BEHAVIOUR OF METAL OXIDES INJECTED INTO AN ARGON INDUCGION PLASMA

The behaviour of Al2O3, CuO, NiO and TiO2 injected along the axis of an argon thermal plasma, generated at 1 atm by induction heating at 4MHz, has been studied by determining the extent of decomposition as a function of the distance travelled within the plasma by particles of different sizes and for different power inputs to the gas. The amount of heat received by the particles can thus be calculated as a function of the distance. The results have been examined on the assumption that the rate-determining step of the decomposition process is the transfer of heat across the boundary layer surrounding the particles. The coefficients of heat transfer in the presence of mass counterflow have been evaluated from the transport properties of argon and from the thermodynamic data of the decomposition process. The equation of motion of the particles has been determined by assuming the validity of Stoke's law. It is concluded that the experimental results can be satisfactorily discussed on the assumption of reaction control by heat transfer. © 1969.