Induced electrodeposition of alloy coatings from baths containing different systems of complexing agents: Preparation and enhanced properties of Co-Mo-Ni-W coatings

Alloy materials are widely used as wear-resistant coatings due to their good mechanical properties. Here, we report the co-electrodeposition of Co-Mo-Ni-W alloy coatings on copper metallic substrate from electrolytes containing different systems of complexing agents. As the properties of Co-Mo alloy coatings can be improved by the addition of Ni, Co-Mo-Ni alloy coatings have been prepared. They were found to be amorphous, showing a nodular morphology. Moreover, Mo content in the alloy was 55.75 wt%, and microhardness value of 617 HV were determined. To further improve the alloy coatings properties, tungsten has been included. The electrode-position of a Co-Mo-Ni-W alloy coating was performed using a bath containing the composite system of complexing agents C6H5O7Na3-C6H8O7-Na(2)EDTA (where Na(2)EDTA is disodium ethylenediaminetetraacetic acid). The Mo and W contents of the Co-Mo-Ni-W alloy coating were 45.39 wt% and 2.3 wt%, respectively, and its microhardness was as high as 685 HV. Results of electrochemical characterization of the prepared alloy coatings showed that the addition of Ni to the electrolyte determined an anodic shift in the deposition potential, an increase of the exchange current density, and a decrease of the charge transfer resistance, which led to an increase of the Mo content in the coating. The addition of Na2WO4 caused a cathodic shift in the deposition potential, a decrease of the exchange current density, and an increase of the charge transfer resistance. In addition, a diminishing of the Mo content in the coating was noticed. The addition of Na(2)EDTA produced a cathodic shift in the deposition potential, a decrease of the exchange current density, and an increase of the charge transfer resistance. The addition of Na(2)EDTA also facilitated the increase of the Mo and W contents in the coating, and induced the coordinated co-electrodeposition of the multicomponent metallic system.

Automated summary

In this study, Co-Mo-Ni-W alloy coatings were co-electrodeposited on a copper metallic substrate using electrolytes containing different systems of complexing agents. The addition of different complexing agents resulted in changes in the deposition potential and hardness of the coatings, as well as the Mo and W content in the coatings.