Abstract: A hollow metal member which holds a mirror of an optical resonator in a gas laser tube is electrically and mechanically connected with a hollow cathode by a spring. The spring is positioned either outside or on the inner surface of the hollow metal member and elastically forces one end of the cathode against the inner wall of the hollow metal member.

Abstract: A method for jointing ceramic elements is disclosed. Ceramic elements to be joined are arranged between a pair of torces each having a nozzle for spouting combustion gas.The joint line of ceramic elements is first heated by flames of combustion gas spouted from each nozzle and, then, a high voltage is applied between said pair of torches. Ceramic elements are joined by said heating and applying a high voltage between torches.

Abstract: A composite material composed of a non-oxide type ceramic and iron or an alloy thereof is disclosed, wherein the non-oxide type ceramic is formed with a copper metallized surface and bonded to the iron or alloy thereof with an intermediate layer of Invar steel, Kovar or copper disposed between the copper metallized surface and the iron or alloy thereof.

Abstract: An adhesive agent having, as its active components, copper sulfide and at least one member selected from the group consisting of alumina, silica, and kaoline enables the opposed surfaces of two oxide-type ceramic articles to be joined to each other with high adhesive strength, this fast union being accomplished by interposing the adhesive agent between the opposed surfaces of the ceramic articles and heating the adhesive agent to a temperature of not less than 1000.degree. C.

Abstract: A composition of at least one member selected from the group consisting of sodium fluoride and calcium fluoride and optionally containing kaolin is powerful adhesive for ceramic articles which is used by interposing the adhesive intimately between the opposed surfaces for union of the ceramic articles and heating the adhesive to a temperature equal to or higher than the decomposition temperature of the fluoride used.

Abstract: Adhesion of two silicon nitride parts is accomplished by interposing a layer of calcium fluoride or a mixture of calcium fluoride with kaoline between the two silicon nitride parts and heating the resultant interposed layer.

Abstract: A method for providing strong adhesion of two ceramic articles to each other or one ceramic article to an article of metallic copper, which method comprises applying, in the former adhesion, a powder mixture of CuS-LaCrO.sub.3 -SiO.sub.2 -Cu to the opposed surfaces of the two ceramic articles or, in the latter adhesion, a powder mixture of CuS-LaCrO.sub.3 -SiO.sub.2 to the opposed surfaces of the ceramic article and the article of metallic copper and, thereafter, heating the pair of articles in the air at a temperature of from 1000.degree. to 1200.degree. C.

Abstract: A method for providing strong adhesion of two ceramic articles to each other or one ceramic article to an article of metallic copper, which method comprises applying, in the former adhesion, a powder mixture of CuS--LaCrO.sub.3 --SiO.sub.2 --Cu to the opposed surfaces of the two ceramic articles or, in the latter adhesion, a powder mixture of CuS--LaCrO.sub.3 --SiO.sub.2 to the opposed surfaces of the ceramic article and the article of metallic copper and, thereafter, heating the pair of articles in the air at a temperature of from 1000.degree. to 1200.degree. C.

Abstract: A thin coating of silver is formed fast on the surface of a nitride type ceramic article by coating the surface of the ceramic article with a mixture consisting of copper sulfide and kaolin, subjecting the coated article to a thermal treatment in a nitrogen-containing atmosphere at a temperature in the range of from 900.degree. to 1300.degree. C., then overcoating the thermally treated ceramic article with silver carbonate and heating the overcoated article again in the nitrogen-containing atmosphere at a temperature in the range of from 700.degree. to 900.degree. C.

Abstract: Arc electrodes formed of the sinter of lanthanum chromite or of a compound having a part of the lanthanum component of lanthanum chromite replaced by at least one member selected from the group consisting of calcium, magnesium and strontium.