| As radar technology continues to evolve,the requirements for its cooling system are increasing.The mechanically sealed water hinge with high reliability and good sealing has become the main trend of development.The water hinge requires a high hardness and high wear resistance ceramic as a friction pair material,and a metal material having good workability is used as a casing material.SiC ceramics are ideal materials for friction pairs due to their high hardness,good wear resistance and corrosion resistance.FeNi42 alloy is an ideal material for water hinge housings due to its low thermal expansion coefficient matched with SiC ceramic.The reliable connection of the two is an effective guarantee for the sealing and mechanical properties of the water hinge.In this paper,Ag-Cu-Ti brazing filler metal is used to realize the brazing joint of FeNi42 alloy and SiC ceramic.The effects of Ti content and brazing temperature change on the mechanical properties of interface structure and joint are studied.The surface reaction and internal dissolution of SiC ceramic were analyzed and ceramical reaction process was analyzed.The effects of three elements of Ti,Fe and Ni on the dissolution of ceramics were investigated,and the composite intermediate layer was designed to inhibit the dissolution of ceramics to control the microstructure and properties of brazed joints.When Ag-Cu-2.5wt.%Ti solder is used to braze FeNi42 alloy and SiC ceramic,when the brazing temperature exceeds 900?,SiC ceramic dissolves under the action of Fe and Ni dissolved in liquid solder,which leads to The mechanical strength of the joint drops sharply.When Ag-Cu-4.5wt.%Ti brazing filler metal is used,the Fe and Ni elements dissolved in the liquid brazing filler metal mainly react with the Ti element in the brazing filler metal to form Fe-Ni-Ti compound,and the SiC ceramic reacts with Fe and Ni elements.To a lesser extent,no dissolution occurs in the temperature range of 840?-920?.When the brazing temperature is 880°C and the brazing filler metal content is 2.5wt.%,the brazed joint has a maximum shear strength of 60MPa.The evolution process of the tissue is divided into three stages,Ti-first and surface reaction stages of ceramic reaction,Fe and Ni preferential and surface reaction stages of ceramic reaction,and ceramic dissolution stage.An increase in the Ti content promotes the formation of a ceramic interface TiC layer,thereby hindering the dissolution of the ceramic.The detachment of the SiC particles on the surface of the ceramic substrate can reduce the formation of the TiC layer at the interface of the ceramic substrate,thereby promoting the dissolution of the ceramic.It is known from the FeNi42/Ag-Cu/SiC brazing test that the dissolution of Fe and Ni into the solder and the reaction with SiC are independent of the Ti element.In the brazing temperature range of this experiment,Fe/Ag-Cu-Ti/SiC reacted with ceramic surface,and ceramic dissolution occurred in Ni/Ag-Cu-Ti/SiC brazed joint.It is speculated that the second stage of microstructure evolution of FeNi42/Ag-Cu-Ti/SiC brazed joint is dominated by Fe element,and the third stage is dominated by Ni element.The Ag-Cu/Cu/Ag-Cu-Ti composite interlayer can effectively block the dissolution and diffusion of FeNi42 alloy and the dissolution of SiC ceramic.The brazed joint has shear strength of 50MPa in the brazing process window of 840?-920?. |
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