Corrosion monitoring of hydrogen by HUP probe in the presence of sulphide and thiourea

Abstract

The effect of sulphide and thiourea on hydrogen uptake during the corrosion of steel in deaerated pH3 has been studied using an electrochemical hydrogen probe incorporating a solid electrolyte (HUP) and lead dioxide (PbO 2 ) as a reference electrode. This probe has been used for the quantitative determination of the hydrogen activity generated during the corrosion of steel. The sensor voltage implies an average equivalent hydrogen pressure in uncharged steel of 2 Â 10 À18 atmospheres. During the corrosion of steel, this value increases by very large amounts; thus in deaerated pH3, the equivalent pressure rose by 10 24.5 in the presence of 200 ppm sulphide and by 10 2 in the presence of 100 ppm thiourea. Weight loss and AC impedance methods were also performed under the same conditions as the hydrogen measurements. The hydrogen probe data were correlated with AC impedance and weight loss results in order to understand the effect of S 2À and thiourea on hydrogen uptake.