JP2010275617A - Method for carburizing treatment of tantalum vessel and tantalum vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the enlargement of an opening part of a tantalum vessel due to a carburizing treatment when the tantalum vessel having the opening part is subjected to the carburizing treatment. <P>SOLUTION: There is provided a method for carburizing treatment of a tantalum vessel 1 which is made of tantalum or a tantalum alloy and has a bottom face part 1a, a side wall part 1b extending in a nearly vertical direction from the bottom face part 1a, and the opening part 1d formed by the end part 1c of the side wall part 1b, and the method subjects the tantalum vessel 1 to the carburizing treatment for infiltrating carbon toward inside from the surface of the vessel 1, and includes: a process for arranging the tantalum vessel 1 in a chamber 3 in which a carbon source exists so that the opening part 1d of the tantalum vessel 1 faces downward; and a carburizing treatment process for infiltrating carbon from the carbon source from the surface of the tantalum vessel 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for subjecting a tantalum container made of tantalum or a tantalum alloy to a carburizing treatment for infiltrating carbon from the surface of the container toward the inside thereof, and a tantalum container obtained by the method.

  Silicon carbide (SiC) is said to be able to realize high temperature, high frequency, withstand voltage and environmental resistance that cannot be achieved with conventional semiconductor materials such as silicon (Si) and barium arsenic (BaAs). It is expected as a semiconductor material for next-generation power devices and high-frequency devices.

  In Patent Document 1, tantalum having a tantalum carbide layer formed on the surface of a single crystal silicon carbide substrate is thermally annealed and a single crystal of silicon carbide is grown on a single crystal silicon carbide substrate. It has been proposed to use the container as a chamber. A single crystal silicon carbide substrate is housed in a tantalum container having a tantalum carbide layer on the surface, and the surface is planarized by thermally annealing the surface or growing a silicon carbide single crystal on the surface, In addition, it has been reported that a single crystal silicon carbide substrate or a silicon carbide single crystal layer with few defects can be formed.

In Patent Document 2 and Patent Document 3, when carbon is infiltrated into the surface of tantalum or a tantalum alloy to form carbide of tantalum on the surface, Ta ₂ O ₅ which is a natural oxide film on the surface is sublimated and removed. After that, it has been proposed to penetrate carbon.

  However, a specific carburizing method has not been studied for a tantalum container having an opening.

JP 2008-16691 A JP 2005-68002 A JP 2008-81362 A

  An object of the present invention is to provide a carburizing method for a tantalum container that can prevent the opening from being expanded by carburizing when a tantalum container having an opening is carburized, and a tantalum container that has been carburized by the method. It is to provide.

  The carburizing method of the present invention is a tantalum container made of tantalum or a tantalum alloy having a bottom surface portion and a side wall portion extending in a substantially vertical direction from the bottom surface portion, and an opening is formed by an end portion of the side wall portion. A method for performing a carburizing process in which carbon is infiltrated from the surface to the inside of the container, and the tantalum container is disposed in a chamber in which a carbon source exists so that an opening of the tantalum container is downward. The method includes a step and a step of performing a carburizing process by infiltrating carbon from a carbon source from the surface of the tantalum container by heating the chamber under reduced pressure.

  In the present invention, the tantalum container is disposed in the chamber so that the opening of the tantalum container is downward, and carburization is performed. When the tantalum container is placed in the chamber so that the opening of the tantalum container is on top and carburizing is performed, the opening of the tantalum container gradually expands as the carburizing process proceeds, and the There arises a problem that the lid made of tantalum or tantalum alloy cannot be closed. If the tantalum container and the lid are not properly fitted, the sealing inside the tantalum container cannot be maintained. This causes a problem that the silicon carbide single crystal cannot be processed or grown in a good state.

  ADVANTAGE OF THE INVENTION According to this invention, when carburizing a tantalum container which has an opening part, it can suppress that an opening part expands greatly by carburizing process. Further, distortion of the opening can be suppressed. For this reason, the fitting state with the lid placed on the tantalum container can be kept good, and the hermeticity in the container can be improved.

  In the present invention, the tantalum container is preferably arranged in the chamber so that a gap is formed below the end of the side wall of the tantalum container. By forming a gap below the end of the side wall of the tantalum container, carbon from the carbon source can be sufficiently supplied also to the inside of the tantalum container. For this reason, the carburizing process inside the tantalum container can be performed in the same manner as the outside of the tantalum container, and the carburizing process can be performed uniformly on the entire surface of the tantalum container.

  The gap below the end of the side wall of the tantalum container is preferably 1 mm or more, more preferably in the range of 2 mm to 20 mm, although it depends on the size and shape of the tantalum container. If the gap is too small, carbon cannot be sufficiently supplied to the inside of the tantalum container, and the carburizing treatment inside the tantalum container may be insufficient. Moreover, even if the gap becomes larger than the above upper limit value, the effect of increasing the gap beyond that cannot be obtained.

  In the present invention, a method of supporting the tantalum container in the chamber includes a method of supporting the bottom surface inside the tantalum container. Specifically, the bottom surface portion inside the tantalum container can be supported by a support member provided in the chamber.

  In the present invention, a carbon source is present in the chamber, but the chamber itself may function as the carbon source. As the carbon source, for example, graphite can be used. Therefore, it can function as a carbon source by using a chamber having at least a surface formed of graphite. Since the chamber is heat-treated at a high temperature, an isotropic graphite material is preferably used as the graphite. Further, a high-purity graphite material that has been subjected to high-purity treatment using a halogen-containing gas or the like is more preferable. The ash content in the graphite material is preferably 20 ppm or less, more preferably 5 ppm or less. The bulk density is preferably 1.6 or more, and more preferably 1.8 or more, so the upper limit of the density is, for example, 2.1. As an example of a method for producing isotropic graphite material, petroleum-based or coal-based coke is pulverized to several μm to several tens of μm as a filler, and a binder such as pitch, coal tar, coal tar pitch is added thereto. Knead. The obtained kneaded product is pulverized to several μm to several tens of μm so as to be larger than the pulverized particle size of the raw material filler to obtain a pulverized product. Moreover, it is preferable to remove particles whose particle diameter exceeds 100 μm. The pulverized product is molded, fired and graphitized to obtain a graphite material. Thereafter, a high-purity treatment is performed using a halogen-containing gas or the like, and the amount of ash in the graphite material is set to 20 ppm or less, whereby contamination of impurity elements from the graphite material into the tantalum container can be suppressed.

  In the present invention, a support member that is provided so as to be located inside the tantalum container and that supports the bottom surface portion inside the tantalum container may function as a carbon source. The support member provided inside the tantalum container functions as a carbon source, so that sufficient carbon can be supplied inside the tantalum container, and the surface inside the tantalum container is uniformly carburized in the same manner as the surface outside the tantalum container. can do.

  Examples of the supporting member that functions as a carbon source include a supporting member formed from the above graphite material.

  The tantalum container of the present invention is characterized by being carburized by the method of the present invention.

  According to the above method of the present invention, the carburizing treatment can suppress the opening of the tantalum container from expanding, and the distortion of the opening can be suppressed. Therefore, the tantalum container of the present invention is fitted with the lid. The combined state is good, and a tantalum container having high hermeticity can be obtained.

  According to the present invention, when carburizing a tantalum container having an opening, it is possible to suppress the opening from expanding due to the carburizing process and to suppress distortion of the opening. For this reason, the airtightness when the lid is fitted to the tantalum container can be enhanced.

Sectional drawing for demonstrating the carburizing method of one Embodiment according to this invention. The top view which shows the position of the support bar in embodiment shown in FIG. The perspective view which shows the tantalum container used in embodiment shown in FIG. The perspective view which shows the lid | cover used for the tantalum container shown in FIG. Sectional drawing of the tantalum container shown in FIG. Sectional drawing of the lid | cover shown in FIG. Sectional drawing which shows the state which attached the lid | cover shown in FIG. 6 to the tantalum container shown in FIG. Sectional drawing for demonstrating the carburizing method in a comparative example. The top view which shows the position of the graphite block in the comparative example shown in FIG. The figure which shows the position of the opening part of the tantalum container before the carburizing process in the Example according to this invention, and after a carburizing process. The figure which shows the position of the opening part of the tantalum container before the carburizing process in a comparative example, and after a carburizing process. Sectional drawing for demonstrating the carburizing process in the Example according to this invention.

  Hereinafter, the present invention will be described with reference to specific embodiments, but the present invention is not limited to the following embodiments.

  FIG. 1 is a cross-sectional view for explaining a carburizing method according to an embodiment of the present invention.

  The tantalum container 1 is disposed in a chamber 3 composed of a chamber container 3a and a chamber lid 3b.

  FIG. 3 is a perspective view showing the tantalum container 1. FIG. 4 is a perspective view showing a lid 2 made of tantalum or a tantalum alloy used for sealing the tantalum container 1 shown in FIG.

  FIG. 5 is a cross-sectional view showing the tantalum container 1. As shown in FIG. 5, the tantalum container 1 has a bottom surface portion 1a and side wall portions 1b extending from the periphery of the bottom surface portion 1a in a direction substantially perpendicular to the bottom surface portion 1a. An opening 1d of the tantalum container 1 is formed by the end 1c of the side wall 1b. Here, the “substantially vertical direction” includes a direction of 90 ° ± 20 °.

  6 is a cross-sectional view showing the lid 2 for sealing the opening 1d of the tantalum container 1 shown in FIG. As shown in FIG. 6, the lid 2 has an upper surface portion 2a and a side wall portion 2b extending from the upper surface portion 2a in a substantially vertical direction.

  7 is a cross-sectional view showing a state where the lid 2 shown in FIG. 6 is placed on the end 1c of the side wall 1b of the tantalum container 1 shown in FIG. 5 and the tantalum container 1 is sealed. As shown in FIG. 7, the side wall 1 b of the tantalum container 1 is arranged inside the side wall 2 b of the lid 2, so that the lid 2 is placed on the tantalum container 1 and the tantalum container 1 is sealed. The

  As shown in FIG. 7, since the side wall 1b of the tantalum container 1 is located inside the side wall 2b of the lid 2, the inner diameter D inside the side wall 2b of the lid 2 shown in FIG. It is designed to be slightly larger than the outer diameter d of the container 1. Usually, the inner diameter D of the lid 2 is designed to be about 0.1 mm to 4 mm larger than the outer diameter d of the tantalum container 1.

  The tantalum container 1 and the lid 2 are made of tantalum or a tantalum alloy. The tantalum alloy is an alloy containing tantalum as a main component, and examples thereof include an alloy containing tantalum metal containing tungsten or niobium.

  The tantalum container 1 and the lid 2 are manufactured by, for example, cutting, drawing from a thin plate, sheet metal processing, or the like. Cutting is a processing method in which a single piece of tantalum metal is cut into a container shape, and a high-precision shape can be manufactured. On the other hand, more metal is cut, resulting in higher material costs. Drawing is a processing method in which one tantalum metal plate is deformed to form a container at a time. When a plate-shaped metal is placed between a die for manufacturing a container and a punch and the punch is pushed toward the die, the material is deformed in a form of being pushed into the die and becomes a container. When the metal plate is pushed in, a wrinkle presser is installed so that the outer metal plate does not wrinkle. Compared with cutting, it is finished in a short time, and the generation of shavings is small, so that the cost and the like can be suppressed. Sheet metal processing is a processing method for forming a container shape by cutting, bending, or welding a single metal plate. Although cost can be reduced in terms of material compared to cutting, the manufacturing time is longer than drawing.

By carburizing each of the tantalum container 1 and the lid 2, carbon can be permeated into the inside from the surface, and the carbon can be diffused inside. When carbon penetrates, a Ta ₂ C layer, a TaC layer, or the like is formed.

  A tantalum carbide layer with a high carbon content is formed on the surface, but carbon diffuses into the container, so that the surface becomes a tantalum carbide layer with a high tantalum content, so that the carbon flux can be occluded.

  Therefore, carbon vapor generated during the growth process can be occluded in the crucible wall by performing liquid phase growth or vapor phase growth of silicon carbide in the crucible consisting of the carburized tantalum container and lid. In addition, a silicon atmosphere with a low impurity concentration can be formed, defects on the surface of the single crystal silicon carbide can be reduced, and the surface can be planarized. In addition, by annealing the surface of the single crystal silicon carbide substrate in such a crucible, defects can be reduced and the surface can be planarized.

  Returning to FIG. 1, the carburizing process of the present embodiment will be described.

  As shown in FIG. 1, the tantalum container 1 is arranged in a chamber 3 composed of a chamber container 3a and a chamber lid 3b. The tantalum container 1 is disposed in the chamber 3 so that the end 1c of the side wall 1b is downward. The tantalum container 1 is supported in the chamber 3 by supporting the bottom surface 1 a inside the tantalum container 1 with a plurality of support rods 6.

  FIG. 2 is a plan view showing an arrangement state of the support rods 6. As shown in FIG. 2, in the present embodiment, five support rods 6 support the bottom surface portion 1 a inside the tantalum container 1.

  As shown in FIG. 1, the tip of the support bar 6 is formed in a tapered shape with a tapered tip. By forming it in a tapered shape, the contact area between the support rod 6 and the bottom surface portion 1a of the tantalum container 1 is reduced, and defects in the carburizing process due to the contact of the support rod are reduced.

  As shown in FIG. 1, the support bar 6 is supported by a support base 5. In the present embodiment, a hole is formed in the support base 5, the lower end of the support bar 6 is inserted into the hole, and the support bar 6 is supported by the support base 5.

  In the present embodiment, the chamber 3, that is, the chamber container 3a and the chamber lid 3b, the support rod 6 and the support base 5 are formed of graphite. Therefore, in the present embodiment, the chamber 3, the support rod 6, and the support base 5 are carbon sources. The chamber 3, the support rod 6, and the support base 5 can be manufactured by cutting.

  It is preferable that the dimension shape of the chamber 3 is set so that the distance between the outer surface of the container 1 and the chamber 3 is substantially uniform as a whole. Thereby, the distance from the chamber which is a carbon source can be made substantially the same in the whole, and it can carburize uniformly throughout the whole.

  In addition, a gap G is preferably formed below the end 1 c of the side wall 1 b of the tantalum container 1. By forming the gap G, carbon can be supplied also from the outside of the tantalum container 1 to the inside of the tantalum container 1. As described above, the gap G is preferably in the range of 2 mm to 20 mm.

  Moreover, the support rod 6 and the support stand 5 which are arrange | positioned inside the tantalum container 1 function also as a carbon source as mentioned above. Therefore, as shown in FIG. 2, the support rods 6 are preferably arranged so as to be distributed almost evenly inside the tantalum container 1.

  As described above, the tantalum container 1 is disposed in the chamber 3, and the carburizing process can be performed by heating the chamber 3 after reducing the pressure in the chamber 3.

  The chamber 3 can be decompressed by disposing the chamber 3 in a vacuum vessel and exhausting the vacuum vessel. The pressure in the chamber 3 is reduced to 10 Pa or less, for example.

Next, the inside of the chamber 3 is heated to a predetermined temperature. As heating temperature, the range of 1700 degreeC or more is preferable, More preferably, it is the range of 1750 degreeC-2500 degreeC, More preferably, it is the range of 2000 degreeC-2200 degreeC. By heating to such a temperature, the pressure in the chamber 3 is generally about 10 ⁻² Pa to 10 Pa.

  The time for maintaining the predetermined temperature is preferably in the range of 0.1 to 8 hours, more preferably in the range of 0.5 to 5 hours, and further preferably in the range of 1 hour to 3 hours. It is. Since the carburizing speed varies depending on the holding temperature, the carburizing thickness is adjusted according to the target carburizing thickness.

  The rate of temperature rise and the rate of cooling are not particularly limited, but generally the rate of temperature rise is preferably in the range of 100 ° C./hour to 2000 ° C./hour, more preferably 300 ° C./hour to 1500 ° C./hour. More preferably, it is 500 ° C./hour to 1000 ° C./hour. The cooling rate is preferably in the range of 40 ° C./hour to 170 ° C./hour, more preferably 60 ° C./hour to 150 ° C./hour, and still more preferably 80 ° C./hour to 130 hours / hour. Cooling is generally performed by natural cooling.

  As shown in FIG. 1, the tantalum container 1 is placed in the chamber 3 so that the opening 1d of the tantalum container 1 is positioned downward, and carburizing treatment is performed in this state, so that the opening 1d expands and is distorted. Can be suppressed. For this reason, as shown in FIG. 7, when the lid 2 is placed on the tantalum container 1, the lid 2 can be placed in a well-fitted state, and the airtightness in the tantalum container 1 is kept good. Can do. For this reason, when thermal annealing or crystal growth is performed inside the tantalum container 1, the silicon vapor can be kept in a good state in the tantalum container 1, and a good crystal state can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to the following examples.

Example 1
The tantalum container 1 was carburized using the chamber 3 shown in FIG. As the tantalum container 1, a container having an outer diameter d of about 160 mm, a height h of about 60 mm, and a thickness t of about 3 mm shown in FIG. 3 was used. The tantalum container 1 was produced by processing metal tantalum into a sheet metal.

  As the chamber 3, a chamber 3 having a cylindrical shape with a diameter of 210 mm and a height of 90 mm was used. An isotropic graphite material having a bulk density of 1.8 was used as a material for the chamber container 3a and the chamber lid 3b.

  The support rod 6 had a diameter of 6 mm and a length of 75 mm. The length of the tapered portion at the tip is 15 mm. The support rod 6 and the support base 5 were formed from the same isotropic graphite material as the chamber container 3a.

  The gap G below the end 1c of the side wall 1b of the tantalum container 1 was 13 mm.

In this way, the tantalum container 1 was placed in the chamber 3, and the chamber 3 was placed in a SUS vacuum container 8 having a diameter of 800 mm × 800 mm. FIG. 12 is a cross-sectional view showing a state when the chamber 3 is arranged in the vacuum vessel 8. As shown in FIG. 12, a heat insulating material 9 is provided in the vacuum vessel 8, and the chamber 3 is disposed in a space 13 formed in the heat insulating material 9. As the heat insulating material 9, the brand name “DON-1000” (manufactured by Osaka Gas Chemical Co., Ltd., bulk density 0.16 g / cm ³ ) was used. This heat insulating material is a porous heat insulating material obtained by impregnating a pitch-based carbon fiber with a resin and molding, curing, carbonizing, and graphitizing.

  A carbon heater 12 is disposed above the space 13 surrounded by the heat insulating material 9, and the carbon heater 12 is supported by a graphite electrode 11 for flowing a current through the carbon heater 12. By passing an electric current through the carbon heater 12, the space 13 covered with the heat insulating material 9 can be heated.

  The vacuum vessel 8 is formed with an exhaust port 10 for exhausting the inside of the vacuum vessel 8. The exhaust port 10 is connected to a vacuum pump (not shown).

  After the inside of the vacuum vessel 8 was evacuated and the pressure inside the chamber 3 was reduced to 0.1 Pa or less, the inside of the chamber 3 was heated to 2150 ° C. at a temperature increase rate of 710 ° C./hour by the carbon heater 12. Carburizing treatment was performed by maintaining 2150 ° C. for 2 hours. The pressure in the chamber 3 was about 0.5 to 2.0 Pa.

  After the carburizing treatment, it was cooled to room temperature by natural cooling. The cooling time was about 15 hours.

  The outer diameter d was measured as the dimension of the opening 1d of the tantalum container 1 before and after the carburizing process. The dimension of the outer diameter d was measured at eight locations around the opening 1d.

  FIG. 10 is a diagram showing dimensions at the eight positions of the outer diameter d before and after the carburizing process. In FIG. 10, A shows the dimension before the carburizing process, and B shows the dimension after the carburizing process.

  As shown in FIG. 10, it can be seen that the outer diameter d is slightly reduced by carburizing in this example. Further, the roundness of the opening 1d was measured using a three-dimensional measuring machine. It calculated | required by the deviation from the measurement data of each point in eight places as shown in FIG. 10 of the opening part 1d, and the finally determined average element shape line. Specifically, the circular shape was recognized by the average line from the measurement data at each point, and the maximum difference in deviation from the average line at each point was defined as the roundness. The roundness of the opening 1d was 0.467 before the carburizing process and 0.575 after the carburizing process. Therefore, the difference before and after carburizing treatment was 0.108.

(Comparative Example 1)
FIG. 8 is a cross-sectional view for explaining the carburizing process in this comparative example.

  In this comparative example, the same chamber container 3a and chamber lid 3b as those in Example 1 were used. Moreover, the tantalum container 1 used the same thing as the said Example 1. FIG.

  In this comparative example, as shown in FIG. 8, the tantalum container 1 is disposed in the chamber 3 so that the opening 1 d of the tantalum container 1 faces upward.

  The tantalum container 1 is placed on a graphite block 7 placed on a support base 5.

  FIG. 9 is a plan view showing an arrangement state of the graphite block 7 with respect to the tantalum container 1. As shown in FIG. 9, the graphite block 7 is provided at each of four locations below the bottom surface portion 1 a of the tantalum container 1. As the graphite block 7, a rectangular parallelepiped having a length of 10 mm, a width of 30 mm, and a height of 10 mm was used. The graphite block 7 used was formed from the same material as the support rod 6 in Example 1. Moreover, the support stand 5 used the same thing as the support stand 5 of the said Example 1. FIG.

  As described above, the tantalum container 1 was placed in the chamber 3 and carburization was performed under the same conditions as in Example 1.

  In the same manner as described above, the dimension of the outer diameter d of the tantalum container 1 before and after the carburizing treatment was measured, and the measurement result is shown in FIG.

  In FIG. 11, A shows the dimension of the outer diameter d before carburizing treatment, and B shows the dimension of the outer diameter d after carburizing treatment.

  As shown in FIG. 11, in this comparative example, it can be seen that the opening 1d is expanded by carburizing.

  Further, the roundness of the opening 1d before and after the carburizing process was measured. The roundness before the carburizing treatment was 0.593, and the roundness after the carburizing treatment was 0.715. Therefore, the difference in roundness before carburizing and after carburizing was 0.122.

  As described above, in Comparative Example 1, it can be seen that the opening 1d expands as a result of performing the carburizing process by arranging the opening 1d of the tantalum container 1 to be on the upper side. Therefore, when the lid 2 is placed on the tantalum container 1 having the opening 1d expanded in this way, the fitting state between the tantalum container 1 and the lid 2 becomes poor, and a gap is formed between the tantalum container 1 and the lid 2. And cannot keep a good sealed state.

  On the other hand, as in Example 1, when the opening 1d does not expand, the lid 2 can be placed on the tantalum container 1 in a good sealed state. In the present embodiment, the opening 1d is slightly smaller after the carburizing process than before the carburizing process. However, in the case of the deformation in which the opening 1d becomes smaller, the sealing property is not impaired and the tantalum container 1 is not damaged. A lid 2 can be placed.

  When the opening 1d of the tantalum container 1 is expanded by carburizing treatment as in Comparative Example 1 above, the amount of expansion of the opening 1d is calculated in advance, and the lid 2 is made to fit such dimensions. It can be considered. However, since the amount of enlargement of the opening 1d varies depending on the carburizing condition and other conditions, and the amount of variation is large, even a lid manufactured in consideration of the dimensional change of the opening 1d is not necessarily tantalum. It does not necessarily match the opening 1d of the container 1 and may not provide good sealing performance. Accordingly, both the tantalum container 1 and the lid 2 become defective products, and the working efficiency is greatly reduced.

  Further, as described above, according to the present invention, the tantalum container is arranged so that the opening 1d faces downward, and carburizing is performed to obtain a high roundness of the opening. Also from this fact, by carburizing the tantalum container according to the present invention, it is possible to maintain a good sealed state in fitting with the lid.

DESCRIPTION OF SYMBOLS 1 ... Tantalum container 1a ... Bottom face part of tantalum container 1b ... Side wall part of tantalum container 1c ... End part of side wall part of tantalum container 1d ... Opening part of tantalum container 2 ... Lid 2a ... Upper surface part of lid 2b ... Side wall part of lid DESCRIPTION OF SYMBOLS 3 ... Chamber 3a ... Chamber container 3b ... Chamber lid 5 ... Support stand 6 ... Support rod 7 ... Graphite block 8 ... SUS vacuum container 9 ... Heat insulating material 10 ... Exhaust port 11 ... Graphite electrode 12 ... Carbon heater 13 ... Heat insulating material Space covered by

Claims (7)

A tantalum container made of tantalum or a tantalum alloy having a bottom surface portion and a side wall portion extending in a substantially vertical direction from the bottom surface portion, and having an opening formed by an end portion of the side wall portion. A method for performing a carburizing process to infiltrate carbon toward
Placing the tantalum container in a chamber in which a carbon source is present such that the opening of the tantalum container is downward;
A method of carburizing a tantalum container, comprising: depressurizing and heating the inside of the chamber to infiltrate carbon from the carbon source from the surface of the tantalum container and performing a carburizing process.   The tantalum container carburizing method according to claim 1, wherein the tantalum container is disposed in the chamber so that a gap is formed below the end portion of the side wall of the tantalum container.   3. The carburizing method for a tantalum container according to claim 1, wherein the tantalum container is supported in the chamber by supporting the bottom surface inside the tantalum container. 4.   The carburizing method for a tantalum container according to claim 3, wherein the bottom surface portion inside the tantalum container is supported by a support member provided in the chamber.   The said chamber functions as said carbon source, The carburizing method of the tantalum container of any one of Claims 1-4 characterized by the above-mentioned.   6. The method for carburizing a tantalum container according to claim 4, wherein the support member functions as the carbon source.   A tantalum container, which has been carburized by the method according to claim 1.

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