Corrosion protection of mild steel in different aqueous media via epoxy/nanomaterial coating: preparation, characterization and mathematical views

Corrosion rates of mild steel in different aqueous solutions at different operating conditions were studied by weight loss technique in the absence and presence of epoxy coating. It was found that corrosion rates increased with temperature and salt concentration and decreased with pH values. Presence of coating reduces the corrosion rates to significant values in acidic solutions. The performance of the coating was poor in saline solution. A magnesium oxide (MgO) nanoparticle was prepared via sol-gel method and the diagnosis was carried out by XRD technique. Maximum coating efficiency was 97% in acidic solution, while the lower one was 29.8% in saline solution in absence of nanoparticles. Nano scale MgO was used effectively with epoxy coating in saline solutions and improve the coating performance with maximum value of 93.7%. SEM test was also used to study the surface morphology. Several mathematical models were suggested to correlate the operating condition with corrosion rate. Polynomial interaction effect model was suitable to represent the data with a high correlation coefficient. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.