JPH0432206A - Oxide magnetic material - Google Patents

Abstract

PURPOSE:To obtain a high density and highly wear-resistant oxide magnetic material by adding the specified quantity of zirconium oxide and calcium oxide as auxiliary constituents to an oxide magnetic material constituting of ferric oxide, manganese oxide, and zinc oxide in a specified composition as principal constituents and sintering and pressing the material by the specified method. CONSTITUTION:At the same time, 0.01-0.4 wt.% of zirconium oxide and 0.005-0.2 wt.% of calcium oxide are added to an oxide magnetic material consisting of 50-56 mol.% of ferric oxide, 20-40 mol.% of manganese oxide, and 6-27 mol.% of zinc oxide. The material is sintered at 1,100-1,350 deg.C in a nitrogenous atmosphere containing a very small amount of oxygen and shaped by hot hydrostatic pressing at 1,000-1,300 deg.C and 600-1,600kg/cm<2> in an argon gas atmosphere. A composition of over 56 mol.% of ferric oxide, under 2 mol.% of manganese oxide, or under 6 mol.% of zinc oxide has a characteristic not suitable for practical use because its effective initial relative magnetic permeability is not higher than 1,500 when zirconium oxide and calcium oxide are added. A composition of under 50 mol.% of ferric oxide, over 40 mol.% of manganese oxide, or over 27 mol.% of zinc oxide has a characteristic not suitable for practical use because its magnetic transformation temperature is not higher than 100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION A.Objective of the Invention [Field of Industrial Application] The present invention provides a magnetic material for a magnetic head used in a floppy disk device or a hard disk device that can be used for high-density and magnetic recording. The present invention relates to an oxide magnetic material suitable for a magnetic head that has high wear resistance when sliding with a medium surface.

[Conventional technology]

In recent years, with the development of office automation, factory automation, and home automation, office computers and personal computers have become widespread. Floppy disk drives (FDD) and hard disk drives (H
DD), but the ferrite, which is an oxide magnetic material for magnetic heads used in these devices, has as few defects as possible due to ultra-precision machining, and the crystals are small in size, making them less likely to wear out. The material is required to be
Conventionally, the main components of oxide magnetic materials for magnetic heads are 50 to 56 mol% of ferric oxide (Fe203), 20 to 40 mol% of manganese oxide (MnO), and zinc oxide (
For the purpose of improving AC loss, 0.0
Silicon dioxide (Si02) of 2% by weight or less, o, oo
Calcium oxide (CaO) is added in an amount of s wt % or less, and tin oxide (SnO) is added in an amount of 1 wt % or less to promote crystal growth for the purpose of increasing the density of the material. After sintering at 1350°C in a nitrogen gas atmosphere to which a trace amount of oxygen has been added, hot isostatic pressing treatment (hereinafter referred to as HIP treatment) is performed in a high-temperature argon gas atmosphere to create an oxide magnetic material for magnetic heads. It was used as a material.

[Problem to be solved by the invention]

In a floppy disk device, the recording/reproducing part of the magnetic head is always in sliding contact with the surface of the magnetic recording medium, and in a node disk device, it is used to start and stop the magnetic disk. Sometimes sliding with the surface of the recording medium always occurs, and as a result, during continuous use over long periods of time, magnetic heads have the problem of deterioration of recording and reproducing characteristics due to abrasion of the sliding surface with the surface of the magnetic recording medium. The object of the present invention is to provide an oxide magnetic material for a magnetic head that has high density, high wear resistance, small crystal grains, and can be processed with ultra-precision processing.

Structure of the Invention [Means for Solving the Problems] The present invention has a property that the value of effective relative magnetic permeability at 100KH2 is at least 1500 or more, and moreover, it has higher density and more wear resistance than conventional ones. This is an excellent oxide magnetic material for magnetic heads, containing ferric oxide (ferric oxide) as the main component.
Fe203) is 50-56 mol%, manganese oxide (Mn
O) is 20-40 mol%, zinc oxide (ZnO) is 6-2
0.01 to 0.40% by weight of zirconium oxide (Zr02) as a subcomponent to an oxide magnetic material consisting of 7 mol%
, and calcium oxide (CaO) at 0.005 to 0.
After adding 20% by weight at the same time and sintering at a temperature of 1100°C to 1350°C, 1000°C to 130°C in argon gas.
600kg/cm2 to 1600kg/in the temperature range of 0℃
It is an oxide magnetic material that is obtained by hot isostatic pressing at a temperature of 1.5 cm" and is characterized by high density and high wear resistance.

[Effect]

Ferric oxide: 50-56 mol%, manganese oxide: 20-56 mol%
An oxide magnetic material having a composition range of 40 mol% and 6 to 27 mol% zinc oxide is known as an oxide magnetic material having high relative permeability characteristics and high saturation magnetic flux density.
In the composition range of 56 mol% or more of ferric oxide, 20 mol% or less of manganese oxide, and 6 mol% or less of zinc oxide, the 1001[H2 The value of effective initial sinking permeability is 2000
The values are as follows, and when zirconium oxide and calcium are further added in the present invention, the value of the effective initial settling permeability becomes 1500 or less, so the properties for practical use can be guaranteed. 50 mol% or less In a composition combination in which manganese oxide is 40 mol% or more and zinc oxide is 27 mol% or more, the magnetic transformation temperature becomes 100°C or less, which is an impractical characteristic. The main components that can guarantee the properties are 50 to 56 mol% of ferric oxide, 20 to 40 mol% of manganese oxide, and 6 to 6 mol% of zinc oxide.
The composition range is 27 mol%. In the present invention, zirconium oxide (Zr02) and calcium oxide (CaO
), the wear resistance properties improve as the amount of these oxides added increases, but as the amount of these oxides increases, the value of the effective initial sinking permeability of AC at 100xnz deteriorates, and zirconium oxide is 0.4% by weight. When o, oos weight percent of calcium oxide is added, the effective initial settling permeability at 100KH2 is approximately 1500, which is the lower limit of the required properties. The content of zirconium must be 0.4% by weight or less, and the content of calcium oxide must be 0.2% by weight or less.

〔Example〕

Next, the oxide magnetic material of the present invention will be explained.

Ferric oxide (Fe203), manganese oxide (MnO), and zinc oxide (ZnO) are used as the main component raw materials, and zirconium oxide (ZrO2) and calcium oxide (CaO) are added as subcomponents. Similar to the normal ferrite manufacturing process, the materials are mixed in a ball mill, calcined, pulverized, and granulated to obtain a powder for pressing. The powder thus obtained is press-molded into a block shape, and this is sintered in a nitrogen gas atmosphere containing a trace amount of oxygen gas. This sintered body is further subjected to hot isostatic pressing in an argon gas atmosphere and then subjected to post-heat treatment to obtain a ferrite block which is a high-density oxide magnetic material. Cut this block into small pieces, use a lap master with a diameter of 300 mm, use diamond paste with a particle size of 1 μ, and set the rotation speed of the lap master to 60 rpm.
was polished for a certain period of time using an alcohol-based lubricant, and the amount of wear was measured.

Example 1 53 mol% of ferric oxide (Fe20:+) as the main component,
Manganese oxide (MnO) 30 mol%, zinc oxide (Zn
Zirconium oxide (Z) as an additive to 17 mol% of
The raw materials weighed and added so that r02) is 0.1% by weight are mixed in a ball mill for 40 hours, then filtered and dried, and the powder is calcined for 2 hours in the atmosphere at 950°C. This powder was further finely pulverized for 20 hours using a ball mill, and 1% by weight of polyvinyl alcohol (PVA) was added as a binder.
Add and mix to obtain a powder for molding. This obtained powder was
It was molded into a block of 0 mm x 40 x 101 m in a nitrogen atmosphere with 0.5% oxygen added per weight ratio.
The sintered body was fired at 1250°C for 3 hours, and the sintered body was subjected to hot isostatic pressing at 1200°C and 1000kg/cm for 2.3 hours in an argon gas atmosphere. After a period of time, heat treatment is performed. From this obtained block, a small piece of 5 Soda m x 5 Iris x 3 Fi Otori was cut out and used as a test sample for wear evaluation. As a method for evaluating the polishing characteristics, this small piece was polished using a diamond paste with a particle size of 1 μm under the test conditions using the Lap Master described above, and the amount of wear over time was measured. The results thus obtained are shown in curve A in FIG. In Fig. 1, the curved line indicates the amount of wear of conventional oxide magnetic materials for magnetic heads, and indicates the amount of wear of this type of oxide magnetic material to which zirconium oxide or calcium oxide is not added. It is a characteristic.

Example 2 A block obtained by adding 0.2% by weight of zirconium oxide (Zr02) to a raw material powder having the same composition as in Example 1 as a main component and under the same manufacturing conditions as in Example 1 was prepared as in Example 1. Similarly, the pieces were cut into small pieces for evaluation and the amount of wear was measured.

The measurement results are shown in curve B in Figure 1.

Example 3 0.04% by weight of zirconium oxide (Zr02) and 0.2% by weight of calcium oxide (CaO) were added to the raw material powder having the same composition as in Example 1 as the main component. Through the manufacturing process, small pieces for evaluating wear characteristics were obtained.

The measurement results of the amount of wear are shown in curve C in Figure 1.

Example 4 The main components were 50.5 mol% of ferric oxide (Fe203), 27.0 mol% of manganese oxide (MnO), and zinc oxide (Zn
O) Add 0.05% by weight of zirconium oxide (Zr02) and 0.2% by weight of calcium oxide (CaO) as additives to 20.5 mol% of oxide magnetic material, and perform the same process as in Example 1. A powder of oxide magnetic material is prepared and a molded body is obtained by pressing. This compact was fired at 1350°C for 3 hours in a nitrogen gas atmosphere to which 0.5% oxygen was added by weight.
Hot isostatic pressing was performed in argon gas for 2.3 hours, followed by post-heat treatment in nitrogen gas. The results of measuring the wear amount of the obtained block are shown in curve E in Figure 2.
It was like that.

In Figure 2, the song MF is calcium oxide (CaO
) and the wear amount when zirconium oxide (Zr02) is not added.

Figure 3 shows ferric oxide (Fe203) as the main component.
An oxide magnetic material containing 30 mol% of manganese oxide (MnO) and 17 mol% of zinc oxide (ZnO), 0.1 to 0.4% by weight of zirconium oxide (ZrO3), and no addition of calcium oxide. , 0.1% by weight, 0.2% by weight of the sample made by the same process as Example 1, the value of effective initial settling permeability (μe) at 100KH2 for the amount of each additive added Zirconium oxide (ZrO
2) and the value of effective initial settling permeability (μe) deteriorates as the amount of calcium oxide (ZaO) added increases.

As shown above, the oxide magnetic material for magnetic heads according to the present invention has superior wear resistance compared to conventional oxide magnetic materials for magnetic heads, so it is suitable for use as a material for magnetic heads. Are suitable.

In addition, the characteristic value of effective initial magnetic permeability of magnetic properties is sufficient for magnetic head materials, so it can be used not only for floppy disk devices and hard disk devices, but also for home and commercial VTR heads and audio heads. It can also be used in the same way.

Furthermore, in the present invention, the upper limit of the amount of zirconium oxide (Zr02) and calcium oxide (CaO) added is limited because if the amount exceeds the claimed range, the effective initial sinking permeability (μe ) is deteriorated. Pressure of hot isostatic press is 800kg/cm”~1600kg
/cm2 because if the pressure is less than 600kg/cm2, a sufficient HIP effect cannot be obtained and pores tend to remain, making it impossible to obtain high density. Since it is necessary to cool the steel while applying pressure to a temperature of , the strain during HIP becomes large and the value of the effective initial sinking permeability deteriorates, which is not preferable.

C0 Effect of the invention [Effect of the invention] Ferric oxide is 50-56 mol%, manganese oxide is 20-56 mol%
Zirconium oxide is added to an oxide magnetic material mainly containing 40 mol% and 6 to 27 mol% of zinc oxide.
4% by weight, and calcium oxide o, oos~0.2
After adding % by weight and sintering at 1100°C to 1350°C,
Temperature terror between 1000℃ and 1300℃ in argon gas
By performing hot isostatic pressing at okglc12 to 1600 kg/c2, it has become possible to obtain an oxide magnetic material for magnetic heads that has high density and high wear resistance properties.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the wear amount of the oxide magnetic material for a magnetic head according to the present invention, where curve A is a characteristic diagram of a sample according to Example 1, curve B is a characteristic diagram of a sample according to Example 2, and curve C is a characteristic diagram of a sample according to Example 2.
is a characteristic diagram of the sample according to Example 3, and the song MD is an oxide magnetic material produced by the same composition and process as in Example 1, Example 2, and Example 3, including zirconium oxide, calcium oxide, etc. according to the present invention. FIG. 2 is a characteristic diagram of a product containing no additives. FIG. 2 is a characteristic diagram showing the wear amount of the oxide magnetic material produced according to Example 4 of the present invention. Curve E is the characteristic diagram of the sample according to Example 4, and curve F is the characteristic diagram of the sample of Example 4. , Characteristic diagram of the sample without addition of calcium oxide. Figure 3 shows the effective initial sinking permeability (μe
) is a characteristic diagram showing changes in Figure 1: Karamasakigou Cold) Figure 2: Patent applicant Tokin Co., Ltd.

Claims (1)

[Claims] 1. Ferric oxide (Fe_2O_3) as the main component is 50%
Zirconium oxide (Zr
0.01 to 0.4% by weight of O_2) and 0.005 to 0.2% by weight of calcium oxide (CaO) were added simultaneously at 1100°C to 13% in a nitrogen atmosphere containing a trace amount of oxygen.
After sintering at a temperature of 50 °C, 1
600kg/cm^2~ at a temperature of 000℃~1300℃
An oxide magnetic material formed by hot isostatic pressing at 1600 kg/cm^2.