Reactive Synthesis Of Polycrystalline Ti₃AlC₂ And Its Sintering Mechanism

Ti3AIC2 is a new type of ceramic material, which combines the properties of ceramic and metal. Having good sintering properties, machinability and self-lubricating characteristics, in the field of low coefficient of friction materials, high temperature structural materials and electrical contact materials have wide application prospects.This paper studied the reactive synthesis of Ti3AIC2 powder and its sintering mechanism.Ti3AlC2 powder is calcined from Ti, Al, TiC materials by high temperature, Si, Sn powders act as addictives. This paper discussed the influence of the milling process, calcination temperature, holding time, material ratio and additives on the preparation of high purity Ti3AIC2 systematically. A hot pressing method was adopted to reasearch the sintering behavior of Ti3AlC2 powder at different temperature. Different properties were obtained from bulk Ti3AlC2, such as hardness, relative density, electrical conductivity and flexural strength. The reaction mechanism and the microstructure evolution of Ti3AlC2 prepared at different temperature were investigated by X-ray diffraction and scanning electron microscopy.Results indicate that high-purity Ti3AlC2 powder was obtained at 1300℃ with 30 min, the molar ratio of TiC/Al/C is 1:1.2:2. Additives of Si, Sn can improve the purity of Ti3AlC2 powder by reduce the calcining temperature and the amout of TiC. The typical laminated structure of Ti3AlC2 appeared at 1300 ℃, The grain size and the laminate thickness increase with the increasing temperature. We get some select electron diffraction pattern and high-resolution micrograms of Ti3AlC2 material along the direction of [0001] and [1120], and analyzed the crystal structure of Ti3AlC2.The bulk samples sintered by hot pressing were using the Ti3AlC2 powder. After hot pressing of different temperature, the fully dense of bulk Ti3AlC2 showed better properties prepared at 1300 ℃. The density of bulk Ti3AlC2 reached to 99.9%. The average Vickers hardness was around 5.7 GPa, and the maximum flexural strength was 630 MPa.