ELECTROCHEMICAL ASSESSING METHOD OF LOCAL CORROSIVENESS ON MATAL SURRFACE

摘要

PURPOSE:To detect the position of corrosion point and the current flowing in the corrosion point only at high precision and at high speed, without requiring complicated pretreatment, by providing a specific electrode for measuring corrosion opposedly and closely to the surface of the metal to be measured, and moving this electrode. CONSTITUTION:A probe electrode 21 is surrounded with a guard electrode 23, and they are met at the flush end. The electrode 21, by way of a current detecting device 22, is connected to the negative side output terminal of a power source 24, together with the electrode 23. When a current runs, the potential between the electrodes 21 and 23 differs by the portion of the voltage drop due to the device 22, but this potential difference is small as compared with the voltage applied to the metal piece being tested 25 and electrodes 21, 23, and, hence, may be regarded as same potential level. Therefore, the stream line of the current in the electrolyte 30 positioned between the metal piece 25 and electrodes 21, 23 resembles a stream line group 31, and the current from the part opposing to the electrode 21 on the metal piece 25 corresponding to the area of the electrode 21 flows into the electrode 21, so that the local phenomenon of the metal piece 25 may be detected.