JPH08120393A - Production of iron-silicon soft magnetic sintered alloy - Google Patents

Abstract

PURPOSE: To provide the magnetic alloy with improved fluldability during the forming, and with the excellent magnetic characteristic by adding kneading and the prescribed binder to the fine powder of Fe-Si alloy, and forming it after the granulation, formation and degreasing. CONSTITUTION: The binder consisting of, by weight, 0.1-2.0% polyvinyl alcohol, methyl-cellulose, and polyacrylamide in a single or composite manner and water is added to the fine powder of Fe-Si alloy, and kneaded and stirred to make the slurry of 20-50% in water content. This slurry is granulated to 20-400μm in the mean grain size by using a spray dryer device. Formation is made by using this granulated powder, and degreasing is achieved in the gaseous hydrogen flow to allow the sintering in vacuum or in the inert gas. The amount of the residual oxygen and carbon in the sintered body is reduced, the fluidability and lubricability of the powder during the formation is improved to improve the dimensional precision of the formed body and the productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a powder metallurgy
The present invention relates to a method for producing an e-Si soft magnetic sintered alloy, and in particular, a specific binder is added to a specific Fe-Si alloy fine powder and kneaded to form a slurry. The granulated powder having a particle size of up to 400 μm improves the fluidity and lubricity of the powder during molding, improves the molding cycle, improves the dimensional accuracy of the molded body, and improves the thickness and shape of the yoke with a thickness of 10 mm or more. The present invention relates to a method for producing an Fe—Si soft magnetic sintered alloy capable of providing an Fe—Si soft magnetic sintered alloy having a complicated shape such as

[0002]

2. Description of the Related Art Today, various soft magnetic materials are used as iron cores or yoke materials for home electric appliances, computer peripherals, transformers and other electric devices, as well as cores for magnetic heads, and have complicated shapes. Higher performance is required as well as smaller size and lighter weight. Typical typical soft magnetic materials at present are soft ferrites such as Mn-Zn and Ni-Zn ferrites, permalloy containing Fe-Ni as a main component, Fe-Al-Si-based sendust, and Fe-Co-based permanent. Mendules, Fe-Si-based silicon steel, etc. may be mentioned.

Among the above, Fe--Si type silicon steel is
It has a high saturation magnetic flux density and a high electric resistivity compared to other soft metal magnetic materials.Because of low iron loss, it can be widely used for AC applications, such as AC / DC relays and high frequency iron cores. Is used for. In general, when Si is added to Fe, the magnetic permeability and electric resistance are increased, and thus the AC magnetic characteristics are improved, but as the amount of Si added is increased, the material becomes a brittle alloy, and plastic working, cold rolling, The cutting process becomes difficult and the processing yield decreases. For this reason,
In particular, for Fe-Si based alloys containing 3 wt% or more of Si, cost-manufacturable parts and applications were naturally limited.

[0004]

In order to make up for such a drawback, there is also adopted a method for producing a complex shaped part by precision casting in which a molten Fe-Si alloy is poured into a mold and taken out after cooling. However, there are drawbacks that the gravity segregation of Fe and Si occurs at the time of solidification, large pores remain to cause deterioration of the magnetic properties, and the quality becomes unstable.

Further, after sintering, Fe powder having a large average particle diameter and Fe--Si powder having a small average particle diameter are mixed and mixed so as to have a required composition, and the plastic deformation of the Fe powder is utilized to function as a binder. A powder metallurgy method in which compression molding is performed and then sintering is also proposed (Japanese Patent Laid-Open No. 62-27545), but since the powder flowability is poor, the mold filling amount during molding tends to vary, and the size after sintering There is a drawback that the accuracy becomes unstable, and it has been difficult to manufacture a product which is required in recent years and has a thick shape of 10 mm or more, a complicated shape and excellent dimensional accuracy.

[0006] Conventionally, in an Fe-Si alloy, a metal injection molding method (MIM) has been applied in order to produce a body having a predetermined shape. However, in the metal injection molding method, a binder addition amount is generally about 10 wt. %, There is a problem that oxygen and carbon are likely to remain after sintering, leading to deterioration of magnetic properties, particularly magnetic permeability. Therefore, a method has also been proposed in which a coupling agent is added to reduce the binder addition amount to reduce the residual carbon amount and residual oxygen amount after sintering to improve the magnetic properties (Japanese Patent Laid-Open No. 1-212702 to 212706). However, even with this method, it was difficult to produce a sintered body having excellent magnetic properties.

Further, in the metal injection molding method, the shrinkage ratio during sintering generally becomes large, so that in a product having a large size and shape, cracks occur during sintering and blisters occur during degreasing, so that the thickness is especially 10 mm. It was difficult to obtain a product having the above-mentioned thick-walled shape, complicated shape, and excellent dimensional accuracy.

On the other hand, polyvinyl alcohol is used as a binder in the production of oxides such as sintered ferrite. For example, after calcined powder of ferrite is wet-ground to an average particle size of about 1 μm by a ball mill, the binder such as polyvinyl alcohol is used. 0.6 to 1.0 wt%
A method of producing granulated powder of 50 to 100 μm by a spray dryer, molding and sintering the granulated powder, etc. is performed. This is effective because carbon hardly remains in the sintered body after sintering.

However, Fe-S which is the object of the present invention
In the case of the i-based soft magnetic sintered alloy, it is necessary to perform the sintering in a vacuum or an inert gas. Therefore, unless it is processed under the optimum degreasing conditions, oxygen and carbon will naturally remain in the sintered body. However, since the sintering density is lowered and the magnetic properties are also deteriorated, the above-mentioned ferrite manufacturing method cannot be easily applied.

As described above, in the method for manufacturing the Fe--Si soft magnetic sintered alloy, an attempt has been proposed to improve the workability of the Fe--Si alloy and further improve the molding method by the metal injection molding method. However, by any of the methods, a Fe—Si based soft magnetic sintered alloy having a thick shape with a thickness of 10 mm or more, a complicated shape such as a yoke, and excellent magnetic characteristics as required in recent years is manufactured. Was difficult.

According to the present invention, in a method for producing a sintered alloy by powder metallurgy, the reaction between the alloy powder and the binder is suppressed to reduce the residual oxygen content and residual carbon content in the sintered body, and at the time of molding. By improving the fluidity and lubricity of the powder, the dimensional accuracy of the molded body and the productivity are improved, and the complex shape such as a thick wall shape with a thickness of 10 mm or more, a yoke, etc. An object of the present invention is to provide a method for producing a Fe-Si based soft magnetic sintered alloy having characteristics.

[0012]

The inventors have found that Fe--Si
As a result of various studies on methods that can suppress the reaction between the base alloy powder and the binder and reduce the residual oxygen content and residual carbon content of the sintered body, a small amount of polyvinyl alcohol, methyl cellulose, or polyacrylamide can be used as the binder alone or in combination of two types. By using a binder composed of the above and water, it is possible to suppress the reaction between the Fe-Si alloy powder and the binder in the spray granulation step,
It was found that the residual oxygen content and residual carbon content in the sintered body after sintering can be significantly reduced.

That is, when each of the above binders is polyvinyl alcohol, methyl cellulose, and polyacrylamide alone, a feeder for supplying powder to a mold at the time of molding even if spray granulation is performed at an addition amount of 2.0 wt% or less. It is possible to obtain an interparticle bonding force sufficient to withstand internal vibration, sufficient fluidity and molded product strength. When two kinds of these binders are combined, the amount is 1.5 wt% The same effect as above can be obtained, and the lubricant used if necessary can be a very small amount of 0.3 wt% or less, and the binder amount can be made smaller than the addition amount of about 10 wt% in the conventional metal injection molding. We have found that it can be significantly reduced.

The Fe-Si alloy powder to be used is generally produced to have the same composition as the sintered alloy by the ingot / pulverization method and atomizing method, but these powder particles have a considerable strain energy inside or on the surface. Due to this distortion, an electric double layer is likely to be formed between the binder and the interface of the metal powder after the granulation, and the static electricity of the granulated powder extremely reduces the fluidity. Therefore, a granulated powder having excellent fluidity can be obtained by a heat treatment step of removing powder distortion before granulation, that is, by performing heat treatment in a temperature range of 300 ° C to 800 ° C in a vacuum or in an inert gas. I found out.

In addition, since the ingot / pulverization method and atomized powder are generally high in crushing cost, they are fragile Fe ₃
Fe containing Fe ₃ Si as a main component and having an Al type crystal structure
After coarsely crushing the Si-based ingot, this alloy powder is wet-milled in water or an organic solvent with a ball mill, an attritor, or the like to produce a fine powder with little residual distortion of the powder particles, and after drying, carbonyl Fe powder is formed into the required composition. It was found that a granulated powder having excellent fluidity can be obtained at low cost by adding and mixing as described above and performing spray granulation.

Further, in the step of preparing a slurry by adding and kneading the above binder to a mixed powder of the Fe-Si alloy powder containing Fe ₃ Si compound as a main component and Fe powder,
It has been found that the oxidation reaction between water and the Fe-Si alloy powder can be largely prevented by cooling to -10 ° C and stirring the slurry. Further, it was found that the binder can be almost removed by degreasing in hydrogen, so that the sintering after degreasing can be advanced by continuing to raise the temperature as it is, and the sintering density is also improved.

The above binder is added to the Fe-Si alloy powder obtained by wet pulverization and kneaded to form a slurry at a low temperature of 0 ° C to 10 ° C, and the slurry has an average particle size of 20 µm by a spray dryer. By molding using the granulated powder obtained so as to have a particle size of up to 400 μm, the granulated powder has a sufficient binding force, and combined with excellent lubricity due to the effect of the binder and the lubricant, the powder flow Fe-having excellent magnetic properties in a thick-walled shape and a complicated shape with excellent dimensional accuracy after sintering without significantly improving the density of the molded body or shortening the life of the molding machine.
The present invention has been completed by finding that a Si-based soft magnetic sintered alloy can be efficiently obtained.

That is, in the present invention, polyvinyl alcohol, methyl cellulose, and polyacrylamide are used alone or in two kinds in the Fe-Si alloy powder in which the intragranular strain is relaxed by the wet pulverization utilizing the brittleness of the Fe-Si alloy. The composite is 0.1-2.0 wt% and the water content is 20-5.
After adding and kneading a binder consisting of 0 wt% water,
Stir at a temperature of 0 ° C to 10 ° C to form a slurry, and the slurry has an average particle size of 20 by a spray dryer device.
a granulated powder having a particle size of μm to 400 μm, and using the granulated powder,
Fe-Si-based soft magnetic material characterized by degreasing in flowing hydrogen after forming, and further sintering in vacuum or an inert gas and homogenizing heat treatment to remove strains to obtain a sintered alloy. It is a method for producing a sintered alloy.

In the composition of the Fe-Si alloy targeted by the present invention, the addition of Si to Fe is effective in increasing the magnetic permeability and electric resistance, but if Si is less than 1 wt%, the effect of such addition is obtained. However, if the content exceeds 10 wt%, the saturation magnetic flux density is extremely reduced and the practical use is lost.
The content is set to 10 wt%. Further, Fe-Si as a main component an Fe ₃ Si compound having a Fe ₃ Al type crystal structure
The amount of Si in the system alloy powder is 6.5 wt% to 23 wt%, and if the Fe content is less than 6.5 wt%, the Fe ₃ Si compound Fe has a body-centered cubic structure, and the Fe-Si alloy contains 6.5 wt% Si. Fe obtained by using powder
-Si alloy has Si of 1 to 6.5 wt% and Si of 2
If it exceeds 3 wt%, Fe ₅ Si ₃ having a close-packed hexagonal crystal structure precipitates in the Fe ₃ Si compound, which hinders the crystallization reaction, which is not preferable.
₃ Fe-containing a required amount of Si containing Si compound as a main component
The compounding ratio of Si powder and Fe powder can be appropriately selected.

In the present invention, the raw material powder for producing the Fe--Si system sintered alloy is a single ingot / pulverized powder having the required composition, atomized powder, and a single alloy having the required composition. Wet-milled powder or, for example, powder obtained by wet-milling Fe—Si alloy powder containing Fe ₃ Si compound as a main component, and then adding and mixing Fe powder to adjust the required composition,
Furthermore, in order to improve iron loss, magnetic permeability, and manufacturability, M
n, S, Ta, Cr, Ti, Al, Zr, V, W, C
Known Fe-Si, such as wet pulverization of alloys containing additive elements such as u, Mg, Ag, Pb, Sb, Mo, Te, and Se
Alloy powders can be used.

As the method for producing the Fe-Si alloy powder, a known method such as an ingot / pulverization method or an atomizing method can be appropriately selected. However, in addition to these powder effects, internal strain or surface strain is added to the powder particles by quenching, impact or oxidation at the manufacturing stage,
When a binder or the like is directly added to these powders for granulation, an electric double layer is formed at the interface between the binder and the metal powder, and the fluidity of the granulated powder after granulation remarkably decreases due to static electricity. For this reason, it is necessary to incorporate a heat treatment step for removing the distortion of the powder before making it into a slurry. If the heat treatment temperature in vacuum or in an inert gas is less than 300 ° C., strain relief is not sufficient, and if the temperature exceeds 800 ° C., a part of the powder begins to be welded, so the heat treatment temperature is 300 ° C. to 800 ° C.
A temperature of ° C is preferred.

On the other hand, in order to reduce the cost of the raw material and alleviate the distortion of the powder particles, an ingot containing a Fe ₃ Si compound, which is a particularly fragile Fe--Si alloy composition as a main component, was prepared and roughed. After pulverizing, Fe powder is added to the powder obtained by wet pulverizing with a ball mill, attritor, etc., which is not relatively distorted in a solvent and dried so that the required composition is obtained, and a binder or the like is added to the powder to granulate. Then,
The fluidity of the granulated powder after granulation is not deteriorated by static electricity, and the fluidity is good. In particular, it is important to cool the mixture to 0 ° C. to 10 ° C. and stir the slurry in order to prevent the oxidation reaction between the water or organic solvent and the Fe—Si alloy powder during wet pulverization as much as possible. Further, the average particle size of the alloy powder by the atomizing method generally exceeds 5 μm, but the crushing particle size can be arbitrarily set in the wet crushing, and the average particle size of 3 μm or less can be obtained, and the residual carbon amount is reduced as compared with the atomizing method. It can be manufactured at low cost.

Binder In the present invention, the binder to be added to make the alloy powder into a slurry is polyvinyl alcohol,
Methyl cellulose, polyacrylamide alone or 2
Use a mixture of types with water added. As the binder, when each of polyvinyl alcohol, methyl cellulose, and polyacrylamide is alone, if the addition amount is less than 0.1 wt%, the granulated powder is broken during powder feeding before molding and the fluidity of the powder is significantly reduced, On the other hand, if it exceeds 2.0 wt%, the residual oxygen amount and the residual carbon amount in the sintered body increase, the magnetic permeability decreases, and the sintered body is easily deformed.
Is preferred. When the content of two kinds of these binders used in combination is similar to the case of using each of the above binders alone, if the content is less than 0.1 wt%, the bonding force between the particles in the granulated powder is weak, and therefore, before molding. The granulated powder is broken during powder feeding, and the fluidity of the powder is significantly reduced.
When the content exceeds 0.1 wt%, the residual oxygen content and the residual carbon content in the sintered body increase, the magnetic permeability decreases, and the sintered body is easily deformed. Therefore, the content of 0.1 wt% to 1.5 wt% is preferable. It is a range.

In the present invention, the content of water added to the mixed slurry of the raw material powder and the binder is 20 wt%.
When the amount is less than the above, the concentration of the slurry in which the alloy powder and the binder are kneaded becomes high, and the viscosity increases too much, so that the slurry cannot be supplied from the agitator described later to the spray dryer device, and 50 wt% is added. If it exceeds, the slurry concentration becomes too low, precipitation occurs in the stirrer and the slurry supply pipe of the stirrer, the supply amount becomes unstable, and the average particle size of the granulated powder obtained by the spray dryer device becomes less than 20 μm. 20 wt% to 50 wt% is a preferable range because the particle size varies. More preferably, 30 wt% to 40 w
It is in the range of t%. As water, deoxidized pure water in order to suppress the reaction with the Fe-Si alloy powder as much as possible,
Alternatively, it is desirable to use water bubbling with an inert gas such as nitrogen. In addition, stirring the slurry after adding the binder is cooled to 0 ° C to 10 ° C with a chiller or the like,
The lower temperature can suppress the oxidation reaction between the alloy powder and water more, and at the water temperature exceeding 10 ° C., the oxidation reaction between the Fe—Si alloy powder and water is rapidly accelerated to increase the oxygen content. Is not preferred.

Further, glycerin,
Wax emulsion, stearic acid, phthalic acid ester, petriol, add at least one of lubricants such as glycol, or further, n- octyl alcohol, polyalkylene derivative,
Addition of an antifoaming agent such as a polyether derivative improves the dispersibility and homogeneity of the slurry and improves the powdering state in the spray dryer device, resulting in less air bubbles and a spherical shape with excellent lubricity and fluidity. It is possible to obtain the granulated powder of. When adding a dispersant or a lubricant, 0.0
If the content is less than 3 wt%, there is no effect in improving the releasability after molding the granulated powder, and if it exceeds 0.3 wt%, the residual carbon content and oxygen content in the sintered body increase and the coercive force increases. As the magnetic properties deteriorate, 0.03 wt% to 0.3 wt%
Is preferred.

Granulation Method In the present invention, the slurry obtained by adding the above-mentioned binder to the alloy powder and kneading the mixture into granulated powder by a spray dryer device. First, a method for producing granulated powder using a spray drier will be described. A slurry is supplied from a slurry stirrer to a spray drier, for example, sprayed by centrifugal force of a rotating disk, or atomized by a pressure nozzle tip. The sprayed droplets are instantaneously dried by hot air of the heated inert gas to become granulated powder, and fall naturally to the lower part in the collection unit.

The structure of the spray dryer device is as follows.
Either the disk rotating type or the pressure nozzle type described above may be used. However, since the fine powder Fe-Si alloy powder is very easily oxidized, the slurry storage part of the device or the granulated powder recovery part is inactive. It is preferable to have a closed structure that can be replaced by gas or the like and that can keep the oxygen concentration at 3% or less at all times.

Further, as the constitution of the recovery part of the spray dryer device, in order to instantly dry the liquid droplets sprayed from the rotary disk or the pressure nozzle, it is heated near the rotary disk or above the pressure nozzle. An injection port for injecting an inert gas is arranged, and a discharge port for discharging the injected gas to the outside of the recovery unit is provided in the lower part of the recovery unit.At that time, heating outside the device or attached to the device is performed in advance. It is preferable to maintain the injection port at a temperature corresponding to the temperature of the inert gas, for example, 60 to 150 ° C., so as not to lower the temperature of the inert gas heated to the required temperature in the vessel.

That is, when the temperature of the inert gas is lowered, the sprayed droplets cannot be dried sufficiently in a short time, so that the slurry supply amount must be reduced and the efficiency is lowered. When making granulated powder having a relatively large particle size, the number of revolutions of the rotating disk or the pressure of the pressurizing nozzle is reduced, but when the temperature of the inert gas is lowered, the spraying is performed. Since the droplets cannot be dried sufficiently, as a result, when the amount of supplied slurry is reduced, the efficiency of obtaining granulated powder having a large particle diameter is extremely reduced. Therefore, in order to feed the preheated inert gas into the recovery unit while maintaining the temperature of the inert gas as it is, it is preferable to maintain the temperature of the injection port at 60 to 150 ° C, and most preferably around 100 ° C.

Further, when the temperature difference between the inert gas injection port and the exhaust port is small, the processing efficiency tends to decrease,
The temperature of the outlet is desirably set at 50 ° C. or lower, preferably 40 ° C. or lower, and particularly preferably at room temperature. As the inert gas, nitrogen gas or argon gas is preferable, and the heating temperature is preferably 60 to 150 ° C.

The particle size of the granulated powder can be controlled by the concentration of the slurry supplied to the spray dryer device, the supply amount thereof, the number of revolutions of the rotary disk or the pressure of the pressure nozzle. When the particle size is less than 20 μm, the fluidity of the granulated powder is hardly improved, and when the average particle size exceeds 400 μm, the particle size is too large and the packing density in the mold at the time of molding decreases. It is not preferable because the density of the compact is also lowered, which in turn lowers the density of the sintered body after sintering. Therefore, the average particle diameter of the granulated powder is limited to 20 to 400 μm. Particularly preferably 5
It is 0 to 200 μm. Further, by performing undercutting and overcutting with a sieve, it is possible to obtain a granulated powder having an extremely high fluidity. Further, it is effective to add a small amount of a lubricant such as zinc stearate, magnesium stearate, calcium stearate, aluminum stearate or polyethylene glycol to the obtained granulated powder, because the fluidity can be further improved.

Any known powder metallurgical means can be adopted for the step after granulation, that is, the conditions and methods such as molding, sintering, heat treatment and the like. An example of preferable conditions is shown below. The molding can be performed by any known molding method, but is most preferably performed by compression molding, and the pressure is preferably 0.3 to 2.0 Ton / cm ² . In the case of molding a product having a complicated shape, the spray granulated powder is excellent in fluidity, so that it can be formed by a multi-stage press machine, and it is possible to cope with a product having a considerably complicated shape.

After molding and before sintering, a general method of heating in vacuum or 100 ° C. to 200 ° C./in hydrogen flow
It is preferred that the binder be removed by a method in which the temperature is raised over a period of time and held at 300 ° C. to 800 ° C. for 1 to 2 hours. In particular, when producing an Fe-Si alloy having excellent magnetic properties, it is indispensable to perform debinding processing in flowing hydrogen in order to reduce the amount of residual oxygen and the amount of residual carbon after sintering. . At a temperature of 300 ° C. or lower, the binder is not sufficiently removed, the binder cannot be completely removed, and a high-purity sintered body cannot be obtained. Further, at a temperature higher than 800 ° C., the sintering cannot be performed because the sintering of the powders progresses before the impurities on the surface of the raw material powder are removed.

Unlike the case of the metal injection molded body, since the binder addition amount is as small as a fraction, even if the temperature rising speed at the time of debinding is set to a speed almost equal to that without the binder. In particular, since cracks and blisters do not occur, there is an advantage that production can be performed with higher efficiency than metal injection molding. After the binder removal treatment, it is preferable to carry out sintering by heating in a vacuum or in an inert gas, and the temperature rising rate after the temperature exceeds 800 ° C. may be arbitrarily selected. 300 ° C / hour, etc.
A known heating method can be adopted.

Sintering of the molded product after the binder removal treatment and heat treatment conditions after the sintering are appropriately selected according to the selected alloy powder, but the sintering and heat treatment conditions after the sintering are 1200 ° C. A sintering step of holding at 1350 ° C. for 1 to 2 hours and a homogenizing treatment step of holding at 300 ° C. to 1000 ° C. for 1 to 2 hours are preferable. A more preferable homogenization treatment temperature is 500 ° C to 900 ° C.

[0036]

The present invention is based on Fe-S which is heat-treated to remove strain.
An i-based atomized alloy powder or a wet-pulverized powder of Fe—Si alloy containing Fe ₃ Si as a main component, mixed with Fe powder, was mixed with polyvinyl alcohol, methyl cellulose, polyacrylamide alone or in combination, and water. An average particle size of 20 μm to 400 μm is obtained with a spray dryer device by adding a binder consisting of, kneading to form a slurry, and stirring the slurry at a low temperature of 0 ° C. to 10 ° C.
The granulated powder of, and by molding, degreasing and sintering using the granulated powder, combined with excellent lubricity due to the effect of the binder and lubricant, the fluidity of the powder is significantly improved, Fe-Si soft magnetic calcination that has a thick wall shape and a complicated shape and has excellent magnetic properties, which improves the cycle, does not reduce the variation in the density of the compact, and has excellent dimensional accuracy after sintering. Bond gold is obtained.

Further, the manufacturing method according to the present invention can significantly reduce the degreasing time as compared with the metal injection molding method, and at the same time, can reduce the residual oxygen content and the residual carbon content, thereby reducing the manufacturing cost and stabilizing the quality. There is an advantage that it can be realized. Furthermore, since the granulated powder in the present invention is hardly oxidized in the atmosphere because it is covered with the binder, there is an advantage that workability in the molding step is improved.

[0038]

【Example】

Example 1 Si 3.0 wt% Remaining Fe Fe average particle size 9.8 μm
After the gas atomized powder of No. 1 was heat-treated in Ar gas at the heat treatment temperature shown in Table 1, binder, water, lubricant, etc. of the kind and the addition amount shown in the same table were added to the powder, and each was mixed at the stirring temperature shown in the same table for 5 A slurry was prepared by stirring for a time. The inside of the chamber was replaced with nitrogen gas for the slurry to adjust the oxygen concentration to 0.
Granulation was carried out by setting the hot air inlet temperature to 100 ° C. and the hot air outlet temperature to 40 ° C. by means of a closed disk rotary spray dryer device that was lowered to 5%.

The granulated powder was pressed with a press at a pressure of 1 To.
After forming into a shape of 10 mm × 15 mm × thickness of 10 mm at n / cm ² , a binder removal treatment of heating from room temperature to 600 ° C. at a heating rate of 100 ° C./hour in flowing hydrogen gas was performed, and subsequently in vacuum. After performing sintering by heating to 1300 ° C. and holding for 2 hours, uniformized heat treatment of holding at 800 ° C. for 1 hour and cooling were performed to obtain a sintered body. Further, at this time, a ring of 30φ × 24φ × 5t was press-molded as a sample for magnetic property measurement, and degreasing, sintering and homogenizing heat treatment were performed simultaneously with the above materials.

Next, the direct current magnetic characteristics are determined by AUTOMATIC.
D. C. B-H CURVESTRACER, as shown in Table 2, maximum permeability μ _max ,
The values of magnetic flux density B ₂₀ at coercive force Hc and ₂₀ Oe were obtained. Moreover, the iron loss, which is an AC magnetic characteristic, was obtained by an iron loss evaluation device. Table 2 shows the fluidity of the granulated powder, the relative density of the sintered body, the amount of residual oxygen and the amount of residual carbon, and the magnetic properties. Here, as the relative density, the density of the Fe-3% Si ingot was used as the true density. In addition, the fluidity is 10
It was measured by the time required for 0 g of the raw material powder to fall spontaneously and pass through. The particle size of the granulated powder is a value obtained by sieving with a mesh and averaging the weight. Flowability of granulated powder is 20 sec
The target is as follows, and the iron loss is magnetic flux density 5kG, frequency 1
The target value was 1000 (J / m ³ ) or less in MHz. Moreover, cracks, cracks, and deformation were not observed in the obtained sintered body at all. In addition, when the heat treatment temperature of the raw material powder is 150 ° C. and 900 ° C., the fluidity of the powder of the comparative examples (No. 1 and No. 5) in Tables 1 and 2 is poor,
Since it is difficult to manufacture a complex shaped product by press molding, it was excluded.

Example 2 A raw material consisting of 14.4 wt% of the balance of Fe was subjected to high frequency melting in an Ar gas atmosphere to obtain a button-shaped ingot alloy of a Fe ₃ Si compound, and then the ingot was roughly crushed and further disc milled. Was crushed to a particle size of about 30 μm. The powder was charged into a ball mill containing the solvent shown in Table 3, and then the ball mill was placed in a tank cooled to 5 ° C. with a chiller and rotated for 10 hours to finely pulverize. The average particle size of the obtained Fe ₃ Si compound powder was 3.3 μm. After the pulverized slurry was dried in a vacuum, Fe ₃ Si compound powder and carbonyl Fe powder having an average particle size of 4.7 μm were added and mixed so as to have a composition of Fe-3% Si. A binder, water, a lubricant, etc. were added in amounts to be added, and the mixture was stirred at the stirring temperatures shown in the table for 5 hours each to prepare a slurry. The hot air inlet temperature was set to 100 ° C. and the hot air outlet temperature was set to 40 ° C. by a closed disk rotary spray dryer device in which the inside of the chamber was replaced with nitrogen gas to reduce the oxygen concentration to 0.5%. And granulated.

The granulated powder was pressed with a press at a pressure of 1 To.
After forming into a shape of 10 mm × 15 mm × thickness of 10 mm at n / cm ² , a binder removal treatment of heating from room temperature to 600 ° C. at a heating rate of 100 ° C./hour in flowing hydrogen gas was performed, and subsequently in vacuum. After performing sintering by heating to 1300 ° C. and holding for 2 hours, uniformized heat treatment of holding at 800 ° C. for 1 hour and cooling were performed to obtain a sintered body. At this time, a ring of 30φ × 24φ × 5t was press-molded as a sample for magnetic property measurement, and degreasing, sintering, and homogenizing heat treatment were performed simultaneously with the above sample.

Next, direct current magnetic characteristic measurement is performed by AUTOMAT.
IC D. C. B-H CURVES TRACER
And the maximum magnetic permeability μ as shown in Table 4.
_The values of _max , coercive force Hc, and magnetic flux density B ₂₀ at ₂₀ Oe were obtained. Moreover, the iron loss, which is an AC magnetic characteristic, was obtained by an iron loss evaluation device. Table 4 shows the fluidity of the granulated powder, the relative density of the sintered body, the residual oxygen content and the residual carbon content, and the magnetic properties. Here, as the relative density, the density of an ingot of Fe-3% Si was used as the true density. The fluidity was measured by the time required for 100 g of the raw material powder to spontaneously drop and pass through a funnel tube having an inner diameter of 8 mm. Further, the particle size of the granulated powder is a value obtained by sieving through a mesh and weight-averaged. The fluidity of the granulated powder is 20se
The target was c or less, and the iron loss was 1000 (J / m ³ ) or less at a magnetic flux density of 5 kG and a frequency of 1 MHz. In addition, cracks, cracks, and deformation were not observed in the obtained sintered body. In Example 2, Fe ₃ S
F by wet-milled powder of i-compound and Fe powder
The production of the e-Si-based compound has an advantage that the raw material cost can be reduced as compared with the atomized powder.

Example 3 Example 1 in which a heat treatment of 400 ° C. × 2H was performed in Ar gas.
Of the raw material powder (Table 5) and Fe ₃ Si are wet pulverized, and the mixed powder (Table 7) of the powder and the carbonyl Fe powder of Example 2 is mixed with the binder and water in the types and addition amounts shown in Tables 5 and 7, respectively. A lubricant or the like was added, and the mixture was stirred at a stirring temperature of 5 ° C. for 5 hours to prepare a slurry. The slurry was spray-granulated under the same conditions as in Example 1. The granulated powder is pressed with a press machine at a pressure of 1 Ton / cm ² to 10 mm × 15 mm × thickness 10 m.
m shape, then room temperature to 600 ° C in flowing hydrogen
Is heated at a heating rate of 100 ° C / hour to remove the binder, and subsequently heated to 1300 ° C in vacuum.
After carrying out the sintering for holding for a time, a homogenizing heat treatment of holding for 1 hour at 800 ° C. and cooling were performed to obtain a sintered body. At this time, as a sample for measuring magnetic characteristics, 30φ × 24φ × 5
The ring of t was press-molded and simultaneously subjected to degreasing, sintering, and uniform heat treatment at the same time as the above sample.

Next, the direct current magnetic characteristic is measured by AUTOMAT.
IC D. C. B-H CURVES TRACER
And the maximum magnetic permeability μ _max , the coercive force Hc, and the magnetic flux density B _{20 at 20} Oe as shown in Tables 6 and 8.
Got the value of. Moreover, the iron loss, which is an AC magnetic characteristic, was obtained by an iron loss evaluation device. Fluidity of granulated powder, relative density of sintered body,
Tables 6 and 8 show the amount of residual oxygen, the amount of residual carbon, and the magnetic properties.
Here, as the relative density, the density of an ingot of Fe-3% Si was used as the true density. The fluidity was measured by the time required for 100 g of the raw material powder to spontaneously drop and pass through a funnel tube having an inner diameter of 8 mm. Further, the particle size of the granulated powder is a value obtained by sieving through a mesh and weight-averaged. The fluidity of granulated powder is
The target is 20 seconds or less, and the iron loss is a magnetic flux density of 5k.
The target value was 1000 (J / m ³ ) or less at G and a frequency of 1 MHz. In addition, the obtained sintered body, cracks, cracks,
No deformation was observed. In addition, when the binder addition amount of polyvinyl alcohol was 0.05 wt%, No. Since the granulated powder of No. 15 had poor fluidity, it was difficult to form a product having a complicated shape, and thus was excluded from the application.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Table 6]

[0052]

[Table 7]

[0053]

[Table 8]

[0054]

As is clear from the examples, the Fe--Si
Wet-milling the base alloy powder in water or a solvent, then adding a binder consisting of polyvinyl alcohol, methyl cellulose, polyacrylamide alone or in combination of two and water to fine powder dried in vacuum and kneading to form a slurry After that, the slurry was cooled to a temperature of 0 ° C. to 10 ° C. and stirred, and then formed into a granulated powder having an average particle size of 20 to 400 μm by a spray dryer device, press-molded using the granulated powder, and hydrogen. The powder metallurgy method of degreasing in flowing air at a specific temperature condition and then sintering in vacuum or an inert gas may yield a sintered body with high sintering density and excellent magnetic properties. all right. Since the granulated powder according to the present invention has very good fluidity, it is possible to produce a compact having a complicated shape by multi-stage press molding, so that the future use of the Fe-Si soft magnetic sintered alloy will be expanded. It is thought to be done.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area H01F 1/22

Claims (7)

[Claims] 1. Fe-Si based alloy fine powder, polyvinyl alcohol, methyl cellulose, polyacrylamide alone or in combination of two kinds 0.1-2.0 wt%
And a binder composed of water are added, kneaded and stirred to form a slurry having a water content of 20 to 50 wt%, and the slurry has an average particle size of 20 to 400 μm by a spray dryer device.
Characterized by obtaining a sintered alloy by the powder metallurgy method of degreasing in a stream of hydrogen after molding and further sintering in a vacuum or in an inert gas. And a method for producing a Fe-Si based soft magnetic sintered alloy. 2. The Fe—Si alloy fine powder is an ingot, powdered powder, or atomized powder that is heat-treated at a temperature of 300 ° C. to 800 ° C. in a vacuum or in an inert gas. The method for producing the Fe-Si based soft magnetic sintered alloy according to 1. 3. The Fe—S alloy according to claim 1, wherein the Fe—Si alloy fine powder is a mixed powder of Fe powder containing Fe ₃ Si compound as a main component and Fe powder.
A method for producing an i-based soft magnetic sintered alloy. 4. Fe-containing Fe ₃ Si compound as a main component
The amount of Si of Si type alloy powder is 6.5 wt% -23 wt%, The manufacturing method of the Fe-Si type soft magnetic sintered alloy of Claim 3 characterized by the above-mentioned. 5. The slurry after the binder is added is 0 ° C.
The method for producing a Fe-Si based soft magnetic sintered alloy according to claim 1, wherein stirring is performed in a state of being cooled to 10 ° C. 6. A molded body in a flowing hydrogen atmosphere at 300 ° C. to 800 ° C.
Degreasing is performed at a temperature of [deg.] C. The method for producing a Fe-Si based soft magnetic sintered alloy according to claim 1. 7. The Fe- according to claim 1, wherein the sintered body is subjected to a uniform heat treatment at 300 ° C to 1000 ° C.
A method for manufacturing a Si-based soft magnetic sintered alloy.