Sintering of Al₂O₃-Cr₂O₃ powder prepared by sol-gel process

The sol-gel method was applied to create Al₂O ₃-Cr₂O₃ ceramics using aluminum ethylacetoacetate diisopropylate and chromium (III) chloride hexahydrate as starting materials. In the calcination at 600-1200°C it was found that the grains of Cr₂O₃-rich solid solution grew when they were exposed to the surrounding Al₂O₃-rich amorphous particles. The composition of the powders obtained by the sol-gel process changed with calcining temperature. Cr₂O₃-rich solid solutions firstly crystallize at low temperature and the composition of the crystallites changes as the crystals grow and react with the surrounding Al₂O ₃-rich phases. The final sintered bodies fired under an Ar atmosphere showed higher relative densities as compared with those fired in air. A dense sintered body was not obtained when abnormal grains grew when calcining occurred.