JPH0354164A - Oxide magnetic material - Google Patents

Abstract

PURPOSE:To improve the density and abrasion resistance of an oxide ferrite by adding specific amounts of Al2O3 and CaO to an oxide ferrite having a specific composition composed of ferric oxide, manganese oxide and zinc oxide. CONSTITUTION:The objective oxide magnetic material is produced by adding 0.01-0.3wt.% of Al2O3 and 0-0.2wt.% of CaO as subsidiary components to an oxide ferrite used as a main component and composed of 50-56mol% of ferric oxide, 20-40mol% of manganese oxide and 6-30mol% of zinc oxide. The magnetic material has high density and excellent abrasion resistance compared with conventional ferrite material. It has sufficiently good magnetic properties for the use as a head material. When the amounts of Al2O3 and CaO exceed the upper limit in the above composition, the magnetic permeability of the material abruptly decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oxide magnetic material suitable for a magnetic head material having high density and high wear resistance.

[Background Art] In recent years, with the promotion of office automation (OA) and home automation (HA), office computers and personal computers have become widespread. Floppy disk drives (HDDs) and hard disk drives are indispensable external storage devices for these computers.

[Problems to be Solved by the Invention] However, in order to perform ultra-precision machining, the ferrite for the head used in these devices must be as defect-free as possible and have a small particle size, and the ferrite for the head must be Since the material is in contact with the medium for a long period of time, it is required that the material is as resistant to wear as possible.

Therefore, a technical object of the present invention is to provide an oxide magnetic material having high density and high wear resistance so as to satisfy these conditions required for a head material.

[Means for Solving the Problems] According to the present invention, the main components are 50 to 56 mol% of ferric oxide, 20 to 40 mol% of manganese oxide, and 6 to 3 mol% of zinc oxide.
High density and high wear resistance made by simultaneously adding 0.01% by weight of aluminum oxide (Al201) and 0 to 0.2% by weight of calcium oxide (CaO) as subcomponents to 0 mol% oxide ferrite. An oxide magnetic material is obtained which is characterized by having a magnetic property.

That is, in the oxide magnetic material of the present invention, 50 to 56 mol% of ferric oxide and 20% of manganese oxide are main components.
~40 mol% of zinc oxide, 6~30 mol% of zinc oxide, and aluminum oxide (AI) as a subcomponent.
,O,) 0.01-0.3% by weight and calcium oxide (
CaO)O ~ 0.2% of heavy melon is added at the same time, and these raw materials are mixed in a ball mill in the same way as in the normal ferrite manufacturing process, calcined, pulverized, and granulated to produce a powder for pressing.
1 Ru.

The powder thus obtained is pressed into a block shape and fired in an N2 and 02 atmosphere. This sintered body is further subjected to hot isostatic pressing in Ar gas, and then subjected to post-heat treatment to obtain a high-density ferrite block. This block was cut into small pieces, polished for a certain period of time using a Lap Master using 1μ diamond paste, and the amount of wear was measured. The results showed a significant improvement compared to high-density ferrite that does not contain aluminum oxide or calcium oxide. It was recognized that

In addition, in the present invention, the upper limit of the amount of addition is limited to 0.3% by weight of aluminum oxide (A 12 0s) and 0.2% by weight of calcium oxide (Cab) because the magnetic permeability decreases rapidly when these amounts are exceeded. This is because the value deteriorates. Furthermore, in order to produce the oxide magnetic material of the present invention, the pressure of HIP treatment was limited to 600 to 1600 kg/cm2.
00kg. /cm2 or less, sufficient HIP effect cannot be obtained, pores tend to remain, and high density cannot be obtained.
This is not preferable because the distortion at P becomes too large and the magnetic properties deteriorate.

[Example] Next, the present invention will be specifically explained with reference to Examples.

Missing Example 1, Fe203: 53 mol%, MnO: 30 mol%. ZnO
: 17 mol% as main component, AL2 0v as additive
:O. The raw materials weighed to be lwt% were mixed in a ball mill for 40 hours, filtered, and the dried powder was mixed for 90 hours.
It was calcined for 2 hours in the atmosphere at 00°C.

This powder was further finely pulverized in a ball mill for 20 hours, and 1% of binder: PVA was mixed to obtain a molding powder.

The obtained powder is 32 mm in length, 32 mm in width, and 10 in height.
Formed into a block of mm and heated at 1250°C in a N2 atmosphere.
, 3 hours, and the sintered body was heated for 1 hour in Ar gas.
A high-density ferrite block was obtained by hot isostatic pressing (HIP) at 200"C, 1000 kg/cm2.3 hours.

From this 151 block, height 5mm, width 5
A small piece with a height of rn m and a height of 3 mm was cut out and used as a test piece for wear evaluation. For evaluation, this small piece was polished using a 1μ diamond paste using a lap master, and the amount of wear over time was measured.

The results thus obtained are shown as curve A in FIG.

Length Example 2 A raw material powder containing the same main components as in Example 1 with 0.2% A1203 added was powder-manufactured, temporarily fired, and
HIP and post-heat treatment were performed. The amount of wear of the block thus obtained is shown as curve B in FIG.

Example 3. The same main components as in Example 1, with 0.05 wt% Al203
, CaO added in an amount of 0.03 wt% was used in the same process as in Example 1 to obtain a block.

The amount of wear of this block is shown as curve C in FIG.

Example 4. Fe20: 52.0 mol%. MnO: 26.0 mol%
, ZnO: 22 mol% as the main component, and Al as an additive.
20s: 0.05wt%, CaO 0.02wt
% of the raw materials weighed in the same manner as in Example 1,
A powder was prepared and a pressed form was obtained.

This compact was burned at 1300°C in a 0.5% N2 atmosphere for 3 hours to produce a sintered body, which was then subjected to HIP at 1200°C, 1000kg/cm23Hr in Ar gas. After processing, a high density ferrite block was obtained. The amount of wear of this high-density ferrite block is shown as curve E in FIG.

Example 5. A raw material powder containing the same main components as in Example 1 and the addition of At203 and CaO was subjected to powder production, temporary calcination, HIP, and post-heat treatment in the same manner as in Example 1. The magnetic property (magnetic permeability) is a
llJ was determined and the results are shown in FIG.

Curves G, H, and I in the figure show that the amount of CaO added is Owt%, respectively.
The values are shown for cases of 0.1 wt% and 0.2 wt%.

As the amount of CaO increases, the permeability decreases somewhat.

Therefore, it was found that CaO must be 10% or less. Furthermore, when the amount of Al203 increases, the magnetic permeability also decreases at a similar rate of decrease in curves G, H, and I, and when the amount of Al203 exceeds 0.3 wt%, the permeability decreases significantly. It turned out that it had to be 3% or less.

A ferrite block was prepared using a raw material consisting only of the same main components as in Comparative Example 1 and Example 1 in the same manner as in Example 1, and the wear resistance of this ferrite block was evaluated. The results are shown as curve D in FIG.

Embodiment 1 of Mutsumei shown by curves A, B, and C from Fig. 1
It can be seen that the ferrite according to , 2.3 has better wear resistance than the ferrite of curve iD to which CaOAl203 is not added.

Comparative example 2. A powder was prepared in the same manner as in Example 1 from a raw material consisting only of the same main components as in Example 4, and a ferrite block was obtained in the same manner as in Example 4. Wearability evaluation was performed.

The results are shown as curve E in FIG.

From FIG. 2, it can be seen that the ferrite according to Example 4 of the present invention, shown by curve E, has better wear resistance than the ferrite shown by curve F, which does not contain CaO or Al20.

Furthermore, as shown in FIG. 3, the ferrites according to Examples 1, 2, and 3.4 of the present invention have a magnetic permeability that is sufficient as a head material, although their magnetic permeability is somewhat inferior to that of ferrites that do not contain Cab or Al20. It can be seen that it has the following characteristics.

Therefore, it has been found that the oxide magnetic material according to the present invention has sufficient properties not only for magnetic properties but also for head materials.

[Effect of Yumei] From the above explanation, it can be seen that the oxide ferrite according to the present invention has excellent wear resistance compared to existing ferrite materials. Furthermore, since it has sufficient magnetic properties as a head material, it can be used not only for office automation equipment but also for home and commercial VTR heads and a wide range of other applications.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the amount of wear of oxide magnetic materials and processing time, where curves A, B, and C represent Examples 1 and 2.3, and curve D
2 shows the relationship between the amount of wear of the oxide magnetic material and the processing patent, and curve E shows the results of Example 4,
Curve F shows Comparative Example 2, and FIG. 3 shows changes in magnetic permeability depending on the amounts of CaO and AlzO3Jn added to the oxide magnetic material according to Example 5 of the present invention. is CaO Owt%. 0.1wt% and 0.2wt% are shown, respectively. ? Amount of wear (μm) Wear! (μm)

Claims (1)

[Claims] 1. The main components are 50-56 mol% of ferric oxide and 20-40 mol% of manganese oxide. Made by simultaneously adding 0.01 to 0.3% by weight of aluminum oxide (Al_2O_3) and 0 to 0.2% by weight of calcium oxide (CaO) as subcomponents to oxide ferrite consisting of 6 to 30 mol% of zinc oxide. An oxide magnetic material characterized by high density and high wear resistance.