Development of Ni-Co-CNT composite coatings for corrosion protection of mild steel in 5% NaCl

Abstract

In this report, corrosion resistance of Ni-Co-CNT composite coatings on mild steel was studied. The deposition step follows composite-electrodeposition technique. The effect of CNT nanoparticle on corrosion resistance behavior of Ni-Co alloy coatings on mild steel were studied. The Ni-Co bath contents such as electrolytes, stabilizer and additives were optimized by using Hull cell. The optimized amount of CNT particle in the bath was found to be 0.5g/L. The surface modification of Ni-Co alloy coatings in the presence of nanoparticle was studied interms of their corrosion resistance behavior. The Ni-Co-CNT composite coatings was developed at different current densities. The corrosion protection efficacy of the deposited coatings has been studied by using Tafel extrapolation and electrochemical impedance techniques. The Ni-Co-CNT coating was found to be more stable and results showed linear change of potential with time. The result depicted that deposited composite coating on mild steel at a current of 4.0Adm −2 was found to be more corrosion resistance as compared with other current density coatings. This was attributed to decrease of size of the particle with increase of current densities as confirmed by AFM analysis. The chronopotentiometry technique revealed that coating was found to be more stable for several hours at different current densities. The coating obtained at a c.d of 4.0A dm −2 was found be more stable towards corrosion and confirmed by Chrono potentiometric techniques.