Fabrication of ZrO2 whisker modified ZrO2 ceramics by oscillatory pressure sintering

Zirconia ceramics were prepared by oscillatory pressure sintering (OPS) with zirconia whisker as the reinforcement. The effects of whisker fraction on the microstructure, densification and mechanical properties of the ceramics were investigated. By applying an oscillatory pressure ranging from 25 to 35 MPa to the powder mixtures, the relative density of the OPS zirconia reached approximately 99.7% at whisker fraction of 15 wt%. Because of the accelerated densification by grain boundary sliding and diffusional creep, the average grain size of the OPS zirconia was 0.9 μm, which was much finer than that of the pressure-less sintered zirconia (1.5 μm). The peak values of flexural strength and fracture toughness of the OPS zirconia corresponded to 1376 MPa and 6.7 MPa m1/2, respectively. Whisker bridging, crack deflections were considered as the primary toughening mechanisms. This study provides an approach to prepare zirconia ceramics with uniform, fine grains and excellent fracture strength and toughness.