Carbon fiber reinforced carbon composites(C/Cs),are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields,owing to their superior performances.However,C/Cs are ve...Carbon fiber reinforced carbon composites(C/Cs),are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields,owing to their superior performances.However,C/Cs are very susceptible to destructive oxidation and thus fail at elevated temperatures.Though matrix modification and coating technologies with Si-based and ultra-high temperature ceramics(UHTCs)are valid to enhance the oxidation/ablation resistance of C/Cs,it’s not sufficient to satisfy the increasing practical applications,due to the inherent brittleness of ceramics,mismatch issues between coatings and C/C substrates,and the fact that carbonaceous matrices are easily prone to high-temperature oxidation.To effectively solve the aforementioned problems,micro/nano multiscale reinforcing strategies have been developed for C/Cs and/or the coatings over the past two decades,to fabricate C/Cs with high strength and excellent high-temperature stability.This review is to systematically summarize the most recent major and important advancements in some micro/nano multiscale strategies,including nanoparticles,nanowires,carbon nanotubes/fibers,whiskers,graphene,ceramic fibers and hybrid micro/nano structures,for C/Cs and/or the coatings,to achieve high-temperature oxidation/ablation-resistant C/Cs.Finally,this review is concluded with an outlook of major unsolved problems,challenges to be met and future research advice for C/Cs with excellent comprehensive mechanical-thermal performance.It’s hoped that a better understanding of this review will be of high scientific and industrial interest,since it provides unusual and feasible new ideas to develop potential and practical C/Cs with improved high-temperature mechanical and oxidation/ablation-resistant properties.展开更多
用液相浸渍 裂解聚硅烷工艺制备了C C SiC复合材料,对比了C C与C C SiC复合材料的氧化及烧蚀性能,用扫描电镜(SEM)和X射线衍射(XRD)分析了氧化与烧蚀前后的微观结构及物相变化.结果表明:C C SiC复合材料使C C复合材料的氧化起始温度从50...用液相浸渍 裂解聚硅烷工艺制备了C C SiC复合材料,对比了C C与C C SiC复合材料的氧化及烧蚀性能,用扫描电镜(SEM)和X射线衍射(XRD)分析了氧化与烧蚀前后的微观结构及物相变化.结果表明:C C SiC复合材料使C C复合材料的氧化起始温度从500℃提高到700℃;在600℃和700℃恒温氧化条件下,C C SiC复合材料比C C复合材料的氧化速率分别降低38%和47%,失重率分别降低35%和47%;C C SiC复合材料的耐烧蚀性能优于C C复合材料.展开更多
Ablation characteristics and mechanism at high temperature for TaC coatings on carbon-carbon composites were investigated by ablation experiments with low power laser and oxyacetylene flame. The results show that the ...Ablation characteristics and mechanism at high temperature for TaC coatings on carbon-carbon composites were investigated by ablation experiments with low power laser and oxyacetylene flame. The results show that the TaC coating is decomposed at the initial stage of laser ablation in atmosphere, and free carbon diffused to the surface, then oxidized to the melt including carbon, oxygen and tantalum. With the increase of ablation time, the melt is oxidized to low valent tantalum-oxide and Ta2O5 is formed finally. During the melt cooling, needle-like crystals of Ta2O5 are precipitated. Between the melt and TaC coating, there exists a diffusion transition layer with thickness of 1-2 μm. The transition layer consists of fine crystals and pores including carbon, oxygen and tantalum. The oxyacetylene flame ablation at 2 300 ℃ results in the rapid oxidation of TaC and formation of protective liquid films of tantalum oxide on the coating surface, where the liquid film can fill up the cracks and cover the coating. In such case, the oxidation mechanism of TaC is converted to the oxygen solution and diffusion control mechanism.展开更多
Multicomponent ultra-high temperature ceramics(UHTCs)are promising candidates for thermal protection materials(TPMs)used in aerospace field.However,finding out desirable compositions from an enormous number of possibl...Multicomponent ultra-high temperature ceramics(UHTCs)are promising candidates for thermal protection materials(TPMs)used in aerospace field.However,finding out desirable compositions from an enormous number of possible compositions remains challenging.Here,through elucidating the role of preferential oxidation in ablation behavior of multicomponent UHTCs via the thermodynamic analysis and experimental verification,the correlation between the composition and ablation performance of multicomponent UHTCs was revealed from the aspect of thermodynamics.We found that the metal components in UHTCs can be thermodynamically divided into preferentially oxidized component(denoted as MP),which builds up a skeleton in oxide layer,and laggingly oxidized component(denoted as ML),which fills the oxide skeleton.Meanwhile,a thermodynamically driven gradient in the concentration of MP and ML forms in the oxide layer.Based on these findings,a strategy for pre-evaluating the ablation performance of multicomponent UHTCs was developed,which provides a preliminary basis for the composition design of multicomponent UHTCs.展开更多
基金supported by the National Natural Science Foundation of China(Nos.91860203,51821091,51872239,52002321 and 52061135102)the China Postdoctoral Science Foundation(No.2019M660265)+3 种基金the Fundamental Research Funds for the Central Universities(China,Nos.G2019KY05116,G2020KY05125)the Innovation Talent Promotion Plan of Shaanxi Province for Science and Technology Innovation Team(No.2020TD003)the Creative Research Foundation of Science and Technology on Thermostructural Composite Materials Laboratory(Nos.614291102010517,5050200015 and 5150200033)the Shaanxi Provincial Education Department of China(No.2020JQ-170)。
文摘Carbon fiber reinforced carbon composites(C/Cs),are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields,owing to their superior performances.However,C/Cs are very susceptible to destructive oxidation and thus fail at elevated temperatures.Though matrix modification and coating technologies with Si-based and ultra-high temperature ceramics(UHTCs)are valid to enhance the oxidation/ablation resistance of C/Cs,it’s not sufficient to satisfy the increasing practical applications,due to the inherent brittleness of ceramics,mismatch issues between coatings and C/C substrates,and the fact that carbonaceous matrices are easily prone to high-temperature oxidation.To effectively solve the aforementioned problems,micro/nano multiscale reinforcing strategies have been developed for C/Cs and/or the coatings over the past two decades,to fabricate C/Cs with high strength and excellent high-temperature stability.This review is to systematically summarize the most recent major and important advancements in some micro/nano multiscale strategies,including nanoparticles,nanowires,carbon nanotubes/fibers,whiskers,graphene,ceramic fibers and hybrid micro/nano structures,for C/Cs and/or the coatings,to achieve high-temperature oxidation/ablation-resistant C/Cs.Finally,this review is concluded with an outlook of major unsolved problems,challenges to be met and future research advice for C/Cs with excellent comprehensive mechanical-thermal performance.It’s hoped that a better understanding of this review will be of high scientific and industrial interest,since it provides unusual and feasible new ideas to develop potential and practical C/Cs with improved high-temperature mechanical and oxidation/ablation-resistant properties.
文摘用液相浸渍 裂解聚硅烷工艺制备了C C SiC复合材料,对比了C C与C C SiC复合材料的氧化及烧蚀性能,用扫描电镜(SEM)和X射线衍射(XRD)分析了氧化与烧蚀前后的微观结构及物相变化.结果表明:C C SiC复合材料使C C复合材料的氧化起始温度从500℃提高到700℃;在600℃和700℃恒温氧化条件下,C C SiC复合材料比C C复合材料的氧化速率分别降低38%和47%,失重率分别降低35%和47%;C C SiC复合材料的耐烧蚀性能优于C C复合材料.
基金Project(2007AA03Z110) supported by the National Hi-tech Research and Development Program of ChinaProject(50721003) supported by the National Natural Science Foundation of China+2 种基金Project(20070420822) supported by China Postdoctoral Science FoundationProject(2007RS4027) supported by the Postdoctoral Science Foundation of Hunan Province, ChinaProject(2007) supported by the Postdoctoral Science Foundation of Central South University, China
文摘Ablation characteristics and mechanism at high temperature for TaC coatings on carbon-carbon composites were investigated by ablation experiments with low power laser and oxyacetylene flame. The results show that the TaC coating is decomposed at the initial stage of laser ablation in atmosphere, and free carbon diffused to the surface, then oxidized to the melt including carbon, oxygen and tantalum. With the increase of ablation time, the melt is oxidized to low valent tantalum-oxide and Ta2O5 is formed finally. During the melt cooling, needle-like crystals of Ta2O5 are precipitated. Between the melt and TaC coating, there exists a diffusion transition layer with thickness of 1-2 μm. The transition layer consists of fine crystals and pores including carbon, oxygen and tantalum. The oxyacetylene flame ablation at 2 300 ℃ results in the rapid oxidation of TaC and formation of protective liquid films of tantalum oxide on the coating surface, where the liquid film can fill up the cracks and cover the coating. In such case, the oxidation mechanism of TaC is converted to the oxygen solution and diffusion control mechanism.
基金supported by the National Natural Science Foundation of China(52072410 and 51602349)Innovation-driven Project of Central South University.
文摘Multicomponent ultra-high temperature ceramics(UHTCs)are promising candidates for thermal protection materials(TPMs)used in aerospace field.However,finding out desirable compositions from an enormous number of possible compositions remains challenging.Here,through elucidating the role of preferential oxidation in ablation behavior of multicomponent UHTCs via the thermodynamic analysis and experimental verification,the correlation between the composition and ablation performance of multicomponent UHTCs was revealed from the aspect of thermodynamics.We found that the metal components in UHTCs can be thermodynamically divided into preferentially oxidized component(denoted as MP),which builds up a skeleton in oxide layer,and laggingly oxidized component(denoted as ML),which fills the oxide skeleton.Meanwhile,a thermodynamically driven gradient in the concentration of MP and ML forms in the oxide layer.Based on these findings,a strategy for pre-evaluating the ablation performance of multicomponent UHTCs was developed,which provides a preliminary basis for the composition design of multicomponent UHTCs.
