Electrochemical Codeposition of Nickel and Tin from Gluconate Solutions

Abstract

Ni-Sn alloys show excellent properties having considerable technological interest. Commercial codeposition of nickel with tin is usually carried out from acidic fluoride-chloride electrolytes, but these are intended to replace by less aggressive baths. In this work codeposition of Ni-Sn alloys from acidic solutions containing sodium gluconate as a cheap and nontoxic complexing agent was carried out. The electrodeposition process was studied using various electrochemical techniques. Cathodic polarization curves have shown that tin (II) ions were reduced under limiting current. Chronoamperometric studies indicated nucleation of the alloys according to the instantaneous mechanism. Equilibrium speciation of the baths was also calculated. Chemical and phase composition as well as morphology of the coatings were investigated. Corrosion resistance of the alloys was also studied.