Contribution of Zn–Co Alloys Coatings Study: Electrodeposition Methodology, Micromechanical Properties, and Tribological Behavior

: An overview of the literature reveals that electrodeposition baths significantly influence deposited coatings’ morphology and properties. The present study investigates a sulphate-based bath in terms of the additive, pH, and temperature for the electrodeposition of Zn–Co alloys onto mild steel, achieving a nanocrystalline structure. The obtained results of the cyclic voltametric and SEM analyses revealed that sodium allowed the enhancement of cobalt electrocrystallisation (22.6 wt%) to homogenize further layers’ structure. However, the adjustment of pH allowed for the obtention of deposits with a refined structure containing only 5 wt% cobalt. Although an increase in room temperature resulted in deposit coatings with the same cobalt content, it notably produced a smoother structure. Subsequently, Zn–Co coatings were compared to pure zinc layers in terms of micromechanical and tribological behaviour. The morphology shifted from hexagonal platelets to nodular structures with the incorporation of cobalt, leading to an increase in microhardness. The morphology transformation, coupled with micromechanical reinforcement, contributed to the mitigation of friction and the improvement of the wear resistance of zinc layers through cobalt alloying. In fact, this improvement enhances the performance of zinc-coated applications in automotive and aerospace industries, particularly for standard assembly components that require adequate resistance to wear and abrasion during handling and tightening.