Abstract: A method for bonding Si.sub.3 N.sub.4 or SiC ceramics with metals which comprises the steps of depositing, on the ceramic material, an insert material consisting of a mixture of at least one metal selected from the group consisting of Ni and Cu and at least one member selected from the group consisting of metal oxides, nitrides and carbides by ion plating or spary coating, subjecting the deposited insert material to thermal reaction treatment to permit metallurgical bond between the insert material and the ceramic material, and bonding a metal member to the surface of the insert material by brazing with a brazing material whose melting point is lower than the insert material or by diffusion welding at a temperature lower than a melting point of the insert material.

Abstract: During arc welding, optical radiation emitted from an arc is detected by means of a photoelectric device, and an electric detection signal from the photoelectric device is used for controlling the travel of a suction hood along a weld line so that the weld fumes may be exhausted through the suction hood and to insure that the weld metal zone is always covered by the suction hood.