Abstract
The corrosion rate of steel in aqueous solutions was monitored by measuring the current in a galvanic couple consisting of steel and an other more noble metal using a zero impedance ammeter. Current densities obtained by monitoring were found to have an extremely high correlation with the corrosion rate obtained from weight loss measurement. The error in the values obtained by weight loss measurement was not more than 25%. Thus, the accuracy of galvanic couple monitor differed little from that of other methods such as Tafel extrapolation, polarization resistance or impedance method. It was also possible with this monitor to obtain simultaneously both the average corrosion rate over a long period and the instantaneous corrosion rate at various points of time. In addition, this method satisfies relatively well the various conditions required of this kind of monitor with regard to automation, cost instrument, measurement conditions and so on.
