Stannate conversion coatings on Mg–8Li alloy

The stannate conversion coatings (SnCC) on Mg–8Li alloy were investigated by simple immersion method. The surface morphology and composition were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD) techniques. The corrosion resistance was assessed by means of potentiodynamic polarization measurements and electrochemical impedance spectra (EIS). The effects of time of a stannate bath on the quality of stannate conversion coatings were investigated by SEM and EIS. It was found that the coating particles were mainly composed of hemispherical particles MgSnO3·3H2O. A comparison of results revealed the coating treated for 60 min exhibited the most uniform, dense and corrosion-resistant.