Sealed beam lamp of borosilicate glass with a sealing glass of zinc silicoborate and a mill addition of cordierite

• US 4,238,704 A
• Filed: 02/12/1979
• Issued: 12/09/1980
• Est. Priority Date: 02/12/1979
• Status: Expired due to Term

• Current Assignee: Corning Glass Works Inc. (Corning Incorporated)
• Original Assignee: Corning Glass Works Inc. (Corning Incorporated)
• Inventors: Malmendier, Joseph W., Bonk, John A.
• Primary Examiner(s): Segal, Robert
• Application Number:
  US06/011,513
• Time in Patent Office: 666 Days
• Field of Search: 313/113
• US Class Current: 313/113
• CPC Class Codes: C03C 8/24 Fusion seal compositions being frit compositions having non-frit additions, i.e. for use as seals between dissimilar materials, e.g. glass and metal; Glass solders
• CPC Class Codes: H01J 5/24 between insulating parts of vessel

Abstract

A composite article is disclosed which embodies a thermally sensitive component enclosed within borosilicate glass bodies having a coefficient of thermal expansion in the range of 30 to 40×10^-7 /° C. The bodies are joined by an intermediate layer of sealing material which is a fused mixture of a sealing glass containing an infra-red absorbing oxide and a mill additive having a low coefficient of thermal expansion. There is further disclosed a method of forming the seal between the glass bodies by application of infra-red radiation to the sealing material.

Claims

1. A sealed beam lamp comprising a filament mounted in a fixed relationship in a reflector member, the reflector member being hermetically sealed to a glass lens member by a layer of sealing material intermediate opposed sealing surfaces on the lens and reflector members, the lens and reflector members being molded from a borosilicate glass having a coefficient of thermal expansion in the range of 30 to 40×

10^-7 /°

C., and the layer of sealing material being a fused mixture having an effective coefficient of thermal expansion not greater than that of the borosilicate glass, the mixture being composed of a sealing glass and a mill addition, the sealing glass having a softening point below 700°

C., a coefficient of thermal expansion greater than that of the borosilicate glass parts, and containing, as part of its composition, an infra-red absorbing oxide selected from copper oxide, iron oxide, and mixtures thereof, and the mill addition, as compared to the sealing glass, having a substantially higher softening point and a lower coefficient of thermal expansion, said sealing glass being a zinc silicoborate composed essentially of 60-70% ZnO, 10-16% SiO₂, and 19-25% B₂ O₃ plus the infra-red absorbing oxide, and said mill addition being a glass having the approximate composition of the mineral cordierite.

2. A composite article in accordance with claim 1 wherein the infra-red absorbing oxide is copper oxide in an amount up to about 20%.