Liquid polycarbosilane-derived C/C-SiC composites with improved mechanical strength for high temperature applications

In the present study, liquid polycarbosilane (LPCS) has been synthesized in the form of low viscous resin, by the heat-treatment of polydimethylsilane (PDMS) in an autoclave at 400 °C for 5 h. The spectral and thermal characterizations carried out at different processing stages indicate the formation of polycarbosilane with high Si-H content. LPCS gave ceramic residue of 34% at 900 °C in argon atmosphere. XRD pattern of 1500 °C heat-treated LPCS, indicates the formation of silicon carbide. LPCS was used as infiltrating resin for the preparation of C/C-SiC composite without any interfacial coating over the T-300 carbon fabric reinforcement. Flexural strength value of 64 MPa for C/C-SiC specimen with density of 1.36 g/cm3 was obtained after six infiltration and pyrolysis cycles. Fractured surface was characterized by SEM which indicates the formation of nano- to submicron wires in the pores of the hybrid composite.