Metal magnetic particle, inductor, method for manufacturing metal magnetic particle, and method for manufacturing metal magnetic core
A metal magnetic particle provided with an oxide layer on a surface of an alloy particle containing Fe and Si. The oxide layer has a first oxide layer, a second oxide layer, a third oxide layer, and a fourth oxide layer. Also, in line analysis of element content by using a scanning transmission electron microscope-energy dispersive X-ray spectroscopy, the first oxide layer is a layer where Fe content takes a local maximum value, the second oxide layer is a layer where Fe content takes a local maximum value, the third oxide layer is a layer where Si content takes a local maximum value, and the fourth oxide layer is a layer where Fe content takes a local maximum value.
1. A method for manufacturing a metal magnetic particle, the method comprising:
mixing a raw material particle having, on a surface of an alloy particle containing Fe and Si, a Si oxide film and an Fe oxide film from a side of the alloy particle with Si alkoxide and alcohol;
forming a coating film forming particle formed with a coating film containing silicon oxide by hydrolyzing and drying the Si alkoxide; and
forming an oxide layer on the surface of the alloy particle by performing heat treatment on the coating film forming particle in an oxidizing atmosphere, wherein
an average thickness of the coating film is from 10 nm to 14 nm,
a layer in which Fe content takes a local maximum value is formed over a layer in which Si content takes a local maximum value and the layer in which Fe content takes the local maximum value also includes Si, and
in the layer in which Si content takes the local maximum value, Si content is greater than Fe content at a point where Si content takes the local maximum value.
2. The method for manufacturing the metal magnetic particle according to claim 1 , wherein
a temperature of the heat treatment is from 600° C. to 740° C.
3. The method for manufacturing the metal magnetic particle according to claim 1 , wherein
the Si alkoxide is tetraethoxysilane.
4. The method for manufacturing the metal magnetic particle according to claim 2 , wherein
the Si alkoxide is tetraethoxysilane.
5. A method for manufacturing a metal magnetic core, the method comprising:
mixing raw material particles each of which has, on a surface of an alloy particle containing Fe and Si, a Si oxide film and an Fe oxide film from a side of the alloy particle with Si alkoxide and alcohol;
forming coating film forming particles each of which is formed with a coating film containing silicon oxide, by hydrolyzing and drying the Si alkoxide;
molding the coating film forming particles; and
forming an oxide layer on a surface of each of the alloy particles by performing heat treatment on a molded body of the coating film forming particles in an oxidizing atmosphere, wherein
an average thickness of the coating film is from 10 nm to 14 nm,
in the oxide layer, a layer in which Fe content takes a local maximum value is formed over a layer in which Si content takes a local maximum value and the layer in which Fe content takes the local maximum value also includes Si, and
in the layer in which Si content takes the local maximum value, Si content is greater than Fe content at a point where Si content takes the local maximum value.
6. The method for manufacturing the metal magnetic core according to claim 5 , wherein
the molding includes laminating and pressing a green sheet containing the coating film forming particles.
7. The method for manufacturing the metal magnetic core according to claim 5 , wherein
the molding includes printing with and drying paste containing the coating film forming particles.
8. The method for manufacturing the metal magnetic core according to claim 5 , wherein
a temperature of the heat treatment is equal to or higher than 600° C. and equal to or lower than 740° C.
9. The method for manufacturing the metal magnetic core according to claim 5 , wherein
the Si alkoxide is tetraethoxysilane.
10. The method for manufacturing the metal magnetic core according to claim 6 , wherein
a temperature of the heat treatment is equal to or higher than 600° C. and equal to or lower than 740° C.
11. The method for manufacturing the metal magnetic core according to claim 7 , wherein
a temperature of the heat treatment is equal to or higher than 600° C. and equal to or lower than 740° C.
12. The method for manufacturing the metal magnetic core according to claim 6 , wherein
the Si alkoxide is tetraethoxysilane.
13. The method for manufacturing the metal magnetic core according to claim 7 , wherein
the Si alkoxide is tetraethoxysilane.