Synthesis of transitionmetal nitride/carbonitride nanopowders and their application for modification of structure of hardmetals

Abstract

Nanodispersed powders of nitrides/carbonitrides of IV-VI group transition metals (for example TiN, TiC_xN_1-x, ZrC_xN_1-x, NbC_xN_1-x, Cr₃C_1·6N_0·4) with an average particle size of 20-200 nm have been prepared by the method of plasmachemical synthesis. Owing to the dynamic conditions of synthesis (starting product evaporation or decomposition, mixing and condensation of the end product lasting for some tenths of second), the product is formed in a form of nanodispersed powder, mainly as a monocrystal with a great concentration of crystal lattice defects. This determines high chemical activity of these powders, including increased sintering rate and decreased sintering temperature (for example, in the case of TiN, TiC_xN_1-x or NbC_xN_1-x this temperature is 400-600°C lower in comparison with the traditional powders). Addition of transition metal nitride/carbonitride to hardmetal can effect formation of its structure and properties. It was shown during the investigation that addition of 10 wt-% of the TiN nanopowder has a positive effect on a decrease of WC grain size in a cermet and improvement of its mechanic characteristics.