enhance both friction and wear resistance in braking systems.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe experimental results indicate that the brake pad composite shows improved frictional performance as the applied load increases. The coefficient of friction (COF) rose from 0.697 at 5 N to 0.795 at 30 N, indicating a 14% enhancement. This results from increased surface compaction, enhanced interlocking among asperities, and tribo-film stabilization at elevated stresses. Nonetheless, this augmentation of friction results in heightened wear.\u003c/p\u003e\u003cp\u003eThe wear rate exhibited a notable increase with load, rising from 0.405 g/N at 5 N to 1.065 g/N at 30 N, indicating a 162.7% escalation. This indicates that while the material can sustain significant friction under load, it becomes increasingly vulnerable to matrix deterioration and microstructural damage, underscoring a compromise between performance and durability.\u003c/p\u003e\u003cp\u003eThe influence of sliding velocity demonstrated a dual trend: the (COF) rose from 0.663 at 0.4 m/s to 0.797 at 0.8 m/s, reflecting a 20.2% enhancement, presumably attributable to more effective tribo-layer development and increased shear strength at the interface. The wear rate increased from 0.47 to 1.02 g·s/m, or a 116% increase, which indicates enhanced surface softening and particle separation resulting from increasing thermal input at higher velocities.\u003c/p\u003e\u003cp\u003eElevating the rotational speed (RPM) from 100 to 1000 RPM resulted in a steady decrease in the (COF) from 0.44 to 0.156, representing a 64.5% reduction. This is mostly due to thermal softening, diminished mechanical interlocking, and the instability of the friction layer under elevated centrifugal forces. This deterioration emphasizes the RPM sensitivity of the composite, especially during high-speed braking circumstances.\u003c/p\u003e\u003cp\u003eSEM micrographs validated a gradual shift in wear processes with varying RPM. At 200 RPM, the surface displayed abrasive wear characterized by micro-cracks, particle extraction, and debris accumulation. At 400 RPM, a smoother surface with a dense tribo-film indicated oxidative and adhesive wear resulting from moderate temperature input. At 800 RPM, the surface exhibited significant adhesive and fatigue wear, characterized by substantial plastic deformation, matrix spreading, and indications of thermal degradation.\u003c/p\u003e\u003cp\u003eHardness testing indicated strain hardening after testing, resulting in enhanced HRC values following tribological exposure. This resulted from localized work-hardening effects induced by frictional heat and cyclic mechanical stress. Reinforcements include SiC, MgO, and 3-mm aramid fibers synergistically enhanced wear resistance, thermal stability, and stress distribution.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSymbol / Abbreviation\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDescription\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUnit / Remarks\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCOF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCoefficient of Friction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDimensionless\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRPM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRotational Speed\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003erevolutions per minute (rpm)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHRC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRockwell Hardness (C-scale)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHardness unit\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal Load\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNewton (N)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003em\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSpecific Wear Rate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eg/N or g·s/m\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSiC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSilicon Carbide (reinforcing phase)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e—\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMgO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMagnesium Oxide (reinforcing filler)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e—\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSEM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eScanning Electron Microscope\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eImaging method\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFESEM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eField Emission Scanning Electron Microscope\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHigh-resolution imaging\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLSCM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLaser Scanning Confocal Microscopy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSurface profiling technique\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSAE J661\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eStandard testing procedure for brake materials\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSociety of Automotive Engineers\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eg·s/m\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSpecific wear rate per sliding distance and time\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003egrams per second per meter\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u0026nbsp;Author Contributions: Conceptualization, M.A.E., N.M.A. and M.M.F.; Methodology, M.A.E., N.M.A., M.M.F and M.A.; Validation, M.A.E., M.M.F and N.M.A.; Formal analysis, M.A.E., M.A.and M.M.F; Investigation, M.A.E., N.M.A.; Resources, M.A.; Writing\u0026mdash;original draft, M.A.E.; Writing\u0026mdash;review \u0026amp; editing, N.M.A., M.A.and M.M.F.; Visualization, M.A.E., N.M.A. and M.A.; Supervision, M.A.E., M.A. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003eData Availability: The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eFunding: This research received no external funding.\u003c/p\u003e\n\u003cp\u003eDeclaration of interests\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003eThe authors declare the following financial interests/personal relationships which may be considered as potential competing interests:\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eL. Ma, S. Ding, C. Zhang, Y. Huang, and X. Zhang, \u0026quot;Study on the wear performance of high-speed railway brake materials at low temperatures under continuous braking conditions,\u0026quot; Wear, vol. 512, p. 204556, 2023.\u003c/li\u003e\n\u003cli\u003eD. Wei, J. Song, Y. Nan, and W. Zhu, \u0026quot;Analysis of the stick-slip vibration of a new brake pad with double-layer structure in automobile brake system,\u0026quot; Mechanical Systems and Signal Processing, vol. 118, pp. 305-316, 2019.\u003c/li\u003e\n\u003cli\u003eM. P. Kshirsagar and H. P. Khairnar, \u0026quot;Comparison of the theoretical and experimental coefficient of friction for the brake disc-brake pad system,\u0026quot; Tribol. Mater, vol. 2, pp. 78-87, 2023.\u003c/li\u003e\n\u003cli\u003eS. Gawande, V. Raibhole, and A. Banait, \u0026quot;Study on tribological investigations of alternative automotive brake pad materials,\u0026quot; Journal of Bio-and Tribo-Corrosion, vol. 6, pp. 1-10, 2020.\u003c/li\u003e\n\u003cli\u003eS. H. Gawande, A. Banait, and K. Balashowry, \u0026quot;Study on wear analysis of substitute automotive brake pad materials,\u0026quot; Australian Journal of Mechanical Engineering, vol. 21, pp. 144-153, 2023.\u003c/li\u003e\n\u003cli\u003eW. Sawczuk, D. Ulbrich, J. Kowalczyk, and A. Merkisz-Guranowska, \u0026quot;Evaluation of wear of disc brake friction linings and the variability of the friction coefficient on the basis of vibroacoustic signals,\u0026quot; Sensors, vol. 21, p. 5927, 2021.\u003c/li\u003e\n\u003cli\u003eT. Peng, Q. Yan, X. Zhang, and Y. Zhuang, \u0026quot;Role of titanium carbide and alumina on the friction increment for Cu-based metallic brake pads under different initial braking speeds,\u0026quot; Friction, vol. 9, pp. 1543-1557, 2021.\u003c/li\u003e\n\u003cli\u003eU. Idris, V. Aigbodion, I. Abubakar, and C. Nwoye, \u0026quot;Eco-friendly asbestos free brake-pad: Using banana peels,\u0026quot; Journal of King Saud University-Engineering Sciences, vol. 27, pp. 185-192, 2015.\u003c/li\u003e\n\u003cli\u003eE. F. EL-kashif, S. A. Esmail, O. A. Elkady, B. Azzam, and A. A. Khattab, \u0026quot;Influence of carbon nanotubes on the properties of friction composite materials,\u0026quot; Journal of Composite Materials, vol. 54, pp. 2101-2111, 2020.\u003c/li\u003e\n\u003cli\u003eV. Kalhapure and H. Khairnar, \u0026quot;Taguchi method optimization of operating parameters for automotive disc brake pad wear,\u0026quot; Appl. Eng. Lett, vol. 6, pp. 47-53, 2021.\u003c/li\u003e\n\u003cli\u003eP. Gurunath and J. Bijwe, \u0026quot;Friction and wear studies on brake-pad materials based on newly developed resin,\u0026quot; Wear, vol. 263, pp. 1212-1219, 2007.\u003c/li\u003e\n\u003cli\u003eW. Sawczuk, A. Merkisz-Guranowska, A.-M. Rilo Ca\u0026ntilde;\u0026aacute;s, and S. Kołodziejski, \u0026quot;New approach to brake pad wear modelling based on test stand friction-mechanical investigations,\u0026quot; Eksploatacja i Niezawodność, vol. 24, 2022.\u003c/li\u003e\n\u003cli\u003eG. Darius, M. Berhan, N. David, A. Shahrul, and M. Zaki, \u0026quot;Characterization of brake pad friction materials,\u0026quot; Comput. Methods Exp. Mater. Charact. II, vol. 51, pp. 43-50, 2005.\u003c/li\u003e\n\u003cli\u003eS. Panchenko, J. Gerlici, A. Lovska, V. Ravlyuk, J. Dižo, and M. Blatnick\u0026yacute;, \u0026quot;Analysis of Asymmetric Wear of Brake Pads on Freight Wagons despite Full Contact between Pad Surface and Wheel,\u0026quot; Symmetry, vol. 16, p. 346, 2024.\u003c/li\u003e\n\u003cli\u003eA. P. Irawan, D. F. Fitriyana, C. Tezara, J. P. Siregar, D. Laksmidewi, G. D. Baskara, M. Z. Abdullah, R. Junid, A. E. Hadi, and M. H. M. Hamdan, \u0026quot;Overview of the important factors influencing the performance of eco-friendly brake pads,\u0026quot; Polymers, vol. 14, p. 1180, 2022.\u003c/li\u003e\n\u003cli\u003eM. Eriksson and S. Jacobson, \u0026quot;Friction behaviour and squeal generation of disc brakes at low speeds,\u0026quot; Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, vol. 215, pp. 1245-1256, 2001.\u003c/li\u003e\n\u003cli\u003eG. Ingo, M. D\u0026rsquo;uffizi, G. Falso, G. Bultrini, and G. Padeletti, \u0026quot;Thermal and microchemical investigation of automotive brake pad wear residues,\u0026quot; Thermochimica acta, vol. 418, pp. 61-68, 2004.\u003c/li\u003e\n\u003cli\u003eV. Raghunathan, G. Sathyamoorthy, V. Ayyappan, R. Srisuk, D. L. Singaravelu, S. M. Rangappa, and S. Siengchin, \u0026quot;Advances in brake friction materials: A comprehensive review of ingredients, processing methods, and performance characteristics,\u0026quot; Journal of Vinyl and Additive Technology, vol. 30, pp. 1396-1431, 2024.\u003c/li\u003e\n\u003cli\u003eE. Denimal, J.-J. Sinou, and S. Nacivet, \u0026quot;Prediction of squeal instabilities of a finite element model automotive brake with uncertain structural and environmental parameters with a hybrid surrogate model,\u0026quot; Journal of Vibration and Acoustics, vol. 144, p. 021006, 2022.\u003c/li\u003e\n\u003cli\u003eM. P. Kshirsagar and H. Khairnar, \u0026quot;Investigation of Coefficient of Friction at The Interface of Automobile Brake Pads Using Greenwood-Williamson Contact Model and Novel Test Rig,\u0026quot; FME Transactions, vol. 50, 2022.\u003c/li\u003e\n\u003cli\u003eB. S. Joo, J. Gweon, J. Park, W. Song, and H. Jang, \u0026quot;The effect of the mechanical property and size of the surface contacts of the brake lining on friction instability,\u0026quot; Tribology International, vol. 153, p. 106583, 2021.\u003c/li\u003e\n\u003cli\u003eC. Dong, J. Deng, S. Fan, S. Kou, S. Yang, R. Huang, Y. Zhang, and Y. Mao, \u0026quot;Tribological performance and composition optimization of semi-metallic friction materials applied for carbon ceramic brake disc,\u0026quot; Ceramics International, vol. 50, pp. 19660-19670, 2024.\u003c/li\u003e\n\u003cli\u003eG. Sathyamoorthy, R. Vijay, and D. Lenin Singaravelu, \u0026quot;Brake friction composite materials: a review on classifications and influences of friction materials in braking performance with characterizations,\u0026quot; Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, vol. 236, pp. 1674-1706, 2022.\u003c/li\u003e\n\u003cli\u003eD. G. Solomon, \u0026quot;Case Studies on Characterization of Brake Pad Surfaces Using Scanning Electron Microscope,\u0026quot; Malaysian Journal of Microscopy, vol. 17, 2021.\u003c/li\u003e\n\u003cli\u003eG. Akıncıoğlu, S. Akıncıoğlu, H. \u0026Ouml;ktem, and İ. Uygur, \u0026quot;Brake pad performance characteristic assessment methods,\u0026quot; International Journal of Automotive Science and Technology, vol. 5, pp. 67-78, 2021.\u003c/li\u003e\n\u003cli\u003eH. Yavuz, \u0026quot;Friction, wear, and hardness properties of hybrid vehicle brake pads and effects on brake disc roughness,\u0026quot; Materials Testing, vol. 66, pp. 1145-1152, 2024.\u003c/li\u003e\n\u003cli\u003eB. Sug\u0026ouml;z\u0026uuml; and İ. Sug\u0026ouml;z\u0026uuml;, \u0026quot;Examination of the Tribological Properties of Brake Pads with Different Hardness Characteristics,\u0026quot; Journal of Current Research on Engineering, vol. 7, pp. 219-224, 2021.\u003c/li\u003e\n\u003cli\u003eM. Mulia, \u0026quot;Comparasion of composition of brake pad hardness and wearness,\u0026quot; International Journal of Mechanical Computational and Manufacturing Research, vol. 12, pp. 59-68, 2023.\u003c/li\u003e\n\u003cli\u003eA. Borawski, D. Szpica, G. Mieczkowski, M. M. Awad, R. M. Shalaby, and M. Sallah, \u0026quot;Simulation study of the vehicle braking process with temperature-dependent coefficient of friction between brake pad and disc,\u0026quot; Heat Transfer Research, vol. 52, 2021.\u003c/li\u003e\n\u003cli\u003eJ. Chen, C. Yu, Q. Cheng, Y. Guan, Q. Zhang, W. Li, F. Ouyang, and Z. Wang, \u0026quot;Research on friction performance and wear rate prediction of high-speed train brake pads,\u0026quot; Wear, vol. 514, p. 204564, 2023.\u003c/li\u003e\n\u003cli\u003eM. Kanagaraj, S. Babu, and T. Christy, \u0026quot;The evaluation of friction and wear performances of commercial automotive brake friction polymer composites,\u0026quot; Industrial Lubrication and Tribology, vol. 75, pp. 299-304, 2023.\u003c/li\u003e\n\u003cli\u003eM. Naidu, A. Bhosale, Y. Munde, S. Salunkhe, and H. M. A. Hussein, \u0026quot;Wear and friction analysis of brake pad material using natural hemp fibers,\u0026quot; Polymers, vol. 15, p. 188, 2022.\u003c/li\u003e\n\u003cli\u003eP. Grzes and M. Kuciej, \u0026quot;Conversion of images of 3D friction maps to study the coupling between coefficient of friction, velocity and contact temperature of the disc brake,\u0026quot; Mechanical Systems and Signal Processing, vol. 223, p. 111853, 2025.\u003c/li\u003e\n\u003cli\u003eZ. Xiang, J. Zhang, S. Xie, J. Mo, S. Zhu, and C. Zhai, \u0026quot;Friction-induced vibration and noise characteristics, and interface tribological behavior during high-speed train braking: The effect of the residual height of the brake pad friction block,\u0026quot; Wear, vol. 516, p. 204619, 2023.\u003c/li\u003e\n\u003cli\u003eL. Barros, J. C. Poletto, G. Gehlen, G. Lasch, P. D. Neis, A. Ramalho, and N. Ferreira, \u0026quot;Transition in wear regime during braking applications: An analysis of the debris and surfaces of the brake pad and disc,\u0026quot; Tribology International, vol. 189, p. 108968, 2023.\u003c/li\u003e\n\u003cli\u003eP. T. Selvam, R. Pugazhenthi, C. Dhanasekaran, M. Chandrasekaran, and S. Sivaganesan, \u0026quot;Experimental investigation on the frictional wear behaviour of TiAlN coated brake pads,\u0026quot; Materials Today: Proceedings, vol. 37, pp. 2419-2426, 2021.\u003c/li\u003e\n\u003cli\u003eN. Stojanovic, A. Belhocine, O. I. Abdullah, and I. Grujic, \u0026quot;The influence of the brake pad construction on noise formation, people\u0026rsquo;s health and reduction measures,\u0026quot; Environmental science and pollution research, vol. 30, pp. 15352-15363, 2023.\u003c/li\u003e\n\u003cli\u003eP. D. Kumar and S. D. Gnanaraj, \u0026quot;Comparative tribological study of the material intended for a lightweight HAMNC brake rotor sliding against NAO brake pad material,\u0026quot; Engineering Research Express, vol. 6, p. 045514, 2024.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Braking pads, Coefficient of Friction, Abrasive Wear, Sliding Velocity, Friction Materials","lastPublishedDoi":"10.21203/rs.3.rs-7591285/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7591285/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study examines the frictional and abrasive wear characteristics of a semi-metallic brake pad composite under different applied loads, sliding velocities, and rotating speeds. The brake pad, consisting of 13 components including SiC, MgO, and 3-mm aramid fibers, was produced by powder metallurgy and assessed according to SAE J661 standard standards. The results indicated that the coefficient of friction (COF) rose from 0.697 at 5 N to 0.795 at 30 N, signifying enhanced interfacial resistance attributable to surface compaction and tribo-film stabilization. The specific wear rate increased with load, from 0.405 g/N at 5 N to 1.065 g/N at 30 N, indicating a compromise between friction and wear resistance. The sliding velocity demonstrated a dual effect: the (COF) rose from 0.663 at 0.4 m/s to 0.797 at 0.8 m/s, while the wear rate climbed from 0.47 g\u0026middot;s/m to 1.02 g\u0026middot;s/m, representing a 116% escalation. Increasing the RPM from 100 to 1000 resulted in a significant 64.5% reduction in the (COF), decreasing from 0.44 to 0.156, attributable to heat softening and surface deterioration. SEM research indicated a change in wear mechanisms from abrasive at 200 RPM to oxidative at 400 RPM, and severe adhesive wear at 800 RPM. These findings underscore the necessity of improving operational circumstances to reconcile friction performance with material durability in high-speed braking systems.\u003c/p\u003e","manuscriptTitle":"Experimental Investigation of Friction and Wear in Automotive Brake Pads: The Role of Load and Speed","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 08:07:47","doi":"10.21203/rs.3.rs-7591285/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-12T19:28:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-09T06:49:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-04T20:19:55+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-28T16:53:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"95578229033429204210642513367931974279","date":"2025-09-19T10:01:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"140867040329251006846022404946762955067","date":"2025-09-18T07:14:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"245523236577302407467671604076824190957","date":"2025-09-18T00:50:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"144269086581386591791803990188502183140","date":"2025-09-17T07:58:49+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-17T05:18:46+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-17T05:10:21+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-15T06:11:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-12T14:26:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-09-11T11:09:40+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ee697998-baac-4e68-81a7-dcaabb9853e8","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":54564555,"name":"Physical sciences/Engineering"},{"id":54564556,"name":"Physical sciences/Materials science"}],"tags":[],"updatedAt":"2026-01-19T16:44:21+00:00","versionOfRecord":{"articleIdentity":"rs-7591285","link":"https://doi.org/10.1038/s41598-025-33326-7","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-01-13 16:28:34","publishedOnDateReadable":"January 13th, 2026"},"versionCreatedAt":"2025-09-12 08:07:47","video":"","vorDoi":"10.1038/s41598-025-33326-7","vorDoiUrl":"https://doi.org/10.1038/s41598-025-33326-7","workflowStages":[]},"version":"v1","identity":"rs-7591285","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7591285","identity":"rs-7591285","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}