Thermal stabilization of aluminium titanate and properties of aluminium titanate solid solutions

Abstract

Aluminium titanate has a near zero thermal expansion coefficient (α=0.8×10⁻⁶ °C⁻¹) in the range 20 to 1000 °C, nevertheless it decomposes below 1200 °C.

The thermal stabilization of Al₂TiO₅ without altering its thermal expansion has been considered by partial substitution in the structure compound of Al³⁺ ions by Fe³⁺ ions.

The solid solutions prepared by solid state reaction are in agreement with the general formula Al(1−x)₂Fe_2x TiO₅(0<x<0.2)

The iron ions present in the crystal structure of Al₂TiO₅ act on its lattice parameters and bring about a catalytic effect in the formation of materials.

Solid solutions show a strong thermal stability and a thermal expansion coefficient specially for the solid solution (x=0.1) which is not far from the Al₂TiO₅ value even after annealing for 300 h at 1000 °C.

The mechanical properties of such materials corresponding to that solid solution present strength values lower than Al₂TiO₅ ones. After annealing, however, these are improved later due to a microcrystallization.