Internal stress of high tungsten content Ni-W alloy coatings.

This article examines the effects of current density on the microstructure, composition, and internal stress of nickel-tungsten (Ni-W) alloy coatings electrodeposited from a citrate electrolyte system. It finds that increasing current density raises tungsten content and current efficiency, transforming the coating from a nanocrystalline to an amorphous-nanocrystalline structure with preferred (111) orientation. The study highlights that carbon content, influenced by the addition of 2-Butyne-1,4-diol as a carburizer, plays a key role in reducing tensile internal stress by promoting carbide formation near grain boundaries, which mitigates coating shrinkage caused by hydrogen evolution. Lower internal stress correlates with improved corrosion resistance, particularly in coatings with high tungsten and carbon content. The research suggests that controlling carbon incorporation during electrodeposition is a promising approach to optimize the mechanical and corrosion properties of Ni-W alloy coatings.