Effect of Additives on Structure and Corrosion Resistance of Molybdate Conversion Coatings Deposited on AZ31B Mg Alloy

Abstract:

Molybdate conversion coatings were prepared on AZ31B Mg alloy in a molybdate based solution with additives of sodium fluoride (NaF) or lanthanum nitrate (La(NO3)3). The effects of F- and La3+ additives on the morphology and on the corrosion resistance of the molybdate coatings were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and potentiodynamic polarization analysis. The results revealed that these additives could accelerate the deposition of molybdenum on the surface of AZ31B magnesium alloy. It can be seen that the composite conversion coatings consist of many spherical particles. It is also found that the corrosion resistance is greatly improved after molybdate treatment. The films formed in F- additive solution showed lower corrosion current density than in La3+ additive solution.

• Periodical: Advanced Materials Research (Volumes 308-310)
• Pages: 2458-2462
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.308-310.2458
• Online since: August 2011
• Authors: Li Hui Yang, Mi Lin Zhang, Cun Guo Lin, Jian Hua Wu
• Keywords: Additive, Conversion Coating, Corrosion Resistance, Magnesium Alloy, Molybdate

References

[1] J. E. Gray, B. Luan, J. Alloy. Comp. 336 (2002) 88-113.

[2] B. L. Mordike, T. Ebert, Mater. Sci. Eng. A 302 (2001) 37-45.

[3] G. L. Song, A. Atrens, M. Dargusch, Corros. Sci. 41 (1998) 249-273.

[4] S. Mathieu, C. Rapin, J. Hazan, P. Steinmetz, Corros. Sci. 44 (2002) 2737-2756.

[5] M. Dabalà, K. Brunelli, E. Napolitani, M. Magrini, Surf. Coat. Technol. 172 (2003) 227–232.

[6] L. Anicai, R. Masi, M. Santamaria, F. Di Quarto, Corros. Sci.47 (2005) 2883- 2900.

DOI: 10.1016/j.corsci.2005.05.033

[7] P. B. Srinivasan, C. Blawert,W. Dietzel, Mater. Sci. Eng. A 494 (2008) 401–406.

[8] W. Shang, B. Z. Chen, X. C. Shi, Y. Chen, X. Xiao, J. Alloy. Comp. 474 (2009) 541-545.

[9] L. P. Wu, J. J. Zhao, Y. P. Xie, Z. D. Yang, Trans. Nonferrous Met. Soc. China, 20 (2010) s630-s637.

[10] Y. R. Gao, C. M. Liu, S. L. Fu, J. Jin, X. Shu, Y. H. Gao, Surf. Coat. Technol. 204 (2010) 3629-3635.

[11] V. Barranco, N. Carmona, J. C. Galván, M. Grobelny, L. Kwiatkowski, M. A. Villegas, Prog. Org. Coat., 68 (2010) 347-355.

[12] W. B. Ding, H. Y. Jiang, X. Q. Zeng, D. H. Li, S. S. Yao, J. Alloy. Comp. 429 (2007) 233-241.

[13] D. R. Gabe, S. E. Gould, Surf. Coat. Technol. 35 (1988) 79-91.

[14] A. A. O. Magalhães, I. C. P.Margarit, O. R. Mattos, J. Electroanal. Chem. 572 (2004) 433-440.

[15] C.G. da Silva, I.C.P. Margarit-Mattos, O.R. Mattos, H. Perrot, B. Tribollet, V. Vivier, Corros. Sci. 51 (2009) 151-158.

DOI: 10.1016/j.corsci.2008.10.019

[16] J. Y. Hu, Q. Li, X. K. Zhong, L. Zhang, B. Chen. Prog. Org. Coat. 66 (2009) 199-205.

[17] Z. Y. Yong, J. Zhu, C. Qiu, Y. L. Liu, Appl. Surf. Sci. 255 (2008) 1672-1680.

[18] K.Z. Chong, T.S. Shih, Mater. Chem. Phys. 80 (2003) 191–200.

[19] E. Almeida, T. C. Diamantino, M. O. Figueiredo, C. Sá, Surf. Coat. Technol. 106 (1998) 8–17.

[20] C.D. Gu, J. S. Lian, J. G. He, Z. H. Jiang, Surf. Coat. Technol. 200 (2006) 5413- 5418.