A ceramic discharge vessel, for high-pressure discharge lamp and method for producing a polycrystalline transparent sintered aluminum oxide body

摘要

A method for preparing a polycrystalline transparent alumina sintered article, which comprises admixing an alumina having a purity of 99.9 % or higher with MgO in the range of 0.002 to 0.010 wt % and La2O3 in the range of 0.005 to 0.020 wt % in a manner such that the sum of MgO and La2O3 is 0.030 wt % or less and the relationship: 0.2 ≤ MgO/La2O3 ≤ 0.5 is satisfied, calcinating the resultant mixture at 900 to 1200˚C, subjecting the calcinated product to a slip casting, subjecting the cast product to a chelating treatment, and holding the chelated product at 1650 to 1900˚C in a reducing atmosphere for 1 hr or more, to thereby fire it under a normal pressure. A polycrystalline transparent alumina sintered article prepared by the method is optimized in the types and the amounts of sintering aids for the use in a light-emitting case of a high-voltage discharge lump.