Cr2O3 nanoparticles: A promising candidate to improve the mechanical properties and corrosion resistance of Ni-Co alloy coatings

This study was aimed to assess the effects of reinforcement nanoparticles content, on the microstructural features, mechanical properties, and corrosion-related properties of Ni-Co-Cr2O3 nanocomposite coatings. Scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD) analysis were employed in order to evaluate the microstructural features and chemical composition of the nanocomposites. Moreover, the microhardness tester and electrochemical impedance spectra (EIS) tests coupled with potentiodynamic polarization measurements were used to investigate the mechanical and corrosion-related properties, respectively. Results demonstrate that albeit the volume fraction of cobalt in coating, average particle size, Cr2O3 nanoparticle content in coating, and microstructural features are of prime significance in determining the mentioned properties of the nanocomposite coatings, Co content is more important. Actually, Cr2O3 nanoparticles serve as suitable nucleation sites for Co particles deposition throughout the microstructure. Thus, combined actions of Cr2O3 nanoparticles incorporation and their optimal content ensures the nucleation of high population of Co particles, which significantly contributes to the improvement in the properties. The Ni-Co-8.9 wt%Cr2O3 nanocomposite coating exhibits the superior mechanical and corrosion-related properties.