Hard metals with improved solderability - obtd. by electrolysis of hard metal in alkaline soln. to form surface free from carbide for use in soldered or brazed joint

摘要

The hard metals contain =1 of the binder metals iron, cobalt, nickel, plus one or more carbides and/or nitrides of the metals Ti, Zr, V, Nb, Cr, Ta, W. solderability is improved by reducing the amt. of carbide in the surface of the hard metal; and this redn. is achieved by the electrolytic treatment, at an anodic potential, of the hard metal in an alkaline soln. (I) prior to soldering. The pref. soln. (I) contains an alkali and/or substances forming complex cpds; and a carbide-free layer 0.1-10 mu m thick is pref. formed on the hard metal surface prior to soldering. Used in soldering or brazing of all types of sintered hard metal tools, e.g. to steel shanks, where the invention attacks the outer layer of the sintered hard metal piece. The process is inexpensive and produces no noxious vapours harmful to humans.