PROBLEM TO BE SOLVED: To solve a problem that a sintered body having high flexural strength, high toughness and high translucency in combination is not obtained and a translucent alumina sintered body suitable for a dental material requiring both strength and sensuousness was not obtained in the conventional alumina sintered bodies.SOLUTION: The translucent alumina sintered body having 4.5 MPa-m0.5 fracture toughness, &ge350 MPa-m0.5 flexural strength, and &ge60% all light transmittance (sample thickness: 1 mm) to a visible light having a wavelength of 600 nm is provided. The sintered body wherein sintered crystal grains are slender plate-like and/or columnar shape having an average aspect ratio of &ge1.5 and &le15 &mum average long axis length is preferred.COPYRIGHT: (C)2009,JPO&INPIT【課題】従来のアルミナ焼結体では曲げ強度、靭性及び透光性を全て兼ね備えたものが得られず、強度と審美性の両方を要求される歯科材料に適する透光性アルミナ焼結体が得られていなかった。【解決手段】破壊靭性が4.5MPa・m0.5以上、曲げ強度350MPa以上、なおかつ波長600nmの可視光に対する全光線透過率(試料厚さ1mm)が60%以上である透光性アルミナ焼結体を提供する。焼結結晶粒子が平均アスペクト比1.5以上、平均長軸長さ15μm以下の細長板状及び/又は柱状粒子の焼結体であることが好ましい。【選択図】 図2
