Process for direct gold plating of stainless steel

Abstract

Stainless steel can be directly plated with gold by a process wherein stainless steel is dipped in an activating solution; the activated stainless steel is subjected to cathodic electrolysis in a cathode electrolytic activation solution and then the treated stainless steel is directly plated with gold. A preferable activating solution contains (i) 3-20 wt. % of HCl, (ii) 2-30 wt. % of H.sub.2 SO.sub.4, (iii) 0.1-5 wt. % of a nonionic or cationic surfactant and (iv) 0.1-20 wt. % of 2-pyrrolidone or N-alkyl-2-pyrrolidone. A preferable cathode electrolytic activation solution contains (i) 5-20 wt. % of H.sub.3 PO.sub.4, (ii) 2-10% HNO.sub.3, (iii) 0.1-5 wt. % of a nonionic or cationic surfactant and (iv) 0.1-20 wt. % of 2-pyrrolidone or N-alkyl-2-pyrrolidone.

Dependencies are inferred from the claim text.