Effect of the powder precursor characteristics in the reaction sintering of aluminum titanate

Aluminum titanate precursor powders, containing 2.5 wt.% MgO additive, were prepared by two powder processing methods, the hydrolysis of alkoxides and coprecipitation of inorganic salts. The hydrolysis-derived precursor powder showed a higher chemical homogeneity than the coprecipitated-derived precursor powder. Dilatometric analysis, accomplished with XRD and microscopy, was a very good method to study both phase transformation and sintering processes. Different phase transformation paths of TiO2 and Al2O3 were observed in the two powders. The formation of aluminum titanate solid solution began at ∼1220°C in both, but in the hydrolysis-derived powder compact the aluminum titanate grains grew faster, leading to incomplete reaction and a non-uniform microstructure of large grains with small residual inclusions.