Development of trimetallic cobalt-nickel-vanadium oxide anticorrosion coatings for the protection of AA2024 Al alloy specimens against sodium chloride solutions

Trimetallic cobalt-nickel-vanadium oxide (CoNiVO_x) thin films were fabricated on aerospace grade AA2024 Al alloy specimens to investigate their behavior as anticorrosion coatings in a sodium chloride (NaCl) medium. Compact and homogenous nanostructured CoNiVO_x coatings were developed using aerosol-assisted chemical vapor deposition by varying the deposition duration from 45 to 150 min at a constant temperature (475 °C). The structure and composition of the trimetallic CoNiVO_x thin films were comprehensively investigated using X-ray diffraction, transmission electron microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, which demonstrated the successful synthesis of CoO/NiO/VO composite materials. The electrochemical corrosion properties of the trimetallic CoNiVO_x films in a 3.5 % NaCl solution were determined using Tafel extrapolation and impedance spectroscopic tests, whereas the electrochemical stability and localized corrosion characteristics were determined using scanning electrochemical microscopic analyses. This study demonstrates that the trimetallic CoNiVO_x oxide layer fabricated for 150 min exhibited an effective barrier protection performance on Al surfaces against corrosive attack in NaCl media.