Abstract:A dark gray, uniform and better corrosion resistant Zn-Mn based conversion coating on the Mg-Li alloy was prepared using the phosphate baths. The temperature of phosphate solution was discussed in this experiment. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition and crystal structure were analyzed by X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The corrosion resistance of Mg-Li alloy and phosphate conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and a mass loss method. The results show that the Zn-Mn phosphate conversion coating is composed of Zn, Zn3(PO4)2, MnHPO4 and Mn3(PO4)2. The corrosion resistance of permanganate conversion coatings is improved greatly compared with that of Mg-Li alloy. When the temperature of phosphate solution is 45 oC, the phosphate conversion coating exhibits the smallest corrosion current density, the highest capacitance arc and minimum corrosion rate, so the conversion coating presents the best corrosion resistance behavior