C/C-SiC防热材料快速制备及其性能研究真

Fast fabrication and properties of C/C-SiC thermal insulation composites

采用CVI+PIC工艺制备了密度为1.35～1.45 g/cm3的C/C多孔体,对多孔体进行LSI快速获得C/C-SiC防热材料,表征了防热材料的微观结构、弯曲性能,对其进行300 s氧乙炔烧蚀试验,检测了筒形C/C-SiC燃烧室热结构缩比构件的整体承压性能。结果表明,采用CVI+PIC方法成型的C/C多孔体LSI后,液相Si主要与树脂炭反应,生成的SiC位于纤维束之间的大孔孔隙中,由炭纤维束与其内部和包覆在纤维束表层的热解炭构成的增强相未受液Si浸蚀。制备的C/C-SiC弯曲强度达122 MPa,弯曲破坏呈现明显的假塑性断裂;筒形C/C-SiC燃烧室热结构缩比件(外径175 mm、壁厚7.5 mm、高度200 mm)水压爆破压力为5.2 MPa。C/C-SiC材料氧乙炔试验线烧蚀率0.000 2～0.000 3 mm/s、质量烧蚀率0.000 1～0.000 3 g/s,材料的烧蚀以热化学烧蚀为主,烧蚀型面整体平滑,烧蚀表面形成了SiO2抗氧化玻璃相和Si纳米线。

Porous C/C composites with density of 1.35~1.45 g/cm^3 prepared by“chemical vapor infiltration plus resin impregnation carbonization”(CVI+PIC)combined process have been used to fabricate C/C-SiC thermal protection composites by liquid silicon infiltration(LSI).The microstructure and flexural properties of C/C-SiC composites were identified and characterized.The ablation properties were investigated by oxyacetylene flame with 300 s.Meanwhile, integral bearing performance of C/C-SiC cylindrical combustion scaling model has been investigated. Results show that the liquid Si reacts mainly with the carbon in the resin to form SiC,which is located in the pore space between the fiber bundles.The reinforcements consisting of carbon fiber bundles and pyro-carbon in the interior and surface of the fiber bundles are not etched by liquid Si. The fracture behavior of C/C-SiC composites with the flexure strength up to 122 MPa shows obvious pseudo-plastic fracture.The burst pressure of the C/C-SiC cylindrical combustion scaling model is 5.2 MPa. In oxyacetylene ablation test,the linear ablation rate and mass ablation rate are 0.000 2~0.000 3mm/s and 0.000 1~0.000 3 g/s,respectively. The ablation is mainly caused by heat ablation.The overall ablation profile is smooth,on which the antioxidative SiO2 glass phase and Si nano-wire are observed.