Enhanced corrosion resistance of MgAl hydrotalcite conversion coating on aluminum by chemical conversion treatment

The effects of the chemical conversion treatment in 8-hydroxyquinolate salt on the structure and corrosion resistance of MgAl hydrotalcite conversion coating on aluminum substrate have been investigated by Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical measurements. The results show that the microstructure of MgAl hydrotalcite coating is preserved, while the corrosion resistance of Al substrate is effectively enhanced after the chemical conversion treatment. The chemical conversion treatment results in the intercalation of 8-hydroxyquinolate anions into the coating, which induces the further decrease of corrosion current density of not converted sample by one order of magnitude after immersion in 3.5 wt.% NaCl solution. It provides a facile way to prepare environmentally friendly conversion coating for corrosion protection of light metal and alloys.