Ellipsoidal fe-ni powder, magnetic powder core comprising the same, and method for manufacturing the same

Abstract

The application provides an ellipsoidal iron-nickel powder, a magnetic powder core containing the same and a preparation method of the same. The iron-nickel powder is ellipsoidal in shape; the ratio of the longest size to the smallest size of the iron-nickel powder is (1.1-3.0):1; the preparation method of the ellipsoidal iron-nickel powder comprises the following steps: a metal liquid containing iron and nickel is subjected to water-gas combined atomization by high-pressure gas to obtain atomized beads; the atomized beads are introduced into water at a distance of 600-1000 mm from the water surface for rapid cooling to obtain the ellipsoidal iron-nickel powder; the preparation method of the iron-nickel magnetic powder core comprises the following steps: (1) the ellipsoidal iron-nickel powder is sequentially subjected to inorganic coating, surface passivation and insulation coating to obtain coated iron-nickel powder; (2) the coated iron-nickel powder is sequentially subjected to pressing, heat treatment and immersion spraying to obtain the iron-nickel magnetic powder core. The application improves the magnetic permeability and reduces the magnetic loss, and also provides a material basis for high-density pressing.

Description

Technical Field

[0001] This invention relates to the field of technology, and more particularly to an ellipsoidal iron-nickel powder, a magnetic powder core containing the same, and a method for preparing the same. Background Technology

[0002] Iron-nickel magnetic powder cores are widely used in telecommunications, computer, and control systems due to their high energy storage capacity, high saturation magnetic flux density, and relatively low loss per unit volume.

[0003] With the upgrading of electronic products, the requirements for the practicality, safety and reliability of inductor components are constantly increasing, and the demand for small-size, high-power inductors is also increasing. Especially in high-power, high-current electronic products, iron-nickel magnetic powder cores with low loss and high superposition are highly favored.

[0004] Therefore, it is necessary to focus on developing low-loss, high-permeability iron-nickel products. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides an ellipsoidal iron-nickel powder, a magnetic powder core containing the same, and a method for preparing the same. The ellipsoidal iron-nickel powder provided by the present invention has an ellipsoidal shape, which results in a dense arrangement of powder particles with almost no gaps between them, significantly improving the magnetic permeability of the magnetic powder core and reducing magnetic loss. Moreover, the present invention optimizes the coating process of the magnetic powder core, increasing the content of iron-nickel powder in the coating, thereby further improving the magnetic permeability.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an ellipsoidal iron-nickel powder, wherein the iron-nickel powder is ellipsoidal in shape; the ratio of the longest dimension to the smallest dimension of the iron-nickel powder is (1.1 to 3.0): 1.

[0008] This invention selects ellipsoidal iron-nickel powder, which is tightly packed during pressing with almost no gaps, thereby significantly improving the magnetic permeability of the subsequent magnetic powder core.

[0009] It is worth noting that controlling the shape of iron-nickel powder is not easy. The general preparation process uses gas atomization technology, which produces spherical powder particles. Through extensive research, this invention has found that by using water-air combined atomization technology and controlling the water entry distance, ellipsoidal particles can be produced. Compared with ordinary spherical particles, this improves the permeability of the subsequent magnetic powder core and reduces magnetic loss.

[0010] Preferably, the nickel content in the iron-nickel powder is 48-52%, for example, it can be 49% or 50%.

[0011] Preferably, the size of the iron-nickel powder is 80-400 mesh, for example, it can be a range of different particle sizes such as 80-400 mesh, 120-400 mesh, 140-400 mesh, 200-400 mesh, etc.

[0012] It is worth noting that the present invention can select different particle sizes according to the different permeability of the magnetic powder core. Different particle sizes such as 80-400 mesh, 120-400 mesh, 140-400 mesh, and 200-400 mesh can be selected for subsequent coating. The coarser the particle size, the higher the permeability of the magnetic powder core under the same process, but the loss will increase slightly.

[0013] Secondly, the present invention provides a method for preparing ellipsoidal iron-nickel powder, the method comprising: a liquid metal containing iron and nickel being atomized by a high-pressure gas to obtain mist droplets; the mist droplets being rapidly cooled in water at a distance of 600-1000 mm from the surface of the water to obtain ellipsoidal iron-nickel powder.

[0014] In this invention, the distance from the water inlet surface is 600-1000mm, for example, 700mm, 750mm, 800mm, 900mm or 950mm.

[0015] This invention controls the time between the formation of the mist droplets and the water surface by controlling the distance between the droplets and the water surface. This allows for control of the water entry time. During this time, the droplets, under the influence of surface tension, do not have time to fully recover their spherical shape before entering the water and rapidly cooling and solidifying, forming ellipsoidal powder.

[0016] When the distance from the water surface is too short, the crushing effect of high-pressure nitrogen forms rod-shaped or sheet-like beads. These beads, before the surface tension has had the necessary contraction effect, rapidly cool and solidify in the water, resulting in irregularly shaped particles with uneven surfaces, such as rods, sharp corners, or dumbbells, making it difficult to form ellipsoids. When the distance from the water surface is too long, the surface tension acts for too long, causing the uncooled and solidified droplets to form regular spheres under the full effect of surface tension. Therefore, this invention controls the distance from the water surface within the range of 600–1000 mm, significantly improving the compactness of the subsequent powder arrangement and increasing the magnetic permeability of the subsequent magnetic powder core.

[0017] Preferably, the pressure of the high-pressure gas is 1.2 to 2.5 MPa, for example, it can be 1.5 MPa, 2.0 MPa or 2.3 MPa.

[0018] When the pressure of the high-pressure gas is too low, the resulting mist droplets will be too large, resulting in coarse powder particles or the inability to break the molten steel and achieve atomization. When the pressure of the high-pressure gas is too high, the resulting mist droplets will be too small, resulting in a low powder yield on a 400-mesh sieve, and the small particles will be difficult to form an ellipsoid.

[0019] Preferably, the source of the molten iron and nickel includes that obtained by high-temperature melting of iron and nickel.

[0020] Preferably, the high-temperature melting includes high-temperature melting in an induction furnace.

[0021] Preferably, the high-pressure gas includes high-pressure nitrogen.

[0022] Preferably, the temperature of the rapidly cooled water is room temperature.

[0023] The ambient temperature referred to in this invention is the ambient temperature without heating or cooling, generally around 25°C, but may fluctuate within the range of -40 to 42°C depending on climatic conditions. Under normal circumstances, an ambient temperature ≤30°C is selected for rapid cooling.

[0024] Preferably, the preparation method further includes: sieving the ellipsoidal iron-nickel powder to obtain the ellipsoidal iron-nickel powder of the desired size.

[0025] Thirdly, the present invention provides a method for preparing an iron-nickel magnetic powder core, wherein the method for preparing the iron-nickel magnetic powder core uses ellipsoidal iron-nickel powder as described in the first aspect, or the method for preparing the iron-nickel magnetic powder core uses ellipsoidal iron-nickel powder obtained by the method for preparing ellipsoidal iron-nickel powder as described in the second aspect; the method for preparing the iron-nickel magnetic powder core includes the following steps:

[0026] (1) Ellipsoidal iron-nickel powder is subjected to inorganic coating, surface passivation and insulating coating in sequence to obtain coated iron-nickel powder;

[0027] (2) The coated iron-nickel powder is pressed, heat-treated and impregnated sprayed in sequence to obtain an iron-nickel magnetic powder core.

[0028] The preparation method provided by this invention uses ellipsoidal iron-nickel powder, which remains ellipsoidal after coating. During the subsequent pressing process, the powder is tightly packed, resulting in an iron-nickel magnetic powder core with high density and low magnetic loss.

[0029] Preferably, the inorganic filler used in the inorganic coating in step (1) includes any one or at least two of kaolin, mica powder or quartz powder, wherein typical but non-limiting combinations are the combination of kaolin and mica powder, the combination of quartz powder and mica powder, and the combination of kaolin and quartz powder.

[0030] Preferably, the inorganic filler accounts for 0.02% to 0.2% of the mass of the ellipsoidal iron-nickel powder, for example, it can be 0.05%, 0.1%, or 0.15%.

[0031] Preferably, the surface passivation includes: using a hydrogen phosphate to perform a passivation reaction with ellipsoidal iron-nickel powder, followed by adding an alkali to terminate the passivation reaction, thereby completing the surface passivation.

[0032] It is worth noting that because phosphates are highly reactive in water, a very small amount (<0.1%) of material can achieve surface passivation and insulation effects in a very short time. This can significantly reduce the amount of non-magnetic coating material added, greatly increase the iron-nickel ratio in the coating powder, which is beneficial to improving magnetic permeability and also provides a material basis for high-density pressing.

[0033] Preferably, the hydrogen phosphate includes calcium dihydrogen phosphate.

[0034] Preferably, the alkali comprises calcium hydroxide.

[0035] Preferably, the amount of the hydrophosphate is 0.01 to 0.1% of the mass of the ellipsoidal iron-nickel powder, for example, it can be 0.03%, 0.05%, or 0.08%.

[0036] Preferably, the amount of alkali used is sufficient to completely react the hydrogen phosphate.

[0037] Specifically, let's take calcium dihydrogen phosphate and calcium hydroxide as examples:

[0038] Ca(H2PO4)2+2Ca(OH)2=Ca3(PO4)2↓+4H2O

[0039] The molecular weight of calcium dihydrogen phosphate is 234 g / mol, and the molecular weight of calcium hydroxide is 74 g / mol. The molar ratio for a complete chemical reaction is 1:2. Therefore, the amount of calcium hydroxide added is approximately 0.63 times the amount of calcium dihydrogen phosphate used (74 × 2 ÷ 234 ≈ 0.63 times).

[0040] Preferably, the passivation reaction time is 20s to 2min, for example, it can be 30s, 50s, 1min or 90s.

[0041] Preferably, the insulation coating includes: using a water-soluble resin for insulation coating.

[0042] Preferably, the amount of water-soluble resin used is 0.2% to 1% of the mass of the ellipsoidal iron-nickel powder, for example, it can be 0.5% or 0.8%.

[0043] Preferably, the water-soluble resin includes any one or a combination of at least two of water-soluble epoxy resin, water-soluble silicone resin, water-soluble acrylic resin, or water-soluble phenolic resin, with water-soluble silicone resin being the most preferred.

[0044] The present invention does not have any special requirements for the water-soluble silicone resin, and any water-soluble silicone resin known to those skilled in the art that can be used as a coating material can be used.

[0045] Preferably, solvents are added independently in the inorganic coating, surface passivation, and insulating coating processes.

[0046] Preferably, the solvents in the inorganic coating, surface passivation, and insulating coating are each water independently.

[0047] Preferably, the amount of solvent used in the inorganic coating, surface passivation, and insulating coating is independently 1-5% of the mass of the ellipsoidal iron-nickel powder, for example, 1.5%, 2%, 3%, or 4%, preferably 3%. This ensures that the water can fully wet the powder without excessive humidity hindering the uniformity of mixing between the coating material and the iron-nickel powder.

[0048] Compared to existing coating technologies that typically use organic solvents such as ethanol, acetone, or ethyl acetate, this invention uses water-soluble resin for coating, avoiding the toxicity and flammability / explosiveness issues of organic solvents. High-insulation powders such as kaolin, mica powder, or quartz powder are selected as inorganic fillers; phosphate aqueous solution is used as a surface passivating agent; and alkaline substances such as calcium hydroxide, which can undergo acid-base neutralization reactions with phosphate and form phosphate precipitates, are used as chemical reaction terminators. Water-soluble silicone resin is used as an adhesive to insulate the iron-nickel powder, resulting in a coating material with excellent performance.

[0049] It is worth noting that the iron-nickel powder prepared by the optimized powder spraying process in this invention is ellipsoidal. This ellipsoidal powder, aided by the vibration fixture in the press, allows the powder particles to be stacked in an optimal arrangement, effectively improving the pressing density of the magnetic ring. Using ellipsoidal powder, a pressing density of 7.5 g / cm³ can be achieved. 3 above.

[0050] Preferably, the atmosphere for the heat treatment is a protective atmosphere.

[0051] Preferably, the protective atmosphere includes any one of a nitrogen atmosphere, an argon atmosphere, or a nitrogen-hydrogen mixture atmosphere.

[0052] Preferably, the heat treatment temperature is 750–810°C, for example, 780°C, 790°C, or 800°C.

[0053] Preferably, the heat treatment duration is 0.5 to 1.5 hours, for example, 0.8 hours, 1.0 hours, 1.2 hours, or 1.4 hours.

[0054] It is worth noting that once the iron-nickel magnetic powder cores produced pass the magnetic performance test, they can be sold or used externally.

[0055] Fourthly, the present invention provides an iron-nickel magnetic powder core, wherein the iron-nickel magnetic powder core is prepared by the preparation method of the iron-nickel magnetic powder core described in the third aspect.

[0056] The iron-nickel magnetic powder core provided by this invention has high permeability and low loss, wherein the high permeability μ value is 160-200 (1V, 100kHz) and the low loss P 50KHz / 100mT <280mW / cm 3 .

[0057] Preferably, the iron-nickel magnetic powder core is ellipsoidal in shape.

[0058] Preferably, the content of iron-nickel powder in the iron-nickel magnetic powder core is 88-99.9 wt%, for example, it can be 88.5 wt%, 90 wt%, 92 wt%, 95 wt%, 99 wt%, or 99.5 wt%.

[0059] Compared with the prior art, the present invention has at least the following beneficial effects:

[0060] (1) The ellipsoidal iron-nickel powder provided by the present invention can be obtained by water-air combined atomization powder preparation technology, and the powder preparation cost is low. When pressed, it is tightly arranged with almost no gaps, thereby significantly improving the magnetic permeability of the subsequent magnetic powder core preparation.

[0061] (2) The method for preparing the iron-nickel magnetic powder core provided by the present invention uses water-soluble materials to insulate and coat ellipsoidal iron-nickel powder, eliminating the safety hazards of toxicity and flammability of organic coating solvents, and the coating scheme is safe and reliable; the introduction of chemical reaction terminator can prevent excessive corrosion of magnetic powder by phosphate and performance deterioration; at the same time, water-soluble organosilicon resin is selected as adhesive, which provides material support for coating high-performance iron-nickel powder with water as solvent; moreover, the iron-nickel powder content in the magnetic powder core obtained by the present invention is high.

[0062] (3) The method for preparing iron-nickel magnetic powder cores provided by the present invention, through high-density pressing and forming and appropriate heat treatment processes, can obtain a core with μ of 160-200 (1V, 100kHz) and low loss P after impregnation spraying. 50KHz / 100mT <280mW / cm 3 High permeability iron-nickel magnetic powder core. Attached Figure Description

[0063] Figure 1 This is a cross-sectional view of the iron-nickel magnetic powder core prepared in Application Example 1 of the present invention.

[0064] Figure 2 This is a cross-sectional view of the iron-nickel magnetic powder core prepared in Application Example 1 of the present invention. Detailed Implementation

[0065] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0066] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0067] Example 1

[0068] This embodiment provides a method for preparing ellipsoidal iron-nickel powder, which includes the following steps:

[0069] (1) Select pure iron and pure nickel as raw materials, and melt them at high temperature in an induction furnace to obtain a metal liquid containing iron and nickel with a suitable iron-nickel ratio. The iron-nickel powder has a nickel content of 50% and the remainder is iron.

[0070] (2) The molten metal containing iron and nickel is atomized by high-pressure nitrogen (pressure 2.0 MPa) in a water-gas combined atomization device to obtain mist droplets;

[0071] (3) The mist droplets enter the water at a distance of 800 mm from the water surface for rapid cooling to obtain ellipsoidal iron-nickel powder;

[0072] (4) The ellipsoidal iron-nickel powder is sieved to obtain iron-nickel alloy powder with a mesh size of 200-400.

[0073] Example 2

[0074] This embodiment provides a method for preparing ellipsoidal iron-nickel powder. Except for obtaining 140-400 mesh iron-nickel alloy powder by sieving, the ellipsoidal iron-nickel powder is the same as in Example 1, and will not be repeated here.

[0075] Example 3

[0076] This embodiment provides a method for preparing ellipsoidal iron-nickel powder. Except for obtaining 120-400 mesh iron-nickel alloy powder by sieving, the ellipsoidal iron-nickel powder is the same as in Example 1, and will not be repeated here.

[0077] Example 4

[0078] This embodiment provides a method for preparing ellipsoidal iron-nickel powder. Except for obtaining 80-400 mesh iron-nickel alloy powder by sieving, the ellipsoidal iron-nickel powder is the same as in Example 1, and will not be repeated here.

[0079] Example 5

[0080] This embodiment provides a method for preparing ellipsoidal iron-nickel powder, which includes the following steps:

[0081] (1) Select pure iron and pure nickel as raw materials, and melt them at high temperature in an induction furnace to obtain a metal liquid containing iron and nickel with a suitable iron-nickel ratio. The iron-nickel powder has a nickel content of 52% and the remainder is iron.

[0082] (2) The molten metal containing iron and nickel is atomized by high-pressure nitrogen (1.2 MPa) in a water-gas combined atomization device to obtain mist droplets;

[0083] (3) The mist droplets enter the water at a distance of 1000mm from the water surface for rapid cooling to obtain ellipsoidal iron-nickel powder;

[0084] (4) The ellipsoidal iron-nickel powder is sieved to obtain iron-nickel alloy powder with a mesh size of 200-400.

[0085] Example 6

[0086] This embodiment provides a method for preparing ellipsoidal iron-nickel powder, which includes the following steps:

[0087] (1) Select pure iron and pure nickel as raw materials, and melt them at high temperature in an induction furnace to obtain a metal liquid containing iron and nickel with a suitable iron-nickel ratio. The iron-nickel powder has a nickel content of 48% and the remainder is iron.

[0088] (2) The molten metal containing iron and nickel is atomized by high-pressure nitrogen (pressure 2.5MPa) in a water-gas combined atomization device to obtain mist droplets;

[0089] (3) The mist droplets enter the water at a distance of 600 mm from the water surface for rapid cooling to obtain ellipsoidal iron-nickel powder;

[0090] (4) The ellipsoidal iron-nickel powder is sieved to obtain iron-nickel alloy powder with a mesh size of 120-400.

[0091] Comparative Example 1

[0092] This comparative example provides a method for preparing iron-nickel powder. Except for the fact that the iron-nickel powder is rapidly cooled in water at a distance of 1300 mm from the water surface, the method is the same as in Example 1 and will not be repeated here.

[0093] Comparative Example 2

[0094] This comparative example provides a method for preparing iron-nickel powder. Except for the fact that the iron-nickel powder is rapidly cooled in water at a distance of 300 mm from the water surface, the method is the same as in Example 1 and will not be repeated here.

[0095] Because the distance from the water surface was too short, the comparative example resulted in irregularly shaped particles with uneven surfaces, such as rod-shaped, sharp-angled, and dumbbell-shaped particles, which were difficult to form ellipsoids. Furthermore, the particles were too small to be coated into a magnetic powder core.

[0096] The shape properties of the iron-nickel powders prepared in the above embodiments and comparative examples are shown in Table 1.

[0097] Table 1

[0098]

[0099] Application Example 1

[0100] This application example provides a method for preparing an iron-nickel magnetic powder core, the method comprising the following steps:

[0101] (1) Mix 0.1 wt% quartz powder and the ellipsoidal iron-nickel powder provided in Example 1 for 10 min, then mix 0.1 wt% calcium dihydrogen phosphate aqueous solution, passivate for 1 min, add 0.063 wt% calcium hydroxide dilute solution to the mixed powder to terminate the passivation reaction, mix 0.8% water-soluble silicone resin (brand name SH9608) for 10 min, the amount of water added in the whole coating process is about 3%, heat to evaporate the solvent (water) until the slurry becomes powder again, and obtain coated iron-nickel powder;

[0102] (2) The coated iron-nickel powder is subjected to pressing (the coated iron-nickel powder is cooled and then mixed with 0.5% zinc stearate lubricant (Sanyi Lubricant Zinc Stearate SAK-ZS-PLB), and the magnetic core size is a magnetic ring with an outer diameter of 26.9 mm, an inner diameter of 14.7 mm, and a height of 11.2 mm, and the pressing pressure is 2200 MPa), heat treatment (annealing under nitrogen atmosphere, annealing temperature is 790℃, annealing time is 1 h) and impregnation spraying to obtain an iron-nickel magnetic powder core.

[0103] The cross-sectional and sectional views of the iron-nickel magnetic powder core prepared in this application example are shown below. Figures 1-2 As shown, from Figures 1-2 It can be seen that the powder particles in the magnetic powder core are obviously ellipsoidal, and the particles are coarse with almost no fine powder below 30μm. After grinding and splitting the cross-section of the magnetic powder core, it can be observed that the particles are closely arranged and there are almost no gaps between the particles.

[0104] Application Examples 2-4 and Comparative Examples 1-3

[0105] Application Examples 2-4 and Comparative Example 1 used the iron-nickel powders provided in Examples 2-4 and Comparative Example 1, respectively. Other specific parameters and the performance of the magnetic powder core are shown in Table 2.

[0106] Application Example 5

[0107] This application example provides a method for preparing an iron-nickel magnetic powder core, the method comprising the following steps:

[0108] (1) Mix 0.2wt% kaolin and the ellipsoidal iron-nickel powder provided in Example 5 for 15 min, then mix 0.05wt% calcium dihydrogen phosphate aqueous solution for 1.5 min for passivation reaction, add 0.015wt% calcium hydroxide dilute solution to terminate the passivation reaction, mix 0.9% water-soluble silicone resin (brand name SH9608) for 8 min, the amount of water added in the whole coating process is about 2.5%, heat to evaporate the solvent (water) until the slurry becomes powder again, and obtain coated iron-nickel powder;

[0109] (2) The coated iron-nickel powder is subjected to pressing (the coated iron-nickel powder is cooled and then mixed with 0.6% zinc stearate lubricant (Sanyi Lubricant Zinc Stearate SAK-ZS-PLB) to press a magnetic ring with an outer diameter of 26.9 mm, an inner diameter of 14.7 mm, and a height of 11.2 mm, with a pressing pressure of 2300 MPa), heat treatment (annealing under nitrogen atmosphere, annealing temperature of 750℃, annealing time of 1.5 h) and impregnation spraying to obtain an iron-nickel magnetic powder core.

[0110] Application Example 6

[0111] This application example provides a method for preparing an iron-nickel magnetic powder core, the method comprising the following steps:

[0112] (1) Mix 0.2wt% quartz powder and the ellipsoidal iron-nickel powder provided in Example 6 for 12 min, then mix 0.08wt% calcium dihydrogen phosphate aqueous solution for 0.5 min for passivation reaction, add 0.025wt% calcium hydroxide dilute solution to terminate the passivation reaction, mix 0.5% water-soluble silicone resin (brand name SH9608) for 12 min, the amount of water added in the whole coating process is about 4%, heat to evaporate the solvent (water) until the slurry becomes powder again, and obtain coated iron-nickel powder;

[0113] (2) The coated iron-nickel powder is subjected to pressing (the coated iron-nickel powder is cooled and then mixed with 0.8% zinc stearate lubricant (Sanyi Lubricant Zinc Stearate SAK-ZS-PLB), and the magnetic core size is a magnetic ring with an outer diameter of 26.9 mm, an inner diameter of 14.7 mm, and a height of 11.2 mm, and the pressing pressure is 2000 MPa), heat treatment (annealing under nitrogen atmosphere, annealing temperature is 810℃, annealing time is 0.5 h) and impregnation spraying to obtain an iron-nickel magnetic powder core.

[0114] Test method: The permeability and DC-Bias were calculated by using the Yihe 6632-1 bias current source test system to test the inductance. The magnetic loss was tested using the SY-8219 BH tester.

[0115] The relevant data for the above application examples and comparative examples are shown in Table 2.

[0116] Table 2

[0117]

[0118] The following points can be observed from Table 2:

[0119] (1) As can be seen from the comprehensive application examples 1 to 4, by selecting different range powders and finely adjusting the coating scheme, magnetic powder cores with different permeabilities can be obtained. Overall, the larger the selected powder particle size, the higher the permeability, but the loss will also increase.

[0120] (2) Comparing Application Example 1 and Application Comparative Example 2, it can be seen that the same powder of the present invention is used to prepare magnetic powder cores with different adhesives. The inorganic adhesive (sodium silicate) suffers severe loss, while the organosilicon resin adhesive used in the present invention has better loss and higher magnetic permeability.

[0121] (3) Comparing Application Example 1 and Application Comparative Example 1, it can be seen that the present invention uses powders of different shapes with the same mesh size and the same coating scheme to prepare magnetic powder cores. Elliptical powder has higher magnetic permeability than spherical powder.

[0122] (4) Comparing Application Example 1 and Application Comparative Example 3, it can be seen that in Application Comparative Example 3, acetone was used as the coating solvent and phosphoric acid and oil-soluble silicone resin (SH-5202N) were used as the coating material. This resulted in a higher magnetic loss and a lower magnetic permeability of the final magnetic powder core compared to Application Example 1. This shows that by using water as the coating solvent and water-soluble silicone resin as the coating material, the present invention can not only avoid the toxicity of organic solvents, but also improve the performance of the magnetic powder core.

[0123] In summary, the method for preparing the iron-nickel magnetic powder core provided by this invention utilizes ellipsoidal iron-nickel powder prepared by combined water-air atomization, and combines it with the coating technology designed in this invention. Through high-density pressing and heat treatment processes, and after impregnation spraying, a core with μ = 160-200 and low loss P50KHz / 100mT < 280mW / cm can be obtained. 3 High permeability iron-nickel magnetic powder core.

[0124] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing ellipsoidal iron-nickel powder, characterized in that, The preparation method includes: Iron and nickel-containing molten metal is atomized by high-pressure gas through a combination of water and gas to obtain mist droplets; The mist droplets enter the water at a distance of 600-1000 mm from the water surface for rapid cooling, resulting in ellipsoidal iron-nickel powder. The ratio of the longest dimension to the smallest dimension of the iron-nickel powder is (1.1~3.0):

1.

2. The method for preparing ellipsoidal iron-nickel powder according to claim 1, characterized in that, The nickel content in the iron-nickel powder is 48-52%.

3. The method for preparing ellipsoidal iron-nickel powder according to claim 1, characterized in that, The iron-nickel powder has a size of 80-400 mesh.

4. The method for preparing ellipsoidal iron-nickel powder according to claim 1, characterized in that, The source of the iron and nickel-containing molten metal includes that obtained by high-temperature melting of iron and nickel.

5. The method for preparing ellipsoidal iron-nickel powder according to claim 4, characterized in that, The high-temperature melting includes high-temperature melting in an induction furnace.

6. The method for preparing ellipsoidal iron-nickel powder according to claim 1, characterized in that, The high-pressure gas includes high-pressure nitrogen.

7. The method for preparing ellipsoidal iron-nickel powder according to claim 1, characterized in that, The pressure of the high-pressure gas is 1.2~2.5MPa.

8. The method for preparing ellipsoidal iron-nickel powder according to claim 1, characterized in that, The preparation method further includes: sieving the ellipsoidal iron-nickel powder to obtain the ellipsoidal iron-nickel powder of the desired size.

9. A method for preparing an iron-nickel magnetic powder core, characterized in that, The method for preparing the iron-nickel magnetic powder core uses ellipsoidal iron-nickel powder obtained by the method for preparing ellipsoidal iron-nickel powder according to any one of claims 1-8; the method for preparing the iron-nickel magnetic powder core includes the following steps: (1) Ellipsoidal iron-nickel powder is subjected to inorganic coating, surface passivation and insulating coating in sequence to obtain coated iron-nickel powder; (2) The coated iron-nickel powder is pressed, heat-treated and impregnated in sequence to obtain an iron-nickel magnetic powder core.

10. The method for preparing an iron-nickel magnetic powder core according to claim 9, characterized in that, The inorganic filler used in step (1) includes any one or a combination of at least two of kaolin, mica powder or quartz powder.

11. The method for preparing an iron-nickel magnetic powder core according to claim 10, characterized in that, The inorganic filler accounts for 0.02~0.2% of the mass of the ellipsoidal iron-nickel powder.

12. The method for preparing an iron-nickel magnetic powder core according to claim 9, characterized in that, The surface passivation includes: using hydrogen phosphate to perform a passivation reaction with ellipsoidal iron-nickel powder, followed by adding an alkali to terminate the passivation reaction and complete the surface passivation.

13. The method for preparing an iron-nickel magnetic powder core according to claim 12, characterized in that, The hydrogen phosphates include calcium dihydrogen phosphate.

14. The method for preparing an iron-nickel magnetic powder core according to claim 12, characterized in that, The alkali includes calcium hydroxide.

15. The method for preparing an iron-nickel magnetic powder core according to claim 12, characterized in that, The amount of the hydrogen phosphate used is 0.01 to 0.1% of the mass of the ellipsoidal iron-nickel powder.

16. The method for preparing an iron-nickel magnetic powder core according to claim 12, characterized in that, The amount of alkali used should be sufficient to completely react the hydrogen phosphate.

17. The method for preparing an iron-nickel magnetic powder core according to claim 12, characterized in that, The passivation reaction takes 20 seconds to 2 minutes.

18. The method for preparing an iron-nickel magnetic powder core according to claim 9, characterized in that, The insulation coating includes: using water-soluble resin for insulation coating.

19. The method for preparing an iron-nickel magnetic powder core according to claim 18, characterized in that, The water-soluble resin includes any one or a combination of at least two of the following: water-soluble epoxy resin, water-soluble silicone resin, water-soluble acrylic resin, or water-soluble phenolic resin.

20. The method for preparing an iron-nickel magnetic powder core according to claim 19, characterized in that, The water-soluble resin is a water-soluble organosilicon resin.

21. The method for preparing an iron-nickel magnetic powder core according to claim 18, characterized in that, The amount of water-soluble resin used is 0.2-1% of the mass of the ellipsoidal iron-nickel powder.

22. The method for preparing an iron-nickel magnetic powder core according to claim 9, characterized in that, Solvents are added independently in each of the inorganic coating, surface passivation, and insulating coating processes.

23. The method for preparing an iron-nickel magnetic powder core according to claim 22, characterized in that, The solvents used in the inorganic coating, surface passivation, and insulating coating are each water.

24. The method for preparing an iron-nickel magnetic powder core according to claim 22, characterized in that, The amount of solvent used in the inorganic coating, surface passivation, and insulating coating is independently 1 to 5% of the mass of the ellipsoidal iron-nickel powder.

25. The method for preparing an iron-nickel magnetic powder core according to claim 24, characterized in that, The amount of solvent used in the inorganic coating, surface passivation, and insulating coating is independently 3% of the mass of the ellipsoidal iron-nickel powder.

26. The method for preparing an iron-nickel magnetic powder core according to claim 9, characterized in that, The atmosphere used for the heat treatment is a protective atmosphere.

27. The method for preparing an iron-nickel magnetic powder core according to claim 26, characterized in that, The protective atmosphere includes any one of nitrogen atmosphere, argon atmosphere, or nitrogen-hydrogen mixture atmosphere.

28. The method for preparing an iron-nickel magnetic powder core according to claim 9, characterized in that, The heat treatment temperature is 750~810℃.

29. The method for preparing an iron-nickel magnetic powder core according to claim 9, characterized in that, The heat treatment lasts for 0.5 to 1.5 hours.

30. A type of iron-nickel magnetic powder core, characterized in that, The iron-nickel magnetic powder core is prepared by the method for preparing iron-nickel magnetic powder core according to any one of claims 9 to 29.

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