GB698173A - Improvements relating to the joining of metal or non-metal parts by brazing, soldering, or casting-on - Google Patents

Abstract

In joining parts by brazing, soldering, or casting-on to a part containing or consisting of a carbide or boride or consisting of an alloy of tungsten or molybdenum, a superficial layer of a wettable metal or alloy is provided first on the part and then diffusion is effected by heat. This diffusion may occur in either direction and may include some alloying. The layer may comprise nickel, copper, iron, tin, zinc, copper, silver, gold or lead or an alloy thereof and be formed by chemical, electro-chemical or physical operation. The metals may be applied as salts, e.g. sulphates or chlorides or oxides and heating be carried out in hydrogen or other reducing gas or the metals may be applied by electrolysis, by decomposing a substance, such as nickel-carbonyl gas or iron-carbonyl liquid, on the surface of the preheated part or by spraying, dipping or painting with a solution or suspension. The material may be applied in successive layers with or without heating between the applications. The temperature used and the duration of application is regulated to ensure the formation of an adherent wettable surface layer. This heating is preferably carried out in a vacuum or in inert or reducing atmosphere and may occur as the first step in the joining operation. The method may be used in making X-ray anticathodes by electroplating a tungsten carbide piece with nickel, heating to 1150 DEG C for 1 hour and casting-on a body of copper. In joining a cemented carbide part to a steel body, both may be provided with a wettable layer before joining.