GB511356A - Improvements in and relating to vacuum-tight seals - Google Patents

Abstract

511,356. Uniting metal to ceramic materials by heat. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 14, 1938, No. 4570. Convention date, Feb. 17, 1937. [Class 36] A tubular lead through a ceramic body, such as the wall of an electric vacuum discharge apparatus, comprises two coaxial tubes sealed together directly or indirectly at one or both ends and having an annular space between them intermediate their ends, the interior of the inner tube being sealed by means of a ceramic member joined to it intermediate its ends and the outer tube being sealed intermediate its ends directly or indirectly to the ceramic body. In Fig. 1, the coaxial tubes 3 are joined at their ends to a main lead 6 inserted between them, the inner tube being sealed by soldering or fusing to the ceramic disc 2 and the outer tube being sealed to the ceramic body 1 which is also joined to the metal wall 7 by another tube 8. The annular spaces may be formed, as in Fig. 1, by expansion and contraction of the central parts of the tubes 3 or, as in Fig. 2, by recessing the main lead 6; alternatively, such spaces may be formed by the provision of flanges on the main lead or on the coaxial tubes at the sealing parts. Further, the tubes may be joined together or to the main lead indirectly, using packing rings or as shown in Fig. 3, the tubes 3 may be joined directly. The Specification as open to inspection under Sect. 91 states also that the annular spaces may be filled with solder or plaster. This subjectmatter does not appear in the Specification as accepted.