镁合金表面缓蚀剂插层LDHs涂层自愈合性能的研究

Self-Healing Properties of Corrosion Inhibitor Intercalated LDHs Film on Magnesium Alloy Surface

通过水热法在AZ31镁合金表面原位合成层状双氢氧化物(LDHs)膜MgAl-LDHs-NO3,采用阴离子交换反应将钨酸根阴离子(WO42-)和半胱氨酸(Cys)阴离子嵌入LDHs层间,制得MgAl-LDHs-WO4和MgAl-LDHs-Cys。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)、电化学阻抗测试(EIS)研究了膜层的形貌、结构、耐蚀性和自愈合性能。结果表明,在3.5%(质量分数)NaCl溶液中3种膜层的耐蚀性由强到弱依次为LDHs-WO4>LDHs-Cys>LDHs-NO3。预制划痕后在3.5%NaCl溶液中浸泡,实验结果表明,3种膜层均表现出良好的自愈合能力,电化学结果显示浸泡8 d时耐蚀性最佳,随后呈下降趋势,且LDHs-WO4和LDHs-Cys自愈合能力明显优于LDHs-NO3。这是由于LDHs-WO4和LDHs-Cys含有缓蚀性阴离子,膜层不仅阻隔溶液对基体的腐蚀,而且LDHs的层间结构还可以释放缓蚀性离子,这些离子与镁结合形成难溶沉淀,促进膜层的自愈合过程。

A layered double hydroxide(LDH)film layer MgAl-LDHs-NO3 was synthesized by hydrothermal method.Tungstate anions(WO42-)and cysteine(Cys)anions were intercalated into the LDHs interlayer through anion exchange reaction to acquire MgAl-LDHs-WO4 and MgAl-LDHs-Cys films,respectively.X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and electrochemical impedance test(EIS)were used to study the morphology,structure,corrosion resistance and self-healing performance of these films.The results show that the corrosion resistance of the three films is in the sequenc e of LDHs-WO4>LDHs-Cys>LDHs-NO3.All of the three films have effective self-healing ability.Electrochemical results indicate that the films with scratch treatment have the optimum corrosion resistance after immersing in 3.5 wt%NaCl solution for 8 d,and th en their corrosion resistance shows a downward trend.Compared to LDHs-NO3,LDHs-WO4 and LDHs-Cys containing corrosion inhibiting anions,display better self-healing ability,because the films can not only capture Cl-,but also release corrosion-inhibiting anions.