Fabrication and characterization of boron nitride reinforced Ni–W nanocomposite coating by electrodeposition

Abstract

Ni–W/BN nanocomposite coating was successfully synthesized by direct current (DC) electrodeposition in the present work. Their surface morphology, structural characterization and electrochemical properties were investigated by SEM, XRD, AFM, XPS and EIS methods. The influence of BN on the properties of Ni–W/BN nanocomposite coating were discussed. Results indicate that the electrodeposited coatings were uniform and compact without cracks, containing homogeneously distributed 2–4 wt% BN particles and 22–29 wt% W. The growth rate of Ni–W/BN was about 0.4 μm min−1 at 2 A dm−2 and its grain size was about 11–13 nm. The average roughness values Ra of Ni–W/BN were 78–100 nm. The hardness and wear resistance first increase then followed by a decrease with the increase of BN concentration. The coating contains metallic nickel, tungsten and the corresponding oxidized/hydroxide, as well as BN particles. The inclusion of BN in Ni–W alloy could refine grains, decrease porosity and enhance the shielding effect. The corrosion resistance of Ni–W/BN nanocomposite coating firstly increased and then decreased with the increase of BN. The higher concentration of BN nanoparticles has adverse effects on the properties of the coating.