| 摘要 |
PCT No. PCT/GB78/00026 Sec. 371 Date Jun. 7, 1979 Sec. 102(e) Date Jun. 7, 1979 PCT Filed Oct. 18, 1978 PCT Pub. No. WO79/00220 PCT Pub. Date May 3, 1979. 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 DEG 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 heating the surfaces to be joined, together with the interposed sealing composition, to a temperature between 1100 DEG and 1650 DEG C.
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