Relationship between density and mechanical properties of spark plasma sintered zirconia ceramics

Abstract

Zirconia ceramics stabilized with 3 mol % Yttria were produced by spark-plasma sintering. Toughness, Vickers hardness, nanoindentation elastic modulus and Berkovich hardness were determined in terms of the final density and sintering temperature. Very fine grain materials from 65 to 800 nm were obtained with relative densities ranging from 88 to 99.5%. Results show lower elastic modulus and hardness in low dense specimens compared to fully dense specimens, also indentation fracture toughness changes with density and grain size. Specimens investigated under hydrothermal degradation at 131ºC for 60 hours show that mechanical properties are not affected by this treatment in low density and low grain size specimens, but affects strongly the elastic modulus and contact hardness of specimens of near full density and large grain size. The results are discussed in terms of density, grain size and t-m transformability.