Effect of preparation conditions on mechanical, dielectric and microwave absorption properties of SiC fiber/mullite matrix composite

摘要

Silicon carbide fiber-reinforced mullite matrix (SiCf/Mu) composites were fabricated via an infiltration and sintering method. Effects of sintering parameters on microstructure, mechanical, dielectric and microwave absorption properties of SiCf/Mu composites have been investigated. The flexural strength is significantly improved with increasing sintering temperature, and the highest flexural strength of 213 MPa is obtained in vacuum at 1000 degrees C for 2 h. The performances of composites with different holding time are further studied at 1000 degrees C. The flexural strengths of composites sintered at 1000 degrees C for 2 and 4 h reach 213 and 219 MPa, respectively. The failure displacement of the composite sintered at 1000 degrees C for 4 h reaches 0.39 mm. The excellent microwave absorption properties are achieved for the composite sintered at 1000 degrees C for 2 h. The minimum reflection loss (RL) reaches -38 dB with a thickness of 2.9 mm at 12 GHz and the effective absorbing bandwidth (RL <= -10 dB) with a thickness of 3.4 mm covers the whole X - band, which indicate that SiCf/Mu composite is a good candidate for microwave absorbing materials. These results provide valuable solutions to obtaining structural-functional materials for microwave absorption applications in civil and military areas.