A Comparative Study on the Oxidative Stability of Polycarbosilane-Based Cf/C–SiC and Cf/SiC Composites

Abstract

A carbon/carbon–silicon carbide (C/C–SiC) composite was prepared by first fabricating a C/C preform using carbon fiber and phenolic resin and subsequently densifying with a polymer precursor of SiC, viz., polycarbosilane (PCS). The C/SiC composite was realized by using PCS. These composites were machined and were subjected to oxidation resistance tests at 1,000°C and 1,500°C under a constant flow of air (6 slpm (standard litre per minute)) for a total duration of 60 min. The oxidation study was extended to the porous C/C preform and a commercially available dense C/C composite. The plot of mass loss versus time for all four types of composites indicates early saturation of mass loss for C/SiC, delayed saturation for C/C–SiC, whereas there was no saturation for C/C composites. The reasons for this behavior are analyzed using a scanning electron microscope equipped with an electron dispersive spectrometer, which reveal that the higher SiC content in C/SiC composite is responsible for self-sealing of the pores even at 1,500°C, whereas the lesser SiC content in C/C–SiC composite and C/C composites is unable to deliver the same results for the chosen set of experiments.