Interface Structure And Properties Of Ti₃SiC₂ Ceramic And Fe Diffusion Bonding Joint

Ti₃SiC₂ ceramics have many advantages,such as good thermal properties,high strength,low density and easy processing,which have attracted many scholars’attention.However,due to the brittleness of Ti₃SiC₂ ceramics,it is difficult to fabricate large scale components.It greatly limits its application.Connecting it with other metal materials can produce large and complex components that meet the needs of industrial production.However,the physical,chemical and mechanical properties of Ti₃SiC₂ ceramic materials are greatly different from those of metals,so it’s hard to get the ideal interface.Therefore,it is of great practical significance to study the bonding between Ti₃SiC₂ ceramic materials and metals.In this paper,the diffusion bonding method is used to realize the connection between Ti₃SiC₂ ceramics and Fe.The Ti₃SiC₂ceramics and Fe are studied by means of XRD,SEM,EDS and are sheared property test.Diffusion bonding interface structure,microstructure and reaction mechanism of Ti₃SiC₂ceramics and Fe joints were studied.The influence of different bonding parameters on the shear strength of Ti₃SiC₂ ceramics and Fe joints was analyzed.The experimental results show:（1）The diffusion bonding between Ti₃SiC₂ ceramics and Fe was realized under the conditions of pressure 10-20 MPa,temperature 850-1050℃and time 60-120 min.The interface structure of Fe（Si）/TiC_x+Fe₃Si/Fe₂Ti+FeSi₂Ti+Fe₃Si+TiC_x+Ti₃SiC₂/Ti₃SiC₂ was formed at the interface of Ti₃SiC₂ ceramics and Fe₃Si,TiC_x,Fe₂Ti and FeSi₂Ti.The thickness of the interface structure is increases with the increase of diffusion temperature and diffusion temperature.（2）The growth rate of the interface reaction layer between Ti₃SiC₂ ceramics and Fe increases with the increase of temperature,and the growth rate of the interface reaction layer satisfies the parabola rule.The activation energies of the reaction layer between Ti₃SiC₂ceramics and Fe at 10 MPa and 20 MPa pressure are Q₁=240 kJ/mol and Q₂=287 kJ/mol,respectively.The growth formulas of the inter facial reaction layer X²=4.4×10^-3exp（-240/RT）t and X²=2.8×10^-4exp（-287/RT）t is obtained.`（3）The influence of process parameters on the strength of Ti₃SiC₂/Fe joints:When holding time is 120 min,the average sheared strength of joints increases first and then decreases with the increase of junction temperature from 850 to 1050℃,and the maximum shear strength is 51MPa at 950℃.At the joining temperature of 950℃,with the increase of holding time from 60min to 120 min,the average sheared strength of the joint increases first and then decreases gradually.The maximum shear strength of the joint is 60 MPa at 90 min,and the effect of connection pressure on the shear strength is positively correlated.The optimum connection condition is 20 MPa,950℃,90 min,and the shear strength of the joint is 60 MPa.（4）The shear fracture analysis of Ti₃SiC₂/Fe joints shows that when the bonding temperature and time are small,the interface reaction layer is thin,the metallurgical bonding strength is not high,and the fracture position of the joint mainly occurs in the middle layer of the interface with weak reaction and the interface of metal Fe.When the bonding temperature,time and pressure are moderate,the interface reaction is relatively adequate,the bonding strength is high,and the shear fracture occurs between the Ti₃SiC₂ ceramics and the interfacial reaction layer,the corresponding fracture strength of the joint is higher.