| 摘要 |
PURPOSE:To obtain a fusing material having a thermal expansion coefficient approximate to that of alumina ceramic as well as sufficient heat resistance and airtightness by adding a specified amount of MgO to mixture consisting of specified concentrational ranges of Al2O3, Y2O3 and SiO2. CONSTITUTION:A composition is obtained by mixing 3-20wt% of MgO into a basic glass consisting of 10-40wt% Al2O3, 15-60wt% Y2O3 and 20-65wt% SiO2. In addition, the composition may contain 5wt% or less of at least one of Sc2O3 and ZrO2. The thermal expansion coefficient of the above composition is much lower than that of alumina ceramic when the content of MgO is less than 3wt%. It exceeds an appropriate range when the content of MgO is higher than 20wt%. This composition has 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. |
