Fabrication of thickness-controlled NiPd nanoalloy thin films as anticorrosive coatings on 316L SS substrates for application in marine environment

Herein, thin NiPd nanoalloy thin films were coated on 316L stainless steel (SS) substrates by aerosol-assisted chemical vapor deposition (AACVD) to investigate their capability to protect the SS surface against corrosion in a marine environment. The nanoalloy films were coated at various thicknesses (1–2 μm) by changing the deposition time from 1 to 3 h using a precursor solution consisting of nickel(II) acetylacetonate and palladium(II) acetylacetonate. Analyses by X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy confirmed the successful formation of clustered crystalline nanoparticles of NiPd alloy films with high phase purity and controlled thickness on steel substrates. The surface protection performance of the deposited films against corrosion in a 3.5% NaCl electrolyte was studied by potentiodynamic polarization and electrochemical impedance spectroscopic analyses, while the localized corrosion features were examined by the scanning vibrating electrode technique. These analyses suggested that the NiPd alloy film formed at a deposition time of 2 h exhibits excellent barrier protection performance against corrosion in the NaCl solution. Thus, the NiPd nanoalloy film formed by the facile, rapid, and cost-effective AACVD route is a highly promising protective coating for SS against the corrosive marine environment.