JP2000192186A - Manufacture of soft magnetic alloy sheet, and magnetic core member using this sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a high toughness sheet-like product favorable to subsequent working in the technique of making a sheet-like product from a soft magnetic alloy. SOLUTION: A powder of soft magnetic alloy is mixed with a liquid containing binder material. The resultant slurry is compressed into sheet-like state. The resultant green sheet is heated to undergo binder removal and temporary sintering. The temporarily sintered sheet is cold or warm rolled and subjected to regular sintering, by which the sheet is obtained. In the case of an Fe-6.5%Si alloy known as silicon steel, a powder of this alloy is used or a powder mixture prepared by mixing Fe-18%Si alloy powder with Fe powder so that a final alloy composition of Fe-6.5%Si is obtained is used. The above powder or powder mixture is compressed using an ethanol solution of polyvinyl butyral as a binder, heated to about 1,050 deg.C to undergo temporary sintering, cold or warm rolled, and then heated to 1,100-1,200 deg.C, by which regular sintering and uniformization of components by diffusion are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a soft magnetic alloy having a particularly low workability, for example, Fe-6.5% Si.
The present invention relates to a method for producing a sheet from an alloy or a sendust alloy. The present invention also relates to a core member made of the sheet.

[0002]

2. Description of the Related Art Fe-Fe is used as a core material of a transformer.
The Si alloy having the Si content of 6.5% has the zero magnetostriction and is the most preferable alloy composition. However, when the Si content exceeds 4.5%, the workability deteriorates. Rolling becomes impossible. Therefore, an alloy composition that can be rolled is usually adopted, but the so-called siliconizing method has been proposed as a manifestation of efforts to exceed this limit. This is because of an alloy having good workability, for example, Fe-3%
Rolling Si to make a thin plate, C using SiCl ₄
This is a method in which the amount of Si on the surface is increased by the VDA method, and Si is diffused by subsequent heating to bring the total amount of Si to around 6.5%. This technique is suitable for the production of very thin materials, but the cost is inevitable.

As another technique, it has been proposed that a slurry of an alloy powder is cast into a tape and then sintered (Japanese Patent Laid-Open No. 57-54247 and others). Although this technique is excellent as a method for producing a sheet from a difficult-to-work alloy, it generally has a problem that the obtained sheet has low toughness. The inventors studied with the aim of improving it,
As a result, it has been found that the toughness is enhanced by performing cold or warm rolling, and that particularly good results can be obtained by temporarily sintering and rolling the powder once and then performing the main sintering.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to make use of the new knowledge obtained by the present inventors to obtain a hard-working alloy,
In particular, in the technology of obtaining a sheet-shaped product from a soft magnetic alloy that is often used after being formed into a thin sheet such as a magnetic core member, a method of manufacturing a sheet-shaped product having high toughness, which is convenient for subsequent processing, is provided. Are also included in the object of the present invention.

[0005]

The method for producing a soft magnetic alloy sheet according to the present invention basically comprises mixing a soft magnetic alloy powder and a liquid containing a binder material, and forming the resulting slurry into a sheet. Into a sheet, and rolling the sheet green in a cold or warm state and then sintering to form a sheet.

In a preferred embodiment of the method for producing a soft magnetic alloy sheet according to the present invention, a powder of a soft magnetic alloy and a liquid containing a binder material are mixed, and the resulting slurry is formed into a sheet, and the sheet green is formed. Is heated to remove the binder and perform temporary sintering, and the pre-sintered sheet is rolled cold or warm and then main-sintered to form a sheet.

[0007] The magnetic core member of the present invention is obtained by processing a sheet of a soft magnetic alloy produced by the method according to any of the above-described basic and preferred embodiments into a desired magnetic core member shape by a method such as punching. It becomes.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a soft magnetic alloy sheet of the present invention can be applied to various hard-to-work soft magnetic alloys such as silicon steel and sendust. 4.5-13)% Si alloy, especially Fe-
This is a case where a 6.5% Si alloy is targeted. Therefore, the Fe-6.5% Si alloy will be described below as a representative. Fe- (4.5-13)% Si alloy is
As described above, cold rolling of 4.5% or less of Si is possible and need not be performed according to the present invention. On the other hand, a composition of more than 13% of Si reduces the electric resistance of the alloy and reduces the iron when used as a magnetic core. It is a reason for limiting the composition range that it is not adopted because of increased loss and disadvantage.

It is well known that in powder metallurgy, there are a pre-alloy method and a pre-mix method as means for realizing a desired alloy composition, and both methods can be employed in the present invention. The pre-alloy method is carried out using only an Fe alloy having a desired alloy composition, in this case, an Fe-6.5% Si alloy powder as a soft magnetic alloy powder. In the premix method, as a soft magnetic alloy powder, a Fe alloy powder containing an alloy component in a higher ratio than a desired alloy composition, and an Fe alloy powder containing an alloy component in a lower ratio, Alternatively, the method is performed using a mixed powder obtained by mixing Fe powder containing no alloy component in a ratio that finally obtains a desired alloy composition. Example 1 described later is a pre-alloy method, and Example 2 is the latter of the premix methods.

According to the premix method, the final alloy composition is F
When an alloy of e-6.5% Si is to be obtained, one of the materials used in Example 2, Fe-18Si, is a composition that forms a eutectic crystal and has a low melting point. This is an advantageous material for pre-sintering performed in a preferred mode. In addition to this, the Fe-Si system suitable for use is:
It is an Fe-50% Si alloy.

The binder for forming the powder of the soft magnetic alloy is a liquid material having a certain degree of viscosity, binding the powder, maintaining the shape of the green, and having the power of the air. Any substance that can be easily volatilized by heating or oxidatively decomposed and removed can be selected and used. In a mode in which cold or warm rolling is performed in the presence of a binder, it is also required that the alloy powder has no adverse effect during the rolling. From water-soluble polymer substances such as polyvinyl alcohol and polyvinyl butyral, an appropriate one may be selected according to each case. An appropriate dispersant can be added to the binder liquid as needed.

The slurry can be formed into a sheet by any method. The most preferable method is to flow the slurry on an appropriate substrate film and make the slurry have a predetermined thickness with a doctor blade. However, it is also possible to use simple casting or extrusion from a T-die.

The binder can be easily removed by heating the green to 200 to 400 ° C. in the atmosphere.

The cold or warm rolling is performed at a temperature between room temperature and 5 ° C.
Rolling at temperatures up to 00 ° C. is meant. The rolling reduction is
Although depending on the workability of the target soft magnetic alloy, the limit is generally 15 to 20% for cold rolling, and can be slightly higher for warm rolling. If rolling is performed twice or more, it will be necessary to perform annealing between them. Intermediate annealing is performed at 500 ° C. for Fe-6.5% Si.
It can be carried out by heating to about the required temperature for a required time.
On the other hand, diffusion annealing is performed at a higher temperature, for example, 1000
To 1200 ° C. for 1 hour to 15 minutes. Sintering is performed in an atmosphere of hydrogen gas or nitrogen gas. Temperature is 800-1000 ° C
Also in the atmosphere of an inert gas or a reducing gas.

In the method of the present invention, the green of the powder of the soft magnetic alloy or the pre-sintered body thereof is rolled cold or warm, so that the structure becomes finer and the grains are strengthened. As a result of sintering in that state, the structure of the product sheet is kept fine, and therefore, the toughness is high.

As is understood from this principle, when the method of the present invention is carried out by the premix method, at least one of the two mixed materials has high workability, so that cold or warm rolling is performed. It can be performed more advantageously than the pre-alloy method. In the case of using the premix method, considering the principle, even if two components to be mixed are combined with any alloy composition, it is only necessary to finally achieve a desired alloy composition by adjusting the proportion of the mixture. However, as a practical matter, if powders with very different components are combined, it is necessary to make the components uniform by diffusion in the final stage.If the temperature is increased or the heating time is lengthened, the crystals become coarser. Is not preferred. From this viewpoint, it is more advantageous to mix powders of alloys whose components do not greatly differ from each other. Ultimately, whether to use the pre-alloy method or the pre-mix method or the latter, what kind of alloy composition should be added depends on the final alloy composition, the availability of the material, and the significance of selecting those materials. (For example, the melting point drop due to the eutectic formation described above)
Should be determined in consideration of

[0017]

According to the present invention, as a result of performing cold or warm rolling, a product obtained by a method of manufacturing a sheet of a soft magnetic alloy by a known tape casting method can be obtained.
A sheet with a fine structure and high toughness can be manufactured. Thereby, intermediate and final processing for manufacturing the magnetic core member is facilitated, and a higher-level product can be manufactured at a reduced cost.

[0018]

EXAMPLES Example 1 An Fe-6.5% Si alloy was melted and powdered by a gas atomization method to obtain an alloy powder having an average particle diameter of 50 microns. 100 parts by weight of this powder was kneaded together with the mixture in the following proportions: 60 parts of anhydrous ethanol 1 part of polyvinyl butyral (binder) 0.1 part of sodium polyacrylate The obtained slurry was poured on a polyester film, and the thickness was adjusted with a doctor blade. A sheet having a thickness of 0.5 mm was dried. This sheet is cold-rolled to a thickness of 0.43 mm
(The rolling reduction is 15%). The rolled sheet was heated to 500 ° C. in the air to oxidize and remove the binder, and was annealed. Subsequently, cold rolling was performed again to obtain a sheet having a thickness of 0.35 mm (in this case, the rolling reduction was 15%).

Example 2 An Fe-18% Si alloy was melted and powdered by a gas atomizing method to obtain an alloy powder having an average particle diameter of 50 μm. This powder and Fe powder are mixed so that the final composition becomes Fe-6.5% Si, and the mixed powder is treated in the same manner as in Example 1, and cold-rolled to a thickness of 0.35 mm. I got a sheet. For these sheets, the crystal size was measured, and a tensile test was performed to examine the toughness. At the same time, the magnetic properties of the sheet were measured. For comparison, a similar test was performed on a material manufactured without performing cold or warm rolling by a conventionally known tape casting method. The results are summarized below.

Category Average crystal elongation Magnetic property size Br Iron loss value Example 1 (Prealloy) 10 μm 2% 5000 10 KHz 318 W / Kg Example 2 (Premix) 12 3 5000 10 382 Conventional material 70 0 5000 10 535

Claims (7)

[Claims] 1. A powder of a soft magnetic alloy and a liquid containing a binder material are mixed, the resulting slurry is formed into a sheet, and the sheet green is rolled cold or warm and then sintered. A method for producing a soft magnetic alloy sheet comprising: 2. A powder of a soft magnetic alloy and a liquid containing a binder material are mixed, the resulting slurry is formed into a sheet, and the sheet green is heated to remove the binder and temporarily sinter. A method for producing a soft magnetic alloy sheet, comprising rolling a pre-sintered sheet cold or warm and then sintering the sheet. 3. The method according to claim 1, wherein the slurry is formed by extrusion or casting. 4. The method according to claim 1, wherein the soft magnetic alloy powder is an Fe alloy powder having a desired alloy composition. 5. A powder of a soft magnetic alloy, a powder of an Fe alloy containing a higher proportion of an alloy component as compared with a desired alloy composition, a powder of an Fe alloy containing a lower proportion of an alloy component, or 3. The production method according to claim 1, wherein the method is carried out by using a mixed powder obtained by mixing an Fe powder containing no alloy component in such a ratio as to finally obtain a desired alloy composition. 6. A magnetic core member obtained by processing a sheet of a soft magnetic alloy produced by the method according to claim 1 into a shape of a magnetic core member. 7. The soft magnetic alloy contains Fe- (4.5-13)%.
7. The magnetic core member according to claim 6, which is a Si alloy.