Electrochemically promoted electroless nickel-phosphorous plating on titanium substrate

Abstract

An electrochemically promoted electroless nickel–phosphorous plating process on titanium substrate is proposed. The influences of the temperature and current density on the phosphorous content, coating thickness and corrosion resistance are investigated. The results show that with the help of the electrochemical promotion, the uniform and amorphous nickel–phosphorous coatings with medium phosphorus content (6–8wt%) are successfully prepared in the electroless bath at 40–60°C. The phosphorous content of the coating increases with the temperature increasing, while decreases with current density increasing. Obvious passivation occurs for the nickel–phosphorous coatings during the anodic polarization in 3.5wt% NaCl solution.