Insulation method of high-performance self-lubricating metal soft magnetic powder

Abstract

The invention discloses an insulation method of high-performance self-lubricating metal soft magnetic powder, which comprises the following steps: activating metal soft magnetic powder through a complexing agent, modifying MXene through a silicon source, and then putting the activated metal soft magnetic powder and the modified MXene material into an insulation liquid together for insulation treatment to obtain the high-performance self-lubricating metal soft magnetic powder. And finally, the insulating metal soft magnetic powder with excellent magnetic performance and self-lubricating performance is obtained. The insulating metal soft magnetic powder prepared according to the method disclosed by the invention has relatively high direct current bias performance and relatively low magnetic core loss, shows excellent comprehensive magnetic performance, also has good self-lubricating performance and excellent binding force, and can be used for remarkably improving the formability and the mechanical property of the insulating powder.

Description

Technical Field

[0001] The present invention relates to the field of material preparation, and particularly to an insulation method for high-performance and self-lubricating metal soft magnetic powder. Background Art

[0002] Metal soft magnetic powder cores are composite materials composed of tiny metal magnetic particles, and these particles are usually wrapped by an insulating layer to reduce eddy current losses. Due to their excellent magnetic properties and the ability to adapt to various application environments, metal soft magnetic powder cores play an important role in modern power electronics technology. They are widely used in power electronic devices, such as transformers, inductors, and magnetic core components in other high-frequency applications. With the increasing demand for high-efficiency electronic products, it is expected that the demand for high-performance metal soft magnetic powder cores will also continue to increase in the future.

[0003] Improving the insulation process of metal soft magnetic powder is an important way to directly enhance the comprehensive performance of metal soft magnetic powder cores. At present, the improvement of the insulation process of metal soft magnetic powder mainly focuses on the selection of insulating substances. Organic insulating substances are mainly various resins. This kind of insulation process is relatively simple, and the presence of resin has a positive effect on improving the strength of the powder core. However, the disadvantage is that the coating is uneven, and the thermal stability of the resin is poor, and high-temperature heat treatment cannot be carried out, which will impose certain limitations on the performance of the powder core; inorganic insulating substances are mainly various inorganic salts and metal oxides, which usually have the advantages of good thermal stability and high resistivity, but also have disadvantages such as easy agglomeration of insulating substances and poor coating strength.

[0004] Therefore, if a suitable material can be selected to combine the advantages of organic and inorganic insulating substances, while maintaining the high strength of the magnetic core and having excellent thermal stability and magnetic properties at the same time, the comprehensive performance of metal soft magnetic powder can be further improved and its application range can be expanded. Summary of the Invention

[0005] Based on the deficiencies existing in the above-mentioned prior art, the present invention provides an insulation method for high-performance and self-lubricating metal soft magnetic powder. By activating the metal soft magnetic powder and introducing the modified MXene material for insulation, a dense and self-lubricating insulating layer is formed on the surface of the metal soft magnetic powder, which not only improves the resistivity of the metal soft magnetic powder, reduces the loss, but also makes full use of the structural characteristics of the MXene material to improve the formability of the insulating powder. The prepared metal soft magnetic powder core has the advantages of high DC bias performance, low loss, and simple forming.

[0006] The technical solution adopted by the present invention is as follows:

[0007] An insulation method for high-performance and self-lubricating metal soft magnetic powder, comprising the following steps:

[0008] (1) Put the metallic soft magnetic powder into the first solvent containing a complexing agent and stir to activate the surface of the magnetic powder, and then dry it to obtain the activated metallic soft magnetic powder;

[0009] Among them: the complexing agent used is at least one of ethylenediaminetetraacetic acid, citric acid, tartaric acid, aminotrimethylene phosphonic acid, polyacrylic acid, and mercapto compounds. The mass of the complexing agent is 0.1-1% of the mass of the metallic soft magnetic powder, and the mass of the first solvent is 7-25% of the mass of the metallic soft magnetic powder.

[0010] (2) Put the MXene material into a reaction kettle, add a silicon source and a second solvent for modification treatment, and generate a certain amount of nanoscale silica particles in the structural voids of the MXene material to improve its resistivity while ensuring the excellent mechanical properties and magnetic properties of the MXene material; after the reaction, dry it to obtain the modified MXene material;

[0011] Among them: the mass of the silicon source is 0.01-0.5% of the mass of the MXene material, and the mass of the second solvent is 10-30% of the mass of the MXene material.

[0012] (3) Prepare an insulating liquid using a main insulating agent, an auxiliary insulating agent, and a third solvent;

[0013] Among them: the main insulating agent used is at least one of nitric acid, phosphoric acid, chromic acid, oxalic acid, acetic acid, and malic acid, and the auxiliary insulating agent used is at least one of alumina, silica, magnesia, calcium oxide, and glass powder. The addition amount of the main insulating agent is 8-35% of the mass of the third solvent, and the addition amount of the auxiliary insulating agent is 0.4-3% of the mass of the third solvent.

[0014] (4) Put the activated metallic soft magnetic powder obtained in step (1) into a reaction container, add the insulating liquid in step (3) according to 0.1-1.2% of the mass of the activated metallic soft magnetic powder, and at the same time add the modified MXene material in step (2) according to 0.05-0.6% of the mass of the activated metallic soft magnetic powder; after fully mixing all the raw materials in the reaction container, react at 15-45°C for 1-6 h; after the reaction, dry it to obtain the final insulating metallic soft magnetic powder.

[0015] Preferably, in step (1), the metallic soft magnetic powder is any one of iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, and iron-nickel powder.

[0016] Preferably, in step (1), the stirring is ultrasonic stirring, and the stirring time is 0.5-3 h.

[0017] Preferably, the first solvent is selected from at least one of ethanol, acetone, ethyl acetate, propylene glycol, and butanol; the second solvent and the third solvent are each independently selected from at least one of ethanol, acetone, deionized water, ethyl acetate, propylene glycol, and butanol.

[0018] Preferably, in step (2), the MXene material is Ti n+1 C n T x 、V n+1 C n T x 、Cr n+1 C n T x 、Mo n+1 C n T x 、Ti n+1 N n T x 、V n+1 N n T x 、Cr n+1 N n T x 、Mo n+1 N n T x at least one of them, and the particle size of the used MXene material is 10 - 120 nm.

[0019] Preferably, in step (2), the silicon source is at least one of methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate, potassium silicate, and sodium silicate.

[0020] Preferably, in step (2), the temperature of the modification treatment is 65 - 100 °C, the time is 0.5 - 8 h, and the pH value of the mixed solution is controlled between 7.0 - 8.5 by dropping ammonia water (the purpose is to control the reaction rate).

[0021] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0022] The present invention selects MXene materials with a special two-dimensional structure as auxiliary insulating substances, utilizes the excellent lubricity and strength of MXene materials to improve the physical properties and formability of metal soft magnetic powders, and at the same time grows silica particles in the pores of MXene materials through modification to improve the magnetic properties of metal soft magnetic powders, ultimately obtaining metal soft magnetic insulating powders that combine the advantages of organic insulation and inorganic insulation, and exhibit excellent magnetic properties and self-lubricating properties. The insulating metal soft magnetic powders prepared according to the method of the present invention have high DC bias performance and low core loss, exhibit excellent comprehensive magnetic properties, and at the same time have good self-lubricating properties and excellent bonding force, which can significantly improve the formability and mechanical properties of insulating powders. Specific Embodiments

[0023] The following combines examples to clearly and completely describe the technical solutions of the present invention. Obviously, the described examples are only a part of the examples of the present invention, rather than all the examples. Based on the examples of the present invention, all other examples obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0024] Example 1

[0025] This example provides an insulation method for high-performance and self-lubricating metal soft magnetic powders, including the following steps:

[0026] (1) Put iron-silicon powder into ethanol dissolved with a complexing agent, stir ultrasonically for 3 h to activate the surface of the magnetic powder, and then dry at 90 °C to obtain activated iron-silicon powder. Among them: the mass of the complexing agent (formed by mixing citric acid and tartaric acid in a mass ratio of 1:1) is 0.2% of the mass of the iron-silicon powder, and the mass of ethanol is 23.5% of the mass of the iron-silicon powder.

[0027] (2) Put Ti n+1 C n T x MXene materials into a reaction kettle, and add a silicon source (tetraethyl orthosilicate) and a solvent (formed by mixing acetone and propylene glycol in a mass ratio of 2:1) for modification treatment. The modification temperature is 100 °C and the modification time is 1.5 h. During the modification, the pH value of the mixed solution needs to be continuously controlled at 7.2 by dropping ammonia water. After the reaction is completed, dry at 80 °C to obtain modified MXene materials. Among them: the addition amount of the silicon source is 0.01% of the mass of the MXene material, and the addition amount of the solvent is 28% of the mass of the MXene material.

[0028] (3) Prepare an insulating liquid using acetic acid as the main insulating agent, calcium oxide as the auxiliary insulating agent, and ethyl acetate and ethanol (with a mass ratio of 1:3) as solvents. Among them: the addition amount of the main insulating agent is 11% of the mass of the solvents, and the addition amount of the auxiliary insulating agent is 0.45% of the mass of the solvents.

[0029] (4) Put the activated iron-silicon powder obtained in step (1) into a reaction vessel, add the insulating liquid from step (3) according to 0.2% of the mass of the activated iron-silicon powder, and add the modified MXene material obtained in step (2) according to 0.15% of the mass of the activated iron-silicon powder. After all the raw materials are fully mixed in the reaction vessel, react at 18°C for 2 h. After the reaction is completed, dry at 120°C to obtain the final insulating iron-silicon powder.

[0030] Add silicone resin powder accounting for 0.4% of the powder mass as a binder to the prepared insulating iron-silicon powder, and form it into a 1.06-inch standard magnetic ring under a pressure of 1860 Mpa. After testing, the density of the prepared magnetic ring is 6.95 g / cm 3 , the breaking strength of the green magnetic core is 223 N, the magnetic permeability is 42, the magnetic permeability percentage under the condition of 100 Oe DC bias is 88%, and the loss under the condition of 100 kHz 50 mT is 220 mW / cm 3 .

[0031] Example 2

[0032] This example provides a method for insulating a high-performance and self-lubricating metal soft magnetic powder, including the following steps:

[0033] (1) Put the iron-nickel powder into ethyl acetate dissolved with a complexing agent, stir ultrasonically for 2 h to activate the surface of the magnetic powder, and then dry at 85°C to obtain the activated iron-silicon powder. Among them: the mass of the complexing agent (ethylenediaminetetraacetic acid) is 0.9% of the mass of the iron-nickel powder, and the mass of ethyl acetate is 15% of the mass of the iron-nickel powder.

[0034] (2) Put V with a particle size of 75 nm n+1 N n T x MXene material into a reaction kettle, and add a silicon source (composed of potassium silicate and sodium silicate mixed at a mass ratio of 2.5:1) and the solvent ethanol for modification treatment. The modification temperature is 90°C and the modification time is 6 h. During the modification, it is necessary to continuously control the pH value of the mixed solution at 8.5 by dropping ammonia water. After the reaction is completed, dry at 90°C to obtain the modified MXene material. Among them: the addition amount of the silicon source is 0.2% of the mass of the MXene material, and the addition amount of the solvent is 20% of the mass of the MXene material.

[0035] (3) Prepare an insulating liquid using phosphoric acid and oxalic acid (mass ratio of 5:1) as the main insulating agent, glass powder as the auxiliary insulating agent, and deionized water as the solvent. Among them: the addition amount of the main insulating agent is 12% of the mass of the solvent, and the addition amount of the auxiliary insulating agent is 2% of the mass of the solvent.

[0036] (4) Put the activated iron-nickel powder obtained in step (1) into a reaction vessel, add the insulating liquid from step (3) according to 0.6% of the mass of the activated iron-nickel powder, and at the same time add the modified MXene material obtained in step (2) according to 0.35% of the mass of the activated iron-nickel powder. After all the raw materials are fully mixed in the reaction vessel, react at 25 °C for 4 h. After the reaction, dry at 95 °C to obtain the final insulated iron-nickel powder.

[0037] Add silicone resin powder accounting for 0.4% of the powder mass as a binder to the prepared insulated iron-silicon powder, and mold it into a 1.06-inch standard magnetic ring at a pressure of 1550 Mpa. After testing, the density of the prepared magnetic ring is 7.41 g / cm 3 , the tensile strength at break of the green magnetic core is 84 N, the magnetic permeability is 65, the percentage of magnetic permeability under the condition of 100 Oe DC bias is 86%, and the loss under the condition of 50 kHz 100 mT is 243 mW / cm 3 .

[0038] Example 3

[0039] This example provides a method for insulating a high-performance, self-lubricating metal soft magnetic powder, including the following steps:

[0040] (1) Put the iron-silicon-aluminum powder into an organic solution dissolved with a complexing agent, stir ultrasonically for 0.5 h to activate the surface of the magnetic powder, and then dry at 95 °C to obtain activated iron-silicon-aluminum powder. Among them: the mass of the complexing agent (polyacrylic acid) is 0.5% of the mass of the iron-silicon-aluminum powder, and the mass of the organic solution (mixed by propylene glycol and butanol in a mass ratio of 1:3) is 7.5% of the mass of the iron-silicon-aluminum powder.

[0041] (2) Put the Ti n+1 N n T x +Mo n+1 N n T x MXene material into a reaction kettle, and add a silicon source (tetramethoxysilane) and a solvent (deionized water) for modification. The modification temperature is 70 °C and the modification time is 8 h. During the modification, continuously control the pH value of the mixed solution at 8 by dropping ammonia water. After the reaction, dry at 95 °C to obtain the modified MXene material. Among them: the addition amount of the silicon source is 0.45% of the mass of the MXene material, and the addition amount of the solvent is 10% of the mass of the MXene material.

[0042] (3) Prepare an insulating liquid by using chromic acid as the main insulating agent, silicon oxide and aluminum oxide (with a mass ratio of 4:1) as the auxiliary insulating agents, and propylene glycol as the solvent. Among them: the addition amount of the main insulating agent is 18.5% of the mass of the solvent, and the addition amount of the auxiliary insulating agent is 0.55% of the mass of the solvent.

[0043] (4) Put the activated iron silicon aluminum powder obtained in step 1 into a reaction vessel, add the insulating liquid from step (3) according to 1.0% of the mass of the activated iron silicon aluminum powder, and at the same time add the modified MXene material from step (2) according to 0.6% of the mass of the activated iron silicon aluminum powder. After all the raw materials are fully mixed in the reaction vessel, react at 44 °C for 6 h. After the reaction is completed, dry at 115 °C to obtain the final insulating iron silicon aluminum powder.

[0044] Add silicone resin powder accounting for 0.4% of the mass of the powder as a binder to the prepared insulating iron silicon powder, and mold it into a 1.06-inch standard magnetic ring at a pressure of 1860 Mpa. After testing, the density of the prepared magnetic ring is 6.12 g / cm 3 , the breaking strength of the green magnetic core is 135 N, the magnetic permeability is 78, the magnetic permeability percentage under the condition of 100 Oe DC bias is 48.3%, and the loss under the condition of 50 kHz 100 mT is 240 mW / cm 3 .

[0045] Comparative Example 1

[0046] In this comparative example, the iron silicon powder was insulated in the same method as in Example 1, except that the addition amount of the modified MXene material in step (4) was 0. After testing, the density of the prepared magnetic ring is 6.78 g / cm 3 , the breaking strength of the green magnetic core is 112 N, the magnetic permeability is 46, the magnetic permeability percentage under the condition of 100 Oe DC bias is 83%, and the loss under the condition of 100 kHz 50 mT is 293 mW / cm 3 .

[0047] When the magnetic permeability of the magnetic core prepared in the comparative example is extremely close to that of the magnetic core prepared in Example 1, the density decreases by 0.17 g / cm 3 , the breaking strength of the green body decreases by 111 N, the magnetic permeability percentage under the condition of 100 Oe DC bias decreases by 5%, and at the same time the loss under the condition of 100 kHz 50 mT increases by 73 mW / cm 3 .

[0048] In summary, the method of the present invention has the following advantages:

[0049] Good formability: In the present invention, MXene materials are used to treat metal soft magnetic powders. The excellent lubricity of MXene materials can effectively promote the improvement of the formability of magnetic powders. The lubricity of the magnetic powders treated with MXene materials is improved, and they can be normally formed without the need to additionally add lubricants. There are no poor forming phenomena such as die drawing and delamination. At the same time, the addition of MXene materials is beneficial to the rearrangement of powders during the pressing process, thereby improving the density and green strength of the prepared magnetic cores.

[0050] Excellent product performance: The modified MXene materials can effectively increase the resistivity of magnetic powders, reduce eddy current losses. At the same time, their low residue characteristics also avoid the magnetic dilution effect on magnetic powders, increase the saturation magnetization intensity, and effectively improve the magnetic properties of magnetic cores.

[0051] Those skilled in the art should understand that the above are only several specific embodiments of the present invention, rather than all embodiments. It should be pointed out that many variations and improvements can be made for those of ordinary skill in the art. All variations or improvements that do not exceed the scope of the claims should be regarded as the protection scope of the present invention.

Claims

1. An insulation method for a high-performance, self-lubricating metal soft magnetic powder, characterized in that It includes the following steps: (1) Put the metal soft magnetic powder into the first solvent containing a complexing agent and stir it to activate the surface of the magnetic powder, and then dry it to obtain the activated metal soft magnetic powder; Among them: the complexing agent used is at least one of ethylenediaminetetraacetic acid, citric acid, tartaric acid, aminotrimethylene phosphonic acid, polyacrylic acid, and mercapto compounds. The mass of the complexing agent is 0.1-1% of the mass of the metal soft magnetic powder, and the mass of the first solvent is 7-25% of the mass of the metal soft magnetic powder; (2) Put the MXene material into a reaction kettle, add a silicon source and a second solvent for modification treatment, and generate nanoscale silica particles in the structural voids of the MXene material; after the reaction is completed, dry it to obtain the modified MXene material; Among them: the mass of the silicon source is 0.01-0.5% of the mass of the MXene material, and the mass of the second solvent is 10-30% of the mass of the MXene material; (3) Prepare an insulating liquid using a main insulating agent, an auxiliary insulating agent, and a third solvent; Among them: the main insulating agent used is at least one of nitric acid, phosphoric acid, chromic acid, oxalic acid, acetic acid, and malic acid. The auxiliary insulating agent used is at least one of alumina, silica, magnesia, calcium oxide, and glass powder. The addition amount of the main insulating agent is 8-35% of the mass of the third solvent, and the addition amount of the auxiliary insulating agent is 0.4-3% of the mass of the third solvent; (4) Put the activated metal soft magnetic powder obtained in step (1) into a reaction vessel, add the insulating liquid in step (3) according to 0.1-1.2% of the mass of the activated metal soft magnetic powder, and add the modified MXene material in step (2) according to 0.05-0.6% of the mass of the activated metal soft magnetic powder; after fully mixing all the raw materials in the reaction vessel, react at 15-45°C for 1-6 h; after the reaction is completed, dry it to obtain the final insulating metal soft magnetic powder.

2. The insulation method of the metal soft magnetic powder according to claim 1, characterized in that, In step (1), the metal soft magnetic powder is any one of iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, and iron-nickel powder.

3. The insulation method of the metal soft magnetic powder according to claim 1, characterized in that, In step (1), the stirring is ultrasonic stirring, and the stirring time is 0.5-3 h.

4. The insulation method of the metallic soft magnetic powder according to claim 1, characterized in that, The first solvent is selected from at least one of ethanol, acetone, ethyl acetate, propylene glycol, and butanol; the second solvent and the third solvent are each independently selected from at least one of ethanol, acetone, deionized water, ethyl acetate, propylene glycol, and butanol.

5. The insulation method of the metallic soft magnetic powder according to claim 1, wherein In step (2), the MXene material is Ti n+1 C n T x 、V n+1 C n T x 、Cr n+1 C n T x 、Mo n+1 C n T x 、Ti n+1 N n T x 、V n+1 N n T x 、Cr n+1 N n T x 、Mo n+1 N n T x or at least one of them, and the particle size of the used MXene material is 10 - 120 nm.

6. The insulation method of the metallic soft magnetic powder according to claim 1, characterized in that, In step (2), the silicon source is at least one of methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate, potassium silicate, and sodium silicate.

7. The insulation method of the metallic soft magnetic powder according to claim 1, characterized in that, In step (2), the temperature of the modification treatment is 65-100°C, the time is 0.5-8 h, and the pH value of the mixed solution is controlled between 7.0 and 8.5 by dropping ammonia water.

8. An insulating metal soft magnetic powder obtained by the insulating method according to any one of claims 1 to 7.