Heat-resistant sealing materials

Abstract From the Canadian patent

Sealing materials for making heat-resistant seals in electrical discharge devices comprise a rare earth oxide, such as lanthanum oxide, and boric oxide preferably together with minor amounts of phosphorus pentoxide, aluminium oxide and magnesium oxide. Preferred compositions comprise 55 to 95 % lanthanum or other oxide, 5 to 45% boric oxide and 0 to 5 % phosphorus pentoxide, 0 to 5 % aluminium oxide and 0 to 5 % magnesium oxide. The compositions can be made by mixing the oxides, or appropriate salts calcining, the mixture at up to 1200°C and crushing it to a powder. They may be used as frits in a slurry or formed into pressed elements such as discs or washers. Sealing can be accomplished by …