Glass composition

Abstract

The subject-matter of the invention is a glass composition, which is suitable for use in electric lamps, comprising SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, SrO, B.sub.2 O.sub.3, and optionally CaO, MgO, TiO.sub.2, P.sub.2 O.sub.5, Sb.sub.2 O.sub.3, Fe.sub.2 O.sub.3, MnO.sub.2, ZnO and/or CeO.sub.2. It is characterized in that its SiO.sub.2 content is 65-73 mass %, Al.sub.2 O.sub.3 content is 0.5 to 2.5 mass %, Na.sub.2 O content is 5 to 9 mass %, K.sub.2 O content is 8 to 12 mass %, Li.sub.2 O content is 0.4 to 1.5 mass %, SrO content is 0.5 to 5 mass %, B.sub.2 O.sub.3 content is 2.1 to 5 mass %. Furthermore in addition to the components listed, it optionally also comprises maximum 2.5 mass % CaO, maximum 3.8 mass % MgO, maximum 1 mass % TiO.sub.2, maximum 0.8 mass % P.sub.2 O.sub.5, maximum 0.5 mass % Sb.sub.2 O.sub.3, maximum 0.25 mass % Fe.sub.2 O.sub.3, maximum 0.25 mass % MnO.sub.2, maximum 5 mass % ZnO, and/or maximum 0.8 mass % CeO.sub.2 with the condition that the total amount of SrO, ZnO and MgO in the composition is at least 1.7 mass %. Stems and bulbs made from the above glass composition and used in electric lamps are also subject matter of the invention.

Dependencies are inferred from the claim text.