Copper–zinc electrodeposition in alkaline-sorbitol medium: Electrochemical studies and structural, morphological and chemical composition characterization

Abstract

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 (jdep) and charge density (qdep). The highest current efficiency was ∼54.0%, at jdep −1.0mAcm−2 and qdep 0.40Ccm−2 in the Cu70/Zn30 bath. Energy dispersive spectroscopy indicated that electrodeposits produced from the bath Cu70/Zn30 showed higher Cu content at lower jdep. Also, for same jdep the Cu content increased with qdep. 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 jdep −20.0mAcm−2 and qdep 10.0Ccm−2. Also, these electrodeposits did not present cracks. X-ray analysis of the Cu–Zn electrodeposits obtained at jdep −8.0, −20.0 and −40.0mAcm−2, in each case, with qdep 2.0 and 10.0Ccm−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.