物理化学学报 >> 2009, Vol. 25 >> Issue (09): 1743-1748.doi: 10.3866/PKU.WHXB20090821

研究论文 上一篇    下一篇

钼酸盐封闭后处理的热镀锌钢板硅烷膜的耐蚀性

吴海江, 卢锦堂   

  1. 湖南科技大学先进材料制备与应用技术研究所, 湖南 湘潭 411201|华南理工大学材料科学与工程学院, 广州 510641
  • 收稿日期:2009-04-01 修回日期:2009-05-15 发布日期:2009-09-03
  • 通讯作者: 吴海江 E-mail:haijiang_wu@126.com

Corrosion Resistance of Silane Films on Hot-Dip Galvanized Steel by Molybdate Post-Sealing

WU Hai-Jiang, LU Jin-Tang   

  1. Advanced Materials Synthesis and Application Technology Laboratory, Hunan University of Science and Technology, Xiangtan 411201, Hunan Province, P. R. China|College of Material Science and Engineering, South China University of Technology, Guangzhou 510641, P. R. China
  • Received:2009-04-01 Revised:2009-05-15 Published:2009-09-03
  • Contact: WU Hai-Jiang E-mail:haijiang_wu@126.com

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摘要：

为进一步增强硅烷膜的耐蚀性, 将硅烷化热镀锌钢板用钼酸盐溶液进行封闭后处理, 并采用扫描电子显微镜(SEM)、中性盐雾(NSS)实验、盐水全浸实验和电化学技术研究了所得复合膜层的表面形貌和耐蚀性能. 结果表明: 经钼酸盐溶液封闭处理后, 硅烷膜的孔隙被填充, 在锌层表面形成了由硅烷膜和钼酸盐转化膜构成的连续完整致密的复合膜; 复合膜的耐蚀性能明显提高, 且与钼酸盐溶液的封闭时间有关, 封闭60 s时所形成的复合膜的耐蚀性最佳. 在5%(w, 质量分数)NaCl溶液中的电化学测量结果表明: 硅烷化热镀锌钢板经钼酸盐溶液封闭处理后, 同时抑制了腐蚀过程中的阳极和阴极反应, 但主要是抑制阴极反应, 导致腐蚀电流密度明显减小, 发挥了单一硅烷膜和单一钼酸盐转化膜腐蚀防护的协同效应, 腐蚀防护效率高达99.1%; 随浸泡时间延长, 试样低频扩散阻抗先增大后减小, 表明膜层具有一定的“自愈”能力, 其耐蚀性优于常规铬酸盐钝化膜.

关键词: 耐蚀性, 热镀锌钢, 硅烷膜, 钼酸盐

Abstract:

To improve the corrosion resistance of silane films further, silanized hot-dip galvanized (HDG) steel was post-sealed with molybdate solution. The surface morphology and corrosion resistance of the composite films were investigated by scanning electron microscopy (SEM), a neutral salt spray (NSS) test, a salt water test, and electrochemical measurements. Results showed that pores in the silane films were filled after post-sealing the silanized HDG steel with molybdate solution. This was accompanied by the formation of a continuous, complete, and compact composite film that was composed of a silane film and a molybdate conversion film on the surface of the HDG steel. The composite coatings have much better corrosion resistance than a single silane film and this is related to the sealing time.  Silanized HDG steel that underwent post-sealing for 60 s in molybdate solution showed the best corrosion resistance. Results of the electrochemical measurements in 5%(w, mass fraction) NaCl solution reveal that both the anodic and cathodic processes of zinc corrosion on the samples are conspicuously suppressed resulting in a large decrease in corrosion current density. A synergistic protection effect for the single silane film and the single molybdate conversion film is evident. The corrosion protection efficiency value was as much as 99.1%. Furthermore, the low frequency inductive loop usually observed in electrochemical impedance spectroscopy (EIS) disappeared and the low frequency impedance values for the composite films initially increased and then decreased with increasing immersion time. This indicates self-healing activity for the composite films. The corrosion resistance of these composite films is superior to some chromate passivation films.

Key words: Corrosion resistance, Hot-dip galvanized steel, Silane film, Molybdate