Effect of stitch spacing on mechanical properties of carbon/silicon carbide composites

The effects of stitch spacing on the mechanical properties of the carbon fiber reinforced silicon carbide composites fabricated by chemical vapor infiltration (CVI) were investigated. The results showed that the stitch spacing had little effect on the density and open porosity of the composites. The stitches improved the shear and tensile strengths of all stitched C/SiC composites, by suppressing and delaying the delamination. However, flexural strength was not changed for the composites with stitch spacing of 10 mm or 5 mm, but was slightly reduced for densely stitched composites with spacing of 2.5 mm. The optimum stitch spacing was 5 mm, which improved apparently the interlaminar shear strength and tensile strength of the composites with little detrimental effect on the flexural strength.