Passivation potential mapping

Theoretical considerations and practical experience on a large number of structures (Elsener and Bohni, 1990 Elsener etal., 1996) demonstrate that the results of potential mapping need careful interpretation. It has been found that there are no absolute potential values to indicate corrosion hazard in a structure - in contrast to the interpretation given in the ASTM C876-91 that relies on a fixed potential value of -0.35 V CSE. Depending on moisture content, chloride content, temperature, carbonation of the concrete and cover thickness, different potential values indicate corrosion of the rebars in different structures (Fig. 8-18). Thus the gradient between corroding and passive areas is more important than the absolute... 

Figure 15.4 Mapping electrochemical material loss against mechanical erosion rates for a nonpassivating surface carbon steel (AISI1020) along with two potentially passivating surfaces of nickel aluminum bronze (NAB) one that has been thermally sprayed by high-velocity oxy-fuel deposition as a coating on carbon steel ( j and another which has been cast (A.). These results were obtained from jet impingement erosion-corrosion tests. Reprinted from Ref. [7]. Copyright (2007) with permission from Elsevier.

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