Effect of Thiourea on the Corrosion Behavior of Aluminum Anode Foil of Aluminum Electrolytic Capacitor

摘要

The specific capacitance is a key performing factor for the aluminum anode foil of aluminum electrolytic capacitor. In order to increase the specific capacitance, the effect of thiourea (TU) as corrosion inhibitor on the aluminum anode foil was investigated in this paper. Electrochemical impedance spectroscopy (EIS), polarization curves and weight loss measurements were used to investigate the effect of corrosion inhibitor TU added to nitric acid. EIS and inductance-capacitance-resistance (LCR) meter were also used to measure the specific capacitance of the aluminum anode foil, which was etched in nitric acid containing different contents of TU, and then formed in boric acid solution (100 g L-1) at 540 V. The results showed that the TU could be used as an inhibitor for Al in an acid solution. When the concentration of TU was 0.10%, the specific capacitance reached up to 0.661 mu F cm(-2), which increased by nearly 24% compared to that without TU. The data for the specific capacitance of Al anode foil corresponding to different TU concentrations obtained by EIS coincided well with the one obtained using LCR meter; thus, EIS could be effectively used for the preliminary selection of the type and ideal concentration of inhibitor.