GENERAL TRENDS IN METAL PARTICLES HETEROGENEOUS COMBUSTION

Experimental results concerning combustion of freely falling particles of copper, tungsten, steel, tantalum and molybdenum are presented in this paper. The experiments were carried out by the setup based on a method of forming and igniting monodisperse metal particles in pulsed discharge, developed at Odessa State University. The existence of flashes and corresponding temperature jumps during combustion of particles of the above metals in air and the existence of analogous jumps in the temperature curves of the underburned particles cooling in the inert gas have been ascertained. It has been found that dissolved oxygen is inside the particles during their burning. It is also shown that the reaction rate of metal particles heterogeneous combustion under the considered conditions is not limited by diffusion of oxygen to the metal surface. Analysis of the general features observed in the temperature history of the various burning metals particles, demonstrated that the dissolution of oxygen in the particles and subsequent phase transformations in the metal-oxygen solution play a substantial role in the above processes and this is the cause of the temperature jumps and flashes in metal particles combustion.