JPS58135607A - 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 a certain amount of glass to ferrite so as to reduce its contraction coeffiecient to 10% or less. CONSTITUTION:After 0.3-15wt% noncrystalline glass powder with the softening point at 700 deg.C or less is added to ferrite powder and mixed together, the mixture is sintered at temperatures higher than those at which the minute shrinkage of the ferrite begins. Although a compact obtained by pressurizing the ferrite powder in a metal mold contains void holes, diffusion will occurs among atoms constituting the ferrite if the compact is heated at temeprature higher than 800- 1,000 deg.C. As the minute shrinkage progresses, the compact indicates almost nearly no magnetism, however, the strength thereof increases when it begins to function as a magnetic material.

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 obtain a device with high performance, it is important to improve 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 to a constant level, but there are limitations and high dimensional accuracy has not been achieved. Efforts have also been made to obtain higher dimensional accuracy by reducing the shrinkage rate, which is as high as 10 to 20%, but this is not sufficient. For example, so-called mold-type products 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 the present invention is to achieve higher dimensional accuracy and further improve the performance of devices.

The novel method of the present invention involves mixing ferrite and glass powder and then firing at a temperature at which the ferrite becomes uniform.The glass powder added at this time covers the ferrite particles. This suppresses the densification of ferrite and achieves a low shrinkage rate.

For example, Japanese Patent Application Laid-Open No. 50-50207 discloses a conventional manufacturing method of mixing a magnetic material and glass and subjecting them to heat treatment, but the cited example uses hot pressing, whereas the present invention uses a normal firing method, making it easier to mass-produce. There is a huge difference. 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 solidified. Let me briefly touch on the microdensification of ferrite. A compact formed by pressing ferrite powder in a mold contains many pores, but when heated to a temperature of 800 to 1000°C or higher, diffusion occurs between the atoms that make up the ferrite, resulting in the formation of pores. decreases and the molded body shrinks.

As this microdensification progresses, the molded product that exhibits almost no magnetism becomes K and becomes strong so that it has the function of a magnetic material. In the present invention, since the glass surrounds the ferrite particles, the shrinkage rate is reduced by progressing microdensification by diffusion to a certain degree and at the same time stopping the diffusion midway. Examples are shown below.

Fezes 47,5 Mg025.0 Zn020
．． Mixed powder consisting of 5 mol % balance Cuu 900~
After calcining at 1200°C and finely pulverizing the powder to 2 to 5 am, 10% by weight of amorphous glass powder with a softening point of 650°C and a particle size of 100 mm or less was added to the finely pulverized powder. The mixture was mixed for 1 hour using a dryer. After adding the KpvA aqueous solution of the mixed powder and granulating it by mixing, a molded body was obtained by applying a pressure of 21 On/cd in a mold having an outer diameter of 2° and an inner diameter of 10°. 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.

By adding glass as shown in the first layer, it is possible to obtain a material with a low shrinkage rate of 10% or less, which was not possible with the prior art. Moreover, the crushing strength is also greater than that of a material made of only ferrite solidified with resin, which is 100 to goo kg/mK.

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 participation were determined in the second
Shown in the table.

Table 2 Example 5 Table 5 shows the characteristics of a sample obtained by adding 2.5 weight of the same glass powder to the same pulverized ferrite powder as in Example 1 and subjecting it to the same treatment.

Table 3 Example 4 The same ferrite powder as in Example 1 was mixed with 5 weights of amorphous glass powder with a particle size of 150 mesh or less and a softening point of 580°C, and then subjected to the same treatment as in Example 1. Table 4 shows the characteristics of the obtained products.

Table 4 Example 5 FesOa 49,5 NiCNa, o ZnO52
, 5 mol qb mixed powder 800-1100'
The properties of the sample were calcined at 1250°C in the air after being calcined at 0°C, granulated and molded in the same manner as in Example 1, with 5 weight of amorphous glass powder having a softening point of 380°C added. Table 5 shows the properties of the product without glass. .

As shown in the examples in Table 5 and above, ferrite with glass added has an unprecedented low shrinkage rate of 109b or less, which greatly contributes to high dimensional accuracy and, in turn, to improved device performance.

Although the magnetic properties are somewhat reduced by adding glass, the properties required for VCl2, for example, in terms of magnetic permeability, are in an extremely wide range of 5 to 20,000, which limits the application of the material of the present invention. It's not something you do. Further, the amount of glass is 15% by weight or more. Since the magnetic material almost loses its properties as a magnetic material, the claimed range was limited to 15% by weight. If the amount of glass is 0.5 weight or less, a procedural amendment (voluntary) 8. -i'7.Metal Co., Ltd. Representative #Norio Kono Osamu Address: Chiyo, Tokyo] 2-1-2 Marunouchi, 11-ku
Issue Sleeve 11: Contents of amendments to ``Patent Restrictions 11'' in the specification is corrected as follows: ``Softening point for 71 light powder?
7. After adding and mixing 0.3~15% of amorphous glass powder. A soft magnetic material with a low damping rate, characterized by being fired at a temperature higher than the temperature at which Wright's Kane J Mitsu II begins. ” Rei The statement in the description of ``Invention II & Structure #! Akira'' is corrected as follows.

Ji Hao (1) ``Hui Ning'' on page 2, line 16 of the specification is rJ &Mifu.''
Correct.

(2) Correct "miniaturization" in line fLiIIze of the same book to "densification" @ (8) Correct "miniaturization" in line 6 of page 3 of the same book to "densification."

(4) Correct "microdensification" in line 8 of the same book to "densification."

(6) "Mini-densification" in line 14 of the same book is corrected to "vaginal-densification."

(6) In line 18 of the same page of the same book, "miniaturization" is corrected to "intelligence".

(7) Correct "Table 1" in line 1 of 114xjll of the same book to "Table 1."

(8) Same book *6j ["Magnetic permeability J" in table 1] "66
J t- “Corrected to 70J.

that's all

Claims (1)

[Claims] A low-temperature glass powder characterized by adding 0.5 to 15% of amorphous glass powder with a softening point of 700"O or less to ferrite powder, and then firing at a temperature above where ferrite begins to become finely densified. Shrinkage rate soft magnetic ferrite material.