阅读说明：本技术 软磁复合材料及其制备方法和应用 (Soft magnetic composite material and preparation method and application thereof ) 是由 刘斌斌 郭峰 吕先松 汪贤 于 2021-06-02 设计创作，主要内容包括：本发明提供一种软磁复合材料及其制备方法和应用,软磁复合材料包括如下重量份数的原料混合制备而成：80～110份的铁粉材料、0.1～1.5份的第一钝化材料以及7～16份的第二钝化材料,其中,第一钝化材料选自磷酸、磷酸二氢铝、磷酸二氢钠和钼酸镍中的至少一种,第二钝化材料选自纳米氧化镁、纳米氧化铝和纳米二氧化硅中的至少一种。上述软磁复合材料通过使用两种钝化材料,第一钝化材料会在铁粉材料表面进行化学钝化并形成相对完整的钝化膜,第二钝化材料通过使用纳米级材料对钝化膜的缺陷处进行填充修复及对完整部分进行加强处理,使得最终在铁粉材料表面上得到的钝化膜完整无缺陷,在保证软磁复合材料的磁性能的前提下还提高了耐蚀性能。(The invention provides a soft magnetic composite material and a preparation method and application thereof, wherein the soft magnetic composite material is prepared by mixing the following raw materials in parts by weight: 80-110 parts of iron powder material, 0.1-1.5 parts of first passivation material and 7-16 parts of second passivation material, wherein the first passivation material is selected from at least one of phosphoric acid, aluminum dihydrogen phosphate, sodium dihydrogen phosphate and nickel molybdate, and the second passivation material is selected from at least one of nano magnesium oxide, nano aluminum oxide and nano silicon dioxide. According to the soft magnetic composite material, two passivation materials are used, the first passivation material can perform chemical passivation on the surface of the iron powder material and form a relatively complete passivation film, the second passivation material performs filling repair on the defect of the passivation film and reinforcing treatment on the complete part by using a nano-scale material, so that the passivation film finally obtained on the surface of the iron powder material is complete and free of defects, and the corrosion resistance is improved on the premise of ensuring the magnetic performance of the soft magnetic composite material.)

1. The soft magnetic composite material is characterized by being prepared by mixing the following raw materials in parts by weight:

80-110 parts of iron powder material,

0.1 to 1.5 parts of a first passivation material, and

7-16 parts of a second passivation material;

wherein the first passivation material is selected from at least one of phosphoric acid, aluminum dihydrogen phosphate, sodium dihydrogen phosphate, and nickel molybdate;

the second passivation material is selected from at least one of nano magnesium oxide, nano aluminum oxide and nano silicon dioxide.

2. A soft magnetic composite material according to claim 1, wherein the iron powder material is at least one selected from carbonyl iron powder, iron silicon chromium powder, iron silicon aluminum powder and iron silicon powder, and the particle size of the iron powder material is D50 ═ 5 μm to 15 μm.

3. The soft magnetic composite material of claim 1, which is prepared by mixing the following raw materials in parts by weight:

4. a soft magnetic composite material according to claim 3, wherein the solvent consists of 11 to 20 parts by weight of organic solvent and 3 to 5 parts by weight of inorganic solvent.

5. A soft magnetic composite material according to any of claims 1 to 4, wherein the particle size of the second passivation material is between 10nm and 50 nm.

6. A method for preparing a soft magnetic composite material according to any of claims 1 to 5, comprising the steps of:

respectively preparing a first passivation solution and a second passivation solution, wherein the first passivation material and part of the solvent are mixed for the first time to prepare the first passivation solution; mixing the second passivation material with the rest of the solvent for the second time to prepare a second passivation solution;

carrying out primary stirring and primary drying on the first passivation solution and the iron powder material to prepare primary passivation iron powder;

and carrying out secondary stirring and secondary drying on the second passivation solution and the primary passivation iron powder.

7. The process for preparing a soft magnetic composite material according to claim 6, wherein the first mixing time is 15 to 30 min; and/or

The first stirring time is 40 min-60 min, the first drying temperature is 100-140 ℃, and the first drying time is 30 min-60 min.

8. The process for preparing a soft magnetic composite material according to claim 6, wherein the second mixing time is 30 to 45 min; and/or

The second stirring time is 40min to 60min, the second drying temperature is 60 ℃ to 80 ℃, and the second drying time is 60min to 90 min.

9. A method for preparing a soft magnetic composite material according to any one of claims 6 to 8, further comprising the step of sieving the first passivated iron powder through a sieve of 160 to 200 meshes.

10. Use of the soft magnetic composite material according to any of claims 1 to 5 for the preparation of electronic products.

Technical Field

The invention relates to the technical field of metal material powder metallurgy manufacturing, in particular to a soft magnetic composite material and a preparation method and application thereof.

Background

The soft magnetic composite material is mainly formed by mixing and pressing metal magnetic powder and an insulating medium by using a powder metallurgy process, and an insulating layer is arranged between adjacent magnetic powder particles. The soft magnetic composite material has the characteristics of 3D isotropic magnetic property, high saturation magnetic flux density, wide working frequency range, lower loss and the like, and can be prepared into various complicated shapes such as C-shaped, E-shaped, I-shaped, U-shaped, annular and the like due to the fact that the powder metallurgy process is adopted for compression molding, and as electronic devices gradually develop towards miniaturization and high frequency, the application of the soft magnetic composite material is wider. In the soft magnetic material, the metal soft magnetic composite material (also called soft magnetic powder core) combines the advantages of soft magnetic alloy and ferrite material, thereby not only maintaining higher soft magnetic performance, but also having higher resistivity. The traditional soft magnetic alloy material has low self resistivity, so that the skin effect is caused, and the high eddy current loss limits the high-frequency application.

Electronic products gradually develop towards smaller and smaller volumes, higher and higher circuit densities and higher and faster transmission speeds, and as important component parts of the electronic products, novel electronic components are developing towards the direction of chip type, miniaturization, high frequency, wide frequency, high precision, integration and environmental protection. The soft magnetic powder is used as an important component of an integrally formed inductance component, and the improvement of the corrosion resistance of the soft magnetic powder is very important.

In the traditional method, in order to improve the corrosion resistance of the soft magnetic powder, the chromium content in the soft magnetic powder is generally improved, and the chromium has the main functions in the soft magnetic material as follows: in an oxidizing medium, a layer of firm and compact chromium oxide is formed on the surface of the soft magnetic powder, so that the soft magnetic powder is protected. And the chromium dissolved in the soft magnetic powder can obviously improve the electrode potential of the soft magnetic material and reduce electrochemical corrosion caused by different electrode potentials. However, the content of chromium is increased, some passivation materials are used for carrying out chemical passivation coating treatment on the soft magnetic powder, and if the passivation materials are added too little, the passivation film coating is incomplete; however, if the passivation material is added too much, the reaction with the soft magnetic material is serious, and the passivation film is too thick, thereby sacrificing the magnetic properties of the soft magnetic powder, such as magnetic permeability.

Disclosure of Invention

Therefore, the soft magnetic composite material, the preparation method and the application thereof are needed to be provided, and the corrosion resistance can be improved on the premise of ensuring the magnetic conductivity of the soft magnetic composite material.

The invention provides a soft magnetic composite material which is prepared by mixing the following raw materials in parts by weight:

80-110 parts of iron powder material,

0.1 to 1.5 parts of a first passivation material, and

7-16 parts of a second passivation material;

wherein the first passivation material is selected from at least one of phosphoric acid, aluminum dihydrogen phosphate, sodium dihydrogen phosphate, and nickel molybdate;

the second passivation material is selected from at least one of nano magnesium oxide, nano aluminum oxide and nano silicon dioxide.

In one embodiment, the iron powder material is at least one selected from carbonyl iron powder, iron silicon chromium powder, iron silicon aluminum powder and iron silicon powder, and the particle size of the iron powder material is D50-5 μm-15 μm.

In one embodiment, the material is prepared by mixing the following raw materials in parts by weight:

in one embodiment, the solvent comprises 11-20 parts by weight of organic solvent and 3-5 parts by weight of inorganic solvent.

In one embodiment, the organic solvent is selected from at least one of acetone and ethanol, and the inorganic solvent is selected from at least one of sodium chloride solution and water.

In one embodiment, the second passivation material has a particle size of 10nm to 50 nm.

Further, the invention also provides a preparation method of the soft magnetic composite material, which comprises the following steps:

respectively preparing a first passivation solution and a second passivation solution, wherein the first passivation material and part of the solvent are mixed for the first time to prepare the first passivation solution; mixing the second passivation material with the rest of the solvent for the second time to prepare a second passivation solution;

carrying out primary stirring and primary drying on the first passivation solution and the iron powder material to prepare primary passivation iron powder;

and carrying out secondary stirring and secondary drying on the second passivation solution and the primary passivation iron powder.

In one embodiment, the first mixing time is 15min to 30 min; and/or

The first stirring time is 40 min-60 min, the first drying temperature is 100-140 ℃, and the first drying time is 30 min-60 min.

In one embodiment, the second mixing time is 30min to 45 min; and/or

The second stirring time is 40min to 60min, the second drying temperature is 60 ℃ to 80 ℃, and the second drying time is 60min to 90 min.

In one embodiment, the method further comprises the step of sieving the first passivated iron powder through a sieve of 160-200 meshes.

The invention further provides the use of a soft magnetic composite material as described above for the preparation of an electronic product.

According to the soft magnetic composite material, two passivation materials are used, the first passivation material can carry out chemical passivation on the surface of the iron powder material and form a relatively complete passivation film, and the second passivation material carries out filling repair on the defect of the passivation film and reinforcing treatment on the complete part by using a nano-scale material, so that the finally obtained passivation film is complete and free of defects. Meanwhile, the mutual matching of the two passivation materials avoids incomplete passivation film coating caused by too little passivation material; and the reaction with the soft magnetic material is serious due to excessive addition of the passivation material, and the magnetic property of the soft magnetic powder is sacrificed due to the excessively thick passivation film.

Drawings

Fig. 1 is a graph showing the salt spray test results of an annular magnetic ring obtained by preparing a soft magnetic composite material according to example 1, wherein (a) is a front view of the magnetic ring, and (b) is a side view of the magnetic ring;

fig. 2 is a diagram showing the salt spray test results of the annular magnetic ring obtained by preparing the soft magnetic composite material of embodiment 2, wherein (a) is a front view of the magnetic ring, and (b) is a side view of the magnetic ring;

fig. 3 is a diagram showing the salt spray test results of the annular magnetic ring prepared from the soft magnetic composite material of example 3, wherein (a) is a front view of the magnetic ring, and (b) is a side view of the magnetic ring;

fig. 4 is a diagram showing the salt spray test results of the annular magnetic ring obtained by preparing the soft magnetic composite material of embodiment 4, wherein (a) is a front view of the magnetic ring, and (b) is a side view of the magnetic ring;

FIG. 5 is a graph showing the results of a salt spray test on an annular magnetic ring prepared from the soft magnetic composite material of comparative example 1, wherein (a) is a front view of the magnetic ring and (b) is a side view of the magnetic ring;

FIG. 6 is a graph showing the results of a salt spray test on an annular magnetic ring prepared from the soft magnetic composite material of comparative example 2, wherein (a) is a front view of the magnetic ring and (b) is a side view of the magnetic ring;

FIG. 7 is a graph showing the results of a salt spray test on an annular magnetic ring prepared from the soft magnetic composite material of comparative example 3, wherein (a) is a front view of the magnetic ring and (b) is a side view of the magnetic ring;

FIG. 8 is a graph showing the results of a salt spray test on an annular magnetic ring prepared from the soft magnetic composite material of comparative example 4, wherein (a) is a front view of the magnetic ring and (b) is a side view of the magnetic ring;

fig. 9 is a diagram showing the results of a salt spray test of a ring-shaped magnetic ring prepared from the soft magnetic composite material of comparative example 5, wherein (a) is a front view of the magnetic ring, and (b) is a side view of the magnetic ring.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise. In the description of the present invention, "a plurality" means at least one, e.g., one, two, etc., unless specifically limited otherwise.

The words "preferably," "more preferably," and the like in this disclosure mean embodiments of the invention that may, in some instances, provide certain benefits. However, other embodiments may be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

When a range of values is disclosed herein, the range is considered to be continuous and includes both the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range-describing features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The invention provides a soft magnetic composite material which is prepared by mixing the following raw materials in parts by weight:

80-110 parts of iron powder material;

0.1-1.5 parts of a first passivation material;

7-16 parts of a second passivation material.

Preferably, the soft magnetic composite material is prepared by mixing the following raw materials in parts by weight:

90-100 parts of iron powder material;

0.5-1 part of a first passivation material;

10-15 parts of a second passivation material.

In a specific example, the first passivation material is selected from at least one of phosphoric acid, aluminum dihydrogen phosphate, sodium dihydrogen phosphate, and nickel molybdate.

The first passivation material is chemically passivated on the iron powder material to form a passivation film.

In a specific example, the second passivation material is selected from at least one of nano-magnesia, nano-alumina and nano-silica.

The second passivation material fills and repairs the defects of the passivation film by using the nano-scale material and strengthens the complete part, so that the finally obtained passivation film is complete and free of defects, and the corrosion resistance is improved on the premise of ensuring the magnetic property of the soft magnetic composite material.

Further, the particle size of the second passivation material is 10nm to 50nm, and it is understood that the particle size of the second passivation material may be, but not limited to, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, or 50 nm.

Preferably, the second passivation material is nano silicon dioxide with the particle size of 20 nm-40 nm

In a specific example, the iron powder material is selected from at least one of carbonyl iron powder, iron silicon chromium powder, iron silicon aluminum powder and iron silicon powder.

Further, the particle size of the iron powder material is 5 to 15 μm in terms of D50.

Specifically, the particle size of the iron powder material D50 may be, but is not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm.

In a specific example, the raw material of the soft magnetic composite material further comprises 14-25 parts of a solvent.

Specifically, the solvent comprises 11-20 parts of organic solvent and 3-5 parts of inorganic solvent.

It is understood that the organic solvent may be, but is not limited to, at least one selected from the group consisting of acetone and ethanol, and preferably, the organic solvent includes 8 to 15 parts of acetone and 3 to 5 parts of absolute ethanol.

It is to be understood that the inorganic solvent may be, but is not limited to, at least one selected from a sodium chloride solution and water, and the inorganic solvent is preferably water.

According to the soft magnetic composite material, two passivation materials are used, the first passivation material can perform chemical passivation on the surface of an iron powder material to form a relatively complete passivation film, the second passivation material performs filling repair on the defect of the passivation film and reinforcing treatment on the complete part by using a nano-grade material, so that the finally obtained passivation film is complete and free of defects, and the corrosion resistance is improved on the premise of ensuring the magnetic property of the soft magnetic composite material.

Further, the invention also provides a preparation method of the soft magnetic composite material, which comprises the steps of respectively preparing a first passivation solution and a second passivation solution, wherein the first passivation solution is prepared by mixing the first passivation material and part of the solvent for the first time; mixing the second passivation material with the rest solvent for the second time to prepare a second passivation solution;

carrying out primary stirring and primary drying on the first passivation solution and an iron powder material to prepare primary passivation iron powder;

and stirring the second passivation solution and the first passivation iron powder for the second time and drying the second passivation solution and the first passivation iron powder for the second time.

Specifically, the method includes the following steps S101 to S105.

Step S101: preparing the materials according to the raw materials of the soft magnetic composite material.

Step S102: and mixing the first passivation material and part of the solvent for the first time to prepare a first passivation solution, wherein the solvent used in the step accounts for 40-60% of the whole solvent.

It is understood that the proportion of the solvent used in this step to the whole solvent may be, but not limited to, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58% or 60%.

In one specific example, the first mixing time is 15min to 30 min.

It is understood that the first mixing time may be, but is not limited to, 15min, 18min, 21min, 24min, 27min, 30min, or 35 min.

Step S103: carrying out primary stirring and primary drying on the first passivation solution and an iron powder material to obtain primary passivation iron powder;

in a specific example, the first stirring time is 40min to 60min, the first drying temperature is 100 ℃ to 140 ℃, and the first drying time is 30min to 60 min.

It is to be understood that the first drying may be, but is not limited to, baking.

The first passivation solution and the iron powder material can be fully mixed through stirring and baking, and the first passivation solution is favorably and fully coated on the iron powder material.

It is understood that the first stirring time may be, but is not limited to, 40min, 42min, 44min, 46min, 48min, 50min, 52min, 54min, 56min, 58min, or 60 min.

Further, the first drying temperature may be, but is not limited to, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, 135 ℃ or 140 ℃.

Step S104: and mixing the second passivation material with the residual solvent for the second time to prepare a second passivation solution.

In a specific example, the second mixing time in the above step is 30min to 45 min.

It is understood that the second mixing time may be, but is not limited to, 30min, 33min, 36min, 39min, 42min, or 45 min.

Step S105: and stirring the second passivation solution and the first passivation iron powder for the second time and drying the second passivation solution and the first passivation iron powder for the second time.

It is to be understood that the second drying may be, but is not limited to, baking.

Further, the second stirring time is 40min to 60min, the second drying temperature is 60 ℃ to 80 ℃, and the second drying time is 60min to 90 min.

Specifically, the second stirring time may be, but is not limited to, 40min, 44min, 48min, 52min, 56min, or 60 min.

The second drying temperature may be, but not limited to, 60 ℃, 62 ℃, 64 ℃, 66 ℃, 68 ℃, 70 ℃, 72 ℃, 74 ℃, 76 ℃, 78 ℃ or 80 ℃.

The second drying time may be, but is not limited to, 60min, 65min, 70min, 75min, 80min, 85min or 90 min.

It can be understood that, in order to obtain a soft magnetic composite material with better performance, after the step S103 and before the step S104, the first passivated iron powder is sieved by a sieve with 160-200 meshes.

The preparation method of the soft magnetic composite material can be summarized as follows: uniformly stirring a first passivation material and a solvent which accounts for 40-60% of the whole solvent to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a sieve of 160-200 meshes; uniformly stirring the second passivation material and the residual solvent to obtain a second passivation solution; and stirring and baking the second passivation solution and the sieved first passivation iron powder.

The soft magnetic composite material is passivated twice in sequence, the first passivation material can form a relatively complete passivation film on the surface of the iron powder material in the first chemical passivation process, and the nanoscale second passivation material is used for filling and repairing the defect of the passivation film and strengthening the complete part in the second physical passivation process, so that the finally obtained passivation film is complete and free of defects, and the corrosion resistance is improved on the premise of ensuring the magnetic performance of the soft magnetic composite material.

The invention also provides the application of the soft magnetic composite material in preparing electronic products.

In some of these embodiments, the electronic product may be, but is not limited to, an integrally formed inductor, relay, or transformer.

In the following examples, all the starting materials are commercially available unless otherwise specified.

Example 1

This example provides a soft magnetic composite material comprising, in parts by weight, 100 parts of Fe having a particle size of 10 μm as D50₉₂Si_3.5Cr_4.50.5 part of aluminum dihydrogen phosphate, 10 parts of 20-40nm nano silicon dioxide, 13 parts of acetone, 4 parts of absolute ethyl alcohol and 4 parts of water.

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring aluminum dihydrogen phosphate, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a 200-mesh sieve; uniformly stirring the nano silicon dioxide, 7.5 parts of acetone and 4 parts of water for 40min to obtain a second passivation solution; and stirring the second passivation solution and the sieved first passivation iron powder for 60min, and baking for 90min at 80 ℃.

And (3) uniformly mixing the prepared soft magnetic composite material with phenolic resin according to the mass ratio of 100:3.5, and granulating to prepare the flowable soft magnetic composite material.

Example 2

This example provides a soft magnetic composite material comprising, in parts by weight, 90 parts D50-10 μm Fe₉₂Si_3.5Cr_4.51 part of aluminum dihydrogen phosphate, 12 parts of 20-40nm nano silicon dioxide, 15 parts of acetone, 5 parts of absolute ethyl alcohol and 4 parts of water.

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring aluminum dihydrogen phosphate, 5.5 parts of acetone and 5 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a 200-mesh sieve; uniformly stirring the nano silicon dioxide, 9.5 parts of acetone and 4 parts of water for 40min to obtain a second passivation solution; and stirring the second passivation solution and the sieved first passivation iron powder for 60min, and baking for 90min at 80 ℃.

And (3) uniformly mixing the prepared soft magnetic composite material with phenolic resin according to the mass ratio of 100:3.5, and granulating to prepare the flowable soft magnetic composite material.

Example 3

This example provides a soft magnetic composite material comprising, in parts by weight, 100 parts of Fe having a particle size of 10 μm as D50₉₂Si_3.5Cr_4.50.5 part of phosphoric acid, 10 parts of 20-40nm nano silicon dioxide, 13 parts of acetone, 4 parts of absolute ethyl alcohol and 4 parts of water.

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring phosphoric acid, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a 200-mesh sieve; uniformly stirring the nano silicon dioxide, 7.5 parts of acetone and 4 parts of water for 40min to obtain a second passivation solution; and stirring the second passivation solution and the sieved first passivation iron powder for 60min, and baking for 90min at 80 ℃.

And (3) uniformly mixing the prepared soft magnetic composite material with phenolic resin according to the mass ratio of 100:3.5, and granulating to prepare the flowable soft magnetic composite material.

Example 4

This example provides a soft magnetic composite material comprising, in parts by weight, 100 parts of Fe having a particle size of 10 μm as D50₉₂Si_3.5Cr_4.50.5 part of aluminum dihydrogen phosphate, 15 parts of 10-20nm nano-magnesia, 13 parts of acetone, 4 parts of absolute ethyl alcohol and 4 parts of water.

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring aluminum dihydrogen phosphate, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a 200-mesh sieve; uniformly stirring the nano magnesium oxide, 7.5 parts of acetone and 4 parts of water for 40min to obtain a second passivation solution; and stirring the second passivation solution and the sieved first passivation iron powder for 60min, and baking for 90min at 80 ℃.

And (3) uniformly mixing the prepared soft magnetic composite material with phenolic resin according to the mass ratio of 100:3.5, and granulating to prepare the flowable soft magnetic composite material.

Comparative example 1

This comparative example differs from example 1 in that the iron powder material is not passivated.

This comparative example provides a soft magnetic composite material comprising, in parts by weight, 100 parts of D50 ═ 10 μm Fe₉₂Si_3.5Cr_4.5And uniformly mixing the soft magnetic composite material and phenolic resin according to the mass ratio of 100:3.5, and granulating to prepare the flowable soft magnetic composite material.

Comparative example 2

This comparative example differs from example 1 in that no second passivation material was added.

This comparative example provides a soft magnetic composite material comprising, in parts by weight, 100 parts of D50 ═ 10 μm Fe₉₂Si_3.5Cr_4.50.5 part of aluminum dihydrogen phosphate, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring aluminum dihydrogen phosphate, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; and stirring the first passivation solution and an iron powder material, and baking to obtain the passivated iron powder.

And (3) uniformly mixing the prepared soft magnetic composite material with phenolic resin according to the mass ratio of 100:3.5, and granulating to prepare the flowable soft magnetic composite material.

Comparative example 3

This comparative example provides a soft magnetic composite material comprising 500 parts by weight of Fe with D50 ═ 10 μm₉₂Si_3.5Cr_4.50.5 part of aluminum dihydrogen phosphate, 10 parts of 20-40nm nano silicon dioxide, 13 parts of acetone, 4 parts of absolute ethyl alcohol and 4 parts of water.

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring aluminum dihydrogen phosphate, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a 200-mesh sieve; uniformly stirring the nano silicon dioxide, 7.5 parts of acetone and 4 parts of water for 40min to obtain a second passivation solution; and stirring the second passivation solution and the sieved first passivation iron powder for 60min, and baking for 90min at 80 ℃.

And (3) uniformly mixing the prepared soft magnetic composite material with phenolic resin according to the mass ratio of 100:3.5, and granulating to prepare the flowable soft magnetic composite material.

Comparative example 4

This comparative example provides a soft magnetic composite material comprising, in parts by weight, 100 parts of Fe with D50 ═ 10 μm₉₂Si_3.5Cr_4.50.5 part of 10-20nm nano-magnesia, 10 parts of 20-40nm nano-silica, 14 parts of acetone, 4 parts of absolute ethyl alcohol and 4 parts of water.

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring nano magnesium oxide, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a 200-mesh sieve; uniformly stirring the nano silicon dioxide, 7.5 parts of acetone and 4 parts of water for 40min to obtain a second passivation solution; and stirring the second passivation solution and the sieved first passivation iron powder for 60min, and baking for 90min at 80 ℃.

Adding phenolic resin which accounts for 3.5 percent of the mass of the iron powder as a bonding agent, uniformly mixing and granulating to prepare the flowable soft magnetic composite material.

Comparative example 5

This comparative example provides a soft magnetic composite material comprising, in parts by weight, 100 parts of Fe with D50 ═ 10 μm₉₂Si_3.5Cr_4.50.5 parts of aluminum dihydrogen phosphate, 10 parts of sodium tetraborate, 14 parts of acetone, 4 parts of absolute ethyl alcohol and 4 parts of water.

The preparation method of the soft magnetic composite material comprises the following steps: uniformly stirring aluminum dihydrogen phosphate, 5.5 parts of acetone and 4 parts of absolute ethyl alcohol, and stirring for 20min to obtain a first passivation solution; stirring the first passivation solution and an iron powder material, and baking to obtain primary passivation iron powder; sieving the primary passivated iron powder through a 200-mesh sieve; uniformly stirring sodium tetraborate, 7.5 parts of acetone and 4 parts of water for 40min to obtain a second passivation solution; and stirring the second passivation solution and the sieved first passivation iron powder for 60min, and baking for 90min at 80 ℃.

Adding phenolic resin which accounts for 3.5 percent of the mass of the iron powder as a bonding agent, uniformly mixing and granulating to prepare the flowable soft magnetic composite material.

Performance testing

The soft magnetic composite materials of the above examples and comparative examples were weighed to 2g and prepared into a ring-shaped magnetic ring with an outer diameter of 1.4cm and an inner diameter of 0.8cm under a pressure of 300Mpa, and then baked to cure the resin, cooled to room temperature and tested by salt spray 24H.

Fig. 1 to 4 are graphs showing the results of salt spray tests on the annular magnetic rings prepared from the soft magnetic composite materials of examples 1, 2, 3 and 4, respectively, and fig. 1, 2 and 4 show that the annular magnetic rings prepared from the soft magnetic composite materials of examples 1, 2 and 4 have smooth, flat and corrosion-resistant surfaces, and the annular magnetic rings in fig. 3 have rust but the rust area is less than 5% of the total area of the magnetic rings.

As shown in FIGS. 5 to 9, which are graphs of the salt spray test results of the annular magnetic rings prepared by using the soft magnetic composite materials of comparative example 1, comparative example 2, comparative example 3, comparative example 4 and comparative example 4, obviously showing that the rust on the surface of the magnetic ring is obvious and is obviously corroded and has poor corrosion resistance, the rust area in the annular magnetic ring prepared by the soft magnetic composite material of the comparative example 1 shown in figure 5 is more than 90 percent of the total area, the rusted area in the annular magnetic ring prepared from the soft magnetic composite material of comparative example 2 shown in fig. 6 exceeds 60 percent of the total area, the rusted area in the annular magnetic ring prepared from the soft magnetic composite material of comparative example 3 shown in figure 7 exceeds 40 percent of the total area, the rusted area in the annular magnetic ring prepared from the soft magnetic composite material of comparative example 4 shown in figure 8 exceeds 70 percent of the total area, the rusted area in the annular magnetic ring prepared from the soft magnetic composite material of comparative example 5 shown in fig. 9 exceeds 50% of the total area.

Therefore, the soft magnetic composite material provided by the invention also improves the corrosion resistance on the premise of ensuring the magnetic performance.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, so as to understand the technical solutions of the present invention specifically and in detail, but not to be understood as the limitation of the protection scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. It should be understood that the technical solutions provided by the present invention and obtained by logical analysis, reasoning or limited experiments by those skilled in the art are all within the scope of the appended claims. Therefore, the protection scope of the patent of the present invention shall be subject to the content of the appended claims, and the description and the attached drawings can be used for explaining the content of the claims.