Characteristics of nickel thin film electroplated by supercritical CO₂ emulsion assisted with ultrasonic agitation

This study uses a novel fabrication method of thin metal coatings by Ni electroplating combining ultrasonic agitation with supercritical CO₂ (US-SC-CO₂) mixed into conventional electrolyte. Coatings were also produced by the conventional and regular SC-CO₂ electroplating methods for comparison. The characteristics obtained from the three fabrication methods such as surface morphology, hardness, roughness; crystallographic orientation, grain size; wear and corrosion resistance were all individually analyzed. Results show that plating quality achieved by US-SC-CO₂ method is superior to that of regular SC-CO₂ and conventional methods. With US-SC-CO₂ process we achieved smoother and more compact surface morphologies, smaller grain size, lower surface roughness and higher microhardness, which also suggest good wear resistance.