JPS58135606A - Ferrite magnetic material - Google Patents

Abstract

PURPOSE:To enable a device to have high dimensional accuracy and to increase the performance of the device by adding glass to ferrite so as to reduce its contraction coefficient to 10% or less. CONSTITUTION:After 0.3-15wt% glass powder by weight is added to ferrite powder and mixed together, the mixture is sintered at temperature higher than those at which the minute shrinkage of the ferrite beings. Although a compact obtained by pressurizing the ferrite powder in a metal mold contains void holes, diffusion will occur among atoms constituting the ferrite if the compact is heated at temperature higher than 800-1,000 deg.C. This causes the void holes to decrease and the compact to shrink.

Description

DETAILED DESCRIPTION OF THE INVENTION Ferrite magnetic materials produced by powder metallurgy are used as useful electronic components in various devices, and are contributing to the development of these devices.

However, since it is manufactured using a powder metallurgy method, 10
This is accompanied by a shrinkage of ~20%, resulting in large variations in the dimensions of the fired product. For this reason, when used as an electronic component, large dimensional variations occur in the assembled product itself, which is an obstacle to improving the performance of the device. Therefore, in order to achieve higher performance devices, it is important to increase the dimensional accuracy of the ferrite, which is the object of the present invention.

Conventionally, in order to obtain high dimensional accuracy, efforts have been made by manufacturers in the art to always control the shrinkage rate at a constant level, but there are limitations and high dimensional accuracy has not been achieved. Further, efforts have been made to obtain high dimensional accuracy by reducing the large shrinkage rate of 10 to 20%, but this is not sufficient. For example, so-called mold-type products, which are made by mixing ferrite and resin and solidifying after molding, have very little difference in dimension between the mold and the product and can achieve high dimensional accuracy, but the product strength is weak and its applications are limited.

The present invention is based on the discovery of a new method for manufacturing a material with a small shrinkage rate of 10% or less, and the purpose of this invention is to achieve higher dimensional accuracy and further improve the performance of devices.

The novel method of the present invention is to mix ferrite and glass powder and then perform firing at a temperature at which the ferrite becomes finer.The glass powder added at this time covers the ferrite particles, causing the ferrite to form. This achieves a low shrinkage rate by suppressing the miniaturization of the material.

Conventional manufacturing methods in which magnetic materials and glass are mixed and heated include the method described in Japanese Patent Application Laid-open No. 50-50207, but in contrast to the coughing method in which hot pressing is performed, the present invention uses a normal firing method. There is a significant difference in mass production. Furthermore, in the present invention, the ferrite is refined to a certain degree, whereas the cited example is different in that the glass and the magnetic material are simply assimilated. Let me briefly touch on the microdensification of ferrite.

A molded product made by pressing ferrite powder in a mold contains many pores, but when heated to a temperature of 0 to 1000", diffusion occurs between the atoms that make up the ferrite, resulting in pores. decreases and the molded body contracts.As this microdensification progresses, the molded body that shows almost no magnetism becomes
It becomes strong as well as functions as a magnetic material. In the present invention, since the glass surrounds the heptad particles, microdensification is progressed by diffusion to a certain degree, and at the same time, the shrinkage rate is reduced by stopping the diffusion midway. Examples are shown below.

Example 1 FeyOs 47.5 Mg025. OZn020.
5mo1% balance CuO mixed powder 900~12
Calcinate at 00°0 to 2~5μ! After the powder was finely pulverized to 100% by weight, the finely pulverized powder was mixed with 100% by weight of amorphous glass powder having a softening point of 650° C. and a particle size of 100 meshier or less using a Raikai machine for 1 hour. After adding a pvA aqueous solution to the mixed powder and granulating it by mixing, it was placed in a mold with an outer diameter of 20 dollars and a diameter of 10 mm. A molded article was obtained to which a pressure of ton/a/ was applied.

Table 1 shows the characteristics of a sample obtained by firing the molded body at 1250 DEG C. in the atmosphere, together with the characteristics of a sample subjected to the same treatment without adding glass powder.

Table 1 By adding glass in this way, it is possible to obtain a material with a low shrinkage rate of 101 or less, which could not be obtained with the prior art. Moreover, the crushing strength is also higher than that of the ferrite solidified with resin, which is 100 to sookg/7.

Example 2 The same glass was added to the same crushed ferrite powder as in Example 1.
The characteristics of the sample subjected to the post-treatment with weight% addition were determined in the second
Shown in the table.

Table 2 Example 3 Table 3 shows the characteristics of a sample obtained by adding 2.5% by weight of the same glass powder to the same ferrite powder as in Example 1 and subjecting it to the same treatment.

Table 5 Example 4 The same ferrite powder as in Example 1 was mixed with 5% by weight of crystallized glass powder with a particle size of 100 mesh or less, and the same treatment as in Example 1 was applied to the mixture. Shown in the table.

Table 4 Example 5 Fears 49.5 Ni018. OZn052,5
After calcining a mixed powder of mo1% at 800 to 1100°C and pulverizing it to 1 to 5 μm, the powder was prepared by adding 5% by weight of the glass used in Example 1 to the pulverized powder. Table 5 shows the characteristics of a sample obtained by firing a sample subjected to similar granulation and molding at 1500° C., together with the characteristics of a sample to which no glass was added.

As shown in the examples in Table 5 and above, ferrite with glass added has a shrinkage rate as low as 10% or less, which is unprecedented, and greatly contributes to higher dimensional accuracy and higher performance of devices. Although the magnetic fPC characteristics deteriorate somewhat by adding glass, the characteristics required of ferrite, for example, in terms of magnetic permeability, are in an extremely wide range of 5 to 20,000. This is not intended to be limiting.6 Furthermore, if the amount of glass exceeds 15% by weight, it will almost lose its properties as a magnetic material, so the scope of the claims is limited to well over 15% by weight. If the amount of glass is less than 0.5% by weight, f) Name of the Invention 78. B. For those who provide magnetic materials assistance.
Norioyo Ukono Osamu To T 5 East 5: (Tokyo E-dai 111-ku Marunouchi 2-1-2 Straddle II, "F Regent Co., Ltd. Telephone Tokyo 284-4642" City 11") Contents of the amendment - The statement in the "Claims" column of the specification is corrected as follows.

"03-15 heavy ii glass powder for 78 light powder
7. After adding % and mixing carefully. 7. Low shrinkage soft magnetism characterized by firing at a temperature above the temperature at which light densification begins. light material. ” The statement in the “Detailed Description of the Invention” column of the Wataru Specification is corrected as follows.

Note (1) “Microdensification” in line 15 of page 2 of the specification is changed to “obscurity”
Correct.

(2) In line 18 of the same page of the same book, ``Mini-densification'' is corrected to ``Rin-densification''.

Corrected to ``Micro-densification J t-r#i-densification'' in the 5th line of the 3rd chapter of the same book.

(4) In line #18 on the same page of the same book, "microdensification" is corrected to "densification".

(5) In line 13 of the same page of the same book, "micro-densification" is corrected to "densification".

i) In line 17 of the same page of the circular, "miniaturization" is corrected to "privacyization."

(γ) Same book @ page 4, line 18, “Table 1” is changed to “Table #I1”
K Correct.

(8) In the same book, page 6, line 16, “1300℃” was changed to “1s
Correct to "oo'c de".

that's all

Claims (1)

[Claims] 7 Elai) 0.5 to 15% by weight of glass powder based on E powder
A low-shrinkage soft magnetic ferrite material characterized by being added and mixed and then fired at a temperature higher than the temperature at which ferrite begins to become finely densified.