Some errors in the estimation of corrosion rates in high conductivity media due to neglect of the ohmic drop compensation

The ohmic drop in the bulk of the electrolytic solution and at the surgace layers of corrosion products, RΩ, can be the source of errors on estimating the corrosion rates, icorr, by the polarization resistance technique, Rp, if their effect is not compensated, for which nowadays use can be made of convenient and effective proceedings. In this paper some experimental results with Al, Cu, Fe and Zn in sulphuric acid solutions are included. These results prove that very important errors can appear even in high conductivity media, whenever the corrosion rates would be high (low Rp), because the relative error magnitude is expressed by the RΩ/Rp ratio, between the resistance offered by the media to the current flow and the polarization resistance value. (author)