Analysis of mechanical and chemical mechanisms on cavitation erosion-corrosion of steels in salt water using electrochemical methods

Abstract

Abstract Cavitation erosion-corrosion causes damage and removal of material especially in rotors of centrifugal pumps, water turbines, as well as in control valves and in motors. Based on a dynamic corrosion model the pure mechanical erosion amount of different steel alloys was identified using an indirect cavitation test method combined with an electrochemical cell. We demonstrate that cavitation erosion can be enormously reduced by application of external cathodic potentials. The cavitation rate was in-situ determined using atomic emission spectrometry during the cavitation test. Due to the separately identified pure mechanical and the combined corrosive and synergistic cavitation erosion-corrosion correlation with hardness and arising charge densities during cathodic potentials were found for the mechanical part.