GB1441972A - Nickel electroplating baths and their use in forming corrosion protective metallic coatings containing electrodeposited nickel and microporous chrome - Google Patents

Abstract

1441972 Nickel electro-plating bath OXY METAL FINISHING CORP 23 Oct 1973 [30 Oct 1972] 49344/73 Heading C7B An acidic Ni plating bath, e.g. of the Watts type, contains 0À1-10 g/l of a bath soluble amine (optionally N-substituted) and 0À001-0À5 g/l of a tri- or tetravalent metal-containing cation which precipitates at a lower pH than the Ni in the bath. A Cr electro-plate layer on Ni plated from this bath is micro-porous in dependence on the amount of polyvalent cation present. The bath pH may be 1-5 at 75-170‹F, using a cathode c.d. of 5-200 ASF for a deposit thickness of 0À15-2 milo. The amine maybe a polyamine-polycarboxylic acid, may contain -SO 3 H or -P(O)(OH) 2 groups and includes polyalkyleneimines. Those specified include Na diethylene triamine penta-acetate, sulphanilic acid, N-methyl taurine and N(CH 2 ÀPÀOÀ(OH) 2 ) 3 , many others being listed. The polyvalent cation may contain Al, Cr, Tl, Th, V, U or La and includes complex ions such as uranyl and vanadyl. Additionally a Group I or II metal may be added in conjunction with 0À001-10 g/l finely divided SiO 2 . Other specified bath additives include Co or Fe (which alloy with the Ni), buffers e.g. H 3 BO 3 or HCOOH and brighteners e.g. bis benzene sulphonamide, Na allyl sulphonate, saccharin, o-benzoyl sulphimide or The initial substrate may be Cu, Zn, Steel, Fe or Ni plate, any of which may be a coating on e.g. PVC, PVdC, polypropylene, polyethylene or ABS resin.