Solid-particle erosion of directionally solidified Al2O3–ZrO2 (Y2O3) eutectics

Resistance to solid-particle erosion was studied by measuring individual damage sites in directionally solidified Al2O3–ZrO2 (Y2O3) eutectics that contained three concentrations of Y2O3 (0.5, 3, and 9% in the ZrO2 phase). For comparison, polycrystalline Al2O3, sapphire, and polycrystalline and single-crystal tetragonally stabilized ZrO2 were also studied. All specimens were impacted at normal incidence by angular 63 and 143 μm SiC particles traveling at 100 m/s. The eutectics containing 3% and 9 mol.% Y2O3 generally exhibited the smallest damage zones and the ZrO2 specimens exhibited by far the largest damage zones. Examination of damage features and comparison with basic mechanical properties and models for erosion of brittle materials led to conclusions that the eutectics were resistant to erosion because of the presence of large compressive residual stresses in their Al2O3 phases and that the ZrO2 materials were susceptible to erosive damage because transformation toughening was ineffective in reducing propagation of lateral cracks that emanated from the damage sites.