The role of neodymium based thin film on the epoxy/steel interfacial adhesion and corrosion protection promotion

The main aim of this study is to investigate the impact of the steel substrate Nd-based chemical modification on the corrosion protection performance, cathodic delamination and adhesion properties of epoxy coating. The morphology, chemical composition, topography and chemistry of the treated samples were studied by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurement. The treated samples and also the epoxy coated samples corrosion resistance was examined through electrochemical impedance spectroscopy (EIS). The impact of mild steel surface modification on the epoxy coating protection efficiency, adhesion strength and cathodic disbondment (CD) resistance was surveyed by salt spray, Pull-off and CD tests. Results showed the deposition of Nd oxide/hydroxide, a surface with lower surface free energy and higher roughness compared to the untreated sample. Chemical treatment by Nd-based film remarkably improved the epoxy coating corrosion protection properties, increased the adhesion strength through chemical and hydrogen bonds, and led to an excellent CD resistance.