High temperature stable alumina and method of manufacturing the same

摘要

To provide a high-temperature stable transition-type alumina that does not undergo transformation into alpha -alumina even at high-temperature exceeding 1300 DEG C., and a method for producing the transition-type alumina. A metal aluminum block is placed on a block of alpha -alumina composed of Al2O3. Portions of the alpha -alumina block and the metal aluminum block close to their boundary was strongly heated by contacting the flame of burning gas with the portions. Alumina and a relatively small amount of magnesium are thereby vaporized, and allowed to react with oxygen in the atmosphere, thereby obtaining a transition-type alumina that contains a small amount of magnesium in the crystal structure. The transition-type alumina obtained by this method is substantially of single crystal type, and does not undergo transformation into alpha -alumina even at high temperatures exceeding 1300 DEG C. and, further, exceeding 1400, but retains a complete transition-type crystal configuration such as delta -alumina and theta -alumina and the like.