Properties of Si/SiC ceramic composite subjected to chemical vapour infiltration

Si/SiC ceramic composite was prepared by infiltration of liquid silicon into carbon preforms that was made from cotton fabric and phenolic resin. This composite was subjected to the chemical vapour infiltration (CVI), using methyltrichlorosilane as a precursor gas. The effect of infiltration time on densification and mechanical properties was studied. Results show a significant improvement in density by pore closure. Flexural strength increases with increasing infiltration time. However, beyond 60 h of infiltration, the strength improvement was insignificant. The high temperature oxidation resistance of the above ceramics was also studied. The CVI treated samples show considerable resistance to oxidation compared to untreated samples. Thermogravimetric analysis also confirmed the better oxidation resistance of the CVI treated samples.