PRODUCTION OF ULTRAFINE POWDER

摘要

PURPOSE:To produce ultrafine magnetic powder having an excellent magnetic characteristic by forming nuclei in an unstable boundary region owing to a difference in the vapor flow contg. the metallic halide flowing in the same direction and the flow of reducing gas, and cooling quickly the same to suppress the growth of the nuclei. CONSTITUTION:A metallic halide is loaded into boilers 1, 1' and a prescribed amt. of diluting gas is introduced through introducing pipes 2, 2' to form metallic halide vapor having the prescribed concn. and flow rate. The gas is ejected in upward counter current from the nozzle 5 of an introducing pipe 4 opened in a reaction cylinder 3 into the cylinder 3 and the reducing gas is introduced therein as against said gas from the introducing pipe 6 in the lower part of the cylinder 3 so that both gases are brought into contact reaction to form a combustion flame at the reaction boundary. The flow rate of the reducing gas is made higher than the flow rate of the gas contg. halide to form an unstable boundary region and to generate many nuclei in said region. The cylinder is water cooled at the same instant by a jacket 8 to cool the combustion flame and to suppress the growth of the nuclei.