JP3003225B2 - Method for producing sintered body of Fe-based soft magnetic material containing B - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered body of an Fe-based B-containing soft magnetic material.

[0002]

2. Description of the Related Art An Fe-Co alloy soft magnetic material is an alloy material having an ordered disorder transformation and forming a CsCl type ordered lattice phase at a transformation temperature, and has the highest saturation among currently known alloys. Because of its magnetic flux density, it is widely used as a magnetic material for yokes such as pulse motors and printer heads, and as a diaphragm for a receiver.

Conventionally, when this alloy is composed only of Fe and Co, it is impossible to suppress the ordered transformation by any heat treatment, so that cold working is impossible, and expensive V and Cr are added. However, it was necessary to improve the processability and manufacture.

[0004] However, it is still not enough to suppress the ordered transformation, and in order to obtain a molded product such as a part, particularly a complicated-shaped product, an attempt has been made to manufacture the product by powder metallurgy.

[0005] In addition, Fe and Co are also used in ordinary powder metallurgy.
Are difficult to diffuse to each other, so it is difficult to increase the density to obtain magnetic properties comparable to that of the melted material. In order to increase the density, it was necessary to use expensive fine powder, sinter for a long time, and perform HIP processing. After sintering, it was necessary to always perform a heat treatment for improving magnetic properties.

Further, when an alternating current is used as a soft magnetic material, a material having a high electric resistance and a small iron loss is required, but the Fe--Co alloy has a disadvantage that the electric resistance is low.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an Fe-based B-containing soft magnetic material sintered body having a soft magnetic property comparable to that of a molten material by overcoming the above-mentioned conventional disadvantages. It is to provide a method that can be manufactured.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, it has been found that the content of B is 0.1 to 0.1%.
At 1.0% by weight, a mixture of a raw material powder and a binder blended so that the balance substantially consists of Fe and Co is injection-molded, and the molded body is subjected to a debinding treatment.
By shifting to a sintering step to complete the sintering of the molded body and gradually cooling the sintered body at a cooling rate in the range of 2 to 50 ° C./min, the lattice strain which is easily recognized when the sintered body is cooled is reduced. The present inventors have found that the above problems can be sufficiently solved without any noticeable decrease in magnetic properties of the sintered body due to the above, and have led to the present invention.

That is, according to the present invention, first, the content of B is set to 0.1.
Fe powder, Co powder, Fe-Co alloy powder, and F so that the balance is substantially 1.0 to 1.0% by weight of Fe and Co.
A mixture is prepared by appropriately mixing the e-B alloy powder and a binder, and the mixture is molded into a predetermined shape by press molding or injection molding.
℃ to remove the binder, then 1100
2-50 ° C./mi after sintering in the temperature range of 1450 ° C.
This is performed by gradually cooling at a cooling rate in the range of n.

As a molding method, either press molding or injection molding may be used. However, injection molding is more effective when manufacturing a complicated-shaped product.
The powder, the Co powder, the Fe—Co alloy powder, and the Fe—B alloy powder each preferably have a particle size of 45 μm or less.

Further, as the binder to be added to the mixture in the present invention, it is possible to use a binder known as an injection molding powder metallurgy method, for example, polyethylene, wax or the like. If a binder that can be easily used is used, carbon may enter the sintered body during the removal of the binder, and in this case, the magnetic properties of the product are reduced. In order to prevent the trouble, it is preferable to use a binder which hardly generates residual carbon, for example, a binder mainly composed of wax.

Further, the operation of removing the binder may be performed by heat degreasing,
Solvent degreasing and other known methods are used, but when compared with other methods, the equipment provided for heat degreasing is the most convenient, so when mass-producing products, use nitrogen or hydrogen, or even a vacuum atmosphere. In the above, a degreasing treatment using a heating device is generally performed.

The sintering of the compact after the binder removal treatment is generally carried out in a hydrogen or vacuum atmosphere.

[0014]

[Operation] The B content of the blended powder and the sintered body after sintering must be 0.1 to 1.0% by weight.

If the B content is less than 0.1% by weight, the final relative density after sintering hardly increases, so that not only excellent magnetic properties are not exhibited, but also a predetermined value of electrical resistance is obtained. Hateful.

On the other hand, if the B content exceeds 1.0% by weight, the magnetic flux density rapidly decreases and cannot be used as a soft magnetic material.

It is preferable that elements other than Fe, Co, and P are not contained, but if the magnetic flux density of the soft magnetic properties of the sintered body is not in the range of B35 = 20,000 G or less, it can be used. Absent.

The powder mixed with the alloy magnet composition is mixed with, for example, a paraffin wax-based binder and molded.
The binder is removed at a temperature of about 00 ° C., and the temperature for removing the binder may be appropriately selected according to the properties of the binder used in forming the product.

In the present invention, the sintering temperature is set at 110
However, in this case, when the sintering process is performed at a temperature lower than 1100 ° C., the sintering phenomenon hardly proceeds even if the same temperature is maintained for a long time, and the sintered body This is because it is difficult to increase the relative density of the product, and as a result, the magnetic properties of the product cannot be improved.

When sintering is carried out at a temperature exceeding 1450 ° C., although a high-density sintered body is obtained, a large amount of liquid phase appears during sintering, so that the shape of the product is lost or Since the surface is melted, it becomes difficult to manufacture a product having a predetermined shape and dimensions.

The sintered body after sintering is 2 ° C./min or more, 50
It is necessary to gradually cool at a cooling rate of not more than ° C / min.

The presence of lattice strain in the sintered body hinders the movement of the magnetic domain wall, which has the effect of lowering the soft magnetic properties.

In order to eliminate this effect, it is necessary to gradually cool the compact after sintering at a cooling rate of 50 ° C./min or less.

If the cooling rate of the sintered body exceeds 50 ° C./min, lattice strain is generated in the sintered body when the sintered body is cooled, and the lattice strain remains as it is at room temperature. become.

The reason why the cooling rate is set to 2 ° C./min or more is that even if the cooling rate is unnecessarily reduced, the effect thereof is not largely changed, and the processing time of the product is only prolonged. .

When a raw material powder having an average particle size of more than 45 μm is used, the amount of binder added to the mixture increases, the sintering progresses slowly, and the final relative density of the sintered body increases. Since it does not increase and the magnetic properties become difficult to improve, Fe powder and
The average particle size of the e-B alloy powder is specified as a limit of 45 μm or less.

[0027]

EXAMPLES Example 1 Fe-50 wt% Co alloy powder having an average particle diameter of 9 μm and Fe-44 wt% B master alloy powder having an average particle diameter of 20 μm were used as raw material powders, and the B content was 0.2%. %, A Co content of 49% by weight and a Fe content of 50.8% by weight are sufficiently mixed with a raw material powder, and a wax-based binder having a content of 40 to 50% is added thereto. After kneading at 1500 ° C., the mixture was granulated into pellets.

The pellets are injection-molded into a mold under an injection pressure of 1200 kg / cm ² using an injection molding machine, and the obtained molded body is kept at 300 ° C. to remove a wax-based binder. A sintering treatment was performed at 1300 ° C. for 2 hours, and cooled at a cooling rate of 10 ° C./min to room temperature.

An excitation coil and a search coil are wound around the sintered body for 50 turns, and a BH hysteresis curve is drawn by a DC recording magnetometer, and an external magnetic field 3
The magnetic flux density (B35), coercive force (Hc), and maximum magnetic permeability (μmax) were determined at 5 Oe.

The results are as shown in Table 1. The sintered density was 95%, the electric resistance was 13 μΩcm, the magnetic flux density was 20,000 G, and the coercive force was 2.2.
Oe, the maximum magnetic permeability was 4500 μmax, and it was clarified that excellent magnetic properties were exhibited.

When all of Examples 2 to 6 were treated in the same manner as in Example 1, they had the composition shown in Table 1, and
In the case of the raw material formulations shown in Table 1, in each case, the results were almost the same as those of Example 1.

Comparative Example 1 Only raw material powder having a composition in which the content of B was 0.5% by weight, the content of Co was 49% by weight, and the content of Fe was 50.5% by weight was used. A compression-molded body was manufactured and treated in the same manner as in Example 1. The result was that the sintered density was only 91%, the magnetic flux density was only 16,000 G, and the maximum magnetic permeability was 3,000 μmax. Good results as in the examples were not obtained.

Comparative Example 2 This is an example in which a product containing no B was prepared, and the composition of the composition except for the lower limit of 0.1% by weight of the B content of claim 1 was examined, and the electrical resistance was 10 μΩcm. And the magnetic flux density is also inferior to 15,000 G.

Comparative Example 3 The content of B was 0.05% by weight, the content of Co was 49% by weight, and the content of Fe was 50.95% by weight.
This is an example of a composition excluding the lower limit of the B content of 0.1% by weight, which has a deteriorated electric resistance of 11 μΩcm, a poor magnetic flux density of 15,500 G, and a maximum permeability. The magnetic susceptibility has also been degraded to 3,100 G / Oe.

Comparative Example 4 The content of B was 1.5% by weight, the content of Co was 49% by weight, and the content of Fe was 49.5% by weight. This is an example in which the composition exceeds 1.0% by weight, and the magnetic flux density is also 10,000 as in Comparative Example 2.
0G is inferior, and the maximum permeability is 1,800G
/ Oe.

Comparative Example 5 The content of B was 0.5% by weight, the content of Co was 49% by weight, the content of Fe was 50.5% by weight. However, since the cooling after sintering was performed with cooling water at 0 ° C., the cooling rate was the upper limit of claim 1.
This is an example in which the temperature exceeds 0 ° C./min to 600 ° C./min. The magnetic flux density is inferior to 11,000 G, and the maximum magnetic permeability is degrading to 2,000 G / Oe.

COMPARATIVE EXAMPLE 6 The B content was 0.5% by weight, the Co content was 49% by weight, and the Fe content was 50.5% by weight. However, cooling after sintering is 25 ° C
In this example, the cooling rate was 400 ° C./min, which exceeded the upper limit of 50 ° C./min in claim 1, and the maximum magnetic permeability was 2,500 G / Oe. And the magnetic flux density is 12,000G
And it is decreasing.

Comparative Example 7 The content of B was 0.5% by weight, the content of Co was 49% by weight, and the content of Fe was 50.5% by weight. However, since the cooling condition after sintering was oil cooling, the cooling rate was 50 ° C. which was the upper limit of claim 1.
/ Min, exceeding 200 ° C./min, the maximum magnetic permeability has been extremely deteriorated to 3,100 G / Oe, and the magnetic flux density has decreased to 14,000 G.

Comparative Example 8 The content of B was 0.5% by weight, the content of Co was 49% by weight, and the content of Fe was 50.5% by weight. However, since the cooling condition after sintering was oil cooling, the cooling rate was 50 ° C. which was the upper limit of claim 1.
In this example, the maximum magnetic permeability has decreased to 3,200 G / Oe, and the magnetic flux density has decreased to 16,000 G.

Comparative Example 9 The average particle size of Fe-50 wt% Co gold powder was 48 to 58 μm.
Wherein the sintered body has a density of only 80% and a maximum magnetic permeability of 1,200 G /
Oe and the magnetic flux density is 9,800
It is decreasing to nearly 50% with G.

Comparative Example 10 This is an example in which the sintering temperature is 1000 ° C. and the sintering is performed at a temperature of 1100 ° C. or less, which is the lower limit of the sintering temperature of claim 2, wherein the density of the sintered body is 85% In addition, the maximum magnetic permeability has been degraded to 1,900 G / Oe, and the magnetic flux density has been reduced to 10,500 G, which is close to 50%.

Comparative Example 11 This is an example in which the sintering temperature was 1470 ° C. and the sintering was performed at a temperature exceeding 1450 ° C., which is the upper limit of the sintering temperature according to claim 2, wherein the shape of the compact was sufficiently high. I couldn't keep it.

From the above results, it was confirmed that the sintered body manufactured according to the present invention had high magnetic flux density, low coercive force, and high magnetic permeability as its soft magnetic properties, and the electrical resistance was also improved. It turns out that it is an excellent magnet.

[0044]

[Table 1]

The symbol * in Comparative Example 1-11 in Table 1 is a parameter outside the scope of the present invention.

[0046]

According to the present invention, while having excellent soft magnetic properties, the density is higher than that of the conventional Fe-Co alloy, the electric resistance is improved, and a complicated shape is obtained by using the injection molding method. It has become possible to stably supply soft magnetic sintered bodies with high-performance soft magnetic properties, and by disclosing the manufacturing method of industrially useful products, it will contribute greatly to the industry. is there.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI C22C 38/00 303 B22F 3/10 E (58) Field surveyed (Int.Cl. ⁷ , DB name) B22F 1/00-7 / 08 C22C 33/02 C22C 38/00 303

Claims (1)

(57) [Claims] 1. A mixture comprising a raw material powder containing B in an amount of 0.1 to 1.0% by weight and having a composition of an Fe-based alloy in which the balance is substantially Fe and Co and having an average particle size of 45 μm or less, and a binder. After the injection molding, the obtained molded body is subjected to a debinding treatment, and the above-described debinding treated molded body is heated and sintered at a temperature of 1100 to 1450 ° C. After that, the sintered body is
F consisting of slow cooling at a cooling rate in the range of ° C / min.
A method for producing an e-based B-containing soft magnetic material sintered body.