EFFECTS OF ELECTROLYTE BATH COMPOSITION ON THE SURFACE PROPERTIES AND NICKEL CONTENT OF ZINC-NICKEL ELECTROPLATING

Electroplating is used as a surface protection process in several industries. The well-known cadmium electroplating needs an alternative due to the environmental hazards, and occupational safety and health risks arising from the carcinogenic nature of cadmium. Zinc-nickel alloy electroplating has the potential to replace cadmium plating in surface protection applications. This paper investigates the effect of acidic and alkaline electrolyte baths on the composition and surface properties of the zinc-nickel electroplating on 300M steel. Five electrolyte baths with different levels of chloride and citrate content were studied. Scanning Electron Microscope (SEM) imaging of specimens was done to study the surface morphology. The composition of nickel in the plating was determined using Energy Dispersive Spectroscopy (EDS) while the phase analysis was conducted by X-ray Diffraction (XRD). Incorporation of chloride in the electrolyte baths increased the nickel composition in the deposit while citrate addition reduced it in the deposit obtained from the acidic electrolyte. Surface roughness was measured using a stylus profilometer. It was observed that smoother surface was obtained with alkaline electrolyte baths. The surface wettability was obtained by measuring the contact angle between deionized water and the plating. Alkaline electrolytes produced higher surface wettability in the plating than acidic electrolytes. Also, the wettability of the surface was found to increase when the alkaline electrolyte was used without any chloride accelerators.