Long time ablation behaviors of designed ZrC-SiC-TiC ternary coatings for environments above 2000 °C

Thermal protection systems with long time anti-ablation property for applications in ultrahigh temperature environments have been a choke point for the development of hypersonic vehicles. In the present work, new ZrC-SiC-TiC ternary composite coatings were designed and fabricated by vacuum plasma spray. The ablation behaviors of the ternary coatings were evaluated by a plasma flame with temperatures about 2200-2500 degrees C and compared with the ZrC-SiC and ZrC-TiC composite coatings. The characteristics of phases, element distributions and microstructure of the oxidized layers were observed in detail. The results showed that the anti-ablation resistant property of the ternary coatings was much better than those of the ZrC-SiC and ZrC-TiC composite coatings. The oxidation products, like high viscous SiO2 and high thermo stable TiO2, played a mutual promoted role in modifying the oxide layers, which contributing a lot to the improved ablation resistance. The ablation mechanisms of the ZrC-SiC-TiC ternary coatings were analyzed based on microstructure observations and thermodynamic analysis.