Ceramic-to-metal joints

909,062. Ceramic-metal seals. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Dec. 4, 1959 [Dec. 16, 1958], No. 40602/58. Drawings to Specification. Class 36. [Also in Group XXII] A metal part composed of an intimate association of copper or copper alloy and tungsten, is joined to a ceramic body by brazing, the proportions of the constituents of the metal part being selected so that its expansion characteristic will match that of the ceramic. The metal part may be 83-86% w/w. tungsten and 14-17% copper with an 80% alumina ceramic; or 70% tungsten and 30% copper with a 90% magnesium-silicate ceramic. Up to 6% of the intimate association may be replaced by nickel or cobalt, the latter replacing an equivalent amount of copper. The metal association may be effected by, e.g., infiltrating copper into a porous tungsten body or by hot-pressing a mixture of copper and tungsten particles. The ceramic may be metallized, the metal body may have a thin layer of nickel plated on before brazing and the brazing metal may be, e.g. a copper-brazing, copper-silver, copper-titanium or gold-nickel alloy. Specifications 776,970 and 824,552 are referred to.