REACTION SINTERING OF ALUMINUM TITANATE .1. 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 po wders. The formation of titanate, the successive sintering process and the corresponding microstructure evolution have been investigated usi ng differential dilatometry, X-ray powder diffraction and scanning ele ctron microscopy. For pure Al2TiO5 the reaction occurs initially by a nucleation and rapid growth process and, afterwards, by the slow conve rsion of unreacted oxide particles by solid-state diffusion. The addit ion of MgO changes the mechanism of titanate formation, probably by ma king easy the nucleation of the new phase through the intermediate for mation 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 r emarkahle increase of the density of the final material.