Ablation resistance of double-layer SiC/ZrB 2 -SiC-La 2 O 3 coating for SiC-coated graphite exposed to oxyacetylene torch

Abstract

The ablation resistance of double-layer SiC/ZrB₂-SiC-La₂O₃ coating for SiC-coated graphite at temperatures of 1600∼2100^oC was investigated by exposure test of an oxyacetylene torch. The double-layer structure of the as-prepared SiC/ZrB₂-SiC-La₂O₃ coating guaranteed its ablation resistance in a wide temperature range. The results showed that the linear ablation rates and the mass ablation rates of the tested samples increased with increasing ablation temperature. At 1600^oC, the SiC outer layer could protect the underneath coating effectively due to the formation of a SiO₂ scale. The evaporation of SiO₂ became severe with increasing ablation temperature, where ablation resistance was provided by the sintered ZrO₂ scale.