Method for preparing TaC. The preparation method is to use tantalum wire as tantalum source and heating source in HFCVD, and directly prepare TaC on graphite substrate one step, which has important value for expanding the application of TaC in industrial field.？
TaC is a transition metal carbide, with excellent physical and chemical properties, such as high hardness (Mohs hardness 9 ~ 10), high melting point (~ 3880℃), good electrical conductivity (25℃, 42.1μΩ·cm) and shock resistance, good chemical resistance and high oxidation resistance, etc. It can be widely used in powder metallurgy, cutting tools, corrosion resistance, high temperature structural materials, hard wear-resistant alloy additives and other fields. At present, the main methods of TaC preparation include sol-gel method, mechanical alloying method, self-propagating reaction method, liquid precursor method, chemical vapor deposition (CVD), etc. These preparation methods are complicated. For example, the sol-gel method has to go through the process of sol, impregnation, coating, drying, gelation and sintering, and the prepared coating is porous and loose. For the self-propagating reaction method and liquid phase precursor method, the preparation of their raw materials and precursors is complicated. Chemical vapor deposition (CVD) method generally uses TaCl5(sublimation into gas) as the tantalum source, C3H6 as the carbon source, H2 as the reducing agent, and Ar as the transport gas and dilution gas to prepare TaC. The existing device of this method can provide a maximum temperature of about 1400℃, and the limitation of reaction temperature leads to the accumulation of free carbon on the deposition surface. Tantalum carbide coating deviates from stoichiometric ratio, resulting in low coating density. In addition to using C3H6 as a carbon source, some researchers use graphite as a carbon source and TaCl5 as a tantalum source to prepare TaC. The above chemical vapor deposition methods are obtained by multi-step REDOX reactions with additional tantalum and carbon sources. The above methods generally have the problems of cumbersome preparation steps and low density of TaC prepared.
The beneficial effects are as follows: (1) The Ta atom evaporated from the tantalum wire in the hot wire chemical vapor deposition (HFCVD) system is deposited on the graphite substrate to directly prepare TaC. The method is simple and easy to operate, and is different from the solid phase method, liquid phase method and traditional vapor phase method, providing a new method for TaC preparation. (2) The invention makes full use of the advantages of HFCVD device in the case of no additional TaCl5, C3H6 and other raw materials, and directly prepares TaC at 800-1000℃ substrate temperature by heating tantalum wire and graphite substrate, which is lower than the preparation temperature reported in the literature and saves the preparation cost.
