阅读说明：本技术 一种具有MnO-SiO2复合绝缘层的铁硅磁粉芯及其制备方法 (Has MnO-SiO2Iron-silicon magnetic powder core of composite insulating layer and preparation method thereof ) 是由 樊希安 罗自贵 杨振甲 于 2020-12-22 设计创作，主要内容包括：本发明属于软磁粉芯技术领域。具体涉及一种具有MnO-SiO-2复合绝缘层的铁硅磁粉芯及其制备方法,其步骤为1.将纳米锰氧化物粉末与铁硅合金粉末按质量比1∶9～99进行混合,进行粉磨得到复合粉末；2.将所得复合粉末进行加压烧结得到烧结坯体；3.将所得烧结坯体进行热处理得到具有MnO-SiO-2复合绝缘层的铁硅磁粉芯。本发明所提供铁硅磁粉芯化学稳定性好、耐高温、绝缘性能好、电阻率高、磁损耗极低以及优良的软磁性能；此外该工艺简单且生产成本低,具有良好的应用前景。(The invention belongs to the technical field of soft magnetic powder cores. In particular to a material with MnO-SiO 2 The preparation method comprises the following steps of 1, mixing nano manganese 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. performing heat treatment on the obtained sintered blank to obtain the sintered blank with MnO-SiO 2 The iron-silicon magnetic powder core of the composite insulating layer. The iron-silicon magnetic powder core provided by the invention has the advantages of good chemical stability, high temperature resistance, good insulating property, high resistivity, extremely low magnetic loss and excellent soft magnetic property; in addition, the process is simple, the production cost is low, and the method has a good application prospect.)

1. Has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer is characterized by comprising the following steps:

firstly, mixing nano manganese oxide powder and iron-silicon alloy powder according to the 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, carrying out heat treatment on the obtained sintered blank to obtain the sintered blank with MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer.

2. The composition of claim 1, wherein said composition has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer is characterized by comprising the following steps of: the nano manganese oxide powder in the first step is composed of MnO₂、Mn₂O₃And Mn₃O₄One or more of them, and the average particle diameter is 1 to 100 nm.

3. The composition of claim 1, wherein said composition has MnO-SiO₂Iron of composite insulating layerThe preparation method of the silicon magnetic powder core is characterized by comprising 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 composition of claim 1, wherein said composition has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer is characterized by comprising the following steps of: 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 composition of claim 1, wherein said composition has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer is characterized by comprising the following steps of: 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 composition of claim 5, wherein said composition has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer is characterized by comprising the following steps of: the pressure sintering mode of the pressure sintering furnace is electrified pressure sintering, discharge plasma sintering or microwave hot-pressing sintering.

7. The composition of claim 1, wherein said composition has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer is characterized by comprising the following steps of: 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. Has MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer is characterized in that: said has MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer is the one with MnO-SiO according to any one of claims 1 to 7₂Iron of composite insulating layerThe silicon magnetic powder core is prepared by the preparation method.

Technical Field

The invention belongs to the technical field of soft magnetic powder cores. In particular to a material with MnO-SiO₂An iron-silicon magnetic powder core of a composite insulating layer 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.

The common inorganic coating material for soft magnetic powder core mainly comprises Al₂O₃MgO and SiO₂However, the ceramic materials are brittle phases, and effective insulation coating is difficult to achieve by using a ball milling process, which deteriorates the soft magnetic property and the insulation property of the soft magnetic composite powder, so that it is very important to prepare an insulating layer capable of achieving both excellent soft magnetic property and low loss of the soft magnetic powder core.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides the soft magnetic powder core which has the advantages of simple process, low production cost, high resistivity, extremely low magnetic loss, high saturation magnetization and excellent permanent magnetism. The invention adopts the technical scheme that the material has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer is characterized by comprising the following steps:

firstly, mixing nano manganese oxide powder and iron-silicon alloy powder according to the 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, carrying out heat treatment on the obtained sintered blank to obtain the sintered blank with MnO-SiO₂Composite insulating layerThe iron-silicon magnetic powder core.

And, the nano-manganese oxide powder in the first step is composed of MnO₂、Mn₂O₃And Mn₃O₄One or more of them, and the average particle diameter 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.

Has MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer is made of any one of the iron-silicon magnetic powder core with MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer is prepared by the preparation method.

Compared with the prior art, the invention has the following advantages:

(1) mixing nanoscale manganese oxide and micron-sized iron-silicon alloy powder, performing ball milling to obtain iron-silicon-based composite powder with a manganese oxide coating layer, and performing redox reaction on Si in the alloy and the manganese oxide coating layer under high-temperature conditions by adopting a pressure sintering molding process to generate high-resistance MnO-SiO₂Compounding insulating layer and powder forming to obtain the product₂The iron-silicon magnetic powder core of the composite insulating layer. The inventionThe ball milling and pressure sintering molding process which is simple and easy to operate is adopted, so that the preparation cost is low, the process is simple and easy, the repeatability is good, and the application prospect is good.

(2) The invention utilizes the good flexibility and adsorption property of the nano manganese oxide and the good toughness of the agate balls, thereby realizing the highly uniform coating of the nano manganese oxide on the iron-silicon alloy powder through long-time ball milling, and further forming highly insulated MnO-SiO₂And (4) compounding a coating layer. 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 MnO-SiO₂The composite insulating layer has good chemical stability, can resist high temperature, has good insulating property, and can effectively limit eddy current among alloy particles, so that the electrical resistivity is high and the magnetic loss is low.

(3) The pressure sintering molding process in the preparation method not only realizes the oriented high-insulation MnO-SiO of the low-resistance manganese oxide coating layer₂The transformation of the composite coating layer realizes the high-densification molding of the iron-silicon magnetic powder core. In addition, because of the formation of the uniform composite insulating layer, no redundant non-magnetic phase is introduced, so that the prepared iron-silicon magnetic powder core has excellent soft magnetic performance, high saturation magnetization and good constant magnetic permeability.

Therefore, the invention has simple process and low production cost, and the prepared MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer has extremely low magnetic loss and excellent soft magnetic performance.

Drawings

FIG. 1 shows a compound of MnO-SiO prepared by the present invention₂SEM image of the iron silicon magnetic powder core of the composite insulating layer.

FIG. 2 is an XRD pattern of the powder of example 1 of the present invention after a first ball milling step;

FIG. 3 is an XRD pattern of the powder of example 1 of the present invention after a second pressure sintering step.

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

Has MnO-SiO₂The preparation method of the iron-silicon magnetic powder core of the composite insulating layer comprises the following steps:

first step, composite powder preparation

Mixing nano manganese oxide powder with the average particle size of 5nm and iron-silicon alloy powder (wherein the Si content of the iron-silicon alloy powder is 9.5 wt%, the balance is iron, and the particle size of the iron-silicon alloy powder is 10 mu m) according to the mass ratio of 1: 19, 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 900 ℃ 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 product with MnO-SiO₂Iron-silicon magnetic powder core of composite insulating layer, obtained with MnO-SiO₂The SEM image of the ferrite core of the composite insulating layer is shown in fig. 1.

FIG. 2 is an XRD pattern after a first ball milling step; FIG. 3 is an XRD pattern after the second pressure sintering step.

Wherein the nano manganese oxide powder consists of MnO₂、Mn₂O₃And Mn₃O₄One or more of the above.

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

First step, composite powder preparation

Mixing nano manganese oxide powder with the average particle size of 50nm and iron-silicon alloy powder (wherein the Si content of the iron-silicon alloy powder is 15 wt%, the balance is iron, and the particle size of the iron-silicon alloy powder is 10 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 25 hours under the condition of 200 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 600 ℃ under the protective atmosphere condition, carrying out heat treatment for 2h, and cooling along with the furnace to obtain the product with MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer.

Wherein the nano manganese oxide powder consists of MnO₂、Mn₂O₃And Mn₃O₄One or more of the above.

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

First step, composite powder preparation

Mixing nano manganese 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: 10, 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 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 25min 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 3h, and cooling along with the furnace to obtain the product with MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer.

Wherein the nano manganese oxide powder consists of MnO₂、Mn₂O₃And Mn₃O₄One or more of the above.

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

First step, composite powder preparation

Mixing nano manganese 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 1.5 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: 50, 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 30h 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 80MPa 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 5h, and cooling along with the furnace to obtain the product with MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer.

Wherein the nano manganese oxide powder consists of MnO₂、Mn₂O₃And Mn₃O₄One or more of the above.

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. obtain a material with MnO-SiO₂The iron-silicon magnetic powder core of the composite insulating layer has the advantages of good chemical stability, high temperature resistance, good insulating property, high resistivity, extremely low magnetic loss and excellent soft magnetic property; 2. the manufacturing process is simple, the production cost is low, and the application prospect is good.