Investigation of corrosion resistance of films prepared on magnesium alloy surfaces under various anodizing conditions
摘要
Enhancing the corrosion resistance of AZ31B magnesium alloy is pivotal for its expanded application in various engineering sectors. This study investigates the effects of anodizing voltage (ranging from 10 to 20 V) and treatment duration (1–5 min) on the formation and performance of MgO protective films on AZ31B surfaces. Via constant‐voltage anodizing, 5–25 µm‐thick oxide layers were prepared. Results show that increasing voltage up to 17.5 V promotes film densification, thickness, adhesion, and hardness. However, voltages exceeding 17.5 V lead to a decline in these properties due to the onset of film peeling and structural defects. Optimal anodizing conditions were identified at 17.5 V for 3 min, yielding a film thickness of 19.5 µm, an adhesion strength of 8.86 N, a hardness of 133.3 HV, and a corrosion current density of 4.43 × 10⁻5 A/cm2. Additionally, the hydrogen evolution rate stabilized at approximately 1 mL·cm⁻2·d⁻1 under these optimal conditions. X-ray diffraction (XRD) confirmed that the film comprised MgO and Mg₂SiO₄ phases. Electrochemical impedance spectroscopy (EIS) further validated the superior protective performance of the optimized oxide layer. These findings underscore the importance of precise control over anodizing parameters to develop robust coatings, thereby extending the service life and applicability of AZ31B magnesium alloys in corrosive environments.