| 摘要 |
PURPOSE:To obtain a fusing material having a thermal expansion coefficient approximate to that of alumina ceramic as well as heat resistance and airtightness by selecting the composition of a glass principally consisting of MgO, Al2O3 and SiO2 to be within a specified range. CONSTITUTION:A glass-like substance containing 27-43wt% MgO, 5-50wt% Al2O3 and 25-55wt% SiO2 as main components is used. In addition, the glass- like substance may contain 10wt% or less of at least one of Y2O3, Sc2O3 and ZrO2. When the amount of Mg is not within the above range, a thermal expansion coefficient approximate to that of alumina ceramic can not be obtained. This composition has a thermal expansion coefficient appropriate for fusing, has no problems in its heat resistance and airtightness and does not react with a metal halide used as an additive for members charged in a lamp. Therefore, it is suitable as a fusing material 5 for a long-life metal halide lamp. |
