Densification behaviour and mechanical properties of CuO doped zirconia-toughened alumina (ZTA) composites prepared by two-stage sintering

Abstract

Small amount of Copper Oxide (CuO) ranging between 0 vol% to 0.8 vol % were added into Zirconia Toughened Alumina (ZTA) containing 10 vol% Yttria-Tetragonal Zirconia Polycrystals (Y-TZP) and its effect on ZTA’s microstructural and mechanical properties were investigated. The ZTA samples were prepared through two-stage sintering (TSS) with first stage sintering temperature T1 set in the range of 1400°C to 1550°C whereas second stage sintering temperature T2 were set at 1350°C followed by 12 hours of holding time. The sintered samples were evaluated on its grain size, bulk density, Vickers hardness, Young’s modulus and fracture toughness. It is revealed that combination of two-stage sintering and CuO as sintering additives were able to further enhance the mechanical properties of the ZTA composite in addition to suppressing grain growth at the final stage of sintering. Compared to undoped ZTA composites prepared via TSS, samples that contain 0.6 vol% CuO sintered at T1 of 1500°C were able to achieve full densification (99 %), Vickers hardness exceeding 19 GPa, Young’s modulus above 410 GPa. Addition of CuO were found to have no significant effect on the ZTA’s fracture toughness with the exception of CuO content of 0.8 vol% regardless of T1.