The variation of thickness of electrodeposited coating on uneven substrates: study of Ni coating from acidic bath

Nickel coatings are widely used in various engineering applications due to their excellent corrosion resistance as well as adequate wear and erosion resistance. The coating process is generally performed by electroplating, which is simple and economical. However, one of the challenges of the electroplating process is the non-uniformity of coating thickness on substrates with sharp points and recesses. In this study, the effect of the substrate geometry on the non-uniformity of coating thickness was investigated and quantified. For this purpose, a screw, one of the most commonly used components in various industries, was coated in a Watts bath. Nickel coating was applied for different durations ranging from ۲ to ۲۵ minutes, and the thickness distribution on the threads was examined. The average thickness in three regions, meaning the tip, middle, and depth of the threads, was measured using scanning electron microscope images of the longitudinal section of the screws. The results showed that the coating thickness at the convex tip of the threads was on average three times greater than at the concave depth. The ratio of maximum to minimum thicknesses did not show a meaningful consistency with the deposition time.

کلیدواژه ها:

Nickel electroplating ، Watts bath ، coating thickness ، uniformity ، substrate effect