改性环氧树脂无铬达克罗涂层的制备及其性能

Preparation and Property of Modified Epoxy Resin Chrome-free Docromet Coating

实施了用聚氨酯改性环氧树脂替代铬酐制备无铬达克罗涂层的工艺,运用扫描电子显微镜(SEM)和X射线衍射(XRD)手段分析了所制备涂层的形貌和成分,通过动电位极化曲线,电化学阻抗(EIS),耐硝酸铵快速腐蚀试验,盐水浸泡试验等方法对涂层的耐蚀性进行了评价和研究。结果表明:树脂固化交联形成致密、均一、连续的膜层,有效阻止腐蚀介质的侵入,提高了涂层的耐蚀性;涂层主要成分为Zn和Al,当腐蚀介质侵入时,锌铝粉钝化生成氧化物,其防腐蚀机理主要是屏蔽作用、电化学作用及钝化作用。

The technology of preparing a chrome-free Dacromet coating with polyurethane modified epoxy resin instead of chromic anhydride was performed. The morphology and composition of the prepared coating were analysed by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The corrosion resistance of the coating was evaluated by potentiodynamic polarization curve, electrochemical impedance spectroscopy （EIS）, ammonium nitrate fast corrosion resistance test and salt water immersion test. The results showed that a dense, uniform and continuous film was formed through curing and cross-linking of resin, which effectively prevented the invasion of corrosive media and improved the corrosion resistance of the coating. The main components of the coating were Zn and A1, when the corrosive medium invaded, the zinc-aluminum powder was passivated to form oxide. The corrosion protection mechanism was mainly the shielding effect, electrochemical action and passivation effect.