The elctrochemical noise analysis was used to detect the onset of crevice corrosion on DHP copper electrodes, exposed to a neutral solution containing bicarbonates, sulphates and chlorides. Some heterocyclic compounds (pyrimidine and thiadiazole derivatives) were studied as inhibitors of this form of corrosion, both solution additives and prefilming agents. The corrosion process was monitored during 5 day immersion periods, by mesuring both electrochemical current noise between two coupled electrodes, and the linear polarization resistance values. After 5 days, anodic and cathodic polarization curves were also recorded. Specimens exposed for 1 month to the aggressive solution, in the absence and in presence of inhibitors, were observed with the scanning electron microscope to ascertain the extent of the corrosion attack. The data indicated a good agreement between noise power values and polarization resistance values to evaluate the aggressiveness of the different conditions. On the contrary, the analysis of the polarization curves gave a poor discrimination among the inhibiting capabilities of the substances against crevice corrosion.
Monitoring of DHP Copper Corrosion and Inhibition by Electrochemical Noise Analysis
MONTICELLI, Cecilia;ZUCCHI, Fabrizio
1995
Abstract
The elctrochemical noise analysis was used to detect the onset of crevice corrosion on DHP copper electrodes, exposed to a neutral solution containing bicarbonates, sulphates and chlorides. Some heterocyclic compounds (pyrimidine and thiadiazole derivatives) were studied as inhibitors of this form of corrosion, both solution additives and prefilming agents. The corrosion process was monitored during 5 day immersion periods, by mesuring both electrochemical current noise between two coupled electrodes, and the linear polarization resistance values. After 5 days, anodic and cathodic polarization curves were also recorded. Specimens exposed for 1 month to the aggressive solution, in the absence and in presence of inhibitors, were observed with the scanning electron microscope to ascertain the extent of the corrosion attack. The data indicated a good agreement between noise power values and polarization resistance values to evaluate the aggressiveness of the different conditions. On the contrary, the analysis of the polarization curves gave a poor discrimination among the inhibiting capabilities of the substances against crevice corrosion.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
