FRACTAL QUANTIFICATION OF ALUMINUM PITTING CORROSION INDUCED BY HUMID TROPICAL CLIMATE
During three annual exposure periods, aluminum samples of wire, used for transmission of high voltage electricity, were exposed at outdoor atmospheric marine-coastal and rural environments, located in the humid tropical climate of Yucatan Peninsula, in the Mexican gulf. In atmospheric conditions the naturally formed aluminum oxide layer can be destroyed by the presence of chlorides, causing pitting localized corrosion attack, difficult for evaluation. The concepts of fractal geometry and self-similarity were used in this study for evaluation of the pitting corrosion as a function of time, making a statistics of the frequency of appearance of pits versus the area occupied by them. The data showed that the distribution of the pits follows a power law. The exponent of self-similarity varied between 1.7-1.9 and it is relatively stable with the progress of corrosion progress. The progress of pits in area and frequency is more pronounced in time in the marine-coastal atmosphere, compared to pitting developed in rural- urban one. The concepts of fractal geometry and self-similarity can quantify the extent of localized corrosion with time, as nondestructive form and rapid method.
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