Corrosion Heusler

The most important outcome of this theory is that the rate of dissolution should be potentially greater as the pH increases, which is in conflict with simple concepts of corrosion kinetics. However, the theory has been proved to be applicable to many systems, and BonhoeflFer and Heusler found that iron in sulphuric acid corroded at a greater rate with increase in pH, whilst Kabanov etal. found that it corroded faster in alkaline solution than in acid solution for the same electrode potential. 

Huerta, D. and Heusler, K. E., Proc. 9th Int. Cong. Metallic Corrosion, National Research Council Canada, Ottawa, 222 (1984)... 

Other results point to no electrocatalytic increment with amorphous metals. Heusler and Huerta [591] have investigated amorphous Co75B25 and Ni67B33 with respect to corrosion. For the reaction of hydrogen evolution, in the case of the Co alloy, Tafel slopes of 120 mV, along with lower exchange currents for the amorphous material have been reported. Thus, the mechanism is the same as for the crystalline metal. In the case of the Ni alloy, some decrease in the Tafel slope has been observed with heat treatment (which promotes crystallization). Similarly, the same Tafel slope of 120 mV and the same exchange current as for pure Fe have been measured with... 

Heusler, K.E., Landolt, D. and Trasatti, S., Electrochemical Corrosion Nomenclature, Pure Appl. Chem. 61 (1989) 19-22. 

W. J. Lorenz, K. E. Heusler, Anodic dissolution of iron group elements in Corrosion Mechanisms (Ed. F. Mansfeld), Marcel Dekker, New York, Basel, 1987. 

In situ X-ray absorption spectroscopy and X-ray diffraction, as well as the already mentioned STM studies, have shown the adsorption of anions at metal surfaces and their influence on metal dissolution. Adsorption and complexation by anions may be followed even by XPS if appropriate preparation of the metal surface and its transfer into the UHV is successful. Therefore, detailed studies with modern microscopic and spectroscopic methods are required to obtain detailed insight into the reaction steps of corrosion processes. However, even electrochemical corrosion studies give insight into their mechanism. As an example, the catalysis of iron dissolution according to Heus-ler is presented (Bonhoeffer and Heusler, 1956). 

Tanabe, H., Yamamura, Y, Misawa, T., In situ ionic imaging for pitting corrosion sites on austenitic stainless steels with scanning electrochemical microscopy. In Passivation of Metals and Semiconductors, Heusler, K. E., Ed. 1995, Materials Science Forum, Vol. 185—188, pp. 991—1000 Proceedings of the 7th International Symposium on the Passivity of Metals and Semiconductors, Clausthal, Germany. ISBN 978-0-87849-692-1. Trans Tech Publications Ltd. 

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