PRODUCTION OF METALLIC MAGNETIC PARTICLE POWDER CONSISTING ESSENTIALLY OF IRON OF ISOTROPIC SHAPE

• Main Authors: MISAWA HIROMITSU, NAKAMURA TATSUYA, KUROKAWA HARUMI
• Format: Patent
• Language: English
• Published: 06.07.1988
• Subjects: BASIC ELECTRIC ELEMENTS; CASTING; CHEMISTRY; CINEMATOGRAPHY; COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F; ELECTRICITY; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; HOLOGRAPHY; INDUCTANCES; INORGANIC CHEMISTRY; MAGNETOGRAPHY; MAGNETS; MAKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; METALLURGY; PERFORMING OPERATIONS; PHOTOGRAPHY; PHYSICS; POWDER METALLURGY; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TRANSFORMERS; TRANSPORTING; WORKING METALLIC POWDER

PURPOSE:To obtain the titled metallic magnetic particles of high coercive force and of large saturating magnetization by hydrothermally treating the acidic suspension of beta-FeOOH particles under a specified condition, and reducing it by heating. CONSTITUTION:The acidic suspension containing beta-FeOOH particles of >=150m /g specific surface area with <0.1mol cocn. is hydrothermally treated in 100-130 deg.C temp. to produce hematite particles of uniform sized isotropic shape. These hematite particles are reduced by heating in a reductive gas to produce metallic magnetic particles main component of which is uniform sized and isotropic shaped iron. These metallic magnetic particles are submerged into the liquid of toluene which is evaporated to make stable oxydized films on the surface of the particles lest the particles should be suddenly oxydized when they are taken out in the air. Thus, the metallic magnetic particle powder of about >=2500e coercive force and of >=170emmu/g saturating magnetization is obtained.