Effects of graphene oxide-filled sol-gel sealing on the corrosion resistance and paint adhesion of anodized aluminum

Anodic aluminum oxide (AAO) film was sealed by graphene oxide-filled sol-gel (GO/sol-gel) and effects of sealing on corrosion resistance and paint adhesion of the film were studied. Samples sealed by boiling water and sol-gel were used for comparison. Cross-sectional analysis of samples was conducted by glow discharge optical emission spectrometry (GDOES) and energy dispersive spectrometer (EDS). Paint adhesion measurement was examined by pull-off test and corrosion resistance property was tested by electrochemical impedance spectroscopy (EIS) and salt spray test. For four kinds of films, unsealed AAO film exhibited a porous structure with poorest corrosion resistance. After the film was sealed by GO/sol-gel, the pores were not only filled, but also a thin and uniform GO/sol-gel film about 1 mu m was formed on the surface of the samples. And GO/sol-gel sealed samples presented better corrosion resistance, which had the least pitting sites after 720 h of salt spray. While sol-gel sealed samples possessed better paint adhesion strength values which were up to 18.4 MPa.