Microstructures and Mechanical Properties of TiO₂-Doped Alumina Ceramics Owing to Decomposition of Formed Al₂TiO₅

Abstract

Al₂TiO₅ decomposes into Al₂O₃ and TiO₂ at 900 to 1300°C. The effect of Al₂TiO₅ decomposition on the microstructure and mechanical properties of Al₂O₃-TiO₂ ceramics was studied by X-ray powder diffraction, scanning electron microscopy, bending and toughness tests. The alumina powder compacts containing 0 to 16wt% TiO₂ were sintered at 1500°C for 2h, and then annealed at 900-1350°C in air. Thermal stress existed in sintered body due to the difference in thermal expansion coefficient between Al₂O₃ and Al₂TiO₅. The stress enhanced the decomposition rate of Al₂TiO₅, while it decreased with the decomposition of Al₂TiO₅. The bending strength of sintered alumina ceramics was increased by the decomposition of Al₂TiO₅, but the toughness almost unchanged.