Fabrication of short carbon fibre reinforced SiC multilayer composites by tape casting

Silicon carbide multilayer composites containing short carbon fibres (Csf/SiC) were prepared by tape casting and pressureless sintering. C fibres were dispersed in solvents and then mixed with SiC slurry to make green Csf/SiC tape. Triton X-100 was found to be the best one for Toho Tenax HTC124 fibres (with water soluble coating) among BYK-163, BYK-410, BYK-2150, BYK-9076, BYK-9077 and Triton X-100 dispersants. Csf/SiC multilayer composites containing 5vol.% fibre (mean fibre length of 3, 4.5, and 6mm) were obtained. Addition of short C fibres seems to worsen the densification process in the Csf/SiC multilayer composites, whereas anisotropy shrinkage in Csf/SiC was also observed. Open pores size was increased slightly after the addition of C fibre but it decreased with the mean fibre length. Mechanical properties were affected by high residual porosity. The addition of short C fibre has not changed the crack deflection at weak interfaces. Csf/SiC multilayer composites containing longer fibres (4.5 and 6mm) presented higher elastic modulus, bending strength and Vickers hardness as compared to shorter fibres (3mm). Improved sintering performance and fibre content are necessary to improve mechanical properties.