The influence of praseodymium (Ⅲ) oxide (Pr2O3) on the corrosion resistance and adhesion properties of an epoxy-polyamide coating on steel substrate

摘要

The influence of praseodymium (Ⅲ) oxide (Pr_2O_3) on the corrosion resistance and adhesion properties of an epoxy-polyamide coating on steel substrate M.Ramezanzadeh, Z.Sanaei, B.Ramezanzadeh Surface Coating and Corrosion Department, Institute for Color Science and Technology, Tehran, Iran. *Corresponding author: E-mail:; Fax: +98 2122947537; Tel: +98 2122969771 Surface treatment of steel substrates by chemical conversion coatings is a promising and effective approach to enhance the corrosion resistance and interfacial adhesion properties of the polymeric coatings. Chromates and phosphates are the most popular types of conversion coatings that have been largely used for this purpose. However, due to the toxic nature of these chemicals and environmental regulations the use of these coatings has been strongly restricted. So in the recent years the researchers' attention have been directed toward developing the environmentally friendly alternatives for the chromates and phosphates. Among various conversion coatings the coatings based on rare earth elements are largely considered. So in this study we have attempted to develop a new type of conversion coating based on Pr2O_3 on the steel substrate. The surface morphology and chemistry of the steel specimen modified with Pr_2O_3 was evaluated by atomic force microscopy and contact angle measurements. Then the influence of Pr_2O_3 film deposition on steel surface on the interfacial adhesion and corrosion resistance of an epoxy-polyamide coating was studied by pull-off adhesion test and electrochemical impedance spectroscopy (EIS). Results revealed that surface treatment by Pr_2O_3 increased the surface roughness and surface free energy. The adhesion and corrosion protection properties of the epoxy coating were noticeably improved after deposition of Pr_2O_3 on the steel substrate.