US 12,110,577 B2
Dust core
Hiroshi Watanabe, Nagoya (JP); Satoshi Mori, Nagoya (JP); Manami Fujii, Nagoya (JP); Katsuya Takaoka, Nagoya (JP); Hiroki Takeuchi, Nagoya (JP); and Hisashi Kozuka, Nagoya (JP)
Assigned to NITERRA CO., LTD., Nagoya (JP)
Appl. No. 17/421,201
Filed by NGK SPARK PLUG CO., LTD., Nagoya (JP)
PCT Filed Mar. 11, 2020, PCT No. PCT/JP2020/010572
§ 371(c)(1), (2) Date Jul. 7, 2021,
PCT Pub. No. WO2020/195842, PCT Pub. Date Oct. 1, 2020.
Claims priority of application No. 2019-054183 (JP), filed on Mar. 22, 2019.
Prior Publication US 2022/0059263 A1, Feb. 24, 2022
Int. Cl. B22F 1/00 (2022.01); B22F 1/05 (2022.01); B22F 1/052 (2022.01); B22F 1/105 (2022.01); B22F 1/16 (2022.01); C22C 38/02 (2006.01); H01F 1/20 (2006.01)
CPC C22C 38/02 (2013.01) [B22F 1/00 (2013.01); B22F 1/05 (2022.01); B22F 1/052 (2022.01); B22F 1/105 (2022.01); B22F 1/16 (2022.01); H01F 1/20 (2013.01); B22F 2301/35 (2013.01); B22F 2302/253 (2013.01); B22F 2304/10 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A dust core comprising soft magnetic metal particles and a particle boundary phase, the soft magnetic metal particles having an average particle size of 5 μm or more and 30 μm or less,
wherein the particle boundary phase includes a polycrystalline compound containing Al (aluminum),
when a sectional structure of the dust core is observed, an area percentage of α-Al2O3 in the particle boundary phase is 75% or less,
when the sectional structure of the dust core is observed in a first field of view of a 150 μm×150 μm square, and when, in a region where the particle boundary phase is located in an H-letter shape, two intersecting points where two vertical lines and one horizontal line that constitute the H letter intersect are connected with a straight line, and a perpendicular bisector of the straight line is drawn, a crossing width at a position where the perpendicular bisector crosses the particle boundary phase is defined as a thickness Tn of the particle boundary phase, and
when the thickness of the particle boundary phase is measured at five positions to respectively determine Tn (where n is an integer of 1 to 5), and an average thickness Ta which is an average of Tn (where n is an integer of 1 to 5) is calculated,
the average thickness Ta is 10 nm or more and 300 nm or less.