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采用Mn2+/HCO-3水溶液为处理液,在AZ91D镁合金表面上制得了Mg6Al2(OH)16CO3·4H2O/MnCO3复合膜。通过扫描电镜(SEM)和X射线衍射(XRD)分析了膜层的表面形貌和成分,利用极化曲线和交流阻抗(EIS)、浸泡试验来评价该转化膜的耐蚀性。结果表明,NaOH溶液的滴加能有效促进碳酸锰的沉积,随着滴加速度的降低,膜层的沉积量逐渐增大,当滴加速度为每隔3 min滴加1 mL时,膜层最为均匀、完整,耐蚀性明显优于镁合金基体,试样的腐蚀速度为9.8×10-5A·cm-2,约为镁合金基体的1/30。
Using Mn2 + / HCO3 aqueous solution as the treatment solution, a composite film of Mg6Al2 (OH) 16CO3 · 4H2O / MnCO3 was prepared on the surface of AZ91D magnesium alloy. The surface morphology and composition of the film were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the film was evaluated by polarization curve and electrochemical impedance spectroscopy (EIS) and immersion test. The results show that the dropping of NaOH solution can effectively promote the deposition of manganese carbonate. With the decrease of the dropping rate, the deposition of the film gradually increases. When the dropping rate is 1 mL every 3 min, the film is the most uniform , Complete corrosion resistance is better than the magnesium alloy substrate, the sample corrosion rate of 9.8 × 10-5A · cm-2, about 1/30 of the magnesium alloy substrate.