Ce元素对低碳钢热浸镀锌镀层耐蚀性的影响  

Effects of Ce on corrosion resistance of hot-dip galvanized coating on mild steel

作　　者：徐文灿 范洪强 赵天亮 张志宏 刘玉宝 李谦[2,3,4] XU Wen-can;FAN Hong-qiang;ZHAO Tian-liang;ZHANG Zhi-hong;LIU Yu-bao;LI Qian(State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization,Baotou 014030,China;School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;State Key Laboratory of Advanced Special Steels,Shanghai University,Shanghai 200444,China;Materials Genome Institute,Shanghai University,Shanghai 200444,China)

机构地区：[1]白云鄂博稀土资源研究与综合利用国家重点实验室,包头014030 [2]上海大学材料科学与工程学院,上海200444 [3]上海大学省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444 [4]上海大学材料基因组工程研究院,上海200444

出　　处：《中国有色金属学报》2020年第6期1377-1388,共12页The Chinese Journal of Nonferrous Metals

基　　金：白云鄂博稀土资源研究与综合利用国家重点实验室开放课题(2018Z2001)。

摘　　要：采用热浸镀法在低碳钢表面制备含Ce元素的镀锌层,利用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪(XRD)、中性盐雾试验(NSS)以及电化学测试方法,揭示不同Ce元素添加量对镀层微观组织结构及耐蚀性能的影响规律。结果表明:在镀液中添加适量的Ce元素可在细化镀锌层晶粒和减薄镀锌层厚度的同时有效地提高镀锌层的耐蚀性。与纯锌镀层相比,镀液中添加0.012%和0.2%Ce(质量分数)后镀层的腐蚀速率分别降低24%和27%。Ce元素提高镀锌层耐蚀性的机理为:一方面,Ce的添加提高了腐蚀产物中Zn5(OH)8Cl2∙H2O占比,从而提高了腐蚀产物的致密性与粘附性;另一方面,腐蚀过程所形成的Ce(OH)3沉淀吸附在阴极相,阻碍氧的扩散,抑制了阴极吸氧反应。当镀液中添加超过0.012%Ce后(过饱和),阴极反应已被充分抑制,因而继续提高Ce添加量对镀锌层耐蚀性的提高有限。Zinc coatings containing rare earth element Ce were prepared on a mild steel surface by hot dipping,the effects of Ce on the microstructure and corrosion resistance of galvanized coating were studied by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffractometry(XRD),neutral salt spray(NSS)test and electrochemical methods.The results show that the addition of Ce in the hot dipping liquid increases the corrosion resistance of the coating considerably while refining the grain size and reducing the thickness.Compared with the pure zinc coating,the coatings prepared with hot dipping liquids with 0.012%and 0.2%(mass fraction)Ce added are reduced by 27%and 23%in thickness and 24%and 27%in corrosion rate,respectively.The enhancement of corrosion resistance by Ce addition comes from two ways,one is that the addition of Ce increases the proportion of Zn5(OH)8Cl2∙H2O,which can improve the compactness and adhesiveness of the corrosion product.The other is that the formed Ce(OH)3 deposited on the cathodic phase impedes the diffusion of oxygen,thereby inhibiting the cathodic reaction.The enhancement reaches the limit since the cathodic reaction has been fully inhibited when the Ce content in hot dipping liquid exceeds 0.012%(supersaturation).

关 键 词：热浸镀 稀土元素 镀锌层 耐蚀性 电化学行为 

分 类 号：TG147[一般工业技术—材料科学与工程]