Morphology and microstructure of three-dimensional orthogonal C/SiC composites ablated by an oxyacetylene flame at 2900°C

Abstract

C/SiC composites were prepared by polycarbosilane infiltration pyrolysis and ablated by oxy-acetylene flame at 2900°C for 180s. The morphology and microstructure of C/SiC were observed by scanning electron microscopy. The phase transition and the composition were confirmed by energy-dispersive spectroscopy and X-ray diffraction. The ablation rates of the center region and the outer region were 2.5 and 1.1μm/s, respectively. The ablated C/SiC was covered by a turbostratic carbon coating resulting from the pyrolysis of acetylene. White dross attached on the surface was composed of SiO2 resulting from the sublimation and decomposition of SiC during ablation and oxidization of Si and SiC during cooling. The results indicated that the ablation was due to a combination of carbon coating deposition, decomposition of SiC, oxidation, and mechanical erosion. © 2009 American Ceramic Society.