Composite coatings have a wide range of application areas requiring improved mechanical and tribological properties^[1,2]. These application areas include aerospace, automotive, chemical and electrical industries. High mechanical and tribological performances can be achieved by incorporation of hard ceramic particles into nickel matrix, which possess anti-corrosion properties. Due to its enhanced properties, Ni-Al₂O₃ electro-co-deposition rather than pure Ni electrodeposition was investigated. A typical sulfamate bath was used to evaluate the effects of current density, the amount of alumina in the electrolyte and the amount of surfactants. Ammonium lignosulfonate and sodium dodecyl sulfate were used as the surfactants in varying concentrations to arrange the floatation and wetting conditions of Al₂O₃particles (~300 nm) in the electrolyte. The influences of plating parameters on mechanical and tribological properties of the co-deposits like hardness, friction coefficient and wear were determined.

It was found that Increase in current density increases the hardness and deposited wt.% Al₂O₃ particles within the parameter ranges covered in this study. A representative cross-sectional view of Al₂O₃–Ni composite coating is shown in Figure 1.

References

[1] Vitry, V., Kanta, A. F., and Delaunois, F. (2012). Application of nitriding to electroless nickel–boron coatings: Chemical and structural effects; mechanical characterization; corrosion resistance. Materials & Design, 39, 269-278.

[2] Saraloğlu Güler, E., Karakaya, İ. and Konca, E. (2014) Effects of current density, coating thickness, temperature, pH and particle concentration on internal stress during Ni-MoS2 electrocodeposition, Surface Engineering, 30, 109-114.