Growth Mechanism of Ni-graphene Composite Coating on Mild Steel: A Combined Experimental and Molecular Dynamics Study

Abstract

In this work, experimental studies were combined with molecular dynamics (MD) simulations to obtain a better understanding of the growth process of Ni-graphene composite coating. Conventional electrochemical techniques (cyclic voltammetry and chronoamperometry) were employed to investigate the electrochemical kinetics and nucleation process of the deposition. The three-dimensional (3D) morphologies of the deposits were observed by using an atomic force microscope (AFM), and the quantitative comparison of surface parameters and grain distribution was conducted. Moreover, MD simulations were employed to model the deposition process of Ni-graphene composite coating, which revealed the co-deposition process and facilitated the prediction of surface roughness evolution. The findings reveal that the Ni-graphene electrodeposition under present conditions tends to follow instantaneous nucleation and diffusion-controlled 3D growth at the initial stage. The graphene reinforced composite coatings have higher grain density, finer grain size, and rougher surface morphology than the pure Ni coating. Enhanced electrolytic corrosion resistance and uniform graphene configuration can be achieved at an optimal graphene oxide concentration. Through systematic experimental tests and MD simulations, this work provides deeper insight into the complex deposition process of Ni-graphene composite coating.