A promising high-temperature oxygen barrier of ZrB2-HfSi2-TaSi2 coating for 1500 °C based on HfSi2-TaSi2 dual-transition-metal silicide alloying enhancement

To enhance the self-healing capability and high-temperature oxidation resistance of ZrB₂-silicon-based coatings, HfSi₂-TaSi₂ dual-transition metal silicide alloying reinforcement was used in ZrB₂-HfSi₂-TaSi₂ coatings, and the oxygen barrier reinforcement effect on different ratios of HfSi₂-TaSi₂ alloying compositions was investigated. The results demonstrate that the synergistic strengthening effect of HfSi₂-TaSi₂ dual silicide alloying significantly enhances the stability at high temperatures and the oxygen barrier performance of the coatings. Notably, the coating containing 30 vol% TaSi₂ exhibited optimal oxidation resistance, with a mass change rate reduction of 79.32 % and an oxygen permeability decrease of 93.75 %. This observed improvement in performance is attributed to the stabilization of the glassy structure through the action of TaSi₂ via a “network compensation” mechanism, which effectively inhibits the aggregation of oxide particles. However, an excess of TaSi₂ resulted in the depolymerization of the glassy film, diminishing its defect-healing capacity and leading to an increase in oxygen permeability to 0.53 %. This research provides new insights for the development of efficient oxidation-resistant coatings.