碳纤维增韧的陶瓷基复合材料在高温高应变率下的压缩力学行为

Mechanical behaviors of C/SiC composites subjected to uniaxial compression at high temperatures and high strain rates

利用高温电子万能试验机和具有高温同步自组装功能的Hopkinson压杆对二维C/SiC复合材料进行了应变率为10-4～103 s-1,温度为293～1 273K下的单轴压缩力学性能测试。实验结果表明:二维C/SiC复合材料破坏时并未表现出典型的脆性破坏,而是在应力达到压缩强度时出现了显著的应变软化,在经历了较大的变形后才最终破坏,同时材料还表现出良好的高温承载能力及一定的温度和应变率依赖性。随着温度的升高,复合材料的压缩强度呈降低的趋势。与准静态下室温压缩时相比,材料在1 273K时的压缩强度的降低程度不超过30%,但压缩强度对应变率的敏感性随着温度的升高而增大。由于高温下试样氧化,C/SiC复合材料压缩强度对应变率的敏感性在温度为1 073K时显著增大。

By using an electronic universal testing machine and a split Hopkinson pressure bar device,a series of uniaxial compression experiments were carried out to explore the mechanical behaviors of a 2D woven C/SiC composite in the temperature range from 293 to 1 273 K and the strain rate range from 10-4 to 103 s-1.The experimental results show as follows.The composite has excellent high temperature mechanical properties in the tested temperature range.The compressive strength of the composite decreases no more than thirty percent at 1 273 K under quasi-static compression if compared with that at room temperature.Catastrophic brittle failure is not observed for the specimens tested at different strain rates.With the increase of the experimental temperature,the compressive strength of the 2D C/SiC composite decreases,but the dependence of compressive strength on strain rate increases.At the temperatures above 1 073 K,the sensitivity factor of compressive strength on strain rate increases remarkably.It is proposed that the sharp increase in the dependence of compressive strength on strain rate is due to the oxidation of the composites.