GB1360201A - Electrodeposition of metals - Google Patents

Abstract

1360201 Electro-deposition of Ni, Co or Ni/Co W CANNING & CO Ltd 17 June 1971 [18 June 1970] 29682/70 Heading C7B Ni, Co or Ni/Co is electro-deposited from an aqueous bath in which has been dissolved soluble salt(s) of the metal(s) and a silicic acid. The silicic acid is soluble in the bath but is precipitated or coagulated in the less acid conditions adjacent the cathode and becomes incorporated in the depositing metal. Suitable silicic acids are specified. The bath may be a sulphate or chloride Ni or Co solution and may include (a) buffers such as formates, acetates, propionates, citrates and maleates, (b) brighteners such as aromatic, aliphatic and carbocyclic sulphonates, sulphonamides, sulphinic acids and sulphimides, e.g. benzene sulphonic acids, benzene sulphinic acid, naphthalene sulphonic acids, allyl sulphonic acid and acetylenic sulphonic acids such as 2-butyne 1, 4-disulphonic acid or the alkali metal salts thereof, benzene sulphonamides, toluene sulphonamides or O. benzole sulphimide and (c) compounds capable of producing semi-bright sulphur free deposits such as formaldehyde, chloral hydrate, bromal hydrate coumarin or 2-butyne 1, 4-diol. Specified conditions are a temperature of 30-70‹C, pH of 3-6 and cathode current density of 1À0-8À0 A/dm<SP>2</SP> and air agitation of the bath. The deposited layer may be electrolytically overplated with Cr or brass or be coated with lacquer. In an example, the precipitated or coagulated material is deposited as particles of size 4 to 6 Angstroms. An aqueous additive for Ni or Co plating baths contains specified proportions of silica hydrogel (which is a particular physical form of silicic acid), saccharin, wetting agent (e.g. sulphated alcohols and ethoxylated alcohols) and xanthan gum (which is a polysaccharide gum of vegetable origin).