Study On Tantalum Carbides Synthesized At High Pressure And High Temperature

Refractory transition metal carbides are of great interest in bothcivilian and military applications because of their unique combination ofphysical and chemical properties and potential applications, such ascutting tools, grinding and ablation resistant coating, etc. The Ta-Csystem in our work is a kind of potential refractory ceramic material. Thetantalum carbon compounds were synthesized firstly under the conditionof high temperature and high pressure by using domestic SPD-6×600Tcubic anvil apparatus, determining the forming conditions of each stage.The synthetic samples were tested by X-ray diffraction and scanningelectron microscopy. Besides, the hardness and resistivity of TaC andTa2C were determined by AHVD-1000XY Vicker’s indentation testmachine and Van der Pauw method, respectively.In this paper, we use high pressure and high temperature method tosynthesize tantalum carbon compounds in SPD-6×600T cubic anvilapparatus. The raw materials are tantalum power (purity99.9%) andgraphite power (purity99.9%), and mixed the tantalum power andgraphite power uniformity in a stoichiometric ratio, at suitable pressureand temperature conditions to synthesize TaC and high purity Ta2Csuccessfully. By this method, we do not use any fluxing agent, mainlyusing the different ratio of raw material, synthetic temperature andpressure to adjust the tantalum carbide material composition and purity,inhibiting the production of tantalum steam, preparing the high-purity tantalum material of carbon compounds. This method is easy toimplement, greatly shorten the preparation period of the traditionalmethod with no environment pollution. By the Vickers hardnessmeasurement of the synthetic TaC and Ta2C, we found that the hardnessof sample decrease as the load increasing, finally tends to a certain value.The vickers hardness of TaC and Ta2C is15.3GPa and13.6GPa. TheVanderbilt method is used to measure the resistivity of TaC and Ta2C in10-6orders of magnitude. Moreover, we find that the oxidationtemperature of TaC and Ta2C is about750oC and it represent a goodoxidation resistance.