CORROSION RESEARCH ROUND‐UP

GERMANY Inhibition of hydrogen corrosion of iron by phenyl thiourea. In de‐aerated acid solutions the corrosion of iron is much reduced by very small additions of phenyl thiourea. For a quantitative study of this, stationary current/voltage curves were studied at potentials close to the open‐circuit potential of carbonyl iron in NaClO‐HClO4 solution of pH 2. By control measurements of various kinds it was thus shown that it is possible to obtain the partial current/voltage curves of both iron dissolution and hydrogen deposition with high accuracy. Therefore a quantitative estimation of the anodic and cathodic components of the total inhibition efficiency is possible. With phenyl thiourea it was found that, under the experimental conditions, inhibition was nearly exclusively cathodic up to 10−6 mol/1. inhibitor, with gradually increasing anodic inhibition at higher concentration.—(H. Kaesche, Werks. u. Korr., 1959, 10 (10), 622–624.)