JPH05443B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) [HIP]
(Hot Isostatic Pressing)
The present invention relates to a capsule for sintering by treatment and a method for manufacturing the same.

(Prior Art) When sintering metal powder or alloy powder by HIP processing, first a step is required to encapsulate the powder in a container, that is, a capsule. This process is generally called a canning process.

Conventionally, this canning process involves filling the capsule body with metal or alloy powder, placing it in a vacuum container, and vacuum-sealing the capsule by electron beam welding while degassing the capsule at room temperature. It had been taken.

With these conventional canning methods, the inside of the capsule is not sufficiently degassed, and especially volatile contaminants (including moisture) cannot be completely removed. Even if the process was carried out, it was not possible to produce the desired sintered metal with a 100% success rate.

(Objective of the Invention) An object of the present invention is to provide a powder capsule and its manufacturing method for manufacturing sintered metal with a 100% success rate by HIP treatment by eliminating the drawbacks of the prior art described above. That is.

(Structure of the Invention) In order to achieve the above object, the present inventors analyzed the causes of conventional canning methods and conducted repeated research. It was discovered that if the pressure is reduced while heating to a high temperature below the melting point of the powder, the inside of the capsule can be sufficiently degassed, and volatile contaminants such as moisture can be completely eliminated. Furthermore, considering that conventional electron beam welding is impossible at high temperatures, we conducted extensive research to find a new and simple sealing method for how to seal the capsules in this vacuum-degassed state. . As a result, the brazing material is melted using the high temperature under reduced pressure and degassing, and the lid body is vacuum-brazed and sealed to the capsule, and the brazed part is melted during the HIP process in the next step. It has been found that it is possible to maintain such a state by welding the cover.

The resulting encapsulated capsule is completely degassed and contains no volatile contaminants, allowing it to maintain an extremely clean environment, and maintain this ideal encapsulation state even during subsequent HIP processing. be able to. Moreover, in this canning process, an ideal encapsulated capsule is obtained as described above, but at the same time, the quality of the sintered product after HIP processing is affected because the metal powder or alloy powder inside the capsule is temporarily sintered in a vacuum. The present invention was made based on the knowledge that the performance can also be improved.

The present invention will be explained in detail below based on examples.

Powders that can be treated according to the present invention are not particularly limited, but heavy metals and alloys thereof are preferred. In the case of metal powder whose surface is easily oxidized, it is preferable to reduce the surface by flowing a reducing gas at a temperature below the melting point of the brazing material before the canning process.

The metal powder is obtained by conventional means. An example of this is as follows. The molten metal obtained by melting metal or alloy in a high-frequency induction furnace is poured into a tundish, and the molten metal falling from the bottom of the tundish is pulverized and rapidly cooled by blowing a high-pressure nitrogen gas jet to obtain a spherical powder.

The capsule can have an appropriate shape and structure, such as a box shape or a cylindrical shape, and an example thereof will be explained with reference to the drawings.

1 and 2 are diagrams showing the capsule manufacturing process according to an embodiment of the method of the present invention, in which 1 is the capsule body, 2 is the metal powder or alloy powder filled therein, and 4 is the inner cover. An inner lid 5 is provided to cover the opening. 6 is a paste-like or powder-like brazing material placed on the periphery of the inner lid 5, and 7 is an outer cover. Note that 3 is a plate for preventing contamination of the brazing material, which is provided as necessary.

To seal the capsule, the capsule body 1 is filled with the metal powder or alloy powder to be treated, and if necessary, a contamination prevention plate 3 is placed on the powder surface. Next, the edge of the inner cover 4 and the edge of the capsule body 1 are welded together by TIG welding, and then the brazing material 6 is placed on the periphery of the inner lid 5. Next, this capsule is placed in a vacuum heating furnace (not shown) to be heated and degassed. When a predetermined temperature and pressure are reached, the brazing filler metal 6 melts due to the high temperature, and the inner lid 5 and inner cover 4
are vacuum brazed.

At this time, heating temperature, heating time, pressure (degree of vacuum)
Conditions such as these are determined on a case-by-case basis depending on the type and particle size of the powder to be treated. The sealing temperature by vacuum brazing can be determined depending on the type of brazing material. For example, BNi-5 is 1150℃, BCu-1 is 1100℃.
℃, BAu-11 is 1000℃, BAg-8 is 850℃. The upper limit of the degassing temperature can be set in advance depending on the type of brazing filler metal.

Next, after taking the capsule out of the furnace, the second
As shown in the figure, the outer cover 7 is placed on the inner cover 4 and the edges are TIG welded.

Thereafter, the capsules are subjected to HIP treatment.
By welding the outer cover 7, the HIP processing temperature can select a sintering temperature suitable for the powder, regardless of the melting point of the brazing filler metal 6. Even if the soldered parts melt at the HIP treatment temperature, the outer cover 7
Since the wax is welded, the cleanliness of the capsule can be maintained as it is, and even if the wax melts and flows out into the opening, the contamination prevention plate 3 can prevent the powder 2 from being contaminated.

According to the invention, a high degree of reliability (nearly 100%)
The powder can be degassed and the state can be maintained during the next HIP process. Furthermore, even metals that are easily oxidized can be degassed with a high degree of reliability by extending the reducing gas into the vacuum heating furnace at a temperature below the melting point of the brazing material.

Furthermore, according to the present invention, the powder to be treated is pre-sintered before the HIP treatment, which, together with degassing before the HIP treatment, makes it possible to obtain high-quality products after the HIP treatment. .

Further, according to the present invention, the degassing capacity is greater due to the high temperature treatment compared to the conventional method, and therefore the degassing time can be significantly shortened.

Further, according to the present invention, a large number of capsules can be vacuum-sealed at once in a vacuum heating furnace, so in addition to the many advantages mentioned above, an extremely significant cost reduction can be achieved.

Next, one embodiment of the present invention will be described.

(Example) Super alloy (Cr18.6%, Fe18.5%,
NrBal.) was melted in a high-frequency induction furnace, the resulting molten metal was poured into a tundish, and the molten metal flowing from the bottom of the tundish was pulverized by spraying a high-pressure nitrogen gas jet to obtain alloy powder.

This was filled into the capsule body shown in Figure 1, the powder surface was covered with a contamination prevention plate, and an inner cover was welded to the inside of the capsule body by TIG welding.

Next, after placing the brazing material BNi-2 (use temperature 1010-1177℃) on the periphery of the inner lid that covers the opening of the inner cover, the obtained capsules are placed in a vacuum heating furnace.
Degassed under reduced pressure at 1050°C. During degassing, the inner lid was brazed under vacuum. Thereafter, the capsule was quickly taken out of the furnace and an outer cover was welded by TIG welding.

Then, the capsules produced in this way are
Charged into HIP treatment furnace and under argon gas atmosphere.
It was heated and compressed at 1100℃ and 1000ar pressure. this
Repeated 10 times. The resulting product has a density of 8.20~
8.23g/cm ³ (=8.22g/cm ³ ), no defects were observed in the capsules, and all products had a 100% success rate.
HIP processed.

(Comparative Example) The crushed super alloy used in the above example was used as a sample. This was filled into the capsule body, degassed at room temperature, and the cover was welded to the capsule body using electron beam welding. The obtained capsules were heated at 1100°C under an argon gas atmosphere according to the above example.
It was HIPed and heated and compressed under a pressure of 1000 bar. When this process was repeated 10 times, 20% of all products were found to be defective.

[Brief explanation of the drawing]

Each figure is an explanatory diagram showing the capsule manufacturing process according to an embodiment of the method of the present invention, in which Fig. 1 is a vertical cross-sectional view of the capsule before vacuum sealing, and Fig. 2 is a longitudinal sectional view of the capsule after vacuum sealing with an outer cover. FIG. 3 is a longitudinal cross-sectional view of the welded state. 1... Capsule body, 2... Metal or alloy powder, 3... Contamination prevention plate, 4... Inner cover, 5...
... Inner lid, 6... Brazing metal (brazing part), 7... Outer cover.

Claims (1)

[Claims] 1. A capsule body is filled with metal powder or alloy powder, then an inner cover having an opening is welded to the capsule body, the opening is covered with an inner lid, and a brazing material is placed. After that, the powder is charged into a vacuum heating furnace, and the inner cover is vacuum-sealed to the opening of the inner cover by vacuum brazing while degassing at a high temperature below the melting point of the powder, and then the outer cover is welded. A method for producing a powder sintered capsule for HIR processing, characterized in that: 2. A capsule for HIP processing consisting of a capsule main body and a cover welded to the main body, which is filled with metal powder or alloy powder and sintered, and the cover consists of an outer cover and an inner cover provided with an opening. A powder sintered capsule for HIP processing, characterized in that the inner lid provided to cover the opening is vacuum-sealed by vacuum brazing.