GB784802A - Improvements in soldering composition for aluminium - Google Patents

Abstract

A soldering composition for aluminium having both a melting point and an ability to remove surface oxide on Al below 250 DEG C. consists of the product of fusing to homogenety a mixture of Alcl3, an alkali metal chloride (NaCl, KCl, or LiCl), and a chloride of a heavy metal electronegative with respect to Al, the molar proportion of AlCl3 in the AlCl3-alkali metal chloride component of the mixture ranging between 52 per cent and 82 per cent and the heavy metal chloride being less than 50 per cent by weight of the mixture and preferably between 1 per cent and 25 per cent thereof. Suitable heavy metal chlorides are zinc, stannous, manganous, chromic, gallium trichloride, ferrous carmium, indium, tellurium monochloride, cobalt, nickelous, lead, copper, mercurous, silver, rhodium, gold, palladium dichloride. The composition is applied preferably in powdered form and requires no metal or alloy solder since it removes the Al surface oxide and simultaneously coats the clean Al surface with the electronegative metal of the heavy metal chloride component. Al base alloys containing 90 per cent or more Al may be soldered; whilst such alloys or Al may also be soldered to copper, copper base alloys particularly brasses and Be copper, silicon bronzes and manganese bronzes. In this latter case the metal of the heavy metal chloride component should be electronegative with respect also to the copper, bronze, &c.