| 摘要 |
PROBLEM TO BE SOLVED: To provide alumina ceramic having high purity and being superior in density and machinability by forming alumina raw material powder containing a specific addition component at a specified condition and firing it. SOLUTION: This alumina ceramic is formed from the raw material powder constituted of 99.05-99.85wt.% Al2 O3 , 0.05-0.50wt.% of the total quantity of at least one kind oxide of MgO, SiO2 or CaO, and 0.05-0.50wt.% Y2 O3 with a conventionally well-kown casting molding method, released from mold and dried, and then kept at the max. firing temp. in the range of 1,550-1,650 deg.C at least for one hour or more to produce an alumina ceramic sintered compact. This sintered compact has >=3.85g/cm<3> Arkimedes density, 5-20μm average particle diameter, <=1,500kgf/mm<2> Vickers hardness and >=370MPa elastic modulus. |
