Influence of refractory oxide additives on the stability of aluminum titanate

Batch additives incorporated in the form of various oxides as a means of improving the physicochemical properties of aluminum titanate can be divided into two groups. The first consists of additives which prevent the decomposition of the titanate at temperatures below 1200°C, and stabilize its high-temperature modification. In terms of the degree of activity these oxides are arranged in the series: MgO, TiO2, SiO2, Cr2O3, La2O3. It is possible to assume that their influence is due mainly to the formation of limited solid solutions, and also the development during sintering of impurity grain boundary phases. The second group of oxides (SnO2, NiO, excess Al2O3, etc.) contributes to the sintering of aluminum titanate by forming secondary crystalline phase on the grain boundaries of the ceramic. In this connection in obtaining sintered ceramic materials based on aluminum titanate it is preferable to consider additives of the first group or their combinations with additives of the second group.