Microstructure Characterization And Tribology Properties Of Ti₃AlC₂ceramic Fabrication By Spark Plasma Sintering

In the thesis Ti₃AlC₂materials were synthesized by spark plasma sintering taking theTi, Al and C powders as raw material, based on the molar ratios of raw material:Ti:Al:C=3:1:2. Effects of sintering temperature and pressure on the phase compositionsand microstructure of sintered samples were investigated by the X-ray diffraction (XRD),scanning electron microscopy (SEM) and transmission electron microscopy (TEM), etc.The optimization of sinter factors and raw receipts were studied.The properties of sintered products, such as Rockwell hardness, thermal conductivity,thermal expansion coefficient, electric conductivity were investigated using TheWilson-2000Rockwell hardness tester, Physics Property Measurement System, Laserthermal conductivity meter and DIL-402C Thermal expansion coefficient apparatus. Thetribology properties of Ti₃AlC₂ceramic have been researched using CFT-I Materialsurface performance comprehensive test instrument.The results show that the optimization parameters of the Ti₃AlC₂ceramic by sparkplasma sintering are that the sintering temperature1300℃, sintering pressure30Mpaunder the raw ratio of3:1.05:2(Ti:Al:C). The density of the product is about4.19g/cm3detected by Archimedes Principle, which is98.6%of the theoretical density. Thesynthesized Ti₃AlC₂ceramic is dense, and the grain shape is near bar-shaped with thelength in the range of10¹5μm. TEM reveals that the grain boundaries between Ti₃AlC₂and Ti₃AlC₂are distinct and intact. The Rockwell hardness of Ti₃AlC₂is around2.07GPa,and a bit plasticity was observed. The radial electric conductivity of the sample is about2.78×10⁶S/m and the axial electric conductivity is about1.98×106S/m. The thermalconductivity of Ti₃AlC₂sample is25.5W/(m·K) between200⁸00℃. The coefficient ofthermal expansion is8.365×10^-6K-1.In this paper, the friction coefficient of Ti₃AlC₂materials is in the range from0.12to0.51. The friction coefficient decreases at first and then increases as the load increasesunder the same sliding velocity. The friction coefficient reaches to the minimum at thevelocity of2.0m/s and load of20N (f=0.12). As the velocity increasing, the friction coefficient decreases when keeping the load constant. The wear rate shows increasingtrend as the loads and velocities increase. The wear rate increases sharply under theconditions of high velocity and heavy load, it was found that the maximum was0.09mg/s.In the low velocity and load, the main wear mechanism is abrasive wear. With the increaseof load and velocity, the wear mechanism is abrasive wear and adhesion wear.