The role of chrome and zinc free-based neodymium oxide nanofilm on adhesion and corrosion protection properties of polyester/melamine coating on mild steel: Experimental and molecular dynamics simulation study

This study introduces a novel environmentally friendly chemical conversion coating based on neodymium (Nd) oxide for mild steel surface treatment. The Nd-based nanofilm impact on the polyester/melamine coating adhesion to metal surface and corrosion protection properties was examined. The Nd film composition and morphology were analyzed by XPS, AFM, SEM, and contact angle measurements. The uniform deposition of Nd-oxide/hydroxide compounds on steel surface was proved by surface characteristic analyses. Pull-off adhesion test results evidenced the wet adhesion bonding strength improvement of coating on steel treated by Nd-oxides/hydroxide compounds. Furthermore, the coating delamination rate remarkably decreased in the presence of Nd film. The significant effect of Nd film on the anti-corrosion properties of steel/coating system was demonstrated by accelerated salt spray corrosion test and electrochemical impedance spectroscopy test results. Additionally, molecular dynamics simulation results clarified the stronger coating molecules adsorption to neodymium oxide substrates as compared with iron oxides. (C) 2018 Elsevier Ltd. All rights reserved.