TWI577469B - A method for producing a degreased body and a method for producing the sintered body - Google Patents

Description

Method for producing degreased body and method for producing sintered body

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

A powder metallurgy method for producing a metal product by sintering a molded body containing a metal powder can obtain a near-net-shape sintered body, and thus has been popularized in many industrial fields in recent years. For example, a magnetic core of a complicated shape can be easily obtained by using a magnetic metal powder, and thus can be used for, for example, a component for a magnetic actuator.

In the production of the sintered body, first, the metal powder and the organic binder are mixed and kneaded, and the kneaded product (compound) is molded to obtain a molded body. Then, the obtained molded body is degreased and calcined to obtain a sintered body.

Among them, in the degreasing step, for example, a degreasing device disclosed in Patent Document 1 is used. The degreasing apparatus includes a container called a degreasing furnace, a degreasing gas supply system that supplies degreasing gas into the degreasing furnace, a stirring blade that agitates the degreasing gas in the degreasing furnace, and a degreasing gas discharge system that discharges the degreasing gas. The organic binder is decomposed by heating the molded body accommodated in the degreasing furnace, and the decomposed component is discharged to the outside of the degreasing furnace along with the flow of the degreasing gas, thereby performing degreasing. Then, the degreased body obtained in this manner is calcined in a calcining apparatus, whereby a sintered body is obtained.

The mechanical properties or magnetic properties of the sintered body obtained are affected by the degreasing state. The term "degreasing" refers to the removal of the organic binder from the molded body, and it is important from the viewpoint of the mechanical properties or magnetic properties of the sintered body finally obtained. This removal is performed uniformly. Therefore, it is required to optimize the degreasing step which affects the degreasing state.

However, since a plurality of components are mixed in the organic binder, it is extremely difficult to strictly control the step of performing the degreasing. Therefore, in fact, the degreasing conditions are determined based on past experience or repeated trial and error. Therefore, each time the shape of the formed body changes, it takes a long time and effort to study the degreasing conditions.

Moreover, when the uniformity of degreasing is emphasized, the time required for the degreasing step is significantly prolonged. Therefore, ensuring the uniformity of the degreased body and degreasing in a shorter period of time has become an important issue.

Further, when the particle diameter of the metal powder is small, the decomposition component of the organic binder is not smoothly discharged and the degreasing is poor.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 11-43704

An object of the present invention is to provide a method for producing a degreased body capable of efficiently producing a uniform degreased body, and a method for producing a sintered body which can efficiently produce a sintered body having excellent magnetic properties.

The above object is achieved by the present invention described below.

In the method for producing a degreased body of the present invention, a molded body comprising a magnetic metal powder or an organic binder containing any one of Fe, Ni, and Co as a main component is subjected to a degreasing treatment to obtain a degreased body, and is characterized in that: The organic binder contains a first binder component having a decomposition temperature of TH [° C.] at 1 atm, and a decomposition temperature at 1 atm is a second TL [°C] that does not reach the above TH. In the binder component, the degreasing treatment includes: heating the first degreasing heating process of the molded body at a temperature not reached (TL-30 ° C), and after (TL-30 ° C) or more after the first degreasing heating process Heating at a temperature of TL (50 ° C) to heat the second degreasing temperature rising process of the molded body, and after the second degreasing heating process, heating at a temperature of (TL + 50 ° C) or more and less than (TH + 200 ° C) The third degreasing heating process of the above shaped body.

As a result, the degreasing can be made uniform and the degreasing can be completed in a shorter period of time. Therefore, it is possible to efficiently produce a degreased body capable of producing a sintered body excellent in magnetic properties.

In the method for producing a degreased body of the present invention, TH-TL is preferably 10 ° C or more and 200 ° C or less.

Thereby, a sufficient time difference can be provided between the second adhesive component and the first adhesive component in the time period until the decomposition, and the sintered body capable of producing a homogeneous and high dimensional accuracy can be obtained. body.

In the method for producing a degreased body of the present invention, it is preferred that the organic binder comprises a polymer containing an unsaturated glycidyl group as the first binder component or the second binder component.

Thereby, the glycidol is opened by the ring in the formed body and bonded to the hydroxyl group on the surface of the particle of the magnetic metal powder, so that the particles of the magnetic metal powder exhibit high adhesion to the polymer containing the unsaturated glycidyl group, which becomes a drive. The magnetic metal powder is mixed with the organic binder without deviation. As a result, a degreased body capable of producing a sintered body which is homogeneous and has high dimensional accuracy is obtained.

In the method for producing a degreased body of the present invention, it is preferable that the organic binder comprises polystyrene as the first binder component or the second binder component.

Thereby, moderate mechanical strength is imparted to the organic binder, and the shape retaining property of the molded body is improved, so that a degreased body capable of producing a sintered body having a particularly high dimensional accuracy can be obtained.

In the method for producing a degreased body of the present invention, it is preferable that the organic binder contains a wax as the first binder component or the second binder component.

Thereby, moderate fluidity is imparted to the composition for forming a molded body, and the uniformity and formability of the composition are improved. Therefore, a degreased body capable of producing a sintered body which is particularly homogeneous and has high dimensional accuracy is obtained.

In the method for producing a degreased body of the present invention, it is preferable that the organic binder contains a phthalate ester as a component other than the first binder component and the second binder component.

Thereby, moderate fluidity is imparted to the composition for forming a molded body, and the uniformity and formability of the composition are improved. Therefore, a degreased body capable of producing a sintered body which is particularly homogeneous and has high dimensional accuracy is obtained.

In the method for producing a degreased body of the present invention, it is preferred that the first degreasing and heating process be carried out in an atmosphere containing an inert gas.

Thereby, the unintentional vaporization of the organic binder or the oxidation or modification of the magnetic metal powder is suppressed, and the temperature of the molded body is made uniform, so that a degreased body capable of producing a sintered body having uniform homogeneity and high dimensional accuracy can be obtained.

In the method for producing a degreased body of the present invention, it is preferred that the second degreasing and heating process be carried out in a reduced pressure atmosphere.

Thereby, the decomposition of the second binder component can be promoted, and the heating temperature in the second degreasing and heating process can be reduced. Therefore, the degreasing step can be shortened, and the second binder component is hard to soften, so that the degreased body can be suppressed. Abnormalities such as deformation and cracking.

In the method for producing a degreased body of the present invention, it is preferred that the third degreasing and heating process be carried out in an atmosphere containing an inert gas.

Thereby, oxidation, modification, and the like of the magnetic metal powder can be suppressed, and the decomposition component of the organic binder can be efficiently discharged by performing gas exchange around the molded body.

In the method for producing a degreased body of the present invention, preferably the above magnetic metal powder The average particle diameter is 3 μm or more and 15 μm or less.

Thereby, significant aggregation of the magnetic metal powder or reduction in compressibility at the time of molding can be avoided, and thus a degreased body capable of producing a sintered body which is sufficiently dense and has high dimensional accuracy can be obtained.

The method for producing a sintered body of the present invention includes the first calcination temperature increasing process of heating the degreased body produced by the method for producing a degreased body of the present invention at a temperature of less than 750 ° C. After the first calcination temperature rising process, the second calcination heating process of the degreased body is heated at a temperature of 750 ° C or higher and less than 1050 ° C, and After the second calcination temperature rising process, the third calcination temperature rising process of the degreased body is heated at a temperature of 1050 ° C or more and less than 1600 ° C.

Thereby, a sintered body which is uniform and excellent in magnetic properties can be efficiently produced.

In the method for producing a sintered body according to the present invention, it is preferred that after the third calcination temperature rising process, the degreased body is cooled in a reduced pressure atmosphere, and then the degreased body is cooled in an environment in which an inert gas is continuously supplied.

Thereby, it is possible to suppress the contamination of the workpiece or the temperature from being drastically lowered and to cool in a reduced pressure environment, so that contamination, cracking, deformation, and the like of the sintered body can be suppressed.

1‧‧‧ yoke box

2‧‧‧Tester

3‧‧‧Sintered body

4‧‧‧Package box

5‧‧‧ bags

10‧‧‧ box body

11‧‧‧Edge

12‧‧ ‧ core

13‧‧‧through holes

20‧‧‧meter body

21‧‧‧ convex

22‧‧‧through holes

41‧‧‧Anti-rust paper

101‧‧‧through holes

Fig. 1 is a view showing the steps of a temperature rising process and a temperature lowering process included in the degreasing step and the calcining step.

Fig. 2 is a (a) plan view and a (b) X-X cross-sectional view showing a yoke case as an application example of the sintered body produced by the present invention.

Fig. 3 is a (a) plan view and (b) a Y-Y line sectional view showing an example of a tester which can be applied to the detection of the yoke case shown in Fig. 2.

Fig. 4 is a perspective view showing an example of a package form of a sintered body.

Hereinafter, the degreased body of the present invention is based on the preferred embodiment shown in the accompanying drawings. The manufacturing method and the manufacturing method of the sintered body will be described in detail.

<composition>

First, the molded body used in the method for producing a degreased body of the present invention and the composition used for the production of the molded body will be described.

The composition is composed of a magnetic metal powder and an organic binder and is kneaded.

Among them, the magnetic metal powder has a main component of any of Fe, Ni, and Co.

On the other hand, the organic binder is one in which the particles of the magnetic metal powder adhere to each other, and the first binder component having a decomposition temperature of TH [° C.] at 1 atm and the decomposition temperature at 1 atm is TL [ °C] (where TL does not reach TH) the second binder component. In the case where the organic binder contains three or more kinds of components, among the two components having a high content rate, the higher the decomposition temperature at 1 atm is the first binder component. The lower one is set as the second binder component. Further, the decomposition temperature of the first binder component at 1 atm is set to TH [° C.], and the decomposition temperature of the second binder component at 1 atm is TL [° C.] (wherein TL does not reach TH).

Hereinafter, each component of the composition will be described in detail.

(magnetic metal powder)

As the magnetic metal powder, a powder containing any one of Fe, Ni, and Co as a main component is used as described above. The term "main component" means an element containing the most magnetic metal material constituting the magnetic metal powder and having a content of more than 50% by mass. Therefore, examples of the magnetic metal material include a Fe-based alloy, a Ni-based alloy, and a Co-based alloy. Specific examples include pure iron, ferrite-based iron-based stainless steel, Sindust, nickel-alloy magnetic alloy (Permalloy), nickel-iron-molybdenum superconducting magnetic alloy (Supermalloy), and iron-cobalt magnetic alloy ( Permendur), Fe-Si, Fe-Al, Fe-Cr, Fe-Al-Cr, Fe-Si-Cr, and the like.

Among these, an iron-cobalt magnetic alloy (Fe-Co-V-based alloy) can be preferably used. Fe-Co-V alloys have excellent magnetic properties due to their high saturation magnetic flux density. A magnetic metal sintered body of a sexual property.

Further, such a magnetic metal powder may be produced by any method, and for example, an atomization method (water atomization method, gas atomization method, high-speed rotary water atomization method, etc.), a reduction method, a carbonyl group, or the like may be used. Manufacturers such as methods such as methods and pulverization methods. Among them, the magnetic metal powder is preferably produced by a method of atomization. According to the atomization method, minute magnetic metal powder can be efficiently produced. Further, a magnetic metal powder having a small particle size unevenness and a uniform particle diameter can be obtained. Therefore, by using such a magnetic metal powder, generation of pores in the sintered body can be surely prevented, and the density can be improved. As a result, a magnetic metal sintered body excellent in magnetic properties and mechanical properties was obtained.

Further, since the metal powder produced by the atomization method forms a spherical shape relatively close to the sphere, it is excellent in dispersibility or fluidity with respect to the organic binder. Therefore, when the granulated powder is filled in a molding die and molded, the filling property can be improved, and finally, a sintered body having high dimensional accuracy and compactness can be obtained.

The average particle diameter of the magnetic metal powder used in the present invention is preferably 3 μm or more and 15 μm or less, more preferably 5 μm or more and 12 μm or less, and still more preferably 6 μm or more and 9 or more. Below μm. The magnetic metal powder of such a particle size can avoid significant aggregation or reduction in compressibility during molding, and can produce a sintered body which is sufficiently dense and has high dimensional accuracy. In the case where the average particle diameter does not reach the above lower limit value, the magnetic metal powder tends to aggregate and the compressibility at the time of molding is remarkably lowered. On the other hand, when the average particle diameter exceeds the above upper limit value, the gap between the particles of the magnetic metal powder is too large, and the densification of the sintered body finally obtained becomes insufficient.

In addition, the average particle diameter is obtained by the laser diffraction method as the particle diameter D50 when the cumulative amount is 50% by mass.

Further, the particle diameter D10 when the cumulative amount is 10% by mass is preferably 1.5 μm or more and 7 μm or less, more preferably 2 μm or more and 5 μm or less.

Further, the particle diameter D90 when the cumulative amount is 90% by mass is preferably 10 μm. The above is 30 μm or less, and more preferably 15 μm or more and 25 μm or less.

The magnetic metal powder having the particle size distribution as described above is capable of producing a magnetic metal sintered body which is uniform and excellent in magnetic properties and mechanical properties when producing a sintered body.

Further, the tap density of the magnetic metal powder used in the present invention is preferably 3.5 g/cm ³ or more, more preferably 3.8 g/cm ³ or more. In the case of the magnetic metal powder having a large density, the filling property between the particles during molding is particularly high. As a result, a particularly dense sintered body can be finally obtained. Further, the tap density of the magnetic metal powder can be measured, for example, according to the tap density measurement method specified in JIS Z 2512.

Further, the specific surface area of the magnetic metal powder used in the present invention is not particularly limited, but is preferably 0.15 m ² /g or more and 0.8 m ² /g or less, more preferably 0.2 m ² /g or more and 0.7 m ² / It is preferably not more than g, more preferably 0.3 m ² /g or more and 0.6 m ² /g or less. When the magnetic metal powder having a large specific surface area as described above has a high surface activity (surface energy), it can be easily sintered even if less energy is supplied. Therefore, when the formed body is sintered, it can be sintered in a shorter time, and it is easy to improve shape retention. On the other hand, when the specific surface area exceeds the above upper limit value, the contact area between the magnetic metal powder and the organic binder is increased to more than necessary, and the stability or fluidity of the composition is lowered. Further, the specific surface area of the magnetic metal powder can be measured, for example, according to the specific surface area measuring method of the powder (solid) adsorbed by gas as defined in JIS Z 8830.

(organic binder)

As described above, the organic binder contains the first binder component at a decomposition temperature of 1 at atmospheric pressure of TH [° C.] and the decomposition temperature at 1 atm is TL [° C.] (where TL does not reach TH). Adhesive ingredients. Therefore, each component can be a first binder component or a second binder component depending on the magnitude of the decomposition temperature in the selected combination. Further, the decomposition temperature is a temperature at which the weight starts to decrease as the temperature rises, and can be determined, for example, by thermogravimetric analysis, differential thermal analysis, or the like.

Examples of the component contained in the organic binder include, for example, polyethylene and polypropylene. a polyolefin of a polyolefin, a polybutene or a polypentene, such as a polyethylene-polypropylene copolymer, a polyolefin-based copolymer of a polyethylene-polybutylene copolymer, a styrene resin such as polystyrene, such as polymethyl. Acrylic resin of methyl acrylate, polybutyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyamine, such as polyethylene terephthalate, polybutylene terephthalate Various resins such as esters, polyethers, polyvinyl alcohols, polyacetals or copolymers thereof, or polymers containing unsaturated glycidyl groups, various waxes, higher fatty acids (for example, stearic acid), higher alcohols, higher grades One or a mixture of two or more of these may be used as the fatty acid ester, the higher fatty decylamine, the phthalic acid ester or the like.

In particular, the organic binder preferably contains a polymer containing an unsaturated glycidyl group, a styrene resin, and a wax as a first binder component or a second binder component, and further contains a phthalate ester as a separator. Adhesive ingredients other than those. Since the combination is a combination of a plurality of binder components having a moderately different decomposition temperature, the molding system containing the components is uniformly degreased in a short period of time when supplied to the degreasing treatment under the following conditions. As a result, a magnetic metal sintered body which is homogeneous and has high dimensional accuracy and excellent mechanical properties or magnetic properties is obtained. Hereinafter, the components will be described.

((Polymer containing unsaturated glycidyl group))

The polymer containing an unsaturated glycidyl group is a polymer containing a monomer having an unsaturated glycidyl group as a repeating unit. Examples of the monomer containing an unsaturated glycidyl group include glycidyl (meth)acrylate, allyl glycidyl ether, α-ethyl glycidyl ether, crotonyl glycidyl ether, and crotonyl glycidol. Ester, itaconic acid monoalkyl ester monoglycidyl ester, fumaric acid monoalkyl ester monoglycidyl ester, maleic acid monoalkyl ester monoglycidyl ester, (ali) containing alicyclic epoxy group In the acrylate or the like, the unsaturated glycidyl group-containing polymer used in the present invention is one or more selected from the group consisting of the unsaturated glycidyl group-containing monomers. Further, it is particularly preferable to use glycidyl (meth)acrylate.

Here, the glycidyl group is opened and bonded to the magnetic metal during mixing, forming, and the like. Hydroxyl bonding of the surface of the particles of the powder. As a result, the particles of the magnetic metal powder exhibit a high adhesion to the polymer containing the unsaturated glycidyl group, and this serves as a driving force to uniformly knead the magnetic metal powder and the organic binder without deviation. As a result, a degreased body which can finally produce a sintered body which is homogeneous and has high dimensional accuracy is produced.

Further, the polymer containing an unsaturated glycidyl group is preferably a copolymer comprising an unsaturated glycidyl group-containing monomer and an ethylenically unsaturated ester compound monomer as described above. The copolymer containing a monomer of an ethylenically unsaturated ester compound contributes to the realization of a molded body and a degreased body which are homogeneous and highly filled. In particular, both the ethylenically unsaturated ester compound monomer and the unsaturated glycidyl group-containing monomer contribute to affinity with the magnetic metal powder particles, and thus the homogeneity can be particularly improved.

Examples of the ethylenically unsaturated ester compound monomer include, for example, vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and methyl group. A carboxylic acid butyl acrylate, an α,β-unsaturated carboxylic acid alkyl ester, or the like may be used, and one or more of these may be used.

Among these ethylenically unsaturated ester compound monomers, it is particularly preferable to use at least one of vinyl acetate and methyl acrylate.

In addition, examples of the polymer containing an unsaturated glycidyl group include Rexpearl (manufactured by Japan Polyethylene), Modiper (manufactured by Nippon Oil & Fats Co., Ltd.), Umex (manufactured by Sanyo Chemical Industries Co., Ltd.), Bondine (manufactured by Simimoto Atofina), and Bondfast (Sumitomo). Chemical manufacturing).

Further, the unsaturated glycidyl group-containing polymer preferably contains a non-polar α-olefin monomer in addition to the unsaturated glycidyl group-containing monomer as described above. The polymer containing an unsaturated glycidyl group is rich in affinity with an olefin-based resin such as a styrene resin by containing a nonpolar α-olefin-based monomer as a repeating unit. As a result, the polymer containing an unsaturated glycidyl group has affinity with magnetic metal powder particles as described above, and also has affinity for other binder components. Stable presence between the magnetic metal powder and other binder components. As a result, it is possible to particularly suppress the improvement of the moldability of the degreased body (molded body) and the decrease in shape retention property.

Examples of the nonpolar α-olefin-based monomer include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, and the like. It is ethylene, propylene, 1-butene, 1-hexene, 1-octene.

Further, the softening point of the unsaturated glycidyl group-containing polymer used in the present invention is preferably 65 ° C or more and 105 ° C or less, more preferably 70 ° C or more and 100 ° C or less. The unsaturated glycidyl group-containing polymer at the softening point exhibits moderate flexibility during kneading and molding, and contributes to production of a degreased body of a sintered body having uniform homogeneity and high dimensional accuracy.

Further, the melt mass flow rate (190 ° C) of the unsaturated glycidyl group-containing polymer used in the present invention is preferably 2 [g/10 min] or more and 10 [g/10 min] or less, more preferably It is about 3 [g/10 min] or more and about 8 [g/10 min] or less. The unsaturated glycidyl group-containing polymer having a melt flow rate is excellent in the filling property in the molding die, and therefore contributes to the production of a degreased body of a sintered body which is particularly homogeneous and has high dimensional accuracy. Further, the melt flow rate can be measured in accordance with the method specified in JIS K 6922-2 at a measurement temperature of 190 ° C and a measurement load of 2.16 kg.

In addition, as the repeating unit constituting the polymer containing an unsaturated glycidyl group, as described above, a monomer containing an unsaturated glycidyl group may be mentioned, and if necessary, an ethylenically unsaturated ester compound monomer or a non-polar α- may be added. An olefin monomer or the like.

The ratio of the presence of the non-polar α-olefin monomer is preferably 300 parts by mass or more and 2,000 parts by mass or less, based on 100 parts by mass of the monomer containing the unsaturated glycidyl group. It is preferably 400 parts by mass or more and 1500 parts by mass or less. Thereby, the compatibility between the nonpolar α-olefin monomer and the styrene resin, and the affinity between the monomer containing the unsaturated glycidyl group and the magnetic metal particles can be highly balanced, and conformality and formability can be achieved. Coexist. As a result, it is possible to obtain a homogenization and a high dimensional accuracy. Degreased body of the knot.

In addition, the ethylenically unsaturated ester compound monomer is preferably 20 parts by mass or more and 80 parts by mass or less, more preferably 25 parts by mass or more and 75 parts by mass or less based on 100 parts by mass of the monomer containing the unsaturated glycidyl group. .

Further, as the polymer containing an unsaturated glycidyl group, a tensile strength of 4 MPa or more and 25 MPa or less can be preferably used, and a tensile strength of 5 MPa or more and 20 MPa or less can be more preferably used. The left and right.

In addition, the weight average molecular weight of the polymer containing an unsaturated glycidyl group is appropriately set in consideration of the melt flow rate and the like as described above, and as an example, it is preferably 10,000 or more and 400,000 or less, more preferably 30,000 or more. And 300,000 or less.

The content of the unsaturated glycidyl group-containing polymer in the organic binder is preferably from 15% by mass to 40% by mass, more preferably from 20% by mass to 35% by mass. By setting the content of the polymer containing an unsaturated glycidyl group within the above range, the affinity between the styrene resin and the magnetic metal particles can be improved, and the formability of the composition can be improved. As a result, it is possible to produce a degreased body of a sintered body which is homogeneous and has high dimensional accuracy.

((styrene resin))

The styrene resin imparts moderate mechanical strength to the organic binder to improve the shape retention of the molded body. Therefore, it contributes to the manufacture of a degreased body which can produce a sintered body which is particularly high in dimensional accuracy.

The styrene-based resin may, for example, be a polymer or a copolymer containing a styrene monomer as a repeating unit, and a homopolymer polystyrene may preferably be used.

The weight average molecular weight of the styrene resin is not particularly limited, but is preferably 5,000 or more and 70,000 or less, more preferably 7,000 or more and 50,000 or less. By the styrene-based resin containing the above molecular weight, it is possible to obtain a degreased body which can produce a sintered body which is homogeneous and has high dimensional accuracy.

The styrene-based resin preferably has a softening point higher than a softening point of a polymer containing an unsaturated glycidyl group, and is 90° C. or higher and 150° C. or lower, and more preferably has a softening point of 100° C. or higher. And below 140 ° C. By setting the weight average molecular weight of the styrene resin within the above range, the magnetic metal powder and the organic binder can be more uniformly mixed, and the formability of the composition can be further improved. As a result, it is possible to obtain a degreased body which can produce a sintered body which is homogeneous and has high dimensional accuracy.

The content of the styrene resin in the organic binder is preferably from 10% by mass to 50% by mass, more preferably from 15% by mass to 40% by mass. By setting the content of the styrene-based resin within the above range, moderate mechanical strength can be imparted to the organic binder, and the shape retaining property of the molded body can be improved, and the molded body can be homogenized. As a result, it is possible to produce a degreased body of a sintered body which is homogeneous and has high dimensional accuracy.

Further, the ratio of the styrene resin to the polymer containing the unsaturated glycidyl group is preferably 80% by mass or more and 150% by mass or less, more preferably 90% by mass or more and 140% by mass or less, and further preferably More than 100% by mass and 130% by mass or less. By setting the ratio within the above range, the affinity between the styrene resin and the magnetic metal particles and the formability of the composition can be particularly high, and a sintered body which is particularly homogeneous and has high dimensional accuracy can be produced. The manufacture of degreased bodies is possible.

((wax))

The wax system imparts moderate fluidity to the composition to improve the uniformity and formability of the composition. As a result, it contributes to the manufacture of a degreased body which is particularly homogeneous and has a high dimensional accuracy.

Examples of the wax include, for example, canary wax, carnauba wax, rice wax, wood wax, jojoba oil, vegetable wax, such as beeswax, lanolin, and cetyl wax, such as montan wax, a mineral wax such as paraffin wax, microcrystalline wax or petroleum wax such as paraffin wax; synthetic hydrocarbon such as polyethylene wax, such as montan wax derivative, paraffin derivative, microcrystalline wax derivative Modified waxes, such as hydrogenated castor oil, hydrogenated castor oil derivatives a wax, such as a fatty acid of 12-hydroxystearic acid, such as a decylamine of stearylamine, such as an ester of anhydrous phthalimide; one or more of these may be used in combination. .

Further, as the wax, a petroleum wax or a modified product thereof can be preferably used, and paraffin wax, microcrystalline wax, carnauba wax or the like can be more preferably used, and paraffin wax can be further preferably used. Or carnauba wax. Since these waxes are excellent in compatibility with a styrene resin, a homogeneous binder can be prepared.

Further, the weight average molecular weight of the wax is preferably 100 or more and less than 10,000, more preferably 200 or more and 5,000 or less. By setting the weight average molecular weight of the wax within the above range, the magnetic metal powder and the organic binder can be more uniformly mixed, and the formability of the composition can be further improved.

Further, as the wax, those having a softening point of 30 ° C or more and 100 ° C or less can be preferably used, and those having a softening point of 50 ° C or more and 95 ° C or less can be more preferably used.

Further, in the case of containing a wax, a plurality of waxes having different softening points may be contained. Thereby, the formability of the composition can be improved. In this case, the difference in softening point between the wax having the highest softening point and the wax having the lowest softening point is not particularly limited, but is preferably about 3 ° C or more and about 40 ° C or less, more preferably about 5 ° C or more and 30 ° C or less. . Specific examples of the combination include paraffin wax and carnauba wax.

The content of the wax in the organic binder is preferably from 10% by mass to 45% by mass, more preferably from 15% by mass to 40% by mass. By setting the content of the wax within the above range, it is possible to impart appropriate fluidity to the organic binder and to suppress a decrease in shape retention. As a result, it is possible to produce a degreased body capable of producing a sintered body which is particularly homogeneous and has high dimensional accuracy.

Further, the ratio of the wax to the polymer containing the unsaturated glycidyl group is preferably 80% by mass or more and 150% by mass or less, more preferably 90% by mass or more and 140% by mass or less, and further preferably more than 100% by mass. % by mass and 130% by mass or less. By setting the ratio within the above range, it is possible to impart moderate fluidity to the composition and to suppress the decrease in shape retention. low.

((phthalate))

The phthalate imparts moderate fluidity to the composition to improve the uniformity and formability of the composition. As a result, it contributes to the manufacture of a degreased body which is particularly homogeneous and has a high dimensional accuracy.

Examples of the phthalic acid ester include dimethyl phthalate, diethyl phthalate, butyl phthalate, dibutyl phthalate, and diisobutyl phthalate. The ester, dioctyl phthalate or the like may be used in combination of one or two of these.

The content of the phthalic acid ester in the organic binder is preferably from 5% by mass to 30% by mass, more preferably from 10% by mass to 25% by mass. By setting the ratio within the above range, it is possible to impart moderate fluidity to the composition and to suppress a decrease in shape retention.

In addition, the ratio of the phthalic acid ester to the polymer containing an unsaturated glycidyl group is preferably 30% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 70% by mass or less. By setting the ratio within the above range, it is possible to impart moderate fluidity to the composition and to suppress a decrease in shape retention.

((Other Ingredients))

Further, the organic binder may contain the above other components in addition to the above four types.

The carbon number of the saturated fatty acid is preferably about 12 or more and about 20 or less. Thereby, the formability can be particularly improved.

Further, examples of the higher fatty acid include stearic acid, oleic acid, and linoleic acid, and saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid are particularly preferably used.

Further, examples of the alcohol include a polyhydric alcohol, polyethylene glycol, and polyglycerol, and cetyl alcohol, stearyl alcohol, oleyl alcohol, mannitol, or the like can be preferably used.

Further, examples of the fatty acid metal include, for example, lauric acid, stearic acid, and amber. Acid, stearyl lactic acid, lactic acid, phthalic acid, benzoic acid, hydroxystearic acid, ricinoleic acid, naphthenic acid, oleic acid, palmitic acid, erucic acid, higher fatty acids such as Li, Na, Mg, Ca a compound of a metal such as Sr, Ba, Zn, Cd, Al, Sn, Pb or Cd, particularly preferably magnesium stearate, calcium stearate, sodium stearate, zinc stearate, calcium oleate or oil. Zinc acid, magnesium oleate, and the like.

Further, examples of the nonionic surfactant-based lubricant include Electrostripper TS-2 and Electrostripper TS-3 (King).

Further, examples of the polyfluorene-based lubricant include dimethyl polysiloxane and a modified product thereof, a carboxyl group-modified polyfluorene oxide, an α-methylstyrene modified polyoxane, and an α-olefin modification. Polyoxymethylene, polyether modified polyfluorene oxide, fluorine modified polyfluorene oxide, hydrophilic special modified polyoxyl oxide, olefin polyether modified polyfluorene oxide, epoxy modified polyoxyl oxide, amine modified Polyoxymethylene, guanamine modified polyoxo, alcohol modified polyoxane, and the like.

Further, examples of the other component include fatty acid esters such as palm oil, adipates such as dibutyl adipate, sebacate such as dibutyl sebacate, polyvinylpyrrolidone, and polyether. , propylene carbonate, bis-stearate, sodium alginate, agar, gum arabic, resin, sucrose, ethylene-vinyl acetate copolymer (EVA), etc., one or two of these may be combined More than one kind.

The content of the above component in the organic binder is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less.

Further, the mass of the other component relative to the polymer containing the unsaturated glycidyl group is preferably 0.005 or more and 0.3 or less, more preferably 0.01 or more and 0.2 or less.

Further, the composition may contain an antioxidant, a degreasing accelerator, a surfactant, and the like in addition to the above components.

In addition, the content of the organic binder in the composition is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass, based on 100 parts by mass of the magnetic metal powder. The following is around. Thereby, the composition can be reliably manufactured It is sufficient to produce a degreased body of a sintered body which is homogeneous and has high dimensional accuracy.

<Method for Producing Degreased Body and Method for Producing Sintered Body>

Next, a method for producing the degreased body of the present invention and a method for producing the sintered body will be described.

The method for producing a degreased body comprises: kneading a magnetic metal powder and an organic binder to obtain a kneading step of the kneaded material, forming a kneaded material into a desired shape, and degreasing the obtained molded body. The degreasing step of the treatment. Further, the method for producing a sintered body includes a calcination step of calcining the degreased body produced by the above-described method for producing a degreased body. Hereinafter, each step will be described in order.

(mixing step)

The kneaded material is prepared by kneading the above-mentioned magnetic metal powder, organic binder, or the like. In the kneading, for example, a pressurizing or two-arm kneading kneader, a roll kneading machine, a Banbury type kneading machine, and a single shaft can be used. Or a variety of kneading machines such as twin-screw extruders.

The kneading temperature in the kneading step is appropriately set depending on the softening point of each component of the organic binder. For example, a polymer or wax containing an unsaturated glycidyl group has a lower softening point than polystyrene, and therefore it is preferred to set the initial kneading temperature to a component having only the lowest softening point to soften and have a softening point higher. The temperature at which the ingredients do not soften. By repeating this operation from the side where the softening point is lower, the components can be softened one by one. Thereby, the uneven distribution of the components when the magnetic metal powder and the organic binder are kneaded is suppressed, and it contributes to the manufacture of the degreased body of the sintered body which is homogeneous and has high dimensional accuracy.

The kneading temperature is not particularly limited, and is preferably set to a temperature between the softening point of each component and the softening point of -10 °C. Further, it is preferred that the kneading temperature is gradually increased, and the final kneading temperature is set to a temperature between a softening point of the component having the highest softening point and a softening point of +70 °C.

Furthermore, the overall kneading time is preferably about 15 minutes or more and about 210 minutes or less.

The viscosity of the obtained kneaded material is preferably 500 P or more and 7000 P or less (50 Pa.s Up and 700 Pa. s or less), more preferably 1000 P or more and 6000 P or less (100 Pa.s or more and 600 Pa.s or less). Thereby, the formability at the time of shaping can be especially improved. Further, the viscosity was measured by maintaining the kneaded material at a temperature of 190 ° C and measuring it according to Capillograph.

Further, it is preferred that the organic binder supplied to this step is a powder. Further, when the organic binder is pulverized, a usual pulverization method is used, and it is particularly preferable to use freeze pulverization. The binder powder obtained by freeze pulverization is particularly fine and uniform, and has an original binder property that suppresses the heat influence upon pulverization.

Further, the average particle diameter of the binder powder is preferably from about 10 μm to about 500 μm, more preferably from about 15 μm to about 400 μm. By pulverizing by freeze pulverization to the above-described particle diameter, the influence of the difference in specific gravity at the time of mixing can be minimized, so that the binder powder and the magnetic metal powder can be uniformly mixed.

In addition, the average particle diameter is obtained by the laser diffraction method as the particle diameter when the cumulative amount is 50% by mass.

Further, when the composition as described above is kneaded, the temperature of the composition rises due to heating from the outside or self-heating accompanying the kneading. As a result, in the obtained kneaded material, an inner layer containing a polymer containing an unsaturated glycidyl group as a main material is formed so as to cover particles of the magnetic metal powder, and other components are formed as a main material on the outer side thereof. Outside layer. The polymer containing an unsaturated glycidyl group is less likely to cause sudden decomposition even when it is in contact with a metal element. Therefore, by forming the inner layer, the catalytic action accompanying the contact of other components with the metal element is suppressed. This catalytic action is effective in that the other components are suddenly decomposed when they are in contact with the metal element, and suppression of the action is suppressed in terms of suppression of cracking of the degreased body. As a result, sudden decomposition of the organic binder can be suppressed to avoid a decrease in shape retention.

(forming step)

Then, the formation of the obtained kneaded material is carried out. Thereby, a molded body of a desired shape and size is produced.

As the molding method, an injection molding method, a compression molding method, an extrusion molding method, or the like is used. The shape and size of the molded body to be produced is determined by estimating the amount of shrinkage caused by subsequent degreasing and sintering.

Further, the obtained molded body may be subjected to subsequent processing such as machining or laser processing as needed.

Further, the molded article to be supplied to the present invention is not limited to those produced by the above-described kneading step and molding step, and may be produced by any method.

(degreasing step)

Then, the obtained molded body is subjected to degreasing treatment. Thereby, the binder contained in the molded body is removed (degreased) to obtain a degreased body.

Fig. 1 is a view showing the steps of a degreasing step and a temperature rising process and a temperature lowering process included in the calcination step described below.

The shaped body is heated in a degreasing step, and the present invention includes a 3-stage degreasing warming process. Further, the heating temperature in each degreasing heating process is based on the decomposition temperature TH [° C.] of the first binder component in the organic binder at 1 atm, and the decomposition temperature TL [° C of the second binder component at 1 atm. ] and set.

Specifically, the degreasing treatment in the present invention includes: heating the first degreasing and heating process of the molded body at a temperature less than (TL-30 ° C), and after (TL-30 ° C) or more after the first degreasing heating process The second degreasing temperature rising process of the molded body at a temperature of TL + 50 ° C and the heating of the molded body at a temperature of (TL + 50 ° C) or more and less than (TH + 200 ° C) after the second degreasing heating process The third degreasing warming process. Hereinafter, each degreasing heating process will be described.

((1st degreasing heating process))

In the first degreasing heating process, the molded body was heated at a temperature not reached (TL-30 ° C). It is considered that although the organic binder is heated in this temperature region, most of it does not rise to decomposition. Therefore, the modification of the organic binder is suppressed, and the temperature of the molded body is made uniform.

The heating time in the first degreasing heating process is not particularly limited, but is preferably set to 0.5 small. The time is more than 15 hours or less, and more preferably 1 hour or more and 10 hours or less. Furthermore, in the degreasing heating process, the temperature is the highest temperature, and the heating may be continued at the highest temperature during the heating time, or may be performed at the highest temperature for only a part of the time, and the time is lower than the other time. The temperature at the highest temperature is heated. This case is also the same in the other heating processes described below.

In addition, the heating environment in the first degreasing and heating process is not particularly limited, and examples thereof include an environment containing an inert gas such as nitrogen or argon, an environment containing an oxidizing gas such as air, and an environment containing a reducing gas such as hydrogen. It is preferable to use an inert gas atmosphere, and it is more preferable to contain an atmosphere of nitrogen gas, such as a decompression environment which decompresses. Thereby, it is possible to suppress unintentional vaporization of the organic binder, oxidation or modification of the magnetic metal powder, and the like, and to uniformize the temperature of the molded body. As a result, it contributes to the manufacture of a degreased body of a sintered body which is homogeneous and has high dimensional accuracy.

In this case, the ambient pressure is preferably about atmospheric pressure (for example, about 50 kPa or more and about 200 kPa or less) or a pressure higher than atmospheric pressure.

In addition, as described above, the heating temperature in the degreasing and heating process is appropriately set depending on the composition of each component of the organic binder, and is set to 100 ° C or less as an example of the heating temperature.

Further, the degreasing step is carried out by placing the object to be treated in the degreasing device, and at this time, the object to be processed is arranged on the ceramic decking board, whereby the object to be treated is easy to handle, and the plurality of objects to be processed can be efficiently and uniformly processed. Degreasing treatment is carried out.

The material of the plating is selected in consideration of heat conduction, heat resistance (deformation resistance, decomposition resistance, etc.), non-reactivity with the workpiece, and low friction with the workpiece, and examples thereof include alumina.

Further, in the case where the object to be processed is placed on the decking, the arrangement pattern such as a lattice shape is used so as to be equally spaced as possible and the arrangement density is uniform. Thereby, the unevenness of the heat capacity is suppressed, and the degreasing treatment is made uniform.

Further, the decking plate can be placed in the degreasing device in a state in which the plurality of sheets are housed in the box-shaped casing. Thereby, the handling of the workpiece becomes easier, and the space utilization efficiency in the degreasing apparatus is improved.

The material of the casing is selected in consideration of heat capacity, heat conduction, heat resistance (deformation resistance, decomposition resistance, etc.), non-reactivity with the workpiece, and the like, and examples thereof include carbon.

((2nd degreasing heating process))

In the second degreasing heating process, the molded body was heated at a temperature of (TL-30 ° C) or more and less than (TL + 50 ° C). It is considered that in this temperature region, the second binder component starts to decompose, and on the other hand, the first binder component hardly decomposes. Therefore, the degree of progress of decomposition occurs between the two components, and the second binder component is preferentially removed. In this way, it is possible to achieve a degreasing action in which a large amount of the binder component is not decomposed in abrupt manner, and a small amount of the binder component is slowly decomposed and removed, and it is difficult to cause deformation and cracking of the molded body (degreased body) accompanying sudden decomposition. Waiting for an exception. In other words, when the second binder component is preferentially removed, a minute path is formed in the molded body after the passage of the second binder component. Therefore, during the subsequent temperature rise, the first binder component passes through the temperature rising process. The path is formed and discharged smoothly. Therefore, the degreased body of the sintered body having a high dimensional accuracy can be finally obtained by the second degreasing heating process.

The heating time in the second degreasing heating process is not particularly limited, but is preferably about 1 hour or more and 20 hours or less, and more preferably 2 hours or more and 15 hours or less. Thereby, the first adhesive component can be smoothly discharged during the subsequent temperature rise process to form a path of sufficient length or diameter.

In addition, the heating environment in the second degreasing and heating process is not particularly limited, and examples thereof include the above various environments, and particularly preferably a reduced pressure environment, and more preferably a reduced pressure environment in an environment containing an inert gas. Thereby, the decomposition of the second binder component can be promoted, and the heating temperature can be lowered even within the above range. As a result, it is possible to shorten the degreasing step, and it is difficult to soften the second binder component, thereby suppressing abnormalities such as deformation and cracking of the degreased body.

In addition, the pressure in a reduced pressure environment is not particularly limited, but is preferably 10 ^-4 Pa or more and 10 kPa or less, and more preferably 10 ^-3 Pa or more and 1 kPa or less. Thereby, the second binder component can be selectively decomposed and removed in a relatively short time. As a result, the shape retention property and the degreasing step can be highly coexisted in a short period of time.

Further, as described above, the heating temperature in the degreasing and heating process is appropriately set according to the composition of each component of the organic binder, and is, as an example of the heating temperature, higher than the heating temperature in the first degreasing and heating process, and is 50 ° C. Above and below 350 ° C.

((3rd degreasing heating process))

In the third degreasing heating process, the molded body was heated at a temperature of (TL + 50 ° C) or more and less than (TH + 200 ° C). It is considered that the decomposition of the first binder component is started in this temperature region. As described above, the first binder component is discharged through the path formed in the molded body (degreased body), so that it can be uniformly removed. As a result, a degreased body capable of producing a sintered body which is homogeneous and has high dimensional accuracy is obtained.

The heating time in the third degreasing heating process is not particularly limited, but is preferably about 0.5 hours or more and 15 hours or less, more preferably about 1 hour or more and 10 hours or less. Thereby, the organic binder component can be sufficiently removed.

Further, the heating environment in the third degreasing and heating process is not particularly limited, and examples thereof include the above various environments, and particularly preferably an environment containing an inert gas, and more preferably an atmosphere containing nitrogen. Thereby, oxidation or modification of the magnetic metal powder can be suppressed, and the decomposition component of the organic binder can be efficiently discharged by performing gas exchange around the molded body (degreased body). Further, from the viewpoint of gas exchange efficiency, it is preferred that the inert gas is continuously supplied (flowed) into the space in which the molded body is disposed without completely closing the inert gas.

In this case, the ambient pressure is preferably about atmospheric pressure (for example, about 50 kPa or more and about 200 kPa or less) or a pressure higher than atmospheric pressure.

Further, as described above, the heating temperature in the degreasing heating process is appropriately set according to the composition of each component of the organic binder, and is set to be higher than the second as an example of the heating temperature. The heating temperature in the degreasing heating process is 200 ° C or more and 600 ° C or less.

Further, TH-TL is preferably 10 ° C or more and 200 ° C or less, more preferably 30 ° C or more and 150 ° C or less. The composition of the second adhesive component and the composition of the first adhesive component are set such that the difference in the decomposition temperature is within the above range, whereby the adhesive component can be set sufficiently during the temperature rise process as described above. With the time difference, it is possible to obtain a degreased body which can produce a sintered body which is homogeneous and has high dimensional accuracy.

((degreasing and cooling process))

After the temperature rising process as described above, the degreased body is cooled. The cooling may be natural cooling by opening the atmosphere, natural cooling in a space filled with a cooling gas, or forced cooling by blowing or circulating a cooling gas.

As the cooling gas, it may be a gas during the temperature rise, preferably an inert gas, more preferably nitrogen. By using these gases, oxidation or modification of the magnetic metal powder can be suppressed, and oxidation or contamination in the degreasing apparatus can also be suppressed.

The degreasing step is completed as described above.

Further, after the degreasing treatment as described above, various subsequent processing may be performed on the obtained degreased body in order to trim or form a minute structure such as a groove.

Further, the binder in the molded body may not be completely removed by the degreasing treatment, and for example, a part of the binder may be left when the degreasing treatment is completed.

In the above-described manner, the temperature rising process in the degreasing step is performed in a plurality of stages in accordance with the decomposition temperature of the components of the organic binder, whereby various abnormalities in the molded body (degreased body) can be suppressed and degreasing can be performed uniformly. Thereby, it is possible to surely obtain a degreased body which can produce a sintered body which is uniform and has high dimensional accuracy.

Further, by performing the temperature rising process in the above manner, the degreasing efficiency can be improved and the degreasing can be completed in a shorter time. Therefore, the above-mentioned degreased body can be produced in a shorter time.

(calcination step)

Next, the calcination step will be described. Burned by calcining the degreased body The magnetic metal powder is knotted and a sintered body is obtained.

The degreased body is heated in the calcining step, and the present invention includes a three-stage calcination heating process. Specifically, the method includes: heating the degreasing body at a temperature of less than 750 ° C for the first calcination heating process, and heating the degreasing body to a second calcination temperature process at a temperature of 750 ° C or higher and less than 1050 ° C after the first calcination heating process. And heating the third calcination temperature rising process of the degreased body at a temperature of 1050 ° C or more and less than 1600 ° C after the second calcination heating process. Hereinafter, each calcination temperature rising process will be described.

((1st calcination heating process))

In the first calcination temperature rising process, the degreased body is heated at a temperature of less than 750 °C. In this temperature range, the organic binder remaining in the degreased body is removed, and the temperature of the degreased body is made uniform. Therefore, by heating in the temperature region for a certain period of time, it is possible to achieve uniformization of sintering in the following calcination temperature rising process. In addition, the heating temperature is appropriately set within the above range depending on the composition of the organic binder, and as an example, it is preferably 500 ° C or more and less than 750 ° C.

The heating time in the first calcination temperature rising process is not particularly limited, but is preferably about 1 hour or more and 20 hours or less, more preferably 2 hours or more and 15 hours or less. Thereby, the organic binder is reliably removed and the temperature of the degreased body is sufficiently uniformized.

In addition, the heating environment in the first calcination temperature rising process is not particularly limited, and examples thereof include the above various environments, and more preferably a reduced pressure environment, and more preferably a reduced pressure environment of an inert gas. Thereby, oxidation or modification of the magnetic metal powder can be suppressed, and the decomposition component of the organic binder can be efficiently discharged by performing gas exchange and vacuum discharge around the degreased body.

((2nd calcination heating process))

In the second calcination temperature rising process, the degreased body is heated at a temperature of 750 ° C or higher and less than 1050 ° C. In this temperature region, sintering of the magnetic metal powder is started. In addition, a reaction in which oxygen atoms contained in the magnetic metal powder are bonded to and vaporized by carbon atoms contained in the decomposition component of the organic binder is also started. As a result, accompanied by reduction of magnetic metal powder The improvement in sinterability is performed simultaneously with the discharge of the decomposition component of the organic binder, which contributes to an improvement in mechanical properties, magnetic properties, and the like of the sintered body finally obtained.

The heating time in the second calcination temperature rising process is not particularly limited, but is preferably about 1 hour or more and 25 hours or less, more preferably 2 hours or more and 20 hours or less.

Further, the heating environment in the second calcination temperature rising process is not particularly limited, and examples thereof include the above various environments, and particularly preferably an environment containing an inert gas, and more preferably an argon-containing atmosphere. Thereby, oxidation or modification of the magnetic metal powder can be suppressed and the magnetic metal powder can be sintered efficiently.

Further, in the calcination temperature rising process, for example, carbon monoxide or the like is generated by bonding oxygen atoms to carbon atoms, and therefore it is preferred to increase the gas exchange by continuously supplying (flowing) an inert gas into the arrangement space of the degreased body. Efficiency and promote waste discharge.

In this case, the ambient pressure may be equal to or higher than atmospheric pressure, and in consideration of cost or the like, it is preferably about atmospheric pressure (for example, about 50 kPa or more and about 200 kPa or less).

((3rd calcination heating process))

In the third calcination temperature rising process, the degreased body is heated at a temperature of 1050 ° C or higher. In this temperature region, the magnetic metal powder reaches a final sintered state to produce a sintered body. In addition, the maximum heating temperature is appropriately set according to the composition of the magnetic metal powder, and is, for example, about 1050 ° C to 1400 ° C.

The heating time in the third calcination temperature rising process is not particularly limited, but is preferably about 1 hour or more and 25 hours or less, and more preferably 2 hours or more and 20 hours or less.

Further, the heating environment in the third calcination temperature rising process is not particularly limited, and examples thereof include the above-described various environments, and particularly preferably an environment containing an inert gas, and more preferably an argon-containing atmosphere. Thereby, the same effects as described above are obtained.

Further, in the calcination temperature rising process, it is preferred that the inert gas is completely enclosed in the arrangement space of the degreased body. Thereby, for example, even if the magnetic metal powder contains vapor such as Cr In the case of an element having a relatively high pressure, the calcination temperature rising process in an environment in which an inert gas is enclosed may make it difficult to vaporize the above elements and suppress unintentional changes in the composition of the magnetic metal powder.

In this case, the ambient pressure may be equal to or higher than atmospheric pressure, and in consideration of cost or the like, it is preferably about atmospheric pressure (for example, about 50 kPa or more and about 200 kPa or less).

((1st calcination cooling process))

After the temperature rising process as described above, the sintered body is cooled. The cooling process is not particularly limited, and preferably includes a first calcination cooling process and a second calcination cooling process thereafter.

In the first calcination and cooling process, the sintered body is placed in a reduced pressure environment. Thereby, the contact of the sintered body with oxygen or nitrogen can be prevented to prevent contamination of the sintered body. At the same time, it is also possible to prevent contamination in the calcining device. Further, by being placed in a reduced pressure environment, the temperature of the sintered body after sintering can be prevented from drastically decreasing. Thereby, generation of contamination, cracking, deformation, and the like of the sintered body can be suppressed. Furthermore, it is also possible to gradually lower the temperature while heating the sintered body as needed.

Further, the reduced pressure environment is preferably a reduced pressure environment of an inert gas.

In addition, the pressure in a reduced pressure environment is not particularly limited, but is preferably about 10 ^-4 Pa or more and about 10 kPa or less, and more preferably about 10 ^-3 Pa or more and about 1 kPa or less. Thereby, an appropriate temperature drop rate and prevention of contamination of the sintered body can be prevented, and a high-quality sintered body can be produced in a short time.

The cooling time in the first calcination and cooling process is not particularly limited, but is preferably about 1 minute or more and about 1 hour or less, and more preferably about 3 minutes or more and 30 minutes or less.

((2nd calcination cooling process))

In the second calcination and cooling process, the sintered body is placed in an inert gas atmosphere. Thereby, the cooling of the sintered body is performed by heat exchange with the environment. Further, by using an inert gas, it is possible to prevent oxidation of the sintered body or contamination in the calcining apparatus. Further, in this case, the heat exchange efficiency may be improved by continuously supplying (flowing) or circulating the inert gas in the arrangement space of the sintered body.

During the calcination and cooling process, it is cooled to a normal temperature, and thereafter, even if the sintered body is in contact with the atmosphere, the enthalpy of oxidation is reduced.

The sintered body was produced in the above manner.

The relative density of the obtained sintered body is desirably 95% or more, and preferably 96% or more. Such a sintered body has a high sintered density and is excellent in appearance and dimensional accuracy.

Further, the obtained sintered body may be subjected to various subsequent processes such as machining (cutting, pressing, polishing, etc.), electric discharge machining, laser processing, etching, and the like. By performing such subsequent processing, it is possible to perform trimming or to further improve the dimensional accuracy.

Further, the obtained sintered body may be subjected to a HIP treatment (hot isostatic pressing treatment) or the like as necessary. Thereby, it is possible to further increase the density of the sintered body.

As a condition of the HIP treatment, for example, the temperature can be set to 850 ° C or more and 1100 ° C or less, and the time can be set to 1 hour or more and 10 hours or less.

Further, the pressurizing pressure is preferably 50 MPa or more, more preferably 100 MPa or more.

The sintered body obtained in the above manner can be used for any purpose, and various structural components, various medical structures, and the like can be cited as the use thereof.

Fig. 2 is a (a) plan view and a (b) X-X cross-sectional view showing a yoke case as an application example of the sintered body produced by the present invention.

The yoke case 1 shown in Fig. 2 has an annular plate-like body having a through hole 101 penetrating the center portion in a plan view, that is, a case body 10, which is provided at the outer edge and the inner edge of the case body 10, and has a thickness and a case. The body 10 is thicker than the edge portion 11 of the case body 10, and is spaced apart from the outer edge and the inner edge of the case body 10 at equal intervals along the inner edge and has a thickness thicker than the case body 10, respectively, and is scattered. A plurality of through holes 13 are formed between the outer edge and the inner edge of the cartridge body 10 and through the cartridge body 10.

The yoke case 1 is composed of a sintered body of soft magnetic metal powder. Each of the cores 12 is wound, whereby the yoke case 1 constitutes a part of the magnetic actuator. Therefore, the yoke case 1 is required to have extremely high dimensional accuracy.

Therefore, the size of the sintered yoke case 1 is detected by a detector. By using the detector, it is possible to detect whether or not the size of the yoke case 1 is within the design value in a short time without separately measuring the size of each portion of the yoke case 1.

Fig. 3 is a (a) plan view and (b) a Y-Y line sectional view showing an example of a tester which can be applied to the detection of the yoke case shown in Fig. 2.

The detector 2 shown in FIG. 3 has a ring-shaped plate-like body, that is, a meter body 20, and a convex portion 21 provided inside the meter body 20 so as to protrude from one side of the meter body 20, and The through holes 22 of the meter body 20 are arranged at equal intervals along the outer edge of the meter body 20.

When the detector 2 is placed so as to overlap the yoke case 1, the convex portion 21 can be inserted into the through hole 101 of the cartridge body 10, and on the other hand, the core 12 can be inserted into the through hole 22. Further, the outer diameter of the convex portion 21 reflects the design value of the inner diameter of the through hole 101, and the arrangement, shape, and size of the through hole 22 reflect the respective design values of the arrangement, shape, and size of the core 12. Therefore, when the probe 2 is inserted into the through hole 101 and the core 12 is inserted into the through hole 22, the through hole 101 and the through hole 22 are designed so that the design value can be displayed. Therefore, the detecting worker of the yoke case 1 can confirm whether or not the detecting meter 2 can be applied, that is, whether the convex portion 21 can be inserted into the through hole 101 and the core 12 can be inserted into the through hole 22, so that the magnetic field can be performed in a short time. The size of the yoke box 1 is detected.

Moreover, the sintered body 3 after the manufacture is arranged in the package 4 made of resin, and is stored and transported. Fig. 4 is a perspective view showing an example of a package form of a sintered body. On the package 4, the rustproof paper 41 is coated as needed. Thereby, oxidation, deterioration, and the like of the sintered body 3 can be suppressed.

Further, the package 4 may be housed in the bag 5 in a state in which the rustproof paper 41 is covered. Thereby, the sintered body 3 can be prevented from coming into contact with the outside air to suppress the oxygen of the sintered body 3. Change, deterioration, etc. Further, as the bag 5, for example, a polyethylene manufacturer can be used, and if necessary, an aluminum laminate processor can be used.

The present invention has been described above on the basis of preferred embodiments, but the present invention is not limited thereto. For example, in the degreasing step, a degreasing heating process or a degreasing and cooling process may be further added as needed, or a degreasing heating process may be set again after the degreasing and cooling process. Similarly, in the calcination step, the calcination heating process or the calcination cooling process may be further added as needed, or the calcination heating process may be set again after the calcination and cooling process.

[Examples]

Next, specific embodiments of the invention will be described.

1. Manufacture of sintered body (Example 1)

First, a magnetic metal powder containing 49% by mass of Fe-49% by mass of Co-2% by mass of a V-based alloy (iron-cobalt alloy) was prepared. The average particle diameter of the magnetic metal powder was measured by a laser diffraction type particle size distribution measuring apparatus (Microtrac, manufactured by Nikkiso Co., Ltd., HRA 9320-X100). As a result, D10 was 3.2 μm, D50 was 8.1 μm, and D90 was 19.9 μm.

Then, the polymer containing the unsaturated glycidyl group, the styrene resin, and the paraffin are respectively subjected to freeze-pulverization to obtain a binder powder.

Then, the magnetic metal powder, the binder powder, and the phthalic acid ester were mixed, and kneaded by a pressure kneader at a kneading temperature of 160 ° C for 30 minutes. This kneading was carried out in a nitrogen atmosphere. In addition, the amount of the binder component added to 100 parts by mass of the magnetic metal powder is 7.5 parts by mass.

Then, the obtained kneaded material was pulverized by a pelletizer to obtain particles having an average particle diameter of 5 mm.

Then, using the obtained pellets, molding was carried out by an injection molding machine under molding conditions of a material temperature of 190 ° C and an injection pressure of 10.8 MPa (110 kgf / cm ² ). Thereby, a molded body is obtained.

Then, the obtained molded body was subjected to degreasing treatment under the conditions shown in Table 1. Thereby, a degreased body is obtained.

Then, the obtained degreased body was subjected to a calcination treatment under the conditions shown in Table 1. Thereby, a sintered body is obtained. The obtained sintered system is a plate-like body (yoke box) formed into an annular shape as shown in Fig. 2, and has an outer diameter of 35 mm, an inner diameter of 10 mm, and a maximum thickness of 5 mm.

(Examples 2 to 10)

A sintered body was obtained in the same manner as in Example 1 except that the components shown in Tables 1 and 2 were used as the organic binder, and the degreasing conditions and the calcination conditions were set as shown in Tables 1 and 2, respectively.

(Comparative examples 1 to 6)

A sintered body was obtained in the same manner as in Example 1 except that the components shown in Tables 1 and 2 were used as the organic binder, and the degreasing conditions and the calcination conditions were set as shown in Tables 1 and 2, respectively.

Further, the meanings of the respective components of the organic binder in Tables 1 and 2 are as follows. Further, in the following unsaturated glycidyl group-containing polymer, E means a repeating unit containing ethylene, GMA means a repeating unit containing glycidyl methacrylate, and VA means a repeating unit containing vinyl acetate. , MA means a repeating unit containing methyl acrylate.

<Polymer containing unsaturated glycidyl group>

‧GMA-1: E-GMA-VA copolymer (decomposition temperature 310 ° C)

‧GMA-2: E-GMA copolymer

‧GMA-3: E-GMA-MA copolymer (decomposition temperature 280 ° C)

<styrene resin>

‧PS: polystyrene (weight average molecular weight 10000) (decomposition temperature 350 ° C)

<wax>

‧PW-1: paraffin (decomposition temperature 260 ° C)

‧PW-2: paraffin (decomposition temperature 230 ° C)

<phthalate>

‧DBP: Dibutyl phthalate

Further, regarding the melt flow rate of the polymer containing an unsaturated glycidyl group, GMA-1 was 7 g/10 min, GMA-2 was 3 g/10 min, and GMA-3 was 7 g/10 min.

2. Evaluation of sintered body 2.1 Evaluation of Sintering Density

The sintered body obtained in each of the examples and the comparative examples was measured for density by a method according to the Archimedes method (specified in JIS Z 2501). Further, the relative density of the sintered body was calculated from the measured sintered density and the true density of the magnetic metal powder.

2.2 Evaluation of appearance

The appearance of the 100 sintered bodies obtained in each of the examples and the comparative examples was evaluated in accordance with the following evaluation criteria.

<Evaluation criteria for appearance>

◎: The number of occurrences of cracks, defects, and deformations was three or less.

○: The number of occurrences of cracks, defects, and deformations was 4 or more and 10 or less.

△: The number of occurrences of cracks, defects, and deformations was 11 or more and 50 or less.

×: The number of occurrences of cracks, defects, and deformations was 51 or more.

2.3 Evaluation of dimensional accuracy

The outer diameter of each of the 100 sintered bodies obtained in each of the examples and the comparative examples was measured by a micrometer. In addition, the average value of the measured values is evaluated based on the following evaluation criteria based on the "wide tolerance difference" defined in JIS B 0411 (General Permissible Difference of Metal Sintered Products).

<Evaluation criteria for dimensional accuracy>

◎: The grade is a fine grade (the allowable difference is ±0.05 mm or less).

○: The rating is medium (the tolerance is more than ±0.05 mm and is ±0.1 mm or less).

△: The level is a normal level (the allowable difference is more than ±0.1 mm and is ±0.2 mm or less).

×: Outside the license range.

The above evaluation results are shown in Tables 1 and 2.

As is clear from Tables 1 and 2, it was confirmed that the sintered bodies obtained in the respective examples had higher sintered densities than the sintered bodies obtained in the respective comparative examples. In addition, it was confirmed that the sintered body obtained in each of the examples was superior in appearance and dimensional accuracy as compared with the sintered body obtained in each of the comparative examples.

Further, with respect to each sintered body, a wire was wound around each core, and the formed coil was energized, whereby the magnetic properties of the respective cores were measured and compared. As a result, it was confirmed that the magnetic properties of the sintered bodies obtained in the respective examples were higher than those of the sintered bodies obtained in the respective comparative examples. Specifically, it was confirmed that the iron loss and the coercive force were small and the magnetic flux density was large. Further, it was confirmed that the magnetic properties of these are excellent as the sintered density is higher.

Further, when pure iron, niobium steel, iron-iron-aluminum magnetic alloy, and nickel-iron magnetic alloy were used instead of the iron-cobalt alloy, the same tendency as in the case of the above-described iron-cobalt alloy was confirmed.

2.4 Evaluation of sintering uniformity

The Vickers hardness of each core surface of the yoke case shown in Fig. 2 was measured for the sintered bodies obtained in the respective Examples and Comparative Examples. Then, the distribution width of the twelve measured values was calculated and compared in each sintered body.

As a result, the distribution width of the Vickers hardness of the sintered body obtained in each of the examples was narrow as compared with the distribution width of the Vickers hardness of the sintered body obtained in each of the comparative examples. Therefore, it was confirmed that the uniformity of the sintered body obtained in each of the examples was higher than that of the sintered bodies obtained in the respective comparative examples.

Further, a magnetic actuator was produced using the yoke case obtained in each of the examples and the comparative examples. Further, in the magnetic actuator manufactured, the cores of the yoke case are wound and energized, whereby the cores generate magnetic force to drive the needles arranged for each core. Therefore, in the case of the yoke case shown in Fig. 2, 12 pins are arranged.

Then, the driving force when the 12 needles were driven was measured. As a result, in terms of the distribution range of the driving force, compared with the yoke case obtained in each comparative example, in each of the examples The yoke boxes obtained are all narrow.

Claims (14)

A method for producing a degreased body, which is obtained by degreasing a molded body comprising a magnetic metal powder or an organic binder containing any one of Fe, Ni, and Co as a main component to obtain a degreased body. The organic binder contains a first binder component having a decomposition temperature of TH [° C.] at 1 atm, and a second binder component at a decomposition temperature of 1 atm, which is less than TL [° C.] of the above TH, and The degreasing treatment includes: heating the first degreasing temperature rising process of the molded body at a temperature not reached (TL-30 ° C), and after (TL-30 ° C) or more (TL + 50) after the first degreasing heating process The temperature of °C) is used to heat the second degreasing temperature rising process of the molded body, and after the second degreasing heating process, the first molded body is heated at a temperature of (TL + 50 ° C) or more and less than (TH + 200 ° C). 3 degreasing heating process. The method for producing a degreased body according to claim 1, wherein the TH-TL is 10 ° C or more and 200 ° C or less. The method for producing a degreased body according to claim 1 or 2, wherein the organic binder comprises a polymer containing an unsaturated glycidyl group as the first binder component or the second binder component. The method for producing a degreased body according to claim 1 or 2, wherein the organic binder comprises polystyrene as the first binder component or the second binder component. The method for producing a degreased body according to claim 1 or 2, wherein the organic binder comprises a wax as the first binder component or the second binder component. The method for producing a degreased body according to claim 1 or 2, wherein the organic binder comprises a phthalate ester as a component other than the first binder component and the second binder component. The method for producing a degreased body according to claim 1 or 2, wherein the first degreasing and heating process is carried out in an atmosphere containing an inert gas. The method for producing a degreased body according to claim 1 or 2, wherein the second degreasing and heating process is carried out in a reduced pressure environment. The method for producing a degreased body according to claim 1 or 2, wherein the third degreasing and heating process is carried out in an atmosphere containing an inert gas. The method for producing a degreased body according to claim 1 or 2, wherein the magnetic metal powder has an average particle diameter of 3 μm or more and 15 μm or less. The method for producing a degreased body according to claim 1 or 2, wherein the magnetic metal powder has a tap density of 3.5 g/cm ³ . The method of manufacturing a request degreased body 1 or 2 of the items, wherein the ratio of the magnetic metal powder of the surface area of 0.15m ² / g or more and 0.8m ² / g or less. A method of producing a sintered body, comprising: heating a first calcination temperature-increasing process of a degreased body produced by the method for producing a degreased body according to any one of claims 1 to 12 at a temperature of less than 750 ° C, After the first calcination temperature rising process, the second calcination heating process of the degreased body is heated at a temperature of 750 ° C or higher and less than 1050 ° C, and after the second calcination heating process, the temperature is 1050 ° C or more and less than 1600 ° C. The third calcination temperature rising process of the above-mentioned degreased body is heated at a temperature. The method for producing a sintered body according to claim 13, wherein after the third calcination temperature rising process, the degreased body is cooled in a reduced pressure atmosphere, and then the degreased body is cooled in an environment in which an inert gas is continuously supplied.