Formation of gas phase boron and carbon-containing molecular species at high temperatures

Abstract

The formation of gas phase boron and carbon containing molecular species at high temperatures (thermal plasma) is investigated theoretically, by computing the equilibrium composition of the gas mixture containing boron, carbon, hydrogen and argon. The calculations are performed for the temperature range between 500 and 6000 K, B/C=1 and 2 and for the total pressure in the system of 1 bar. Use is made of the fact that the thermal plasma is plasma in local thermodynamic equilibrium, which makes possible theoretical determination (by employing the Gibbs free energy data for the compounds present in the system) of its equilibrium composition. From the calculated compositions of the investigated gas systems, presented in this paper, it was concluded that the initial molecule for cluster formation, as a connection between individual molecules and the solid state, in the case of the synthesis of solid boron carbide by means of thermal plasma should be the B2C molecule.