Journal of South China University of Technology (Natural Science Edition) ›› 2007, Vol. 35 ›› Issue (5): 104-108.

• Chemistry & Chemical Engineering • Previous Articles     Next Articles

Performance of Trivalent and Hexavalent Chromium Passivation Films Based on Zinc Plating

Zeng Zhen-ou1  Zou lin-guang1  Zhao Guo-peng2  Liu lian-ping2   

  1. 1. School of Chemical Science , South China Univ. of Tech. , Guangzhou 510640 , Guangdong , China;2. Guangzhou Etsing Plating Research Institute , Guangzhou 510170 , Guangdong , China)
  • Received:2006-06-05 Online:2007-05-25 Published:2007-05-25
  • Contact: 曾振欧(1955-)，男，教授，主要从事应用电化学和表面处理方面的研究. E-mail:zhouzeng@scut.edu.cn
  • About author:曾振欧(1955-)，男，教授，主要从事应用电化学和表面处理方面的研究.

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Abstract:

In order to replace the hexavalent chromium in passivation solution with trivalent chromium and achieve pollution-free production for zinc plating , the cOITosion resistances , electrochemical behaviors , heat-resistant abilities and microstructures of trivalent and hexavalent chromium passivation films were studied via neutral salt spray (NSS) test , Tafel plot curves and SEM. The results of NSS test show that trivalent chromium passivation film can
pass 84 h of NSS test and possesses better cOITosion resistance than the hexavalent one. The Tafel plot curves indicate that trivalent chromium passiva.tion film is of a lower cOITosion rate but a higher heat-resistant ability than the hexavalent one. Moreover , the SEM micrographs show that trivalent chromium passivation film is compact even after heat treatment , while the microstructure of hexavalent chromium passivation film is loose reticular.

Key words: zinc plating, trivalent chromium, hexavalent chromium, passivation