High silicon steel magnetic powder and preparation method thereof

Abstract

The invention discloses high silicon steel magnetic powder and a preparation method thereof, and relates to the technical field of material scientificity, the preparation method comprises the following steps: step S100, strip preparation: raw materials are added into a smelting furnace, mother alloy smelting is carried out in an argon atmosphere, and the raw materials comprise 6.5 wt% of silicon, 0.03 wt% of Y2O3 and the balance of iron; molten steel obtained through smelting is subjected to cooling rolling through a cooling copper roller, and an initial strip is obtained through strip spraying forming; s200, annealing is conducted, specifically, the initial strip is guided into an atmosphere furnace to be subjected to high-temperature annealing treatment, and a high-silicon steel strip is obtained; and S300, crushing is conducted, specifically, the high-silicon steel strip is subjected to crushing treatment, and crushed high-silicon steel magnetic powder is obtained. According to the method, the high silicon steel strip is prepared in a rapid ultra-cold strip spraying mode, the ultra-thin high silicon steel strip can be prepared, and then the high-performance high silicon steel magnetic powder can be produced through an airflow crushing method, so that the application scene of the high silicon steel can be widened, for example, the high silicon steel can be applied to the field of transformers or wave-absorbing and shielding materials.

Description

Technical Field

[0001] The present invention relates to the field of material science and technology, and in particular to high-silicon steel magnetic powder and a preparation method thereof. Background Art

[0002] As silicon content increases, the magnetostriction coefficient of silicon steel decreases, iron loss decreases, and magnetic permeability increases. When the silicon mass fraction reaches 6.5%, silicon steel exhibits optimal soft magnetic properties and is particularly suitable for high-frequency electrical products. Magnetic permeability reaches its maximum, iron loss is minimized, and magnetostriction approaches zero, making it an ideal material for achieving high efficiency, energy conservation, and lightweight electromagnetic equipment. For example, in high-frequency motors, audio and high-frequency transformers, and magnetic shielding, 6.5 wt% Si silicon steel can effectively reduce iron loss, improve efficiency, and reduce energy consumption. However, the presence of ordered DO3 and B2 phases in 6.5 wt% Si high-silicon steel results in brittleness and extremely poor processability, making it difficult to prepare using conventional rolling methods, thus restricting its production and application.

[0003] Therefore, the current high silicon steel products have the following disadvantages: 1. The thickness of high-silicon steel sheets produced using traditional mechanical hot / cold rolling methods can only reach around 0.1mm, making it difficult to make thinner. This limits further improvements in the loss and magnetic properties of high-silicon steel products. 2. The presence of DO3 and B2 ordered phases in 6.5 wt% Si high-silicon steel results in brittle texture and extremely poor processing properties, making it difficult to produce using conventional rolling methods. CVD deposition of Si gradients is required to increase the silicon content of the silicon steel sheet to improve product performance. However, the CVD method produces harmful gases, increasing the cost of exhaust gas treatment and placing higher demands on environmental protection. 3. Although the single method of extreme cold spraying can obtain thinner strip products, severe segregation leads to poor disorder, resulting in poor magnetic and loss performance of the product. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention aims to provide a high silicon steel magnetic powder and a preparation method thereof, aiming to solve the above-mentioned problems recorded in the prior art.

[0005] A first aspect of the present invention is to provide a method for preparing high silicon steel magnetic powder, the method comprising: Step S100, tape making: The raw materials are added into a melting furnace and the master alloy is melted in an argon atmosphere. The raw materials contain 6.5wt% Si, 0.03wt% Y2O3, and the balance is iron. The molten steel obtained by smelting is cooled and rolled using a cooling copper roller, and the initial strip is obtained by spray forming; Step S200, annealing: introducing the initial strip into an atmosphere furnace for high-temperature annealing to obtain a high-silicon steel strip; Step S300, crushing: The high silicon steel strip is crushed to obtain crushed high silicon steel magnetic powder.

[0006] According to one aspect of the above technical solution, the smelting temperature of the master alloy is 1300°C-1550°C, the smelting time is 50min-60min, and the smelting furnace power is 2800kW-3000kW.

[0007] According to one aspect of the above technical solution, the annealing temperature of the high-temperature annealing treatment performed on the initial strip is 950° C.-1200° C., and the annealing time is 2 hours.

[0008] According to one aspect of the above technical solution, the high-temperature annealing treatment of the initial strip is carried out in a mixed atmosphere including a nitrogen atmosphere and a hydrogen atmosphere, with a gas flow ratio of N2:H2=3:1.

[0009] According to one aspect of the above technical solution, the crushing process of the high silicon steel strip includes: The high silicon steel strip is subjected to primary crushing, and the intermediate product is subjected to secondary crushing after the primary crushing.

[0010] According to one aspect of the above technical solution, the primary crushing of the high silicon steel strip includes: The high silicon steel strip is coarsely crushed by a ball mill to obtain crushed high silicon steel magnetic blocks, thus completing the first-level crushing; Among them, the ball-to-material mass ratio in the ball milling equipment is 3:1, the ball milling speed is 600 r / min, and the ball milling time is 1 h.

[0011] According to one aspect of the above technical solution, after the primary crushing, the intermediate product is subjected to secondary crushing: comprising The crushed high silicon steel magnetic blocks are put into an air flow crusher for air flow crushing, and the powder is screened to obtain high silicon steel magnetic powder; Among them, the air flow breaking time is 0.5h.

[0012] According to one aspect of the above technical solution, the high silicon steel magnetic powder obtained through strip making, annealing and crushing has a D50 particle size of 30 μm, a D10 particle size of 5 μm, and a D90 particle size of 80 μm.

[0013] The second aspect of the present invention is to provide a high silicon steel magnetic powder prepared by the method described in the above technical solution.

[0014] Compared with the prior art, the high silicon steel magnetic powder and the preparation method thereof shown in the present invention have the following beneficial effects: This invention proposes improving the ductility of high-silicon steel products by doping them with a certain amount of the rare earth element Y2O3. The addition of the rare earth element Y not only refines the ordered domains of the high-silicon steel but also reduces the ordered phase content, degree of order, and hardness, while stabilizing grain boundaries, effectively improving the plasticity of the high-silicon steel. Furthermore, this invention produces ultra-thin high-silicon steel strips through rapid, ultra-cold spraying. This is then followed by airflow crushing to produce high-performance high-silicon steel magnetic powder, broadening the application of high-silicon steel, for example, in transformers or as absorbing and shielding materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 Schematic diagram of a process for preparing high silicon steel magnetic powder according to one embodiment of the present invention; Figure 2 This is a morphology diagram of a high silicon steel strip produced in one embodiment of the present invention; Figure 3 This is a morphology diagram of high silicon steel magnetic powder prepared in one embodiment of the present invention. DETAILED DESCRIPTION

[0016] To make the objectives, features, and advantages of the present invention more readily apparent, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The accompanying drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0017] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] Conventional high-silicon steel (6.5wt% silicon content) is difficult to roll into thin strips (<0.03mm) due to the ordered formation of brittle phases such as B2 and DO3 by silicon atoms, and cannot be directly crushed into high-performance magnetic powder. This invention overcomes this brittleness limitation by combining rare earth doping (Y2O3) with a rapid solidification and graded crushing process, producing high-silicon steel magnetic powder with a uniform particle size (D50 = 30μm).

[0020] Example 1 See also Figure 1 The first embodiment of the present invention provides a method for preparing high silicon steel magnetic powder, the method comprising: Step S100, tape making: The raw materials are added into a melting furnace and the master alloy is melted in an argon atmosphere. The raw materials contain 6.5wt% Si, 0.03wt% Y2O3, and the balance is iron. The molten steel obtained by smelting is cooled and rolled using a cooling copper roller, and the initial strip is formed by spraying.

[0021] Among them, the smelting temperature of the master alloy is 1300°C-1550°C, the smelting time is 50min-60min, and the smelting furnace power is 2800kW-3000kW.

[0022] Specifically, in this embodiment, the raw materials used for strip production contain 6.5wt% silicon, 0.03wt% Y2O3, and the balance iron. The strip production process includes a raw material smelting step, specifically master alloy smelting, at a temperature of 1300°C-1550°C, a furnace power of 2800kW-3000kW, a furnace capacity of 250kg, and a smelting time of 50-60 minutes. Argon gas is used throughout the process to protect the melt. The strip production process also includes a cooling step, which involves controlling the speed of the cooling copper roller via a control system; controlling the positional relationship with the nozzle to ensure that the molten steel forms an amorphous strip; and controlling the distance between the nozzle and the cooling copper roller to 0.2mm-3mm. The addition of rare earth Y to the raw materials stabilizes and refines the grain boundaries, thereby improving the brittleness of the high-silicon steel strip.

[0023] Step S200, annealing: The initial strip is introduced into an atmosphere furnace for high-temperature annealing to obtain a high-silicon steel strip.

[0024] The initial strip is subjected to high-temperature annealing treatment at a temperature of 950° C. to 1200° C., preferably 1100° C., and the annealing time is 2 hours.

[0025] The high temperature annealing treatment of the initial strip is carried out in a mixed atmosphere including a nitrogen atmosphere and a hydrogen atmosphere, with a gas flow ratio of N2:H2=3:1.

[0026] Specifically, in this embodiment, the formed strip, i.e., the prepared initial strip, is introduced into an atmosphere furnace for high-temperature annealing. The annealing temperature is 950°C-1200°C, preferably 1100°C in this embodiment. A mixed atmosphere is required in the atmosphere furnace, which is a nitrogen atmosphere and a hydrogen atmosphere. The gas flow ratio is N2:H2=3:1, and the annealing time is 2h. In this embodiment, a high-silicon steel strip is obtained by high-temperature annealing the initial strip. Its morphology is shown in the figure below. Figure 2 As shown, this is conducive to reducing the degree of texture deviation, that is, the degree of deviation of grain orientation from random distribution in polycrystalline materials, and reducing the lattice distortion caused by residual stress. The resistance to magnetic domain wall migration during magnetization is smaller and the magnetic induction Bs is higher.

[0027] Step S300, crushing: The high silicon steel strip is crushed to obtain crushed high silicon steel magnetic powder.

[0028] The crushing process of the high silicon steel strip includes: The high silicon steel strip is subjected to primary crushing, and the intermediate product is subjected to secondary crushing after the primary crushing.

[0029] More specifically, the primary crushing of the high silicon steel strip includes: The high silicon steel strip is coarsely crushed by a ball mill to obtain crushed high silicon steel magnetic blocks, thus completing the first-level crushing; Among them, the ball-to-material mass ratio in the ball milling equipment is 3:1, the ball milling speed is 600 r / min, and the ball milling time is 1 h.

[0030] And, secondary crushing of the intermediate product after primary crushing includes: The crushed high silicon steel magnetic blocks are put into an air flow crusher for air flow crushing, and the powder is screened to obtain high silicon steel magnetic powder; Among them, the air flow breaking time is 0.5h.

[0031] In this embodiment, the high silicon steel magnetic powder obtained through strip making, annealing and crushing has a D50 particle size of 30 μm, a D10 particle size of 5 μm, and a D90 particle size of 80 μm.

[0032] Specifically, in this embodiment, ball milling is used to roughly break the strip and air flow crushing is used to shape it and eliminate the sharp corners of the broken powder. Specifically, the annealed high silicon steel strip is crushed by ball milling equipment to obtain broken high silicon steel magnetic blocks or high silicon steel magnetic powder; the ball-to-material mass ratio in the ball milling equipment is 3:1, the ball milling speed is 600r / min, and the ball milling time is 1 hour; then the coarsely broken high silicon steel magnetic blocks or high silicon steel magnetic powder are put into the air flow crusher, and the crushing time is 0.5h; then sieving to obtain flaky high silicon steel magnetic powder, the morphology of which is shown in the figure. Figure 3 As shown, the average particle size of the high silicon steel magnetic powder obtained at this time, that is, the D50 particle size is 30 μm, the D10 particle size is 5 μm, and the D90 particle size is 80 μm.

[0033] It should be noted that the reason why rare earth Y is added to high silicon steel in this embodiment to refine the grains and reduce the degree of order so as to improve the toughness and ductility of high silicon steel is that the rare earth Y element has a strong affinity for impurity elements such as O and S. On the one hand, it purifies harmful elements and enhances the grain boundary strength of silicon steel. At the same time, the oxides formed in high silicon steel, specifically oxysulfides, can promote heterogeneous nucleation and significantly refine the grains. On the other hand, during the formation of B2 and DO3 ordered phases, due to the strong binding ability between rare earth Y atoms and Fe atoms and Si atoms, when adjacent atoms are rearranged, Fe atoms and Si atoms will be dragged by Y atoms, hindering the binding of Fe atoms and Si atoms during the formation of ordered phases. The addition of Y element refines the ordered domains, hinders the formation of ordered phases, and significantly reduces the degree of order.

[0034] The method described in this embodiment employs an annealing process to improve the degree of crystal disorder caused by extreme cold during belt spinning, resulting in a product with improved magnetic properties and lower losses. The airflow crushing method produces flaky, high-performance, high-silicon steel magnetic powder, which can be used as raw powder for pressing and sintering transformer cores or as raw material for microwave absorbing materials.

[0035] Therefore, compared with the prior art, the high silicon steel magnetic powder and the preparation method thereof shown in this embodiment have the following beneficial effects: This embodiment proposes improving the ductility of high-silicon steel products by doping a certain amount of the rare earth element Y2O3. The addition of the rare earth element Y not only refines the ordered domains of the high-silicon steel but also reduces the ordered phase content, degree of order, and hardness, while stabilizing grain boundaries, effectively improving the plasticity of the high-silicon steel. Furthermore, this embodiment produces high-silicon steel strip through rapid, ultra-cold spraying, enabling the production of ultra-thin high-silicon steel strip. This is then followed by the production of high-performance high-silicon steel magnetic powder through air flow crushing, thereby broadening the application of high-silicon steel, for example, in transformers or in the fields of radar absorbing and shielding materials.

[0036] Comparative Example 1 The first comparative example provides a method for preparing high silicon steel magnetic powder, which adopts the current CVD method to prepare a high carbon steel product with a thickness of 0.1 mm.

[0037] Comparative Example 2 The second comparative example provides a preparation method of high silicon steel magnetic powder that is substantially the same as that of the first embodiment of the present invention, except that the Y2O3 content is 0%, that is, no Y2O3 is added to the raw materials for master alloy smelting.

[0038] Comparative Example 3 The third comparative example provides a preparation method of high silicon steel magnetic powder that is substantially the same as that of the first embodiment of the present invention, except that the Y2O3 content is 1%, i.e., Y2O3 0.01 wt%.

[0039] Comparative Example 4 The fourth comparative example provides a preparation method of high silicon steel magnetic powder that is substantially the same as that of the first embodiment of the present invention, except that the Y2O3 content is 2%, i.e., Y2O3 0.02 wt%.

[0040] Comparative Example 5 The fifth comparative example provides a preparation method of high silicon steel magnetic powder that is substantially the same as that of the first embodiment of the present invention, except that the Y2O3 content is 4%, i.e., Y2O3 0.04 wt%.

[0041] Table 1 is a performance comparison table of the embodiments of the present invention and the comparative examples under the same test conditions and at a characteristic point of 5000 H / A.

[0042] Table 1

[0043] According to Example 1 of the present invention and Comparative Example 1, compared with the high-silicon steel product obtained by the traditional CVD method shown in Comparative Example 1, it can be seen that the high-silicon steel product prepared by the method shown in Example 1 of the present invention is thinner (0.03 mm) and has higher magnetic properties and lower losses.

[0044] In addition, in combination with Example 1 of the present invention and Comparative Examples 2-5 obtained based on the variation of Example 1, it can be seen that as the Y element content in high silicon steel increases, its elongation at break can be effectively improved, the loss is effectively reduced, and the saturated Bs value is effectively improved. Due to the increase in elongation at break, ultra-wide strips can be produced with lower loss and higher saturated Bs value. After the Y element content in high silicon steel reaches a certain concentration, the performance indicators of elongation at break, loss and saturated Bs value all decrease significantly. This shows that the higher the Y element content in high silicon steel, the better. By limiting it to below 0.03% as shown in Example 1 of the present invention, better performance can be obtained.

[0045] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0047] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing high silicon steel magnetic powder, characterized in that: The preparation method comprises: Step S100, tape making: The raw materials are added into a melting furnace and the master alloy is melted in an argon atmosphere. The raw materials contain 6.5wt% Si, 0.03wt% Y2O3, and the balance is iron. The molten steel obtained by smelting is cooled and rolled using a cooling copper roller, and the initial strip is obtained by spray forming; Step S200, annealing: introducing the initial strip into an atmosphere furnace for high-temperature annealing to obtain a high-silicon steel strip; Step S300, crushing: The high silicon steel strip is crushed to obtain crushed high silicon steel magnetic powder.

2. The method for preparing high silicon steel magnetic powder according to claim 1, wherein: The smelting temperature of the master alloy is 1300°C-1550°C, the smelting time is 50min-60min, and the smelting furnace power is 2800kW-3000kW.

3. The method for preparing high silicon steel magnetic powder according to claim 1, characterized in that: The initial strip is subjected to high-temperature annealing treatment at a temperature of 950° C. to 1200° C. and for a time of 2 hours.

4. The method for preparing high silicon steel magnetic powder according to claim 3, characterized in that: The high temperature annealing treatment of the initial strip is carried out in a mixed atmosphere including a nitrogen atmosphere and a hydrogen atmosphere, with a gas flow ratio of N2:H2=3:

1.

5. The method for preparing high silicon steel magnetic powder according to claim 1, characterized in that: The crushing process of the high silicon steel strip comprises: The high silicon steel strip is subjected to primary crushing, and the intermediate product is subjected to secondary crushing after the primary crushing.

6. The method for preparing high silicon steel magnetic powder according to claim 5, characterized in that: The primary crushing of the high silicon steel strip comprises: The high silicon steel strip is coarsely crushed by a ball mill to obtain crushed high silicon steel magnetic blocks, thus completing the first-level crushing; Among them, the ball-to-material mass ratio in the ball milling equipment is 3:1, the ball milling speed is 600 r / min, and the ball milling time is 1 h.

7. The method for preparing high silicon steel magnetic powder according to claim 5, characterized in that: Secondary crushing of the intermediate product after primary crushing includes: The crushed high silicon steel magnetic blocks are put into an air flow crusher for air flow crushing, and the powder is screened to obtain high silicon steel magnetic powder; Among them, the air flow breaking time is 0.5h.

8. The method for preparing high silicon steel magnetic powder according to any one of claims 1 to 7, characterized in that: The high silicon steel magnetic powder obtained through strip making, annealing and crushing has a D50 particle size of 30 μm, a D10 particle size of 5 μm and a D90 particle size of 80 μm.

9. A high silicon steel magnetic powder, characterized in that: The method is prepared by any one of claims 1 to 8.

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