Effect of SiC and Al2O3 particles on the electrodeposition of Zn, Co and ZnCo: II. Electrodeposition in the presence of SiC and Al2O3 and production of ZnCo–SiC and ZnCo–Al2O3 coatings

Abstract

SiC or Al2O3 microsized particles were added to acid sulfate-based solutions for the electrodeposition of Zn, Co, and ZnCo. Initially, their effects on the electrochemical processes were evaluated. The Zn electrodeposition rate was increased in both SiC and Al2O3-loaded solutions. The Co electrodeposition rate was also increased by SiC. However, Al2O3 decreased it, especially at the beginning. Both SiC and Al2O3 influenced the electrodeposition of ZnCo positively at moderate loadings. The factors involved in producing ZnCo–SiC and ZnCo–Al2O3 composites were evaluated. ZnCo–SiC composites could be deposited with a higher [Co/Zn] ratio in the metal matrix than for pure ZnCo. In ZnCo–Al2O3, the [Co/Zn] ratio was smaller than in ZnCo and ZnCo–SiC. It was necessary to reduce the CoSO4 concentration to improve the Al2O3 co-deposition. The variation in [Co/Zn] ratio could, in principle, be related to the effects of SiC and Al2O3 on the individual Zn and Co electrodeposition.