Effects of ablation at different regions in three-dimensional orthogonal C/SiC composites ablated by oxyacetylene torch at 1800℃

摘要

C/SiC composites were prepared by polycarbosilane infiltration pyrolysis and ablated by oxyacetylene flame at 1800 ℃ for 180s. Morphology and microstructure of C/SiC have been studied by scanning electron microscopy/energy dispersive spectroscopy, and X-ray diffraction analysis. Two concentric ring regions appeared on the surface of the ablated C/SiC. In the centre region of the ablated C/SiC was composed of irregular SiC particles with a lot of pores. The pores were resulted from (i) gas expansion in closed pores during ablation, and (ii) from the release of SiO gas produced by the oxidation of SiC with sufficiently low oxygen partial pressure. The results indicated the ablation was due to a combination of oxidation, mechanical erosion and recrystallization of the surface SiC.