GB1386781A - Electrodeposition of nickel - Google Patents

Abstract

1386781 Electrodeposition of nickel ALBRIGHT & WILSON LTD 1 March 1972 [5 March 1971] 6149/71 Heading C7B A coumarin-free aqueous electrolyte for nickel plating comprises (a) at least 30 gms per litre of a nickel-II salt; (b) 0.1 to 250 milimoles per litre of a mixture of water soluble acetylenic compounds including an α-alkynol and a condensation product of an α-alkynol with an alkylene oxide in a weight ratio of said α-alkynol to said condensation product of from 4:1 to 1 :4 and (c) from 0.1 to 45 gms per litre of a non-conjugated carboxylic acid in which the pKa is between 3.0 and 5.0. The solution may contain chloride, sulphate, sulphamate and/or borate. The α-alkynol may have the formula R 1 CHOHC#CR 2 where R 1 , R 2 are each hydrogen, or an alkyl, alkenyl or alkynyl group of 1 to 4 carbon atoms or such group having an amine or hydroxy substituent. Specific α-alkynols are listed; e.g. 2-butyn-1, 4 diol, 1-butyn-3-ol and propargyl alcohol. The condensation product may be a condensation product of an α-alkynol of the above mentioned general formula with ethylene oxide. Specified suitable carboxylic acids are formic, acetic, propionic, glycolic, tartaric, lactic, succinic and phenoxyacetic acids. Other suitable acids are listed in Specification 871276. The acids may be added as derivatives thereof, e.g. as alkali metal, NH4, Mg or Ni salts or as lactones, esters, acid chlorides or anhydrides. Specified operating conditions are a pH between 2.5 and 5.5, a temperature of 40-70 ‹C a current density of 2-100 amps/sq. ft. and agitation of the cathode or blowing of air through the electrolyte. The electrodeposited Ni may be mechanically polished or may be used as a base for electrodeposition of fully bright Ni using an acetylenic compound and sulpho-oxygen compound as additives. Cr may be electrodeposited on to the fully bright Ni.