Preparation and research of fine-grained alumina with high mechanical properties

Fine-grained pure alumina ceramics were fabricated by hot-pressing process from a commercial gamma-Al2O3 powder. The relations between mechanical properties, microstructure and hot-pressing temperature were discussed. Two kinds of alumina ceramics were obtained under different hot-pressing conditions. One, the particle size was about 0.5 mu m and its flexure strength was 500+/-45MPa at 1450 degrees C/30min, and the other, fracture toughness was 5.7+/-0.5MPa.m(1/2) at 1550 degrees C/30min. Also, the effect of MgO additives on alumina ceramics was studied. The results showed that the process was the critical factor to decide the role of MgO additives. Moreover, under the hot-pressing conditions of 1420 degrees C/30min, the alumina with relative density of 99.3% and flexure strength of 584+/-51MPa was obtained.