Effect of TiO2 content on the microstructure and mechanical and wear properties of yttria-stabilized zirconia ceramics prepared by pressureless sintering

Abstract

A yttria-stabilized zirconia ceramic is prepared by pressureless sintering at 1350 °C, and the effects of TiO2 additive (0-10.0 wt%) on the microstructure, phase composition, and mechanical properties of the ceramic are investigated. The ceramic with no added TiO2 consists mainly of a monoclinic phase with a few tetragonal phases. With increasing TiO2 content, more t-ZrO2 phases are stabilized to room temperature, and a new phase, ZrTiO4, forms when the content of the TiO2 excess reaches 5 wt%. TiO2 facilitates the elimination of pores in the YSZ ceramics and increases the densification of the YSZ ceramics. The relative density increases from 91.5% (TiO2 0 wt%) to 96.2% (TiO2 10 wt%). Performance test results show a maximum bending strength of 312.56 MPa when the TiO2 content of reaches 10 wt%. The micro-hardness and wear resistance of the YSZ ceramics first increases then decreases as the TiO2 content increases, and the maximum micro-hardness and best wear resistance occur when the TiO2 is added at 5 wt%; the maximum micro-hardness and the minimum volume wear rate is 1792.5 HV and 2.06 × 10-4 mm3 N-1 × m, respectively. The wear mechanism of the ceramic is mainly plastic deformation and microcracking, and the fracture mechanism is mainly intergranular fracture. These results show that TiO2 is an effective sintering additive that promotes more t-ZrO2 phases stabilized at room temperature, with acceptable mechanical and wear resistance properties.