JP2709002B2 - Sintering method using glass capsule - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a raw material powder compact encapsulated in a glass capsule under a high-temperature isostatic pressing condition such as a hot isostatic pressing (HIP) or a self-heating combustion method. To a sintering method for forming a compact sintered body.

[0002]

2. Description of the Related Art As shown in FIGS.
The P device (1) places an airtight container (11) on a lower lid (10) and covers the airtight container with an upper lid (12).
0) on the support (13), the support is insulated mantle (1).
Around 4), a heater (15) is provided, and a gas inlet (16) is provided on the upper lid so that the raw material powder compact can be isotropically sintered at high temperature and high gas pressure. It is a device to make.

A raw material powder compact such as ceramics is degassed and sealed in a glass capsule.
A sintering method for forming a sintered body in an IP device is known. In this sintering method, a glass capsule (22) containing a raw material powder compact (20) is placed on a support (13) of a HIP device (1),
After evacuating the inside of the apparatus, a high-pressure inert gas such as Ar is introduced from the inlet (16) of the upper lid (12) and heated to a predetermined sintering temperature by the heater (15) to perform sintering. Things.

[0004] Conventionally, as shown in FIG.
The glass capsule (22) containing (20) was placed directly on the support (13) for sintering. Glass capsule (22)
Melts at a high temperature and becomes a fluid molten glass (24),
As shown in FIG. 7, even during sintering, the molten glass (24) completely covers the raw material powder compact (20) and plays a role in maintaining the hermetically sealed state of the raw material compact. Since the raw material powder compact is subjected to the high-pressure action of the inert gas through the glass melt film, it is compacted into a dense sintered compact.

However, when a substance having a large specific gravity such as a metal is used as a raw material powder, when the glass capsule is melted at a high temperature, the molten glass (24) at the bottom is pushed out by the weight of the raw material molded body. . For this reason, as shown in FIG. 8, the raw material powder compact (20) and the support (1
The amount of the molten glass (24) existing between 3) is very small. As a result, a cavity as indicated by reference numeral (26) is formed, and the sealed state of the raw material powder molded body (20) cannot be maintained. Since the raw material powder compact itself contains a large number of voids, it cannot be molded into a dense sintered compact no matter how much pressure is applied in an unsealed state. As described above, when the raw material powder is a substance having a large specific gravity such as a metal, there is a problem that a dense sintered body cannot be manufactured by the sintering method using a glass capsule.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method capable of sintering into a completely dense body using a glass capsule even if the raw material powder is a substance having a large specific gravity such as a metal.

[0007]

[MEANS FOR SOLVING THE PROBLEMS] In a sintering method in which a raw material powder compact encapsulated in a glass capsule is sintered at a high temperature while being pressurized with an inert gas, a glass containing a raw material powder compact (20) Place the bottom of the capsule (22) on several supports (3
2) The capsule is placed on top, and sintering is performed by applying temperature and pressure while the bottom of the capsule is supported by each support with a small contact area.

The plurality of supports (32) may be any as long as they can support the bottom of the glass capsule with a small contact area, and may be in the form of a sphere, a truncated cone, or the like. Support (3
The number of 2) can be appropriately selected so that the bottom of the glass capsule can be stably supported.

The support (32) can be directly mounted on a support (13) such as a HIP device (1),
It is also possible to prepare a tray (30) to be placed on the (30) and deploy it in the tray (30).

[0010] The projecting height of the support (32) is a glass capsule.
It is desirable that the thickness be substantially the same as the thickness of (32), but there is no particular limitation.

[0011]

After evacuating the inside of the apparatus, a high-pressure inert gas such as Ar is introduced from a gas inlet (16) and heated to a predetermined sintering temperature. The glass capsule (22) melts at a high temperature to become a flowable molten glass (24), and moves downward by the weight of the raw material molded body (20). For this reason, the thickness of the glass melt film (24) gradually decreases in the portion of the capsule bottom that was initially supported by each support, and finally comes into contact with each support (32).

However, since the contact area of the contact portion between the raw material compact (20) and the support (32) is small, the contact portion is immediately wrapped in the molten glass by the action of the surface tension of the molten glass, and the raw material compact is Thus, the sealed state is maintained.

When the number of the supports (32) is increased,
Since the distance between the supports is narrowed, the molten glass at the bottom of the capsule is filled between the supports, and the sealed state of the raw material molded article becomes strong. On the other hand, even when the number of supports is small, as shown in FIG. 2, a part of the molten glass comes into contact with the base of the tray (30), so that the sealed state of the raw material molded body can be reliably maintained.

The raw material compact (20) is made of the glass molten film (24)
, A dense sintered body is formed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a support (32) is provided in a tray (30) will be described. The tray (30) is, as shown in FIG.
It has a circular base (33), and a vertical wall (34) protrudes from the edge. The vertical wall (34) serves to stop the flow of the molten glass as described later, and is therefore preferably provided in advance.

As the support (32), a commercially available refractory ball is used. Therefore, a recess (35) for receiving the ball (32) is formed in the base (33) of the tray as shown in FIG. When the support (32) is directly provided on the support (13) of the HIP device, the recess (35) may be formed on the support (13).

The shape of the base (33) of the tray (30) is not limited to a circular shape, but can be appropriately selected according to the shape of the sintered body. In addition, the support (32) is not limited to the ball, but may be any as long as it can support the bottom of the glass capsule with a small contact area.
For example, as shown in FIG. 5, a tapered projection (32) may be protruded from the base (33).

The sintering method of the present invention was applied to sintering of Cr powder. Note that Cr powder is a raw material that has not been successfully sintered by the sintering method using a glass capsule because of its large specific gravity.

Pressure molding of a Cr powder having an average particle size of 40 μm,
A raw material powder compact (20) having a diameter of 30 mm and a height of 50 mm was prepared.
Next, this raw material powder compact was sealed in Pyrex glass having a thickness of 3 to 5 mm. For the tray (30), a disk with a thickness of 5 mm and a diameter of 55 mm is prepared from a carbon material, and a 5 mm
The vertical wall (34) of the above was used. As the support (32), 30 balls of Al ₂ O _{3 having} a diameter of 3 mm are used, and they are respectively disposed in the recesses (35) of the tray (30).

As shown in FIG. 1, a support for the HIP device (1)
A tray (30) is placed on (13), and a glass capsule (2) enclosing a raw material powder compact (20) is placed on a support (32) in the tray.
Place 4).

As described above, after the inside of the HIP device (1) is evacuated to a vacuum, Ar gas is introduced from the inlet (16) of the upper lid (12) and heated to the sintering temperature by the heater (15). . Gas pressure
1000 atm and sintering temperature was 1300 ° C.

Since the glass capsule (22) is melted into a fluid molten glass (24), as shown in FIG.
It is pushed out by its own weight of (20). As a result, the raw material molded body (20) moves downward, and the thickness of the molten glass (24) gradually decreases at the bottom of the capsule initially supported by each support, and finally each ball (32) Contact with. However, since the contact area between the raw material compact (20) and the ball (32) is small, the molten glass immediately envelops the contact portion by the action of surface tension. Further, since the glass molten film between the supports remains as it is, the raw material molded body remains sealed with the molten glass.

Further, since the tray (30) is provided with the vertical wall (34), the outflow of the molten glass can be prevented.

According to the above method, the raw material powder compact (20)
Could be formed into a dense sintered body. This is because, during sintering, the raw material powder compact (20) was sealed by the glass melt film (24), and the high pressure action of Ar gas could be received through the glass melt film.

[0025]

According to the sintering method using a glass capsule, even when the raw material powder is a substance having a large specific gravity such as a metal, it can be sintered into a completely dense body.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a sintering method of the present invention.

FIG. 2 is a diagram illustrating a flow state of molten glass in the sintering method of the present invention.

FIG. 3 is a perspective view showing one embodiment of a tray and a support used in the sintering method of the present invention.

FIG. 4 is a sectional view of the embodiment shown in FIG. 3;

FIG. 5 is a sectional view of another embodiment of the tray and the support.

FIG. 6 is a diagram illustrating a conventional sintering method.

FIG. 7 is a view for explaining a flow state of molten glass when a specific gravity of raw material powder is small in a conventional sintering method.

FIG. 8 is a diagram illustrating a flow state of molten glass when a specific gravity of raw material powder is large in a conventional sintering method.

[Explanation of symbols]

 (1) HIP device (13) Support base (20) Raw material powder compact (22) Glass capsule (24) Molten glass (30) Tray (32) Support

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuyoshi Nishida 2-4-7 Kyomachibori, Nishi-ku, Osaka-shi, Osaka Inside Chugai Furnace Industry Co., Ltd. (72) Inventor Toru Kawai 1-1-1, Nakamiya Oike, Hirakata-shi, Osaka No. 1 Inside Kubota Hirakata Factory (72) Inventor Bin Shinozaki 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture Inside Kubota Hirakata Factory (56) References JP-A-2-83271 (JP, A)

Claims (1)

(57) [Claims] 1. A sintering method for forming a raw material powder compact (20) encapsulated in a glass capsule (22) into a sintered body under high-temperature isostatic pressing conditions, comprising: Is placed on a plurality of supports (32), and the temperature and pressure are applied while the bottom of the capsule is supported by each support with a small contact area. Sintering method using a glass capsule.