JP2001093719A - Partial carbonized ferrite and method for manufacturing thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To newly develop absorbent of ultrahigh frequency microwave which has not existed, and a high-level technique which converts dust containing a magnetic material of a steel manufacturing plant, which is generated in large quantities and is in trouble for dumping it and becomes a cause of environmental pollution, into a magnetic material of high-added value which is used widely in the electronic industry. SOLUTION: In this manufacturing method, an oxide powder of various purity which forms a soft magnetic material is treated in a reducing atmosphere at a suitable temperature, together with material forming carbon fine grains, and texture in which glass fine grain carbon is uniformly dispersed in the magnetic material is formed. Thereby a new semiconductor and a manufacturing method are developed, so that new radio wave absorbent which has not existed, a new product of very low cost and a new means for preventing environment pollution are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is widely used worldwide as a basic material for floppy disks of various computers in the modern electronics industry, or for all equipment in the telephone and other communication fields. The present invention relates to a new material for ferrite, which is an oxide magnetic material that has become a new material, a new method for producing the same, and a new method for producing from waste materials.

[0002]

2. Description of the Related Art The quality of conventional technology, the manufacturing method and the like up to now are as follows. Ferrite is widely and widely used as a magnetic material in electromagnetic devices. That is, since it is generally used for precision, small-sized, and high-performance components, excellent magnetic properties and stable quality corresponding to the application are required. In order to stably improve the quality, especially to improve the magnetic properties, first, an appropriate composition is selected using magnetite (FeO.Fe ₂ O ₃ ) having a spinel-type crystal structure as a basic substance. For example, part or all of the above-mentioned FeO is replaced with another divalent metal oxide, ZnO, MnO, Ni
Each performance is exhibited by substituting O, MgO or the like.

The first prior art is as follows, all of which are a magnetic material produced from a high-purity raw material and a method for producing the same. Ferrite, compared to metal,
The electric resistivity is as high as 10 7 [Ωm] or more. Therefore,
It has extremely low loss of quiescent current and exhibits excellent performance as a magnetic core material in the high frequency band. Ferrite materials for high frequencies are represented by MnO.ZnO ferrite and NiO.ZnO ferrite. The former belongs to a low class of ferrite having an electric resistance as low as about 10 3 [Ωm], and therefore, the quiescent current loss increases, and 1 [MHZ] is the limit of use. On the other hand, the latter NiO.ZnO ferrite has a high electric resistance and is mainly used in a radio frequency band of 1 to 100 [MHZ]. Also, M
nO.ZnO ferrite suppresses particle growth to several [microns] by a method by adding a small amount of Ca or Si,
By generating pores at the grain boundaries, high resistance at the grain boundaries is realized. As a result, high-frequency loss is reduced, and in the present age, ferrites of this type are mass-produced and used for various applications.

A second prior art is a magnetic material produced from factory waste and a method for producing the same. That is, a large amount of dust is generated in a steel mill in Japan. The amount of iron slag used as a raw material by electric furnace manufacturers, such as surface-treated steel sheets for automobiles, containing zinc is increasing, and the amount of electric furnace dust mainly composed of zinc and iron is increasing. Resources are being reused by recycling technology that recovers zinc from electric furnace dust. The steelmaking dust is fine, and particles such as zinc oxide, iron oxide, and Zn ferrite are microscopically dispersed. Zn ferrite crystal grains are about 1 micron, and no further grain growth occurs. Ca, Pb,
Although impurity atoms such as Si exist in about 10%, they may be used as a magnetic material.

[0005]

In the first prior art, ferrite, which is a magnetic material, is required to have not only high purity but also an appropriate particle size. Iron oxide or the like is used. In addition, the above-mentioned divalent metal compound is added to ferrite raw materials other than magnetite, and the raw materials used must each be of high purity. Therefore, there is a disadvantage that the raw material cost is high and the product price is too high. Next, in addition to the adjustment of the components of the raw material powder, the refinement and mixing of the raw materials are also important steps. The powdery raw material is appropriately shaped as necessary and then fired first to ferrite. In order to obtain the maximum magnetic performance, the mixture is again baked after blending and the grain size is controlled. Ferrite formation requires the progress of oxidation of Fe atoms and the formation of a spinel-type crystal structure, and the conditions such as oxygen partial pressure treatment temperature and treatment time must be precisely controlled and controlled. Precise control for that purpose raises the problem that the manufacturing cost is high and the product price is high. Furthermore, an electromagnetic wave absorbing ferrite absorption plate for preventing electromagnetic wave interference, which has become a social problem in recent years, requires a large thickness in order to be applied to a wide area structurally and to cope with various wavelengths. Therefore, there is a disadvantage that the cost burden is increased. Further, the magnetic material of the first prior art has an electric resistance of about 10 3 [Ωm] and a relatively small eddy current inside the material, so that the frequency is 3 to 3000.
[MHz] HF (short wave), VHF (ultra short wave), UHF
(Ultra high frequency) and other radio waves are absorbed, but SHF and EH of 3 to 300 [GHz], which have recently become more frequently used
There is a problem that F (microwave; high frequency) cannot be absorbed.

[0006] As described above, the second conventional technique is to produce a magnetic material from dust in a steelmaking plant. At the same time, however, it is necessary to recover a large amount of zinc to increase the purity of ferrite. Therefore, there is a problem in that this recycling technology is expensive and a heavy burden on steelmaking costs. Further, steelmaking dust is fine, and particles such as zinc oxide, iron oxide, and Zn ferrite are microscopically dispersed, but about 10% of impurity atoms such as Ca, Pb, and Si are present. However, when reproduced as a magnetic material, there is a disadvantage that the dielectric constant is reduced and the mechanical strength is also reduced accordingly.

In order to solve the above-mentioned drawbacks and problems of the prior art, the present invention has provided, as a completely novel material, partially carbide ferrite suitable for electromagnetic wave absorption. It is a first object to provide a method of manufacturing at low cost. The present invention further makes use of oxides that have been calcined and contain impurities of about 10%, and in particular, makes it possible to reduce the cost of dust generated in large quantities in steel factories and to use it as a useful resource. The second object is to develop and provide a new method.

[0008]

Means for Solving the Problems To solve the above problems,
Therefore, in the present invention, the structure of the following new product and the structure of the manufacturing method are described.
It is the beginning of success. That is, usually high electric resistivity
Has an electrical resistivity of 10 -1 [Ωm]
The provisional, with surprisingly low resistivity,
Develop a new material and use it as a framework for solving problems. Replace this
In other words, it is as follows. First feature of the present invention
Is that this new product is sintered at 800 ~ 1100 [℃]
Forming a ferrite soft magnetic material
Oxide powder 95-99 [% by weight] and glassy carbon 1
-5% by weight is uniformly dispersed and sintered.
That is, it constitutes ferrite nitride. Also the second
The main feature of the magnetic substance in the ferrite soft magnetic material is that
The component is Zn ferrite (ZnO_TwoO_Three), Mn
Ferrite (MnO.Fe_TwoO_Three), Mn / Zn ferrite
(MnO-ZnO-Fe_TwoO_Three), Ni ferrite (Ni
O ・ Fe_TwoO_Three), NiZn ferrite (NiO.ZnO)
・ Fe_TwoO_Three), Mg ferrite (MgO.Fe) _TwoO_Three),
Mg-Zn ferrite (MgO-ZnO-Fe_TwoO_Three )
At least one selected from the group consisting of glassy carbon grains
This is to constitute a partially carbonized ferrite composed of iron.

[0009] A third feature of the present invention is that an oxide containing a magnetic substance or a salt of the substance can be used, if necessary, in a range of 300 to 300.
After calcining at 1000 ° C. to form a soft magnetic material, a carbonizable binder is added in the presence of a carbonizable organic compound, or 1 μm to 5 mm. Pellets having a size of 10 cm square to 1
[M] After forming into a plate shape having an angle, 800 to 1100
In the reducing atmosphere of [° C.], the main firing is performed for 1 to 5 hours, whereby the glassy carbon is reduced to 1 to 5% by weight.
This is a method for producing a partially carbonized ferrite which is transformed into a magnetic substance that is contained and uniformly dispersed. The fourth feature is that the method of forming into a pellet or a plate in the presence of the carbonizable organic compound and firing in a reducing atmosphere includes means for covering the surface of these formed products with graphite particles. This is a method for producing a partially carbonized ferrite in which the calcination is performed in a completely reducing atmosphere.
A fifth feature is a method for producing a partially carbonized ferrite in which the carbonizable organic compound is a water-soluble resin. A sixth feature is a method for producing a partially carbonized ferrite in which the oxide containing the magnetic substance is obtained from dust of a steelmaking plant as a raw material.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 1) The present invention will be described more specifically and in detail, including the operation of the present invention. In the case of containing about 10% of impurities, the calcined ferrite-forming oxide is pelletized with a resin and fully sintered in a reducing atmosphere. Highly conductive strength with a resistivity of less than 10-1 [Ωm], with only the carbon particles being uniformly dispersed, with no growth of ferrite crystal grains of about 1 micron or more. Ferrite with a large value is obtained. This ferrite has high energy due to eddy current loss in a high frequency band.
I also knew that absorption occurred. The amount of glassy carbon is 1
５5 [%]. Preferably, it may be 1-2 [%].

2) Although the first feature of the present invention has been described above, the main component of the magnetic substance finally obtained is Z
The method of manufacturing n-ferrite, Mn ferrite or Mn-Zn ferrite, Ni ferrite or Ni-Zn ferrite, Mg ferrite or Mg-Zn ferrite, in the form of pellets or plates is described in the second and third features. Included in. Further, during the manufacturing method of waste recycling, Z
The method for producing n-ferrite is a method in which metal zinc, zinc oxide, etc. are put into a melting furnace and zinc oxide dust is generated in parallel with iron oxide dust, and dust generated from an electric furnace, from a converter. A method of collecting and producing dust generated is also included. Furthermore, a complete reducing atmosphere can be obtained by covering the pellet-like ferrite with graphite particles having high crystallinity and high thermal conductivity and firing.

3) One of the characteristics is that the carbonizable organic compound is a water-soluble resin.
Compounds that can form a bon bond include cellulose,
Natural polymer compounds such as lignin and petroleum pitch coke,
Synthetic polymer compounds such as polyester resin, epoxy resin and phenol resin are used if necessary. These compounds may be added in the form of a powder, but are preferably added in the form of a solvent, especially an aqueous solution. The amount of addition is ferrite 100
1 to 100 parts by weight, especially 10 to 30 parts by weight
By weight, the amount of carbon finally obtained is 1 to 5% by weight [%] It is suitable for improving the strength and magnetism of the pellet or plate.

4) An operation mechanism for obtaining mechanical strength will be described. 800 to 1 for high mechanical strength
A temperature of 100 ° C. is good. In addition, in order to obtain high conductivity and magnetism, desirably 900 to 1000 [° C.]
It is best to perform the secondary firing under the above conditions. The reason why high mechanical strength can be obtained by firing at such a temperature can be logically presumed to be due to glassy carbon bonds microdispersed between ferrite particles.

Further, by firing at 800 to 1000 [° C.], conductivity is imparted, and the conductivity increases as the degree of carbonization increases. However, carbonization 5 [%]
In this case, the conductivity becomes constant and the cost increases. The reason why such high mechanical strength and electromagnetic properties are exhibited is that the action is due to the strong bonding between ferrite particles and 1 to 5% of microscopically dispersed glassy carbon in the glassy carbon compound. It is considered that the improvement of the mechanical strength and the electrical conductivity were remarkably improved, and the generation of eddy current caused the absorption of energy when the electromagnetic wave passed, thereby improving the electromagnetic characteristics.

(Example) In terms of conversion, FeO is 55% by weight [%], ZnO is 23% by weight [%], CaO + SiO ₂ +
5% in electric furnace dust containing 10% by weight of Al ₂ O ₃
An aqueous resin solution having a concentration of 8% is added and mixed in an amount of 30% by weight to form pellets having a diameter of about 5 mm, and the mixture is reduced at 980 ° C. for 60 minutes in a reducing atmosphere. Fired.
After cooling, pulverization was performed to remove non-magnetic components by magnetic separation, but non-magnetic components were removed due to the total amount attached. Most of the molded body was made of Zn ferrite (ZnO.Fe) by X-ray diffraction.
₂ O ₃ ) and iron oxide spinel (Fe ₃ O ₄ ).
Electron diffraction suggests that the glassy carbon is micro-dispersed between the ferrite particles. The carbon content in the pellets was 2% by weight [%]. A conductive magnetic pellet having high mechanical strength was obtained. Next, the relationship between the electrical resistivity of the product of the present invention and the conventional product and the associated electric wave absorption performance are as shown in Table 1, and the conventional product has a large electrical resistivity of 10 ⁵ to 10 ³ [Ωm]. The eddy current is small, the electromagnetic wave absorption performance is small, and microwaves cannot be absorbed. On the other hand, the product of the present invention has an electric resistivity of 10 ^-1 [Ω].
m] or less, the generation of eddy current is large, the electromagnetic wave absorption performance is large, and microwaves can be absorbed. Further, the high frequency absorption performance of the product of the present invention such as EHF will be described with reference to FIG. FIG. 1 is a graph showing the results of an experiment on the absorption performance of microwaves and high frequencies by the reflection loss of the product of the present invention with respect to a plate-like body.
[Hz], a large reflection loss, that is, absorption is shown. This supports the above description.

[Table 1]

[0016]

According to the present invention, as an embodiment, as one embodiment, a calcined ferrite-forming oxide containing 10% of impurities, particularly ferrite dust generated from a melting furnace, an electric furnace, a converter, and the like. Alternatively, by molding the synthetic ferrite dust together with a carbonizable organic compound and heating and firing in a reducing atmosphere, it can be converted into a conductive magnetic material, and a high mechanical strength and a high magnetic material can be obtained. Therefore, especially in the case of using waste such as steelmaking dust, the product of the present invention can be used at a cost of about 1/10 of the conventional cost, such as a radio wave absorbing material.
Various products can be supplied to the market. 2) Further, the radio wave absorption / absorption material of the present invention can absorb high frequency of SHF and EHF, which was impossible with conventional products, so that it is particularly novel in terms of performance, and it has been sufficiently advanced. Also has properties. 3) One of the production methods of the present invention uses dust from a steel factory which is disposed of in large quantities and is in trouble at dumping sites. It has a significant effect of being very large.

[Brief description of the drawings]

FIG. 1 is a diagram showing high frequency absorption performance by a magnetic material of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 35/30 C04B 35/36 Z 35/36 35/38 Z 35/38 35/26 J H01F 1/00 L H01F 1/00 CF term (reference) 4G002 AA06 AA07 AA12 AB01 AC03 AE02 4G018 AA07 AA21 AA23 AA25 AA28 AA31 AA39 AC15 AC16 5E040 AB03 AB09 BD01 CA13 HB01 HB03 HB05 HB14 HB15 NN02 NB18 AB04 AB03 AB01 AB04 HB05 HB15 NN02 NN18

Claims (6)

[Claims] An oxide powder forming a ferritic soft magnetic material of 95 to 99% by weight and a glassy carbon of 1 to 100% by sintering at 800 to 1100 ° C.
Partially carbonized ferrite characterized in that 5% by weight constitutes a uniformly dispersed and sintered structure. 2. A ferrite soft magnetic material according to claim 1, wherein the main component of the magnetic substance is Zn ferrite (ZnO.Fe).
₂ O ₃ ), Mn ferrite (MnO · Fe ₂ O ₃ ), Mn ·
・ Zn ferrite (MnO.ZnO.Fe ₂ O ₃ ), Ni
Ferrite (NiO.Fe ₂ O ₃ ), NiZn ferrite (NiO.ZnO.Fe ₂ O ₃ ), Mg ferrite (Mg
O.Fe ₂ O ₃ ), Mg.Zn ferrite (MgO.Zn)
_2. Partially carbonized ferrite according to claim 1, comprising one or more selected from O.Fe ₂ O ₃ ) and glassy carbon particles. 3. An oxide containing a magnetic substance or a salt of the substance is, if necessary, calcined at 300 to 1000 ° C. to obtain a substance forming a soft magnetic substance, and then a carbonizable organic substance. In the presence of the compound or after adding a carbonizable binder, and forming into a pellet or plate, 800 to 110
In a reducing atmosphere of 0 [° C.], the main firing is carried out for 1 to 5 hours to convert the magnetic substance into a magnetic substance containing 1 to 5% by weight of glassy carbon and uniformly dispersed. Of producing partially carbonized ferrite. 4. In the presence of the carbonizable organic compound,
The method in which pellets or plates are formed and fired in a reducing atmosphere includes means for covering the surface of these molded products with graphite particles, whereby the firing is performed in a completely reducing atmosphere. 3. The method for producing partially carbonized ferrite according to item 3. 5. The method according to claim 3, wherein the carbonizable organic compound is a water-soluble resin. 6. The oxide containing a magnetic substance is obtained from dust of a steelmaking plant as a raw material,
A method for producing a partially carbonized ferrite according to any one of claims 3 to 5.