Anti-corrosion and Microstructural Properties of Nanostructured Ni-Co Coating Prepared by Pulse-Reverse Electrochemical Deposition Method

In this research, nanostructured Ni-Co coating was synthesized by reverse-pulse electrodeposition method using Watts bath under both ultrasonic and stirring conditions. The grain refinement agent, sodium saccharin, was added to the plating bath in order to achieve very fine grains for both coatings. The microstructure, microhardness, and corrosion resistance of the prepared coatings were evaluated. The ultrasonic treatment changed the texture, deposition rate, and chemical composition of the coating. A clear increase was seen in the texture coefficient for all (200) planes. The corrosion resistance of the coatings was analyzed by polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl solution at ambient temperature. Based on the results, the corrosion resistance of Ni-Co coating increased by 42%, the microhardness decreased by 16%, and the film thickness increased from 20 to 30 µm as a result of applying ultrasonic during electroplating, which can be attributed to the changes in composition and morphology of the coating.