Instantaneous impedance monitoring of synergistic effect between cavitation erosion and corrosion processes

• Authors have determined method of cavitation erosion-corrosion monitoring.
• The results obtained from DEIS and weight loss show excellent agreement.
• Erosion influence local corrosion processes, such as deallyoing.

The most common method of determination of cavitation erosion resistance as well as the magnitude of erosion-corrosion synergistic interaction is based on the weight loss measurements. Nondestructive characterization of installations elements is in most cases impossible to perform. Also, such a measurement does not include local types of failure or alteration of operating conditions. There is an urge to elaborate a method for monitoring of cavitation erosion-corrosion damage. The authors used dynamic impedance technique to study change of electric parameters of various engineering alloys under synergistic interaction of cavitation erosion and corrosion in 3% NaCl solution. Monitoring of electric parameters offers a very good resemblance to failure level identified with weight loss function and microscopic analysis. It was possible to distinguish different stages of material degradation by means of instantaneous impedance measurements. Instantaneous value of charge transfer resistance provides information about synergistic influence of mechanical erosion on corrosion.