Characterization of electrodeposited Ni-TiO2 nanocomposite coatings

Nanocomposites containing titania nanoparticles in a nickel matrix have been prepared by means of electrocodeposition from two different types of nickel plating baths, viz. an acidic sulfamate and an alkaline pyrophosphate bath. The surface charge and sedimentation behavior of the titania particles in these electrolytes were characterized by zeta potential and stability measurements. A maximum particle incorporation of 4.3 wt.% titania was found for the alkaline pyrophosphate bath. The structure and mechanical properties of the coatings have been investigated as a function of the particle content. The surface morphology and microstructure of the nickel matrix was significantly altered due to the presence of titania nanoparticles. In the case of both nickel baths, the Vickers microhardness showed a tendency to increase with the amount of particle incorporation. The wear resistance increased with decreasing current density and due to the particle incorporation.