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

Abstract The SiC fibers are essential for designing microwave absorption and mechanical properties of multifunctional composites. In this study, SLF, KD-II and KD-S SiC fibers were used to fabricate SiC f /SiC composites. The SLF SiC fibers are composed by amorphous SiOC. The KD-II and KD-S SiC fibers exhibit higher crystallizations and free carbon content. 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. The microwave absorption property of the SLF SiC f /SiC composites can be obtained over -25 dB with a thickness of 2.3 mm and the effective absorption bandwidth (EAB) 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 the whole X band when the thickness varies from 2 to 2.9 mm. KD-S SiC f /SiC composites can be obtained over -9dB with the thickness of 2mm and the EAB below -7 dB reaches 4.12 GHz with a thickness of 2.2 mm. The mechanisms of mechanical, microwave absorption and penitential applications for SiC f /SiC composites are also discussed.