Reaction sintering of aluminium titanate: I-Effect of MgO addition

The effect of 2 wt% MgO addition on the reactive sintering of Al2TiO5 was studied starting from commercially available alumina and rutile powders. The formation of titanate, the successive sintering process and the corresponding microstructure evolution have been investigated using differential dilatometry, X-ray powder diffraction and scanning electron microscopy. For pure Al2TiO5 the reaction occurs initially by a nucleation and rapid growth process and, afterwards, by the slow conversion of unreacted oxide particles by solid-state diffusion. The addition of MgO changes the mechanism of titanate formation, probably by making easy the nucleation of the new phase through the intermediate formation of MgAl2O4, followed by the growth of a Mg-rich solid solution. The main result is a strong reduction of the average grain size and remarkable increase of the density of the final material.