Laser surface modification of Al 2 O 3 / CYSZ functionally graded TBC against CMAS and hot corrosion damage

Laser surface modification of Al 2 O 3 / CYSZ functionally graded TBC against CMAS and hot corrosion damage | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Laser surface modification of Al 2 O 3 / CYSZ functionally graded TBC against CMAS and hot corrosion damage Fatih Kirbiyik This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6040852/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Oct, 2025 Read the published version in Lasers in Manufacturing and Materials Processing → Version 1 posted 12 You are reading this latest preprint version Abstract This study investigates the effects of laser surface modification on the corrosion resistance and thermal performance of thermal barrier coatings (TBCs) exposed to calcium-magnesium-aluminosilicate (CMAS) and hot corrosion environments. Two TBC designs, single-layered ceria-yttria-stabilized zirconia (CYSZ) and a functionally graded Al2O3/CYSZ (FG) structure, were investigated through thermal gradient and thermal cycling tests at 1200 °C. Laser surface modification significantly improved the microstructure and mechanical properties, including a twofold increase in microhardness for CYSZ and a fourfold increase for the FG design. The modified surfaces showed improved resistance to CMAS penetration and hot corrosion salts, with reduced tetragonal to monoclinic phase transformation and improved phase stability. Microstructural analysis revealed stress-induced delamination in CYSZ due to CMAS infiltration, while FG TBCs exhibited better performance with minimal coating failure and improved thermal expansion compatibility. After modification, both designs maintained high durability, withstanding up to 100 thermal cycles without significant delamination. The results highlight the superior corrosion resistance and thermal stability of laser surface modified FG TBCs, demonstrating their potential for extended life in high temperature applications. Laser surface modification TBC Al2O3 CYSZ Thermal test Figures Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction The service life of thermal barrier coatings (TBCs) is typically limited to shear due to oxidative stress between the ceramic layer and the bond layer. Morphological instability or "wrinkling" has been identified as one of the dissociation mechanisms between the thermally growing oxide layer (TGO) and the TBC. In addition to the thermal coefficient of expansion (CTE) mismatch between the ceramic TBC and a metallic substrate, damage can also occur as a result of the concentration of non-engine contaminants that accumulate on the TBC surface and penetrate the TBC structure during gas turbine engine operation. Notable components of these contaminants include calcium-magnesium-aluminum-silicon oxides (CaO - MgO -Al2O3 -SiO2), referred to as CMAS, and hot corrosion fuel impurities (NaSO4, NaCl, and V2O5). Depending on the environment, CMAS may also contain small amounts of oxides of elements such as Ni, Fe, Ti, and Cr. This material has a relatively low eutectic melting point, ranging from 1190 to 1260°C, which varies depending on its composition. The melting temperature of CMAS can be further reduced by the presence of multiple components and modifying elements such as sodium. As CMAS melts, it wets the outer YSZ (TBC) layer and infiltrates the inner porous structure. This infiltration reduces the porosity and disrupts the columnar architecture, resulting in an increase in the Young's modulus of the TBC. As a result, the reduced strain tolerance and mismatch in coefficient of thermal expansion (CTE) between the CMAS and TBC causes fragmentation, ultimately compromising the thermal protection of the underlying metal component [1,2]. In recent years, considerable effort has been devoted to developing methods to combat CMAS corrosion. Two main approaches have shown promising results. The first involves the use of impermeable and non-wetting materials, while the second focuses on modifying TBC compositions to react rapidly with CMAS to form a dense protective layer. This reaction requires a fast reaction rate, high melting point, and dense reaction products. However, these methods have certain drawbacks. Impermeable or non-wetting materials may not be suitable as stand-alone TBCs, and candidate materials that facilitate crystallization often face significant application challenges due to their relatively poor mechanical properties [3,4]. Consequently, there is a need for practical, cost-effective and user-friendly solutions. One promising approach is the design of pavement-like structures, with laser modification of TBC surface structures emerging as an effective method to enhance resistance to CMAS corrosion. Many researchers have investigated [3,4] that laser-based surface modification results in the formation of TBCs with a more compact and refined surface. This altered morphology effectively protects against the infiltration of hot corrosion melts into the coating. Unwanted fuel contaminants accumulate on the TBC surface during high-temperature service. These contaminants interact with the coating at high temperatures, causing degradation, cracking, or disintegration. This damage mechanism, known as hot corrosion, occurs when molten salts penetrate through microcracks and pores in the topcoat. Under hot corrosion service conditions, elements such as sodium, vanadium and lead change the chemical structure of the coating. When elements such as sodium, sulfur, phosphorus, and vanadium from fuel contamination are present in the structure, they react with the Y2O3 phase and cause its depletion. In the absence of the Y2O3 phase, a tetragonal-monoclinic phase transformation occurs. Stabilization of the tetragonal ZrO2 phase is no longer possible. This transformation can result in a volume change that compromises the integrity of the surface layer. Corrosion mechanisms triggered by poor quality fuel or adverse operating conditions further weaken the surface layer and lead to damage. Hot corrosion begins with the accumulation of high melting point salts on the metal surface. Typically, after the reaction of SO 3 and NaCl, a salt deposit of Na2SO4 and hot corrosion salts is formed on the coating surface. Reactions 1 and 2 proceed according to the hot corrosion damage mechanism. 2NaCl + SO 3 + H 2 O→Na 2 SO 4 + 2HCl (g) (1) 4NaCl + 2SO 2 + 2H 2 O + O 2 →2Na 2 SO 4 + 4HCl (2) Hot corrosion is a form of deterioration caused by the presence of salts such as Na₂SO₄, NaCl, and V₂O₅. These salts, either individually or in combination, can cause corrosion at high temperatures. The mechanism of hot corrosion is classified into two types based on the temperature range and the nature of the corrosion process. Type I is high-temperature hot corrosion and type II is low-temperature hot corrosion. The progression of these two types of hot corrosion can be influenced by several factors, including alloy composition, thermomechanical state, contaminant composition, flow rate, temperature and thermal cycling, gas composition, and erosion. The demanding performance and durability standards of gas turbine engines in the aerospace and automotive industries require the use of advanced, next-generation thermal barrier coatings (TBCs). To meet these needs, numerous TBC materials have been developed with low thermal conductivity, high temperature resistance, and excellent corrosion resistance. However, even TBC materials with high thermal conductivity and superior phase stability are exposed to various corrosive environments due to the use of low-grade fuels. These TBCs are specifically designed to function effectively in highly corrosive operating conditions. In TBCs, high-temperature corrosion is typically caused by mixtures of Na2SO4 and V2O5 molten salts. Especially in TBCs with YSZ topcoat, the mixture of V2O5 and Na2SO4 salt reacts with the topcoat at high temperatures to form the following equations (Equations 3, 4 and 5). According to these equations, the topcoat is monoclinic. It consists of zirconia and YVO 4 structures. The formation of these new hot corrosion products leads to volume expansion within the coating, resulting in coating damage. [5-7] V 2 O 5 + Na 2 SO 4 → 2(NaVO 3 ) + SO 3 (3) ZrO2 (Y 2 O 3 ) + 2(NaVO 3 ) → ZrO 2 +2(YVO 4 ) + Na 2 O (4) Na 2 O(base) + V 2 O 5 (acid) = 2NaVO 3 (salt) (5) In this study, CMAS and hot corrosion effect on TBC was examined by using two different test methods (thermal cycling and thermal gradient test) before and after laser surface modification. Scanning electron microscope images and XRD Rietveld analysis were used to understand the effect of CMAS and hot corrosion damage 2. Materials and Methods The experimental studies used INCONEL 625 superalloy metallic substrates with a diameter of 25.4 mm (1 inch) and a thickness of 2 mm. INCONEL alloys are used in high-temperature regions of gas turbine engines, and ceramic thermal barrier coatings with low thermal conductivity are usually applied to their surfaces. Since moisture, dust, oil, and oxide films on the substrates can adversely affect the bonding mechanism between the substrate and the coating, the substrate surfaces were first cleaned by washing with acetone. Then, the roughening process was applied to the substrate surfaces to increase the adhesion properties of the substrate surface with the bond layer. The roughening process, also known as sandblasting, is the process of spraying SiC powder onto the substrate surface using compressed air. During this process, SiC sand was sprayed for 60 seconds on the substrate surfaces located 40 cm away from the sand gun. The roughness value (Ra) was increased from 0.5 to 2.3 μm. A bond coat of NiCoCrAlY composition was applied to the metal substrate surface. The purpose of the bonding layer is to tolerate thermal expansion mismatch between the ceramic top layer and the metal substrate and to increase the adhesion strength of the ceramic top layer. The thermal expansion coefficients of the metallic substrate, the bond layer and the Al2O3 ceramic top layer are 17.5 × 10-6 K-1, 13 × 10-6 K-1 and 9. 86 × 10-6 K-1, respectively [8]. High velocity oxy-fuel (HVOF) process (2700 DJHE, Sulzer Metco) was used to produce the bond layer with 100 ±30 μm by using NiCoCrAlY with particle size - 37 μm (Ni 23Co 20Cr.8.5Al 4Ta 0.6Y). Single-layer CYSZ and functionally graded 8-layer alumina (Al2O3, Metco 105NS: a-Al2O3, particle size range of -45 ± 15 μm) - CYSZ (CYSZ, Metco 205NS: ZrO2, 24CeO2, 2.5Y2O3, particle size range of -90 ± 16 μm) TBCs were used for the experiments with the thickness of 250 ±50 μm for each layer 40 ±10 μm. The spray parameters of the ceramic top and bond layers are given in Table 1. The reason for using the functionally graded design as an 8-layer configuration is that it demonstrated the best thermal and mechanical performance among the 4-, 8-, and 12-layer designs tested [9,10] (Fig. 1). 2.1. Laser Surface Modification The operation of a laser is based on three main components: the laser pump, the resonators, and the active medium. The energy source is part of the second component, and the phase of the active medium determines the classification of the laser. When a laser beam hits the surface of a material, only a small fraction of the energy photons are absorbed by the target area, while the rest of the beam is reflected or transmitted through the material. The amount of energy photons absorbed depends on several factors, including laser parameters, wavelength of the laser system, power density, material composition and surface roughness. The absorbed energy is converted to heat depending on the material properties. For example, using a typical coating with a surface roughness between 3 and 6 µm and a laser system with a shorter wavelength, a significant number of high-energy photons will be reflected due to multiple reflections caused by surface irregularities, reducing the total energy absorbed by the target. Conversely, with a longer wavelength laser system such as the 10.6 µm CO₂ laser, more energy penetrates the surface, which appears flat due to the reduced beam wavelength. As the laser interacts with the target surface, intense heating occurs, potentially melting the surface, followed by rapid solidification within milliseconds. During this process, the temperature gradient and growth rate influence the size and morphology of the solidified structure. Ultimately, the rate of solidification determines the physical properties of the processed surface, such as microhardness and toughness [11,12]. The degradation of thermal barrier coatings (TBCs) is largely attributed to the characteristic surface microstructure of atmospheric plasma sprayed (APS) coatings. Although APS is a low-cost manufacturing process, it often results in high surface roughness and defects such as microcracks, molten particles, and splats. The surface architecture has a significant impact on the performance of the coating. Therefore, modifying the surface of TBCs is expected to improve their resistance to degradation, as the interaction kinetics are strongly influenced by microstructural features. Laser surface modification is an established technique for altering the surface architecture of APS coatings to improve performance. Studies have shown significant improvements in microhardness, phase stability, high-temperature corrosion and erosion resistance, wear resistance, surface roughness, and thermal shock resistance of APS coatings after laser treatment. The observed improvements are attributed to the reduction in surface roughness, increased compaction and subsequent decrease in specific reactive area, all of which contribute to the improved corrosion and erosion resistance of laser-treated APS coatings. [13-19]. Accordingly, grain size was measured for both types of specimens using the linear intercept method. The linear intercept method for ASTM hardness measurement using the nanoindentation method was carried out at the Nano Research Facility laboratory at Dublin City University, with average results taken from 15 different points on both sprayed and laser surface modified surfaces using the Bruker Hysitron TI Premier nanoindenter. 2.2. CMAS and hot corrosion tests Two experimental setups were developed for CMAS and hot corrosion testing using a laser beam with either a water-cooled plate or compressed air cooling (Fig. 2(a)). First, Na₂SO₄ and V₂O₅ corrosion salts were combined in a 1:1 ratio and applied to the coating surface. CMAS powder, produced by mechanical grinding of volcanic rock, was then added to this mixture in a 2:3 ratio and mixed again using a turbulent mixer. The chemical composition of the CMAS powder, determined by XRF analysis (Rigaku ZSX Primus-II), is shown in Table 2. This process resulted in a hot corrosion and CMAS salt dust mixture that was uniformly distributed over the thermal barrier coating at a concentration of 30 mg/cm². To minimize potential edge effects (such as molten product flow from the surface to the edges and direct substrate reaction), a 2 mm margin was maintained around the coating edges. A CO₂ laser beam (Rofin DC-015 CO₂, max. 1.5 kW) was used as the heat source. The TBC surface with the hot corrosion and CMAS mixture was heated to 1200 °C by the laser beam, with the surface temperature monitored by an optical pyrometer. The temperature was held for 1 hour. For the thermal gradient test, the samples were placed on a copper plate through which water at 15°C was circulated and heated from the surface for 1 hour. For the thermal cycling test, the samples were heated from the surface with a laser for 1 minute and then cooled from the bottom with an air cooling compressor under the substrate for 1 minute. To replicate the harsh environment and thermal gradient experienced by TBCs in gas turbine engines during real-world operation, the bottom surface of the substrate was simultaneously cooled. This was accomplished using a water-cooled copper plate. Since most thermal barrier coated components in gas turbine engines experience heating of the top surface of the ceramic layer while being cooled by the back surface of the metallic substrate, this dual heating and cooling setup effectively simulated actual operating conditions. [20]. For this reason, metal substrates with ceramic TBCs on the surface, as shown in Fig. 2a, were placed on a copper plate through which cooling water at a constant temperature of 15 °C was passed. In this way, a thermal gradient was created along the cross section of the samples as they were heated from the surface by the laser beam and simultaneously cooled from the bottom of the substrate. Meanwhile, since CMAS and hot-corrosive salt-dust mixtures are present on the sample surfaces, hot-corrosive and CMAS tests were also performed simultaneously to more realistically simulate the working conditions of the turbine engine. On the other test rig, dynamic test conditions were created to study rapid temperature changes. Thermal cycling of thermal barrier coatings in the presence of CMAS and hot corrosion powder was performed using a laser heat source and compressed air cooling. Samples were heated to 1200 C from the surface for 1 min, then cooled to room temperature under the substrate for 1 min using compressed air (Fig. 1b). Thermal cycling tests were performed until reaching 50% damage and separation or 100 cycles of TBCs Fig. 2 (b). 3. Results and discussion 3.1. Laser surface modification parameters The required surface properties are determined in the light of studies in the literature [21-23]: reduction of open surface porosity, surface remelting with 20-50 µm layer thickness, lower surface roughness (Ra <5 µm), distribution of surface cracks and no separation between layers. All of these characteristics must be present at the same time. The surface was scanned by trial and error until different laser parameters met the required characteristics. These laser parameters are laser power, laser power density, laser scanning speed, laser-sample surface distance and corresponding laser melt diameter were determined. The samples were characterized by scanning electron microscopy (surface and cross-section), profilometer, and nanohardness measurements. In the light of the characterization, different experiments were tried. The parameters for CYSZ and FG TBC samples are shown in Table 3. 3.2. Microstructure after laser surface modification After surface modification, the surface and cross-section of the CYSZ TBC were examined by scanning electron microscopy. The surface and cross-sectional microstructures of CYSZ TBC after laser surface modification are shown in Figure 3 (a-b). A uniformly distributed crack network, a reduction in open porosity on the surface, no delamination of the coating, and an approximately 30 μm re-melted zone on the surface were achieved. Examining the scanning electron microscope images of the FG sample, as shown in Figure 3 (c-d), a uniformly distributed crack network, a reduction in surface porosity, no delamination of the coating, and an approximately 35 μm re-melted zone on the surface were observed. 3.3. Surface Roughness 3.3.1. Surface Roughness of CYSZ After laser surface modification, the CYSZ sample was scanned with an optical profilometer to measure the surface roughness (Ra) before modification (as-sprayed) and after scanning. The as-sprayed surface roughness of CYSZ is shown in Fig. 4 (a). As shown in Fig. 4 (a), the surface roughness value of the as-sprayed CYSZ was determined to be Ra = 9.839 μm. After laser surface modification, the surface roughness was measured to be Ra = 1.111 μm (Fig. 4 (b)). The surface roughness value of CYSZ was reduced from 9.839 μm to 1.111 μm after laser surface modification. Correspondingly, the required surface roughness value was reduced to below 5 μm, meeting all the necessary criteria for surface modification parameters reported in the literature. 3.3.2. Surface roughness of FG The surface roughness values of the FG TBC before laser surface modification (as-sprayed) and after modification were measured using an optical profilometer. As shown in Figure 4(c), the surface roughness of the as-sprayed FG was determined to be Ra = 4.567 μm. After laser surface modification, the required surface roughness value was measured to be less than 5 μm. However, further surface modification was applied to achieve a lower average surface roughness over the entire surface, and the surface roughness value was determined. The surface roughness characteristics for FG after laser surface modification are shown in Figure 4(d). After laser surface modification, the surface of alumina was measured with an average surface roughness value of Ra = 1.633 μm. Correspondingly, the as-sprayed surface roughness value decreased from 4.567 μm to 1.633 μm. After laser surface modification, the required average surface roughness for both samples was reduced to less than 5 μm, successfully meeting all the conditions for laser surface modification. In the next section, the comparison of grain size and hardness values of the re-melted surface after laser surface modification is discussed. Studies in the literature have reported that the surface after laser surface modification has denser and harder properties compared to sprayed TBC samples [24-26]. 3.4. Micro-hardness The grain size of the coatings subjected to laser surface modification was calculated using the linear intercept method based on scanning electron microscope images taken at 2500X magnification. The average grain size was determined using 7 lines and the ASTM E112 G number formula (Formula 1), where G is the ASTM grain size number and N1 is the number of intercepts with one test line. G= -6,643856 log (Nl) – 3,288 (Formula1) According to the average grain size calculation performed by the linear intercept method, the CYSZ sample was found to have an average grain size of 1.23 μm. However, when the microstructure was examined in detail, it was observed that during the laser surface modification process, the grains grew by diffusion and fine grains aggregated to form single large grains (Fig. 5(a)). The average grain size calculated for the alumina surface was determined to be 2.52 μm (Fig. 5 (b)). The grain size increase observed for the CYSZ sample also occurred for the alumina surface. During the laser modification of the surface, it was observed that the molten particles on the surface partially diffused and transformed into single grains. The different hardness properties of the sprayed and laser surface modified coatings were calculated using the nanoindentation method. After reviewing the results, the average surface hardness of the sprayed sample was calculated to be 0.44 ± 0.25 GPa, while after laser surface modification, it was calculated to be 1.33 ± 0.28 GPa. This difference is thought to be due to the remelting that occurs during the laser interaction, where the unmelted particles and splatters visible in the APS surface morphology have a lower hardness. It has been shown that along with a denser structure, higher hardness properties can be achieved by laser surface modification. The hardness of the sprayed FG sample was measured to be 0.48 ± 0.23 GPa. After laser surface modification, the hardness value was found to be 2.46 ± 0.52 GPa. It is believed that there are two reasons for the high standard deviation after laser surface modification. These are the formation of hardness values in different ratios on the melted and unmelted surfaces after laser surface modification, and the fact that the alumina layer is harder than zirconia. All results are shown in the graph in Figure 6. Based on the hardness results evaluated after laser surface modification, the hardness of the CYSZ sample increased 2-fold, while the hardness of the FG alumina surface increased 4-fold due to remelting during laser treatment. The laser surface modification resulted in a denser surface through remelting and sintering, which made the surface harder. These results clearly demonstrate the effect of laser surface modification. Scanning of the entire surface was performed on a CNC machine with different scanning intervals depending on the melt thicknesses. For example, the CYSZ sample was scanned at a distance of 1 mm between each laser pass, and the FG sample was scanned at a distance of 1.5 mm. This approach avoided remelting and the associated damage that would occur above the melt thicknesses.. 3.5. Thermal Tests after laser surface modification The thermal gradient and cycling test was applied after laser surface modification to understand the effects of laser surface modification. By evaluating the phase analysis, microstructure analysis and EDS mapping results after laser surface modification, it was found that the re-melting and cooling during the surface modification led to the densification of the surface, which had a significant positive effect on the coatings. The evaluations showed a significant decrease in the penetration of CMAS and hot corrosion powder + salt mixtures, as well as a reduction in zirconia phase transformation and the resulting damage factors. The results of the thermal gradient and thermal cycling tests were studied in detail. 3.5.1. Thermal Gradient Test Under Static Conditions 3.5.1.1. Phase Analysis After Thermal Gradient Test After laser surface modification, the thermal gradient test was performed and phase analysis was performed on both samples evaluating three conditions: sprayed, from the surface, and from the back of the ceramic layer. Phase analysis was performed on the top and bottom surfaces of the coatings that separated between the ceramic top layer and the bond layer during the thermal test. For the CYSZ sample, the semi-stable tetragonal zirconia phase remained intact on both the surface and backside of the ceramic layer, as shown in Figure 7. The tetragonal to monoclinic phase transformation observed after the thermal gradient test prior to laser surface modification did not occur. In addition, the NaAlSi3O8 (albite) phase, resulting from the interaction between CMAS and the hot corrosion dust-salt mixture on the surface, was identified as before modification. Since no monoclinic transformation required for Rietveld analysis was detected, this analysis was not performed after the test. The laser surface modification improved the phase stability by maintaining the tetragonal phase, thereby improving the performance of the thermal barrier coating (TBC). In the FG TBC sample, phase analysis after the thermal gradient test showed that the zirconia tetragonal phase behind the ceramic top layer remained unchanged, with no tetragonal to monoclinic transformation, similar to the CYSZ sample. The results suggest that the laser surface modification created surface properties that blocked the reaction described in equations 3, 4, and 5, preventing vanadium penetration and improving phase stability. By blocking penetration, prolonged high temperature exposure caused the degradation of CMAS and hot corrosion components, forming new phases such as M-SiMg2O4, S-SiO2, and C-CaSiO3, as shown in Figure 7 (b). For the semi-stable α-γ Al2O3 phases in the sprayed FG TBC, Rietveld analyses were compared before and after the thermal gradient test. Initially, the γ-Al2O3 phase accounted for 54.6%, which increased to 71.3% after the test. Before laser surface modification, the Al2O3 phase was calculated to be 81.6%. Laser surface modification further increased the stability of the alumina phase by 14%. 3.5.1.2. Microstructure Analysis After Thermal Gradient Testing The microstructure of the CYSZ sample, analyzed from the surface and cross sections after the thermal gradient test, reveals the influence of the molten CMAS and the hot corrosion dust-salt mixture on the surface. As shown in Figure 8(a), these mixtures appear as molten and semi-molten regions due to the high temperature. The NaAlSi3O8 (albite) phases identified in the phase analysis as forming on the TBC surface were also observed in the surface microstructure as rod-like formations (Fig. 8 (a)). These phases were found to penetrate the coating and reach the interface between the ceramic top layer and the bond coat. The penetration of albite phases through surface cracks induced stress within the coating, resulting in delamination at the interface (Fig. 8 (b)). The micrograph of the CYSZ TBC sample at 25x magnification, shown in Figure 8 (c), shows damage originating from the edges, where edge effects caused delamination in the peripheral regions of the surface. The central areas of the coating also showed delamination between the ceramic layer and the bond coat. Although no tetragonal to monoclinic phase transformation was detected in the XRD results, indicating chemical stability, the penetration of the molten CMAS and the hot corrosion dust-salt mixture at high temperatures caused stress during solidification in the penetrated regions, resulting in coating failure. Figure 8(e) illustrates the penetration mechanism more clearly in the FG TBC specimen. CMAS and the hot corrosion dust-salt mixture penetrated through cracks in the surface and resolidified in these areas, promoting crack propagation. Regions of different phases and varying molten and semi-molten zones were observed on the FG sample surface. A compositional image taken using backscattered electrons revealed phases with different hues, further emphasizing the presence of multiple phases. XRD phase analysis of the sample surface confirmed the formation of new phases as a result of reactions between CMAS and the hot corrosion dust-salt mixture. In Figure 8(e), a cross-sectional image of the FG TBC sample shows the ceramic layer and bond coat interface with a 0.5 µm thermally grown oxide (TGO) layer. According to a study by Torkashvand et al [27], a TGO thickness greater than 4 µm can generate critical stresses that lead to coating failure. In the CYSZ sample, the TGO thickness measured after the thermal gradient test performed prior to laser surface modification ranged from 2 to 5 µm. This indicates that the oxidation resistance of the bond coat was improved under the same conditions due to the effects of alumina and laser surface modification. In the 25x magnified image of the FG coating, no delamination was observed below the region containing CMAS and the hot corrosion dust-salt mixture. The coating failure appears to have originated from the edge regions, probably due to thermal expansion mismatch. Therefore, it can be concluded that the TBC was effective in protecting against the corrosive components (Fig. 8 (f)). The elemental analysis performed using the EDS mapping method shows that Si and Na elements are concentrated at the ceramic-bond coat interface of the CYSZ sample (Fig. 9). This suggests that the NaAlSi3O8 (albite) phase has penetrated the TBC interface and caused stress-induced delamination, as confirmed by the EDS mapping analysis. It was also observed that V and Ca elements were distributed within the coating, while sulfur was comparatively more concentrated in all layers, including the substrate. 3.5.2. Thermal Cycling Test Under Dynamic Conditions Both thermal barrier coating samples were dynamically thermally cycled by heating the surface to 1200°C for 1 minute using a laser, followed by cooling from below the sample for 1 minute using an air compressor. The thermal cycling test was terminated after either 100 cycles or when 50% of the coating had delaminated from the substrate.. 3.5.2.1. Phase Analysis After Thermal Cycling Test In the XRD phase analysis performed after the thermal cycling test, some reactions occurring on the surface of the CYSZ sample were observed. It was found that SiO2 and AlMgYO3 phases, which were not observed before the laser surface modification, had formed. The SiO2 phase is thought to be residual CMAS dust, while the AlMgYO3 phase probably formed due to the dissolution of Y+ ions from the Y2O3 stabilizer in the coating interacting with the CMAS dust. However, due to the beneficial effects of laser surface modification, phase stabilization was maintained. Although Y+ ions extracted from the dense surface formed a new phase, they did not create an effect that would cause the tetragonal-monoclinic transformation of zirconia. Despite the formation of a dense coating on the surface, XRD results from both the surface and the back of the ceramic layer showed the presence of NaAlSi3O8 (albite) phases. This can be attributed to the penetration of CMAS and hot corrosion dust + salts during thermal cycling, interacting with Al2O3, Na2SO4 and SiO2 and creating stress in the penetration regions. These results can be understood from the EDS mapping images in Figure 12, where higher penetration of Na, Al, and Si elements are observed (Figure 10). When examining the phase analysis results for the FG TBC, it was observed that no tetragonal to monoclinic phase transformation occurred in the analysis results taken from below the ceramic layer. This can be attributed to the higher penetration reduction of CMAS and the hot corrosion dust + salt mixture in the laser concentrated region, which prevented reactions that could disrupt phase stability. The phase analysis result of the alumina surface showed that α-γ alumina phase transformation occurred, which led to a Rietveld analysis using the HighScore Plus application of PANalytical (Malvern PANalytical) Empyrean & X'Pert PRO. In the sprayed state, the result indicated the presence of 54.6% gamma alumina phase. However, after the thermal cycling test on the laser modified surface, 70.5% γ-alumina phase was found. Comparing the sprayed and laser-modified alumina surfaces after the thermal cycling test under the same conditions, the sprayed sample contained 81.6% γ-alumina, while the laser-modified sample contained 70.5% γ-alumina. Similar to the result from the thermal gradient test, the laser surface modification resulted in a 15.7% increase in phase stability. 3.5.2.2. Microstructure Analysis After Thermal Cycling Test As observed in the surface microstructure of the CYSZ sample, it was found that the CMAS and hot corrosion dusts melted at 1200 °C and spread over the entire surface and distributed over the coating (Fig. 11 (a)). No damage was observed on the surface during the microstructural examination; however, to analyze penetration and damage, the cross-sectional microstructure of the coatings was examined (Fig. 11). In the cross-sectional microstructure shown in Figure 11 (b), cracks formed on the CYSZ sample surface after laser surface modification are seen to expand and penetrate deeper into the coating under the influence of CMAS and hot corrosion components. The cracks, which extend to the interface between the ceramic layer and the bond coat, are thought to oxidize the bond coat and cause the coating to delaminate. In Figure 11 (c), looking at the edges of the coating, it is observed that the surface crack progresses along the bond coat, with the metal substrate experiencing greater thermal expansion while the ceramic layer experiences less thermal expansion. As a result, the substrate extends from under the ceramic layer, causing separation at the metal-ceramic interface. In Figure 11(d), semi-molten and molten regions of CMAS and hot corrosion melts are observed on the laser-modified surface of the FG sample after the thermal cycling test. The thermal cycling effects are not clearly distinguishable from the surface morphology. However, by examining Fig. 11(e), the formation of stress due to solidification of CMAS and hot corrosion melts at lower temperatures near the coating surface is shown, leading to coating damage and crack propagation. Similar to the CYSZ sample, delamination at the ceramic-metal bond coat interface due to thermal expansion mismatch is observed in Figure 11. Figure 12 shows the EDS mapping images of the cross-sectional microstructures of two samples after thermal cycling following laser surface modification. The penetration of CMAS and hot corrosion melts is clearly identified, and the presence of the corrosion-causing V element is observed in the Zr-rich regions of both samples. The Si penetration is also higher in the CYSZ sample compared to the FG sample. Researchers have reported that SiO2 has a very detrimental effect during thermal cycling. SiO2 decomposes at zirconia grain boundaries and accumulates excessively, resulting in localized grain boundary degradation [28]. The initial formation of the surface crack seen in Figure 12 (a) is believed to be due to the regional concentration of Si elements. The addition of alumina is shown to reduce the effects of CMAS, and the hot corrosion dust + salt mixture in thermal barrier coatings (Fig. 12 (b)) shows the separation of the coating from the bond coat. 4. Conclusion The CMAS and hot corrosion properties of CYSZ and FG TBCs were retested after laser surface modification using two different test methods (thermal gradient and thermal cycling). - Thermal gradient testing was performed on both designs at 1200°C with CMAS and hot corrosion salts using a CO2 laser. After 1 hour of testing, the FG design showed better performance due to a lower TGO layer and higher design stability. - Both designs were subjected to thermal cycling tests at 1200°C with CMAS and hot corrosion salts using a CO2 laser. After 100 cycles, both designs showed improved protection due to the laser surface modification. To understand vanadium corrosion before and after laser surface modification, Rietveld analysis was performed on the surface and behind the ceramic layer of the TBCs. Before laser surface modification, a 64% monoclinic transformation was calculated, while a 12% monoclinic transformation was observed in the CYSZ TBC. However, no phase transformation occurred in either design (CYSZ and FG) after the thermal cycling or thermal gradient tests due to the laser surface modification. - Laser surface modification positively affected the corrosion properties of the TBC surfaces, and no monoclinic transformation was observed in either type of TBC after laser surface modification. - Laser surface modified functionally graded (FG) TBCs were found to have better properties than single-layer CYSZ according to the results of CMAS and hot corrosion tests. Declarations Acknowledgement The authors thank Prof. Dr. Gultekin Goller and Hasan Huseyin Sezer for their contributions to the thermal spray and characterization process. The authors also thank Prof. Dermot Brabazon and Merve Nur Dogu at Dublin City University (DCU) for his support on SEM-EDS mapping analyses Ethical Aproval There is no ethically problem with the samples or other datas included in manuscript. Fundings There is no funding for this study. All data are available for the journal. There is no competing interest. Manuscript is propried by one author. It is me Fatih KIRBIYIK. There is no other competing author for this manuscript. References Feng J, Wu J, Guo L, Guo H. Finite element analysis on temperature field and stress distribution of thermal barrier coatings by laser modification and CMAS corrosion. Corrosion Communications 2022;6:29–39. https://doi.org/10.1016/j.corcom.2021.12.002. Bakkar S, Pantawane MV, Gu JJ, Ghoshal A, Walock M, Murugan M, et al. Laser surface modification of porous yttria stabilized zirconia against CMAS degradation. Ceram Int 2020;46:6038–45. https://doi.org/10.1016/j.ceramint.2019.11.061. Bakkar S, Pantawane MV, Gu JJ, Ghoshal A, Walock M, Murugan M, et al. Laser surface modification of porous yttria stabilized zirconia against CMAS degradation. Ceram Int 2019. https://doi.org/10.1016/J.CERAMINT.2019.11.061. Guo L, Gao Y, Cheng Y, Sun J, Ye F, Wang L. Microstructure design of the laser glazed layer on thermal barrier coatings and its effect on the CMAS corrosion. Corros Sci 2021;192. https://doi.org/10.1016/j.corsci.2021.109847. Oxidation and hot corrosion of thermal barrier coatings (TBCs). n.d. Zhong XH, Wang YM, Xu ZH, Zhang YF, Zhang JF, Cao XQ. Hot-corrosion behaviors of overlay-clad yttria-stabilized zirconia coatings in contact with vanadate-sulfate salts. J Eur Ceram Soc 2010;30:1401–8. https://doi.org/10.1016/j.jeurceramsoc.2009.10.017. Eliaz N, Shemesh G, Latanision RM. Hot corrosion in gas turbine components. Eng Fail Anal 2002;9:31–43. https://doi.org/10.1016/S1350-6307(00)00035-2. Cao XQ, Vassen R, Stoever D. Ceramic materials for thermal barrier coatings. J Eur Ceram Soc 2004;24:1–10. https://doi.org/10.1016/S0955-2219(03)00129-8. Al Harbi N, Benyounis KY, Looney L, Stokes J. Laser Surface Modification of Ceramic Coating Materials. Encyclopedia of Smart Materials, Elsevier; 2018, p. 445–61. https://doi.org/10.1016/B978-0-12-803581-8.11386-4. Kirbiyik F, Gok MG, Goller G. Microstructural, mechanical and thermal properties of Al 2 O 3 /CYSZ functionally graded thermal barrier coatings. Surf Coat Technol 2017;329:193–201. https://doi.org/10.1016/j.surfcoat.2017.08.025. Harbi N Al, Benyounis KY, Looney L, Stokes J. Laser Surface Modification of Ceramic Coating Materials. Encyclopedia of Smart Materials, Elsevier; 2021, p. 445–61. https://doi.org/10.1016/B978-0-12-803581-8.11386-4. Gok MG, Goller G. Microstructural evaluation of laser remelted gadolinium zirconate thermal barrier coatings. Surf Coat Technol 2015;276:202–9. https://doi.org/10.1016/j.surfcoat.2015.06.074. Varghese P, Vetrivendan E, Krupa BRV, Shukla PK, Gupta RK, Rao EH, et al. Degradation of thermally sprayed Al2O3 coatings in reactor-grade liquid-sodium and its mitigation by laser treatment. Ceram Int 2022;48:13914–26. https://doi.org/10.1016/j.ceramint.2022.01.276. Wellman RG, Nicholls JR. Erosion, corrosion and erosion-corrosion of EB PVD thermal barrier coatings. Tribol Int 2008;41:657–62. https://doi.org/10.1016/j.triboint.2007.10.004. Huo K, Zhao Y, Hua Y, Cai J, Ye Y, Dai F. Study of CMAS wettability, penetration, and degradation behaviors on EB-PVD 8YSZ coatings laser micro-glazed (LMGed) by an ultraviolet picosecond ultrashort pulsed laser. Surf Coat Technol 2024;489. https://doi.org/10.1016/j.surfcoat.2024.131136. Huo K, Zhao Y, Hua Y, Cai J, Ye Y, Dai F. Study of CMAS wettability, penetration, and degradation behaviors on EB-PVD 8YSZ coatings laser micro-glazed (LMGed) by an ultraviolet picosecond ultrashort pulsed laser. Surf Coat Technol 2024;489. https://doi.org/10.1016/j.surfcoat.2024.131136. Wu J, Gao Y, Guo C, Guo L. Laser surface modification to improve the resistance of CMAS + molten salt coupling corrosion to thermal barrier coatings. Ceram Int 2023;49:32282–91. https://doi.org/10.1016/j.ceramint.2023.07.203. Guo L, Gao Y, Cheng Y, Sun J, Ye F, Wang L. Microstructure design of the laser glazed layer on thermal barrier coatings and its effect on the CMAS corrosion. Corros Sci 2021;192. https://doi.org/10.1016/j.corsci.2021.109847. Huo K, Qian W, Cai J, Ye Y, Hua Y, Zhang X, et al. The hot corrosion resistance of APS YSZ coatings micro glazed via an ultraviolet picosecond ultrashort pulsed laser. Corros Sci 2023;222. https://doi.org/10.1016/j.corsci.2023.111435. Jackson RW, Begley MR. Critical cooling rates to avoid transient-driven cracking in thermal barrier coating (TBC) systems. Int J Solids Struct 2014;51:1364–74. https://doi.org/10.1016/j.ijsolstr.2013.12.029. Guo L, Xin H, Zhang Z, Zhang X, Ye F. Microstructure modification of Y2O3 stabilized ZrO2 thermal barrier coatings by laser glazing and the effects on the hot corrosion resistance. Journal of Advanced Ceramics 2020;9:232–42. https://doi.org/10.1007/s40145-020-0363-z. Ahmadi-Pidani R, Shoja-Razavi R, Mozafarinia R, Jamali H. Improving the thermal shock resistance of plasma sprayed CYSZ thermal barrier coatings by laser surface modification. Opt Lasers Eng 2012;50:780–6. https://doi.org/10.1016/j.optlaseng.2011.12.007. Ilyinkova TA, Baldaev SL, Fedorova MO. Laser modification of thermal barrier coatings. Strengthening Technologies and Coatings 2024:114–9. https://doi.org/10.36652/1813-1336-2024-20-3-114-119. Reza MS, Aqida SN, Mohd Toff MR. An Investigation of Phase Crystallinity in Laser Modified Yttria Stabilized Zirconia (YSZ) Thermal Barrier Coating Key Eng Mater 2014;611–612:1601–7. https://doi.org/10.4028/www.scientific.net/KEM.611-612.1601. Avcı A, Karabaş M, Akdoğan Eker A, Akman E, Aslan C. Improvement of CMAS resistance of laser glazed and nano-modified YSZ thermal barrier coatings. Ceram Int 2024;50:9985–99. https://doi.org/10.1016/j.ceramint.2023.12.228. Varghese P, Vetrivendan E, Krupa BRV, Shukla PK, Gupta RK, Rao EH, et al. Degradation of thermally sprayed Al2O3 coatings in reactor-grade liquid-sodium and its mitigation by laser treatment. Ceram Int 2022;48:13914–26. https://doi.org/10.1016/j.ceramint.2022.01.276. Torkashvand K, Poursaeidi E, Mohammadi M. Effect of TGO thickness on the thermal barrier coatings life under thermal shock and thermal cycle loading. Ceram Int 2018;44:9283–93. https://doi.org/10.1016/j.ceramint.2018.02.140. Ma W, Dong H. Ceramic thermal barrier coating materials. Thermal Barrier Coatings, Elsevier; 2011, p. 25–52. https://doi.org/10.1533/9780857090829.1.25. Tables Table 1. APS and HVOF spraying parameters of ceramic top coats and NiCoCrAlY. Parameters CYSZ Al 2 O 3 CYSZ + Al 2 O 3 NiCoCrAlY Hydrogen flow rate (l/min) 15 15 15 - Argon flow rate (l/min) 90 90 90 - Ampere (A) 400 450 450 - Voltage (V) 63 63 63 - Oxygen flow rate (SLPM) - - - 24 Air flow rate (SLPM) - - - 50 Propane flow rate (SLPM) - - - 40 Spray distance (mm) 75 75 75 250 Spray angle to surface (°) 90 90 90 90 Powder feed (lb/min) 6.5 6.5 6.5 7.4 Table 2. CMAS powders XRF analysis results. CaO SiO 2 Al 2 O 3 Fe 2 O 3 MgO K 2 O TiO Other 29.23 28.31 19.32 9.20 2.52 4.62 3.26 3.54 Table 3 . Laser surface modification parameters. Sample Laser power (W) Laser power density (W/cm 2 ) Laser distance (cm) Laser spot diameter (mm) Laser scanning speed (mm/s) CYSZ 360 90 5.5 2.2 170 FG 380 100 5.5 2.2 170 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 03 Oct, 2025 Read the published version in Lasers in Manufacturing and Materials Processing → Version 1 posted Editorial decision: Revision requested 29 Jul, 2025 Reviews received at journal 29 Jul, 2025 Reviewers agreed at journal 03 Jul, 2025 Reviewers agreed at journal 02 Jul, 2025 Reviewers agreed at journal 03 Apr, 2025 Reviewers agreed at journal 29 Mar, 2025 Reviews received at journal 10 Mar, 2025 Reviewers agreed at journal 21 Feb, 2025 Reviewers invited by journal 19 Feb, 2025 Editor assigned by journal 19 Feb, 2025 Submission checks completed at journal 19 Feb, 2025 First submitted to journal 16 Feb, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6040852","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":418476507,"identity":"70b90c07-96f2-477f-9af5-46088e6e8104","order_by":0,"name":"Fatih Kirbiyik","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIiWNgGAWjYBACCWYGNoYEBgkD9vbGBpAAYwPRWnjOHATrAWphJqCFAagFCAx4biQwEqdFsp332YOHbRbGPJKP2x/zMNjIbjjAf+wDPi3SzOzmBoltEmY80omNzTwMacYbDjAzz8CnRY6ZjU0CqMXGHqLlcCJIC16HwbXwSB4EaflPWIs0VIsZjwQjSMsBwlokm9nYDRLOSRjz8CQ2zpxjkGw88zCzMV4tEuePsT38UVZn2MN+/MGHNxV2sn3HGx/j1QIGjGwwlgEQE4gWKPhDlKpRMApGwSgYqQAAnn0/f/6XgyoAAAAASUVORK5CYII=","orcid":"","institution":"Adıyaman University","correspondingAuthor":true,"prefix":"","firstName":"Fatih","middleName":"","lastName":"Kirbiyik","suffix":""}],"badges":[],"createdAt":"2025-02-16 11:38:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6040852/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6040852/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s40516-025-00315-7","type":"published","date":"2025-10-03T15:57:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":76883408,"identity":"196456ac-f445-48b2-94fc-b431b05563a0","added_by":"auto","created_at":"2025-02-21 17:43:10","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":100132,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of laser a) thermal gradient and b) thermal cycling test.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/a794968aa5233195a91f9111.jpg"},{"id":76883409,"identity":"3735648f-2423-4a99-aae8-b8e5ecb7452f","added_by":"auto","created_at":"2025-02-21 17:43:11","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":10888852,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructures after laser surface modification a) CYSZ surface, b) CYSZ cross-sectional, c) FG surface and d) FG cross-sectional.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/6879e2901b7988391d2cc1ea.jpg"},{"id":76882755,"identity":"40a3bb5b-4a9c-42eb-b47d-2d9dedb56d3e","added_by":"auto","created_at":"2025-02-21 17:35:10","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1065928,"visible":true,"origin":"","legend":"\u003cp\u003eCYSZ surface roughness properties a) as sprayed and b) laser surface modified FG surface roughness properties c) as-sprayed and d) laser surface modified.\u003c/p\u003e","description":"","filename":"Figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/889da14cec10003ad357e8d7.jpg"},{"id":76882756,"identity":"54f56d65-ebea-4e0c-bef5-ced90215c7b9","added_by":"auto","created_at":"2025-02-21 17:35:10","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":4647978,"visible":true,"origin":"","legend":"\u003cp\u003eGrain image after laser surface modification at 2500x magnification a) CYSZ and b) FG.\u003c/p\u003e","description":"","filename":"Figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/ee9776a47ab9c5d72a370b59.jpg"},{"id":76882754,"identity":"498343a4-ced0-42e1-b8fb-32e8ca312e6a","added_by":"auto","created_at":"2025-02-21 17:35:10","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":30419,"visible":true,"origin":"","legend":"\u003cp\u003eHardness values before and after laser surface modification: CYSZ as-sprayed (CYSZ APS), CYSZ laser surface modified (CYSZ LSM), FG as-sprayed (FG APS), and FG after laser surface modification (FG LSM).\u003c/p\u003e","description":"","filename":"Figure6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/ea494335422c4966041655c7.jpg"},{"id":76882757,"identity":"3a09a8dd-cf49-49cf-a75b-f5d629ce6235","added_by":"auto","created_at":"2025-02-21 17:35:11","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1109805,"visible":true,"origin":"","legend":"\u003cp\u003eXRD analysis results of samples subjected to thermal gradient testing after laser surface modification: (a) CYSZ, (b) FG.\u003c/p\u003e","description":"","filename":"Figure7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/dbf2bf1e6f54dfa6315ec872.jpg"},{"id":76882764,"identity":"7557f8e6-3e7d-4e86-8797-2bfd74f2372d","added_by":"auto","created_at":"2025-02-21 17:35:11","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":7256664,"visible":true,"origin":"","legend":"\u003cp\u003eAfter single-layer CYSZ thermal gradient test a) surface b,c) cross-section, after functionally graded TBC thermal gradient test d) surface e,f) cross-section microstructure.\u003c/p\u003e","description":"","filename":"Figure8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/652ab7783f016a8e3ff034c7.jpg"},{"id":76882765,"identity":"6ba099e0-58d1-48a1-92e3-2f57c49a1aef","added_by":"auto","created_at":"2025-02-21 17:35:11","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":160164,"visible":true,"origin":"","legend":"\u003cp\u003eEDS mapping analysis of the samples after the thermal gradient test following laser modification a) CYSZ b) FG.\u003c/p\u003e","description":"","filename":"Figure9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/e704abbede65da0395f5663c.jpg"},{"id":92884282,"identity":"ff092694-db54-4b98-a208-56120f8ad971","added_by":"auto","created_at":"2025-10-06 16:12:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":25901268,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6040852/v1/980f3745-efbd-49cf-b020-6d62a2c8c3ad.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Laser surface modification of Al 2 O 3 / CYSZ functionally graded TBC against CMAS and hot corrosion damage","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe service life of thermal barrier coatings (TBCs) is typically limited to shear due to oxidative stress between the ceramic layer and the bond layer. Morphological instability or \u0026quot;wrinkling\u0026quot; has been identified as one of the dissociation mechanisms between the thermally growing oxide layer (TGO) and the TBC. In addition to the thermal coefficient of expansion (CTE) mismatch between the ceramic TBC and a metallic substrate, damage can also occur as a result of the concentration of non-engine contaminants that accumulate on the TBC surface and penetrate the TBC structure during gas turbine engine operation. Notable components of these contaminants include calcium-magnesium-aluminum-silicon oxides (CaO - MgO -Al2O3 -SiO2), referred to as CMAS, and hot corrosion fuel impurities (NaSO4, NaCl, and V2O5). Depending on the environment, CMAS may also contain small amounts of oxides of elements such as Ni, Fe, Ti, and Cr. This material has a relatively low eutectic melting point, ranging from 1190 to 1260\u0026deg;C, which varies depending on its composition. The melting temperature of CMAS can be further reduced by the presence of multiple components and modifying elements such as sodium. As CMAS melts, it wets the outer YSZ (TBC) layer and infiltrates the inner porous structure. This infiltration reduces the porosity and disrupts the columnar architecture, resulting in an increase in the Young\u0026apos;s modulus of the TBC. As a result, the reduced strain tolerance and mismatch in coefficient of thermal expansion (CTE) between the CMAS and TBC causes fragmentation, ultimately compromising the thermal protection of the underlying metal component [1,2].\u003c/p\u003e\n\u003cp\u003eIn recent years, considerable effort has been devoted to developing methods to combat CMAS corrosion. Two main approaches have shown promising results. The first involves the use of impermeable and non-wetting materials, while the second focuses on modifying TBC compositions to react rapidly with CMAS to form a dense protective layer. This reaction requires a fast reaction rate, high melting point, and dense reaction products. However, these methods have certain drawbacks. Impermeable or non-wetting materials may not be suitable as stand-alone TBCs, and candidate materials that facilitate crystallization often face significant application challenges due to their relatively poor mechanical properties [3,4]. Consequently, there is a need for practical, cost-effective and user-friendly solutions. One promising approach is the design of pavement-like structures, with laser modification of TBC surface structures emerging as an effective method to enhance resistance to CMAS corrosion. Many researchers have investigated [3,4] that laser-based surface modification results in the formation of TBCs with a more compact and refined surface. This altered morphology effectively protects against the infiltration of hot corrosion melts into the coating.\u003c/p\u003e\n\u003cp\u003eUnwanted fuel contaminants accumulate on the TBC surface during high-temperature service. These contaminants interact with the coating at high temperatures, causing degradation, cracking, or disintegration. This damage mechanism, known as hot corrosion, occurs when molten salts penetrate through microcracks and pores in the topcoat. Under hot corrosion service conditions, elements such as sodium, vanadium and lead change the chemical structure of the coating. When elements such as sodium, sulfur, phosphorus, and vanadium from fuel contamination are present in the structure, they react with the Y2O3 phase and cause its depletion. In the absence of the Y2O3 phase, a tetragonal-monoclinic phase transformation occurs. Stabilization of the tetragonal ZrO2 phase is no longer possible. This transformation can result in a volume change that compromises the integrity of the surface layer. Corrosion mechanisms triggered by poor quality fuel or adverse operating conditions further weaken the surface layer and lead to damage. Hot corrosion begins with the accumulation of high melting point salts on the metal surface. Typically, after the reaction of SO 3 and NaCl, a salt deposit of Na2SO4 and hot corrosion salts is formed on the coating surface. Reactions 1 and 2 proceed according to the hot corrosion damage mechanism.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 491px;\"\u003e\n \u003cp\u003e2NaCl + SO\u003csub\u003e3\u0026nbsp;\u003c/sub\u003e+ H\u003csub\u003e2\u003c/sub\u003eO\u0026rarr;Na\u003csub\u003e2\u0026nbsp;\u003c/sub\u003eSO\u003csub\u003e4\u0026nbsp;\u003c/sub\u003e+ 2HCl (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 56px;\"\u003e\n \u003cp\u003e(1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 491px;\"\u003e\n \u003cp\u003e4NaCl + 2SO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e+ 2H\u003csub\u003e2\u003c/sub\u003eO + O \u003csub\u003e2\u0026nbsp;\u003c/sub\u003e\u0026rarr;2Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u0026nbsp;\u003c/sub\u003e+ 4HCl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 56px;\"\u003e\n \u003cp\u003e(2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eHot corrosion is a form of deterioration caused by the presence of salts such as Na₂SO₄, NaCl, and V₂O₅. These salts, either individually or in combination, can cause corrosion at high temperatures. The mechanism of hot corrosion is classified into two types based on the temperature range and the nature of the corrosion process. Type I is high-temperature hot corrosion and type II is low-temperature hot corrosion. The progression of these two types of hot corrosion can be influenced by several factors, including alloy composition, thermomechanical state, contaminant composition, flow rate, temperature and thermal cycling, gas composition, and erosion.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe demanding performance and durability standards of gas turbine engines in the aerospace and automotive industries require the use of advanced, next-generation thermal barrier coatings (TBCs). To meet these needs, numerous TBC materials have been developed with low thermal conductivity, high temperature resistance, and excellent corrosion resistance. However, even TBC materials with high thermal conductivity and superior phase stability are exposed to various corrosive environments due to the use of low-grade fuels. These TBCs are specifically designed to function effectively in highly corrosive operating conditions. In TBCs, high-temperature corrosion is typically caused by mixtures of Na2SO4 and V2O5 molten salts. Especially in TBCs with YSZ topcoat, the mixture of V2O5 and Na2SO4 salt reacts with the topcoat at high temperatures to form the following equations (Equations 3, 4 and 5). According to these equations, the topcoat is monoclinic. It consists of zirconia and YVO 4 structures. The formation of these new hot corrosion products leads to volume expansion within the coating, resulting in coating damage. [5-7]\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 491px;\"\u003e\n \u003cp\u003eV\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u0026nbsp;\u003c/sub\u003e+ Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u0026nbsp;\u003c/sub\u003e\u0026rarr; 2(NaVO\u003csub\u003e3\u003c/sub\u003e) + SO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 56px;\"\u003e\n \u003cp\u003e(3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 491px;\"\u003e\n \u003cp\u003eZrO2 (Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) + 2(NaVO\u003csub\u003e3\u003c/sub\u003e) \u0026rarr; ZrO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e+2(YVO\u003csub\u003e4\u003c/sub\u003e) + Na\u003csub\u003e2\u0026nbsp;\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 56px;\"\u003e\n \u003cp\u003e(4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 491px;\"\u003e\n \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eO(base) + V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u0026nbsp;\u003c/sub\u003e(acid) = 2NaVO\u003csub\u003e3\u0026nbsp;\u003c/sub\u003e(salt)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 56px;\"\u003e\n \u003cp\u003e(5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eIn this study, CMAS and hot corrosion effect on TBC was examined by using two different test methods (thermal cycling and thermal gradient test) before and after laser surface modification. Scanning electron microscope images and XRD Rietveld analysis were used to understand the effect of CMAS and hot corrosion damage\u003c/p\u003e"},{"header":"2.\tMaterials and Methods ","content":"\u003cp\u003eThe experimental studies used INCONEL 625 superalloy metallic substrates with a diameter of 25.4 mm (1 inch) and a thickness of 2 mm. INCONEL alloys are used in high-temperature regions of gas turbine engines, and ceramic thermal barrier coatings with low thermal conductivity are usually applied to their surfaces. Since moisture, dust, oil, and oxide films on the substrates can adversely affect the bonding mechanism between the substrate and the coating, the substrate surfaces were first cleaned by washing with acetone. Then, the roughening process was applied to the substrate surfaces to increase the adhesion properties of the substrate surface with the bond layer. The roughening process, also known as sandblasting, is the process of spraying SiC powder onto the substrate surface using compressed air. During this process, SiC sand was sprayed for 60 seconds on the substrate surfaces located 40 cm away from the sand gun. The roughness value (Ra) was increased from 0.5 to 2.3 \u0026mu;m. A bond coat of NiCoCrAlY composition was applied to the metal substrate surface. The purpose of the bonding layer is to tolerate thermal expansion mismatch between the ceramic top layer and the metal substrate and to increase the adhesion strength of the ceramic top layer. The thermal expansion coefficients of the metallic substrate, the bond layer and the Al2O3 ceramic top layer are 17.5 \u0026times; 10-6 K-1, 13 \u0026times; 10-6 K-1 and 9. 86 \u0026times; 10-6 K-1, respectively [8]. High velocity oxy-fuel (HVOF) process (2700 DJHE, Sulzer Metco) was used to produce the bond layer with 100 \u0026plusmn;30 \u0026mu;m by using NiCoCrAlY with particle size - 37 \u0026mu;m (Ni 23Co 20Cr.8.5Al 4Ta 0.6Y). Single-layer CYSZ and functionally graded 8-layer alumina (Al2O3, Metco 105NS: a-Al2O3, particle size range of -45 \u0026plusmn; 15 \u0026mu;m) - CYSZ (CYSZ, Metco 205NS: ZrO2, 24CeO2, 2.5Y2O3, particle size range of -90 \u0026plusmn; 16 \u0026mu;m) TBCs were used for the experiments with the thickness of 250 \u0026plusmn;50 \u0026mu;m for each layer 40 \u0026plusmn;10 \u0026mu;m. The spray parameters of the ceramic top and bond layers are given in Table 1. The reason for using the functionally graded design as an 8-layer configuration is that it demonstrated the best thermal and mechanical performance among the 4-, 8-, and 12-layer designs tested [9,10] (Fig. 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.1. \u0026nbsp;Laser Surface Modification\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe operation of a laser is based on three main components: the laser pump, the resonators, and the active medium. The energy source is part of the second component, and the phase of the active medium determines the classification of the laser. When a laser beam hits the surface of a material, only a small fraction of the energy photons are absorbed by the target area, while the rest of the beam is reflected or transmitted through the material. The amount of energy photons absorbed depends on several factors, including laser parameters, wavelength of the laser system, power density, material composition and surface roughness.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe absorbed energy is converted to heat depending on the material properties. For example, using a typical coating with a surface roughness between 3 and 6 \u0026micro;m and a laser system with a shorter wavelength, a significant number of high-energy photons will be reflected due to multiple reflections caused by surface irregularities, reducing the total energy absorbed by the target. Conversely, with a longer wavelength laser system such as the 10.6 \u0026micro;m CO₂ laser, more energy penetrates the surface, which appears flat due to the reduced beam wavelength.\u003c/p\u003e\n\u003cp\u003eAs the laser interacts with the target surface, intense heating occurs, potentially melting the surface, followed by rapid solidification within milliseconds. During this process, the temperature gradient and growth rate influence the size and morphology of the solidified structure. Ultimately, the rate of solidification determines the physical properties of the processed surface, such as microhardness and toughness [11,12].\u003c/p\u003e\n\u003cp\u003eThe degradation of thermal barrier coatings (TBCs) is largely attributed to the characteristic surface microstructure of atmospheric plasma sprayed (APS) coatings. Although APS is a low-cost manufacturing process, it often results in high surface roughness and defects such as microcracks, molten particles, and splats. The surface architecture has a significant impact on the performance of the coating. Therefore, modifying the surface of TBCs is expected to improve their resistance to degradation, as the interaction kinetics are strongly influenced by microstructural features.\u003c/p\u003e\n\u003cp\u003eLaser surface modification is an established technique for altering the surface architecture of APS coatings to improve performance. Studies have shown significant improvements in microhardness, phase stability, high-temperature corrosion and erosion resistance, wear resistance, surface roughness, and thermal shock resistance of APS coatings after laser treatment. The observed improvements are attributed to the reduction in surface roughness, increased compaction and subsequent decrease in specific reactive area, all of which contribute to the improved corrosion and erosion resistance of laser-treated APS coatings. [13-19]. Accordingly, grain size was measured for both types of specimens using the linear intercept method. The linear intercept method for ASTM hardness measurement using the nanoindentation method was carried out at the Nano Research Facility laboratory at Dublin City University, with average results taken from 15 different points on both sprayed and laser surface modified surfaces using the Bruker Hysitron TI Premier nanoindenter.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2. \u0026nbsp; CMAS and hot corrosion tests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTwo experimental setups were developed for CMAS and hot corrosion testing using a laser beam with either a water-cooled plate or compressed air cooling (Fig. 2(a)). First, Na₂SO₄ and V₂O₅ corrosion salts were combined in a 1:1 ratio and applied to the coating surface. CMAS powder, produced by mechanical grinding of volcanic rock, was then added to this mixture in a 2:3 ratio and mixed again using a turbulent mixer. The chemical composition of the CMAS powder, determined by XRF analysis (Rigaku ZSX Primus-II), is shown in Table 2.\u003c/p\u003e\n\u003cp\u003eThis process resulted in a hot corrosion and CMAS salt dust mixture that was uniformly distributed over the thermal barrier coating at a concentration of 30 mg/cm\u0026sup2;. To minimize potential edge effects (such as molten product flow from the surface to the edges and direct substrate reaction), a 2 mm margin was maintained around the coating edges.\u003c/p\u003e\n\u003cp\u003eA CO₂ laser beam (Rofin DC-015 CO₂, max. 1.5 kW) was used as the heat source. The TBC surface with the hot corrosion and CMAS mixture was heated to 1200 \u0026deg;C by the laser beam, with the surface temperature monitored by an optical pyrometer. The temperature was held for 1 hour. For the thermal gradient test, the samples were placed on a copper plate through which water at 15\u0026deg;C was circulated and heated from the surface for 1 hour. For the thermal cycling test, the samples were heated from the surface with a laser for 1 minute and then cooled from the bottom with an air cooling compressor under the substrate for 1 minute.\u003c/p\u003e\n\u003cp\u003eTo replicate the harsh environment and thermal gradient experienced by TBCs in gas turbine engines during real-world operation, the bottom surface of the substrate was simultaneously cooled. This was accomplished using a water-cooled copper plate. Since most thermal barrier coated components in gas turbine engines experience heating of the top surface of the ceramic layer while being cooled by the back surface of the metallic substrate, this dual heating and cooling setup effectively simulated actual operating conditions. [20]. For this reason, metal substrates with ceramic TBCs on the surface, as shown in Fig. 2a, were placed on a copper plate through which cooling water at a constant temperature of 15 \u0026deg;C was passed. In this way, a thermal gradient was created along the cross section of the samples as they were heated from the surface by the laser beam and simultaneously cooled from the bottom of the substrate. Meanwhile, since CMAS and hot-corrosive salt-dust mixtures are present on the sample surfaces, hot-corrosive and CMAS tests were also performed simultaneously to more realistically simulate the working conditions of the turbine engine. On the other test rig, dynamic test conditions were created to study rapid temperature changes. Thermal cycling of thermal barrier coatings in the presence of CMAS and hot corrosion powder was performed using a laser heat source and compressed air cooling. Samples were heated to 1200 C from the surface for 1 min, then cooled to room temperature under the substrate for 1 min using compressed air (Fig. 1b). Thermal cycling tests were performed until reaching 50% damage and separation or 100 cycles of TBCs Fig. 2 (b).\u003c/p\u003e"},{"header":"3.\tResults and discussion","content":"\u003cp\u003e\u003cstrong\u003e3.1. \u0026nbsp; \u0026nbsp;Laser surface modification parameters\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe required surface properties are determined in the light of studies in the literature [21-23]: reduction of open surface porosity, surface remelting with 20-50 \u0026micro;m layer thickness, lower surface roughness (Ra \u0026lt;5 \u0026micro;m), distribution of surface cracks and no separation between layers. All of these characteristics must be present at the same time. The surface was scanned by trial and error until different laser parameters met the required characteristics. These laser parameters are laser power, laser power density, laser scanning speed, laser-sample surface distance and corresponding laser melt diameter were determined. The samples were characterized by scanning electron microscopy (surface and cross-section), profilometer, and nanohardness measurements. In the light of the characterization, different experiments were tried. The parameters for CYSZ and FG TBC samples are shown in Table 3.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2. \u0026nbsp; \u0026nbsp;Microstructure after laser surface modification\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter surface modification, the surface and cross-section of the CYSZ TBC were examined by scanning electron microscopy. The surface and cross-sectional microstructures of CYSZ TBC after laser surface modification are shown in Figure 3 (a-b). A uniformly distributed crack network, a reduction in open porosity on the surface, no delamination of the coating, and an approximately 30 \u0026mu;m re-melted zone on the surface were achieved. Examining the scanning electron microscope images of the FG sample, as shown in Figure 3 (c-d), a uniformly distributed crack network, a reduction in surface porosity, no delamination of the coating, and an approximately 35 \u0026mu;m re-melted zone on the surface were observed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3. Surface Roughness\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e3.3.1. Surface Roughness of CYSZ\u003c/p\u003e\n\u003cp\u003eAfter laser surface modification, the CYSZ sample was scanned with an optical profilometer to measure the surface roughness (Ra) before modification (as-sprayed) and after scanning. The as-sprayed surface roughness of CYSZ is shown in Fig. 4 (a). As shown in Fig. 4 (a), the surface roughness value of the as-sprayed CYSZ was determined to be Ra = 9.839 \u0026mu;m. After laser surface modification, the surface roughness was measured to be Ra = 1.111 \u0026mu;m (Fig. 4 (b)). The surface roughness value of CYSZ was reduced from 9.839 \u0026mu;m to 1.111 \u0026mu;m after laser surface modification. Correspondingly, the required surface roughness value was reduced to below 5 \u0026mu;m, meeting all the necessary criteria for surface modification parameters reported in the literature.\u003c/p\u003e\n\u003cp\u003e3.3.2. Surface roughness of FG\u003c/p\u003e\n\u003cp\u003eThe surface roughness values of the FG TBC before laser surface modification (as-sprayed) and after modification were measured using an optical profilometer.\u003c/p\u003e\n\u003cp\u003eAs shown in Figure 4(c), the surface roughness of the as-sprayed FG was determined to be Ra = 4.567 \u0026mu;m. After laser surface modification, the required surface roughness value was measured to be less than 5 \u0026mu;m. However, further surface modification was applied to achieve a lower average surface roughness over the entire surface, and the surface roughness value was determined. The surface roughness characteristics for FG after laser surface modification are shown in Figure 4(d). After laser surface modification, the surface of alumina was measured with an average surface roughness value of Ra = 1.633 \u0026mu;m. Correspondingly, the as-sprayed surface roughness value decreased from 4.567 \u0026mu;m to 1.633 \u0026mu;m.\u003c/p\u003e\n\u003cp\u003eAfter laser surface modification, the required average surface roughness for both samples was reduced to less than 5 \u0026mu;m, successfully meeting all the conditions for laser surface modification. In the next section, the comparison of grain size and hardness values of the re-melted surface after laser surface modification is discussed. Studies in the literature have reported that the surface after laser surface modification has denser and harder properties compared to sprayed TBC samples [24-26].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4. Micro-hardness\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe grain size of the coatings subjected to laser surface modification was calculated using the linear intercept method based on scanning electron microscope images taken at 2500X magnification. The average grain size was determined using 7 lines and the ASTM E112 G number formula (Formula 1), where G is the ASTM grain size number and N1 is the number of intercepts with one test line.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 491px;\"\u003e\n \u003cp\u003eG= -6,643856 log (Nl) \u0026ndash; 3,288\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e(Formula1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAccording to the average grain size calculation performed by the linear intercept method, the CYSZ sample was found to have an average grain size of 1.23 \u0026mu;m. However, when the microstructure was examined in detail, it was observed that during the laser surface modification process, the grains grew by diffusion and fine grains aggregated to form single large grains (Fig. 5(a)). The average grain size calculated for the alumina surface was determined to be 2.52 \u0026mu;m (Fig. 5 (b)). The grain size increase observed for the CYSZ sample also occurred for the alumina surface. During the laser modification of the surface, it was observed that the molten particles on the surface partially diffused and transformed into single grains.\u003c/p\u003e\n\u003cp\u003eThe different hardness properties of the sprayed and laser surface modified coatings were calculated using the nanoindentation method. After reviewing the results, the average surface hardness of the sprayed sample was calculated to be 0.44 \u0026plusmn; 0.25 GPa, while after laser surface modification, it was calculated to be 1.33 \u0026plusmn; 0.28 GPa. This difference is thought to be due to the remelting that occurs during the laser interaction, where the unmelted particles and splatters visible in the APS surface morphology have a lower hardness. It has been shown that along with a denser structure, higher hardness properties can be achieved by laser surface modification. The hardness of the sprayed FG sample was measured to be 0.48 \u0026plusmn; 0.23 GPa. After laser surface modification, the hardness value was found to be 2.46 \u0026plusmn; 0.52 GPa. It is believed that there are two reasons for the high standard deviation after laser surface modification. These are the formation of hardness values in different ratios on the melted and unmelted surfaces after laser surface modification, and the fact that the alumina layer is harder than zirconia. All results are shown in the graph in Figure 6.\u003c/p\u003e\n\u003cp\u003eBased on the hardness results evaluated after laser surface modification, the hardness of the CYSZ sample increased 2-fold, while the hardness of the FG alumina surface increased 4-fold due to remelting during laser treatment. The laser surface modification resulted in a denser surface through remelting and sintering, which made the surface harder. These results clearly demonstrate the effect of laser surface modification.\u003c/p\u003e\n\u003cp\u003eScanning of the entire surface was performed on a CNC machine with different scanning intervals depending on the melt thicknesses. For example, the CYSZ sample was scanned at a distance of 1 mm between each laser pass, and the FG sample was scanned at a distance of 1.5 mm. This approach avoided remelting and the associated damage that would occur above the melt thicknesses..\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.5. Thermal Tests after laser surface modification\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe thermal gradient and cycling test was applied after laser surface modification to understand the effects of laser surface modification. By evaluating the phase analysis, microstructure analysis and EDS mapping results after laser surface modification, it was found that the re-melting and cooling during the surface modification led to the densification of the surface, which had a significant positive effect on the coatings. The evaluations showed a significant decrease in the penetration of CMAS and hot corrosion powder + salt mixtures, as well as a reduction in zirconia phase transformation and the resulting damage factors. The results of the thermal gradient and thermal cycling tests were studied in detail.\u003c/p\u003e\n\u003cp\u003e3.5.1. Thermal Gradient Test Under Static Conditions\u003c/p\u003e\n\u003cp\u003e3.5.1.1. Phase Analysis After Thermal Gradient Test\u003c/p\u003e\n\u003cp\u003eAfter laser surface modification, the thermal gradient test was performed and phase analysis was performed on both samples evaluating three conditions: sprayed, from the surface, and from the back of the ceramic layer. Phase analysis was performed on the top and bottom surfaces of the coatings that separated between the ceramic top layer and the bond layer during the thermal test. For the CYSZ sample, the semi-stable tetragonal zirconia phase remained intact on both the surface and backside of the ceramic layer, as shown in Figure 7. The tetragonal to monoclinic phase transformation observed after the thermal gradient test prior to laser surface modification did not occur. In addition, the NaAlSi3O8 (albite) phase, resulting from the interaction between CMAS and the hot corrosion dust-salt mixture on the surface, was identified as before modification. Since no monoclinic transformation required for Rietveld analysis was detected, this analysis was not performed after the test. The laser surface modification improved the phase stability by maintaining the tetragonal phase, thereby improving the performance of the thermal barrier coating (TBC).\u003c/p\u003e\n\u003cp\u003eIn the FG TBC sample, phase analysis after the thermal gradient test showed that the zirconia tetragonal phase behind the ceramic top layer remained unchanged, with no tetragonal to monoclinic transformation, similar to the CYSZ sample. The results suggest that the laser surface modification created surface properties that blocked the reaction described in equations 3, 4, and 5, preventing vanadium penetration and improving phase stability. By blocking penetration, prolonged high temperature exposure caused the degradation of CMAS and hot corrosion components, forming new phases such as M-SiMg2O4, S-SiO2, and C-CaSiO3, as shown in Figure 7 (b).\u003c/p\u003e\n\u003cp\u003eFor the semi-stable \u0026alpha;-\u0026gamma; Al2O3 phases in the sprayed FG TBC, Rietveld analyses were compared before and after the thermal gradient test. Initially, the \u0026gamma;-Al2O3 phase accounted for 54.6%, which increased to 71.3% after the test. Before laser surface modification, the Al2O3 phase was calculated to be 81.6%. Laser surface modification further increased the stability of the alumina phase by 14%.\u003c/p\u003e\n\u003cp\u003e3.5.1.2. Microstructure Analysis After Thermal Gradient Testing\u003c/p\u003e\n\u003cp\u003eThe microstructure of the CYSZ sample, analyzed from the surface and cross sections after the thermal gradient test, reveals the influence of the molten CMAS and the hot corrosion dust-salt mixture on the surface. As shown in Figure 8(a), these mixtures appear as molten and semi-molten regions due to the high temperature. The NaAlSi3O8 (albite) phases identified in the phase analysis as forming on the TBC surface were also observed in the surface microstructure as rod-like formations (Fig. 8 (a)). These phases were found to penetrate the coating and reach the interface between the ceramic top layer and the bond coat. The penetration of albite phases through surface cracks induced stress within the coating, resulting in delamination at the interface (Fig. 8 (b)).\u003c/p\u003e\n\u003cp\u003eThe micrograph of the CYSZ TBC sample at 25x magnification, shown in Figure 8 (c), shows damage originating from the edges, where edge effects caused delamination in the peripheral regions of the surface. The central areas of the coating also showed delamination between the ceramic layer and the bond coat. Although no tetragonal to monoclinic phase transformation was detected in the XRD results, indicating chemical stability, the penetration of the molten CMAS and the hot corrosion dust-salt mixture at high temperatures caused stress during solidification in the penetrated regions, resulting in coating failure.\u003c/p\u003e\n\u003cp\u003eFigure 8(e) illustrates the penetration mechanism more clearly in the FG TBC specimen. CMAS and the hot corrosion dust-salt mixture penetrated through cracks in the surface and resolidified in these areas, promoting crack propagation. Regions of different phases and varying molten and semi-molten zones were observed on the FG sample surface. A compositional image taken using backscattered electrons revealed phases with different hues, further emphasizing the presence of multiple phases. XRD phase analysis of the sample surface confirmed the formation of new phases as a result of reactions between CMAS and the hot corrosion dust-salt mixture.\u003c/p\u003e\n\u003cp\u003eIn Figure 8(e), a cross-sectional image of the FG TBC sample shows the ceramic layer and bond coat interface with a 0.5 \u0026micro;m thermally grown oxide (TGO) layer. According to a study by Torkashvand et al [27], a TGO thickness greater than 4 \u0026micro;m can generate critical stresses that lead to coating failure. In the CYSZ sample, the TGO thickness measured after the thermal gradient test performed prior to laser surface modification ranged from 2 to 5 \u0026micro;m. This indicates that the oxidation resistance of the bond coat was improved under the same conditions due to the effects of alumina and laser surface modification.\u003c/p\u003e\n\u003cp\u003eIn the 25x magnified image of the FG coating, no delamination was observed below the region containing CMAS and the hot corrosion dust-salt mixture. The coating failure appears to have originated from the edge regions, probably due to thermal expansion mismatch. Therefore, it can be concluded that the TBC was effective in protecting against the corrosive components (Fig. 8 (f)).\u003c/p\u003e\n\u003cp\u003eThe elemental analysis performed using the EDS mapping method shows that Si and Na elements are concentrated at the ceramic-bond coat interface of the CYSZ sample (Fig. 9). This suggests that the NaAlSi3O8 (albite) phase has penetrated the TBC interface and caused stress-induced delamination, as confirmed by the EDS mapping analysis. It was also observed that V and Ca elements were distributed within the coating, while sulfur was comparatively more concentrated in all layers, including the substrate.\u003c/p\u003e\n\u003cp\u003e3.5.2. Thermal Cycling Test Under Dynamic Conditions\u003c/p\u003e\n\u003cp\u003eBoth thermal barrier coating samples were dynamically thermally cycled by heating the surface to 1200\u0026deg;C for 1 minute using a laser, followed by cooling from below the sample for 1 minute using an air compressor. The thermal cycling test was terminated after either 100 cycles or when 50% of the coating had delaminated from the substrate..\u003c/p\u003e\n\u003cp\u003e3.5.2.1. Phase Analysis After Thermal Cycling Test\u003c/p\u003e\n\u003cp\u003eIn the XRD phase analysis performed after the thermal cycling test, some reactions occurring on the surface of the CYSZ sample were observed. It was found that SiO2 and AlMgYO3 phases, which were not observed before the laser surface modification, had formed. The SiO2 phase is thought to be residual CMAS dust, while the AlMgYO3 phase probably formed due to the dissolution of Y+ ions from the Y2O3 stabilizer in the coating interacting with the CMAS dust. However, due to the beneficial effects of laser surface modification, phase stabilization was maintained. Although Y+ ions extracted from the dense surface formed a new phase, they did not create an effect that would cause the tetragonal-monoclinic transformation of zirconia.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDespite the formation of a dense coating on the surface, XRD results from both the surface and the back of the ceramic layer showed the presence of NaAlSi3O8 (albite) phases. This can be attributed to the penetration of CMAS and hot corrosion dust + salts during thermal cycling, interacting with Al2O3, Na2SO4 and SiO2 and creating stress in the penetration regions. These results can be understood from the EDS mapping images in Figure 12, where higher penetration of Na, Al, and Si elements are observed (Figure 10).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWhen examining the phase analysis results for the FG TBC, it was observed that no tetragonal to monoclinic phase transformation occurred in the analysis results taken from below the ceramic layer. This can be attributed to the higher penetration reduction of CMAS and the hot corrosion dust + salt mixture in the laser concentrated region, which prevented reactions that could disrupt phase stability.\u003c/p\u003e\n\u003cp\u003eThe phase analysis result of the alumina surface showed that \u0026alpha;-\u0026gamma; alumina phase transformation occurred, which led to a Rietveld analysis using the HighScore Plus application of PANalytical (Malvern PANalytical) Empyrean \u0026amp; X\u0026apos;Pert PRO. In the sprayed state, the result indicated the presence of 54.6% gamma alumina phase. However, after the thermal cycling test on the laser modified surface, 70.5% \u0026gamma;-alumina phase was found. Comparing the sprayed and laser-modified alumina surfaces after the thermal cycling test under the same conditions, the sprayed sample contained 81.6% \u0026gamma;-alumina, while the laser-modified sample contained 70.5% \u0026gamma;-alumina. Similar to the result from the thermal gradient test, the laser surface modification resulted in a 15.7% increase in phase stability.\u003c/p\u003e\n\u003cp\u003e3.5.2.2. Microstructure Analysis After Thermal Cycling Test\u003c/p\u003e\n\u003cp\u003eAs observed in the surface microstructure of the CYSZ sample, it was found that the CMAS and hot corrosion dusts melted at 1200 \u0026deg;C and spread over the entire surface and distributed over the coating (Fig. 11 (a)). No damage was observed on the surface during the microstructural examination; however, to analyze penetration and damage, the cross-sectional microstructure of the coatings was examined (Fig. 11). In the cross-sectional microstructure shown in Figure 11 (b), cracks formed on the CYSZ sample surface after laser surface modification are seen to expand and penetrate deeper into the coating under the influence of CMAS and hot corrosion components. The cracks, which extend to the interface between the ceramic layer and the bond coat, are thought to oxidize the bond coat and cause the coating to delaminate. In Figure 11 (c), looking at the edges of the coating, it is observed that the surface crack progresses along the bond coat, with the metal substrate experiencing greater thermal expansion while the ceramic layer experiences less thermal expansion. As a result, the substrate extends from under the ceramic layer, causing separation at the metal-ceramic interface.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn Figure 11(d), semi-molten and molten regions of CMAS and hot corrosion melts are observed on the laser-modified surface of the FG sample after the thermal cycling test. The thermal cycling effects are not clearly distinguishable from the surface morphology. However, by examining Fig. 11(e), the formation of stress due to solidification of CMAS and hot corrosion melts at lower temperatures near the coating surface is shown, leading to coating damage and crack propagation. Similar to the CYSZ sample, delamination at the ceramic-metal bond coat interface due to thermal expansion mismatch is observed in Figure 11.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 12 shows the EDS mapping images of the cross-sectional microstructures of two samples after thermal cycling following laser surface modification. The penetration of CMAS and hot corrosion melts is clearly identified, and the presence of the corrosion-causing V element is observed in the Zr-rich regions of both samples. The Si penetration is also higher in the CYSZ sample compared to the FG sample. Researchers have reported that SiO2 has a very detrimental effect during thermal cycling. SiO2 decomposes at zirconia grain boundaries and accumulates excessively, resulting in localized grain boundary degradation [28]. The initial formation of the surface crack seen in Figure 12 (a) is believed to be due to the regional concentration of Si elements. The addition of alumina is shown to reduce the effects of CMAS, and the hot corrosion dust + salt mixture in thermal barrier coatings (Fig. 12 (b)) shows the separation of the coating from the bond coat.\u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe CMAS and hot corrosion properties of CYSZ and FG TBCs were retested after laser surface modification using two different test methods (thermal gradient and thermal cycling).\u003c/p\u003e\n\u003cp\u003e- Thermal gradient testing was performed on both designs at 1200\u0026deg;C with CMAS and hot corrosion salts using a CO2 laser. After 1 hour of testing, the FG design showed better performance due to a lower TGO layer and higher design stability.\u003c/p\u003e\n\u003cp\u003e- Both designs were subjected to thermal cycling tests at 1200\u0026deg;C with CMAS and hot corrosion salts using a CO2 laser. After 100 cycles, both designs showed improved protection due to the laser surface modification.\u003c/p\u003e\n\u003cp\u003eTo understand vanadium corrosion before and after laser surface modification, Rietveld analysis was performed on the surface and behind the ceramic layer of the TBCs. Before laser surface modification, a 64% monoclinic transformation was calculated, while a 12% monoclinic transformation was observed in the CYSZ TBC. However, no phase transformation occurred in either design (CYSZ and FG) after the thermal cycling or thermal gradient tests due to the laser surface modification.\u003c/p\u003e\n\u003cp\u003e- Laser surface modification positively affected the corrosion properties of the TBC surfaces, and no monoclinic transformation was observed in either type of TBC after laser surface modification.\u003c/p\u003e\n\u003cp\u003e- Laser surface modified functionally graded (FG) TBCs were found to have better properties than single-layer CYSZ according to the results of CMAS and hot corrosion tests.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank Prof. Dr. Gultekin Goller and Hasan Huseyin Sezer for their contributions to the thermal spray and characterization process. The authors also thank Prof. Dermot Brabazon and Merve Nur Dogu at Dublin City University (DCU) for his support on SEM-EDS mapping analyses\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Aproval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere is no ethically problem with the samples or other datas included in manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFundings\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere is no funding for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll data are available for the journal.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThere is no competing interest. Manuscript is propried by one author. It is me Fatih KIRBIYIK. There is no other competing author for this manuscript.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eFeng J, Wu J, Guo L, Guo H. Finite element analysis on temperature field and stress distribution of thermal barrier coatings by laser modification and CMAS corrosion. Corrosion Communications 2022;6:29\u0026ndash;39. https://doi.org/10.1016/j.corcom.2021.12.002.\u003c/li\u003e\n \u003cli\u003eBakkar S, Pantawane MV, Gu JJ, Ghoshal A, Walock M, Murugan M, et al. Laser surface modification of porous yttria stabilized zirconia against CMAS degradation. Ceram Int 2020;46:6038\u0026ndash;45. https://doi.org/10.1016/j.ceramint.2019.11.061.\u003c/li\u003e\n \u003cli\u003eBakkar S, Pantawane MV, Gu JJ, Ghoshal A, Walock M, Murugan M, et al. Laser surface modification of porous yttria stabilized zirconia against CMAS degradation. Ceram Int 2019. https://doi.org/10.1016/J.CERAMINT.2019.11.061.\u003c/li\u003e\n \u003cli\u003eGuo L, Gao Y, Cheng Y, Sun J, Ye F, Wang L. Microstructure design of the laser glazed layer on thermal barrier coatings and its effect on the CMAS corrosion. Corros Sci 2021;192. https://doi.org/10.1016/j.corsci.2021.109847.\u003c/li\u003e\n \u003cli\u003eOxidation and hot corrosion of thermal barrier coatings (TBCs). n.d.\u003c/li\u003e\n \u003cli\u003eZhong XH, Wang YM, Xu ZH, Zhang YF, Zhang JF, Cao XQ. Hot-corrosion behaviors of overlay-clad yttria-stabilized zirconia coatings in contact with vanadate-sulfate salts. J Eur Ceram Soc 2010;30:1401\u0026ndash;8. https://doi.org/10.1016/j.jeurceramsoc.2009.10.017.\u003c/li\u003e\n \u003cli\u003eEliaz N, Shemesh G, Latanision RM. Hot corrosion in gas turbine components. Eng Fail Anal 2002;9:31\u0026ndash;43. https://doi.org/10.1016/S1350-6307(00)00035-2.\u003c/li\u003e\n \u003cli\u003eCao XQ, Vassen R, Stoever D. Ceramic materials for thermal barrier coatings. J Eur Ceram Soc 2004;24:1\u0026ndash;10. https://doi.org/10.1016/S0955-2219(03)00129-8.\u003c/li\u003e\n \u003cli\u003eAl Harbi N, Benyounis KY, Looney L, Stokes J. Laser Surface Modification of Ceramic Coating Materials. Encyclopedia of Smart Materials, Elsevier; 2018, p. 445\u0026ndash;61. https://doi.org/10.1016/B978-0-12-803581-8.11386-4.\u003c/li\u003e\n \u003cli\u003eKirbiyik F, Gok MG, Goller G. Microstructural, mechanical and thermal properties of Al 2 O 3 /CYSZ functionally graded thermal barrier coatings. Surf Coat Technol 2017;329:193\u0026ndash;201. https://doi.org/10.1016/j.surfcoat.2017.08.025.\u003c/li\u003e\n \u003cli\u003eHarbi N Al, Benyounis KY, Looney L, Stokes J. Laser Surface Modification of Ceramic Coating Materials. Encyclopedia of Smart Materials, Elsevier; 2021, p. 445\u0026ndash;61. https://doi.org/10.1016/B978-0-12-803581-8.11386-4.\u003c/li\u003e\n \u003cli\u003eGok MG, Goller G. Microstructural evaluation of laser remelted gadolinium zirconate thermal barrier coatings. Surf Coat Technol 2015;276:202\u0026ndash;9. https://doi.org/10.1016/j.surfcoat.2015.06.074.\u003c/li\u003e\n \u003cli\u003eVarghese P, Vetrivendan E, Krupa BRV, Shukla PK, Gupta RK, Rao EH, et al. Degradation of thermally sprayed Al2O3 coatings in reactor-grade liquid-sodium and its mitigation by laser treatment. Ceram Int 2022;48:13914\u0026ndash;26. https://doi.org/10.1016/j.ceramint.2022.01.276.\u003c/li\u003e\n \u003cli\u003eWellman RG, Nicholls JR. Erosion, corrosion and erosion-corrosion of EB PVD thermal barrier coatings. Tribol Int 2008;41:657\u0026ndash;62. https://doi.org/10.1016/j.triboint.2007.10.004.\u003c/li\u003e\n \u003cli\u003eHuo K, Zhao Y, Hua Y, Cai J, Ye Y, Dai F. Study of CMAS wettability, penetration, and degradation behaviors on EB-PVD 8YSZ coatings laser micro-glazed (LMGed) by an ultraviolet picosecond ultrashort pulsed laser. Surf Coat Technol 2024;489. https://doi.org/10.1016/j.surfcoat.2024.131136.\u003c/li\u003e\n \u003cli\u003eHuo K, Zhao Y, Hua Y, Cai J, Ye Y, Dai F. Study of CMAS wettability, penetration, and degradation behaviors on EB-PVD 8YSZ coatings laser micro-glazed (LMGed) by an ultraviolet picosecond ultrashort pulsed laser. Surf Coat Technol 2024;489. https://doi.org/10.1016/j.surfcoat.2024.131136.\u003c/li\u003e\n \u003cli\u003eWu J, Gao Y, Guo C, Guo L. Laser surface modification to improve the resistance of CMAS + molten salt coupling corrosion to thermal barrier coatings. Ceram Int 2023;49:32282\u0026ndash;91. https://doi.org/10.1016/j.ceramint.2023.07.203.\u003c/li\u003e\n \u003cli\u003eGuo L, Gao Y, Cheng Y, Sun J, Ye F, Wang L. Microstructure design of the laser glazed layer on thermal barrier coatings and its effect on the CMAS corrosion. Corros Sci 2021;192. https://doi.org/10.1016/j.corsci.2021.109847.\u003c/li\u003e\n \u003cli\u003eHuo K, Qian W, Cai J, Ye Y, Hua Y, Zhang X, et al. The hot corrosion resistance of APS YSZ coatings micro glazed via an ultraviolet picosecond ultrashort pulsed laser. Corros Sci 2023;222. https://doi.org/10.1016/j.corsci.2023.111435.\u003c/li\u003e\n \u003cli\u003eJackson RW, Begley MR. Critical cooling rates to avoid transient-driven cracking in thermal barrier coating (TBC) systems. Int J Solids Struct 2014;51:1364\u0026ndash;74. https://doi.org/10.1016/j.ijsolstr.2013.12.029.\u003c/li\u003e\n \u003cli\u003eGuo L, Xin H, Zhang Z, Zhang X, Ye F. Microstructure modification of Y2O3 stabilized ZrO2 thermal barrier coatings by laser glazing and the effects on the hot corrosion resistance. Journal of Advanced Ceramics 2020;9:232\u0026ndash;42. https://doi.org/10.1007/s40145-020-0363-z.\u003c/li\u003e\n \u003cli\u003eAhmadi-Pidani R, Shoja-Razavi R, Mozafarinia R, Jamali H. Improving the thermal shock resistance of plasma sprayed CYSZ thermal barrier coatings by laser surface modification. Opt Lasers Eng 2012;50:780\u0026ndash;6. https://doi.org/10.1016/j.optlaseng.2011.12.007.\u003c/li\u003e\n \u003cli\u003eIlyinkova TA, Baldaev SL, Fedorova MO. Laser modification of thermal barrier coatings. Strengthening Technologies and Coatings 2024:114\u0026ndash;9. https://doi.org/10.36652/1813-1336-2024-20-3-114-119.\u003c/li\u003e\n \u003cli\u003eReza MS, Aqida SN, Mohd Toff MR. An Investigation of Phase Crystallinity in Laser Modified Yttria Stabilized Zirconia (YSZ) Thermal Barrier Coating\u0026amp;lt;sup\u0026amp;gt;\u0026amp;lt;/sup\u0026amp;gt; Key Eng Mater 2014;611\u0026ndash;612:1601\u0026ndash;7. https://doi.org/10.4028/www.scientific.net/KEM.611-612.1601.\u003c/li\u003e\n \u003cli\u003eAvcı A, Karabaş M, Akdoğan Eker A, Akman E, Aslan C. Improvement of CMAS resistance of laser glazed and nano-modified YSZ thermal barrier coatings. Ceram Int 2024;50:9985\u0026ndash;99. https://doi.org/10.1016/j.ceramint.2023.12.228.\u003c/li\u003e\n \u003cli\u003eVarghese P, Vetrivendan E, Krupa BRV, Shukla PK, Gupta RK, Rao EH, et al. Degradation of thermally sprayed Al2O3 coatings in reactor-grade liquid-sodium and its mitigation by laser treatment. Ceram Int 2022;48:13914\u0026ndash;26. https://doi.org/10.1016/j.ceramint.2022.01.276.\u003c/li\u003e\n \u003cli\u003eTorkashvand K, Poursaeidi E, Mohammadi M. Effect of TGO thickness on the thermal barrier coatings life under thermal shock and thermal cycle loading. Ceram Int 2018;44:9283\u0026ndash;93. https://doi.org/10.1016/j.ceramint.2018.02.140.\u003c/li\u003e\n \u003cli\u003eMa W, Dong H. Ceramic thermal barrier coating materials. Thermal Barrier Coatings, Elsevier; 2011, p. 25\u0026ndash;52. https://doi.org/10.1533/9780857090829.1.25.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u0026nbsp;\u003c/strong\u003eAPS and HVOF spraying parameters of ceramic top coats and NiCoCrAlY.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eParameters\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003eCYSZ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003eCYSZ +\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003eNiCoCrAlY\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eHydrogen flow rate (l/min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eArgon flow rate (l/min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eAmpere (A)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e400\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e450\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e450\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eVoltage (V)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eOxygen flow rate (SLPM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eAir flow rate (SLPM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003ePropane flow rate (SLPM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eSpray distance (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003eSpray angle to surface (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 166px;\"\u003e\n \u003cp\u003ePowder feed (lb/min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 70px;\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e7.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp id=\"_Toc124465840\"\u003e\u003cstrong\u003eTable 2.\u0026nbsp;\u003c/strong\u003eCMAS powders XRF analysis results.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"86%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003eCaO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11px;\"\u003e\n \u003cp\u003eAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003eMgO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003eTiO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003eOther\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e29.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e28.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e19.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e9.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e2.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e4.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e3.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e3.54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e. Laser surface modification parameters.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLaser power (W)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLaser power density (W/cm\u003csup\u003e2\u003c/sup\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLaser distance (cm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLaser spot diameter (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLaser scanning speed (mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCYSZ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e360\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e170\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFG\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e380\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 101px;\"\u003e\n \u003cp\u003e170\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"lasers-in-manufacturing-and-materials-processing","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"lmmp","sideBox":"Learn more about [Lasers in Manufacturing and Materials Processing](http://link.springer.com/journal/volumesAndIssues/40516)","snPcode":"40516","submissionUrl":"https://submission.nature.com/new-submission/40516/3","title":"Lasers in Manufacturing and Materials Processing","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Laser surface modification, TBC, Al2O3, CYSZ, Thermal test","lastPublishedDoi":"10.21203/rs.3.rs-6040852/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6040852/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"This study investigates the effects of laser surface modification on the corrosion resistance and thermal performance of thermal barrier coatings (TBCs) exposed to calcium-magnesium-aluminosilicate (CMAS) and hot corrosion environments. Two TBC designs, single-layered ceria-yttria-stabilized zirconia (CYSZ) and a functionally graded Al2O3/CYSZ (FG) structure, were investigated through thermal gradient and thermal cycling tests at 1200 °C. Laser surface modification significantly improved the microstructure and mechanical properties, including a twofold increase in microhardness for CYSZ and a fourfold increase for the FG design. The modified surfaces showed improved resistance to CMAS penetration and hot corrosion salts, with reduced tetragonal to monoclinic phase transformation and improved phase stability. Microstructural analysis revealed stress-induced delamination in CYSZ due to CMAS infiltration, while FG TBCs exhibited better performance with minimal coating failure and improved thermal expansion compatibility. After modification, both designs maintained high durability, withstanding up to 100 thermal cycles without significant delamination. The results highlight the superior corrosion resistance and thermal stability of laser surface modified FG TBCs, demonstrating their potential for extended life in high temperature applications.","manuscriptTitle":"Laser surface modification of Al 2 O 3 / CYSZ functionally graded TBC against CMAS and hot corrosion damage","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-21 17:35:06","doi":"10.21203/rs.3.rs-6040852/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-07-29T14:44:17+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-29T14:36:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"226962674474638107431957154514671639655","date":"2025-07-03T09:04:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"86087393121173824954115470645036161152","date":"2025-07-03T00:42:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"213512163705092780697095021183837034273","date":"2025-04-03T20:01:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"305444229639834556398546130292409530748","date":"2025-03-29T04:01:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-10T10:40:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"243767448788474163241121963322149524265","date":"2025-02-22T03:51:31+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-02-19T15:25:55+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-02-19T15:23:10+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-02-19T09:27:26+00:00","index":"","fulltext":""},{"type":"submitted","content":"Lasers in Manufacturing and Materials Processing","date":"2025-02-16T11:25:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"lasers-in-manufacturing-and-materials-processing","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"lmmp","sideBox":"Learn more about [Lasers in Manufacturing and Materials Processing](http://link.springer.com/journal/volumesAndIssues/40516)","snPcode":"40516","submissionUrl":"https://submission.nature.com/new-submission/40516/3","title":"Lasers in Manufacturing and Materials Processing","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d08949c2-88c0-4278-81c3-456328a8a25f","owner":[],"postedDate":"February 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-10-06T16:08:14+00:00","versionOfRecord":{"articleIdentity":"rs-6040852","link":"https://doi.org/10.1007/s40516-025-00315-7","journal":{"identity":"lasers-in-manufacturing-and-materials-processing","isVorOnly":false,"title":"Lasers in Manufacturing and Materials Processing"},"publishedOn":"2025-10-03 15:57:11","publishedOnDateReadable":"October 3rd, 2025"},"versionCreatedAt":"2025-02-21 17:35:06","video":"","vorDoi":"10.1007/s40516-025-00315-7","vorDoiUrl":"https://doi.org/10.1007/s40516-025-00315-7","workflowStages":[]},"version":"v1","identity":"rs-6040852","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6040852","identity":"rs-6040852","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}