Combination of lubricants, powder mixture, combination of raw materials for powder mixture, and method for producing sintered compact

Abstract

To provide: a combination of lubricants capable of improving extractability of a compact and further capable of producing a sintered compact with suppressed poor appearance; a powder mixture containing the combination of the lubricants and a combination of raw materials for powder mixture; and a method for producing a sintered compact using the powder mixture or the combination of the raw materials for powder mixture.SOLUTION: A combination of lubricants comprises a lubricant A having a melting point of 60°C to 85°C and a metal soap-based lubricant B. When sieved using a JIS standard sieve, a proportion of particles having a particle size of 63 μm or less is 88 mass% or more relative to a total amount of the combination of the lubricants.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a combination of lubricants, a powder mixture, a combination of raw materials for the powder mixture, and a method for manufacturing a sintered body.

Background Art

[0002] Generally, lubricants are used for lubrication, for example, to reduce the friction between solids in contact with each other. Examples of lubricants include liquid lubricating oils, semi-solid greases, solid lubricants, etc. For example, in powder metallurgy, solid lubricants in powder form (powder lubricants) are used.

[0003] Among powder metallurgy methods, particularly in die forming, in order to reduce the friction between the die wall surface and the compacted powder, a powder mixture in which a powder lubricant is usually mixed into the raw material powder is used. The powder mixture is obtained by mixing a powder of a secondary raw material such as copper powder, graphite powder, powder for improving machinability, etc. and a powder of a lubricant with an iron-based powder as the main raw material powder.

[0004] When the powder mixture contains a powder lubricant, powder characteristics such as fluidity and compactibility in the powder mixture are improved, and it becomes easier to extract the compression-molded compact from the die. Examples of the powder lubricant include metal soap-based lubricants such as stearic acid and its metal salts, organic lubricants (wax-based lubricants), and fatty acid amide-based lubricants (see, for example, Patent Documents 1 and 2).

[0005] The lubricant is selected in consideration of its miscibility with the metal powder, powder characteristics when made into a powder mixture, extractability of the compact after compression molding, dissipation of the lubricant when sintering the compact, etc. Among these, zinc stearate is widely used as a lubricant from the viewpoints of relatively excellent lubricating characteristics and cost. Such a lubricant is generally used by being previously mixed into the powder mixture. Although there is also a method of applying the lubricant to the die wall surface, since a special device is required, the manufacturing cost of the sintered body becomes relatively high.

[0006] However, metal soap-based lubricants typified by zinc stearate have a problem of contaminating the product surface, exhaust ducts, etc. when sintering the compact powder, and thus replacement with organic lubricants (wax-based lubricants) is desired. As organic lubricants, in addition to the lubricants described in Patent Documents 1 and 2, amide compounds having a long-chain alkyl group have been proposed (see, for example, Patent Document 3).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] When a powder mixture added with a lubricant is compression-molded using a mold, it is desirable that the molded body can be easily removed from the mold, that is, the molded body has excellent extractability. Regarding the sintered body formed by sintering the molded body, unevenness is likely to be formed on its surface, so it is desirable that appearance defects can be suppressed.

[0009] The present disclosure aims to provide a combination of lubricants capable of improving the extractability of a molded body and further manufacturing a sintered body with suppressed appearance defects, a powder mixture containing the combination of lubricants and a combination of raw materials for the powder mixture, and a method for manufacturing a sintered body using the powder mixture or the combination of raw materials for the powder mixture.

Means for Solving the Problems

[0010] Specific means for achieving the above problems are as follows. <1> Lubricant A having a melting point of 60°C to 85°C, and a metal soap-based lubricant B, and, a combination of lubricants in which, when sieved using a JIS standard sieve, the proportion of particles having a particle diameter of 63 μm or less is 88% by mass or more based on the total amount of the combination of lubricants. <2> The lubricant A according to <1> above contains at least one selected from the group consisting of oleic acid amide, erucic acid amide, ricinoleic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, N-oleyl-hydroxy stearic acid amide, stearic acid, and N-oleyl palmitoamide. The combination of lubricants described in <1>. <3> The metal soap-based lubricant B according to <1> or <2> above contains a metal salt of a fatty acid having 12 to 22 carbon atoms and at least one metal selected from the group consisting of lithium, magnesium, calcium, barium, zinc, and strontium. The combination of lubricants described in <1> or <2>. <4> The proportion of particles that do not pass through the sieve when sieved with a JIS standard sieve having an opening of 150 μm is 5% by mass or less based on the total amount of the lubricant. The combination of lubricants described in any one of <1> to <3>. <5> The combination of lubricants according to any one of <1> to <4> above, further comprising a lubricant C that is a fatty acid bisamide. <6> The melting point of the lubricant C according to <5> above is 140°C or higher and less than 150°C. The combination of lubricants described in <5>. <7> The lubricant C includes at least one selected from the group consisting of methylene bisstearic acid amide, methylene bislauric acid amide, methylene bishydroxystearic acid amide, ethylene biscaprylic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, butylene bishydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, methylene bisoleic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, m-xylylene bisstearic acid amide, and N,N'-distearyl isophthalic acid amide, and is the combination of lubricants according to <5>. <8> A powder mixture including a raw material powder and the combination of lubricants according to any one of <1> to <7>. <9> A combination of raw materials for a powder mixture including a raw material powder and the combination of lubricants according to any one of <1> to <7>. <10> A method for manufacturing a sintered body by sintering a powder mixture obtained from the powder mixture according to <8> or the combination of raw materials for the powder mixture according to <9>.

Advantages of the Invention

[0011] According to the present disclosure, it is possible to provide a combination of lubricants capable of improving the extractability of a molded body and further manufacturing a sintered body with suppressed appearance defects, a powder mixture including the combination of lubricants, a combination of raw materials for the powder mixture, and a method for manufacturing a sintered body using the powder mixture or the combination of raw materials for the powder mixture.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the lubricant combination, powder mixture, combination of raw materials for the powder mixture, and manufacturing method of the sintered body of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present invention. In the present disclosure, the numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value of the numerical range described in other stepwise descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, each component may contain a plurality of corresponding substances. When there are a plurality of substances corresponding to each component, the content rate or content of each component means the total content rate or content of the plurality of substances, unless otherwise specified. In the present disclosure, the particles corresponding to each component may contain a plurality of types. When there are a plurality of types of particles corresponding to each component, the particle size of each component means the value for the mixture of the plurality of types of particles, unless otherwise specified.

[0013] [Lubricant combination] The lubricant combination of the present disclosure includes lubricant A having a melting point of 60°C to 85°C and metal soap-based lubricant B, and when sieved using a JIS standard sieve, the proportion of particles having a particle size of 63 μm or less is 88% by mass or more based on the total amount of the lubricant combination.

[0014] By using the lubricant combination of the present disclosure, the extractability of the molded body can be improved, and furthermore, a sintered body with suppressed appearance defects can be manufactured. More specifically, the lubricant combination of the present disclosure includes a lubricant A with a relatively low melting point, which makes it easier to extract the molded body from the mold, that is, the extractability of the molded body tends to be improved. Furthermore, when sieved, the proportion of particles with a particle size of 63 μm or less is 88% by mass or more based on the total amount of the lubricant. Thereby, in the sintered body obtained by sintering the molded body, a sintered body with reduced surface unevenness and suppressed appearance defects can be manufactured.

[0015] Using lubricant A tends to slightly reduce the fluidity of the powder mixture. By combining lubricant A with a metal soap-based lubricant B, the fluidity of the powder mixture can be greatly enhanced. Therefore, in the lubricant combination of the present disclosure, the fluidity of the powder mixture tends to be good. By using lubricant A and the metal soap-based lubricant B in combination, the amount of the metal soap-based lubricant B used can be reduced.

[0016] The lubricant combination of the present disclosure is preferably used, for example, for powder metallurgy. The lubricant combination of the present disclosure may also be used for applications other than powder metallurgy.

[0017] In the lubricant combination of the present disclosure, when sieved using a JIS standard sieve, the proportion of particles with a particle size of 63 μm or less is 88% by mass or more based on the total amount of the lubricant combination. Thereby, in the sintered body obtained by sintering the molded body, a sintered body with reduced surface unevenness and suppressed appearance defects can be manufactured. In the present disclosure, the proportion of particles with a particle size less than a specific particle size (for example, 63 μm or less) is the proportion of particles passing through the sieve when the lubricant is sieved with a JIS standard sieve having a mesh opening of the specific particle size (for example, 63 μm).

[0018] When sieving using a JIS standard sieve, the proportion of particles with a particle size of 63 μm or less may be 90% by mass or more, 95% by mass or more, or 100% by mass, from the viewpoint of suitably suppressing appearance defects of the sintered body, based on the total amount of the lubricant combination.

[0019] The particle size serving as the sieving criterion is not limited to 63 μm or less, and may be 50 μm or less, or 43 μm or less. For example, the proportion of particles with a particle size of 50 μm or less may be 88% by mass or more, 90% by mass, 95% by mass or more, or 100% by mass, based on the total amount of the lubricant. The proportion of particles with a particle size of 43 μm or less may be 88% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass, based on the total amount of the lubricant.

[0020] The JIS standard sieve complies with JIS-Z-8801-1:2006 and corresponds to ISO3310-1:2000. When using ISO3310-1:2000, it is preferable to apply a sieve with a square mesh shape similar to JIS-Z-8801-1:2006.

[0021] In the lubricant combination of the present disclosure, the proportion of particles that do not pass through a JIS standard sieve with an aperture of 150 μm (preferably 100 μm, more preferably 80 μm) is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, based on the total amount of the lubricant combination, from the viewpoint of suitably suppressing appearance defects of the sintered body. The proportion of the aforementioned particles may be 0% by mass, or may be 0.5% by mass or more, based on the total amount of the lubricant combination.

[0022] When the lubricant combination of the present disclosure consists of lubricant A and a metal soap-based lubricant B, when sieved using a JIS standard sieve, the proportion of particles with a particle size of 63 μm or less may be 88% by mass or more based on the total amount of lubricant A and the metal soap-based lubricant B. When the lubricant combination of the present disclosure consists of lubricants such as lubricant A, a metal soap-based lubricant B, and lubricant C described later, when sieved using a JIS standard sieve, the proportion of particles with a particle size of 63 μm or less may be 88% by mass or more based on the total amount of lubricant A, the metal soap-based lubricant B, and lubricant C described later.

[0023] In the present disclosure, the lubricant combination may be a mixture of lubricants containing at least lubricant A and a metal soap-based lubricant B, or may be a combination of a lubricant containing lubricant A and a lubricant containing a metal soap-based lubricant B prepared without mixing them. For example, in the case of a combination of a lubricant containing lubricant A and a lubricant containing a metal soap-based lubricant B prepared without mixing them, when manufacturing a powder mixture, the lubricant containing lubricant A and the lubricant containing a metal soap-based lubricant B may be mixed. If necessary, a lubricant such as lubricant C described later may be added to the mixture. A lubricant containing lubricant C or the like may be prepared without mixing it with a lubricant containing lubricant A and a lubricant containing a metal soap-based lubricant B.

[0024] (Lubricant A) The lubricant combination of the present disclosure contains a lubricant A having a melting point of 60°C to 85°C. The lubricant combination may contain one type of lubricant A or may contain two or more types of lubricant A. In the present disclosure, the melting point is a value measured by differential scanning calorimetry (DSC).

[0025] Lubricant A preferably contains at least one selected from the group consisting of oleic acid amide, erucic acid amide, ricinoleic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, N-oleyl-hydroxy stearic acid amide, stearic acid, and N-oleyl palmitoamide, and more preferably contains at least one selected from the group consisting of oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid, and N-oleyl palmitoamide. Among them, from the viewpoint of the extractability of the molded body, it is more preferable to contain at least one of erucic acid amide and oleic acid amide.

[0026] The content of Lubricant A may be 10% by mass to 90% by mass, 20% by mass to 70% by mass, or 30% by mass to 50% by mass with respect to the total amount of the lubricant combination.

[0027] (Metal soap-based lubricant B) The lubricant combination of the present disclosure contains a metal soap-based lubricant B. The lubricant combination may contain one kind of metal soap-based lubricant B or may contain two or more kinds of metal soap-based lubricants B.

[0028] Examples of the metal soap-based lubricant B include metal salts of fatty acids having 12 to 22 carbon atoms and at least one metal selected from the group consisting of lithium, magnesium, calcium, barium, zinc, and strontium.

[0029] The fatty acid having 12 to 22 carbon atoms may be a saturated fatty acid having 12 to 22 carbon atoms or an unsaturated fatty acid having 12 to 22 carbon atoms. The number of carbon atoms in the fatty acid may be 16 to 20 or 16 to 18.

[0030] Examples of fatty acids having 12 to 22 carbon atoms include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid, and unsaturated fatty acids such as linoleic acid, linolenic acid, oleic acid, and erucic acid.

[0031] Specific examples of the metal soap-based lubricant B include lithium stearate, calcium stearate, barium stearate, zinc stearate, and the like.

[0032] The content of the metal soap-based lubricant B may be 1% by mass to 90% by mass, 10% by mass to 90% by mass, 30% by mass to 80% by mass, or 50% by mass to 70% by mass with respect to the total amount of the lubricant combination.

[0033] From the viewpoint of the balance between the fluidity of the powder mixture and the extractability of the molded body, the mass ratio of lubricant A to metal soap-based lubricant B, which is lubricant A:metal soap-based lubricant B, is preferably 1:9 to 9.9:0.1, more preferably 1:9 to 9:1, still more preferably 2:8 to 8:2, and particularly preferably 3:7 to 7:3.

[0034] (Lubricant C) The lubricant combination of the present disclosure may contain a lubricant C that is a fatty acid bisamide. The lubricant combination may contain one type of lubricant C or two or more types of lubricant C.

[0035] The melting point of the lubricant C may be 140°C or higher and less than 150°C, or 140°C or higher and 148°C or lower.

[0036] Examples of lubricant C include methylene bisstearic acid amide, methylene bislauric acid amide, methylene bishydroxystearic acid amide, ethylene biscaprylic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, butylene bishydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, methylene bisoleic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, m-xylylene bisstearic acid amide, and N,N'-distearyl isophthalic acid amide. Among them, from the viewpoint of the fluidity of the powder mixture, lubricant C more preferably contains ethylene bisstearic acid amide.

[0037] When the lubricant combination includes lubricant A, metal soap-based lubricant B, and lubricant C, in terms of the balance between the fluidity of the powder mixture and the extractability of the molded body, a preferred combination of lubricant A, metal soap-based lubricant B, and lubricant C is that lubricant A is at least one selected from the group consisting of erucic acid amide and oleic acid amide, metal soap-based lubricant B is zinc stearate, and lubricant C is preferably ethylene bisstearic acid amide.

[0038] The content of lubricant C may be 1% by mass to 90% by mass, 10% by mass to 90% by mass, 30% by mass to 80% by mass, or 50% by mass to 70% by mass based on the total amount of the lubricant combination.

[0039] The mass ratio of lubricant A to lubricant C, i.e., lubricant A:lubricant C, is preferably from 1:9 to 9.9:0.1, more preferably from 1:9 to 9:1, still more preferably from 2:8 to 8:2, and particularly preferably from 3:7 to 7:3, from the viewpoint of the balance between the fluidity of the powder mixture and the extractability of the molded body.

[0040] The mass ratio of lubricant A to the total of metal soap-based lubricant B and lubricant C, i.e., lubricant A:the total of metal soap-based lubricant B and lubricant C, is preferably from 1:9 to 9:1, more preferably from 2:8 to 8:2, and still more preferably from 3:7 to 7:3, from the viewpoint of the balance between the fluidity and consolidation of the powder mixture and the extractability of the molded body. The mass ratio of metal soap-based lubricant B to lubricant C, i.e., metal soap-based lubricant B:lubricant C, is preferably from 1:9 to 9:1, more preferably from 2:8 to 8:2, and still more preferably from 3:7 to 7:3, from the viewpoint of the balance between the fluidity and consolidation of the powder mixture and the extractability of the molded body.

[0041] The total content of lubricant A, metal soap-based lubricant B, and lubricant C (if any) with respect to the total amount of the lubricant combination is preferably 50% by mass to 100% by mass. Further, the total content of lubricant A, metal soap-based lubricant B, and lubricant C (if any) may be 60% by mass to 95% by mass, or may be 80% by mass to 90% by mass.

[0042] (Other lubricants) The lubricant combination of the present disclosure may contain other lubricants other than lubricant A, metal soap-based lubricant B, and lubricant C. Examples of lubricants other than lubricant A include fatty acid amides having a melting point exceeding 85°C. When using other lubricants, one type may be used alone, or two or more types may be used in combination.

[0043] Examples of fatty acid amides having a melting point exceeding 85°C include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, N-lauryl lauric acid amide, N-palmityl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl-hydroxystearic acid amide, and the like.

[0044] The content of other lubricants with respect to the total amount of the lubricant combination may be more than 0% by mass and 50% by mass or less, may be 5% by mass to 40% by mass, or may be 10% by mass to 20% by mass.

[0045] 〔Powder mixture〕 The powder mixture of the present disclosure includes a raw material powder and the aforementioned lubricant combination of the present disclosure. By using this powder mixture, the extractability of the molded body can be improved, and furthermore, a sintered body with suppressed appearance defects can be manufactured. The powder mixture of the present disclosure is preferably used, for example, for powder metallurgy.

[0046] Examples of the raw material powder include a main raw material powder containing iron as a main component, and a sub-raw material powder for improving the characteristics of the sintered body. Note that containing iron as a main component means that the iron content in the raw material powder is 50% by mass or more of the entire raw material powder.

[0047] Examples of the main raw material powder include iron-based powders such as pure iron powder and iron-based alloy powders that may contain inevitable impurities (oxygen, silicon, carbon, manganese, etc.). The main raw material powder may be used alone or in combination of two or more.

[0048] The average particle diameter of the main raw material powder is preferably 30 μm to 150 μm, and more preferably 50 μm to 100 μm. In the present disclosure, the average particle diameter is the particle diameter (D50) at which the cumulative value from the small-diameter side becomes 50% in the volume-based particle size distribution measured by the laser diffraction method.

[0049] The iron-based powder can be produced, for example, by atomizing molten iron or a molten iron alloy into fine particles, reducing the fine particles, and then pulverizing them.

[0050] The auxiliary raw material powder is not particularly limited as long as it is a raw material powder that can improve the characteristics of the sintered body, and examples include powders that improve the mechanical properties such as the hardness and toughness of the sintered body, powders that enhance the machinability of the sintered body, and the like.

[0051] Examples of the auxiliary raw material powder include metal powders and inorganic powders other than the main raw material powder. The auxiliary raw material powder may be used alone or in combination of two or more.

[0052] Examples of the metal powder include powders of copper, nickel, chromium, molybdenum, tin, vanadium, manganese, and the like.

[0053] Examples of the inorganic powder include sulfides such as manganese sulfide and manganese disulfide; nitrides such as boron nitride; oxides such as boric acid, magnesium oxide, potassium oxide, and silicon oxide; graphite such as natural graphite and artificial graphite; phosphorus; sulfur; and the like.

[0054] The average particle size of the auxiliary raw material powder is preferably 2 μm to 100 μm, and more preferably 5 μm to 50 μm.

[0055] Among 100 parts by mass of the raw material powder, the content of the main raw material powder is preferably 90 parts by mass to 99 parts by mass, and more preferably 95 parts by mass to 98 parts by mass.

[0056] Among 100 parts by mass of the raw material powder, the content of the auxiliary raw material powder is preferably 1 part by mass to 10 parts by mass, and more preferably 2 parts by mass to 5 parts by mass.

[0057] With respect to 100 parts by mass of the raw material powder, the content of the combination of lubricants is preferably 0.1 part by mass to 2.0 parts by mass, more preferably 0.2 part by mass to 1.5 parts by mass, and even more preferably 0.3 part by mass to 1.0 part by mass.

[0058] (Other components) The powder mixture of the present disclosure may contain other components other than the raw material powder and the lubricant of the present disclosure. Examples of other components include binders. By including a binder in the powder mixture, segregation, scattering, etc. of the raw material powder can be suppressed.

[0059] The binder is not particularly limited, and examples thereof include polyolefins, acrylic resins, polystyrenes, styrene-butadiene rubbers, ethylene glycol distearates, epoxy resins, rosin esters, and the like.

[0060] When the powder mixture of the present disclosure contains a binder, the content of the binder is preferably 0.01 parts by mass to 1.0 parts by mass, and more preferably 0.1 parts by mass to 1.0 parts by mass, based on 100 parts by mass of the raw material powder.

[0061] The powder mixture of the present disclosure is obtained by mixing the raw material powder, the combination of the lubricants of the present disclosure, and, if necessary, other components. The mixing of the raw material powder and the combination of the lubricants of the present disclosure can be performed using commonly used mixers such as a paddle mixer, a V-shaped mixer, and a double conical mixer (W-cone).

[0062] The combination of raw materials for the powder mixture of the present disclosure includes the raw material powder and the combination of the lubricants of the present disclosure. The combination of raw materials for the powder mixture of the present disclosure may be a mixture of the combination of the raw material powder and the lubricant. Alternatively, it may be a combination of the raw material powder and the combination of the lubricants of the present disclosure prepared without mixing, and the raw material powder and the combination of the lubricants of the present disclosure may be mixed and used when manufacturing the molded body. The preferred conditions of the combination of raw materials for the powder mixture of the present disclosure are the same as those of the powder mixture of the present disclosure described above, and thus the description thereof is omitted.

[0063] 〔Method for manufacturing a sintered body〕 The method for manufacturing a sintered body of the present disclosure is a method for manufacturing a sintered body by sintering a powder mixture obtained from the powder mixture of the present disclosure described above or a combination of raw materials for the powder mixture of the present disclosure described above. The method for manufacturing a sintered body of the present disclosure preferably includes filling a powder mixture into a mold, compression molding the powder mixture filled in the mold to form a molded body, and sintering the molded body taken out of the mold.

[0064] In the method for manufacturing a sintered body of the present disclosure, by using the powder mixture described above, the extractability of the molded body can be improved, and furthermore, a sintered body with suppressed appearance defects can be manufactured.

[0065] In the method for manufacturing a sintered body of the present disclosure, the powder mixture filled in the mold may be compression molded. The molding temperature, molding pressure, etc. are not particularly limited, and may be appropriately adjusted according to the composition, addition amount of the powder mixture, shape in the mold, etc.

[0066] In the method for manufacturing a sintered body of the present disclosure, a sintered body is manufactured by sintering a powder mixture, and preferably a sintered body is manufactured by sintering a molded body taken out of a mold. The conditions for sintering the powder mixture or the molded body are not particularly limited, and an ordinary sintering method can be adopted.

Examples

[0067] Hereinafter, the present disclosure will be described in more detail based on examples. It should be noted that the present invention is not limited by the following examples.

[0068] [Examples 1 to 50 and Comparative Examples 1 to 120] As the main raw material powder, atomized iron powder for powder metallurgy with an average particle size of 75 μm was prepared. As the secondary raw material powder, electrolytic copper powder with an average particle size of 30 μm and graphite powder with an average particle size of 10 μm were prepared. Next, 0.8 parts by mass of a lubricant mixture of lubricant A and metal soap-based lubricant B (referred to as "lubricant B" in the table) shown in Tables 1 to 3 and below, or a lubricant mixture of lubricant A, metal soap-based lubricant B, and lubricant C was added to 97.5 parts by mass of iron powder, 1.5 parts by mass of copper powder, and 1.0 part by mass of graphite powder. In each example and each comparative example, a lubricant mixture in which the ratio of particles with a particle size of 63 μm or less was the numerical value shown in Tables 1 to 3 with respect to the total amount of the lubricant was used when sieving using a JIS standard sieve. The ratios of lubricant A, metal soap-based lubricant B, and lubricant C in each example and each comparative example are as shown in Tables 1 to 3. Then, the mixture of the raw material powder and the lubricant was put into a V-type mixer and mixed for 30 minutes to obtain the powder mixtures of each example and each comparative example. <Lubricant A> Erucamide (melting point: 78°C to 81°C) Oleamide (melting point: 75°C) <Metal soap-based lubricant B (referred to as lubricant B in the table)> Zinc stearate <Lubricant C> Ethylene bisstearamide (melting point: 145°C)

[0069] (Flowability of the powder mixture) The flowability of the powder mixtures obtained in each example and each comparative example was evaluated by the fluidity test method specified in JIS Z 2502 (2012). The evaluation criteria are as follows. - Evaluation criteria - A The powder mixture flowed within 30 seconds. B The powder mixture flowed after more than 30 seconds and within 35 seconds. C The powder mixture did not flow, or the powder mixture flowed after more than 35 seconds. The results are shown in Tables 1 to 3. If the evaluation is A or B, the flowability of the powder mixture is good.

[0070] (Consolidation of the powder mixture) The evaluation of the compactibility of the powder mixtures obtained in each example and each comparative example was carried out based on the following criteria after supplying 7 g of the powder mixture into a mold and then forming a cylindrical compact with a diameter of 11.3 mm at a forming pressure of 700 MPa. - Evaluation Criteria - A The density of the cylindrical compact was 7.10 g / cm 3 or more. B The density of the cylindrical compact was 7.06 g / cm 3 or more and less than 7.10 g / cm 3 - Evaluation Criteria - C The density of the cylindrical compact was less than 7.06 g / cm 3 - Evaluation Criteria - The results are shown in Tables 1 to 3. If the evaluation is A or B, the compactibility of the powder mixture is good.

[0071] (Ejectability of the Cylindrical Compact) The ejectability of the cylindrical compacts in each example and each comparative example was evaluated based on the following criteria by measuring the ejection pressure when extracting the cylindrical compact used for the evaluation of the compactibility of the above-mentioned powder mixture from the mold. - Evaluation Criteria - A The ejection pressure was 8 MPa or less. B The ejection pressure was more than 8 MPa and 15 MPa or less. C The ejection pressure was more than 15 MPa. The results are shown in Tables 1 to 3. If the evaluation is A or B, the ejectability of the cylindrical compact is good.

[0072] (Evaluation of Appearance) The evaluation of the appearance in each example and each comparative example was carried out based on the following criteria by visually checking the surface of the sintered body obtained by firing the cylindrical compact used for the evaluation of the compactibility of the above-mentioned powder mixture in nitrogen at about 1100 °C. - Evaluation Criteria - A No roughness due to surface unevenness was observed on the surface of the sintered body. C Roughness due to surface unevenness was observed on the surface of the sintered body. The results are shown in Tables 1 to 3. If the evaluation is A, the appearance of the sintered body is good.

[0073]

Table 1

[0074]

Table 2

[0075]

Table 3

[0076] As shown in Tables 1 to 3, by using the powder mixtures of Examples 1 to 36, it was possible to produce a sintered body having excellent extractability of the molded body and suppressed appearance defects.

[0077] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. a lubricant A with a melting point of 60°C to 85°C, and a metal soap-based lubricant B, and when sieved using a JIS standard sieve, the proportion of particles with a particle size of 63 μm or less is 88% by mass or more based on the total amount of the lubricant combination. A lubricant combination.

2. The lubricant combination according to Claim 1, wherein the lubricant A contains at least one selected from the group consisting of oleic acid amide, erucic acid amide, ricinoleic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, N-oleyl-hydroxy stearic acid amide, stearic acid, and N-oleyl palmitoamide.

3. The lubricant combination according to Claim 1 or Claim 2, wherein the metal soap-based lubricant B contains a metal salt of a fatty acid having 12 to 22 carbon atoms and at least one metal selected from the group consisting of lithium, magnesium, calcium, barium, zinc, and strontium.

4. The lubricant combination according to any one of Claims 1 to 3, wherein the proportion of particles that do not pass through the sieve when sieved with a JIS standard sieve having a mesh opening of 150 μm is 5% by mass or less based on the total amount of the lubricant.

5. The lubricant combination according to any one of Claims 1 to 4, further comprising a lubricant C that is a fatty acid bisamide.

6. The lubricant combination according to Claim 5, wherein the melting point of the lubricant C is 140°C or higher and less than 150°C.

7. The lubricant C includes at least one selected from the group consisting of methylene bisstearic acid amide, methylene bislauric acid amide, methylene bishydroxystearic acid amide, ethylene biscaprylic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, butylene bishydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, methylene bisoleic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, m-xylylene bisstearic acid amide, and N,N'-distearyl isophthalic acid amide. The combination of lubricants according to claim 5.

8. A powder mixture comprising a raw material powder and the combination of lubricants according to any one of claims 1 to 7.

9. A combination of raw material for a powder mixture comprising a raw material powder and the combination of lubricants according to any one of claims 1 to 7.

10. A method for producing a sintered body by sintering a powder mixture obtained from the powder mixture according to claim 8 or the combination of raw materials for a powder mixture according to claim 9.

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