Fabrication And Mechanical Properties Of Cu/Ti₃SiC₂ Co-continuous Composites

The ternary layered ceramic material Ti₃SiC₂combines the excellent properties of ceramics and metals,and Cu has excellent heat transfer,plasticity,toughness and other properties.With Cu as the metal matrix and Ti₃Si C₂as the reinforcing phase,it is designed as a Cu/Ti₃Si C₂cermet with a dual continuous structure,which can meet the requirements of light weight,high strength,ablation resistance,wear resistance and good interface bonding in the field of aerospace engineering.In this paper,firstly prepare high-purity porous Ti₃Si C₂preforms with different porosities,and use pressureless infiltration methods to prepare dual continuous phase Cu/Ti₃Si C₂composites with different processes.Through X-ray diffraction analysis(XRD),scanning electron microscopy secondary electron analysis(SEM),backscatter analysis(BSE),energy spectrum scanning analysis(EDS)and other experimental equipment,the phase changes and microscopic morphology changes of a series of dual continuous phase Cu/Ti₃Si C₂composites are analyzed.Finally,the relationship between the microstructure change and the performance change in the dual continuous phase cermet composite material is summarized.The research results indicate that:(1)Using Ti powder,Si powder,Al powder,and Ti C powder as raw materials,through the in-situ reaction sintering method,holding at 1440?for 20 min and 90 min,respectively,high-purity porous Ti₃Si C₂preforms can be obtained.The apparent porosity of the Ti₃Si C₂preform prepared under the two holding times is 34%and 25%,respectively.(2)When the infiltration temperature is 1200?,the holding time is 1 h,1.5 h and2 h to prepare the dual continuous phase Cu/Ti₃Si C₂composites.The interface between the Cu solution and Ti₃Si C₂reacts violently in a high temperature environment,and this reaction process will corrode the ceramic framework to a certain extent.The edge part of Ti₃Si C₂is decomposed to generate Ti Cx particles,and the Si atoms desolved from the a site are free to enter the Cu solution to form Cu(Si)solid solution.(3)By adjusting the impregnation process,it is possible to reduce micro-cracks caused by violent interface reactions.In the process of impregnation temperature of1090?,heat preservation for 1 h,Cu/Ti₃Si C₂cermets with bi-continuous structure,compact structure and firm interface were prepared,each exhibiting a three-dimensional network structure and interlacing each other.Among them,only part of Ti₃Si C₂and Cu react and decompose to generate Ti Cx particles,which ensures the integrity and continuity of Ti₃Si C₂.(4)The change of the infiltration process and the metal content have a significant impact on the micro morphology and properties of Cu/Ti₃Si C₂composites.As the holding time is extended,the Cu solution gradually fills the pores,and the density and performance of the composite material will be improved.When the porosity of the preform is low,the composite material favors ceramic properties;otherwise,it favors metal properties.(5)The dual continuous phase Cu/Ti₃SiC₂composite material prepared by the pressureless infiltration method has excellent mechanical properties.Among them,the34Cu/Ti₃Si C₂composite prepared at the impregnation temperature of 1200°C and holding for 2 hours has a compressive strength of 1190 MPa and a fracture strain of13.5%.The density of 25Cu/Ti₃Si C₂composite prepared at the impregnation temperature of 1090?and holding for 1 hour is up to 99%,the fracture toughness reaches 13.08 MPa·m^1/2,and the maximum bending strength reaches 827.5 MPa.