Effect of different kinds of SiC fibers on microwave absorption and mechanical properties of SiC_f/SiC composites

The SiC fibers are essential for designing microwave absorption and mechanical properties of multifunctional composites. In this study, SiC_f/SiC composites were fabricated by SLF, KD-II, and KD-S SiC fibers. The SLF fibers are composed by amorphous SiOC. The KD-II and KD-S fibers reveal higher crystallizations. The conductivity of SLF, KD-II, and KD-S SiC fibers are 0.0127, 1.184, and 0.1316 S/cm, respectively. The flexural strength of SLF, KD-II, and KD-S SiC_f/SiC composites are 147.77, 322.57, and 248.16 MPa, respectively. With the thickness of 2.3 mm, the microwave absorption property of SLF SiC_f/SiC composites is over − 25 dB in X band. Additionally, the effective absorption bandwidth (EAB) of SLF SiC_f/SiC composites below − 10 dB reaches 3.72 GHz with the thickness of 2.7 mm. In contrast, the KD-II SiC_f/SiC composites only reach − 3.6 dB in X band when the thickness varies from 2 to 2.9 mm. With the thickness of 2 mm, the microwave absorption property of KD-S SiC_f/SiC composites is over − 9 dB. With the thickness of 2.2 mm, the EAB of KD-S SiC_f/SiC composites below − 7 dB reaches 4.12 GHz. The mechanisms of mechanical, microwave absorption, and penitential applications for SiC_f/SiC composites are also discussed.