Fabriation Of Ti₃AlC₂ Cermics By Self-propagating High-temperature Synthesis

Ti3 AIC2 is a novel structural and functional material which combines the merits of both metals and ceramics. Like metals, they are highly thermal and electrical conductive, a lower Vickers hardness, easy to be machined with conventional tools without lubrication, and well resistant to thermal shock; like ceramics, they present a high strength, high melting point and thermal stability. Besides the listed properties, it is self-lubricative, and has lower friction coefficient that is even less than those of graphite and MoS2. Based on these unique properties, the application prospect of Ti3AIC2 is extremely extensive and highly attractive. Till now, a variety of sintering methods have been adopted to synthesize Ti3AIC2, such as SHS (self-propagating high-temperature synthesis), hot-pressing (HP), hot isostatic pressing (HIP), spark plasma sintering (SPS) and so on. Self-propagating high-temperature synthesis process compare to others, however, which is simple, low cost, high purity, and the reacting substance will not need to provide any energy when it is ignited. So we conducted the research on the fabrication of Ti3AlC2 ceramics by SHS.In this paper, the commercially available powders of Ti, Al and C as raw materials, we studied the effect of TiC additive on the Ti3AIC2 phase formation by self-propagating high-temperature synthesis, meanwhile adjusting content of Al, we can systhesize the single-phase Ti3AlC2 ceramics; By using Ti, Al, C and TiC powders as raw materials, the as-synthesized Ti3AlC2 was studied by SHS with doping different content of Si and adjusting content of Al, X-ray diffraction (XRD), scanning electron microscope (SEM) coupled with energy-dispersive spectroscopy (EDS) and differential scanning calorimetry (DSC) were utilized to investigate the phase compositions, the morphology characteristics of the products and the reaction mechanism, Si is an effective additive and its effect on the formation of Ti3AIC2 ceramics has been discussed.The experiment results show that the single-phase Ti3AlC2 ceramics with high purity and density was synthesized by self-propagating high-temperature synthesis from the mixture powders with the starting off-stoichiometric mole ratios of 2Ti/1.1Al/C/0.9TiC and 2Ti/1.2Al/C/0.9TiC/0.1Si under the pressure of 50MPa in air atmosphere. The mass ratio of steel balls to elemental powder is 10:1, with milling speeding of 150rpm, mixing time for 4 hours. By using Si as an additive can effectively inhibite formation of Ti2AlC.