Mechanical and microwave absorption properties of Ti-filled SiCf/SiC composites via precursor infiltration and pyrolysis

SiC fiber reinforced SiC ceramic matrix composite is a kind of promising high-temperature structure absorbing integrated material because of its good temperature resistance and high-temperature stability. However, the mechanical properties of the composites are poor and it is difficult to adjust the electromagnetic parameters. In this study, Ti powders were used as active fillers to improve the mechanical and microwave absorption properties of SiCf/SiC composites fabricated by polymer infiltration and pyrolysis (PIP) process. The compositions of SiC matrix derived from polycarbosilane (PCS) precursor modified by various content Ti powders were investigated by XRD and Raman spectroscopy. With the incorporation of Ti powders, free carbon decomposed from PCS was consumed due to the formation of TiC phase. The effect of Ti fillers on the mechanical and dielectric properties of SiC/SiC composites was also investigated. The flexural strength of SiCf/SiC composite was gradually improved with increasing Ti content owing to the improved density and TiC particle strengthening. Besides, consumption of free carbon in SiC matrix may impair the conductive network of free carbon, leading to decreased conductivity and the imaginary part of complex permittivity of the composite. Therefore, an optimum microwave absorption performance of SiCf/SiC composite with an RLm value of - 37 dB at 10.51 GHz and an effective absorption bandwidth of 3.28 GHz was obtained at the thickness of 2.5 mm and the Ti content of 5 wt%. The Ti-filled SiCf/SiC composite with superior microwave absorption property is a promising candidate in the high-temperature structure absorbing field.