Estimation of Brightener Concentrations in Nickel Plating Liquids Using the Characteristics of Polarization Curves

Abstract

To estimate brightener concentrations in nickel plating liquids, we applied electrochemical measurements and numerical analyses. The polarization curves of fresh nickel plating liquids at different concentrations were measured using a conventional three-electrode configuration. Several characteristic values were selected on the polarization curves. Relations between the characteristic values and the brightener concentrations were analyzed. The polarization curve shape correlated with the concentrations of saccharin sodium salt dihydrate and 2-butyne-1,4-diol, which are commonly used brighteners for nickel plating liquids. These correlations were changed to functions when the brightener concentrations were markedly lower than the commonly used values. The brightener concentrations estimated according to the functions were compared with the prepared brightener concentrations. The estimated values showed good linearity. We concluded that this method is applicable for estimating brightener concentrations in nickel plating liquids.