Alumina sintered compact and method of producing the same, and article for heat treatment using alumina sintered compact
AssigneeMurata Manufacturing Co., Ltd.
InventorsKoichiro Hirako, Kenji Ueno, Tomonobu Suzuki
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Abstract
An alumina sintered compact includes at least two layers including an internal layer and a surface layer formed on the surface of the internal layer, which internal layer is composed of alumina crystal grains formed by sintering of a fine alumina powder, and which surface layer is composed of alumina crystal grains formed by grain growth of a fine alumina powder and having a mean grain size larger than that of the alumina crystal grains of the internal layer. This alumina sintered compact can prevent the accumulation of PbO in a surface area while controlling the absorption of PbO.
Claims20
An alumina sintered compact comprising an internal layer and a surface layer on the surface of said internal layer, said internal layer comprising alumina crystal grains of sintered fine alumina powder and said surface layer comprising alumina crystal grains of grain grown fine alumina powder, wherein the mean grain size of said alumina crystal grains of the surface layer is larger than that of said alumina crystal grains of the internal layer.
An alumina sintered compact according to claim 4, wherein the alumina crystal grains of said surface layer are oriented in a layer substantially parallel to the surface of said surface layer.
A method of producing an alumina sintered compact, comprising the steps of:
- providing a mixture of fine alumina powder A and fine alumina powder B, said fine alumina powder A comprising plate Al2O3 grains having a mean grain size between about 0.4 μm and 3.0 μm and having a purity of at least about 99%, and said fine alumina powder B having a mean grain size between about 0.3 μm and 2.0 μm and having a purity of at least about 99%;
- casting and molding the mixture in a mold to form a green compact;
- and
- firing the dried green compact at a temperature between about 1550° C. and 1750° C.
Dependencies are inferred from the claim text.