GB842826A - Improvements in or relating to chemical plating - Google Patents

Abstract

Catalytic material is coated with a nickle-boron or cobalt-boron alloy containing 1-8% boron by being contacted with an aqueous solution having a pH of at least 3.5 and containing nickel or cobalt ions and an amine-borane. The catalytic material may be nickel, cobalt, iron, steel, aluminium, zinc, palladium, platinum, copper, brass, manganese, chromium, molybdenum, tungsten, titanium, tin, silver or carbon further, non-catalytic material such as glass or plastic may be rendered catalytic by producing a film of catalytic material on its surface, e.g. by dipping into stannous chloride solution and then contacting with palladium chloride to produce a palladium film. The nickel or cobalt ions may be introduced into the solution in the form of water-soluble salts, e.g. sulphate, chloride, acetate and formate; the amineborane may be ethylamine-diethylamine-, methylethylamine-, dimethylamine-, isopropylamine-, tertiary propylamine-, pyridine-, or ammonia-borane (H3NBH3), or may be the reaction product of ammonia and diborane (approximately 2NH3B2H6). The solution may also contain a fluoride accelerator, e.g. sodium, ammonium or nickel fluoride; a conventional buffering system; a lead salt or an organo-sulphur compound e.g. thiourea or a xanthate, to render inert any impurities in the solution; and, when the solution is alkaline, a nickel or cobalt sequestering agent such as ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, ethylenediaminetetraacetic acid, citric acid, tartaric tartaric acid and related polyamines and N-carboxymethyl derivatives thereof. The solution is preferably stirred and/or contains a wetting agent such as sodium lauryl sulphate. The initiation of the coating process may be accelerated by contacting the surface to be coated with a more electro-negative metal while in contact with the coating solution.