Abstract
The performance of corrosion resistant inorganic oxide coatings formed on Al–Cu–Mg alloys is often degraded by Cu enrichment that occurs during oxide formation. This is particularly true of coating processes conducted in basic solutions. A modification to an alkaline oxide coating process has been made that simultaneously eliminates Cu enrichment and forms a corrosion resistant coating. In this paper, the modified process is described and the resulting coating morphology, structure and composition are reported. Results from electrochemical and exposure corrosion tests show that useful gains in corrosion resistance are achieved. Cu removal during the modified process is rationalized using an argument based on the increase in Cu solubility that occurs in solutions with a pHgreater than the solubility minimum for Cu (9.8), and the effect of Cu complexing by carbonate.
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References
J. E. Hatch (Ed.), ‘Aluminum: Properties and Physical Metallurgy’, ASM, Metals Park, OH (1984) p. 321.
L. F. Modolfo (Ed.), ibid., p. 693.
Idem, ibid., p. 254.
M. Pourbaix, ‘Atlas of Electrochemical Equilibria in Aqueous Solutions’, NACE, Houston, TX (1974) p. 389.
C. A. Drewien and R. G. Buchheit, paper 622, Corrosion ‘94, NACE, Houston, TX (1994).
N. Fin, H. Dodink, A. E. Yaniv and L. Drori, Appl. Surf. Sci. 28 (1987) 11.
J. S. Solomon and N. T. McDevitt, Thin Solid Films 84 (1981) 155.
A. V. Pocius, T. H. Wilson, Jr., S. H. Lundquist and S. Sugii, in ‘Progress in Advanced Materials and Processes: Durability, Reliability and Quality Control (edited by G. Bartelds and R. J. Schekelmann), Elsevier Science, Amsterdam (1985) 71.
T. S. Sun, J. M. Chen and J. D. Venables, Appl. Surf. Sci. 1 (1978) 202.
F. Mansfeld and L. Kwiatowski, ‘Surface Treatment of High-Cu Aluminum Alloys’, University of S. California, Interim Report (1992).
Sanchem 1000, Sanchem, Inc., Chicago, IL.
ZPlot for WindowsTM, Scribner Associates, Charlottesville, VA.
ASTM B117, Standard Method of Salt Spray (Fog) Testing, v. 3.02, ‘Annual Book of ASTM Standards’, American Society for Testing and Materials, Philadelphia, PA (1993) 19.
R. G. Buchheit, M. D. Bode and G. E. Stoner, Corrosion 50 (1994) 205.
J. Hitzig, K. Juttner and W. J. Lorenz, J. Electrochem. Soc. 133 (1986) 887.
F. Mansfeld and M. W. Kendig, ibid, 135 (1988) 828.
F. Mansfeld, S. Lin, S. Kim and H. Shih, Electrochim. Acta 34 (1989) 1123.
G. Phragmen, J. Inst. Metals 77 (1950) 459.
B. Mazurkiewicz and A. Piotrowski, Corros. Sci. 23 (1983) 697.
R. G. Buchheit, R. P. Grant, P. F. Hlava, B. A. McKenzie and G. L. Zender, J. Electrochem. Soc. 144 (1997) 2621.
K. Urushino and K. Sugimoto, Corros. Sci. 19 (1979) 225.
C. F. Baes, Jr. and R. E. Mesmer, ‘Hydrolysis of Cations’, R. E. Krieger Publishing, Malabar, FL (1986) 268.
P. Schindler, M. Reinert and H. Gamjager, Helv. Chim. Acta 51 (1968) 1845.
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Buchheit, R.G. Copper removal during formation of corrosion resistant alkaline oxide coatings on Al–Cu–Mg alloys. Journal of Applied Electrochemistry 28, 503–510 (1998). https://doi.org/10.1023/A:1003217211727
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DOI: https://doi.org/10.1023/A:1003217211727