Preparation and Corrosion Behavior of Environment Friendly Conversion Coating Formed on Zn-5%Al Galvanized Steel

Abstract:

A non-chromate conversion coating was prepared from molybdate based bath on the surface of Zn-5%Al hot dip galvanized steel. The influence of the preparation conditions such as temperature, bath pH and treating time on the corrosion resistance of the obtained conversion coating was investigated. The corrosion performance of the film was researched using electrochemical technique in 3.5%NaCl. The results indicate that the anodic branch of the polarization curves present in passivation character. Electrochemical impedance spectroscopy (EIS) illustrate that the radius of the capacity impedance for conversion coating varies distinctly according to the preparation condition. The surface morphology was observed using scanning electron microscopy (SEM), and the results show that the surface of Zn-5%Al hot dip galvanized steel present in eutectic feature after conversion coating treatment. The chemical composition of the coating was detected by energy dispersive X-ray (EDX), and the results illustrate that the conversion coating is composed of Zn, Al , O, P and Mo.

• Periodical: Advanced Materials Research (Volume 773)
• Pages: 429-434
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.773.429
• Online since: September 2013
• Authors: Wan Qiu Zhou, Jian Wang, Li Sheng, Yan Hong Kang, Shi Gang Xin, Shi Wei Wu
• Keywords: Corrosion Resistance, Hot Dip Galvanized Steel, Non-Chromate Conversion Coating

References

[1] M.A. Dominguez-Crespo, E. Onofre-Bustamante, A. M. Torres-Huerta, F. J. Rodriguez-Gomez: J. Mex. Chem. Soc. Vol52(2008), p.235.

[2] R. Berger, U. Bexell, T. M. Grehk, S.E. Hornstrom: Surface & Coatings Technology Vol. 202 (2007), p.391.

[3] Y. Hamlaoui, C. Remazeilles, M. Bordes, L. Tifouti, F. Pedraza: Corr. Sci. Vol. 52( 2010), p.1020.

[4] K.W. Cho, V. S. Rao, H.S. Kwon: Electrochimica Acta Vol. 52( 2007), p.4449.

[5] F. Defloriana, S. Rossia, L. Fedrizzib, P.L. Bonora: Progress in Organic CoatingsVol. 52(2005), p.271.

[6] Y.K. Song, F. Mansfeld: Corrosion science section Vol. 62 (2006), p.1067.

[7] A. A. Magalhaes, I. C. Margarit, O. R. Mattos: J. of Electroanalytical Chem. Vol. 572 ( 2004), p.433.

[8] J.T. Lu, G. Kong, J.H. Chen: Tansactions of Nonferrous Metals Society of ChinaVol. 13( 2003), p.145.