Microstructure and mechanical properties of near-eutectic ZrO2–60 wt.% Al2O3 produced by quenched plasma spraying

Nanostructured free-standing materials with the near-eutectic composition ZrO2–60 wt.% Al2O3were prepared by atmospheric plasma spraying (APS) of micron-scale powders plus subsequent quenching using liquid nitrogen-cooled substrates. The microstructure was characterized by X-ray diffraction (XRD), SEM, and TEM, and the influence of thermal treatment at 1400 °° C on the mechanical properties like bending strength, Young’s modulus, microhardness as well as the friction and wear behavior of the materials was investigated. Quenching of the immiscible phases led to the formation of a mixture of metastable and stable phases, since complete separation was limited by the high cooling rate. After thermal treatment, the formation of zirconia precipitates in a corundum matrix was observed.