The Research On Technology Of Liquid Phase Diffusion Welding With Pulse Current Auxiliary Of Ti(C,N)/40Cr

Ti(C,N) based ceramic is the new type metal ceramic with high performance,whichbased on TiC base ceramic.The research on the connencton technology of dissimilarmaterials such as Ti(C,N) based ceramic to steel has far-reaching significance.In this paper,tests of liquid-solid diffusion bonding and auxiliary pulse current diffusion bonding at lowtemperature of Ti(C,N) based ceramics to40Cr steel were done.By scanning electronmicroscope (SEM),energy spectrum analyzer (EDS),and other equipment releated, theimpact of process parameters on the interface microstructure and comparison of two kindsof diffusion method were studied.In test of liquid-solid composite diffusion bonding of Ti(C,N)/Ag-Cu-Ti/Cu compositelayer/40Cr,the impact of different heat preservation time and pressureon on jointmicrostructure and properties,and the formation mechanism of the joint interface were bothstudied.The results show that:With gradual increase of pressure and holding time,diffusionlayer width gradually widened,then form the joint tightness microstructure.When heatingtemperature is880℃,holdingtime is60min,pressure is10MPa,ceramic side interface mainlyforms Ti2Cu,Ag based solid solution,(Cu,Ni) solid solution;40Cr steel interface mainly Febased solid solution.For Ti(C,N)/Ag-Cu-Ti/Cu-Ag/Cu/40Cr auxiliary pulse current low temperaturediffusion bonding, the effect of holding time on the joint microstructure studied, and theceramic side fracture is analyzed.The results show that microstructure of welding jointwelded at750℃,5min,1MPa main components is:Ti(C,N) substrate/Ti/Cu base of solidsolution+TiCu compounds based solid solution and AgCu eutectic;Compared to theliquid-solid diffusion bonding,the required temperature is reduced,and on the basis of thelow temperature,the interface high temperature and base metal low temperature weldingway realized,certainly weakened ceramic side joint tensile stress concentration,significantlyimproved the cooling rate after welding,reduced the energy consumption,shortened thewelding cycle, and improveed the welding efficiency.In the test of Ti(C,N)/Ag-Cu-Zr/Ag-Cu/40Cr liquid-solid diffusion bonding, theinfluence of temperature and heat preservation time on the microstructure of joint wereresearched.The results show that when the welding parameter is950℃,60min,10MPa,ceramic side interfacial microstructure mainly are:ZrO2,Cu(Zr,Ti),etc.Zr has good wetting and respond ability to Ti(C,N) ceramics matrix.And Zr in Ag-Cu-Zr solder spread toceramic substrate and react with ceramic generating,substitution reaction with Al2O3happened,and Al atoms is activated from Al-O ionic bond, significantly enhanced it’sdiffusion ability;Zr reacts with ceramic and metal phase,in which reduces the atomicdiffusion barrier,Ag,Cu can diffuse into ceramic substrate,concurrently formed a connectioninterface similar to the ceramic substrate.