The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 23, 1982
Filed:
Sep. 04, 1979
Peter Hing, London, GB;
Thorn Electrical Industries Limited, London, GB;
Abstract
The invention provides a particulate sealing material for use in preparing hermetic seals between ceramic and cermet members, which material comprises at least 70 wt. % refractory oxide and minor quantities of non-vitreous additive comprising SiO.sub.2, MgO and B.sub.2 O.sub.3. This particulate sealing material is conveniently pressed into the form of a coherent element shaped to suit the particular sealing operation concerned, e.g. the sealing of an open end of a ceramic arc tube to a cermet closure therefor. The invention also provides a method of sealing a ceramic component to a cermet member by interposing said sealing material between the opposed faces of the component and member and applying heat and pressure to sinter the sealing material and achieve a seal between the component and member. It has been observed that the sintered sealing composition in the completed seal can have a microstructure characterized by flattened refractory oxide-rich islands aligned generally parallel to said faces and substantially surrounded and interconnected by non-vitreous material rich in oxides of silicon, magnesium, and boron and said non-vitreous material forming layers thinner than said islands and also aligned generally parallel to said faces. The invention is of especial advantage in the closure of the second end of a ceramic arc tube containing volatile fill constituents, since the seal can be effected without melting of the sealing material and hence with improved retention of the tube fill constituents.