Enhancement in the corrosion resistance of nanocrystalline aluminium coatings by incorporation of graphene oxide

Abstract

Non-aqueous electrolyte containing aluminium chloride (AlCl3) and 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) topped with n-decane was used to electrodeposit aluminium (Al) coating via chronoamperometric method at ambient atmosphere. Aluminium-graphene oxide (Al-GO) composite coating was further obtained from the Al electrolytic bath by dispersing GO in it. GO was prepared by oxidation of high purity graphite. The Al deposition potential was noted by cyclic voltammetry (CV) method. Influence of GO on the morphology and microstructure of Al metal matrix was analysed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD). Inclusion of GO into the Al matrix enhanced the coating compactness thus nullifying the surface defects which were observed for the pristine Al deposit. The texture co-efficient calculation showed that the addition of GO altered the growth texture from growth predominately along (002) plane for pure Al coating to growth predominantly along (111) and (022) plane for Al-GO composite coating. The morphological and microstructural changes occurred in the Al coating from GO incorporation influenced the anti-corrosion behaviour of the coatings. The electrochemical corrosion analysis by Tafel polarization and Impedance Spectroscopy confirmed that the GO reinforced Al deposit possessed two-fold enhanced anticorrosive property than pure Al coating.