Dynamical model and numerical study of cavitation bubble in ultrasonic assisted electrochemical polishing solution of selective laser melting NiTi alloy

Abstract

In the process of ultrasound assisted electrochemical polishing of selective laser melting (SLM) NiTi alloy, a large number of cavitation bubbles will be generated in the anode and cathode, and these cavitation bubbles will expand and compress rapidly until finally collapse. At the moment of collapse, high temperature and high pressure will occur, and at the same time, pressure shock wave and micro-jet will be produced, which will have a certain impact on material removal during polishing. In order to explore the mechanism of ultrasonic assisted electrochemical polishing, in this paper, the dynamics of cavitation bubbles with free interface and rigid interface are analyzed by ultrasonic assisted electrochemical polishing. The dynamics models of single cavitation bubble and two cavitation bubbles are established. The fourth order Runge–Kutta method was used to solve the model numerically, and the influence of electric field intensity, initial bubble radius, sound pressure amplitude and ultrasonic frequency on the dynamics of cavitation bubble was analyzed. The results show that in the range of f = 1–10 KHz, the initial radius of bubble is 0.01–0.05 micron, the sound pressure amplitude is 103 Pa, and the electric field intensity is 104 V m−1, the cavitation movement gradually becomes regular, and it goes through a complete process of expansion, contraction and then collapse, which is beneficial to the cavitation effect. This provides a theoretical basis for further research on the mechanism of ultrasonic assisted electrochemical polishing of SLM-NiTi alloy, which is of great significance for broadening the processing of additive manufacturing parts with low cost, high efficiency, and consistent quality.