Study Of Bonding And Joint Performance Controling On SiC Ceramics/316L Stainless Steel

In order to achieve ceramic packaging and make anti elastic armor modules,the diffusion welding and brazing of SiC and 316L stainless steel were studied in this paper.The difficulties in welding SiC and steel are mainly concentrated on the poor wettability and excessive residual stress of the joint,so the property of the joint is poor.In this paper,diffusion welding and brazing method are used to connect SiC ceramic and 316L stainless steel.By studying the interface structure of welded joints,Analyzing the influence of different processing parameters on the interface and mechanical properties of welded joints,Exploring the method of relieving the stress and improving the property of the joint.Ti foil,Ti-Ni-Ti and Ti-Cu-Ti are used for diffusion bonding between SiC and 316L diffusion welding.When Ti foil is used as an intermediate layer,no reliable joint is formed.When Ti-Ni-Ti is used as the middle layer,the welding temperature is 1080?,and the pressure is 10 MPa,the mechanical properties of the joint are the best and the shear strength is 10.8MPa.When Ti-Cu-Ti is used as the middle layer,the mechanical properties of the joint are the best when the welding temperature is 1020?,and the pressure is 5MPa,and the shear strength is 18.4MPa.The difference of thermal expansion coefficient of the base material is the key factor affecting the property of the joint.When SiC is connected with SiC ceramic,the residual stress and strength of the joint are uniform due to the same base material.The shear test is broken at the base of ceramic,and the strength of the joint is 115.7MPa.Due to the large difference of thermal expansion coefficient between 316L and SiC ceramics,the residual stress caused by cooling process affects the property of joints of SiC ceramics and 316L stainless steel brazing joints.The maximum shear strength of Ag-Cu-Ti brazed SiC ceramic and 316L stainless steel joint is 32.4MPa,and the welding temperature is 900?.In order to relieve the residual stress and improve the property of the joint,the effects of SiC ceramic nickel plating,the addition of second phase particles,the preparation of composite solder,the addition of transition intermediate layer and the composite intermediate layer on the properties of the joint were studied.The experimental results show that ceramic nickel plating does not increase the shear strength of ceramic joints.Adding proper amount of TiC particles to the solder can reduce the thermal mismatch between solder and ceramics and relieve the residual stress of joints.However,the addition of excessive TiC enhances the strength of joints.When adding 5vol.%TiC to enhance the particle,the strength of the joint obtained at 900 ? for 20min is the highest,which is 35.6MPa.The method of using interlayer as a middle layer can relieve the residual stress and improve the mechanical properties of the joint.When the thickness of the intermediate layer is 0.3mm,the property of the welded joints obtained at 900? and 20min is the highest,34.1MPa.Ti+ Kovar Alloy as the middle layer to make up for the consumption of only Ti elements Kovar Alloy interlayer,and improve the property of joints,adding 20?m Ti at 930? foil obtained by 20min welding joint shear strength reached 54.6MPa,increased 68%with the Ag-Cu-Ti solder joint.