Investigation of the Corrosion and Wear Behavior of Electrochemically Deposited Zn-Co-Graphene-TiO2 Nanocomposite Coatings on Ti6Al4V Substrates Fabricated by Selective Laser Melting (SLM).

This study investigates the microstructural, tribological, and corrosion properties of electrodeposited Zn-Co nanocomposite coatings reinforced with graphene and TiO2 nanoparticles on Selective Laser-Melted (SLM) Ti6Al4V alloy. Systematic characterization using XRD, SEM, and Raman spectroscopy revealed that the incorporation of graphene and TiO2 significantly refined the grain structure, resulting in a dense and defect-free surface morphology. Reciprocating wear tests demonstrated that the optimized hybrid coating (Zn-Co-GTi) exhibited superior tribological performance. Electrochemical impedance spectroscopy (EIS) tests conducted in simulated body fluid (SBF) at 37 °C demonstrated that the optimized hybrid coating (Zn-Co-GTi) also provided enhanced corrosion resistance. Specifically, the coefficient of friction decreased from 0.79 to 0.24, while the wear rate was reduced to 5.1 × 10-4 mm3/Nm. Electrochemical evaluations further confirmed a significant improvement in corrosion resistance, with the Zn-Co-GTi coating exhibiting the lowest corrosion current density (0.0059 μA cm-2) and the highest charge transfer resistance (Rct). However, increasing the reinforcement content beyond the optimum level resulted in partial nanoparticle agglomeration, leading to a slight deterioration in both tribological and corrosion performance. Overall, the optimized Zn-Co-Graphene-TiO2 nanocomposite coating provides an effective and scalable surface engineering strategy for improving the durability and corrosion resistance of SLM-produced Ti6Al4V components for advanced engineering and biomedical applications.