Processing and properties of 2D-Cf/SiC composites incorporating SiC fillers

Carbon fiber cloth reinforced silicon carbide (2D-Cf/SiC) composites were prepared through polycarbosilane (PCS)/divinylbenzene (DVB) pyrolysis with SiC as inactive filler. Then, six infiltration–curing–pyrolysis cycles were conducted to densify the composites. Effects of the SiC filler content on the structure and properties of 2D-Cf/SiC composites were investigated. The results showed that the flexural strengths of the unfilled composites was low because big pores existed in the composites that led to stress concentration. The strengths of the composites were increased with increasing SiC filler content from 0 to 30 wt%. But when the SiC filler content exceeded 30 wt%, the fiber fraction would decrease sharply and SiC particles would hurt the carbon fibers seriously. Therefore, the flexural strengths of the composites were also decreased. It was found that when fabricated with 30 wt% SiC the composites exhibited highest flexural strength, reached 246.4 MPa. The flexural strengths of the unfilled and filled composites after three to six cycles were also measured by a three-point bending test. It was found that the addition of SiC fillers eliminated the delamination problem and increase the mechanical properties at a low number of cycles. Furthermore, much higher flexural modulus were obtained for the filled composites because of the higher modulus of the SiC fillers relative to the SiC matrix derived from the PCS/DVB pyrolysis.