Ablation resistance of different coating structures for C/ZrB₂ -SiC composites under oxyacetylene torch flame

C/ZrB₂-SiC composites were fabricated by polymer infiltration and pyrolysis combined with slurry impregnation method. Three kinds of coating structures for these composites were applied in order to improve their ablation resistance: pure silicon carbide coatings, ZrB₂ -SiC mixture coatings, and ZrC-SiC alternating multilayer coatings. The ablation experiments were carried out on an oxyacetylene torch flame with a temperature of about 3000°C. The ZrC-SiC alternating multilayer showed the best ablation resistance. The linear erosion rate for ZrC-SiC alternating multilayer coatings is half of that for ZrB₂-SiC mixture and pure SiC coatings. A model was put forward to account for such a result.