REACTION SINTERING OF ALUMINUM TITANATE .2. EFFECT OF DIFFERENT ALUMINA POWDERS

Reaction sintering of aluminium titanate was studied starting from dif ferent commercial alumina powders and rutile. The formation of titanat e, the successive sintering process and the corresponding microstructu re evolution have been investigated using differential dilatometry, X- ray powder diffraction and scanning electron microscopy. Reaction sint ering of pure Al2TiO5 results in a coarse-grained material with low de nsity; the dependence of the average grain size of the resulting mater ial from the level of impurities of the starting alumina is qualitativ ely discussed; the purest aluminas result in the largest grains. Addit ion of 2 wt% of MgO changes the mechanism of titanate formation, resul ting in a strong reduction of the average grain size and remarkable in fluence on densification of the final material. Since final microstruc ture is mainly determined by the amount of MgO added, the influence of the nature of alumina powder is less pronounced in comparison with pu re Al2TiO5.