Preparation And Properties Of Layered Ceramic Ti₃AlC₂

New-type layered Ti3AlC2 materials show unusual characteristics of both metals and ceramics. It not only presents good thermal, electrical conductivity and machinability as metal but also excellent mechanical properties and corrosion resistance as ceramics. Ti, Al, graphite and TiC powders used as the raw materials, high-dense Ti3AlC2 materials were prepared by hot pressing in this work. The relation between the composition, structure, properties and application of Ti3AlC2 materials was established by investigation on the phase composition, microstructures, mechanical properties and corrosion behavior. This study can boost the development of the preparation and application in the field of ship and marine corrosion-structure laid.Two group of bulk Ti3AIC2 matrials with different molar ratio, e.g., 3Ti/1.1Al/2C/0.2Si and 2TiC/1Ti/1.1Al/0.2Si, were prepared at 1200-1400℃, 30MPa pressure by vacuum hot pressing sintering. It indicted that the 2TiC/1Ti/1.1Al/0.2Si material system properties were superior to 3Ti/1.1Al/2C/0.2Si material system by analysis of the mechanical properties, phase, and microstructure.The optimal processing parameters, e.g., sintering temperature 1300℃, vacuum 6.67x10-3 Pa, heating rate 15℃/min, pressure 30MPa, soaking time 1.5h, were adopted to obtain the bulk Ti3AIC2 matrials from the raw materials 2TiC/1Ti/1.1Al/0.2Si. The x-ray diffraction of Ti3AlC2 was well concided with that of the standard Ti3AlC2 and Ti3AlC2 showed layered structure. The mechanical test implied that the flexural strength, fracture toughness, compressive strength and Vickers hardness were 445.6MPa,6.13MPa-m1/2,1256MPa and 4.0-5.5GPa, respectively.The electrochemical corrosion behavior of Ti3AlC2 in the 3.5% NaCl solution was also investigated by means of potentiodynamic polarization curves (CV) and SEM in this work. It indicated that no corrosion pits were found on the surface of the Ti3AIC2 bulk material after electrochemical corrosion. Among all Ti3AIC2 bulk materials prepared by the raw materials 3Ti/1.1Al/2C/0.2Si, the blunt-dimensional current density in 3.5% NaCl solution, e.g.,2.197x10-5 A-cm"2, can obtained from the sample prepared under the 1400℃sintering temperature. Moreover, its blunt-dimensional current density is most stable and shows the best corrosion resistance.