An Application of Electrochemical Method for Studying Nano-Composite Plating

Nickel plating is investigated using an electrochemical method in this study. Cathodic polarization indicated that electrode polarization at a current density of 10(-1) A/㎠ increased by approximately 100 ㎷ in a pH range 3-5, and by nearly 150 ㎷ with 1 g/L of carbon powder in a Watts solution, as compared to bare nickel. The influence of inert particles such as carbon powder, silicon carbide and rice husk ash included in the nickel deposit was studied further using a potentiodynamic technique. Results showed that a co-deposit of nano-particles increased cathodic polarization. With a three-fold increase of the carbon powder in the plating solution, the polarization potential of the nickel deposit was doubled at a current density of 10(-2) A/㎠. Passivation of the nickel deposit in the presence of all of the inert particles studied was improved in the area of hundreds of times higher compared to a bare nickel deposit. By increasing the amount of inert particles to twenty times the original amount, the passive current density was decreased by 85-95%. A co-deposit of rice husk ash in the nickel deposit decreased the passive current density by 98%, compared to a carbon and silicon carbide powder. Thus, rice husk ash has the potential to improve the pitting corrosion resistance of nickel composite plating.