New technology for fabrication of C/SiC composites reinforced by continuous carbon tows

Carbon/silicon carbide composites were fabricated using the continuous synchronous composite (CSC) process, which is an improved technology based on conventional chemical vapour infiltration principles to fabricate ceramic matrix composites reinforced with carbon cloth or continuous tows which are not braided to a preform. In the CSC process, a gradient temperature field on the surface of the graphitic substrate, consisting of high (1000-1200°C), intermediate (900-1000°C), and low (700-900°C) temperature regions, was obtained by a bottom heating element. Since the rotation of the substrate accompanied simultaneously the preparation of the reinforcement phase and the deposition of the SiC matrix, micropores were well infiltrated in the intermediate temperature regions by diffusion transport, and macropores were well infiltrated in the high temperature regions with flow transport, respectively. Using methyltrichlorosilane (MTS) as a precursor, with hydrogen as a carrying gas and argon gas as a diluent, in the present studies, densification of C/SiC composites was uniform, and the highest deposition rate obtained was 0.168 mg cm^-2 min^-1), and the conversion efficiency of MTS varied from 31% to a maximum of 47%.