JPH0196303A - Method for degassing capsule for hot isostatic pressurization device - Google Patents

Abstract

PURPOSE:To enable easy and quick dehydration of a compactly packed work up to the corners thereof by making deaeration through a porous body provided in a capsule. CONSTITUTION:A vacuum chamber 1 has a vent hole 2 communicating with a vacuum pump and the capsule 3 made of a metal or glass has a top cap 4. The gas in the capsule is discharged and deaerated from the spacing 5 formed between the circumferential edge of the top cap 4 and the capsule 3 into the vacuum chamber 1. The cup-shaped porous body 6 into which the work 7 such as powder or sintered powder body is fitted into the inside wall of the capsule 3. The efficient deaeration is executable even in hardly deaeratable parts 8 of the work 7 having, for example, an inverted T shape in section.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for filling powder into capsules made of metal or glass, etc., and processing the powder with a hot isostatic pressing device (hereinafter referred to as HIP). This relates to a method of degassing at times.

(Conventional technology) When performing HIP treatment on powder and powder sintered bodies.

Since the pressure medium of HIP is gas, it is not possible to pressurize the processed product if there is a through hole to the inside. Therefore, the HIP treatment is usually performed by placing the processed product in a capsule and vacuum shielding it, but if gas remains in the capsule, it may cause pores or a decrease in strength. Particularly in the case of HIP treatment of active metals such as Ti alloys and superalloys, this degassing treatment is an important treatment.

This degassing process is carried out, for example, by drawing a vacuum from one part of the exhaust pipe of capsule a in Figure 6, but since the powder is packed quite densely, the degassing near the corner e in Figure 6 is sufficient. The problem was that I couldn't do it.

Conventional examples of this degassing treatment include the following.

1) Figure 3 shows an exhaust pipe attached to the top of capsule a.
This was connected to a vacuum pump for deaeration, and then the exhaust pipe was closed.

2) In Figure 4, air was removed from the gap d between the capsule a and the upper cover C, and then the gap d was closed by electron beam welding.

3) A method in which a gas passage communicating vertically is provided on the inner wall surface of the capsule, and gas is vacuum-suctioned from the top of the capsule through this gas passage (Japanese Patent Laid-Open Publication No. 17102/1983).

Regarding methods 1) and 2), both have a deaeration port only in the upper part of the capsule, and it is difficult to perform sufficient vacuum deaeration of the lower part of the capsule in a short time.

Regarding method 3), it is not easy to provide a gas flow path on the inner surface of the capsule, and the cost increases.
Even if such a gas flow path is provided, the effect cannot be expected to be much.

(Problem to be Solved by the Invention) This degassing process had a problem in that the lower part of the capsule could not be sufficiently degassed because the powder was packed quite densely inside the capsule. The object of the present invention is to provide a method that can perform degassing treatment in such places in a short time and reliably, and can create a sufficient degree of vacuum.

(Solution by the Invention) In powder metallurgy, in which a porous material such as powder is filled into a capsule, vacuum shielded, and then sintered, a porous body is provided inside the capsule, and complete vacuum degassing is performed through the porous body. I made it possible to do so.

(Example) An explanation will be given based on FIG. 1. A vacuum chamber 1 has a deaeration port 2 communicating with a vacuum pump. Reference numeral 3 denotes a capsule made of metal or glass, which is provided with a capsule upper lid 4, and the gas inside the capsule is discharged and degassed into the vacuum chamber 1 through a gap 5 formed between the periphery of the upper lid 4 and the capsule. Reference numeral 6 denotes a pot-shaped porous body filled with a processed product 7 such as powder or powder sintered body, which is fitted into the inner wall of the capsule 3.

This porous body 6 does not have to be in the shape of a pot, and may be a combination of a disk-shaped bottom and a cylindrical wall. Or maybe capsule 3
When the porous body 6 has a fence shape, the porous body 6 corresponds to this.
It may also be a combination of an integral fence shape or a square bottom and a square cylindrical wall, or a combination of all top surfaces.

In addition, when vacuum degassing is performed with an exhaust pipe attached, and when the porous body 6 is made of the same material as the processed product 7, the porous body 6 is not on the inner wall surface of the capsule 3 as shown in Fig. 2, but inside the capsule 3. It is also possible to provide the porous body 6 in the portion connected to the exhaust pipe.

The porous body 6 fitted inside the capsule 3 is required to have the following characteristics.

a) It has pores (uniform, connected pores of several microns or more) that are large enough not to cause problems during vacuum degassing; b) Since it is processed at high temperature and high pressure, it must be processed under such conditions. Do not cause harmful phenomena such as melting, reaction, or diffusion with product 7 (preferably, the same material as the treated product).

C) The layer thickness may be arbitrary, but at least it has a thickness that does not impair its effectiveness as a gas flow path, and it has a lower density than treated product 7 (if the porosity is large, the degree of vacuum will be 1
(The amount of deformation becomes large when it reaches 00%), so it must be thick enough to cause healthy deformation; however, it is not desirable to be too generous.

d) The strength of the porous body is as long as it maintains its shape until it is vacuum shielded, so press, cold isostatic press equipment i! (
CIP) etc. that remain pressed together.

Alternatively, it may be made of any material such as sintered material.

e) Any raw material for the porous body may be used, such as beads, wire, or a thin plate made with holes made using a punching press: a laser, or the like.

f) Due to high pressure, the capsule undergoes considerable deformation. Therefore, it must be able to follow the amount of deformation or must not inhibit the pressure or deformation.

g) The shape of the porous body is arbitrary, and it is desirable that it can be adapted to areas that are particularly difficult to degas due to the shape of the capsule. For example, even if the processed product has a chevron-shaped cross section as shown in FIG. 5, by providing a corresponding porous layer, it is possible to efficiently deaerate the gas even at the portion 8 in FIG. 1.

(Effects) Since the porous body is inserted into the capsule, when vacuum shielding is performed, degassing can be easily and quickly carried out to the corners of the densely packed processed product through the porous body.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of an apparatus for carrying out the method of the present invention. FIG. 2 also shows a second example. FIG. 3 is a cross-sectional view of a case where a porous body is provided inside a capsule with a complicated shape. Figures 4 and 5 illustrate a conventional degassing method. Figure 6 is a cross-sectional view showing incomplete degassing in the conventional degassing method. Processed product (concretions, etc.) 8 Degassing female part of complex-shaped capsules Applicant Sumitomo Heavy Industries, Ltd. Sub-agent Patent attorney Isamu Ohashi Figure 1 Figure 3 Figure 2 Figure 4

Claims (1)

[Claims] 1) In powder metallurgy, in which a porous material such as powder is filled into a capsule, vacuum shielded, and then heated, a porous body is provided inside the capsule, and degassing is performed through the porous body. Features: A method for degassing capsules for hot isostatic pressurization equipment. 2) The method for degassing a capsule for a hot isostatic pressurizing device according to claim 1, wherein the porous body has uniform communicating pores of several microns or more. 3) A capsule for a hot isostatic pressurizing device according to claim 1, wherein the porous body is made of a material that does not melt, react, or diffuse with the processed product under high temperature and high pressure. Degassing method. 4) A method for degassing a capsule for a hot isostatic pressurizing device according to claim 1, wherein the porous material is made of beads, wires, or thin plates with holes.