Effects of MgO and Fe2O3 additives on the microstructure and fracture properties of aluminium titanate flexible ceramics

Abstract

Aluminium titanate (Al2TiO5, AT) flexible ceramics were prepared from Al2O3–TiO2 powder system with MgO and Fe2O3 as additives through solid-state method. The effects of addition level of MgO and Fe2O3 on phase compositions, sintering behavior, microstructure and fracture properties of AT flexible ceramics were systematically investigated. The experimental results show that the introduction of additives can promote the formation of AT and improve the densification by forming solid solution. The addition of MgO could effectively refine AT grains since the formed MgAl2O4 spinel grains could pin at the AT grain boundary and inhibit the growth of AT grains. Conversely, the addition of Fe2O3 could promote the AT grain growth. And the simultaneous addition of MgO and Fe2O3 is beneficial to develop elongated rod-like AT grains. With that, the improved fracture properties can be obtained. Due to pining effect of spinel and better densification, the flexural strength of modified AT flexible ceramics is about 34 times higher than that of virgin. In addition, thanks to the microcracked structure and high grain aspect ratio, events of crack deflection, crack branching, grains pull-out and grains bridging are more likely to occur, leading to an increase in the flexibility by about 133%.