Corrosion resistance of Ni-Cu-Ni coating under hydrostatic pressure: Experimental and molecular dynamics investigations

Abstract

This study employs pulsed electroplating to fabricate Ni-Cu-Ni multilayer coatings with high corrosion resistance, aiming to elucidate the impact and mechanism of hydrostatic pressure on the corrosion behavior of these coatings. The findings indicate that high hydrostatic pressure promotes the formation and propagation of pitting corrosion as well as the development of cracks in the surface corrosion products. By integrating molecular dynamics (MD) simulations, it is revealed that the strong permeability and aggressiveness of Cl^- are the primary factors responsible for the initiation of pitting corrosion in the coatings under the high hydrostatic pressure conditions. High hydrostatic pressure not only increases the activity (effective concentration) of Cl^- and H₂O, enhancing the interaction between these species and the metallic surface of the coating, but also accelerates the corrosion reaction rate and changes the corrosion reaction mechanism. The combined effects of the accelerated corrosion product formation and internal stress within the pits lead to the cracking and spalling of corrosion products, providing convenient pathways for further Cl^- penetration, thereby accelerating the overall corrosion of the coating. This research offers a theoretical guidance for understanding the corrosion behavior and mechanisms of coatings in hydrostatic pressure environments.