One-step multi-compositional oxidation of YSi alloy: Experiments and ab initio computation

Abstract

YSi alloy is a promising candidate as oxidation resistant coatings for both the bond coat of environmental barrier coatings (EBCs) and anti-ablation coatings at a high temperature of ∼1300 °C. In this study, a one-step multi-compositional oxidation by rapid heating oxidation mode is proposed to reduce the oxidation rate by 3.6 times compared to conventional slow heating oxidation mode. Results show that preferentially formed Y2O3 oxide initiates a multi-step oxidation, produces a cracking and porous oxides, and thereby resulting in a fast oxidation with pesting. The one-step multi-compositional oxidation with a compact and dense Y2Si2O7 scale contributes to the much better oxidation resistance for rapid heating oxidation mode of YSi alloy. The stable formation of Y2Si2O7 scale is comprehensively understood by the energy barrier, charge density and electronic level based on density functional theory. This study demonstrates a promising application of YSi alloy by rapid heating oxidation mode.