Development and Characterization of Nickel-Graphene Nano Composite Coating for Corrosion Protection of Steel

Abstract

Nickel is a common and abundantly found material. Nickel composite coatings have been useful in providing optimal protection against corrosion and one of the abundantly researched composite coatings. The primary focus of this research is to develop a composite coating which can provide optimal protection against corrosive environment. Graphene is a new age material and has impressive properties; incorporation of graphene nano particles in nickel matrix provides better corrosion resistance and surface roughness as compare to pure nickel coatings. Graphene oxide (GO) was first reduced by hydrazine hydrate and then used for developing composite coating. Reduction of graphene oxide to reduced graphene oxide (rGO) was confirmed by SEM, XRD and FTIR. Electrochemical deposition technique was used for developing nickel-graphene composite coatings on steel substrate. Composite coatings were developed at different deposition current densities 3.6Adm-2 , 9Adm-2 and 14.5Adm-2 T were characterized by SEM, EDX and XRD. Three application testing Polarization Testing, EIS and Two Dimensional Non-Contact Profilometry (roughness assessment) were carried out to find the efficiency of developed composite coatings. SEM results showed a spherical morphology and bulges which increased with an increase in deposition current density. Coating developed at higher deposition current density 14.5Adm-2 displayed more number of bulges as compared to others. EDX result showed an increase in amount of carbon content in coatings with increase in deposition current density. XRD results showed a reduction in grain size with increasing deposition current density and reduction in (200) peak. Corrosion rate of composite coating in 3.5% NaCl solution was found by electrochemical polarization testing; coating developed at high deposition current density showed low corrosion rate as compared to coatings developed at low deposition current densities. EIS was carried out in 3.5% NaCl solution and EIS spectra showed semi-circles of different diameters depending upon the deposition current density. Coatings developed at high deposition current density exhibited semi-circle of larger diameter indicating higher impedance of developed composite coatings. Roughness assessment of composite coating was done by Two Dimensional Non-Contact Profilometry and roughness in terms of Rq (root mean square roughness) and Ra (average roughness) were found and roughness increased with an increase in deposition current density.