Evaluation of cavitation erosion resistance of copper alloy in different liquid media

Abstract

To evaluate the influence of liquid property on cavitation erosion resistance of the copper alloy, an experimental investigation is performed with the ultrasonic vibratory apparatus. Liquid media of deionized water, tap water, and 3.5 wt.% NaCl solution are selected. The cumulative mass loss rate and microhardness are measured and surface morphology observed at different erosion time. The results show that the cumulative mass loss increases consistently with the erosion time, and the highest cumulative mass loss rate is witnessed in tap water. The erosion time at which the maximum cumulative mass loss rate is reached is the shortest with the 3.5 wt.% NaCl solution. Surface morphology testifies the rapid evolution of small cavitation erosion pits into large eroded area in the specimen surface submerged in the deionized water and tap water. In comparison, the specimen surface in the 3.5 wt.% NaCl solution is featured by insignificant cavitation erosion, and plastic deformation remains predominant for a long erosion time. The initiation and development of micro‐cracks are remarkable in tap water. In the 3.5 wt.% NaCl solution, the progression of cavitation erosion is mitigated relative to the other two cases, and cavitation erosion pits remain the predominant constituents of the erosion pattern as the erosion time increases. The hardening layer is found beneath the specimen surface, and the 3.5 wt.% NaCl solution is responsible for the thickest hardening layer. As cavitation erosion develops, the softening phenomenon is salient with consistent flaking off of surface layers.