Effect of added TiO2 on the mechanical properties of sintered Al2O3 insulator

Abstract

The effect of TiO<sub>2</sub> additive concentration and sintering temperatures on the densification of alumina (Al<sub>2</sub>O<sub>3</sub> ) ceramics were investigated. Densified alumina specimens were prepared by uniaxial pressing at a pressure of 60 MPa followed by isothermal heating at either 1400, 1500, or 1600 o C for 2 h. The relative density, microstructure, crystallinity, and hardness were investigated, and the correlation between properties and structure was discussed in relation to TiO<sub>2</sub> addition and sintering temperature. The densities of the 0.05wt%-TiO<sub>2</sub> specimens sintered at 1500 and 1600 o C had higher values than the pure alumina specimens. Adding more than 5.0wt% TiO<sub>2</sub> lowered the relative density. The maximum achieved density was 99.7% at 0.05wt% TiO<sub>2</sub> addition. Shrinkage and hardness analyses confirmed that the sintering temperature for the Al<sub>2</sub>O<sub>3</sub> insulator could be lowered by adding TiO<sub>2</sub>. The optimal concentration to obtain a dense alumina with high hardness for insulator use was determined to be in the range of 0.05 to 1.0 wt% of TiO<sub>2</sub> . These results provide fundamental composition and process optimization data for the development of high-dielectric alumina insulators.