Bath for electrodeposition of gold-zinc alloys - contains alkali sulphite, gold-sulphite complex, zinc salt, complex or chelate, complexing or chelating agent and metal

摘要

Alkali sulphite bath for the electrodeposition of bright gold-zinc alloys which are homogenous, grey to white in colour, and of relatively low % Au, contains no cyamide. The bath contains (a) a gold-sulphite complex; (b) free alkali sulphite; (c) Zn as a salt, complex, or soluble chelate; (d) an agent forming a complex or chelate; (e) >=1 alloying metal, acting as a homogeniser and reducing internal stress in the deposit, the metal(s) being present as a salt, complex or chelate. Agent(d) contains >=1 acid contg. N or P, of which the Pk for Zn is 6-15, >=1 hydroxy-organic acid chosen from acyclic acids with min. two OH gps. and ration OH/COOH is min. 1: or aliphatic or aromatic cyclic hydroxy acids. Metal(e) is In or Ga. The bath contains no toxic cyanide, or toxic Cd; and low % Au can be obtd.