Effect of Electrical Parameters on the Microstructure and Corrosion Resistance of Anodized Film of Mg-1Zn-1Gd Alloy Based on Orthogonal Experiment Method

Mg-rare earth (RE) alloy, i.e. , Mg-1Zn-1Gd (ZG11), was treated by a conventional pulse anodization process. The effect of electrical parameters (processing time, duty cycle and applied current) on the microstructure and corrosion resistance of anodized film was investigated by orthogonal method. SEM and XRD were used to characterize the microstructures and compositions of anodized films. Polarization curve, electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) were performed to evaluate the corrosion resistances of anodized samples. The results show that with the employment of appropriate electrical parameters, corrosion resistance of ZG11 alloy can be significantly enhanced ( i corr decreases by nearly three orders of magnitude) after anodized for less than 2 min. Besides, the optimal sample selected from orthogonal experiments in terms of the thickness and porosity of anodized film appropriately matches with the sample with the best corrosion resistance determined by electrochemical corrosion measurements, indicating the strong relationship between the thickness and porosity of anodized film and its corrosion resistance. Additionally, results of cell proliferation tests demonstrate that the varied surface morphologies and microstructure characteristics of the anodized samples in the present study do not necessarily influence the related cytocompatibilities. The study helps to further understand the effect orders of different current parameters on the structure and properties of anodized film and therefore provides a high-efficiency and low-energy consumption way to manufacture Mg alloys with excellent corrosion resistances.