GB1006333A - Electrodeposition of nickel - Google Patents

Abstract

An electrolyte for nickel plating comprising an aqueous acidic solution of a nickel salt, e.g. nickelous sulphate, chloride, sulphamate and/or fluoborate, also contains from 0.05 m.mole/1. to saturation of a water-soluble sulphur-free acetylenic compound and at least 0.01 g./1., preferably no more than 5 g./1., of formaldehyde, chloral and/or bromal; or the electrolyte contains from 0.05 m.mole/1. to saturation of an acetal reaction product of the above aldehyde e.g. anhydrous chloral with from 1/Z to 2 times an equimolar quantity of a hydroxy acetylenic compound e.g. propargyl alcohol, Z representing the number of OH groups therein. The electrolyte is preferably free of, but may contain, any organic sulpho-oxygen compound as brightener, e.g. unsaturated aliphatic, aromatic or heterocyclic sulphonic acids, aromatic sulphinic acids, or the alkali metal, ammonium, Mg or Ni salts thereof, or aromatic sulphonamides or sulphonimides. The acetylenic compound may be a -substituted or a ,a 1-disubstituted, many examples being given, wherein each a may be a hydroxy, alkoxy, carboxy-substituted alkoxy, formoxy, alkanoxy, halogen or polyoxy group, e.g. 2-butyn-1,4-diol or 1,4-di-(b -hydroxy-ethoxy)-2-butyne. The electrolyte may also contain at least 0.5 g./1., preferably no more than 100 g./1., of a non-conjugated carboxylic acid having a pKa value of between 3 and 5, many examples of which are given; similar salts of these acids may be used, as with the organic sulpho-oxygen compound, as well as their lactones, esters and anhydrides. A Watts type nickel plating bath may be used comprising 270-450 g./1. NiSO4.7H2O, 37.5-60 g./1. NiCl2.6H2O and 30-49 g./1. H3BO3. The nickel plate may be used as a base electrodeposit for a further electrodeposit of nickel or other metal.