JPS63134555A - Manufacture of ferrite composite body - 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] L11 Tadan-ri 11 The present invention relates to a method for manufacturing a ferrite composite.

Conventional techniques and their 21 problems Conventional methods for manufacturing ferrite composites include (1) mixing ferrite particles and an organic resin as a binder and processing the mixture into a sheet, or mixing ferrite particles and a thermosetting resin; A method for producing a tuyurite composite by mixing and forming a block-shaped molded body (Japanese Unexamined Patent Application Publication No. 58-71698), (2
) A method in which magnetite and glass powder as a binder are mixed, nitride is further added to this mixture, molded, and the molded product is heat-treated in air at 1000°C or less (Japanese Patent Application Laid-Open No. 167473/1982); (3) A method in which a ferrite molded body is treated in an electric furnace at 1150°C in a controlled atmosphere mainly composed of nitrogen gas ("Magnetogoramix", Gihodo Publishing) without using a binder. . However, (1) above
All methods (3) have the following disadvantages and are not preferred.

That is, since the ferrite composite obtained by the method (1) uses an organic resin as a binder, it has low heat resistance and is easily deteriorated over time. Also, weather resistance, damage resistance, etc. are not sufficient. In the method (2), since expensive nitride is used, the manufacturing cost increases considerably. Furthermore, method (3) requires a special electric furnace and expensive inert gas, which also increases manufacturing costs.

Means for Solving the Problems As a result of extensive research in view of the problems of the prior art, the present inventor has developed an extremely simple method in which ferrite particles of a specific particle size and glass powder are fired at a specific temperature range. Heat-resistant,
The present invention was completed based on the discovery that a ferrite composite having excellent weather resistance and strength as well as good magnetic properties can be manufactured at low cost.

That is, the present invention provides (a) ferrite particles having a particle size of 1 mm or less and a fine powder content of 70 to 951% with a particle size of 10 μm or less and less than 30%, and (b) glass powder having a particle size of 0.2 mm or less. Production of a ferrite composite characterized by firing a clay containing a composite raw material consisting of 5 to 30% by weight and a binder at 800 to 1100°C in a reducing atmosphere using a hydrocarbon fuel. Pertaining to law.

In the present invention, ferrite particles and glass powder are used as composite raw materials.

As the ferrite particles, magnetite-based ones, manganese-zinc-based ones, etc. are used. The particle size is 1mm
or less, and the content of fine powder with a particle size of about 10 μm or less is about less than 30% by weight. Particle size is 1
If it exceeds mm, the bending strength of the obtained ferrite composite will decrease.

Furthermore, when the content of fine powder with a particle size of 10 μm exceeds 30% by weight, oxidation of the ferrite tends to occur due to excess air when the temperature is increased during the firing process, and the magnetic properties of the resulting ferrite composite deteriorate.

As a method for pulverizing ferrite particles, any method commonly used in this field can be employed.

The blending amount of ferrite particles is 70 to 9 of the total amount of composite raw materials.
The content should be approximately 5% by weight. If it is less than 70% by weight, the excess glass content will cause foaming phenomenon in the fired product after firing, and the magnetic properties will also deteriorate, making it impossible to commercialize the product. On the other hand, if it exceeds 95% by weight, discoloration due to oxidation during cooling will be observed in the fired body after firing, and the magnetic properties will be poor, making it impossible to commercialize the product.

As the glass, any ordinary glass can be used, such as ordinary plate glass, soda lime glass such as container glass,
Examples include borosilicate glass and aluminosilicate glass. In the present invention, the above glass usually has a particle size of 0.2 mm.
It is used after being pulverized to a size of 0.043 mm (325 mesh) or less, preferably 0.043 mm (325 mesh) or less. Particle size is 0.2mm
If it exceeds this value, the surface of the ferrite particles cannot be coated with glass during firing, and the ferrite particles are likely to be oxidized, which is undesirable. The method for pulverizing glass is not particularly limited, and any conventional method can be used.

The amount of glass powder blended is approximately 5 to 30% by weight of the total amount of composite raw materials. If it is less than 5% by weight, sufficient strength and weather resistance cannot be obtained, and part of the ferrite is oxidized during cooling in the firing process, which is not preferable. On the other hand, if it exceeds 30% by weight, desired magnetic properties cannot be obtained.

As the binder, any binder that is normally used in the production of ceramics can be used, such as organic binders such as polyvinyl alcohol and starch, and inorganic binders such as bentonite and talc. The blending amount of the binder is not particularly limited and may be selected as appropriate, but usually the organic binder is about 0.05 to 3 parts by weight and the inorganic binder is about 1 part by weight per 100 mm parts of the composite raw material.
It should be about 10 times the same part.

The method of the present invention will be explained in detail below.

First, a predetermined amount of the above-mentioned ferrite particles and glass powder are put into a common mixer such as a mixer and mixed to obtain a composite raw material. Furthermore, an appropriate amount of binder is added to this composite raw material and thoroughly kneaded. The obtained clay is used as necessary.
It is molded into the desired shape using a conventional molding machine. Molding pressure is not particularly limited, but is usually 200 to 2000
It may be about kof/Ci.

The clay or the resulting molded body is then fired in a reducing atmosphere using a conventional hydrocarbon fuel. The firing temperature is approximately 800 to 1100°C.

At temperatures below 800°C, the desired strength and weather resistance cannot be obtained;
On the other hand, if the temperature exceeds 1100°C, problems such as deformation and foaming will occur. The firing time is usually 30 minutes or more, preferably 8 to 8 minutes.
It may take about 20 hours.

During firing, an oxygen sensor is used to adjust the oxygen concentration of the atmosphere to about 2% or less. Any conventional hydrocarbon fuel can be used, such as methane, propane, butane, gas fuel such as city gas, kerosene,
Examples include liquid fuels such as heavy oil.

After the firing is completed, cooling is performed. According to the method of the present invention, the surfaces of the ferrite particles are coated with glass, and the ferrite particles are not oxidized by oxygen in the atmosphere.

Therefore, in the present invention, any conventional cooling method in this field can be employed, such as a rapid cooling method, a natural cooling method, and the like.

In this way, 1q of the ferrite composite of the present invention can be obtained.

The ferrite composite of the present invention can be used in common applications in this field, such as magnetic shields, radiation shields, radio wave absorbers, and magnetic labels.

Effect of the invention The method of the present invention has the following excellent effects.

(1) According to the method of the present invention, the production of a ferrite composite can be simplified, and there is no need to use expensive nitrides and inert gases that have been used in the past, so costs can be significantly reduced.

(2) The ferrite composite obtained by the method of the present invention has high strength and excellent heat resistance and weather resistance. Moreover, its magnetic properties are also fully satisfactory.

E-1-1 Examples and comparative examples are given below to make the present invention even clearer.

Example 1 Ferrite particles (containing about 20% of fine particles of 10 μm or less) were sieved to a particle size of 1.0 mm or less using the blending ratios (wt%) shown in Table 1, and ferrite particles with a particle size of 0.0 mm that were finely ground in a wet ball mill. A composite raw material was prepared by thoroughly mixing the powder with plate glass powder having a size of 0.043 mm or less using a mixer. This composite raw material 100
A binder was added to the mixture in the proportions (parts by weight) shown in Table 1 and sufficiently kneaded to obtain a clay.

The obtained clay was molded using a hydraulic press at a pressure of 1000 ko.
It was molded using f/ai technology to obtain a molded body having a shape of 100×100×I Omm. This molded body is heated to 150°C in a firing furnace that uses propane as fuel, while controlling the oxygen concentration to 2% or less using an oxygen sensor.
The temperature was raised to 900° C. for 3 hours and fired. After firing, it was allowed to cool naturally for 24 hours to obtain a ferrite composite of the present invention.

When the constituent minerals of the obtained ferrite complex were identified using an X-ray diffraction device, it was found that it was magnetite (Fe304
) consisted only of This composite was subjected to various performance tests. The results are shown in Table 1.

Example 2 A ferrite composite of the present invention was obtained in the same manner as in Example 1, except that the raw materials shown in Table 1 were used and the firing temperature was 1060°C. The obtained composite was subjected to the same performance test as in Example 1. The results are shown in Table 1.

Example 3 A ferrite composite of the present invention was obtained in the same manner as in Example 1, except that the raw materials shown in Table 1 were used and the firing temperature was 860°C. The obtained composite was subjected to the same performance test as in Example 1. The results are shown in Table 1.

Comparative Example 1 The raw materials shown in Table 1 were used as ferrite particles.
30% by weight of fine powder with a particle size of 43 μm or less crushed with a trommel and 70% by weight of particles with a particle size of 1mm or less (no glass powder used), and the firing temperature was set at 12% by weight outside the specifications of the present invention.
A ferrite composite was obtained in the same manner as in Example 1 except that the temperature was 50°C. When the constituent minerals of the obtained composite were identified using an X-ray diffraction apparatus, it was found that only a small amount of magnetite was present, and the majority was hematite (Fe203), which had been oxidized and had no magnetic properties.

This composite was subjected to the same performance test as in Example 1.

The results are shown in Table 1.

Comparative Example 2 The raw materials shown in Table 1 were used as ferrite particles.
20% by weight of coarse particles with a particle size of 1.0 to 3.0 mm and a particle size of 1 m
(Using 75% by weight of clay of less than
A ferrite composite was obtained in the same manner as in Example 1 except that the temperature was 060°C.

The obtained composite had a rough appearance on the surface and had no commercial value. This composite was subjected to the same performance test as in Example 1. The results are shown in Table 1.

Comparative Example 3 Comparative Example 2 was performed except that 80% by weight of fine powder with a particle size of 43 μm or less and 15% by weight of ferrite particles with a particle size of 1 mm or less were used as ferrite particles. A ferrite composite was obtained in the same manner. The resulting composite was oxidized and discolored, and was mostly composed of hematite with no magnetic properties. This composite was subjected to the same performance test as in Example 1. The results are shown in Table 1.

Comparative Examples 4 and 5 Composites were obtained using the raw materials and firing conditions shown in Table 1, with the glass powder composition outside the range specified in the present invention.

The obtained composite was subjected to the same performance test as in Example 1.

The results are shown in Table 1.

[Performance test method]

1) Water absorption rate According to JIS R2205-74.

2) Bulk specific gravity According to JIS R2205-74.

3) Bending strength According to JIS R2213-78.

4) Weather resistance The test was repeated 10 times at -20°C according to the "freeze-thaw test method" specified in JIS A3209-1975.

5) Saturation magnetization Measured using a vibration magnetization measuring device.

From Table 1, the various performances of the products of the present invention (Examples 1 to 3) are the standards for the successful use of ferrite composites [water absorption: less than 5%, bending strength: 150k (Jr/c1j or more)] ,
Appearance: good, weather resistance (freeze-thaw test): good (no change), saturation magnetization (σ): 60 emu/g or more], indicating that it has excellent performance. On the other hand, comparative products (Comparative Examples 1 to 5)
cannot satisfy any of the five criteria and is inferior to the product of the present invention.

(that's all)

Claims (1)

[Claims] (1) (a) The particle size is 1 mm or less, and the particle size is 10 μm.
Ferrite particles with the following fine powder content of less than 30% by weight 7
A clay containing a composite material consisting of 0 to 95% by weight and (b) 5 to 30% by weight of glass powder with a particle size of 0.2 mm or less was heated to 800% by weight in a reducing atmosphere using hydrocarbon fuel. A method for producing a ferrite composite characterized by firing at a temperature of ~1100°C.