Research Of Ultrasonic Process And Element Sb Synergistic Effect On The Joint Of Aluminum Alloy With Low Temperature

Due to the advantages of high specific strength,low price,light density,abundant reserves,good processing and strong corrosion resistance,aluminum alloy is widely used in construction,petrochemical,transportation,aviation and military equipment industries.Low temperature soldering as a high precision low temperature bonding method is widely used in aluminum alloy bonding.However,there are still many scientific problems such as the low bonding strength between filler metal and aluminum alloy,the easy oxidation of filler metal etc.Many researchers have solved these problems by modifying solder alloys and reinforcing particles,but the results have been little.For this reason,this paper focuses on the connection of filler metal modification and ultrasonic coating brazing technology,and explores the connection mechanism of filler metal and ultrasonic coating technology to aluminum alloy.In this paper,on the basis of Sn9Zn solder,the influence of element Sb content on the performance of Sn9Zn solder was systematically studied by adding Sb element with different contents.Influence of element Sb on microstructure,mechanical properties and thermoelectric properties of ultrasonic wetting 6061 aluminum alloy and low temperature soldering 6061aluminum alloy of filler metal;The influence of elements Sb with different contents on the heat dissipation process of ultrasonic wetting 6061 aluminum alloy of filler metal was systematically analyzed and observed.At the same time,ultrasonic assisted coating soldering process was used to connect 6061 aluminum alloy and the aluminum back pole of solar panel,and the optimal process parameters were analyzed and explored.In this paper,two kinds of ultrasonic soldering processes for 6061 aluminum alloy with different times of ultrasonic coating are studied and compared.The Ultrasonic coating two-step ultrasonic soldering process can refine the structure of solder,in which the structure of Sn-Zn eutectic is much smaller than that of Sn-Zn eutectic,with an average decrease of 27%;The Ultrasonic coating two-step ultrasonic soldering process can make the tensile strength of 6061aluminum alloy The microhardness of the welding layer increased by 14.5%(from 41Hv_0.3 to47Hv_0.3).The maximum tensile strength of the ultrasonic coating two-step ultrasonic soldering process soldering joint with was 230MPa.The tensile fracture of the soldering joint occurred in the solder layer and the local base metal.By adding element Sb in Sn9Zn solder,the microstructure and mechanical properties of the original composite solder were improved to some extent.The mechanical properties of Sn9Zn-Sb composite solder have been significantly improved.The tensile strength of Sn9Zn-1.5Sb solder can reach 58MPa,which is 48%higher than that of Sn9Zn-1.5Sb solder and 17%higher than that of Sn9Zn solder.Different composite filler metals have different heat dissipation rates in 6061 aluminum alloy,among which Sn9Zn-1.5Sb composite filler metal has a faster heat dissipation rate in 6061 aluminum alloy,which is about 1.8?/s.The cooling rate of the same composite solder is different at different positions.The farther away from the solder wetting spreading center,the smaller the cooling rate is,and the heat dissipation rate at the edge is about 0.4-0.7?/s.The joint of 6061 aluminum alloy soldered with Sn9Zn-Sb composite solder was studied.Al₂Zn₃ solid solution layer is formed at the interface of soldered joint,and the thickness decreases with the increase of element Sb.However,the intermediate compound Sb₃Zn₄ phase increases gradually,which leads to the decrease of the interface resistance of the joint.The interface resistance of Sn9Zn2.0Sb soldered joint is relatively small,about 0.18m?.The soldered joint of Sn9Zn1.5Sb solder alloy has good mechanical properties.The shear strength is 235 MPa,the fracture surface of the joint presents relatively uniform distribution of dimple structure,and it has good plasticity.The polycrystalline Si aluminum back electrode and 6061 aluminum alloy were soldered with Sn9Zn-1.5Sb solder.At the 220?,when the ultrasonic coating power is 350W and the ultrasonic coating insulation time is 60s,more cellular Al is distributed in the filler layer of the brazed joint,and the hardness value of the diffusion layer is relatively high,which is about96.42 Hv_0.3.The shear strength of the soldered joint is relatively high,which is about 23 MPa.