Corrosion Inhibition Properties of Epoxy-Zinc Oxide Nanocomposite Coating on Stainless Steel 316L

Abstract

Metal corrosion generally refers to metal deterioration process that is caused by electrochemical reactions between the metallic substrate with corrosive environment. Marine grade stainless steel type 316L (SS 316L) is a premium material for marine applications. Prolonged exposure to chloride-containing environments increases the susceptibility of unprotected SS 316L to localized corrosion namely pitting and crevice corrosion. In this study, the potential protective coating comprising of the epoxy matrix with ZnO nanoparticles combination was formulated and its anticorrosive properties on SS 316L substrate were analyzed. Variation in corrosion behaviour of SS 316L coated with a series of epoxy coating solution containing 1, 3, 5, 7 and 10 wt % ZnO nanoparticles were thoroughly observed. The coating formulations were characterised by using X-ray Diffraction (XRD) spectroscopy and Scanning Electron Microscope (SEM). Meanwhile, the corrosion performance testing was measured by using Potentiodynamic Polarization (PP) technique. The results revealed that epoxy coating incorporated with 3 wt % of ZnO nanoparticles provided the best corrosion protection on SS 316L as the corrosion rate for the metal substrate has been minimized from 0.05268 mm/year to as low as 0.00047 mm/year after coating. Dispersion of ZnO nanoparticles in epoxy matrix increases the barrier properties of the coating and impeded corrosion process on SS 316L through suppression of anodic reaction.