Powder core and iron-base powder for powder core
View Patent ↗The present invention relates to an iron-base powder for a powder core, wherein when cross-sections of at least 50 iron-base powders are observed and a crystal grain size distribution containing at least a maximum crystal grain size is determined by measuring a crystal grain size of each iron-base powder, 70% or more of the measured crystal grains are a crystal grain having a crystal grain size of 50 μm or more. According to the iron-base powder of the invention, a coercivity of the powder core can be made small and a hysteresis loss can be reduced.
1. An iron-base powder for a powder core, wherein when cross-sections of at least 50 iron-base powders are observed and a crystal grain size distribution comprising at least a maximum crystal grain size is determined by measuring a crystal grain size of each iron-base powder, 70% or more of the crystal grain size is 50 μm or more, and the iron-base powder comprises an insulating film present on a surface of the iron-base powder, wherein the insulating film is a chemical film of a phosphoric acid comprising Co.
2. The iron-base powder according to claim 1 , wherein when the iron-base powder is sieved using a sieve having a sieve opening of 75 μm, the iron-base powder which does not pass through the sieve accounts for 80 mass % or more.
3. The iron-base powder according to claim 1 , further comprising a silicone resin film present on a surface of the chemical film.
4. A powder core obtained by a method comprising compacting the iron-base powder according to claim 1 , wherein the powder core has a green density of 7.5 g/cm 3 or more.
5. An iron-base powder for a powder core, wherein when cross-sections of at least 50 iron-base powders are observed and a crystal grain size distribution comprising at least a maximum crystal grain size is determined by measuring a crystal grain size of each iron-base powder, 70% or more of the crystal grain size is 50 μm or more, and the iron-base powder comprises an insulating film present on a surface of the iron-base powder, wherein the insulating film is a chemical film of a phosphoric acid comprising Co and at least one elements selected from the group consisting of Na, S, Si, and W.
6. The iron-base powder according to claim 5 , wherein when the iron-base powder is sieved using a sieve having a sieve opening of 75 μm, the iron-base powder which does not pass through the sieve accounts for 80 mass % or more.
7. The iron-base powder according to claim 5 , further comprising a silicone resin film present on a surface of the chemical film.
8. A powder core obtained by a method comprising compacting the iron-base powder according to claim 5 , wherein the powder core has a green density of 7.5 g/cm 3 or more.