Synergistic effect between cavitation erosion and corrosion of Monel K500 alloy in 3.5 wt% NaCl solution

Abstract

Cavitation erosion-corrosion simultaneously damaged the material through mechanical attack and electrochemical corrosion. In this work, experiments were performed on Monel K500 alloy in deionized water and 3.5 wt% NaCl solution using an indirect ultrasonic vibration system to investigate the synergistic effect between cavitation erosion and corrosion. Mass loss measurement and surface topography observation were used to identify the different stages of cavitation erosion. The electrochemical properties at different cavitation stages were analyzed by EIS technique. Results showed that the synergistic effect between cavitation erosion and corrosion exacerbated cavitation damage, and the weight loss rate in 3.5 wt% NaCl solution was about 10% higher than that in deionized water. The increase in ion diffusion and oxygen supply caused by violent agitation accelerated the surface corrosion process, resulting in corrosion-enhanced erosion. Mechanical damage to the material surface during the cavitation process also accelerated the corrosion process, indicating that cavitation-enhanced corrosion was the primary synergistic mechanism. Pure cavitation accounted for 90.75% of total mass loss, suggesting that mechanical deterioration dominated the overall cavitation erosion and corrosion process. Cavitation-enhanced corrosion accounting for 96.12% of the synergistic effect，was the main synergistic mechanism.