US 12,030,122 B2
Method of manufacturing soft magnetic dust core
Naomichi Nakamura, Tokyo (JP); Makoto Nakaseko, Tokyo (JP); Takuya Takashita, Tokyo (JP); Mineo Muraki, Tokyo (JP); Hoshiaki Terao, Niigata (JP); Raita Wada, Niigata (JP); Akiri Urata, Sendai (JP); Yu Kanamori, Sendai (JP); Makoto Yamaki, Sendai (JP); Koichi Okamoto, Sendai (JP); Toshinori Tsuda, Sendai (JP); Shoichi Sato, Sendai (JP); and Kimihiro Ozaki, Nagoya (JP)
Assigned to JFE STEEL CORPORATION, Tokyo (JP); TOKIN CORPORATION, Miyagi (JP); and National Institute of Advanced Industrial Science and Technology, Tokyo (JP)
Filed by JFE STEEL CORPORATION, Tokyo (JP); TOKIN CORPORATION, Sendai (JP); and National Institute of Advanced Industrial Science and Technology, Tokyo (JP)
Filed on Oct. 21, 2020, as Appl. No. 17/075,693.
Application 17/075,693 is a division of application No. 15/737,429, abandoned, previously published as PCT/JP2016/003512, filed on Jul. 28, 2016.
Claims priority of application No. 2015-152804 (JP), filed on Jul. 31, 2015.
Prior Publication US 2021/0031268 A1, Feb. 4, 2021
Int. Cl. B22F 3/14 (2006.01); B22F 1/00 (2022.01); B22F 1/02 (2006.01); B22F 1/08 (2022.01); B22F 1/102 (2022.01); B22F 1/16 (2022.01); B22F 3/00 (2021.01); B22F 3/02 (2006.01); B22F 3/03 (2006.01); C22C 33/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/16 (2006.01); C22C 45/02 (2006.01); H01F 1/153 (2006.01); H01F 3/08 (2006.01); H01F 41/02 (2006.01); H01F 27/255 (2006.01)
CPC B22F 3/14 (2013.01) [B22F 1/00 (2013.01); B22F 1/08 (2022.01); B22F 1/102 (2022.01); B22F 1/16 (2022.01); B22F 3/00 (2013.01); B22F 3/02 (2013.01); B22F 3/03 (2013.01); C22C 33/02 (2013.01); C22C 38/00 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/16 (2013.01); C22C 45/02 (2013.01); H01F 1/15308 (2013.01); H01F 1/15325 (2013.01); H01F 1/15333 (2013.01); H01F 1/15375 (2013.01); H01F 3/08 (2013.01); H01F 41/0246 (2013.01); B22F 2301/35 (2013.01); B22F 2304/10 (2013.01); C22C 2200/02 (2013.01); C22C 2200/04 (2013.01); C22C 2202/02 (2013.01); H01F 27/255 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method of manufacturing a soft magnetic dust core comprising:
preparing coated powder including amorphous powder made of an Fe-B-Si-P-C-Cu-based alloy, an Fe-B-P-C-Cu-based alloy, an Fe-B-Si-P-Cu-based alloy, or an Fe-B-P-Cu-based alloy, with a first initial crystallization temperature Tx1 and a second initial crystallization temperature Tx2; and a coating formed on a surface of particles of the amorphous powder;
applying a compacting pressure to the coated powder or a mixture of the coated powder and the amorphous powder at a temperature equal to or lower than Tx1−100 K;
heating to a maximum end-point temperature equal to or higher than Tx1−50 K and lower than Tx2 with the compacting pressure being applied; and
thereby producing a soft magnetic dust core having a green density of 78% or more, a crystallization degree of 40% or more, and α-Fe crystallites with a size of 50 nm or less.