CN115775665A - Method for manufacturing powder magnetic core - Google Patents
Method for manufacturing powder magnetic core Download PDFInfo
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- CN115775665A CN115775665A CN202210873100.XA CN202210873100A CN115775665A CN 115775665 A CN115775665 A CN 115775665A CN 202210873100 A CN202210873100 A CN 202210873100A CN 115775665 A CN115775665 A CN 115775665A
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Abstract
The invention provides a method for manufacturing a dust core, which can reduce hysteresis loss and improve magnetic permeability. The invention comprises the following steps: a powder heat treatment process; a first addition step of adding a first lubricant to the FeSiAl alloy powder subjected to the powder heat treatment step; and a second addition step of adding a second lubricant to the FeSiAl alloy powder coated with the insulating resin. The ratio of the peak value of the crystal plane index 220 to the peak value of the crystal plane index 111 in the X-ray diffraction of the FeSiAl alloy powder subjected to the powder heat treatment step is 0.020 or more and 0.030 or less based on the following formula (c) ((b))1) The value of the uneven strain of (a) is 0.232 to 0.325 inclusive. In the formula (1), β represents an integral width, D represents a crystallite size, θ represents a diffraction angle, λ represents a wavelength of an X-ray, and η represents an uneven strain.
Description
Technical Field
The present invention relates to a method for manufacturing a powder magnetic core.
Background
Coil components such as reactors are used in various applications such as Office Automation (OA) equipment, solar power generation systems, and automobiles. The coil component has a coil mounted on a core. In addition, a dust core is often used as the core.
The powder magnetic core is produced, for example, by: an insulating layer formed around soft magnetic powder such as FeSiAl alloy powder is formed, and after adding a lubricant, press molding is performed. Since the pressure at the time of press molding is a relatively high pressure of several tons (ton) to several tens of tons, the soft magnetic powder is compacted.
For the purpose of improving energy exchange efficiency, reducing heat generation, and the like, a powder magnetic core is required to have magnetic properties that can obtain a large magnetic flux density with a small applied magnetic field and magnetic properties that cause less energy loss in the change in magnetic flux density. As the magnetic characteristics relating to the magnetic flux density, for example, magnetic permeability (μ) can be cited. As the magnetic characteristics related to the energy loss, iron loss (Pcv), also called core loss (core loss), can be cited. The iron loss (Pcv) is expressed as the sum of the hysteresis loss (Ph) and the eddy current loss (Pe).
[ Prior art documents ]
[ patent document ]
[ patent document 1] Japanese patent No. 5929819
[ patent document 2] Japanese patent laid-open No. 2009-088502
Disclosure of Invention
[ problems to be solved by the invention ]
Conventionally, studies related to reduction of hysteresis loss and studies related to improvement of permeability are advancing. For example, as in patent document 1, when crystal grains are coarse, studies have been advanced to obtain low hysteresis loss and the like. Further, as in patent document 2, studies have been advanced on improving the magnetic permeability by reducing the deformation of the crystal structure in the soft magnetic powder by applying heat treatment to the soft magnetic powder. However, it is difficult to achieve both reduction of hysteresis loss and improvement of magnetic permeability.
The present invention has been made to solve the above-described problems, and an object thereof is to provide a method for manufacturing a powder magnetic core that can reduce hysteresis loss and improve magnetic permeability at the same time.
[ means for solving the problems ]
The present inventors have obtained a finding that a dust core manufactured by satisfying three conditions can achieve both reduction in hysteresis loss and high permeability when FeSiAl-based alloy powder is used as soft magnetic powder.
The method for manufacturing a powder magnetic core according to the present invention is based on the findings of the present inventors, and in order to achieve the above object, the method for manufacturing a powder magnetic core includes: a first addition step of adding a first lubricant to the FeSiAl alloy powder; a coating step of coating the FeSiAl alloy powder subjected to the first lubricant addition step with an insulating resin; and a second addition step of adding a second lubricant to the fesiall-based alloy powder subjected to the coating step, wherein the first lubricant has a melting point of 59 ℃ or higher and 135 ℃ or lower, wherein the ratio of the peak of the crystallographic index 220 to the peak of the crystallographic index 111 in the X-ray diffraction of the fesiall-based alloy powder before the first addition step is 0.020 or higher and 0.030 or lower, and wherein the value of the non-uniform strain based on the following expression (1) is 0.232 or higher and 0.325 or lower.
[ number 1]
In the formula (1), β represents an integral width, D represents a crystallite size, θ represents a diffraction angle, λ represents a wavelength of an X-ray, and η represents an uneven strain.
[ Effect of the invention ]
According to the present invention, a method for manufacturing a dust core can be obtained that can achieve both reduction in hysteresis loss and improvement in magnetic permeability.
Drawings
Fig. 1 is a graph comparing magnetic permeability and hysteresis loss in each example and each comparative example.
Fig. 2 is a graph showing a relationship between the melting point and the magnetic permeability of the first lubricant.
Fig. 3 is a graph showing a relationship between the melting point and the hysteresis loss of the first lubricant.
Detailed Description
(embodiment mode)
A method for manufacturing the powder magnetic core of the present embodiment will be described. The present invention is not limited to the embodiments described below.
The dust core is a magnetic material used for a core of a coil component mounted in OA equipment, a solar power generation system, an automobile, or the like. The dust core contains soft magnetic powder. The soft magnetic powder is added with the lubricant to form an insulating layer, and the lubricant is added again to the soft magnetic powder formed with the insulating layer, followed by pressure molding to produce a molded body. Then, the compact is heat-treated to produce a dust core. Specifically, the powder magnetic core is produced by passing through (1) a powder heat treatment step, (2) a first addition step, (3) a coating step, (4) a second addition step, (5) a press molding step, and (6) a molded body heat treatment step.
(1) Powder Heat treatment Process
The powder heat treatment step is a step of heat-treating the soft magnetic powder. The soft magnetic powder may be FeSiAl alloy powder containing iron, silicon, and aluminum. The FeSiAl alloy powder contains about 7 to 11wt% of Si and about 4 to 8wt% of Al relative to Fe. The FeSiAl-based alloy powder may contain Ni in an amount of about 1wt% to 3wt% with respect to Fe, for example. Further, the FeSiAl-based alloy powder may contain Co, cr, or Mn.
In the powder heat treatment step, the mixture is heated in a non-oxidizing atmosphere for 1 to 6 hours. The non-oxidizing atmosphere includes a low-oxygen atmosphere or an inert gas atmosphere, such as 0.01% of the atmosphere. As the inert gas, H can be mentioned 2 Or N 2 . The heat treatment temperature is 450 ℃ or higher and 550 ℃ or lower. Through the powder heat treatment processThe FeSiAl alloy powder after the sintering has a ratio of the peak value of the crystal plane index 220 to the peak value of the crystal plane index 111 of 0.02 to 0.03, and has a non-uniform strain of 0.232 to 0.325.
The peak ratio is calculated by X-ray diffraction using Rietveld (Rietveld) analysis. By setting the peak ratio to the above range, hysteresis loss can be reduced. The peak described here is the height of the peak (value on the vertical axis, the number of counts) in a graph in which the horizontal axis represents the diffraction angle 2 θ (unit: degree (deg)) and the vertical axis represents the X-ray intensity (unit CPS (cycle per second) = counts/second) obtained by X-ray diffraction. That is, the peak of the crystal plane index 111 means the height of the peak in the crystal plane index 111, and the peak of the crystal plane index 220 means the height of the peak in the crystal plane index 220.
The uneven strain is a variation in strain when an aggregate of tens of thousands of particles of powder is observed and observed from each lattice plane. The uneven strain is calculated from the following formula (1) by X-ray diffraction of the crystal structure of the FeSiAl alloy powder. The value of the uneven strain calculated by the formula (1) is 0.232 or more and 0.325 or less. By setting the range, hysteresis loss can be reduced.
[ number 1]
In the formula (1), β represents an integral width, D represents a crystallite size, θ represents a diffraction angle, λ represents a wavelength of an X-ray, and η represents an uneven strain.
Further, the powder heat treatment step may be omitted as long as the FeSiAl alloy powder has a peak ratio of 0.02 to 0.03 and an uneven strain of 0.232 to 0.325. For example, in the case of producing a FeSiAl-based alloy powder by a gas atomization (gas atomization) method, a gas is blown to the FeSiAl-based alloy powder melted at a high temperature, and then the powder is cooled. By adjusting the cooling rate, the peak ratio and the non-uniform strain can be changed. Examples of the adjustment of the cooling rate include: a method of adjusting the cooling rate by adjusting the amount of water when cooling by blowing the adsorbed gas and then blowing the adsorbed water; or a method of adjusting the cooling rate by changing the particle diameter of powder formed by adjusting the flow rate or pressure of gas when blowing the gas or adjusting the diameter of a nozzle through which the molten alloy flows out. Therefore, instead of the powder heat treatment step, the cooling rate may be adjusted to bring the peak ratio and the uneven strain into the above-described ranges.
(2) First adding step
The first addition step is a step of adding a first lubricant to the fesiall-based alloy powder subjected to the powder heat treatment step. The first lubricant has a melting point of 59-135 ℃. By setting the melting point of the first lubricant to the above range, the magnetic permeability can be high and the hysteresis loss can be reduced. Stearic acid, zinc stearate, magnesium stearate, fatty acid derivatives are particularly preferably used as the first lubricant. By using these kinds as the first lubricant, high permeability and hysteresis loss reduction can be achieved more significantly.
The amount of the first lubricant added is preferably 0.1wt% or more and 0.6wt% or less with respect to the FeSiAl alloy powder. By setting the range, the sliding of the powder becomes better and the density is improved.
(3) Coating step
The coating step is a step of adding an insulating resin to the FeSiAl-based alloy powder having undergone the first addition step and forming an insulating layer around the FeSiAl-based alloy powder. That is, an insulating layer containing an insulating resin is formed around the FeSiAl alloy powder. The form of adhesion of the insulating material is not limited as long as the insulating layer is formed around the FeSiAl alloy powder. That is, the insulating resin may be attached so as to completely cover the periphery of the fesai alloy powder, or may be attached so as to partially cover the periphery of the fesai alloy powder, and a part of the surface of the fesai alloy powder is exposed. The insulating resin may be attached to the surface of each particle of the FeSiAl-based alloy powder, may be attached to the surface of an aggregate of the FeSiAl-based alloy powder, or may be attached in a mixed form of these attachments.
As the insulating resin, a silane coupling agent, a silicone resin, or a mixture of these may be used. That is, the silane coupling agent and the silicone resin may be used as a single component, or may be used by mixing the silane coupling agent with the silicone resin.
The insulating layer may be a single layer or a multilayer. For example, the insulating layer may include a plurality of layers divided into respective layers according to kinds, or may be composed of a single layer in which one or more kinds of insulating materials are mixed. In the present embodiment, the insulating layer containing the silane coupling agent and the silicone resin is formed around the FeSiAl-based alloy powder.
As the silane coupling agent, there can be used an aminosilane-based, epoxysilane-based or isocyanurate-based silane coupling agent, and 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane or tris- (3-trimethoxysilylpropyl) isocyanurate is particularly preferable. The amount of the silane coupling agent added is preferably 0.05wt% or more and 1.0wt% or less with respect to the FeSiAl-based alloy powder. When the amount of the silane coupling agent added is in the above range, the flowability of the FeSiAl-based alloy powder can be improved, and the density, magnetic properties, and strength properties of the formed powder magnetic core can be improved.
The silicone resin is a resin having a siloxane bond (Si-O-Si) in the main skeleton. By using a silicone resin, a coating film having excellent flexibility can be formed. Examples of the silicone resin include methyl-based, methylphenyl-based, propylphenyl-based, epoxy-modified, alkyd-modified, polyester-modified, and rubber-modified silicone resins. Among them, when a methylphenyl silicone resin is used, an insulating layer having a small heating loss and excellent heat resistance can be formed. The amount of the silicone resin added to the FeSiAl alloy powder is preferably 0.6 to 2.0wt%. If the amount is less than 0.6wt%, the film cannot function as an insulating film, and the eddy current loss increases, resulting in a decrease in magnetic properties. If the amount is more than 2.0wt%, the density of the dust core is lowered.
When a silane coupling agent is added as an insulating resin, a mixture of the FeSiAl alloy powder and the silane coupling agent is heated and dried. The drying temperature is preferably 25 ℃ or more and 200 ℃ or less. The reason for this is that: some drying temperatures are lower than 25 ℃, and the solvent remains and the insulating film may be incomplete. On the other hand, the reason for this is that: if the drying temperature is higher than 200 ℃, the decomposition proceeds and the insulating film cannot be formed in some cases. The drying time was about 2 hours.
When a silicone resin is added as an insulating resin, a mixture of FeSiAl alloy powder and the silicone resin is heated and dried. The drying temperature is preferably 100 ℃ or higher and 200 ℃ or lower. The reason for this is that: if the drying temperature is less than 100 ℃, the formation of the insulating film may be incomplete, and the eddy current loss may increase. On the other hand, the reason for this is that: if the drying temperature is more than 200 ℃, the powder becomes an inorganic substance and fails to function as a binder, and the shape retention is deteriorated, whereby the density and magnetic permeability of the molded article may be lowered. The drying time was about 2 hours.
(4) Second adding step
The second addition step is a step of adding a second lubricant to the FeSiAl-based alloy powder on which the insulating layer has been formed through the coating step. As the second lubricant, it is not necessarily required to use the same lubricant as the first lubricant. As the second lubricant, in addition to the kind of the first lubricant, a lubricant having a melting point not included in the range of 59 ℃ to 135 ℃ such as ethylene bisstearylamide (ethylene bisstearylamide) may be used.
However, as with the melting point of the first lubricant, it is preferable to use a lubricant having a melting point of 59 ℃ or higher and 135 ℃ or lower as the second lubricant. As shown in condition C described later, the melting point of the first lubricant is important as a condition for reducing hysteresis loss while having high magnetic permeability. Therefore, by setting the second lubricant to be also within the range of the melting point of the first lubricant, it is possible to prevent the fear of adding the lubricants in the wrong order.
More preferably, the second lubricant is the same lubricant as the first lubricant. That is, in the case of using stearic acid for the first lubricant, it is also preferable to use stearic acid for the second lubricant. By making the first lubricant and the second lubricant of the same kind, it is possible to prevent the fear of wrong sequential addition, and it is not necessary to prepare two kinds of lubricants. In addition, the amount of the catalyst used can be easily controlled, and thus productivity is improved.
The amount of the second lubricant added is preferably 0.2wt% or more and 0.7wt% or less with respect to the FeSiAl alloy powder. Further, the total amount of the first lubricant and the second lubricant added to the FeSiAl alloy powder is preferably 0.3wt% or more and 0.8wt% or less. By setting the above range, the sliding of the powder becomes good and the density is improved.
(5) Pressure forming process
The press molding step is a step of press molding the FeSiAl alloy powder on which the insulating layer is formed to produce a powder compact. First, a FeSiAl alloy powder was charged into a die, and then the pressure at the time of molding was set to 10ton/cm 2 ～20ton/cm 2 The resultant was pressed to obtain a compact.
(6) Heat treatment step for molded article
The molded body heat treatment step is a step of heat-treating the molded body produced through the press molding step. In the compact heat treatment step, the heat treatment is performed in a non-oxidizing environment such as a nitrogen gas, a mixed gas of nitrogen and hydrogen, a low-oxygen environment of 0.01%, or the like, at a temperature of 600 ℃ or higher and lower than a temperature at which the insulating layer formed around the FeSiAl alloy powder is destroyed (for example, 850 ℃). The powder magnetic core is produced by passing through the molded body heat treatment step.
The powder magnetic core produced through the above steps satisfies the following conditions a to C. By satisfying these three conditions, it is possible to reduce hysteresis loss while improving magnetic permeability.
(condition a) the FeSiAl alloy powder before the first addition step has a nonuniform strain in the range of 0.232 to 0.325, and a peak ratio in the range of 0.02 to 0.03.
(Condition B) the lubricant was added twice.
(Condition C) the melting point of the first lubricant is 59 ℃ or higher and 135 ℃ or lower.
In addition, the second lubricant is preferably the same kind of lubricant as the first lubricant. As shown in condition C, it is important that the melting point of the first lubricant is 59 ℃ or higher and 135 ℃ or lower. Therefore, the second lubricant can prevent the fear of adding in wrong order by using the same kind of lubricant as the first lubricant.
(examples)
The present invention will be described in more detail based on examples. The present invention is not limited to the following examples.
Powder magnetic cores of example 1, example 2, and comparative examples 1 to 7 were produced. The powder magnetic cores of example 1, example 2, and comparative examples 1 to 7 are different in whether or not the following conditions a to C are satisfied. Table 1 shows whether or not the powder magnetic cores of example 1, example 2, and comparative examples 1 to 7 satisfy the following conditions a to C.
(condition a) the FeSiAl alloy powder before the first addition step has a nonuniform strain in the range of 0.232 to 0.325, and a peak ratio in the range of 0.02 to 0.03.
(Condition B) the lubricant was added twice.
(Condition C) the melting point of the lubricant is 59 ℃ or higher and 135 ℃ or lower.
[ Table 1]
Example 1 was prepared as follows so as to satisfy all of the conditions a to C. First, a FeSiAl alloy powder was passed through a sieve having a mesh size of 150 μm, and then heat-treated at 450 ℃ for 2 hours in a nitrogen atmosphere.
Here, the crystal structure of the FeSiAl alloy powder subjected to the powder heat treatment was observed. Specifically, the ratio of the peak of the crystal plane index 220 to the peak of the crystal plane index 111 and the uneven strain were measured by X-ray diffraction. The X-ray diffraction apparatus used was a fully automatic X-ray diffraction apparatus (D2 fassel (PHASER): cu tube ball, manufactured by BRUKER corporation, X-ray wavelength λ =0.154 nm). The results are shown in Table 1.
After the measurement, 0.3wt% of stearic acid (melting point 59 ℃) based on the FeSiAl alloy powder was added as a first lubricant and mixed. Thereafter, 0.5wt% of a silane coupling agent and 1.2wt% of a silicone resin were mixed in this order with respect to the FeSiAl alloy powder, and the mixture was dried at 150 ℃ for 2 hours.
In order to eliminate the aggregation, the powder for dust core was passed through a 850 μm mesh sieve, and stearic acid, which was the same as the first lubricant, was added as a second lubricant in an amount of 0.2wt% based on the FeSiAl alloy powder. The FeSiAl alloy powder to which the second lubricant was added was charged into a die and press-molded to obtain powder compacts each having an outer diameter of 16.5mm, an inner diameter of 11.0mm and a height of 5.0 mm. The pressure for press forming was set at 15ton/cm 2 The process is carried out. Thus, a powder compact was produced. After the powder compact was produced, the powder compact was subjected to a heat treatment at a temperature of 700 ℃ for 2 hours in a nitrogen atmosphere. Thus, a powder magnetic core of example 1 was produced.
In example 2, the heat treatment temperature of only the fesai alloy powder was different from that of example 1. Example 2 a heat treatment of the powder was carried out at 550 ℃.
The comparative example 1 is different from the example 1 in that: the lubricant was not mixed twice, and ethylene bis stearamide (melting point 140 ℃ C.) was used as a lubricant, and condition B and condition C were not satisfied. That is, in comparative example 1, a silane coupling agent was mixed with a silicone resin without adding a lubricant to the FeSiAl alloy powder subjected to the powder heat treatment, and then 0.5wt% of ethylene bis stearamide as a lubricant was mixed with the FeSiAl alloy powder on which the insulating layer was formed. Other production methods and production conditions were the same as in example 1.
The comparative example 2 is different from the example 1 in that: the FeSiAl alloy powder was not heat-treated, and ethylene bis-stearamide (melting point: 140 ℃) was used as the first lubricant and the second lubricant, so that the conditions A and C were not satisfied. That is, in comparative example 2, the peak ratio and the uneven strain were measured without performing the heat treatment of the powder, and then 0.3wt% of ethylene bis stearamide as the first lubricant and further 0.2wt% of ethylene bis stearamide as the second lubricant were mixed. Other manufacturing methods and manufacturing conditions were the same as in example 1.
Comparative example 3 is different from example 1 in that: the FeSiAl alloy powder was not subjected to heat treatment and mixed with a lubricant twice, and the conditions A and B were not satisfied. That is, in comparative example 3, the peak ratio and the uneven strain were measured without performing the powder heat treatment, and thereafter, the silane coupling agent was mixed with the silicone resin without adding the lubricant, and thereafter, 0.2wt% of stearic acid (melting point 135 ℃) as a lubricant was mixed with the FeSiAl-based alloy powder on which the insulating layer was formed. Other manufacturing methods and manufacturing conditions were the same as in example 1.
Comparative example 4 is different from example 1 only in that ethylene bis stearamide (melting point 140 ℃ C.) is used as the first lubricant and the second lubricant, and does not satisfy condition C. Other production methods and production conditions were the same as in example 1.
Comparative example 5 is different from example 1 only in that no heat treatment is performed on the fesai alloy powder, and the other production methods and production conditions are the same as in example 1. That is, comparative example 5 does not satisfy condition a. In comparative example 6, the heat treatment temperature of only the fesai alloy powder was different from that of example 1. That is, the production method and production conditions in comparative example 6 were the same as those in example 1, except that the heat treatment of the FeSiAl-based alloy powder was performed at 800 ℃. That is, comparative example 6 does not satisfy condition a.
Comparative example 7 is different from example 1 only in that the lubricant was not mixed twice, and does not satisfy condition B. That is, in comparative example 7, the lubricant was not added to the FeSiAl-based alloy powder subjected to the powder heat treatment, the silane coupling agent was mixed with the silicone resin, and then, 0.5wt% of stearic acid (melting point 135 ℃) as the lubricant was mixed with the FeSiAl-based alloy powder on which the insulating layer was formed (melting point 135 ℃). Other production methods and production conditions were the same as in example 1.
The powder magnetic cores thus prepared were wound with 17-turn windings of the primary winding and 17-turn windings of the secondary winding using a copper wire having a diameter of 0.5mm, and hysteresis loss was measured. The measurement conditions were a frequency of 100kHz and a maximum magnetic flux density Bm =100mT. The iron loss, hysteresis loss and eddy current loss were calculated by using a BH analyzer (SY-8219, available from Tokyo measurements Co., ltd.) as a magnetic measuring instrument. The calculation is performed by calculating a hysteresis loss coefficient and an eddy current loss coefficient by a least square method using the following expressions (1) to (3) with respect to the frequency curve of the iron loss.
Pcv＝Kh×f+Ke×f 2 ··(1)
Ph＝Kh×f··(2)
Pe＝Ke×f 2 ··(3)
Pcv (calculated volume): iron loss
Kh: coefficient of hysteresis loss
And Ke: coefficient of eddy current loss
f: frequency of
Ph: hysteresis loss
Pe: loss of eddy current
Further, the magnetic permeability of each powder magnetic core was measured. The permeability was calculated as an amplitude permeability when the maximum magnetic flux density Bm was set at the time of measuring the iron loss, using an inductance, capacitance, and resistance (LCR) meter (4284A, manufactured by Agilent Technologies, ltd.). The magnetic permeability is measured by measuring the initial magnetic permeability (0 kA/m) at which the magnetic field is zero without superimposing a direct current.
The measurement results are shown in table 2. Fig. 1 shows graphs in which the permeability and hysteresis loss of examples 1 and 2 and comparative examples 1 to 7 were compared with each other.
[ Table 2]
As shown in Table 2 and FIG. 1, the hysteresis loss (Ph) of examples 1 and 2 satisfying the three conditions was 200 (kw/m) 3 ) Less than or equal to the right and left, and a magnetic permeability of 150 or more, and can satisfy both of the three conditions as compared with comparative examples 1 to 7 in which one or two of the three conditions are not satisfiedReduction of hysteresis loss and high permeability.
Indeed, the permeability of comparative example 5 satisfying the conditions B and C was 162, and the hysteresis loss of comparative example 6 satisfying the conditions B and C was 200 (kw/m) 3 ). However, the hysteresis loss of comparative example 5, in which the uneven strain was 0.381 and the peak ratio was 0.016, was 214 (kw/m) 3 ) The hysteresis loss is high, and both the reduction of the hysteresis loss and the high magnetic permeability cannot be achieved. In addition, the magnetic permeability of comparative example 6 in which the uneven strain was 0.044 and the peak ratio was 0.080 was 121, and the magnetic permeability was not improved, so that both reduction of hysteresis loss and high magnetic permeability could not be achieved. Therefore, as shown in examples 1 and 2, it was confirmed that, as condition a, when the uneven strain is in the range of 0.232 to 0.325 inclusive and the peak ratio is in the range of 0.02 to 0.03 inclusive, both reduction of hysteresis loss and high magnetic permeability can be achieved.
Next, examples 3 to 6, comparative examples 9 and 10 were prepared in which only the types of the first lubricant and the second lubricant in example 1 were changed. Other manufacturing methods and manufacturing conditions were the same as in example 1. That is, examples 3 to 6 and comparative examples 9 and 10 satisfy conditions a and B. The types of the first lubricant and the second lubricant used in the examples and the comparative examples are shown in table 3 below. The lubricants shown in table 3 below are all powders except for capric acid, and the average particle diameter shown in table 3 is the particle diameter of median particle diameter D50.
[ Table 3]
In example 3, zinc stearate (melting point 135 ℃) was used as the first lubricant and the second lubricant. In example 4, zinc stearate (melting point 120 ℃ C.) was used as the first lubricant and the second lubricant. In example 5, magnesium octadecanoate (melting point 115 ℃) was used as the first lubricant and the second lubricant. In example 6, a fatty acid derivative (melting point 80 ℃) was used as the first lubricant and the second lubricant.
On the other hand, in comparative example 9, lauric acid (melting point 43 ℃) was used as the first lubricant, and stearic acid (melting point 59 ℃) was used as the second lubricant. In comparative example 10, capric acid (melting point 17 ℃ C.) was used as the first lubricant, and stearic acid (melting point 59 ℃ C.) was used as the second lubricant.
In each of the examples and comparative examples, magnetic permeability and hysteresis loss were measured. The measurement method, measurement conditions, and measurement equipment are the same as described above. The measurement results are shown in table 4. Fig. 2 is a graph showing a relationship between the melting point and the magnetic permeability of the first lubricant, and fig. 3 is a graph showing a relationship between the melting point and the hysteresis loss of the first lubricant.
[ Table 4]
| Magnetic permeability | Ph(kw/m 3 ) | |
| Comparative example 4 | 131 | 212 |
| Example 3 | 145 | 179 |
| Example 4 | 152 | 166 |
| Example 5 | 148 | 177 |
| Example 6 | 153 | 197 |
| Example 1 | 156 | 195 |
| Comparative example 9 | 126 | 228 |
| Comparative example 10 | 109 | 231 |
First, when comparative examples 9 and 10 were observed, the hysteresis loss was as high as 230 (kw/m) 3 ) On the other hand, the permeability is also lower than 130. In comparative examples 9 and 10, the second lubricant satisfied condition C, but the first lubricant did not satisfy condition C. Therefore, it was confirmed that in the first lubricant, it is important to satisfy the condition C.
The first lubricant has a melting point of 59 ℃ to 135 ℃ and has a magnetic permeability of 140 or higher and a hysteresis loss of 200 or less (kw/m) or less in examples 1, 3 and 6 3 ) The magnetic permeability can be high and the hysteresis loss can be reduced. On the other hand, as a result of comparative example 1 in which the melting point of the first lubricant is higher than 135 ℃ or comparative examples 9 and 10 in which the melting point of the first lubricant is lower than 59 ℃, the permeability is lower than about 130 and the hysteresis loss is higher than 210 (kw/m) 3 ). Therefore, it was confirmed that, as condition C, when the melting point of the first lubricant is in the range of 59 ℃ to 135 ℃, the magnetic permeability can be high and the hysteresis loss can be reduced at the same time.
The magnetic permeability of examples 1, 3 to 6 was high, which was higher than 140, but the magnetic permeability of examples 1, 4 and 6 was extremely high, which exceeded 150. Therefore, it was confirmed that stearic acid, zinc stearate (melting point 120 ℃ C., average particle diameter 0.54 μm), and fatty acid derivatives were used as the first lubricant to achieve particularly high magnetic permeability.
Since the magnetic permeability can be increased by increasing the density of the core, the soft magnetic powder is molded at a high molding pressure. However, as the molding pressure is increased, friction between the soft magnetic powders and strain in the soft magnetic powder are more likely to occur, and hysteresis loss is deteriorated. Therefore, it is difficult to achieve both high permeability and a reduction in hysteresis loss.
However, as a result of diligent studies by the present inventors, it has been found that: when the lubricant is added twice, the type of the lubricant for the first time is in the range of the melting point of 59 to 135 ℃, the non-uniform strain of the FeSiAl alloy powder before the lubricant is added is in the range of 0.232 to 0.325, and the peak ratio is in the range of 0.02 to 0.03, the magnetic permeability can be high and the reduction of the hysteresis loss can be achieved at the same time, and it is confirmed that the above-described situation is satisfied.
(other embodiments)
In the present specification, the embodiments of the present invention have been described, but the embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments described above can be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. The embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.
Claims (5)
1. A method of manufacturing a powder magnetic core, comprising:
a first addition step of adding a first lubricant to the FeSiAl alloy powder;
a coating step of coating the FeSiAl-based alloy powder subjected to the first addition step with an insulating resin; and
a second addition step of adding a second lubricant to the FeSiAl alloy powder subjected to the coating step,
the first lubricant has a melting point of 59 ℃ or higher and 135 ℃ or lower,
a ratio of a peak of a crystal plane index 220 to a peak of a crystal plane index 111 in X-ray diffraction of the FeSiAl alloy powder before the first addition step is 0.020 or more and 0.030 or less,
and the number of the first and second electrodes,
the value of the uneven strain based on the following formula (1) is 0.232 to 0.325,
in the formula (1), β represents an integral width, D represents a crystallite size, θ represents a diffraction angle, λ represents a wavelength of an X-ray, and η represents an uneven strain.
2. The method of manufacturing a powder magnetic core according to claim 1,
the first lubricant is the same kind as the second lubricant.
3. The method of manufacturing a powder magnetic core according to claim 1,
the first lubricant is any one of stearic acid, zinc stearate, magnesium stearate or fatty acid derivatives.
4. The method of manufacturing a powder magnetic core according to claim 2,
the first lubricant is any one of stearic acid, zinc stearate, magnesium stearate or fatty acid derivatives.
5. The method of manufacturing a powder magnetic core according to any one of claims 1 to 4,
the magnetic permeability is 140 or more.
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