Fabrication and Wear Resistance of Ni-CeO2 Nanocomposite Coatings by Electrodeposition under Ultrasound Condition

Abstract

Ni-CeO2 nanocomposite coatings were fabricated by a novel method from a modified Watt’s type electrolyte containing CeO2 nanoparticles with an average particle size of 30 nm, where an ultrasonic field was imposed during electrodeposition process. Surface morphologies of the coatings were examined by a scanning electron microscope (SEM) with energy dispersive analyzer system (EDX) to determine the composition of nanocomposite coatings. The crystal structure of coatings was characterized by employing the X-ray diffraction (XRD). Vickers hardness of nanocomposite coatings was measured with a microhardness tester. The wear resistance of Ni-CeO2 nanocomposite coatings and pure Ni coating was comparatively investigated on a UMT-2MT test rig in a ball-on-disk contact mode. It was found that the Ni-CeO2 nanocomposite coating with ultrasonic irradiation exhibited grain structure with finer and compact crystal of Ni matrix compared to pure Ni and the Ni-CeO2 nanocomposite coating without ultrasonic irradiation. The crystal orientation of Ni-CeO2 nanocomposite coatings greatly changed in presence of ultrasound. Furthermore, the imposition of ultrasound gave rise to increasing the hardness and wear resistance of the Ni-CeO2 nanocomposite coating. The results could be considered as the effects of nanoparticles embedded and ultrasonic irradiation and the finer-grain structured coating resulted. The improvement in the wear resistance of Ni-CeO2 nanocomposite coatings can be attributed to the grains refinement of Ni matrix in presence of ultrasound as well as the dispersion-strengthening effect to some extent. Because of the aid of ultrasound, the co-deposited CeO2 nanoparticles were uniformly distributed in Ni matrix and contributed to largely increase the microhardness and wear resistance of the nanocomposite coatings.