Abstract

Measurements of the corrosion rate belong to the most important aspects of materials science. In order to reduce material loss corrosion inhibitors are used. However selection of proper inhibitor should be based on evaluation of its mechanism and effective concentrations. Mechanism of inhibition usually has dynamic character so physicochemical parameters are changing in time. Most of actually used methods are stationary or contain assumptions which highly influences obtained values. Development of new dynamic method allows perturbation of the system by signal composed of galvanodynamic perturbation and AC signal as a set of 20 sinusoids. The modified DEIS technique is used for determining instant value of charge transfer resistance. Novel electrochemical approach for estimation of actual corrosion rate of mild steel in industrial water inhibited by 8-Hydroxyquinoline based on impedance measurements in the form of modified galvanodynamic electrochemical impedance spectroscopy (DEIS) under linear current change conditions is presented. Obtained values were instantly compared with polarization resistance taken from the potential-current dependence. Concentration of inhibitor was changed by 3 steps during measurement. The highest recorded inhibition efficiency was about 76% for concentration 5.97x10-3g/mol. Two methods confirmed that higher concentration has negative effect. After twenty hours of exposition of sample in the 9.19x10-3g/mol of 8-HQ efficiency was equal to 72% is maintained. Tafel polarization measurements allowed indication of 8-Hydroxyquinoline as cathodic type inhibitor.

Authors (3)