A New Indication System for Demonstration of a Corrosion Differential Aeration Cell
Department of Metals and Corrosion Engineering, Institute of Chemical Technology Prague,Prague
A new indication system was designed to demonstrate a differential aeration cell on iron in a drop experiment in NaCl solution (30 g l-1). Bromethymol blue (0.4 g l-1) and 2,2’-bipyridyl (0.5 g l-1) were used for the indication of elevated alkalinity and ferrous ions, respectively. The new indication system has no corrosion stimulating effects as the traditional ferroxyle indicator (hexacyanoferrite + phenolphthalein) and indicates more reliably formation of anodic and cathodic zones in dependence on the surface accessibility for air oxygen. The new indication system can fully replace the ferroxyle indicator for demonstrations of other types of corrosion cells as well.
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