2D SiC/SiC复合材料电阻率对服役环境的响应特性

Response of 2D SiC/SiC Composites Resistivity to Service Environments

研究针对不同服役环境下2DSiC/SiC复合材料的电阻率特性进行了研究。从1300℃降至室温的无氧环境中,复合材料的电阻率随温度降低而增大;借助曲线拟合,建立了电阻率与温度之间的映射关系。在1300℃空气环境中氧化20和60 h后,由于PyC界面层和SiC基体的氧化,复合材料的导电性显著降低;以SiO_(2)的含量定量表征氧化程度,建立了电阻率与氧化损伤之间的映射关系。复合材料的电阻率和应力随应变的变化趋势相似,电阻率变化率和刚度随应变的变化趋势相反。在线性阶段,基体开裂数量极少,刚度几乎不变,电阻率缓慢增大;在非线性阶段,基体开裂数量增加较快,造成刚度降低,电阻率快速增大;后半段的基体裂纹数量缓慢增多,刚度和电阻率变化率趋于平稳。

The resistivity characteristics of 2D SiC/SiC composites were studied experimentally. In the oxygen-free environment, the resistivity increases when temperature decreases. With curve fitting, the mapping relationship between resistivity and temperature is established. After oxidation at 1300 ℃ in the air for 20 and 60 h, the conductivity of composites is greatly reduced due to the oxidation of the PyC interface and the SiC matrix. The degree of oxidation was characterized by the content of SiO_(2), and the quantitative relationship between resistivity and oxidative damage was obtained. The changes in resistivity and stress with strain are similar. In the linear segment of stress-strain curve, with few matrix cracks the stiffness is almost unchanged, and the resistivity increases slowly. In the non-linear section, the resistivity rate and stiffness increase quickly because crack increases rapidly. They eventually stabilize when the increase in cracks slows down.