WO2020128126A1 - Aimant permanent, procédé d'obtention et utilisations - Google Patents

Aimant permanent, procédé d'obtention et utilisations Download PDF

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Publication number
WO2020128126A1
WO2020128126A1 PCT/ES2019/070848 ES2019070848W WO2020128126A1 WO 2020128126 A1 WO2020128126 A1 WO 2020128126A1 ES 2019070848 W ES2019070848 W ES 2019070848W WO 2020128126 A1 WO2020128126 A1 WO 2020128126A1
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Prior art keywords
soft magnetic
magnetic structure
permanent magnet
equal
magnetic
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English (en)
Spanish (es)
Inventor
Jesús Carlos GUZMÁN MINGUEZ
Luis MORENO ARCHE
Adrián QUESADA MICHELENA
José Francisco FERNÁNDEZ LOZANO
Federico MOMPEAN GARCÍA
Mar GARCÍA HERNÁNDEZ
Lucas PÉREZ
Sandra RUIZ GOMEZ
Dmitry BERKOV
Sergey EROHKIN
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General Numerics Research Lab EV
Consejo Superior de Investigaciones Cientificas CSIC
Universidad Complutense de Madrid
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General Numerics Research Lab EV
Consejo Superior de Investigaciones Cientificas CSIC
Universidad Complutense de Madrid
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Publication of WO2020128126A1 publication Critical patent/WO2020128126A1/fr
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • Permanent magnet, method of obtaining and uses The present invention relates to a permanent magnet comprising hard magnetic particles and a two-sided magnetic structure with an aspect ratio greater than or equal to 3 and with a monodomain magnetic structure. Furthermore, the present invention relates to the method of obtaining said magnet and the use of said magnet as part of a generator or a motor vehicle.
  • the present invention falls within the field of magnetic materials and their industrial applications.
  • Permanent magnets are crucial materials since they allow storing, supplying and converting electrical energy into mechanical and vice versa, so that better magnets lead to greater energy efficiency.
  • One way to reduce the rare earth content in permanent magnets without worsening or maintaining their magnetic properties is to combine a rare earth based hard magnetic material and a ferritic hard magnetic material of an oxidic nature as claimed by CN 106312077.
  • CN 105006325 discloses a method for preparing composite ferrite powder with an exchange coupling effect and single-phase magnetic behavior through milling between a soft magnetic phase of FeB and a hard magnetic phase of ferrite according to a mass ratio of 1 :one.
  • the exchange cupping effect can be realized without the need for high temperature sintering.
  • the resulting product does not exhibit a behavior like permanent magnet since it exhibits soft magnetic behavior with remaining magnetization values of less than 0.12 T.
  • CN1 Q1481241 refers to a method of preparing a nanocrystalline permanent magnet, characterized in that a nanocrystalline barium ferrite powder with hard magnetic behavior and a nanocrystalline nickel-copper-zinc ferrite powder with soft magnetic behavior are mixed, they are dried and thermally treated obtaining a complex nanocrystalline phase that has a saturation magnetization greater than 0.3 T, and a coercive field between 0.5 and 0.8 T; similar in terms of saturation magnetization to those obtained for the nanocrystalline powder of barium ferrite.
  • WG201713764QA1 claims hybrid permanent magnet micro-composites comprising an oxide-based ferrite hard magnetic material, a metal-based soft magnetic material and an organic coupling agent.
  • the micro-composite shows improvements of 25% in the remanence magnetization with respect to the ferrite phase, of isotropic powders without magnetic orientation.
  • the presence of a coupling agent is required to protect the soft magnetic material that has particles with sizes greater than 200 nm from oxidation.
  • the material in WO2017137640A1 is an isotropic powder that exhibits an improvement in remanence over an isotropic ferrite powder; however, the invention of WO2017137640A1 does not cover the case of anisotropic materials (i.e. magnetically oriented).
  • anisotropic materials i.e. magnetically oriented
  • the present invention relates to a permanent magnet (hereafter “the magnet of the invention”), characterized in that it comprises
  • weight percentage of the soft magnetic structure is between 1% and 40% with respect to the final weight of the magnet
  • hard magnetic nanostructure is understood in the present invention as that particle of size between 100 nm and 100 p that has a coercive field greater than 240 kA.nr 1 and saturation magnetization less than 525 kA.rrr 1 .
  • soft magnetic nanostructure is understood as that structure with an aspect ratio greater than or equal to 5 that has a saturation magnetization greater than 700 kA.rrr 1 .
  • magnetic anisotropy is meant the non-homogeneity of the magnetic properties when measured in different directions in space. A material will be magnetically harder the greater its total magnetic anisotropy.
  • magnetrocrisialin anisotropy is meant the non-homogeneity of the magnetic properties along specific axes of the crystal structure.
  • shape anisotropy is meant the magnetic response as a consequence of the geometric shape of the material or the particles that constitute it.
  • the soft magnetic structure is characterized by having an aspect ratio greater than or equal to 3, more particularly greater than or equal to 5.
  • An aspect ratio greater than or equal to 5 of the soft magnetic structure results in a high remanence magnetization and a monodomain structure as a consequence of its shape anisotropy.
  • the aspect ratio of the soft magnetic structure is of special relevance to the formation of the permanent magnet of the present invention.
  • the physical mechanism that is at the origin of this response, and without being limiting it, is as follows: the system seeks to minimize the accumulation of magnetic poles and their magnetization is aligned with the longitudinal axis of the particle. The alignment of the magnet with the longitudinal axis of the soft magnetic structure of the present invention is maximized above a certain aspect ratio.
  • Electromagnetic simulation calculations establish that for a diameter / gauge of 30 nm and an aspect ratio greater than 3, 83% of spins aligned in the longitudinal direction of the anisotropic soft magnetic structure are reached.
  • the nanowire has an aspect ratio greater than or equal to 5, it reaches its optimal monodomain state, that is, all its magnetization is oriented in the same direction.
  • the soft magnetic structure is a wire with a length of between 150 nm and 60 pm and a gauge of less than or equal to 100 nm, preferably less than 50 nm.
  • the soft magnetic structure is passivated with an amorphous surface oxide layer with monodomain structure and thickness less than 10 nm.
  • the surface oxide coating or layer of the soft magnetic structure is an oxide with a thickness of less than or equal to 10 nm, preferably less than or equal to 7 nm and with special preference less than or equal to 5 nm.
  • the oxide layer is generated during the manufacturing process by exposing the soft metallic structure of magnetically soft material to a controlled air atmosphere during the drying process of the solvents used in the removal of the washing chemicals of said materials. Said oxide layer acts as a coating that protects the metallic material from complete oxidation.
  • the oxide layer of the coating is characterized by the absence of long-range crystalline order, thus constituting an amorphous oxide layer. Furthermore, the oxide layer of the coating, in addition to protecting it from subsequent oxidation, produces a surprising effect that is related to the reduction of the effective diameter of the soft magnetic structure, which contributes to stabilizing the mono-domain state of the soft magnetic structure.
  • Nanowires When the soft magnetic structure is a wire with a length of between 150 nm and 60 p and a gauge less than or equal to 100 nm, that is, as a nanowire, these nanowires are kept in a single-domain state and increase the remanence magnetization value of hard magnetic particles. Nanowires are characterized by presenting an oxide layer as a coating that appears during the partial oxidation of the surface when exposed to air after the membrane dissolution processes where they have grown. The oxide layer of the nanowire coating protects them from complete oxidation and increases the effective aspect ratio of the magnet by reducing the magnetic diameter of the metal phase inside.
  • step (b) drying the magnetic structure obtained in step (b) at a temperature between 30 ° C and 120 ° C and in the presence of an air atmosphere
  • step (d) mixing with ultrasound of the soft magnetic structure obtained in step (c) with the hard magnetic particles in a liquid ethane medium until obtaining a homogeneous mixture, and e) drying and compacting of! product obtained in step (d) in the presence of a magnet of between 0.2 T and 1.25 T and under a pressure of between 150 Kg / cm 2 and 1500 Kg / cm 2 .
  • the procedure uses a porous support as a standard element for e! Growth of soft magnetic phase nanowires.
  • the porous support consists of a membrane that has transverse pores where each of the pores has a diameter of between 10 nm and 300 nm, a pore length greater than or equal to 100 pm and a pore density of between 10 5 to 10 10 pores per cm 2 .
  • the material that is used for the porous membrane is polymer based, for example, polycarbonate, polyester, polystyrene, polystyrene-glyceryl polymethacrylate or polyvinylidene fluoride; or an oxide, such as a porous aluminum oxide membrane.
  • the porous membrane used for the growth of the nanowire-shaped soft magnetic structure is an etched nanoporous polycarbonate membrane.
  • the selected membrane is electroded on one of its faces with a metallic layer, preferably Au, using the thermal evaporation deposition technique.
  • a metallic layer preferably Au
  • an Au electrode with a thickness of 100 nm was preferably deposited.
  • the electrodeposition of the soft magnetic structure is carried out using an aqueous solution of boric acid, where the sulfate salts corresponding to the metal cations of the corresponding compositions are diluted.
  • the concentration of metal cation saies in the aqueous boric acid solution is between 0.04M and 0.3M.
  • the aqueous boric acid solution contains a 0.09M concentration of C0SO 4 and 0.1M FeS0 4 and is at a pH of 2.7.
  • step a) the growth of the soft magnetic structure is carried out by electrochemical deposition applying a voltage for a time determined by the pore density of the porous membrane and the diameter of the same.
  • a voltage for a time determined by the pore density of the porous membrane and the diameter of the same.
  • a voltage of -1, 1 V applied between 100 s and 3000 s. using a porous membrane 25 mm in diameter and 6 pm thick that has transverse pores, with a pore density of 6-10 ® pores / cm 2 , with a nominal pore diameter of 30 nm of pore and area! 50nm.
  • step b) of the process of the present invention the porous membrane is removed by dissolution. It is a chemical attack to remove the contact electrode and the membrane, keeping the magnetic structure soft.
  • the chemical attack of the membrane contact electrode is carried out by iodide solutions, for example, molecular iodine and potassium iodide.
  • the chemical attack of the Au layer that acts as a contact electrode of the membrane is carried out by washing with an aqueous solution of 25 g / l of diiode and 100 g / l of KL
  • the chemical attack of the membrane is carried out by means of a washing routine in different solvents in order to obtain the soft magnetic structure free of residues from said membrane.
  • Solvents for removing polymer-based membranes are common solvents for such polymers, such as toluene, xylene, ethyl acetate, ethyl acetate, dichloromethane, chloroform, acetone, alcohol, perchioroethylene, methyl chloride, tetrahydrofuran, dimethylformamide, diethyl ether and acid. formic.
  • the membrane dissolution strategy combines sequential washing in different solvents and the use of sonication processes by ultrasound and centrifugation at each stage to obtain the soft magnetic structure.
  • the chemical attack to remove the membrane and the contact electrode is carried out by means of the following cleaning routine that comprises the following steps:
  • step (c) of! procedure the drying of the soft magnetic structure obtained in step (b) is carried out by means of a heat treatment in an oven at a temperature between 30 ° C and 120 ° C and in the presence of an air atmosphere.
  • step (c) controlled oxidation (passivation) of the surface of the soft magnetic structure occurs.
  • drying of step (c) is carried out in an oven at 60 ° C for 1 hour in an air atmosphere.
  • the product resulting from step c) is a powdery material corresponding to the passivated soft magnetic structure.
  • step (d) of the process of the present invention the soft magnetic structure obtained in step (d) is homogeneously mixed, with the help of ultrasound, with the hard magnetic particles in a liquid medium.
  • compositions are carried out by usual means in a semi-liquid medium or in a liquid medium.
  • semi-liquid mixture is meant in the present invention a mixture such as that described in the permanent magnet that has a percentage of solvent in the composition so that the product does not behave as a paste or as a solid without presenting the characteristic behavior of a liquid or suspension.
  • the liquid medium used corresponds to a solvent selected from water, alcohol, acetone, hydrocarbon or a mixture of various solvents.
  • An example of mixing in "liquid medium” corresponds to a suspension of the mixture at 20% by weight in ethanol and mechanical stirring by means of a propeller stirrer rotating at 150 rpm for 10 minutes and with sonication by ultrasound.
  • Step (e) of the process of the present invention refers to the drying and compaction of the product obtained in step (d) in the presence of a magnet of between 0.20 T and 1.25 T and under a pressure of between 150 Kg / cm 2 and 1500 Kg / cm 2
  • the drying of stage (e) is carried out by heat treatment in an oven at a temperature between 30 ° C and 120 ° C and in the presence of a selected atmosphere of air.
  • the drying carried out in step (d) can be complete or partial.
  • a product that maintains a weight percentage of water between 3% and 8% is called a “partially dry product”.
  • the advantage of the partially dry product is that it favors the subsequent shaping process by pressing in the presence of a magnetic field such as that generated by a magnet of between 0.2 T and 1.25 T and under pressure of between 150 Kg / cm 2 and 1500 Kg / cm 2
  • the process of forming under pressure in the presence of a magnetic field allows the magnetic orientation of the particles of the mixture, maximizing the magnetic anisotropy of the compact.
  • the presence of a semi-liquid mixture (partially dry product) favors both the compaction and the orientation of the particles within the magnetic field when the liquid medium acts as a lubricant.
  • a completely dry product is defined as a product that contains an amount of solvent less than 0.5% by weight with respect to the product obtained in step (d)
  • the compaction process of the partially or completely dry product is carried out by injection molding using thermoplastic material and working at the usual injection temperature for said thermoplastic.
  • the polymer used for the injection molding process is a polyamide type polymer.
  • Magnetization of the product obtained in step (d) can be carried out by applying a stationary magnetic field with an electromagnet or with coils fed with an alternating current source.
  • a third aspect of the invention relates to the use of the permanent magnet of the present invention as part of a generator.
  • generators are an electric turbine generator, a flywheel, and a wave generator.
  • Another aspect of the invention relates to the use of the permanent magnet of the present invention as as part of a motor vehicle, specifically as part of a hybrid or electric motor, as part of the electric window system, as part of the power steering system.
  • FIG. 1 Transmission electron microscopy images of a FeCo nanowire of 100 nm in diameter / gauge and> 800 nm in length covered by an oxide layer of thickness between 4-10 nm.
  • FIG. 2 Thermogravimetric analysis (TGA) of 30 nm diameter / gauge FeCo nanowires carried out in air at a temperature between room temperature and 900 ° C.
  • FIG. 4 Magnesium curves versus applied field of the hard magnetic particles of ferrite (1), of the soft magnetic nanowires (2), and of the magnet I6 which comprises 80% of hard magnetic particles of ferrite and 40% by weight of nanowires soft magnetic (3).
  • FIG. 5 Magnetization curve against an applied field of an I8 magnet comprising 80% by weight of hard magnetic strontium ferrite particles and 20% by weight of spherical Fe nanoparticles with a diameter of 25 nm.
  • FIG. 7a Simulated data of the evolution of the coercive field with the length of a cylindrical nanowire of 30 nm in diameter.
  • FIG. 7b Simulated data of the evolution of the remanence to saturation ratio (Mr / Ms) with the length of a cylindrical nanowire of 30 nm in diameter.
  • FeCo nanowires with diameters of 30, 50 and 100 nm, were grown by electrodeposition within the pores of a polycarbonate membrane on which an Au electrode had grown on one side. 3 different pore sizes were used: 30, 50 and 100 nm. All the membranes used were 6 prn high.
  • both the membrane and the Au electrode were dissolved to obtain the nanowires in powder form.
  • the membrane dissolution method was performed following a cleaning routine that used dichloromethane, acetone, ethanoi, and aqueous solutions of iodides as solvents. It was necessary to repeat the dissolution process several consecutive times, on the order of 5, in order to completely remove the membrane. Subsequently, an oven drying step was carried out at a temperature of 60 ° C for 1 hour in an air atmosphere, generating an oxide layer of approximately 5 nm that covers the nanowires.
  • the electrodeposition conditions used were:
  • a 25 mm diameter membrane with a pore density of 6-10 8 pores / cm 2 , with a nominal pore size of 30 nm and a real pore of 50 nm.
  • the cleaning routine consists of: • Elimination of Au with an aqueous solution of 25 g / l of and 100 g / i of Kl. 4 washes of 2 ml of dichloromethane.
  • Each wash is sonicated for one minute in a device labeled "ultrasons sonicator" with a power of 50 W for 60 Hz and centrifuged for 1 min at 7000 rpm.
  • Figure 1 shows a transmission electron microscopy image of a FeCo nanowire of 30 nm in diameter / gauge and> 800 nm in length, showing the existence of the oxide coating of the nanowire with a thickness of between 4 nm and 10nm.
  • the oxide layer corresponds to the lightest part near its edge and is characterized by not having a crystalline order, being amorphous.
  • the central metal part is dark and features characteristic crystal clear pianos.
  • This coating acts as a protective layer and prevents complete oxidation of the nanostructure.
  • FIG. 2 shows a thermogravimetric analysis (TGA) of 30 nm diameter / gauge FeCo nanowires carried out in air between room temperature and 900 ° C, in which the oxidation process thereof is observed.
  • TGA thermogravimetric analysis
  • the oxide coating reduces the effective diameter of the nanowire, helping to stabilize a remanent mono-domain magnetic state (see example 2 for more details). Stabilization of the mono-domain state after the nanowires have been magnetized parallel to their long axis entails a remanence magnetization value of between 60-100% of the saturation magnetization value, since the magnetization of the wire remains mostly aligned with its axis in the absence of an external magnetic field.
  • the magnetic remanence values corresponding to the nanowires have been determined according to their diameter (Table 1), concluding that they are necessary diameters less than 50 nm to stabilize the mono-domain state.
  • Table 1 The 30 nm nanowires, with their oxide coating of approximately 5 nm, had the best properties in containing the highest fraction of mono-domain threads of all the samples studied.
  • Figure 3 presents the curve of magnetization versus applied field of the FeCo threads of 30 nm, in which a high ratio of remanence magnetization (Mr) to saturation magnetization (Ms) can be observed, which has the consequence that the nanowires they have a remanence of 102 Am-kg 1 , measured on a vibrating sample magnetometer (VSM).
  • VSM vibrating sample magnetometer
  • Example 2 Magnets comprising FeCo soft magnetic nanowires This example demonstrates the improvement in magnetic performance, relative to the best commercial hard ferrites, of the biphasic compounds corresponding to the magnet of the present invention.
  • Magnets were made with a composition of 60% by weight of hard magnetic strontium ferrite particles (SrFe ⁇ Gig) and 40% by weight of soft FeCo magnetic nanowires, 30 nm in diameter, obtained according to Example 1.
  • the two materials in powder form were mixed in the presence of ethanol.
  • the mixture is sonicated for one minute in an "ultrasons sonicator" equipment with a power of 50 W for 60 Hz and centrifuged for 1 min at 7000 rpm.
  • a 0.2 T magnetic field was applied during drying, also, after drying, the material was aligned by using a 0.3 T magnetic field and compacted applying a pressure of 400 Kg.crrr 2 housed in the inside a gelatin capsule using a spatula and a piece of cotton.
  • Table 2 shows the properties of the different magnets of the invention manufactured
  • Figure 4 clearly shows the increase in the remanence magnetization of both the magnet of the invention and the FeCo soft magnetic nanowires which is 87 Am 2 .kg ⁇ 1 for a generated field of 0.68 T, greater than magnetization of hard magnetic particles of commercial ferrite. It should be noted that the best commercial ferrites generate 0.45 T fields.
  • the coercive field of the magnet of the invention is 1047 Oe.
  • Comparative data magnet comprising Fe metallic spherical soft magnetic particles
  • Example 3 presents a Magnet composed of hard magnetic particles of ferrite (80% by weight) and soft magnetic particles in the form of spherical nanoparticles of Fe with an average diameter of 25 nm (20% by weight).
  • Figure 5 shows the magnetization curves of the magnet.
  • Table 4 shows the properties of the different magnets of the invention manufactured
  • the remanence magnetization for the ferrite was 63 Am 2 kg 1 while the magnet has a remanence magnetization of magnets 17-112 was a maximum of 55 Am 2 .kg ⁇ 1 .
  • the remanence magnetization values and the remanence / saturation ratio are clearly lower than the values obtained for the magnets 11-16 of the present invention, which comprise soft magnetic nanowires, especially in the case of the 30nm nanowires that are in monodomain status.
  • An advantageous aspect of the present invention results in that the mechanism involved in obtaining the permanent magnet of the present invention allows to solve the negative effect that agglomerates of anisotropic particles of material present Metallic with soft magnetic response in enhancing magnetic energy products.
  • the agglomerates of soft magnetic particles constitute in themselves a muitidomain system and the difficulty in the dispersion of said particles prevents the effective coupling from taking place between the particles corresponding to the hard and soft magnetic phases.
  • magnetically soft particles with an aspect ratio sufficient to preserve their magnetic monodomain status are used.
  • the oxide layer of the nanofilm coating in addition to limiting the oxidation degradation processes of said particles, is also beneficial for modifying the surface charge state of the nanowires.
  • Said surface modification results in an alteration of the short-range forces on the surface that are responsible for the accumulation of surface charge.
  • the amorphous nature of the oxide layer of the coating is likewise beneficial, since the absence of crystalline order minimizes the energy of surface dipole interactions by reducing the agglomeration of the soft magnetic particles of the present invention.
  • Comparative data Commutational simulation of the aspect ratio that stabilizes the magnetic mono-domain state in e! magnet
  • the minimum aspect ratio value is established that stabilizes the nano-magnetic magnetic domain state of the nanobilos, by means of micromagnetic simulations of their domain structure.
  • R aspect ratio
  • Figure 7 shows the evolution of the coercive field (H c ) and the ratio of remanence to saturation (M r / M s ) with the length of the wire, for a nanohyo of 30 nm in diameter.
  • the transition to the multidomain state occurs by increasing the diameter or caliber of the nanowires, that is, by reducing the aspect ratio.
  • soft anisotropic or nanowire magnetic structures there is a competition between magnetocrystalline anisotropy, which favors the alignment of magnetization along a preferred crystallographic axis, and anisotropy in a way that aims to avoid the accumulation of magnetic poles.
  • shape anisotropy, K s is:
  • N d 1 ⁇ 2.
  • M s the saturation magnetization of the material and N d is its deterrent factor.
  • the deterrent factor of a nanowire is defined as
  • N 1 / (2n + 1) where n is the aspect ratio.
  • Example 3 Manufacture of FeCo soft magnetic nanowires using an aluminum substrate.
  • FeCo nanowires were grown by electrodeposition of the soft magnetic structure in the presence of a porous alumina porous membrane.
  • the porous membrane is obtained in a previous stage from aluminum sheets (A! 1050 99.5% purity in aluminum) that were subjected to a cleaning process in a solution of perchloric acid and ethanol with a ratio of 1: 3, and electropolished under a constant voltage of 20 V for 4 minutes at a temperature of 4 ° C
  • the electro-polished aluminum sheets were anodized in a two-electrode electrochemical cell using platinum cathodes.
  • the pore diameter depends on both the voltage and the electrolyte used. Using a voltage of 40 V and an electrolyte of oxalic acid 0.30 M. As a result, porous membranes of aluminum oxide with pore diameters of 50 nm were obtained.
  • the residual aluminum was removed from the sheet by chemical etching using a solution of copper (II) chloride dihydrate (CUCI2 2H2O) and hydrochloric acid (HCI) in a 1: 4 ratio.
  • the barrier aluminum oxide layer at the bottom of the pores was removed using phosphoric acid to open the pore. In this way, a porous aluminum oxide membrane with pores of between 40 nm - 60 nm, length of 50 pm - 200 pm and a pore density of 1x10 10 pores / cm 2 was obtained .
  • porous aluminum oxide membranes thus prepared were metallized on one side using thermal gold evaporation.
  • porous membranes of metallized alumina oxide on one of its faces were subjected to a FeCo alloy electrodeposition process similar to that described in Example 1. Once the nano-ohium had been deposited, the alumina membrane was removed using a solution CuCEy HCI (1: 4 ratio).

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Abstract

La présente invention concerne un aimant permanent qui comprend des particules magnétiques dures et une structure magnétique souple à rapport d'aspect supérieur ou égal à 3 et à structure magnétique monodomaine. En outre, la présente invention concerne le procédé d'obtention de cet aimant et son utilisation comme partie d'un générateur ou d'un véhicule automobile. La présente invention concerne le secteur des matériaux magnétiques et ses applications industrielles.
PCT/ES2019/070848 2018-12-20 2019-12-16 Aimant permanent, procédé d'obtention et utilisations Ceased WO2020128126A1 (fr)

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ES201831258A ES2768433B2 (es) 2018-12-20 2018-12-20 Imán permanente, procedimiento de obtención y usos
ESP201831258 2018-12-20

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Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
COJOCARU, P. ET AL.: "Nanowires of NiCo/barium ferrite magnetic composite by electrodeposition", MATERIALS LETTERS, vol. 65, 23 May 2011 (2011-05-23), pages 2765 - 2768, XP028237402, ISSN: 0167-577X, DOI: 10.1016/j.matlet.2011.05.085 *
GORBACHEV, E.A. ET AL.: "Synthesis and magnetic properties of the exchange-coupled SrFe10.7A11.3O19/Co composite", MENDELEEV COMMUNICATIONS, vol. 28, 8 July 2018 (2018-07-08), pages 401 - 403, XP085438024, ISSN: 0959-9436, DOI: 10.1016/j.mencom.2018.07.020 *
KHAMENEH, K. ET AL.: "Surfactant-Assisted Electrodeposition of CoFe-Barium Hexaferrite Nanocomposite Thin Films", JOURNAL OF ULTRAFINE GRAINED AND NANOSTRUCTURED MATERIALS, vol. 47, 2014, pages 51 - 56, XP085438024 *
YANG, X. ET AL.: "Magnetic properties and BSA adsorption of nano-Fe-embedded BaFeO porous microfibers via organic gel-thermal selective reduction process", JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY, vol. 63, 3 April 2012 (2012-04-03), pages 8 - 15, XP035076203, ISSN: 1573-4846, DOI: 10.1007/s10971-012-2755-1 *

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