COMPUTER MODELING OF CHEMICAL EQUILIBRIUMS IN С–W–H TERNARY SYSTEM
thermodynamics estimation conditions WC synthesis without W, W2C and C impurities was carried out. Preliminary calculations of equilibrium states showed, to eliminate W2C impurities in the WC it is necessary to carry out WC synthesis at temperatures below 1320 °С. At these temperatures, from the thermodynamic point of view the C–W–H system has only carbide WC that simplifies the analysis of the system because for WC synthesis without W and C impurities at temperature range 100–1320 °C it is necessary to prevent the occurrence in the WC only these elements. For this presumed quasibinary sections WC–CH4, WC–H and W–CH4 on the concentration triangle of C–W–H system were built, for which computation of equilibrium composition depending on the temperature were carried out. Calculations of chemical equilibrium of various compositions, which are on supposed quasibinary sections allowed to establish that there are two sections in the C–W–H system: quasibinary section of a special kind of WC–CH4 and partly quasibinary section of WC–H. At that WC–CH4 section is valid section at the temperatures 100–1320 °С, and WC–H section is valid at the temperatures 700–1320 °С. Analysis of the results indicates that from thermodynamic point of view to receive WC, containing no free tungsten or carbon, during heating and cooling of mixtures WC with CH4 or WC with H2 is impossible because during cooling of mixtures WC with H2 at temperatures below 700 °C in the reaction products due to decarburization of WC by hydrogen free tungsten will be present and during heating WC with CH4 free carbon will be present in the reaction products, which of cooling below 1000 °C will be impossible to remove duo to kinetic braking. Based on carried out computations equilibrium states in C–W–H system a number of possible variants of nonequilibrium processes were proposed, that capable of obtaining WC without W and C impurities. Bibl. 7, Fig. 10, Tab. 8.
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