Iron-silicon alloy composition, iron-silicon magnetic powder core, and preparation method and application thereof

Abstract

The present invention relates to an iron silicon alloy composition, which contains, by mass percentage, 6.0wt% to 7.0wt% Si, 0.3wt% to 1.0wt% Co, 0.5wt% to 2.0wt% Ti, 0.4wt% to 1.0wt% V and the balance Fe. It also relates to an iron silicon magnetic powder core and a preparation method thereof, the iron silicon magnetic powder core comprising an inner core magnetic powder core and an outer coating layer, the inner core magnetic powder containing the above-mentioned iron silicon alloy composition, and the outer coating layer may sequentially include a passivation layer, an insulating layer, a molded layer and a strengthening layer. The iron silicon magnetic powder core has excellent DC superposition characteristics and low power loss. At 100Oe, the DC superposition is ≥0.82; the power loss Pcv (50kHz, 100mT) is ≤550mW / cm 3 , can be used in electric vehicle DC charging pile inverters, solar photovoltaic inverter PFC inductors, high-power active filters and hybrid reactors.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy, and in particular to an iron-silicon alloy composition, an iron-silicon magnetic powder core, and a preparation method and application thereof, and in particular to an iron-silicon magnetic powder core with low loss and good DC characteristics and a preparation method thereof. The soft magnetic material can be applied to an electric vehicle DC charging pile inverter, a PFC inductor in a solar photovoltaic inverter, a high-power active filter (APF) and a hybrid reactor. Background Art

[0002] At present, the main power generation method in my country is thermal power generation, accounting for about 70% of the total. Thermal power generation consumes a lot of non-renewable resources such as coal and oil. In order to reduce resource consumption, reduce carbon emissions, and achieve comprehensive, coordinated and sustainable development of economy, society and ecology, it is necessary to vigorously develop new energy power generation, such as solar photovoltaic, hydropower and wind power generation. Among them, suitable magnetic materials are the key factor in realizing the efficient conversion of mechanical energy into electrical energy. Traditional magnetic materials have low resistance (10 -6 ~10 -9 Ω / cm 2 ), its eddy current loss increases dramatically with the increase of frequency, so it cannot be used at high frequency (0.2~2MHz).

[0003] The magnetic powder core is made of iron-silicon soft magnetic alloy, which has excellent DC superposition and high-frequency low-loss characteristics. It especially meets the technical requirements of low voltage, high power density and high frequency. It can partially replace pure iron powder core, iron-nickel powder core and iron-silicon-aluminum powder core and has great commercial application prospects in electronic components and energy industries.

[0004] Patent document CN104240890A discloses a Fe-6.5% Si magnetic powder core, which contains 3% to 7% Co by weight. The high addition amount of Co leads to a high cost.

[0005] Patent document CN102294476A discloses a method for preparing an iron silicon material and a μ60 iron silicon magnetic powder core, the composition of which is a binary iron silicon alloy with trace amounts of Nb and V elements added, the Si content is 6.4wt% to 7.0wt%, and the remainder is Fe. Although the magnetic powder core has low power loss, it fails to solve the DC superposition problem.

[0006] Patent document CN103824670A discloses a method for preparing an iron silicon magnetic powder core, which uses permanganate for purification. Due to its strong oxidizing property, it has high requirements for mixing equipment during production and poses a great safety hazard. In addition, when the melting temperature is 1500°C, the probability of leakage and blockage will increase significantly, which is not conducive to normal production.

[0007] Based on this, it is necessary to develop an iron silicon magnetic powder core with high frequency, low loss, good DC superposition characteristics, low cost and large-scale production. Summary of the invention

[0008] The object of the present invention includes providing an iron-silicon alloy composition having excellent DC superposition characteristics and high frequency and low loss.

[0009] A first aspect of the present invention provides an iron-silicon alloy composition, which contains the following components, in mass percentage: 6.0wt% to 7.0wt% Si, 0.3wt% to 1.0wt% Co, 0.5wt% to 2.0wt% Ti, 0.4wt% to 1.0wt% V, and the balance Fe.

[0010] In some embodiments of the present invention, in the iron-silicon alloy composition, the content of Fe is 89 wt % to 92.8 wt %.

[0011] The second aspect of the present invention provides an iron silicon magnetic powder core, comprising a core portion and an outer cladding layer, wherein the core portion is filled with inner core magnetic powder, and the inner core magnetic powder comprises the iron silicon alloy composition provided by the first aspect of the present invention.

[0012] In some embodiments of the present invention, in the iron silicon magnetic powder core, from the core to the outside, the outer coating layer includes the following structural layers in sequence: a passivation layer, an insulating layer, a molded layer and a strengthening layer.

[0013] In some embodiments of the present invention, in the iron silicon magnetic powder core,:

[0014] The main component of the passivation layer is ferrous phosphate;

[0015] The main component of the insulating layer is silicone resin;

[0016] The main component of the molded layer is zinc stearate;

[0017] The main component of the strengthening layer is epoxy resin.

[0018] In some embodiments of the present invention, in the iron silicon magnetic powder core:

[0019] The content of the silicone resin is 0.1% to 1.0% of the mass of the inner core magnetic powder;

[0020] The content of zinc stearate is 0.1% to 0.5% of the total mass of the inner core magnetic powder and the passivation layer;

[0021] The content of the epoxy resin is 2% to 10% of the total mass of the inner core magnetic powder, the passivation layer and the molded layer.

[0022] The third aspect of the present invention provides a method for preparing an iron silicon magnetic powder core, comprising the steps of alloy smelting, crushing and powdering, particle size proportioning, powder reduction, oil quenching, powder passivation, insulation coating, compression molding, heat treatment and strengthening treatment;

[0023] Alloy smelting: under inert gas protection conditions, add Fe powder and Si powder, heat to melt Fe powder and Si powder, then add Co powder, Ti powder and V powder, and smelt at 1650℃~1770℃; wherein, according to the total mass parts of Si powder, Fe powder, Co powder, Ti powder and V powder is 100 parts, Si powder is 6~7 parts, Co powder is 0.3~1 parts, Ti powder is 0.5~2 parts, V powder is 0.4~1 parts, and the balance is Fe powder;

[0024] Crushing and powdering: After the alloy is smelted, it is directly subjected to aerosol powdering to obtain iron-silicon alloy powder I;

[0025] Particle size ratio: the iron-silicon alloy powder I is sieved to obtain an iron-silicon alloy powder II with a particle size of -300 mesh, an iron-silicon alloy powder III with a particle size of -200 mesh to +300 mesh, and an iron-silicon alloy powder IV with a particle size of -100 mesh to +200 mesh; the iron-silicon alloy powder II, the iron-silicon alloy powder III and the iron-silicon alloy powder IV are mixed in a mass ratio of (1-2):(2-3):1 to obtain an iron-silicon alloy powder V;

[0026] Powder reduction: after evacuation, hydrogen is introduced, the temperature of the iron-silicon alloy powder V is raised to 700-900° C. at 15-20° C. / min, and the temperature is kept for 60-120 min to obtain the iron-silicon alloy powder VI;

[0027] Oil quenching treatment: under inert gas protection conditions, heating the iron-silicon alloy powder VI to 600-800° C. at 20-40° C. / min, keeping the temperature for 60-120 min, and oil quenching to obtain iron-silicon alloy powder VII;

[0028] Powder passivation: adding a phosphate acetone solution having a phosphoric acid concentration of 10% to 15%, mixing, and drying at 100 to 150° C. to obtain an iron-silicon alloy powder VIII; wherein the amount of the phosphate acetone solution added is 10% to 20% of the mass of the iron-silicon alloy powder VII;

[0029] Insulation coating: adding silicone resin, mixing, adding acetone, mixing, and drying at 50-60° C. to obtain iron-silicon alloy powder IX; wherein the amount of the silicone resin added is 0.1%-1.0% of the iron-silicon alloy powder VIII, and the amount of the acetone added is 10%-20% of the iron-silicon alloy powder VIII;

[0030] Compression molding: adding zinc stearate, mixing, and pressing at 1600-2100 MPa to prepare iron silicon magnetic powder core blank I; wherein the amount of zinc stearate added is 0.1%-0.5% of the mass of the iron silicon alloy powder IX;

[0031] Heat treatment: under inert gas protection conditions, the iron silicon magnetic powder core blank material I is kept at 600-800° C. for 60-120 min to obtain the iron silicon magnetic powder core blank material II;

[0032] Strengthening treatment: providing a strengthening solution, which is a 2wt% to 10wt% one-component epoxy resin acetone solution; soaking the iron silicon magnetic powder core blank II in the strengthening solution for 20 to 60 minutes, washing with alcohol, and drying at 200 to 220° C. for 20 to 40 minutes to obtain the iron silicon magnetic powder core.

[0033] In some embodiments of the present invention, in the method for preparing the iron silicon magnetic powder core, in the alloy smelting step, the mass fraction of the Fe powder is 89 to 92.8 parts.

[0034] Application of the iron-silicon alloy composition provided in the first aspect of the present invention, or the iron-silicon magnetic powder core provided in the second aspect of the present invention, or the iron-silicon magnetic powder core prepared by the preparation method provided in the third aspect of the present invention in the preparation of electromagnetic devices.

[0035] In some embodiments of the present invention, in the application: the electromagnetic device is an inverter for a DC charging pile of an electric vehicle, a PFC inductor in a solar photovoltaic inverter, an active filter or a hybrid reactor.

[0036] The iron-silicon alloy composition of the present invention can significantly improve the comprehensive magnetic properties and corrosion resistance of the magnetic powder core by adding only a very small amount of Co, Ti and V.

[0037] The method for preparing the iron silicon magnetic powder core of the present invention can prepare uniform smooth spherical powder with few internal pores, fine grains and no impurity phase, and can provide better direct current superposition characteristics and low power loss.

[0038] In the existing preparation method, water quenching is usually adopted. The present invention adopts oil quenching treatment, which can further reduce the oxygen content and improve the DC superposition characteristics of the magnetic powder core.

[0039] In the existing preparation method, permanganate is usually used for passivation, which has strong oxidizing property, has high requirements on mixing equipment and has great safety hazards. In the present invention, acetone phosphate solution is used for passivation, which has good operability and high safety.

[0040] The magnetic powder core of the present invention has a lower melting temperature and is not easy to block the flow guide tube, which is conducive to normal production.

[0041] The iron silicon magnetic powder core of the present invention has excellent physical and magnetic properties, and its effective magnetic permeability can reach 60, and at 100Oe, the DC superposition is ≥0.82, and the power loss Pcv (50kHz, 100mT) is ≤550mW / cm 3 , which greatly meets the development requirements of low voltage, high power density and high frequency in the electronics industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. It should also be noted that the drawings are all drawn in a simplified form and are only used to conveniently and clearly assist in explaining the present invention. The various sizes of each component shown in the drawings are arbitrarily shown and may be accurate or may not be drawn according to the actual scale. For example, in order to make the illustration clearer, the size of the components is appropriately exaggerated in some places in the drawings. Unless otherwise specified, the components in the figure are not drawn to scale. The present invention does not limit each size of each component.

[0043] In the following description, the same reference numerals denote the same parts.

[0044] Figure 1 It is a schematic diagram of the structure of an iron silicon magnetic powder core prepared in one embodiment of the present invention;

[0045] Explanation of reference numerals: 100 - core; 200 - outer cladding layer; 210 - passivation layer; 220 - insulation layer; 230 - molding layer; 240 - strengthening layer. DETAILED DESCRIPTION

[0046] The present invention will be further described below in conjunction with the accompanying drawings, embodiments and examples. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the protection scope of the appended claims of the application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0048] the term

[0049] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0050] The terms "and / or", "or / and", and "and / or" used in this article include any one of two or more related listed items, and also include any and all combinations of related listed items, and the arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions that are all connected by "logical and", and undoubtedly includes technical solutions that are all connected by "logical or". For example, "A and / or B" includes three parallel solutions of A, B and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, the technical solution that is all connected by "logical OR"), and also includes any and all combinations of A, B, C, and D, that is, the combination of any two or any three of A, B, C, and D, and also includes the combination of four of A, B, C, and D (that is, the technical solution that is all connected by "logical AND").

[0051] In the present invention, “preferred”, “better”, “better”, etc. are only used to describe implementation methods or examples with better effects. It should be understood that they do not constitute limitations on the scope of protection of the present invention.

[0052] In the present invention, “further”, “furthermore”, “particularly”, etc. are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present invention.

[0053] In the present invention, in the "first aspect", "second aspect", "third aspect", "fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0054] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0055] In the present invention, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the optional numerical distribution is considered continuous within the above numerical interval, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical range, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to integers within the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges included therein.

[0056] The temperature parameters in the present invention, if not specifically limited, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the precision range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0057] In the present invention, unless otherwise specified, the size, particle size, and diameter generally refer to the average value.

[0058] In the present invention, unless otherwise specified, the term "molecular weight" refers to an average molecular weight, and further refers to a number average molecular weight.

[0059] In the present invention, the plus or minus sign before the mesh number indicates whether the particles can pass through the mesh of the mesh number. A negative number indicates that the particles can pass through the mesh of the mesh number, i.e., the particle size is smaller than the mesh size. A positive number indicates that the particles cannot pass through the mesh of the mesh number, i.e., the particle size is larger than the mesh size. For example, if the particles are -100 mesh to +200 mesh, it means that the particles can pass through the mesh of 100 mesh but cannot pass through the mesh of 200 mesh. When screening the particles of this mesh number, the particles with a large mesh number (200) should be placed under the sieve with a small mesh number (100). The particles left in the sieve with a large mesh number (200) are particles with a mesh number of -100 to +200 mesh.

[0060] In this article, when referring to the unit of a data range, if there is a unit only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 20~40min means that the units of the left endpoint "20" and the right endpoint "40" are both min.

[0061] At present, metal magnetic powder cores mainly include iron powder cores, iron-nickel magnetic powder cores, iron silicon magnetic powder cores, sendust magnetic powder cores and iron-nickel-molybdenum magnetic powder cores. Among them, iron powder cores have the lowest price, but poor comprehensive magnetic properties; iron-nickel powder cores and iron-nickel-molybdenum powder cores have good comprehensive magnetic properties, but the nickel element is expensive, resulting in high preparation costs; sendust magnetic powder cores have low losses and good frequency characteristics, but poor DC superposition characteristics. The iron silicon magnetic powder core has excellent comprehensive magnetic properties, moderate prices, and a wider range of application prospects, but the high-frequency loss is high and still needs further improvement.

[0062] The first aspect of the present invention provides an iron-silicon alloy composition, which only adds a very small amount of Co, Ti and V elements, has a low cost, and the iron-silicon magnetic powder core prepared by using the composition has a stable magnetic permeability (effective magnetic permeability can reach 60) and a low high-frequency loss (Pcv (50kHz, 100mT) ≤ 550mW / cm 3 ), DC superposition characteristics (at 100Oe, DC superposition ≥ 0.82), and excellent comprehensive magnetic properties.

[0063] In some embodiments of the present invention, an iron-silicon alloy composition is provided, which contains the following components by mass percentage: 6.0wt% to 7.0wt% Si, 0.3wt% to 1.0wt% Co, 0.5wt% to 2.0wt% Ti, 0.4wt% to 1.0wt% V, and the balance Fe. In the present invention, the total addition amount of Co, Ti and V does not exceed 4wt%, preferably does not exceed 3wt%, and further may not exceed 1.5wt%.

[0064] In some embodiments of the present invention, based on the total mass percentage of the iron-silicon alloy composition as 100wt%, the mass content of Fe is 89wt% to 92.8wt%, and can further be 90.6wt% to 91.4wt%, and further can be 90.6wt% to 90.7wt%, for example 90wt%, 90.2wt%, 90.6wt%, 90.7wt%, 90.9wt%, 91wt%, 91.2wt%, 91.4wt%, 91.6wt%, 91.8wt%, 92wt%, etc.

[0065] In some embodiments of the present invention, based on the total mass percentage of the iron-silicon alloy composition as 100wt%, the mass content of Si is 6.0wt% to 7.0wt%, and the balance is Fe. Further, the content of Si is 6.0wt% to 6.5wt%, for example 6.0wt%, 6.2wt%, 6.5wt%, 6.8wt%, 7.0wt%, etc.

[0066] Conventional technology usually requires the addition of a large amount of Co (such as 3% to 7%). If the Co content is lower than 3% (for example, 1%), the coercive force and loss will increase significantly, and the overall magnetic properties will decrease. Ti is related to the soft magnetic properties of the magnetic powder core. When the addition amount is higher than 2%, it can improve the properties. When it is lower than this value (for example, 1%), the improvement effect is not obvious. V has a great influence on the ordered phase decomposition of ferrosilicon alloy atoms. A suitable addition of V can weaken the ordered phase decomposition of the alloy, improve the plasticity of the alloy and enhance the magnetism. When the addition amount is lower (for example, 1%), the improvement effect is not obvious. After a lot of experimental exploration, the inventors of the present application unexpectedly discovered that the comprehensive performance can be significantly improved by adding only a very small amount of trace elements. The iron-silicon alloy composition provided by the present invention only needs to add a small amount of Co (preferably 0.3wt% to 1.0wt%), a small amount of Ti (preferably 0.5wt% to 1.0wt%), and a small amount of V (preferably 0.4wt% to 1.0wt%) to effectively improve the soft magnetic properties of the magnetic powder core, achieve high frequency and low loss and excellent DC superposition characteristics, so that the prepared iron-silicon magnetic powder core has excellent comprehensive magnetic properties. Moreover, the total addition amount of Co, Ti and V (preferably not more than 4wt%) is still far lower than the trace element addition amount required in the traditional technology.

[0067] In some embodiments of the present invention, based on the total mass percentage of the iron-silicon alloy composition as 100wt%, the mass content of Co is 0.3wt% to 1.0wt%, and can further be 0.8wt% to 1.0wt%, for example 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, and the like.

[0068] In some embodiments of the present invention, based on the total mass percentage of the iron-silicon alloy composition as 100wt%, the mass content of Ti is 0.5wt% to 2.0wt%, and can further be 0.5wt% to 1.0wt%, for example 0.5wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2.0wt%, and the like.

[0069] In some embodiments of the present invention, based on the total mass percentage of the iron-silicon alloy composition as 100wt%, the mass content of V is 0.4wt% to 1.0wt%, and can further be 0.4wt% to 0.8wt%, for example 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, etc.

[0070] In some preferred embodiments, the iron-silicon alloy composition contains the following components: 6.0 wt% to 6.5 wt% Si, 0.8 wt% to 1.0 wt% Co, 0.5 wt% to 1.0 wt% Ti, 0.4 wt% to 0.8 wt% V, and the balance Fe. Further, the content of Fe is selected from any suitable range mentioned above.

[0071] The second aspect of the present invention provides an iron silicon magnetic powder core, comprising a core 100 and an outer coating 200. The core is filled with inner core magnetic powder, the inner core magnetic powder contains the iron silicon alloy composition provided by the first aspect of the present invention, the iron silicon alloy composition has high density, low magnetostriction coefficient and magnetocrystalline anisotropy coefficient is almost zero, and can provide excellent DC superposition characteristics. The outer coating can wrap the filling of the core to achieve granulation, and can further improve the comprehensive magnetic properties and provide a certain corrosion resistance.

[0072] In some embodiments of the present invention, the outer coating layer 200 includes the following structural layers in order from the core 100 to the outside: a passivation layer 210, an insulating layer 220, a molded layer 230, and a strengthening layer 240. It should be understood that the "in order" here only indicates the order in position, and does not limit whether the relevant structural layers are directly in contact with each other. For example, between the molded layer and the insulating layer, it is also allowed to add other functional layers, such as a curing layer. For another example, in addition to the strengthening layer, other functional layers, such as a fixing layer, can be further coated to improve the bonding strength between the insulating layer and the molded layer.

[0073] Figure 1 The structure diagram of the iron silicon magnetic powder core in one embodiment of the present invention includes a core 100 and an outer coating layer 200. From the core 100 to the outside, the outer coating layer 200 includes a passivation layer 210, an insulation layer 220, a molded layer 230 and a strengthening layer 240 in sequence. At this time, the iron silicon magnetic powder core is composed of the core 100 and the outer coating layer 200, and the outer coating layer 200 is composed of the passivation layer 210, the insulation layer 220, the molded layer 230 and the strengthening layer 240.

[0074] In some embodiments of the present invention, the passivation layer of the iron silicon magnetic powder core can improve the chemical bonding strength with the insulating layer and provide a more uniform coating. In some embodiments, the main component of the passivation layer is ferrous phosphate.

[0075] In some embodiments, the thickness of the passivation layer is preferably not more than 20 nm, and may further be 10 to 20 nm, with example thicknesses of 2 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, and the like.

[0076] In some embodiments of the present invention, the insulating layer of the iron silicon magnetic powder core can improve frequency stability and reduce high-frequency loss. In some embodiments, the main component of the insulating layer is silicone resin, and further, it is a neutral low molecular weight silicone resin (such as a molecular weight of 6000 to 10000Da), and the molecular weights are 6000Da, 7000Da, 8000Da, 9000Da, 10000Da, etc. In some preferred embodiments, the silicone resin is in the form of fine powder. In some preferred embodiments, the viscosity of the silicone resin is 100 to 200cSt.

[0077] In some embodiments, the content of silicone resin is 0.1% to 1.0% of the mass of the inner core magnetic powder, and can further be 0.1% to 0.5%, for example 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc.

[0078] In some embodiments of the present invention, the molded layer of the iron silicon magnetic powder core can improve the soft magnetic properties such as the compaction density and magnetic permeability of the magnetic powder core. In some embodiments, the main component of the molded layer is zinc stearate. In some embodiments, the content of zinc stearate is 0.1% to 0.5% of the total mass of the inner core magnetic powder and the passivation layer, and can further be 0.1% to 0.3%, for example 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc.

[0079] In some embodiments of the present invention, the strengthening layer of the iron silicon magnetic powder core can prevent corrosion. In some embodiments, the main component of the strengthening layer is epoxy resin. In some embodiments, the content of epoxy resin is 2% to 10% of the total mass of the inner core magnetic powder, the passivation layer and the molded layer, and can further be 2% to 5%, for example 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0080] In this article, "main component", unless otherwise specified, refers to the components listed above, such as a mass content greater than 80%, greater than 85%, greater than 90%, greater than 95%, greater than 96%, greater than 97%, greater than 98%, greater than 99%, etc. In some embodiments, "main component" is allowed to refer to a mass content of 100%. It should be understood that it is allowed to contain other components, such as unavoidable impurities, composition changes caused by the preparation method, etc., and also for example, transition areas formed by contact and penetration of adjacent structural layers. In combination with the example of the preparation method provided in the third aspect of the present invention, those skilled in the art can clearly understand the distribution and connection methods of each structural layer, as well as the meaning of the "main component".

[0081] The third aspect of the present invention provides a method for preparing an iron silicon magnetic powder core, which can be used to prepare the iron silicon magnetic powder core described in the second aspect of the present invention.

[0082] In some embodiments, the method for preparing the iron silicon magnetic powder core includes alloy smelting, crushing and powdering, particle size ratio, powder reduction, oil quenching, powder passivation, insulation coating, compression molding, heat treatment and strengthening treatment steps. In the preparation of traditional iron silicon magnetic powder cores, after the powder reduction step, the powder is directly passivated, or water quenching is performed first and then passivation is performed. The present invention adopts the method of oil quenching treatment to reduce the oxygen content of the powder, prevent iron from being oxidized, and improve the DC superposition characteristics. In the preparation of traditional iron silicon magnetic powder cores, before the next step, annealing is not performed or annealing is performed in an inert gas. The present invention is reduced in hydrogen (the reduction process can also be called an annealing process), which can further reduce impurities such as oxygen and sulfur content and improve the plasticity and corrosion resistance of the powder.

[0083] In some embodiments, the alloy smelting step includes: adding Fe powder and Si powder under inert gas protection, heating to melt the Fe powder and Si powder, and then adding Co powder, Ti powder and V powder for smelting; wherein the addition amount of Si powder, Fe powder, Co powder, Ti powder and V powder can be selected and adjusted according to the formula of the iron-silicon alloy composition of the first aspect of the present invention;

[0084] Crushing and powdering: After the alloy is smelted, it is directly subjected to aerosol powdering to obtain iron-silicon alloy powder I;

[0085] Particle size ratio: sieve the iron-silicon alloy powder I to obtain iron-silicon alloy powder II with a particle size of -300 mesh, iron-silicon alloy powder III with a particle size of -200 mesh to +300 mesh, and iron-silicon alloy powder IV with a particle size of -100 mesh to +200 mesh; mix the iron-silicon alloy powder II, the iron-silicon alloy powder III, and the iron-silicon alloy powder IV to obtain iron-silicon alloy powder V;

[0086] Powder reduction: after evacuation, hydrogen is introduced, the temperature of the iron-silicon alloy powder V is raised to 700-900°C, and the temperature is kept to obtain the iron-silicon alloy powder VI;

[0087] Oil quenching treatment: under inert gas protection conditions, the iron-silicon alloy powder VI is heated to 600-800°C, kept warm, and oil quenched to obtain the iron-silicon alloy powder VII;

[0088] Powder passivation: adding a phosphoric acid acetone solution having a phosphoric acid concentration of 10% to 15%, mixing, and drying to obtain an iron silicon alloy powder VIII;

[0089] Insulation coating: adding silicone resin, mixing, adding acetone, mixing, and drying to obtain iron-silicon alloy powder IX;

[0090] Compression molding: adding zinc stearate, mixing, pressing, and preparing iron silicon magnetic powder core blank Ⅰ;

[0091] Heat treatment: under the protection of inert gas, the iron silicon magnetic powder core blank material I is kept at 600-800°C to obtain the iron silicon magnetic powder core blank material II;

[0092] Strengthening treatment: providing a strengthening solution, which is a 2% to 10% one-component epoxy resin acetone solution; soaking the iron silicon magnetic powder core blank II in the strengthening solution, washing with alcohol, and drying to obtain the iron silicon magnetic powder core.

[0093] In some embodiments, each step included in the method for preparing the iron silicon magnetic powder core may adopt any appropriate combination of the following steps and technical features.

[0094] In some embodiments, the alloy smelting step is: under inert gas protection conditions, adding Fe powder and Si powder, heating to melt the Fe powder and Si powder, then adding Co powder, Ti powder and V powder, and smelting at 1650°C to 1770°C; wherein, based on the total mass fraction of Si powder, Fe powder, Co powder, Ti powder and V powder being 100 parts, Si powder is 6 to 7 parts, Co powder is 0.3 to 1 part, Ti powder is 0.5 to 2 parts, V powder is 0.4 to 1 part, and the balance is Fe powder; and / or,

[0095] Crushing and powdering: After the alloy is smelted, aerosol powdering is directly carried out. After cooling, the atomized powder is sieved through a 100-mesh sieve to obtain -100-mesh iron-silicon alloy powder I; and / or,

[0096] Particle size ratio: sieving the iron-silicon alloy powder I to obtain iron-silicon alloy powder II with a particle size of -300 mesh, iron-silicon alloy powder III with a particle size of +300 mesh to -200 mesh, and iron-silicon alloy powder IV with a particle size of +200 mesh to -100 mesh; mixing the iron-silicon alloy powder II, the iron-silicon alloy powder III, and the iron-silicon alloy powder IV in a mass ratio of (1-2):(2-3):1 to obtain iron-silicon alloy powder V; and / or,

[0097] Powder reduction: after evacuation, hydrogen is introduced, the temperature of the iron-silicon alloy powder V is raised to 800-1000° C. at 15-20° C. / min, and the temperature is kept for 60-120 min to obtain the iron-silicon alloy powder VI; and / or,

[0098] Oil quenching treatment: under inert gas protection conditions, heating the iron-silicon alloy powder VI to 600-800° C. at 20-40° C. / min, keeping the temperature for 60-120 min, and oil quenching to obtain iron-silicon alloy powder VII; and / or,

[0099] Powder passivation: adding a phosphate acetone solution having a phosphoric acid concentration of 10% to 15%, mixing, and drying at 100 to 150° C. to obtain an iron-silicon alloy powder VIII; wherein the amount of the phosphate acetone solution added is 10% to 20% of the mass of the iron-silicon alloy powder VII; and / or,

[0100] Insulation coating: adding silicone resin, mixing, adding acetone and mixing, and drying at 50-60° C. to obtain iron-silicon alloy powder IX; wherein the amount of the silicone resin added is 0.1%-1.0% of the iron-silicon alloy powder VIII, and the amount of the acetone added is 10%-20% of the iron-silicon alloy powder VIII; and / or,

[0101] Compression molding: adding zinc stearate, mixing, and pressing at 1600-2100 MPa to prepare iron silicon magnetic powder core blank I; wherein the amount of zinc stearate added is 0.1%-0.5% of the mass of the iron silicon alloy powder IX; and / or,

[0102] Heat treatment: Under inert gas protection conditions, the iron silicon magnetic powder core blank I is kept at 600-800° C. for 60-120 min to obtain the iron silicon magnetic powder core blank II; and / or,

[0103] Strengthening treatment: providing a strengthening solution, which is a 2% to 10% one-component epoxy resin acetone solution; soaking the iron silicon magnetic powder core blank II in the strengthening solution for 20 to 60 minutes, washing with alcohol, and drying at 200° C. to 220° C. for 20 to 40 minutes to obtain the iron silicon magnetic powder core.

[0104] Alloy melting:

[0105] In some embodiments of the present invention, in the alloy smelting step, Fe powder and Si powder are added under inert gas protection conditions, heated to melt the Fe powder and Si powder, and then Co powder, Ti powder and V powder are added and smelted (preferably smelted at 1650°C to 1770°C). Among them, the addition amounts of Si powder, Fe powder, Co powder, Ti powder and V powder can be selected and adjusted according to the formula of the iron-silicon alloy composition of the first aspect of the present invention. In some embodiments, based on the total mass fraction of Si powder, Fe powder, Co powder, Ti powder and V powder being 100 parts, Si powder is 6 to 7 parts, Co powder is 0.3 to 1 part, Ti powder is 0.5 to 2 parts, V powder is 0.4 to 1 part, and the balance is Fe powder.

[0106] In some embodiments of the present invention, in the alloy melting step, the inert gas is nitrogen.

[0107] In some embodiments of the present invention, in the alloy smelting step, the mass fraction of Fe powder is 89-92.8 parts, further, it can be 90-92 parts, and example mass fractions are 89, 89.2, 89.5, 90, 90.5, 91, 91.2, 91.5, 92, 92.5, 92.8, etc.

[0108] In some embodiments of the present invention, the alloy melting step is performed in a magnesium oxide crucible vacuum medium frequency induction furnace.

[0109] In some embodiments of the present invention, in the alloy smelting step, after adding Fe powder, Si powder, Co powder, Ti powder and V powder, the alloy is smelted at 1650°C to 1700°C for 1 to 3 hours. Furthermore, the smelting time can be 1 to 2 hours, for example 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0110] In some embodiments, the alloy smelting step is carried out under nitrogen protection, preferably, nitrogen is continuously introduced at a rate of 0.2 L / min for nitrogen protection. In some embodiments, after the Fe powder, Si powder, Co powder, Ti powder and V powder are melted into molten steel, the molten steel is deoxidized with a deoxidizer.

[0111] Crushing and milling:

[0112] In some embodiments of the present invention, the alloy is directly subjected to gas atomization powdering after smelting to obtain iron-silicon alloy powder I. Traditional mechanical crushing powdering cannot guarantee the uniform spherical characteristics of the powder, and the magnetic properties are easily affected by the equipment, which is not conducive to large-scale production. The atomization method can directly crush the liquid metal to form metal droplets, which are finally condensed to form uniform metal magnetic powder, which mainly includes water atomization and gas atomization. Among them, the water atomization method uses water as a cooling medium, which makes the alloy easy to oxidize during preparation. The gas atomization method uses inert gas such as argon, nitrogen, etc. as an atomization medium, which can effectively reduce the oxygen content and reduce the oxidation of the alloy. The gas as an atomization medium has a slow cooling speed for the metal droplets, and the metal droplets will not solidify immediately. They gradually shrink into a sphere during the falling process, and it is easy to prepare spherical metal magnetic powder, which can further improve its magnetic properties.

[0113] In some embodiments of the present invention, nitrogen spray powdering is directly performed after the alloy is smelted, and the nitrogen pressure is 3.5-4.5 MPa, and can further be 3.8-4.2 MPa, for example 3.5 MPa, 3.8 MPa, 4.0 MPa, 4.2 MPa, 4.5 MPa, etc.

[0114] In some embodiments of the present invention, in the crushing and pulverizing step, the temperature is lowered by cooling to room temperature along with the furnace.

[0115] Particle size ratio:

[0116] In some embodiments of the present invention, iron-silicon alloy powder I is sieved through a 100-mesh sieve to obtain iron-silicon alloy powder II with a particle size of -300 mesh, iron-silicon alloy powder III with a particle size of +300 to -200 mesh, and iron-silicon alloy powder IV with a particle size of +200 to -100 mesh; the iron-silicon alloy powder II, iron-silicon alloy powder III and iron-silicon alloy powder IV are mixed in a proportion (preferably in a mass ratio of (1 to 2): (2 to 3): 1) to obtain iron-silicon alloy powder V.

[0117] In some embodiments of the present invention, in the particle size ratio step, the mass ratio of iron-silicon alloy powder II, iron-silicon alloy powder III and iron-silicon alloy powder IV is (1-2):(2-3):1, and can further be (1.5-2):(2.5-3):1, for example 1:2:1, 1:3:1, 2:2:1, 2:3:1, 1:2.5:1, 1.5:2.5:1, 2:2.5:1, 1.5:2:1, 1.5:3:1, etc.

[0118] Powder reduction:

[0119] In some embodiments of the present invention, in the powder reduction step, after vacuuming, hydrogen is introduced to heat the iron-silicon alloy powder V to 700-900°C, and then the temperature is reduced with the furnace after insulation to obtain the iron-silicon alloy powder VI. In some embodiments of the present invention, the powder reduction step is performed in a vacuum atmosphere furnace.

[0120] In some embodiments of the present invention, during the powder reduction step, the pressure is evacuated to -0.1 MPa and hydrogen is introduced, preferably, the concentration of hydrogen is 96% to 99.5%. The hydrogen concentration refers to the volume concentration of hydrogen in a relatively closed system.

[0121] In some embodiments of the present invention, in the powder reduction step, after hydrogen is introduced, the iron-silicon alloy powder V is heated to 700-900°C at 15-20°C / min, and kept warm for 60-120min to obtain the iron-silicon alloy powder VI. In some embodiments, the heating rate is 15-20°C / min, and can further be 16-18°C / min, for example, 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min, 20°C / min, etc. In some embodiments, the temperature is heated to 700-900°C and then kept warm, and the temperature of the heat preservation can be 700-900°C, and can further be 850-900°C, for example, 700°C, 750°C, 800°C, 850°C, 900°C, etc. In some embodiments, the insulation time is 60 to 120 min, and can further be 70 to 100 min, for example 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, etc.

[0122] In some embodiments of the present invention, after the powder reduction step (before the oil quenching step), the temperature is further lowered in the following manner: under the protection of a hydrogen atmosphere, the temperature is kept for 60 to 90 minutes, and then the temperature is lowered to 50 to 100° C. with the furnace.

[0123] Oil quenching treatment:

[0124] In some embodiments of the present invention, in the oil quenching step, the iron-silicon alloy powder VI is heated to 600-800°C under inert gas protection, kept warm, and oil quenched to obtain the iron-silicon alloy powder VII. Compared with the water quenching method in the conventional technology, the oil quenching treatment can obtain a lower magnetocrystalline anisotropy constant; if the oil quenching step is omitted, it is easy to cause the powder crystal phase to exist mainly in the form of a disordered phase, which is not conducive to obtaining better magnetic properties.

[0125] In some embodiments of the present invention, in the oil quenching step, the inert gas is nitrogen or helium.

[0126] In some embodiments of the present invention, in the oil quenching step, the iron silicon alloy powder VI is heated to 600-800°C at 20-40°C / min, and further, the heating rate can be 25-35°C / min, for example, 20°C / min, 25°C / min, 30°C / min, 35°C / min, 40°C / min, etc. In some embodiments, the iron silicon alloy powder VI is heated to 600-800°C and kept warm, and further, the temperature of the heat preservation can be 650-750°C, for example, 600°C, 650°C, 700°C, 750°C, 800°C, etc. In some embodiments, the heat preservation time can be 80-100min, for example, 60min, 70min, 80min, 90min, 100min, 110min, 120min, etc. In some embodiments, in the oil quenching step, the iron silicon alloy powder VI is kept at 700°C for 60min.

[0127] In some embodiments of the present invention, in the oil quenching step, engine oil is used for oil quenching, and further, the medium of the oil quenching is a high boiling point hydrocarbon mixture at a temperature of 650-750° C. An iron-silicon alloy powder VII with a smooth surface is obtained.

[0128] Powder passivation:

[0129] In some embodiments of the present invention, in the powder passivation step, acetone phosphate solution is added, mixed, and dried to obtain iron silicon alloy powder VIII. Changing the formula and concentration of the passivator and controlling the degree of passivation are one of the effective means to control the performance of the iron silicon magnetic powder core (effective magnetic permeability, quality factor Q, loss, frequency characteristics, etc.). In the present invention, in the powder passivation step, the loss of the iron silicon magnetic powder core can be reduced and the soft magnetic properties can be improved by using a suitable passivation agent and passivation method.

[0130] In some embodiments of the present invention, in the powder passivation step, a phosphate acetone solution with a phosphoric acid concentration of 10% to 15% is added and mixed, and dried at 100 to 150° C. to obtain an iron-silicon alloy powder VIII. Preferably, the amount of the phosphate acetone solution added is 10% to 20% of the mass of the iron-silicon alloy powder VII.

[0131] In some embodiments of the present invention, in the powder passivation step, acetone phosphate solution is added to the iron-silicon alloy powder VII at a rate of 1 to 5 mL / min. In some embodiments, the addition rate is 1 to 5 mL / min, and further can be 2 to 4 mL / min, and examples of the addition rate are 1 mL / min, 2 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, etc.

[0132] In some embodiments of the present invention, in the powder passivation step, a phosphate acetone solution with a phosphoric acid concentration of 10% to 15% is added and mixed, and further, the phosphoric acid concentration is 11 to 13%, for example, 10%, 11%, 12%, 13%, 14%, 15%, etc. In some embodiments, the phosphate acetone solution is added and mixed for 2 to 10 minutes, and further, the mixing time is 3 to 8 minutes, for example, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.

[0133] In some embodiments of the present invention, in the powder passivation step, acetone phosphate solution is added and mixed, and dried at 100-150°C. Further, the drying temperature is 100-120°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc.

[0134] In some embodiments of the present invention, in the powder passivation step, based on the mass percentage of the iron-silicon alloy powder Ⅶ being 100%, the mass percentage of the added acetone phosphate solution is 10% to 20%, and can further be 12 to 16%, for example 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0135] Insulation coating:

[0136] In some embodiments of the present invention, in the insulation coating step, silicone resin is added, mixed, acetone is added, mixed, and dried to obtain iron-silicon alloy powder IX. Insulation coating can further improve the soft magnetic properties of the magnetic powder core.

[0137] In some embodiments of the present invention, in the insulation coating step, silicone resin is added, mixed, acetone is added, mixed, and dried at 40-70° C. to obtain iron-silicon alloy powder IX. Preferably, the amount of silicone resin added is 0.1%-1.0% of the iron-silicon alloy powder VIII, and the amount of acetone added is 10%-20% of the iron-silicon alloy powder VIII.

[0138] In some embodiments of the present invention, in the insulation coating step, after adding the silicone resin, the mixing time is 1 to 3 minutes, for example 1 minute, 2 minutes, 3 minutes, etc.

[0139] In some embodiments of the present invention, in the insulation coating step, after adding acetone, the mixing time is 2 to 10 minutes, and can further be 3 to 8 minutes, for example, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc. In some embodiments, the acetone is analytical pure acetone, the purity of the acetone is 99.5%, and the water content of the acetone is less than 0.3%.

[0140] In some embodiments of the present invention, in the insulation coating step, the order of adding silicone resin and adding acetone is limited, and the silicone resin needs to be added first and mixed, and then the acetone needs to be added and mixed.

[0141] In some embodiments of the present invention, in the insulation coating step, silicone resin is added and mixed, acetone is added and mixed, and then dried at 50-60°C, for example 40°C, 50°C, 60°C, 70°C, etc.

[0142] In some embodiments of the present invention, in the insulation coating step, based on the mass percentage of the iron-silicon alloy powder VIII being 100%, the mass percentage of the added silicone resin is 0.1% to 1.0%, and can further be 0.1% to 0.5%, for example 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc.

[0143] In some embodiments of the present invention, in the insulation coating step, based on 100% by mass of the iron-silicon alloy powder VIII, the mass percentage of the acetone solution added is 10% to 20%, and can further be 12% to 16%, for example 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0144] Compression Molding:

[0145] In some embodiments of the present invention, in the compression molding step, zinc stearate is added, mixed, and pressed to prepare the iron silicon magnetic powder core blank I.

[0146] In some embodiments of the present invention, in the molding step, zinc stearate is added, mixed, and pressed at 1600-2100 MPa to prepare the iron silicon magnetic powder core blank I. Preferably, the amount of zinc stearate added is 0.1%-0.5% of the mass of the iron silicon alloy powder IX.

[0147] In some embodiments of the present invention, in the compression molding step, based on 100% by mass percentage of the iron-silicon alloy powder IX, the mass percentage of zinc stearate added is 0.1% to 0.5%, and can further be 0.2% to 0.4%, for example 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc.

[0148] In some embodiments of the present invention, in the compression molding step, after zinc stearate is added, mixing is performed for 1 to 4 minutes. Furthermore, the mixing time can be 2 to 3 minutes, for example, 1 minute, 2 minutes, 3 minutes, 4 minutes, and the like.

[0149] In some embodiments of the present invention, in the compression molding step, zinc stearate is added, mixed, and then pressed at 1600-2100 MPa. Further, the pressing pressure can be 1800-2000 MPa, for example, 1600 MPa, 1700 MPa, 1800 MPa, 1900 MPa, 2000 MPa, 2100 MPa, etc. In some embodiments, the pressing pressure is 1800 MPa.

[0150] Heat Treatment:

[0151] In some embodiments of the present invention, in the heat treatment step, the iron silicon magnetic powder core blank I is kept at 600-800° C. under inert gas protection conditions to obtain the iron silicon magnetic powder core blank II.

[0152] In some embodiments of the present invention, during the heat treatment step, the inert gas is nitrogen or helium.

[0153] In some embodiments of the present invention, in the heat treatment step, under the protection of inert gas, the iron silicon magnetic powder core blank I is kept at 600-800°C for 60-120 minutes to obtain the iron silicon magnetic powder core blank II. In some embodiments, the temperature of the insulation can be 600-800°C, and can further be 650-750°C, for example, 600°C, 650°C, 700°C, 750°C, 800°C, etc. In some embodiments, the insulation time is 60-120 minutes, and can further be 60-80 minutes, for example, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, etc. In some embodiments, the iron silicon magnetic powder core blank I is kept at 720°C for 60 minutes.

[0154] Enhanced treatment:

[0155] In some embodiments of the present invention, a strengthening solution is provided in the strengthening treatment step. Preferably, the strengthening solution is a 2% to 10% acetone solution of a single-component epoxy resin.

[0156] In some embodiments of the present invention, in the strengthening treatment step, the iron silicon magnetic powder core blank II is soaked in a strengthening solution, rinsed with alcohol, and dried to obtain an iron silicon magnetic powder core. In some embodiments, the soaking time can be 20 to 60 minutes, and further can be 30 to 50 minutes, for example, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc. In some embodiments, after rinsing with alcohol, it is dried at 200°C to 220°C, for example, 200°C, 205°C, 210°C, 215°C, 220°C, etc. In some embodiments, it is dried at 200°C to 220°C for 20 to 40 minutes to obtain an iron silicon magnetic powder core, and further, the drying time can be 25 to 35 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0157] In some embodiments of the present invention, in the strengthening treatment step, the iron silicon magnetic powder core blank II is immersed in a strengthening solution and then rinsed with alcohol until the surface is evenly coated and free of fine debris.

[0158] In some embodiments of the present invention, in the strengthening treatment step, the strengthening solution is a 2% to 10% one-component epoxy resin acetone solution according to the mass fraction ratio, and further, the mass of the one-component epoxy resin is 4 to 8% of the acetone solution, for example, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. In some embodiments, the acetone solution in the strengthening solution is an acetone aqueous solution with a volume concentration of 90% to 98%.

[0159] The fourth aspect of the present invention provides the use of the above-mentioned iron-silicon alloy composition or iron-silicon magnetic powder core in the preparation of electromagnetic devices. It can be used, but is not limited to, to prepare high-power (such as 2-4Kw) and high-current (such as 10-20A) electromagnetic devices, such as photovoltaic solar energy, new energy vehicles and charging piles and other new energy fields.

[0160] In some embodiments of the present invention, the electromagnetic device is an inverter for a DC charging station of an electric vehicle.

[0161] In some embodiments of the present invention, the electromagnetic device is a PFC inductor in a solar photovoltaic inverter.

[0162] In some embodiments of the present invention, the electromagnetic device is a high-power (power of 2 to 4Kw) APF active filter.

[0163] In some embodiments of the present invention, the electromagnetic device is a hybrid reactor.

[0164] In some embodiments of the present invention, the effective magnetic permeability of the iron silicon magnetic powder core is μ=60, at 100Oe, the DC superposition is ≥0.82, and the power loss Pcv (50kHz, 100mT) is ≤550mW / cm 3 . In some embodiments, the effective magnetic permeability μ of the iron silicon magnetic powder core is 60±2, and can further be μ=60±1, for example, 58, 58.5, 59, 59.4, 60, 61, 61.9, etc. In some embodiments, the effective magnetic permeability μ of the iron silicon magnetic powder core is 60. In some embodiments, at 100Oe, the DC superposition of the iron silicon magnetic powder core is ≥0.82, and further is 82% to 85%, for example, 82%, 82.3%, 82.6%, 83.2%, 84%, 85%, etc. In some embodiments, the power loss Pcv (50kHz, 100mT) of the iron silicon magnetic powder core is ≤550mW / cm 3 , further to 520~550mW / cm 3 , for example 520mW / cm 3 、528.9mW / cm 3 、530mW / cm 3 、537.3mW / cm 3 、540mW / cm 3 、548.6mW / cm 3 、550mW / cm 3 ,wait.

[0165] The following are some specific embodiments.

[0166] For experimental parameters not specified in the following specific embodiments, reference is made to the instructions given in the present application document, and reference may also be made to experimental manuals in the art or other experimental methods known in the art, or to experimental conditions recommended by manufacturers.

[0167] The raw materials and reagents involved in the following specific examples can be obtained from commercial sources, or can be prepared by those skilled in the art according to known methods.

[0168] raw material:

[0169] The raw materials in the following examples were purchased:

[0170] Fe powder was purchased from Taiyuan Steel; purity ≥ 99.8%;

[0171] Si powder was purchased from Yichang Jiashengxin; purity ≥ 99.8%;

[0172] Co powder was purchased from Maclean; purity ≥ 99.9%;

[0173] Ti powder was purchased from Sinopharm Group; purity ≥ 99.9%;

[0174] V powder was purchased from Maclean; purity ≥ 99.9%;

[0175] Phosphoric acid was purchased from Sinopharm Group; purity ≥ 85%

[0176] Acetone was purchased from Sinopharm Group; purity ≥ 99.5%

[0177] Silicone resin was purchased from Dow Corning; model 805; molecular weight 6000-10000Da;

[0178] The single-component epoxy resin was purchased from Dadong Resin; model 95F; molecular weight 900-1000Da;

[0179] Zinc stearate was purchased from Tianjin Damao; model AR / 500g.

[0180] Example 1

[0181] (1) Alloy smelting: under nitrogen protection, according to the sum of the mass percentage of Si powder, Fe powder, Co powder, Ti powder and V powder as 100wt%, add 91.6wt% Fe powder and 6.0wt% Si powder, deoxidize under nitrogen protection, after the Fe powder and Si powder are melted, add 1.0wt% Co powder, 1.0wt% Ti powder and 0.4wt% V powder, and smelt in a vacuum medium frequency induction furnace with a vacuum degree of <1.5Pa and a temperature of 1650-1700℃ for 1h;

[0182] (2) Crushing and powdering: After the alloy is smelted, it is directly powdered by nitrogen spraying at a nitrogen pressure of 4.5 MPa. The sprayed powder is cooled to room temperature along with the furnace to obtain iron-silicon alloy powder I.

[0183] (3) Particle size ratio: The iron silicon alloy powder I is sieved through a 100-mesh sieve to obtain an iron silicon alloy powder II with a particle size of -300 mesh, an iron silicon alloy powder III with a particle size of -300 mesh + 200 mesh, and an iron silicon alloy powder IV with a particle size of -200 mesh + 100 mesh; the iron silicon alloy powder II, the iron silicon alloy powder III, and the iron silicon alloy powder IV are mixed in a mass ratio of 3:5:2 to obtain an iron silicon alloy powder V.

[0184] (4) Powder reduction: The iron-silicon alloy powder V is placed in a hydrogen furnace, heated to 900°C at a rate of 20°C / min, kept at this temperature for 60 min, and then cooled to room temperature in the furnace to obtain the iron-silicon alloy powder VI.

[0185] (5) Oil quenching: Under nitrogen protection, the Fe-Si alloy powder VI was heated to 700°C at a rate of 30°C / min, kept at this temperature for 60 min, and oil quenched at 700°C for 10 min to obtain Fe-Si alloy powder VII.

[0186] (6) Powder passivation: Based on the mass percentage of the iron silicon alloy powder VII being 100%, 10% acetone phosphate solution (phosphoric acid concentration 10%) was added and mixed for 5 minutes, and dried at 150° C. to obtain the iron silicon alloy powder VIII.

[0187] (7) Insulation coating: Based on the mass percentage of the iron-silicon alloy powder VIII being 100%, 0.2% silicone resin was added and mixed, and 15% acetone solution was added and mixed, and the mixture was dried at 55° C. for 15 minutes to obtain an iron-silicon alloy powder IX.

[0188] (8) Compression molding: Based on the mass percentage of the iron-silicon alloy powder IX being 100%, 0.2% zinc stearate was added and mixed for 3 minutes; then the mixture was put into a mold of φ26.90×φ14.5×11.0 mm and pressed at a pressure of 1800 MPa to prepare the iron-silicon magnetic powder core blank Ⅰ.

[0189] (9) Heat treatment: Under nitrogen protection, the iron silicon magnetic powder core blank I was kept at 720°C for 60 min to obtain the iron silicon magnetic powder core blank II.

[0190] (10) Strengthening treatment: a single-component epoxy resin (6%) and an acetone solution (95%) were mixed in a mass ratio of 1:9 to prepare a strengthening solution; the iron silicon magnetic powder core blank II was immersed in the strengthening solution for 20 minutes, rinsed with alcohol until the surface was smooth and free of debris, and baked at 200° C. for 30 minutes to obtain the iron silicon magnetic powder core.

[0191] Example 2

[0192] An iron silicon magnetic powder core was prepared by a preparation method basically the same as that in Example 1, except that: in step (1), based on the sum of the mass percentages of Si powder, Fe powder, Co powder, Ti powder and V powder being 100wt%, 91.2wt% of Fe powder, 6.5wt% of Si powder, 1.0wt% of Co powder, 0.5wt% of Ti powder and 0.8wt% of V powder were added; and the remaining parameters and operating steps were the same as those in Example 1.

[0193] Example 3

[0194] An iron silicon magnetic powder core was prepared by a preparation method basically the same as that in Example 1, except that: in step (1), based on the sum of the mass percentages of Si powder, Fe powder, Co powder, Ti powder and V powder being 100wt%, 91.4wt% of Fe powder, 7.0wt% of Si powder, 0.5wt% of Co powder, 0.5wt% of Ti powder and 0.6wt% of V powder were added; and the remaining parameters and operating steps were the same as those in Example 1.

[0195] Comparative Example 1

[0196] An iron silicon magnetic powder core was prepared by a preparation method basically the same as that in Example 1, except that: in step (1), based on the sum of the mass percentages of Si powder, Fe powder, V powder and Nb powder being 100wt%, 93wt% of Fe powder, 6.4wt% of Si powder, 0.4wt% of V powder and 0.2wt% of Nb powder were added; and the remaining parameters and operating steps were the same as those in Example 1.

[0197] Comparative Example 2

[0198] An iron silicon magnetic powder core is prepared by a preparation method basically the same as that in Example 1, except that: in step (1), 92.9wt% of Fe powder, 7wt% of Si powder and 0.1wt% of Co powder are added, based on the sum of the mass percentages of Si powder, Fe powder and Co powder being 100wt%; the remaining parameters and operating steps are the same as those in Example 1.

[0199] Comparative Example 3

[0200] An iron silicon magnetic powder core was prepared by a preparation method basically the same as that in Example 1, except that: in step (1), based on the sum of the mass percentages of Si powder, Fe powder, Cr powder and V powder being 100wt%, 92.93wt% of Fe powder, 6.85wt% of Si powder, 0.1wt% of Cr powder and 0.12wt% of V powder were added; the remaining parameters and operating steps were the same as those in Example 1.

[0201] Comparative Example 4

[0202] An iron silicon magnetic powder core is prepared by a preparation method basically the same as that in Example 1, except that: in step (1), 93.5wt% of Fe powder and 6.5wt% of Si powder are added based on the sum of the mass percentages of Si powder and Fe powder being 100wt%; the remaining parameters and operating steps are the same as those in Example 1.

[0203] Performance Testing

[0204] The following performance tests (Table 1) were performed on the iron silicon magnetic powder cores of Examples 1 to 3, and the test standards were "Material Characteristics 106 Ring" and "Q / YAJS10-2011 Standard for Powders for Magnetic Materials".

[0205] Table 1

[0206]

[0207] Note: 100mT = 1000Gs

[0208] According to the data in Table 1, it can be found that the iron silicon magnetic powder core of the present application has low core loss and good DC superposition characteristics, and is suitable for use in electric vehicle DC charging pile inverters, PFC inductors in solar photovoltaic inverters, high-power active filters (APFs) and hybrid reactors. It can also be found that changing the formula type or omitting some trace elements will result in a significant reduction in the DC superposition characteristics under the same effective permeability.

[0209] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as a reference separately. Unless they conflict with the invention purpose and / or technical solution of the present application, the cited documents involved in the present invention are cited with all contents and all purposes. When the present invention involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the present invention involves cited documents, the examples and preferred embodiments of the cited relevant technical features may also be incorporated into this application as references, but are limited to the ability to implement the present invention. It should be understood that when the content of the citation conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0210] The technical features of the above-mentioned implementation modes and examples can be combined in any appropriate manner. To make the description concise, not all possible combinations of the technical features in the above-mentioned implementation modes and examples are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0211] The above-described embodiments only express several implementation methods of the present invention, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, without departing from the concept of the present invention, several variations and improvements can be made, which all belong to the protection scope of the present invention. In addition, it should be understood that after reading the above-mentioned teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. It should also be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description and drawings may be used to explain the contents of the claims.

Claims

1. A method for preparing an iron silicon magnetic powder core, characterized in that: It includes alloy smelting, crushing and powdering, particle size ratio, powder reduction, oil quenching, powder passivation, insulation coating, compression molding, heat treatment and strengthening treatment steps; Alloy smelting: under inert gas protection conditions, add Fe powder and Si powder, heat to melt Fe powder and Si powder, then add Co powder, Ti powder and V powder, and smelt at 1650℃~1770℃; wherein, according to the total mass parts of Si powder, Fe powder, Co powder, Ti powder and V powder is 100 parts, Si powder is 6~7 parts, Co powder is 0.3~1 parts, Ti powder is 0.5~1.0 parts, V powder is 0.4~0.8 parts, and the balance is Fe powder; Crushing and powdering: After the alloy is smelted, it is directly subjected to aerosol powdering to obtain iron-silicon alloy powder I; Particle size ratio: the iron-silicon alloy powder I is sieved to obtain an iron-silicon alloy powder II with a particle size of -300 mesh, an iron-silicon alloy powder III with a particle size of -200 mesh to +300 mesh, and an iron-silicon alloy powder IV with a particle size of -100 mesh to +200 mesh; the iron-silicon alloy powder II, the iron-silicon alloy powder III and the iron-silicon alloy powder IV are mixed in a mass ratio of (1-2):(2-3):1 to obtain an iron-silicon alloy powder V; Powder reduction: after evacuation, hydrogen is introduced, the temperature of the iron-silicon alloy powder V is raised to 700-900° C. at 15-20° C. / min, and the temperature is kept for 60-120 min to obtain the iron-silicon alloy powder VI; Oil quenching treatment: under inert gas protection conditions, heating the iron-silicon alloy powder VI to 600-800° C. at 20-40° C. / min, keeping the temperature for 60-120 min, and oil quenching to obtain iron-silicon alloy powder VII; Powder passivation: adding a phosphate acetone solution having a phosphoric acid concentration of 10% to 15%, mixing, and drying at 100 to 150° C. to obtain an iron-silicon alloy powder VIII; wherein the amount of the phosphate acetone solution added is 10% to 20% of the mass of the iron-silicon alloy powder VII; Insulation coating: adding silicone resin, mixing, adding acetone, mixing, and drying at 50-60° C. to obtain iron-silicon alloy powder IX; wherein the amount of the silicone resin added is 0.1%-1.0% of the iron-silicon alloy powder VIII, and the amount of the acetone added is 10%-20% of the iron-silicon alloy powder VIII; Compression molding: adding zinc stearate, mixing, and pressing at 1600-2100 MPa to prepare iron silicon magnetic powder core blank I; wherein the amount of zinc stearate added is 0.1%-0.5% of the mass of the iron silicon alloy powder IX; Heat treatment: Under inert gas protection conditions, the iron silicon magnetic powder core blank I is kept at 600-800° C. for 60-120 min to obtain the iron silicon magnetic powder core blank II; Strengthening treatment: providing a strengthening solution, which is a 2wt% to 10wt% one-component epoxy resin acetone solution; soaking the iron silicon magnetic powder core blank II in the strengthening solution for 20 to 60 minutes, washing with alcohol, and drying at 200 to 220° C. for 20 to 40 minutes to obtain the iron silicon magnetic powder core.

2. The method for preparing the iron silicon magnetic powder core according to claim 1, characterized in that: In the alloy smelting step, the mass fraction of the Fe powder is 89 to 92.8 parts.

3. An iron silicon magnetic powder core, characterized in that: The invention relates to an iron silicon magnetic powder core prepared by the method for preparing the iron silicon magnetic powder core according to claim 1 or 2.

4. The iron silicon magnetic powder core according to claim 3, characterized in that: It comprises a core and an outer cladding layer. From the core to the outside, the outer cladding layer comprises the following structural layers in sequence: a passivation layer, an insulating layer, a molding layer and a strengthening layer.

5. The iron silicon magnetic powder core according to claim 4, characterized in that: The main component of the passivation layer is ferrous phosphate; The main component of the insulating layer is silicone resin; The main component of the molded layer is zinc stearate; The main component of the strengthening layer is epoxy resin.

6. The iron silicon magnetic powder core according to claim 5, characterized in that: The content of the silicone resin is 0.1% to 1.0% of the mass of the core; The content of zinc stearate is 0.1% to 0.5% of the total mass of the core and the passivation layer; The content of the epoxy resin is 2% to 10% of the total mass of the core, the passivation layer and the molded layer.

7. Use of the iron silicon magnetic powder core prepared by the preparation method according to any one of claims 1 to 2, or the iron silicon magnetic powder core according to any one of claims 3 to 6 in the preparation of electromagnetic devices.

8. The use according to claim 7, characterized in that: The electromagnetic device is an inverter for a DC charging pile of an electric vehicle, a PFC inductor in a solar photovoltaic inverter, an active filter or a hybrid reactor.

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