General Electric Company

Zsuzsanna Klara Varga

Zoltan Kamill Suha

Zoltan Laszlo Bako

The invention relates to a glass composition for electric lamps which glass composition comprises SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, B.sub.2 O.sub.3, BaO and SrO and optionally CaO, MgO, ZnO, P.sub.2 O.sub.5, Sb.sub.2 O.sub.3, TiO.sub.2, MnO.sub.2, Fe.sub.2 O.sub.3 and/or CeO.sub.2. The composition according to the invention has a B.sub.2 O.sub.3 content of 1 to 2.8 mass %, a SrO content of 2.1 to 4.5 mass %, a BaO content of 3 to 6 mass % and of the components being present optionally, the amount of CaO is maximum 1 mass %, that of MgO is maximum 2.4 mass % and that of ZnO is maximum 3 mass %, on the condition that the total amount of SrO and B.sub.2 O.sub.3 is at least 3.6 mass %, the total amount of CaO and MgO is maximum 2.4 mass % and the total amount of MgO and ZnO is maximum 4.5 mass %.

Glass composition

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.

The invention relates to a glass composition for electric lamps comprising SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, B.sub.2 O.sub.3, BaO, CaO and MgO, in addition optionally SrO, Sb.sub.2 O.sub.3, MnO.sub.2, Fe.sub.2 O.sub.3, and/or CeO.sub.2. The glass composition according to the invention is characterized in that its B.sub.2 O.sub.3 content is 1 to 5 mass %, K.sub.2 O content is 7.2 to 11 mass %, BaO content is 5.5 to 9 mass % and MgO content is 2.1 to 4 mass %, furthermore in addition to the components listed, it optionally also comprises maximum 3.5 mass % ZnO, maximum 1.2 mass % TiO.sub.2 and maximum 0.8 mass % P.sub.2 O.sub.5 with the condition that the total amount of CaO, MgO and ZnO in the composition is at least 5.8 mass %. Stems and bulbs made of the above glass composition and used in electric lamps are also subject matters of the invention.

The invention is a glass for electric lamps comprising SiO.sub.2, A1.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, BaO, MgO, CaO, ZnO, B.sub.2 O.sub.3, TiO.sub.2, SbO.sub.3, MnO.sub.2 and one or more of the following Fe.sub.2 O.sub.3, As.sub.2 O.sub.3 and CeO.sub.2, where

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Dunakeszi, Hungary

Zsuzsanna Klara Varga