CHEMICAL VAPOR INFILTRATION OF SIXC1-X FILMS FOR THE PREPARATION OF COMPOSITE-MATERIALS USING BOTH ORGANOSILICON AND HYDROCARBON PRECURSORS

The chemical vapour infiltration of porous carbon fibre preforms by SixC1-x has been investigated. SiEt4 has been used as both volatile silicon and carbon source and a further carbon enrichment of these films has been achieved by addition of cumene in the gas phase. The composition of infiltrated films is not significantly different from that of coatings grown on the outer surface of the samples. The infiltration efficiency defined by the thickness uniformity inside the porous preforms has been found to be better at low pressure and low temperature. However, weight gain measurements have revealed a slow rate of deposition in such conditions. The infiltration quality is discussed in terms of both these factors as a function of temperature, pressure and initial gas phase composition to evaluate the most appropriate conditions for large-scale applications of this process.