Studies on Sintering of Technical Grade Alumina—Part I: Characterization of Ground Alumina Powders

Characteristics of powders play an important role in the densification and grain growth during the sintering process of oxide ceramics. During the process of grinding for reduction of particle size, factors like impurity, hydration etc have to be controlled by the comminution period, ratio of material to grinding media (balls) as well as the use of proper liquid medium.In this investigation characterization of powders prepared by comminution of technical grade commercial alumina has been made with respect to wet grinding media and ratio of weight of balls to material. Powders thus obtained were examined by chemical analysis (purity), BET (surface area), SEM (shape and size), particle size distribution by X-ray (Sedigraph) methods. The influence of powder properties on the sintering behaviour of compacts was studied at 1400° and 1500°C for two hours.It was observed that an increased amount of balls reduced the particle size to a limiting stage with characteristic size distribution; a corresponding increase in surface area has been noticed. A significant change followed in the sinterability of these powders, corresponding to the nature of surface of particles and their size distribution.