The effects of compaction methods on the sintering density, microstructures, and mechanical properties were investigated in α-alumina ceramics. α-Alumina powders were granulated with a 10% aqueous solution of polyvinyl alcohol (PVA). Uniaxially pressed (UAP) and cold isostatic-pressed (CIP) samples were prepared by pressing uniaxially at a pressure of 1 ton for 1 min, and isostatically at 200 MPa for 15 min, respectively. Subsequently, both types of samples were sintered at 1,200℃, 1,300℃, 1,400℃, 1,450℃, 1,500℃, 1,550℃, and 1,600℃ at a rate of 5℃/min for 2 h. The CIP samples were better than the UAP samples for all properties measured, such as the sintering density, Vicker’s hardness, and toughness. The CIP sample sintered at 1,400℃ showed the maximum Vicker’s hardness and toughness; this may be attributed to the competing effects of a decrease in porosity and the growth of grains with increasing sintering temperature.
