The kinetics questions of the niobium pentachloride thermal decomposition

The paper is a study of the thermal decomposition of niobium pentachloride vapours in a heated substrate under vacuum in the 1460-21600 K temperature range. The temperature dependence of the rate of niobium precipitation was obtained for mass flows of NbC15 of 8.3, 35.0 and 141.6 mg/cm2h. The experimental data were analysed on the basis of an equation for the kinetics of a reversible heterogeneous reaction in the diffusion region. The conclusion was reached that decomposition takes place in the diffusion region. The experimental value for the exponential of the kinetics equation coincides with the value ΔH2980/5=63kcal/mol. It cannot be taken for the energy of the activation process. Analysis of the kinetics equation can serve as a basis for predicting the peak dependence of the metal precipitation rate on the size of the flow. (author)