SiC-based multilayered composites containing short carbon fibres obtained by tape casting

Silicon carbide multilayered composites containing short carbon fibres were prepared by tape casting followed by pressureless sintering. The dispersion of fibres into the SiC slurry was studied either by ultrasonics or by mechanical agitation, choosing the best solvent-dispersant couple that was compatible with the requirements of the tape casting technique. The effect of sintering temperature was studied, using carbon and boron as sintering aids, and mechanical properties were measured on composites containing from 5 vol.% to 25 vol.% of short carbon fibres. The results show that carbon fibres inhibit the complete densification of the sintered samples, and mechanical properties suffer from the high residual porosity. Since tape casting demonstrated to be a good technique to align the fibres along the casting direction, different architectures were tested for the composites, studying the effect of fibres alignment direction on the mechanical properties.