There are many ways to prepare aluminum copper bimetal sheet, which can be divided into solid-solid composite method and liquid-solid composite method. Solid solid compound method includes explosive compound and rolling compound. Solid liquid compound method mainly includes core filling continuous casting method, mold casting method and semi molten rolling compound method.
The main difficulties in preparing aluminum copper bimetal sheet are as follows: 1. Copper and aluminum are easy to be oxidized, especially aluminum, and the oxide film is difficult to be removed; 2. Copper and aluminum form intermetallic compound at lower temperature. This kind of intermetallic compound is hard and brittle, which greatly destroys the composite strength between copper and aluminum, and affects the conductivity and thermal conductivity of copper and aluminum. The semi molten rolling compound method can solve the two problems in the process of copper aluminum compound ingeniously. When the liquid aluminum is cooled and crystallized to semi molten state, the two metals are combined under the action of large rolling force. Under the action of high temperature and high pressure, there is interface interaction between copper strip and semi molten aluminum, and the interface interacts several times in a short time, which solves the problems of oxidation and eutectic in the process of copper aluminum composite. On the basis of good composite strip blank, the copper aluminum composite rolling process and the corresponding annealing process were studied, and the copper aluminum composite strip and foil were industrialized.
The semi molten rolling technology solves the key technology of oxidation and eutectic in copper aluminum composite technology, realizes the metallurgical combination between copper and aluminum, and realizes the production of copper aluminum composite plate, strip and foil by matching copper aluminum composite rolling technology and annealing process system, which is the inevitable trend of copper aluminum composite preparation in the future.
In recent ten years, the rise of copper price accelerates the development of copper aluminum composite, The application field of this technology is also gradually expanding. The main common fields are heat conduction, communication, power, etc.
1. Application on the heat dissipation substrate of high power LED package
2. Application in the field of radiator fins
Copper aluminum composite fin is superior to pure copper in cost and comprehensive heat dissipation performance. It has broad promotion prospects in electronics, communication, computer, PLC, gas water heater, air conditioning and refrigeration industry.
3. Application in cable industry
The inner and outer conductors of RF cables and leaky cables conduct high-frequency weak current signals, and the signal attenuation is the main performance control index. The shielding cable foil used for control cable and computer cable can prevent mutual interference between communication signals and ensure normal communication. The shielding performance of signal is the main performance index. In high-frequency signal transmission and shielding, due to the skin effect, only the surface copper plays the role of signal transmission, and the attenuation of copper aluminum composite tape is close to that of pure copper, while the performance of aluminum can not be compared with that of copper, and it can not meet the demand when the shielding performance is higher.
4. Application in power industry
The requirements of electric power industry for aluminum copper bimetal sheet are mainly in four aspects: electrical performance, mechanical performance, processing performance, safety and reliability. The surface copper of copper aluminum composite strip is hot rolled open billet, the internal structure is compact, and the mechanical properties and electrical conductivity are better than those of as cast structure. The bonding strength of copper aluminum composite strip is high, and the state of composite strip can be adjusted by heat treatment. The mechanical properties and machinability of composite strip are no different from those of pure copper strip. Due to the characteristics of copper and aluminum, the traditional fusion welding can not be used in the welding of copper aluminum composite, which is suitable for the common brazing process of composite. The development of medium temperature brazing technology is closely related to the popularization and application of copper aluminum composite strip. As a conductor material, the electrical performance of copper aluminum composite strip can be adjusted by the cross-sectional area and the volume ratio of copper to aluminum, which can meet the requirements of electrical performance. In terms of safety and reliability, copper aluminum strip has passed the high and low temperature performance test, and the composite performance, electrical performance and mechanical performance have not changed.
5. Copper aluminum composite transition material
Aluminum copper bimetal sheet is widely used in the electrical industry with a wide variety, including transformer copper aluminum transition device connector, copper aluminum equipment clamp, reactor and transformer connection bar. At present, friction welding, diffusion welding, flash welding, explosive welding and other processes are mainly used for copper aluminum composite joints.
