Microwave heated chemical vapour infiltration of SiC powder impregnated SiC fibre preforms

A microwave heated methyl trichlorosilane based chemical vapour infiltration technique has been used to form SiCf/SiC composites from SiC fibre preforms preimpregnated with SiC powder using two different fabrication techniques. While infiltration rates obtained from samples loaded with powder were generally higher than for preforms without powder, preferential infiltration occurred in regions where the SiC powder was most concentrated as a result of the initial non-uniform distribution of the powder across the preforms. The consequence was density gradients in the final composites. Nevertheless, average densities as high as 75% could be achieved in a 10 h process.