The Effect of Surface Pretreatment on the Corrosion Performance of Graphene Coatings on 6061 Aluminum Alloy

Abstract

This study presents an investigation into the effect of surface pretreatment on the electrochemical characteristics and corrosion behavior on graphene coated 6061 aluminum alloy (Al 6061). The corrosion properties of graphene coated 6061 aluminum alloy with different surface pretreatments were studied using electrochemical impedance spectroscopy (EIS), and polarization measurement. Surface morphologies of pretreated and coated samples were analyzed by atomic force microscopy (AFM). The integrity of graphene transferred from the growth Cu substrate was examined by Raman spectroscopy. We also investigated the adhesion between the graphene and Al 6061 by measuring the water and diiodomethane contact angle, and calculating the surface free energy of various pretreated samples.

Challenges for continuous graphene as a corrosion barrier

“…This is in contrast to some types of conventional coatings, where surface roughness may be increased by etching or blast cleaning (Hagen et al 2016) to anchor the coating, increasing contact area and slowing down cathodic delamination (Sørensen et al 2009b). For chemically inert coatings like graphene that do not spontaneously form chemical bonds with the substrate, a nitric acid treatment of the metal substrate before transfer can make it smoother and thereby improve adhesion between metal and coating (Huang et al 2017). Strong graphene-metal interaction is essential to achieve effective long-term protection of the metal (Weatherup et al 2015), and even though using transferred graphene could expand the applicability of CVD graphene to a larger range of substrates, poor adhesion still remains a serious roadblock.…”