Multi-healing behavior of (NbC-TaC)/ZrC/SiC triple-layer coated C/C composites enduring oxyacetylene flame

Herein, the ablation resistance of plasma-sprayed TaC-modified NbC (NbC-TaC) coatings on ZrC/SiC doublelayer-coated C/C composites was firstly tested using an oxyacetylene flame. Next, the phase composition of ZrO2-Ta2O5 (TaO2.5) systems heat-treated at 2100 degrees C in an argon atmosphere was determined. The results demonstrated the formation of a free-standing Ta-O film that extended the effective ablation time of the TaC coating to >90 s. Among the NbC-TaC coatings, the 37.5 mol% TaC-addition produced a continuous film, achieving the best ablation property. Multi-healing behavior, comprised of interfacial, in situ, and surficial healing, further improved ablation performance. At 2100 degrees C, the solubility of TaO2.5 in ZrO2 was 15 mol%, and the stable phases were tetragonal ZrO2 and Ta with face- and body-centered cubic structures. Furthermore, the interfacial bonding conditions of the heat-treated Zr-O-Ta system and the thermal stability mechanism of ZrO2 to Ta2O5 were discussed.

Automated summary

The ablation resistance of plasma-sprayed NbC-TaC coatings on ZrC/SiC doublelayer-coated C/C composites was tested using an oxyacetylene flame. The phase composition of ZrO2-Ta2O5 systems heat-treated at 2100 degrees C was determined. The formation of a Ta-O film extended the effective ablation time of the TaC coating, and the addition of 37.5 mol% TaC produced the best ablation property.