Microstructure And Properties Of Al-Si/Ti 3 SiC 2 Composites Prepared By SPS Sintering

Al-Si alloy is widely used in axle,piston,engine,brake block and other wear-resistant parts because of its good casting performance,such as good physical properties,good chemical properties and good corrosion resistance.With the development of the industry,the traditional Al-Si alloy in the performance can't keep up with the pace of industrial development.As early as the late 70 s of last century,Japan have embarked on the development of aluminum oxide short fibers local reinforced aluminum alloy,hoping that the new kind of material can replace the traditional ordinary aluminum piston.Subsequently,to prepare high-performance wear-resistant materials people are constantly exploring in the Al-Si alloy to add Al2O3,aluminum silicate,aluminum borate,graphite,etc.Compared with those familiar external reinforcements,the new three-dimensional layered ceramic MAX phase not only has high hardness,high thermal conductivity,good electrical conductivity,but also has good self-lubricating properties.Therefore,it is very important to study the preparation of MAX/Al-Si composites for the enrichment of aluminum-based piston materials,and it is of great significance to promote the application of MAX.In this paper,Al-Si/Ti₃SiC₂ self-lubricating composites were prepared by SPS?spark plasma sintering?method.Microstructures of the composites were investigated by using Scanning Electron Microscope?SEM?and Optical Microscope?OM?.Also,chemical reaction products were studied by X-rd.The propertie of the sintering process?sintering temperature,sintering time,sintering pressure?and the influence of the content of Si and Ti₃SiC₂ on the microstructure and properties of Ti₃SiC₂/Al-Si composites were investigated.Meanwhile,the effect of heat preservation on the interfacial reaction product and microstructure of 10%Ti₃SiC₂/Al-Si composites with different Si contents were also studied.The main results are as follows:?1?The sintering temperature and pressure have great influence on the Al-10Si/10%Ti₃SiC₂ properties of the composite,and the effect of sintering time on the properties of the composites is not obvious.The higher the temperature and pressure,the better the density and hardness of the composite.The optimum preparation conditions were as follows: sintering temperature 525 ?,pressure 40 MPa,sintering time 10 min.The diffusion reaction does not occur at the interface between Ti₃SiC₂ and the matrix at 525?.?2?The change of silicon content has a significant effect on the microstructure and properties of 10%Ti₃SiC₂/Al-Si composites.With the increase of silicon content,the grain size of the composites becomes smaller and the density changes little,but the hardness of the composites was greatly improved.The addition of Ti₃SiC₂ significantly reduced wear of the composite material,while the friction coefficient of the material also decreases.Al-20Si/10%Ti₃SiC₂ had best comprehensive properties.?3?In the range of 500?-700?,the change of silicon content will affect the morphology of Ti₃SiC₂ of 10%Ti₃SiC₂/Al-Si composites.The Ti₃SiC₂,which uniformly distributed in the Al-4Si/10%Ti₃SiC₂ and Al-10Si/10%Ti₃SiC₂,grows into a strip-like structure.When the temperature was raised to 600 ?,the reaction between Ti₃SiC₂ and aluminum matrix generation of Al₄C₃ and TiC.In Al-20Si/10%Ti₃SiC₂ composites,Ti₃SiC₂ does not undergo slab growth with the rise of holding temperature,and Al₄C₃ and TiC are formed in the matrix when the temperature is 500?.?4?In Al-10Si/Ti₃SiC₂ composites,the density of the composites decreases with the increase of Ti₃SiC₂.The density of the composites decreases rapidly when the content of Ti₃SiC₂ exceeds 10 Wt.%.The addition of Ti₃SiC₂ can improve the hardness of the composites.The wear amount of the composites decreases slightly with the increase of the particle.At the early stage of the friction,the addition of Ti₃SiC₂ has no obvious effect on the friction coefficient.At the later stage of the friction test,the addition of Ti₃SiC₂ significantly reduces the coefficient of friction of the material.