Surface Strengthening of Alumina-Zirconia Composite by Addition of Molybdenum Dioxide

MoO₂ is found to stabilize m -ZrO₂ Because of the addition of MoO₂ into ZrO₂ at the surface region of an Al₂O₃-15 vol% ZrO₂composite, the volume fraction of m -ZrO₂ at the surface increases from 0.3 to 0.5–0.6 without changing the size of the ZrO₂grains. This enhanced transfomation results in an increase in flexural strength of up to 30% because of compressive stresses built in at the surface. The increase in flexural strength is proportional to the difference in volume fraction of m -ZrO₂ between the surface layer and the bulk matrix, in agreement with a previous analysis.