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.