**2. Experimental**

2 Tungsten Carbide – Processing and Applications

active carbon-containing gas phase.

includes a mixture of H2 and CH4.

by thermal plasma transferred arc method [14].

quantity of tungsten carbide powder.

(ultrafine grades) [13].

or

content the reaction occurs according to the scheme:

the characteristics of the metal powder and forming carbide.

The second stage includes carbonization of tungsten by carbon in the graphite furnace with hydrogen atmosphere. Depending on the type of the furnace, atmosphere, and carbon

2W + C → W2C

W + C → WC. The obtained tungsten carbide powder has particles of the indefinite melted form, minimum 3 – 5 μm in size and contains 5 % of W2C minimum. The reduction terms greatly influence

Thermochemical synthesis of nano-phased tungsten carbide powders was also studied. It consisted of two stages [10, 11]. At first, nano-phased powders of metal tungsten were synthesized by reduction of various tungsten salts and chemical decomposition of vapor of volatile tungsten compounds. Then nano-phased tungsten carbide with the particle size of ~30 nm was obtained by carbonization at low temperature in the medium of controlled

The method suitable for tungsten carbide synthesis at low temperatures (~800°C) during 2 hours was suggested [12]. It is based on the gas-solid reaction between a tungsten source (ammonium paratungstate or tungsten oxide) and carbon-containing gas phase which

The conventional calcination–reduction–carburization (CRC) process offers the potential to manufacture commercial tungsten carbide powders with median grain sizes below 0.5 μm

In [14] point to that transferred arc thermal plasma method is more economical and less energy intensive than the conventional arc method and results in a fused carbide powder with higher hardness. Coatings of high wear resistance can be produced using fused tungsten carbide powder with WC and W2C phases, which can be economically synthesized

However, it is not economically efficient to use very pure and fine tungsten powder obtained from tungsten compounds at the stage of its reduction for producing a large

The existing economical and technological restrictions make the problem of the development of large-scaled cheap production of ultrafine and nanosized tungsten carbide powders very actual. Nowadays, a promising ecologically safe method, discovered in 1967 by academician A.G Merzhanov and his co-workers I.P. Borovinskaya and V.M. Shkiro – Self-propagating High-temperature Method (SHS) – is used for obtaining refractory compounds of high quality. This method combines a simple technology with low power consumption and allows obtaining products with regulated chemical and phase
