Preparation process of silver clad aluminum bars by vertical continuous casting composite forming

Silver clad aluminum composite wire, which combines the high electrical conductivity of silver-coated metal, good welding performance, and low density, has wide application prospects in aerospace and other fields. The preparation of silver clad aluminum bars with high surface quality and good combination of interfaces is an important step in the preparation of silver clad aluminum wire with excellent performance. Continuous casting composite forming is a short, high-efficiency material-forming process, which provides methods for the preparation of silver clad aluminum. The boundary conditions of the vertical continuous casting process of silver clad aluminum composite rod that has a diameter of 20 mm and cladding ratio of 50% were established through finite element numerical simulation using the ProCAST software and corresponding experiments. The effect of each process parameter on continuous composite casting was analyzed, based on which the optimized control method was obtained. A silver clad aluminum composite rod with high surface quality and excellent bonding interface was prepared on the basis of the simulation results. The length of the core tube and the speed of continuous casting are considered to be the most important factors affecting the formation process. The length of the core tube is assumed to affect the contact temperature and time of the aluminum liquid and silver tube at the end of the core tube, and result in the variation of the relative position of the solid-liquid interface of the aluminum. The interface reaction is severe when the core tube is too short. Conversely, significant cold separation occurs in aluminum because of the high cooling intensity when length of the core tube is too large. The actual casting temperature increases with the high continuous casting speed, which can be attributed to the reduction in the distance between solid-liquid interface and the outlet of the core tube for silver and the increase for aluminum. The increase in aluminum casting temperature and reduction in the flow rate of cooling water are found to have a similar effect to that of the increase in continuous casting speed. A series of optimized casting parameters was obtained in this study, i.e., length of the core tube 30 mm, the casting speed is 37-67 mm·min^-1, the casting temperature of silver is in the range between 1225℃ and 1325℃, casting temperature of aluminum is 800℃, and the flow rate of cooling water is 300 L·h^-1.