循环盐雾环境中电镀锌和锌铝涂覆涂层的腐蚀行为

Corrosion Behavior of Electrogalvanizied Coating and Zinc-Aluminum Coating in Cyclic Salt Spray Environment

将电镀锌涂层和锌铝涂覆涂层制备在冷轧板基体上,进行了42 d循环盐雾试验,通过扫描电镜(SEM)、XRD分析和电化学测试考察了其经过不同时间循环盐雾试验后的腐蚀形貌、腐蚀产物组成和电化学行为。结果表明:锌铝涂覆涂层的耐蚀性强于电镀锌涂层,经过28 d循环盐雾试验后电镀锌涂层已完全失效,而锌铝涂覆涂层经过42 d试验后仍未失效;在循环盐雾试验环境中,二者共同的腐蚀产物有ZnO,Zn_(5)(CO_(3))_(2)(OH)_(6)、Zn_(5)(OH)_(8)Cl_(2)·H_(2)O和Fe_(3)O_(4),电镀锌涂层的腐蚀产物中还有Zn_(4)CO_(3)(OH)_(6)和FeOOH,而锌铝涂覆涂层的腐蚀产物中含有具有保护作用的Al_(2)O_(3)。

Electro-galvanized coating and zinc-aluminum coating were prepared on the cold-rolled plate substrate, and a 42 d cyclic salt spray test was carried out. Scanning electron microscopy(SEM), XRD analysis and electrochemical tests were used to investigate the corrosion morphology, corrosion product composition and electrochemical behaviors of these coating samples after different periods of time of cyclic salt spray test. The results showed that the corrosion resistance of the zinc-aluminum coating was stronger than that of the electro-galvanized coating, and the electro-galvanized coating completely failed after 28 d cyclic salt spray test, and the zinc-aluminum coating did not fail after 42 d test. In the cyclic salt spray test environment, the common corrosion products of the two samples were ZnO,Zn_(5)(CO_(3))_(2)(OH)_(6),Zn_(5)(OH)_(8)Cl_(2)·H_(2)O and Fe_(3)O_(4). The corrosion products of galvanized coating also contained Zn_(4)CO_(3)(OH)_(6)and FeOOH, while the corrosion products of zinc-aluminum coating contained protective Al_(2)O_(3).