Densification and mechanical properties of fine-grained Al_2O_3-ZrO_2 composites consolidated by spark plasma sintering

摘要

Alumina matrix composites containing 5 and 10wt% of ZrO_2 were sintered under 100MPa pressure by spark plasma sintering process. Alumina powder with an average particle size of 600 nm and yttria-stabilized zirconia with 16 at% of Y_2O_3 and with a particle size of 40 nm were used as starting materials. The influence of ZrO_2 content and sintering temperature on microstructures and mechanical properties of the composites were investigated. All samples could be fully densified at a temperature lower than 1400 °C. The microstructure analysis indicated that the alumina grains had no significant growth (alumina size controlled in submicron level 0.66-0.79 μm), indicating that the zirconia particles provided a hindering effect on the grain growth of alumina. Vickers hardness and fracture toughness of composites increased with increasing ZrO_2 content, and the samples containing 10 wt% of ZrO_2 had the highest Vickers hardness of 18GPa (5kg load) and fracture toughness of 5.1 MPam~(1/2).