Powder magnetic core
View Patent ↗A powder magnetic core having a high electrical resistivity and a high magnetic flux density, including at least a composite magnetic particle the composite magnetic particle including: a core particle containing iron as the main component; and an insulating passivation layer formed on the core particle, wherein: the insulating passivation layer at least has an inner layer formed on the core particle and the outermost layer formed on the inner layer; and the outermost layer contains iron oxide as the main component.
1. A powder magnetic core comprising at least a composite magnetic particle, the composite magnetic particle comprising:
a core particle containing iron as a main component; and
an insulating passivation layer formed on the core particle, wherein:
the insulating passivation layer has an inner layer formed on the core particle and an outermost layer formed on the inner layer;
the outermost layer contains iron oxide as a main component;
the inner layer and the outermost layer contain iron oxide and at least one kind of an oxide of nonferrous metal;
the inner layer contains more nonferrous metal than the outermost layer;
Fe is present in the outermost layer in an amount of 50 at. % or more;
the nonferrous metal includes at least one kind selected from the group consisting of aluminum, zirconium, silicon, titanium, chromium, manganese, sodium, lithium, zinc, barium and cesium; and
a content of the nonferrous metal in the inner layer is from 5 to 80 at. %.
2. The powder magnetic core according to claim 1 , wherein the core particle comprises a soft magnetic particle containing iron as a main component and an insulating film formed on a surface of the soft magnetic particle.
3. The powder magnetic core according to claim 1 , wherein a sum of thicknesses of the insulating passivation layer is 50 nm or more and 1.5 μm or less.
4. The powder magnetic core according to claim 2 , wherein the insulating film of the core particle contains iron phosphate.
5. The powder magnetic core according to claim 2 , wherein a sum of thicknesses of the insulating passivation layer is 50 nm or more and 1.5 μm or less.
6. The powder magnetic core according to claim 4 , wherein a sum of thicknesses of the insulating passivation layer is 50 nm or more and 1.5 μm or less.