GB789887A - Improvements in bright nickel electroplating for the reception of chromium electroplating - Google Patents

Abstract

789,887. Electrodepositing successively semibright nickel, bright nickel and chromium. HARSHAW CHEMICAL CO. Jan. 17, 1955 [Feb. 4, 1954], No. 1344/55. Class 41. A surface of extreme brightness is produced on a base metal, e.g. steel, copper, or brass, of smoothness not worse than 50 R.M.S. microinches by electrodepositing semi-bright nickel from an aqueous acid buffered nickel sulphate chloride bath containing coumarin or a derivative thereof as in Specification 622,761 to a thickness of 0.5 to 1.5 mil. electrodepositing directly thereon bright nickel of a thickness of 0.1 to 0.5 mil. from a similar bath which contains additionally an aromatic sulphonic acid or sulphonate, an aromatic sulphonamide or sulphonimide or salt thereof, or an aromatic sulphonyl chloride, and after rinsing electrodepositing a layer of chromium directly on the bright nickel surface. The semi-bright nickel bath may contain additionally a wetting agent such as sodium lauryl sulphate, while the bright nickel bath may also contain cobalt, cadmium or zin c as the chlorides or sulphates; selenious or selenic acids; triaminotriphenyl methane or amine; N: N<SP>1</SP> - (oxydiethylene) - bis isoquinolinium chloride or -bis pyridinium chlorate ; cyanoacetic acid; ethylene cyanohydrin; or nitriles of acetic, propionic, succinic, or benzoic acids. Specifications 525,847, 684,434 and 741,096 also are referred to.