JPH02225322A - Magnetic material and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) The present invention relates to a magnetic material and a method for producing the same, and in particular to a magnetic material having a large saturation magnetization and a large electrical resistance, and is suitable for use in a high frequency range1, for example, a core for a magnetic head. The present invention relates to magnetic materials used in transformer cores, motor cores, choke cores, yokes, relay iron pieces, magnetic shielding materials, etc., and methods for manufacturing the same. (Conventional technology) Soft magnetic materials are used for magnetic head cores, transformer cores,
Widely used in motor cores, magnetic shielding materials, etc., metal/alloy magnetic materials are used in the low frequency range of 100 KHz or less, and soft ferrite oxide magnetic materials are usually used in the higher frequency range. It is. (Problems to be Solved by the Invention) Among these, the former metal/alloy magnetic materials include:
Permalloy (Ni-Fe type), Sendust (Fe-3
1-AfL series), silicon steel plate, pure iron. There are amorphous materials, etc., which have the advantage of having a saturation magnetization of 6KG or more. However, due to their low electrical resistance, when used in high frequency ranges, eddy current loss becomes large and it becomes unusable. . Therefore, in order to solve this problem, we sometimes try to increase the resistance by creating a thin plate with a thickness of several tens of micrometers or less, by creating a fine texture, or by producing precipitates.
There is a limit to this, and there is a problem in that the magnetic permeability decreases significantly at frequencies above IMHz, and there is also a problem in that it is difficult to process into a bulk having an irregular or complicated shape. On the other hand, the latter soft ferrite ugliness is Mn.
Zn ferrite, NiZn ferrite. There are materials such as CuZn ferrite, which have high electrical resistance and are mainly used in equipment used at frequencies above IMHz, but because their saturation magnetization is small at 5KG or less, they cannot be used to record the medium sufficiently in, for example, magnetic heads. However, if a large output voltage is required in the transformer core, the cross-sectional area must be increased. Furthermore, in metal-alloy magnetic materials, in order to provide air resistance, it is used by forming powder particles and solidifying them using adhesives, self-sintering, powder compacts, etc. However, the magnetic permeability itself is less than 100, which is only a few to several tenths of that of soft ferrite oxides, and the permeability is lower than that of soft ferrite oxides. Furthermore, there was a problem that the magnetization decreased significantly due to the formation of non-magnetic material between the grains. (Object of the Invention) The present invention has been made in view of the conventional problems as described above, and can be made into a solid having an arbitrary bulk shape, and has a high saturation magnetic flux density of 8 KG or more. The object of the present invention is to provide a soft magnetic material having excellent characteristics such that a magnetic permeability of 100 or more is maintained up to a high frequency range of IMHz or more.

[Structure of the invention]

(Means for Solving the Problems) A magnetic material according to the present invention has a core portion and a surface layer covering the core portion, and the core portion is made of a metal 1 alloy magnetic material having high saturation magnetization. The structure is made up of magnetic particles made of a soft ferrite oxide whose surface layer has high electrical resistance in an arbitrary bulk shape, and in an embodiment, the short axis of the core of the magnetic particles is 2 to 10 lm , is characterized in that the thickness of the surface layer of the magnetic particles is 0.01 to 2 μm. Further, the method for producing a magnetic material according to the present invention has a configuration in which a metal/alloy magnetic material powder and a soft ferrite oxide powder are mixed, then crushed, and solidified by heating and pressurizing.
In other manufacturing methods, soft ferrite oxide is coated on the surface of metal/alloy magnetic material powder, mixed uniformly, and then heated and pressurized to solidify. During solidification, the oxygen partial pressure is controlled to create a spinel-phase stable atmosphere for soft ferrite oxides and an oxidizing atmosphere for metal-alloy magnetic materials, and vibration and magnetic fields are controlled. The present invention is characterized in that it is configured to solidify while applying at least one or both of them, and each of the above configurations is a means for solving the conventional problems described above. The magnetic material according to the present invention is made of magnetic particles having a core part and a surface layer covering the core part in an arbitrary bulk shape, and the core part is a metal/alloy magnetic material having high saturation magnetization. Materials include Fe-Ni (permalloy, isobalm) containing 35-80ffi% Ni, Fe-C
o series, Fe-NiC0 series (Verminvar), pure Fe, F
e-3i series, Fe-5t-A2 series (Sendust), Fe
-Crystalline high saturation magnetization materials such as Cr-based and Fe-A-based materials, and amorphous materials such as Fe-based and Co-based materials (amorphous materials)
is used. In addition, as the soft ferrite oxide having high electrical resistance and forming the surface layer of the magnetic particles, 1MO-Fe2O, (M
are Mn, Ni, Cu, and Zn. ferrite represented by Mg), for example NjZn7x
Light t-, M n Z n 7 x light. CuZn ferrite, MgZn ferrite, etc. are used. In this case, if the short axis of the metal/alloy magnetic material that becomes the core is too small, the saturation magnetization in bulk will be too small, and on the other hand, if the short axis is too large, the permeability will be 100 or more at frequencies of I MHz or higher. Since it is difficult to make it magnetic, the short axis of the metal/alloy magnetic material should be 2 to 10 μm.
It is more desirable to set the range to . In addition, if the thickness of the soft ferrite oxide that forms the surface layer is too small, eddy current loss will increase, and on the other hand, if the thickness is too large, the saturation magnetization will become too low. Therefore, the thickness of the soft ferrite oxide should be 0.01 to 2 μm. It is more desirable to set the range to . In the method for manufacturing a magnetic material according to the present invention, a metal/alloy magnetic material powder and a soft ferrite oxide powder are mixed, then crushed, and solidified by heating and pressure treatment, or by other manufacturing methods. sputtering, ion blasting,
Coating soft ferrite oxide using PVD methods such as ionized vapor deposition, various CVD methods, or solution methods,
After uniformly mixing, heating and pressure are applied to solidify. However, when solidifying by heating and pressure in these manufacturing methods, a spinel phase stable atmosphere is created for the soft ferrite oxide, and a metal-alloy based magnetic material is created. It is more desirable to control the atmosphere so that it becomes an oxidizing atmosphere, and to apply at least one or both of vibration and a magnetic field while solidifying.
The reason for this is that the soft ferrite oxide layer on the surface layer is solidified softly and densely without destroying it, and the metal-alloy magnetic material in the core and the soft ferrite oxide layer on the surface layer are appropriately bonded. This is because it is desirable that the interface exists stably so that bonding between the particles can proceed appropriately. (Function of the Invention) The magnetic material according to the present invention is made of magnetic particles having a core made of a metal/alloy magnetic material and a surface layer made of a soft ferrite oxide in an arbitrary bulk shape. It takes advantage of both the high saturation magnetization properties of alloy-based magnetic materials and the high electrical resistance properties of soft ferrite oxides, and has a high saturation magnetization of 8KG or more and a magnetic permeability of 100 or more at frequencies of 1MHz or more. It is a magnetic material with unique characteristics. (Example) "Hikamenuki" A metal/alloy magnetic material that becomes the core of the magnetic particles is produced by a high-purity gas atomization method with a short axis of 4 μm and a long axis of 10p.
m Ni80Fe20 (permalloy) powder was used. Then, this permalloy powder was put into a sputter deposition apparatus and heated at 600°C x 2 in an Ar gas stream containing 5% hydrogen gas.
hr reduction treatment to reduce the oxides on the surface layer, and then reduced pressure (8X
10-' Torr) using a NiZn ferrite target as a soft ferrite oxide, the permalloy powder was sputtered at a temperature of 600°C and while applying vibration to the permalloy powder to form a 0.5 μm±0. Magnetic particles coated with a 2 μm thin NiZn ferrite oxide layer were obtained. These magnetic particles are solidified and molded into an arbitrary bulk shape when used as an actual product, but in this example, in order to measure the characteristics, the outer diameter was 10 mm, the inner diameter was Eimm,
A ring-shaped mold with a height of 10 mm was used, and the magnetic particles were placed therein, and the mold was placed in a hot press device capable of controlling the atmosphere. In this hot press apparatus, the tip of an ultrasonic vibrator was attached to the bottom surface of the mold from the outside, and the temperature was raised while applying vibrations. At this time, the degree of vacuum was maintained at 1X10-5 Torr or less, and the temperature increase rate was 400
℃/hr,! :did. After that (7), keep it at 90°C for 1 hour, then stop applying vibration, and keep it at 60°C until 600"0.
The temperature is lowered at a rate of 0°O/hr, and after that the temperature is lowered at a rate of 200°C.
The magnetic material of Example 1 was obtained by lowering the temperature at a rate of °C/h, r and completing solidification molding by heating and pressurizing. Next, the frequency characteristics of magnetic permeability were investigated for the magnetic material of Example 1 and the magnetic material of a comparative example obtained by mixing permalloy powder and resin for comparison, and the results were shown in Figure 1. there were. As shown in FIG. 1, the magnetic material of Example 1 has a larger LA permeability than the magnetic material of the comparative example over the entire frequency range, and also has a larger saturation magnetization (Bs). It was recognized that it has particularly good properties as a highly saturated magnetic material for high frequencies. NiB as the core in the same manner as in Example 1. Thin N layer on the entire surface of Fe20 (permalloy) powder
Magnetic particles coated with an iZn ferrite oxide layer were used. Next, 95 pieces of this magnetic particle powder were planted and a diameter of 0.4
pm NiZn ferrite powder with 5% by volume was mixed uniformly with a small amount of ginger and alcohol, and the outer diameter was 10.
It was placed in a mold with a diameter of 6 mm, an inner diameter of 6 mm, and a height of 10 mm. Next, this mold is placed in a hot press equipment that can control the atmosphere, and vibration is applied from the outside by attaching the tip of an ultrasonic vibrator to the bottom surface of the mold, and at the same time, 0.1 KO is applied in the thickness direction.
The temperature was raised while applying a magnetic field of e. At this time, the degree of vacuum is l
Maintain the temperature below Xl0”-5 Torr, and the temperature increase rate is 300
°C/hr. Then, after holding at 950"O for 1 hour, the application of vibration was stopped, and the application of the magnetic field was also stopped and the temperature was lowered. The temperature was lowered at 600'0/hr until it reached 600°C, and thereafter the temperature was lowered at 200°C/hr. The magnetic material of Example 2 was obtained by completing the solidification molding by applying 8-pressure.Next, the magnetic material of Example 2 was mixed with permalloy powder and resin for comparison. When the frequency characteristics of magnetic permeability were investigated for the magnetic material of Example 2, the results were shown in Figure 2. As shown in Figure 2, the magnetic material of Example 2 was different from the magnetic material of Example 1. Since the gaps are roughly filled with NlZn ferrite, the magnetic permeability is even higher over the entire frequency range, especially in the high frequency range, and the saturation magnetization (Bs) is also larger, especially in the high frequency range. The material was found to have good properties as a highly saturated magnetic material for use in applications.

【Effect of the invention】

The magnetic material according to the present invention has a core portion and a surface layer covering the core portion, the core portion is made of a metal base alloy magnetic material having high saturation magnetization, and the surface layer is a soft ferrite having high electrical resistance. Since it is made of magnetic particles made of oxide in an arbitrary bulk shape, it has a high saturation magnetization of 8KG or more, which cannot be obtained with conventional soft ferrite oxides.
Frequency IM that cannot be obtained with conventional metal/alloy magnetic materials
It can simultaneously achieve high magnetic permeability of 100 or more in the high frequency range of Hz or more, and can also have an arbitrary bulk shape, making it suitable for a wide range of applications such as cores, yokes, and magnetic heads with complex shapes. It is particularly suitable as a core for a transformer that requires high saturation magnetization at high frequencies. This results in significantly superior effects that can be provided.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are graphs illustrating the results of investigating the frequency characteristics of magnetic permeability in magnetic materials of Example 1, Example 2, and Comparative Example, respectively.

Claims (5)

[Claims] (1) Magnetism comprising a core and a surface layer covering the core, the core being made of a metal/alloy magnetic material having high saturation magnetization, and the surface layer being made of soft ferrite oxide having high electrical resistance. A magnetic material characterized by particles having an arbitrary bulk shape. (2) The magnetic material according to claim (1), wherein the short axis of the core of the magnetic particles is 2 to 10 μm, and the thickness of the surface layer of the magnetic particles is 0.01 to 2 μm. (3) A method for producing a magnetic material, which comprises mixing a metal/alloy magnetic material powder and a soft ferrite oxide powder, pulverizing the mixture, and solidifying the mixture by heating and pressurizing the mixture. (4) A method for producing a magnetic material, which comprises coating the surface of metal/alloy magnetic material powder with soft ferrite oxide, mixing uniformly, and solidifying by heating and pressurizing. (5) When solidifying by heating and pressurizing, the oxygen partial pressure is controlled to create a spinel phase stable atmosphere for soft ferrite oxides and an oxidizing atmosphere for metal/alloy magnetic materials. Claim (3) or (4) characterized in that the solidification is performed while controlling and applying at least one of vibration and a magnetic field.
) The method for manufacturing the magnetic material described in item 1.