Improvement of Microstructure and Wear Resistance of the Ni-La₂O₃ Nanocomposite Coatings by Jet-Electrodeposition

A jet electrodeposition, a special electrodeposition method, was used to produce Ni-La₂O₃ nanocomposite coating. The influence of key experimental conditions including current density and La₂O₃ nanoparticles added in the electrolyte on the composite coating morphology, phase structure, surface roughness, microhardness and wear resistance were examined. It is found that by properly increasing the La₂O₃ nanoparticles in the electrolyte and increasing the current density, a composite coating with dense and grain-refined structure can be formed with improved surface roughness and mechanical and tribological properties. It is also proved that jet velocity helps to increase the La₂O₃ content in the composite coating. With the optimal experimental parameters including a current density of 80 A/dm², La₂O₃ addition of 30 g/L and jet velocity of 8 m/s, a smooth and consolidated Ni-La₂O₃ coating was obtained with a hardness of 618 HV, surface roughness of 0.213 μm and wear rate of 6 mg/min. A smooth and only slight abrasive wear of the worn surface was also observed.