In the present paper, the influence of α-AI_2Ol_3 seeds and sinteringmethods on elongated grain growth and fracture toughness is investigated. The preparation of aluminaceramics started with commercial aluminum hydroxide. Abrasives were introduced to the startingmaterials by wet-grinding of high-purity alumina milling balls. Abrasives, playing the role ofseeds, lowered the transformation temperature of aluminum hydroxide to alumina. Microstructures withelongated grains were developed by hot-pressing for the above calcined powders containingα-AI_2O_3 seeds, and alumina grain shapes changed with the amount of seeds introduced. However,only equiaxed grains were observed for the samples pressureless sintered. Fracture toughness of thealumina ceramics was dramatically improved by elongated grains. For the sample hot-pressed at 1600℃for 2 h under 40 MPa pressure, fracture toughness reached 7.1 MPa·m^(1/2), which is much higherthan that of normal alumina ceramics without elongated grains. In addition, high flexural strengthof 630 MPa for the hot-pressed samples was also obtained.
