WO2020252551A1 - Matériau particulaire pour l'obtention d'un composite magnétique doux et procédé de production de matériau particulaire pour l'obtention d'un composite magnétique doux - Google Patents

Matériau particulaire pour l'obtention d'un composite magnétique doux et procédé de production de matériau particulaire pour l'obtention d'un composite magnétique doux Download PDF

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WO2020252551A1
WO2020252551A1 PCT/BR2020/050218 BR2020050218W WO2020252551A1 WO 2020252551 A1 WO2020252551 A1 WO 2020252551A1 BR 2020050218 W BR2020050218 W BR 2020050218W WO 2020252551 A1 WO2020252551 A1 WO 2020252551A1
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soft magnetic
particles
layer
ferromagnetic particles
particulate material
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PCT/BR2020/050218
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English (en)
Portuguese (pt)
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Leandro Lima EVANGELISTA
Antonio Itamar Filho RAMOS
Letícia Espíndola MACHADO
Gustavo TONTINI
Aloisio Nelmo Klein
Valderes DRAGO
Gisele Hammes
Cristiano Binder
Nelson Jhoe Batistela
Roberto Binder
Felipe Darabas RZATKI
Bernardo Sena da SILVA
Indiara Pitta Corrêa da SILVA
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Universidade Federal De Santa Catarina
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
    • B60Q1/26—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic
    • B60Q1/34—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction
    • B60Q1/38—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction using immovably-mounted light sources, e.g. fixed flashing lamps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/33—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials mixtures of metallic and non-metallic particles; metallic particles having oxide skin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
    • B60Q1/26—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic
    • B60Q1/34—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction
    • B60Q1/346—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction with automatic actuation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
    • B60Q1/26—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic
    • B60Q1/34—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction
    • B60Q1/40—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction having mechanical, electric or electronic automatic return to inoperative position

Definitions

  • the present invention describes a particulate material for obtaining a soft magnetic composite (SMC), this material comprising ferromagnetic particles coated by at least two layers of coating, at least one layer of oxide nanoparticles and at least one layer glassy, said covering layers promoting greater continuity, homogeneity and adhesion of insulating coatings on ferromagnetic particles.
  • SMC soft magnetic composite
  • the present invention also relates to a process of producing particulate material to obtain soft magnetic composite (SMC).
  • the present invention is located in the field of Mechanical Engineering, Electrical Engineering, Chemical Engineering and Materials Engineering. Fundamentals of the Invention
  • Soft Magnetic Composite - SMC Soft Magnetic Composite - SMC
  • this material is composed of ferromagnetic particles covered with an electrical insulating material, thus preventing the passage of electrical current between particles. This fact allows the SMC to considerably eliminate the difficulty related to eddy currents and thereby maintain the efficiency of machines and electrical devices at medium and high frequency.
  • the SMC presents another important characteristic, which is its three-dimensional isotropic ferromagnetic behavior, which offers the electrical equipment design possibilities for improvement in relation to thermal characteristics, design flexibility, processing and assembly , in addition to the contribution in reducing the costs of scale production.
  • SMCs with organic coating present themselves as advantageous in terms of cost and simplicity of the production process in relation to inorganic coatings.
  • the temperature limitation for heat treatment of SMCs with organic coating makes the losses of this type of SMC relatively high, especially due to the static loss component.
  • this type of SMC also suffers from the degradation of polymers over time, leading to deterioration of mechanical resistance and electrical resistivity.
  • SMCs that have inorganic coatings allow heat treatments at higher temperatures, providing greater stress relief and lower losses, which would lead to the possibility of more efficient electrical machines.
  • This patented material was designed focusing on high frequency applications and, according to the invention, its good characteristics for working in these conditions are due to the fact that (a) the metal particle with average diameters of 20 to 70nm easily form magnetic domains, (b) the the metallic particle is covered with a stable first insulating layer such as Si02 and (c) that the first insulating layer is covered by a eutectic crystal produced by the reaction between the first and the second insulating layer.
  • the material can be processed in order to produce a component through (1) lamination (sheet-molding), being able to rely on magnetic alignment, followed by heating to form the eutectic between the oxides that make up the insulating coating to form the composite matrix or by (2) grinding the particles coated with a double layer in a ball mill, followed by washing, drying, dispersion in acetone, centrifugation, organization of the particles in acetone in order to achieve high density, separation of acetone maintaining the ordering carried out, drying of residual acetone, compaction using a pressure close to 10OMPa in a body with a thickness close to 400pm, and heat treatment in an argon atmosphere at 500 ° C.
  • the material is dedicated to the production of small devices, such as antennas, making it difficult to use for electrical machine projects with larger volume cores, for example.
  • the material of the patent US2008 / 0029300A1 is especially used in applications above 100MHz, that is, in frequencies where eddy currents represent the dominant fraction over the losses of a ferromagnetic core.
  • the high density of the SMC is vital to achieve high permeability and low losses through hysteresis, which have an appreciable weight on the total magnetic losses at frequencies up to 1kHz.
  • the density of composites obtained by the methods described in US2008 / 0029300A1 hardly reach those obtained by the conventional compaction process and heat treatment of SMCs using micrometric particles.
  • FeSiAl or FeSi powder mixed with ethanol, a silane coupling agent and deionized water, and to that mixture is added a silicon precursor, such as tetraethyl orthosilicate (TEOS), and a certain amount of ammonia.
  • TEOS tetraethyl orthosilicate
  • Such mixture is stirred for 2-8 hours at a temperature of 40-100 ° C and pH adjusted between 7-8, followed by magnetic separation, washing with anhydrous ethanol and deionized water and drying at 40-100 ° C to obtain the particles coated with SiO2.
  • these particles are mixed with n-butyl borate, absolute ethanol, polyethylene glycol and deionized water, with a pH adjusted between 5-6 using acetic acid.
  • the mixture is kept under stirring at 40-80 ° C for 1-5 hours to complete the reaction and finally, the coated and dry powder undergoes calcination carried out between 400 - 500 ° C.
  • the patent WO2018035595 also claims the production of SMCs using alkali metal silicates containing submicrometric particles dispersed inside.
  • the submicrometric particles dispersed in the silicate act (a) as thermal masses, absorbing the heat provided during the heat treatment and increasing the time necessary for the coating to undergo the glass transition; (b) as a thickening agent, keeping the coating adhered to the surface of the particles even after their glass transition; (c) as a nucleating agent, encouraging the silicate crystallization process at lower temperatures; (d) dissolving and partially or totally altering the composition of the silicate itself.
  • a particulate material for obtaining a soft magnetic composite comprising ferromagnetic particles coated by at least two layers of coating, at least one layer of oxide nanoparticles and at least one glassy layer, said layers of coating promoting greater continuity , homogeneity and adhesion of insulating coatings on ferromagnetic particles.
  • the objective of the present invention to provide a particulate material for obtaining a soft magnetic composite (SMC) in which the first layer of the coating, called oxide layer, contributes to increase the electrical resistivity due to its insulating nature and improves the conditions of wetting of the second insulating layer of the coating, called the vitreous layer, on the ferromagnetic particles during the heat treatment to produce the soft magnetic composites.
  • SMC soft magnetic composite
  • SMC soft magnetic composite
  • a particulate material to obtain a soft magnetic composite comprising ferromagnetic particles covered by at least one oxide layer and at least one glassy layer; said particulate material in which said ferromagnetic particles comprise pure metals or ferromagnetic alloys containing at least one of the elements selected from Fe, Ni and Co and comprises particles of average size between 10pm and 500pm;
  • the oxide layer comprises nanometric particles of oxides selected from ZnO, T1O2, MgO, AI2O3, M h 3 ⁇ 04, MnO, M h 2q3, MnCh, MnCb and M h 2q7 with an average size between 0.005pm and lpm;
  • the vitreous layer comprises vitreous phase or precursor to vitreous phase based on compounds selected from alkali metal silicates such as liquid glass like Na20-nSiC> 2 and BbO-mSiCh or boron oxide or boron oxide precursors such as boric acid, metabolic acid, t
  • the objectives are achieved through a process of producing particulate material for obtaining a soft magnetic composite in which the coating of ferromagnetic particles by the oxide layer is characterized by a liquid mixing of the ferromagnetic particles with a suspension of nanoparticles of at least one of the oxides selected from ZnO, T1O2, MgO, AI2O3, Mn3C> 4, MnO, Mn2C> 3, MnC> 2, MnC> 3, Mn2C> 7.
  • nanoparticles of at least one of the oxides ZnO, THIO2, MgO, AI2O3, M h 3q4, MnO, M3 ⁇ 4q3, M h q2, M h q3, M h 2q7 are preferably synthesized from of metallic hydroxides of Zn, Ti, Mg, Ai or Mn simultaneously to the said mixing stage with ferromagnetic particles by the reaction between water-soluble hydroxides and precursors of metallic hydroxides.
  • the process of producing particulate material to obtain soft magnetic composite provides that water-soluble hydroxides are selected from NaOH, KOH, NH 4 OH and metal salts precursors of the hydroxides Metals are selected from Zn, Ti, Mg, Ai or Mn salts.
  • the production process provides that the coating of the ferromagnetic particles with the oxide layer is carried out in a liquid medium; the process comprising the steps of: (I) mixing, under agitation, the ferromagnetic particles, in a mass proportion of 30% to 60%, with a suspension containing oxide nanoparticles or metallic hydroxides precursors of nanoparticles synthesized simultaneously with the mixing step of this suspension with ferromagnetic particles, containing a molar concentration of nanoparticles between 1 and 500mM; (II) removal of excess nanoparticles suspension and subsequent drying of the mixture obtained in step (I) at temperatures between room temperature and 150 ° C.
  • the ferromagnetic particles previously covered by the oxide layer are covered with the insulating material of the vitreous layer, the process comprising the steps: (I ) coating of ferromagnetic particles by immersion or incipient wetting with a suspension of alkali metal silicates of the type liquid glass or boron oxide or glass phase precursor based on boron oxide precursors selected from boric acid, metabolic acid, tetraboric acid, ammonium tetraborate, pentaborate, peroxyborate, in the proportion by weight of 65% to 95% of coated ferromagnetic particles and 5% to 35% of glass phase suspension or glass phase precursor; and (II) drying the coated composite at a temperature between room temperature and 150 ° C.
  • the solution of boron oxide precursors is composed of the dilution of one or more precursors selected from boric acid, metabolic acid, tetraboric acid, ammonium tetraborate, pentaborate, peroxyborate; the solution of said precursors being prepared in a concentration between 0.001g / mL and lg / mL and containing a mass of precursors between 0.01% to 10.00% in relation to the mass of ferromagnetic particles of the soft magnetic composite.
  • the alkali metal silicate solution is composed of the dilution of one or more silicates, and the molar ratio between the silica molecules and alkali metal oxides must be between 0.5 and 8; the alkali metal silicate solution or mixture of silicates should contain a solids concentration between 0.001mg / ml and 15mg / ml.
  • Figure 1 illustrates ferromagnetic particles with double insulating coating
  • Figure 2 illustrates the behavior of the oxide and vitreous layers during the stages of compaction and heat treatment at the interface between the coated ferromagnetic particles
  • Figure 3 illustrates the advantages in magnetic behavior in terms of reducing magnetic losses of the patented material with double insulating layer in relation to solutions containing only one insulating layer;
  • a particulate material for obtaining a soft magnetic composite (here also called SMC) comprising ferromagnetic particles coated by at least one oxide layer and at least one vitreous layer ;
  • the oxide layer comprises nanometric particles of oxides selected from ZnO, T1O2, MgO, AI2O3, MnsCq, MnO, Mh2q3, Mhq2, MnCb and Mh2q7, "where the glassy layer comprises an oxide phase with low glass transition temperature or glass phase precursor based on compounds selected from alkali metal silicates such as liquid glass like Na20-nSiC> 2 and BbO-mSiCh or boron oxide or boron oxide precursors like boric acid, metabolic acid, tetraboric acid, ammonium tetraborate, pentaborate, peroxyborate; the soft magnetic composite in which the nanoparticles comprising the oxide layer have an average size between 0.005pm and
  • the particulate material for obtaining a soft magnetic composite consists of more than one insulating layer, being a first layer of inorganic insulation based on nanometric oxide particles, referred to in this invention as the oxide layer.
  • This layer includes nanoparticles of zinc oxide, magnesium oxide, aluminum oxide, titanium oxide or manganese oxide, or a mixture of these oxides.
  • These nanometric particles cover the ferromagnetic particles preferentially in a liquid medium by contact under agitation with a dispersion of nanometric particles of these oxides or with sol-gel suspensions of hydroxides of these elements, which are converted to oxide form in the course of processing.
  • the aforementioned nanometric particles in the oxide layer penetrate, even if minimally, the surface of the ferromagnetic particles. This effect leads to an increase in oxide layer on the ferromagnetic particles.
  • This layer named in this invention as the vitreous layer, has high electrical resistivity and good wetting in relation to the compounds of the oxide layer, in order to allow the mechanism of self-healing of cracks during heat treatment. Adding to the crack regeneration effect and the adhesion of the first layer on the ferromagnetic particles, there is a complete coating of the ferromagnetic particles, promoting the high electrical resistivity and low magnetic losses of the SMC.
  • the selection of the particle size defines an effective way of adjusting the optimal properties for application at different frequencies, using the same insulating system and the same covering method.
  • the first layer of the coating contributes to increase the electrical resistivity due to its insulating nature and improves the wetting conditions of the second insulating layer of the coating, called the glassy layer, on the ferromagnetic particles during the heat treatment for production of soft magnetic composites.
  • the oxides formed have great chemical affinity in relation to the vitreous layer, reducing the interface energy between the compounds and resulting in a good wettability between them, that is, they form a low contact angle of the vitreous layer on the oxide nanoparticles layer. Because of this good wettability, it is possible to obtain a complete coating of the ferromagnetic particle and promote a synergistic effect between the two layers that results in an insulating film of high resistivity and good adhesion on the ferromagnetic particles.
  • the oxide layer can also act as a nucleating agent for the crystallization process of the vitreous phase, which increases the viscosity of the vitreous layer and assists in maintaining the high electrical resistivity of the insulating film. .
  • the present invention proposes a process for the production of a particulate material to obtain a soft magnetic composite in which the coating of the ferromagnetic particles by the oxide layer is characterized by occurring through liquid mixing of the ferromagnetic particles with a suspension of nanoparticles of at least one of the oxides selected from ZnO, T1O2, MgO, AI2O3, Mn3C> 4, MnO, Mn2C> 3, MnCó, MnCq, Mn2C> 7.
  • nanoparticles of at least one of the oxides ZnO, T1O2, MgO, AI2O3, Mh3q4, MnO, M3 ⁇ 4q3, Mhq2, Mhq3, Mh2q7 are preferably synthesized from metallic hydroxides of Zn, Ti, Mg, Ai or Mn simultaneously to said mixing stage with ferromagnetic particles by the reaction between water-soluble hydroxides and precursors of metal hydroxides; the water-soluble hydroxides being selected from NaOH, KOH, NH4OH or similar and metal salts precursor to the metal hydroxides are selected from Zn, Ti, Mg, Ai or Mn salts.
  • the ferromagnetic particles are coated with the oxide layer in a liquid medium; the process comprises the steps of: mixing, under agitation, the ferromagnetic particles, in a mass proportion of 30% to 60%, with a suspension containing oxide nanoparticles or metallic hydroxides precursors of nanoparticles synthesized simultaneously with the mixing step of this suspension with the particles ferromagnetic, containing a molar concentration of nanoparticles between 1 and 500mM, and removal of excess nanoparticles suspension and subsequent drying of the mixture obtained in step (I) at temperatures between room temperature and 150 ° C.
  • the coating with insulating material of the vitreous layer occurs, in a process comprising the steps of: coating of the ferromagnetic particles by immersion or incipient wetting with a suspension of alkali metal silicates such as liquid glass or boron oxide or glass phase precursor based on boron oxide precursors selected from boric acid, metabolic acid, tetraboric acid, ammonium tetraborate, pentaborate, peroxyborate or similar, na mass proportion of 65% to 95% of coated ferromagnetic particles and 5% to 35% of glass phase suspension or glass phase precursor; and drying the coated composite with temperature between room temperature and 150 ° C.
  • alkali metal silicates such as liquid glass or boron oxide or glass phase precursor based on boron oxide precursors selected from boric acid, metabolic acid, tetraboric acid, ammonium tetraborate, pentaborate, peroxyborate or similar, na mass proportion of 65% to 95% of coated ferromagnetic particles
  • the solution of boron oxide precursors is composed of the dilution of one or more precursors selected from boric acid, metabolic acid, tetraboric acid, ammonium tetraborate, pentaborate, peroxyborate or the like; the solution of said precursors being prepared at a concentration between 0.001g / mL and lg / mL and more preferably between 0.002g / mL and 0.02g / mL, and containing a mass of precursors between 0.01% to 10.00% and more preferably between 0.05% and 5.00% in relation to the mass of ferromagnetic particles of the soft magnetic composite.
  • the alkali metal silicate solution is composed of the dilution of one or more silicates, with the molar ratio between the silica molecules and alkali metal oxides being between 0.5 and 8 and more preferably between 1.5 and 4; the alkali metal silicate solution or mixture of silicates must contain a solids concentration between 0.001mg / ml and 15mg / ml and more preferably between 0.005mg / ml and 5mg / ml.
  • incipient wetting arises from the English translation of the expression Inc ⁇ p ⁇ ent wetness, which can also be translated by "capillary impregnation” or “dry impregnation” and refers to cyclic processes of partial and drying a solution on a substrate; in the case of that patent, on ferromagnetic particles. During this process, a layer of precipitates forms on the particles homogeneously and with a layer thickness that can be controlled.
  • a route to the production process of a particulate material for obtaining generalized soft magnetic composite for the production of powders containing double coating for the manufacture of soft magnetic composite materials follows the steps: 1 - Preparation of a suspension containing oxide or hydroxide nanoparticles, which can be prepared directly by dispersing commercial nanoparticles in liquid medium or by mixing appropriate chemical solutions for the synthesis of these nanoparticles simultaneously with the subsequent step. 2 - Mixing of ferromagnetic particles, under agitation, with the suspension prepared in step 1 promoting the adhesion of the oxide or hydroxide nanoparticles, synthesized simultaneously or not, to the surface of the ferromagnetic particles, thus forming the oxide layer.
  • 3 Magnetic separation of ferromagnetic powder, coated with the oxide layer, from the rest of the suspension and drying. 4 - Addition of the vitreous layer, by immersion or incipient wetting, to the ferromagnetic powder previously coated with the oxide layer, using a solution containing glassy compounds or precursors that will form the vitreous layer. 5 - Magnetic separation of ferromagnetic powder coated with double layer of insulators from the rest of the suspension and drying.
  • the double-coated ferromagnetic particles are obtained as schematically shown in Figure 1. Next, these particles are mixed with a compaction lubricant, followed by the uniaxial compaction and heat treatment steps, resulting in the dimensions and microstructure suitable for use of the SMC material.
  • the nanoparticles that make up the oxide layer slightly penetrate the surface of the ferromagnetic particles due to the difference in hardness. This leads to a better anchoring of the oxide layer on the ferromagnetic powder, despite generating some discontinuity of the insulating film due to the high pressures of the compaction step.
  • some precursors of the vitreous layer such as boric acid (H 3 BO 3 ), for example, can add a lubricating effect, helping to process the material in this compacting stage.
  • SMC compacted parts are usually heat treated to relieve stress and increase mechanical strength.
  • the formation of the vitreous phase is also sought, when only precursors of that phase are added, and the process of self-healing of the cracks.
  • Self-regeneration comes from good wettability between the compounds used in the oxide layer and the compounds that make up the glassy layer at the end of the heat treatment.
  • the vitreous layer ends up covering the entire ferromagnetic particle, allowing to regenerate the cracks of coating generated during the compaction stage during the subsequent heat treatment.
  • the oxide layer also acts as a nucleating agent for the crystallization process of the vitreous phase, and may even be partially dissolved during this process.
  • the behavior of the oxide and vitreous layers during the stages of compaction and heat treatment at the interface between two coated ferromagnetic particles are shown schematically in Figure 2.
  • the iron particles covered with the insulating nanoparticles are separated from the rest of the suspension, washed with a mixture of ethanol and water, and finally dried in a vacuum oven at 80 ° C for 30 minutes. After drying, the iron particles are coated with a layer of zinc oxide (ZnO) nanoparticles. This layer comes from the transformation of Zn (OH) 2 into ZnO, which started in the mixing stage and ended in the drying stage.
  • ZnO zinc oxide
  • a heated solution of isopropanol containing a mass concentration of 0.5% boric acid (H 3 BO 3 ) dissolved is prepared.
  • the iron powder, coated with ZnO as an oxide layer, is then immersed in this solution so that the mass concentration of the ferromagnetic powder in this solution is 83.5%.
  • the powder is kept in contact with the solution until complete drying by evaporation of isopropanol.
  • iron particles have a double coating of insulators, that is, containing the oxide layer and precursor to the glassy layer.
  • the iron particles covered with the insulating nanoparticles are separated from the rest of the suspension, washed with a mixture of ethanol and water, and finally dried in a vacuum oven at 80 ° C for 30 minutes. After drying, the iron particles are coated with a layer of zinc oxide (ZnO) nanoparticles. This layer comes from the transformation of Zn (OH) 2 into ZnO, which started in the mixing stage and ended in drying step.
  • ZnO zinc oxide
  • a level of lubricant extraction temperature in this example, a temperature of 320 ° C is used for 30 minutes, and a second level at a higher temperature for stress relief and increased mechanical strength, where for the sample in question, the temperature of 500 ° is used C at a 30-minute level.
  • Iron particles with an average particle size of 180pm, are immersed in a heated isopropanol solution containing a mass concentration of 0.5% dissolved boric acid (H3BO3).
  • the iron powder without previous coating, is then immersed in this solution so that the mass concentration of the ferromagnetic powder is 83.5%.
  • the powder is kept in contact with the solution until complete drying by evaporation of isopropanol. After the isopropanol has dried, the iron particles have only the precursor coating of the vitreous layer.
  • the iron particles covered with the insulating nanoparticles are separated from the rest of the suspension, washed with a mixture of ethanol and water, and finally dried in a vacuum oven at 80 ° C for 30 minutes. After drying, the iron particles are coated with a layer of zinc oxide (ZnO) nanoparticles. This layer comes from the transformation of Zn (OH) 2 into ZnO, mixing stage and finalized in the drying stage.
  • ZnO zinc oxide
  • an aqueous solution containing manganese acetate tetrahydrate (Mn (CH3COO) 2 ⁇ 4H2O) with a mass concentration of 0.97% and the same volume as the previous NaOH solution is added, under strong stirring, to the NaOH solution containing the iron particles in order to synthesize manganese hydroxide (Mn (OH) 2) nanoparticles concomitantly with the adhesion of these nanoparticles to the surface of the iron particles.
  • Mn (OH) 2 manganese hydroxide
  • the iron particles covered with the insulating nanoparticles are separated from the rest of the suspension, washed with a mixture of ethanol and water, and finally dried in a vacuum oven at 80 ° C for 30 minutes. After drying, the iron particles are coated with a layer of manganese oxide nanoparticles (MnsCh). This layer comes from the transformation of Mn (OH) 2 into (MnsCh), which started in the mixing stage and ended in the drying stage.
  • H3B03 a heated isopropanol solution containing a mass concentration of 0.5% dissolved boric acid
  • an aqueous solution containing magnesium chloride hexahydrate (MgCl2 ⁇ 6H2O) with a mass concentration of 0.81% and the same volume as the previous NaOH solution is added, under strong stirring, to the NaOH solution containing the iron particles, in order to synthesize magnesium hydroxide (Mg (OH) 2) nanoparticles concomitantly with the adhesion of these nanoparticles to the surface of the iron particles.
  • Mg (OH) 2 magnesium hydroxide
  • the iron particles covered with the insulating nanoparticles are separated from the rest of the suspension, washed with a mixture of ethanol and water, and finally dried in a vacuum oven at 80 ° C for 30 minutes. After drying, the iron particles are coated with a layer of magnesium oxide (MgO) nanoparticles. This layer comes from the transformation of Mg (OH) 2 into MgO, which started in the mixing stage and ended in the drying stage.
  • MgO magnesium oxide
  • (b) Vitre Layer Formation - B2O3 Precursor After adding the first coating layer, a heated isopropanol solution containing 0.5% mass concentration of dissolved boric acid (H 3 BO 3 ) is prepared . The iron powder, coated with MgO as an oxide layer, is then immersed in this solution so that the mass concentration of the ferromagnetic powder in this solution is 83.5%. The powder is kept in contact with the solution until complete drying by evaporation of isopropanol. After the isopropanol has dried, iron particles have a double coating of insulators, that is, containing the oxide layer and precursor to the glassy layer.
  • H 3 BO 3 dissolved boric acid
  • (a) Formation of the Oxide Layer - TIO 2 Iron particles, with an average particle size of 180pm, are immersed in an aqueous suspension containing commercial titanium oxide (T1O2) nanoparticles with a dispersion mass concentration of 0.16 % and average particle size equal to 20nm. Iron powder is added to this suspension in such a way that the concentration of ferromagnetic particles in the suspension is equal to 28.5%, equivalent to a molar concentration of 20mM. The mixture is kept under stirring, strong enough to keep the iron particles suspended, for the period of 1 hour.
  • T1O2 commercial titanium oxide
  • the iron particles covered with the insulating nanoparticles are separated from the rest of the suspension, washed with a mixture of ethanol and water, and finally dried in a vacuum oven at 80 ° C for 30 minutes. After drying, the iron particles are coated with a layer of titanium oxide nanoparticles.
  • a heated solution of isopropanol containing a mass concentration of 0.5% of dissolved boric acid (H3BO3) is prepared.
  • the iron powder, coated with T1O2 as an oxide layer, is then immersed in this solution so that the mass concentration of the ferromagnetic powder in this solution is 83.5%.
  • the powder is kept in contact with the solution until complete drying by evaporation of isopropanol.
  • the iron particles with double insulating coating that is, containing the oxide layer and precursor to the vitreous layer.
  • AI2O3 commercial aluminum oxide
  • the iron particles covered with the insulating nanoparticles are separated from the rest of the suspension, washed with a mixture of ethanol and water, and finally dried in an oven vacuum at 80 ° C for 30 minutes. After drying, the iron particles are coated with a layer of aluminum oxide nanoparticles.
  • a heated solution of isopropanol containing a mass concentration of 0.5% of dissolved boric acid (H3BO3) is prepared.
  • the iron powder, coated with AI2O3 as an oxide layer, is then immersed in this solution so that the mass concentration of the ferromagnetic powder in this solution is 83.5%.
  • the powder is kept in contact with the solution until complete drying by evaporation of isopropanol.
  • iron particles have a double coating of insulators, that is, containing the oxide layer and precursor to the glassy layer.
  • Samples in the form of toroid produced in examples 1 to 6 and comparative examples 1 and 2 have approximate dimensions of outside diameter, inside diameter and height respectively equal to 65, 55 and 5mm. These samples were measured on a bench for measuring magnetic properties MPG 200D manufactured by Brockhaus Messtechn ⁇ k and their results are shown in Table 1 and Table 2.
  • Table 1 Losses in maximum magnetic induction of 1T and maximum relative permeability at different frequencies of samples containing respectively double layer of insulators, only oxide layer (ZnO) and only vitreous layer (B2O3).
  • Table 2 Losses in maximum magnetic induction of 1T and maximum relative permeability at different frequencies of samples containing different combinations of oxide layer and vitreous layer.
  • the oxide layer it allows a significant improvement in the wetting of the vitreous layer on the ferromagnetic particle, in addition to this synergy between the layers leading to the self-healing mechanism of the cracks generated in the compaction stage, with the possibility of increasing the electrical resistivity during the heat treatment. It is important to note that for this phenomenon to occur as shown in the examples of this invention, both layers must be present and added in two stages as a way to ensure that from the surface of the ferromagnetic powder, the oxide layer is found first and then the layer glassy.
  • the properties achieved and demonstrated in the examples of this invention present the possibility of immediate use for several applications, especially with a focus on medium frequency.
  • optimizations for different conditions of use, especially in relation to the frequency of operation can be carried out through modifications of process parameters keeping the same molds claimed by the invention, such as example: size of ferromagnetic particles, control of particle size, composition and concentration of nanoparticles in suspension, composition of the liquid medium of the suspension, mixing time with the suspension, pH of the suspension, stirring speed, composition and glass phase concentration or precursors, in addition to process parameters such as lubricant quantity, compaction pressure, compaction temperature, as well as temperature and heat treatment time.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Power Engineering (AREA)
  • Soft Magnetic Materials (AREA)
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Abstract

La présente invention concerne un matériau particulaire pour l'obtention d'un composite magnétique doux (SMC), ce matériau comprenant des particules ferromagnétiques revêtues par au moins deux couches de recouvrement, soit au moins une couche de nanoparticules d'oxyde et au moins une couche vitreuse, lesdits couches de recouvrement permettant d'obtenir une continuité, une homogénéité et une adhésion améliorées des revêtements isolants sur les particules ferromagnétiques. La présente invention concerne également un procédé de production d'un matériau particulaire pour l'obtention d'un composite magnétique doux (SMC).
PCT/BR2020/050218 2019-06-19 2020-06-18 Matériau particulaire pour l'obtention d'un composite magnétique doux et procédé de production de matériau particulaire pour l'obtention d'un composite magnétique doux WO2020252551A1 (fr)

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BR102019012755A BR102019012755A8 (pt) 2019-06-19 2019-06-19 Material particulado para obtenção de compósito magnético mole e processo de produção de material particulado para a obtenção de compósito magnético mole

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024041930A1 (fr) 2022-08-24 2024-02-29 Höganäs Ab (Publ) Composition de poudre ferromagnétique et son procédé de production

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1852199A1 (fr) * 2005-01-25 2007-11-07 Mitsubishi Materials PMG Corporation Poudre de fer enrobee d'oxyde contenant du magnesium
US20080029300A1 (en) * 2006-08-07 2008-02-07 Kabushiki Kaisha Toshiba Insulating magnectic metal particles and method for manufacturing insulating magnetic material
KR20090033524A (ko) * 2007-10-01 2009-04-06 현대자동차주식회사 비자성 나노 알루미나 분말 절연층으로 코팅된 자성분말코어 제조 방법
US20130228716A1 (en) * 2011-08-31 2013-09-05 Kabushiki Kaisha Toshiba Magnetic material, method for producing magnetic material, and inductor element

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1852199A1 (fr) * 2005-01-25 2007-11-07 Mitsubishi Materials PMG Corporation Poudre de fer enrobee d'oxyde contenant du magnesium
US20080029300A1 (en) * 2006-08-07 2008-02-07 Kabushiki Kaisha Toshiba Insulating magnectic metal particles and method for manufacturing insulating magnetic material
KR20090033524A (ko) * 2007-10-01 2009-04-06 현대자동차주식회사 비자성 나노 알루미나 분말 절연층으로 코팅된 자성분말코어 제조 방법
US20130228716A1 (en) * 2011-08-31 2013-09-05 Kabushiki Kaisha Toshiba Magnetic material, method for producing magnetic material, and inductor element

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024041930A1 (fr) 2022-08-24 2024-02-29 Höganäs Ab (Publ) Composition de poudre ferromagnétique et son procédé de production

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