Preparation method of amorphous FeSiCr magnetic powder

Abstract

This invention discloses a method for preparing amorphous FeSiCr magnetic powder, comprising preparing raw materials according to a formula, vacuum refining the raw materials and casting master alloy rods, melting the master alloy rods and spinning them into strips, mechanically crushing the strip alloy, sieving, and annealing to obtain the finished amorphous FeSiCr powder. This invention obtains sheet-like or strip-like amorphous FeSiCr alloys through jet spinning, followed by mechanical crushing to obtain amorphous FeSiCr magnetic powder with no compositional segregation and a uniform structure. This powder exhibits isotropy, better processing plasticity, higher surface uniformity, and more stable overall performance, significantly improving the magnetic properties of the powder product. It is suitable for preparing high-permeability, low-loss inductor devices and further enhances the corrosion resistance of the powder.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic powder materials technology, and more specifically, to a method for preparing amorphous FeSiCr magnetic powder. Background Technology

[0002] The development of 5G technology and new energy vehicles is driving the continuous upgrading of electronic components, with increasingly higher requirements for their functions such as high frequency, high power density, lightweight, and resistance to electromagnetic interference. In recent years, industry professionals have been researching the addition of appropriate amounts of Cr to the binary FeSi alloy system to improve the overall performance of the alloy. FeSiCr alloys, with their high permeability, high resistivity, good resistance to saturation current, and stable environmental reliability, are widely used in integrally molded inductor components.

[0003] For example, application number 202010278557.7 discloses a FeSiCr soft magnetic powder suitable for MIM wire-wound inductors, its preparation method, and the resulting inductor. The FeSiCr magnetic powder prepared by the combined water vapor atomization process has advantages such as uniform alloy composition and microstructure, fine and reasonably distributed powder particle size, good sphericity, and low impurity content, and can be used as a raw material for MIM wire-wound inductors.

[0004] For example, application number 201910245639.9 discloses a soft magnetic alloy material and its preparation method. This method uses vapor deposition to form a metal film on the surface of FeSiCr particles with a particle size of 8μm to 15μm. After heat treatment, the film is mixed with FeSiCr powder with a particle size of 1μm to 3μm in a certain proportion. Then, nano-silica and / or nano-magnesium oxide are added to obtain a FeSiCr mixed powder with a high self-resonant frequency and Q value, which can be used in operating frequency bands above 1MHz.

[0005] Currently, the main preparation processes for FeSiCr alloy magnetic powder are gas atomization, water atomization, or a combination of water and gas atomization. The FeSiCr powders obtained by atomization processes are all crystalline structures, with limited performance. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing amorphous FeSiCr magnetic powder, thereby solving one or more of the above-mentioned problems.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing amorphous FeSiCr magnetic powder, comprising the following steps: S1. Prepare the master alloy raw materials according to the element mass ratio, and obtain master alloy bars by vacuum refining. S2. Melt the master alloy rod and spin it to obtain a sheet or strip-shaped amorphous alloy; S3. Mechanical crushing yields amorphous or microcrystalline semi-finished alloy powder; S4. The semi-finished alloy powder is sieved and annealed to obtain amorphous finished alloy powder.

[0008] Furthermore, in step S1, the master alloy is formulated with 2-9 wt% Si and 1.5-9.5 wt% Cr by mass, with the remainder being Fe, and the purity of Fe, Si, and Cr is greater than 99%.

[0009] Further, in step S1, the raw materials of the formula amount are put into a vacuum high-frequency induction furnace for refining. The refining temperature is 1600~1700℃, and the material is held at the temperature and alloyed for 2~5 minutes before being cast to obtain the master alloy rod.

[0010] Furthermore, in step S2, the melting and spinning process involves placing the refined master alloy rod into a quartz tube to melt it, and then spraying it under pressure through a nozzle onto a high-speed rotating water-cooled copper roller.

[0011] Furthermore, after the master alloy rod is placed into the quartz tube, it needs to be sealed with a cap and then evacuated and heated. Before the molten master alloy rod is ejected through a nozzle, argon gas is introduced into the quartz tube to break the pressure.

[0012] Furthermore, in step S2, when the master alloy rod is heated to 1400~1500℃, the water-cooled copper roller is started. The rotation speed of the water-cooled copper roller is 1~30m / s. The higher the rotation speed of the water-cooled copper roller, the greater the spraying pressure, and the thinner and tougher the sheet amorphous alloy.

[0013] Furthermore, the mechanical crushing method in step S3 is one or more of crushing by a crusher, grinding by a ball mill, and grinding by an air jet mill, with protective gas introduced during crushing.

[0014] Furthermore, in step S4, powder that meets the particle size requirements is sieved using a 100-500 mesh sieve, and the annealing temperature is 320-520℃.

[0015] In summary, the present invention has the following beneficial effects: by spraying and spinning to obtain sheet-like or strip-like amorphous FeSiCr alloy, and then mechanically crushing to obtain amorphous FeSiCr magnetic powder with no compositional segregation and uniform structure, it exhibits isotropy, better processing plasticity, higher surface uniformity, and more stable overall performance of the product, greatly improving the magnetic properties of the powder product, making it suitable for preparing inductor devices with high magnetic permeability and low loss, and further improving the corrosion resistance of the powder. Attached Figure Description

[0016] Figure 1 A process flow diagram for one embodiment of the present invention; Figure 2Images of amorphous FeSiCr alloy strips produced under different rolling speed conditions in one embodiment of the present invention; Figure 3 The morphology of amorphous FeSiCr alloy powder obtained at a fixed roller speed in one embodiment of the present invention. Detailed Implementation

[0017] The following is in conjunction with the appendix Figure 1-3 The present invention will be described in further detail below. Example 1

[0018] A method for preparing amorphous FeSiCr magnetic powder, comprising the following steps: S1. Prepare the master alloy raw materials according to the master alloy formula with a mass ratio of 3.5wt% Si and 4.5wt% Cr, and the remainder being Fe. All raw materials are industrial grade materials with a purity >99%. The raw materials of the formula are put into the vacuum high-frequency induction furnace, the sealing plug is tightened, the quartz tube is evacuated and the power is gradually increased to 120kw. When the alloy liquid is heated to 1650℃, the power is maintained, the temperature is kept and the alloy liquid is alloyed for 3.5min. The alloy liquid is then poured into the prepared cylindrical mold to obtain the master alloy rod.

[0019] S2. Melting and Spinning the Master Alloy Rod. Specifically, the refined master alloy rod is placed in a quartz tube, which is then placed in an induction coil and secured with clamps. The sealing plug at the top of the quartz tube is tightened, and a vacuum is created inside before heating and melting. When heated to 1450℃, the water-cooled copper roller is started, and its rotation speed is set to 10 m / s. Simultaneously, argon gas is injected into the quartz tube to break the vacuum and create a positive pressure inside. By controlling the pressure inside the quartz tube, the molten liquid FeSiCr is rapidly and pressurized through a nozzle orifice onto the high-speed rotating water-cooled copper roller, obtaining a sheet or strip-shaped amorphous alloy. Within a speed range of 1~30 m / s, throughout the spinning process, the higher the rotation speed of the water-cooled copper roller and the greater the spray pressure, the thinner and more resilient the resulting sheet-shaped amorphous alloy.

[0020] S3. The obtained flake or ribbon-like amorphous FeSiCr is mechanically crushed. The mechanical crushing method is one or more of crushing by a crusher, grinding by a ball mill, and grinding by an air jet mill. Preferably, a ball mill is used for crushing, with a steel ball to alloy mass ratio of 6:1, an inert protective gas is introduced, the ball mill speed is 300 r / min, and the ball milling is carried out for 70 h to obtain amorphous or microcrystalline semi-finished alloy powder. S4. The semi-finished alloy powder is sieved through a 200-mesh copper sieve to obtain powder that meets the particle size requirements. The sieved powder is then annealed in a vacuum annealing furnace to eliminate internal stress and other defects through heat treatment. The annealing temperature is 320~520℃. Specifically, the temperature is first raised to 250℃ and held for 30 minutes, then raised to 460℃ and held for 70 minutes. The heating power is then turned off, nitrogen gas is introduced, and the powder is cooled to room temperature to obtain amorphous FeSiCr finished powder. Example 2

[0021] A method for preparing amorphous FeSiCr magnetic powder, comprising the following steps: S1. Prepare the master alloy raw materials according to the master alloy formula with 2wt% Si and 1.5wt% Cr by mass, and the remainder being Fe. All raw materials are industrial grade materials with a purity >99%. The raw materials of the formula are put into the vacuum high-frequency induction furnace, the sealing plug is tightened, the quartz tube is evacuated and the power is gradually increased to 120kw. When the alloy liquid is heated to 1600℃, the power is maintained, the temperature is kept and the alloy liquid is alloyed for 2 minutes. The alloy liquid is then poured into the prepared cylindrical mold to obtain the master alloy rod.

[0022] S2. Melting and Spinning the Master Alloy Rod. Specifically, the refined master alloy rod is placed in a quartz tube, which is then placed in an induction coil and secured with clamps. The sealing plug at the top of the quartz tube is tightened, and a vacuum is created inside before heating and melting. When heated to 1400℃, the water-cooled copper roller is started, and its rotation speed is set to 1 m / s. Simultaneously, argon gas is injected into the quartz tube to break the vacuum and create a positive pressure inside. By controlling the pressure inside the quartz tube, the molten liquid FeSiCr is rapidly and pressurized through a nozzle orifice onto the high-speed rotating water-cooled copper roller, obtaining a sheet or strip-shaped amorphous alloy. Within a speed range of 1~30 m / s, throughout the spinning process, the higher the rotation speed of the water-cooled copper roller and the greater the spray pressure, the thinner and more ductile the resulting sheet-shaped amorphous alloy.

[0023] S3. The obtained flake or ribbon-like amorphous FeSiCr is mechanically crushed. The mechanical crushing method is one or more of crushing by a crusher, grinding by a ball mill, and grinding by an air jet mill. Preferably, a ball mill is used for crushing, with a steel ball to alloy mass ratio of 6:1, an inert protective gas is introduced, the ball mill speed is 260 r / min, and the ball milling is carried out for 40 h to obtain amorphous or microcrystalline semi-finished alloy powder. S4. The semi-finished alloy powder is sieved through a 100-mesh copper sieve to obtain powder that meets the particle size requirements. The sieved powder is then annealed in a vacuum annealing furnace to eliminate internal stress and other defects through heat treatment. The annealing temperature is 320~520℃. Specifically, the temperature is first raised to 250℃ and held for 30 minutes, then raised to 420℃ and held for 40 minutes. The heating power is then turned off, nitrogen gas is introduced, and the powder is cooled to room temperature to obtain amorphous FeSiCr finished powder. Example 3

[0024] A method for preparing amorphous FeSiCr magnetic powder, comprising the following steps: S1. Prepare the master alloy raw materials according to the master alloy formula with a mass ratio of 9 wt% Si and 9.5 wt% Cr, and the remainder being Fe. All raw materials are industrial grade materials with a purity > 99%. The raw materials of the formula are put into the vacuum high-frequency induction furnace, the sealing plug is tightened, the quartz tube is evacuated and the power is gradually increased to 120kw. When the alloy liquid is heated to 1700℃, the power is maintained, the temperature is kept and the alloy liquid is alloyed for 5 minutes. It is then poured into the prepared cylindrical mold to obtain the master alloy rod.

[0025] S2. Melting and Spinning the Master Alloy Rod. Specifically, the refined master alloy rod is placed in a quartz tube, which is then placed in an induction coil and secured with clamps. The sealing plug at the top of the quartz tube is tightened, and a vacuum is created inside before heating and melting. When heated to 1500℃, the water-cooled copper roller is started, and its rotation speed is set to 30 m / s. Simultaneously, argon gas is injected into the quartz tube to break the vacuum and create a positive pressure inside. By controlling the pressure inside the quartz tube, the molten liquid FeSiCr is rapidly and pressurized through a nozzle orifice onto the high-speed rotating water-cooled copper roller, obtaining a sheet or strip-shaped amorphous alloy. Within the speed range of 1~30 m / s, throughout the spinning process, the higher the rotation speed of the water-cooled copper roller and the greater the spray pressure, the thinner and more ductile the resulting sheet-shaped amorphous alloy.

[0026] S3. The obtained flake or ribbon-like amorphous FeSiCr is mechanically crushed. The mechanical crushing method is one or more of crushing by a crusher, grinding by a ball mill, and grinding by an air jet mill. Preferably, a ball mill is used for crushing, with a steel ball to alloy mass ratio of 6:1, an inert protective gas is introduced, the ball mill speed is 350 r / min, and the ball milling is carried out for 100 h to obtain amorphous or microcrystalline semi-finished alloy powder. S4. The semi-finished alloy powder is sieved through a 500-mesh copper sieve to obtain powder that meets the particle size requirements. The sieved powder is then annealed in a vacuum annealing furnace to eliminate internal stress and other defects through heat treatment. The annealing temperature is 320~520℃. Specifically, the temperature is first raised to 250℃ and held for 30 minutes, then raised to 500℃ and held for 40~100 minutes. The heating power is then turned off, nitrogen gas is introduced, and the powder is cooled to room temperature to obtain amorphous FeSiCr finished powder.

[0027] The present invention involves obtaining sheet-like or strip-like amorphous FeSiCr alloy by spinning, followed by mechanical crushing to obtain amorphous FeSiCr alloy magnetic powder with no compositional segregation and uniform structure. Examples 2 and 3 are supplementary samples to Example 1, verifying that amorphous FeSiCr alloy powder can still be prepared under different conditions. The amorphous FeSiCr powder prepared in Example 1 was pressed into ring-shaped powder cores with an outer diameter of 14 mm and an inner diameter of 8 mm, numbered 1#, 2#, and 3#. The magnetic property data of the powder cores are shown in Table 1. Table 1. Performance data of amorphous FeSiCr powder cores

[0028] As can be seen from the table, the non-segregated master alloy rods refined under vacuum are melted, spun, and physically broken into uniformly structured amorphous or microcrystalline FeSiCr alloy magnetic powder. Unlike conventional crystalline FeSiCr alloy magnetic powder, this process can greatly improve the magnetic properties of the powder, making it suitable for preparing inductors with high permeability and low loss. Furthermore, the amorphous or microcrystalline structure can also improve the corrosion resistance of the powder.

[0029] It should be noted that this specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for preparing amorphous FeSiCr magnetic powder, characterized in that, The steps are as follows: S1. Prepare the master alloy raw materials according to the element mass ratio, and obtain master alloy bars by vacuum refining. S2. Melt the master alloy rod and spin it to obtain a sheet or strip-shaped amorphous alloy; S3. Mechanical crushing yields amorphous or microcrystalline semi-finished alloy powder; S4. The semi-finished alloy powder is sieved and annealed to obtain amorphous finished alloy powder.

2. The method for preparing amorphous FeSiCr magnetic powder according to claim 1, characterized in that, In step S1, the master alloy is formulated with 2-9 wt% Si and 1.5-9.5 wt% Cr by mass, with the remainder being Fe. The purity of Fe, Si, and Cr is greater than 99%.

3. The method for preparing amorphous FeSiCr magnetic powder according to claim 1, characterized in that, In step S1, the raw materials of the formula amount are put into a vacuum high-frequency induction furnace for refining. The refining temperature is 1600~1700℃, and the material is held at the temperature and alloyed for 2~5 minutes. The material is then cast to obtain the master alloy rod.

4. The method for preparing amorphous FeSiCr magnetic powder according to claim 1, characterized in that, In step S2, the melting and spinning process involves placing the refined master alloy rod into a quartz tube to melt it, and then spraying it under pressure through a nozzle onto a high-speed rotating water-cooled copper roller.

5. The method for preparing amorphous FeSiCr magnetic powder according to claim 4, characterized in that, After the master alloy rod is placed into the quartz tube, it needs to be sealed with a cap and then evacuated and heated. Before the molten master alloy rod is ejected through the nozzle, argon gas is introduced into the quartz tube to break the pressure.

6. The method for preparing amorphous FeSiCr magnetic powder according to claim 5, characterized in that, In step S2, when the master alloy rod is heated to 1400~1500℃, the water-cooled copper roller is started. The rotation speed of the water-cooled copper roller is 1~30m / s. The higher the rotation speed of the water-cooled copper roller, the greater the spraying pressure, the thinner the sheet amorphous alloy and the better the toughness.

7. The method for preparing amorphous FeSiCr magnetic powder according to claim 1, characterized in that, In step S3, the mechanical crushing method is one or more of the following: crushing by a crusher, grinding by a ball mill, and grinding by an air jet mill. Protective gas is introduced during the crushing process.

8. The method for preparing amorphous FeSiCr magnetic powder according to claim 1, characterized in that, In step S4, powder that meets the particle size requirements is sieved using a 100-500 mesh sieve, and the annealing temperature is 320-520℃.

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