An experimental investigation into the thermal conductivity of CF-SiC two-phase composite asphalt concrete is presented.The main objective of this study was to verify the possibility of using SiC powder instead of min...An experimental investigation into the thermal conductivity of CF-SiC two-phase composite asphalt concrete is presented.The main objective of this study was to verify the possibility of using SiC powder instead of mineral powder as the thermal conductive filler to prepare a new type of asphalt concrete and improve the efficiency of electrothermal snow and ice melting systems accordingly.The thermal conductivity of asphalt concrete prepared with different thermally conductive fillers was tested by a transient plane source method,and the related performances were measured.Then the temperature rise rate and surface temperature were studied through field heating tests.Finally,the actual ice melting efficiency of the thermally conductive asphalt concrete was evaluated using an effective electrothermal system.As shown by the experimental results,the composite made of SiC powder and carbon fiber has a high thermal conductivity.When SiC replaces mineral powder,the thermal conductivity of the asphalt mixture increases first and then decreases with the increase of carbon fiber content.In the present study,in particular,the thermal conductivity attained a peak when the carbon fiber content was 0.2%of the aggregate mass.展开更多
3D carbon fiber needled felt and polycarbosilane-derived SiC coating were selected as reinforcement and interfacial coating,respectively,and the sol-impregnation-drying-heating(SIDH)route was used to fabricate C/Al2O3...3D carbon fiber needled felt and polycarbosilane-derived SiC coating were selected as reinforcement and interfacial coating,respectively,and the sol-impregnation-drying-heating(SIDH)route was used to fabricate C/Al2O3 composites.The effects of Si C interfacial coating on the mechanical properties,oxidation resistance and thermal shock resistance of C/Al2O3 composites were investigated.It is found that the fracture toughness of C/Al2O3 composites was remarkably superior to that of monolithic Al2O3 ceramics.The introduction of SiC interfacial coating obviously improved the strengths of C/Al2O3 composites although the fracture work diminished to some extent.Owing to the tight bonding between SiC coating and carbon fiber,the C/SiC/Al2O3 composites showed much better oxidation and thermal shock resistance over C/Al2O3 composites under static air.展开更多
ZrB_2–SiC/ZrSi_2 ceramics containing 30 vol% carbon fiber(Cf) additive were fabricated by hot pressing at low temperature(1500 ℃) using submicron ZrB_2 powders, and their microstructural evolution and performance we...ZrB_2–SiC/ZrSi_2 ceramics containing 30 vol% carbon fiber(Cf) additive were fabricated by hot pressing at low temperature(1500 ℃) using submicron ZrB_2 powders, and their microstructural evolution and performance were investigated. The addition of SiC or ZrSi_2 significantly reduced the onset sintering temperature and enhanced the densification of ZrB_2. ZrB_2–ZrSi_2–Cf showed poor performance owing to the serious fiber degradation, while the fiber degradation was effectively inhibited in ZrB_2–SiC–Cf resulting in high fracture toughness, substantial fiber pull-out, and non-brittle fracture mode for such material. The critical thermal shock temperature difference of ZrB_2–SiC–Cf was up to 741 ℃, significantly higher than those of ZrB_2–SiC/ZrSi_2 and ZrB_2–ZrSi_2–Cf. Moreover, this composite displayed a good oxidation resistance at 1500 ℃ in air.展开更多
Oxidation behaviors of carbon fiber reinforced SiC matrix composites(C/SiC)are one of the most noteworthy properties.For C/SiC,the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coef...Oxidation behaviors of carbon fiber reinforced SiC matrix composites(C/SiC)are one of the most noteworthy properties.For C/SiC,the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coefficients of thermal expansion(CTEs)and elastic modulus between carbon fiber and SiC matrix.In order to improve the oxidation resistance,multilayer SiC–Si_(3)N_(4) matrices were fabricated by chemical vapor infiltration(CVI)to alleviate the above two kinds of mismatch and change the local stress distribution.For the oxidation of C/SiC with multilayer matrices,matrix microcracks would be deflected at the transition layer between different layers of multilayer SiC–Si_(3)N_(4) matrix to lengthen the oxygen diffusion channels,thereby improving the oxidation resistance of C/SiC,especially at 800 and 1000℃.The strength retention ratio was increased from 61.9%(C/SiC–SiC/SiC)to 75.7%(C/SiC–Si_(3)N_(4)/SiC/SiC)and 67.8%(C/SiC–SiC/Si_(3)N_(4)/SiC)after oxidation at 800℃for 10 h.展开更多
High-performance thermal protection materials(TPMs)for spacecraft are becoming current research hotspots.Lightweight polymer-based ablators are considered to be the most promising candidates for TPMs due to their exce...High-performance thermal protection materials(TPMs)for spacecraft are becoming current research hotspots.Lightweight polymer-based ablators are considered to be the most promising candidates for TPMs due to their excellent designability and versatility.In this study,a unique nano-TiO_(2) coated needled carbon fiber felt/phenolic resin aerogel composite(TiCF/PR)is reported.Wherein the anatase nano-TiO_(2) was in-situ coated on the surface of carbon fibers uniformly through the sol-gel and calcination method,then,the phenolic resin aerogel was in-situ synthesized in the nano-TiO_(2) coated needled carbon fiber felt(TiCF)preform through vacuum impregnation and solvothermal method.The as-prepared aerogel com-posite possesses a low density(0.30–0.32 g/cm^(3)),low thermal conductivity(0.034 and 0.312 W/(m K)in the z and xy directions),and excellent thermal stability with 13.86%residual weight at 1300℃ in air.It is worthwhile to note that the TiCF/PR composite exhibits excellent antioxidant ablation and infrared(IR)radiation shielding properties in a high-temperature heating environment.With an oxygen-acetylene blaze heating of 1.5 MW/m^(2) for 150 s,the linear ablation rates decreased by 13.4%,and the backside temperature reduced from 322.3 to 179.1℃ compared to that of the sample without nano-TiO_(2) coating.The experimental and theoretical analysis showed that the present TiCF/PR nanocomposite has competitive and potential application prospects in the field of future TPMs.展开更多
基金the support of the Joint Funds of the Natural Science Foundation of Hubei Province(2022CFD130)the Technology Innovation Project of Hubei Province(Key Program,No.2023BEB010)+1 种基金the Key Research and Development Program of Hubei Province(No.2021BGD015)the Knowledge Innovation Project of Wuhan(No.2022010801010259).
文摘An experimental investigation into the thermal conductivity of CF-SiC two-phase composite asphalt concrete is presented.The main objective of this study was to verify the possibility of using SiC powder instead of mineral powder as the thermal conductive filler to prepare a new type of asphalt concrete and improve the efficiency of electrothermal snow and ice melting systems accordingly.The thermal conductivity of asphalt concrete prepared with different thermally conductive fillers was tested by a transient plane source method,and the related performances were measured.Then the temperature rise rate and surface temperature were studied through field heating tests.Finally,the actual ice melting efficiency of the thermally conductive asphalt concrete was evaluated using an effective electrothermal system.As shown by the experimental results,the composite made of SiC powder and carbon fiber has a high thermal conductivity.When SiC replaces mineral powder,the thermal conductivity of the asphalt mixture increases first and then decreases with the increase of carbon fiber content.In the present study,in particular,the thermal conductivity attained a peak when the carbon fiber content was 0.2%of the aggregate mass.
文摘3D carbon fiber needled felt and polycarbosilane-derived SiC coating were selected as reinforcement and interfacial coating,respectively,and the sol-impregnation-drying-heating(SIDH)route was used to fabricate C/Al2O3 composites.The effects of Si C interfacial coating on the mechanical properties,oxidation resistance and thermal shock resistance of C/Al2O3 composites were investigated.It is found that the fracture toughness of C/Al2O3 composites was remarkably superior to that of monolithic Al2O3 ceramics.The introduction of SiC interfacial coating obviously improved the strengths of C/Al2O3 composites although the fracture work diminished to some extent.Owing to the tight bonding between SiC coating and carbon fiber,the C/SiC/Al2O3 composites showed much better oxidation and thermal shock resistance over C/Al2O3 composites under static air.
基金provided by Scientific Research Starting Foundation of Anhui Polytechnic University of China (No.2017YQQ009)the Fundamental Research Funds for the Central Universities (Grant No.HIT.BRETIII.201506)
文摘ZrB_2–SiC/ZrSi_2 ceramics containing 30 vol% carbon fiber(Cf) additive were fabricated by hot pressing at low temperature(1500 ℃) using submicron ZrB_2 powders, and their microstructural evolution and performance were investigated. The addition of SiC or ZrSi_2 significantly reduced the onset sintering temperature and enhanced the densification of ZrB_2. ZrB_2–ZrSi_2–Cf showed poor performance owing to the serious fiber degradation, while the fiber degradation was effectively inhibited in ZrB_2–SiC–Cf resulting in high fracture toughness, substantial fiber pull-out, and non-brittle fracture mode for such material. The critical thermal shock temperature difference of ZrB_2–SiC–Cf was up to 741 ℃, significantly higher than those of ZrB_2–SiC/ZrSi_2 and ZrB_2–ZrSi_2–Cf. Moreover, this composite displayed a good oxidation resistance at 1500 ℃ in air.
基金This work was supported by the National Natural Science Foundation of China(Nos.52072303 and 51821091)the National Science and Technology Major Project(No.J2019-VI-0014-0129)。
文摘Oxidation behaviors of carbon fiber reinforced SiC matrix composites(C/SiC)are one of the most noteworthy properties.For C/SiC,the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coefficients of thermal expansion(CTEs)and elastic modulus between carbon fiber and SiC matrix.In order to improve the oxidation resistance,multilayer SiC–Si_(3)N_(4) matrices were fabricated by chemical vapor infiltration(CVI)to alleviate the above two kinds of mismatch and change the local stress distribution.For the oxidation of C/SiC with multilayer matrices,matrix microcracks would be deflected at the transition layer between different layers of multilayer SiC–Si_(3)N_(4) matrix to lengthen the oxygen diffusion channels,thereby improving the oxidation resistance of C/SiC,especially at 800 and 1000℃.The strength retention ratio was increased from 61.9%(C/SiC–SiC/SiC)to 75.7%(C/SiC–Si_(3)N_(4)/SiC/SiC)and 67.8%(C/SiC–SiC/Si_(3)N_(4)/SiC)after oxidation at 800℃for 10 h.
基金We gratefully acknowledge the support from the National Nat-ural Science Foundation of China(Nos.51872066,52032003,and U20B2017).
文摘High-performance thermal protection materials(TPMs)for spacecraft are becoming current research hotspots.Lightweight polymer-based ablators are considered to be the most promising candidates for TPMs due to their excellent designability and versatility.In this study,a unique nano-TiO_(2) coated needled carbon fiber felt/phenolic resin aerogel composite(TiCF/PR)is reported.Wherein the anatase nano-TiO_(2) was in-situ coated on the surface of carbon fibers uniformly through the sol-gel and calcination method,then,the phenolic resin aerogel was in-situ synthesized in the nano-TiO_(2) coated needled carbon fiber felt(TiCF)preform through vacuum impregnation and solvothermal method.The as-prepared aerogel com-posite possesses a low density(0.30–0.32 g/cm^(3)),low thermal conductivity(0.034 and 0.312 W/(m K)in the z and xy directions),and excellent thermal stability with 13.86%residual weight at 1300℃ in air.It is worthwhile to note that the TiCF/PR composite exhibits excellent antioxidant ablation and infrared(IR)radiation shielding properties in a high-temperature heating environment.With an oxygen-acetylene blaze heating of 1.5 MW/m^(2) for 150 s,the linear ablation rates decreased by 13.4%,and the backside temperature reduced from 322.3 to 179.1℃ compared to that of the sample without nano-TiO_(2) coating.The experimental and theoretical analysis showed that the present TiCF/PR nanocomposite has competitive and potential application prospects in the field of future TPMs.
