Patent ID: 8852314
Filing Date: 2014-10-07
Classification: B22F,G11B,H01F

Abstract:
1. A method for producing a magnetic powder constituted primarily of Fe and containing Co, Al and a rare earth-element, including at least Y, which uses an iron oxy-hydroxide particle essentially consisting of Fe, Co, O, H and unavoidable impurities as a starting material, the method comprising: adding a carbonate and a Co amine complex to a slurry of the iron oxy-hydroxide particle and covering a surface of the iron oxyhydroxide particle with a carbonate of Co, adding Al salt to the slurry of the iron oxy-hydroxide particle and adhering Al to the surface of the iron oxy-hydroxide particle, adding a rare earth-element salt to the slurry of the iron oxy-hydroxide particle and adhering the rare earth-element, including at least Y, to the surface of the iron oxy-hydroxide particle, recovering an iron oxy-hydroxide particle on which surface Co, Al and the rare earth-element, including at least Y, are deposited, converting the recovered iron oxy-hydroxide particle to an iron oxide particle by thermal dehydration at a temperature range of 250 to 700 ° C., reducing the iron oxide particle in a gas-phase to obtain an iron based alloy particle containing Co, Al and the rare earth-element, including at least Y, and gradually oxidizing the iron based alloy particle obtained by the gas-phase reduction process, wherein the magnetic powder constituted primarily of Fe contains Co in an amount such that a Co/Fe ratio is 50% or less, Co is contained such that a surface portion of the powder has a higher concentration than a core portion of the powder, and the core portion of the powder is substantially Fe-Co alloy containing Co in an amount such that a Co/Fe ratio is from 6.4 to 23.2 at. %.