A review of corrosion resistance of metals coated with graphene

Corrosion is a serious global problem. Chemical reaction occurs when metal surface comes in contact with oxygen in air, resulting metals being oxidized and corroded [1, 2]. Various methodshave been employed by the industries to protect metal from corroding, such as coating with othermetal(s), chemical modification, anodizing, using an oxide layer and organic layer/polymer coating [2].Recently, graphene, which was successfully grown on large-area metals substrates by different methods was tested as a barrier and shown to protect metals surfaces from oxidation [1-5] because of its impermeability [6]. The purpose of this study is a review of low cost method for protection of metal surface from oxidation with graphene.Methods Some authors conducted studies on the oxidation resistance of graphene and graphene base composite materials [7- 10] coated Cu [1, 2], Ni [5], Cu/Ni alloys, Fe [2], Pt [9], Ti [10], Co [9],Mg [3] and stainless steel [8]. However, all the above mentioned graphene coatings weredeposited via chemical vapor deposition (CVD) which involve tedious and high vacuum system. Electrophoretic deposition (EPD) is a simple electrochemical method used to deposit thin layer ofcoating onto any conducting substrate [1]. Results and discussionGraphene, which was successfully grown on large-area metal substrates by a CVD method was tested as a barrier and shown to protect Cu and Cu/Ni alloy surfaces from oxidation. Fe can alsobe used for CVD graphene growth. However, uniform graphene layers have not been achieved onFe substrates. Reduced graphene oxide (rG-O), when deposited as a thin film, is an alternative candidate for protecting Fe and Cu surfaces because large thin films can be readily formed by a solution process [2- 5]. Results showed the possibility of CVD graphene as a layer of corrosion barrier. It was confirmedthat chemical vapor deposition (CVD) graphene layer works as a barrier for Cu and Cu/Ni alloy against air oxidation and chemical oxidation in the solution of 30% hydrogen peroxide [1, 8]. Fig.1 shows the polarization curve for the bare copper and Cu+G samples that GO solution used asthe electrolyte in the electrophoretic deposition (EPD) process. The polarization curve enables the corrosion potential and the current densities, iCORR to bedetermined and compared between the graphene coated and uncoated copper sample. Thecorrosion potential, ECORR is a measurement of sample resistance towards corrosion. From the polarization curve, it can be seen that there is a shift in the ECORR towards the positive directionfor the Cu+G sample. It proves the graphene coating acts as a corrosion resistance barrier [1]. Conclusion In summary, this review shown that graphene can work effectively as a corrosion inhibiting coating on metal surfaces against O2 exposure at partial pressures. It is believed that agraphenematerial which is coated on the metal surface would be an effective strategy for improving the anticorrosion performance of various engineering materials. This proposed method of corrosion passivation is quite versatile and is applicable to arbitrary metallic surfaces that are either smooth or rough [3].

Keywords:

Graphene , Corrosion , CVD , EPD , Oxidation