Ablation properties of three dimensional needled C/C-SiC composites

Three dimensional needled carbon/carbon-silicon carbide composites were prepared by chemical vapor infiltration + precursor impregnation pyrolysis(CVI+PIP) combined process.The ablation properties were investigated by using oxyacetylene ablation technique while the flow ratio between oxygen and ethyne was 2∶1,and the ablation duration time was 600 s.Ablated surfaces of the samples were investigated by using scanning electron microscopy and energy dispersive spectroscopy.The results show that the linear and mass ablation rates of C/C-SiC composites were 0.004 3 mm/s and 0.001 4 g/s,respectively;the ablation morphology and mechanism were varied at different positions.At the ablation centre,the ablation of the composites was dominated by oxidation of the matrix and the carbon fiber,as well as the mechanical erosion.Between the ablation center and the edge,the ablation mechanisms of the composites mainly were oxidation of SiC matrix and mechanical erosion.At the edge,the ablation of the composites was dominated by thermo-oxidation.So 3D C/C-SiC composites under the oxyacetylene ablation conditions are synergistic effects of thermo-oxidation ablation,thermo-physics ablation and mechanical erosion.