JP2013204050A - Method for producing metal sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily produce a metal sintered compact having high mechanical strength, by removing an oxide coating of a metal powder by the thermal decomposition of a flux agent, thereby facilitating sintering.SOLUTION: In a production treatment of a metal sintered compact, a mixture is prepared by mixing a metal powder, a flux agent and a binder resin (Step S11), and then, a molding is obtained by extrusion-molding the mixture (Step S13), and the molding is heated to a sintering temperature of the metal powder (Step S16). In that treatment, an oxide coating of the metal powder is removed by the thermal decomposition of the flux agent, thereby: facilitating sintering; and easily producing the metal sintered compact having high mechanical strength.

Description

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

  As a technique for molding a metal material, hot extrusion molding has been conventionally performed. In hot extrusion molding, it is possible to produce a rod-like or cylindrical long member. In Patent Document 1, a mixture obtained by mixing a metal powder and a water-soluble pore-forming medium powder is molded by hot extrusion, and the molded product is immersed in water to dissolve and remove the pore-forming medium from the molded product. A technique for obtaining the above is disclosed. In the stretched molded product, a large number of continuous pores each extending in the extrusion direction are formed.

  Patent Document 2 discloses a method for producing a porous metal sintered body. A sheet-like molded body containing a pore-forming material, a metal powder, and a binder resin, which are polyhydroxyalkanoate particles, is disclosed. After forming and heating the molded body above the decomposition temperature of the pore-forming material to thermally decompose the pore-forming material, the molded body is sintered at a sintering temperature higher than the heating temperature, thereby forming a porous metal A sintered body is produced.

International Publication WO2006 / 089773 JP 2006-124833 A

  By the way, when forming by hot extrusion as in Patent Document 1, since a high-temperature material is extruded at a very high pressure (for example, several tens to several hundreds of megapascals), the dimensional accuracy of the formed body is lowered. There is a problem that large-scale equipment is required and the maintenance cost of the equipment becomes high. Further, the known die casting method has a problem that the yield of the product is lowered due to air entrainment caused by press-fitting the molten metal into the mold or non-filling of the molten metal into the corner of the mold.

  On the other hand, as in Patent Document 2, the above problem is suppressed by the method of heating and sintering the molded body, but in the case of metals such as zinc (Zn), aluminum (Al), and magnesium (Mg), the surface of the metal powder Since there is a strong oxide film on top and the diffusion of atoms between the powders is hindered, an appropriate sintered body cannot be obtained by the above method. Accordingly, there is a need for a new technique that can easily produce an appropriate metal sintered body.

  This invention is made | formed in view of the said subject, and aims at manufacturing an appropriate metal sintered compact easily.

  The invention according to claim 1 is a method for producing a sintered metal body, comprising: a) a step of preparing a mixture in which metal powder, a flux agent and a binder resin are mixed; and b) a molded body obtained by extrusion molding of the mixture. And c) a step of obtaining a metal sintered body by heating the compact to a sintering temperature of the metal powder.

  Invention of Claim 2 is a manufacturing method of the metal sintered compact of Claim 1, Comprising: The said metal powder is a powder of zinc, aluminum, or magnesium.

  Invention of Claim 3 is a manufacturing method of the metal sintered compact of Claim 1 or 2, Comprising: The said metal powder is a powder of a pure metal, The said flux agent is a metal different from the said pure metal Not included.

  Invention of Claim 4 is a manufacturing method of the metal sintered compact in any one of Claim 1 thru | or 3, Comprising: The said mixture contains a pore formation agent.

  A fifth aspect of the present invention is the method for producing a sintered metal body according to any one of the first to fourth aspects, wherein the extrusion molding is performed at substantially normal temperature in the step b).

  The invention according to claim 6 is the method for producing a metal sintered body according to any one of claims 1 to 5, wherein the average particle diameter of the metal powder is 100 micrometers or more and 500 micrometers or less.

  According to the present invention, by removing the oxide film of the metal powder by thermal decomposition of the flux agent, sintering can be promoted, and a metal sintered body having high mechanical strength can be easily manufactured. .

  In invention of Claim 3, it can prevent that an unnecessary metal is mixed with a metal sintered compact. In invention of Claim 4, a porous metal sintered compact can be manufactured. In invention of Claim 5, the dimensional accuracy of a metal sintered compact can be improved.

It is a figure which shows the flow of the manufacturing process of a metal sintered compact. It is sectional drawing of an extrusion molding machine. It is a figure which shows the other example of the manufacturing process of a metal sintered compact.

  FIG. 1 is a diagram showing a flow of a manufacturing process of a sintered metal body according to an embodiment of the present invention. In the metal sintered body manufacturing process, first, a mixture in which metal powder, a flux agent and a binder resin are mixed using a predetermined mixer is prepared (step S11). Here, the flux agent is for removing the oxide film on the surface of the metal powder, and the binder resin is for binding the metal powder in the mixture. Details of the metal powder, the fluxing agent, and the binder resin will be described later.

  The mixing conditions of the metal powder, the flux agent and the binder resin are the material type and metal composition of the metal powder, the particle size of the metal powder, the type and composition of the binder resin, the composition of the flux agent, or the mixing ratio thereof. For example, the temperature during mixing is 5 ° C. or more and 50 ° C. or less, and the time required for mixing is 1 minute or more and 20 minutes or less. In addition to the metal powder, flux agent and binder resin, the mixture requires various additives such as plasticizers, dispersants, antioxidants, degreasing accelerators, surfactants and lubricants as auxiliary agents. May be added accordingly.

  Subsequently, the mixture is fed into the extruder 1 from the hopper 10 of the screw type extruder 1 shown in FIG. A rotating upper kneader 11 is disposed below the hopper 10, and the mixture passes through the upper kneader 11 and reaches the root of the upper screw 12. Around the upper screw 12, a substantially cylindrical upper barrel 13 centering on the central axis of the upper screw 12 is disposed. The mixture is in the direction indicated by the arrow on the right side of FIG. 2 (indicated by an arrow A1 in FIG. 2) while receiving a shearing force due to the rotation of the upper screw 12 between the upper screw 12 and the inner surface of the upper barrel 13. , Hereinafter referred to as “feed direction”). A vacuum chamber 14 which is a decompressed space is provided in the vicinity of the tip of the upper screw 12, and the mixture sent in the feeding direction is pushed out into the vacuum chamber 14 and deaerated. In the present embodiment, the mixture is substantially kneaded (kneaded) by passing through the vicinity of the upper kneader 11 and the upper screw 12 (step S12). In addition, although the conditions at the time of kneading the mixture depend on various conditions as in the mixing of materials, in this embodiment, for example, the temperature at the time of kneading is 5 ° C. or more and 50 ° C. or less, and the time required for kneading is It is 10 minutes or more and 180 minutes or less. Further, the mixture may be kneaded in a kneader such as a kneader or a three-roll mill prepared separately.

  A rotating lower kneader 21 is provided below the vacuum chamber 14, and the mixture (which can also be regarded as a kneaded product) passes through the lower kneader 21 and reaches the root of the lower screw 22. A substantially cylindrical lower barrel 23 centering on the central axis of the lower screw 22 is disposed around the lower screw 22. The mixture moves in the feeding direction between the lower screw 22 and the inner surface of the lower barrel 23 while receiving a shearing force due to the rotation of the lower screw 22. In the vicinity of the tip of the lower screw 22, an extrusion die 24 is provided in which the inner diameter gradually decreases (including a portion having a constant inner diameter) toward the front side in the feed direction (the right side in FIG. 2). The mixture fed in the feeding direction by the lower screw 22 is molded according to the inner surface shape of the extrusion die 24, and a molded body obtained by extrusion molding of the mixture is obtained (step S13). Note that the shape of the extrusion die 24 may be changed according to a desired cross-sectional shape of the molded body. In addition, the dimensions of the molded body (that is, the dimensions of the extrusion die 24) are determined in consideration of the volume shrinkage due to the drying process, the degreasing process, and the sintering process described later.

  In the extrusion molding machine 1 that shears the mixture, the temperature rises due to frictional heat, and the temperature of the mixture (kneaded product during and after kneading) rises accordingly. Alternatively, there is a possibility of deterioration of the characteristics of the molded body, but by supplying water cooled by a cooling machine such as a chiller to a cooling water circulation path (not shown) provided in the extrusion molding machine 1 as necessary, It is prevented that the mixture and the molded body are affected by the temperature rise of the extruder 1. The cooling temperature at the time of extrusion molding may be appropriately determined within a range in which the solvent contained in the mixture is not frozen and good moldability is maintained, and is, for example, 5 ° C. or more and 40 ° C. or less. Thereby, extrusion molding is performed at substantially normal temperature.

  Subsequently, after the molded body is dried in air at normal temperature and pressure (step S14), the molded body is placed in the sintering furnace, and the temperature in the sintering furnace is changed according to a predetermined profile. Thus, the degreasing process and the sintering process are sequentially performed (steps S15 and S16). The drying process may be performed in a sintering furnace or the like. Further, the degreasing process and the sintering process (and the drying process when performed in the sintering furnace) do not need to be clearly distinguished, but in FIG. 1, they are illustrated as different processes for convenience of explanation. .

  The temperature of the drying process may be a temperature sufficient for desorption of moisture contained in the molded body, and is, for example, 20 ° C. or higher and 70 ° C. or lower. The drying treatment may be performed under any conditions of normal pressure or reduced pressure, and the atmosphere around the molded body in the drying treatment may be either an oxidizing atmosphere or a non-oxidizing atmosphere. For example, the drying process time is 2 hours or more and 24 hours or less.

  The temperature of the degreasing process may be higher than the temperature of the drying process and sufficient to desorb the binder resin and the auxiliary agent contained in the molded body, and is, for example, 100 ° C. or higher and 220 ° C. or lower. The degreasing treatment may be performed under any conditions of normal pressure or reduced pressure, and the treatment atmosphere may be either an oxidizing atmosphere or a non-oxidizing atmosphere. For example, the degreasing time is 2 hours or more and 48 hours or less.

  The temperature of the sintering treatment is higher than the temperature at which the fluxing agent contained in the compact is decomposed, for example, 200 ° C. or more and 400 ° C. or less (however, lower than the melting point of the metal powder and higher than the temperature of the degreasing treatment). Temperature.) In the sintering process, the metal powder oxide film is removed (dissolved) by the gas generated by the thermal decomposition of the fluxing agent, and the surface of the metal material (so-called new surface) appears on the surface of the metal powder. Is promoted. In other words, when the molded body is heated to a predetermined sintering temperature, adjacent metal powders are sintered mainly through a new surface generated by thermal decomposition of the flux agent. The sintering treatment may be performed under any conditions of normal pressure or reduced pressure, and the treatment atmosphere may be either an oxidizing atmosphere or a non-oxidizing atmosphere. For example, the sintering process time is 1 hour or more and 48 hours or less.

  In the present embodiment, after drying the molded body in air at room temperature and normal pressure, the molded body is placed in a sintering furnace, and the temperature in the sintering furnace up to a certain temperature within the above degreasing temperature range. Is gradually increased (including a period in which the temperature is substantially constant; the same applies hereinafter), and then a sintering temperature within the range of the above-mentioned sintering temperature (for example, about half the melting point of the metal powder expressed in absolute temperature) The temperature in the sintering furnace is gradually increased to Thus, the compact is gradually heated to the sintering temperature of the metal powder, whereby the compact is sequentially degreased and sintered to obtain a sintered metal. As already mentioned, the degreasing and sintering processes do not need to be clearly distinguished, and the binder resin and auxiliary agent desorption, the fluxing agent pyrolysis, and the metal powder sintering proceed in part at the same time. May be. The metal sintered body obtained by the manufacturing process of FIG. 1 has a dense structure, and has higher strength than a sintered body (a sintered body of a comparative example) manufactured without using a flux agent.

  Next, the detail of the mixture containing metal powder, a flux agent, and binder resin is described. Examples of metal materials constituting the metal powder include copper (Cu), lead (Pb), tin (Sn), nickel (Ni), iron (Fe), chromium (Cr), zinc (Zn), and manganese (Mn). , Pure metals such as aluminum (Al) and magnesium (Mg), or alloys containing at least one metal element.

  Here, zinc, aluminum, and magnesium have a strong oxide film on the powder surface that inhibits the diffusion of atoms between the powders and have a relatively low melting point, so a general powder metallurgy technique forms a sintered body. Difficult to do. Even if a molded body molded without using a flux agent is heated, only a green compact is obtained, and its strength becomes very low. On the other hand, in the manufacturing process of FIG. 1, it is possible to form a sintered body having high mechanical strength by melting the oxide film by thermal decomposition of the flux agent even if the powder is zinc, aluminum, and magnesium. is there. From such a viewpoint, the metal powder in the mixture is particularly preferably a zinc, aluminum, or magnesium powder.

  The particle size (average particle size) of the metal powder is not particularly limited, but considering the clearance (gap) between the screw and the barrel (cylinder) in the extruder 1 used in the extrusion molding in step S13, 500 It is preferable that it is micrometer (micrometer) or less (for example, it is 1 micrometer or more, Preferably it is 10 micrometers or more), More preferably, it is 200 micrometers or less.

  By the way, in the production of a general sintered body, it is preferable to use a powder having a small particle diameter from the viewpoint of promoting the sintering and the strength of the sintered body, but metal powders such as zinc, aluminum, and magnesium are used. As the pulverization progresses, care must be taken. On the other hand, in the method of FIG. 1 in which a new surface is generated on the surface of the metal powder by thermal decomposition of the fluxing agent, a metal powder having a large average particle size that is not usually used in a powder metallurgy method, for example, an average particle size of 100 μm or more. Even when a relatively coarse metal powder is used, the sinterability does not deteriorate, and an appropriate metal sintered body can be easily produced. Various known methods such as a reduction method, a water / gas atomization method, an electrolysis method, and a pulverization method can be used as the method for producing the metal powder.

  As the binder resin, both aqueous and non-aqueous binders can be used, and various known binders may be used. From the viewpoint of environmental conservation, an aqueous binder resin is preferably used. Further, from the viewpoint of easily removing (degreasing) the binder resin in step S15, the decomposition temperature is preferably 400 ° C. or lower. Specific examples of the binder resin used in the present embodiment include polyethylene, polypropylene, polyolefins of ethylene-vinyl acetate copolymer, acrylic resins such as polymethyl methacrylate and polybutyl methacrylate, styrene resins such as polystyrene, and polychlorinated. Examples thereof include vinyl, polyvinylidene chloride, polyamide, polyester, polyether, polyvinyl alcohol, and copolymers thereof. These binder resins can be used alone or in admixture of two or more. The amount of the binder added is not particularly limited as long as it does not affect operability and shape retention, but in terms of shortening the time required for degreasing, it is 10 parts or less (that is, 100 g (g) of metal powder. 10 g or less).

  The fluxing agent is not limited to any resin type, inorganic acid type, or organic acid type, and a known fluxing agent can be used. Specific examples of active ingredients contained in the fluxing agent include amine halogen salts, organic acids, amine organic acid salts, ammonium halides, zinc halides, magnesium halides, tin halides, potassium halides, sodium halides, halogens. Examples thereof include lithium halide, calcium halide, aluminum halide, phosphoric acid, and hydrogen halide. These active components can be used alone or in admixture of two or more. Since the flux agent is gasified by thermal decomposition in the sintering process, no residue of the flux agent is generated in the sintered body. In addition, it is preferable that the decomposition temperature of a flux agent is higher than the decomposition temperature of binder resin. Here, when the metal powder is a pure metal powder, the flux agent contains only the pure metal as a metal from the viewpoint of preventing an unnecessary metal from being mixed with the sintered metal, or It is preferable that no metal is contained. That is, it is preferable that the flux agent does not contain a metal different from the pure metal.

  The addition amount of the fluxing agent related to the removal of the oxide film and the generation of the new surface in the metal powder only needs to be an amount that can realize sufficient bonding between particles in the sintering of the metal powder in step S16. Then, it is 1 mass percent or more and 20 mass percent or less, preferably 1 mass percent or more and 10 mass percent or less based on the amount of metal powder. In addition, in the process of step S16, when the sintering of the metal powder in the molded body does not proceed sufficiently, that is, when the addition amount of the fluxing agent at the time of preparing the mixture is insufficient, the fluxing agent is water or solvent. The molded body (that is, a poorly sintered product) is dipped in a flux solution that is a solution dissolved in, and the process of step S16 is performed again, whereby the sintering is sufficiently advanced, and an appropriate metal sintered body is obtained. It is possible to obtain

  Solvent in the mixture is water or alcohols such as methanol, ethanol, isopropyl alcohol, diethylene glycol, cellosolves such as methyl cellosolve, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, N, N-dimethylformamide, etc. Amides, esters such as ethyl acetate and butyl acetate, ethers such as dioxane, chlorinated solvents such as chloroform, aromatic hydrocarbons such as toluene and xylene, and these solvents are used alone or Two or more kinds can be mixed and used. From the viewpoint of environmental conservation, the solvent is preferably water. The amount of the solvent added is not particularly limited as long as it does not affect the operability and shape retention, but in terms of shortening the drying process time, it is 10 parts or less (that is, 100 g (g of metal powder (g ) Is preferably 10 g or less).

  By the way, when obtaining a sintered body using a metal powder having an oxide film, heat treatment is performed in a vacuum or in a non-oxidizing atmosphere, thereby converting the hydroxide present on the surface into an oxide. Decomposing and removing water molecules, and then adopting a technique (for example, a technique using a hot extrusion molding machine) that forms a new surface on the surface of the metal powder by applying physical plastic deformation to bond the metal. Can be considered. However, in this case, it is necessary to apply a very large force to the metal powder, which requires a large apparatus, increases the manufacturing cost of the metal sintered body, and further, due to expansion of the molded body after molding, etc. Dimensional accuracy is reduced.

  On the other hand, in the manufacturing process of the metal sintered body of FIG. 1, after preparing the mixture which mixed metal powder, the flux agent, and binder resin, the molded object by extrusion molding of a mixture is acquired, and a molded object is the said metal powder. Is heated to the sintering temperature. In the process of FIG. 1, sintering can be promoted by removing the oxide film of the metal powder by thermal decomposition of the fluxing agent, and a metal sintered body having high mechanical strength can be easily manufactured. .

  Moreover, in the manufacturing process of the metal sintered body, since extrusion molding can be performed at a relatively low pressure at almost normal temperature, a change in the size of the molded body after extrusion molding can be suppressed. The dimensional accuracy of the sintered body can be improved. Moreover, the size of the extrusion molding machine 1 used in extrusion molding can be reduced as compared with the molding machine used for hot extrusion. Furthermore, in the extrusion molding machine 1, it is possible to produce a molded body continuously and at low cost (low energy).

  FIG. 3 is a diagram showing a part of the flow of the manufacturing process of the sintered metal body according to another example, and shows a process performed in place of step S11 of FIG. In the process of FIG. 3, in addition to the metal powder, the flux agent and the binder resin, a mixture in which a pore forming agent is mixed is prepared (step S11a). The pore forming agent is for forming pores in the sintered body, and details thereof will be described later. When the mixture is prepared, the mixture is kneaded (FIG. 1: step S12) in the same manner as in the above process, and a molded body obtained by extrusion molding of the mixture is obtained (step S13). And the drying process of a molded object, a degreasing process, and a sintering process are performed continuously in order (step S14, S15, S16). At this time, the pore-forming agent in the molded body disappears by heating the molded body to the decomposition temperature of the pore-forming agent lower than the sintering temperature, and voids corresponding to the particle diameter of the pore-forming agent are formed in the molded body (sintered). Body). The said space | gap is disperse | distributed in the direction (direction corresponding to a feed direction) of a center axis | shaft of a molded object, and a direction perpendicular | vertical to a center axis. Further, since the oxide film of the metal powder is removed by thermal decomposition of the flux agent, the sintering of the metal powder is promoted. Thereby, the metal sintered body which has high mechanical strength and is made porous is obtained. In the metal sintered body, the pore diameter and the distribution (density) of the pores are controlled by the particle diameter and the addition rate of the pore-forming agent added to the mixture.

  In a pipe-shaped porous metal sintered body (for example, the wall thickness is 5 mm or less), the space on the inner surface side and the space on the outer surface side communicate with each other through a large number of pores, and water can be passed therethrough. . The porous metal sintered body can be used for, for example, a gas filter, a liquid filter, a catalyst carrier for use in a fuel cell reformer, an exhaust gas treatment particulate filter, a primary and secondary battery electrode, and the like.

  The pore-forming agent is not limited to either water-soluble or water-insoluble, and a known pore-forming agent can be used. From the viewpoint of controlling pore diameter and pore distribution, water-insoluble pores are used. It is preferable to use a forming agent. The pore-forming agent exists independently without being dissolved in the binder resin in the state of the mixture. Examples of water-insoluble pore-forming agents include waxes such as paraffin wax, thermoplastic resins such as polypropylene, polystyrene and EVA, methacrylic resins such as polyvinyl alcohol, ethyl cellulose, methyl methacrylate and butyl methacrylate, acrylic resins, A camphor can be mentioned, and it can be used alone or in admixture of two or more. The particle size of the pore-forming agent is not particularly limited, but is preferably 1 μm or more and 1000 μm or less in consideration of gas permeation and liquid permeation in the sintered metal body. In order to achieve effective pore formation without reducing the mechanical strength of the sintered metal, the volume ratio of the pore-forming agent to the metal powder in the mixture is preferably 1% or more and 70% or less, More preferably, it is 5 percent or more and 50 percent or less.

  As described above, in the process including FIG. 3, the porous metal sintered body having high mechanical strength can be easily manufactured by including the pore forming agent together with the metal powder, the flux agent, and the binder resin in the process. be able to. Moreover, in the porous metal sintered body obtained by the above-described treatment, the diameter and distribution density of the pores (independent pores and communication pores) can be controlled by the particle size and addition amount of the pore-forming agent. Therefore, in the process including FIG. 3, a sintered metal body having pore diameters and distributions can be manufactured in accordance with applications and purposes such as reaction / adsorption site, gas permeation, and liquid permeation.

  Hereinafter, Examples 1 to 8 of the manufacturing process of the metal sintered body of FIG. 1, Examples 9 and 10 of the manufacturing process of the porous metal sintered body including FIG. 3, and the case where no flux agent is added to the mixture Comparative examples 1 and 2 will be described.

Example 1
2500 g of zinc metal powder having an average particle size of 22.1 μm (manufactured by Toho Zinc Co., Ltd.), 150 g of aqueous binder (binder resin) R-400 (manufactured by Meisei Chemical Industry Co., Ltd.), ammonium chloride as a flux agent (Kishida Chemical Co., Ltd.) 100 g) was put into a stainless steel pot, and mixed with a high speed cutter MHS-165 manufactured by Miyazaki Tekko Co., Ltd. for 2 minutes in a dry powder state. Subsequently, 150 g of water, 38 g of Unilube (registered trademark) 50MB-26 (manufactured by NOF Corporation) as a dispersant, 38 g of dynamite glycerin (manufactured by NOF Corporation) as a plasticizer and Ceramisole (registered trademark) A-08 After mixing 25 g (manufactured by NOF Corporation) and stirring until uniform, a mixture was obtained by mixing for 2 minutes using a high-speed cutter for each addition while adding half by half to the mixed dry powder.

  Next, in the screw-type extruder FM-P30 manufactured by Miyazaki Tekko Co., Ltd., the cooling water temperature is set to 25 ° C., and the mixture is kneaded for 1 hour using the upper kneader, the upper screw and the upper barrel. A kneaded product was obtained. After mounting an extrusion die for producing a pipe-shaped molded body (die for pipe molding with an outer diameter of 17 millimeters (mm) / inner diameter of 13 mm) to the extruder, the cooling water temperature was set to 25 ° C. The kneaded product was extruded to obtain a 2200 mm long pipe-shaped product. In addition, the obtained molded object was cut | disconnected to length 100mm in consideration of subsequent operativity (it is the same in another Example and a comparative example). Moreover, the pressure applied to the vicinity of the extrusion die during extrusion molding was 7 megapascals (MPa).

  Subsequently, the molded body obtained as described above was dried under air at 25 ° C. for 24 hours, and then the molded body was subjected to degreasing treatment at 300 ° C. for 12 hours to obtain organic components (binder resin, auxiliary agent). Then, by further sintering at 400 ° C. for 12 hours, a pipe-like zinc sintered body having an outer diameter of 17.2 mm and an inner diameter of 13.1 mm to which zinc particles (that is, zinc powder) were fused was obtained. The strength of the obtained sintered body in the three-point bending test was 12.4 MPa.

(Example 2)
The length of the extrusion die is extrusion-molded in the same manner as in Example 1 except that the extrusion die is replaced with a pipe-shaped extrusion die (outer diameter 10 mm / inner diameter 3 mm) having a different size from that of Example 1. A 2200 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 5 MPa. Subsequently, a pipe having an outer diameter of 10.0 mm and an inner diameter of 3.0 mm in which zinc particles are fused by performing a drying process, a degreasing process, and a sintering process on the obtained molded body in the same manner as in Example 1. A zinc sintered body was obtained. The strength of the obtained sintered body in a three-point bending test was 30.4 MPa.

(Example 3)
The fluxing agent was changed from ammonium chloride in Example 1 to [ZnCl ₄ ] Cl (NH ₄ ) ₃ (the addition amount is also 100 g), and other materials were used in the same mixture as in Example 1, Extrusion molding was carried out in the same manner as in Example 1 to obtain a 2200 mm long pipe-shaped molded body. The pressure applied near the extrusion die at the time of extrusion molding was 6 MPa. Subsequently, a pipe having an outer diameter of 17.1 mm and an inner diameter of 13.2 mm in which zinc particles are fused by performing drying, degreasing, and sintering in the same manner as in Example 1. A zinc sintered body was obtained. The strength of the obtained sintered body in a three-point bending test was 11.3 MPa.

Example 4
The length of the extrusion die was extrusion-molded in the same manner as in Example 3 except that the extrusion die was replaced with an extrusion die (outer diameter 10 mm / inner diameter 3 mm) for producing a pipe-shaped molded product having a different size from that of Example 3. A 2150 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 5 MPa. Subsequently, a pipe having an outer diameter of 10.0 mm and an inner diameter of 3.1 mm in which zinc particles are fused by performing a drying process, a degreasing process, and a sintering process on the obtained molded body in the same manner as in Example 1. A zinc sintered body was obtained. The strength of the obtained sintered body in a three-point bending test was 30.1 MPa.

(Example 5)
5000 g of zinc metal powder having an average particle size of 43.7 μm (manufactured by Toho Zinc Co., Ltd.), 300 g of an aqueous binder R-400 (manufactured by Meisei Chemical Co., Ltd.), 180 g of ammonium chloride (manufactured by Kishida Chemical Co., Ltd.) as a flux agent It put in the stainless steel pot, and it mixed for 2 minutes under the state of dry powder with the high-speed cutter MHS-165 by Miyazaki Tekko Co., Ltd. Subsequently, 300 g of water, 75 g of Unilube (registered trademark) 50MB-26 (manufactured by NOF Corporation) as a dispersant, 75 g of dynamite glycerin (manufactured by NOF Corporation) as a plasticizer and Ceramisole (registered trademark) C-08 After mixing 50 g (manufactured by NOF Corporation) and stirring until uniform, a mixture was obtained by mixing for 2 minutes using a high-speed cutter for each addition while adding half by half to the mixed dry powder.

  Next, in the screw type extrusion molding machine FM-P30 manufactured by Miyazaki Tekko Co., Ltd., the cooling water temperature is set to 15 ° C., and the mixture is kneaded for 1 hour using the upper kneader, the upper screw and the upper barrel. A kneaded product was obtained. After mounting an extrusion die (outer diameter 17 mm / inner diameter 13 mm) for producing a pipe-shaped molded body to the extruder, the cooling water temperature was set to 25 ° C., and the resulting kneaded product was extruded to be long. A 2200 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 6 MPa. And a pipe-shaped zinc sintered body having an outer diameter of 17.1 mm and an inner diameter of 13.1 mm in which zinc particles are fused by performing a drying process, a degreasing process, and a sintering process on the molded body in the same manner as in Example 1. Got the body. The strength of the obtained sintered body in a three-point bending test was 11.0 MPa.

(Example 6)
The length of the extrusion die is extrusion-molded in the same manner as in Example 5 except that the extrusion die is replaced with an extrusion die (outer diameter 10 mm / inner diameter 3 mm) for producing a pipe-shaped molded body having a different size from that of Example 5. A 2150 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 7 MPa. Subsequently, a pipe having an outer diameter of 10.0 mm and an inner diameter of 3.0 mm in which zinc particles are fused by performing a drying process, a degreasing process, and a sintering process on the obtained molded body in the same manner as in Example 1. A zinc sintered body was obtained. The strength of the obtained sintered body in a three-point bending test was 30.2 MPa.

(Example 7)
5000 g of zinc metal powder having an average particle size of 90.5 μm (manufactured by Toho Zinc Co., Ltd.), 400 g of an aqueous binder R-400 (manufactured by Meisei Chemical Co., Ltd.), 260 g of ammonium chloride (manufactured by Kishida Chemical Co., Ltd.) as a flux agent It put in the stainless steel pot, and it mixed for 2 minutes under the state of dry powder with the high-speed cutter MHS-165 by Miyazaki Tekko Co., Ltd. Subsequently, 400 g of water, 75 g of Unilube (registered trademark) 50MB-26 (manufactured by NOF Corporation) as a dispersant, 75 g of dynamite glycerin (manufactured by NOF Corporation) as a plasticizer and Ceramisol (registered trademark) C-08 After mixing 50 g (manufactured by NOF Corporation) and stirring until uniform, a mixture was obtained by mixing for 2 minutes using a high-speed cutter for each addition while adding half by half to the mixed dry powder.

  Next, in the screw-type extruder FM-P30 manufactured by Miyazaki Tekko Co., Ltd., the cooling water temperature is set to 25 ° C., and the mixture is kneaded for 1 hour using the upper kneader, the upper screw and the upper barrel. A kneaded product was obtained. After mounting an extrusion die (outer diameter 17 mm / inner diameter 13 mm) for producing a pipe-shaped molded body to the extruder, the cooling water temperature was set to 25 ° C., and the resulting kneaded product was extruded to be long. A 2200 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 3 MPa. And a pipe-shaped zinc sintered body having an outer diameter of 17.2 mm and an inner diameter of 13.1 mm in which zinc particles are fused by performing a drying process, a degreasing process, and a sintering process on the molded body in the same manner as in Example 1. Got the body. The strength of the obtained sintered body in a three-point bending test was 5.9 MPa.

(Example 8)
The length of the extrusion die was extrusion-molded in the same manner as in Example 7 except that the extrusion die was replaced with an extrusion die (outer diameter 10 mm / inner diameter 3 mm) for producing a pipe-shaped molded body having a size different from that of Example 7. A 2150 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 3 MPa. Subsequently, a pipe-shaped zinc sintered body having an outer diameter of 10.1 mm and an inner diameter of 3.0 mm to which zinc particles were fused was obtained by performing drying treatment, degreasing treatment, and sintering treatment in the same manner as in Example 1. The strength of the obtained sintered body in the three-point bending test was 7.8 MPa.

Example 9
2500 g zinc metal powder with an average particle size of 20 μm (manufactured by Toho Zinc Co., Ltd.), 150 g of aqueous binder R-400 (manufactured by Meisei Chemical Co., Ltd.), 100 g of ammonium chloride as a flux agent (manufactured by Kishida Chemical Co., Ltd.), pore formation 360 g of IBM-2 (manufactured by Sekisui Plastics Co., Ltd.) as an agent was placed in a stainless steel pot and mixed for 2 minutes under a dry powder condition with a high-speed cutter MHS-165 manufactured by Miyazaki Tekko Co., Ltd. Subsequently, 150 g of water, 38 g of Unilube (registered trademark) 50MB-26 (manufactured by NOF Corporation) as a dispersant, 38 g of dynamite glycerin (manufactured by NOF Corporation) as a plasticizer and Ceramisole (registered trademark) C-08 After mixing 25 g (manufactured by NOF Corporation) and stirring until uniform, a mixture was obtained by mixing for 2 minutes using a high-speed cutter for each addition while adding half by half to the mixed dry powder.

  Next, in the screw-type extruder FM-P30 manufactured by Miyazaki Tekko Co., Ltd., the cooling water temperature is set to 25 ° C., and the mixture is kneaded for 1 hour using the upper kneader, the upper screw and the upper barrel. A kneaded product was obtained. After mounting an extrusion die (outer diameter 17 mm / inner diameter 13 mm) for producing a pipe-shaped molded body to the extruder, the cooling water temperature was set to 25 ° C., and the resulting kneaded product was extruded to be long. A 2200 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 7 MPa.

  Subsequently, after the obtained molded body was dried at 25 ° C. for 24 hours in air, the molded body was subjected to degreasing treatment at 300 ° C. for 12 hours to remove organic components (binder resin, auxiliary agent, pore forming agent). Removal was performed, and further, a sintering process was performed at 400 ° C. for 12 hours to obtain a pipe-like porous zinc sintered body having an outer diameter of 17.0 mm and an inner diameter of 13.0 mm, to which zinc particles were fused. The strength of the obtained porous zinc sintered body in a three-point bending test was 9.4 MPa, the porosity was 67%, and the gas permeation amount was 8348 m / hr / atm at 0.002 MPa.

(Example 10)
The length of the extrusion die is extrusion-molded in the same manner as in Example 9 except that it is replaced with a pipe-shaped extrusion die (outer diameter 10 mm / inner diameter 3 mm) for production of a pipe-shaped product having a different size from that of Example 9. A 2150 mm pipe-shaped molded body was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 5 MPa. Subsequently, the molded body was dried, degreased, and sintered in the same manner as in Example 9 to fuse the zinc particles to a pipe-like porous material having an outer diameter of 10.1 mm and an inner diameter of 3.0 mm. A zinc sintered body was obtained. The strength of the obtained porous zinc sintered body in a three-point bending test was 20.9 MPa, the porosity was 69%, and the gas permeation amount was 8008 m / hr / atm at 0.002 MPa.

(Comparative Example 1)
By extruding a mixture which is the same as in Example 1 except that no flux agent is added, using an extrusion die (outer diameter 17 mm / inner diameter 13 mm) for producing a pipe-shaped molded body, as in Example 1. A pipe-shaped molded product having a length of 2100 mm was obtained. The pressure applied near the extrusion die at the time of extrusion molding was 5 MPa. Subsequently, a pipe having an outer diameter of 17.5 mm and an inner diameter of 13.8 mm in which zinc particles are fused by performing drying, degreasing, and sintering in the same manner as in Example 1. A zinc sintered body was obtained. The strength of the obtained sintered body in the three-point bending test is 0.8 MPa, which is lower than the strength of the zinc sintered body obtained in Example 1.

(Comparative Example 2)
Except that the fluxing agent was not added, the same mixture as in Example 1 (and Example 2) was used, as in Example 2, using an extrusion die (outer diameter 10 mm / inner diameter 3 mm) for producing a pipe-shaped molded body. The pipe-shaped molded product having a length of 2100 mm was obtained by extrusion molding. The pressure applied near the extrusion die at the time of extrusion molding was 5 MPa. Subsequently, an outer diameter of 10.3 mm in which zinc particles are fused by performing drying treatment, degreasing treatment, and sintering treatment in the same manner as in Example 1 (and Example 2) on the obtained molded body, A pipe-shaped zinc sintered body having an inner diameter of 3.2 mm was obtained. The strength of the obtained sintered body in the three-point bending test is 1.0 MPa, which is lower than the strength of the zinc sintered body obtained in Example 2.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, in the above-described embodiment, a non-heat-molded plunger-type extruder or the like can be used instead of the screw-type extruder 1. However, since the supply of the mixture is a batch type in the plunger type extruder, it is preferable to use a screw type extruder capable of continuous molding in consideration of mass productivity. Further, when high dimensional accuracy is not required in a sintered metal body, a molded body is obtained by performing extrusion molding with heating on a mixture containing metal powder, a flux agent and a binder resin. May be.

  The configurations in the above-described embodiments and modifications may be combined as appropriate as long as they do not contradict each other.

1 Extruder S11-S16, S11a Step

Claims (6)

A method for producing a sintered metal body, comprising:
a) preparing a mixture in which a metal powder, a fluxing agent and a binder resin are mixed;
b) obtaining a molded body by extrusion molding of the mixture;
c) obtaining the metal sintered body by heating the compact to the sintering temperature of the metal powder;
The manufacturing method of the metal sintered compact characterized by the above-mentioned. It is a manufacturing method of the metal sintered compact according to claim 1,
The method for producing a sintered metal body, wherein the metal powder is zinc, aluminum, or magnesium powder. It is a manufacturing method of the metal sintered compact according to claim 1 or 2,
The metal powder is a pure metal powder, and the flux agent does not contain a metal different from the pure metal. It is a manufacturing method of the metal sintered compact according to any one of claims 1 to 3,
The method for producing a sintered metal body, wherein the mixture contains a pore forming agent. It is a manufacturing method of the metal sintered compact according to any one of claims 1 to 4,
In the step b), the extrusion molding is performed at substantially normal temperature. It is a manufacturing method of the metal sintered compact according to any one of claims 1 to 5,
An average particle diameter of the metal powder is 100 micrometers or more and 500 micrometers or less, A method for producing a metal sintered body, wherein

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