GLASS COMPOSITION FOR A LAMP, GLASS PART FOR A LAMP, LAMP, AND ILLUMINATION DEVICE

摘要

A glass composition contains the following constituents expressed in terms of oxides: 65 wt % to 75 wt % of SiO2; 1 wt % to 5 wt % of Al2O3; 0.5 wt % to 5 wt % of Li2O; 5 wt % to 12 wt % of Na2O; 3 wt % to 7 wt % of K2O; 12 wt % to 18 wt % of Li2O+Na2O+K2O; 2.1 wt % to 7 wt % of MgO; 2 wt % to 7 wt % of CaO; 0 wt % to 0.9 wt % of SrO; 7.1 wt % to 12 wt % of BaO; and substantially no PbO. The glass composition for a lamp is substantially lead-free, has an electrical insulation suitable for an illumination purpose, and further reduces the risk of devitrification.