Oxidation resistance and protective mechanism of ZrB2-SiC coating modified by Y2O3 at 1700 ℃

Abstract

To enhance the resistance of ZrB₂-SiC-based coatings against oxidation on carbon materials surfaces under ultra-high temperatures, Y₂O₃ was added to a ZrB₂-SiC based coatings, and the structural evolution was investigated upon static oxidation at 1700 °C for 100 min. After modification, Y₂O₃ effectively inhibited the volume expansion caused by ZrO₂ phase transformation, thereby reducing the stress accumulation. Furthermore, the oxidation process led to the dispersion of Y₂SiO₅, Y₂Si₂O₇ and ZrO₂ nanocrystals within the glass matrix, resulting in the formation of a Zr-Y-Si-O composite glass layer. In contrast to the unmodified coating, the 1 wt% Y₂O₃ doped ZrB₂-SiC coating demonstrated superior oxidation resistance, achieving reductions in average oxygen permeability and inert factor by 65.58 % and 53.35 %, respectively. However, an excess of Y₂O₃ results in Y³⁺ ions promoting oxide aggregation, which subsequently interacts extensively with SiO₂, compromising the structural integrity of the glass film and enhancing the oxidative degradation of the coating.