| 摘要 |
PROBLEM TO BE SOLVED: To provide an alumina sintered body having a dense and fine sintered structure, high strength and toughness as high as >=5 MPa.m1/2 fracture toughness as measured by to JIS-R1607 and more preferably >=6 MPa.m1/2. SOLUTION: A high purity alumina calcined body having pores with 40 to 63% relative density is impregnated with a solution of a metal salt of Ca, Sr or Ba. The body is then sintered at 1,350 to 1,600 deg.C to thermally decompose the metal salt so that alumina grains are anisotropically grown by the effect when the metal oxide is formed on the intergranular faces and that anisotropic particles having <=3 μm major diameter and >=2 aspect ratio occupies an area of >=20% based on observation of the cross section. The structure of the sintered body is homogenous, dense and fine, and the fracture toughness can be significantly improved while high strength is maintained. |
