Sinterability of low-cost 3Y-ZrO2 powder and mechanical properties of the sintered body

Abstract

This study investigated the effects of grain size and phase constitution on the mechanical properties of 3Y-ZrO2 by varying the sintering conditions. The raw powder prepared by a low-cost wet milling using the coarse solid oxide powders was sintered by both pressureless sintering and hot-pressing, respectively. As increasing holding time at 1450°C for pressureless sintering, it promoted the microstructural coarsening of matrix grains and the phase transformation to tetragonal phase, whereas the bimodal microstructure embedded with abnormal cubic-ZrO2 grains was observed regardless of sintering time. On the other hand, the specimens hot-pressed at 1300°C for 2 h reached ~ 97% of relative density with homogeneous fine microstructure and mixed phase constitution. It was found that the proportion of untransformed monoclinic zirconia had the most adverse effect on the biaxial strength compared to the impacts of grain size and density. The pressureless sintering of the low-cost powder for prolonged sintering time to 8 h led to a decent combination of mechanical properties (HV = 13.2 GPa, KIC = 8.16 MPa·m1/2, σ = 981 MPa).