Preparation Of Molybdenum Matrix Interconnect Sheet Materials And Simulation Of Resistance Welding Process

Spacecraft solar array interconnects usually use metal Ag as interconnect material.However,because of the existence of atomic oxygen and thermal cycling on the low earth orbit,Ag is prone to crack and continue to be ablated,eventually falling off,which greatly affects the service life of the aircraft.In the previous work,The Mo/Ag layered composites which meet the performance requirement of the long-life spacecraft solar cell interconnection sheet have been prepared by the irradiation damage alloying method,but the efficiency of preparation process is low and its welding performance is inferior to that of the pure Ag.In order to increase productivity furtherly,the Mo/Pt/Ag layered metal matrix composites were prepared by adding the intermediate layer,but the surface activity of the metal Mo was too low,which make the bonding strength of Mo/Pt interface low.In order to solve above problems and improve the bonding strength of Mo/Pt interface,in this paper,a nanoporous metal layer with a thickness of about 200 nm is prepared on the surface of Mo by de-alloying.The metal layer had a typical hole and ligament structure.Then,by the processes of plating,annealing and calendering,the Mo/Pt/Ag metal matrix composites with good interfacial bonding strength were obtained.The SEM?EDS analysis and tensile tests show that the Mo/Pt/Ag layered composite prepared by de-alloying for 2.5 h,then electroplating,calendering and annealing,has the highest tensile strength.The highest tensile strength was 330 gf,and the average was 247.5 gf,and has good plasticity,which meet the national army standard GJB2602-1996 and 160 gf of space requirements raised by users.And the problem of foaming in the process of silver plating is solved by the method of layered platingIn addition,the ANSYS software was used to simulate the temperature field of Mo/Ag layered composite and GaAs cell in single-side double spot welding process.By preloading analysis,it was found that there was no significant change in the contact area during the welding process due to the small squeezing force and the flat end of the electrode.Thus,the length of the contact resistance during electrical-thermal analysis assumed to be constant was reasonable.Based on the results of pre-loading analysis,a thermo-electric coupling model is established to simulate the temperature field during the resistance welding process and the current shunt phenomenon in the welding process.It was found that,at the early stage of power supplied,the temperature of the contact area increased rapidly due to the large contact resistance,and the temperature rise was slow due to the decrease of contact resistance at the late stage.Moreover,due to the edge effect of the current,the current density in the contact region is a double-bucket-shaped distribution.At the beginning of the power-on,the ratio of welding resistance to total resistance is small,and the shunt phenomenon of single-sided double-spot welding is serious.With the temperature increases,the contact resistance decreases and the shunt phenomenon is gradually reduced.Finally,by comparing the measured results with the simulated results,the feasibility of the finite element model and the selected method is verified.