Thermal ablation behavior of SiBCN-Zr composites prepared by reactive spark plasma sintering.

To meet the ultrahigh temperature requirements of a thermal protection system, an ultrahigh temperature phase of ZrB 2 was introduced into a SiBCN matrix that was fabricated using a reactive spark plasma sintering method. The thermal ablation behavior of SiBCN-Zr composites was investigated using an oxyacetylene flame test. The test results indicated that the ablation behavior of the modified ceramic composites was significantly improved over that of a monolithic SiBCN ceramic. The linear and mass ablation rates of the SiBCN-Zr material were found to be 0.004 mm/s and 4.75×10 −4 g/s, which was indicative of excellent ablation resistance. Analysis of the material after thermal ablation testing showed that ablation products mainly consisted of the ZrSiO 4 , SiO 2 and ZrO 2 phases. A reaction occurred between the SiO 2 and ZrO 2 phases in the central region of the ceramic forming ZrSiO 4 that protected the material from further thermal damage. A loose and porous oxidation layer was found from the matrix based on analysis of a cross-section image. [ABSTRACT FROM AUTHOR]