WO2006003703A1

WO2006003703A1 - Sintered compact having portions of different sinter relative densities and method for production thereof

Info

Publication number: WO2006003703A1
Application number: PCT/JP2004/009410
Authority: WO
Inventors: Yoshimitsu Kankawa
Original assignee: Mold Research Co., Ltd.
Priority date: 2004-07-02
Filing date: 2004-07-02
Publication date: 2006-01-12
Also published as: WO2006004011A1; JPWO2006004011A1

Abstract

A sintered compact having some portions of different sinter relative densities, wherein the sintered interface of said portions are integrated by sintering; and a method for producing a sintered compact having some portions of different sinter relative densities, characterized in that it comprises the steps of subjecting molding materials X and Y to the injection molding using a two-color molding machine into articles having respective desired shapes, degreasing and then sintering, wherein the above molding material X contains a metal powder A having an average particle diameter of 30 μm or less and the above molding material Y comprises a metal powder B which comprises the same material as that of the above powder A and has an average particle diameter being larger than that of the above powder A by 20 μm or more.

Description

Specification

Sintered products in which portions having different sintered relative densities coexist and a manufacturing method thereof

The present invention relates to a sintered product using powder injection molding and a method for manufacturing the same. More specifically, the present invention relates to a sintered product in which portions having different sintered relative densities coexist and a manufacturing method thereof.

Background art

[0002] Conventionally, several techniques for forming a porous body (sintered body having a low sintered relative density) by powder metallurgy by pressing and sintering powder are found in Patent Document 1, Patent Document 2, and the like. . In these manufacturing methods, powder is filled into a press mold and a product is obtained by applying pressure. Therefore, it is difficult to obtain a product with a complicated shape. The pores in the surface portion are blocked, and it is difficult to obtain a porous sintered body uniformly from the surface to the inside.

[0003] In the case of metal, the powder injection molding method is a technique that can obtain a product with high density by molding and sintering using a powder having an average particle diameter of 20 μm or less. A porous body can be obtained by performing molding and sintering using a powder having a coarse particle diameter by a powder injection molding method. In the case of metal, a sintered product of a porous body having a low sintering density can be obtained by using a powder having a particle size of about 10 × m and sintering at a low temperature. In addition, Patent Document 3 and Patent Document 4 show techniques for obtaining a porous sintered body by adding a thermosetting resin or the like to an organic binder and performing injection molding.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-2130

Patent Document 2: JP-A-2-44077

Patent Document 3: Japanese Patent Laid-Open No. 5-163082

Patent Document 4: Japanese Patent Laid-Open No. 5-117058

Disclosure of the invention

Problems to be solved by the invention

[0005] However, since these porous sintered bodies have low strength, they are complicated by injection molding or the like. It is difficult to produce a thin product when trying to produce a shaped product. In particular, when a porous product is made with ceramics, the product becomes even more brittle, making it difficult to commercialize the product. For this reason, attempts have been made to cover the brittleness of the porous portion by combining the porous body with a high-density portion having high strength. In addition to these purposes, there is a demand in the industry for products having a porous portion and a high-density portion.

[0006] Conventionally, a product having a porous portion and a high-density portion is made by combining a porous sintered product and a high-density sintered product by machining, welding, bonding, or shrink fitting. Have been made.

However, since the strength of the porous portion is low as described above, it is difficult to combine it with the high-density portion by machining. In addition, it is difficult to produce a large number of products with complex shapes by the method using machining. Furthermore, the sintered product thus obtained has a problem of peeling from the bonded portion.

[0008] The present invention has been made in view of the above-described problems in the prior art, and is a sintered product in which the high-density portion and the porous portion have different sintered relative densities. Thus, the present invention provides a sintered product in which the sintered body interface between the parts is integrated by sintering, and a method for producing the sintered product without using machining. Means for solving the problem

[0009] The present invention is a sintered product in which parts having different sintered relative densities coexist, and the interface between the parts is integrated by sintering. This sintered product can be manufactured by the manufacturing method of the present invention.

[0010] The sintered product according to the present invention is different from the conventional product in which parts having different densities are combined by machining because the interface between parts having different sintered relative densities is integrated by sintering. The durability is excellent because no peeling occurs at the interface between them. Further, the sintered product according to the present invention includes products having a low sintering relative density and a thickness of 100 μm 1 mm in the portion and a thin portion.

[0011] Further, the present invention is a method for producing a sintered metal product in which parts having different sintered relative densities coexist,

Molding materials X and Y are each injection molded into the desired shape using a two-color molding machine. Including the steps of degreasing and sintering,

The molding material X contains metal powder A having an average particle size of 30 / m or less, and the molding material Y is made of the same material as the powder A, and the average particle size of the powder A is 20 μm. More than the above, containing metal powder B,

It is the method characterized by this.

[0012] By using the molding material X containing the metal powder A having an average particle size of 30 xm or less, a portion having a high sintered relative density (hereinafter referred to as a high-density portion) can be molded. On the other hand, by using the molding material Y containing the metal powder B having the same material strength as the powder A and having an average particle size of 20 μm or more larger than the powder A, the sintered relative density is higher than that of the high density portion. Five. / ₀ or more lower part (hereinafter referred to as low density part) can be molded. The molding material and Y are injection-molded into a desired shape using a two-color molding machine, degreased and sintered, and the interface between the high-density part and the low-density part is integrated by sintering. The ability to produce sintered products is possible.

[0013] Furthermore, the present invention is a method for producing a sintered ceramic product in which portions having different sintered relative densities coexist.

The molding materials X 'and Y' are each injection-molded into a desired shape using a two-color molding machine, degreased, and sintered.

The molding material X ′ contains ceramic powder C having a BET specific surface area of 3. lm ² / g or more; and

The molding material Y ′ is made of the same material as the powder C and contains a ceramic powder D having a BET specific surface area smaller than the powder C by 3 m ² / g or more.

It is the method characterized by this.

[0014] BET specific surface area 3. By using molding material X 'containing ceramic powder C of lm ² Zg or more, it is possible to mold parts with high sintered relative density (hereinafter referred to as high density parts). On the other hand, by using a molding material Y ′ made of the same material as that of the powder C and containing a ceramic powder D smaller than the powder C by a BET specific surface area of 3 m ² / g or more, it is sintered from the high-density portion. It is possible to form a part with a relative density of 5% or more (hereinafter referred to as a low density part). Molding materials X 'and Y' can be formed into desired shapes using a two-color molding machine. A ceramic sintered product in which the boundary surface between the high-density part and the low-density part is integrated by sintering can be manufactured by injection molding into a shape, degreasing, and sintering.

[0015] By using a two-color molding machine, it is possible to easily and continuously form portions having different densities. That is, after one part is molded, another part in contact with that part is injection-molded, so that the concavity and convexity of both contact surfaces are completely coincident. After that, by sintering at high temperature, the contact surfaces of both are welded. Therefore, the interface between the two is completely integrated by the combination of unevenness and welding and does not peel off. In addition, by using this method, it is possible to reduce the thickness of all or part of the low density portion to 100 zm. Therefore, even a product having a thin part with a thickness of 1 mm or less in a low density part can be stably supplied.

The invention's effect

[0016] As described above, the sintered product according to the present invention includes portions where the sintered relative density differs by 5% or more, but the interface between the portions is integrated by sintering. No surface separation occurs. Further, according to the manufacturing method of the present invention, the sintered product can be manufactured without machining, so that the manufacturing process is simple and suitable for mass production of products having complicated shapes. Furthermore, it is possible to stably supply products in which the thickness of all or part of the low density portion is 1 mm or less.

Brief Description of Drawings

[0017] [Fig. 1] Sintered product consisting of an outer peripheral portion of a high density portion and a central portion of a low density portion.

[Figure 2] Sintered product with a three-layer structure

Explanation of symbols

[0018] 1 Center

2 Outer part

a Sintering density of 95%

b Sintered relative density 85%

c Part consisting of 75% sintered relative density

BEST MODE FOR CARRYING OUT THE INVENTION [0019] The sintered relative density can be determined by the following equation.

Sintered relative density = weight of sintered body / (weight of sintered body-weight in water) X 100

[0020] An interface between parts having different sintered relative densities means a contact surface between the parts. In the present invention, the portions having different sintered relative densities may not be two but may be three or more. For example, as shown in Figure 2A, the sintered relative density is 95. /. The sintered product of the present invention also includes a sintered product having a three-layer structure comprising 85%, 75%, and 75%. In addition, as shown in FIG. 2B, a sintered product having a three-layer structure with two types of density, including 95%, 85%, and 95%, is also included in the sintered product of the present invention.

Such a sintered product can be produced, for example, by embossing the molded body and sintering it by combining three types of molded bodies having different sintered relative densities. By changing the amount of fine powder applied to coarse powder, it is possible to integrally form products with three levels of density.

“Integrated by sintering” means that the interface between the parts is welded by heating during sintering.

[0022] The sintered product according to the present invention and the sintered product manufactured by the method according to the present invention are sintered products in which portions having different sintered relative densities coexist. In industry, it is desirable that the relative density of sintering in the high-density part is higher and stronger. On the other hand, the low-density part is often used as a so-called porous part in a filter or the like, so that the porosity is high so that dust can be removed with high efficiency, that is, the sintered relative density is low. There is a tendency to be demanded. For this reason, the high density portion of the sintered product according to the present invention preferably has a sintered relative density of 90% or more, more preferably 93% or more, and still more preferably 95% or more. In addition, the low density portion of the sintered product according to the present invention preferably has a sintered relative density of less than 90%, more preferably 85% or less, and even more preferably 80% or less. Accordingly, a preferable sintered product according to the present invention is a product having a difference in sintered relative density between parts having different densities of 5% or more, more preferably 7% or more, and further preferably 10% or more. Particularly preferred is a sintered product of 15% or more.

[0023] In addition to the method using a two-color molding machine, the sintered product according to the present invention is obtained by separately injection-molding the molding materials X and Y (or the molding materials X ′ and Y ′). , X compact and In addition, after obtaining a molded body of Y (or a molded body of X ′ and a molded body of Y ′), they can be combined, degreased and sintered.

[0024] Furthermore, the sintered product according to the present invention can also be produced by adjusting the sintering temperature in addition to the particle diameter of the powder used and the BET specific surface area.

Specifically, the molding materials X ′ ′ and Y ′ ′ are each injection-molded into a desired shape using a two-color molding machine, degreased and sintered, or

A method in which molding materials X '' and Y '' are separately injection molded without using a two-color molding machine to obtain YJ molded body and Y molded body, and then combined, degreased and sintered In

By setting the sintering temperature to be equal to or higher than the densification temperature of the molding material X ′ ′ and lower than the densification temperature of the molding material Y ′, parts having different sintered relative densities coexist, and the interface between the parts becomes It is possible to produce a sintered product integrated by sintering.

[0025] In the present specification, the densification temperature refers to a temperature at which the sintered relative density is 91% or more.

[0026] When the sintered product according to the present invention is manufactured using the difference in densification temperature, the difference in densification temperature between the above X ′ ′ and Y ′ ′ is preferably 30 ° C. or more. More preferably, it is 50 ° C or higher, and more preferably 100 ° C or higher.

[0027] In the sintering process, by adjusting the sintering temperature to be higher than the densification temperature of the molding material X ′ ′ and lower than the densification temperature of the Y ′ ′, a portion made of the molding material X ′ ′ Densifies and increases the sintered relative density, but the portion made of the molding material Y ′ ′ keeps the sintered relative density low. Therefore, according to the method, it is possible to form a sintered body in which portions having different densities coexist without adjusting the difference in average particle diameter or BET specific surface area. Further, as described above, since the interfaces between the respective parts are integrated in the sintering process, it is possible to manufacture a sintered product in which no separation of the boundary surface occurs.

[0028] As described above, by utilizing the difference in densification temperature in addition to the average particle diameter and the BET specific surface area, a sintered product in which portions having different sintered relative densities coexist, A sintered product in which the interface between the parts is integrated by sintering can be obtained. According to the method, the sintered metal product according to the present invention is manufactured even when the metal powder contained in each molding material is different. Is possible.

Similarly, even if the ceramic powder contained in each molding material is different, the sintered product according to the present invention can be manufactured.

In addition, products made of different materials made of ceramics and metals are also sintered products in which parts with different relative sintering densities coexist by adjusting the sintering temperature and the sintering atmosphere. It is possible to create a sintered product whose interface is integrated by sintering. For example, it is possible to produce a sintered body having a metal part and a ceramic part by using stainless steel or iron as the metal and alumina or zirconium as the ceramic.

[0029] A two-color molding machine refers to a machine capable of molding two types of materials into desired shapes. In general, it has two screws and cylinder parts that are molded by fusing the material, and the mold is filled with each material from each cylinder at different timings to the desired position. A molding machine capable of molding a desired shape.

[0030] In carrying out the method for producing a sintered metal product according to the present invention, powder A is mixed with molding material Y (the blending amount is 90% by weight or less with respect to the total amount of powder B). Alternatively, when the method for producing a sintered ceramic product according to the present invention is performed, the powder C is added to the molding material Y ′ (the blending amount is 90% by weight or less with respect to the total amount of the powder D). It is possible to control the porosity of the low density part. The porosity is calculated by the following formula.

Porosity = Density of sintered body / Density when porosity is 0 x 100

[0031] In addition, the molding material Y or Y ′ contains a resin having a high softening point (such as an epoxy resin, a urethane resin, a polyester resin, or a phenol resin), thereby further increasing the porosity of the low density portion. S can.

[0032] Powders A and B may be a kind of metal powder or a mixed powder composed of two or more kinds of metal powders. The metal powder used in the production method of the present invention is a powder having a melting point of 600 ° C. or higher and can be sintered. Examples include carbonyl iron, carbonyl nickel, stainless steel, low alloy steel, titanium, titanium alloy, single or alloy powders of copper, silver, gold, or a mixture thereof. [0033] The average particle size of the metal powder A is 30 / im or less, preferably 20 / im or less, and more preferably 10 / im or less. The metal powder B is made of the same material as the powder A, and has an average particle size larger than the powder A by 20 μm or more. When the particle size difference between metal powder B and metal powder A is reduced, the difference between the low density portion and the high density portion is reduced. The average particle size of the metal powder B is preferably about 30-100 μm or less, more preferably about 50 μm. When the particle size of the powder becomes large, the powder is easily clogged between the screw and the cylinder at the time of injection molding, making it difficult to mold, and the low density part is obtained by sintering at high temperature, but the strength is lowered.

[0034] On the other hand, when a ceramic sintered product is produced, a finer powder than a metal powder is used because of its sintering characteristics. In the case of ceramics, the BET specific surface area of the powder D used to obtain the low-density part is 0.1 about 6 m ² Zg, preferably about 1 to about 5 m ² / g, and is used to obtain the high-density part. The resulting powder C has a specific surface area of 3. lm ² Zg or more, preferably about 7 to about 30 m ² / g, more preferably about 7 to about 16 m ² / g.

[0035] Powders C and D may be a kind of ceramic powder or a mixed powder made of two or more kinds of ceramic powder. Examples of the ceramic used in the present invention include oxide ceramics such as alumina, dinoleconia, ferrite, titanium oxide and barium titanate, non-oxide ceramics such as silicon carbide, silicon nitride, aluminum nitride and boron nitride, or Mention may be made of these mixtures.

[0036] In the present invention, being made of the same material as the powder A means that when the powder A is a single metal powder, the powder B is also the same metal powder, and when the powder A is a mixed powder, It means that powder B is composed of the same metal powder as each metal powder constituting powder A. The mixing ratio of each metal powder constituting powder A and the mixing ratio of each metal powder constituting powder B may be different, but are more preferably the same.

Similarly, the same material as the powder C means that if the powder C is a single ceramic powder, the powder D is also the same ceramic powder. If the powder C is a mixed powder, the powder D The same ceramic powder force as each ceramic powder composing the powder C is composed. The mixing ratio of the ceramic powders composing the powder C and the mixing ratio of the ceramic powders composing the powder D may be different, but more preferably the same. [0037] In the manufacturing method according to the present invention, metal powder A and gold powder can be used even when metal powder (metal powder P) made of a material different from metal powder A is used instead of metal powder B. If the melting point of the metal powder P is close, adjust the particle size of the two in the same way as above (that is, as in the case of the metal powder A and the metal powder B) to obtain the desired density difference. Is possible. Here, that the melting points of both are close means that the difference between the melting points of the metal powders A and P is 400 ° C or less, preferably 200 ° C or less, more preferably 100 ° C or less.

Similarly, when ceramic powder (ceramic powder Q) made of a material different from ceramic powder C is used instead of ceramic powder D, the melting point of ceramic powder C and ceramic powder Q is close. By adjusting the BET specific surface area of both in the same manner as described above (that is, as in the case of ceramic powder C and ceramic powder D), a desired density difference can be obtained. Here, the close melting point of both means that the difference between the melting points of ceramic powders C and Q is 800 ° C or lower, preferably 600 ° C or lower, more preferably 500 ° C or lower.

[0038] For the molding material (X and Y) of the sintered metal product, the molding material useful for the present invention preferably contains an organic binder of about 30 to about 60 vol% of the total amount of the molding material. More preferably, it is about 35 to 50 vol%. The sintered ceramic molding material (X 'and Y') should contain about 40 to about 70 vol% of organic binder, preferably about 40 to about 70 vol% of the total amount of molding material. Is more preferable.

[0039] For the organic binder, thermoplastic resin, wax, plasticizer, lubricant, and the like are used. Thermoplastic resins have the effect of enhancing the retention after molding, and examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, acrylic resin, polyacetal, ethylene acetate butyrate, and polybutyral.

[0040] Wax has the effect of facilitating fluidity during molding and thermal decomposition during degreasing. Examples of the wax include paraffin wax, carnauba wax, ester wax and the like.

[0041] The plasticizer has a function of lowering the temperature during molding and a role of imparting flexibility, and examples of the plasticizer include phthalic compounds such as dioctyl phthalate and dibutyl phthalate. [0042] The lubricant has a function of promoting fluidity during molding. Examples of lubricants include fatty acid ester compounds such as stearic acid, myristic acid and oleic acid.

[0043] In the production method of the present invention, "including degreasing and sintering steps" includes not only the case where the degreasing step 'sintering step is included separately but also the case where degreasing' sintering is performed in one step. Is also included.

Next, the sintered product according to the present invention will be illustrated with reference to FIG. The central part of the sintered product shown in Fig. 1 is a part consisting of low-density parts. The outer periphery around it is a place consisting of high-density parts. When the sintered product of FIG. 1 is formed using a two-color molding machine, the low-density part in the central part and the high-density part in the outer peripheral part can be continuously formed.

When each part is produced individually, a desired sintered product can be obtained by molding the central part and the outer peripheral part and then combining these to degrease and sinter.

[0045] Hereinafter, a method for producing a sintered product of the present invention will be described in detail based on examples.

Example 1

[0046] Manufacture of sintered metal products

Using the method according to the present invention, a sintered product shown in FIG. 1 was produced.

Stainless steel powder (SUS316L) was used as the metal powder. Stainless steel powder with an average particle size of 6 μm is used as the powder A used for the molding material X for molding the high-density portion, and stainless steel powder with an average particle size of 50 μm is used as the powder B for the molding material Y for molding the low-density portion. Using.

As the organic binder, a mixture in which polyacetal, polypropylene, and paraffin wax were mixed at a ratio of 25:25:50 was used.

[0047] The composition of the molding material X and the molding material Y is as follows.

Molding material X: Powder A60vol% + organic binder 40vol%

Molding material Y: powder B65vol% + organic binder 35vol%

[0048] Injection molding was performed using a two-color molding machine. The molding temperature was 180 ° C, and a molded body consisting of a low density part (diameter 3 mm) in the center and a high density part (diameter 10 mm) on the outer periphery was produced. The obtained green body was degreased at a maximum temperature of 400 ° C ′ nitrogen atmosphere, and the degreased green body was sintered at a maximum temperature of 1350 ° C ′ argon atmosphere. The density of each part of the obtained sintered body Degrees were as follows, and the boundary surface between the high density part (outer peripheral part) and the low density part (center part) was welded.

Sintering relative density High density part: 95%, Low density part: 85%

[0049] From Example 1, a metal having a high-density part and a low-density part coexisting in the same product, and the interface between the high-density part and the low-density part is welded by sintering, and there is no problem in practical use. Sintered products could be obtained without post-processing under the same sintering conditions.

Example 2

[0050] Ceramics' Manufacture of sintered products made of metal

Using a molding material containing ceramic powder and a molding material containing metal powder, the sintered product shown in Fig. 1 was manufactured using the difference in densification temperature.

[0051] The composition of each molding material is as follows.

Molding material on the outer periphery: metal powder (stainless steel SUS304L powder: average particle size 10 a m) 65vol% + organic binder 35vol%

Molding material in the center: ceramic powder (alumina powder: BET specific surface area 3. lmVg) 55vol% + organic binder 45vol%

The temperature at which the outer peripheral part (metal part) becomes dense is 1300 ° C, and the temperature at which the central part (ceramic part) becomes dense is 1550 ° C.

[0052] Injection molding was performed using a two-color molding machine. Molding temperature is 170 ° C, center part (diameter

3 mm) and an outer peripheral part (diameter 10 mm). The obtained molded body was degreased at a maximum temperature of 400 ° C. in a nitrogen atmosphere, and the degreased molded body was sintered at a maximum temperature of 1350 ° C. under an argon atmosphere. The density of each part of the obtained sintered body was as follows, and the boundary surface between the high density part (outer peripheral part) and the low density part (inner peripheral part) was welded.

Sintered relative density High density part (metal part): 95% Low density part (ceramic part): 90%

[0053] According to Example 2, a high-density portion and a low-density portion coexist in the same product, and the interface between the high-density portion and the low-density portion is welded by sintering. Ceramic sintered products could be obtained under the same sintering conditions without post-processing.

[0054] Note that both the particle size of the metal powder and the BET specific surface area of the ceramic powder can form a high-density portion. If it is o ° c, the ceramic part is not densified and the sintered density can be kept low. On the other hand, the metal part was densified at a temperature of 1300 ° C., so it was densified under the above-mentioned sintering conditions, and as a result, a sintered product in which parts having a sintered relative density different by 5% or more coexisted could be obtained.

[0055] In Examples 3 and 4 below, a method for producing a sintered product according to the present invention without using a two-color molding machine is illustrated.

Example 3

[0056] Manufacture of sintered metal products

The sintered product shown in FIG. 1 was manufactured using the following method.

Titanium powder was used as the metal powder. Titanium powder with an average particle size of 20 μm as powder 成形 used for molding material X for molding high-density parts, and titanium with an average particle size of 50 μΐη as powder B used for molding material Y for molding low-density parts Use powder. Further, in this example, in order to adjust the porosity of the low density portion, in addition to powder B, 20% by weight of powder A of powder B was mixed to prepare molding material Y.

[0057] The composition of the molding material X and the molding material Y is as follows.

Molding material X: Powder A60vol% + organic binder 40vol%

Molding material Y: Powder B40vol% + Powder A25vol% + Organic binder 35vol%

[0058] Molding materials X and Y were each injection-molded, and the outer periphery (molded body X, cylindrical hollow body with a diameter of 10 mm having a cavity with a diameter of 3 mm at the center) and the center portion shown in FIG. (Form Y, 3 mm diameter cylinder) was produced. The molding temperature was 180 ° C. Molded body X is inserted and combined with molded body Y, and the combined molded body is degreased at a maximum temperature of 400 ° C and argon atmosphere, and the degreased molded body is at a maximum temperature of 1220 ° C * under high vacuum Sintered with (10-3AB). The sintered relative density of the obtained sintered body was as follows, and the boundary surface between the high density portion (outer peripheral portion) and the low density portion (center portion) was welded.

Sintering relative density High density part: 95%, Low density part: 84%

[0059] From Example 3, the same product has a high-density part and a low-density part, and the interface between the high-density part and the low-density part is welded by sintering. The product Under the same sintering conditions, it could be obtained without post-processing.

Example 4

[0060] Steelmaking of sintered ceramics

Alumina powder was used as the ceramic powder. Molding material for molding high-density parts

As powder C used for X ′, alumina powder having a specific surface area of 7 m ² / g was used, and as powder D used for molding material Y ′ for molding the low density part, alumina powder having a specific surface area of 3 m ² / g was used. Further, in this example, in order to adjust the porosity of the low density portion, in addition to powder D, 10% by weight of powder D was mixed with powder D to prepare molding material Y ′.

As the organic binder, a mixture in which acrylic resin, polypropylene, paraffin wax, dibutino phthalate, and stearic acid were mixed at a ratio of 25: 25: 40: 5: 5 was used.

[0061] The composition of the molding material X 'and the molding material Y' is as follows.

Molding material X '; powder C55vol% + organic binder 45vol%

Molding material Y ': Powder D40vol% + Powder C20vol% + Organic binder 40vol%

[0062] Molding materials X 'and Y' were respectively injection-molded, and the outer peripheral part (molded body X ', a cylindrical hollow body with a diameter of 10mm having a cavity with a diameter of 3mm at the center) and A central part (molded body Y ′, cylinder with a diameter of 3 mm) was produced. The molding temperature was 180 ° C. The formed body X ′ was inserted and combined with the formed body X ′, and an acrylic resin diluted with a solvent was applied to the insertion part. The combined green body was degreased at a maximum temperature of 400 ° C 'atmosphere, and the degreased green body was sintered at a maximum temperature of 1600 ° C' atmosphere. The density of the obtained sintered body was as follows, and the boundary surface between the high density portion and the low density portion was welded.

Sintered relative density, high density part: 99%, low density part: 85%

[0063] From Example 4, a ceramic sintered material having a high density portion and a low density portion coexisting in the same product, and having an interface between the high density portion and the low density portion welded by sintering, and causing no problem in practical use. The product could be obtained under the same sintering conditions without post-processing.

[0064] [Comparative Example 1]

Manufacture of sintered metal products (comparative products)

Instead of metal powder B, which is useful in the present invention, metal powder having an average particle size of 10 / m (metal powder A The average particle size difference was 4 _μΙη ), and the sintered product shown in FIG. 1 was produced.

[0065] Stainless steel powder (SUS316L) was used as the metal powder. Stainless steel powder with an average particle size of 6 / m was used as the powder used for the material forming the outer peripheral portion, and stainless steel powder with an average particle size of 10 μm was used as the powder used for the material forming the central portion.

[0066] The composition of each molding material is as follows.

Molding material on the outer periphery: Stainless steel powder (6 μm) 60vol% + Organic binder 40vol% Molding material on the center: Stainless steel powder (10μm) 65vol% + Organic binder 35vol%

[0067] Injection molding was performed using a two-color molding machine. Molding temperature is 180 ° C, center part (diameter

3 mm) and an outer peripheral part (diameter 10 mm). The obtained molded body was degreased at a maximum temperature of 400 ° C. in a nitrogen atmosphere, and the degreased molded body was sintered at a maximum temperature of 1350 ° C. under an argon atmosphere. The density of each part of the obtained sintered body was as follows, and the boundary surface between the central part and the outer peripheral part was welded.

Sintering relative density Peripheral part: 95%, central part: 94%

[0068] In Comparative Example 1, although the interface between the central portion and the outer peripheral portion was welded and a product having no problem in practical use was obtained, the sintered relative density of the central portion that was planned to become a low-density portion was obtained. Was as high as 94%, and there was no difference between the density of the outer peripheral portion and the desired sintered product could not be obtained.

[0069] [Comparative Example 2]

Manufacture of ceramic sintered products (comparative products)

Using the ceramic powder with a BET specific surface area of 5 m ² / g (difference 2 m ² Zg from the BET specific surface area of powder C) instead of the ceramic powder D, which is useful for the present invention, the sintered product shown in Fig. 1 was produced. did.

[0070] Alumina powder was used as the ceramic powder. Alumina powder having a specific surface area of 7 m ² Zg was used as a powder to be used as a material for molding the outer peripheral portion, and an alumina powder having a specific surface area of 5 m ² Zg was used as a powder to be used as a material for molding the center portion.

In this example, in order to adjust the porosity of the central portion, a specific surface area of 5 m ² In addition to alumina powder of / g, alumina powder having a specific surface area of 7 m ² / g was mixed to prepare a molding material forming the center part.

[0071] The composition of each molding material is as follows.

Molding material of the outer circumferential portion: alumina powder (specific surface area 7m ² / g) 55vol% + organic binder 45 vol% central molding material: alumina powder (specific surface 5m ² / g) 45vol% + alumina powder (specific surface area 7m ² / g) 15vol% + organic binder 40vol%

[0072] Each molding material was injection-molded, and as shown in Fig. 1, a molded body at the outer peripheral portion (a cylindrical hollow body with a diameter of 10 mm having a cavity with a diameter of 3 mm at the center) and a molded body at the center ( A cylinder with a diameter of 3 mm) was produced. The molding temperature was 180 ° C. The molded product at the center part was inserted into the molded product at the outer peripheral part and combined, and an acrylic resin diluted with a solvent was applied to the inserted part. The combined molded body was degreased at a maximum temperature of 400> atmosphere, and the degreased body was sintered at a maximum temperature of 1200> atmosphere. The density of the obtained sintered body was as follows, and the boundary surface between the central portion and the outer peripheral portion was welded. Sintering relative density Peripheral part: 89%, central part: 85%

[0073] In Comparative Example 2, the difference in the sintered relative density between the outer peripheral portion and the central portion was less than 5%, and it was impossible to obtain a desired sintered product.

Claims

The scope of the claims

[1] A sintered product in which parts having different sintered relative densities coexist, and the interface between the parts is integrated by sintering.

[2] A method for producing a sintered metal product in which parts having different sintered relative densities coexist,

It includes the steps of injection molding, degreasing and sintering molding materials X and Y into desired shapes using a two-color molding machine,

The molding material X contains metal powder A having an average particle size of 30 / m or less, and the molding material Y is made of the same material as the powder A, and the average particle size is 20 β m from the powder A. Containing a larger metal powder Β,

A method characterized by.

[3] A method for producing a sintered ceramic product in which parts having different sintered relative densities coexist, and molding materials X ′ and Y ′ are each injection molded into a desired shape using a two-color molding machine.

Including degreasing and sintering processes,

The molding material Y ′ is made of the same material as the powder C, and contains a ceramic powder D having a BET specific surface area smaller than the powder C by 3 m ² Zg or more.

A method characterized by.