阅读说明：本技术 一种软磁铁粉芯制备工艺 (Preparation process of soft magnetic powder core ) 是由 傅小鹤 唐璐 代欣茁 雷亮 罗建成 谭力波 于 2021-07-20 设计创作，主要内容包括：一种软磁铁粉芯制备工艺,包括如下步骤：1)原料预处理：选择雾化铁粉作为原料,将雾化铁粉进行绝缘包覆处理；2)压制成型：将经过绝缘包覆处理的雾化铁粉与润滑剂搅拌混合后压制成型；3)热处理：往高温炉中通入氮气,将步骤2)中压制成型的物料置于所述高温炉内,物料依次在高温炉中依次经过第一热处理区、第二热处理区以及冷却降温区；物料经过冷却降温区后出炉即得到软磁铁粉芯,物料出炉温度小于或等于50℃。本发明得到的软磁铁粉芯最大磁导率达到600,电阻率达到1000μΩ·m以上。(A preparation process of a soft magnetic powder core comprises the following steps: 1) pretreatment of raw materials: selecting atomized iron powder as a raw material, and carrying out insulation coating treatment on the atomized iron powder; 2) and (3) pressing and forming: stirring and mixing atomized iron powder subjected to insulation coating treatment and a lubricant, and then pressing and molding; 3) and (3) heat treatment: introducing nitrogen into the high-temperature furnace, placing the material subjected to compression molding in the step 2) into the high-temperature furnace, and sequentially passing the material through a first heat treatment area, a second heat treatment area and a cooling and cooling area in the high-temperature furnace; and discharging the material after cooling and temperature reduction to obtain the soft magnetic powder core, wherein the discharging temperature of the material is less than or equal to 50 ℃. The maximum magnetic conductivity of the soft magnetic powder core obtained by the invention reaches 600, and the resistivity reaches more than 1000 mu omega.)

1. A preparation process of a soft magnetic powder core is characterized by comprising the following steps:

1) pretreatment of raw materials: selecting atomized iron powder as a raw material, and carrying out insulation coating treatment on the atomized iron powder;

2) and (3) pressing and forming: stirring and mixing atomized iron powder subjected to insulation coating treatment and a lubricant, and then pressing and molding;

3) and (3) heat treatment: introducing nitrogen into the high-temperature furnace, placing the material subjected to compression molding in the step 2) into the high-temperature furnace, and sequentially passing the material through a first heat treatment area, a second heat treatment area and a cooling and cooling area in the high-temperature furnace; the temperature of the first heat treatment area is lower than that of the second heat treatment area, and the materials are discharged from the furnace after passing through a cooling and cooling area to obtain the soft magnetic powder core.

2. The process for preparing the soft magnetic powder core according to claim 1, wherein in the step 3), when the material passes through the first heat treatment zone, the temperature of the first heat treatment zone is raised to 380-450 ℃ at a speed of more than 10 ℃/min, and then the temperature is maintained for 10-120 min; when the material passes through the second heat treatment area, the temperature of the second heat treatment area is increased to 580-680 ℃ at the speed of more than 5 ℃/min, and then the temperature is kept for 3-30 min.

3. The process for preparing soft magnetic powder core according to claim 2, wherein in step 3), the high temperature furnace is a mesh belt furnace with built-in mesh belt or a push rod furnace with built-in conveying rail, and the material pressed and formed in step 2) is placed in a containing box and then placed on the mesh belt or the conveying rail.

4. The process for preparing soft magnetic iron powder core according to claim 3, wherein in step 3), the purity of nitrogen is not less than 99.5%, the conveying positions of nitrogen are the feeding port and the discharging port of the high temperature furnace, the air inlet direction of nitrogen is opposite to the conveying direction of the mesh belt or the conveying rail, and the nitrogen flow at the discharging port is 5-20 m³/h。

5. The process for preparing soft magnetic powder core according to claim 4, wherein in the step 3), the oxygen content in the high temperature furnace is maintained at 0.01-0.3%.

6. The process for preparing soft magnetic powder core according to claim 5, wherein in step 3), the height of the containing box is higher than the surface height of the material in the containing box, and the weight of the material in the containing box is 0.01-2 kg.

7. The process for preparing a soft magnetic iron powder core according to claim 1, wherein in step 1), the atomized iron powder is water atomized iron powder or gas atomized iron powder, the purity of the atomized iron powder is not less than 99.0%, and the particle size of the atomized iron powder is less than 40 mesh.

8. The process for preparing a soft magnetic powder core according to claim 1, wherein the insulating coating treatment in step 1) is performed by: and mixing the atomized iron powder with 0.1-5 wt% of phosphoric acid solution, and stirring until the mixture is dried.

9. The process for preparing the soft magnetic iron powder core according to claim 1, wherein in the step 2), the mass ratio of the lubricant to the atomized iron powder is 0.3-1: 100, and the lubricant comprises one or more of zinc stearate, lithium stearate, phenolic resin, polyetherimide, polyamide and epoxy resin.

10. A soft magnetic powder core characterized by being prepared by the process as claimed in any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of soft magnetic powder core treatment, in particular to a preparation process of a soft magnetic powder core.

Background

With the rapid development of the high-efficiency permanent magnet motor towards miniaturization and high frequency, in the field of high-frequency work, the suppression of the eddy current loss of the silicon steel sheet in the traditional motor becomes more and more difficult, so that the heat loss is increased, and the high-efficiency performance of the motor cannot obtain a satisfactory effect. The soft magnetic powder core with high magnetic conductivity and high resistivity has the advantages of small eddy current loss, small size, energy conservation, environmental protection and good prospect in the aspect of replacing silicon steel sheets. However, in the prior art, because iron is a ferromagnetic material, and pure iron has higher ferromagnetism than its oxide, and its magnetic permeability is generally several times higher than manganese-zinc ferrite and nickel-zinc ferrite, but because pure iron has low resistivity, it causes large magnetic loss, and limits its application, so that it is difficult to realize the performance of both high magnetic permeability and high resistivity in the preparation process of the soft magnetic iron powder core. The invention aims to develop a preparation process for a soft magnetic powder core, and the soft magnetic powder core product with better magnetic conductivity and resistivity is prepared only by controlling process conditions, so that the actual requirement is better met.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a preparation process of a soft magnetic iron powder core, so as to solve the problems in the background technology.

The technical problem solved by the invention is realized by adopting the following technical scheme:

a preparation process of a soft magnetic powder core comprises the following steps:

1) pretreatment of raw materials: selecting atomized iron powder as a raw material, and carrying out insulation coating treatment on the atomized iron powder;

2) and (3) pressing and forming: stirring and mixing atomized iron powder subjected to insulation coating treatment and a lubricant, and then pressing and molding;

3) and (3) heat treatment: introducing nitrogen into the high-temperature furnace, placing the material subjected to compression molding in the step 2) into the high-temperature furnace, and sequentially passing the material through a first heat treatment area, a second heat treatment area and a cooling and cooling area in the high-temperature furnace; the temperature of the first heat treatment area is lower than that of the second heat treatment area, and the materials are discharged from the furnace after passing through a cooling and cooling area to obtain the soft magnetic powder core.

Further, in the step 3), when the material passes through the first heat treatment area, the temperature of the first heat treatment area is increased to 380-450 ℃ at a speed of more than 10 ℃/min, and then the temperature is kept for 10-120 min; when the material passes through the second heat treatment area, the temperature of the second heat treatment area is increased to 580-680 ℃ at the speed of more than 5 ℃/min, and then the temperature is kept for 3-30 min.

Further, in the step 3), the high-temperature furnace is a mesh belt furnace with a built-in mesh belt or a push rod furnace with a built-in conveying rail, and the material which is pressed and formed in the step 2) is placed in the containing box and then placed on the mesh belt or the conveying rail.

Further, in the step 3), the purity of the nitrogen is not less than 99.5%, the conveying positions of the nitrogen are a feeding hole and a discharging hole of the high-temperature furnace, the air inlet direction of the nitrogen is opposite to the conveying direction of the mesh belt or the conveying rail, and the nitrogen flow at the discharging hole is 5-20 m³/h。

Further, in the step 3), the oxygen content in the high-temperature furnace is maintained to be 0.01-0.3%.

Further, in the step 3), the height of the accommodating box is higher than the surface height of the materials in the accommodating box, and the weight of the materials in the accommodating box is 0.01-2 kg. The accommodating box is preferably an iron box.

Further, in the step 1), the atomized iron powder is water atomized iron powder or gas atomized iron powder, the purity of the atomized iron powder is not less than 99.0%, and the particle size of the atomized iron powder is less than 40 meshes.

Further, in the step 1), the method for the insulation coating treatment comprises the following steps: and mixing the atomized iron powder with 0.1-5 wt% of phosphoric acid solution, and stirring until the mixture is dried.

Further, in the step 2), the mass ratio of the lubricant to the atomized iron powder is 0.3-1: 100, and the lubricant comprises one or more of zinc stearate, lithium stearate, phenolic resin, polyetherimide, polyamide and epoxy resin.

The soft magnetic iron powder core is prepared by adopting any one of the processes.

Has the advantages that: the preparation process of the soft magnetic iron powder core of the invention comprises the steps of carrying out insulation coating treatment on iron powder with higher purity, combining with a nitrogen protection type mesh belt furnace or a push rod furnace to carry out special staged heat treatment and other processes after molding and pressing, thus leading the maximum magnetic conductivity of the iron powder core obtained after processing the pure iron powder to reach 600, leading the resistivity to reach more than 1000 mu omega.m, and being capable of better meeting the requirements of permanent magnet motors and other products.

In the heat treatment process, the first heat treatment area ensures that the organic lubricant in the material is fully combusted to play a good dewaxing role, if the dewaxing is insufficient, the surface of the product is blackened, and the magnetic property is seriously reduced, and in the second heat treatment area, the product is rapidly cooled after reaching the critical temperature through high-temperature stress removal, so that the coated insulating layer can be prevented from being damaged to cause resistivity. In the process, it is very critical to strictly control the heating rate, the temperature after heating and the heat preservation time of each stage.

Detailed Description

In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

Example 1

The preparation process of the soft magnetic powder core comprises the following steps:

1) pretreatment of raw materials: selecting water atomized iron powder as a raw material, and carrying out insulation coating treatment on the water atomized iron powder; the purity of the water atomized iron powder is not less than 99.0 percent, and the particle size of the atomized iron powder is less than 40 meshes; the method for the insulation coating treatment comprises the following steps: and mixing the water atomized iron powder with 2 wt% phosphoric acid solution, and stirring until the mixture is dried.

2) And (3) pressing and forming: stirring and mixing the water atomized iron powder subjected to the insulating coating treatment and a lubricant, and then performing compression molding, wherein the normal-temperature compression molding is performed at the pressure of 800MPa during compression; the mass ratio of the lubricant to the atomized iron powder is 0.6:100, and the lubricant is zinc stearate.

3) And (3) heat treatment: introducing nitrogen into the high-temperature furnace, wherein the purity of the nitrogen is more than 99.5%, the conveying positions of the nitrogen are a feed inlet and a discharge outlet of the high-temperature furnace, the air inlet direction of the nitrogen is opposite to the conveying direction of the mesh belt or the conveying rail, and the nitrogen flow at the discharge outlet is 15-20 m³The oxygen content in the high-temperature furnace is maintained to be 0.1-0.3 percent.

The high-temperature furnace is a mesh belt furnace with a built-in mesh belt, the materials which are pressed and formed in the step 2) are placed in the containing box and then placed on the mesh belt, the height of the containing box is higher than the surface height of the materials in the containing box, and the weight of the materials in the containing box is 1.5 kg.

The material sequentially passes through a first heat treatment area, a second heat treatment area and a cooling and cooling area in a high-temperature furnace; when the material passes through the first heat treatment area, the temperature of the first heat treatment area is raised to 450 ℃ at the speed of 13 ℃/min, and then the temperature is kept for 60 min; when the material passes through the second heat treatment area, the temperature of the second heat treatment area is raised to 660 ℃ at a speed of more than 8 ℃/min, and then the temperature is kept for 10 min; and discharging the material after cooling and cooling the temperature zone to obtain the soft magnetic powder core, wherein the discharging temperature of the material is 50 ℃.

The obtained soft magnetic powder core was subjected to a test in which the resistivity was measured in the form of a standard circle (Φ 55 × Φ 45 × 5 mm). The direct current magnetic performance test is according to a measuring method of direct current magnetic performance of GB/T13012-2008 soft magnetic materials, and the alternating current magnetic performance test is according to a testing method of GB/T19346.1-2017 amorphous nanocrystalline alloy part 1: test of ring sample AC magnetic property

The indexes are as follows:

the product is blue gray and has no rusting phenomenon.

Resistivity: 1607 μ Ω · m.

Inductance: 24.3 uH (f 1KHz)

D, direct current magnetic property testing:

magnetic induction B @1000 (T): 1.55

Maximum magnetic permeability μmax: 604

And (3) testing alternating current magnetic property:

AC Core loss AC cores 1T (W/Kg): [email protected], [email protected], [email protected], [email protected] KHz.

Example 2

The preparation process of the soft magnetic powder core comprises the following steps:

1) pretreatment of raw materials: selecting gas atomization iron powder as a raw material, and carrying out insulation coating treatment on the gas atomization iron powder; the purity of the gas atomization iron powder is not less than 99.0 percent, and the granularity of the gas atomization iron powder is less than 40 meshes; the method for the insulation coating treatment comprises the following steps: and mixing the gas atomized iron powder with 1 wt% phosphoric acid solution, and stirring until the mixture is dried.

2) And (3) pressing and forming: stirring and mixing the water atomized iron powder subjected to the insulation coating treatment and a lubricant, and then performing compression molding, wherein the compression molding is performed at normal temperature under the pressure of 1000 MPa; the mass ratio of the lubricant to the atomized iron powder is 0.3:100, and the lubricant is composed of zinc stearate, polyamide and epoxy resin.

3) And (3) heat treatment: introducing nitrogen into the high-temperature furnace, wherein the purity of the nitrogen is more than 99.5%, the conveying positions of the nitrogen are a feed inlet and a discharge outlet of the high-temperature furnace, the air inlet direction of the nitrogen is opposite to the conveying direction of the mesh belt or the conveying rail, and the nitrogen flow at the discharge outlet is 10-15 m³The oxygen content in the high-temperature furnace is maintained to be 0.03-0.15 percent.

The high-temperature furnace is a push rod furnace with a built-in conveying rail, the materials which are pressed and formed in the step 2) are placed in the containing box and then placed on the conveying rail, the height of the containing box is higher than the surface height of the materials in the containing box, and the weight of the materials in the containing box is 0.5 kg.

The material sequentially passes through a first heat treatment area, a second heat treatment area and a cooling and cooling area in a high-temperature furnace; when the material passes through the first heat treatment area, the temperature of the first heat treatment area is raised to 420 ℃ at the speed of 15 ℃/min, and then the temperature is kept for 60 min; when the material passes through the second heat treatment area, the temperature of the second heat treatment area is raised to 620 ℃ at the speed of 10 ℃/min, and then the temperature is kept for 10 min; and discharging the material after cooling and cooling the temperature zone to obtain the soft magnetic powder core, wherein the discharging temperature of the material is 48 ℃.

The assay was performed according to the method described in example 1, with the following assay results:

the product is blue gray and has no rusting phenomenon.

Resistivity: 1871 μ Ω. m

Inductance: 24.6 uH (f 1KHz)

D, direct current magnetic property testing:

magnetic induction B @1000 (T): 1.56

Maximum magnetic permeability μmax: 625

And (3) testing alternating current magnetic property:

AC Core loss AC cores 1T (W/Kg): [email protected], [email protected], [email protected], [email protected] KHz.

Comparative example 1

In the process for preparing the soft magnetic powder core in the comparative example, when the material passes through the second heat treatment zone, the temperature of the second heat treatment zone is raised to 700 ℃ at a speed of 10 ℃/min, and then the temperature is maintained for 40min, and other operation conditions are the same as those in example 2.

The assay was performed according to the method described in example 1, with the following assay results:

the product is blue gray and has no rusting phenomenon.

Resistivity: 50.9. mu. omega. m

Inductance: 20.5 μ H (f ═ 1 KHz).

Comparative example 2

In the preparation process of the soft magnetic powder core according to the comparative example, in the step 3), the material is heated in a high-temperature furnace in stages, the temperature is directly raised to 620 ℃ at a speed of 15 ℃/min, the temperature is kept for 10min, and the material is cooled and cooled, and then is discharged from the furnace to obtain the soft magnetic powder core.

The assay was performed according to the method described in example 1, with the following assay results:

the product is blue-gray and has trace residue of combustion products.

Resistivity: 177 [ mu ] omega m

Inductance: 22.3 μ H (f ═ 1 KHz).

In the comparison example, the powder lubricant is not sufficiently combusted due to direct high temperature rise in the heat treatment process, and meanwhile, the powder lubricant enters a high temperature stage too quickly, an oxide layer on the outer surface of the product is not formed completely, and the protection effect on the internal powder cannot be achieved.

Comparative example 3

In the process for preparing the soft magnetic powder core in the comparative example, the oxygen content in the high-temperature furnace exceeds 2%, and other operating conditions are the same as those in the example 2.

The assay was performed according to the method described in example 1, with the following assay results:

the product is red and rusty.

Resistivity: 310 μ Ω. m

Inductance: 21.1 μ H (f ═ 1 KHz).

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.