JPS61280601A - Manufacture of isotropic ferritic magnet - Google Patents

Abstract

PURPOSE:To improve the magnetic property by wet-pulverizing a part or all of ferric oxide after calcination. CONSTITUTION:Ferric oxide is wet-pulverized in the state of dispersed suspension in water instead of dry-pulverization after calcination. The wet-pulverization can provide the ferric oxide with excellent magnetic property even if the ferric oxide never provided with said property by the dry-pulverizing process is used as a material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in isotropic ferrite magnets.

MO.6Fe2O3 based flightlite magnets are roughly divided into anisotropic magnets, which are press-formed in a magnetic field, and isotropic magnets, which are press-formed in a non-magnetic field. Anisotropic magnets are made by blending iron oxide and barium carbonate or strontium carbonate at a molar ratio of 5 to 6, which is calcined and then coarsely ground, and then finely ground after being dispersed in water using an attritor or ball mill. . So-called wet pulverization is performed, and the slurry is either left in the form of a slurry, or the slurry is dried, a binder is added and crushed, and then magnetic field press molding is performed and sintered to produce an anisotropic magnet.

Isotropic magnets are manufactured through the same process as anisotropic magnets, but the difference is that dry pulverization is performed instead of wet pulverization after calcination.

In this conventional manufacturing method, in order to improve the magnetic properties (especially the residual magnetic flux density) of the magnet, the particle size of the iron oxide used as the raw material,
Purity etc. must be kept within a narrow range. Iron oxide, which is currently used in large quantities, is obtained by thermally decomposing ferrous sulfate and ferrous chloride, which are by-products in the pickling process of steel sheets at steel manufacturers.The average particle size is determined by air permeation method. 0.5~ in diameter
1. About 99% or more of LLL ￥ degree is used excluding water. Furthermore, the calcination temperature must be controlled within a narrow range of around 1100°C. However, as steel manufacturers have introduced other steel sheet processing methods instead of pickling, the amount of by-product iron oxide is decreasing, and other sources of iron oxide must be sought.

The present invention is based on the discovery of a method for manufacturing isotropic ferrite magnets that expands the range of usable raw material iron oxides and allows easy control of magnetic properties during the manufacturing process.

The process that differs from the conventional manufacturing method is that instead of dry pulverization after calcination, it is pulverized in a state dispersed and suspended in water, that is, wet pulverization, which produces isotropic ferrite magnets with high magnetic properties. The technical content of the present invention will be explained in detail with reference to the obtained 1° or less Examples and Comparative Examples. The raw material iron oxide has an average particle size of 10A and a purity of 97%.

Example 1 Raw materials iron oxide and barium carbonate were mixed at a molar ratio of 563 and calcined at 1150°C. This clinker is coarsely crushed, and a particle size of 1.1. It was pulverized to LL, dried, granulated, press-molded, and sintered at 120°C. The magnetic properties of this test bead are determined by the residual magnetic flux density (Br
) 22O0 G, coercive force (B Hc) 17000
It had a coercive force (IHC) of 31,000e.

Example 2 Raw iron oxide was pulverized to 2A using a wet attritor, and the same steps as in Example 1 were carried out, including blending, calcination, coarse crushing, wet pulverization, drying, granulation, pressing, and sintering. Magnetic properties are Br 22
2OG, BHC17500e, IHC350
00e Te Atsuta.

Comparative Example 1 Raw material iron oxide was treated with a wet attritor in the same manner as in Example 2.
It was ground to LL and calcined at 1050°C with a molar ratio of 5.3. This clinker is coarsely crushed, and a particle size of 1
．． It was pulverized to IA, granulated, press-molded, and sintered at 1200°C. Magnetic properties are Br 1950, BHC1
The temperature was 550°C and IHC37000e.

Voice comparison example 2 Raw material iron oxide was 0.9. The material was pulverized to tL, and the rest was carried out in the same manner as in Comparative Example 1 up to sintering. Magnetic properties are Br2O00G, BHC16000e, x
It was Hc38000e.

As described above, even if iron oxide is used as a raw material, which cannot obtain high magnetic properties by the conventional production method using dry pulverization, magnetic properties equivalent to or higher than those of conventional products can be obtained by performing wet pulverization. Similar high magnetic properties can be obtained using naturally occurring iron oxide, the Lussner method, the Lurgi method, etc. Furthermore, if necessary, the shrinkage rate and magnetic properties can be controlled by additives such as silicon dioxide, and the same tendency was obtained even when strontium carbonate was used instead of barium carbonate in the above example. After the wet pulverization shown in the present invention, the cost can be reduced by directly kneading with a binder such as PVA and granulating without drying.

Tone Sangyo Co., Ltd.

Claims (1)

[Claims] In a method for manufacturing an isotropic ferrite magnet of MO・6Fe_2O_3 system (M is one or two of Ba and Sr),
A method for producing an isotropic ferrite magnet, characterized in that part or all of the pulverization after calcination is performed by wet pulverization.