Applied Surface Science, Vol.333, 13-22, 2015
Copper-zinc electrodeposition in alkaline-sorbitol medium: Electrochemical studies and structural, morphological and chemical composition characterization
The galvanostatic technique was used to analyze the electrodeposition of Cu-Zn on to AISI 1010 steel electrode from an alkaline-sorbitol bath with various proportions of the metal ions in the bath: Cu70/Zn30, Cu50/Zn50 and Cu30/Zn70. Coloration of Cu-Zn films were whitish golden, light golden, golden/gray depending on the Cu2'/Zn2+ ratios in the electrodeposition bath, deposition current density (jd,) and charge density (qd). The highest current efficiency was -54.0%, atjd -1.0 mA cm -2 and qd 0.40 C cm -2 in the Cu70/Zn30 bath. Energy dispersive spectroscopy indicated that electrodeposits produced from the bath Cu70/Zn30 showed higher Cu content at lower jd. Also, for same jd the Cu content increased with qd,. Scanning electron microscopy showed that Cu-Zn electrodeposits of high quality were obtained from the Cu70/Zn30 bath, since the films were fine-grained, except the obtained at jd, -20.0 mAcm-2 and qd, 10.0 C cm -2. Also, these electrodeposits did not present cracks. X-ray analysis of the Cu-Zn electrodeposits obtained at jd, -8.0, -20.0 and -40.0 mA cm-2, in each case, with qd, 2.0 and 10.0 C cm-2, in the Cu70/Zn30 bath, suggested the occurrence of a mixture of the following phases, CuZn, CuZn5 and Cu5Zn8. Galvanostatic electrodeposits of Cu-Zn obtained from sorbitol-alkaline baths exhibited whitish golden color, with good prospects for industrial applications, especially for decorative purposes. (C) 2015 Elsevier B.V. All rights reserved.
Keywords:Galvanostatic electrodeposition;Cu-Zn alloys;Sorbitol-alkaline baths;Microstructure;Structural phase