Complex Formation in Metal Dissolution and Metal Treatment.
Technical progress rept.,
AMERICAN UNIV WASHINGTON D C DEPT OF CHEMISTRY
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This report examines the concept that a critical step in metal dissolution or metal reaction involves the formation of metal-anion complexes and further, the nature of the complex dictates the ensuing reaction, be it accelerated dissolution or protective film formation. This is the concept which furnishes the basis for the complex ion theory of corrosion. Various lines of evidence are cited to support the theory, including the existence of a stoichiometric order of reaction for the pitting of iron, stainless steel, and aluminum alloys in halide solutions, the spectrophotometric observation of iron-anion complexes during the dissolution of iron in acid solutions and the decay of the scrape potential in various electrolytic solutions. New supporting data are presented using relaxation theory treatment of scrape potential and scrape current measurements. Reactions at the interface between oxide-free metal and aqueous solutions take place during time durations similar to those reported for the formation of complexes in solution, also, studied with relaxation techniques.
- Properties of Metals and Alloys