Effect of ultrasonic cavitation micro-jet impact on corrosion of material in ultrasonic assisted electrochemical micromachining

Ultrasonic assisted electrochemical micromachining (UAEMM) is a promising method for its advantages in micromachining applications. It was conformed that more micro-bubbles can be produced and collapse in the proximity of an interface, resulting in high-speed micro-jet formation with surface erosion. This paper investigates the specific effect of cavitation micro-jet generated in a narrow gap in UAEMM on material corrosion. Firstly, the micro-jet impinging pressure was computed, erosion pits of chemical reaction by the micro-jet were simulated and verified, and the material was more easily removed in bulged areas by the analysis of electric field distribution around erosion pits. Furthermore, the variation of metallographic structure and electrochemical polarization characteristics of materials influenced by ultrasonic amplitude and processing time were studied in detail. Results show that the crystalline grain was refined with the increase of ultrasonic amplitude and processing time, which leads to a decrease in corrosion potential. Consequently, verification experiments were done in UAEMM and denoted that the material removal and surface precision improved significantly, and surface hardness was also increased. Graphical abstract