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Several Synthetic Methods Of Niobium Carbide

wallpapers Industry 2020-11-13
Niobium carbide, CAS No. 12069-94-2, molecular formula CHNb, molecular weight 105.925, is a gray-brown metallic powder, it needs to be sealed at room temperature, cool and ventilated, and used to produce wear-resistant films and semiconductor films. It can also be used as a raw material for the production of molybdenum carbide. It can be used to manufacture chromium-free special alloys and engineering ceramics.
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1. Auxiliary metal bath method. Use cobalt as auxiliary metal, select Nb and Co to form a metal bath in the ratio of 1:2, use pure graphite crucible, heat to 1800℃ in Taman furnace in hydrogen flow, after cooling (heating should be within 1h, at the highest Keep the temperature for 2~3h, and cool to room temperature within 2h) Dissolve and remove the cobalt with concentrated hydrochloric acid, and obtain powdered NbC with a particle size of 100~200μm, with a purity of 11.3% bound carbon (mass fraction) and 0.3% free carbon ( Quality score). The NbC produced by this method is the same as TaC, and the content of impurities, especially oxygen and nitrogen, is low (oxygen 100×10-6, nitrogen 10×10-6 or less).

2. Gas phase reaction method. Pass the mixed gas of niobium pentachloride NbCl5 vapor and hydrogen to the tungsten wire heated to about 1000℃ by direct energization, and form a metal niobium layer on the surface of the tungsten wire, and then increase the current through the tungsten wire to increase the metal niobium The layer temperature reaches 1300°C. In addition, the gas leading to the surface of the tungsten wire is changed from the above-mentioned mixed gas to a mixed gas of methane and hydrogen and passed to the upper part of the niobium layer to carbonize niobium into niobium carbide.
3. It is made from metal niobium by carbonization. Niobium powder obtained by reducing niobium oxide Nb2O5 or Nb2O3 with hydrogen or mixing niobium hydride powder and carbon black in an equimolar ratio [Dry mixing for 10h with a ball mill, and then pressing for molding. When niobium powder is used, it is high pressure (294199.5kPa) About); Low pressure (about 98066.5kPa) when using niobium hydride]. Store this pressurized powder in a pure graphite crucible or pan, and heat it to 1300~1400℃ in a hydrogen stream (using pure hydrogen with a dew point of about -35℃) in a Taman furnace or an induction heating furnace to make it permeate Carbon forms niobium carbide. The heating time depends on the amount of raw materials and the capacitance of the heating furnace. Generally, it must be kept at the highest temperature for 1 hour.

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