Protection of aluminium foil AA8021 by molybdate-based conversion coatings

摘要

A quick method for surface treatment of aluminium foil with environment-friendly and effective molybdate-based coating was developed in this study. Aluminium foil samples were treated with molybdate-based solution. The microstructure and composition of the resulting molybdate-based conversion coatings were explored by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectric spectroscopy (XPS). We found that the molybdate-based conversion coating was composed mainly of MoO_3,(MoO_3)_x(P_2O_5)_y, and Al_2(MoO_4)_3 compounds. Furthermore, corrosion resistance of the treated aluminium foil was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Our results show that all of the aluminium foils with molybdate-based conversion coatings have much better corrosion resistance than bare aluminium foil. Notably, the sample treated at 40 ℃ exhibited the best corrosion resistance. The new method is very suitable for continuous processing.