GB1337281A - Electroplating of cobalt or cobalt alloy and a composition for depositing the electroplate - Google Patents

Abstract

1337281 Electro-plating with cobalt or cobalt alloy M & T CHEMICALS Inc 7 Dec 1970 [10 Dec 19691 58101/70 Heading C7B Cobalt or cobalt alloy (e. g. cobalt-nickel alloy) is electro-deposited from an aqueous acidic plating solution containing iodide ions provided by iodine, e.g. dissolved in methanol, or an inorganic soluble iodine compound e.g. alkali metal iodide, alkaline earth metal iodide, or nickel or cobalt iodide; and a primary, secondary or auxiliary brightener, defined as follows:- Auxiliary brightener-aliphatic or aromatic-aliphatic olefinically or acetylenically unsaturated sulphonate, sulphonamide or sulphonimide; or zinc, cadmium or selenium in the form of a soluble salt; examples given including sodium (allyl, styrene or propargyl) sulphonate and allyl sulphamide or sulphonamide. Secondary brightener -aromatic sulphonate, sulphonamide, sulphonimide or sulphinate; examples including saccharin, sodium naphthalene sulphonate, sodium benzene sulphinate and benzene sulphonimide. Primary brighteners - N-heterocyclics, acetylenics, active sulphur compounds other than those defined above and dyestuffs; examples including pyridinium and quinaldinium compounds, butyne-diol, thiodipropionitrile and thiourea. An anti-pitting agent may also be present. The cobalt may be present as sulphate and chloride or sulphamate salts with boric acid, formate or citrate as buffer. The substrate to be coated may be Ni, Zn, Cd or steel; zinc plated with copper; or copper, brass or bronze which are previously coated in a bath not containing the iodide ions, or which are introduced into the present bath at very low current density, subsequently increased. The counter-electrode may be of cobalt or cobalt-nickel alloy, either as a bagged bar, or as pieces in a bagged titanium basket.