Effect of different kinds of SiC fibers on microwave absorption and mechanical properties of SiCf/SiC composites

Effect of different kinds of SiC fibers on microwave absorption and mechanical properties of SiCf/SiC composites | 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 Effect of different kinds of SiC fibers on microwave absorption and mechanical properties of SiC f /SiC composites Zhaowen Ren, Wancheng Zhou, Yuchang Qing, Shichang Duan, Qinlong Wen, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-27933/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 06 Aug, 2020 Read the published version in Journal of Materials Science: Materials in Electronics → Version 1 posted You are reading this latest preprint version Abstract The SiC fibers are essential for designing microwave absorption and mechanical properties of multifunctional composites. In this study, SLF, KD-II and KD-S SiC fibers were used to fabricate SiC f /SiC composites. The SLF SiC fibers are composed by amorphous SiOC. The KD-II and KD-S SiC fibers exhibit higher crystallizations and free carbon content. The conductivity of SLF, KD-II and KD-S SiC fibers are 0.0127, 1.184 and 0.1316 S/cm, respectively. The flexural strength of SLF, KD-II and KD-S SiC f /SiC composites are 147.77, 322.57 and 248.16 MPa, respectively. The microwave absorption property of the SLF SiC f /SiC composites can be obtained over -25 dB with a thickness of 2.3 mm and the effective absorption bandwidth (EAB) below -10 dB reaches 3.72 GHz with the thickness of 2.7 mm. In contrast, the KD-II SiC f /SiC composites only reach -3.6 dB in the whole X band when the thickness varies from 2 to 2.9 mm. KD-S SiC f /SiC composites can be obtained over -9dB with the thickness of 2mm and the EAB below -7 dB reaches 4.12 GHz with a thickness of 2.2 mm. The mechanisms of mechanical, microwave absorption and penitential applications for SiC f /SiC composites are also discussed. Ceramics SiCf/SiC composites microwave absorption mechanical property SiC fibers Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Nowadays, as the development of microwave technology, electromagnetic pollution usually appears in daily life. Numerous researches have been devoted to designing and implementing excellent electromagnetic absorption materials [ 1 – 5 ] . In recently years, ceramics composites with excellent microwave absorption properties have increasingly attracted attentions, such as SiC nanowires reinforced SiOC ceramic, Si 3 N 4 -SiCN ceramics composites [ 6 ] and Fe 3 O 4 nanoparticles on MXenes [ 7 ] . Continuous fiber reinforced ceramics matrix composites (CFRCMCs) were believed to be the most prospective multifunctional composites due to their high mechanical strength, stability under high temperature, low densities and oxidation resistance properties [ 8 – 10 ] . Therefore, SiC fiber reinforced SiC ceramic matrix composites can be promising candidates of multifunctional materials with microwave absorption and mechanical properties. The microwave absorption and mechanical properties of SiC CFRCMCs depend on complex permittivity, electrical conductivity and free carbon content of SiC fibers, as well as interphase and matrix. The SiC ceramics matrix can be fabricated by chemical vapor infiltration (CVI) [ 11 ] , precursor impregnation and pyrolysis (PIP) [ 12 ] , liquid silicon infiltration (LSI) [ 13 ] and melt infiltration (MI) [ 14 ] . Among these techniques, the PIP method has many advantages, for instance, the designable molecular precursor of polymer derived ceramics (PDC), safe in operation and the feasibility of manufacture in large complex components. Thus, the PIP method should be a better way to fabricate the multifunctional SiC f /SiC composites. Different types of SiC fiber significantly affect the properties of SiC f /SiC composites. Up to now, the SiC fibers have developed three generations [ 15 – 17 ] . The first generation of SiC fibers is Nicalon 200 from Nippon Carbon and Tyranno LOX-M from UBE industries, etc. The second generation of SiC fibers is Hi-Nicalon from Nippon Carbon, Tyranno ZE from UBE Industries, and so on. The third generation of SiC fibers is Tyranno SA 1 from UBE Industries, Sylramic from COI ceramics, and so forth. The oxygen contents in fibers came down as the generation developed. The first generation oxygen content could go as high as 12 wt% with the maximum limit temperature only 1200 °C. The excessive oxygen content of SiC fibers was harmful. Since the active-oxidation could cause coarsening of β-SiC crystals at high temperature [ 18 ] . The oxygen content of the second generation is lower than 2 wt% with enhanced limit temperature of about 1300 °C. However, the second generation also has poor oxidation-resistance property due to the high C/Si ratio of 1.5. The oxygen content of the third generation is lower than 1 wt% with the maximum temperature over 1700 °C and the C/Si ratio only about 1. Moreover, the third generation has high crystallinity and density. The polycrystalline SiC fibers can give rise to better elastic modulus and tensile strength of fibers [ 19 ] . All of the above mentioned SiC fibers are from Japan, America and Germany. However, with the efforts of Chinese researchers, SiC fibers can be fabricated in China at present. In this research, the SLF, KD-II and KD-S SiC fibers are all produced in China and represent first, second and third generation of SiC fibers, respectively. These SiC fibers were used as reinforcements. The polycarbosilane (PCS) was used as precursor of SiC ceramics matrix. In order to avoid the influence of interphase on properties of SiC f /SiC composites, the interphase on the surface of fibers was not fabricated in the present work. We systematically investigated the properties of SiC fibers and the effects of different SiC fibers on microwave absorption and mechanical properties of SiC f /SiC composites. 2. Experimental 2.1 Raw materials of SiC f /SiC composites The SLF fibers and PCS powders were bought from Suzhou CeraFil Ceramic Fiber Co., Ltd. KD-II and KD-S fibers were purchased from the National University of Defense and Technology (NUDT). The general properties of three three types of SiC fibers are listed in Table 1 [ 9 , 20 ] . The SiC fibers were used as reinforcement and fabricated into 2.5D with a volume fraction of 35%. Additionally, the PCS/xylene solution was prepared at 50 wt%. Table 1 properties of KD-S, KD-II and SLF SiC fibers SiC fibers C/Si atomic ratio Bulk density (g/cm 3 ) Diameter (µm) Tensile strength (GPa) Tensile modulus (GPa) KD-S 1.05 2.85 11 2.6 320 KD-II 1.4 2.75 12 2.9 280 SLF / 2.47 12 2.2 185 2.2 Preparation of SiC f /SiC composites with different SiC fibers Firstly, these three kinds of 2.5D SiC fibers were ultrasonic cleared in acetone solution for 15 min. Afterwards, the 2.5D SiC fibers were dipped into PCS/xylene solution for 30 min in the vacuum infiltration oven and then dried at 80 °C for 3 h in the vacuum drying oven. After dried, the samples were pyrolyzed in a vacuum sintering furnace at 1000 °C for 2 h. SiC f /SiC composites were fabricated by the PIP procedure and repeated until the weight gain less than 1% per cycle. 2.3 Characterization of SiC f /SiC composites The density and open porosity of these SiC f /SiC composites were measured by Archimedes’ principle. Phase compositions of SiC fibers were analyzed by X-ray diffraction (X'Pert PRO MPD, PANalytical. Almelo, the Netherlands, Cu-Kα radiation). The crystalline grain size L of SiC fibers was calculated by Scherrer’s Equation [ 21 ] : where B is the full width at half maximum (FWHM) of the (1 1 1) peak. θ is the Bragg’s diffraction angle. K is the Scherrer’s constant. λ is the X-ray wavelength. Additionally, the crystallinity of SiC fibers was calculated by the following equation with XRD spectra: where I c represents the crystal diffraction peak area. I a represents amorphous diffraction peak area. The judging standard of crystal diffraction peak is FWHM less than 3.0. The flexural strength of the SiC f /SiC composites was characterized by the three-point-bending method using a universal testing machine (Haida Qualitative Analysis, HD-609B) at room temperature. Mechanical samples were cut into 40mm × 4mm × 3 mm. This universal testing machine had a cross head speed of 0.5 mm/min with a span of 30 mm. The surface of SiC fibers and fracture surfaces of SiC f /SiC composites were observed by scanning electron microscope (Model VEGA3 SBH, TESCAN, Brno, Czech) with energy dispersion spectroscopy (EDS). The conductivity of SiC fibers can be calculated by the equation: where L and S is the length and cross section area of a bunch of SiC fibers, respectively. One bunch of fibers consisted of 1000 SiC fibers. R is the resistance of one bunch of SiC fibers, which was measured by a resistant tester. The complex permittivity of SiC f /SiC composites was measured at the frequency between 8.2 and 12.4 GHz using the waveguide method with a vector network analyzer (Agilent Technologies E8362B). The dimension of complex permittivity samples was 22.86mm × 10.16mm × 2.0 mm. 3. Results And Discussion 3.1 Microstructure of SiC fibers The surface and cross-section morphologies of different SiC fibers are shown in Fig. 1 . The surface of the SiC fibers is smooth and homogeneous. The diameters of SiC fibers are all about 12 µm. The SiC fibers were cut to observe cross-section, which was shown a dense morphology. Many particles with a small size can be seen on the cross-section of fibers. Compositional elements of surface and cross-section of different SiC fibers at selected regions in Fig. 1 were measured by EDS, seen in Fig. 2 . By comparing SLF, KD-II and KD-S SiC fibers, Fig. 2 (a) and (b) show that the content of oxygen element in SLF fibers is 17.21% on the surface and 10.36% in cross-section. Therefore, SLF SiC fibers satisfy the characteristic of high oxygen content in the first generational and process a large amount of SiOC phase [ 22 ] . In contrast, the oxygen content of KD-S SiC fibers is only 2.34% on surface and 3.03% in cross-section. The content of Si element increased with the content of oxygen element decreasing in the SLF, KD-II and KD-S SiC fibers. Additionally, from SLF, KD-II to KD-S, the ratio of C/Si is reduced. However, the content of C element in KD-II SiC fibers is the highest in the cross-section. The different properties of these three types of SiC fibers can be reflected by polycrystalline microstructure [ 19 ] . As shown in Fig. 3 , the XRD revealed the crystalline structure of different SiC fibers. The crystallinity and crystallite size of β-SiC crystallite for SLF, KD-II and KD-S SiC fibers are shown in Table 2 . The XRD patterns demonstrate that the microstructures of SiC fibers are mainly formed by β-SiC at peaks of 35.74°, 41.50°, 60.14°, 71.97° and 75.71°, which are indexed to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) lattices, respectively. It can be seen that the SLF SiC fibers present three main diffraction peaks at 35.74°, 60.14° and 71.97°, which were assigned to the (1 1 1), (2 2 0) and (3 1 1) planes of the amorphous β-SiC phase, respectively. The sharp XRD peaks observed for the KD-II and KD-S SiC fibers clearly confirm the larger crystallite size (4.4 nm and 4.1 nm) of β-SiC than that of the SLF SiC fibers (1.4 nm). Moreover, other peaks were indexed as the (2 0 0) and (2 2 2) planes of the β-SiC appeared in KD-II and KD-S SiC fibers. As same as the first generation of SiC fibers, the SLF fibers are almost amorphous, according to the broad minor peaks [ 23 ] . In contrast, the KD-II and KD-S SiC fibers have high crystallinity with 83.92% and 87.76%, respectively. Thanks to the amorphous phase and high oxygen content, the free carbon conductive network in the SLF fibers will be separated by Si-C-O phase [ 16 ] . Therefore, as shown in Table 3 , the conductivity of SLF fibers is only 0.0127 S/cm. The conductivity of KD-II fibers is 1.1811 S/cm owing to the larger C/Si atomic ratio [ 19 ] and the conductive network of carbon-rich layers. The conductivity of KD-S fibers is 0.1316 S/cm due to the lower C and O content. Table 2 Crystallinity and crystallite size of β-SiC for SLF, KD-II and KD-S SiC fibers Properties SLF KD-II KD-S Crystallinity (%) ≈ 0 83.92 87.76 Crystallite size (nm) 1.4 4.4 4.1 Table 3 Conductivity of SLF, KD-II and KD-S SiC fibers SLF KD-II KD-S Conductivity(S/cm) 0.0127 1.1811 0.1316 3.2 Mechanical properties and microstructure of SiC f /SiC composites Mechanical properties of SiC f /SiC composites with SLF, KD-II and KD-S SiC fibers are listed in Table 4 . The flexure strength of the KD-S and KD-II SiC f /SiC composites are 248.16 MPa and 322.57 MPa, respectively. The KD-II SiC f /SiC composites exhibited the best mechanical properties comparing to the SLF and KD-S SiC f /SiC composites, owing to the fact that massive free carbon networks generated by the high content of C in the KD-II SiC fibers. Under the same fabricating condition, the density and open porosity of SLF, KD-II and KD-S SiC f /SiC composites are pretty similar. However, the flexure strength of SLF SiC f /SiC composites is only 147.77 MPa. It indicates that the growth of crystallites and high crystallinity are beneficial to enhance the flexure strength of SiC f /SiC composites. Table 4 Properties of SiC f /SiC composites SLF, KD-II and KD-S SiC fibers SiC f /SiC composites Density (g/cm 3 ) Open porosity (%) Flexural strength (MPa) Displacement (mm) SLF 1.99 12.2 147.77 0.240 KD-II 2.13 12.5 322.57 0.333 KD-S 1.98 13.04 248.16 0.275 The stress-displacement curves obtained from the bending test for SiC f /SiC composites with different kinds of SiC fibers are shown in Fig. 4 . The load on the SLF, KD-II and KD-S SiC f /SiC composites decreases sharply as reaching the peak value. It is revealed that all kinds of SiC fibers reinforced SiC f /SiC composites appear a typical brittle fracture behavior. It can be concluded that the bonding strength between three types of SiC fibers and the matrix was strong. The fracture morphologies of SiC f /SiC composites with SLF, KD-II and KD-S fibers were shown in Fig. 5 . As illustrated in Fig. 5 (a), the fracture surface of SLF SiC f /SiC composites was plane and there are no fibers pull-out phenomenon appearance due to the strong bonding at the surface between matrix and SLF SiC fibers. The fracture surface of KD-II SiC f /SiC composites exhibits step-shaped appearances, shown in Fig. 5 (b). In Fig. 5 (c), the step-shaped fracture and fibers pull-out can be discovered in the fracture surface of KD-S. According to the fracture morphologies, the matrix densification of SLF, KD-II and KD-S SiC f /SiC composites are similar. With the same content of matrix and SiC fibers in SiC f /SiC composites, the different mechanical properties should be caused by different kinds of SiC fibers. 3.3 Dielectric properties of SiC f /SiC composites with different SiC fibers The complex permittivity ( ε = ε’-jε’’ ) of SiC f /SiC composites with various SiC fibers was measured at the frequency range of X band (8.2–12.4 GHz). The real part of permittivity ( ε’ ) is correlated with polarization and the imaginary part of permittivity ( ε’’ ) in reference to the ability of dielectric loss and electrical conductivity [ 24 ] . The loss tangent (tanδ) of SiC f /SiC composites were calculated by tanδ = ε’/ε’’ [ 25 ] , which represents the microwave absorption ability of SiC f /SiC composites [ 26 ] . As shown in Fig. 4 , both the real and imaginary permittivity of KD-II SiC f /SiC composites reveal a decreasing trend as the frequency increases in the whole X band. It can be indicated that the KD-II SiC f /SiC composites possess frequency dispersion effect and a broad microwave absorption band. The complex permittivity of SLF and KD-S SiC f /SiC composites almost keeps constant in the measured range, in which the values are 7.9-4.0j and 11.6-9.2j at the frequency of 10 GHz respectively. Compared with SLF and KD-S SiC f /SiC composites, the KD-II SiC f /SiC composites possess much higher imaginary permittivity and loss tangent. The real and imaginary part of permittivity of KD-II SiC f /SiC composites is 12.6 and 25.0 at 10 GHz, respectively, and the loss tangent of it is in the range of 1.7–2.2 in the whole X band. It suggests that the KD-II SiC f /SiC composites has the strongest microwave absorption ability. The SiC f /SiC composites are composited by SiC fibers, interface and SiC matrix. Therefore, the real and imaginary permittivity of SiC f /SiC composites can be illustrated as Lichtencker’s logarithmic equations [ 8 , 24 ] : where v f , v m and v i are volume contents, ε’ f , ε’ m and ε’ i are real permittivities, and ε’’ f , ε’’ m and ε’’ i imaginary permittivities of SiC fiber, SiC matrix and interface, respectively. In this experiment, the interface was not fabricated and the porosity and density of SiC matrix was similar as shown in Table 4 . Additionally, the SLF, KD-II and KD-S SiC fibers were all fabricated into 2.5D with volume fraction of 35% and the process of manufacture SiC f /SiC composites was under the same experimental condition. Consequently, the real and imaginary part of SiC f /SiC composites are mainly dependent on SiC fibers. On the one hand, there are lots of interfaces around SiC nano-crystals, free carbons and amorphous SiOC phase. Additionally, the dipoles from defect in SiC nano-crystals and free carbons in SiC fibers [ 24 ] . The KD-II and KD-S SiC fibers with high crystallinity have more grain boundaries and free carbons. Therefore, the higher real permittivity of KD-II and KD-S SiC f /SiC composites owing to the polarization from interfaces among the grain boundary and dipoles in the KD-II and KD-S SiC fibers under the X band. On the other hand, according to the Debye theory [ 27 ] , the imaginary part of permittivity can be decided by the conductivity, which can be calculated by the following equation: where σ is the electrical conductivity, ε 0 is the dielectric constant in vacuum and f is the frequency of the electromagnetic wave. According to the above analysis, the imaginary part of permittivity of SiC f /SiC composites in this experiment is proportional to the conductivity of SiC fibers. As shown in Table 3 , the conductivity of KD-II SiC fibers 1.1811 S/cm is the highest. Therefore, the higher electrical conductivity of KD-II SiC fibers gives rise to the larger imaginary part of KD-II SiC f /SiC composites. 3.4 Microwave absorption properties of SiC f /SiC composites The microwave absorption property of SLF, KD-II and KD-S SiC f /SiC composites are evaluated by the reflection loss (RL) values, which is based on the transmission line theory. The RL values can be calculated as the following equations: where Z 0 is the characteristic impedance of free space, Z in is the input impedances of the interface between SiC f /SiC composites and free space. µ 0 and ε 0 are the permeability and permittivity of vacuum. µ r and ε r are the measured relative permeability and permittivity. Because of negligible magnetic properties of SiC, the value of µ r , in this experiment, is taken as 1. Consequently, the RL values of dielectric microwave absorption SiC f /SiC composites can be calculated by complex permittivity and thickness in X band. Generally, the high loss tangent can give rise to the better microwave absorption abilities. However, the optimum impedance matching between the free space and the surface of microwave absorption material leads microwave reflection reduced, and then enhanced the energy loss of the incident microwave. For optimum matching impedance, it demands that the input impedance Z in equal with free space impedance Z 0 as far as possible. The input impedance Z in of SLF, KD-II and KD-S SiC f /SiC composites with a thickness of 2.9 mm are shown in Fig. 5 . The Z in value of the KD-II SiC f /SiC composites is in the range of 63.15–75.12 Ω. The higher difference between Z in and Z 0 leads to the stronger reflection of incident microwave on the surface of the SiC f /SiC composites. Therefore, the KD-II SiC f /SiC composites possess poor microwave absorbing properties, as shown in Fig. 6 (c) and (d). In X band, the KD-II SiC f /SiC composites has only − 3.6 dB RL values from 2 to 2.9 mm thickness and there is no reflection loss peak appearance. On the contrary, the Z in value of SLF SiC f /SiC composites is the highest, in the range of 328.65–178.70 Ω, and processes the lowest deviation between Z in and Z 0 . As a consequence, most of the microwave incidence into SLF SiC f /SiC composites. As shown in Fig. 6 (a) and (b), the RL values of SLF SiC f /SiC composites can be obtained over − 25 dB with a thickness of 2.3 mm and the effective absorption bandwidth (EAB) below − 10 dB reaches 3.72 GHz (from 8.68 to 12.40 GHz) with a thickness of 2.7 mm. The Z in value of the KD-S SiC f /SiC composites is in the range of 141.80-85.39 Ω. That deviation between Z in and Z 0 is higher than that of KD-II SiC f /SiC composites and lower than that of SLF SiC f /SiC composites. As shown in Fig. 6 (c) and (f), the RL values of KD-S SiC f /SiC composites can be obtained over − 9dB with a thickness of 2 mm and the EAB below − 7 dB reaches 4.12 GHz (from 8.28 GHz to 12.40 GHz), indicating more than 84% microwave absorption [ 26 ] , with the thickness of 2.2 mm. With the same SiC matrix, the SLF SiC f /SiC composites possess the optimum microwave absorption property due to the amorphous Si-O-C structure and low conductivity of SLF fibers. Additionally, the interfacial polarization is generated by the massive amount of amorphous SiOC and free carbon in SLF fibers. When microwave propagates into the SLF SiC f /SiC composites, a large number of dipoles generated from free carbon, amorphous SiOC and amorphous SiC. The dipoles could cause displacement polarization or steering polarization with the changed electromagnetic wave. The dipoles polarization gradually lagged behind the changes. At this time, the energy of electromagnetic wave can be consumption [ 4 , 28 ] . Instead, a large amount of interface generated between free carbon in the KD-II and KD-S fibers lead displacement polarization or steering of dipoles easy and consume less electromagnetic wave energy under the alternating microwave. 4. Conclusion In summary, the SiC f /SiC composites fabricated with SLF, KD-II and KD-S SiC fibers by PIP method have similar density and open porosity values. The SLF SiC fiber possessed a large amount of oxygen and amorphous phase. The KD-II and KD-S SiC fiber exhibit higher crystallizations and higher free carbon contents than SLF SiC fibers. KD-II SiC f /SiC composites have the highest flexural strength with a value of 322.57 MPa and possess the worst microwave absorption property owing to the massive carbon in the fibers. SLF SiC f /SiC composites possess the best microwave absorption property due to the best impedance matching with air and the lowest flexural strength can be ascribed to the poor strength of SLF SiC fibers. The microwave absorption property of the SLF SiC f /SiC composites can be obtained over − 25 dB with a thickness of 2.3 mm and the effective absorption bandwidth (EAB) below − 10 dB reaches 3.72 GHz with a thickness of 2.7 mm, indicating its potential application in the structural and absorbing field. Above all, the SLF SiC fiber can be used as reinforcement for microwave absorption structure composites. But the interphase on the surface of SLF SiC fibers was necessary to the flexural strength enhancement. Because of the high loss tangent and mechanical property, KD-II SiC fibers are better used as the absorption layer in the multi-layered radar absorbing structures composites field. The KD-S SiC fibers possess medium levels of microwave absorption and mechanical properties. Therefore, further studies should focus on the matrix and interphase modification of KD-S composites. 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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-27933","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":563751,"identity":"9a416f50-b032-4deb-9719-43970b7e0979","order_by":1,"name":"Zhaowen Ren","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYJCCAx8MJOQYGBgbD8BEJAjoYHw4o8DCGEg3EK2F2ZjnQ0ViA8g6orSY958xk+YxkEhf23644QDjjsN5BgeYD97mYbDLw6VF5sAZM8k5BhK5284kArWcOVxscIAt2ZqHIbkYlxYJxt5tEm9AWg6AtLTdTtxwgAdoL8MBsFOxamHm3SYBcpjZ+YcwLfzf8Gth491sCNSSYHYDYQsbfi08/B8fzjCQMNx2A2hLYtv/YsnDbMaWcwyScWvhP5Zw4MOfOnmz8+kPH3xsS8vjO9788MabCjucWlBBAggxg1gGRKmH6xoFo2AUjIJRgAoAEIJdnHcFaV0AAAAASUVORK5CYII=","orcid":"","institution":"Northwestern Polytechnical University School of Science","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Zhaowen","middleName":"","lastName":"Ren","suffix":""},{"id":563752,"identity":"a293888d-99a1-42b0-9302-e7399885bc1b","order_by":2,"name":"Wancheng Zhou","email":"","orcid":"","institution":"State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, Shaaxi, China","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Wancheng","middleName":"","lastName":"Zhou","suffix":""},{"id":563753,"identity":"877c8b11-33a9-4f8a-bcae-213d6777011d","order_by":3,"name":"Yuchang Qing","email":"","orcid":"","institution":"State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, China","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yuchang","middleName":"","lastName":"Qing","suffix":""},{"id":563754,"identity":"484172d2-6519-4c30-8c51-ecd6bdf0d138","order_by":4,"name":"Shichang Duan","email":"","orcid":"","institution":"Shaanxi Huaqin Technology Industry Co., Ltd.","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shichang","middleName":"","lastName":"Duan","suffix":""},{"id":563755,"identity":"0368a358-1ea3-4ced-8c12-66b10bb07702","order_by":5,"name":"Qinlong Wen","email":"","orcid":"","institution":"Northwestern Polytechnical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Qinlong","middleName":"","lastName":"Wen","suffix":""},{"id":563756,"identity":"cde947f4-adaf-41da-8900-2d8bddd89d7c","order_by":6,"name":"Yingying Zhou","email":"","orcid":"","institution":"School of Materials Engineering, Xi'an Aeronautical University, Xi'an 710077","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yingying","middleName":"","lastName":"Zhou","suffix":""},{"id":563757,"identity":"bfb5b375-0b39-4a21-83dd-66b764a87f44","order_by":7,"name":"Yanyu Li","email":"","orcid":"","institution":"State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072Northwestern Polytechnical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yanyu","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2020-05-08 08:51:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-27933/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-27933/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10854-020-04129-5","type":"published","date":"2020-08-06T21:01:27+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":1109210,"identity":"efac8a2f-73e1-495e-b78d-0f519c74d7ac","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":377507,"visible":true,"origin":"","legend":"The surface and cross-section morphologies of SLF (a, b), KD-II (c, d) and KD-S (e, f)","description":"","filename":"fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig1.png"},{"id":1109211,"identity":"6a298378-bdff-4906-8784-e084ccdbde9c","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":12728,"visible":true,"origin":"","legend":"Compositional elements analyzed of surface (a) and cross-section (b) of SLF, KD-II and KD-S SiC fibers by EDS","description":"","filename":"fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig2.png"},{"id":1109212,"identity":"bf330f28-483c-47ef-a7ea-89de4c571a9e","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":19502,"visible":true,"origin":"","legend":"XRD spectra of the SLF, KD-II and KD-S SiC fibers","description":"","filename":"fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig3.png"},{"id":1109213,"identity":"a4701c9d-b202-494a-8d4b-7d8b8838844e","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":19733,"visible":true,"origin":"","legend":"Stress-displacement curves of SiCf/SiC composites with SLF, KD-II and KD-S SiC fibers","description":"","filename":"fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig4.png"},{"id":1109214,"identity":"3fd15b6a-a297-4214-a0ad-28f14534db6a","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":791135,"visible":true,"origin":"","legend":"Fracture surface morphologies of SiCf/SiC composites with different SiC fibers (a) SLF, (b) KD-II and (c) KD-S.","description":"","filename":"fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig5.png"},{"id":1109215,"identity":"43807662-0dd2-4800-9130-bd111dbab45b","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":26292,"visible":true,"origin":"","legend":"The real (a), imaginary (b) part of complex permittivity and loss tangent (c) for SiCf/SiC composites with SLF, KD-II and KD-S SiC fibers","description":"","filename":"fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig6.png"},{"id":1109216,"identity":"bb27360c-6b33-453f-8833-3d3ed2862f03","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":14222,"visible":true,"origin":"","legend":"The characteristic input impedance of SLF, KD-II and KD-S SiCf/SiC composites","description":"","filename":"fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig7.png"},{"id":1109217,"identity":"d1946de6-dfca-42d7-b67b-2291d0322e2c","added_by":"auto","created_at":"2020-05-15 19:30:22","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":311201,"visible":true,"origin":"","legend":"Three-dimensional and detailed maps of RL for SiCf/SiC composites with SLF (a, b), KD-II (c, d) and KD-S (e, f) SiC fibers","description":"","filename":"fig8.png","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/fig8.png"},{"id":15667033,"identity":"d77ab80c-7b60-4db5-b103-c49390018a03","added_by":"auto","created_at":"2021-11-18 13:39:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2031661,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-27933/v1/1f40f6c9-b1f0-4e38-afbc-2d642b0a8032.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eEffect of different kinds of SiC fibers on microwave absorption and mechanical properties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":" \u003cp\u003eNowadays, as the development of microwave technology, electromagnetic pollution usually appears in daily life. Numerous researches have been devoted to designing and implementing excellent electromagnetic absorption materials\u003csup\u003e[\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. In recently years, ceramics composites with excellent microwave absorption properties have increasingly attracted attentions, such as SiC nanowires reinforced SiOC ceramic, Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-SiCN ceramics composites\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles on MXenes\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Continuous fiber reinforced ceramics matrix composites (CFRCMCs) were believed to be the most prospective multifunctional composites due to their high mechanical strength, stability under high temperature, low densities and oxidation resistance properties\u003csup\u003e[\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. Therefore, SiC fiber reinforced SiC ceramic matrix composites can be promising candidates of multifunctional materials with microwave absorption and mechanical properties.\u003c/p\u003e \u003cp\u003eThe microwave absorption and mechanical properties of SiC CFRCMCs depend on complex permittivity, electrical conductivity and free carbon content of SiC fibers, as well as interphase and matrix. The SiC ceramics matrix can be fabricated by chemical vapor infiltration (CVI)\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e, precursor impregnation and pyrolysis (PIP)\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e, liquid silicon infiltration (LSI)\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e and melt infiltration (MI)\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. Among these techniques, the PIP method has many advantages, for instance, the designable molecular precursor of polymer derived ceramics (PDC), safe in operation and the feasibility of manufacture in large complex components. Thus, the PIP method should be a better way to fabricate the multifunctional SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites.\u003c/p\u003e \u003cp\u003eDifferent types of SiC fiber significantly affect the properties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites. Up to now, the SiC fibers have developed three generations\u003csup\u003e[\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. The first generation of SiC fibers is Nicalon 200 from Nippon Carbon and Tyranno LOX-M from UBE industries, etc. The second generation of SiC fibers is Hi-Nicalon from Nippon Carbon, Tyranno ZE from UBE Industries, and so on. The third generation of SiC fibers is Tyranno SA 1 from UBE Industries, Sylramic from COI ceramics, and so forth. The oxygen contents in fibers came down as the generation developed. The first generation oxygen content could go as high as 12\u0026nbsp;wt% with the maximum limit temperature only 1200\u0026nbsp;\u0026deg;C. The excessive oxygen content of SiC fibers was harmful. Since the active-oxidation could cause coarsening of β-SiC crystals at high temperature\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. The oxygen content of the second generation is lower than 2\u0026nbsp;wt% with enhanced limit temperature of about 1300\u0026nbsp;\u0026deg;C. However, the second generation also has poor oxidation-resistance property due to the high C/Si ratio of 1.5. The oxygen content of the third generation is lower than 1\u0026nbsp;wt% with the maximum temperature over 1700\u0026nbsp;\u0026deg;C and the C/Si ratio only about 1. Moreover, the third generation has high crystallinity and density. The polycrystalline SiC fibers can give rise to better elastic modulus and tensile strength of fibers\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. All of the above mentioned SiC fibers are from Japan, America and Germany. However, with the efforts of Chinese researchers, SiC fibers can be fabricated in China at present.\u003c/p\u003e \u003cp\u003eIn this research, the SLF, KD-II and KD-S SiC fibers are all produced in China and represent first, second and third generation of SiC fibers, respectively. These SiC fibers were used as reinforcements. The polycarbosilane (PCS) was used as precursor of SiC ceramics matrix. In order to avoid the influence of interphase on properties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites, the interphase on the surface of fibers was not fabricated in the present work. We systematically investigated the properties of SiC fibers and the effects of different SiC fibers on microwave absorption and mechanical properties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites.\u003c/p\u003e "},{"header":"2. Experimental","content":" \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Raw materials of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites\u003c/h2\u003e \u003cp\u003eThe SLF fibers and PCS powders were bought from Suzhou CeraFil Ceramic Fiber Co., Ltd. KD-II and KD-S fibers were purchased from the National University of Defense and Technology (NUDT). The general properties of three three types of SiC fibers are listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. The SiC fibers were used as reinforcement and fabricated into 2.5D with a volume fraction of 35%. Additionally, the PCS/xylene solution was prepared at 50\u0026nbsp;wt%.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eproperties of KD-S, KD-II and SLF SiC fibers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSiC fibers\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC/Si atomic ratio\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBulk density (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDiameter (\u0026micro;m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTensile strength (GPa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTensile modulus (GPa)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKD-S\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e320\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKD-II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e280\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSLF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e185\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Preparation of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites with different SiC fibers\u003c/h2\u003e \u003cp\u003eFirstly, these three kinds of 2.5D SiC fibers were ultrasonic cleared in acetone solution for 15\u0026nbsp;min. Afterwards, the 2.5D SiC fibers were dipped into PCS/xylene solution for 30\u0026nbsp;min in the vacuum infiltration oven and then dried at 80\u0026nbsp;\u0026deg;C for 3\u0026nbsp;h in the vacuum drying oven. After dried, the samples were pyrolyzed in a vacuum sintering furnace at 1000\u0026nbsp;\u0026deg;C for 2\u0026nbsp;h. SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites were fabricated by the PIP procedure and repeated until the weight gain less than 1% per cycle.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Characterization of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites\u003c/h2\u003e \u003cp\u003eThe density and open porosity of these SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites were measured by Archimedes\u0026rsquo; principle. Phase compositions of SiC fibers were analyzed by X-ray diffraction (X'Pert PRO MPD, PANalytical. Almelo, the Netherlands, Cu-Kα radiation). The crystalline grain size \u003cem\u003eL\u003c/em\u003e of SiC fibers was calculated by Scherrer\u0026rsquo;s Equation\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e:\u003c/p\u003e\u003cp\u003e\u003cimg 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\" style=\"width: 452px;\"\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eB\u003c/em\u003e is the full width at half maximum (FWHM) of the (1 1 1) peak. \u003cem\u003eθ\u003c/em\u003e is the Bragg\u0026rsquo;s diffraction angle. \u003cem\u003eK\u003c/em\u003e is the Scherrer\u0026rsquo;s constant. λ is the X-ray wavelength.\u003c/p\u003e \u003cp\u003eAdditionally, the crystallinity of SiC fibers was calculated by the following equation with XRD spectra:\u003c/p\u003e\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" style=\"width: 471px;\"\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e represents the crystal diffraction peak area. \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e represents amorphous diffraction peak area. The judging standard of crystal diffraction peak is FWHM less than 3.0.\u003c/p\u003e \u003cp\u003eThe flexural strength of the SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites was characterized by the three-point-bending method using a universal testing machine (Haida Qualitative Analysis, HD-609B) at room temperature. Mechanical samples were cut into 40mm\u0026thinsp;\u0026times;\u0026thinsp;4mm\u0026thinsp;\u0026times;\u0026thinsp;3\u0026nbsp;mm. This universal testing machine had a cross head speed of 0.5\u0026nbsp;mm/min with a span of 30\u0026nbsp;mm. The surface of SiC fibers and fracture surfaces of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites were observed by scanning electron microscope (Model VEGA3 SBH, TESCAN, Brno, Czech) with energy dispersion spectroscopy (EDS). The conductivity of SiC fibers can be calculated by the equation:\u003c/p\u003e \u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" style=\"width: 490px;\"\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eL\u003c/em\u003e and \u003cem\u003eS\u003c/em\u003e is the length and cross section area of a bunch of SiC fibers, respectively. One bunch of fibers consisted of 1000 SiC fibers. \u003cem\u003eR\u003c/em\u003e is the resistance of one bunch of SiC fibers, which was measured by a resistant tester.\u003c/p\u003e \u003cp\u003eThe complex permittivity of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites was measured at the frequency between 8.2 and 12.4\u0026nbsp;GHz using the waveguide method with a vector network analyzer (Agilent Technologies E8362B). The dimension of complex permittivity samples was 22.86mm\u0026thinsp;\u0026times;\u0026thinsp;10.16mm\u0026thinsp;\u0026times;\u0026thinsp;2.0\u0026nbsp;mm.\u003c/p\u003e \u003c/div\u003e "},{"header":"3. Results And Discussion","content":" \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Microstructure of SiC fibers\u003c/h2\u003e \u003cp\u003eThe surface and cross-section morphologies of different SiC fibers are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The surface of the SiC fibers is smooth and homogeneous. The diameters of SiC fibers are all about 12\u0026nbsp;\u0026micro;m. The SiC fibers were cut to observe cross-section, which was shown a dense morphology. Many particles with a small size can be seen on the cross-section of fibers.\u003c/p\u003e \u003cp\u003eCompositional elements of surface and cross-section of different SiC fibers at selected regions in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e were measured by EDS, seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. By comparing SLF, KD-II and KD-S SiC fibers, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (a) and (b) show that the content of oxygen element in SLF fibers is 17.21% on the surface and 10.36% in cross-section. Therefore, SLF SiC fibers satisfy the characteristic of high oxygen content in the first generational and process a large amount of SiOC phase\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. In contrast, the oxygen content of KD-S SiC fibers is only 2.34% on surface and 3.03% in cross-section. The content of Si element increased with the content of oxygen element decreasing in the SLF, KD-II and KD-S SiC fibers. Additionally, from SLF, KD-II to KD-S, the ratio of C/Si is reduced. However, the content of C element in KD-II SiC fibers is the highest in the cross-section.\u003c/p\u003e \u003cp\u003eThe different properties of these three types of SiC fibers can be reflected by polycrystalline microstructure\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the XRD revealed the crystalline structure of different SiC fibers. The crystallinity and crystallite size of β-SiC crystallite for SLF, KD-II and KD-S SiC fibers are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The XRD patterns demonstrate that the microstructures of SiC fibers are mainly formed by β-SiC at peaks of 35.74\u0026deg;, 41.50\u0026deg;, 60.14\u0026deg;, 71.97\u0026deg; and 75.71\u0026deg;, which are indexed to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) lattices, respectively. It can be seen that the SLF SiC fibers present three main diffraction peaks at 35.74\u0026deg;, 60.14\u0026deg; and 71.97\u0026deg;, which were assigned to the (1 1 1), (2 2 0) and (3 1 1) planes of the amorphous β-SiC phase, respectively. The sharp XRD peaks observed for the KD-II and KD-S SiC fibers clearly confirm the larger crystallite size (4.4\u0026nbsp;nm and 4.1\u0026nbsp;nm) of β-SiC than that of the SLF SiC fibers (1.4\u0026nbsp;nm). Moreover, other peaks were indexed as the (2 0 0) and (2 2 2) planes of the β-SiC appeared in KD-II and KD-S SiC fibers. As same as the first generation of SiC fibers, the SLF fibers are almost amorphous, according to the broad minor peaks\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. In contrast, the KD-II and KD-S SiC fibers have high crystallinity with 83.92% and 87.76%, respectively.\u003c/p\u003e \u003cp\u003eThanks to the amorphous phase and high oxygen content, the free carbon conductive network in the SLF fibers will be separated by Si-C-O phase\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. Therefore, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the conductivity of SLF fibers is only 0.0127\u0026nbsp;S/cm. The conductivity of KD-II fibers is 1.1811\u0026nbsp;S/cm owing to the larger C/Si atomic ratio\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e and the conductive network of carbon-rich layers. The conductivity of KD-S fibers is 0.1316\u0026nbsp;S/cm due to the lower C and O content.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCrystallinity and crystallite size of β-SiC for SLF, KD-II and KD-S SiC fibers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProperties\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSLF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eKD-II\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eKD-S\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrystallinity (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026asymp;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e83.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e87.76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrystallite size (nm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eConductivity of SLF, KD-II and KD-S SiC fibers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSLF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eKD-II\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eKD-S\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConductivity(S/cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.0127\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.1811\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1316\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Mechanical properties and microstructure of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites\u003c/h2\u003e \u003cp\u003eMechanical properties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites with SLF, KD-II and KD-S SiC fibers are listed in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The flexure strength of the KD-S and KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites are 248.16\u0026nbsp;MPa and 322.57\u0026nbsp;MPa, respectively. The KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites exhibited the best mechanical properties comparing to the SLF and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites, owing to the fact that massive free carbon networks generated by the high content of C in the KD-II SiC fibers. Under the same fabricating condition, the density and open porosity of SLF, KD-II and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites are pretty similar. However, the flexure strength of SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites is only 147.77\u0026nbsp;MPa. It indicates that the growth of crystallites and high crystallinity are beneficial to enhance the flexure strength of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eProperties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites SLF, KD-II and KD-S SiC fibers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSiC\u003csub\u003ef\u003c/sub\u003e/SiC composites\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDensity (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOpen porosity\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFlexural strength (MPa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDisplacement\u003c/p\u003e \u003cp\u003e(mm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSLF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e147.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.240\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKD-II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e322.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.333\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKD-S\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e248.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.275\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe stress-displacement curves obtained from the bending test for SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites with different kinds of SiC fibers are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The load on the SLF, KD-II and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites decreases sharply as reaching the peak value. It is revealed that all kinds of SiC fibers reinforced SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites appear a typical brittle fracture behavior. It can be concluded that the bonding strength between three types of SiC fibers and the matrix was strong.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe fracture morphologies of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites with SLF, KD-II and KD-S fibers were shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003e. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003e (a), the fracture surface of SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites was plane and there are no fibers pull-out phenomenon appearance due to the strong bonding at the surface between matrix and SLF SiC fibers. The fracture surface of KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites exhibits step-shaped appearances, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003e (b). In Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003e (c), the step-shaped fracture and fibers pull-out can be discovered in the fracture surface of KD-S. According to the fracture morphologies, the matrix densification of SLF, KD-II and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites are similar. With the same content of matrix and SiC fibers in SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites, the different mechanical properties should be caused by different kinds of SiC fibers.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Dielectric properties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites with different SiC fibers\u003c/h2\u003e \u003cp\u003eThe complex permittivity (\u003cem\u003eε\u0026thinsp;=\u0026thinsp;ε\u0026rsquo;-jε\u0026rsquo;\u0026rsquo;\u003c/em\u003e) of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites with various SiC fibers was measured at the frequency range of X band (8.2\u0026ndash;12.4\u0026nbsp;GHz). The real part of permittivity (\u003cem\u003eε\u0026rsquo;\u003c/em\u003e) is correlated with polarization and the imaginary part of permittivity (\u003cem\u003eε\u0026rsquo;\u0026rsquo;\u003c/em\u003e) in reference to the ability of dielectric loss and electrical conductivity\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e. The loss tangent (tanδ) of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites were calculated by tanδ\u0026thinsp;=\u0026thinsp;ε\u0026rsquo;/ε\u0026rsquo;\u0026rsquo;\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e, which represents the microwave absorption ability of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites\u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003e, both the real and imaginary permittivity of KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites reveal a decreasing trend as the frequency increases in the whole X band. It can be indicated that the KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites possess frequency dispersion effect and a broad microwave absorption band. The complex permittivity of SLF and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites almost keeps constant in the measured range, in which the values are 7.9-4.0j and 11.6-9.2j at the frequency of 10\u0026nbsp;GHz respectively. Compared with SLF and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites, the KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites possess much higher imaginary permittivity and loss tangent. The real and imaginary part of permittivity of KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites is 12.6 and 25.0\u0026nbsp;at 10\u0026nbsp;GHz, respectively, and the loss tangent of it is in the range of 1.7\u0026ndash;2.2 in the whole X band. It suggests that the KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites has the strongest microwave absorption ability.\u003c/p\u003e \u003cp\u003eThe SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites are composited by SiC fibers, interface and SiC matrix. Therefore, the real and imaginary permittivity of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites can be illustrated as Lichtencker\u0026rsquo;s logarithmic equations \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e:\u003c/p\u003e \u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" style=\"width: 488px;\"\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003ef\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e are volume contents, \u003cem\u003eε\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ef\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eε\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eε\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e are real permittivities, and \u003cem\u003eε\u0026rsquo;\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ef\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eε\u0026rsquo;\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eε\u0026rsquo;\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e imaginary permittivities of SiC fiber, SiC matrix and interface, respectively. In this experiment, the interface was not fabricated and the porosity and density of SiC matrix was similar as shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Additionally, the SLF, KD-II and KD-S SiC fibers were all fabricated into 2.5D with volume fraction of 35% and the process of manufacture SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites was under the same experimental condition. Consequently, the real and imaginary part of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites are mainly dependent on SiC fibers.\u003c/p\u003e \u003cp\u003eOn the one hand, there are lots of interfaces around SiC nano-crystals, free carbons and amorphous SiOC phase. Additionally, the dipoles from defect in SiC nano-crystals and free carbons in SiC fibers\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e. The KD-II and KD-S SiC fibers with high crystallinity have more grain boundaries and free carbons. Therefore, the higher real permittivity of KD-II and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites owing to the polarization from interfaces among the grain boundary and dipoles in the KD-II and KD-S SiC fibers under the X band. On the other hand, according to the Debye theory\u003csup\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e, the imaginary part of permittivity can be decided by the conductivity, which can be calculated by the following equation:\u003c/p\u003e\u003cp\u003e\u003cimg src=\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAhcAAABUCAYAAAAxihWjAAALGUlEQVR4Ae3d3Y3aTBgGUFpIDV8LuXIDKSEdIKWFdJA7LtNBKggNpIHco3SQHubTazMweG08y87GsHuQouVnPDbHlngyf94kDwIECBAgQIBAQ4FNw7pURYAAAQIECBBIwoWLgAABAgQIEGgqIFw05VQZAQIECBAgIFy4BggQIECAAIGmAsJFU06VESBAgAABAsKFa4AAAQIECBBoKiBcNOVUGQECBAgQICBcuAYIECBAgACBpgLCRVNOlREgQIAAAQLChWuAAAECBAgQaCogXDTlVBkBAgQIECAgXLgGCBAgQIAAgaYCwkVTTpURIECAAAECwoVrgAABAgQIEGgqIFw05VQZAQIECBAgIFy4BggQIECAAIGmAsJFU06VESBAgAABAsKFa4AAAQIECBBoKiBcNOVUGQECBAgQICBcuAYIECBAgACBpgLCRVNOlREgQIAAAQLChWuAAAECBAgQaCogXDTlVBkBAgQIECAgXNz9NXBI+902dV2XNpvNwr9t2t/993GABAgQIPDWBYSLez7D+23qFgNFETi2osU9n07HRoAAgfciIFzc65neb4+tFF3a7vbpcCgONEJHt0vlW8WnnhIgQIAAgVUFhItV+Wd2ftgdWyy2aT+ZIA5p123SRkvFDKC3CRAgQGBNAeFiTf2Zfe+3Q1fHtexw2MUYjC7tJsPHTMXeJkCAAAEC/0BAuPgHyM/bxT5tY5zFQrdHTQB53n6VJkCAAAECbQSEizaO7WrJYy2uNVukY7eIlot27moiQIAAgWYCwkUzykYV1YSLmjKNDkc1BAgQIEDguQLCxXPFXr38QrfI4fj5xpoWr34q7IAAAQIEbhIQLm5ie92NDrllotsVs0UOKd7v171YGI/xukendgIECBAgcF1AuLjus9qnh/0ubWO66WkRrS51XUxNNT1ktZNixwQIEPgHAr9//07fvn27aU9fv35Nsf3ajwcMF7nbIHcLjF+vTWr/BAgQIEDgNoEfP36kL1++LG4c5T5//pw+fPjQ/yf0169f/TZ///7tt4/P13w8Xrg4LTB1XONh/HpNTfsmQIAAAQI3CkQg+PTp09Wto1Xi48ePfaCIEPLz588UgaJ8xOsos2bAeOBwcWy5OIWL3JJREntOgAABAgTuXyBCQ3SD//nzZ/Zgo0y0VMS/3FIxVzjXF3/XeDxeuEi5GyTfW2P8eg1G+yRAgAABArcLREtDdHPMPcpgURsYohUk6l3j8YDhYnxfjfHrNRjtkwABAgQI3CYQ3RfRajHXjRHdHP/999/F2IqaPX3//v1qvTV13FrmbsLFMDsi7pdxniERsyOm7p0RS193xQfj17di2I4AAQIECPxrgWhhuNYlEjNH4vOl8Rjj485dI9daRMbbtHp9B+HivJT19nQL0EPK986YusdG3LSrXB17/LoVjnoIECBAgMBrCkSrRP5P9dx+cqtFhIyYappfx9+lKau57vGgz7l9tXp/9XCRQ0QZFvov1y8kFSHi5es6DHcQPbeIZOy5v2WrSCto9RAgQIAAgbFADMyM36K5sRG59SHKxOyQPOAztsvTUCNwzD1ymaUBoHPb3/r+yuEit1qY6XHrCbQdAQIECDyuwFKXRx43ESFh/MjBJILH3CDP3OWy1MIxrvulr1cOFykNrQrHNSte+m1sT4AAAQIEHkhgKVwsfR4tHhEu5sLDuw0XKcX4itFAzmKw5r1dI3ES3/O/ezsfjocAAQKPLLAUHpY+jy4R4eLiCjiHim63Ty8fWXFRuRcECBAgQODuBZbCQ+76iMGbU4+8ffydery7los8kHPzZCRn+3EYBnROXXLeI0CAAIG1BZbCQxxfHpSZB3OWx5xbLubGXORuk3cyoPO4quZmczGlNMBOQcBtxcvrx3MCBAgQeIMCNVNR86DO8Q3N8uJa19a/yN3472Qqam6d2KRouRi6RA5pvzuOvehvLf4GryJfiQABAgQIjARikasIAXOtD1E8gkWUiaARj2jFyHdFnQsOUSa2uRY+RofS7OV6s0UO+7TrRgM5u2FdC+Mvmp1fFREgQIDAnQssLf+dDz/GVeQFtKKrJALHXLCIbWrrzfW3/LteuGj5LdRFgAABAgQeWCDGRrRepjvqm1uc67WphIvXFlY/AQIECBBYEMgrcV7rGlmo4uLj3CXSqr6LyiteCBcVSO+3yDBduDuu7dFt823u36+Ib06AAIHXEohujFYtDdFqMXeX1dc6/rJe4aLUePbzyx/fzaZL3WmA6rMru68NDrs0hIptGm7vMszwcd+V+zpNjoYAgbclEIHg2r1Car5tjMVYM1jEMQoXNWdqskwx4+XJqp2Pfq+UPFW4WJb9dCO5SQxvEiBAgEAjgejKmFsUa2kXsd1aXSHlsQkXpcYznvfrcXTbtDvkuS3FVNoIG08WB3tG5SsXzQucaaVY+UTYPQECBB5UQLi46cRFq8V068RpEbDN9Oc37e5fbtS3UMT9Ux70+P+llX0RIECAwKSAcDHJsvTmPu3mbq5WjlVYqubOPj/st8dxFpuk1eLOTo7DIUCAwAMJCBetT1YOF1eWLz/szj/ieWnWyb+jrpXDfpe2TxYei66ZF3yJU0vFxN1er3yHF+zRpgQIECDwxgWEi9Yn+PhjPcoFp73k8QyTYWI0MPRcRx48OqxgOlQWM1WOgaBRCDh16TSq7/SlPSFAgACBdyUgXDQ+3f0P/syPc7RYbPeH471UYkZGOa5hmKFxDhTnA8sh4slnpxkcL2m6yPvJAUaXSBbxlwABAgRuExAubnOb3qrvEimmb06XGt6NYFCkhWH2ydQiVflHvwwi1yq+8bPcnbOpPP4bd2MzAgQIEHj7AsJFs3McISC6LWoqHMqex0oMAWJuEOXQXfG6P/q6RGrOmzIECBAgUCMgXNQoVZSJH+e5cPBk81GrRTp2b5zDxniLYSXQcpxG9b7GVU2+zq0jukQmebxJgAABAs8SEC6exTVduA8WdU0WKaXhh7ws3o+pKN847eYcKrrd/jhW4/Rhuye6RNpZqokAAQIELP/90mugXxtiMhhM19x3P1wM+Jy/Z0ceyFmOzRhqzS0N43EY+f1N2lzsY/pY8rvz+8kl/CVAgAABAvUCWi7qrZ6U7IPFzI94rEkRNzErH3lcw8XbfZdI7o6IlopdGrbK9/fYPBnHkesZB4gICbm7pC9zsaPySMrn8/spS3lOgAABAgRqBYSLWqlRuQgW5RiIqeflb/spEJRvRifJrruo5/xx0QpxutNqcf+SWH68nIHad22ULRkRGsrXoy+QX+bvMROScjF/CRAgQIBArYBwUStVlKsJFpf35jgGhakf8GK8Q6yBcfE47PsZKGVw6foZKXmtjKJ0hISL+od9nsNKUbZ4mrtEcotH8ZGnBAgQIEDgJgHh4ia2+9voaTdIRbg4BZuKFo77+8qOiAABAgTuVEC4uNMT89zDuiVc5C6ZpdaN5x6L8gQIECDwvgWEi7dy/he6RYYgUbZQHAdyShZv5QrwPQgQIHA3AsLF3ZyKFx7IeEDnxevLMR/D3VU3/WyW0SiPFx6EzQkQIECAQLLOxVu6CMZTUS8GaZ7GV8QaGNu0Gw8efUsQvgsBAgQIrCqg5WJV/tY7P7ZQxK3bdXe0xlUfAQIECFQKCBeVUIoRIECAAAECdQLCRZ2TUgQIECBAgEClgHBRCaUYAQIECBAgUCcgXNQ5KUWAAAECBAhUCggXlVCKESBAgAABAnUCwkWdk1IECBAgQIBApYBwUQmlGAECBAgQIFAnIFzUOSlFgAABAgQIVAr8DyluEGint9CnAAAAAElFTkSuQmCC\" style=\"width: 475px;\"\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eσ\u003c/em\u003e is the electrical conductivity, \u003cem\u003eε\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e is the dielectric constant in vacuum and \u003cem\u003ef\u003c/em\u003e is the frequency of the electromagnetic wave. According to the above analysis, the imaginary part of permittivity of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites in this experiment is proportional to the conductivity of SiC fibers. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the conductivity of KD-II SiC fibers 1.1811\u0026nbsp;S/cm is the highest. Therefore, the higher electrical conductivity of KD-II SiC fibers gives rise to the larger imaginary part of KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003c/span\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Microwave absorption properties of SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites\u003c/h2\u003e \u003cp\u003eThe microwave absorption property of SLF, KD-II and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites are evaluated by the reflection loss (RL) values, which is based on the transmission line theory. The RL values can be calculated as the following equations:\u003c/p\u003e \u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" style=\"width: 462px;\"\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e is the characteristic impedance of free space, \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e is the input impedances of the interface between SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites and free space. \u0026micro;\u003csub\u003e0\u003c/sub\u003e and ε\u003csub\u003e0\u003c/sub\u003e are the permeability and permittivity of vacuum. \u003cem\u003e\u0026micro;\u003c/em\u003e\u003csub\u003e\u003cem\u003er\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eε\u003c/em\u003e\u003csub\u003e\u003cem\u003er\u003c/em\u003e\u003c/sub\u003e are the measured relative permeability and permittivity. Because of negligible magnetic properties of SiC, the value of \u003cem\u003e\u0026micro;\u003c/em\u003e\u003csub\u003e\u003cem\u003er\u003c/em\u003e\u003c/sub\u003e, in this experiment, is taken as 1. Consequently, the RL values of dielectric microwave absorption SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites can be calculated by complex permittivity and thickness in X band.\u003c/p\u003e \u003cp\u003eGenerally, the high loss tangent can give rise to the better microwave absorption abilities. However, the optimum impedance matching between the free space and the surface of microwave absorption material leads microwave reflection reduced, and then enhanced the energy loss of the incident microwave. For optimum matching impedance, it demands that the input impedance \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e equal with free space impedance \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e as far as possible. The input impedance \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e of SLF, KD-II and KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites with a thickness of 2.9\u0026nbsp;mm are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eThe \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e value of the KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites is in the range of 63.15\u0026ndash;75.12 Ω. The higher difference between \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e leads to the stronger reflection of incident microwave on the surface of the SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites. Therefore, the KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites possess poor microwave absorbing properties, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e6\u003c/span\u003e (c) and (d). In X band, the KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites has only \u0026minus;\u0026thinsp;3.6 dB RL values from 2 to 2.9\u0026nbsp;mm thickness and there is no reflection loss peak appearance. On the contrary, the \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e value of SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites is the highest, in the range of 328.65\u0026ndash;178.70 Ω, and processes the lowest deviation between \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e. As a consequence, most of the microwave incidence into SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e6\u003c/span\u003e (a) and (b), the RL values of SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites can be obtained over \u0026minus;\u0026thinsp;25 dB with a thickness of 2.3\u0026nbsp;mm and the effective absorption bandwidth (EAB) below \u0026minus;\u0026thinsp;10 dB reaches 3.72\u0026nbsp;GHz (from 8.68 to 12.40\u0026nbsp;GHz) with a thickness of 2.7\u0026nbsp;mm. The \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e value of the KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites is in the range of 141.80-85.39 Ω. That deviation between \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e is higher than that of KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites and lower than that of SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e6\u003c/span\u003e (c) and (f), the RL values of KD-S SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites can be obtained over \u0026minus;\u0026thinsp;9dB with a thickness of 2\u0026nbsp;mm and the EAB below \u0026minus;\u0026thinsp;7 dB reaches 4.12\u0026nbsp;GHz (from 8.28\u0026nbsp;GHz to 12.40\u0026nbsp;GHz), indicating more than 84% microwave absorption\u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e, with the thickness of 2.2\u0026nbsp;mm.\u003c/p\u003e \u003cp\u003eWith the same SiC matrix, the SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites possess the optimum microwave absorption property due to the amorphous Si-O-C structure and low conductivity of SLF fibers. Additionally, the interfacial polarization is generated by the massive amount of amorphous SiOC and free carbon in SLF fibers. When microwave propagates into the SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites, a large number of dipoles generated from free carbon, amorphous SiOC and amorphous SiC. The dipoles could cause displacement polarization or steering polarization with the changed electromagnetic wave. The dipoles polarization gradually lagged behind the changes. At this time, the energy of electromagnetic wave can be consumption\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. Instead, a large amount of interface generated between free carbon in the KD-II and KD-S fibers lead displacement polarization or steering of dipoles easy and consume less electromagnetic wave energy under the alternating microwave.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e "},{"header":"4. Conclusion","content":" \u003cp\u003eIn summary, the SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites fabricated with SLF, KD-II and KD-S SiC fibers by PIP method have similar density and open porosity values. The SLF SiC fiber possessed a large amount of oxygen and amorphous phase. The KD-II and KD-S SiC fiber exhibit higher crystallizations and higher free carbon contents than SLF SiC fibers. KD-II SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites have the highest flexural strength with a value of 322.57\u0026nbsp;MPa and possess the worst microwave absorption property owing to the massive carbon in the fibers. SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites possess the best microwave absorption property due to the best impedance matching with air and the lowest flexural strength can be ascribed to the poor strength of SLF SiC fibers.\u003c/p\u003e \u003cp\u003eThe microwave absorption property of the SLF SiC\u003csub\u003ef\u003c/sub\u003e/SiC composites can be obtained over \u0026minus;\u0026thinsp;25 dB with a thickness of 2.3\u0026nbsp;mm and the effective absorption bandwidth (EAB) below \u0026minus;\u0026thinsp;10 dB reaches 3.72\u0026nbsp;GHz with a thickness of 2.7\u0026nbsp;mm, indicating its potential application in the structural and absorbing field.\u003c/p\u003e \u003cp\u003eAbove all, the SLF SiC fiber can be used as reinforcement for microwave absorption structure composites. But the interphase on the surface of SLF SiC fibers was necessary to the flexural strength enhancement. Because of the high loss tangent and mechanical property, KD-II SiC fibers are better used as the absorption layer in the multi-layered radar absorbing structures composites field. The KD-S SiC fibers possess medium levels of microwave absorption and mechanical properties. Therefore, further studies should focus on the matrix and interphase modification of KD-S composites.\u003c/p\u003e "},{"header":"Declarations","content":" \u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eThis work was financially supported by National Nature Science Foundation of China (Grant No. 51701148), Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2019JQ-916)\u003c/p\u003e "},{"header":"References","content":"\u003cp\u003e\u0026nbsp;[1] Qing Y, Min D, Zhou Y, et al. Graphene nanosheet- and flake carbonyl iron particle-filled epoxy\u0026ndash;silicone composites as thin\u0026ndash;thickness and wide-bandwidth microwave absorber[J]. 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Journal of the European Ceramic Society. 2018, 38(4): 1327-1333.\u003c/p\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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"SiCf/SiC composites, microwave absorption, mechanical property, SiC fibers","lastPublishedDoi":"10.21203/rs.3.rs-27933/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-27933/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The SiC fibers are essential for designing microwave absorption and mechanical properties of multifunctional composites. In this study, SLF, KD-II and KD-S SiC fibers were used to fabricate SiC f /SiC composites. The SLF SiC fibers are composed by amorphous SiOC. The KD-II and KD-S SiC fibers exhibit higher crystallizations and free carbon content. The conductivity of SLF, KD-II and KD-S SiC fibers are 0.0127, 1.184 and 0.1316 S/cm, respectively. The flexural strength of SLF, KD-II and KD-S SiC f /SiC composites are 147.77, 322.57 and 248.16 MPa, respectively. The microwave absorption property of the SLF SiC f /SiC composites can be obtained over -25 dB with a thickness of 2.3 mm and the effective absorption bandwidth (EAB) below -10 dB reaches 3.72 GHz with the thickness of 2.7 mm. In contrast, the KD-II SiC f /SiC composites only reach -3.6 dB in the whole X band when the thickness varies from 2 to 2.9 mm. KD-S SiC f /SiC composites can be obtained over -9dB with the thickness of 2mm and the EAB below -7 dB reaches 4.12 GHz with a thickness of 2.2 mm. The mechanisms of mechanical, microwave absorption and penitential applications for SiC f /SiC composites are also discussed.","manuscriptTitle":"Effect of different kinds of SiC fibers on microwave absorption and mechanical properties of SiCf/SiC composites","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2020-05-15 19:30:20","doi":"10.21203/rs.3.rs-27933/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"dd8baeee-c3d5-4fe1-a9c4-a5e91cecb2ac","owner":[],"postedDate":"May 15th, 2020","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":101459,"name":"Ceramics"}],"tags":[],"updatedAt":"2021-07-22T21:01:27+00:00","versionOfRecord":{"articleIdentity":"rs-27933","link":"https://doi.org/10.1007/s10854-020-04129-5","journal":{"identity":"journal-of-materials-science-materials-in-electronics","isVorOnly":false,"title":"Journal of Materials Science: Materials in Electronics"},"publishedOn":"2020-08-06 21:01:27","publishedOnDateReadable":"August 6th, 2020"},"versionCreatedAt":"2020-05-15 19:30:20","video":"","vorDoi":"10.1007/s10854-020-04129-5","vorDoiUrl":"https://doi.org/10.1007/s10854-020-04129-5","workflowStages":[]},"version":"v1","identity":"rs-27933","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-27933","identity":"rs-27933","version":["v1"]},"buildId":"-HB7Z8yhvgn0wM9Nzuekk","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}