Two methods to prepare tungsten/tungsten oxide as reference electrode for performing electrochemical measurements in H2O-saturated super critical (SC) CO2 phase in the study. The W/Woxide reference electrodes are fabricated using electrochemical or thermal oxidation.
The stability of each type of tungsten/tungsten oxide electrodes is verified by comparing the potential in brine solutions containing MEG up to 100ºC with exposure time over 48 hours. The results are consistent with literature that the reference potential decreases with the increase in temperature. The results also show that the thermal-prepared W/Woxide reference electrode is stable at high temperature.
The W/Woxide reference electrode is employed to electrochemically test carbon steel (Q-125) in the SC-CO2 at 65ºC. It is found that the W/Woxide reference electrode can be used for studying the electrochemical mechanism of carbon steel corrosion in SC-CO2, assessing the effect of changing oxidizing conditions of the SC-CO2 environment on the carbon steel corrosion kinetics.
Keywords: Corrosion, tungsten, supercritical, electrochemistry