摘要
通过在Ce(NO_3)_3水溶液中对锌和电镀锌钢进行化学转化(钝化)处理,在试样表面形成了铈转化膜。利用电子探针显微分析(EPMA)、X射线光电子能谱(XPS)和X射线衍射(XRD)等研究了转化膜的形貌、成分和结构,探讨了锌表面铈转化膜的形成机理。在氯化钠溶液中测定了试样的腐蚀率、极化曲线和电化学交流阻抗谱(EIS)等腐蚀性能参量,并与未钝化和普通铬酸盐钝化试样的情况作了对比。结果表明,本实验得到的锌表面稀土转化膜主要是由CeO_2、Ce_2O_3和ZnO组成的复合氧化物膜,铈转化膜的存在阻碍了锌在电化学腐蚀过程中的阴极反应和阳极反应,导致电荷传递电阻增大,腐蚀率降低。在一定条件下,铈转化膜对锌和镀锌钢的肪蚀效果优于铬酸盐转化膜。
A cerium conversion coating was prepared on zinc and galvanized steel by chemical conversion treatment of specimens in an aqueous solution of 0. 005 mol / L Ce(NO3)3. The surface morphology, chemical composition and structure of the coatings were analyzed by means of the electron microprobe, X-ray photoelectron spectroscopy and X-ray diffraction. The mechanisms involved in the formation of the coatings are discussed. The corrosion rate, polarization curve and electrochemical impedance spectroscopy of the specimens, untreated and treated with the cerium salt and the chromate, were measured in sodium chloride aqueous solution. It was found that the cerium conversion coating formed on zinc mainly consists of composite oxides of CeO2,Ce?O3 and ZnO, which can effectively retard both the cathodic and the anodic reaction of the corrosion of zinc, leading to a higher charge transfer resistance and a lower corrosion rate. The cerium conversion coating, which was prepared properly, would provide a better protection a-gainst corrosion for zinc and galvanized steel than the chromate conversion coating did-
出处
《稀土》
EI
CAS
CSCD
北大核心
2003年第5期52-56,共5页
Chinese Rare Earths
基金
云南省自然科学资助项目(98E042M)
关键词
稀土转化膜
锌
镀锌钢
无铬钝化
耐蚀性
rare earth metal conversion coating
zinc
galvanized steel
chromate - free passivation
corrosion protection
