径棒法编织C/C复合材料高温拉伸性能研究

Tensile Behavior of C/C Composites Woven with Radial Carbon Rods Under High Test Temperature

采用化学气相沉积、沥青浸渍-高压碳化混合致密工艺向径棒法编织的预制体内引入基体碳,实现高密度(≥1.94g/cm3)炭/炭复合材料制备。利用快速通电加热测试技术,模拟C/C复合材料的高温工作环境,研究不同温度下材料的环向拉伸性能。结果表明:在2 300℃时,材料拉伸强度最大(80.3 MPa),断裂应变随着温度的升高而增加。采用扫描电镜对试样及断口形貌进行观察,发现测试温度、机加损伤及试样过渡区应力集中影响材料断裂特征。温度为1 800℃、2 300℃时材料在过渡区断裂;温度为2 800℃时,材料在标距区发生破坏,纤维与基体界面结合强度低,纤维拔出多,表现出假塑性断裂特征。

The C/C composites woven with radial carbon rods were prepared by combination densification process of chemical vapor infiltration(CVI)and pitch impregnation/high pressure carbonization(HPIP).By applying fast electric heating techniques,the high temperature condition of C/C composites was simulated and the circular tensile properties of C/C composites under different temperature was studied.The results showed that the maximum tensile strength was 80.3 MPa at 2 300℃,failure strain increased with increasing temperature.It was also found that the fractured characters of C/C composites were related to test temperature,machining damage and stress concentration in transition region by observation the samples and their fracture morphology with SEM.The failure position of samples was in transition region at 1 800℃and 2 300℃.However,the test temperature was 2 800℃,the fractured surface were made of the interface with weak bonding and more fiber pulling out in gauge length region,showed pseudo-plastic failure.