FUSIFORM GOETHITE PARTICLE POWDER AND ITS PRODUCTION, FUSIFORM HEMATITE PARTICLE POWDER AND ITS PRODUCTION AND FUSIFORM METALLIC MAGNETIC PARTICLE POWDER CONSISTING ESSENTIALLY OF IRON AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide a fusiform goethite particle powder, a fusiform hematite particle powder and a fusiform metallic magnetic particle powder. ;SOLUTION: In the formation of the fusiform goethite particle by aging a water suspension containing a ferrous salt-containing precipitate obtained by allowing a mixed alkali aq. solution of an alkali carbonate aq. solution with an alkali hydroxide aq. solution to react with a ferrous salt aq. solution, passing the oxygen-containing gas to form a fusiform goethite seed crystal particle, passing the oxygen-containing gas through the water suspension containing the seed crystal particle to grow a goethite layer on the surface of the seed crystal particle, the fusiform goethite particle powder having Co existing ratio of 50:50 to 95:5 and powder of Al existing only on the surface layer part is obtained by adding 10-45 atom% Co compound at the time of forming, performing an oxidation reaction in the range of 30-80% of total Fe²⁺, making the space velocity of an oxygen-containing gas at the time of growing 2 times that at the time of forming and adding 5-20 atom% Al compound.;COPYRIGHT: (C)1999,JPO