Abstract
The results of studies on the production of a new class of alloying materials in the combustion mode are presented on the example of synthesis of composite alloys based on vanadium, chromium and silicon nitrides. Prove the principal possibility of creation of the SHS in the production of various composite alloys for steelmaking when using as a raw material of conventional ferroalloys. It is shown that the degree of nitriding of ferroalloys in the regime of filtration combustion strongly depends on the pressure of nitrogen, dispersity of the powder starting material and porosity of the nitride samples. The higher the nitrogen pressure, the greater the porosity of the samples and larger particles of the original powder of the alloy the greater the amount of nitrogen fixed in the combustion products. More dense samples and samples of the larger ferroalloy powder nitrided in a more narrow range of nitrogen pressure. To initiate a stable filtration combustion in such samples need higher pressure. It is shown that depending on the composition of the initial ferroalloy, its nitriding can occur either by solid-phase (ferrochromium) or by liquid-phase mechanisms (ferrosilicon, ferrovanadium). In the first case, the combustion temperature below the melting point of the raw alloy, and eutectic in the system Cr-Fe-N. In the second it is higher. When solid-phase nitriding the saturation of the alloy with nitrogen always occurs in stages. Liquid-phase nitriding, depending on the amount of liquid phase in the combustion wave, the absorption of nitrogen can occur in one or in two stages. In the formation of a large number of processed combustion products (ferrovanadium) diazotoluene missing. At a lower fraction of liquid products of combustion (ferrosilicon) contribution to the response is significant.
Keywords
Self-propagating high-temperature synthesis, ferroalloys, ferrovanadium nitride, ferrochromium nitride, nitride ferrosilicon, filtration combustion, microalloying, nitriding.