Miniaturisierte elektrochemische Sensoren zur in-situ-Untersuchung der Spaltkorrosion in Modellsystemen

In-situ-investigation of crevice corrosion in model systems using miniaturized electrochemical sensors Measuring characteristics of miniaturized sensors for the determination of the parameters pH value, oxygen content, concentration of chloride ions and redox potential was tested and optimized with regard to the application in model crevices. The sensors were used for examinations of crevice corrosion in 0.1 molar and 1 molar solution of NaCl at the following alloys: X 20 Cr 13, X 2 CrNi 18 10, X 2 CrNiMoN 17 13 5, X 2 CrNiMoN 17 13 5*, X 2 CrNiMo CuN 20 25 6. Corrosion characteristic of the alloys and the change of crevice electrolyte without external polarization and with galvanostatic polarization (i = 10 μA/cm², i = 200 μA/cm²) were tested and discussed by the hand of the model concepts from Oldfield and Sutton 1]. In experiments with galvanostatic polarization the steels with increasing content of chromium or molybdenum showed a growing stability against crevice corrosion. The results showed that simultaneous measurements of the above mentioned chemical parameters of crevice electrolyte in connection with the corrosion potential can supply additional information about causes and mechanism of crevice corrosion.