STUDY OF A MECHANISM OF HARD GOLD ELECTRODEPOSITION

Electrodeposition of nickel hardened gold was studied from a proprieta ry bath (Renovel N). Linear sweep voltammetry (LSV), chronoamperometry and chronopotentiometry were employed and Tafel curves determined. LS V studies revealed formation of a current peak connected with the inhi bition of the deposition reaction. In the hard gold bath Tafel curves are characterized by two slopes: -0.47 V dec.(-1) between -0.5 and -0. 8 V and -0.19 V dec.(-1) at more negative potentials; in the soft gold bath (without Ni) these slopes are: -0.35 V dec.(-1) and -0.15 V dec. (-1), respectively. Current efficiency of hard gold plating in galvano static conditions was on the average 54-57%, depending more on current density than on the charge passed (thickness of the deposit). No infl uence of oxygen on the process was found. It was also found, that the bath must be activated before reproducible results are obtained.