JPH01129403A - High-frequebnc high-permeability magnetic material - Google Patents

Abstract

PURPOSE:To improve various magnetic characteristics including permeability in a high-frequency range by containing ZrO2 enhancing working characteristics and CaO as a low loss material into a fundamental composition composed of Fe2O3, ZnO and MnO and comprising at least one kind of TiO2 and SnO2 improving magnetic characteristics such as permeability in the high-frequency range. CONSTITUTION:50-65mol% Fe2O3, 5-30mol% ZnO and 10-40mol% MnO are used as a fundamental composition, and 0.01-0.2wt.% ZrO2 and 0.01-0.5wt.% CaO are contained while at least one kind of TiO2 and SnO2 is included at 0.01-0.3wt.%. An effect remarkable for improving the magnetic loss characteristics of a ferrite material is obtained because ZrO2 is contained, and low magnetic loss is acquired by including CaO into the fundamental composition of the ferrite material. At least one kind of TiO2 and SnO2 is added because magnetic characteristics more excellent than the single addition of CaO are obtained owing to composition addition with CaO.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a high-frequency, high-permeability magnetic material with excellent high-frequency characteristics used as a magnetic head material for video tape recorders and hard disks, and in particular, It is about composition.

[Summary of the invention]

The present invention relates to high frequency, high permeability magnetic materials used as magnetic head materials, including Fe, O, ZnO.

By adding a specified oxide material to a ferrite material whose basic composition is MnO and mixed at a specified composition ratio, we are attempting to significantly improve various properties including magnetic permeability in high frequency bands. It is something to do.

[Conventional technology]

Ferrite materials for magnetic heads used in video tape recorders, hard disk drives, etc. are required to have good high frequency characteristics, excellent workability, and good wear resistance when sliding with magnetic tape. .

Here, the present inventors have previously proposed that the above-mentioned processability can be improved by adding a predetermined amount of ZrO□ to the basic composition of ferrite.

On the other hand, conventional methods for improving high frequency characteristics include C
A method of adding aO or 5tOz (generally, both are often added in combination at the same time) is known.

By the way, in particular, magnetic heads used for recording and reproducing hard disks, etc., are required to have even higher frequency characteristics, that is, higher magnetic permeability in high frequency bands. It has become necessary to add elements generously. However, when the high-frequency characteristic improving element is added in excess and the sintering temperature is raised for the purpose of increasing the density of the material, an abnormal sintering reaction occurs and the sintered composition becomes large crystals. This results in a state of coexistence with small crystals, and these elements precipitate at grain boundaries, resulting in deterioration of high frequency characteristics and material strength. That is, there is a limit to the improvement of high frequency characteristics by adding elements such as CaO or 5ift, and there is also a limit to increasing magnetic permeability in a high frequency band.

[Problem that the invention seeks to solve]

As mentioned above, even when certain additive elements are added to the basic composition of the ferrite material in order to achieve the high-frequency characteristics and workability required for the ferrite material, there is a limit to the improvement effect, and it is difficult to achieve the desired high frequency characteristics and workability. However, this was not sufficient to satisfy the high frequency characteristics.

Therefore, the present invention was proposed to solve the above-mentioned problems, and it improves the ILF rate in the high frequency band while maintaining good processing characteristics without deteriorating the coercive force. The purpose is to significantly improve various characteristics.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention uses Fe.

Oh: 50-65 mol%, ZnO: 5-30 mol%, M
The basic composition is nO: 10 to 40 mol%, and Z r 02
: 0.01~O,'2% by weight, CaO: 0.01~
Contains 0.5 % of heavy weight and further T t O.

and Snow in an amount of 0.01 to 0.3%.

Here, the basic composition of the ferrite material used in the present invention is Fezoz: 50 to 65 mol%, ZnO: 5 to 30 mol%, and MnO: 10 to 40 mol%. Generally M
It is called n-Z n-based ferrite. M
The reason why the basic composition of n-Zn ferrite is within the range of the above-mentioned composition ratio is that otherwise the magnetic permeability will be extremely low, and the saturation magnetic flux density will decrease and the coercive force will increase, making it difficult to put it into practical use as a soft magnetic material. This is because it would result in a lack of sex.

The high frequency high permeability magnetic material of the present invention first contains 0.01 to 0.2% by weight of ZrO2, Ca
The composition contains 0.01 to 0.5% by weight of O.

By containing Zr0z, a remarkable effect can be obtained in improving the magnetic loss characteristics of the ferrite material. This Zr
The content of O, is preferably 0.01 to 0.2fflff1%, and the content 41 of Z r Ot is 0.01% to 0.2ffff1%.
If it is less than 01ff (ffi%), the processability cannot be sufficiently improved, and the KrPA content of ZrO□ is 0.01ff (ffi%).
If it exceeds 2 x %, magnetic losses such as a decrease in magnetic permeability, a decrease in saturation magnetic flux density, and an increase in coercive force become large, which is not preferable.

On the other hand, low magnetic loss can be obtained by incorporating CaO into the basic composition of the ferrite material. The CaO content is preferably 0.01 to 0.5% by weight. If the content of CaO is less than 0.01311u1%, the electric resistance becomes small and the desired magnetic properties cannot be obtained, and if the content of CaO exceeds 0.5% by weight, the density increases. If the sintering temperature is increased, abnormal m1tt is likely to occur, and magnetic losses such as a decrease in magnetic permeability, a decrease in saturation magnetic flux density, and an increase in coercive force also increase.

Here, the high-frequency characteristics of the magnetic flux are improved to some extent by adding Zr0z+CaO as described above, but in the high-frequency, high-permeability magnetic material of the present invention, T i O and SnO□
At least one of the above shall be added in an amount of 0.01 to 0.3% by weight.

The reason why at least one of Tiot and SnO is added to the above composition is that combined addition with CaO provides even better magnetic properties than when CaO is added alone. The amount of at least one of Ti1t and 5nOt added is preferably 0.01 to 0.3% by weight, and if it is less than 0801%, the effect of improving the magnetic properties cannot be expected; If it exceeds % by weight, the permeability will actually decrease, i? ! This results in deterioration of magnetic properties such as a decrease in the sum magnetic flux density and an increase in coercive force. Here, Ti
e.

and at least one type of Snow, at least Ti01
This indicates that it is sufficient if TiOz+SnO is added, and each may be added alone, but TiOz+S
Both may be added to the ferrite material basic composition at the same time, such as nO□. Even when both are added at the same time, the amount added is 0.01 to 0.3 weight ff1%. Further, by adding both at the same time in this way, the effect of adding -JiTtOz and Snug can be expected.

To form the high frequency high permeability magnetic material according to the present invention,
Although a normal dry method is employed, it is preferable to further perform hot isostatic pressing treatment (hereinafter referred to as HI'P treatment). The above-mentioned HIP treatment is a press treatment performed after the secondary sintering, and this HIP treatment method involves applying high pressure from the surroundings to the pressure-sintered product in a high-pressure gas atmosphere. It was designed to be pressed from
Since it is possible to apply a high pressure of several thousand kg/- to about 10,000 kg/cj, it becomes possible to produce extremely high-density ferrite.

The above-mentioned HIP processing conditions are not particularly limited as long as they are normal conditions, but it is preferable that the processing is carried out under the following conditions.

That is, the ferrite material is first sintered at a predetermined sintering temperature T (however, 1050°C≦Ti), and the ferrite sintered body produced by causing crystal grain growth has a density of 90.
% or more in preparation for HIP processing. Here, if the above-mentioned sintering temperature T is less than 105[theta]C, the equilibrium oxygen pressure of ferrite cannot be realistically achieved, so oxidation may occur and hematite may precipitate. Furthermore, the reaction of ferrite (
Since the temperature at which spinel formation is completed is 1050 to 1100°C, even if a sintered body is formed, spinel formation may be insufficient and predetermined magnetic properties may not be obtained. In order to ensure sufficient growth of grains (crystal particles), the sintering temperature T,
It is preferable to set the temperature to 125θ℃ or higher, but if the grain growth
In order to suppress the thickness to 5 μm or less and improve workability, it is preferable to suppress the sintering temperature T to 1250° C. or less.

Further, in the second sintering, it is necessary to appropriately select the oxygen partial pressure of the atmosphere during sintering. If the oxygen partial pressure is too high than necessary, α-Fezes will precipitate during sintering, and if the oxygen partial pressure is too low than necessary and the amount of oxygen in the ferrite sintered body after sintering is small, the next HIP treatment will be difficult. During the process, ferrite is prone to cracking (therefore, it is usually the composition of ferrite.

Set the equilibrium oxygen pressure according to the sintering temperature. In particular, when the temperature is raised to reach the predetermined sintering temperature T, and when the temperature is lowered after sintering, a nitrogen atmosphere (not limited to nitrogen, any inert gas atmosphere is fine) is used. If the equilibrium oxygen pressure concentration corresponding to the temperature T is set only during firing, there will be almost no precipitation of the wustite layer or hematite layer, resulting in an extremely good sintered state.

The surface of the ferrite sintered body obtained by the above-mentioned primary sintering is wrapped with ferrite powder (or embedded in ferrite powder B) as necessary, and then
Perform HIP treatment to increase density. HIP processing is a process in which high pressure due to gas pressure is applied from the surroundings to a pressure-fired product in a high-pressure gas atmosphere, but this HIP processing is performed at a temperature lower than the firing temperature T of the ferrite powder and at a temperature lower than the firing temperature T of the ferrite powder. - The next sintering temperature T is lower than the temperature Tz at which grain growth does not substantially occur (however, 1000℃≦Tt≦1250℃
), and it is preferable to further increase the density of the ferrite sintered body while keeping the fine crystal grain size to a density of 99% or more.

The temperature T2 during HIP treatment is actually 1000°C≦T
! ≦1250°C, and in relation to the sintering temperature T, it is preferable that T≦72-100°C.

In other words, by setting the temperature T2 lower than 1250°C, the growth of crystal grains will not substantially occur.
It is possible to obtain a predetermined density by pressing while maintaining the crystal grain size by sintering. I (If the temperature T8 during the IP treatment exceeds 1250°C, the ferrite sintered body and the ferrite powder will undergo a solid phase reaction and will be sintered, making it difficult to remove them after the treatment.
.

By lowering the temperature by 50° C. or more, the growth of crystal grains can be completely suppressed, and therefore the accumulation of strain due to crystal grain growth can be completely prevented, and there is no need to perform annealing after treatment.

However, the above-mentioned secondary sintering temperature T is kept below 1250°C,
When trying to suppress grain growth to 15 μm or less, HI
P treatment treatment pressure T! is 1000℃≦Tt≦1200
℃, T2≦Ts It is preferable to set it as 50℃.

Further, it is desirable that the HIP treatment pressure is 300 atmospheres or more. If the pressure is 300 atmospheres or more, the density of the ferrite sintered body can be increased to 99% or more. In this case, there is a certain relationship between pressure and time during pressing; for example, at a pressure of 300 atm, 10
The time may be 4 hours at a pressure of 500 atm and 30 minutes at a pressure of 2000 atm.

In addition, when performing the above HIP treatment, the density of the ferrite sintered body is made to be 90% or more (the ratio of the measured density to the X-ray density or the theoretical density) by the secondary sintering, so there are no pores. However, the ferrite sintered body has almost closed pores, so even if it is placed directly into high-pressure gas, atmospheric gas will not enter from the surface, and unlike conventional platinum, nickel, or glass containers, it will not be able to be vacuumed. It can be placed directly into a high-pressure container for HIP treatment without being sealed.

[Effect]

Adding ZrO□ to a ferrite material for a magnetic head improves workability and grain boundary strength.

In addition, CaO is added to this ferrite material, and Sn
By adding at least one of O and T i O, magnetic properties, especially high frequency properties, can be improved while maintaining workability, material strength, and low coercive force.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Fe, O,: 53 mol%, ZnO: 16 mol%.

Mno: Z to ferrite raw material powder consisting of 31 mol%
rO□, CaO were added in the ranges shown in Table 1, Ti0z or 5nOt was added as a third additive element in the range shown in Table 1, and after normal wet mixing, this was mixed into a 12φ×7φ It was molded into a toroidal shape of 4 cranes. Then, this toroidal shaped body was subjected to primary sintering for ferrite formation at 1250° C. for 4 hours in an oxygen-containing nitrogen gas atmosphere taking into account the equilibrium oxygen pressure. after that,
HIP treatment was performed in an argon gas atmosphere at 1200°C and a pressure of 1000 kg/- for 3 hours to produce a desired ferrite material.

Table 1: Effective magnetic permeability μ°, saturation magnetic flux density Bs, and coercive force Hc for the ferrite material formed as described above.

Workability was measured. The results are shown in Table 2.

Table 2 As is clear from Table 2 above, even if ZrO□ and CaO are only added to the ferrite material consisting of the basic composition, the effective magnetic permeability at 5 MHz exceeds 700, but in addition, Ti By adding a small amount of Ot or S n Ot, the coercive force shows a high value exceeding 900.

Here, FIG. 1 shows the relationship between the amounts of TiO□ and SnO□ added and the effective i2 [rate μ′ when Tie, SnO, and the like are added. In addition, the mark in Figure 1 indicates a frequency of 1 kll.
Addition amount of Ti0i at z and effective i! The symbol O indicates the relationship between the added amount of SnO and the effective magnetic permeability μ° at a frequency of 1kllz. In addition, in Fig. 1, the mu mark indicates the relationship between the added amount of Ti0t and the effective 1g1ff rate μ' at the frequency IMHz, and the Δ mark indicates the relationship between the amount of Ti0t added and the effective 1g1ff rate μ' at the frequency IMHz.
It shows the relationship between the amount of n Ot added and the effective magnetic permeability μ°. Furthermore, the ■ symbol in Figure 1 indicates the relationship between the added amount of TiOz and the effective magnetic permeability μ' at a frequency of 5 MHz, and the 0 symbol indicates the relationship between the amount of TiOz added and the effective magnetic permeability μ' at a frequency of 5 MHz.
This figure shows the relationship between the addition of O□ (■) and the effective magnetic permeability μ'.

As is clear from FIG. 1, by adding tetravalent elements such as TiO□ and Snow in addition to ZrO, CaO, H magnetic flux in a high frequency band can be achieved.

〔Effect of the invention〕

As is clear from the above description, the high-frequency, high-permeability magnetic material according to the present invention includes Fe, O, and the like.

The basic composition of ZnO and Mn○ contains Zr0t, which improves processing characteristics, and CaO, which is a low-loss material, and TiO□, which further improves magnetic properties such as magnetic permeability in high frequency bands.
and SnO, it is possible to significantly improve various magnetic properties including magnetic permeability in high frequency bands while maintaining workability, material strength, etc. .

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between the amount of T iOt *S n Oz added and the effective magnetic permeability μ°. Patent Applicant Sony Corporation Representative Patent Attorney Akioka Koike Sakae Kyuzai Masaru Sao TiO2,5n022hiro7+DIJ (i!'
/+) Figure 1 hand v9 Shuho Shogo Y (voluntary) February 10, 1986

Claims (1)

[Claims] Fe_2O_3: 50-65 mol%, ZnO: 5-30
mol%, MnO: 10 to 40 mol% as the basic composition, Z
rO_2: 0.01-0.2% by weight, CaO: 0.01
~0.5% by weight and further contains TiO_2
and SnO_2 in an amount of 0.01 to 0.3% by weight.