Research On Dynamic Bonding Behavior And Bonding Performance Of Cold Rolled Cu/AI Composite Plate Based On Surface Treatment

Pure copper is widely used in automobile,aerospace and other fields due to its excellent thermal conductivity,electrical conductivity and corrosion resistance.However,its use cost is higher because of the lack of resources.Cu/Al composite plates have been widely concerned by scholars as the substitute materials.In this paper,the research was carried out on the preparation of Cu/Al composite plates by cold rolling technology.Using ABAQUS software to analyze the influence of inter-plate friction coefficient and pre-adding residual stress on the rolling process of Cu/Al composite plate.The surface treatment of slabs was performed by three processes of wire brush grinding,shot blasting processing and integrated surface treatment(wire brush + shot blasting).The effect of the mechanical surface treatment process on the surface state of the original slab,the rolling bonding efficiency,the interface structure of the composite plate and the bonding performance was studied systematically.The dynamic bonding process and bonding mechanism of the Cu/Al composite plates were analyzed through a sudden stop during the rolling experiment.The surface treatment process before rolling was optimized and deeply analyzed.Finite element simulation results showed that increasing the friction coefficient of the interface can promote the simultaneous deformation ability of Cu and Al.While increasing the friction coefficient,the greater rolling force was required under the same reduction ratio,and the degree of plate warpage was more significant.In the pre-applied residual stress simulation process,the pre-pressure stress on Cu plate and the pre-tension stress on Al plate can improve the shape of the composites and improve the deformation coordination ability between Cu and Al.The experimental results showed that different mechanical surface treatments had significant effects on the slab surface morphology,roughness and residual stress.After mechanical polishing,the surface of the slab formed a scaly scratch and a working hardened layer,and the surface stress condition and roughness will change obviously.After shot blasting,the surface was uneven and had high surface roughness and surface residual stress.After comprehensive treatment,the surface morphology of slab had the characteristics of both polishing treatment and shot blasting treatmentAfter mechanical polishing,Cu and Al bimetal showed the optimal cold rolling bonding efficiency,and the critical bonding compression rate was 35%,far lower than that of shot blasting(45%).In addition,the composite plate prepared by this process also showed the optimal interface bonding performance,and the tensile and shear strength reached 78 MPa,which was 26% higher than the composite plate prepared by the shot blasting process.After the comprehensive surface treatment combined with two surface treatment methods,Cu/Al composite plate with the same pressing rate showed the medium bonding strength,and the morphology of the stripping interface also exhibited the morphology characteristics of the two surface treatment methods.Through a sudden stop during the rolling experiment,the effect of different surface treatment methods on the dynamic cold rolling bonding process of Cu/Al composite plate was studied and the bonding mechanism was analyzed.During the rolling process,the hard and brittle layer on the metal surface cracked,and the softer Al was squeezed into the Cu-side and contacted with the fresh Cu metals.Under the action of the rolling force,a stable bond was formed.The high-strength combination of the cold-rolled Cu/Al composite plate is the result of the comprehensive effects of surface morphology,surface roughness and surface residual stress.The scaly scratches on the surface of the slab along the rolling direction and the smaller compression residual stress were conducive to the cracking of the surface metals.Appropriate roughness had a positive effect on the contact length and contact pressure during the rolling process to improve the bonding strength of the composite plate.Through comparative analysis,it can be seen that the mechanical polishing process of wire brush had a better effect on the cold rolling combination of Cu/Al composite plate than the other two surface treatment methods.The bonding strength of the Cu/Al composite plate made by steel wire brush mechanical polishing process was higher than that of the shot blasting treatment and comprehensive surface treatment.After the wire brush with a diameter of 0.3mm was polished in the rolling direction for 20 seconds,the Cu/Al composite plate showed the highest tensile shear strength(78MPa),about four times that of the untreated sample.