Effect of pulse electroplating parameters on the morphology and corrosion resistance of Ag plating coating

Abstract

Pulse electroplating technology has the characteristics of fine grain and good corrosion resistance. In order to ensure the good application of electroplated silver cone cavity in solar radiation detector. The effects of three process parameters, including average current density (0.4–1 A dm−2), pulse on-time (0.2–1.8 ms) and pulse off-time (0.8–4.8 ms), on the deposition rate, appearance and corrosion resistance of silver coating were studied by control variates. The surface morphology and composition of silver coatings were studied by scanning electron microscope (SEM), laser confocal microscopy and energy dispersive x-ray spectrometer (EDX). The corrosion resistance of silver coating in 3.5 wt% NaCl solution (pH=5.5) was studied by polarisation curves and electrochemical impedance spectroscopy. The results show that pulse electroplating takes advantage of the dynamic change of current to influence the size of deposited particles and the degree of densification of the coating by precisely adjusting the pulse plating parameters, and ultimately obtains the coating with excellent morphology. The optimal parameters are: average current density 0.6 A dm−2, pulse on-time 1.2 ms, pulse off-time 1.8 ms. The silver coating prepared under process conditions has excellent corrosion resistance (7059 Ω cm−2). The surface crystal grain is dense, without obvious defects.