CN115621029A - Borosilicate-coated metal soft magnetic powder core and preparation method thereof - Google Patents
Borosilicate-coated metal soft magnetic powder core and preparation method thereof Download PDFInfo
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- CN115621029A CN115621029A CN202211333448.6A CN202211333448A CN115621029A CN 115621029 A CN115621029 A CN 115621029A CN 202211333448 A CN202211333448 A CN 202211333448A CN 115621029 A CN115621029 A CN 115621029A
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- 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
- H01F1/14—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 metals or alloys
- H01F1/20—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 metals or alloys in the form of particles, e.g. powder
- H01F1/22—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 metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
- H01F1/24—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 metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated
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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
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Abstract
The invention provides a borosilicate-coated metal soft magnetic powder core and a preparation method thereof, wherein the preparation method comprises the following steps: (1) Mixing siloxane, boric acid powder, a first solvent, a catalyst and water, carrying out hydrolysis reaction, and carrying out polycondensation reaction on a hydrolysate to obtain a borosilicate-containing coating agent; (2) Mixing the borosilicate-containing coating agent, the soft magnetic powder and a second solvent to obtain coated soft magnetic powder; (3) And mixing the coated soft magnetic powder, the binder and the release agent, and sequentially performing compression molding and annealing treatment to obtain the borosilicate-coated metal soft magnetic powder core. The preparation method of the invention adopts the chemical organic synthesis borosilicate-containing coating to uniformly coat the surface of the soft magnetic powder, effectively improves the insulation coating of the surface of the soft magnetic powder, further greatly improves the resistance of the metal soft magnetic powder core, reduces the eddy current loss under high-frequency use, and has large-scale industrialized popularization and application prospect.
Description
Technical Field
The invention relates to the technical field of metal soft magnetic materials, in particular to a borosilicate-coated metal soft magnetic powder core and a preparation method thereof.
Background
The soft magnetic material is an important magnetic functional material, has good electromagnetic conversion functional characteristics, and the prepared electronic components are widely applied to the fields of communication, power equipment, information technology, automatic control and the like. The metal soft magnetic material has the advantages of high saturation magnetization, good frequency characteristic and the like, and can be used in the use scene of electronic components with high frequency, high energy efficiency, large current and miniaturization by being coated and mixed with the insulating binder and then being prepared by the processes of molding, annealing treatment, impregnation curing and the like.
The surface coating of the metal magnetic powder can improve the surface resistance of the powder core and reduce the eddy current loss under high-frequency use. The current technology mainly uses the silicon-containing compound coated on the surface of magnetic powder particles as a main means, and means include inorganic coating, organic coating, inorganic-organic coating and the like.
CN110246679A discloses a method for preparing a metal soft magnetic powder core based on an organic/inorganic composite insulation process, which adopts the technical scheme that: firstly, epoxy resin is adopted to carry out organic insulation coating on metal magnetic powder, then silane coupling agent is utilized to carry out modification coupling on nanometer silicon oxide powder generated by hydrolysis of the epoxy resin and tetraethoxysilane, composite insulation of the epoxy resin and the silicon oxide on the metal magnetic powder is realized, on the basis, cold press molding is carried out on the insulated powder, and high-temperature annealing is carried out on a green body, so that the metal soft magnetic powder core with excellent direct current bias performance and low high-frequency loss is obtained. However, the process does not improve the insulation among particles well, and the obtained metal soft magnetic powder core has high magnetic loss.
CN101599334A discloses a method for producing a ferrosilicon-aluminum material with high resistivity and high magnetic permeability, which comprises adding 1-10wt% of Ni powder to FeSiAl magnetic powder, and coating the surface of the magnetic powder with SiO 2 The layer can greatly reduce the conductivity of the magnetic conductive material on the basis of basically not changing the original magnetic property, thereby greatly reducing the loss. And SiO 2 The thickness of the coating layer can be adjusted according to the concentration of the added tetraethoxysilane. The method carries out surface treatment on the coating powder, improves the dispersibility of the product, improves the processing performance of the product and obviously improves the physical and chemical properties of the product. However, the method is difficult and the process is not easy to control.
CN103247403A discloses a method for preparing a metal soft magnetic powder core, which comprises six parts of raw material sieving, insulation coating, preparation of magnetic powder to be formed, press forming, heat treatment and surface spraying. The manufacturing process is simple, and the used equipment is simple; the nano oxide dispersion liquid is selected to carry out insulation coating on the magnetic powder, so that the use effect is good, the environment is not polluted, and the raw material cost is low; the preparation process does not use organic solvent and organic binder, does not carry out infiltration curing treatment, and has low cost and no pollution; the metal soft magnetic powder core manufactured by the method has good magnetic property stability, higher quality factor and lower magnetic core loss. But the coating effect of the preparation method is poor.
Therefore, the development of the borosilicate-coated metal soft magnetic powder core and the preparation method thereof have important significance, wherein the borosilicate-coated metal soft magnetic powder core has a good insulating coating effect, can improve the surface resistance of the magnetic powder core and reduce the eddy current loss under high-frequency use.
Disclosure of Invention
In order to solve the technical problems, the invention provides the borosilicate-coated metal soft magnetic powder core and the preparation method thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, comprising the steps of:
(1) Mixing siloxane, boric acid powder, a first solvent, a catalyst and water, carrying out hydrolysis reaction, and carrying out polycondensation reaction on a hydrolysate to obtain a borosilicate-containing coating agent;
(2) Mixing the borosilicate-containing coating agent, the soft magnetic powder and a second solvent to obtain coated soft magnetic powder;
(3) And mixing the coated soft magnetic powder, the binder and the release agent, and sequentially performing compression molding and annealing treatment to obtain the borosilicate-coated metal soft magnetic powder core.
According to the preparation method of the metal soft magnetic powder core coated with the borosilicate, the raw materials of siloxane, boric acid powder, a first solvent, a catalyst and water are sequentially subjected to hydrolysis reaction and polycondensation reaction to obtain the coating agent containing the borosilicate, a glass net structure can be formed on the surface of soft magnetic powder particles, the insulation coating on the surface of the soft magnetic powder is effectively improved, the resistance of the metal soft magnetic powder core is greatly improved, and the eddy current loss under high-frequency use is reduced. The preparation method provided by the invention has the advantages that the preparation process is easy to control, and the insulation coating effect is good.
Preferably, the step of mixing the siloxane, the boric acid powder, the first solvent, the catalyst and the water of step (1) comprises: the siloxane and boric acid powder are mixed to obtain a mixed solution, then the first solvent and the catalyst are added, the mixture is stirred and heated to 50-100 ℃, and then water is added, wherein the mixture is stirred and heated to 50-100 ℃, for example, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃, but the invention is not limited to the enumerated values, and other unrecited values in the numerical range are also applicable.
Preferably, the siloxane of step (1) comprises polydimethylsiloxane and/or dimethyldiethoxysilane.
Preferably, the purity of the boric acid powder is 99.9% or more, and may be, for example, 99.9%, 99.91%, 99.92%, 99.94%, 99.95%, or 99.98%, etc., but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
The boric acid powder preferably has a particle size of 5 to 50 μm, and may be, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm or 50 μm, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
Preferably, the mass ratio of the siloxane to the boric acid powder is 10 (0.5 to 3), and may be, for example, 10.
According to the invention, the mass ratio of the siloxane to the boric acid powder is preferably 10 (0.5-3), which is beneficial to forming a boron-containing silicon coating with a glass net structure on the surface of soft magnetic powder particles, thereby improving the surface resistance of the metal soft magnetic powder core and reducing the eddy current loss under high-frequency use. When the mass ratio of the siloxane to the boric acid powder is lower than 10.5, the silicon content of the powder coating is low, and the effect of reducing eddy current loss is poor; when the mass ratio of siloxane to boric acid powder is higher than 10.
Preferably, the first solvent in step (1) comprises any one of methanol, ethanol, isopropanol or n-butanol or a combination of at least two thereof, wherein typical but non-limiting combinations include a combination of methanol and ethanol, a combination of isopropanol and n-butanol, a combination of ethanol and isopropanol or a combination of n-butanol, methanol and isopropanol.
Preferably, the catalyst comprises any one of hydrochloric acid, sulfuric acid or nitric acid or a combination of at least two thereof, wherein typical but non-limiting combinations include a combination of hydrochloric acid and sulfuric acid, a combination of nitric acid and hydrochloric acid or a combination of sulfuric acid, nitric acid and hydrochloric acid.
Preferably, the catalyst mass concentration is 2 to 10mol/mL, for example, 2mol/mL, 3mol/mL, 5mol/mL, 7mol/mL, 8mol/mL or 10mol/mL, but not limited to the values listed, and other values in the range are also applicable.
Preferably, the volume ratio of the first solvent to the catalyst is 10 (0.1 to 0.5), and may be, for example, 10.
Preferably, the water comprises deionized water.
Preferably, the water is added in an amount of 1 to 5% by mass of the siloxane and boric acid powder, for example, 1%, 2%, 3%, 4%, or 5%, but not limited to the recited values, and other values not recited in the above range are also applicable.
Preferably, the hydrolysis reaction time is 0.5 to 5 hours, for example, 0.5 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, etc., but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the polycondensation reaction of step (1) is carried out in a distillation apparatus.
Preferably, the hydrolysate is distilled under reduced pressure in the distillation apparatus.
Preferably, the vacuum degree of the vacuum distillation is 0.02 to 0.15MPa, and for example, it may be 0.02MPa, 0.05MPa, 0.1MPa, 0.12MPa, 0.14MPa or 0.15MPa, but it is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned range are also applicable.
Preferably, the polycondensation reaction temperature is 80 to 150 ℃, for example, 80 ℃, 90 ℃,100 ℃, 130 ℃, 140 ℃ or 150 ℃, but not limited to the values listed, and other values not listed within the range of the values are also applicable.
Preferably, the time of the polycondensation reaction is 1 to 20 hours, for example, 1 hour, 3 hours, 5 hours, 10 hours, 15 hours, or 20 hours, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the ratio by mass of the borosilicate-containing coating agent, the soft magnetic powder, and the second solvent in step (2) is (0.01 to 0.5) 10, and may be, for example, 0.01.
Preferably, the soft magnetic powder includes any one of iron-nickel magnetic powder, iron-silicon-aluminum magnetic powder, iron-nickel-molybdenum magnetic powder, amorphous magnetic powder or nanocrystalline magnetic powder or a combination of at least two of them, wherein typical but non-limiting combinations include a combination of iron-nickel magnetic powder and iron-silicon magnetic powder, a combination of iron-silicon-aluminum magnetic powder and iron-nickel-molybdenum magnetic powder, a combination of iron-nickel magnetic powder and iron-silicon-aluminum magnetic powder or a combination of iron-nickel-molybdenum magnetic powder, iron-nickel magnetic powder and iron-silicon magnetic powder.
Preferably, the second solvent comprises acetone.
Preferably, the coated soft magnetic powder is further sequentially subjected to drying and sieving.
Preferably, the step (3) of mixing the coated soft magnetic powder, the binder and the release agent includes: and mixing the coated soft magnetic powder and the binder, drying, and adding a release agent.
Preferably, the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10 (0.01 to 0.1) and may be, for example, 10.
Preferably, the binder comprises any one or a combination of at least two of a silicone, epoxy or phenolic resin, with typical but non-limiting combinations including a combination of a silicone and an epoxy resin, a combination of a phenolic resin and a silicone resin or a combination of an epoxy resin, a phenolic resin and a silicone resin.
Preferably, the mold release agent comprises any one or a combination of at least two of zinc stearate, aluminum stearate, or graphite, with typical but non-limiting combinations including combinations of zinc stearate and aluminum stearate, combinations of graphite and zinc stearate, or combinations of aluminum stearate, graphite, and zinc stearate.
Preferably, the pressure for the press forming in step (3) is 1000 to 3000MPa, for example, 1000MPa, 1050MPa, 2000MPa, 2500MPa or 3000MPa, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
The invention preferably selects the pressure of the compression molding to be 1000-3000 MPa, and has the advantages of improving the compactness of the borosilicate-coated metal soft magnetic powder core and ensuring that the insulating layer is not damaged.
Preferably, the annealing treatment is performed in a nitrogen atmosphere.
Preferably, the annealing temperature is 500 to 800 ℃, for example, 500 ℃, 550 ℃, 600 ℃, 700 ℃, 770 ℃, or 800 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
The annealing treatment temperature is preferably 500-800 ℃, and the method has the advantages of stress removal and hysteresis loss reduction.
Preferably, the annealing time is 0.1 to 8 hours, for example, 0.1 hour, 0.5 hour, 1 hour, 2 hours, 5 hours, 8 hours, etc., but the annealing time is not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferred technical scheme of the invention, the preparation method comprises the following steps:
(1) Firstly, mixing siloxane and boric acid powder according to the mass ratio of 10 (0.5-3) to obtain a mixed solution, then adding a first solvent and a catalyst according to the volume ratio of 10 (0.1-0.5), stirring and heating to 50-100 ℃, then adding water, and carrying out hydrolysis reaction for 0.5-5 h; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 80-150 ℃ for 1-20 h to obtain a coating agent containing borosilicate;
the siloxane comprises polydimethylsiloxane and/or dimethyldiethoxysilane; the purity of the boric acid powder is more than 99.9%; the particle size of the boric acid powder is 5-50 mu m; the first solvent comprises any one or the combination of at least two of methanol, ethanol, isopropanol or n-butanol; the catalyst comprises any one or the combination of at least two of hydrochloric acid, sulfuric acid or nitric acid; the mass concentration of the catalyst is 2-10 mol/mL; the water comprises deionized water; the addition amount of the water is 1-5 wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.02-0.15 MPa;
(2) Mixing the coating agent containing borosilicate, the soft magnetic powder and the second solvent according to the mass ratio of (0.01-0.5) to (10) (0.5-1.5) to obtain coated soft magnetic powder;
the soft magnetic powder comprises any one or the combination of at least two of iron-nickel magnetic powder, iron-silicon-aluminum magnetic powder, iron-nickel-molybdenum magnetic powder, amorphous magnetic powder or nanocrystalline magnetic powder; the second solvent comprises acetone; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and a binder, drying, then adding a release agent, and sequentially carrying out compression molding at the pressure of 1000-3000 MPa and annealing treatment at the temperature of 500-800 ℃ for 0.1-8 h in a nitrogen atmosphere to obtain a borosilicate-coated metal soft magnetic powder core;
the mass ratio of the coated soft magnetic powder, the adhesive and the release agent is 10 (0.01-0.1) to 0.01-0.1; the binder comprises any one or a combination of at least two of silicone resin, epoxy resin or phenolic resin; the release agent comprises any one or a combination of at least two of zinc stearate, aluminum stearate or graphite.
In a second aspect, the invention further provides a borosilicate-coated metal soft magnetic powder core, wherein the metal soft magnetic powder core is prepared by the preparation method of the borosilicate-coated metal soft magnetic powder core in the first aspect.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) According to the preparation method of the borosilicate-coated metal soft magnetic powder core, the borosilicate-containing coating is chemically and organically synthesized by using the boric acid powder as the raw material, so that the insulating coating on the surface of the metal soft magnetic powder core is effectively improved, and the resistance of the magnetic powder core is improved;
(2) The borosilicate-coated metal soft magnetic powder core provided by the invention has excellent magnetic performance, high magnetic conductivity and low magnetic loss, and has a large-scale industrial popularization and application prospect.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Example 1
The embodiment provides a preparation method of a borosilicate-coated metal soft magnetic powder core, which comprises the following steps:
(1) Firstly, mixing polydimethylsiloxane and boric acid powder according to the mass ratio of 10 to 0.5 to obtain a mixed solution, then adding a first solvent ethanol and a catalyst hydrochloric acid according to the volume ratio of 10 to 0.3, stirring and heating to 50 ℃, then adding deionized water, and carrying out hydrolysis reaction for 0.5h; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 80 ℃ for 1h to obtain a borosilicate-containing coating agent;
the purity of the boric acid powder is 99.9%; the particle size of the boric acid powder is 30 micrometers; the mass concentration of the catalyst is 5mol/mL; the addition amount of the water is 2wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.02MPa;
(2) Mixing the coating agent containing borosilicate, the iron-nickel magnetic powder and a second solvent acetone according to a mass ratio of 0.5; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and a binding agent silicone resin, drying, then adding a release agent zinc stearate, and sequentially carrying out press forming under the pressure of 1500MPa and annealing treatment at the temperature of 600 ℃ for 5 hours in a nitrogen atmosphere to obtain a borosilicate coated metal soft magnetic powder core; the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10.05.
Example 2
The embodiment provides a preparation method of a borosilicate-coated metal soft magnetic powder core, which comprises the following steps:
(1) Firstly, mixing polydimethylsiloxane and boric acid powder according to the mass ratio of 10; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 100 ℃ for 1h to obtain a borosilicate-containing coating agent;
the purity of the boric acid powder is 99.93%; the particle size of the boric acid powder is 10 micrometers; the mass concentration of the catalyst is 2-10 mol/mL; the addition amount of the water is 1-5 wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.05MPa;
(2) Mixing the coating agent containing borosilicate, the iron-nickel magnetic powder and a second solvent acetone according to a mass ratio of 0.05; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and binder epoxy resin, drying, then adding a release agent aluminum stearate, and sequentially carrying out press forming under the pressure of 1500MPa and annealing treatment at the temperature of 650 ℃ in a nitrogen atmosphere for 2h to obtain a borosilicate coated metal soft magnetic powder core; the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10.01.
Example 3
The embodiment provides a preparation method of a borosilicate-coated metal soft magnetic powder core, which comprises the following steps:
(1) Firstly, mixing polydimethylsiloxane and boric acid powder according to the mass ratio of 10 to 0.5 to obtain a mixed solution, then adding a first solvent ethanol and a catalyst nitric acid according to the volume ratio of 10 to 0.5, stirring, heating to 50 ℃, adding deionized water, and performing hydrolysis reaction for 2 hours; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 80 ℃ for 1h to obtain a borosilicate-containing coating agent;
the purity of the boric acid powder is 99.95%; the particle size of the boric acid powder is 25 micrometers; the mass concentration of the catalyst is 4mol/mL; the addition amount of the water is 4wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.05MPa;
(2) Mixing the coating agent containing borosilicate, the iron-silicon magnetic powder and a second solvent acetone according to a mass ratio of 0.05; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and a binder phenolic resin, drying, then adding a release agent graphite, and sequentially carrying out press forming under the pressure of 1500MPa and annealing treatment at the temperature of 700 ℃ in a nitrogen atmosphere for 7 hours to obtain a borosilicate coated metal soft magnetic powder core; the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10.09.
Example 4
The embodiment provides a preparation method of a borosilicate-coated metal soft magnetic powder core, which comprises the following steps:
(1) Firstly, mixing polydimethylsiloxane and boric acid powder according to the mass ratio of 10; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 120 ℃ for 6h to obtain a borosilicate-containing coating agent;
the purity of the boric acid powder is more than 99.9%; the particle size of the boric acid powder is 50 μm; the mass concentration of the catalyst is 10mol/mL; the addition amount of the water is 2.4wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.1MPa;
(2) Mixing the coating agent containing borosilicate, the sendust magnetic powder and a second solvent acetone according to a mass ratio of 0.05 to 10 to obtain coated soft magnetic powder; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and binder epoxy resin, drying, then adding a release agent zinc stearate, and sequentially carrying out press forming under the pressure of 1500MPa and annealing treatment at the temperature of 700 ℃ in a nitrogen atmosphere for 5.5 hours to obtain a borosilicate coated metal soft magnetic powder core; the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10.08.
Example 5
The embodiment provides a preparation method of a borosilicate-coated metal soft magnetic powder core, which comprises the following steps:
(1) Firstly, mixing dimethyldiethoxysilane and boric acid powder according to the mass ratio of 10; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 150 ℃ for 20h to obtain a borosilicate-containing coating agent;
the purity of the boric acid powder is 99.92%; the particle size of the boric acid powder is 5 micrometers; the mass concentration of the catalyst is 2mol/mL; the adding amount of the water is 1wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.02MPa;
(2) Mixing the borosilicate-containing coating agent, the iron-silicon magnetic powder and a second solvent acetone according to a mass ratio of 0.01 to 10, so as to obtain coated soft magnetic powder; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and a binding agent silicone resin, drying, then adding a release agent aluminum stearate, and sequentially carrying out compression molding under the pressure of 1000MPa and annealing treatment at the temperature of 500 ℃ in a nitrogen atmosphere for 8 hours to obtain a borosilicate coated metal soft magnetic powder core; the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10.01.
Example 6
The embodiment provides a preparation method of a borosilicate-coated metal soft magnetic powder core, which comprises the following steps:
(1) Firstly, mixing polydimethylsiloxane and boric acid powder according to the mass ratio of 10; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 80 ℃ for 1h to obtain a borosilicate-containing coating agent;
the purity of the boric acid powder is 99.98%; the particle size of the boric acid powder is 50 μm; the mass concentration of the catalyst is 10mol/mL; the addition amount of the water is 5wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.15MPa;
(2) Mixing the boron-silicon-containing coating agent, the iron-silicon-aluminum magnetic powder and a second solvent acetone according to a mass ratio of 0.5; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and a binding agent silicone resin, drying, then adding a release agent zinc stearate, and sequentially carrying out compression molding at 3000MPa and annealing treatment at 800 ℃ in a nitrogen atmosphere for 0.1h to obtain a borosilicate-coated metal soft magnetic powder core; the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10.1.
Example 7
This example provides a method for producing a borosilicate-coated metallic soft magnetic powder core, which is the same as in example 1 except that the mass ratio of siloxane to boric acid powder in step (1) is 10.5 instead of 10.
Example 8
This example provides a method for producing a borosilicate-coated metallic soft magnetic powder core, which is the same as in example 1 except that the mass ratio of siloxane to boric acid powder in step (1) is 10.5 instead of 10.
Example 9
This example provides a method for producing a borosilicate-coated metallic soft magnetic powder core, which is the same as in example 1 except that the pressure for press molding in step (3) is 500MPa instead of 1500 MPa.
Example 10
This example provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, which is the same as in example 1 except that the pressure for press molding in step (3) is replaced with 3500MPa instead of 1500 MPa.
Example 11
This example provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, which is the same as in example 1 except that the annealing temperature in step (3) is changed from 600 ℃ to 400 ℃.
Example 12
This example provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, which is the same as in example 1 except that the annealing temperature in step (3) is changed from 600 ℃ to 900 ℃.
Comparative example 1
The present comparative example provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, the method comprising the steps of:
the 500-mesh iron-nickel magnetic powder is passivated in phosphoric acid, 0.5wt% of kaolin is added for insulation coating, and 0.3wt% of silicon resin is added for secondary coating. Adding phenolic resin serving as a binder and zinc stearate serving as a release agent into the coated magnetic powder, performing compression molding under 1500MPa, and annealing at 600 ℃ in a nitrogen atmosphere to obtain a ring sample.
Comparative example 2
This comparative example provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, which is the same as in example 1 except that boric acid powder is not added in step (1).
Comparative example 3
The present comparative example provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, which is the same as in comparative example 1 except that iron and nickel are replaced with iron-silicon magnetic powder.
Comparative example 4
The present comparative example provides a method for preparing a borosilicate-coated metallic soft magnetic powder core, which is the same as in comparative example 1 except that iron nickel is replaced with sendust.
The permeability and magnetic loss results of the borosilicate-coated metallic soft magnetic powder cores obtained in the above examples and comparative examples are shown in table 1.
TABLE 1
As can be seen from table 1:
(1) It can be seen from the above results in examples 1 to 6 that when the raw material is Fe-Ni magnetic powder, the magnetic permeability of the obtained borosilicate-coated metallic soft magnetic powder core can reach 125 or more, and the loss can reach 133mW/cm under the conditions of 50kHz,100mT 3 In the following, inUnder the conditions of 100kHz and 100mT, the loss can reach 287mW/cm 3 The following; when the raw material is iron-silicon magnetic powder, the magnetic conductivity of the obtained borosilicate-coated metal soft magnetic powder core can reach more than 56, and the loss can reach 749mW/cm under the conditions of 50kHz,100mT 3 The loss can reach 1783mW/cm under the conditions of 100kHz and 100mT 3 The following; when the raw material is Fe-Si-Al-Si magnetic powder, the magnetic conductivity of the obtained borosilicate-coated metal soft magnetic powder core can reach more than 60, and the loss can reach 132mW/cm under the conditions of 50kHz,100mT 3 The loss can reach 272mW/cm under the conditions of 100kHz and 100mT 3 The following;
(2) It can be seen from the combination of example 1 and examples 7 to 8 that, when the mass ratio of siloxane to boric acid powder in step (1) of example 7 is 10.1, the magnetic permeability of the obtained borosilicate-coated metallic soft magnetic powder core is significantly reduced as compared with example 1; however, the losses at 50kHz,100mT and at 100kHz,100mT were comparable to those of example 1; in the step (1) of example 8, the mass ratio of siloxane to boric acid powder is 10, the magnetic permeability of the obtained borosilicate-coated metal soft magnetic powder core is 132, the magnetic permeability is slightly improved, but the loss is obviously increased;
(3) It can be seen from the combination of example 1 and examples 9 to 10 that the pressure for press molding in step (3) of example 9 is low, and the magnetic permeability of the obtained borosilicate-coated metallic soft magnetic powder core is low, 76; example 10 the press molding pressure in step (3) was high, and the obtained borosilicate-coated metallic soft magnetic powder core had a magnetic permeability higher than that of example 1 and was 141; however, the loss of the borosilicate-coated metallic soft magnetic powder core obtained in examples 9 and 10 was much higher than that of example 1;
(4) It can be seen from the combination of example 1 and examples 11 to 12 that the annealing temperature in step (3) of example 11 is low, and the permeability of the obtained borosilicate-coated metallic soft magnetic powder core is slightly lower than that of example 1, but the loss is much higher than that of example 1; example 12 the annealing temperature in step (3) was higher and the permeability of the obtained borosilicate-coated metallic soft magnetic powder core was comparable to that of example 1, but the loss was as high as 1210mW/cm under the conditions of 100kHz,100mT 3 ；
(5) By combining the example 1 with the comparative example 1, the example 3, the example 5 with the comparative example 3, and the example 4, the example 6 with the comparative example 4, it can be seen that the preparation method of the borosilicate-coated metal soft magnetic powder core provided by the invention is applied to raw materials of iron-nickel, iron-silicon, and iron-silicon-aluminum magnetic powder, and compared with the methods of the comparative example 1, the comparative example 3, and the comparative example 4, the obtained borosilicate-coated metal soft magnetic powder core has high magnetic permeability and low loss;
(6) It can be seen from the combination of example 1 and comparative example 2 that step (1) of comparative example 2 does not add boric acid powder, and the obtained metallic soft magnetic powder core has slightly lower magnetic permeability than example 1, but much higher loss than example 1.
In summary, the preparation method of the borosilicate-coated metal soft magnetic powder core provided by the invention adopts a specific mass ratio of siloxane to boric acid powder, and utilizes the boric acid powder as a raw material to carry out chemical organic synthesis on the borosilicate-containing coating under the conditions of specific pressure for press molding and specific annealing temperature, so that the insulation coating on the surface of the metal soft magnetic powder core is effectively improved, the resistance of the magnetic powder core is improved, and the obtained borosilicate-coated metal soft magnetic powder core has excellent magnetic performance, high magnetic permeability and low magnetic loss.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. A preparation method of a borosilicate-coated metal soft magnetic powder core is characterized by comprising the following steps:
(1) Mixing siloxane, boric acid powder, a first solvent, a catalyst and water, carrying out hydrolysis reaction, and carrying out polycondensation reaction on a hydrolysate to obtain a coating agent containing borosilicate;
(2) Mixing the borosilicate-containing coating agent, the soft magnetic powder and a second solvent to obtain coated soft magnetic powder;
(3) And mixing the coated soft magnetic powder, the binder and the release agent, and sequentially performing compression molding and annealing treatment to obtain the borosilicate-coated metal soft magnetic powder core.
2. The method of claim 1, wherein the step of mixing the siloxane, the boric acid powder, the first solvent, the catalyst, and the water in step (1) comprises: firstly mixing siloxane and boric acid powder to obtain a mixed solution, then adding a first solvent and a catalyst, stirring, heating to 50-100 ℃, and then adding water.
3. The production method according to claim 1 or 2, characterized in that the siloxane of step (1) comprises polydimethylsiloxane and/or dimethyldiethoxysilane;
preferably, the purity of the boric acid powder is more than 99.9%;
preferably, the particle size of the boric acid powder is 5-50 μm;
preferably, the mass ratio of the siloxane to the boric acid powder is 10 (0.5-3).
4. The method according to any one of claims 1 to 3, wherein the first solvent of step (1) comprises any one of methanol, ethanol, isopropanol or n-butanol or a combination of at least two thereof;
preferably, the catalyst comprises any one of hydrochloric acid, sulfuric acid or nitric acid or a combination of at least two thereof;
preferably, the mass concentration of the catalyst is 2-10 mol/mL;
preferably, the volume ratio of the first solvent to the catalyst is 10 (0.1-0.5);
preferably, the water comprises deionized water;
preferably, the addition amount of the water is 1 to 5 percent of the mass of the siloxane and the boric acid powder;
preferably, the time of the hydrolysis reaction is 0.5 to 5 hours.
5. The production method according to any one of claims 1 to 4, wherein the polycondensation reaction in step (1) is carried out in a distillation apparatus;
preferably, the hydrolysate is distilled under reduced pressure in the distillation apparatus;
preferably, the vacuum degree of the reduced pressure distillation is 0.02-0.15 MPa;
preferably, the temperature of the polycondensation reaction is 80-150 ℃;
preferably, the time of the polycondensation reaction is 1 to 20 hours.
6. The production method according to any one of claims 1 to 5, wherein the mass ratio of the borosilicate-containing cladding agent, the soft magnetic powder and the second solvent in step (2) is (0.01 to 0.5) to (10) (0.5 to 1.5);
preferably, the soft magnetic powder comprises any one or a combination of at least two of iron-nickel magnetic powder, iron-silicon-aluminum magnetic powder, iron-nickel-molybdenum magnetic powder, amorphous magnetic powder or nanocrystalline magnetic powder;
preferably, the second solvent comprises acetone;
preferably, the coated soft magnetic powder is further sequentially subjected to drying and sieving.
7. The production method according to any one of claims 1 to 6, wherein the step of mixing the coated soft magnetic powder, the binder and the release agent in step (3) comprises: firstly, mixing the coated soft magnetic powder and the binder, drying, and then adding a release agent;
preferably, the mass ratio of the coated soft magnetic powder, the binder and the release agent is 10 (0.01-0.1) to (0.01-0.1);
preferably, the binder comprises any one of silicone, epoxy or phenolic resin or a combination of at least two thereof;
preferably, the release agent comprises any one or a combination of at least two of zinc stearate, aluminum stearate, or graphite.
8. The production method according to any one of claims 1 to 7, wherein the pressure for press molding in step (3) is 1000 to 3000MPa;
preferably, the annealing treatment is performed in a nitrogen atmosphere;
preferably, the temperature of the annealing treatment is 500-800 ℃;
preferably, the time of the annealing treatment is 0.1 to 8 hours.
9. The production method according to any one of claims 1 to 8, characterized by comprising the steps of:
(1) Firstly, mixing siloxane and boric acid powder according to the mass ratio of 10 (0.5-3) to obtain a mixed solution, then adding a first solvent and a catalyst according to the volume ratio of 10 (0.1-0.5), stirring and heating to 50-100 ℃, then adding water, and carrying out hydrolysis reaction for 0.5-5 h; carrying out reduced pressure distillation on the hydrolysate in a distillation device, and carrying out polycondensation reaction at the temperature of 80-150 ℃ for 1-20 h to obtain a coating agent containing borosilicate;
the siloxane comprises polydimethylsiloxane and/or dimethyldiethoxysilane; the purity of the boric acid powder is more than 99.9%; the particle size of the boric acid powder is 5-50 mu m; the first solvent comprises any one or the combination of at least two of methanol, ethanol, isopropanol or n-butanol; the catalyst comprises any one or the combination of at least two of hydrochloric acid, sulfuric acid or nitric acid; the mass concentration of the catalyst is 2-10 mol/mL; the water comprises deionized water; the addition amount of the water is 1-5 wt% of the mass of the siloxane and the boric acid powder; the vacuum degree of the reduced pressure distillation is 0.02-0.15 MPa;
(2) Mixing the coating agent containing borosilicate, the soft magnetic powder and the second solvent according to the mass ratio of (0.01-0.5) to (10) (0.5-1.5) to obtain coated soft magnetic powder;
the soft magnetic powder comprises any one or the combination of at least two of iron-nickel magnetic powder, iron-silicon-aluminum magnetic powder or iron-nickel-molybdenum magnetic powder; the second solvent comprises acetone; the coated soft magnetic powder is further sequentially subjected to drying and screening treatment;
(3) Firstly, mixing the coated soft magnetic powder and a binder, drying, then adding a release agent, and sequentially carrying out compression molding at the pressure of 1000-3000 MPa and annealing treatment at the temperature of 500-800 ℃ for 0.1-8 h in a nitrogen atmosphere to obtain a borosilicate-coated metal soft magnetic powder core;
the mass ratio of the coated soft magnetic powder, the adhesive and the release agent is 10 (0.01-0.1) to 0.01-0.1; the binder comprises any one or a combination of at least two of silicone resin, epoxy resin or phenolic resin; the release agent comprises any one or a combination of at least two of zinc stearate, aluminum stearate or graphite.
10. A borosilicate-coated metallic soft magnetic powder core, which is produced by the method for producing a borosilicate-coated metallic soft magnetic powder core according to any one of claims 1 to 9.
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| PCT/CN2023/127840 WO2024088426A1 (en) | 2022-10-28 | 2023-10-30 | Boron- and silicon-coated metal soft magnetic powder core and preparation method therefor |
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| CN110246679B (en) * | 2019-07-31 | 2020-12-22 | 合肥工业大学 | Preparation method of metal soft magnetic powder core based on organic/inorganic composite insulation process |
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