elaboration and characterzation of NI-CeO2 coating :evaluation of anticorrosion properties

Abstract

Nickel coatings are widely recognized for their intrinsic corrosion and wear resistance, high hardness, and excellent mechanical integrity. However, under prolonged exposure to chloride-rich conditions, nickel coatings can suffer from localized corrosion, cracking, and delamination.To overcome these challenges, Ni coatings performance can be enhanced through the incorporation of advanced nanomaterials. Therefore, in the present study, graphene (Gr) nanosheets were synthesized via controlled electrochemical exfoliation and a novel Ni-CeO2-Gr ternary nanocomposite coating was elaborated on copper substratesby the incorporation of synthetized graphene nanosheets and cerium oxide (CeO2) nanoparticles into the nickel matrix via co-electrodeposition and under identical optimized electrodeposition parameters (watts bath, 55°C, 0.1g/L SDS at 55 mA/cm2). The elaborated coatings were characterized using optical microscopy, scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS), Raman spectroscopy, X-ray diffraction (XRD), Vickers microhardness and micro-scratch tests. While the electrochemical properties of the coatings were evaluated by electrochemical impedance (EIS) and DC-polarization measurements in 0.5 M NaCl. SEM-EDS, Raman, and XRD analysis confirmed the successful synthesis of high-quality single layer graphene. The incorporation of CeO2 nanoparticles and graphene nanosheets into the nickel coating matrix was confirmed by SEM‑EDS, XRD and Raman spectroscopy. it was found that the ternary Ni-CeO2-Gr coating achieved an outstanding microhardness of 915.6 HV, which is 3.5 times higher than conventional Ni coatings (265 HV) and exhibited a significant increase in critical load, indicative of superior cohesive strength and resistance to delamination. Furthermore, electrochemical impedance spectroscopy (EIS) and DC‑polarization measurements in 0.5 M NaCl demonstrated that the Ni-CeO2-Gr composite possessed the highest polarization resistance (544 kΩ.cm2) compared to pure Ni (30 kΩ.cm2) and both binary composites. This remarkable enhancement is due to the synergistic effect of the graphene’s impermeable lamellar structure and CeO2 duplex layer within the Ni matrix, forming a robust anticorrosion barrier. the results confirm that optimized electrodeposition parameters combined with duplex nanomaterial reinforcement offer valuable insights into the designing highly efficient advanced nanocomposite coatings for corrosion protectionfor demanding industrial applications. Key words: Ni-CeO2NPs-Graphene nanosheets, Ternary nanocomposites Coatings, Co-electrodeposition, Corrosion resistance, Surface characterization, Electrochemical exfoliation, EIS, DC-polarization, Vickers microhardness, scratch test