Abstract:The continuously dynamic-controlled combustion synthesis (CDCCS) was developed based on the continuous fluidization and combustion synthesis technologies. CoC₂O₄·2H₂O powders were transformed to Co₃O₄ in a gas-solid fluid bed unit designed and build independently, where the reactant of CoC₂O₄·2H₂O powders and the reactant of air were poured and introduced from the top and the bottom of the bed at a certain rates respectively. The reagents met in the bed and ignited at a given low temperature, resulting in formation of Co₃O₄. The results show a significant difference in combustion wave models. In the case of CDCCS, there was an immobile combustion wave, floating in the combustion zone located in the middle of the bed, instead of propagating of the combustion wave. The temperature of the combustion wave can be controlled by adjusting the flow rate of carrier gas. The resultant Co₃O₄ powders (diameter size ≤0.8 μm) have a narrow particle size distribution and spherical or quasi-spherical shape. This novel technique has many advantages, such as continuation, efficiency, energy conservation and environmental friendly and has been used in mass production.

Key words: combustion synthesis; fluidization; cobalt oxide; ultrafine powders