Journal of Materials Research and Technology (Mar 2023)
Deposition of mono dispersed Co–CeO2 nanocomposite coatings by a sol-enhanced pulsed reverse electroplating: process parameters screening
Abstract
Co–CeO2 nanocomposite coatings are a unique engineering material with enhanced corrosion and wear properties and high oxidation resistance. The size and dispersion of the second phase within the matrix are of great concern in such coatings. Compared with a conventional method, the sol-enhanced nanocomposite electrodeposition process is a state-of-the-art route with high efficiency to fully disperse nanoparticles in the coatings. This study aims to deposit Co–CeO2 nanocomposite layers by incorporating CeO2 sol preparation with the Co electrodeposition process. Various process parameters were investigated, such as the current density, duty cycle, frequency, and CeO2 content in the electrolyte. FE-SEM surface morphology, BSE-SEM cross-sectional observations, surface XRD characterization, Vickers microhardness measurements, and Daimler-Benz adhesion test were performed to characterize and evaluate the coatings. Preliminary study of electrodeposition process under a pulsed reverse current screened duty cycle, frequency, and current density to 90%, 100 Hz, and <9 A dm−2, respectively. FE-SEM surface observations proved the co-deposition of ∼10 nm CeO2 particles within the Co matrix. The CeO2 content of the coatings reached to ∼2.5 wt % where a maximum hardness of ∼400 HV was achieved. The deposit growth model changed from a columnar to a disorganized columnar grain structure by incorporating the second phase into the matrix. The coating adhesion to the substrate was strong for all samples, according to the Daimler-Benz adhesion test. However, shorter cracks inside the indentation craters and lower depth of stress-affected zones (SAZ) were observed with microhardness increase of the coatings via analytical characterization of the indentation crater.
