Effects of thermal oxidation on microwave-absorbing and mechanical properties of SiCf/SiC composites with PyC interphase
(1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China;
2. College of Materials and Mineral Resources, Xi’an University of Architecture and Technology, Xi’an 710055, China)
2. College of Materials and Mineral Resources, Xi’an University of Architecture and Technology, Xi’an 710055, China)
Abstract: 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 SiCf/SiC 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 dB in the frequency of 9.7-11.9 GHz and the minimum value was -11.4 dB 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.
Key words: SiCf/SiC composites; thermal oxidation; dielectric properties; microwave absorbing; mechanical properties