采用化学气相渗透法制备含热解碳界面层的SiCf/SiC复合材料,研究热氧化对复合材料在8.2-12.4 GHz波段的介电和吸波性能影响。复介电常数的实部和虚部在氧化后都降低。当氧化100 h后,反射损耗超过-10 d B的波段范围为9.7-11.9 GHz,且反射损耗最小值在11.0 GHz时达到-11.4 dB。复合材料的弯曲强度在氧化后降低,但断裂韧性明显提高。结果表明:含热解碳界面层的SiCf/SiC复合材料氧化后具有很好的吸波性能和断裂韧性。
The SiCf/SiC composites containing PyC interphase were prepared by chemical vapor infiltration process. The influences of thermal oxidation on the complex permittivity and microwave absorption properties of Si Cf/Si C composites were investigated in the frequency range of 8.2-12.4 GHz. Both the real and imaginary parts of the complex permittivity decreased after thermal oxidation. The composites after 100 h thermal oxidation showed that reflection loss exceeded-10 d B in the frequency of 9.7-11.9 GHz and the minimum value was-11.4 d B at 11.0 GHz. The flexural strength of composites decreased but fracture behavior was improved obviously after thermal oxidation. These results indicate that the SiCf/SiC composites containing PyC interphase after thermal oxidation possess good microwave absorbing property and fracture behavior.