Electroplating of Ni–ZrO 2 nanocomposite coatings on 40CrNiMo7 alloy

Ni–ZrO₂ nanocomposite coatings were obtained by electroplating using Watts nickel baths with different concentrations of ZrO₂ particles in suspension. The substrate was horizontally immersed in the bath to enhance the ZrO₂ content in the Ni matrix. X-ray diffraction analysis showed that the presence of ZrO₂ leaded to the intensity of crystal face (311) sharply increasing, and, simultaneously, the crystal orientation of (220) was greatly decreased. Observation using scanning electron microscopy indicated that the incorporation of ZrO₂ nanoparticles also caused changes in the morphology and size of Ni grains. Although agglomeration of ZrO₂ nanoparticles occurs in the deposits, the nanocomposites exhibited a great improvement in wear resistance compared to those of unreinforced Ni coating.