Ni-Al polyvanadate layered double hydroxide with nanoceria decoration for enhanced corrosion protection of aluminium alloy

Abstract The present study introduces a modified layered double hydroxide (LDH) based system for corrosion inhibition on dual actions by both active and passive mechanisms. Nickel aluminium LDH (Ni Al LDH) intercalated with vanadate ion was further decorated with ceria nanoparticles. The modifications of LDH were confirmed by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, infrared and Raman spectroscopy. We have investigated the effect of nanoceria decoration on Ni Al LDH for the corrosion inhibition efficiency with and without intercalation of vanadate species on A356 aluminium alloy by electrochemical analysis and immersion test. The bare metallic substrates in 3.5 wt% sodium chloride solution containing inhibitor loaded LDH were tested to understand the inhibition mechanism. The presence of stable ceria nanoparticles layer can be an effective cathode, which passively protects the metal from corrosive anions and water molecules. The release of vanadate species during anion exchange of LDH with chloride ion in the corrosive environment and formation of polymeric vanadate on the surface actively protects the metal from further corrosion. The modified LDH loaded epoxy composite coatings were also made on A356 alloy to study the corrosion resistance in the real applications.