Corrosion protection investigations of oxide‐silane composite coating on hot dip aluminized steel

Abstract The hot dip aluminized ASTM 1035 steels (Al‐coated steel) underwent anodic oxidization, and various thicknesses of Al 2 O 3 coating were applied to the surface of the Al‐coated steels (Al–Al 2 O 3 ‐coated steel). The corrosion resistance of the Al–Al 2 O 3 ‐coated steel was investigated using potentiodynamic tests, electrochemical impedance spectroscopy tests and measurement of galvanic current density in a bimetallic cell. It was found that the anodic oxidation resulted in the formation of a porous Al 2 O 3 coating on the surface of the Al‐coated steel, improving both its corrosion resistance and galvanic corrosion resistance when coupled with carbon fiber reinforced nylon 6 composite (C f /PA6). Silane treatment effectively sealed the pores within the Al 2 O 3 coating, resulting in improved corrosion protection for Al–Al 2 O 3 ‐coated steel due to the exceptional insulation, impermeability and hydrophobic properties of silane coating. Compared to the Al‐coated steel/carbon fiber reinforced polymer (CFRP) couple and Al–Al 2 O 3 ‐coated steel/CFRP couple, stable galvanic current density decreased by approximately 75% and 45%, respectively.