电耦合CVI制备穿刺C/C喉衬材料的微结构及性能

Micro-structure and properties of fine weave pierced C/C throat with electrically coupled CVI

采用电耦合化学气相渗透(CVI)联合树脂浸渍碳化工艺制备了穿刺碳纤维预制体增强C/C喉衬材料,利用μ-CT表征了穿刺C/C材料增密不同阶段孔隙尺寸,研究了该材料2 800℃拉伸性能和缩比固体发动机烧蚀性能。结果表明,电耦合CVI增密后穿刺C/C喉衬材料孔隙主要存在于纤维束间,呈现空间联通的网状结构,树脂碳循环致密后材料内部仍残存少量体积0~0.08mm^3的微小孔隙,孔隙呈现孤立的点分布状态。穿刺C/C材料2 800℃拉伸强度略高于室温,断裂应变比室温提高118%,表现出优异的非线性断裂行为。穿刺C/C喉衬缩比固体发动机点火试验后线烧蚀率0.077mm/s,喉衬不同区域的烧蚀机制有一定差异,喉衬收敛段穿刺纤维束承受驻点烧蚀,产生蜂窝状烧蚀凹坑,烧蚀较严重,喉部和扩散段烧蚀较为平滑。

Fine weave pierced C/C throat was fabricated using electrically coupled chemical vapour impregnation（CVI）process together with resin infiltration and carbonization method.The pore size of fine weave pierced preform at different densification stages was characterized byμ-CT.Tensile properties of the samples at 2 800℃ and the ablation behaviors of the scaling down motor were also discussed.The results show that pores are located in between the fiber bundles in the material after the electrically coupled CVI,where the pores joint their boundaries to form the carbon body a net structure.Some micro pores,which sized 0-0.08 mm-3 and scattered dispersed in the body,were left after several resin infiltration and carbonization cycles.The tensile strength is a little higher,but the fracture strain is increased by 118% at 2 800℃ than that at room temperature,which mean that the material possesses abnormal non-liner fracture behavior.The liner ablation rate is 0.077 mm/s for the material in a scaling solid motor.There are different ablation mechanisms for different throat parts：there are severe stagnations ablation at the convergent part which caused the honeycomb ablation dots,while the throat and divergent part have smooth ablation surfaces.