Mechanical properties and ablation behavior of C/C-ZrC and C/C-ZrC-SiC composites prepared by precursor infiltration and pyrolysis combined with chemical vapor infiltration

C/C-ZrC and C/C-ZrC-SiC composites were prepared by a combined process of precursor infiltration and pyrolysis and chemical vapor infiltration. C/C-ZrC composites exhibited a higher flexural strength than that of C/C-ZrC-SiC composites. Oxyacetylene torch testing results showed that at the heat flux of 2.38 MW/m(2), compared to C/C-ZrC-SiC composites, the mass and linear ablation rates of C/C-ZrC composites were decreased by 7.5% and 39.2%, respectively, which was ascribed to the developed ZrO2 with a relatively dense and holonomic microstructure. At the heat flux of 4.18 MW/m(2), C/C-ZrC-SiC composites exhibited a lower linear ablation rate than that of C/C-ZrC composites. No effectively protective layers were developed and the spallation formed on the ablated surface of C/C-ZrC and C/C-ZrC-SiC composites as a result of the mechanical denudation of the high speed flame stream.