Electroless gold plating of 316 L stainless steel beads

This paper describes an electroless gold plating process for particulate 31 6L stainless steel. The process is based on a mildly acidic gold sodium thi osulfate/ascorbic acid plating solution and is performed under an inert env ironment at room temperature. The process affords a gold deposition efficie ncy of similar to 50% as inferred from a modified tin chloride based spectr ophotometric assay for gold ion concentration. Successful gold deposition d epended on the removal of the thin, passivating surface oxide layer on the stainless steel; this was accomplished by an initial cleaning step with 2 M HCl. In situ cyclic voltammetry experiments on a stainless steel electrode and atomic force microscopy scans on small coupons were used to further ch aracterize the oxide removal and gold deposition reactions. (C) 1999 The El ectrochemical Society. S0013-4651(98)04-007-5. All rights reserved.