Mechanical properties and CMAS corrosion behavior of Sc2O3 and Y2O3 co-stabilized ZrO2 pellets

Abstract

Rare-earth stabilizer design provides an effective approach for enhancing the high-temperature CMAS corrosion resistance of zirconia-based ceramics. In this study, Sc₂O₃–Y₂O₃ co-stabilized ZrO₂ pellets containing 0–6 wt% Sc₂O₃ were prepared by solid-state reaction, cold isostatic pressing, and high-temperature sintering. Their microstructures, phase constitution, apparent crystallite size, mechanical properties, porosity, and CMAS corrosion behavior were systematically investigated. Rietveld profile fitting showed that an m-ZrO₂–Y₂O₃–Sc₂O₃ model reproduced the powder patterns of YSZ and 2ScY more closely than those of 4ScY and 6ScY, indicating limitations of the three-phase model at higher Sc₂O₃ contents. In contrast, the sintered pellets were satisfactorily described by a t-ZrO₂ model, supporting a predominantly tetragonal structure. Increasing the Sc₂O₃ content partially suppressed grain growth and increased hardness, but reduced the critical crack-growth energy release rate. After CMAS exposure, degraded, loose, and dense matrix zones were identified in the cross-sections. The degradation thickness, loose-zone height, and effective CMAS penetration depth progressively decreased with increasing Sc₂O₃ content. Overall, Sc₂O₃–Y₂O₃ co-stabilization improved the CMAS resistance of zirconia pellets relative to YSZ, with 6ScY exhibiting the lowest measured degradation and penetration values.