不同ZrC含量的(C/C)/SiC-ZrC复合材料的抗烧蚀性能

Anti-ablative property of(C/C)/SiC-ZrC composites with different ZrC content

采用先驱体转化(PIP)法制备了不同ZrC含量的(C/C)/SiC-ZrC复合材料,考察了ZrC含量对复合材料微观结构和抗烧蚀性能的影响。结果表明,氧乙炔烧蚀600 s后,(C/C)/SiC复合材料表面疏松,出现了较大的烧蚀凹坑;而(C/C)/SiC-ZrC复合材料表面相对较致密,被白色氧化物质覆盖,烧蚀率均有所降低。在较低的ZrC含量下,(C/C)/SiC-ZrC复合材料表面形成ZrO2-SiO2二元共熔体系氧化膜,有效抑制氧化性气氛向复合材料内部渗透,同时氧化物不断熔化和挥发,降低了复合材料烧蚀表面的温度;而当ZrC体积分数为12.4vol%时,在烧蚀过程中(C/C)/SiC-ZrC复合材料表面能形成一个ZrO2外层/SiO2内层的双层结构保护膜,ZrO2是一种优异的热障材料,且导热系数较低,使烧蚀过程中烧蚀区域热扩散降低,因此(C/C)/SiCZrC复合材料表现为较高的表面温度,但双层氧化膜阻挡有氧气氛进一步进入复合材料内部,使复合材料表现出优异的抗烧蚀性能。

The(C/C)/SiC-ZrC composites with different ZrC content were fabricated by precursor infiltration and pyrolysis(PIP)process,and effects of the ZrC content on the microstructures and anti-ablative properties of the(C/C)/SiC-ZrC composites were investigated.The results show that after oxyacetylene ablation 600 s,the surface of(C/C)/SiC composites are loose,and a rather large ablation pit appeared.Whereas the surface of(C/C)/SiC-ZrC composites are compact relatively and coverd by white oxide.Compared with(C/C)/SiC composites,ablation rate of(C/C)/SiC-ZrC composites with different ZrC content decreases.When the ZrC content is low,ZrO2-SiO2 binary eutectic systems a oxide film is formed on the surface,which can effectively prevent the infiltration of oxidation atmosphere,and also the oxide melt and volatilize continuously,which can reduce temperature of ablation surface of the(C/C)/SiC-ZrC composites.When the ZrC volume fraction rises to 12.4 vol%,outer ZrO2 and inner SiO2 are formed by the oxidation of ZrC and SiC,respectively.ZrO2 is a excellent heat barrier material with low heat conduction coefficient,which can alleviate the heat diffusion of ablation area during ablation,leading the higher surface temperature of the(C/C)/SiC-ZrC composites,but two dense oxidation film can prevent the corrosion of oxidation atmosphere,resulting in a good ablation resistance of(C/C)/SiC-ZrC composites.