Analysis And Experimental Study On Vibration Performance Of Aluminum Alloy Radiator

Ultrasonic wave can purify the melt,refine the solidified structure and improve the casting defects.Its mode of action is mainly to directly conduct high-frequency and high-energy ultrasonic waves into the melt through the radiation rod,and regulate the melt quality and solidified structure through special physical and chemical effects such as ultrasonic cavitation and acoustic flow.As the radiation rod is in direct contact with the high-temperature melt,its working environment is relatively harsh,and it is the main loss part of the ultrasonic vibration system.The replacement cost is high,and the long-term cavitation,fatigue and melting corrosion will inevitably lead to the reduction of the transmission performance of the radiation rod and the weakening of the ultrasonic metallurgical effect,which is the bottleneck problem that restricts the popularization of ultrasonic casting technology,especially its application in hightemperature metal melts such as steel and tungsten.At present,titanium alloy is widely used as the material of ultrasonic radiating rod.The research focuses on how to improve the surface corrosion resistance of radiating rod and the use of nonmetallic materials such as ceramics,graphite and silicon nitride,but it still can’t effectively solve the problems of high cost or connection reliability of radiating rod.In this paper,a new design concept of radiant bar is put forward: using the same material as the processed metal melt to develop radiant bar as a pollution-free additive consumable can not only greatly reduce the cost,but also break through the bottleneck of its application in ultra-high temperature melt.The research is aimed at ultrasonic casting of 2219 aluminum alloy,and the radiation rod of 2219 aluminum alloy is developed,and its vibration performance,casting law,corrosion law and surface strengthening are tested and studied.The specific research contents and conclusions of this paper are as follows:(1)Based on the principle of horn,the 2219 aluminum alloy radiating rod was designed.Through simulation analysis and combined with the requirements of specific casting conditions,the best matching size was (?)50×381mm.The vibration performance of two ultrasonic vibration systems equipped with aluminum and titanium alloy radiating rods is compared.The results show that aluminum and titanium radiating rods have little influence on the modal shape of the ultrasonic vibration system,but great influence on its resonant frequency and output amplitude.The resonant frequency of aluminum alloy radiating rods is 20.1k Hz,and the output amplitude is 118),which is 4% higher and 15% lower than that of titanium alloy radiating rods.Its dynamic performance can better meet the requirements of casting technology.(2)Taking ultrasonic power and time as variables,the change law of solidification structure of aluminum alloy melt under the action of aluminum alloy radiating rod was studied.The results showed that the ultrasonic effect of aluminum alloy radiating rod was close to that of titanium alloy radiating rod,which indicated that the radiating rod made of the same material as 2219 aluminum alloy melt could also achieve good ultrasonic refining effect.(3)The variation law of ultrasonic vibration performance of aluminum alloy radiating rod in the process of dynamic melting and corrosion and the influence law of ultrasonic wave on solidified structure were studied.According to the microstructure evolution characteristics and the early dynamic analysis results,it was estimated that the service life of aluminum alloy radiating rod was about 1h under the experimental conditions,and the radiating rod loss was about 2/3 at this time,so the refining effect of ultrasonic wave on structure was weak.(4)The aluminum alloy radiating rod was treated by hard anodic oxidation,and the corrosion change law of radiating rod before and after surface treatment was compared and analyzed.The mechanism of melting corrosion resistance of radiating rod after surface treatment was discussed.The results show that the corrosion of aluminum alloy radiant bar is mainly melting corrosion,and the influence of cavitation corrosion can be neglected.After the surface of the radiant bar is treated by hard anodizing,there is almost no melting corrosion in the first 0.5h,and the end face of aluminum alloy radiant bar is completely melted after 1h,which indicates that the aluminum oxide on the surface can withstand high temperature,thus greatly prolonging its.