Study On The Preparation And Performance Of Steel/aluminum, Copper/aluminum Composites

Aimed at some problems of explosive welding processed steel/aluminum electricity conducting rods, such as complication of the process, needing special equipments, high interface fracture tendency, and the performance instability of traditional electricity products with copper/aluminum bonding, the interface microstructure and conductibility of steel/aluminum and copper/aluminum composite materials fabricated by improved casting method, as well as the preparation of copper claded aluminum are studied in the present paper.It is showed that the interface with transition layer of 39μm in thickness and shear strength of 58MPa can be obtained for steel/aluminum electricity conducting rods without interlayer as the pouring temperature is 760℃, the preheating temperature of steel sample treated in a mix solution is 500℃. For a steel sample with large volume, the well-bonded interface with transition layer thickness about 20μm, interface shear strength of 72MPa and tensile strength of 45MPa can be obtained under the treatment with interlayer.Influence of application condition on the microstructure and properties of steel-aluminum electricity conducting rods obtained under the treatment without interlayer have been studied. It is showed that the interface kept a strong bonding between steel and aluminum after several heating-cooling cycles from 400℃to the room temperature. As the heating-cooling cycle was from 500℃to the room temperature, the interface bonding kept well after 4 cycles. However, Fe diffused deeper into aluminum side after 5 cycles and slight cracks were found at the interface. The interfacial cracks became serious after 8～10 cycles. The interface resistance remains 0.5-0.6μΩas employed at 400℃.To the copper/aluminum composite materials, the well-bonded interface with transition layer thickness about 45μm and shear strength of 57MPa can be obtained as the pouring temperature is 700℃and the preheating temperature for the Cu plate treated in a mix solution is 400℃. The processing parameters that affect the transition layer thickness and shear strength of copper/aluminum interface, interface microstructures and bonding properties of copper/aluminum are also studied. As suitable mix solution is employed and the pouring temperature of aluminum melt is 680℃, the Cu-Al interface is mechanically bonded and the interface bonding strength is relatively low. However, the transition interface layer will become thicker and result in low interface strength as the pouring temperature of aluminum melt is 740℃. The interface resistance of copper/aluminum composite material was measured as 0.3～0.4μΩas the pouring temperature of aluminum melt was 700℃.Under the protection of argon, copper and aluminum with glossy surface can be obtained as the preheating temperature for the copper tube is 300℃and the pouring temperature of aluminum melt is 680℃. This will play very significant roles in the further preparation of copper/aluminum composite materials.