Adhesive, soft magnetic composite material and preparation method and preparation equipment of soft magnetic composite material

Abstract

The invention discloses an adhesive, a soft magnetic composite material as well as a preparation method and preparation equipment of the soft magnetic composite material, and the adhesive comprises the following components in percentage by mass: 10-40% of a bonding component, 20-40% of a strength enhancing component, 20-40% of a lubricating component and 5-15% of a thixotropic component. According to the adhesive disclosed by the invention, through regulation and control of the components such as the bonding component, the strength enhancing component, the lubricating component and the thixotropic component, the bonding and strength enhancing effects of the adhesive are favorably improved, so that the adhesive has lubricating and antifriction functions, the adhesive can be directly pressed into a soft magnetic composite material after being coated with the magnetic powder, a lubricant does not need to be added, the cost can be reduced, and the application range is wide. Meanwhile, the component uniformity of the soft magnetic composite material can be improved, the strength of the soft magnetic composite material is improved, and the problems of pressing layering, edge falling or corner falling and the like are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of soft magnetic composite materials, and in particular to an adhesive, a soft magnetic composite material, and a preparation method and preparation equipment thereof. Background Art

[0002] In recent years, as power electronic devices have progressed towards miniaturization, higher power, and higher efficiency, third-generation wide-bandgap semiconductor materials, represented by gallium nitride (GaN) and silicon carbide (SiC), have gradually become rising stars in the market. The development and application of third-generation semiconductors have also placed higher demands on the performance of their supporting magnetic components, driving their development towards higher frequency, higher power, miniaturization, and energy conservation. To meet these higher magnetic performance requirements, soft magnetic composites have been prepared by combining different magnetic powders. This approach combines the advantages of two or more magnetic powders while offsetting the shortcomings of a single material. These soft magnetic composites combine the high magnetic permeability of metallic soft magnetic materials with the high resistivity of soft ferrites, resulting in high resistivity, high permeability, low loss, high saturation magnetic induction, good DC bias characteristics, and a wide range of applicable frequencies. However, during the magnetic powder mixing process, differences in particle size, morphology, and / or density can easily lead to component segregation, resulting in problems such as low strength and susceptibility to fracture in the resulting soft magnetic composites. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the first object of the present invention is to provide an adhesive that, after coating magnetic powder, can be directly pressed into a soft magnetic composite material. This adhesive improves the compositional uniformity and strength of the soft magnetic composite material, and avoids problems such as delamination, edge or corner chipping during pressing.

[0004] The second object of the present invention is to provide a soft magnetic composite material.

[0005] The third object of the present invention is to provide a method for preparing a soft magnetic composite material.

[0006] The fourth object of the present invention is to provide a preparation device for soft magnetic composite materials.

[0007] The adhesive according to the embodiment of the first aspect of the present invention comprises, by mass percentage, 10% to 40% of a bonding component, 20% to 40% of a strength enhancing component, 20% to 40% of a lubricating component, and 5% to 15% of a thixotropic component.

[0008] According to the adhesive of the embodiment of the present invention, the regulation of components such as bonding components, strength enhancing components, lubricating components and thixotropic components is conducive to improving the bonding and strength enhancing effects of the adhesive, so that the adhesive has both lubrication and friction reduction functions. After the adhesive is coated with magnetic powder, it can be directly pressed into a soft magnetic composite material without the need to add lubricant, which can reduce costs and improve production efficiency. At the same time, it can improve the uniformity of the composition of the soft magnetic composite material, improve the strength of the soft magnetic composite material, and avoid problems such as pressing delamination, edge or corner falling.

[0009] According to some embodiments of the present invention, the bonding component includes at least one of paraffin wax, polyamide wax, polyvinyl alcohol, epoxy resin, phenolic resin and acrylic resin; and / or the strength enhancing component includes sodium silicate and / or silicone resin; and / or the lubricating component includes at least one of stearic acid, ethylene bisstearamide, lauric acid and isooctanoic acid; and / or the thixotropic component includes polyethylene wax and / or microcrystalline wax.

[0010] According to some embodiments of the present invention, when the bonding component includes paraffin wax, the content of the paraffin wax in the adhesive is 5% to 15% by mass; when the bonding component includes polyamide wax, the content of the polyamide wax in the adhesive is 5% to 10% by mass; when the bonding component includes polyvinyl alcohol, the content of the polyvinyl alcohol in the adhesive is 0% to 15% by mass; when the bonding component includes epoxy resin, the content of the epoxy resin in the adhesive is 0% to 10% by mass; when the bonding component includes phenolic resin, the content of the phenolic resin in the adhesive is 0% to 10% by mass; when the bonding component includes acrylic resin, the content of the acrylic resin in the adhesive is 0% to 10% by mass.

[0011] According to some embodiments of the present invention, when the strength enhancing component includes sodium silicate, the content of sodium silicate in the adhesive is 15% to 35% by mass; when the strength enhancing component includes silicone resin, the content of the silicone resin in the adhesive is 5% to 25% by mass.

[0012] According to some embodiments of the present invention, when the lubricating component includes stearic acid, the content of the stearic acid in the adhesive is 5% to 10% by mass; when the lubricating component includes ethylene bisstearamide, the content of the ethylene bisstearamide in the adhesive is 10% to 30% by mass; when the lubricating component includes lauric acid, the content of the lauric acid in the adhesive is 0% to 5% by mass; when the lubricating component includes isooctanoic acid, the content of the isooctanoic acid in the adhesive is 0% to 1% by mass.

[0013] According to some embodiments of the present invention, when the thixotropic component includes polyethylene wax, the content of the polyethylene wax in the adhesive is 5% to 15% by mass; when the thixotropic component includes microcrystalline wax, the content of the microcrystalline wax in the adhesive is 5% to 15% by mass.

[0014] The soft magnetic composite material according to the second embodiment of the present invention includes: magnetic powder and an adhesive, wherein the adhesive is the adhesive according to the first embodiment of the present invention.

[0015] According to some embodiments of the present invention, the magnetic powder includes pure iron powder or soft magnetic alloy powder, wherein the soft magnetic alloy powder includes at least one of FeSi powder, FeSiAl powder, FeSiCr powder, FeCo powder, FeNi powder, FeNiMo powder and FeSiB amorphous nanocrystalline powder.

[0016] According to some embodiments of the present invention, the added amount of the adhesive is 0.1 wt.% to 3 wt.% by mass.

[0017] According to some embodiments of the present invention, the soft magnetic composite material further comprises: an insulating layer, the insulating layer being coated on the surface of the magnetic powder particles, the insulating layer comprising: at least one of phosphate, aluminum oxide, silicon dioxide, zirconium dioxide, magnesium oxide, ferroferric oxide, MnZn ferrite and NiZn ferrite The method for preparing a soft magnetic composite material according to the third embodiment of the present invention comprises the following steps: Pretreatment of magnetic powder; Coating adhesive treatment, wherein the coating adhesive treatment comprises: The adhesive is dissolved in a solvent to form an adhesive solution, and the adhesive solution is mixed with the pretreated magnetic powder to obtain a soft magnetic composite material.

[0018] According to some embodiments of the present invention, the concentration of the adhesive solution is 0.005 g / ml to 0.05 g / ml, and the volume ratio of the adhesive solution to the mass of the magnetic powder is 150 mL / kg to 400 mL / kg.

[0019] According to some embodiments of the present invention, the adhesive solution is mixed with the magnetic powder at intervals of N times, wherein the interval time is 10 minutes to 25 minutes, and N is a positive integer greater than or equal to 3.

[0020] According to some embodiments of the present invention, the solvent includes, by mass percentage, 35% to 65% of n-heptane, 25% to 45% of any one of chloroform, acetone and ethanol, 0% to 20% of any one of chlorobenzene, N,N-dimethylacetamide and acetonitrile, and 0% to 10% of toluene or xylene.

[0021] According to some embodiments of the present invention, the temperature at which the adhesive and the solvent are mixed is 80° C. to 120° C.

[0022] According to some embodiments of the present invention, the pretreatment of the magnetic powder includes: Annealing and insulation treatment, The annealing treatment includes: annealing the magnetic powder at 500° C. to 700° C.; The insulation treatment includes: coating an insulation layer on the surface of the annealed magnetic powder.

[0023] According to a fourth embodiment of the present invention, an apparatus for preparing the soft magnetic composite material of the second embodiment of the present invention comprises: mixers and pumps, placing the pretreated magnetic powder in the mixer for dispersion; The pump adds the adhesive solution into the mixer under the action of the protective gas for mixing.

[0024] According to some embodiments of the present invention, the pressure of the protective gas is 0.1 MPa to 0.5 MPa.

[0025] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which: Figure 1 is a schematic diagram of a preparation device according to an embodiment of the present invention; Reference numerals: 100: Preparation equipment; 1: Mixer; 2: Adhesive delivery channel; 3: Protective gas delivery channel. DETAILED DESCRIPTION

[0027] The adhesive according to the first embodiment of the present invention is described below with reference to the adhesive being applied to a soft magnetic composite material as an example.

[0028] The adhesive according to the embodiment of the first aspect of the present invention includes, by mass percentage, 10% to 40% of a bonding component, 20% to 40% of a strength enhancing component, 20% to 40% of a lubricating component, and 5% to 15% of a thixotropic component.

[0029] Specifically, due to the differences in particle size, morphology, and specific gravity of the magnetic powder in the soft magnetic composite material, component segregation is very easy to occur during the mixing process. In addition, for some hard magnetic powders, the plastic deformation of the powder after pressing is small, there is no mechanical kneading, and the magnetic powder pressed is low in strength and prone to delamination, edge or corner loss, etc. The adhesive includes an appropriate amount of bonding components, strength-enhancing components, lubricating components, and thixotropic components. During the preparation of soft magnetic composite materials, the bonding reliability of the adhesive can be improved to improve the soft magnetic composite material. Among them, the addition of bonding components can effectively reduce powder segregation and facilitate the pressing and forming of magnetic powder. The decomposition of the binder component during the heat treatment process will lead to a decrease in the strength of the magnetic powder, and the strength-enhancing component will undergo a curing reaction during the annealing process, thereby providing strength for the magnetic powder after heat treatment. The addition of lubricants reduces friction between magnetic powder particles and between the powder and the mold wall during the pressing process, thus playing two roles: first, the lubricant increases the powder density, thereby improving magnetic properties such as saturation magnetic induction and permeability; second, the lubricant reduces damage to the insulating layer on the powder surface, maintaining the integrity and insulation of the layer. The role of the thixotropic component is reflected in the pressing process of the soft magnetic composite material. Under the action of the pressing pressure, the viscosity of the thixotropic component decreases, transforming from a solid to a semi-liquid state, thereby enhancing the lubricating effect of the lubricant component.

[0030] The above-mentioned limits on the content of bonding, strength-enhancing, lubricating, and thixotropic components are relatively reasonable, helping to fully utilize the bonding, strength-enhancing, lubricating, and thixotropic components while avoiding their excessive use, thereby controlling adhesive costs. In actual production, the adhesive components and content can be adjusted to meet different application requirements to achieve the target performance. After the magnetic powder is coated with adhesive, it can be directly pressed without the addition of lubricants, which can reduce costs and improve production efficiency.

[0031] Therefore, by regulating components such as bonding components, strength enhancing components, lubricating components and thixotropic components, it is beneficial to improve the bonding and strength enhancing effects of the adhesive, so that the adhesive has both lubrication and friction reduction functions, which can improve the composition uniformity of soft magnetic composite materials and solve problems such as low strength of soft magnetic composite materials, delamination during pressing, edge and corner falling.

[0032] In summary, the above adhesives have the following advantages: 1) It can improve the uniformity of magnetic powder composition, insulation coating effect, solve the problems of low strength of soft magnetic composite materials, pressing delamination, edge and corner loss, etc. According to different magnetic powders and application requirements, the target performance can be achieved by adjusting the adhesive composition and content.

[0033] 2) It is not only applicable to single magnetic powder, but also to composite magnetic powder. After adhesive coating, it can be directly pressed without adding lubricant, which can reduce costs and improve production efficiency.

[0034] According to the adhesive of the embodiment of the present invention, the regulation of components such as bonding components, strength enhancing components, lubricating components and thixotropic components is conducive to improving the bonding and strength enhancing effects of the adhesive, so that the adhesive has both lubrication and friction reduction functions. After the adhesive is coated, it can be directly pressed into a soft magnetic composite material without the need to add a lubricant, which can reduce costs and improve production efficiency. At the same time, it can improve the uniformity of the composition of the soft magnetic composite material, improve the strength of the soft magnetic composite material, and avoid problems such as pressing delamination, edge or corner falling.

[0035] According to some embodiments of the present invention, the bonding component includes at least one of paraffin wax, polyamide wax, polyvinyl alcohol, epoxy resin, phenolic resin, and acrylic resin. Among them, the bonding performance of paraffin wax itself is relatively weak, mainly relying on its ability to fill some gaps after heating and melting, and to play a certain fixing role after cooling and solidification. Polyamide wax can indirectly improve the durability and reliability of the bonding by improving the system performance, for example, improving the adhesion and wear resistance of the adhesive. Polyvinyl alcohol has certain bonding properties, moderate bonding strength, and good film-forming properties. It can form a tough film on the surface of the adherend, thereby playing a bonding and protective role. Epoxy resin has excellent bonding properties, low shrinkage after curing, high bonding strength, water resistance, chemical corrosion resistance, and good electrical insulation properties. Phenolic resin has high bonding strength and good heat resistance, and can maintain good bonding performance at high temperatures. Acrylic resin adhesives have good transparency, weather resistance and bonding strength, fast curing speed, and can meet different performance requirements such as flexibility and hardness by adjusting the formula.

[0036] Therefore, using at least one of paraffin wax, polyamide wax, polyvinyl alcohol, epoxy resin, phenolic resin and acrylic resin as a bonding component helps to improve the bonding performance of the adhesive, so that the bonding strength of the adhesive is suitable for the use requirements of the soft magnetic composite material.

[0037] Strength-enhancing components include sodium silicate and / or silicone resin. Sodium silicate is used as an adhesive to improve the water resistance and weather resistance of the soft magnetic composite material. Silicone resin has good flexibility and elasticity, excellent weather resistance, water resistance, heat resistance and electrical insulation. The silicon-oxygen bond in its molecular structure enables it to remain stable at high temperatures and not easily decomposed; at the same time, the presence of organic groups gives it certain organic compound properties and is compatible with a variety of organic materials. Therefore, the use of sodium silicate and / or silicone resin as a strength-enhancing component helps to improve the strength of the adhesive, thereby helping to improve the strength of the soft magnetic composite material and extend the service life and reliability of the soft magnetic composite material.

[0038] The lubricating components include at least one of stearic acid, ethylene bisstearamide (EBS), lauric acid, and isooctanoic acid. Stearic acid molecules are composed of long-chain hydrocarbon groups and carboxyl groups. The long-chain hydrocarbon groups are lipophilic and hydrophobic, forming a directional molecular film on the surface of objects, reducing friction and providing lubrication. The carboxyl groups can bind to active sites on surfaces such as metals, enhancing the adhesion of the lubricating film. The EBS molecule contains two long-chain fatty acid amide groups, which are highly hydrophobic and lubricating. At high temperatures, it can form a uniform lubricating film on the surface of materials (such as magnetic powder), reducing intermolecular friction within the material while also providing insulation and lubrication between the material and the surface of processing equipment.

[0039] The molecular structure of lauric acid is similar to that of stearic acid, but its carbon chain length is shorter and its relative molecular mass is smaller. It has better fluidity and permeability, and can quickly form a lubricating film on the friction surface to reduce friction resistance. At the same time, the carboxyl group in lauric acid can react chemically with the metal surface to form a chemically bonded lubricating film, thereby improving the durability of lubrication.

[0040] The molecular structure of isooctanoic acid has certain side chains, which give it unique physical and chemical properties. Isooctanoic acid achieves lubrication by forming an adsorption film or chemical reaction film on the metal surface. Its acidic group can react with the metal surface to generate metal soap substances with lubricating properties, thereby reducing friction.

[0041] Therefore, the use of at least one of the above-mentioned lubricating components is beneficial to improving the lubrication performance of the adhesive, eliminating the process of adding lubricant before pressing the soft magnetic composite material, thereby helping to simplify the preparation process of the soft magnetic composite material and improve the preparation efficiency of the soft magnetic composite material.

[0042] Thixotropic components include polyethylene wax and / or microcrystalline wax. Polyethylene wax is harder and has a relatively higher melting point, making it suitable for providing good lubricity to adhesives. Microcrystalline wax is softer and has better ductility, making it suitable for providing high flexibility and viscosity to adhesives. Furthermore, both polyethylene wax and microcrystalline wax can transform from a solid to a liquid during the pressing process, reducing viscosity and providing a lubricating effect.

[0043] Furthermore, when the adhesive component includes paraffin wax, the content of the paraffin wax in the adhesive is 5% to 15% by mass. When the adhesive component includes polyamide wax, the content of the polyamide wax in the adhesive is 5% to 10% by mass. When the adhesive component includes polyvinyl alcohol, the content of the polyvinyl alcohol in the adhesive is 0% to 15% by mass. When the adhesive component includes epoxy resin, the content of the epoxy resin in the adhesive is 0% to 10% by mass. When the adhesive component includes phenolic resin, the content of the phenolic resin in the adhesive is 0% to 10% by mass. When the adhesive component includes acrylic resin, the content of the acrylic resin in the adhesive is 0% to 10% by mass.

[0044] At least one of the polyvinyl alcohol, epoxy resin, phenolic resin, and acrylic resin in the adhesive component may not be added. Therefore, using a reasonable amount of at least one of paraffin wax, polyamide wax, polyvinyl alcohol, epoxy resin, phenolic resin, and acrylic resin as the adhesive component can fully enhance the adhesive's bonding properties while avoiding side effects (such as reduced fluidity) caused by excessive amounts of any one component, and can also reasonably control the adhesive's cost.

[0045] According to some embodiments of the present invention, when the strength-enhancing component includes sodium silicate, the content of sodium silicate in the adhesive is 15% to 35% by mass. When the strength-enhancing component includes silicone resin, the content of silicone resin in the adhesive is 5% to 25% by mass. The addition amounts of sodium silicate and silicone resin are reasonable, helping to fully exert their effects while avoiding excessive use that would increase the strength of the adhesive and make it more difficult to press.

[0046] According to other embodiments of the present invention, when the lubricating component includes stearic acid, the content of stearic acid in the adhesive is 5% to 10% by mass. When the lubricating component includes ethylene bisstearamide, the content of ethylene bisstearamide in the adhesive is 10% to 30% by mass. When the lubricating component includes lauric acid, the content of lauric acid in the adhesive is 0% to 5% by mass. When the lubricating component includes isooctanoic acid, the content of isooctanoic acid in the adhesive is 0% to 1% by mass.

[0047] Among them, lauric acid and isooctanoic acid can be omitted. Therefore, the addition amounts of stearic acid, ethylene bisstearamide (EBS), lauric acid, and isooctanoic acid are relatively reasonable, which helps to improve the lubrication properties of the adhesive, improve the magnetic properties of the soft magnetic composite material, and enhance the integrity of the coating on the surface of the magnetic powder particles during the pressing process.

[0048] According to further embodiments of the present invention, when the thixotropic component includes polyethylene wax, the content of the polyethylene wax in the adhesive is 5% to 15% by weight. When the thixotropic component includes microcrystalline wax, the content of the microcrystalline wax in the adhesive is 5% to 15% by weight. Therefore, the appropriate amount of polyethylene wax and / or microcrystalline wax helps fully utilize the lubricating effect during the pressing process while avoiding affecting the adhesive's bonding effect.

[0049] The soft magnetic composite material according to the second embodiment of the present invention includes: magnetic powder and an adhesive, and the adhesive is the adhesive according to the first embodiment of the present invention.

[0050] According to the soft magnetic composite material of the embodiment of the present invention, the use of the above-mentioned adhesive helps to improve the compaction density and magnetic properties of the prepared soft magnetic composite material, thereby improving the applicability of the soft magnetic composite material and enhancing the market competitiveness of the soft magnetic composite material.

[0051] Furthermore, the magnetic powder includes pure iron powder or soft magnetic alloy powder. Pure iron powder has a high initial magnetic permeability, can be quickly magnetized in a weak magnetic field, effectively gather and conduct magnetic lines of force, which is conducive to making the soft magnetic composite material have the advantage of high sensitivity magnetic response. In addition, the soft magnetic composite material prepared by using pure iron powder as magnetic powder is easy to demagnetize after magnetization, that is, when the external magnetic field is removed, the soft magnetic composite material retains weak magnetism and can quickly respond to changes in the magnetic field, making it suitable for frequent changes in the direction and intensity of the magnetic field. Soft magnetic alloy powder has a high resistivity, which helps to reduce the eddy current loss of soft magnetic alloy powder in the alternating magnetic field, reduce energy loss, and improve the use efficiency and performance of soft magnetic alloy powder.

[0052] The pure iron powder or soft magnetic alloy powder may be spherical, or may have irregular shapes such as flakes or sponges, without specific limitation.

[0053] Soft magnetic alloy powders include at least one of FeSi powder, FeSiAl powder, FeSiCr powder, FeCo powder, FeNi powder, FeNiMo powder, and FeSiB amorphous nanocrystalline powder. FeSi powder has advantages such as excellent DC superposition characteristics, strong energy storage capacity, high saturation magnetic induction, good corrosion resistance, and temperature stability. It also features low oxygen content, low losses, good DC bias magnetic properties, and stable magnetic properties. FeSiAl powder has high magnetic permeability and saturation magnetic induction, low losses, good DC bias characteristics, and certain corrosion and oxidation resistance, maintaining good magnetic properties at high frequencies. FeSiCr powder has advantages such as good stability, high magnetic permeability, good dielectric strength, and excellent saturation characteristics. FeCo powder has a saturation magnetic flux density (Bs) as high as 2.4T and a Curie temperature between 980°C and 1100°C. It also has good DC bias characteristics, low losses, and good temperature stability. FeNi powder has high saturation magnetization and high magnetic permeability. By adjusting the ratio of nickel to iron, the resistivity, magnetic permeability, and magnetoelectric conversion performance can be optimized. FeNiMo powder is produced using gas and water atomization processes and exhibits high saturation flux density, low loss, and excellent DC superposition characteristics. FeSiB amorphous nanocrystalline powder has excellent soft magnetic properties, including high saturation magnetic induction intensity, high magnetic permeability, low coercivity, and manufacturing flexibility, which can enhance magnetic properties and reduce inductor size.

[0054] Therefore, by using at least one of FeSi powder, FeSiAl powder, FeSiCr powder, FeCo powder, FeNi powder, FeNiMo powder and FeSiB amorphous nanocrystalline powder as soft magnetic alloy powder, the prepared soft magnetic composite material can withstand high voltage and large current, effectively transmit and convert electrical energy, and improve the efficiency and stability of the power system.

[0055] According to some embodiments of the present invention, the amount of adhesive added is 0.1 wt.% to 3 wt.% by mass. The amount of adhesive added is relatively reasonable, which is beneficial to improving the mechanical strength, compressive strength and tensile strength of the soft magnetic composite material using the above-mentioned adhesive, reducing the stress inside the soft magnetic composite material, and improving the toughness of the soft magnetic composite material. At the same time, a reasonable adhesive content is conducive to reducing porosity, thereby ensuring the density of the soft magnetic composite material and the shrinkage rate during the sintering process. In addition, the appropriate adhesive content can improve the fluidity of the magnetic powder and the adhesive, making the soft magnetic composite material easy to demold and having a good surface finish.

[0056] According to some other embodiments of the present invention, the soft magnetic composite material further includes: an insulating layer, the insulating layer being coated on the surface of the magnetic powder particles, the insulating layer including: at least one of phosphate, aluminum oxide, silicon dioxide, zirconium dioxide, magnesium oxide, ferroferric oxide, MnZn ferrite and NiZn ferrite.

[0057] Phosphates have good heat resistance and chemical stability and are suitable for increasing the high-temperature insulation properties of soft magnetic composite materials. Aluminum oxide has high mechanical strength, good thermal stability, and excellent electrical insulation properties. Silicon dioxide is also an excellent insulating material. Zirconium dioxide has the advantages of high hardness, wear resistance, and good chemical inertness, which are conducive to meeting the corrosion resistance and high strength requirements of soft magnetic composite materials. Magnesium oxide has high thermal conductivity and good electrical insulation properties. Magnetic powder coated with ferroferric oxide, MnZn ferrite, and / or NiZn ferrite can effectively increase the resistivity of soft magnetic composite materials, and because of their magnetic properties, the magnetic permeability decreases less, which is conducive to maintaining high magnetic properties.

[0058] Therefore, the magnetic powder itself has high conductivity and is prone to generate eddy current loss in high-frequency applications, causing the soft magnetic composite material to heat up and deteriorate in magnetic properties. Selecting at least one of the above materials as an insulating layer can increase the resistivity between magnetic powder particles and limit the eddy current between particles, thereby effectively reducing eddy current loss and improving the performance of the soft magnetic composite material at high frequencies.

[0059] The selection of the specific insulating layer depends on the type of magnetic powder and the magnetic performance parameter index.

[0060] The method for preparing a soft magnetic composite material according to the third embodiment of the present invention comprises the following steps: Pretreatment of magnetic powder; Coating adhesive treatment, wherein the coating adhesive treatment includes: The adhesive is dissolved in a solvent to form an adhesive solution, and the adhesive solution is mixed with the pretreated magnetic powder to obtain a soft magnetic composite material.

[0061] The method for preparing the soft magnetic composite material according to the embodiment of the present invention simplifies the preparation method, which is beneficial to improving the preparation efficiency of the soft magnetic composite material.

[0062] Furthermore, the concentration of the adhesive solution is 0.005 g / ml to 0.05 g / ml, and the volume ratio of the adhesive solution to the mass of the magnetic powder is 150 mL / kg to 400 mL / kg. Thus, within the above concentration range, the adhesive solution helps to fully exert its adhesive effect, thereby stably and densely adhering to the surface of the magnetic powder. At the same time, the ratio of the adhesive to the magnetic powder is relatively reasonable, and the adhesive can fully bond all the magnetic powders, resulting in better integrity of the formed soft magnetic composite material and improved toughness of the soft magnetic composite material.

[0063] According to some embodiments of the present invention, the adhesive solution is mixed with the magnetic powder at intervals of N times, wherein the interval time is 10 minutes to 25 minutes, and N is a positive integer greater than or equal to 3. The interval of 10 minutes to 25 minutes between each addition of the adhesive solution helps to fully mix the added adhesive solution and the magnetic powder, so that the adhesive can be fully filled between the magnetic powder particles, thereby improving the integrity of the prepared soft magnetic composite material.

[0064] According to some specific embodiments of the present invention, the solvent includes, by mass percentage, 35% to 65% of n-heptane, 25% to 45% of any one of chloroform, acetone and ethanol, 0% to 20% of any one of chlorobenzene, N,N-dimethylacetamide and acetonitrile, and 0% to 10% of toluene or xylene. The selection of the above solvents is conducive to fully dissolving the adhesive, thereby improving the integrity and uniformity of the formed adhesive solution, and is conducive to fully filling the pores between the magnetic powder particles, thereby helping to improve the quality of the soft magnetic composite material. In addition, the amount of each of the above solvents added is relatively reasonable, which not only satisfies the dissolution of the adhesive, but also helps to ensure the compatibility between the solvent and the adhesive, so that the fluidity and viscosity of the adhesive solution are balanced.

[0065] The adhesive component and solvent component and their ratio in the specific adhesive solution can be adjusted appropriately.

[0066] Furthermore, the temperature of mixing the adhesive and the solvent is 80° C. to 120° C. The above temperature is required for the dissolution of the adhesive, thereby increasing the dissolution efficiency and improving the uniformity of the adhesive solution.

[0067] According to some embodiments of the present invention, the pretreatment of magnetic powder includes: Annealing and insulation treatment, The annealing treatment includes annealing the magnetic powder at 500° C. to 700° C. Annealing the magnetic powder within the above temperature range helps to remove the internal stress of the magnetic powder and improve the compaction performance of the magnetic powder.

[0068] The main reasons for magnetic powder annealing include the following: 1. During the preparation of magnetic powder, such as melt spinning and atomization, residual stress is generated, which affects the magnetic properties of the prepared soft magnetic composite material, resulting in a decrease in magnetic permeability and an increase in loss. Annealing can effectively release these residual stresses, thereby improving the magnetic permeability and reducing the loss of the soft magnetic composite material.

[0069] 2. Improving the magnetic powder pressing performance can increase the magnetic powder density of soft magnetic composite materials and obtain higher saturation magnetic induction intensity and magnetic permeability.

[0070] 3. Optimize the microstructure of magnetic powder, reduce defects, and promote grain growth, thereby increasing the saturation magnetic induction intensity and reducing the coercive force of soft magnetic composite materials. In addition, annealing can also improve the magnetic domain structure of magnetic powder and reduce hysteresis loss.

[0071] Insulation treatment involves applying an insulating layer to the surface of the annealed magnetic powder. This treatment, which coats the surface of the magnetic powder with a layer of high-resistivity insulating material (insulation layer), effectively reduces eddy current losses and improves the performance of the magnetic powder at high frequencies.

[0072] The annealed magnetic powder is coated with an insulating layer using physical or chemical methods. Insulation treatment methods include physical methods such as mechanical mixing and ball milling, and chemical methods such as hydrothermal treatment, phosphating, and sol-gel treatment. The specific coating process depends on the target insulation layer.

[0073] For multi-component composite magnetic powder, different types of magnetic powder can adopt different insulation coating processes and insulation layers.

[0074] According to a fourth embodiment of the present invention, an apparatus 100 for preparing the soft magnetic composite material of the second embodiment of the present invention includes a mixer 1 and a pump. The pretreated magnetic powder is placed in the mixer 1 for dispersion. The dispersion time can be 15 minutes to 45 minutes. The magnetic powder obtained after annealing and insulation treatment is placed in the mixer 1 according to the proportion. The blade speed in the mixer 1 is set to 200 r / min to 300 r / min to disperse the magnetic powder agglomerated during the insulation treatment.

[0075] Place the adhesive and multi-component organic solvent in a storage tank, heat to 80°C to 120°C, and mechanically stir until the adhesive is completely dissolved to form an adhesive solution.

[0076] The pump adds the adhesive solution to the mixer 1 under the action of the protective gas for mixing. The pump can be a peristaltic pump, which is not specifically limited here.

[0077] The adhesive solution is added to mixer 1 in multiple batches using a pump and protective gas, with intervals of 15 to 45 minutes between each addition to ensure complete evaporation of the organic solvent. This results in a bonded and mixed magnetic powder. This powder is then pressed and annealed to produce a soft magnetic composite material. The pump extracts the adhesive solution, which is then added to the mixing system through an atomizing nozzle under the action of protective gas and uniformly mixed with the magnetic powder.

[0078] The preparation device 100 of the soft magnetic composite material according to the embodiment of the present invention is beneficial to the preparation and use of the soft magnetic composite material.

[0079] Furthermore, the pressure of the protective gas is 0.1 MPa to 0.5 MPa. The protective gas at the above pressure is conducive to ensuring the efficiency of the pump in pumping the adhesive solution, thereby improving the use efficiency of the preparation.

[0080] The protective gas may be an inert gas such as N2 or Ar, which is not specifically limited here.

[0081] The preparation equipment 100 mainly consists of a heat transfer oil temperature control, a circulation device, a conical mixer 1 (with an atomizing nozzle and an eight-leaf crushing blade), a control panel, an adhesive mixed solution storage tank, a peristaltic pump adhesive delivery channel 2, and a protective gas delivery channel 3. Figure 1 Through the atomizing nozzle and mechanical crushing, the adhesive is evenly coated on the surface of the magnetic powder, reducing the component segregation of the composite magnetic powder.

[0082] The following embodiments of the present invention are described in detail. It should be noted that the following embodiments are illustrative and are intended only to explain the present invention and are not to be construed as limiting the present invention. In addition, unless otherwise expressly stated, all reagents used in the following embodiments are commercially available or can be synthesized according to methods described herein or known methods. Reaction conditions not listed are also readily available to those skilled in the art.

[0083] Example 1 Water-atomized Fe powder and gas-atomized FeSi powder (containing 5.5% silicon) were used as raw materials. The Fe powder had a particle size of 140 μm, and the FeSi powder had a particle size of 35 μm. The Fe and FeSi powders were first annealed in a tube furnace at 550°C for 45 minutes for the Fe powder and 600°C for 1 hour for the FeSi. Then, 1 kg of Fe powder was passivated with 300 ml of a 5 wt.% phosphoric acid solution consisting primarily of ethanol. After mechanical stirring for 30 minutes, the solution was oven-dried at 60°C. The FeSi powder was coated with TiO2 via a sol-gel method through the hydrolysis and condensation of tetrabutyl titanate. A total of 300 g of FeSi powder was prepared.

[0084] The Fe phosphide powder and TiO2-coated FeSi powder were placed in mixer 1. The blade speed in mixer 1 was set to 250 r / min, and the mixture was mixed for 0.5 h to disperse any agglomerated magnetic powder during the insulation process. During this process, 6.5 g of adhesive and 390 ml of a multi-component organic solvent were placed in a storage tank, heated to 90°C, and mechanically stirred until the adhesive was completely dissolved. The adhesive components and their proportions were as follows: polyethylene wax 5 wt.%, ethylene bisstearamide 15 wt.%, paraffin wax 15 wt.%, microcrystalline wax 10 wt.%, polyamide wax 5 wt.%, stearic acid 10 wt.%, polyvinyl alcohol 10 wt.%, sodium silicate 15 wt.%, silicone resin 5 wt.%, and phenolic resin 10 wt.%. The organic solvent ratio was n-heptane: chloroform: acetonitrile: toluene = 5:3:1:1. The adhesive solution was added to mixer 1 in three batches using a peristaltic pump and high-pressure gas, with a 15-minute interval between each batch to ensure complete evaporation of the organic solvent. This yielded a Fe / FeSi bonded mixed magnetic powder. This powder was then pressed and annealed to produce an Fe / FeSi composite powder core.

[0085] Examples 2-6 The composite powder cores of Examples 2-6 are substantially the same as those of Example 1, except that the adhesive components have different proportions, as shown in Table 1.

[0086] Example 7 Atomized FeSiAl powder and reduced FeNi powder were used as raw materials. The FeSiAl powder had a particle size of 50 μm, and the FeNi powder had a particle size of 30 μm. The FeSiAl powder was first annealed in a tube furnace at 650°C for 1 hour. Then, 500 g of FeNi powder was passivated with 150 ml of 8 wt.% acetone-based phosphoric acid solution. After mechanical stirring for 45 minutes, the powder was oven-dried at 60°C. The FeSiAl powder was coated with SiO2 using a sol-gel method using tetraethyl orthosilicate as the silicon source. A total of 1 kg of FeSiAl powder was prepared. The phosphated FeNi powder and the SiO2-coated FeSiAl powder were placed in a mixer (1) with the blades rotating at 220 rpm for 0.5 hours to disperse any agglomerated magnetic powder during the insulation treatment. During this process, 9 g of adhesive and 450 ml of a multi-component organic solvent were placed in a storage tank, heated to 95°C, and mechanically stirred until the adhesive was completely dissolved. The adhesive components and their proportions were as follows: polyethylene wax 5 wt.%, ethylene bisstearamide 10 wt.%, paraffin wax 15 wt.%, microcrystalline wax 5 wt.%, polyamide wax 5 wt.%, stearic acid 5 wt.%, lauric acid 5 wt.%, polyvinyl alcohol 5 wt.%, sodium silicate 15 wt.%, silicone resin 20 wt.%, epoxy resin 5 wt.%, and acrylic resin 5 wt.%. The organic solvent ratio was n-heptane: ethanol: toluene: acetonitrile = 4:3:1:2. The adhesive solution was added to mixer 1 in four portions using a peristaltic pump and high-pressure gas, with 20-minute intervals between each addition to ensure complete evaporation of the organic solvent. This yielded a FeSiAl / FeNi bonded mixed magnetic powder. This powder was subsequently pressed and annealed to produce a FeSiAl / FeNi composite powder core.

[0087] Example 8 Atomized FeSiCr powder and reduced carbonyl Fe powder (CIP) were used as raw materials. The FeSiCr powder had a particle size of 35 μm, and the carbonyl Fe powder had a particle size of 3 μm. The FeSiCr powder was first annealed in a tube furnace at 630°C for 70 min. Then, 200 g of the carbonyl Fe powder was passivated with 60 ml of a 10 wt.% phosphoric acid solution containing acetone as the main component. After mechanical stirring for 35 minutes, the mixture was oven-dried at 60°C. The FeSiCr powder was coated with ZrO2 by ball milling, yielding 1 kg of FeSiCr powder. The phosphated carbonyl Fe powder and the ZrO2-coated FeSiCr powder were placed in a mixer (1) with the blade speed set at 220 r / min. Mixing was performed for 0.5 h to disperse any agglomerated magnetic particles during the insulation treatment. During this process, 8 g of adhesive and 360 ml of a multi-component organic solvent were placed in a storage tank, heated to 90°C, and mechanically stirred until the adhesive was completely dissolved. The adhesive components and their proportions were as follows: polyethylene wax 10 wt.%, ethylene bisstearamide 25 wt.%, microcrystalline wax 5 wt.%, polyamide wax 10 wt.%, stearic acid 5 wt.%, sodium silicate 15 wt.%, silicone resin 10 wt.%, epoxy resin 5 wt.%, phenolic resin 10 wt.%, and acrylic resin 5 wt.%. The organic solvent ratio was n-heptane:acetone:toluene = 6:3:1. The adhesive solution was added to mixer 1 in five portions using a peristaltic pump and high-pressure gas, with 25-minute intervals between each addition to ensure complete evaporation of the organic solvent. This yielded a Fe / FeSi bonded mixed magnetic powder. This powder was subsequently pressed and annealed to produce a FeSiCr / CIP composite powder core.

[0088] Example 9 Atomized FeSi powder and FeSiAl powder were used as raw materials. The FeSi powder had a median particle size of 42 μm, and the FeSiAl powder had a median particle size of 15 μm. The FeSi and FeSiAl powders were first annealed in a tube furnace at 520°C for 60 min for the FeSi powder and 580°C for 45 min for the FeSiAl powder. 800 g of FeSi powder was then passivated with 250 ml of a 6 wt.% phosphoric acid solution consisting primarily of acetone. After mechanical stirring for 45 minutes, the powder was dried in a 75°C oven. The FeSiAl powder was coated with MgO by ball milling, producing 200 g of FeSiCr powder. The phosphated FeSi powder and the MgO-coated FeSiAl powder were placed in a mixer (1) with the blades rotating at 170 rpm for 45 minutes to disperse any agglomerated magnetic powder during the insulation treatment. During this process, 6 g of adhesive and 300 ml of a multi-component organic solvent were placed in a storage tank, heated to 85°C, and mechanically stirred until the adhesive was completely dissolved. The adhesive components and their proportions were as follows: polyethylene wax 15 wt.%, ethylene bisstearamide 30 wt.%, paraffin wax 5 wt.%, stearic acid 5 wt.%, polyvinyl alcohol 10 wt.%, microcrystalline wax 5%, sodium silicate 15 wt.%, silicone resin 5 wt.%, and acrylic resin 10 wt.%. The organic solvent ratio was 4:4:1:1 for n-heptane: chloroform: N,N-dimethylacetamide: xylene. The adhesive solution was added to mixer 1 in five portions using a peristaltic pump and high-pressure gas, with 20-minute intervals between each addition to ensure complete evaporation of the organic solvent. This yielded a FeSi / FeSiAl bonded mixed magnetic powder. This powder was then pressed and annealed to produce a FeSi / FeSiAl composite powder core.

[0089] Example 10 Atomized FeSiCr and FeCo powders were used as raw materials. The FeSiCr powder had a particle size of 48 μm, and the FeCo powder had a particle size of 22 μm. The FeSiCr powder was first annealed in a tube furnace at 650°C for 90 min. Then, 500 g of the FeCo powder was passivated with 110 ml of an 11 wt.% phosphoric acid solution composed primarily of acetone. After mechanical stirring for 50 min, the mixture was oven-dried at 70°C. The FeSiCr powder was coated with Fe₃O₄ by ball milling, yielding 1.2 kg of FeSiCr powder. The phosphated FeCo powder and the Fe₃O₄-coated FeSiCr powder were placed in a mixer (1) with the blades rotating at 180 rpm for 45 minutes to disperse any agglomerated magnetic powder during the insulation treatment. During this process, 10 g of adhesive and 510 ml of a multi-component organic solvent were placed in a storage tank, heated to 95°C, and mechanically stirred until the adhesive was completely dissolved. The adhesive components and their proportions were as follows: 10 wt.% ethylene bisstearamide, 10 wt.% microcrystalline wax, 5 wt.% polyethylene wax, 5 wt.% paraffin wax, 10 wt.% polyamide wax, 5 wt.% stearic acid, 4 wt.% lauric acid, 1 wt.% isooctanoic acid, 20 wt.% sodium silicate, 15 wt.% silicone resin, 10 wt.% epoxy resin, and 5 wt.% phenolic resin. The organic solvent ratio was n-heptane:acetone:acetonitrile = 4:4:2. The adhesive solution was added to mixer 1 in five portions using a peristaltic pump and high-pressure gas, with 25-minute intervals between each portion to ensure complete evaporation of the organic solvent. This resulted in the FeSiCr / FeCo bonded mixed magnetic powder. The powder can be subsequently pressed, annealed and other steps to obtain a FeSiCr / FeCo composite powder core.

[0090] Comparative Example 1 Water-atomized Fe powder and gas-atomized FeSi powder (containing 5.5% silicon) were used as raw materials. The Fe powder had a particle size of 140 μm, and the FeSi powder had a particle size of 35 μm. The Fe and FeSi powders were first annealed in a tube furnace at 550°C for 45 minutes for the Fe powder and 600°C for 1 hour for the FeSi. Then, 1 kg of Fe powder was passivated with 300 ml of a 5 wt.% phosphoric acid solution consisting primarily of ethanol. After mechanical stirring for 30 minutes, the solution was oven-dried at 60°C. The FeSi powder was coated with TiO2 via a sol-gel method through the hydrolysis and condensation of tetrabutyl titanate. A total of 300 g of FeSi powder was prepared.

[0091] The Fe phosphide powder and TiO2-coated FeSi powder were placed in mixer 1, with the blade speed set at 250 r / min. Mixing was continued for 0.5 h to disperse any agglomerated magnetic powder during the insulation treatment. During this process, 6.5 g of ethylene bisstearamide and 390 ml of a multi-component organic solvent were placed in a storage tank, heated to 90°C, and mechanically stirred until the ethylene bisstearamide was completely dissolved. The organic solvent ratio was 5:3:1:1 for n-heptane:trichloromethane:acetonitrile:toluene. The ethylene bisstearamide acetone solution was added to mixer 1 using a peristaltic pump and high-pressure gas in three separate additions, with 15-minute intervals between each addition to ensure complete evaporation of the organic solvent. This yielded a bonded Fe / FeSi mixed magnetic powder. This powder was subsequently pressed and annealed to produce an Fe / FeSi composite powder core.

[0092] Except for the adhesive components, the other process parameters of Comparative Examples 2-5 are completely consistent with those of Example 1 and Comparative Example 1. The adhesive components and the proportions of each component of Example 1 and Comparative Examples 1-5 are shown in Table 1.

[0093] Table 1 Adhesive components and ratios of Examples 1-6 and Comparative Examples 1-5

[0094] Magnetic powder pressing performance test The adhesive-coated magnetic powder was compacted at 1200 MPa to 1800 MPa using a ring die with an outer diameter of 25 mm and an inner diameter of 15 mm, without holding pressure. The resulting green compact exhibited a complete appearance, free of delamination, edge loss, or corner chipping. The composite powder cores were tested as follows, with the results shown in Table 1.

[0095] (1) Density test The density test uses the Archimedes drainage method. First, weigh the mass of the composite powder core in air as m1, the mass of the composite powder core in air after saturation with water as m2, and the mass of the composite powder core in water after saturation with water as m3. The density of the composite powder core is calculated as follows:

[0096] Where ρ w ——Density of water, g / cm 3 ; m1——mass of composite powder core in air, g; m2——the mass of the composite powder core in the air after saturation with water, g; m3——The mass of the composite powder core in water after saturation with water, g.

[0097] (2) Magnetic permeability test The magnetic permeability test was performed using Hunan Lianzhong's magnetic material automatic testing system, which consists of the MATS-2010SD soft magnetic DC measuring device and the MATS-2010SA soft magnetic AC measuring device.

[0098] (3) Bending strength test The flexural strength test adopts the three-point flexural test method, referring to the national standard "GB / T232-2010 Metal Material Bending Test Method". The flexural strength calculation formula is as follows: R=(3FL) / (2BH 2 ) Where R is the flexural strength, MPa; F——failure load, N; L——span, mm; B——width, mm; H——thickness, mm.

[0099] Table 2 Performance test results of Examples 1-10 and Comparative Examples 1-5

[0100] Result Analysis The adhesive of the present application has strong applicability. Examples 1 and 7-10 are some examples of the application of the adhesive of the present application in different magnetic powder systems, corresponding to the prepared Fe / FeSi composite powder core, FeSiAl / FeNi composite powder core, FeSiCr / Fe composite powder core, FeSi / FeSiAl composite powder core and FeSiCr / FeCo composite powder core, respectively.

[0101] Examples 1-6 illustrate the application of the adhesive of the present application within the same magnetic powder system. Comparative Examples 1-5, except for the adhesive, share the same parameters as Examples 1-6. The test results in Table 2 show that the density, magnetic permeability, and flexural strength of Examples 1-6 are superior to those of Comparative Examples 1-5. Taking Comparative Example 1 as an example, its adhesive is a single component without a strength-enhancing component, a thixotropic component, or a bonding component. Its density and flexural strength are lower than those of Examples 1-6, resulting in lower magnetic permeability.

[0102] Compared with Comparative Example 1, Comparative Example 2 adds strength-enhancing components and bonding components, and the flexural strength increases from 54 MPa to 72 MPa. However, due to the lack of thixotropic components, the lubricating effect of stearic acid cannot be enhanced, resulting in a lower density of the composite powder core of Comparative Example 2. The adhesive of Comparative Example 3 does not contain a lubricating component, so that the density and magnetic permeability of the composite powder core of Comparative Example 3 are the lowest. The amount of sodium silicate added to the adhesive of Comparative Example 4, a strength-enhancing component, reaches 50 wt.%. Although its flexural strength is higher than that of the other comparative examples, it is still lower than that of Examples 1-6. The adhesive of Comparative Example 5 contains a lubricating component, a thixotropic component, a bonding component, and a strength-enhancing component, but the proportion of each component is relatively small, so that its magnetic properties and mechanical properties are lower than those of Examples 1-6.

[0103] In addition, the addition amount of silicone resin and ethylene bisstearamide is explored as follows: Experiment 1: Evidence of the silicone resin addition range (5 wt.% to 25 wt.%) Aerosolized FeSi5.5 powder (5.5% silicon content) was used as the raw material, with a particle size of 35 μm and a 5 wt.% adhesive. The adhesive components consisted of phenolic resin (10 wt.%), ethylene bisstearamide (15 wt.%), microcrystalline wax (10 wt.%), polyamide wax (5 wt.%), stearic acid (10 wt.%), polyvinyl alcohol (10 wt.%), sodium silicate (5 wt.%), and silicone resin and polyethylene wax (35 wt.%). Polyethylene wax had no strength-enhancing effect and was added as a balancing agent. The specific experimental design and the corresponding flexural strength of the FeSi magnetic powder are shown in Table 3.

[0104] Table 3 Changes in flexural strength of FeSi magnetic powder with silicone resin content

[0105] Experiment 2: Evidence of the addition amount of ethylene bisstearamide (10 wt%-30 wt.%) Water-atomized Fe powder with a particle size of 150 μm was used as the raw material. An adhesive was added at an amount of 8 wt%. The adhesive components consisted of 25 wt% polyethylene wax, 5 wt% microcrystalline wax, 10 wt% polyamide wax, 5 wt% stearic acid, 10 wt% silicone resin, 5 wt% acrylic resin, and 40 wt% ethylene bisstearamide (EBS wax) and sodium silicate. Sodium silicate has no lubricating effect and can be added as a balancing medium. The specific experimental design and the corresponding Fe powder density and magnetic permeability are shown in Table 4.

[0106] Table 4 Changes in Fe magnetic powder density and magnetic permeability with the addition of ethylene bisstearamide

[0107] Performance results analysis As shown in Table 3, the flexural strength of FeSi magnetic powder increases with increasing silicone resin content in the adhesive. At low silicone resin content, the increased silicone resin content significantly improves the flexural strength of the magnetic powder. Increasing the silicone resin content from 5 wt.% to 10 wt.% increases the flexural strength by 22 MPa, from 25 MPa to 47 MPa, nearly doubling it. However, when the silicone resin content exceeds 25 wt.%, further increases in content lead to a decrease in flexural strength, indicating excessive silicone resin addition. Increasing the silicone resin content from 25 wt.% to 30 wt.% results in a decrease in flexural strength to 86 MPa. Therefore, the optimal silicone resin content in the adhesive is between 5 wt.% and 25 wt.%.

[0108] Referring to Table 4, as the EBS wax content increases from 0 wt.% to 40 wt.%, the density of Fe magnetic powder first increases gradually and then stabilizes, and the magnetic permeability first increases and then decreases. When the EBS wax addition amount is low, the density increases more with the increase of its content, and the magnetic permeability increases with the increase of density. When the EBS wax content increases from 0 to 10 wt.%, the density increases from 7.15 g / cm 3 Increased to 7.19 g / cm 3 , increased by 0.04 g / cm 3 , the magnetic permeability increased from 201.2 to 232.3, a 15% improvement. When the EBS wax content exceeds 30 wt.%, the magnetic powder density remains unchanged. The decrease in magnetic permeability may be due to residual non-magnetic material. Therefore, the optimal EBS wax addition level in adhesives is 10 wt.% to 30 wt.%.

[0109] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "example," "specific example," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0110] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. An adhesive, characterized in that: Calculated by mass percentage, including: 10% to 40% bonding components, 20% to 40% strength enhancing components, 20% to 40% lubricating components and 5% to 15% thixotropic components.

2. The adhesive according to claim 1, characterized in that The bonding component comprises at least one of paraffin wax, polyamide wax, polyvinyl alcohol, epoxy resin, phenolic resin and acrylic resin; and / or, The strength enhancing component comprises sodium silicate and / or silicone resin; and / or, The lubricating component includes at least one of stearic acid, ethylene bisstearamide, lauric acid and isooctanoic acid; and / or, The thixotropic component includes polyethylene wax and / or microcrystalline wax.

3. The adhesive according to claim 2, characterized in that When the bonding component includes paraffin wax, the content of the paraffin wax in the adhesive is 5% to 15% by mass; When the bonding component includes polyamide wax, the content of the polyamide wax in the adhesive is 5% to 10% by mass; When the bonding component includes polyvinyl alcohol, the content of the polyvinyl alcohol in the adhesive is 0% to 15% by mass; When the bonding component includes epoxy resin, the content of the epoxy resin in the adhesive is 0% to 10% by mass; When the bonding component includes phenolic resin, the content of the phenolic resin in the adhesive is 0% to 10% by mass; When the bonding component includes acrylic resin, the content of the acrylic resin in the adhesive is 0% to 10% by mass.

4. The adhesive according to claim 2, characterized in that When the strength enhancing component includes sodium silicate, the content of the sodium silicate in the adhesive is 15% to 35% by mass; When the strength enhancing component includes an organic silicone resin, the content of the organic silicone resin in the adhesive is 5% to 25% by mass.

5. The adhesive according to claim 2, characterized in that When the lubricating component includes stearic acid, the content of the stearic acid in the adhesive is 5% to 10% by mass; When the lubricating component includes ethylene bisstearamide, the content of the ethylene bisstearamide in the adhesive is 10% to 30% by mass; When the lubricating component includes lauric acid, the content of the lauric acid in the adhesive is 0% to 5% by mass; When the lubricating component includes isooctanoic acid, the content of isooctanoic acid in the adhesive is 0% to 1% by mass.

6. The adhesive according to claim 2, characterized in that When the thixotropic component includes polyethylene wax, the content of the polyethylene wax in the adhesive is 5% to 15% by mass; When the thixotropic component includes microcrystalline wax, the content of the microcrystalline wax in the adhesive is 5% to 15% by mass.

7. A soft magnetic composite material, characterized in that include: Magnetic powder and adhesive, wherein the adhesive is the adhesive according to any one of claims 1-6.

8. The soft magnetic composite material according to claim 7, characterized in that The magnetic powder includes pure iron powder or soft magnetic alloy powder, wherein the soft magnetic alloy powder includes at least one of FeSi powder, FeSiAl powder, FeSiCr powder, FeCo powder, FeNi powder, FeNiMo powder and FeSiB amorphous nanocrystalline powder.

9. The soft magnetic composite material according to claim 7, characterized in that Calculated by mass percentage, the added amount of the adhesive is 0.1 wt.% to 3 wt.%.

10. The soft magnetic composite material according to any one of claims 7 to 9, characterized in that: Also includes: An insulating layer is coated on the surface of the magnetic powder particles, and the insulating layer includes at least one of phosphate, aluminum oxide, silicon dioxide, zirconium dioxide, magnesium oxide, ferroferric oxide, MnZn ferrite and NiZn ferrite.

11. A method for preparing the soft magnetic composite material according to any one of claims 7 to 10, characterized in that: The steps include: Pretreatment of magnetic powder; Coating adhesive treatment, wherein the coating adhesive treatment comprises: The adhesive is dissolved in a solvent to form an adhesive solution, and the adhesive solution is mixed with the pretreated magnetic powder to obtain a soft magnetic composite material.

12. The preparation method according to claim 11, characterized in that The concentration of the adhesive solution is 0.005 g / ml to 0.05 g / ml, and the mass ratio of the volume of the adhesive solution to the magnetic powder is 150 mL / kg to 400 mL / kg.

13. The preparation method according to claim 11, characterized in that The adhesive solution is mixed with the magnetic powder at intervals of N times, wherein the interval time is 10 minutes to 25 minutes, and N is a positive integer greater than or equal to 3.

14. The preparation method according to claim 11, characterized in that Calculated by mass percentage, the solvent includes 35% to 65% of n-heptane, 25% to 45% of any one of chloroform, acetone and ethanol, 0% to 20% of any one of chlorobenzene, N,N-dimethylacetamide and acetonitrile, and 0% to 10% of toluene or xylene.

15. The preparation method according to claim 14, characterized in that The temperature at which the adhesive and the solvent are mixed is 80° C. to 120° C.

16. The preparation method according to claim 11, characterized in that The pretreatment of the magnetic powder includes: Annealing and insulation treatment, The annealing treatment includes: annealing the magnetic powder at 500° C. to 700° C.; The insulation treatment includes: coating an insulation layer on the surface of the annealed magnetic powder.

17. A device for preparing the soft magnetic composite material according to any one of claims 7 to 10, characterized in that: include: mixers and pumps, placing the pretreated magnetic powder in the mixer for dispersion; The pump adds the adhesive solution into the mixer under the action of the protective gas for mixing.

18. The preparation equipment according to claim 17, characterized in that The pressure of the protective gas is 0.1 MPa to 0.5 MPa.

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