US 12,121,965 B2
Silicon-oxide-coated soft magnetic powder, and method for manufacturing same
Hidefumi Fujita, Tokyo (JP); Koji Tanoue, Tokyo (JP); Keisuke Yamada, Tokyo (JP); and Tetsuya Kawahito, Tokyo (JP)
Assigned to DOWA ELECTRONICS MATERIALS CO., LTD., Tokyo (JP)
Appl. No. 17/773,865
Filed by DOWA ELECTRONICS MATERIALS CO., LTD., Tokyo (JP)
PCT Filed Nov. 19, 2020, PCT No. PCT/JP2020/043268
§ 371(c)(1), (2) Date May 3, 2022,
PCT Pub. No. WO2021/106752, PCT Pub. Date Jun. 3, 2021.
Claims priority of application No. 2019-214326 (JP), filed on Nov. 27, 2019.
Prior Publication US 2022/0392676 A1, Dec. 8, 2022
Int. Cl. B22F 1/00 (2022.01); B22F 1/14 (2022.01); B22F 1/16 (2022.01); H01F 1/147 (2006.01)
CPC B22F 1/16 (2022.01) [H01F 1/14766 (2013.01); B22F 2301/35 (2013.01); B22F 2302/256 (2013.01)] 1 Claim
OG exemplary drawing
 
1. A silicon oxide-coated soft magnetic powder, in which the surface of a soft magnetic powder containing 20 mass % or more of iron is coated with silicon oxide, wherein when a volume-based cumulative 50% particle diameter obtained by a laser diffraction particle size distribution analysis in a state where the silicon oxide-coated soft magnetic powder is dispersed in a gas under the condition of 0.5 MPa is represented by D50 (HE) and a volume-based cumulative 50% particle diameter obtained by a laser diffraction/scattering particle size distribution analysis in a state where the silicon oxide-coated soft magnetic powder is dispersed in pure water is represented by D50 (MT), the D50 (HE) is 0.1 um or more and 10.0 um or less and D50 (HE)/D50 (MT) is 0.7 or more, and the coverage ratio R of a silicon oxide coating layer defined by the following formula (1) is 70% or more,
wherein the silicon dioxide is a silanol derivative and the soft magnetic powder does not contain rare-earth elements:
R=Si×100/(Si+M)  (1)
wherein Si is a molar fraction of Si obtained by X-ray photoelectron spectroscopy (XPS) measurement for the silicon oxide-coated soft magnetic powder, and M is the sum of molar fractions obtained by XPS measurement for metal elements and non-metal elements excluding oxygen among the elements constituting the soft magnetic powder,
wherein an average film thickness of the silicon oxide coating layer is 1 nm or more and 30 nm or less, a tap density of the silicon oxide-coated soft magnetic powder is 3.0 (g/cm3) or more and 5.0 (g/cm3) or less, and a ratio of the tap density to the D50 (MT) (tap density (g/cm3)/D50 (MT) (μm)) is 0.5 (g/cm3)/(μm) or more and 5.0 (g/cm3)/(μm) or less.