2022 年 73 巻 5 号 p. 248-252
A sensor probe involving a copper reference electrode was developed for copper corrosion diagnosis（CCD）in fresh water. Electrochemical measurements are often employed for CCD in three-electrode system. In such cases, commercial glass reference electrodes are used for electrochemical measurements. Because the repeated use of commercial glass reference electrodes in fresh water with different compositions degrades the reference electrode, a maintenance-free reference electrode is necessary for fieldwork involving CCD. In this study, a copper tube was selected as the reference electrode for electrochemical measurements. Our newly developed sensor probe for CCD comprises three copper tubes as the working electrode, counter electrode, and reference electrode. Each 1.6-mm-diameter copper tube was covered with a polyvinyl chloride insulator and was arranged as parallel with the others, with 1.6 mm spacing. Because these copper tubes can be cut off easily after electrochemical measurements, the maintenance-free reference electrode can be used for each electrochemical measurement. Potentiostatic polarization and galvanostatic polarization were conducted using the sensor probe. Then the obtained values（current and potential）and pH of the test solution were applied to the three-dimensional diagram, designated as corrosion map 3D, for CCD. Results confirmed that the corrosion diagnosis in corrosion map 3D can be categorized as having no corrosion, pitting corrosion, or general dissolution. Moreover, results obtained using the sensor probe showed good agreement with results obtained using the three-electrode system involving the commercial glass reference electrode.
