Low temperature sintering of α-alumina with the aid of abrasive powder in wet grinding

Abstract

Wet grinding of aluminum hydroxide in a tumbling mill was conducted to investigate the effect of abrasive powder worn from the ball media on the preparation of low temperature sinterable α-alumina powder. The abrasive powder worn from high purity alumina balls reduces the transformation temperature to α-alumina during the calcination process. The transformation temperature decreases, from about 1300°C for the unground sample to about 1000°C for the ground product, with increasing amounts of abrasive powder. Only 0.2 mass% of contaminant causes a reduction in temperature by about 200°C in comparison with the unground one. The α-alumina powder calcined after the grinding is very fine. Therefore, low temperature sintering of such α-alumina calcined powder is easily achieved, forming a dense sintered body. The alumina abrasive powder is considered to play a significant role as a seed effect in the formation of α-alumina.