Research On Mechanism Of Oxygen Dissolved And Released In Molten Silver And Casting Machine Design Of Silver

With the development of Chinese economy society and the advance of industry technology, and the improvement of people’s living standards, the consumption amount of silver is rising gradually, especially the industrial use of silver amount is more and more larger. The higher production capacity and product quality were put forward. However, characteristics of oxygen dissolved and released in molten silver make "silver rain" phenomenon, make splash damage when product silver ingot. The "silver rain" phenomenon weaken by using small opening standing mode. However, the narrow opening of standing mould increasing the difficulty of drainage in casting and make the production of primary silver ingots still by hand, not accord with the trend of industrial modernization. Therefore, there are important theoretical and practical significance to research the characteristics of oxygen dissolved and released, and it is extremely important to improve the production process of silver ingots through explore new technology of silver ingots product.Combined with Ag-O phase diagram and diffusion theory, analyze the microscopic behavior of oxygen dissolved and released in molten silver. The oxygen saturation solubility appear step increased after silver’s melting point, but the process not abrupt change in time. Oxygen dissolved in slow process, its release process is faster and make the "silver rain" phenomenon. Calculating the critical nucleation radius of dissolved oxygen, and its value is around 5 μm.Research on oxygen dissolved and released behavior through air-cooled experiment and water-cooled experiment, explore new technology of silver ingots casting, the results show that:The surface blowhole pits size of silver ingot get from air-cooled experiment about 1～4 mm, It indicate that the oxygen dissolved in the molten silver experience process of atomic oxygen and molecular oxygen —critical small bubbles — big bubbles. Water-cooled experiment increase the speed of solidification, "Silver rain" phenomenon was decreased significantly. The surface of water-cooled casting silver ingots compared with the air-cooled is more smooth, and the surface quality improved obviously. Ordinary nozzle in casting will appear blocking phenomenon after working a period of time, the possibility of its application in casting directly still need further study. The temperature reduced of mould surface near the water-cooled is remarkable, it could reduce the heat of the mould released to the environment when casting effectively, then reduce the environment temperature and improve the casting environment.Simulate the condition of molten liquid water-cooled through FLUENT in this paper, monitor the temperature change condition of face which the molten liquid contact with the mould and air and central-point of the molten liquid, and the temperature change condition of monitor face and point of water velocity of 0.4 m/s, 0.6 m/s,0.8 m/s and 1.0 m/s are obtained through FLUENT simulation. The simulation results show that, the molten solidification is completed at around 1.5 s, the temperature down to about 300 ℃ at around 10s, the results make a foundation for silver casting machine design.On the basis of experiment research and simulation analysis, explore the design of water-cooled casting machine preliminary, and put forward a design scheme. Make 3D modeling of the main body of the casting machine through SolidWorks. Statics analysis was carried out on parting mould and getting ingot status. Simulation results show that mould bracket stress belongs to the scope of security, the parting mechanism maximum stress belongs to the scope of security after improved. The simulation results have certain reference value to the subsequent design and research.