Abstract
In order to providefurther evidence concerning the reliability ofpredicting relativegeneral corrosion rates of metals and alloysfrom the nature of their corrosion potential/time and potentiostatic polarisation curves, some characteristic datafrom the literature are summarised, especially data concerning Fe and Al. Some new material obtained in our own laboratory is also included. The criterion of the accuracy of the prediction was the closeness of the predicted values to those obtainedfrom weight loss measurements.
It was concluded that prediction is trustworthy only in some cases. In general the prediction is wrong and, in addition to general causes already quoted in the literature, it was found that disagreement arises when the spontaneously established electrical corrosion field is disturbed by electrical forces derived from the type of set-up, from certain protective materials such as anticorrosive paints containing metal powder or bipolar molecules, from additives in surrounding concrete etc.
It was also found that the weight loss itselfis influenced by the kind of individual container in which each specimen is placed. The weight loss of a specimen is further affected (increased) by the actual measurements of its potential.
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