Abstract
THE thickening of oxide or other films on metals according to the parabolic equation y2= K1t + K2 (where y is the film thickness at time t and all K's are constants) is generally attributed to lattice-defects, K1 being related to the electrical constants of the film substance by Wagner's equations1. Logarithmic thickening (y = K3 log (K4t + K5) is, in my view2, associated with discrete mechanical breakdowns caused by the strains arising from the volume increase accompanying oxidation ; evidence of such strains is provided by the wrinkling observed during film-stripping3.
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For analysis, see Stuart, N., and Evans, U. R., J. Iron and Steel Inst., 147, 131P (1943).
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Vernon, W. H. J., Akeroyd, E. I., and Stroud, E. G., J. Inst. Met., 65, 301 (1939).
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EVANS, U. Crack-Heal Mechanism of the Growth of Invisible Films on Metals. Nature 157, 732 (1946). https://doi.org/10.1038/157732a0
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DOI: https://doi.org/10.1038/157732a0
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