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采用超声辅助工艺在AZ91D镁合金表面制得了镁铝水滑石(Mg6Al2(OH)16CO3·4H2O)转化膜,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)来评价该转化膜对镁合金的防护作用,研究了超声波对膜层质量的影响规律。结果表明,超声辅助处理工艺能够有效地缩短成膜时间,但长时间处理会使膜层出现局部破裂。超声辅助酸碱浸泡2 h试样(US1+1 h)表面形成了较为连续、致密的水滑石膜,该膜层能明显提高镁基体的自腐蚀电位,并减小其腐蚀电流密度,腐蚀速度约为镁基体的1/20。
The hydrotalcite (Mg6Al2 (OH) 16CO3 · 4H2O) conversion coating was prepared on the surface of AZ91D magnesium alloy by ultrasonic assisted technique. The surface morphology and composition of the coating were analyzed by scanning electron microscopy (SEM) and X-ray diffraction , The polarization curve and AC impedance (EIS) were used to evaluate the protective effect of the conversion coating on the magnesium alloy. The influence of ultrasonic on the film quality was studied. The results show that the ultrasonic assisted processing technology can effectively shorten the filming time, but prolonged treatment will make the film appear partial rupture. Ultrasonic-assisted acid-base immersion 2h sample (US1 +1 h) surface formed a more continuous, dense hydrotalcite film, the film can significantly improve the self-corrosion potential of the magnesium matrix, and reduce the corrosion current density, corrosion rate About 1/20 of the magnesium matrix.