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Composite soft magnetic powder, method for producing same, and powder magnetic core using same

A manufacturing method and powder magnetic core technology, applied in the direction of inductance/transformer/magnet manufacturing, inorganic material magnetism, transportation and packaging, etc., can solve the problems of BN layer thickness, iron volume ratio reduction, BN layer is easy to damage, etc., and achieve good Effects of lubricity, high density, and high magnetic permeability

Inactive Publication Date: 2013-10-02
HITACHI METALS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the above-mentioned documents, there are problems as follows: since the heat treatment temperature is high, 1000°C, the formed BN layer becomes too thick, and not only the volume ratio of iron decreases, but also the thick BN layer is easily broken during compression molding, Unable to obtain low loss powder cores

Method used

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  • Composite soft magnetic powder, method for producing same, and powder magnetic core using same
  • Composite soft magnetic powder, method for producing same, and powder magnetic core using same
  • Composite soft magnetic powder, method for producing same, and powder magnetic core using same

Examples

Experimental program
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Effect test

Embodiment 1

[0071] (1) Manufacture and measurement of composite soft magnetic powder

[0072] After mixing iron nitride powder (Fe / N atomic ratio = 4:1) with an average particle size of 4.4 μm and boron powder with an average particle size of 0.7 μm at a B / Fe atomic ratio of 0.6, the Heat treatment was carried out at 700°C for 2 hours, and non-magnetic components were removed by magnetic separation in IPA to obtain a composite soft magnetic powder with an average particle size of 4.3 μm. figure 1 It is a TEM photograph of the cross section of a composite soft magnetic powder. It was confirmed that there were surface portions not covered by the boron nitride layer on the iron-based core particles, but the surface of the core particles was not completely covered.

[0073]According to the analysis results of the surface composition obtained by XPS, although the coating layer is mainly composed of boron nitride, boron oxide is also contained, and the ratio of Fe (local oxide) on the outermos...

Embodiment 2

[0089] Iron nitride powder with an average particle size of 47 μm (Fe / N atomic ratio = 4:1) and boron powder with an average particle size of 0.7 μm were mixed at a B / Fe atomic ratio of 0.6, and heated at 800 ° C in a nitrogen atmosphere. Heat treatment was performed for 2 hours, and nonmagnetic components were removed by magnetic separation in IPA to obtain composite soft magnetic powder. The average particle size of the composite soft magnetic powder is 30 μm, the saturation magnetization is 196 emu / g, the volume ratio of iron is 71%, the ratio of Fe at the outermost surface is 6.0 atomic %, and the average crystal particle size of boron nitride is 12 nm. As a result of TEM photograph observation, it was found that the boron nitride coating layer was composed of polycrystals with different C-axis orientations. The average thickness T of the boron nitride coating layer calculated from the saturation magnetization A 1.6μm, T obtained from the volume ratio of iron A / D A was...

Embodiment 3

[0094] Iron nitride powder with an average particle size of 90 μm (Fe / N atomic ratio = 4:1) and boron powder with an average particle size of 0.7 μm were mixed at a B / Fe atomic ratio of 0.6, and heated at 800 ° C in a nitrogen atmosphere. Heat treatment was performed for 2 hours, and non-magnetic components were removed by magnetic separation in IPA to obtain composite soft magnetic powder. The average particle size of the composite soft magnetic powder is 85 μm, the saturation magnetization is 198 emu / g, the volume ratio of iron is 73%, the ratio of Fe at the outermost surface is 11.5 atomic %, and the average crystal particle size of boron nitride is 10 nm. As a result of TEM photograph observation, it was found that the boron nitride coating layer was composed of polycrystals with different C-axis orientations. The average thickness T of the boron nitride coating layer calculated from the saturation magnetization A 4.1μm, T obtained from the volume ratio of iron A / D A w...

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Abstract

This composite soft magnetic powder comprises soft magnetic ferrous core particles, which have a particle size of 2-100 [mu]m, and a layer, which has boron nitride as the primary constituent and covers at least a portion of the surface of the soft magnetic ferrous core particles, the covering layer being a polycrystalline layer that comprises boron nitride microcrystalline grains having an average crystal grain size of 3-15 nm and differing crystal axis orientations and that has an average thickness that is no greater than 6.6% of the average particle size of the soft magnetic ferrous core particles. The composite soft magnetic powder is produced by means of (1) mixing an iron nitride powder having an average particle size of 2-100 [mu]m and a boron powder having an average particle size of 0.1-10 [mu]m, (2) heat treating the obtained mixed powder at a temperature of 600-850 DEG C in a nitrogen atomosphere, and (3) eliminating the non-magnetic components.

Description

technical field [0001] The present invention relates to a composite soft magnetic powder having a coating layer mainly composed of boron nitride, a method for producing the composite soft magnetic powder, and a dust core using the composite soft magnetic powder. Background technique [0002] In recent years, the miniaturization and high frequency of electrical and electronic components such as reactors, inductors, choke coils, and motor cores using soft magnetic materials have continued to progress, and magnetic steel sheets or soft ferrite materials used in the past have been required. Such as soft magnetic materials with small losses in the high-frequency region, large saturation magnetization, and good DC superposition characteristics (when a DC bias current is passed, there is little decrease in inductance accompanying an increase in the current value). The powder of such a soft magnetic material is suitable for dust cores for electrical and electronic components. In ord...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/24B22F1/02H01F1/33H01F41/02B22F1/16
CPCC22C29/16H01F1/24H01F41/0246B22F1/16H01F1/01H01F41/005
Inventor 栗田富美所久人
Owner HITACHI METALS LTD
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