CN112712992A - FeSi/Ni composite magnetic powder core and preparation method thereof - Google Patents

FeSi/Ni composite magnetic powder core and preparation method thereof Download PDF

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Publication number
CN112712992A
CN112712992A CN202011529345.8A CN202011529345A CN112712992A CN 112712992 A CN112712992 A CN 112712992A CN 202011529345 A CN202011529345 A CN 202011529345A CN 112712992 A CN112712992 A CN 112712992A
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fesi
powder
magnetic powder
composite magnetic
composite
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樊希安
罗自贵
杨振甲
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Wuhan University of Science and Engineering WUSE
Wuhan University of Science and Technology WHUST
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Wuhan University of Science and Engineering WUSE
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/33—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials mixtures of metallic and non-metallic particles; metallic particles having oxide skin

Abstract

The invention belongs to the technical field of soft magnetic powder cores. The preparation method comprises the following steps of 1, mixing nano nickel oxide powder and iron-silicon alloy powder according to the mass ratio of 1: 9-99, and grinding to obtain composite powder; 2. performing pressure sintering on the obtained composite powder to obtain a sintered blank; 3. carrying out heat treatment on the obtained sintered blank to obtain the product with SiO2The FeSi/Ni composite magnetic powder core of the insulating layer. The FeSi/Ni composite magnetic powder core provided by the invention has the characteristics of good chemical stability, high temperature resistance, good insulating property, high resistivity, extremely low magnetic loss and high saturation magnetic flux density; in addition, the process is simple, the production cost is low, and the method has a good application prospect.

Description

FeSi/Ni composite magnetic powder core and preparation method thereof
Technical Field
The invention belongs to the technical field of soft magnetic powder cores. In particular to a FeSi/Ni composite magnetic powder core and a preparation method thereof.
Background
The soft magnetic powder core is used as an indispensable magnetic element of a power circuit due to high magnetic conductivity, low loss, low magnetostriction, excellent thermal stability and direct current bias capability, is widely applied to electronic components such as inverters, inductors, transformers, chokes and the like, and relates to the fields of motors, telecommunication, power supplies and the like.
It is worth mentioning that the eddy current loss of the soft magnetic powder core increases exponentially with the increase of the frequency of use, and the insulation coating of the soft magnetic composite powder is undoubtedly the most effective method for reducing the eddy current loss. On the basis, the insulation coating is mainly divided into an organic coating and an inorganic coating. The traditional organic coating materials such as phenolic resin, epoxy resin and the like have poor heat resistance, and cannot be subjected to high-temperature heat treatment at the temperature of more than 200 ℃ and eliminate high-temperature residual stress, so that the magnetic performance is influenced. And the soft magnetic powder core coated by the organic material generates heat due to eddy current loss in long-term operation, so that the organic insulating layer is aged and even thermally decomposed, the insulativity of the soft magnetic powder core is weakened, the eddy current loss is increased, and the stability of the soft magnetic powder core is influenced. Therefore, the inorganic coating material is receiving attention for its excellent chemical and thermal stability and electrical insulation.
Inorganic coating materials commonly used for soft magnetic powder cores are mainly phosphates and ceramic oxides (Al)2O3MgO and SiO2Etc.), the addition of the insulating coating material, which is a non-magnetic phase, causes a significant decrease in the saturation magnetic flux density of the soft magnetic powder core, thereby limiting the efficiency and size reduction of the inductor element. Therefore, it is very important to prepare a novel soft magnetic powder core with high magnetic flux density and low loss.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of a soft magnetic powder core, which has simple process and low production cost; the soft magnetic powder core prepared by the preparation method not only has high saturation magnetic flux density, but also has extremely low magnetic loss. The invention adopts the technical scheme that the preparation method of the FeSi/Ni composite magnetic powder core is characterized by comprising the following steps:
firstly, mixing nano nickel oxide powder and iron-silicon alloy powder according to a mass ratio of 1: 9-99, and grinding to obtain composite powder;
secondly, performing pressure sintering on the obtained composite powder to obtain a sintered green body;
thirdly, the obtained sintered body is subjected to heat treatment to obtain the product with SiO2The FeSi/Ni composite magnetic powder core of the insulating layer.
In the first step, the average particle diameter of the nano nickel oxide powder is 1 to 100 nm.
In addition, in the first step, the mass percentage of silicon contained in the ferrosilicon alloy powder is 1.5-13.5%, and the particle size of the ferrosilicon alloy powder is 10-200 μm.
And in the grinding, the mixed powder and the agate balls are mixed according to the mass ratio of 1: 10-20, the mixture is placed into the same ball milling tank to be ball milled for 15-30 hours under the condition of 100-300 r/min, and the agate balls are separated out after the grinding is finished.
And in the second step of pressure sintering, the composite powder is put into a die and placed in a pressure sintering furnace, the pressure is increased to 30-80 MPa under the protective atmosphere condition, the temperature is increased to 800-1000 ℃, and the heat preservation and pressure maintaining are carried out for 10-30 min.
The pressure sintering mode of the pressure sintering furnace is electrified pressure sintering, discharge plasma sintering or microwave hot-pressing sintering.
And in the third step, the heat treatment is to place the sintered blank in a heat treatment furnace, heat the sintered blank to 500-800 ℃ under the protective atmosphere, preserve the heat for 0.5-5 h, and cool the sintered blank along with the furnace.
A FeSi/Ni composite magnetic powder core is prepared by any one of the preparation methods of the FeSi/Ni composite magnetic powder core.
Compared with the prior art, the invention has the following advantages:
(1) the invention mixes the nanometer nickel oxide powder and the micron ferrosilicon alloy powder and ball-mills them to obtain the ferrosilicon-based composite powder with nickel oxide coating layer, then adopts the pressure sintering molding technique, makes the Si in the alloy and the nickel oxide coating layer have redox reaction by using high temperature condition, generates high resistance SiO2An insulating layer, soft magnetic phase Ni with high saturation magnetic flux density, and powder molding to obtain the final product with SiO2The FeSi alloy of the insulating layer and the Ni metal (namely FeSi/Ni composite magnetic powder core). The invention adopts ball milling and pressure sintering molding process which is simple and easy to operate, thereby having low preparation cost, simple process, good repeatability and good application prospect.
(2) The invention utilizes nano nickel oxideThe high flexibility of the nickel oxide nano-powder and the high toughness of the agate balls can realize the high uniform coating of the iron-silicon alloy powder by the nano-nickel oxide through long-time ball milling, and further form the high-insulation SiO2And (4) coating. And ceramic oxides such as SiO with good insulation2And Al2O3And the like, because of their brittleness and poor interfacial adhesion, the insulating coating of ferrosilicon powder cannot be achieved by the same process. Therefore, the iron-silicon magnetic powder core prepared by the invention has highly uniform SiO2The insulating layer has good chemical stability, can resist high temperature, has good insulating performance, and can effectively limit eddy current among alloy particles, so that the insulating layer has high resistivity and extremely low magnetic loss.
(3) The pressure sintering molding process in the preparation method not only realizes the low-resistance nickel oxide cladding layer to high-insulation SiO2The transformation of the cladding layer generates soft magnetic phase Ni, and realizes the synergistic enhancement of FeSi and Ni on magnetic performance. In addition, no excessive nonmagnetic phase is introduced due to the formation of a uniform coating layer, and thus the prepared FeSi/Ni composite magnetic powder core has a high saturation magnetic flux density.
Therefore, the method has simple process and low production cost, and the prepared FeSi/Ni composite magnetic powder core has extremely low magnetic loss and high saturation magnetic flux density.
Drawings
FIG. 1 is an SEM image of a FeSi/Ni composite magnetic powder core prepared by the invention;
FIG. 2 is an SEM image after partial position magnification;
fig. 3 is an EDS line scan of selected portions of fig. 2.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and examples, and the present invention is not limited to the examples.
Example 1
A preparation method of FeSi/Ni composite magnetic powder core comprises the following steps:
first step, composite powder preparation
Mixing nano nickel oxide powder with the average particle size of 1nm and iron-silicon alloy powder (wherein the Si content of the iron-silicon alloy powder is 1.6 wt%, the balance is iron, and the particle size of the iron-silicon alloy powder is 15 mu m) according to the mass ratio of 1: 99, placing the mixed powder and agate balls in the same ball-milling tank according to the mass ratio of 1: 10, carrying out ball milling for 15 hours under the condition of 100 revolutions per minute, and separating the agate balls to obtain composite powder;
second step, pressure sintering and forming
Loading the composite powder into a mold, placing the mold in a pressure sintering furnace, simultaneously pressurizing to 30MPa and heating to 800 ℃ under the protective atmosphere condition, and preserving heat and pressure for 10min to obtain a sintered blank;
third step, heat treatment
Placing the sintered blank body in a heat treatment furnace, heating to 500 ℃ under the protective atmosphere condition, carrying out heat treatment for 0.5h, and cooling along with the furnace to obtain the SiO-containing material2The SEM image of the FeSi/Ni composite magnetic powder core of the insulating layer is shown in FIG. 1. FIG. 2 is an SEM photograph of a partially enlarged portion, and it can be seen that the composite magnetic powder core is prepared with SiO2The composite magnetic powder core of FeSi alloy and Ni metal of the insulating layer. FIG. 3 is an EDS line scan of selected portions of FIG. 2, the EDS lines identified in FIG. 2.
Wherein the protective atmosphere in the second and third steps is nitrogen or argon.
The pressure sintering mode of the pressure sintering furnace is one of electrified pressure sintering, discharge plasma sintering and microwave hot-pressing sintering.
Example 2
A preparation method of FeSi/Ni composite magnetic powder core comprises the following steps:
first step, composite powder preparation
Mixing nano nickel oxide powder with the average particle size of 50nm with iron-silicon alloy powder (wherein the Si content of the iron-silicon alloy powder is 13.3 wt%, the balance is iron, and the particle size of the iron-silicon alloy powder is 150 mu m) according to the mass ratio of 1: 9, placing the mixed powder and agate balls in the same ball-milling tank according to the mass ratio of 1: 15, carrying out ball milling for 20 hours under the condition of 100 revolutions per minute, and separating the agate balls to obtain composite powder;
second step, pressure sintering and forming
Loading the composite powder into a mold, placing the mold in a pressure sintering furnace, simultaneously pressurizing to 80MPa and heating to 900 ℃ under the protective atmosphere condition, and preserving heat and pressure for 30min to obtain a sintered blank;
third step, heat treatment
Placing the sintered blank body in a heat treatment furnace, heating to 600 ℃ under the protective atmosphere condition, carrying out heat treatment for 3h, and cooling along with the furnace to obtain the SiO-containing material2The FeSi/Ni composite magnetic powder core of the insulating layer.
Wherein the protective atmosphere in the second and third steps is nitrogen or argon.
The pressure sintering mode of the pressure sintering furnace is one of electrified pressure sintering, discharge plasma sintering and microwave hot-pressing sintering.
Example 3
A preparation method of FeSi/Ni composite magnetic powder core comprises the following steps:
first step, composite powder preparation
Mixing nano nickel oxide powder with the average particle size of 70nm and iron-silicon alloy powder (wherein the Si content of the iron-silicon alloy powder is 7.2 wt%, the balance is iron, and the particle size of the iron-silicon alloy powder is 150 mu m) according to the mass ratio of 1: 50, placing the mixed powder and agate balls in the same ball-milling tank according to the mass ratio of 1: 10, carrying out ball milling for 30 hours under the condition of 300 revolutions per minute, and separating the agate balls to obtain composite powder;
second step, pressure sintering and forming
Loading the composite powder into a mold, placing the mold in a pressure sintering furnace, simultaneously pressurizing to 50MPa and heating to 800 ℃ under the protective atmosphere condition, and preserving heat and pressure for 20min to obtain a sintered blank;
third step, heat treatment
Placing the sintered blank body in a heat treatment furnace, heating to 700 ℃ under the protective atmosphere condition, carrying out heat treatment for 5h, and cooling along with the furnace to obtain the SiO-containing material2The FeSi/Ni composite magnetic powder core of the insulating layer.
Wherein the protective atmosphere in the second and third steps is nitrogen or argon.
The pressure sintering mode of the pressure sintering furnace is one of electrified pressure sintering, discharge plasma sintering and microwave hot-pressing sintering.
Example 4
A preparation method of FeSi/Ni composite magnetic powder core comprises the following steps:
first step, composite powder preparation
Mixing nano nickel oxide powder with the average particle size of 100nm and iron-silicon alloy powder (wherein the Si content of the iron-silicon alloy powder is 11 wt%, the balance is iron, and the particle size of the iron-silicon alloy powder is 200 mu m) according to the mass ratio of 1: 70, placing the mixed powder and agate balls in the same ball-milling tank according to the mass ratio of 1: 20, carrying out ball milling for 25 hours under the condition of 300 revolutions per minute, and separating the agate balls to obtain composite powder;
second step, pressure sintering and forming
Loading the composite powder into a mold, placing the mold in a pressure sintering furnace, simultaneously pressurizing to 70MPa and heating to 1000 ℃ under the protective atmosphere condition, and preserving heat and pressure for 30min to obtain a sintered blank;
third step, heat treatment
Placing the sintered blank body in a heat treatment furnace, heating to 800 ℃ under the protective atmosphere condition, carrying out heat treatment for 2h, and cooling along with the furnace to obtain the SiO-containing material2The FeSi/Ni composite magnetic powder core of the insulating layer.
Wherein the protective atmosphere in the second and third steps is nitrogen or argon.
The pressure sintering mode of the pressure sintering furnace is one of electrified pressure sintering, discharge plasma sintering and microwave hot-pressing sintering.
Compared with the prior art, the invention has the following advantages:
1. to obtain a catalyst with SiO2The FeSi/Ni composite magnetic powder core has the characteristics of good chemical stability, high temperature resistance, good insulating property, high resistivity, extremely low magnetic loss and high saturation magnetic flux density;2. the ball milling and pressure sintering molding process has the advantages of simple process, low production cost and good application prospect.

Claims (8)

1. A preparation method of FeSi/Ni composite magnetic powder core is characterized by comprising the following steps:
firstly, mixing nano nickel oxide powder and iron-silicon alloy powder according to a mass ratio of 1: 9-99, and grinding to obtain composite powder;
secondly, performing pressure sintering on the obtained composite powder to obtain a sintered green body;
thirdly, the obtained sintered body is subjected to heat treatment to obtain the product with SiO2The FeSi/Ni composite magnetic powder core of the insulating layer.
2. The method for preparing the FeSi/Ni composite magnetic powder core according to claim 1, wherein the method comprises the following steps: in the first step, the average particle size of the nano nickel oxide powder is 1-100 nm.
3. The method for preparing the FeSi/Ni composite magnetic powder core according to claim 1, wherein the method comprises the following steps: in the first step, the silicon content of the ferrosilicon alloy powder is 1.5-13.5% by mass, and the grain diameter of the ferrosilicon alloy powder is 10-200 μm.
4. The method for preparing the FeSi/Ni composite magnetic powder core according to claim 1, wherein the method comprises the following steps: the powder grinding is to mix the mixed powder and agate balls according to the mass ratio of 1: 10-20, put the mixture into the same ball milling tank, perform ball milling for 15-30 hours under the condition of 100-300 r/min, and separate the agate balls after the powder grinding is finished.
5. The method for preparing the FeSi/Ni composite magnetic powder core according to claim 1, wherein the method comprises the following steps: and in the second step of pressure sintering, the composite powder is put into a die and placed in a pressure sintering furnace, the pressure is increased to 30-80 MPa under the protective atmosphere condition, the temperature is increased to 800-1000 ℃, and the heat preservation and pressure maintaining are carried out for 10-30 min.
6. The method for preparing FeSi/Ni composite magnetic powder core according to claim 5, wherein: the pressure sintering mode of the pressure sintering furnace is electrified pressure sintering, discharge plasma sintering or microwave hot-pressing sintering.
7. The method for preparing the FeSi/Ni composite magnetic powder core according to claim 1, wherein the method comprises the following steps: and the third step of heat treatment is to place the sintered blank in a heat treatment furnace, raise the temperature to 500-800 ℃ under the protective atmosphere condition, preserve the temperature for 0.5-5 h, and then cool the sintered blank along with the furnace.
8. A FeSi/Ni composite magnetic powder core is characterized in that: the FeSi/Ni composite magnetic powder core is prepared by the preparation method of the FeSi/Ni composite magnetic powder core according to any one of claims 1-7.
CN202011529345.8A 2020-12-22 2020-12-22 FeSi/Ni composite magnetic powder core and preparation method thereof Pending CN112712992A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114360882A (en) * 2021-12-31 2022-04-15 华南理工大学 Magnetic powder core with nano oxide/double-scale soft magnetic core functional elements and preparation method and application thereof
CN117393261A (en) * 2023-11-13 2024-01-12 中南大学 FeSiNi soft magnetic composite material and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
FAN LUO等: ""Ultra-low inter-particle eddy current loss of Fe3Si/Al2O3 soft magnetic composites evolved from FeSiAl/Fe3O4 core-shell particles"", 《JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114360882A (en) * 2021-12-31 2022-04-15 华南理工大学 Magnetic powder core with nano oxide/double-scale soft magnetic core functional elements and preparation method and application thereof
CN117393261A (en) * 2023-11-13 2024-01-12 中南大学 FeSiNi soft magnetic composite material and preparation method thereof

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