JP2014204051A - Soft magnetic flat-particle powder, and magnetic sheet arranged by use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide soft magnetic flat-particle powder for a magnetic sheet which has a high magnetic permeability and can be used for various electronic devices.SOLUTION: Soft magnetic flat-particle powder comprises 84.0-96.0 mass% of Fe, 3.0-8.5 mass% of Si, and 1.0-13.0 mass% of Al. The soft magnetic flat-particle powder satisfies the formula (1) below, and has an aspect ratio of 15 or larger. In addition, at least one element of Ti, V, Cr, Mn, Co, Ni and Cu may be substituted for part of Fe within a range of 5.0% or less. 2Si%-Al%≤15.0 Formula (1).

Description

  The present invention relates to a soft magnetic flat powder for a magnetic sheet having a high magnetic permeability, which is used in various electronic devices, and a magnetic sheet containing the same.

  Conventionally, a magnetic sheet containing a soft magnetic flat powder has been used as an electromagnetic wave absorber and an RFID (Radio Frequency Identification) antenna. In recent years, it has come to be used also for a position detection device called a digitizer. This digitizer includes an electromagnetic induction type as disclosed in, for example, Japanese Patent Laid-Open No. 2011-22661 (Patent Document 1), and is transmitted from a coil built in the tip of a pen-shaped position indicator. The indicated position is detected by reading the high-frequency signal with a loop coil built in the panel-shaped position detector. Here, for the purpose of increasing the detection sensitivity, a sheet serving as a magnetic path for the high-frequency signal is disposed on the back surface of the loop coil.

  As the sheet serving as the magnetic path, a magnetic sheet containing a soft magnetic flat powder or a soft magnetic amorphous alloy foil bonded thereto is applied. In the case of using a magnetic sheet, the entire detection panel can be made into one sheet, so that excellent uniformity can be obtained without any detection failure at the bonded portion such as an amorphous foil.

  Although the digitizer function is applied to smartphones, notebook PCs, and the like, such mobile electronic devices are severely demanded for miniaturization, and there is a high demand for thinning magnetic sheets used as magnetic path sheets. Such thinning requires a higher magnetic permeability than conventionally used electromagnetic wave absorbers and RFID antenna magnetic sheets. Therefore, a magnetic sheet having a high magnetic permeability is required at a digitizer operating frequency of several hundred kHz.

  Conventionally, powder made of Fe-Si-Al alloy, Fe-Si alloy, Fe-Ni alloy, Fe-Al alloy, Fe-Cr alloy, etc. is flattened on the magnetic sheet by an attritor (attrition mill) or the like. Has been added. This is because, in order to obtain a magnetic sheet having a high magnetic permeability, a so-called “Olendorff's formula” uses a soft magnetic powder having a high magnetic permeability, and a flatness having a high aspect ratio in the magnetization direction in order to reduce the demagnetizing field. This is because it is important to use powder and to highly fill the magnetic sheet with soft magnetic powder.

  In particular, the Fe-Si-Al alloy called Sendust has both the magnetocrystalline anisotropy and magnetostriction zero in the composition of Fe-9.6% Si-5.4% Al, thereby obtaining a remarkably high magnetic permeability. Therefore, it is currently widely used for electromagnetic wave absorbers. For example, as disclosed in Japanese Patent Application Laid-Open No. 2005-281783 (Patent Document 2), it is proposed to use an Fe—Si—Al alloy containing 8 to 11 wt% Si and 4 to 7 wt% Al. . In addition, as described in paragraph [0025] of Patent Document 2 as a preferable range, components having Si of 9.0 to 10.5 wt% and Al of 4.5 to 6.5 wt% are also shown above. In addition, it is known as a composition capable of obtaining the highest magnetic permeability, and a magnetic sheet having excellent magnetic properties can be obtained by using a flat powder having this composition.

  On the other hand, Japanese Patent Application Laid-Open No. 2005-209753 (Patent Document 3) discloses a soft magnetic flat powder, and Japanese Patent Application Laid-Open No. 2002-299113 (Patent Document 4) includes a soft magnetic powder and a compact using the same. A magnetic core is disclosed. JP-A-2005-123531 (Patent Document 5) discloses a flat powder used for an electromagnetic wave absorber. Further, Japanese Patent Application Laid-Open No. 10-330806 (Patent Document 6) proposes a method for producing a coagulated metal powder, and Japanese Patent Application Laid-Open No. 62-13207 (Patent Document 7) proposes a method for producing a metal powder. Yes.

JP 2011-22661 A Japanese Patent Laid-Open No. 2005-281783 JP 2005-209753 A JP 2002-299113 A Japanese Patent Laid-Open No. 2005-123531 Japanese Patent Laid-Open No. 10-330806 JP 62-13207 A JP 2010-196123 A JP 2012-9825 A

  However, in the magnetic sheet used for the digitizer magnetic path sheet disclosed in Patent Documents 1 and 2 as described above, there is a severe demand for higher magnetic permeability, which cannot be handled by the conventional technology. It is becoming. On the other hand, an oxide film as disclosed in Patent Documents 3 and 4 is not required. Moreover, what satisfy | fills the component composition and aspect ratio as used in the field of this invention is not described in each Example.

  Further, the oxygen content of the pre-flat powder described in Patent Document 5 is not a problem at all. In addition, as in Patent Documents 3 and 4, those that satisfy the component composition referred to in the present invention are not described in the examples. Furthermore, it is not necessary to positively add oxygen to the atomizing gas as disclosed in Patent Documents 6 and 7. In addition, in Examples of Patent Document 7, as in Patent Documents 3 and 4, those that satisfy the component composition and aspect ratio of the present invention are not described.

  In order to obtain the above-described problems of Patent Documents 1 and 2 and characteristics not found in the techniques disclosed in Patent Documents 3 to 7, the inventors have intensively developed and, as a result, obtained the highest magnetic permeability particularly as an alloy composition. As a soft magnetic flat powder capable of realizing a high magnetic permeability when used in a magnetic sheet, the composition deliberately deviated from Fe-9.6% Si-5.4% Al is obtained. The composition range obtained was found and the present invention was achieved.

The gist of the invention is that
(1) The composition is mass%, Fe is 84.0% or more and 96.0% or less, Si is 3.0% or more and 8.5% or less, Al is 1.0% or more and 13.0% or less, A soft magnetic flat powder satisfying the following formula (1) and having an aspect ratio of 15 or more.
2Si% -Al% ≦ 15.0 Formula (1)

  (2) In the above (1), a part of Fe is substituted with one or more elements of Ti, V, Cr, Mn, Co, Ni, and Cu within a range of 5.0% or less. Soft magnetic flat powder. (3) A magnetic sheet comprising the soft magnetic flat powder described in (1) or (2).

  As described above, according to the present invention, it is possible to provide a soft magnetic flat powder capable of realizing a high magnetic permeability when used as a magnetic sheet and a high magnetic permeability magnetic sheet using the same.

It is a figure which shows the initial magnetic permeability of a Fe-Si-Al alloy. It is a figure which shows the map of K and (lambda) s of a Fe-Si-Al alloy. FIG. 10 is a diagram showing μ ′ of Experiment A. It is a figure which shows μ '' of experiment A. It is a figure which shows the aspect ratio of Experiment A. FIG. 4 is a diagram showing the crystal grain size of Experiment A. It is a figure which shows the coercive force of Experiment A. The result of Experiment B is a diagram showing the influence of the aspect ratio on μ ′.

Hereinafter, the present invention will be described in detail.
A feature of the present invention is that, when used in a magnetic sheet after being flattened in a composition region that has been conventionally considered to obtain the highest magnetic permeability, Fe-9.6% Si-5.4% Al. In addition, a composition range in which higher magnetic permeability can be obtained has been found. In other words, this is a technique obtained by making the composition range positively deviated from the vicinity of the composition at which the highest magnetic permeability known so far is obtained.

  Many examples of flattening an Fe-Si-Al alloy and using it for a magnetic sheet have been seen in the past, and many patents have been filed. However, the compositions proposed for the magnetic sheet are all in the vicinity of Fe-9.6% Si-5.4% Al, and the compositions actually evaluated are all Fe-9.6%. It is in the immediate vicinity of Si-5.4% Al. This is considered to be due to the specificity of the composition of Fe-9.6% Si-5.4% Al. That is, for example, as shown in FIG. 1, the initial permeability of the Fe—Si—Al alloy is remarkably high only in a very small composition region of Fe-9.6% Si-5.4% Al. It has been known. Therefore, it is considered that a composition slightly deviating from this composition is not considered to be actively applied for a high magnetic permeability magnetic sheet.

  In contrast, the inventors made an alloy powder in a wide range of composition deviated from Fe-9.6% Si-5.4% Al, and performed X-ray diffraction on the flattened powder. It was. As a result, it was found that significant crystal orientation anisotropy was observed in the thickness direction of the flattened powder and in a plane perpendicular thereto, and the (100) direction was aligned with the thickness direction of the flattened powder. That is, when X-ray diffraction was performed using Cu—Kα rays on the surface of the sheet in which the thickness direction of the flat powder was matched with the thickness direction of the magnetic sheet by pressing, the diffraction angle 2θ was compared with the spherical powder before the attritor. A peak around = 65 ° was clearly observed to be high. Furthermore, when the magnetic permeability of the magnetic sheet produced using these powders was measured, a higher magnetic permeability was obtained in a wide Al content range on the low Si side than Fe-9.6% Si-5.4% Al. I found out that The details of the factor that the magnetic sheet using the flat powder in this composition range shows the magnetic permeability superior to that of the Fe-9.6% Si-5.4% Al composition is not clear but is estimated as follows. The

  Within the scope of the present invention, Fe is 84.0% or more and 96.0% or less, Si is 3.0% or more and 8.5% or less, Al is 1.0% or more and 13.0% or less, and 2Si The composition of% -Al% ≦ 15.0 is a region in which the magnetocrystalline anisotropy constant (K) is positive and the saturation magnetostriction constant (λs) is positive from near zero, for example, from the conventionally known FIG. It is. Here, the magnetocrystalline anisotropy constant in a cubic metal is a positive value when the (100) direction is the easy axis and a negative value when the (111) direction is the easy axis. .

  As described above, since the flattened powder has (100) aligned in the thickness direction, there are many (010) and (001) easy-magnetization axis directions in the in-plane direction perpendicular to the thickness direction. It is considered that the (111) direction, which is the hard axis of magnetization, hardly exists. When used as a magnetic sheet, since the in-plane direction perpendicular to the thickness of the flat powder is the external magnetization direction, such an alloy having a positive magnetocrystalline anisotropy constant is in the direction of external magnetization when using the magnetic sheet. It is presumed that there are many coincidence directions of easy magnetization as crystals.

  Further, a positive saturation magnetostriction constant means that when the magnetic material is magnetized, it extends in the magnetization direction, and slightly contracts in the perpendicular plane. In general, a magnetic sheet is produced by mixing a soft magnetic flat powder with resin or rubber, and then extending the sheet into a sheet shape by a press or a roll. Accordingly, the soft magnetic flat powder is oriented so that the in-plane direction of the sheet and the in-plane direction of the flat powder coincide with each other by compression by a press or roll. At the same time, since the sheet is compressed in the thickness direction, the flat powder remains pressed in the thickness direction in the magnetic sheet. In such a state, it is considered that when a flat powder having a positive saturation magnetostriction constant is magnetized in the in-plane direction, the powder contracts slightly in the thickness direction perpendicular thereto. This shrinkage is presumed to work in the direction in which the flat powder described above is pushed in the thickness direction and the residual stress is reduced.

  As described above, when used as a magnetic sheet, the external magnetization direction and the easy magnetization axis direction coincide with each other, and the residual stress is reduced by being pushed in the thickness direction by extending in the external magnetization direction. This is considered to promote the magnetization rotation in the in-plane direction of the flat powder against the high-frequency magnetic field from the outside, and in this application, compared with the usual isotropic application, the magnetocrystalline anisotropic constant and saturation It is presumed that a magnetic sheet having a magnetic permeability higher than that of an Fe-9.6% Si-5.4% Al composition in which both magnetostriction constants are zero is obtained.

  Furthermore, in the composition range of this invention, it turned out that the deformation | transformation behavior of the powder particle by flat processing differs also compared with Fe-9.6% Si-5.4% Al which is a normal high magnetic permeability composition. That is, the present inventors have also found that the composition range of the present invention is deformed to an aspect ratio higher than that of the Fe-9.6% Si-5.4% Al composition. Thereby, it is possible to reduce the demagnetizing field generated in the magnetic sheet, and it is considered that there is an effect of promoting high magnetic permeability of the magnetic sheet. This deformation behavior is considered to be influenced by mechanical mechanical properties such as hardness and ductility of the powder particles.

  Furthermore, it was found that the composition range of the present invention is different from the Fe-9.6% Si-5.4% Al composition in the crystal grain refinement behavior by flattening. In flattening by mechanical processing such as an attritor, a large plastic strain is introduced into the powder, and thereby the crystal grains of the flat powder are refined. In general, the influence of the crystal grain size on the permeability and coercive force is considered to change the behavior around 20 to 40 nm, but the crystal grain size of the flat powder used in the magnetic sheet is approximately 50 nm or more, In this crystal grain size region, the magnetic permeability decreases and the coercive force increases as the crystal grain size decreases. Here, when the composition of the scope of the present invention and the Fe-9.6% Si-5.4% Al composition were compared for the effect of grain refinement by flattening, the composition of the scope of the present invention had a relatively larger crystal grain size. Found that it was great.

  Accordingly, it is considered that the composition within the range of the present invention can suppress the decrease in the magnetic permeability due to the flattening process to be relatively small as compared with the Fe-9.6% Si-5.4% Al composition. The cause of this phenomenon is considered as follows. In general, semimetal elements such as B, C, and P, including Si, are elements that promote amorphous formation with respect to Fe. Therefore, it is considered that Si has an effect of promoting amorphization and nanocrystallizing by introducing mechanical strain such as mechanical alloy. From this, the composition within the range of the present invention is presumed that the crystal grains after flattening are relatively large because Si is lower than the Fe-9.6% Si-5.4% Al composition.

  As described above, the composition within the scope of the present invention is based on magnetic characteristics such as magnetocrystalline anisotropy and magnetostriction, mechanical and mechanical characteristics such as hardness and ductility, and a plurality of characteristics that are considered to be due to grain refinement behavior. Only when used in this application, the present inventors have found that the magnetic permeability is superior to that of the Fe-9.6% Si-5.4% Al composition, and the present invention has been achieved.

  In addition, as an examination example of the composition deviating from the Fe-9.6% Si-5.4% Al composition, Patent Document 8 (Japanese Patent Laid-Open No. 2010-196123) that considers oxidation during flattening or a high temperature is used. Although there exists patent document 9 (Unexamined-Japanese-Patent No. 2012-9825) regarding a powder magnetic core etc., the former has composition of Fe-9.6% Si-5.4% Al more strictly in consideration of the composition shift by oxidation. It is intended to obtain high permeability. The latter is not accompanied by flat processing, and the use and usage environment (especially the use temperature) are completely different. ing.

  The method for producing a flat powder in the present invention can be performed by a conventionally proposed method. For example, it is possible to improve the magnetic permeability by heat treatment after preparing alloy powder as a raw material by various atomizing methods, flattening this by various milling apparatuses. In particular, considering the production efficiency of the raw material powder and the flat processing efficiency, a method of producing the raw material powder by the water atomizing method or the gas atomizing method and flattening by an attritor is preferable.

  In addition, since the powder after flattening has a large amount of plastic strain and crystal grains are refined, it can be eliminated by heat treatment that has been proposed in the past, and the magnetic permeability can be improved. In consideration of magnetic susceptibility deterioration, heat treatment in a vacuum or in an inert atmosphere is preferable. Furthermore, it is possible to improve the corrosion resistance or the dispersibility in rubber by a conventionally proposed surface treatment represented by a cyan coupling agent. In addition, a magnetic sheet can be produced by a conventionally proposed method. For example, it can be produced by mixing a flat powder with a solution obtained by dissolving chlorinated polyethylene or the like in toluene, and applying and drying the mixture with various presses or rolls.

Fe is 84.0% or more and 96.0% or less. In the present invention, Fe is an essential element for imparting ferromagnetism to the flat powder and improving the magnetic permeability of the magnetic sheet. However, if the content is less than 84.0% or exceeds 96.0%, the magnetic permeability of the magnetic sheet deteriorates. If it is less than 84.0%, it is considered that the saturation magnetic flux density of the flat powder is excessively low, and if it exceeds 96.0%, the crystal magnetic anisotropy constant of the flat powder is excessively large. Preferably it is more than 86.0% and less than 94.0%, more preferably more than 85.0% and less than 92.0%.

Si is not less than 3.0% and not more than 8.5% In the present invention, Si is an essential element that increases the permeability of the flat powder and improves the permeability of the magnetic sheet. However, if it is less than 3.0% or exceeds 8.5%, the magnetic permeability of the magnetic sheet deteriorates. If it is less than 3.0%, it is considered that the crystal magnetic anisotropy constant of the flat powder becomes excessively large, and if it exceeds 8.5%, the crystal magnetic anisotropy constant and / or the saturation magnetostriction constant of the flat powder is increased. It is a negative value, and the hardness of the powder particles is excessively increased, the aspect ratio of the flat powder is decreased, and further, the compound effect of excessively promoting the grain refinement in the flat processing is obtained. This is probably because of this. Preferably, it is more than 3.5% and less than 8.0%, more preferably more than 4.0% and less than 7.0%.

Al is 1.0% or more and 13.0% or less In the present invention, Al is an essential element that increases the permeability of the flat powder and improves the permeability of the magnetic sheet. However, if it is less than 1.0% or exceeds 13.0%, the magnetic permeability of the magnetic sheet deteriorates. If it is less than 1.0%, it is considered that the magnetocrystalline anisotropy constant of the flat powder becomes excessively large, and if it exceeds 13.0%, the saturation magnetic flux density of the flat powder becomes excessively low. Preferably it is more than 2.0% and less than 12.0%, more preferably more than 3.5% and less than 11.0%.

2Si% -Al% ≦ 15.0
In the present invention, 2Si% -Al% is a parameter that affects the magnetic permeability of a magnetic sheet using the flat powder of the present invention. That is, when 2Si% -Al% exceeds 15.0, the magnetic permeability of the magnetic sheet deteriorates. Here, 2Si% -Al% = 12.0 generally corresponds to the line of λs = 0 in the range where Fe in FIG. 2 is 84.0% or less. Therefore, when 2Si% -Al% is excessively higher than 12.0, a composition range in which λs is large and has a negative value is obtained. From this, when 2Si% -Al% exceeds 15.0, it is thought that the magnetic permeability of a magnetic sheet deteriorates. Preferably it is less than 13.5%, more preferably less than 12.0%.

The aspect ratio of the flat powder in the present invention is 15 or more. The aspect ratio of the flat powder is a factor that affects the magnetic permeability of the magnetic sheet using the flat powder of the present invention. That is, when the aspect ratio of the flat powder is less than 15, the magnetic permeability of the magnetic sheet is deteriorated. Here, the aspect ratio of the flat powder is obtained by dividing the length in the longitudinal direction of the flat powder by the thickness. In addition, since the permeability of a magnetic sheet improves so that the aspect ratio of flat powder is large, there is no restriction | limiting in particular in an upper limit. However, depending on the manufacturing method and manufacturing conditions of the magnetic sheet, when the aspect ratio is excessively large, it may be difficult to disperse in rubber or resin, or the surface irregularities of the magnetic sheet may increase. . Therefore, the preferable range of the aspect ratio of the flat powder is more than 35 and less than 300, more preferably more than 50 and less than 250.

In a range of 5.0% or less, a part of Fe is replaced with one or more elements of Ti, V, Cr, Mn, Co, Ni and Cu. In the present invention, Ti, V, Cr, Mn, Co, Ni, Cu is a selective element that can replace Fe within a range that does not have a significant adverse effect on the permeability of the flat powder and the permeability of the magnetic sheet. However, if it exceeds 5.0%, the magnetic permeability of the magnetic sheet deteriorates. Preferably less than 3.0% substitution, more preferably less than 1.0% substitution.

Hereinafter, the present invention will be specifically described with reference to examples.
(Experiment A)
[Production of flat powder]
First, the influence of the amount of Fe, Si, and Al on the magnetic permeability of the magnetic sheet was examined. Powders of predetermined components were prepared by the water atomization method and classified to 75 μm or less. Water atomization was performed by using an alumina crucible for melting, discharging molten alloy from a nozzle having a diameter of 5 mm under the crucible, and spraying high pressure water on the molten alloy. This was made into raw material powder and flattened by an attritor. The attritor was a SUJ2 ball with a diameter of 4.8 mm, and was put together with the raw material powder and industrial ethanol into a stirring vessel, and the blade rotation speed was 300 rpm.

  Normally, the aspect ratio changes depending on the processing time in flat processing with an attritor, but the raw material powder is flattened and the aspect ratio increases in the first half of the processing, but the flattened powder after a certain processing time and in the second half of the processing Is crushed and the aspect ratio decreases. Therefore, in this experiment, powder was sampled at every attritor processing time, and the comparison was made at the processing time at which the aspect ratio of each composition was maximum. The flat powder taken out of the stirring vessel after flattening and industrial ethanol were transferred to a stainless steel dish and dried at 80 ° C. for 24 hours. The flat powder thus obtained was heat-treated at 650 ° C. for 2 hours in nitrogen and used for magnetic sheet evaluation.

[Production and evaluation of magnetic sheet]
Chlorinated polyethylene was dissolved in toluene, and the resulting flat powder was mixed and dispersed. This dispersion was applied to a polyester resin to a thickness of about 1 mm and dried at normal temperature and humidity. Then, it pressed at 130 degreeC and the pressure of 15 Mpa, and obtained the magnetic sheet. The volume filling rate of the flat powder in the magnetic sheet was about 50%. Next, this magnetic sheet was cut into a donut shape having an outer diameter of 7 mm and an inner diameter of 3 mm, and impedance characteristics at 1 MHz were measured at room temperature with an impedance measuring device. From the result, permeability (real part of complex permeability: μ ′ ) Was calculated. Similarly, the maximum value of the loss part (imaginary part of complex permeability: μ ″) in the range of 0.1 MHz to 100 MHz was evaluated.

  Further, the cross-section of the obtained magnetic sheet was resin-filled and polished, 50 powders of “length / thickness in the longitudinal direction” were randomly measured from the optical microscope image, and the average was taken as the aspect ratio. Furthermore, X-ray diffraction was performed on the surface of the obtained magnetic sheet, and the crystal grain size was evaluated using the Scherrer equation. Cu-Kα rays were used for X-ray diffraction, and the crystal grain size was calculated from the half width of the main peak near the diffraction angle 2θ = 45 °. And the coercive force of the magnetic sheet was measured with a coercive force meter. The applied magnetic field was 144 kA / m and applied in the in-plane direction of the magnetic sheet.

  These results are shown in Fig. 3 (µ '), Fig. 4 (µ "), Fig. 5 (aspect ratio), Fig. 6 (crystal grain size), and Fig. 7 (coercive force). , 160 or more is less than 160, ○ is 120 or more and less than 140 is Δ, and less than 120 is x. In FIG. 4, the maximum value of μ ″ is 45 or more, and 40 or more and less than 45 is ○. A value of 35 or more and less than 40 was evaluated as Δ, and a value of less than 35 as ×. In FIG. 5, those with an aspect ratio of more than 50 are indicated by ●, those having an aspect ratio of more than 35 and not more than 50 are indicated by ◯, those having an aspect ratio of 15 to 35 are indicated by Δ, and those having an aspect ratio of less than 15 are indicated by ×. In FIG. 6, the crystal grain size of 150 nm or more is indicated by ●, the crystal grain size of 100 nm or more and less than 150 nm is indicated by ◯, the crystal grain size of 80 nm or more and less than 100 nm is indicated by Δ, and the crystal grain size of less than 80 nm is indicated by ×. In FIG. 7, the coercive force is less than 100 A / m, ●, 100 A / m or more and less than 200 A / m, ○, 200 A / m or more and less than 300 A / m, Δ, 300 A / m or more. X.

  From FIG. 3, the magnetic sheets using the flat powder within the composition range of the present invention (the range of the thick dotted line frame) all have a high μ ′ of 120 or more. In addition, it can be seen from FIG. 4 that a high μ ″ is also obtained in the composition range in which a generally high μ ′ is obtained, and the magnetic sheet of the present invention is also excellent in electromagnetic wave absorption characteristics. The ratio is generally obtained with a low Si composition, and it can be seen from Fig. 6 that a relatively large crystal grain size is also obtained with a low Si composition, as shown in Fig. 5. As can be seen from FIG. 7, the coercive force has a Fe-9.6% Si-5.4% Al composition, which is conventionally known as a high permeability composition. It can be seen that the value is extremely low only in the vicinity, however, although it is not as high as the Fe-9.6% Si-5.4% Al composition, Low coercivity This is thought to be due to the relatively large crystal grain size in this composition range.

  Therefore, the coercive force of the alloy composition itself has the lowest value in the vicinity of the Fe-9.6% Si-5.4% Al composition in which both the magnetocrystalline anisotropy constant and the saturation magnetostriction constant are zero. It can be seen that, as a magnetic sheet to which a powder subjected to flattening processing is added, a high magnetic permeability is obtained in the composition region of the present invention that deviates from this composition for a high-frequency magnetic field. This is considered to be caused not only by the magnetic permeability of the alloy composition itself, but also by a composition that provides positive magnetocrystalline anisotropy and saturation magnetostriction constant, high aspect ratio, and large crystal grain size. As a result of X-ray diffraction in this experiment, it was recognized that the (100) direction was anisotropic in the thickness direction of the magnetic sheet in all flat powders.

(Experiment B)
Next, the influence of the aspect ratio on μ ′ of the magnetic sheet was examined. In the composition of Fe-6% Si-7% Al and Fe-3% Si-13% Al, the attritor processing time was changed to produce a flat powder with several levels of aspect ratio. 'And aspect ratio were evaluated. The conditions other than the attritor processing time are the same as in Experiment A. The result is shown in FIG. FIG. 8 shows that a high μ ′ is obtained by processing to a high aspect ratio in both compositions. However, it can be seen that when the aspect ratio is less than 15, only μ ′ less than 120 is obtained.

(Experiment C)
Furthermore, the effect of substituting part of Fe with Ti, V, Cr, Mn, Co, Ni, and Cu was examined. Fe-6% Si-7% Al was used as the basic composition, and the substitution elements shown in Table 1 were substituted with Fe by a predetermined amount. For these compositions, flat powders and magnetic sheets were prepared in the same manner as in Experiment A, and μ ′ and aspect ratio were evaluated. The results are shown in Table 1. Note that μ ′ and aspect ratio evaluation marks are the same as in Experiment A. From Table 1, the composition (Nos. 1 to 6) in which Ti, V, Cr, Mn, Co, Ni, and Cu are substituted for Fe within a range of 5.0% or less has an aspect ratio of 15 or more and 120 or more. It can be seen that it has a high μ ′. On the other hand, No. with a substitution amount exceeding 5.0%. 7 and 8 have only obtained a low μ ′ of less than 120.

As described above, by using a lower Si composition than the Sendust center composition, the hardness of the alloy is reduced, the aspect ratio can be increased in flat processing, and both the magnetocrystalline anisotropy constant and the saturation magnetostriction constant are positive. The complex permeability as a magnetic sheet can be increased. Furthermore, we provide soft magnetic flat powder that can achieve high magnetic permeability when used as an excellent magnetic sheet with a small crystal grain refining effect in flat processing with an attritor, and a high magnetic permeability magnetic sheet using the same. There is something you can do.


Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina

Claims (3)

The composition is mass%, Fe is 84.0% to 96.0%, Si is 3.0% to 8.5%, Al is 1.0% to 13.0%, and the following formula ( A soft magnetic flat powder satisfying 1) and having an aspect ratio of 15 or more.
2Si% -Al% ≦ 15.0 Formula (1) The soft magnetism according to claim 1, wherein a part of Fe is substituted with one or more elements of Ti, V, Cr, Mn, Co, Ni, Cu in a range of 5.0% or less. Flat powder. A magnetic sheet comprising the soft magnetic flat powder according to claim 1.

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