| 摘要 |
PURPOSE:To unnecessitate a troublesome firing stage and to improve homogeneity and transparentness by adding an alkali metal fluoride other than LiF to a powdery Al2O3-MgO mixture optionally after calcination and sintering them. CONSTITUTION:Al2O3 powder having <=3 mum average particle size and >=99% purity is mixed with MgO powder having <=3 mum average particle size in about 1:1 molar ratio to obtain a powdery mixture. This mixture is converted into spinel powder by calcination as required and an alkali metal fluoride (e.g. NaF) other than LiF is added to the mixture by 0.1-3 wt.%. They are molded and this molded body is sintered at 1,400-1,800 deg.C for >=3 hr in vacuum or in an inert gas to obtain the title sintered body. |
