Effect of Na₂SiO₃ Concentration on Microstructure and Properties of Micro-arc Oxidation Film on Al-Li Alloy

The oxidation film was prepared on the surface of as-cast Al-Li alloy by micro-arc oxidation.The effects of Na₂SiO₃ concentration (0.05 mol/L, 0.07 mol/L, 0.09 mol/L)on the microstructure and properties of micro-arc oxidation film on Al-Li alloy were analyzed by scanning electron microscope (SEM), X-ray diffractometer (XRD), microhardness test and friction test.The results show that the oxidation films are composed of dense layer near the substrate and outer loose layer, which are mainly composed of α-Al₂O₃ phase and γ-Al₂O₃ phase. With the increase of sodium silicate concentration, the number of micropores on the film increases, and the film thickness and Al₂O₃ content increase at first and then decrease.When the concentration of sodium silicate is 0.07 mol/L, the hardness and coefficient of the film are 1171 HV and 0.49, respectively, and the wear resistance of the film is best.