Experiment And Mechanism Study Of Cavitation Erosion Of Ultrasound Radiator In Aluminum Melt

Abstract:In the Al-alloys casting technology treated by ultrasonic, the cavitation effect produced by power ultrasonic leads to serious cavitation corrosion at the end face of ultrasound radiation rod, which is the most urgent problem needed to be solved in the ultrasonic casting technology. The cavitation destroys of the ultrasound radiation rod not only affects the function of ultrasonic but also restricts the effective service life of the radiation rod. The cavitation corrosion process and mechanism in aluminum melt of titanium alloy ultrasound radiation rod was mainly investigated in this paper:1.Based on the VOF method in the powerful fluid calculation software Fluent, a simulation analysis was carried out to study the collapse of a single cavitation bubble near wall. The simulation results showed that cavitation bubble near wall collapsed asymmetrically and formed a certain scale of micro Jet just at the moment of collapse. The micro Jet pointed to surface, and decayed rapidly from the normal directions of the wall. The micro Jet produced by the collapse of cavitation bubble could lead to the water hammer effect on wall, thus generated instantaneous high pressure. The pulse high pressure was an important reason to cavitation destroys.2.The experiment of cavitation erosion about titanium alloy ultrasound radiation rod in the Aluminum melt was carried out using weight-loss method and melt Ti-elements detection method to describe the cavitation process of radiation rod. The experimental results indicated that cavitation first appeared at the center of the end surface of the radiation rod. The center cavitation pit gradually enlarged over time and inward concaved, eventually spread to the entire end face, until the end surface material peeled off completely. Acceleration period and stable period were clearly observed in the process of cavitation erosion, while incubation period and attenuation period were not obvious. The optimum duration of titanium alloy radiation rod was about15hours.3.Micro-morphology observation and component detection were carried out using Scanning Electron Microscopic (SEM) and energy spectrum of the cavitation erosion sample at different cavitation erosion time. The results showed that cavity collapse would produce pits on the surface of material and make surface matrix shed. At the same time, titanium alloy matrix would react with aluminum melt and form granular Al3Ti, which would break off easily from titanium alloy matrix under the impact of the cavity collapse because it’s hard and brittle. The cavitation damage of titanium alloy radiation rod in aluminum melt was resulted from both mechanical damage and chemical etching produced by the cavitation bubble collapse. With46figures,8tables, and82references.