Commercial nickel phosphorus electroplating

Abstract

A plating bath for nickel and/or cobalt phosphorus amorphous alloy coating can last almost indefinitely. The anode current density of the bath is controlled so as to maintain the amount of phosphoric acid in the bath constant, and less than a level (e.g. around 0.5 molar) at which it has significant deleterious effects on the bath, i.e. maintaining the free acid concentration in the bath in an acid titer range of about 9-14. The anode current density is maintained at about 200 amperes per square foot or greater, and preferably about 500 amperes per square foot or greater, by employing an anode construction that comprises a plurality of widely spaced strips (e.g. wires) of platinum or rhodium; e.g. platinum wires each having a diameter of about 0.010 inches and, for example, a length of about 3.2 inches, and disposed vertically and generally parallel to, but spaced from, a face of a cathode-workpiece that is to be plated with nickel phosphorus, cobalt phosphorus, or nickel/cobalt phosphorus. The anode alternatively may comprise a wire extending in zig-zag fashion between a pair of spaced bus bars. The methods according to the invention are particularly useful for plating fluid jet orifice plates, electrical contacts, carbon steel or stainless steel cutlery, aluminum articles, cookware substrates (such as aluminum, stainless steel, copper, iron, or cast iron substrates), magnetic or magnetizable material such as computer memory storage discs, and wear surfaces such as thrust bearings, shafts for high speed machinery, or the like.