JPH07326508A - Compose magnetic material for bond-molded magnetic body and bond-molded magnetic body - Google Patents

Abstract

PURPOSE:To improve the toughness, corrosion resistance, heat resistance and formability of a bonded magnetic body by covering the surface of a ferromagnetic powder with an insulation thin film contg. a polysilazane compd. CONSTITUTION:A raw material mixture RM contg. a dil. soln. of a polysilazane compd. and ferromagnetic powder is stirred by a stirrer 17 while the mixture is heated to evaporate a solvent and cover the surface of this powder with a uniform film of this compd. This compd. is dissolved by heating whereby it acts as a lubricant and flows peeping a chose adhesion to the ferromagnetic powder. When it is heated, it hardness to tightly bond the particulates of the powder and decomposes to convert into ceramics. Hence, the insulation film- covered ferromagnetic powder can be formed into specified compact by the hot forming method. Accordingly, a high-density formed product so excellent in mechanical strength as having a bending strength higher than that of alumina and also excellent in heat resistance, corrosion resistance and electric insulation can be made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic material for a bond type molded magnetic body and a bond type molded magnetic body molded from this magnetic powder.

[0002]

2. Description of the Related Art So-called bond-type molded ferromagnetic materials obtained by molding a ferromagnetic material powder with a binder are classified into soft magnetic materials and hard magnetic materials.

Soft magnetic materials include transformers for switching power supplies, flyback transformers and deflection yokes for televisions, inductor / transformers of circuit elements, noise filters, smooth choke coils, thyristors and converters, and magnetic cores of other microwave elements. Is used for. As a magnetic core used in these electronic devices, there is a demand for a bond-type molded magnetic material that is inexpensive, has good moldability, has a high magnetic flux density, and has excellent frequency characteristics of magnetic permeability. It is further expanding from the order to the order of MHz.

On the other hand, hard magnetic materials include motors, speakers,
It is used as various permanent magnets for microphones and small generators.

In the resin-bonded molded magnetic material of the soft magnetic material, a ferrite-based material is most often used conventionally. However, the injection-molded product shows constant performance in the frequency range up to 10 ⁴ KHz, but has a magnetic permeability of 30 μH / m.
And low.

On the other hand, the magnetic permeability of a compression-molded magnetic material having a thin-film insulating layer formed of Fe-Si type metal alkoxide is 110 μm.
Although it is as high as H / m, the magnetic permeability begins to drop from the frequency of 10 KHz and becomes as low as 80 μH / m at the frequency of 10 ⁴ KHz.
Further, the ferromagnetic powder coated with the metal alkoxide thin film insulating layer has poor fluidity, and it is extremely difficult to form a complex shape.

Although not a bond-type molded ferromagnetic material, Co
Or in Fe-based amorphous alloy, the magnetic permeability is 80,000μ
Although even higher and H / m, it begins to decrease from the frequency of 10 ⁴ kHz, as low as 500 .mu.H / m at 10 ⁴ kHz frequency. This amorphous alloy cannot be freely formed into any shape other than a thin strip shape, except by roll forming.

There is also a method of compressing and sintering a ferromagnetic powder having high magnetic characteristics. However, although the magnetic substance obtained by this method has improved magnetic characteristics, eddy currents are generated in the high frequency region, and the magnetic permeability is reduced like the amorphous alloy. Moreover, it cannot be formed into a free shape.

[0009]

[Problems to be Solved by the Invention] Recently developed Sm ₂ Fe
It has been proved that ₁₇ N ₈ nitride is a super strong magnet material, but since this nitride magnet decomposes into rare earth nitrides and iron at temperatures above 650 ° C, so-called temperatures below that decomposition temperature are known. A technology that enables low-temperature molding is required.

Rare earth magnetic materials such as Ni-Fe, Sm-Co and Fe-Nd-B have remarkable improvement in magnetic characteristics, but have a problem that they are easily rusted. In particular, with Fe-Nd-B, it is difficult to uniformly coat the surface of the powder with the resin. For example, there is a method of treating the powder surface with a phosphate, a method of treating with a coupling agent, or a method of modifying an unterminated group of the coating resin, but it is still insufficient.

Various proposals have been made to solve the problem of corrosion resistance. For example, regarding bonded magnets using Fe-Nd-B alloy magnetic powder, in order to prevent rust due to surface oxidation, the powder surface is subjected to chemical conversion treatment such as phosphate treatment, chromate treatment, etc. A chemical conversion film is formed (Japanese Patent Laid-Open No. 01-014902), zinc or aluminum is vapor-deposited, or electroless nickel plating is applied (Japanese Patent Laid-Open No. 64-0153).
No. 01), or addition of an antioxidant such as sodium sulfite to the resin binder (Japanese Patent Application Laid-Open No. 01-147806).
Technology has been proposed.

However, these techniques are aimed solely at improving the oxidation resistance, and are well combined with a resin binder, which is one of the most important properties of bonded magnets (good adhesion). (Or wettability) is not considered, and problems still remain in strength and magnetic properties.

On the other hand, a number of techniques have been proposed in which the surface of magnetic powder is coated with a resin to form a bonded magnet.
For example, JP-A-51-038641 discloses a thermosetting resin.
A surface coating technique using (particularly, an epoxy resin) is disclosed, and JP-A-50-104254 discloses a surface coating technique using a thermoplastic resin (in particular, polyamide).

However, the epoxy resin-coated magnetic powder has poor mold fluidity at the time of compression molding, and is thermoset after molding.
(Cure) Treatment required. In addition, the obtained molded product cannot be used practically from the viewpoint of heat resistance in a high temperature environment of 150 ° C or higher, and in order to improve oxidation resistance, surface treatment such as coating resin or plating is applied to the molded product. Will also be required.

On the other hand, in the case of the thermoplastic resin-coated magnetic powder, whether the surface treatment of the magnetic powder has hitherto been carried out,
Or because it is not optimal even if done, the surface coating with resin is not uniform, corrosion resistance, heat resistance, dimensional stability,
There is still a problem in terms of mechanical strength.

Japanese Unexamined Patent Publication No. 02-022802 and Japanese Unexamined Patent Publication No. 02-2817
Japanese Patent Laid-Open Publication No. 12-29242 discloses a surface coating technique using a so-called super engineering resin such as polyether ketone and polysulfide ketone. However, these super engineering resins do not have sufficient wettability with the magnetic powder, and it is difficult to coat the surface uniformly, and there is a problem in moldability. Further, the super engineering resin has a problem that the filling property of the magnetic powder is poor.

For example, polyphenylene sulfide resin is a resin which is easily compounded among super engineering resins, but the filling rate of magnetic powder is about 70.
When the content exceeds the volume%, a very high temperature and a high shearing force are required for compounding, which has a great adverse effect on the magnetic properties and physical properties of the magnetic powder.

The present invention improves the toughness, corrosion resistance, heat resistance, and moldability of the bond type magnetic material, and in addition, enables the hard magnetic material to be sintered at a temperature of 650 ° C. or lower. ,
The purpose of the soft magnetic material is to improve the magnetic flux density and reduce the loss in the high frequency band (improve the insulation).

[0019]

Means and Actions for Solving the Problems
As a result of diligent research and experimentation on means for solving the above problems, it was found that the object can be achieved by coating the surface of the ferromagnetic powder with an insulating thin film containing a polysilazane compound.

That is, in order to achieve the above object, according to the present invention, a ferromagnetic powder is surface-coated with an insulating thin film having a polysilazane compound layer as an outermost layer, and the surface-coated ferromagnetic powder is used to form a bond-type molding magnetic material. The body is to be molded.

As the polysilazane compound, perhydropolysilazane is particularly preferable.

The composite magnetic material of the present invention is formed by heat molding such as hot pressing, extrusion, injection molding,
It can be a bond-type molded magnetic body.

As described above, the present invention relates to a magnetic material for a bond-type magnetic body and a bond-type molded magnetic body molded from the magnetic material. The magnetic material of the present invention is used for compression molding and sintering. Injection molding is also possible. The bond-type molded magnetic body of the present invention can be freely designed to have a complicated shape as compared with the conventional sintered magnetic body, and is free from the brittleness found in the conventional sintered magnetic body.

The raw ferromagnetic powder used in the present invention includes hard ferrite powders such as barium ferrite and strontium ferrite, and the formula LTm _z (here,
L is yttrium or lanthanide metal, Tm is transition metal, z is 4.6-8.8) Sm-Co alloy, Nd-Fe alloy, Sm-Fe-Nd alloy, Sm-Fe-Ti alloy and other alloy powders, Alnico powder, etc., and also Fe, Zn, Cu, P as high permeability materials.
b, Sn, Mn, P, Ni, Co, Mg, etc. Soft ferrite powder, carbonyl iron powder, Fe-Al-Si alloy sendust powder, Ni-Fe alloy permalloy powder, reduced iron powder, Examples include electrolytic iron powder, nickel powder, molybdenum powder, and other amorphous alloy powder.

These ferromagnetic powders can be used alone or as a mixture of two or more kinds. The particle size of the ferromagnetic powder is generally 0.1 μm to 500 μm. In particular,
The use of ferromagnetic powders having different particle diameters improves the fluidity and the compression density.

In the present invention, the insulating thin film that covers the surface of the ferromagnetic powder contains a polysilazane compound. The polysilazane compound is a silazane polymer having (-Si-N-) as the main chain, and may have a substituent such as an alkyl group in the side chain, but only hydrogen is bonded as the side chain. Perhydropolysilazane is particularly preferred.

The polysilazane compound is preferably a liquid (including a highly viscous liquid) at room temperature for easy handling. Such polysilazane compounds usually have a molecular weight of 600 to 1500.

In the present invention, in coating the surface of the ferromagnetic powder with the polysilazane compound, the polysilazane compound is preferably diluted with an organic solvent, and the ferromagnetic powder is put into this and stirred sufficiently.

Polysilazane compounds include benzene, toluene, xylene, ether, tetrahydrofuran (THF),
Methylene chloride, ketone, carbon tetrachloride, trichloro (fluoro) ethanol, phenol, m-cresol, N-
Methyl-2-pyrrolidone (NMP), α-chloronaphthalene, dichloroacetic acid, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfone oxide, dimethylacetamide, dimethylformamide, p-chlorophenol,
It is also possible to use a mixture of these solvents dissolved in isopropyl alcohol, dioxane, formic acid and the like.

Further, the polysilazane compound is disclosed in JP-A-50-1.
Although it is soluble in a mixture of the alcohol solvent disclosed in 04254 and a chlorinated hydrocarbon solvent such as methylene or trichlorethylene, the alcohol solvent hydrolyzes the silazane compound, and therefore its use Pay attention to the amount. The polysilazane compound is preferably dissolved in the organic solvent at a concentration of 5% by weight to 40% by weight.

When stirring the raw material mixture containing the polysilazane compound and the ferromagnetic powder, the raw material mixture is heated to, for example, 50 ° C.
Heat to ~ 800 ° C, preferably 200 ° C to evaporate the solvent. This operation can be performed in the air, in a gas atmosphere of hydrogen, nitrogen, helium, argon, ammonia, or the like, or in a vacuum. As a result, the surface of the ferromagnetic powder is extremely thin (1 μm) made of the polysilazane compound.
m or less), and is covered with a uniform and strong insulating film.

The device (coating device) used for coating the surface of the ferromagnetic powder is particularly limited as long as it can uniformly form the insulating thin film of the present invention on the surface of the ferromagnetic powder. There is no. For example, universal stirrer, ribbon blender, tumbler, nauta mixer, Henschel mixer, super mixer, kneader, roll mixer, kneader kneader, spray drier. -, A vibration fluidized dryer, an instant vacuum dryer, etc. can be used.

FIG. 1 shows an example of the coating device. The coating device 10 shown is for charging a diluted solution of a polysilazane compound, a raw material mixture RM such as a ferromagnetic powder,
For example, a container 11 made of stainless steel is provided. This container 11 comprises a container body 12 and a lid 13 having three mouths 13a, 13b, 13c. Inside the container, the mouth 13a is hermetically sealed, for example, a Teflon stirring sheet. A stirrer 17 is inserted through the rule member 14. This stirrer 17 is
It is rotationally driven by the motor 18 at a predetermined rotational speed.

The container 11 is housed in the mantle heater 19,
Most of the container body 12 is surrounded by a mantle heater. Inside the container 11 is a stopper member 15 for sealing the mouth 13b of the container.
The thermocouple 20 is inserted via the so as to reach the raw material mixture RM in the container 11. The thermocouple 20 is connected to one end of a temperature controller 21 installed outside the container 11, and the other end of the temperature controller is connected to a relay device 22 connected to a mantle heater 19.

The temperature controller 21 controls the relay device 22 in response to the temperature of the raw material mixture RM detected by the thermocouple 20 to maintain the temperature of the raw material mixture at a predetermined temperature.

A stopper member 16 for sealing this is also attached to the mouth portion 13c of the container 11. A three-way cock valve 23 is provided through the plug member 16, and the three-way cock valve 23 is connected to a discharge pipe 24 for discharging the solvent vapor in the container 11. The discharge pipe 24 is connected to a vacuum pump 26 via a cooling trap 25 that cools the solvent vapor and captures it.

For example, the coating device 10 is operated as follows. First, the raw material mixture RM is stirred by the stirrer 17. During this stirring, the raw material mixture RM is heated to evaporate the solvent and cover the surface of the ferromagnetic powder with a uniform coating of the polysilazane compound. The evaporated solvent is discharged to the outside of the system through the discharge pipe 24 by driving the vacuum pump 26, and the cooling trap 25
Are captured and collected by.

The insulating thin film-covered ferromagnetic powder (composite magnetic material) of the present invention thus obtained can be molded into a predetermined molded body by a heat molding method such as hot press molding, extrusion molding, injection molding or the like.

The molding can be carried out in the air, in a gas atmosphere of hydrogen, nitrogen, helium, argon, ammonia or the like, or in a vacuum. In this molding, it is preferable to heat the composite magnetic material of the present invention to a temperature near the melting point of the polysilazane compound, usually 200 ° C to 1200 ° C, preferably 500 ° C.

By this heating, the composite magnetic material of the present invention exhibits a free-flowing property to such an extent that the above heat molding can be easily carried out. That is, the polysilazane compound that forms the insulating thin film that covers the surface of the ferromagnetic powder melts when heated, acts as a lubricant, and flows while maintaining close contact with the ferromagnetic powder. When further heated, the polysilazane compound solidifies, decomposes while firmly binding the ferromagnetic powder particles to each other, and converts into a ceramic (silicon compound).

Therefore, the composite magnetic material of the present invention is
Injection molding similar to plastic (melting temperature 200 ℃ ~ 300
℃, mold temperature 250 ℃ ~ 500 ℃) is also possible, and because of good flowability during compression molding, molding of complicated shapes can be easily performed. Moreover, relatively low temperature (80 ℃ ~ 800
C.) and then sintered at a temperature of 500 to 1200.degree.

The ceramic derived from the polysilazane compound has a higher bending strength than that of alumina and is excellent in mechanical strength, and is also excellent in heat resistance, corrosion resistance and electric insulation, and provides a high density molded body.

As described above, since the bond-type molded magnetic material of the present invention is firmly bonded by the silicon-based ceramic derived from polysilazane and excellent in adhesion and mechanical strength, it is tough and rust occurs. In addition, it exhibits excellent high-frequency characteristics that it has no iron loss and has a large magnetic permeability μ, and also has good heat resistance and corrosion resistance. Further, since the silicon-based ceramic derived from polysilazane has a high insulating property and the molded magnetic body becomes a high resistance body as a whole, no eddy current is generated and the magnetic permeability does not decrease.

In addition, since the polysilazane compound coating the ferromagnetic powder has a small film thickness (1 μm or less) and is uniform, it is possible to provide a compact having a small decrease rate of the magnetic flux density and the absolute value of the magnetic permeability. it can.

The present invention also provides a bond type molded magnetic body in which a ferromagnetic powder coated with a polysilazane compound layer is compounded with a resin.

The resin may be thermoplastic or thermosetting as long as it is soluble in the solvent of the polysilazane compound. The resin is preferably used in a proportion of 1 to 5% by weight based on the polysilazane-coated ferromagnetic powder.

Examples of the resin include polyamide (nylon), polyethylene, polyethylene oxide, polyisobutylene, polymethyl methacrylate, epoxy resin, polyester, fluororesin, super engineering resin such as polyphenylene sulfide, poly Butylene terephthalate (PBT), modified polyester, modified polyamide (specifically, for example, BASF PAMX66, PA6
T, PA6 / 6T, PA66 / 6T).

In the magnetic material of the present invention in which such an insulating resin is further compounded, the ferromagnetic powder coated with the polysilazane compound is dipped in a solution of the resin, and mixed by heating (during this time, purging with nitrogen gas). After that, the solvent is removed, and the obtained agglomerate is crushed.
The resin is compounded to cover the polysilazane compound.

In addition to the advantages of the above polysilazane compound-coated ferromagnetic material, the magnetic material of the present invention in which a resin is further compounded has a low temperature mold as in the conventional magnetic material for resin-bonded molded magnetic material. It has the advantage that it can also be used for injection molding. Moreover, in the conventional resin-bonded molded magnetic material, the orientation of the magnetic material at the time of molding in a magnetic field is poor and the insulating state between particles becomes non-uniform, but this invention also improves this point.

Further, the composite magnetic material of the present invention (including a composite of resin) may have an insulating layer other than the polysilazane compound as an underlayer of the polysilazane layer. Examples of such an insulating layer include known metal alkoxides. The ferromagnetic fine powder coated with such other insulating layer, in addition to the ferromagnetic powder, ferrite (Mn-Zn, Ni-Zn, etc.), magnetite (Fe ₃ O _4), hematite (alpha- Fe ₂ O ₃ ) and iron hydroxide (FeOOH) can be exemplified, and a mixture of two or more of them can also be used.

The mixing ratio of the insulating ferromagnetic fine powder coated with such another insulating layer and the polysilazane compound insulating ferromagnetic fine powder is preferably 1: 0.01 to 0.02 in weight ratio.

The insulating ferromagnetic fine powder coated with another insulating layer can be coated with the polysilazane compound by adding it to the solution of the polysilazane compound and treating it in the same manner.

Needless to say, the ferromagnetic powder having these two insulating layers (the underlying insulating layer other than polysilazane and the polysilazane insulating layer formed thereon) can be compounded with the above resin.

[0054]

EXAMPLES Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

Example 1 A composite magnetic material of the present invention was prepared using the coating apparatus 10 shown in FIG. That is, 2 in 30 ml of xylene
Wt% polysilazane (Tonen Corporation PHPS-2: molecular weight 1200)
~ 1500 perhydropolysilazane, highly viscous liquid) solution (containing 3.60 g of polysilazane) was charged into container 11, and 150 g of ferromagnetic powder (Mylon PM: soft magnetic iron powder manufactured by Toho Zinc Co., Ltd.) was added to this, and nitrogen was added. The solvent xylene was evaporated while heating and stirring in a gas atmosphere at 200 ° C. to coat the surface of the ferromagnetic powder with a polysilazane film.

At this time, the solvent xylene vapor was exhausted by the vacuum pump 26 and collected in the cooling trap 25. The obtained coated powder mass was crushed with a sample mill or a mortar to obtain a composite magnetic material of the present invention. A scanning electron micrograph of this composite material is shown in FIG. As can be seen from FIG. 2, the polysilazane film uniformly covered the surface of the ferromagnetic powder.

Next, the obtained composite material is 3 tons / square C
Under the molding conditions of m and 500 ° C, a disk having a diameter of 12 mm and a thickness of 4 mm was heated and pressed. The characteristics of the obtained molded product are shown in Table 1 below. As can be seen from these results, the molded magnetic material of the present invention exhibits magnetic characteristics equivalent to those of the conventional epoxy resin bond-type molded magnetic material, but no rust occurs in the 24-hour salt spray test, and the high-frequency magnetic characteristics are It's very good.

Comparative Example 1 A disk was molded in the same manner as in Example 1 using a ferromagnetic powder (Myron PM manufactured by Toho Zinc Co., Ltd.) which was not coated with polysilazane, and its characteristics were measured. The results are also shown in Table 1. The molded product of Comparative Example 1 suffered from rust in the salt spray test for 24 hours, and the high frequency magnetic properties were deteriorated by eddy current loss.

Example 2 Sm-Co powder (manufactured by Shin-Etsu Chemical Co., Ltd. 2-
A molded product (diameter 12 mm, height 10 mm) was obtained in the same manner as in Example 1 except that a 17-system, average particle size 7 μm) was used and an external magnetic field of 15 KOe was applied during pressure molding. The properties of this molded product are also shown in Table 1. As can be seen from these results, this molded product had excellent corrosion resistance and high-frequency magnetic properties.

Comparative Example 2 Using a ferromagnetic powder (Myron PM manufactured by Toho Zinc Co., Ltd.) not subjected to the polysilazane coating treatment, a molded body was molded in the same manner as in Example 2 and its characteristics were measured. The results are also shown in Table 1. In the molded product of Comparative Example 2, rust was generated in the salt spray test for 24 hours, and the high frequency magnetic properties were also deteriorated.

[0061]

[Table 1]

Example 3 A coating apparatus 10 shown in FIG. 1 was charged with 35 ml of m-cresol as a solvent and 2% by weight (3.06 g) of a resin (Ultramid T manufactured by BASF) and heated at 200 ° C. While stirring
The resin was fully dissolved. 150 g of the polysilazane-coated ferromagnetic powder obtained in Example 2 was placed in this resin solution and stirred at 200 ° C. for 100 minutes while heating. Meanwhile, the inside of the container was purged with nitrogen gas.

Then, the solvent was removed and recovered by a vacuum pump, and the obtained lumps were crushed by a sample mill or a mortar to obtain a magnetic material further compounded with a resin. And
The obtained magnetic material was injection-molded by using J-20M manufactured by Nippon Steel Co., Ltd. while applying an external magnetic field of 10 kOe.

The characteristics of the obtained molded product are shown in Table 2. From this result, this molded body has excellent magnetic properties and strength, and since the insulation resistance is improved, the coating film of polysilazane sufficiently withstands the shear stress during injection molding,
It can be seen that the coating film is not damaged.

Comparative Example 3 A molded product was obtained in the same manner as in Example 3 except that the polysilazane coating treatment was not performed. The properties of this molded product are also shown in Table 2. As can be seen from this result, the magnetic properties of this molded product are deteriorated due to the low degree of orientation of the magnetic powder,
Also, the insulation resistance is very low. From this, it is understood that the insulation is incomplete only by the insulation coating with the resin. Also, the strength of the molded body is low.

[0066]

[Table 2]

[0067]

As described above, according to the present invention, it is possible to obtain a composite magnetic material for a bond-type molded magnetic body which is coated with a coating film having excellent corrosion resistance and insulating properties and which is also excellent in moldability. .

When the resin is further compounded, it becomes possible to perform injection molding under the same conditions as in the conventional resin bond type magnetic material.

The molded body formed by heat molding from the composite magnetic material of the present invention has high mechanical strength and molding density, and exhibits excellent corrosion resistance and high frequency magnetic characteristics.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a coating device used for producing the composite magnetic material of the present invention.

FIG. 2 is a scanning electron micrograph showing the grain structure of the composite magnetic material of the present invention.

[Explanation of symbols]

 10 coating device 11 container 17 stirrer 19 mantle heater RM raw material mixture

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Claims (10)

[Claims] 1. A ferromagnetic powder surface-coated with an insulating thin film having a polysilazane compound layer as an outermost layer,
Composite magnetic material for bond type molded magnetic material. 2. The composite magnetic material according to claim 1, wherein the polysilazane compound is perhydropolysilazane. 3. The composite magnetic material according to claim 1, wherein the insulating thin film further has a base insulating layer other than the polysilazane compound. 4. The composite magnetic material according to claim 3, wherein the underlying insulating layer is made of a metal alkoxide. 5. A composite magnetic material for a bond-type molded magnetic body, which is obtained by further compounding a resin with a ferromagnetic powder, the surface of which is coated with an insulating thin film having a polysilazane compound layer as an outermost layer. 6. The composite magnetic material according to claim 5, wherein the polysilazane compound is perhydropolysilazane. 7. The composite magnetic material according to claim 5, wherein the resin is a thermoplastic resin, a thermosetting resin or a modified resin thereof. 8. The resin is polyamide, polyethylene, polyethylene oxide, polyisobutylene, polymethylmethacrylate, epoxy resin, polyester, fluororesin, polyphenylene sulfide, polybutylene terephthalate, modified polyester, or modified polyamide. The composite magnetic material according to claim 7. 9. A bond-type molded magnetic body obtained by heat-molding a composite magnetic material comprising a ferromagnetic powder, the surface of which is coated with an insulating thin film having a polysilazane compound layer as an outermost layer. 10. A bond-type molded magnetic body obtained by heat-molding a composite magnetic material comprising a ferromagnetic powder having a polysilazane compound layer as an outermost layer, the surface of which is coated with an insulating thin film, and a composite of a resin and a resin.