Reaction-Sintered Alumina - Spinel Composites: Effect of Raw Material Sources

Abstract

The project involved the formation of alumina-spinel composites from combinations of different raw material sources, at two different compositions, varied over a range of temperatures succeeding a single stage firing route. The starting materials used were viz. A16SG, CL370, CT9FG for alumina sources and fused magnesia and sintered magnesia for magnesia sources. Alumina and magnesia sources were combined at compositions of 80:20 and 90:10 weight ratio, pressed and reaction sintered at temperatures 1200ºC, 1300ºC, 1400ºC, 1500ºC and 1600ºC. Increase in the spinel content formed, was observed in samples fired at higher temperatures. Batches with finer raw material sources offered better densification an increasing trend with temperature was observed for the same. The XRD analysis plots of 80:20 batches showed trace amounts of corundum phase peaks at 1600ºC while the 90:10 batches indicated small but clear peaks of the same at the highest temperature and that can be attributed to the higher residual alumina in the latter batches.