Transient Thermal Stress Behavior in ZrO2‐Toughened Al2O3

Abstract

The initial strength of (σi) and thermal shock resistances (ΔTc and σr/σi), as determined by quench tests, of Al2O3‐ZrO2 composites are increased by increasing amounts of tetragonal ZrO2 second phase for contents of up to ∼15 vol%. For composites with ≤9 vol% ZrO2 the increases in σr and ΔTc reflect the increase in γIC with addition of ZrO2 However, for ZrO2contents >9 vol%, the thermal shock resistances (ΔTc and σr/σi) and σi are also affected by machining‐induced microcracking in the surface of the samples. For ZrO2 contents >14 vol%, bulk microcracking can become extensive and result in a degradation of σi and ΔTc.