Evaluation of anticorrosion behavior of automotive electrocoating primers by the AC-DC-AC accelerated test method

Journal: Vol.7, No.3, Summer 2014 - Article 5   Pages :   Until 

Article Code:

Sepehr Lajevardi Esfahani: Institute for Color Science and Technology - Surface Coating and Corrosion Department
Zahra Ranjbar: Institute for Color Science and Technology - Surface Coating and Corrosion Department
Saeed Rastegar: Amirkabir University of Technology - Polymer Engineering and Color Technology Department

Article's abstract:

A protective coating has been applied onto the phosphated panels using cathodic electrocoating in two different dry film thickness namely 8µm and 20µm. The corrosion resistance of cathodic electrocoatings has been studied using AC/DC/AC method. Twelve cycles of AC/DC/AC test were carried out on each sample which the DC voltage of the first 6 cycles were -4 V VS. Ag/AgCl @ 20 minutes followed by 6 more cycles at -4V for two hours. Electrical current density and bode plotes of samples were investigated during the carried AC/DC/AC test. The results showed that by decreasing the thickness of electrocoating, the barrier properties of film were declined drastically. Also, applying DC potential for a longer time 2 hours prepared harsh condition for degradation of coating. The sample with normal thickness 20µm has failed after 6 cycles although the sample with lower thickness 8µmhas failed only after 3 cycles.

Cathodic electrocoating; AC/DC/AC test; Electrical current density; Bode plote.

1. T. Boss, Prediction of coating durability, Gildeprint drukkerijen B.V., Enschede, The Netherlands, 2008, 13-36.#2. S. J. Garcia, J. Suay, A comparative study between the results of different electrochemical techniques (EIS and AC/DC/AC) application to the optimisation of the cataphoretic and curing parameters of a primer for the automotive industry, Prog. Org. Coat., 59(2007), 251-258.#3. S. J. Garcia, M. T. Rodriguez, R. Izquierdo, J. Suay, Evaluation of cure temperature effects in cataphoretic automotive primers by electrochemical techniques, Prog. Org. Coat., 60(2007), 303-311.#4. X. Liu, J. Xiong, Y. Lv, Y. Zuo, Study on corrosion electrochemical behavior of several different coating systems by EIS, Prog. Org. Coat., 64(2009), 497-503.#5. W. Walter, A critical review of DC electrochemical tests for painted metals, Corros. Sci., 26(1986), 39-47.#6. A. Ghanbari, M. M. Attar, M. Mahdavian, Acetylacetonate complexes as new corrosion inhibitors in phosphoric acid media: inhibition and synergism study, Prog. Color Colorants Coat., 2(2009), 115-122.#7. E. Alibakhshi, E. Ghasemi, M. Mahdavian, A comparison study on corrosion behavior of zinc phosphate and potassium zinc phosphate anticorrosive pigments, Prog. Color Colorants Coat., 5(2012), 91-99.#8. J. R. Scully, D. C. Silverman, M. W. Kendig, Electro-chemical impedance: analysis and interpretation, ASTM Special Technical Publication, London, 1993.#9. R. Cottis, S. Turgoose, Electrochemical impedance and noise, NACE International, NewYork, 1999.#10. D.J. Mills, K. Schaefer, Use of electrochemical methods to examine different surface preparation methods for organic coatings on steel, Prog. Org. Coat., 69(2010), 193-198.#11. F. D. Wall, M. A. Martinez, N. A. Missert, R. G. Gpeland, A. C. Kilgo, Characterizing corrosion behaivior under atmospheric conditions using electrochemical techniques, Corros. Sci., 47(2005), 17-32.#12. D. Landolt, Corrosion and surface chemistry of metals, CRC Press, NewYork, 2007.#13. M. Rashvand, Z. Ranjbar, S. Rastegar, Nano zinc oxides as UV-stabilizer for aromatic polyurethane coatings, Prog. Org. Coat., 71(2011), 362-368.#14. M. Rashvand, Z. Ranjbar, S. Rastegar, Preserving anti-corrosion properties of epoxy based coatings simultaneously exposed to humidity and UV-radiation using nano zinc oxide, J. Electrochem. Soc., 159(2012), 129-132.#15. M. Rashvand, Z. Ranjbar, Degradation and stabilization of an aromatic polyurethane coating during an artificial aging test via FTIR spectroscopy, Mater. Corros., 63(2012), 1-8.#16. M. T. Rodriguez, J. J. Gracenea, J. J. Saura, J. J. Suay, Testing the influence of the plasticizers addition on the anticorrosive properties of an epoxy primer by means of electrochemical techniques, Prog. Org. Coat., 50(2004), 123-131.#17. S. J. Garcia, J. J. Suay, Influence on the anti-corrosive properties of the use of erbium (III) trifluoromethanesulfonate as initiator in an epoxy powder clearcoat, Corros. Sci., 49(2007), 3256-3275.#18. M. T. Rodriguez, J. J. Gracenea, J. J. Saura, J. J. Suay, The influence of the critical pigment volume concentration (CPVC) on the properties of an epoxy coating, Part II. anticorrosion and economic properties, Prog. Org. Coat., 50(2004), 68-74.#19. N. Allahar, G. P. Bierwagen, V. J. Gelling, Understanding AC-DC-AC accelerated test results, Corros. Sci., 52(2010), 1106-1114.#20. K. N. Allahar, V. Upadhyay, G. P. Bierwagen, Characterizing the relaxation of the open circuit potential during an AC-DC-AC accelarated test, DOD Corrosion Conference, London, 2009.#21. J. Hollaender, E. Ludwig, S. Hillebrand, in: Proceedings of the 5th International Tinplate Conference, London, 1992.#22. J. Hollaender, Rapid assessment of food/package interactions by electrochemical impedance spectroscopy (EIS), Food Addit. Contam., 14(1997), 617-626.#23. J. Hollaender, C. A. Schiller, W. Strunz, in: Proceedings of the EIS 2001, Marilleva, Italy, 2001.#24. G. P. Bierwagen, K. N. Allahar, Q. Su, V. J. Gelling, Electrochemically characterizing the AC-DC-AC accelerated test method using embedded electrodes, Corros. Sci., 51(2009), 95-101.#25. N. Q. Su, K. Allahar, G. Bierwagen, Embedded electrode electrochemical noise monitoring of the corrosion beneath organic coatings induced by AC-DC-AC conditions, Electrochemical Acta, 53(2008), 2825-2830.

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Prof. Zahra Ranjbar
Dr. Farahnaz Nourmohammadian
Assistant Editor:
Dr. Mozhgan Hosseinnezhad
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Institute for Color Science and Technology (ICST)

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