JP6702773B2 - Method for manufacturing metal powder compact and metal powder compact - Google Patents

Description

The present invention relates to a method for producing a metal powder compact and a metal powder compact. More specifically, the present invention relates to a method for producing a metal powder compact, which has high mixability and fluidity of raw material powders, is less likely to adhere to a mold, and is excellent in shape retention. .. Further, the present invention relates to a metal molded body having a uniform composition and excellent shape retention.

Generally, metal powder compaction is to compact a raw material powder into a metal powder compact having a desired shape. Metal powder molding can be mass-produced while reducing the processing cost, that even hard-to-cut materials such as cemented carbide can be molded into the desired shape, and the material and composition of the molded body is the raw material powder. There is an advantage that it can be easily adjusted by blending. The metal powder compact may be used as it is, or may be fired after molding and used as a fired body. In particular, when a metal powder compact having a complicated shape or a fine structure is used as it is, chipping or the like is more likely to occur than in a fired body, and thus the metal powder compact is required to have high shape retention. Further, even if the metal powder molded body is not used as it is, it is required to have a high shape-retaining property in order to carry and store it in a stable state. When the metal powder compact is used as it is, it may be required to increase the proportion of the main raw material as much as possible in order to fully exhibit the properties of the main raw material.

Examples of the method for producing a metal powder compact having a high shape retention property include the following. Metal fine particles, which are the main raw material, are mixed with fine metal particles to increase the number of contact points between particles, and a binder, a large amount of solvent, etc. are added, and after wet mixing, granules are formed using a granulator in the granulation process. This is a method of press-molding the granules (for example, Patent Documents 1 and 2). However, the method for producing a metal powder compact described in Patent Document 1 includes a step of wet mixing, which sometimes requires a large amount of energy to evaporate the excess solvent. Further, a large amount of solvent is required in the wet mixing step, and in the case of a raw material powder that dislikes water as the solvent, it is necessary to use an organic solvent, which may result in high cost. Further, since a granulation step for producing granules is required, the steps may be complicated. Further, when the fine metal particles are mixed with the coarse metal particles as the main raw material, impurities are likely to be mixed, and the ratio of the main raw material of the metal powder compact described in Patent Document 1 may be low.

Here, as a method of mixing the main raw material with a binder or the like to obtain a powder molding raw material, there is dry mixing in addition to wet mixing. The dry mixing is a mixing method in which the amount of the solvent added when mixing the main raw material and the binder and the like is smaller than that of the wet mixing, without a step of evaporating the solvent after mixing or a granulation step, The powder molding raw material can be press-molded.

The following is a method for producing a powder compact using such dry mixing. To reduce the particle size of the main raw material for powder compacts, and to increase the amount of excipients (binders) that bind the particles together and additives that improve fluidity during press molding (function as a lubricant, etc.) Then, there is a method for producing a powder compact that facilitates compaction while ensuring the fluidity of the powder as the main raw material (for example, Patent Document 3).

JP, 2008-31552, A Japanese Patent No. 4947613 Japanese Patent No. 4841564

As described above, in the invention described in Patent Document 3, it is possible to obtain a powder compact by continuous press molding by limiting the particle size and adding a large amount of excipients, binders, fluidizing agents and the like. it can. However, the method described in Patent Document 3 has a problem in that the strength of the powder compact is low and shape retention is difficult to obtain when coarse particles, which are powders having a large particle size, are used as the main raw material. Further, when a hard metal powder such as silicon, molybdenum, tungsten, beryllium, chromium, or tungsten carbide is used as the main raw material of the powder molding raw material, there is a problem that the strength of the powder molded body is low and shape retention is difficult to obtain. .. Further, with the method described in Patent Document 3, it is difficult to manufacture a metal powder compact having a complicated shape or a fine structure because the shape retention of the powder compact is insufficient. Generally, in order to improve the shape retention of the metal powder molded body, the ratio of the mass of the excipient and the binder to the mass of the metal powder molding raw material, the ratio of the mass of the fluidizing agent, the water contained in the binder. It is conceivable to increase either the mass ratio, or both the mass ratio of the superplasticizer and the mass ratio of water. However, if these are increased, there is a problem that lumps are likely to occur when the metal powder forming raw materials are mixed, and the mixability of the metal powder forming raw materials deteriorates. Further, due to the deterioration of the mixing property of the metal powder molding raw material, the adhesion of the metal powder molding raw material to the mold sometimes becomes severe. Further, since the mixing property is deteriorated, the fluidity of the metal powder molding raw material is also deteriorated, which sometimes makes continuous molding difficult. Further, the composition and the density of the metal powder compact after press molding may become non-uniform due to deterioration of the mixing property. As described above, in the case of producing a metal powder compact by the conventional method for producing a powder compact, the shape retention of the obtained metal powder compact is improved and the mixing property of the metal powder compacts is improved, which is excellent. Achieving formability was a trade-off. For this reason, it was very difficult to solve both at the same time.

The present invention has been made in view of such problems. ADVANTAGE OF THE INVENTION According to this invention, manufacture of a metal powder compact which has high mixability and fluidity of raw material powder, is hard to adhere to a metal mold, and can manufacture a metal powder compact excellent in shape retention property. A method is provided. Further, a metal molded product having a uniform composition and excellent shape retention is provided.

According to the present invention, the following method for producing a metal powder compact and a metal powder compact are provided.

[1] A forming raw material preparation step of producing a metal powder forming raw material by mixing and kneading a raw material powder containing 10 mass% or more of metal powder and a binder, and press forming the metal powder forming raw material to form a metal powder forming A molded body producing step of producing a body, and using at least a saccharide having 20 or less carbon atoms and a solvent as the binder, in the forming raw material producing step, the binder is added to 100 parts by mass of the raw material powder. A method for producing a metal powder compact, which comprises adding 3.5 to 20 parts by mass to produce the metal powder compact material ,
The method for producing a metal powder compact, wherein the saccharide having 20 or less carbon atoms is trehalose .

[2] The method for producing a metal powder compact according to [1], wherein the mass ratio of the saccharide having 20 or less carbon atoms in the binder 100 mass parts is 20 to 80 mass parts.

[3] The method for producing a metal powder molded body according to the above [1] or [2], wherein the mass ratio of the solvent in 100 parts by mass of the binder is 20 to 80 parts by mass.

[4] The method for producing a metal powder compact according to any one of [1] to [3], wherein the saccharide having 20 or less carbon atoms is used in a solid state in the forming raw material producing step.

[ 5 ] The method for producing a metal powder compact according to any one of [1] to [ 4 ], wherein the raw material powder contains carbon powder.

[ 6 ] The method for producing a metal powder compact according to [ 5 ], wherein the carbon powder is less than 15 parts by mass with respect to 100 parts by mass of the raw material powder.

[ 7 ] The method for producing a metal powder molded body according to any one of [1] to [ 6 ], wherein the pressing pressure applied to the metal powder molding raw material is 5 to 200 MPa in the molded body manufacturing step.

[ 8 ] The metal powder includes fine metal particles having a particle diameter of 10 to 1000 nm, coarse metal particles having a particle diameter of 100 to 1000 μm, or fine metal particles having a particle diameter of 10 to 1000 nm and coarse particles having a particle diameter of 100 to 1000 μm. The method for producing a metal powder compact according to any one of the above [1] to [ 7 ], which comprises metal particles as a main material.

[ 9 ] At least the metal powder is selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, tantalum, niobium, titanium, and magnesium. The method for producing a metal powder compact according to any one of [1] to [ 8 ], which is a powder containing one kind of metal.

[ 10 ] A molded body obtained by press-molding a molding raw material, wherein the molded body contains a raw material powder containing 10 mass% or more of metal powder and a binder containing a saccharide having 20 or less carbon atoms. A metal powder compact containing 0.7 to 16 parts by mass of the saccharide having 20 or less carbon atoms per 100 parts by mass ,
A metal powder compact, wherein the saccharide having 20 or less carbon atoms is trehalose .

[ 11 ] The metal powder compact according to [ 10 ], wherein the raw material powder contains carbon powder.

[ 12 ] The metal powder compact according to [ 11 ], wherein the carbon powder is less than 15 parts by mass with respect to 100 parts by mass of the raw material powder.

[ 13 ] The metal powder is fine metal particles having a particle diameter of 10 to 1000 nm, coarse metal particles having a particle diameter of 100 to 1000 μm, or fine metal particles having a particle diameter of 10 to 1000 nm and coarse particles having a particle diameter of 100 to 1000 μm. The metal powder compact according to any one of [ 10 ] to [ 12 ], which contains metal particles as a main material.

[ 14 ] The metal powder is at least selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, tantalum, niobium, titanium, and magnesium. The metal powder compact according to any one of [ 10 ] to [ 13 ], which is a powder containing one kind of metal.

According to the method for producing a metal powder molding material of the present invention, the metal powder molding raw material can be uniformly mixed without causing lumps, and thus the metal powder molding raw material has high mixability. Further, since the metal powder compact has high mixability, the fluidity of the metal powder molding raw material is also high. Further, during press molding, the metal powder molding raw material is less likely to be attached to the mold. Furthermore, it is possible to manufacture a metal powder compact having excellent shape retention and uniform composition.

More specifically, the method for producing a metal powder compact of the present invention includes a forming raw material producing step and a compact producing step. The forming raw material producing step is a step of producing a metal powder forming raw material by mixing and kneading a raw material powder containing 10 mass% or more of metal powder and a binder, and dry-mixing. Then, at least a saccharide having 20 or less carbon atoms and a solvent are used as the binder, and 3.5 to 20 parts by mass of the binder is added to 100 parts by mass of the raw material powder in the forming raw material manufacturing step. The molded body manufacturing step is a step of press-molding the metal powder molding raw material manufactured in the molding raw material manufacturing step to manufacture a metal powder molded body. According to the method for producing a metal powder compact of the present invention, the metal powder compact having a high mixing property of the metal powder compact and a uniform composition can be produced by the above-mentioned forming raw material producing step. Further, the ratio of the metal powder to the metal powder forming raw material can be increased. In addition, since the metal powder forming raw material has high fluidity, it is easy to flow the metal powder forming raw material into the mold in the forming process of the formed body. Further, the metal powder forming raw material is unlikely to adhere to the mold. Further, since the shape retention of the metal powder compact after press molding is high, a metal powder compact having a complicated shape or a fine structure can be manufactured. For example, in the conventional method for producing a powder compact, when a coarse metal powder having a large particle size is used, it is difficult to realize a complicated shape or a fine structure. According to the manufacturing method, it is possible to realize a complicated shape or a fine structure even when a coarse-grained metal powder is used. Further, in the conventional method for producing a powder compact, it was difficult to mix the metal powder when a fine metal powder having a small particle size of 1 micron or less was used. According to the method for producing a body, the metal powder can be mixed well even when the fine metal powder is used.

The metal powder compact of the present invention has a uniform composition and high shape retention. Therefore, a metal powder compact having a complicated shape or a fine structure can be obtained. Further, the ratio of the mass of the metal powder to the mass of the entire metal powder forming raw material can be increased.

More specifically, the metal powder compact of the present invention comprises a compact obtained by press molding a molding raw material. Moreover, the said green compact contains the raw material powder containing 10 mass% or more of metal powder, and the binder containing the saccharide whose carbon number is 20 or less, and has 20 carbon atoms or less with respect to 100 mass parts of raw material powder. 0.7 to 16 parts by mass. With this configuration, a metal powder compact having a uniform composition and a high shape-retaining property and having a complicated shape or a fine structure can be obtained.

It is a perspective view which shows typically 1st embodiment of the metal powder compact of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. Therefore, it is understood that, without departing from the spirit of the present invention, those obtained by appropriately modifying and improving the following embodiments are also included in the scope of the present invention based on ordinary knowledge of those skilled in the art. Should be.

(1) Method for producing metal powder compact The first embodiment of the method for producing a metal powder compact of the present invention will be described below.

The method for producing a metal powder compact of the present embodiment includes a forming raw material producing step and a compact producing step. The forming raw material producing step is a step of producing a metal powder forming raw material by mixing and kneading a raw material powder containing 10 mass% or more of metal powder and a binder. Then, at least a saccharide having 20 or less carbon atoms and a solvent are used as the binder, and 3.5 to 20 parts by mass of the binder is added to 100 parts by mass of the raw material powder in the forming raw material manufacturing step. Further, the molded body manufacturing step is a step of press-molding the metal powder molding raw material manufactured in the molding raw material manufacturing step to manufacture a metal powder molded body.

The forming raw material producing step is to produce a metal powder forming raw material by dry mixing. Therefore, in the method for manufacturing the metal powder compact of the present embodiment, the step of evaporating the solvent and the granulation step are not required after the forming raw material preparing step. That is, in the method for manufacturing a metal powder molded body of the present embodiment, the metal powder molding raw material obtained in the molding raw material manufacturing step is directly subjected to the molding body manufacturing step, and the metal powder molded body is manufactured by press molding. .. Therefore, according to the method for producing a metal powder compact of the present embodiment, the metal powder compact can be produced extremely simply and at low cost.

The raw material powder used in the forming raw material manufacturing step contains 10 mass% or more of metal powder. The metal powder in the raw material powder is preferably 10 to 100% by mass, more preferably 50 to 100% by mass, and particularly preferably 90 to 99% by mass. When the metal powder in the raw material powder is less than 10% by mass, the amount of the metal powder in the raw material powder is too small, and it becomes difficult to obtain a metal powder compact having desired metal characteristics.

As the binder, at least a saccharide having 20 or less carbon atoms and a solvent are used. Then, by adding 3.5 to 20 parts by mass of the binder to 100 parts by mass of the raw material powder, the shape retention of the obtained metal powder molding is improved, and the mixing property and fluidity of the metal powder molding raw material are improved. Improvement in moldability due to superiority is realized together. That is, when the binder containing a saccharide having 20 or less carbon atoms and a solvent is less than 3.5 parts by mass, the raw material powder cannot be sufficiently bonded during press molding, and the obtained metal powder molded body is obtained. The shape retention property of is reduced. On the other hand, when the amount of the binder is more than 20 parts by mass, the amount of the binder becomes excessive, the mixing property and fluidity of the metal powder forming raw material deteriorate, and the continuous formability (productivity) greatly decreases. Further, when the amount of the binder is excessive, the metal powder molding raw material easily adheres to the mold, which may make it difficult to achieve good press moldability. In addition, even if saccharides having 20 or less carbon atoms are not used as the binder and 3.5 to 20 parts by mass of the binder is added to 100 parts by mass of the raw material powder, the shape retention of the resulting metal powder compact is obtained. It is difficult to achieve both the improvement in moldability and the improvement in moldability due to the excellent mixability and fluidity of the metal powder molding raw material. For example, when a saccharide having 20 or less carbon atoms is not used as the binder, the metal powder molding raw material is likely to be lumped and the mixing property of the metal powder molding raw material is significantly deteriorated. Therefore, in order to improve the mixing property, it is necessary to reduce the amount of the binder, but when the amount of the binder is reduced, it is impossible to improve the shape retention of the metal powder forming raw material.

The binder containing a saccharide having 20 or less carbon atoms and a solvent is 3.5 to 20 parts by mass with respect to 100 parts by mass of the raw material powder. The binder containing a saccharide having a carbon number of 20 or less and a solvent is preferably 5.1 to 15 parts by mass, more preferably 5.5 to 10 parts by mass, relative to 100 parts by mass of the raw material, Particularly preferably, it is 5.5 to 7.5 parts by mass.

The metal powder is at least one metal selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, titanium, niobium, tantalum, and magnesium. It is preferably a powder containing Further, the metal powder is more preferably a powder containing at least one metal selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, and cobalt. Furthermore, it is particularly preferable that the metal powder is silicon. In addition, the case where the surface of the metal powder is oxidized and the metal oxide is generated on at least a part of the surface is also referred to as the metal powder. However, a powder such as ceramic in which the inside of the metal powder is oxidized is a metal oxide powder and is not called a metal powder.

The metal powder is at least two kinds of metals selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, titanium, niobium, tantalum, and magnesium. It is also preferable that the metal alloy powder contains. Further, the metal powder is more preferably a metal alloy powder containing at least two kinds of metals selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium and cobalt. In addition, the case where the surface of the metal alloy powder is oxidized and the metal oxide is generated on at least a part of the surface is also referred to as the metal alloy powder. However, powders such as ceramics that have been oxidized to the inside of the metal alloy powder are metal alloy oxide powders and are not called metal alloy powders.

The metal powder contains at least one metal selected from the group consisting of molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, titanium, niobium, tantalum, and magnesium. It is also preferably a metal silicide powder. Further, the metal powder is more preferably a metal silicide powder containing at least one metal selected from the group consisting of molybdenum, tungsten, iron, manganese, vanadium, and niobium.

As the metal powder, two or more kinds of metal powders having different average particle sizes may be used. Further, as the metal powder, two or more kinds of metal powders having different constituent elements may be used. Further, the average particle diameter of the metal powder is not particularly limited. In general, when a metal powder containing a metal powder composed of fine metal particles as a main raw material is used, compared with a case where a metal powder containing a metal powder composed of coarse metal particles is used as a main raw material, the metal powder Mixability and fluidity of the forming raw material may deteriorate. Further, in general, when using a metal powder containing a metal powder consisting of coarse metal particles as a main raw material, compared to a case using a metal powder containing a metal powder consisting of fine metal particles as a main raw material, Since there are few points of contact between the powders, the shape retention of the metal powder compact may be reduced. In addition, the "main raw material" refers to a metal powder having a ratio of 80 mass% or more to 100 mass%. In the method for producing a metal powder molded body of the present embodiment, even if a metal powder composed of fine metal particles is used as a main raw material of the metal powder, the mixing property and the fluidity of the metal powder molding raw material are lowered. Can be suppressed. Further, even when a metal powder composed of coarse metal particles is used as the main raw material of the metal powder, the shape retention of the metal powder compact can be improved. In addition, in this specification, the average particle diameter of the metal powder is a value measured by the following method. First, the metal particles constituting the metal powder are classified into particles having a particle diameter of more than 250 μm and particles having a particle diameter of 250 μm or less. The classification of the metal particles can be performed by a sieve. For the classified “powder consisting of particles having a particle size of more than 250 μm”, a particle size analysis using a sieve is performed to obtain a particle size distribution curve of the metal powder. When the particle diameter distribution curve is obtained by sieving the classified “powder consisting of particles having a particle diameter of more than 250 μm”, for example, 350 μm, 500 μm, 750 μm, and 1000 μm sieves are used, and the respective particle size (particle It is possible to determine the mass of the particle having a diameter. Further, regarding the classified “particles having a particle diameter of 250 μm or less”, a particle diameter analysis by a laser diffraction method is performed to obtain a particle diameter distribution curve of the metal powder. Next, the particle size distribution curve obtained by the particle size analysis using a sieve and the particle size distribution curve obtained by the laser diffraction method are superposed to obtain a particle size distribution curve of the metal powder, and an average particle size of the metal powder is obtained. .. When the particle diameters of all the metal particles constituting the metal powder are apparently 250 μm or less, the particle diameter analysis using a sieve may be omitted. Hereinafter, "metal powder consisting of fine metal particles" and "metal powder consisting of coarse metal particles" may be referred to as "fine metal particles" and "coarse metal particles", respectively. ..

The metal powder may contain fine metal particles having a particle diameter of 10 to 1000 nm as a main raw material. When the metal powder contains such fine metal particles having a particle diameter of 10 to 1000 nm as a main raw material, for example, it is preferable to use a fine powder having an average particle diameter of 10 to 1000 nm as the metal powder. It is more preferable to use a fine powder having a diameter of 10 to 500 nm, and it is particularly preferable to use a fine powder having an average particle diameter of 10 to 100 nm. In the method for producing a metal powder compact according to the present embodiment, as the metal powder, fine metal powder containing fine metal particles having a particle diameter of 10 to 1000 nm as a main raw material and having an average particle diameter of 1000 nm or less is also used. It is possible to suppress the deterioration of the mixing property and the fluidity of the metal powder forming raw material. The ratio (mass %) of the mass of the metal particles having a predetermined particle size to the mass of the entire metal powder can be calculated from the particle size distribution of the metal particles that can be obtained by the laser diffraction method.

The metal powder may contain coarse metal particles having a particle diameter of 100 to 1000 μm as a main raw material. When the metal powder contains such coarse metal particles having a particle diameter of 100 to 1000 μm as the main raw material, for example, it is preferable to use a coarse powder having an average particle diameter of 100 to 1000 μm as the metal powder, It is more preferable to use coarse powder having an average particle diameter of 150 to 800 μm, and it is particularly preferable to use coarse powder having an average particle diameter of 200 to 500 μm. In the method for producing a metal powder compact according to the present embodiment, when a coarse powder containing coarse metal particles having a particle diameter of 100 to 1000 μm as a main raw material and having an average particle diameter of 100 μm or more is used as the metal powder. Also, the shape retention of the metal powder compact can be improved. Note that the ratio (mass %) of the mass of the metal particles having a predetermined particle size to the mass of the entire metal powder, from the particle size analysis by sieving, or the particle size distribution of the metal particles that can be obtained by the laser diffraction method, It can be calculated.

The metal powder may contain fine metal particles having a particle diameter of 10 to 1000 nm and coarse metal particles having a particle diameter of 100 to 1000 μm as main raw materials. There is no particular limitation on the mass ratio between the mass of fine metal particles having a particle diameter of 10 to 1000 nm and the mass of coarse metal particles having a particle diameter of 100 to 1000 μm in the main raw material.

In the forming raw material producing step, the ratio of the mass of the saccharide having 20 or less carbon atoms in 100 parts by mass of the binder is preferably 20 to 80 parts by mass, and more preferably 40 to 70 parts by mass. It is preferably 50 to 70 parts by mass, and particularly preferably. If the ratio of the mass of the saccharide having 20 or less carbon atoms to 100 parts by mass of the binder is less than 20 parts by mass, the mixing property of the metal powder forming raw material may be deteriorated and the fluidity may be deteriorated. Further, when the ratio of the mass of the saccharide having 20 or less carbon atoms in 100 parts by mass of the binder is more than 80 parts by mass, the saccharide having 20 or less carbon atoms is not completely dissolved in the solvent and the obtained metal powder. The shape retention of the molded product may be reduced.

Examples of saccharides having 20 or less carbon atoms include non-reducing disaccharides and sugar alcohols. Examples of the non-reducing disaccharide and sugar alcohol include the non-reducing disaccharide and sugar alcohol shown below.

As the non-reducing disaccharide, sucrose in which α-glucose and β-fructose are 1,2-glycoside-bonded, trehalose in which α-glucose and α-glucose are 1,1-glycoside-bonded, β-glucose and β-glucose are 1,1-glycoside-bonded isotrehalose, α-glucose and β-glucose are 1,1-glycoside-bonded neotrehalose, and α-galactose. Galactosucrose, which is a 1,2-glycosidic bond to β-fructose, can be mentioned. Among the above-mentioned non-reducing disaccharides, trehalose and neotrehalose are preferable, and trehalose is particularly preferable. Here, the non-reducing disaccharide is a disaccharide that does not form a reducing aldehyde group or ketone group in a basic solution. Among the above-mentioned non-reducing disaccharides, trehalose has a particularly high hydration power. Therefore, for example, when the solvent contains water, the water is more evenly dispersed in the metal powder forming raw material by the trehalose. That is, the water molecule is stabilized by solvation such as hydrogen bond formed between trehalose and water molecule rather than hydrogen bond formed between water molecules in the solvent. Therefore, trehalose becomes a more preferable binder of the metal powder molding raw material for producing the metal powder molded body.

Examples of sugar alcohols include erythritol, sorbitol, xylitol, mannitol, maltitol, lactitol and the like. Among the above sugar alcohols, erythritol, sorbitol, xylitol and mannitol are preferable, erythritol, sorbitol and xylitol are more preferable, and xylitol is particularly preferable.

As the saccharide having 20 or less carbon atoms, one of the above-mentioned saccharides having 20 or less carbon atoms may be selected and used as a binder, or two or more types may be selected and used as a binder.

In the forming raw material producing step, the ratio of the mass of the solvent in 100 parts by mass of the binder is preferably 20 to 80 parts by mass, more preferably 30 to 60 parts by mass, and 30 to 50 parts by mass. Is particularly preferable. With such a configuration, the saccharides having 20 or less carbon atoms can be sufficiently adapted to the solvent, and the raw material powder can be sufficiently bound at the time of press molding. "Familiar" means "a saccharide having 20 or less carbon atoms is dissolved in a solvent, a saccharide having 20 or less carbon atoms is dispersed without being dissolved in a solvent, or both".

Water or an organic solvent is preferable as the solvent. It is also preferable that the mixed solvent is a mixture of water and an organic solvent. When the solvent is a mixed solvent, the mixed solvent preferably contains water in an amount of more than 0% by mass and less than 80% by mass and an organic solvent in an amount of less than 100% by mass and more than 20% by mass. Further, the mixed solvent more preferably contains water in an amount of more than 0% by mass and less than 60% by mass and an organic solvent in an amount of less than 100% by mass and more than 40% by mass. Furthermore, it is particularly preferable that the mixed solvent contains water in an amount of more than 0% by mass and less than 30% by mass and an organic solvent in an amount of less than 100% by mass and more than 70% by mass. When an organic solvent or a mixed solvent is used as the solvent, the solvent contains almost no water, the solvent contains no water, or the mass ratio of water contained in the solvent becomes small. Therefore, a metal powder compact can be produced even if the raw material powder contains a substance that reacts with water (a substance that dislikes water).

As the organic solvent, ethylene glycol, diethylene glycol, 2-propanol, normal butanol, hexane, methanol, ethanol, carbon tetrachloride, acetone, benzene, ethyl acetate, and toluene are preferable.

The binder may contain other components as a binder other than the sugar having 20 or less carbon atoms and the solvent. Other components include a cellulose-based binder and polyvinyl alcohol. As the cellulosic binder, methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, and carboxymethyl cellulose are preferable.

When the binder contains the above-mentioned other components (that is, sugars having 20 or less carbon atoms, and components other than the solvent), the other components are 0.1 to 30 parts by mass with respect to 100 parts by mass of the binder. Is preferable, 5 to 25 parts by mass is more preferable, and 10 to 20 parts by mass is particularly preferable.

The raw material powder may contain a powder other than the metal powder. Other powders can include, for example, higher fatty acid metal salts, boron, powdered glass, and carbon powder. Further, among these other powders, zinc stearate, lithium stearate, and carbon powder, which function as a lubricant between the particles of the metal powder, function as a lubricant between the particles of the metal powder, so press molding is performed. At the same time, the metal powder raw material can be pressed and solidified with a uniform density, and the shape retention of the metal powder molded body after press molding can be enhanced.

In addition, the raw material powder may include an organic molding aid, a pore-forming agent, and the like as other powders. The organic molding aid functions as a dispersant that further enhances the mixing properties of the raw material powders, a lubricant for the particles of the metal powder, and the like. Examples of organic molding aids include surfactants, silicone oil, glycerin, liquid paraffin, and phenol resins. Examples of the surfactant include anionic surfactants, cationic surfactants, nonionic surfactants, and zwitterionic surfactants. Examples of the pore-forming agent include foamed resin and water-absorbent resin.

The amount of the other powder that functions as a lubricant between the metal particles of the metal powder is preferably less than 15 parts by mass, and 0.5 parts by mass or more and less than 10 parts by mass, relative to 100 parts by mass of the raw material powder. Is more preferable, and 0.5 parts by mass or more and less than 5 parts by mass is particularly preferable. If the amount of the other powder is 15 parts by mass or more with respect to 100 parts by mass of the raw material powder, the composition may not be uniform, and it may be difficult to obtain a metal powder compact having desired characteristics.

When the other powder that functions as a lubricant for the metal particles of the metal powder is carbon powder, the following carbon powder is preferable. Carbon powder includes fine carbon powder, activated carbon powder, granular activated carbon powder, carbon yarn powder, carbon felt powder, glassy carbon powder, scaly graphite powder, lumpy graphite powder, earthy graphite powder, and heat. It is preferably a decomposed graphite powder. The carbon powder may be derived from natural graphite or artificial graphite.

Among the above-mentioned carbon powders, those derived from natural graphite are preferable. The density and the average particle diameter of the carbon powder derived from natural graphite are preferably the density and the average particle diameter in the following ranges, respectively. A carbon powder having a density of 1.45 to 2.25 g/cm ³ and an average particle diameter of 1 to 500 μm is preferable, and a carbon powder having a density of 1.6 to 2.2 g/cm ³ and an average particle diameter of 10 to 300 μm is more preferable. Carbon powder having 1.8 to 2.1 g/cm ³ and an average particle diameter of 20 to 200 μm is particularly preferable. The average particle diameter value is a value measured by a laser diffraction method.

In the forming raw material producing step, the method for producing the metal powder forming raw material by mixing and kneading the raw material powder and the binder is not particularly limited, and for example, a mixer or the like can be used. Examples of the mixer include Kenmix mixer (product number: KMM-770) manufactured by Aikosha Seisakusho.

In the forming raw material preparation step, a saccharide having 20 or less carbon atoms may be dissolved in a solvent as a solute in advance and then added to the raw material powder as a binder, or a saccharide having 20 or less carbon atoms in a solid state. After mixing with the raw material powder, the solvent may be added to the mixture of the raw material powder and the saccharide having 20 or less carbon atoms. Hereinafter, "the saccharide having a carbon number of 20 or less in a solid state and the raw material powder are mixed to form a mixture, and then a solvent is added to the mixture" is referred to as "a saccharide having a carbon number of 20 or less in the solid state. It is used in the state." When a solid saccharide having 20 or less carbon atoms is used, it is not necessary to previously dissolve a saccharide having 20 or less carbon atoms as a solute in a solvent, and it is necessary to manage a solution of saccharides having 20 or less carbon atoms. Nor. Therefore, from the viewpoint of workability and cost reduction, it is preferable to use solid saccharides having 20 or less carbon atoms in the forming raw material manufacturing step.

In the forming process of the formed body, the metal powder forming raw material is poured into a mold, press-formed, and then taken out from the mold to obtain a metal powder formed body. As the mold, it is preferable to use a mold designed to have a desired shape of the metal powder compact. As the material of the die, die steel, cemented carbide, ceramic and the like are preferable. It is also preferable that the surface of the mold is sprayed with these materials and coated with CVD.

In the forming process of the formed body, the pressing pressure applied to the metal powder forming raw material is preferably 5 to 200 MPa, more preferably 10 to 100 MPa, and particularly preferably 40 to 80 MPa. In the forming process of the formed body, if the press pressure applied to the metal powder forming raw material is less than 5 MPa, the metal powder formed body may not be solidified, and if it is more than 200 MPa, wear of the mold may be severe. ..

The method for producing a metal powder compact of the present embodiment may further include a compact drying step of drying the metal powder compact obtained in the compact production step. The drying method is not particularly limited and may be natural drying, but it is preferable to dry in a hot air dryer at 40 to 160°C. By performing such a molded body drying step, it is possible to improve the shape retention of the obtained metal powder molded body.

(2) Metal powder compact The first embodiment of the metal powder compact of the present invention will be described below.

As shown in FIG. 1, the metal powder compact 1 of the present embodiment is formed by press molding a molding raw material. Moreover, the said green compact contains the raw material powder containing 10 mass% or more of metal powder, and the binder containing the saccharide whose carbon number is 20 or less, and has 20 carbon atoms or less with respect to 100 mass parts of raw material powder. It contains 0.7 to 16 parts by mass of the saccharide. FIG. 1 is a perspective view schematically showing a first embodiment of the metal powder compact of the present invention.

As described above, the metal powder compact of the present embodiment contains the raw material powder containing 10 mass% or more of the metal powder and the binder containing the saccharide having 20 or less carbon atoms. Then, 0.7 to 16 parts by mass of saccharides having 20 or less carbon atoms are included with respect to 100 parts by mass of the raw material powder. Therefore, the metal powder compact has a uniform composition and high shape retention. Further, since the shape retention property is high, a metal powder compact having a complicated shape or a fine structure can be formed, if necessary. Furthermore, if necessary, the ratio of the mass of the metal powder to the mass of the metal powder forming raw material can be increased.

The “ratio of the mass of the metal powder to 100 parts by mass of the raw material powder” can be measured by the following method. First, a metal powder compact is crushed, and a part of the powder is used as a test powder. Next, the test powder is subjected to a qualitative/quantitative analysis using an energy dispersive X-ray device (EDX) to determine the type of the metal powder contained in the metal powder compact, and "for 100 parts by mass of the test powder, "Mass ratio of metal powder" is obtained. The "ratio of the mass of the metal powder to 100 parts by mass of the test powder" is defined as the "ratio of the mass of the metal powder to 100 parts by mass of the metal powder compact". Moreover, "the ratio of the mass of the sugar having 20 or less carbon atoms to 100 mass parts of the raw material powder" can be measured by the following method. First, the test powder is dried in a dry atmosphere at 80° C. for 60 minutes or more. Then, the test powder after drying is diluted with KBr powder, and qualitative/quantitative analysis is performed using a Fourier transform infrared spectroscope (FT-IR). Is the ratio of the masses of 20 or less sugars". And "the ratio of the mass of the sugar having 20 or less carbon atoms to 100 parts by mass of the test powder" is defined as "the ratio of the mass of the metal powder to 100 parts by mass of the raw material powder".

The molded body contains a binder containing a saccharide having 20 or less carbon atoms. The molded body contains 0.7 to 16 parts by mass of saccharides having 20 or less carbon atoms with respect to 100 parts by mass of the raw material powder. The molded product preferably contains 2.0 to 10.5 parts by mass, more preferably 2.8 to 7 parts by mass, and further preferably 2.8 to 5.3 parts by mass with respect to 100 parts by mass of the raw material powder. Is particularly preferable.

The raw material powder contains metal powder in an amount of 10% by mass or more. The metal powder in the raw material powder is preferably 10 to 100% by mass, more preferably 50 to 100% by mass, and particularly preferably 90 to 99% by mass. If the content of the metal powder in the raw material powder is less than 10% by mass, the amount of the metal powder in the raw material powder may be too small and desired metal characteristics may not be obtained.

The binder containing a saccharide having 20 or less carbon atoms is preferably 1.1 to 16 parts by mass, more preferably 2.0 to 10.5 parts by mass, relative to 100 parts by mass of the raw material powder. It is more preferably 2.8 to 7 parts by mass, and particularly preferably 2.8 to 5.3 parts by mass.

The metal powder is at least one metal selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, titanium, niobium, tantalum, and magnesium. It is preferably a powder containing Further, the metal powder is more preferably a powder containing at least one metal selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, and cobalt. Furthermore, it is particularly preferable that the metal powder is silicon. In addition, the case where the surface of the metal powder is oxidized and the metal oxide is generated on at least a part of the surface is also referred to as the metal powder. However, a powder such as ceramic in which the inside of the metal powder is oxidized is a metal oxide powder and is not called a metal powder.

The metal powder is at least two kinds of metals selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, titanium, niobium, tantalum, and magnesium. It is also preferable that the metal alloy powder contains. Further, the metal powder is more preferably a metal alloy powder containing at least two kinds of metals selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium and cobalt. In addition, the case where the surface of the metal alloy powder is oxidized and the metal oxide is generated on at least a part of the surface is also referred to as the metal alloy powder. However, powders such as ceramics that have been oxidized to the inside of the metal alloy powder are metal alloy oxide powders and are not called metal alloy powders.

The metal powder contains at least one metal selected from the group consisting of molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, titanium, niobium, tantalum, and magnesium. It is also preferably a metal silicide powder. Further, the metal powder is more preferably a metal silicide powder containing at least one metal selected from the group consisting of molybdenum, tungsten, iron, manganese, vanadium, and niobium.

The metal powder may be composed of two or more kinds of metal powders having different average particle diameters. Further, the metal powder may be composed of two or more kinds of metal powders having different constituent elements. Further, the average particle diameter of the metal powder is not particularly limited. In general, when a metal powder containing a metal powder composed of fine metal particles as a main raw material is used, compared with a case where a metal powder containing a metal powder composed of coarse metal particles is used as a main raw material, the metal powder Mixability and fluidity of the forming raw material may deteriorate. Further, in general, when using a metal powder containing a metal powder consisting of coarse metal particles as a main raw material, compared to a case using a metal powder containing a metal powder consisting of fine metal particles as a main raw material, Since there are few points of contact between the powders, the shape retention of the metal powder compact may be reduced. In addition, the "main raw material" refers to a metal powder having a ratio of 80 mass% or more to 100 mass%. The metal powder compact of the present embodiment suppresses deterioration of the mixing property and the fluidity of the metal powder molding raw material even when the metal powder composed of fine metal particles is used as the main raw material of the metal powder. be able to. Further, even when a metal powder composed of coarse metal particles is used as the main raw material of the metal powder, the shape retention of the metal powder compact can be improved. The average particle size is a value measured by the particle size analysis using the above-mentioned sieve and the laser diffraction method.

The metal powder may contain fine metal particles having a particle diameter of 10 to 1000 nm as a main raw material. When the metal powder contains such fine metal particles having a particle diameter of 10 to 1000 nm as a main raw material, for example, it is preferable to use a fine powder having an average particle diameter of 10 to 1000 nm as the metal powder. It is more preferable to use a fine powder having a diameter of 10 to 500 nm, and it is particularly preferable to use a fine powder having an average particle diameter of 10 to 100 nm. In the metal powder compact of the present embodiment, the metal powder contains fine metal particles having a particle diameter of 10 to 1000 nm as a main raw material, and even if the average particle diameter is 1000 nm or less, in the manufacturing process thereof, Mixability and fluidity of the metal powder forming raw material do not easily deteriorate. The ratio (mass %) of the mass of the metal particles having a predetermined particle size to the mass of the entire metal powder can be calculated from the particle size distribution of the metal particles, which can be obtained by a laser diffraction method.

The metal powder may contain coarse metal particles having a particle diameter of 100 to 1000 μm as a main raw material. When the metal powder contains such coarse metal particles having a particle diameter of 100 to 1000 μm as the main raw material, for example, it is preferable to use a coarse powder having an average particle diameter of 100 to 1000 μm as the metal powder, It is more preferable to use coarse powder having an average particle diameter of 150 to 800 μm, and it is particularly preferable to use coarse powder having an average particle diameter of 200 to 500 μm. In the metal powder compact of the present embodiment, even if the metal powder contains coarse metal particles having a particle diameter of 100 to 1000 μm as a main raw material and the average particle diameter is 100 μm or more, the metal powder molding is performed. The shape retention of the body can be enhanced. The ratio (mass %) of the mass of the metal particles having a predetermined particle size to the mass of the entire metal powder can be determined by a particle size analysis using a sieve or a laser diffraction method. From the particle size distribution of the metal particles , Can be calculated.

The metal powder may contain fine metal particles having a particle diameter of 10 to 1000 nm and coarse metal particles having a particle diameter of 100 to 1000 μm as main raw materials. There is no particular limitation on the mass ratio between the mass of fine metal particles having a particle diameter of 10 to 1000 nm and the mass of coarse metal particles having a particle diameter of 100 to 1000 μm in the main raw material.

Examples of saccharides having 20 or less carbon atoms include non-reducing disaccharides and sugar alcohols. Examples of the non-reducing disaccharide and sugar alcohol include the non-reducing disaccharide and sugar alcohol shown below.

As the non-reducing disaccharide, sucrose in which α-glucose and β-fructose are 1,2-glycoside-bonded, trehalose in which α-glucose and α-glucose are 1,1-glycoside-bonded, β-glucose and β-glucose are 1,1-glycoside-bonded isotrehalose, α-glucose and β-glucose are 1,1-glycoside-bonded neotrehalose, and α-galactose. Galactosucrose, which is a 1,2-glycosidic bond to β-fructose, can be mentioned. Among the above-mentioned non-reducing disaccharides, trehalose and neotrehalose are preferable, and trehalose is particularly preferable. Here, the non-reducing disaccharide is a disaccharide that does not form a reducing aldehyde group or ketone group in a basic solution.

Examples of sugar alcohols include erythritol, sorbitol, xylitol, mannitol, maltitol, lactitol and the like. Among the above sugar alcohols, erythritol, sorbitol, xylitol and mannitol are preferable, and erythritol, sorbitol and xylitol are more preferable. From the viewpoint of fluidity of the raw material powder, erythritol is particularly preferable.

The binder may contain other components as a binder other than the sugar having 20 or less carbon atoms and the solvent. Other components include a cellulose-based binder and polyvinyl alcohol. As the cellulosic binder, methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, and carboxymethyl cellulose are preferable.

When the binder contains the above-mentioned other components (that is, components other than sugars having 20 or less carbon atoms), the other components are 0.1 to 60 parts by mass with respect to 100 parts by mass of the binder. Is more preferable, 10 to 50 parts by mass is more preferable, and 30 to 40 parts by mass is particularly preferable.

The raw material powder may contain a powder other than the metal powder. As the powder other than the metal powder, the same powder as the other powder described in the embodiment of the method for manufacturing the metal powder compact described above can be mentioned. Also, the blending amount of other powders contained in the raw material powder is preferably the same as the value described in the embodiment of the method for manufacturing the metal powder compact described above.

When the other powder is a carbon powder, it is preferable to use the carbon powder described in the section of the method for producing a metal powder compact, and the density and the average particle diameter of the carbon powder are also preferably the same. ..

The shape of the metal powder compact is not particularly limited and is appropriately determined depending on, for example, the shape of the space in the mold. As described above, the metal powder molding raw material for producing the metal powder molded body is unlikely to adhere to the mold. Therefore, the metal powder molded body of the present embodiment has extremely good releasability from the mold, and thus can be molded into a complex shape or a shape having a fine structure. For example, the shape of the metal powder compact may be a relatively simple shape such as a prismatic shape or a cylindrical shape, or a shape having irregularities on the outer surface thereof or a shape having a thin portion. It may be. For example, the metal powder compact may have a local thickness of 3 mm or less.

The metal powder compact of the present embodiment is not limited to this as long as the shape of the metal powder compact can be maintained, but the bending strength is preferably 0.5 MPa or more. Here, the bending strength is a three-point bending strength in which the direction of pressing during press molding is the load load direction, and was measured using a material testing machine manufactured by Instron (model number: 5900 series). It is a value. The bending strength is measured by cutting out a test piece of “length of the metal powder compact in the direction pressed in the press molding”×10 mm×40 mm from the metal powder compact. For example, when the metal powder compact has a cylindrical shape, the direction of the pressure applied during press molding can be determined to be the direction of the bottom surface pressed during press molding. If the pressure direction during press molding is unknown, it is assumed that the direction perpendicular to one surface of the metal powder compact is the pressure direction during press molding. Is cut out and the bending strength is measured. Also, regarding the direction perpendicular to the remaining surface of the metal powder compact, similarly, it is assumed that it is the direction in which pressure is applied during press molding, and the above-described test piece is cut out and the bending strength is measured. Then, the maximum value of the measured bending strength is set as the bending strength of the metal powder compact. The bending strength of the metal powder compact is more preferably 1.0 MPa or more, and particularly preferably 3.0 MPa or more. With this configuration, the shape retention of the metal powder compact can be improved. In the metal powder compact of the present embodiment, the metal powders are bound to each other by the binding force of the binder contained in the metal powder molding raw material, and the shape thereof is maintained. Therefore, the upper limit of the bending strength of the metal powder compact of this embodiment is about 5 to 10 MPa. The bending strength of the metal powder compact may change depending on the content ratio of the liquid contained in the metal powder compact. Therefore, when measuring the bending strength of the metal powder compact, the metal powder compact to be measured shall be dried after the following method. The metal powder compact to be measured is dried for 60 minutes or more in a dry atmosphere at 80° C. using a hot air dryer. By performing such drying, the ratio of the mass of the liquid in the metal powder compact to the mass of the metal powder compact is 1 mass% or less. Here, the liquid in the metal powder compact is a liquid such as a solvent contained in the metal powder compact when the metal powder compact is manufactured.

Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to these Examples.

(Example 1)
First, a metal powder molding raw material was manufactured by the following molding raw material manufacturing process. First, a metal powder and a carbon powder as another powder were mixed to prepare a raw material powder. Silicon (Si), which is hard and difficult to press-mold, was selected as the metal powder, and two types of silicon powder were used as the first metal powder and the second metal powder having different average particle diameters. Silicon (Si) powder having an average particle diameter of 500 μm was used as the first metal powder, and silicon (Si) powder having an average particle diameter of 15 μm was used as the second metal powder. The metal powder was prepared so as to contain 85 mass% of the first metal and 15 mass% of the second metal. As the carbon powder, a carbonaceous material having an average particle diameter of 50 μm and a density of 2.05 g/cc was used. The raw material powder was prepared by mixing 3 mass% of carbon powder with 100 mass% of metal powder. The average particle size of the metal powder is a value measured by the particle size analysis using the above-mentioned sieve and the laser diffraction method. Moreover, the value of the average particle diameter of the other powders is a value measured by a laser diffraction method. In the laser diffraction measurement, a laser diffraction type particle size distribution measuring device (product number: SALD-7100) manufactured by SHIMADZU was used.

Table 1 shows the type of the first metal powder, the average particle diameter (μm) of the first metal powder, the mass ratio of the first metal powder to the mass of the metal powder (mass %), and the second metal powder. , The average particle diameter (μm) of the second metal powder, and the ratio (mass %) of the mass of the second metal powder to the mass of the metal powder. In addition, Table 1 shows the types of other powders, the average particle diameter (μm) of the other powders, and the ratio (mass %) of the mass of the other powders to the mass of the raw material powder. In addition, the column of “ratio of mass of other powder (mass %)” in Table 1 shows “ratio of mass of other powder to mass of raw material powder (mass %)”. In Table 1, "Type of first metal powder" and "Type of second metal powder", when silicon powder is used as the metal powder, it is described as "Si". In the column of "other powder types" in Table 1, when carbon powder is used as the other powder, it is described as "C".

Next, to 100 parts by mass of the obtained raw material powder, 10 parts by mass of a binder containing a saccharide having 20 or less carbon atoms and a solvent was added, and mixed and kneaded using a mixer to prepare a metal powder molding raw material. Trehalose was used as the saccharide having 20 or less carbon atoms. Water was used as the solvent. The binder used in Example 1 contained 50 parts by mass of trehalose and 50 parts by mass of water with respect to 100 parts by mass of the binder.

Table 2 shows parts by mass (parts by mass) of the binder with respect to 100 parts by mass of the raw material powder. Table 2 shows the types of saccharides having 20 or less carbon atoms, the types of solvents, and the compounding recipes of binders. The compounding recipe of the binder is the ratio (mass parts) of the mass of each component in 100 parts by mass of the binder. The column of "Ratio of sugar to raw material powder (parts by mass)" in Table 2 shows "Ratio of mass of saccharide having 20 or less carbon atoms to mass of raw material powder (parts by mass)". The column of "binder (parts by mass)" in Table 2 shows "parts by mass of binder with respect to 100 parts by mass of raw material powder".

Next, a metal molded body made of a metal powder molding raw material was manufactured by the following molded body manufacturing process. First, the metal powder molding raw material was press-molded using a predetermined mold. After that, the press-molded metal powder forming raw material was taken out of the mold to produce a metal formed body. The press pressure applied to the metal powder forming raw material during press forming was 50 MPa. The shape of the space of the mold was a columnar shape, and press molding was performed so that the height of the columnar shape was 7 to 8 mm.

Table 3 shows the press pressure (MPa) applied to the metal powder forming raw material and the shape of the mold during press forming. In Table 3, the pressing pressure (MPa) applied to the metal powder forming raw material is expressed as "pressing pressure (MPa)". Regarding the shape of the mold space, the shape of the cylinder is A, the shape of the cylinder having a height of 7 to 8 mm is A, the shape of the cylinder having a height of 4 to 6 mm is B, and the height of the cylinder is 2 to 3 mm. A certain shape is designated as C.

(Mixability of metal powder forming materials)
With respect to the metal powder forming raw material produced in the forming raw material producing step, the mixing property of the metal powder forming raw material was evaluated based on the following criteria. The results are shown in Table 3. In Table 3, the miscibility of the metal powder forming raw material is described as "mixability". Hereinafter, the “mixability of the metal powder forming raw material” may be simply referred to as “mixability”. A Kenmix mixer (product number: KMM-770) manufactured by Aikosha Seisakusho was used for mixing the metal powder forming raw material and the binder in the following evaluation of the mixing property.
Evaluation A: "When the metal powder forming raw material and the binder are mixed for 5 minutes, and then the metal powder forming raw material is in a state of being uniformly mixed without lumps or non-uniformity of water content" Is evaluated as “A”.
Evaluation B: “When the metal powder forming raw material and the binder are mixed for 10 minutes, and then the metal powder forming raw material is in a state of being uniformly mixed without lumps or non-uniformity of water content” Is evaluated as “B”.
Evaluation C: "When mixing the metal powder forming raw material and the binder, after mixing for 10 minutes, the metal powder forming raw material was in a state in which lumps and moisture were not uniform and could not be mixed well. The case is defined as the evaluation “C”.

(Fluidity of metal powder forming material)
In the forming process of the formed body, the fluidity of the metal powder forming raw material was evaluated based on the following criteria. The results are shown in Table 3. In Table 3, the fluidity of the metal powder forming raw material is described as "fluidity". Hereinafter, the "fluidity of the metal powder forming raw material" may be simply referred to as "fluidity". A quadrangular pyramid-shaped hopper having an outlet of about 25 mm×about 80 mm and a capacity of about 10 L was used as the supply hopper in the evaluation of fluidity described below. Further, in the evaluation of fluidity below, "to form a bridge" means that "the particles of the metal powder forming raw material form an arch structure at the discharge port of the supply hopper, the discharge port is blocked, and the metal powder forming raw material is It is not discharged." Evaluation A: "When the metal powder forming raw material was supplied to the mold through the supply hopper without forming a bridge in the supply hopper, the metal powder forming raw material could be filled in the mold without delay" The evaluation is “A”.
Evaluation B: “When supplying the metal powder forming raw material to the mold through the supply hopper, a bridge may be formed in a part of the supply hopper, but the mold is filled with a uniform amount of the metal powder forming raw material. If it can be done", the evaluation is "B".
Evaluation C: “When supplying the metal powder forming raw material to the mold through the supply hopper, a bridge may be formed in a part of the inside of the supply hopper, and the metal powder forming raw material from the supply hopper appears unevenly. And the case where the amount of the metal powder forming raw material with which the mold is filled becomes non-uniform" is evaluated as "C".
Evaluation D: “When the movement of the metal powder forming raw material in the supply hopper is not good, the metal powder forming raw material does not come out of the supply hopper, and the metal powder forming raw material cannot be filled in the mold, that is, press forming is possible. If there is not," the evaluation is "D".

(Releasability of metal powder compact)
In the forming process of the formed body, the releasability of the formed metal powder body was evaluated based on the following criteria. The results are shown in Table 3. In Table 3, the releasability of the metal powder compact was described as "releasability". Hereinafter, the “releasability of the metal powder forming raw material” may be simply referred to as “releasability”.
Evaluation A: "When the metal powder forming raw material was not adhered to the inner surface of the mold after the mold release even after the metal powder forming raw material was continuously press-formed 10 times or more," was evaluated as "A". And Evaluation B: "When the metal powder forming raw material is adhered to the inner surface of the mold after release after the metal powder forming raw material is press-formed 5 times or more and less than 10 times continuously", the evaluation "B ". Evaluation C: "When the metal powder forming raw material is adhered to the inner surface of the mold after releasing from the mold after the metal powder forming raw material is continuously press-formed less than 5 times", the evaluation is "C". ..

(Bending strength of metal powder compact)
The bending strength of the obtained metal powder compact was evaluated based on the following criteria. The results are shown in Table 3. In Table 3, the "strength of the metal powder compact" obtained by the three-point bending test was described as "bending strength". The bending strength was measured by performing a destructive test by a three-point bending test using a material testing machine manufactured by Instron (model number: 5900 series). Further, the bending strength was measured by press-molding a metal powder molding raw material to obtain a metal powder molded body, taking out from the mold, and then drying the metal powder molded body using a hot air dryer. Next, a test piece having a size of 10 mm×40 mm×cylinder height was cut out from the cylindrical metal powder compact. Then, the height direction of the cylinder of the test piece (in other words, the pressing direction at the time of press molding) was set as the load application direction, and the three-point bending test was performed. The metal powder compact was dried for 60 minutes or more in a dry atmosphere at 80°C. Hereinafter, the "bending strength of the metal powder forming raw material" may be simply referred to as "bending strength".
Evaluation A: "When the measurement result of the bending strength is 3 MPa or more" is evaluated as "A".
Evaluation B: "When the measurement result of the bending strength is 0.5 MPa or more and less than 3 MPa" is evaluated as "B". In the evaluation “B”, the one having higher bending strength is evaluated as “B+”.
Evaluation C: "When the measurement result of bending strength is less than 0.5 MPa" is evaluated as "C". In addition, in the evaluation “C”, one having higher bending strength is evaluated as “C+”.
Evaluation D: "When the shape of the metal powder molded body after press molding is not determined and the bending strength cannot be measured" is evaluated as "D".

(Comprehensive evaluation)
A comprehensive evaluation of excellent, good, good and bad was made based on the following evaluation criteria from the evaluation results of the mixing property, the evaluation results of the fluidity, the evaluation results of the releasability, and the evaluation results of the bending strength. The results are shown in Table 3.
Evaluation "excellent": "When all the evaluation results of the four evaluation results of the mixing property, the fluidity, the releasability, and the bending strength are A or B and B is 2 or less", Evaluation is "excellent".
Evaluation “good”: “when all the evaluation results of the four evaluation results of the mixing property, the fluidity, the releasability, and the bending strength are A or B and B is 3 or more”, Evaluation is “good”.
Evaluation “OK”: “When all of the four evaluation results of the mixing property, the fluidity, the releasability, and the bending strength are A, B, or C, and C is one or more” Is evaluated as “OK”.
Evaluation “impossible”: “When D is one or more out of the four evaluation results of mixing property, fluidity, releasability, and bending strength”, the evaluation is “impossible”.

(Examples 2-6, 9-13, and 32-35)
In Examples 2 to 6, 9 to 13 and 32 to 35, metal powder compacts were produced in the same manner as in Example 1 except that the binder formulation was changed as shown in Table 2. ..

(Comparative Examples 1 to 3)
In Comparative Examples 1 to 3, metal powder compacts were produced in the same manner as in Example 1 except that the formulation of the binder was changed as shown in Table 2.

(Examples 7 and 8, and 14-16)
In Examples 7 and 8 and 14 to 16, metal powder compacts were prepared in the same manner as in Example 1 except that the formulation of the raw material powder and the formulation of the binder were changed as shown in Table 2. Was produced.

(Example 17)
In Example 17, a metal powder compact was prepared in the same manner as in Example 1 except that the raw material powder and the binder formulation were changed as follows. As the metal powder contained in the raw material powder, a tungsten (W) powder and a nickel (Ni) powder were used. Tungsten (W) powder having an average particle diameter of 0.5 μm was used as the first metal powder, and nickel (Ni) powder having an average particle diameter of 0.5 μm was used as the second metal powder. The raw material powder formulation and the binder formulation were as shown in Table 4 and Table 5, respectively. In addition, in the columns of "first metal powder" and "second metal powder" in Table 4, when tungsten and nickel powders are used as the metal powder, they are described as "W" and "Ni", respectively. To do.

(Examples 18 and 19)
In Examples 18 and 19, metal powder compacts were produced in the same manner as in Example 1, except that the formulation of the raw material powder and the binder were changed as follows. As the metal powder contained in the raw material powder, a powder of tungsten (W) and a powder of copper (Cu) were used. A tungsten (W) powder having an average particle diameter of 0.5 μm was used as the first metal powder, and a copper (Cu) powder having an average particle diameter of 1 μm was used as the second metal powder. The raw material powder formulation and the binder formulation were as shown in Table 4 and Table 5, respectively. In addition, in the column of “second metal powder” in Table 4, when copper powder is used as the metal powder, it is described as “Cu”.

(Examples 20 to 22)
In Examples 20 to 22, metal powder compacts were produced in the same manner as in Example 1 except that the press pressure applied to the metal powder molding raw material during press molding was changed as shown in Table 6, respectively. did. In addition, in Examples 20 to 22, there is no change in the formulation of the raw material powder and the formulation of the binder as compared with Example 1, but Table 4 shows the formulation of the raw material powder.

(Examples 23 to 25)
In Examples 23 to 25, a metal powder compact was prepared in the same manner as in Example 1 except that methylcellulose was used as the other component contained in the binder and the formulation of the binder was changed as shown in Table 5, respectively. Was produced. In addition, in Examples 23 to 27, the compounding recipe of the raw material powder is the same as that of Example 1, but the compounding recipe of the raw material powder is shown in Table 4.

(Comparative Examples 4 and 5)
In Comparative Examples 4 and 5, methylcellulose was used as the other component contained in the binder, and the formulation of the binder was changed as shown in Table 5, to obtain a metal powder compact in the same manner as in Example 1. It was made. It should be noted that in Comparative Example 1, the formulation of the raw material powder is the same as that of Example 1, but the formulation of the raw material powder is shown in Table 4.

(Example 26)
In Example 26, a metal powder compact was produced in the same manner as in Example 1 except that the mixed solvent A was used as the solvent and the formulation of the binder was changed as shown in Table 5. The mixed solvent A contained 50 mass% of water and 50 mass% of ethanol (purity: 99.5 mass% or more). In addition, in Example 26, the formulation of the raw material powder is the same as that of Example 1, but the formulation of the raw material powder is shown in Table 4.

(Example 27)
In Example 27, a metal powder compact was prepared in the same manner as in Example 1, except that the mixed solvent B was used as the solvent and the binder formulation was changed as shown in Table 5. The mixed solvent B contained 20 mass% of water and 80 mass% of ethanol (purity: 99.5 mass% or more). In addition, in Example 27, the compounding recipe of the raw material powder is the same as that of Example 1, but the compounding recipe of the raw material powder is shown in Table 4.

(Examples 28 to 31)
In Examples 28 to 31, the compounding formulation of the binder, the “pressing pressure applied to the metal powder forming raw material during press forming”, and the shape of the space of the mold were changed as shown in Table 5 and Table 6, respectively. A metal powder compact was prepared in the same manner as in Example 1 except for the above. In addition, in Examples 28 to 31, the compounding recipe of the raw material powder is the same as that of Example 1, but the compounding recipe of the raw material powder is shown in Table 4.

(Examples 36 to 38)
In Examples 36 to 38, metal powder compacts were produced in the same manner as in Example 1 except that the binder formulation was changed as shown in Table 5. In Example 36, erythritol was used as the saccharide having 20 or less carbon atoms. In Example 37, sorbitol was used as the saccharide having 20 or less carbon atoms. In Example 38, xylitol was used as the saccharide having 20 or less carbon atoms. Water was used as the solvent. The binder used in Examples 36 to 38 contained 50 parts by mass of each saccharide and 50 parts by mass of water with respect to 100 parts by mass of the binder. In addition, in Examples 36 to 38, the compounding recipe of the raw material powder is the same as that of Example 1, but the compounding recipe of the raw material powder is shown in Table 4. Hereinafter, Examples 36 to 38 are referred to as Reference Examples 36 to 38.

The metal powder compacts of Examples 2-38 and the metal powder compacts of Comparative Examples 1-5 were also evaluated for mixability, fluidity, releasability, and bending strength. The results are shown in Tables 3 and 6. In addition, when the metal powder forming raw material could not be supplied to the mold and the releasability and the bending strength could not be evaluated, "-" is shown in the corresponding column.

(result)
As shown in Tables 3 and 6, the metal powder compacts of Examples 1 to 38 were able to obtain good results in the comprehensive evaluation. In particular, when Examples 1 to 6 and 32 to 35 are compared, Examples 3, 4, 6, and 32 to 34 in which the amount of the binder compounded is 3.5 to 7.5 parts by mass are mixed and flowable. , And releasability were all evaluated as “A”. Regarding the evaluation of the bending strength, when the binder content is 5.1 to 20 parts by mass, the evaluation is "B" or more, and when the binder content is 5.5 to 20 parts by mass, The evaluation was "B+" or higher. Further, as in Examples 36 to 38, even when erythritol, sorbitol, and xylitol are used as the saccharide having 20 or less carbon atoms, good results can be obtained as in the case of using trehalose. It was Particularly good results were obtained in terms of fluidity when erythritol was used.

The metal powder compact of Comparative Example 1 had more than 20 parts by mass of the binder with respect to 100 parts by mass of the raw material powder, so that the comprehensive evaluation was not possible.

In the metal powder molded body of Comparative Example 2, the binder did not contain saccharides having 20 or less carbon atoms, and thus was unacceptable in the comprehensive evaluation.

In the metal powder molded body of Comparative Example 3, the binder did not contain a solvent, so that the comprehensive evaluation was not possible.

In the metal powder compacts of Comparative Examples 4 and 5, the binder contained methylcellulose as the other component, but it did not contain the saccharides having 20 or less carbon atoms, and thus was unacceptable in the comprehensive evaluation.

The method for producing a metal powder compact of the present invention can be used as a method for producing a metal powder compact excellent in shape retention. Further, the metal powder compact of the present invention can be used as a metal compact containing various metals.

1: Metal powder compact.

Claims (14)

A forming raw material producing step of producing a metal powder forming raw material by mixing and kneading a raw material powder containing 10 mass% or more of metal powder and a binder;
A forming step of forming the metal powder forming material by press forming the metal powder forming material,
As the binder, at least a saccharide having 20 or less carbon atoms and a solvent are used, and in the forming raw material preparing step, 3.5 to 20 parts by mass of the binder is added to 100 parts by mass of the raw material powder to obtain the metal powder. A method for producing a metal powder compact, which comprises producing a forming raw material ,
The method for producing a metal powder compact, wherein the saccharide having 20 or less carbon atoms is trehalose . The method for producing a metal powder compact according to claim 1, wherein the ratio of the mass of the saccharide having 20 or less carbon atoms in the binder (100 parts by mass) is 20 to 80 parts by mass. The method for producing a metal powder compact according to claim 1, wherein the ratio of the mass of the solvent in 100 parts by mass of the binder is 20 to 80 parts by mass. The method for producing a metal powder compact according to any one of claims 1 to 3, wherein the saccharide having 20 or less carbon atoms is used in a solid state in the forming raw material preparing step. The raw material powder comprises carbon powder, method for producing a metal powder compact according to any one of claims 1-4. The method for producing a metal powder compact according to claim 5 , wherein the carbon powder is less than 15 parts by mass with respect to 100 parts by mass of the raw material powder. In the compact preparation step, the press pressure applied to the metal powder forming material are 5～200MPa, method for producing a metal powder compact according to any one of claims 1-6. The metal powder is fine metal particles having a particle diameter of 10 to 1000 nm, coarse metal particles having a particle diameter of 100 to 1000 μm, or fine metal particles having a particle diameter of 10 to 1000 nm and coarse metal having a particle diameter of 100 to 1000 μm. containing particles as a main raw material, method for producing a metal powder compact according to any one of claims 1-7. The metal powder is at least one kind selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, tantalum, niobium, titanium, and magnesium. a powder containing a metal, a manufacturing method of the metal powder compact according to any one of claims 1-8. It consists of a molded body that is formed by press molding a molding raw material.
The molded body contains a raw material powder containing 10 mass% or more of metal powder, and a binder containing a saccharide having 20 or less carbon atoms,
A metal powder compact, containing 0.7 to 16 parts by mass of the saccharide having 20 or less carbon atoms, relative to 100 parts by mass of the raw material powder ,
A metal powder compact, wherein the saccharide having 20 or less carbon atoms is trehalose . The metal powder compact according to claim 10 , wherein the raw material powder contains carbon powder. The metal powder compact according to claim 11 , wherein the carbon powder is less than 15 parts by mass with respect to 100 parts by mass of the raw material powder. The metal powder is fine metal particles having a particle diameter of 10 to 1000 nm, coarse metal particles having a particle diameter of 100 to 1000 μm, or fine metal particles having a particle diameter of 10 to 1000 nm and coarse metal having a particle diameter of 100 to 1000 μm. containing particles as a main raw material, a metal powder molded body according to any one of claims 10-12. The metal powder is at least one kind selected from the group consisting of silicon, molybdenum, tungsten, beryllium, chromium, iron, aluminum, nickel, manganese, silver, copper, vanadium, cobalt, tantalum, niobium, titanium, and magnesium. The metal powder compact according to any one of claims 10 to 14 , which is a powder containing a metal.

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