Galvanostatic Pulse Plating of Cu-Al Alloy in a Room-Temperature Chloroaluminate Molten Salt Rotating Ring-Disk Electrode Studies

Abstract

The galvanostatic plating of Cu-Al alloy was examined at a platinum electrode in solutions of in the 60.0-40.0 mol % aluminum chloride-1-ethyl-3-methylimidazolium chloride room-temperature molten salt at 28°C using periodic-current plating techniques. The plating techniques that were investigated include pulse current, superimposed-pulse current, and reverse-pulse current. The composition of the electrodeposited alloy was determined by using rotating ring-disk anodic linear sweep voltammetry. The electrodeposition of Cu-Al is complicated by the instability of the alloy in solutions containing If alloy electrodeposits are removed from cathodic protection while immersed in the plating bath, a condition that occurs during the pulse plating “off-time,” in the plating solution oxidizes Al from the electrodeposits. The rate of this displacement reaction is greatest for small values of but decreases as becomes longer, suggesting that a copper-rich layer forms on the electrodeposits that blocks the displacement reaction. The displacement reaction can be minimized by lowering the concentration at the electrode surface through the application of a superimposed current during whose magnitude is comparable to that of the limiting current for © 2001 The Electrochemical Society. All rights reserved.