WO2023203892A1

WO2023203892A1 - Method for manufacturing titanium compact and method for manufacturing titanium sintered body

Info

Publication number: WO2023203892A1
Application number: PCT/JP2023/007918
Authority: WO
Inventors: 昌志早川
Original assignee: 東邦チタニウム株式会社
Priority date: 2022-04-21
Filing date: 2023-03-02
Publication date: 2023-10-26
Also published as: JP2023160150A

Abstract

In a method for manufacturing a titanium compact 1 according to the present invention, the titanium compact 1 has a hollow body part 2 in which there is formed an internal space 2b that includes an opening part 2a opening to the outside, and plate parts 3 that are provided so as to stand on an inner surface 2c of the hollow body part 2 facing the internal space 2b and that extend on the inner surface 2c. The manufacturing method includes: a step for placing a core material 61, for forming the internal space 2b, in a core material placement space in a mold 51 made of a resin; a step for filling a molding space 52 of the mold 51 with a raw material powder 71; and a step for performing cold isostatic pressing, at a pressing force of 300 MPa or above, on the mold 51 in which the molding space 52 is filled with the material powder 71, in a state in which the core material 61 is placed in the core material placement space. A core-material-constituting material having a consistency of 50 or above is used as the core material 61.

Description

Method for manufacturing titanium-based green compact and method for manufacturing titanium-based sintered body

The present invention relates to a method for producing a titanium-based green compact and a method for producing a titanium-based sintered body.

For example, titanium and titanium alloys are being considered for use in various parts because of certain excellent properties such as fatigue resistance, corrosion resistance, light weight, and high specific strength.
However, manufacturing parts made of titanium or titanium alloys generally involves a number of steps such as melting by electron beam melting or vacuum arc melting, casting, and in some cases further hot rolling, heat treatment and machining, and welding. This increases manufacturing costs. Due to such high costs, it cannot be said that the scope of application of titanium and titanium alloys has been sufficiently expanded.

Under these circumstances, in recent years, so-called near-net shapes have been developed by filling raw material powder containing titanium into a resin mold and applying cold isostatic pressure to the raw material powder to form a predetermined shape. Powder metallurgy methods for obtaining titanium-based green compacts are attracting attention. In the powder metallurgy method, after cold isostatic pressing, the material may be heated and sintered as necessary to increase the density.

By the way, some parts made of titanium or titanium alloy have an internal space or a recessed part including an opening to the outside. In order to produce a titanium-based green compact having such an internal space using the powder metallurgy method, a core material is placed in a position corresponding to the internal space of the mold, and the mold, whose forming space is filled with raw material powder, is cooled. Apply isostatic pressure for a while.

Regarding this, Patent Document 1 states, ``Production of a hollow structure obtained by immersing a sintered body having a base material and a core made of an iron-based material in an acid solution to dissolve and remove the core. In the method, the base material is made of a material nobler than the iron-based material constituting the core, and the base material is formed with a non-conductive coating on at least a part of the surface of the base material. A method for manufacturing a hollow structure comprising a film forming step that reduces the surface that comes into contact with an acid solution has been proposed. An example of the "hollow structure" is an "impeller (pump impeller)."

Further, Patent Document 2 describes a method for manufacturing a metal green compact having a recess, in which a resin mold having a shape corresponding to the recess is placed in a position corresponding to the recess of a resin mold. A method for producing a green compact comprising the step of applying cold isostatic pressure to the raw material powder filled in the mold with the core material positioned in the mold. According to the method described in Patent Document 2, "it is possible to suppress the occurrence of bulges on the surface of the green compact near the core material."

Although the material is not titanium or titanium alloy, there are techniques related to green compacts, such as those described in Patent Documents 3 and 4. Patent Document 3 states, ``When performing cold isostatic pressure molding by enclosing powder in a mold, storing it in a pressure vessel, and applying isostatic pressure using a liquid such as water as a pressure medium, A method for cold isostatic pressure molding of powder, characterized in that a mold made of a viscoplastic material is used as the mold. Patent Document 4 states, ``In a method of manufacturing a green compact by molding raw powder, a cavity of a desired shape is provided in a mold made of a semi-solid material with a consistency of 15 to 300, and a cavity of a desired shape is formed in the cavity. "A method for producing a green compact, which comprises filling the powder raw material with pressure, and then pressurizing the powder raw material using the mold as a pressure medium."

Japanese Patent Application Publication No. 2016-17218 International Publication No. 2021/060363 Japanese Unexamined Patent Publication No. 63-219503 Japanese Patent Application Publication No. 2003-154494

When using a highly rigid core material such as the "core made of iron-based material" described in Patent Document 1, the core material hardly undergoes elastic deformation during cold isostatic pressurization. Differences may occur in the transmission of pressurizing force in the raw material powder, which may result in insufficient compaction. As a result, in the case of a highly rigid core material, the surface near the core material may bulge, and as a result, it may not be possible to satisfactorily produce a titanium-based green compact having a predetermined shape. In addition, the method described in Patent Document 1 requires "immersing a sintered body having a base material and a core made of an iron-based material in an acid solution to dissolve and remove the core." However, it is difficult to say that titanium-based green compacts can be easily produced.

On the other hand, in the manufacturing method described in Patent Document 2, since a core material made of resin is used, the protrusion of the surface near the core material in the titanium-based powder compact formed after cold isostatic pressing is suppressed. can do. Moreover, the resin core material can be relatively easily taken out from the titanium-based powder compact after cold isostatic pressing.

By the way, parts made of titanium or titanium alloy have a more complicated shape, such as a closed impeller, in which a plate part such as a blade part is provided upright on the inner surface facing the internal space including the opening to the outside. There is something. Such a titanium-based green compact having a plate portion provided in the internal space may not be manufactured even if a resin core material is placed in a mold for cold isostatic pressing.

Patent Documents 3 and 4 do not consider producing a titanium-based compact having a plate portion in the internal space as described above.

An object of the present invention is to provide a method for manufacturing a titanium-based green compact that can relatively easily produce a titanium-based green compact having a predetermined complicated shape, and a method for producing a titanium-based sintered body. There is a particular thing.

As a result of intensive studies, the inventor found that if a core component material with a consistency of 50 or higher is used as the core material placed in a resin mold, titanium-based powder compacts with a plate section erected in the internal space can be obtained. It has been found that it can be produced satisfactorily. For materials with a consistency of less than 50 and poor fluidity, springback of the core material when the load is unloaded by cold isostatic pressing may cause the plate part, which is thin to some extent, of titanium-based powder compacts to It is assumed that it will be easily damaged. By using a core constituent material having a consistency of 50 or more, damage to the plate portion is suppressed, and it becomes possible to manufacture a titanium-based green compact having the plate portion. Moreover, the core material constituent material having a consistency of 50 or more can be easily taken out from the titanium-based green compact after cold isostatic pressing.

(1) The method for producing a titanium-based green compact according to the present invention is such that the titanium-based powder green body has a hollow main body portion forming an internal space including an opening to the outside, and a hollow main body portion having an internal space including an opening to the outside. and a plate portion that is provided upright on a facing inner surface and extends on the inner surface, and the manufacturing method includes a step of arranging a core material forming the inner space in a core material arrangement space of a resin mold; filling the molding space of the mold with raw material powder, and applying a pressure of 300 MPa or more to the mold with the molding space filled with the raw material powder with the core material arranged in the core material arrangement space; The method includes a step of performing cold isostatic pressurization in a step, and a core material constituting material having a consistency of 50 or more is used as the core material.

(2) In the method for producing a titanium-based green compact according to item (1) above, it is preferable that the core constituent material has a consistency of 60 or more and 240 or less.

(3) In the method for producing a titanium-based green compact according to item (1) or (2) above, it is preferable that the core constituent material contains a polybutene resin or clay.

(4) In the method for producing a titanium-based powder compact according to any one of (1) to (3) above, in the titanium-based powder compact for an impeller, the hollow main body portions are spaced apart from each other. A casing portion including a pair of disk-shaped portions arranged to provide the internal space therebetween, and the plate portion is oriented radially outward from the center of the disk-shaped portion between the disk-shaped portions. The blade portion may extend straight or include curved and/or bent portions.

(5) In the method for producing a titanium-based green compact according to item (4) above, the titanium-based green compact has a cross section perpendicular to the central axis including the plate portion of the titanium-based green compact, The ratio of the length corresponding to the thickness of the plate portion to the total length of each space portion located on both sides of the plate portion in the circumferential direction on a perpendicular line perpendicular to the extending direction of the plate portion is 0.05. There may be a portion in the titanium-based powder compact where the value is above and below 0.25.

(6) In the method for producing a titanium green compact according to any one of (1) to (5) above, the mold is made of a thermoplastic resin having a Shore D hardness within the range of 30 to 120. It is preferable to use a mold consisting of:
(7) In the method for producing a titanium green compact described in (6) above, it is preferable to use a mold made of a thermoplastic resin having a Shore D hardness in the range of 30 to 85.
(8) In the method for producing a titanium green compact according to any one of (1) to (7) above, the thickness of the mold is preferably 0.5 mm to 2.0 mm.

(9) In the method for producing a titanium-based powder compact according to any one of (1) to (8) above, the mold may be a mold produced using a three-dimensional modeling device. .

(10) The method for producing a titanium-based sintered body of the present invention is a method for producing a titanium-based powder compact produced by the method for producing a titanium-based powder compact according to any one of (1) to (9) above. This includes a sintering step of heating and sintering.

According to the method for producing a titanium-based powder compact of the present invention, a titanium-based powder compact having a predetermined complicated shape can be produced relatively easily.

1 is a perspective view showing an example of a titanium-based powder compact that can be manufactured by a manufacturing method according to an embodiment of the present invention. 2(a) is a plan view of the titanium-based compact shown in FIG. 1, and FIG. 2(b) is a cross-sectional view taken along line bb in FIG. 2(a). FIG. 3(a) is a side view of the titanium-based compact shown in FIG. 1, and FIG. 3(b) is a cross-sectional view taken along line bb in FIG. 3(a). FIG. 4(a) is a sectional view taken along the central axis line, showing a mold and core material that can be used for manufacturing the titanium-based compact shown in FIG. FIG. 3 is a cross-sectional view taken along line bb. FIG. 5 is a cross-sectional view taken along the central axis line, schematically showing a state in which cold isostatic pressing is performed using the mold and core material of FIG. 4 . FIG. 3 is a perspective view showing another example of a titanium-based powder compact that can be manufactured by the manufacturing method according to one embodiment of the present invention. 7(a) is a plan view of the titanium-based powder compact of FIG. 6, and FIG. 7(b) is a sectional view taken along line bb of FIG. 7(a). FIG. 8(a) is a side view of the titanium-based powder compact of FIG. 6, and FIG. 8(b) is a sectional view taken along line bb of FIG. 8(a). It is a perspective view showing still another example of the titanium-based green compact which can be manufactured by the manufacturing method concerning one embodiment of this invention. 10(a) is a plan view of the titanium-based compact shown in FIG. 9, and FIG. 10(b) is a sectional view taken along line bb in FIG. 10(a). 11(a) is a side view of the titanium-based green compact shown in FIG. 9, and FIG. 11(b) is a sectional view taken along line bb in FIG. 11(a). It is a perspective view showing still another example of the titanium-based green compact which can be manufactured by the manufacturing method concerning one embodiment of this invention. 13(a) is a plan view of the titanium-based powder compact of FIG. 12, and FIG. 13(b) is a sectional view taken along line bb of FIG. 13(a). 14(a) is a side view of the titanium-based powder compact of FIG. 12, and FIG. 14(b) is a sectional view taken along the line bb of FIG. 14(a). It is a perspective view showing still another example of the titanium-based green compact which can be manufactured by the manufacturing method concerning one embodiment of this invention. 16(a) is a plan view of the titanium-based compact shown in FIG. 15, and FIG. 16(b) is a cross-sectional view taken along line bb in FIG. 16(a). 16 is a side view of the titanium-based powder compact of FIG. 15. FIG.

Embodiments of the present invention will be described in detail below with reference to the drawings.
In the method for producing a titanium-based powder compact according to one embodiment of the present invention, a titanium-based powder compact 1 is provided with a plate portion 3 in an internal space 2b including an opening 2a, as illustrated in FIGS. 1 to 3. etc. Note that the term "titanium-based" herein includes not only pure titanium but also titanium alloys.

In order to manufacture the titanium-based powder compact 1 in which the plate portion 3 is provided in the internal space 2b, in this embodiment, prior to cold isostatic pressing, the core material placement space of the resin mold is When arranging the core material forming the internal space, a material constituting the core material having a consistency of 50 or more is used as the core material.

A core made of core material with a consistency of 50 or higher has a relatively low viscosity and high fluidity, so when the load is removed after cold isostatic pressing, it will not have much springback. It is presumed that this prevents damage to the plate portion of the titanium-based green compact from occurring. Moreover, since the core material of the core material having a consistency of 50 or more has fluidity, it can be easily taken out from the titanium compact after cold isostatic pressing. As a result, a titanium-based green compact having a predetermined complicated shape can be produced relatively easily.

(Production method)
Here, as an example, a method for manufacturing the titanium-based powder compact 1 shown in FIGS. 1 to 3 will be explained in detail. This titanium-based powder compact 1 is provided upright on a hollow main body part 2 forming an internal space 2b including an opening 2a to the outside, and an inner surface 2c facing the inner space 2b of the hollow main body part 2, and the inner surface 2c It has a plate portion 3 extending above.

Here, the hollow main body part 2 includes a pair of disc-shaped

parts

4a and 4b arranged parallel to each other at intervals, and a disc-shaped part 4a extending parallel to the central axis between the disc-shaped

parts

4a and 4b. , 4b are included (see FIGS. 2 and 3). The internal space 2b is defined on the outer peripheral side of the connecting portion 5 between the disc-shaped

portions

4a and 4b, and is recessed from the outer surface of the hollow main body portion 2 and exists at a position deeper than the outer surface. This internal space 2b has an opening 2a to the outside between the outer peripheral surfaces of the disk-shaped

portions

4a and 4b of the outer surface of the hollow main body portion 2. In addition, the boundary between the outer end surface facing the outside of each disk-shaped

part

4a, 4b, and an outer peripheral surface can form the chamfered part 4c of the curved surface shape over the entire circumference as needed.

The plate portion 3 has an inner surface 2c facing the inner space 2b of the disc-shaped

parts

4a, 4b and facing the inner space 2b (more specifically, an inner end face of the disc-shaped

parts

4a, 4b facing the inner space 2b). It is set in. The number of plate portions 3 can be one or more, and in the illustrated example, there are six. Each plate portion 3 is formed integrally with the inner surface 2c (the inner end surface of each disc-shaped

portion

4a, 4b), and extends on the inner surface 2c in an upright position from the inner surface 2c.

In this example, the plurality of plate parts 3 are connected to a connecting part 5 at the center of the disc-shaped

parts

4a and 4b, and have a shape that extends straight radially outward from the connecting part 5. As shown in FIG. 3, the internal space 2b is divided into a corresponding number of space parts by a plurality of plate parts 3, and a plurality of openings are provided at the outermost radial direction of each space part. 2a exists.

The mold 51 for molding the titanium-based green compact 1 is provided with a molding space 52 having a shape corresponding to the shape of the titanium-based green compact 1, as shown in FIGS. 4(a) and (b). More specifically, this mold 51 includes a pair of hollow disc-shaped

walls

53a, 53b arranged at intervals, and a wall extending parallel to the central axis at the center between the disc-shaped

walls

53a, 53b. A hollow cylindrical wall 54 connected to the disc-shaped

walls

53a, 53b, and a hollow columnar wall 54 connected to each of the disc-shaped

walls

53a, 53b and the cylindrical wall 54 between the disc-shaped

walls

53a, 53b. It has a plurality of hollow plate-like wall portions 55 extending radially.

In the illustrated mold 51, a molding space 52 is defined inside the hollow disc-shaped

walls

53a, 53b, the cylindrical wall 54, and the plate-shaped wall 55. The disk-shaped

parts

4a and 4b of the titanium-based powder compact 1 are connected on the forming surfaces inside the disk-

like walls

53a and 53b, and the titanium-based powder compact 1 is connected on the forming surface inside the columnar wall 54. The plate portion 3 of the titanium-based powder compact 1 is formed at the portion 5 and the molding surface inside the plate-like wall portion 55, respectively. In addition, in this mold 51, a through hole 53c used for supplying the raw material powder 71 to the molding space 52 is provided in the center portion of the outside of one disk-shaped wall portion 53a, but the through hole is not provided in the other part of the mold. It may be provided in some parts. Further, the number of through holes 53c is not limited to one, but may be plural.

The mold 51 is made of resin, preferably thermoplastic resin, and is particularly preferably made of acrylic resin, elastomer-containing acrylic resin, polylactic acid (PLA) resin, or the like. The resin mold 51 is preferably made of a thermoplastic resin with a Shore D hardness within the range of 30 to 120 in order to ensure the required strength and maintain its shape even when filling the raw material powder 71. It may also be a thermoplastic resin having a molecular weight within the range of 30 to 85. Shore D hardness can be measured by a test method based on JIS K7215 (1986). From the same viewpoint, the thickness of the resin mold 51 is preferably 0.5 mm to 2.0 mm.

Although the resin mold 51 can be produced by various methods, it is preferably produced using a three-dimensional modeling device (so-called 3D printer). Thereby, molds 51 of various shapes can be easily produced. The modeling method of the three-dimensional printer is not particularly limited, and may be any one of, for example, a stereolithography method, an inkjet method, an inkjet powder layering method, a powder sintering layered manufacturing method, a hot melt layering method, or a powder fixation method.

As the raw material powder 71 to be filled into the molding space 52 of the mold 51, various powders such as titanium powder, alloying element powder, mother alloy powder, etc. can be used in combination as necessary. This titanium powder includes pure titanium powder consisting essentially only of titanium, titanium hydride powder mainly containing titanium, and containing hydrogen in an amount of 5% by mass or less. The pure titanium powder may be, for example, a hydride-dehydrogenated powder obtained by dehydrogenating titanium hydride powder. In addition, when the raw material powder 71 contains titanium hydride powder, it is desirable to perform a step of heating and sintering the titanium-based powder compact 1 as described later. Further, the above-mentioned alloying element powder means a powder containing a single alloying element of a titanium alloy, and the mother alloy powder means a powder containing a plurality of elements. The raw material powder 71 may be, for example, only titanium powder, or may include titanium powder, an alloying element powder selected from the group consisting of iron, aluminum, vanadium, zirconium, tin, molybdenum, copper, and nickel, and/or powder. Alternatively, a mixture of two or more types of master alloy powders may be used. Alternatively, it is also possible to use only a powder containing titanium and an alloying element as the raw material powder 71. Note that pure titanium means titanium having a titanium content of 99% by mass or more. The mass ratio of the alloying element to titanium in the raw material powder 71 may be in the range of 0 to 0.33, for example, 0 to 0.11, where titanium is 1.

The average particle size of the raw material powder 71 is preferably 10 μm to 150 μm. By using such relatively fine particles, it is possible to improve the compressed density of the titanium-based green compact after cold isostatic pressing and furthermore of the titanium-based sintered body after heating. The average particle diameter means the particle diameter D50 (median diameter) of the particle size distribution (volume basis) obtained by a laser diffraction scattering method. As the raw material powder 71, known powders such as crushed powder and atomized powder can be used.

In order to manufacture the titanium-based powder compact 1 using the mold 51 and the raw material powder 71, a core material 61 is placed in the core arrangement space of the mold 51 to form the internal space 2b of the titanium-based powder compact 1. Place. As shown in FIG. 4, between the pair of disc-shaped

walls

53a and 53b in the mold 51, a core material is formed in the space between the circumferentially adjacent plate-shaped walls 55 on the outer peripheral side of the columnar wall 54. 61 is arranged, and this space corresponds to the core material arrangement space. The core material having flowability can be filled by pouring into the core material arrangement space from the opening to the outside around the core material arrangement space, whereby the core material 61 is arranged in the core material arrangement space. be done. After arranging the core material 61, the opening of the core material arrangement space can be closed with a sealing member 56, such as a plate, to seal the core material arrangement space (see FIG. 5).

Furthermore, before or after the step of arranging the core material 61 in the core material arrangement space of the mold 51, the raw material powder 71 is filled into the molding space 52 of the mold 51 through the through hole 53c. After filling the molding space 52 with the raw material powder 71, a plate-shaped lid member 57 made of, for example, substantially the same material as the mold 51 is provided in the through hole 53c, thereby sealing the molding space 52. (See Figure 5).

Note that the process of arranging the core material 61 in the core material arrangement space and the process of filling the molding space 52 of the mold 51 with the raw material powder 71 may be performed in any order, and either process may be performed first. Further, instead of the lid member 57 provided in the through hole 53c and/or the sealing member 56 that closes the opening of the core material arrangement space, the entire mold may be covered with a bag-like covering member, although not shown. . In this case, if necessary, the interior of the covering member surrounding the mold may be depressurized before the cold isostatic press described below.

Thereafter, with the core material 61 arranged in the core material arrangement space, the mold 51 with the raw material powder 71 filled in the molding space 52 is subjected to cold isostatic pressure in a cold isostatic pressure device. CIP). Here, as shown in FIG. 5, the mold 51 is pressurized from the outside. Note that the sealing member 56 and the lid member 57 constitute a part of the mold 51, and pressure is applied to the sealing member 56 and the lid member 57 from the outside. As the mold 51 is pressurized, the raw material powder 71 in the molding space 52 of the mold 51 is compressed and compacted, and becomes the titanium-based compact 1 .

In cold isostatic pressurization, the mold 51 is pressurized with isostatic pressure (hydrostatic pressure, etc.) by the surrounding fluid, regardless of its shape. Therefore, by cold isostatic pressing, the titanium-based powder compact 1 can be manufactured using molds 51 of various shapes.

The pressure applied to the mold 51 by cold isostatic pressing is 300 MPa or more, preferably 400 MPa or more. If the pressing force is less than 300 MPa, the raw material powder 71 will not be sufficiently compressed, and the shape accuracy of the titanium-based compact 1 will become insufficient. The pressing force may be, for example, 750 MPa or less, or 600 MPa or less, and typically 500 MPa or less. Further, the holding time under such pressure may be, for example, 0.5 minutes to 30 minutes.

After the cold isostatic pressing step, the titanium-based powder compact 1 is taken out together with the mold 51 and the core material 61 from the cold isostatic pressing device. Thereafter, the mold 51 and the core material 61 are removed from the titanium-based compact 1. At this time, since the core material 61 has fluidity, it can be easily removed. Depending on the type of core material forming the core material 61, the core material 61 may be taken out together with a part of the mold 51. Note that the mold 51 may be heated to about 100° C. in the atmosphere to soften it before removal, if necessary. Thereby, the titanium-based green compact 1 can be manufactured.

When producing a titanium-based sintered body, a step of heating the titanium-based compact 1 is performed after the cold isostatic pressing step. When the titanium-based green compact 1 is heated, the particles constituting it are sintered to become a titanium-based sintered body. Note that the manufactured titanium-based green compact and titanium-based sintered body can be subjected to further processing such as cutting and polishing.

In this step, the titanium-based powder compact 1 can be heated without pressure at a temperature of, for example, 1200° C. to 1300° C. for 1 hour to 3 hours. Alternatively or additionally, hot isostatic pressing (HIP) is applied to the titanium-based green compact 1, and argon gas An isostatic pressure of about 100 MPa to 200 MPa may be applied for 30 minutes to 180 minutes using a pressure medium such as gas.

A titanium-based sintered body can be produced by pressureless heating and/or hot isostatic pressing. When both pressureless heating and hot isostatic pressing are performed, the order is not particularly limited, but for example, hot isostatic pressing can be performed after pressureless heating.

In the manufacturing method as described above, the core material 61 arranged in the core material arrangement space of the mold 51 is made of a core material constituting material having a consistency of 50 or more.

If the consistency of the core material constituent material is 50 or more, the core material 61 exhibits a certain degree of low viscosity and high fluidity. 51. When such a core material 61 is used, the titanium-based powder compact 1 tends to be less likely to be damaged after cold isostatic pressing. This is because the consistency of the core material constituent material is 50 or more, so that the core material 61, which has appropriate viscosity and fluidity, does not recover so much when the load of cold isostatic pressing is removed. It is assumed that this is due to the following. If a core material 61 made of a core material having a consistency of less than 50 is used, a large springback of the core material 61 may occur when the load of cold isostatic pressing is removed. As a result, the relatively thin plate portion 3 of the titanium-based powder compact 1 that is adjacent to the core material 61 with the plate-like wall portion 55 interposed therebetween is likely to be damaged.

Until now, when manufacturing a titanium-based powder compact 1 in which the plate portion 3 exists in the internal space 2b, it was necessary to weld the plate portion 3 because cutting the internal space 2b was difficult. . However, since titanium and titanium alloys easily combine with oxygen, there is a problem that when the plate portion 3 is joined by welding, the welded portion tends to contain oxygen and has different mechanical properties from other parts. In contrast, the embodiments described above do not require welding and have the advantage that such problems do not occur.

Moreover, the core material 61 whose core material constituting material has a consistency of 50 or more can be filled and arranged in core material arrangement spaces of various shapes because of its fluidity. Therefore, by using such a core material 61, titanium-based powder compacts 1 having internal spaces 2b of various shapes can be manufactured.

In general, a material constituting the core material whose consistency does not change is used; however, in the case of a material constituting the core material whose consistency can change due to hardening due to heat, etc., immediately before filling the core material arrangement space of the mold 51. , and the consistency of the core constituent material immediately after being taken out from the titanium-based powder compact 1 may all be 50 or more. Even if the consistency of the core component material before filling into the core material placement space is 50 or more, if the consistency becomes less than 50 due to hardening after filling, cold isostatic pressure is applied. Springback of the core material may occur when unloading.

The consistency of the core constituent material is preferably 60 or more and 240 or less. When the consistency is 60 or more, damage to the titanium-based powder compact 1 as described above can be suppressed even more effectively. On the other hand, when the consistency is set to 240 or less, contamination of the titanium-based powder compact 1 due to adhesion of the core material 61 or penetration into the interior when the core material 61 is removed from the titanium-based powder compact 1 can be suppressed. . If the core material constituent material adheres to or permeates into the titanium-based green compact 1, the concentration of oxygen, carbon, nitrogen, etc. increases locally during subsequent sintering, and the mechanical properties of the titanium-based sintered body deteriorate. There are concerns about this. Moreover, if the consistency is appropriate, it becomes easy to fill the core material into the core material arrangement space and to take it out from there.

The consistency of the core material is measured using a standard cone in accordance with JIS K2220:2013.

Specific examples of core material constituent materials include polybutene resin, clay, and the like. Clay is an aggregate of artificial or natural soil or particles containing soil, sand, oil, pulp, etc. and having a predetermined adhesive property, such as oil clay.

(Titanium-based green compact)
According to the manufacturing method of the embodiment described above, the titanium-based powder compact 1 shown in FIGS. 1 to 3 can be manufactured. The specific structure of this titanium-based powder compact 1 is as described above, and its explanation will be omitted.

The titanium-based powder compact 1 is made of titanium made of pure titanium, or made of Ti-5Al-1Fe, Ti-5Al-2Fe, Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr. It may be made of a titanium alloy such as -2Mo, Ti-6Al-2Sn-4Zr-6Mo, or Ti-10V-2Fe-3Al. In addition, in the components of the titanium alloy listed here, the number attached before each alloy element symbol means the content (mass %). For example, "Ti-6Al-4V" represents a titanium alloy containing 6% by mass of Al and 4% by mass of V.

What can be manufactured is not limited to the titanium-based compact 1 shown in FIGS. 1 to 3. In addition, it is also possible to manufacture, for example, the titanium-based powder compact 11 shown in FIGS. 6 to 8, the titanium-based powder compact 21 shown in FIGS. 9 to 11, or the titanium-based powder compact 31 shown in FIGS. 12 to 14. be.

The titanium-based powder compact 11 shown in FIGS. 6 to 8 does not have a portion corresponding to the connecting portion 5 of the titanium-based powder compact 1 shown in FIGS. It has almost the same structure as the titanium-based powder compact 1, except that it is ring-shaped with a through hole 15 connected to the gap between the titanium-based powder compact 1 and the disc-shaped part 14b. The through hole portion 15 constitutes a part of the internal space 12b, and an opening portion 15a to the outside is also present on the outer end surface side of the disk-shaped portion 14a (see FIGS. 6 and 7). Note that the pair of disk-shaped

portions

14a and 14b are connected to each other by a plate portion 13 between them.

The titanium-based powder compact 21 shown in FIGS. 9 to 11 has a connecting portion 25 having a larger diameter than the connecting portion 5 of the titanium-based powder compact 1 in FIGS. 1 to 3, and each plate portion 23 is , extends radially outward from the center of the disc-shaped

portions

24a, 24b, including a curved portion that protrudes toward one side in the circumferential direction (counterclockwise in FIG. 11(b)). Except for this, it has almost the same configuration as the titanium-based powder compact 1. In this titanium-based powder compact 21, the entire plate portion 23 is a curved portion. However, although not shown in the drawings, the plate portion may partially include at least one curved portion instead of the entire plate portion.

The titanium-based powder compact 31 shown in FIGS. 12 to 14 has a connecting portion 35 having a larger diameter than the connecting portion 5 of the titanium-based powder compact 1 in FIGS. 1 to 3, and each plate portion 33 has a , has almost the same structure as the titanium-based powder compact 1, except that it extends radially outward from the center of the disc-shaped

portions

34a and 34b, including at least one bent point. In the illustrated titanium-based powder compact 31, each plate portion 33 has a plurality of bending points, and as shown in FIG. It has a zigzag shape with alternate locations and bent locations protruding to the other side. Note that a corner portion 33 a is formed on the outer surface of the columnar connecting portion 35 by connecting with an end portion of the zigzag plate portion 33 .

Although not shown, the curved portions included in the plate portion 23 of the titanium-based powder compact 21 shown in FIGS. 9 to 11 and the plate portion 33 of the titanium-based powder compact 31 shown in FIGS. 12 to 14 It is also possible to have a plate portion that has both such bending points.

The titanium-based

powder compacts

1, 11, 21, and 31 shown in FIGS. 1 to 14 can be used as an impeller such as a closed impeller. In these titanium-based

powder compacts

1, 11, 21, 31, the pair of disc-shaped

parts

4a, 4b, 14a, 14b, 24a, 24b, 34a, 34b and the connecting

parts

5, 25, 35 are the casing part of the impeller. corresponds to In each of the titanium-based

powder compacts

1, 11, 21, and 31, the casing portion includes a pair of disk-shaped

portions

4a, 4b, 14a, 14b, 24a, 24b, 34a, and 34b. Furthermore, the

plate portions

3, 13, 23, and 33 of the titanium-based

powder compacts

1, 11, 21, and 31 correspond to the blade portions of the impeller.

In such titanium-based

powder compacts

1, 11, 21, and 31 for impellers, the

plate portions

3, 13, 23, and 33, which are blade portions existing in the

internal spaces

2b, 12b, 22b, and 32b, are relatively thick. May be thin.

This point will be explained using the titanium-based powder compact 1 shown in FIGS. 1 to 3 as an example. When viewed in a cross section including the portion 3 and perpendicular to the central axis, the thickness of the plate portion 3 occupies a small proportion or area in the internal space 2b. More specifically, in the above-mentioned cross section, the titanium-based powder compact 1 has a plate portion in the circumferential direction on a perpendicular line PL (indicated by a broken line in FIG. 3(b)) perpendicular to the direction in which the plate portion 3 extends. The ratio (Lt/Ls) of the length Lt corresponding to the thickness of the plate portion 3 to the total length (Ls) of the lengths (Ls/2) in each space portion located on both sides of the plate portion 3 is, for example, 0.05 or more and There may be locations where the value is 0.25 or less. It is not necessary that the entire plate portion of the titanium-based powder compact has the above ratio (Lt/Ls). If there is a portion where the above ratio (Lt/Ls) is 0.05 or more and 0.25 or less in at least a part of the plate part, the titanium-based compacted powder has a portion where the ratio (Lt/Ls) is Applies to the body.

The length of each space portion on both sides in the circumferential direction of the plate portion 3 is as shown in FIG. means the length in the direction along the perpendicular line PL from the side surface of the plate section 3 to the side surface of another plate section. Alternatively, although not shown, if there is an inner surface facing the internal space on the side across the space of the plate, the length in the perpendicular direction from the side of the plate to the inner surface is corresponds to the length of each spatial portion on both sides of .

As described above, the ratio (Lt/Ls) between the length Lt corresponding to the thickness of the plate portion 3 and the total length (Ls) of the space portions on both sides in the circumferential direction is 0.05 or more and 0.25 A titanium-based powder compact 1 having the following locations tends to be easily damaged due to the springback of the core material 61 mentioned above during its manufacture. In contrast, according to this embodiment, by using a predetermined core constituent material, even such a titanium-based powder compact 1 can be manufactured satisfactorily while suppressing damage to the plate portion 3. be able to.

By the way, according to the embodiment of the present invention, not only the titanium-based

powder compacts

1, 11, 21, and 31 for impellers, but also the titanium-based powder compacts 41 for other uses shown in FIGS. 15 to 17 can be manufactured. can.

The titanium-based powder compact 41 shown in FIGS. 15 to 17 is provided upright on a hollow main body 42 forming an internal space 42b including an opening 42a to the outside, and on an inner surface 42c of the hollow main body 42 facing the internal space 42b. , and three plate portions 43 extending on the inner surface 42c.

Here, the hollow main body 42 has a pair of disc-shaped

parts

44a and 44b arranged at intervals, which are connected to each other by a cylindrical connecting part 45 extending along the central axis. . The internal space 42b is recessed from the outer surface of the hollow main body portion 42 and is defined by the pair of disc-shaped

portions

44a, 44b and the inner surface of the connecting portion 45 on the inner space 42b side.

In addition, in the illustrated example, each plate portion 43 provided around the cylindrical connecting portion 45 extends in the circumferential direction on the inner surface 42c facing the internal space 42b side of the connecting portion 45, and has a radial radius. It has a circular plate shape whose thickness gradually decreases toward the outside. Note that the number of plate portions 43 can be changed as appropriate, and may be one, two, or four or more.

Although the titanium-based green compact 41 shown in FIGS. 15 to 17 is not intended for use in an impeller, it can be manufactured using this embodiment in order to be molded without causing damage to the plate portion 43 provided in the internal space 42b. can.

Next, the method for producing a titanium-based green compact of the present invention was carried out on a trial basis, and its effects were confirmed, which will be described below. However, the description here is for the purpose of mere illustration, and is not intended to be limiting.

By applying cold isostatic pressure to the raw material powder, we attempted to produce titanium-based powder compacts A as shown in FIGS. 1 to 3 and titanium-based powder compacts B as shown in FIGS. 9 to 11, respectively. The titanium-based powder compact A has a length in each space portion located on both sides of the plate portion in the circumferential direction on a perpendicular line perpendicular to the extending direction of the plate portion in a cross section including the plate portion and perpendicular to the central axis. The minimum value of the ratio (Lt/Ls) of the length Lt corresponding to the thickness of the plate portion to the total length Ls is 0.05. Further, the minimum value of the similar ratio (Lt/Ls) in the titanium-based green compact B is 0.09.

In Examples 1 to 8 and Comparative Examples 1 to 3, titanium compacts were produced. Hydrodehydrogenation powder (HDH powder) was used as the raw material powder in Examples 1 to 7 and Comparative Examples 1 to 3. In Example 8, a mixture of HDH powder and titanium hydride powder at a mass ratio of 1:1 was used. The above HDH powder had a titanium content of 99% by mass or more and an average particle size of 66 μm. Further, the titanium hydride powder had a titanium content of 95% by mass or more, a hydrogen content of 5% by mass or less, and an average particle size of 66 μm.

In Example 9, a powder compact made of titanium alloy was produced, and a mixture of the above HDH powder and 60Al40V powder at a mass ratio of 9:1 was used as the raw material powder. The above 60Al40V powder was produced by crushing an ingot, contained 60% by mass of aluminum and 40% by mass of vanadium, and had an average particle size of 35 μm.

The mold used for manufacturing was modeled using a 3D printer. The resin material constituting the mold was polylactic acid (PLA), and had a Shore D hardness of 83. The thickness of the mold was 1.0 mm. Each core material constituent material shown in Table 1 was used for the core material arranged in the core material arrangement space of the mold. In Table 1, "putty for air conditioner piping" is made of polybutene resin. The consistency of the core constituent material was measured in accordance with JIS K2220:2013, as described above. However, since the silicone sealant of Comparative Example 1 hardens over time, and the carbon steel of Comparative Example 2 and the thermosetting resin of Comparative Example 3 do not have fluidity at room temperature, the consistency was could not be measured. From this, it can be considered that Comparative Examples 1 to 3 are hard materials and have a consistency of clearly less than 50.

After placing the core material in the above mold and filling it with raw material powder, the entire mold is wrapped in a plastic bag, the inside of the mold is depressurized, and then hydrostatic pressure is applied in a cold isostatic pressurizer. Cold isostatic pressing (CIP) was performed. In the cold isostatic pressing, a pressing force of 490 MPa was applied to the mold filled with the raw material powder for 1 minute. After cold isostatic pressing, the mold was taken out of the plastic bag, and most of the core material was removed manually. The mold was then heated to about 100° C. in air to soften it. Thereafter, the mold was removed from the titanium compact inside using a tool such as pliers.

The titanium-based green compact produced in this way was visually observed to check for damage, adhesion of the core material, and penetration into the interior. The results are shown in Table 1.

In Examples 1 to 9, no breakage occurred in any of the titanium-based powder compacts A and B. On the other hand, in Comparative Examples 1 and 3, in both titanium-based powder compacts A and B, the plate portion (blade portion) was broken after being taken out from the mold. In Comparative Example 2, titanium-based powder compact B could not be manufactured because a core material made of carbon steel was used. In addition, in the titanium-based green compacts A and B of Examples 4 to 6, the core material constituent material adhered and penetrated into the interior during the removal operation from the mold. On the other hand, in the titanium-based powder compacts A and B of Examples 1 to 3 and 7 to 9, there was no such adhesion or penetration of the core constituent material. In addition, especially in Examples 1 to 3 and 7 to 9, it was easy to fill and remove the core material from the core material arrangement space.

From the above, it was found that according to the manufacturing method of the present invention, a titanium-based green compact having a complicated shape can be manufactured relatively easily.

1, 11, 21, 31, 41 Titanium-based compact 2, 12, 22, 32, 42 Hollow

main body

2a, 12a, 15a, 22a, 32a,

42a Opening

2b, 12b, 22b, 32b,

42b Internal space

2c, 12c, 22c, 32c,

42c Inner surface

3, 13, 23, 33, 43 Plate portion

33a Corner portion

4a, 4b, 14a, 14b, 24a, 24b, 34a, 34b, 44a, 44b Disc-shaped

portion

4c, 14c, 24c, 34c,

44c Chamfered portion

5, 25, 35, 45 Connecting portion 15 Through-hole portion 51 Mold 52 Molding space 53a Disc-shaped wall portion 53b Disc-shaped wall portion 53c Through-hole 54 Column-shaped wall portion 55 Plate-shaped wall portion 56 Sealing Member 57 Lid member 61 Core material 71 Raw material powder PL Perpendicular line perpendicular to the extending direction of the plate portion Ls Total length in the space on both circumferential sides of the plate portion Lt Length equivalent to the thickness of the plate portion

Claims

A method for producing a titanium green compact, the method comprising:
A hollow main body part in which the titanium-based powder compact forms an internal space including an opening to the outside, and a plate part provided upright on an inner surface facing the inner space of the hollow main body part and extending on the inner surface. has
The manufacturing method includes a step of arranging a core material forming the internal space in a core material arrangement space of a resin mold, a step of filling the molding space of the mold with raw material powder, and a step of filling the core material arrangement space in the core material arrangement space. with the core material arranged, applying cold isostatic pressure to the mold filled with the raw material powder in the molding space at a pressure of 300 MPa or more,
A method for producing a titanium-based powder compact, using a core constituent material having a consistency of 50 or more as the core material.
The method for producing a titanium-based powder compact according to claim 1, wherein the core constituent material has a consistency of 60 or more and 240 or less.
The method for producing a titanium-based green compact according to claim 1 or 2, wherein the core constituent material contains a polybutene resin or clay.
The titanium-based green compact is for an impeller,
The hollow main body portion is a casing portion including a pair of disc-shaped portions spaced apart from each other and having the internal space therebetween;
Claim: The plate portion is a blade portion that extends between the disc-shaped portions from the center of the disc-shaped portions toward the outside in the radial direction, either straight or including curved portions and/or bent portions. A method for producing a titanium-based green compact according to any one of 1 to 3.
In each space portion located on both sides of the plate portion in the circumferential direction on a perpendicular line perpendicular to the extending direction of the plate portion in a cross section including the plate portion of the titanium-based compact and perpendicular to the central axis. The titanium-based powder body according to claim 4, wherein the titanium-based powder compact has a portion where the ratio of the length corresponding to the thickness of the plate portion to the total length is 0.05 or more and 0.25 or less. Method for producing green compacts.
The method for producing a titanium-based green compact according to any one of claims 1 to 5, wherein a mold made of a thermoplastic resin having a Shore D hardness in the range of 30 to 120 is used as the mold.
The method for producing a titanium-based green compact according to claim 6, wherein a mold made of a thermoplastic resin having a Shore D hardness in the range of 30 to 85 is used as the mold.
The method for producing a titanium green compact according to any one of claims 1 to 7, wherein the thickness of the mold is 0.5 mm to 2.0 mm.
The method for producing a titanium-based green compact according to any one of claims 1 to 8, wherein a mold produced using a three-dimensional modeling device is used as the mold.
A method for manufacturing a titanium-based sintered body, the method comprising:
Production of a titanium-based sintered body, comprising a sintering step of heating and sintering a titanium-based green compact produced by the method for producing a titanium-based green compact according to any one of claims 1 to 9. Method.