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Pb-Sn alloy plating by direct and reverse pulse (DC) electrolysis and their corrosion behavior in carbonate solution

M.Palaniappa,M.Jayalakshmi,B.R.V.Narasimhan,P.M.Prasad,K.Balasubramanian

Pb-Sn alloywas electroplated using direct and reverse pulse DC (Direct Current) electrolysis froma commercialmethane sulfonic acid bath. Copper substrates were used.Material characterization was done by XRD, SEM,AFM, XRF and wet chemical analysis. Electrochemical characterization was done by E-Log I polarization at the scan rate of 2 mVs-1 in 0. 1M Na2CO3 solution. Chemical composition of the alloys determined bywet chemical analysis and X-ray fluorescence was ca. 60 wt.%Pb and 40wt.%Sn. The Ecorr for D-PbSn alloy is -824mV and icorr is 28.5Acm-2 while for, P-PbSn alloy the Ecorr is -776 mV and icorr is 73.5A cm-2. The corrosion occursmore spontaneously inD-PbSn but the rate of corrosion is higher in P-PbSn sample. Formation of protective carbonate filmon the D-PbSn surface prevented further dissolution, thus leading to less corrosion current.