JPS5964572A - Manufacture of high density ferrite - 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 The present invention relates to a method for manufacturing high-density ferrite for magnetic heads.

If there are pores in the magnetic head material Ferrite 1,
When the magnetic deso travels over the head surface, the pores become a source of damage to the head, degrading the characteristics of the magnetic head and damaging the magnetic tape, which is undesirable. Therefore, ferrite for magnetic heads is required to have high density and few pores. A method for obtaining such high-density ferrite is the vacuum sintering method (Japanese Patent Publication No. 47-15194).
No.), Bo] - Press Law Special Publication 1977-20550Y5
), and hot isostatic pressing method (Japanese Unexamined Patent Publication No. 128-1989)
No. 296) etc. are known.

Among these, the hot isostatic pressing method is superior to other methods in terms of eliminating pores and has good productivity. This hot isostatic pressing method requires primary sintering as a preliminary step when a combiner is not used, and the resulting sintered body is treated in a high temperature, high pressure inert gas atmosphere. However, in this method, Inn-Zn ferrite and NL-
Reducing atmosphere and 4T for Zn fluorite
When the amount of oxygen to Lie 1 (chemical!L theory) is reduced, the magnetic properties deteriorate significantly.

In order to deal with this, Japanese Patent Application Laid-Open No. 54-732998,
After primary sintering (for magnetic heads) of 1 light, this sintered body was placed in a ferrite powder that had the same composition and the same treatment as the raw material of this sintered body, and was heated under hot isostatic pressure. A technique called Breath 4 has been proposed. However, even with this method, the sintered body undergoes partial reduction due to the atmosphere during hot isostatic pressing, resulting in variations in magnetic properties, making it difficult to stably mass-produce high-density ferrite with good quality. was difficult.

The present invention solves the above-mentioned problems and proposes a method for producing high-density ferrite that does not require annealing after hot isostatic pressing.

In other words, in the present invention, after sintering a ferrite molded body, 1 g of M2O3 powder, ZrO2 powder, and 1 g of M2O3 powder and ZrO2 powder are prepared.

At least one of the powders is buried in a tightly packed container and then placed, or a 210 plate is placed on top of the filled powder and then placed in a container under high temperature and high pressure. This is a method for producing high-density ferrite, the gist of which is hot isostatic pressing in an active gas atmosphere.

In this invention, any mixed gas of oxygen and inert gas such as nitrogen is used when the ferrite moon press-molded into a predetermined shape is primarily sintered. .1-10%.

A mixed gas consisting of the balance being an inert gas is effective, and Nj
- For Zn-based ferrite 1 to molded bodies, improvements in magnetic permeability and porosity cannot be obtained in an atmosphere containing an inert gas;
It is most effective to use 0% oxygen gas at 1 to 2 atmospheres.

In addition, in the hot isostatic pressing of the present invention, the above-mentioned secondary sintered body is packed with M2O3 powder, 'lr
02 powder, MgO powder, or a mixture of two or more powders is that the above powders are chemically stable within the hot isostatic pressure treatment temperature range and do not easily react with the secondary sintered body. In addition, the sintering of the powder itself does not proceed easily.
Moreover, since the above powder is reduced and generates oxygen gas, -
This is because it has the effect of preventing the subsequent sintered body from being reduced.

The particle size of the above powder used is 50μ+r-3000Jl
11+ is good J, good, 50. Less than 1. Powder scatters easily during handling, and hot isostatic pressure treatment J! It becomes difficult to replace the air in the atmosphere during the IF preparation stage with an inert gas, and if the pressure exceeds 3000 °C, the container will be densely filled.
Since C also has a large porosity in the powder and the primary sintered body is more likely to be reduced, a particle size of 50 μn to 3000 m is preferable.

In addition, in this invention, after embedding the -order sintered body in a single powder of M2O3 powder, ZrO2 powder, -〇 powder, or a mixed powder of two or more types packed densely in a container, it is placed on top of the powder. The reason for placing a ZnO plate formed into a predetermined shape is that the ZnO on the plate is reduced by hot isostatic pressure treatment, but the primary sintering of the ferrite in the container charged to the above powder and -11. This is because the 02 concentration in the processing atmosphere of the ferrite can be maintained at an equilibrium concentration.Furthermore, even if the ZnO plate is used several times, it prevents reduction during the hot isostatic pressure treatment of ferrite. It has the advantage that high-density ferrite, which has excellent magnetic properties, can be mass-produced at low cost and with high quality.

The gap between the Zη0 plate and the container is preferably as small as possible to allow the inert gas of the pressure medium to pass through, and the plate thickness is preferably as thick as possible. It may be selected appropriately in consideration of production costs.

Examples according to the present invention will be shown below to clarify its effects.

[Example 1] Iron oxide 52.0 mol%, manganese carbonate 26.8 mol%.

21.2 mol % of zinc oxide was stirred and mixed in a ball mill using water as a dispersion medium, dried, and then calcined in air. This was again individually pulverized in a ball mill for 20 hours to obtain a powder with a particle size of 111 Al.

Next, this raw material powder was 36mmφX24mmφX6
N containing 0.1 to 21.0% oxygen
Primary sintering was performed in two gases at 1200°C for 3 hours.

Cooling was performed in pure N2 gas.・This secondary sintered body was embedded in a container filled with ZrO2 powder of -28 mesh, and a 75mmφ x 17mm diameter 5m container was placed on the top.
After placing m ZnO disk, RM M'l L/,
1100℃.

Pressure 1000 and argon gas for 1 hour! 1, hot isostatic pressure treatment was performed.

For comparison, the same primary sintered body was embedded in a container filled with 114 mesh ferrite powder of the same composition and same treatment as the sintered body, and hot isostatically treated under the same conditions as above. .

The results of measuring the magnetic permeability and porosity of each of the obtained samples are shown in Table 1. Trial 7 of the method of the present invention in Table 1 shows the results when no ZnO disk was placed.

As is clear from the results in Table 1, this invention method has J,
However, in the case of the conventional method in which ferrite is mixed with ferrite powder, better magnetic properties can be obtained, and one advantage is that the separation is reduced during hot isostatic pressure treatment. In particular, in the case of primary sintering in a gas with an oxygen concentration of 2 to 10% and the remainder N2, the density is 3.1 to the theoretical density of J, and -C is almost 100%.
It can be seen that the magnetic properties significantly improve as the temperature increases.

In addition, since Zr 02 powder is used, hot isostatic pressure treatment TH! At times, there was no sintering on the J5# sintered body, and after use (7) Zy Oe powder was 1 ooo.
It can be used repeatedly if it is heat treated in the atmosphere for 3 hours from 1 to 3 hours, making it suitable for mass production.

[Example 2] Iron oxide: 49.5 mol%, nickel oxide: 13.5 mol%.

32.0 mol % of zinc oxide was stirred and mixed in a ball mill using water as a dispersion medium, dried, and then calcined in air. This was wet-milled again in a ball mill for 20 hours to obtain a powder with a particle size of approximately 1.

Next, this raw material powder was 36mmφX24mmφX6
Press molded to +nm, in oxygen atmosphere under various conditions,
Primary sintering was performed at 1200°C for 3 hours. Cooling was carried out in the middle of the day.

This secondary sintered body was embedded in a container filled with Zr 02 powder of -28 mesh, and a 75 mmφ x 5 door size was placed on the top.
After placing a mm ZnO disk, it was placed and heated to 1200°C.
.

Hot isostatic pressure treatment was carried out under the conditions of argon gas at a pressure of 100,100 O for 1 hour.

For comparison, the same primary sintered body was subjected to an intermediate hydrostatic pressure treatment of 114 mesh ferrite powder having the same composition and the same treatment as the sintered body.

Table 2 shows the results of measuring the magnetic permeability and porosity of each sample obtained.

Note that Sample 5 of the method of the present invention in Table 2 is the result when the 2710 disk was not placed.

As is clear from the results in Table 2, according to the method of this invention, better magnetic properties are obtained than in the case of the conventional method of embedding ferrite into powder, and hot isostatic pressure treatment The degree of reduction of the sample that falls inside is small, especially when the oxygen concentration is 1
It can be seen that when the material is primarily sintered at 0.00% and 1 atm, its density becomes almost 100% of the theoretical density, and the magnetic properties are significantly improved.

Furthermore, annealing after hot isostatic pressure treatment is no longer necessary.
Mass productivity has improved significantly.

Applicant Sumitomo Special Metals Co., Ltd. Voluntary Procedure NerljJJE mR October 28, 1981 Commissioner of the Patent Office Mr. Kazuo Wakasugi 1, Matter! Indication of 1 1981 Patent Application No. 153200 2 Name of the invention Method for manufacturing high-density ferrite 3 Relationship with the person making the amendment Applicant address 5-22 Kitahama, Higashi-ku, Osaka Sumi 1-Mo 1-
Kushiko Kinzoku Name: Sumitomo Special Metals Co., Ltd. 4. Column 6, ``Detailed explanation of the invention for agent specification'', Contents of amendment (1) Amend pages 8 and 11 of the specification as shown in the attached J
Ru.

, pa 448

Claims (1)

[Claims] 1. 15, M2O obtained by sintering a ferrite molded body
3 powder, Zy02 powder, and at least one powder among 10 powders is embedded in a container tightly packed, and then placed, followed by hot isostatic pressing in a high temperature and high pressure inert gas atmosphere. A method for manufacturing characteristic high-density ferrite. 2 After sintering the ferrite molded body, N2O3
At least one of powder, ZrO'2 powder, and Mgo powder is embedded in a container tightly packed, and a ZnO plate is placed on top of the filled powder, and then placed and placed in an inert state under high temperature and high pressure. 1. A method for producing high-density ferrite 1, which comprises hot isostatic pressing in a gas atmosphere.