KR930011236B1 - Magnetic materials - Google Patents

Abstract

The composite magnetic powder is prepared by mixing 33.5-40.5 mol.% BaO, 23.5-26.5 mol.% B2O3, (33-43)-X mol.% Fe2O3 and X mol.% CoO, melting the mixture at 1000-1500 deg.C, rapidly cooling to form amorphous body, treating at the same temperature as above to crystallize the magnetic phase, treating in an acid solution to select the crystallized magnetic phase. A good composite magnetic powder is produced by only a rapid cooling method not by both a rapid cooling method and a wet method. The composition of the powder brings a good reproduction output at low and high frequency areas.

Description

Manufacturing method of compound magnetic powder

The present invention relates to a magnetic powder production method used as a magnetic recording medium, and more particularly, a rapid cooling, isothermal heat treatment and acid treatment process using a mixture of BaO, Fe ₂ O ₃ , B ₂ O ₃ and CoO as starting materials It relates to a method for producing a composite magnetic powder of hexagonal and spinel ferrite excellent magnetic properties through.

As a conventional magnetic recording medium, a needle-like γ-Fe ₂ O ₃ magnetic component is magnetically coated and coated on a nonmagnetic substrate, and the so-called horizontal magnetic recording method in which magnetization is oriented in the in-plane direction by an alignment process such as mechanical orientation or magnetic field orientation This is mainstream.

However, this type of magnetic recording medium of the horizontal magnetic recording method is not suitable for high density recording since the magnetic output action is large when the recording signal becomes short wavelength and the reproduction output is lowered.

In order to overcome such a problem, a so-called vertical magnetic recording method has been proposed.

For example, as in Japanese Patent Laid-Open Nos. 58-203625 and 61-217927, magnetic recording media made by dispersing ferromagnetic powder and hexagonal ferrite magnetic components in a resin binder have been proposed.

However, the magnetic recording medium of this proposal is made of magnetic composite powder by simply mixing ferromagnetic powder and hexagonal ferrite magnetic powder. The magnetic recording medium by this method has to be combined with quenching method and wet method in the manufacturing process. There is a complicated problem.

Accordingly, the inventors of the present invention are in the process of manufacturing a barium ferrite magnetic powder to solve the above problems. The present invention has been proposed through repeated experiments through several experiments, focusing on the fact that a multicomponent powder mixed with CoFe ₂ O ₄ having a spinel structure is obtained, and an object of the present invention is BaO, Fe ₂ O ₃ , B After melting the mixture of ₂ O ₃ and CoO, amorphous materials are prepared using only the rapid cooling method, and then crystallized by isothermal heat treatment. Acid-treated amorphous materials are made using weak acid, and then crystallized by isothermal heat treatment and acid using weak acid. By treatment, it is to provide only high quality composite magnetic component with excellent magnetic properties mixed with hexagonal ferrite and spinel structure ferrite. There is.

In order to achieve the above object, the present invention is mol%, BaO: 33.5 ~ 40.5%, B ₂ O ₃ : 23.5 ~ 26.5%, Fe ₂ O ₃ : (33 ~ 43) -X% and CoO: X% (X (7.2 ~ 10.8) mixed raw materials are melted at a temperature in the range of 1000 ℃ to 1500 ℃ and then rapidly cooled to prepare an amorphous material, and the crystallization of the magnetic phase by isothermal heat treatment, the acid treatment to separate and extract this magnetic phase The manufacturing method of the composite magnetic powder which consists of a process is characterized by the structure.

Hereinafter, the reason for numerical limitation of the component content of this invention is demonstrated.

If the BaO and B ₂ O ₃ is 33.5 ~ 40.5%, respectively, and 23.5 ~ 26.5% facilitates the formation of a homogeneous amorphous body, and the Fe ₂ O ₃ is Fe ₂ O ₃ as a component having the cross-closely related to the CoO and matter content In the case of 22.2% or less and 35.8% or more, and CoO is 7.2% or less and 10.8% or more, the optimum magnetic phase is not formed. Since 300e < Hc < 2000 Oc, the content of BaO and B ₂ O ₃ , Fe ₂ O ₃ and CoO is preferably as described above.

In addition, when the melting temperature of the mixed raw materials is 1000 ° C or lower and 1500 ° C or higher, the melting temperature is preferably in the range of 1000 ° C to 1500 ° C because it is not uniformly dissolved and uniform amorphous bodies are not formed after rapid cooling. In addition, the crystallization heat treatment temperature is preferably performed at 800 ° C or higher, because the temperature at which the optimum magnetic phase is crystallized and precipitated is 800 ° C or higher.

Meanwhile, SrO and PbO may be used instead of the BaO component, and BaCO ₃ may be used instead of BaO.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Table 1 and a starting material having a composition were mixed and melted at 1250 ° C., an amorphous material was prepared by rapid cooling using a twin roller quencher, and crystallized by heat treatment at 850 ° C. for 5 hours, followed by 20 vol% acetic acid. Acid treatment was carried out at 95 ° C for 1 hour. The comparative materials and inventions thus obtained were examined in the X-ray image after the rapid cooling structure and the acid treatment, and are shown in Table 1 below.

TABLE 1

Example 2

In Table 1, the mixed raw material having the composition of the present invention materials (1 to 6) was prepared in the same manner as in Example 1, an amorphous material was prepared, heat treated at 850 ° C. for 5 hours for crystallization, and then subjected to acid treatment, followed by magnetic properties. The results are shown in Table 2 below.

TABLE 2

As shown in Examples 1 and 2, the present invention prepared by the composition, melting temperature and heat treatment conditions in accordance with the present invention is made of a ferrite composite mixed with a hexagonal ferrite and a spinel structure ferrite, unlike the comparative material It can be seen that it is a composite magnetic powder of high quality with excellent magnetic properties of coercive force of 300Oe or more and 20000Oe or less.

Example 3

Table 3 shows the results of the rapid cooling structure and the X-ray phase after heat treatment and acid treatment obtained after rapid cooling, heat treatment and acid treatment of the conventional materials and the present invention having the composition as shown in Table 3 in the same manner as in Example 1. 3 is shown.

TABLE 3

As shown in Table 3, the conventional material is a barium ferrite single phase, whereas the present invention is a composite phase of barium ferrite and cobalt ferrite. As described above, according to the manufacturing method of the present invention, there is an effect of obtaining a high quality compound powder having excellent magnetic properties in which a hexagonal ferrite and a spinel structure ferrite are mixed only by a quenching method. In addition, the combination of the hexagonal ferrite magnetic component and the spinel ferrite magnetic component enables the effective use of the vertical magnetization component of the hexagonal magnetic component, which improves the reproduction output in the high frequency range and copes with high density recording. Since the horizontal magnetization component of the magnetic component can be effectively used, it is possible to improve the reproduction output in the low frequency region.

Claims (1)

In the method of producing a composite magnetic powder comprising a step of rapidly cooling the mixed raw material to produce an amorphous body, a step of crystallizing the magnetic phase by isothermal heat treatment, and a pretreatment step for separating and extracting the crystallized magnetic phase, wherein Amorphous as mol%, BaO: 33.5 ~ 40.5%, B ₂ O ₃ : 23.5 ~ 26.5%, Fe ₂ O ₃ : (33 ~ 43) -X% and CoO: X% (X = 7.2 ~ 10.8) Method for producing a composite magnetic powder characterized in that it is produced by melting the mixed raw material to be in the range of 1000 ℃ to 1500 ℃ rapid cooling.