WO2022160433A1

WO2022160433A1 - Febp amorphous soft magnetic powder and preparation method for magnetic powder core thereof

Info

Publication number: WO2022160433A1
Application number: PCT/CN2021/082236
Authority: WO
Inventors: 李旺昌; 肖世鹏; 车声雷; 余靓; 郑精武; 乔梁; 应耀
Original assignee: 浙江工业大学
Priority date: 2021-02-01
Filing date: 2021-03-23
Publication date: 2022-08-04
Also published as: CN112958779A

Abstract

Disclosed are an FeBP amorphous soft magnetic powder and a preparation method for a magnetic powder core thereof. The powder is prepared on the basis of a chemical precipitation method, which preparation comprises: fully dissolving ferrous chloride, ammonium chloride, citric acid and sodium hydrogen hypophosphite, then adding sodium hydroxide, dropwise adding an NaBH4 solution after reaction, and separating, washing and drying the reaction product to obtain the FeBP amorphous soft magnetic powder, wherein the particle size of the FeBP amorphous soft magnetic particles is 100 nanometers to 2 micrometers. After the powder is subjected to insulation coating, same is uniformly mixed with an adhesive, and mould pressed and then annealed to form the magnetic powder core. The powder particles prepared by the method of the present invention are more uniform and finer, and have a higher specific surface area and resistivity; and a magnetic material device prepared therefrom has a lower loss and can be applied in a higher frequency range. In addition, the method is simple in terms of process, convenient in terms of operation, low cost, and suitable for large-scale industrial production.

Description

A kind of FeBP amorphous soft magnetic powder and preparation method of magnetic powder core

technical field

The invention relates to a preparation method of amorphous soft magnetic powder and a molding method thereof, in particular to a chemical reduction precipitation method, which uses a strong reducing agent to reduce metal ions in an aqueous metal salt solution to obtain ultra-fine amorphous precipitates , The method of obtaining FeBP amorphous particles after repeated washing and vacuum drying, and then the prepared amorphous particles are pressed into magnetic powder cores in a certain way, which are used in many electronic power equipment and components, such as filters, replacement sensors, new magnetic sensors and drivers, integrated inductors.

Background technique

Amorphous alloys, also known as amorphous alloys, have different microstructures from general crystalline metals and are thermodynamically unstable or metastable, thus showing unique physical and chemical properties: atoms are topologically free in three-dimensional space. It is arranged in order state, and there are no defects such as grain boundaries, dislocations and segregation that usually exist in crystalline alloys; the constituent elements are connected by metal bonds and exist in the range of several lattice constants, maintaining short-range order, forming a similar on the structure of atomic clusters. Compared with crystalline alloys of the same or similar composition, amorphous alloys often have excellent mechanical properties, chemical properties and electromagnetic properties, and have been used in powder metallurgy, magnetic recording materials, ferrofluids, composite materials and catalysts. . With the development of high power, high frequency and low power consumption, due to the advantages of low high frequency loss and high magnetic permeability of amorphous alloys, it provides ideal materials that meet the requirements. drive has been widely used. In the amorphous alloy material system, Fe, Ni and Co bases are the most mature types at present. In addition, due to its abundant natural resources, low material cost, high magnetic permeability (μ _e ) and saturation magnetic flux density (B _s ), and low magnetic core loss, iron-based amorphous alloys have become the most Competitive candidate material. Amorphous alloys can be prepared by various techniques, including liquid quenching, mechanical alloying, vapor deposition, and chemical alloying, among others. Among them, chemical alloying technology is considered as a new method. In this method, ultra-fine amorphous particles can be produced by reducing metal salts with various reducing agents. Compared with traditional methods such as smelting and stripping, spraying, etc., the process is simpler, the operation is convenient, and the cost is low. It is suitable for industrial applications. mass production. With the rise of new fields such as 5G communication, intelligent applications, Internet of Things, and intelligent manufacturing in recent years, electronic systems have developed in the direction of high integration, high frequency and broadband, and various electronic components have been proposed to miniaturize and thin film. development requirements. In order to develop amorphous soft magnetic materials with higher energy efficiency, smaller size and lighter weight, the development of new amorphous soft magnetic composite materials has become a current hotspot, sometimes called "insulation-coated amorphous powder". A new type of amorphous iron-based soft magnetic composite (SMC) was developed. The design idea of this material is to combine the amorphous iron-based powder with high saturation magnetic induction intensity and the insulating coating with high resistivity to give full play to the advantages of both.

There are many types of insulating cladding layers of SMC materials, but organic polymers and inorganic _oxides are the main ones. However, these materials have their own advantages and disadvantages, and are used in different environments. At present, there are not many research and scientific papers and patents on such materials at home and abroad, so there are still many unsolved problems and potentials to be explored, and there are broad development and research prospects.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a FeBP amorphous soft magnetic powder with good dispersibility, complete and uniform particles and a preparation method for the magnetic powder core thereof. The preparation method of the powder mainly uses a strong reducing agent to reduce the metal ions in the metal salt solution to Ultra-fine amorphous soft magnetic particles are obtained, and uniform nano-scale amorphous particles below 2 microns are obtained after repeated washing and vacuum drying; the soft magnetic powder is usually insulated and coated, and then resin is used as a binder. It is uniformly mixed with the powder, molded and then annealed at a certain temperature to obtain an amorphous soft magnetic powder core.

The technical scheme adopted in the present invention is:

A preparation method of FeBP amorphous soft magnetic powder, wherein the FeBP amorphous soft magnetic particles in the powder have a particle size between 100 nanometers and 2 micrometers, and are mainly prepared on the basis of chemical precipitation method. Specific preparation methods include:

Fully dissolve a certain amount of ferrous chloride, ammonium chloride, citric acid and sodium hypophosphite; then add a certain amount of sodium hydroxide to the solution, and the reaction solution changes from a clear light green solution to a dark green turbid liquid ; Add NaBH ₄ solution dropwise under the action of magnetic stirring, the reaction solution gradually changes from dark green turbid liquid to light gray-white turbid liquid, in addition, a small amount of nucleating agent can be added during the reaction process to improve the yield, such as: silver nitrate, chloroplatinum Sodium, etc. The reaction product is separated out, washed with distilled water and absolute ethanol for several times, and finally dried in a vacuum drying box to obtain FeBP amorphous soft magnetic powder.

Further, the molar ratio of ferrous chloride, ammonium chloride, citric acid and sodium hypophosphite is 1:0.5-4.5:0.1-2.5:0.5-2.5;

Further, the molar concentration of the sodium hydroxide is 1.2 to 6 times the molar concentration of ferrous ions;

Further, the molar ratio of the dripped sodium borohydride to ferrous chloride is 1:0.5-4;

Further, the added amount of the nucleating agent is no more than 0.02 mol% of the content of ferrous chloride.

The powder obtained above is pressed into a ring by the following method. First, the obtained soft magnetic powder is insulated and coated, and then resin is added as a binder and placed in a mold. annealing.

Further, the insulating coating can be stober coating, phosphating coating, silane coating or sodium silicate coating, and the materials used are silicon dioxide, silicone resin, sodium silicate, Magnesium oxide, or titanium oxide, etc.;

Further, the binder may be one or more of epoxy resin, silicone resin, acrylic resin and cyanate resin. The molding pressure during pressing is 1000-2500MPa.

Compared with the prior art, the beneficial effects of the present invention are mainly reflected in: (1) the present invention adopts the amorphous powder prepared by the chemical reduction method, compared with the traditional water atomization process, gas atomization process and rapid cooling stripping. The method of preparing amorphous powder or amorphous strip has the advantages of simple process, convenient operation, low cost and the like, and is suitable for large-scale industrial production. (2) The particle size of the powder prepared by the method of the present invention is 100 nanometers to 2 microns, and the particle size of the amorphous powder prepared by the industrial atomization method is usually above 3 microns. The method disclosed in the invention is more stable than the conventional atomization method commonly used in the industry, and the particles are more uniform and fine, so the powder has higher specific surface area and resistivity, and the magnetic material device made of the powder has lower loss, can be used in higher frequency range. (3) Since the particle size of the magnetic powder is too small and difficult to form, the general press forming process is not suitable, which easily leads to cracking of the magnetic ring. The press forming process of the present invention solves the problem that the fine powder is difficult to press and form.

Description of drawings

FIG. 1 is the SEM images of amorphous nanoparticles prepared by chemical reduction method in the present invention under 5k(a) and 10k(b) magnifications.

Figure 2 is a graph of the complex permeability of a magnetic ring made in the frequency range of 1MHz to 1GHz.

FIG. 3 is a graph of the tangent value of the permeability loss angle of the magnetic ring made in the frequency range of 1MHz to 1GHz.

Detailed ways

The present invention is further described below in conjunction with specific embodiment, but the protection scope of the present invention is not limited to this:

Example 1

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 0.6mol NH ₄ Cl, 0.2mol C ₆ H ₈ O ₇ ·H ₂ O and 0.6mol NaH ₂ PO ₂ ·H ₂ O respectively and add them to the three-necked flask, and then add 1000mL Distilled water, stir magnetically evenly; then add 800mL 3mol/L sodium hydroxide solution; then add 15g NaBH ₄ solution dropwise to the reaction solution. The obtained product is separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility.

10 g of the prepared amorphous powder was dispersed in 100 mL of distilled water, then 2.5 mL of ammonia water and 5 mL of TEOS were added dropwise to the solution, and stirred for 10 h, then the powder was separated, washed three times, and then dried. Then weigh 1.5 g of the coated powder, add 1 wt % epoxy resin as a binder, press it into a ring at 1000 MPa, and finally perform annealing treatment at 500 °C for 1 h. In the RF impedance analyzer, the highest real permeability in the frequency range of 1MHz-2.5GHz is about 8.2, and the permeability loss tangent angle in the frequency range of 1MHz-200MHz is lower than about 0.07;

Example 2

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 0.2mol NH ₄ Cl, 1mol C ₆ H ₈ O ₇ ·H ₂ O and 1mol NaH ₂ PO ₂ ·H ₂ O respectively and add them to the three-necked flask, then add 1000mL distilled water, Magnetic stirring was uniform; then 400 mL of 4mol/L sodium hydroxide solution was added; then 15 g of NaBH ₄ solution was added dropwise to the reaction solution. The obtained product is separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility.

10 g of the prepared amorphous powder was coated with 1 wt % sodium silicate, and then distilled water was added for dilution, ultrasonication, stirring and drying. Weigh 1.5g of the coated powder, add 2wt% epoxy resin as a binder, press it into a ring at 2500MPa, and finally anneal at 450℃ for 1h. In the RF impedance analyzer, the highest real permeability in the frequency range of 1MHz-2.5GHz is about 9.2, and the permeability loss tangent angle in the frequency range of 1MHz-200MHz is lower than about 0.09;

Example 3

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 1mol NH ₄ Cl, 0.1mol C ₆ H ₈ O ₇ ·H ₂ O and 0.5mol NaH ₂ PO ₂ ·H ₂ O respectively and add them to the three-necked flask, and then add 1000mL distilled water , magnetic stirring uniformly; then add 400mL 3mol/L sodium hydroxide solution; then add 15g NaBH ₄ solution dropwise to the reaction solution. The obtained product is separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility.

10 g of the prepared amorphous powder was coated with 1 wt % phosphating solution, and then distilled water was added for dilution, ultrasonication, stirring and drying. Weigh 1.5g of the coated powder, add 3wt% epoxy resin as a binder, press it into a ring at 1500MPa, and finally perform annealing treatment at 300℃ for 1h. In the RF impedance analyzer, the highest real permeability in the frequency range of 1MHz-2.5GHz is about 6.2, and the permeability loss tangent angle in the frequency range of 1MHz-300MHz is lower than about 0.06;

Example 4

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 0.5mol NH ₄ Cl, 0.5mol C ₆ H ₈ O ₇ · H ₂ O and 0.5mol NaH ₂ PO ₂ ·H ₂ O respectively and add them to the three-necked flask, and then add 1400mL Distilled water, stir magnetically evenly; then add 400 mL of 2mol/L sodium hydroxide solution; then add 15 g of NaBH ₄ solution dropwise to the reaction solution. The obtained product is separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility.

10 g of the prepared amorphous powder was coated with 1 wt % silane, and then distilled water was added for dilution, ultrasonication, stirring and drying. Weigh 1.5 g of the coated powder, add 1 wt% epoxy monomer as a binder, press it into a ring at 2000 MPa, and finally perform annealing treatment at 300 °C for 1 h. In the RF impedance analyzer, the highest real permeability is about 7.6 in the frequency range of 1MHz-2.5GHz, and the permeability loss tangent angle in the frequency range of 1MHz-500MHz is lower than about 0.1;

Example 5

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 0.6mol NH ₄ Cl, 1mol C ₆ H ₈ O ₇ ·H ₂ O and 0.5mol NaH ₂ PO ₂ ·H ₂ O and add them to the three-necked flask, and then add 1100mL distilled water , magnetic stirring uniformly; then add 400mL 2mol/L sodium hydroxide solution; then add 15g NaBH ₄ solution dropwise to the reaction solution. The obtained product is separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility.

10 g of the prepared amorphous powder was coated with 1 wt % phosphating solution, and then distilled water was added for dilution, ultrasonication, stirring and drying. 1.5g of the coated powder was weighed and added with 1wt% acrylic resin as a binder, pressed into a ring under the condition of 1000MPa, and finally annealed at 200℃ for 1h. In the RF impedance analyzer, the highest real permeability in the frequency range of 1MHz-2.5GHz is about 8.6, and the permeability loss tangent angle in the frequency range of 1MHz-600MHz is lower than about 0.09;

Example 6

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 0.5mol NH ₄ Cl, 0.6mol C ₆ H ₈ O ₇ ·H ₂ O and 0.3mol NaH ₂ PO ₂ ·H ₂ O respectively into the three-necked flask, and then add 1200mL Distilled water, stir magnetically evenly; then add 400 mL of 3.5 mol/L sodium hydroxide solution; then add 15 g of NaBH ₄ solution dropwise to the reaction solution. The obtained product is separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility.

Disperse 10 g of the prepared amorphous powder in 100 mL of distilled water and 300 mL of absolute ethanol, and add 0.4 g of KH550, then dropwise add 2 mL of ammonia water and 4 mL of TEOS to the solution, and stir for 5 hours, then separate the powder and wash it three times Dry again. Then weigh 1.5 g of the coated powder, add 1 wt% cyanate as a binder, press it into a ring at 2500 MPa, and finally perform annealing treatment at 450 °C for 1 h. In the RF impedance analyzer, the highest real permeability in the frequency range of 1MHz-2.5GHz is about 7.5, and the permeability loss tangent angle in the frequency range of 1MHz-400MHz is lower than about 0.06;

Example 7

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 0.6mol NH ₄ Cl, 0.6mol C ₆ H ₈ O ₇ ·H ₂ O and 0.6mol NaH ₂ PO ₂ ·H ₂ O respectively and add them to the three-necked flask, and then add 800mL Distilled water, stir magnetically evenly; then add 400 mL of 2.5 mol/L sodium hydroxide solution; then add 15 g of NaBH ₄ solution dropwise to the reaction solution. The obtained product was separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility.

Disperse 10 g of the prepared amorphous powder in 100 mL of distilled water and 300 mL of absolute ethanol, add 0.4 g of KH550, then dropwise add 3 mL of ammonia water and 6 mL of TEOS to the solution, and stir for 5 hours, then separate the powder and wash it three times Dry again. Then weigh 1.5g of the coated powder, add 2wt% acrylic resin as a binder, press it into a ring under the condition of 1000MPa, and finally perform annealing treatment at 350℃ for 1h. In the RF impedance analyzer, the highest real permeability is about 7.7 in the frequency range of 1MHz-2.5GHz, and the permeability loss tangent angle in the frequency range of 1MHz-300MHz is lower than about 0.05.

Example 8

Weigh 0.4mol FeCl ₂ ·4H ₂ O, 0.6mol NH ₄ Cl, 0.6mol C ₆ H ₈ O ₇ ·H ₂ O and 0.6mol NaH ₂ PO ₂ ·H ₂ O respectively and add them to the three-necked flask, and then add 1500mL Distilled water, stir magnetically evenly; then add 400 mL of 2.5 mol/L sodium hydroxide solution; then add 0.1 mL of sodium chloroplatinate and 15 g of NaBH ₄ solution dropwise to the reaction solution. The obtained product was separated, washed with distilled water and absolute ethanol, and dried in vacuum to obtain amorphous FeBP particles with good dispersibility, and the yield was 20% higher than that without nucleating agent.

10 g of the prepared amorphous powder was coated with 1 wt % phosphating solution, and then distilled water was added for dilution, ultrasonication, stirring and drying. 1.5g of the coated powder was weighed and added with 1wt% acrylic resin as a binder, pressed into a ring at 1000MPa, and finally annealed at 200°C for 1h. In the RF impedance analyzer, the highest real permeability is about 8.7 in the frequency range of 1MHz-2.5GHz, and the permeability loss tangent angle in the frequency range of 1MHz-600MHz is lower than about 0.08.

Claims

A method for preparing FeBP amorphous soft magnetic powder, characterized in that the FeBP amorphous soft magnetic particles in the powder have a particle size of 100 nanometers to 2 microns, and are prepared based on a chemical precipitation method, and the specific method includes:

Fully dissolve a certain amount of ferrous chloride, ammonium chloride, citric acid and sodium hypophosphite; then add a certain amount of sodium hydroxide to the solution ; add the NaBH solution dropwise under the action of magnetic stirring, and mix the reaction product It is separated, washed with distilled water and absolute ethanol for several times, and finally dried to obtain FeBP amorphous soft magnetic powder.
The preparation method of FeBP amorphous soft magnetic powder according to claim 1, wherein the molar ratio of the ferrous chloride, ammonium chloride, citric acid and sodium hypophosphite is 1:0.5～4.5 : 0.1 to 2.5: 0.5 to 2.5.
The method for preparing FeBP amorphous soft magnetic powder according to claim 1, wherein the molar concentration of the sodium hydroxide is 1.2 to 6 times the molar concentration of ferrous ions.
The method for preparing FeBP amorphous soft magnetic powder according to claim 1, wherein the molar ratio of the sodium borohydride to ferrous chloride added dropwise is 1:0.5-4.
The preparation method of FeBP amorphous soft magnetic powder according to claim 1, wherein a nucleating agent silver nitrate or sodium chloroplatinate is also added in the reaction process.
The method for preparing FeBP amorphous soft magnetic powder according to claim 5, wherein the amount of the nucleating agent added is not more than 0.02 mol% of the content of ferrous chloride.
A method for forming FeBP amorphous soft magnetic powder core, characterized in that, the powder obtained by the method according to any one of claims 1-6 is firstly insulated and coated, then a binder is added, put into a mold, and pressed After that, it is annealed at 200-550°C.
The method for forming FeBP amorphous soft magnetic powder core according to claim 7, wherein the material used for the insulating coating is silicon dioxide, silicone resin, sodium silicate, magnesium oxide, or titanium oxide.
The method for forming FeBP amorphous soft magnetic powder core according to claim 7, wherein the binder is epoxy resin, silicone resin, acrylic resin, phenolic resin, polyurethane, triazine resin, isocyanate One or more, the molding pressure during pressing is 1000-2500 MPa.