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 γ-Al2O3 powder. The relations between mechanical properties, microstructure and hotpressing temperature were discussed. Two kinds of alumina ceramics were obtained under different hot-pressing conditions. One, the particle size was about 0.5μm and its flexure strengthwas 500±45MPa at 1450℃/30min, and the other, fracture toughness was 5.7±0.5MPa.m1/2 at1550℃/30min. Also, the effect of MgO additives on alumina ceramics was studied. The resultsshowed that the process was the critical factor to decide the role of MgO additives. Moreover,under the hot-pressing conditions of 1420℃/30min ) the alumina with relative density of 99.3%and fiexure strength of 584±51MPa was obtained.