JP2008214664A - Method for manufacturing sintered body, and sintered body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a sintered body by which an Fe-Al-Si alloy sintered body usable, owing to its excellent magnetic properties and high toughness, as e.g. machine parts to which external stress is applied can be easily manufactured and also to provide a sintered body manufactured by such a manufacturing method. <P>SOLUTION: The manufacturing method comprises: a granulation step where a plurality of core particles 1 composed of Fe-Al-Si alloy, a plurality of Ni-based metal particles 2 composed of Ni-based metallic material and a binder are mixed and granulated to prepare a granulated powder; a compaction step where the granulated powder is compacted into a prescribed shape to prepared a green body; a debinding step where debinding treatment is applied to the green body to prepare a brown body; and a firing step where the brown body is fired to obtain a sintered body 30. By this method, the sintered body 30 in which the Ni-based metal particles 2 are distributed among the plurality of core particles 1 can be obtained. In the sintered body 30, the brittle core particles 1 are reinforced by the high-toughness Ni-based metal particles 2 to improve overall toughness. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a sintered body and a sintered body.

An Fe—Al—Si based alloy material is known as a soft magnetic material exhibiting a high magnetic permeability and a high saturation magnetic flux density. Such an Fe—Al—Si based alloy material is excellent in magnetic properties, and thus is used as a material constituting magnetic cores of various coils.
In addition, since Fe—Al—Si based alloy material is excellent in wear resistance, it is also used as a constituent material of a magnetic head that continuously rubs against a magnetic tape.

On the other hand, although the Fe—Al—Si based alloy material has high hardness, it has a drawback of being very brittle.
For example, in Patent Document 1, one or two of polyvinyl alcohol, methylcellulose, and polyacrylamide is added to the Fe—Al—Si alloy powder as a binder at a ratio of 0.1 to 2.0 wt%. Further, water is further added and kneaded, and a granulated powder having an average particle size of 20 to 400 μm is produced from the kneaded product by a spray dryer, and a sintered alloy is obtained using the granulated powder. A method for producing an Fe—Al—Si based sintered alloy is disclosed.

  According to the method described in Patent Document 1, although a sintered body having a high density can be obtained, the particles of the Fe—Al—Si based alloy powder are sintered to form a sintered body. Brittleness is maintained as it is. For this reason, the sintered body manufactured by such a conventional method is easily broken by applying external stress, and is difficult to use as a machine part.

JP-A-8-67941

  An object of the present invention is a sintered body capable of easily producing a sintered body of an Fe-Al-Si alloy that can be used, for example, as a mechanical part to which external stress is applied because of excellent magnetic properties and high toughness. It is providing the manufacturing method and the sintered compact manufactured by this manufacturing method.

The above object is achieved by the present invention described below.
The method for producing a sintered body of the present invention comprises mixing a plurality of core particles composed of an Fe-Al-Si alloy, a plurality of Ni-based metal particles composed of a Ni-based metal material, and a binder. A first step of granulating and obtaining granulated particles;
A second step of forming the granulated particles into a predetermined shape to obtain a molded body;
And a third step of firing the molded body to obtain a sintered body.
Thereby, since it is excellent in a magnetic characteristic and toughness is high, the sintered compact of the Fe-Al-Si type alloy which can be used as a mechanical component to which external stress is added, for example can be manufactured easily.

In the method for producing a sintered body of the present invention, the granulated particles are preferably such that the Ni-based metal particles and the binder are positioned so as to cover the core particles.
Thereby, each core particle and each Ni base metal particle are disperse | distributed uniformly, and the compact | molding | casting which reinforced each brittle core particle with each tough Ni base metal particle efficiently is obtained.
In the method for producing a sintered body according to the present invention, the Fe-Al-Si-based alloy contains Fe as a main component, the Al content is 3 to 8 wt%, and the Si content is 5 to 11 wt%. It is preferable.
Thereby, the sintered compact which shows a high magnetic permeability and a high saturation magnetic flux density can be obtained.

In the method for producing a sintered body according to the present invention, the Ni-based metal material is preferably Ni simple substance.
Since Ni simple substance has especially high toughness, the toughness of a sintered compact can be improved especially.
In the manufacturing method of the sintered compact of this invention, it is preferable that the average particle diameter of the said granulated particle is 40-180 micrometers.
Thereby, when the granulated particles are filled into the mold and the molded body is formed, the granulated particles are excellent in fluidity and fillability into the mold.

In the method for producing a sintered body according to the present invention, the average particle diameter of the Ni-based metal particles is preferably smaller than the average particle diameter of the core particles.
As a result, the core particles and the Ni-based metal particles are easily mixed, and the Ni-based metal particles are easily distributed so as to cover the core particles. For this reason, granulated particles in which Ni-based metal particles are distributed on the surface of the core particles or in the gaps between the plurality of core particles can be easily obtained.

In the manufacturing method of the sintered compact of this invention, it is preferable that the average particle diameter of the said Ni group metal particle is 5 to 50% of the average particle diameter of the said core particle.
As a result, the core particles and the Ni-based metal particles are more easily mixed.
In the method for producing a sintered body of the present invention, the average particle diameter of the core particles is preferably 2 to 20 μm.
Thereby, the size of the crystal grains of the Fe—Al—Si alloy formed in the sintered body becomes relatively small. For this reason, the fracture probability within the crystal structure in the sintered body is lowered, and mechanical properties such as the bending strength and toughness of the sintered body can be enhanced.

In the manufacturing method of the sintered compact of this invention, it is preferable that the average particle diameter of the said Ni group metal particle is 0.5-10 micrometers.
This makes it easy for the Ni-based metal particles to be distributed so as to cover the surface of the core particles in the granulated particles, or to enter the gaps between the plurality of core particles. Therefore, by producing a sintered body using the granulated particles in such a state, a sintered body having high toughness can be obtained even if the core particles are very brittle particles.
In the method for producing a sintered body of the present invention, the mixing ratio of the core particles and the Ni-based metal particles in the granulated particles is preferably 99.5: 0.5 to 90:10 by weight ratio. .
Thereby, the toughness of a sintered compact can be improved, preventing the magnetic characteristic of a sintered compact falling remarkably.

In the method for producing a sintered body of the present invention, the first step is a step of mixing the plurality of core particles and the plurality of Ni-based metal particles to obtain a mixture,
It is preferable to have a step of granulating the mixture and obtaining the granulated particles while supplying a binder solution obtained by dissolving the binder in a solvent.
Thereby, for example, even if it is difficult to uniformly disperse the Ni-based metal particles in the binder solution because the particle diameter of the Ni-based metal particles is relatively large, the core particles and the Ni-based metal particles can be uniformly dispersed.

In the method for producing a sintered body according to the present invention, the first step is a step of dispersing the plurality of Ni-based metal particles in a binder solution obtained by dissolving the binder in a solvent to obtain a dispersion,
It is preferable to have a step of granulating the plurality of core particles and obtaining the granulated particles while supplying the dispersion.
As a result, the Ni-based metal particles can be efficiently diffused on the binder solution. For this reason, the core particles and the Ni-based metal particles can be more uniformly dispersed.

In the method for producing a sintered body according to the present invention, in the first step, it is preferable to perform the granulation by a rolling granulation method, a rolling fluid granulation method, or a spray drying method.
Thereby, a granulated powder having a relatively narrow particle size distribution can be efficiently produced.
In the method for producing a sintered body according to the present invention, in the third step, the firing temperature is preferably 1100 to 1270 ° C., and the firing time is preferably 0.5 to 8 hours.
Thereby, a molded object can be sintered reliably, preventing melting of core particles.

The sintered body of the present invention is manufactured by the method for manufacturing a sintered body of the present invention.
Thereby, while being excellent in a magnetic characteristic, the sintered compact of the Fe-Al-Si type alloy with high toughness is obtained.
The sintered body of the present invention is characterized in that a Ni-based metal material is distributed between a plurality of core particles composed of an Fe—Al—Si alloy.
Thereby, while being excellent in a magnetic characteristic, the sintered compact of the Fe-Al-Si type alloy with high toughness is obtained.

In the sintered body of the present invention, the bending strength is preferably 680 N / mm ² or more.
As a result, the obtained sintered body of Fe—Al—Si alloy has particularly high mechanical properties while maintaining its excellent magnetic properties, and thus can be suitably applied as, for example, mechanical parts. It will be a thing.
In the sintered body of the present invention, the porosity is preferably 1 to 10%.
As a result, the obtained Fe—Al—Si-based alloy sintered body has particularly high mechanical properties and magnetic properties.

Hereinafter, the manufacturing method and sintered body of the sintered body of the present invention will be described based on preferred embodiments shown in the accompanying drawings.
<First Embodiment>
First, the manufacturing method of the sintered compact of this invention and 1st Embodiment of a sintered compact are demonstrated.
FIG. 1 is a process diagram showing a first embodiment of a method for producing a sintered body according to the present invention, and FIG. 2 is a schematic cross-sectional view of a granulated powder used in the method for producing a sintered body according to the first embodiment. FIG. 3 is a diagram schematically showing a longitudinal section of a molded body obtained by the method for manufacturing a sintered body according to the first embodiment, and FIG. 4 is a longitudinal section of the sintered body of the present invention. It is a figure shown typically.

  The method for producing a sintered body of the present invention uses a plurality of core particles composed of an Fe-Si-Al-based alloy and a plurality of Ni-based metal particles composed of a Ni-based metal material, which are used as raw materials. , A method of manufacturing a sintered body composed of an Fe—Si—Al based alloy. The sintered body produced in this way is excellent in magnetic properties and has high toughness, so that it can be suitably used, for example, as a mechanical component to which external stress is applied.

Hereinafter, the aforementioned core particles and the aforementioned Ni-based metal particles used in the present invention will be described.
In the present embodiment, first, Fe-Si-Al-based alloy powder including a plurality of particles composed of Fe-Si-Al-based alloy serving as core particles, and Ni-based metal material serving as Ni-based metal particles are used. A Ni-based metal powder containing a plurality of particles is mixed to obtain a mixture.

Hereinafter, in the present embodiment, the plurality of particles composed of the Fe—Si—Al alloy, that is, the plurality of core particles are also referred to as “Fe—Si—Al alloy powder”. A plurality of particles made of a Ni-based metal material, that is, a plurality of Ni-based metal particles are also referred to as “Ni-based metal powder”. Further, the plurality of granulated particles are also referred to as “granulated powder”.
Here, the core particle is made of an Fe—Al—Si alloy as described above.
On the other hand, the Ni-based metal particles are made of a Ni-based metal material as described above. This Ni-based metal material is a metal material containing Ni as a main component.

By the way, although the Fe—Al—Si-based alloy is excellent in magnetic properties as described above, it has a drawback of being very brittle. For this reason, conventionally, the Fe—Al—Si based alloy cannot be forged, and even if the Fe—Al—Si based alloy is cast to produce a structural body, the mechanical structure of the obtained structural body There was a problem that the characteristics were low.
On the other hand, by powder metallurgy technology, an Fe-Al-Si alloy powder and a binder are mixed and granulated to obtain a granulated powder, and a sintered body has also been obtained using this granulated powder. . However, since the Fe—Al—Si based alloy powder constitutes the sintered body in a state where the brittleness of each particle itself is maintained, there is a problem that the mechanical properties of the sintered body are low.

Therefore, in the present invention, the Ni-based metal powder and the binder are mixed with the Fe-Al-Si-based alloy powder, and these are granulated to obtain a granulated powder. A sintered body was obtained by firing.
That is, as shown in FIG. 1, the manufacturing method of the sintered body according to the present embodiment includes a plurality of core particles (Fe—Al—Si alloy powder) composed of Fe—Al—Si alloy, Ni A plurality of Ni-base metal particles (Ni-base metal powder) composed of a base metal material and a binder are mixed and granulated to obtain a granulated powder (first step) [A]; The obtained granulated powder is molded into a predetermined shape, and a molding step (second step) [B] for obtaining a molded body, and a degreasing step for obtaining a degreased body by degreasing the obtained molded body [C] And a firing step (third step) [D] for firing the obtained degreased body to obtain a sintered body.
By manufacturing a sintered body through these steps, a sintered body having excellent magnetic properties and high toughness can be obtained.

Hereinafter, the respective steps will be sequentially described.
[A] Granulation step (first step)
In this embodiment, in this granulation step, first, a step of obtaining a mixture by mixing Fe-Al-Si alloy powder (a plurality of core particles) and Ni metal powder (a plurality of Ni-based metal particles); The step of preparing a binder solution by dissolving the binder in a solvent, and then granulating the obtained mixture while supplying the prepared binder solution, Granulated particles).

First, an Fe—Al—Si based alloy powder 1 and a Ni-based metal powder 2 shown in FIG. 2 are prepared.
Among these, the Fe—Al—Si based alloy constituting the Fe—Al—Si based alloy powder 1 may be an alloy in which each element of Fe, Al, and Si is contained in any composition ratio. It is preferable that it is an alloy.

Specifically, the Fe—Al—Si based alloy is an alloy containing Fe as a main component and containing Al at a content of about 3 to 8 wt% and Si at a content of about 5 to 11 wt%. It is preferable to be an alloy containing Fe as a main component, Al in a content of about 4 to 7 wt%, and Si in a content of 8 to 11 wt%.
Such an Fe—Al—Si-based alloy material is a soft magnetic material excellent in magnetic properties exhibiting high magnetic permeability and high saturation magnetic flux density. For this reason, by using the core particles 1 made of the Fe—Al—Si based alloy material having the composition as described above as a raw material, the sintered body has excellent magnetic properties.

Further, the Fe—Al—Si based alloy may further contain other components other than Fe, Al, and Si.
Examples of other components include Ni and Ti. For example, by adding about 0.5 to 5 wt% of Ni, the saturation magnetic flux density can be further increased while maintaining the soft magnetic properties of the Fe—Al—Si based alloy. Moreover, magnetic characteristics can be improved also by adding Ti.

  Examples of other components further include elements such as O (oxygen), C (carbon), P (phosphorus), and S (sulfur) that are inevitably mixed during the production process. However, the total content of other components is preferably 1 wt% or less. When the content of other components is within the above range, it is possible to prevent the magnetic properties of the Fe—Al—Si based alloy from unintentionally changing greatly.

  The average particle diameter of such Fe—Al—Si based alloy powder 1 (average particle diameter of core particle 1) is not particularly limited, but is preferably about 2 to 20 μm, and is preferably about 3 to 10 μm. More preferred. By making the average particle diameter of the Fe—Al—Si alloy powder 1 within the above range, the size of the crystal grains of the Fe—Al—Si alloy formed in the finally obtained sintered body is compared. Small. For this reason, the fracture probability within the crystal structure in the sintered body is lowered, and mechanical properties such as the bending strength and toughness of the sintered body can be enhanced.

  Moreover, the shape of the Fe—Al—Si alloy particles (core particles) 1 is not particularly limited, but is preferably a shape close to a sphere. Thereby, in the shaping | molding process mentioned later, the filling rate to the shaping | molding die of the Fe-Al-Si type alloy particle 1 becomes high, and the molded object and sintered body of a higher density are obtained. Furthermore, when the shape of the core particle 1 is close to a sphere, there is also an advantage that it is more difficult to break due to the shape action.

  The Fe—Al—Si based alloy powder 1 may be manufactured by any method. For example, an atomizing method (for example, a water atomizing method, a gas atomizing method, a high-speed rotating water atomizing method, etc.), reduction It can be produced by a powder production method such as a method, a carbonyl method, or a pulverization method. Among these, the Fe—Al—Si based alloy powder 1 is preferably manufactured by an atomizing method. Thereby, the Fe-Al-Si type alloy powder 1 closer to a true sphere can be efficiently manufactured.

On the other hand, the Ni-based metal material constituting the Ni-based metal powder 2 is a metal material containing Ni as a main component as described above.
The Ni content in the Ni-based metal material is preferably about 50 to 100 wt%, and more preferably about 80 to 100 wt%. Thereby, the toughness of the Ni-based metal particles 2 can be further increased. As a result, the finally obtained sintered body of Fe-Al-Si alloy also exhibits high toughness.

The Ni-based metal material is more preferably Ni simple substance. Since Ni alone has particularly high toughness, the toughness of the sintered body can be particularly enhanced.
The average particle diameter of the Ni-based metal powder 2 (average particle diameter of the Ni-based metal particles 2) is not particularly limited, but is preferably about 0.5 to 10 μm, and about 0.5 to 5 μm. Is more preferable. By setting the average particle diameter of the Ni-based metal powder 2 within the above range, the Ni-based metal particles 2 are distributed so as to cover the surface of the core particle 1 in the granulated powder described later, or a plurality of core particles It becomes easy to get into the gap between the ones. Therefore, by producing a sintered body using the granulated powder in such a state, even if the Fe-Al-Si alloy particles 1 are very brittle particles, a sintered body having high toughness is obtained. be able to. This action / effect will be described in detail later.

Further, the shape of the Ni-based metal particle 2 is not particularly limited, but it is preferably a shape close to a sphere like the core particle 1. Thereby, the fluidity of the Ni-based metal particles 2 becomes higher, and it becomes easier to enter the gaps between the plurality of core particles 1. For this reason, in the molding process to be described later, a molded body having a higher filling rate, that is, a higher density can be obtained.
The Ni-based metal powder 2 may be manufactured by any method, and can be manufactured by the same method as the method for manufacturing the Fe-Al-Si alloy powder 1 described above.

Next, the prepared Fe—Al—Si alloy powder 1 and the Ni-based metal powder 2 are mixed to obtain a mixture.
Although this mixing is not specifically limited, it can be performed using various mixers, such as a V-type mixer, a Dalton mixer, and a rolling mixer.
In the present embodiment, since the Fe—Al—Si based alloy powder 1 and the Ni-based metal powder 2 are mixed in advance as described above, for example, the particle diameter of the Ni-based metal powder 2 is relatively large. Even when it is difficult to uniformly disperse in the binder solution, the Fe—Al—Si based alloy powder 1 and the Ni-based metal powder 2 can be uniformly dispersed.

Next, the binder 3 shown in FIG. 2 and a solvent for dissolving the binder 3 are prepared. Then, the binder 3 is dissolved in a solvent to prepare a binder solution.
Examples of the binder 3 include polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), zinc stearate, lithium stearate, calcium stearate, ethylene bisstearamide, ethylene vinyl copolymer, paraffin, wax, sodium alginate, agar , Gum arabic, resin, sucrose, etc., and one or more of these can be used in combination.
Among these, polyvinyl alcohol or polyvinyl pyrrolidone is preferable. Such a binder has a strong bonding force despite being inexpensive and easily available. Moreover, since it decomposes easily by heating, there is an advantage that unintended components hardly remain, that is, the binder removal characteristic is high.

  The solvent is not particularly limited as long as it can dissolve the binder 3. For example, inorganic solvents such as water, carbon disulfide, and carbon tetrachloride, ketone solvents, alcohol solvents, ether solvents, Cellosolve solvent, aliphatic hydrocarbon solvent, aromatic hydrocarbon solvent, aromatic heterocyclic compound solvent, amide solvent, halogen compound solvent, ester solvent, amine solvent, nitrile solvent, nitro solvent Organic solvents such as aldehyde solvents and the like can be mentioned, and one or a mixture of two or more selected from these can be used.

  The weight of the binder 3 dissolved in the solvent is preferably about 0.5 to 30 g per kg of the total weight of the raw material powder (Fe—Al—Si alloy powder 1 and Ni-based metal powder 2). More preferably, it is about 20 g. By setting the weight of the binder 3 to be within the above range, the surface of the core particle 1 is coated with a sufficient amount of binder, and a large amount of binder that does not contribute to the coating can be prevented. it can. As a result, a granulated powder capable of producing a molded body excellent in shape retention and molding density is obtained in the steps described later.

  Further, the weight of the solvent used for dissolving the binder 3 is preferably about 5 to 100 g, more preferably about 7 to 70 g, per 1 g of the binder. By setting the weight of the solvent within the above range, the binder 3 is surely dissolved, and the amount of the solvent is excessively increased so that the viscosity of the binder solution is remarkably lowered. It is possible to reliably prevent the formability from deteriorating.

Next, a mixture of Fe—Al—Si based alloy powder (core particles) 1 and Ni-based metal powder (Ni-based metal particles) 2 is put into a granulator, and the prepared binder solution is supplied to this mixture. Meanwhile, the mixture is granulated.
This granulation is, for example, various granulation methods such as tumbling fluid granulation method, tumbling granulation method, spray drying method (spray dryer), stirring and mixing granulation, extrusion granulation, crush granulation, compression granulation and the like. However, it is particularly preferable to carry out by the rolling fluid granulation method, the rolling granulation method or the spray drying method. According to these methods, a granulated powder having a relatively narrow particle size distribution can be efficiently produced.

By such granulation, a granulated powder 10 as shown in FIG. 2 is obtained. In the granulated powder 10, a plurality of core particles 1 and a plurality of Ni-based metal particles 2 are bonded to each other by a binding action of a binder 3 and a solvent to form a granulated particle.
Moreover, it is preferable that the obtained granulated powder 10 contains granulated particles in which each Ni-based metal particle 2 and the binder 3 are distributed so as to cover each core particle 1 (see FIG. 2). When such a granulated powder 10 is filled in a mold and molded, the core particles 1 and the Ni-based metal particles 2 can be uniformly dispersed. For this reason, by using the granulated powder 10, it is possible to produce a molded body obtained by efficiently reinforcing the brittle core particles 1 with the Ni-based metal particles 2 having high toughness.

  Here, in the granulated powder 10 shown in FIG. 2, the average particle diameter of the Ni-based metal particles 2 is smaller than the average particle diameter of the core particles 1. Accordingly, the core particles 1 and the Ni-based metal particles 2 are easily mixed, and the Ni-based metal particles 2 are easily distributed so as to cover the core particles 1. For this reason, as shown in FIG. 2, the granulated powder 10 in which the Ni-based metal particles 2 are distributed on the surface of the core particles 1 and the gaps between the plurality of core particles 1 is easily obtained. In the granulated powder 10, the core particles 1 and the Ni-based metal particles 2 are particularly uniformly dispersed.

In this case, the average particle diameter of the Ni-based metal particles 2 is preferably about 5 to 50% of the average particle diameter of the core particles 1, and more preferably about 5 to 30%. By setting the average particle diameter of the Ni-based metal particles 2 in such a range, the core particles 1 and the Ni-based metal particles 2 are more easily mixed. And the granulated powder 10 in which the core particle 1 and the Ni-based metal particle 2 are more uniformly dispersed is obtained.
Such a granulated powder 10 is molded in the steps described below and further fired to obtain a sintered body in which the Ni-based metal particles 2 are filled in the gaps between the plurality of core particles 1. .

In such a sintered body, the brittle core particles 1 are reinforced by the Ni-based metal particles 2 having high toughness. As a result, even if a large load is applied to the sintered body, the atomic arrangement of the Ni-based metal particles 2 having high toughness changes, so that the energy of the applied load is absorbed and a load is applied to the brittle core particles 1. Can be suppressed. As a result, the mechanical properties of the Ni-based metal particles become dominant in the sintered body, and a sintered body with high toughness can be obtained.
In particular, according to the rolling fluid granulation method or the rolling granulation method, since the granulation is performed while rolling the above-mentioned mixture, the Ni-based metal particles 2 are formed on the surface of the core particle 1 when rolling. Is easy to adhere. For this reason, according to these granulation methods, the granulated powder 10 as shown in FIG. 2 can be manufactured efficiently.

  At this time, the supply rate of the binder solution is not particularly limited, but is preferably about 1 to 40 g / min per 1 kg of the total weight of the raw material powders (Fe-Al-Si alloy powder 1 and Ni-based metal powder 2). 2 to 32 g / min is more preferable, and 4 to 24 g / min is more preferable. By setting the supply rate of the binder solution within the above range, the binder solution can be evenly distributed throughout the raw material powder, and the particle size distribution of the obtained granulated powder can be made narrower.

On the other hand, when the supply rate of the binder solution is lower than the lower limit value, there is a possibility that granulation unevenness occurs. On the other hand, when the supply rate of the binder solution exceeds the upper limit, granulation may proceed excessively with a part of the raw material powder. For this reason, there exists a possibility that the particle size distribution of the granulated powder obtained may spread.
The granulation time is not particularly limited, but is preferably about 30 to 120 minutes, more preferably about 40 to 100 minutes, and further preferably about 50 to 90 minutes.

In the present embodiment, the granulated powder 10 in which the Ni-based metal particles 2 are distributed on the surfaces of the core particles 1 and the gaps between the plurality of core particles 1 has been described. Is not limited to the state shown in FIG. That is, a plurality of core particles 1 may be aggregated, and the Ni-based metal particles 2 may be distributed around the aggregate.
The granulated powder 10 thus obtained preferably has an average particle size of about 40 to 180 μm, more preferably about 45 to 140 μm, and further preferably about 50 to 100 μm. . By setting the average particle size of the granulated powder 10 within the above range, when the granulated powder 10 is filled into a mold and a molded body is formed, the granulated powder 10 is improved in fluidity and mold. Excellent filling properties.
When the average particle size is below the lower limit, the fluidity of the granulated powder 10 is not stable, and the dimensional variation of the sintered body (molded body) may increase. On the other hand, when the average particle size exceeds the upper limit, when forming a particularly small compact, uneven filling of the granulated powder 10 is likely to occur, and the dimensional variation of the sintered compact (molded product) may increase. There is.

  Further, the mixing ratio of the core particles 1 and the Ni-based metal particles 2 in the granulated powder 10 is preferably about 99.5: 0.5 to 90:10 by weight, and is 99: 1 to 95: 5. More preferred is the degree. If the mixing ratio of the core particles 1 and the Ni-based metal particles 2 is set within the above range, the toughness of the sintered body can be increased while preventing the magnetic properties of the sintered body from being significantly lowered.

If the ratio of the Ni-based metal particles 2 to the core particles 1 is below the lower limit, the Ni-based metal particles 2 cannot be sufficiently distributed in the gaps between the plurality of core particles 1 or the surfaces of the core particles 1. The core particles 1 may not be sufficiently reinforced. On the other hand, if the ratio of the Ni-based metal particles 2 to the core particles 1 exceeds the upper limit, the content of the core particles 1 that are excellent in soft magnetism may be reduced, and the magnetic properties of the sintered body may be reduced.
The granulated powder 10 may contain various additives such as a plasticizer, a dispersant, a surfactant, and a lubricant as other components. Such various additives may be contained, for example, in the raw material powder or the binder solution.

[B] Molding step (second step)
Next, the obtained granulated powder 10 is filled in a mold and molded to obtain a molded body.
At this time, as a molding method, for example, various molding methods such as a compacting (compression molding) method, a metal powder injection molding (MIM: Metal Injection Molding) method, and an extrusion molding method can be used.

Among these, the molding conditions in the compacting method vary depending on various conditions such as the composition and particle size of the raw material powder used, the composition of the binder, and the blending amount thereof, but the molding pressure is 20 to 1000 MPa (2.0. About 10 to 10 t / cm ² ).

Moreover, although the molding conditions in the metal powder injection molding method vary depending on various conditions, the material temperature is about 80 to 210 ° C. and the injection pressure is about 50 to 500 MPa (0.5 to 5 t / cm ² ). preferable.
Moreover, although the molding conditions in the case of an extrusion molding method differ with various conditions, it is preferable that material temperature is about 80-210 degreeC and extrusion pressure is about 50-500 MPa (0.5-5 t / cm < ² >).
The molded body 20 thus obtained is in a state in which a plurality of Ni-based metal particles 2 and a binder 3 are distributed in the gaps between the plurality of core particles 1 as shown in FIG.
In addition, the shape dimension of the molded body 20 to be produced is determined in consideration of the shrinkage of the molded body 20 in the subsequent degreasing and firing steps.

[C] Degreasing process Next, the obtained molded body 20 is subjected to a degreasing process (a debinding process) to obtain a degreased body.
The degreasing treatment is not particularly limited, but in a non-oxidizing atmosphere, for example, in a vacuum or under reduced pressure (for example, 1 × 10 ⁻¹ to 1 × 10 ⁻⁶ Torr (13.3 to 1.33 × 10 ⁻⁴ Pa) ), Or by performing a heat treatment in a gas such as nitrogen gas, argon gas, hydrogen gas, or ammonia decomposition gas.
In this case, the heat treatment conditions vary slightly depending on the decomposition start temperature of the binder, etc., but are preferably about 100 to 750 ° C. for about 0.5 to 20 hours, more preferably about 150 to 700 ° C. for 1 to 10 hours. It is assumed that

Further, degreasing by such heat treatment may be performed in a plurality of steps (stages) for various purposes (for example, for shortening the degreasing time). In this case, for example, a method in which the first half is degreased at a low temperature and the second half at a high temperature, a method in which low temperature and high temperature are repeated, and the like can be mentioned.
The binder may not be completely removed by the degreasing process. For example, a part of the binder may remain when the degreasing process is completed.

[D] Firing step (third step)
Next, the obtained degreased body is fired. By this firing, the raw material powder constituting the granulated powder is sintered and becomes a sintered body.
In the sintered body 30 thus obtained, as shown in FIG. 4, the Ni-based metal material is distributed without gaps so as to fill the gaps between the plurality of core particles 1. For this reason, the brittle core particles 1 are reinforced by the Ni-based metal particles 2 having high toughness, and a sintered body 30 having high toughness is obtained.

Moreover, since Ni in the Ni-based metal particles 2 has a large diffusion coefficient into the alloy containing Fe, it easily diffuses between the particles of the core particle 1 and between grain boundaries. For this reason, the core particles 1 and the Ni-based metal particles 2 are firmly bonded based on this diffusion. As a result, grain boundary misalignment or the like hardly occurs between the core particle 1 and the Ni-based metal particle 2, and the mechanical characteristics of the sintered body 30 are further improved.
Furthermore, since Ni is not a main element of the Fe—Al—Si alloy, even if Ni diffuses into the Fe—Al—Si alloy, the composition of the Fe—Al—Si alloy changes significantly. There is nothing. For this reason, even if the above-mentioned Ni diffusion occurs, the excellent magnetic properties of the Fe—Al—Si alloy can be maintained.

  The firing temperature is slightly different depending on the composition and particle size of the raw material powder, but is preferably about 1100 to 1270 ° C, more preferably about 1150 to 1270 ° C, and about 1200 to 1260 ° C. Is more preferable. Moreover, although baking time changes a little with baking temperature, it is preferable that it is about 0.5 to 8 hours, and it is more preferable that it is about 1 to 5 hours. By setting the firing temperature and firing time within the above ranges, the degreased body (molded body) can be reliably sintered while preventing the core particles 1 from melting.

  In addition, when any one of a calcination temperature and a calcination time is less than the said lower limit, there exists a possibility that a degreased body cannot fully be sintered. On the other hand, when either one of the calcination temperature and the calcination time exceeds the upper limit value, almost the entire core particle 1 is melted, and the shape of the degreased body is deformed. There is a possibility that the elements segregate and the magnetic properties are deteriorated.

The firing atmosphere is preferably a reduced pressure (vacuum) or non-oxidizing atmosphere. Thereby, the characteristic deterioration by the oxidation of the core particle 1 or the Ni group metal particle 2 can be prevented.
Among these, a specific firing atmosphere under reduced pressure (vacuum) is preferably under reduced pressure (vacuum) of 1 Torr (133 Pa) or less, preferably 1 × 10 ⁻⁶ to 1 × 10 ⁻² Torr (1.33). It is more preferable to be under reduced pressure (vacuum) of × 10 ^{−4 to} 1.33 Pa).
Further, specific non-oxidizing atmospheres are preferably an inert gas atmosphere such as nitrogen gas and argon gas, and a reducing gas atmosphere such as hydrogen gas.

Note that the atmosphere in which the firing process is performed may change during the process. For example, a reduced-pressure atmosphere may be set first, and an inert atmosphere may be switched on the way.
Moreover, you may perform a baking process in 2 steps or more. Thereby, the efficiency of sintering of the granulated powder is improved, and sintering can be performed in a shorter sintering time.
Moreover, it is preferable to perform a baking process continuously with the above-mentioned degreasing process. Thereby, a degreasing process can serve as a pre-sintering process, can preheat a degreased body, and can sinter a degreased body more certainly.
As described above, since the magnetic properties are excellent and the toughness is high, a sintered body of an Fe—Al—Si alloy that can be used, for example, as a mechanical component to which external stress is applied can be easily manufactured.

Sintered body of Fe-Al-Si alloy obtained in this manner is preferably its transverse strength is 680N / mm ² or more, more preferably 700 N / mm ² or more. The sintered body of the Fe-Al-Si based alloy having a high bending strength within the above range has particularly high mechanical properties while maintaining its excellent magnetic properties. It can be suitably applied. In addition, according to the method for manufacturing a sintered body of the present invention, a sintered body excellent in both magnetic characteristics and mechanical characteristics can be easily manufactured.

Further, the sintered body of the Fe—Al—Si based alloy preferably has a porosity of about 1 to 10%, more preferably about 1 to 8%. The sintered body of Fe—Al—Si alloy having a porosity as small as the above range has particularly high mechanical properties and magnetic properties. For this reason, such a sintered body can be used particularly suitably as, for example, a machine part.
In addition, the obtained sintered body of the Fe—Al—Si based alloy may be used for any purpose, for example, mechanical parts (electronic machine parts, aircraft parts, automobile parts, etc.), magnetic cores, magnetic It can be used as a head or the like.

Second Embodiment
Next, 2nd Embodiment of the manufacturing method of the sintered compact of this invention is described.
Hereinafter, although the second embodiment will be described, the description will focus on the differences from the first embodiment, and the description of the same matters will be omitted.
The manufacturing method of the sintered body according to the present embodiment is the same as that of the first embodiment except that the mixing method of the Ni-based metal particles in the granulation step is different.

  In the present embodiment, in the granulation step (first step), first, a step of preparing Fe—Al—Si alloy powder (a plurality of core particles) and a binder solution by preparing a binder in a solvent are prepared. In addition, the Ni-based metal powder (a plurality of Ni-based metal particles) is sequentially added to the binder solution, and then the Fe-Al-Si system is supplied while supplying the binder solution to which the Ni-based metal powder is added. A granulated powder (a plurality of granulated particles) is obtained by performing a step of granulating the alloy powder.

According to this method, the Ni-based metal powder can be efficiently diffused on the binder solution. For this reason, the Fe—Al—Si based alloy powder and the Ni-based metal powder can be more uniformly dispersed.
In this embodiment, since the Ni-based metal powder is supplied to the Fe—Al—Si-based alloy powder in a state where the Ni-based metal powder is dispersed in the binder solution in this way, for example, the particle size of the Ni-based metal powder is compared. Therefore, even when aggregation is likely to occur in the Ni-based metal powder, the Fe-Al-Si alloy powder and the Ni-based metal powder can be uniformly dispersed.

As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.
For example, the mixing method of the Fe—Al—Si alloy powder, the Ni-based metal powder, and the binder may be mixed in any order.

1. Production of sintered body (Example 1)
<1> First, an Fe—Al—Si alloy powder having an average particle size of 8.2 μm and an Ni powder having an average particle size of 1 μm manufactured by a water atomization method were prepared as a raw material powder. The Fe—Al—Si based alloy powder used here is Fe-5.5 wt% Al-9.5 wt% Si powder.
Next, the Fe—Al—Si alloy powder and Ni powder were mixed with a V-type mixer to obtain a mixture. The mixing ratio of the Fe—Al—Si alloy powder and the Ni powder was 99: 1 by weight.

<2> On the other hand, polyvinylpyrrolidone (BASF Co., Ltd.) powder was prepared as a binder, and this powder was dissolved in water (solvent) to prepare a binder solution.
The amount of the binder in the binder solution was 12 g per kg of the total weight of the Fe—Al—Si alloy powder and the Ni powder.
The amount of the solvent in the binder solution was 50 g per 1 g of binder.

<3> Next, the mixture of the Fe—Al—Si based alloy powder and the Ni powder was put into a processing container of a rolling fluidized granulator (manufactured by POWREC Co., Ltd., MP-01). Then, the mixture was rolled and granulated while spraying the binder solution from the spray nozzle toward the mixture in the processing container to obtain a granulated powder having an average particle diameter of 75 μm.
The supply rate of the binder solution was 10 g / min per kg of the total weight of the Fe—Al—Si alloy powder and the Ni powder.
The granulation time was 90 minutes.

<4> Next, the obtained granulated powder was used and molded under the following molding conditions to obtain a molded body.
<Molding conditions>
Molding method: compacting Molding pressure: 600 MPa (6 t / cm ² )
<5> Next, this molded body was degreased under the following degreasing conditions to obtain a degreased body.
<Degreasing conditions>
・ Degreasing temperature: 600 ° C
・ Degreasing time: 1 hour ・ Degreasing atmosphere: Hydrogen gas atmosphere

<6> Next, the obtained degreased body was fired under the following firing conditions to obtain a sintered body.
<Baking conditions>
・ Baking temperature: 1250 ° C
・ Baking time: 2 hours ・ Baking atmosphere: Vacuum atmosphere

(Examples 2 to 4)
A sintered body was obtained in the same manner as in Example 1 except that the mixing ratio of the Fe—Al—Si based alloy powder and the Ni powder and the firing temperature were set as shown in Table 1.
(Example 5)
A sintered body was obtained in the same manner as in Example 3 except that Ni powder having an average particle diameter of 3 μm was used.

(Example 6)
A sintered body was obtained in the same manner as in Example 3 except that the granulated powder was obtained as follows.
First, as a raw material powder, an Fe—Al—Si based alloy powder having an average particle size of 8.2 μm manufactured by a water atomization method was prepared. The Fe—Al—Si based alloy powder used here is Fe-5.5 wt% Al-9.5 wt% Si powder.

Next, Ni powder having an average particle size of 1 μm and polyvinyl pyrrolidone (BASF) powder are prepared as a binder, and Ni powder and polyvinyl pyrrolidone powder are dispersed or dissolved in water (solvent) to obtain a binder solution. Was prepared. The amount of Ni powder prepared was such that the mixing ratio of Fe—Al—Si alloy powder and Ni powder was 98: 2 by weight.
The amount of the binder in the binder solution was 12 g per kg of the total weight of the Fe—Al—Si alloy powder and the Ni powder, and the amount of the solvent was 50 g per 1 g of the binder.

Next, the Fe—Al—Si based alloy powder was put into a processing container of a rolling fluidized granulator (manufactured by POWREC Co., Ltd., MP-01). Then, while spraying the binder solution from the spray nozzle toward the Fe—Al—Si alloy powder in the processing vessel, the Fe—Al—Si alloy powder is rolled and granulated to produce an average particle size of 80 μm. A granular powder was obtained.
The supply rate of the binder solution was 20 g / min per kg of the total weight of the Fe—Al—Si alloy powder and the Ni powder.
The granulation time was 50 minutes.
(Example 7)
A sintered body was obtained in the same manner as in Example 3 except that Fe-4.0 wt% Al-6.0 wt% Si-3.2 wt% Ni powder was used as the Fe-Al-Si alloy powder. It was.

(Comparative Example 1)
A sintered body was obtained in the same manner as in Example 2 except that the addition of Ni powder was omitted.
(Comparative Example 2)
A sintered body was obtained in the same manner as in Example 3 except that the addition of Ni powder was omitted.
(Comparative Example 3)
A sintered body was obtained in the same manner as in Example 7 except that the addition of Ni powder was omitted.

2. Evaluation 2.1 Evaluation of Density of Sintered Body The density of each sintered body obtained in each Example and each Comparative Example was measured. The density was measured by a method according to the Archimedes method (specified in JIS Z 2501).

2.2 Evaluation of bending strength of sintered body The bending strength of each sintered body obtained in each example and each comparative example was measured. In addition, the bending strength was measured by a method in accordance with a bending strength test method for metal materials (specified in JIS Z 2248).
2.3 Evaluation of Hardness of Sintered Body Rockwell hardness (HRC) was measured for each of the sintered bodies obtained in each of Examples and Comparative Examples. The Rockwell hardness was measured by a method according to the Rockwell hardness test method (specified in JIS Z 2245).
The evaluation results of 2.1 to 2.3 are shown in Table 1.

As is clear from Table 1, in each Example, a sintered body having a sufficiently high density was obtained.
In each Example, a sintered body having a sufficiently high bending strength and Rockwell hardness was obtained.
On the other hand, all of the sintered bodies obtained in the respective comparative examples had low bending strength. Some of them have particularly low density and Rockwell hardness.
In addition, when the magnetic permeability and the saturation magnetic flux density of the sintered bodies obtained in each of the examples and the comparative examples were measured, all had substantially the same magnetic characteristics.

It is process drawing which shows 1st Embodiment of the manufacturing method of the sintered compact of this invention. It is a figure which shows typically the longitudinal cross-section of the granulated powder used with the manufacturing method of the sintered compact concerning 1st Embodiment. It is a figure which shows typically the longitudinal cross-section of the molded object obtained with the manufacturing method of the sintered compact concerning 1st Embodiment. It is a figure which shows typically the longitudinal cross-section of the sintered compact of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fe-Al-Si type alloy powder (Fe-Al-Si type alloy particle, core particle) 2 ... Ni base metal powder (Ni base metal particle) 3 ... Binder 10 ... Granulated powder 20 ... Molded body 30 ... Sintered body

Claims (18)

First, a plurality of core particles composed of an Fe-Al-Si alloy, a plurality of Ni-based metal particles composed of a Ni-based metal material, and a binder are mixed and granulated to obtain granulated particles. And the process of
A second step of forming the granulated particles into a predetermined shape to obtain a molded body;
And a third step of firing the shaped body to obtain a sintered body.   2. The method for producing a sintered body according to claim 1, wherein the granulated particles are formed by positioning the Ni-based metal particles and the binder so as to cover the core particles.   3. The sintered body according to claim 1, wherein the Fe—Al—Si-based alloy has Fe as a main component, has an Al content of 3 to 8 wt%, and an Si content of 5 to 11 wt%. Manufacturing method.   The method for producing a sintered body according to any one of claims 1 to 3, wherein the Ni-based metal material is Ni simple substance.   The method for producing a sintered body according to any one of claims 1 to 4, wherein an average particle diameter of the granulated particles is 40 to 180 µm.   The method for producing a sintered body according to any one of claims 1 to 5, wherein an average particle diameter of the Ni-based metal particles is smaller than an average particle diameter of the core particles.   The method for producing a sintered body according to claim 6, wherein an average particle diameter of the Ni-based metal particles is 5 to 50% of an average particle diameter of the core particles.   The method for producing a sintered body according to any one of claims 1 to 7, wherein an average particle diameter of the core particles is 2 to 20 µm.   The method for producing a sintered body according to any one of claims 1 to 8, wherein an average particle diameter of the Ni-based metal particles is 0.5 to 10 µm.   The sintered body according to any one of claims 1 to 9, wherein a mixing ratio of the core particles and the Ni-based metal particles in the granulated particles is 99.5: 0.5 to 90:10 by weight. Manufacturing method. The first step is a step of mixing the plurality of core particles and the plurality of Ni-based metal particles to obtain a mixture;
The method for producing a sintered body according to any one of claims 1 to 10, further comprising the step of granulating the mixture and obtaining the granulated particles while supplying a binder solution obtained by dissolving the binder in a solvent. . The first step is a step of dispersing the plurality of Ni-based metal particles in a binder solution obtained by dissolving the binder in a solvent to obtain a dispersion;
The method for producing a sintered body according to any one of claims 1 to 10, further comprising a step of granulating the plurality of core particles and obtaining the granulated particles while supplying the dispersion.   The method for producing a sintered body according to any one of claims 1 to 12, wherein in the first step, the granulation is performed by a rolling granulation method, a rolling fluid granulation method, or a spray drying method.   The method for producing a sintered body according to any one of claims 1 to 13, wherein, in the third step, the firing temperature is 1100 to 1270 ° C, and the firing time is 0.5 to 8 hours.   A sintered body manufactured by the method for manufacturing a sintered body according to any one of claims 1 to 14.   A sintered body characterized in that a Ni-based metal material is distributed between a plurality of core particles composed of an Fe-Al-Si alloy. The sintered body according to claim 15 or 16, which has a bending strength of 680 N / mm ² or more.   The sintered body according to any one of claims 15 to 17, which has a porosity of 1 to 10%.

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