Fabrication of ZrO₂ Solid Solution Ceramics Containing Al₂O₃ Having High Bending Strength (σ_b≥1 GPa) and High Fracture Toughness (K_IC≥20 MPa·m^1/2) Simultaneously by Pulsed Electric-current Pressure Sintering (PECPS)

Abstract

ZrO₂ solid solution (ss) ceramics containing 25mol%Al₂O₃ and 1.125mol%Y₂O₃, i.e., 75mol%ZrO₂(1.5mol%Y₂O₃:1.5Y)-25mol%Al₂O₃ ceramics, have been fabricated by sintering cubic ZrO₂ (ss) nanoparticles prepared via a sol-gel process with a pulsed electric-current pressure sintering (PECPS) at 1100°∼1350°C for 10 min under 60 MPa in Ar. Dense tetragonal-ZrO₂ (ss) ceramics with a small amount of α-Al₂O₃, sintered at 1300° to 1350°C, were composed of 0.2-0.3 μm grains with a high relative density of ≥97.5 %. They showed extreme high bending strength (σ_b≥1 GPa) and high fracture toughness (K_IC≥20 MPa·m^1/2) simultaneously. High-resolution TEM observation revealed that these mechanical properties were originated from homogeneous distribution of α-Al₂O₃ particles in the nanometer-grain matrix of t-ZrO₂; the precipitation of α-Al₂O₃ could be achieved by adopting the solid solution powders containing α-Al₂O₃ and PECPS.