JP2004085134A - Hot isotropic pressurization device and hot isotropic pressurization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot isotropic pressurization device capable of uniformly mixing led-in treatment gas in a treatment chamber in the case of using mixed gas as the treatment gas and sampling the uniformly mixed gas to make an accurate composition analysis. <P>SOLUTION: In this hot isotropic pressurization device, two or more kinds of gas are separately supplied into a high pressure container 4 and mixed, and while regulating the partial pressure of each component of the mixed gas based on the result of sampling and analyzing the obtained mixed gas, a treated object 10 disposed in the high pressure container 4 is pressurized in an isotropic manner under high temperature by the mixed gas of high temperature and high pressure. A flow straightening cylinder 9 is disposed between the high pressure container 4 and the treated object 10. Opening parts 23, 38 of supply pipelines 22, 37 of each gas are arranged below in the high pressure container 4, on the inner peripheral surface side, and an agitating fan 14 is arranged below in the high pressure container 4, on the center side. An opening part 46 of a sampling pipeline 43 of the mixed gas is disposed near the agitating fan 14. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hot isostatic pressing apparatus and a hot isostatic pressing method, and more particularly, to a powder compact while controlling a partial pressure of a gas component having a characteristic under a high-temperature high-pressure gas atmosphere. The present invention relates to a hot isostatic pressing technique for performing surface treatment such as sintering or transforming the surface of a product made of a specific material into a compound by using a reaction with a gas.
[0002]
2. Description of the Related Art
As a technique for sintering a powder compact under a high-temperature and high-pressure gas atmosphere, by sintering the compact while compressing the compact using a gas pressure using a substantially inert gas such as argon, A so-called hot isostatic pressing method (HIP method) for producing a sintered body containing almost no pores is known.
[0003]
Further, in the HIP method, in the case of a molded body or a pre-sintered sintered body obtained by partially sintering an oxide or nitride ceramic material, the HIP processing in which the processing material is directly exposed to an atmospheric gas is not completely performed. It is known that HIP processing cannot be performed properly when HIP processing is performed in an inert argon gas atmosphere. That is, in the oxide ceramics, oxygen deficiency may occur, and desired characteristics may not be obtained. Mn-Zn-ferrite is known as a typical material. The HIP treatment of the temporarily sintered Mn—Zn—ferrite is performed at 1200 ° C. and about 100 MPa, but when heated to 1200 ° C. using pure argon, (Mn, Zn) O / Fe ₂ O ₃ The composite oxide having a spinel structure, which is known by the composition described above, partially decomposes due to oxygen deficiency, generates FeO (wustite) on the surface, and causes hair cracks. On the other hand, if the oxygen partial pressure is too high, Fe ₂ O ₃ (γ-hematite) is generated.
[0004]
In order to improve such a problem, the present applicant has previously proposed a HIP device in Japanese Utility Model Publication No. 5-14159. However, the following problems have been newly found even with the proposed HIP device. That is, the gas introduced from the gas supply pipe is discharged from the upper opening of the inverted cup-shaped case, so that the gas is discharged to the outside of the high-pressure container before it becomes sufficiently uniform inside the processing chamber. Also, the opening of the sampling pipe for gas analysis in the processing chamber needs to be separated from the opening of the gas supply pipe as much as possible in order to sample a sufficiently homogeneously mixed gas, and the pipe is opened above the processing chamber. There is a need. However, such piping to the upper side is difficult and practically difficult due to exposure to high temperature and high pressure. Furthermore, there is only one gas compressor for pressurizing and supplying two or more types of gas cylinders in the gas supply pipe. Therefore, when switching gas cylinders to adjust gas components or supply different kinds of gases, the gas The gas supplied to the compressor remained in the compressor and in the piping, and high-precision control could not be performed.
[0005]
In addition, as a processing method using the HIP method other than the above-mentioned proposal, a pre-sintered processed product is embedded in the same type of powder or an inert powder, and the atmosphere around the processed product is reduced by the powder or the processed product. The so-called “packing method” in which oxygen is controlled by itself is used. This “filling method” is a reliable method in that it utilizes a natural phenomenon. However, as a result of suppressing the convection of gas around the processed product by the packing, heat transfer becomes extremely poor, and a large HIP device is used. When the sintered body is processed, there is a problem that the processed product is cracked by the thermal stress due to the temperature distribution. In addition, in the case of the “packing method”, there is also an operational problem that the packing powder is scattered inside the processing chamber in the gas recovery or discharge step of the HIP processing and reacts with the furnace structure to cause damage. It has often been experienced.
[0006]
On the other hand, in the case of nitride ceramics typified by silicon nitride, it is known that not only sufficient densification cannot be realized by HIP treatment with pure argon, but also that the surface is roughened by a decomposition reaction, Pure nitrogen gas has been used to avoid this. By using pure nitrogen, the decomposition reaction of silicon nitride is suppressed and a dense sintered body without pores can be obtained, but the grain boundary phase, which greatly affects the high-temperature strength characteristics of silicon nitride ceramics, is altered and It has been experienced that high temperature strength properties cannot be obtained. To avoid this, it is effective to use a mixed gas of argon and nitrogen to reduce the nitrogen partial pressure to about 2 MPa in the holding step of the HIP treatment in a temperature range of about 1700 ° C. .
[0007]
As a method for realizing such a condition, a gas obtained by mixing nitrogen with an amount of nitrogen capable of obtaining a nitrogen partial pressure of 2 MPa as a pressure medium gas for processing, or first, only nitrogen is used. Is supplied to the HIP apparatus, the temperature is set to 1700 ° C. with 2 MPa of nitrogen, and then argon gas is pressurized and injected to bring the total pressure to 100 MPa. There is no problem when the used gas is released and discarded, but since the amount of nitrogen changes depending on the use for repeated use, repeated use of gas is required to keep the nitrogen partial pressure for each batch process the same. Therefore, the HIP processing cost is high, and it has not been put to practical use.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the related art, and an object of the present invention is to use a mixed gas as a processing gas so that the introduced processing gas can be uniformly mixed in the processing chamber. It is intended to provide a hot isostatic pressurizing apparatus and a hot isostatic pressurizing method capable of sampling the uniformly mixed gas and accurately analyzing the components.
[0009]
[Means for Solving the Problems]
The present invention for achieving the above object has the following configuration. That is, the invention according to claim 1 is based on a result obtained by separately supplying two or more kinds of gases into a high-pressure container, mixing the respective gases in the high-pressure container, sampling the obtained mixed gas, and analyzing the mixed gas. A hot isostatic pressurizing apparatus for isostatically pressurizing a processed product disposed in the high-pressure vessel at a high temperature with a high-temperature and high-pressure mixed gas while adjusting the partial pressure of each component of the mixed gas. A cylindrical rectifying tube is arranged between the high-pressure vessel and the processing product in a state surrounding the processing product, and an opening of each gas supply pipe is located below the inner periphery of the high-pressure container in the high-pressure container. And a stirring fan is arranged below the high-pressure vessel and closer to the center, and an opening of a mixed gas sampling pipe is arranged near the stirring fan. This is an isotropic pressure pressing device.
[0010]
In the above hot isostatic pressurizing apparatus, the gas introduced into the high-pressure vessel is raised by the agitating fan through the outer circumference of the rectifying cylinder, and then lowered inside the rectifying cylinder while being lowered inside the rectifying cylinder. The gas can be supplied to and circulated, so that the gas can be reacted with the processed product while being sufficiently mixed, and the sample gas can be led out of the high-pressure vessel while being sufficiently mixed and reacted. Therefore, the gas introduced into the high-pressure vessel is not immediately discharged out of the processing chamber as in the prior application, and the gas circulation inside the processing chamber is performed uniformly and completely, and the gas is sampled to the upper part of the processing chamber. Sampling for gas analysis can be performed without providing piping. Furthermore, since the uniform mixing and gas analysis can be performed efficiently, the partial pressure of the target gas component of the processing gas can be controlled and managed in real time (real time), and the processing gas can be used repeatedly. Is also possible.
[0011]
The invention according to claim 2 is the hot isostatic pressurizing apparatus according to claim 1, wherein the supply pipes for the respective gases can independently control the supply amounts. is there.
[0012]
With this configuration, the operation of changing or / and controlling the gas component of the processing gas can be performed more efficiently than the operation performed by switching the valve with one compressor as in the prior application, and the above-described operation and effect can be achieved. It can be enjoyed more effectively.
[0013]
The invention according to claim 3 is that, based on the result obtained by separately supplying two or more types of gases into the high-pressure vessel, mixing the respective gases in the high-pressure vessel, and sampling and analyzing the obtained mixed gas, A hot isostatic pressing method in which a processing product disposed in the high-pressure vessel is isotropically pressed at a high temperature with a high-temperature and high-pressure mixed gas while adjusting a partial pressure of each component of the mixed gas, A supply disposed below the inner peripheral surface of the high-pressure container along the outer peripheral surface of a cylindrical rectifying cylinder disposed between the container and the treated product so as to surround the treated product. The respective gas for mixing supplied from the opening of the pipe for use is raised, and the mixed gas is passed from the inside of the rectifying cylinder through the processing product by a stirring fan arranged below and at the center of the high-pressure vessel. Lower the mixer placed near the stirring fan. It is an hot isostatic pressure system method characterized by adjusting the components of the mixed gas by sampling the components of the mixed gas from the sampling pipe of the gas.
[0014]
According to a fourth aspect of the present invention, at least one of the two or more gases is an argon gas, and at least another is a mixed gas of an argon gas and an oxygen gas. The hot isostatic pressing method according to claim 3, wherein the oxygen concentration in the container is adjusted.
[0015]
The invention according to claim 5 is characterized in that the mixed gas after treating the treated product is returned to the argon gas supply pipe and reused, according to claim 4. Method.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional front view of a hot isostatic pressing apparatus (HIP apparatus) according to the present invention.
[0017]
In FIG. 1, a cylindrical heat-insulating structure 5 with a bottom is placed upside down inside a high-pressure vessel 4 composed of a high-pressure cylinder 1, an upper lid 2, and a lower lid 3, and a processing chamber 6 is formed therein. I have. A rectifying cylinder 9 having a processed product shelf 8 in which a through hole 7 is formed so as to rectify and flow gas is disposed in the processing chamber 6, and a processed product 10 is disposed therein. The flow regulating cylinder 9 is placed on a processing product table 12 in which a through hole 11 for gas flow is formed. A heater 13 for heating, a fan 14 for stirring the processing gas, and a motor 15 for driving the stirring fan 14 are arranged below the processing product table 12. Reference numeral 16 denotes a lower heat insulating member, which serves to block heat to the drive motor 15 and the lower lid 3 and forms a processing chamber 6 together with the heat insulating structure 5.
[0018]
Outside the high-pressure vessel 4, three gas collecting devices 17, 18, and 19 are provided, and a partial pressure control device 20 and a gas analyzer 21 are provided, respectively. The gas collecting device 17 is a device for storing the collected gas and measuring its reuse. The gas supply pipe 22 on the supply side is inserted through the lower lid 3 of the high-pressure container 4 and the opening 23 is provided with the stirring fan 14. The gas recovery pipe 24 on the recovery side is connected to the gas discharge path 25 of the upper lid 2. Further, a pressure gauge 26 and a pressurization control device 29 including a compressor 27 and a closing valve 28 are connected to the gas supply line 22, and the pressurization control device 29 can be controlled by the partial pressure control device 20. ing. A discharge pipe 31 provided with a manual closing valve 30 and a pressure control device 34 provided with a pressure gauge 32 and a closing valve 33 are connected to the gas recovery line 24, and the pressure control device 34 is controlled by the partial pressure control device 20. It is possible.
[0019]
Each of the gas collecting devices 18 and 19 is a device for containing a new gas and supplying it as a processing gas into the processing chamber 6 of the high-pressure container 4. In the gas collecting device 18, the gas supply line 35 is connected to the gas supply line 22 on the upstream side of the pressurization control device 29 via the manual closing valve 36. The gas collecting device 19 is provided such that the gas supply pipe 37 passes through the lower lid 3 of the high-pressure vessel 4 and the opening 38 faces the inner peripheral surface of the heat insulating structure 5 on the side of the stirring fan 14. ing. The gas supply line 37 is connected to a pressure gauge 39, and a pressurization control device 42 including a compressor 40 and a closing valve 41. The pressurization control device 42 can be controlled by the partial pressure control device 20. .
[0020]
The gas analyzer 21 is a device for analyzing the components of the processing gas, is controllable by the partial pressure control device 20, and is provided with a sampling pipe 43 inserted through the lower lid 3 of the high-pressure container 4. It is connected to and provided. A blocking valve 44 and a pressure regulator 45 are provided in the sampling pipe 43, and an opening 46 of the sampling pipe 43 is provided so as to face the vicinity of the stirring fan 14.
[0021]
Next, a processing method using the HIP apparatus having the above-described configuration will be described by taking as an example a case where a mixed gas of argon (Ar) and oxygen is used as a processing gas. In this case, the gas collecting device 18 is filled with pure Ar gas serving as a main pressure medium gas, and the gas collecting device 19 is filled with Ar-20% O ₂ gas containing oxygen gas whose partial pressure is to be controlled. . In addition, the gas collecting device 17 collects and fills a mixed gas of Ar and oxygen used in the previous process. Further, a program capable of controlling the oxygen partial pressure is incorporated in the partial pressure control device 20, and a gas analyzer using a zirconia oxygen sensor is used as the gas analyzer 21.
[0022]
The processing gas is supplied from the gas collecting devices 17 and 19 to the high-pressure vessel 4 via the gas supply line 22 having the independent pressurization control device 29 and the gas supply line 37 having the pressurization control device 42. You. By this supply, the respective gases are controlled by the pressurization controllers 29 and 42 and a predetermined ratio is injected into the processing chamber from the openings 23 and 38. The injected gas is stirred and sent to the upper part of the processing chamber along the outer peripheral side of the flow regulating tube 9 by the stirring fan 14, and descends inside the flow regulating tube 9 to be circulated and mixed. The large flow of the circulating flow is indicated by arrow A. In the course of the circulation and mixing, the processing gas (a mixed gas of Ar and oxygen corresponding to the article to be treated 10 at a predetermined ratio) is heated by the heater 13 to heat the article 10 to be processed, and at a high temperature and a high pressure under a predetermined condition. HIP processing is performed. In the above HIP process, the processing gas is supplied through a closing valve 44 and a pressure regulator 45 through an opening 46 of a sampling pipe 43 provided near the stirring fan 14 in the processing chamber 6 for a predetermined period. And supplied to the gas analyzer 21.
[0023]
In this example, an example is described in which the recovered gas mainly containing Ar from the gas collecting device 17 is used. However, when the recovered gas is absent or insufficient, or when the mixed amount of the oxygen gas of the recovered gas is the processing gas. If it becomes too large, the manual closing valve 36 may be opened and pure Ar gas from the gas collecting device 18 may be used. In this example, the gas collecting device 18 is connected to the gas supply line 22 of the gas collecting device 17 on the upstream side of the pressurizing control device 29. A supply pipe configuration may be adopted. In this case, the manual closing valve 36 becomes unnecessary.
[0024]
Here, the physical quantity controlled in the HIP processing will be described. The controlled physical quantities are the temperature, the total pressure, the partial pressure of the target gas component, and the time inside the processing chamber 6.
[0025]
The temperature is adjusted by measuring the temperature with a thermocouple (not shown) generally used in the industry and a PID control method with a temperature program controller (not shown). Program control can also be performed with respect to time for the overall pressure. In this case, if the pressure of the processing gas is lower than the program value, the gas collection is performed based on the indicated value of the pressure gauge 32 and the program set value. The pressurization control device 29 of the device 17 (or the gas collecting device 18) is driven to supply and control the Ar gas from the gas supply line 22. If the pressure is high, the closing valve 33 is opened to open the processing gas. Release part to make adjustments. Regarding the oxygen partial pressure of the target gas component, a program for time or temperature is set, and the actual oxygen partial pressure calculated from the output value from the gas analyzer 21 and the total pressure is lower than the program set value. , The pressurization control device 42 of the gas collecting device 19 is driven to supply an Ar-20% O ₂ gas to control the oxygen partial pressure. When it is higher than the program set value, the pressurizing control device 29 of the gas collecting device 18 is driven to supply Ar gas from the gas supply pipe line 22 to dilute oxygen. As a result, when the entire pressure becomes higher than the program set value, the closing valve 33 of the gas discharge passage 25 is opened to lower the pressure in the high-pressure container 4.
[0026]
As described above, according to the HIP apparatus of the present invention, when a mixed gas of Ar gas and oxygen gas is used as the processing gas, the processing gas introduced into the high-pressure vessel 4 is circulated and mixed in the processing chamber 6. And the processing gas can be sampled and the components can be accurately analyzed. As a result, it is possible to sinter a material such as an oxide ceramic with desired characteristics without causing oxygen deficiency. In addition, Ni-based, Co-based or heat-resistant metals such as heat-resistant stainless steel also react with oxygen in a high temperature state to consume oxygen, and the oxygen partial pressure often fluctuates to a lower side. The desired characteristics can be obtained without sintering and sintering can be performed. In addition, since the oxygen is consumed, the oxygen in the recovered gas after the treatment tends to decrease as a result. However, the present invention facilitates the reuse of the recovered gas.
[0027]
In addition, in addition to the examples described above, the present invention uses a method of controlling the partial pressure of ammonia (NH ₃ ) by adding a mixed gas of nitrogen and hydrogen to argon as a main component, such as GaN. Can also be used for the synthesis of nitride semiconductors. In this case, as a matter of course, the gas collecting device requires a gas collecting device for nitrogen and hydrogen in addition to argon as the main component gas, and in many cases, only nitrogen is consumed in the reaction with the processed material. Control can be easily achieved, and the collected gas can be reused.
[0028]
【The invention's effect】
As described above, according to the hot isostatic pressing apparatus and the hot isostatic pressing method according to the present invention, it has been conventionally difficult to control the gas partial pressure in real time. Processing in a high-pressure gas atmosphere can be performed in real time and with high accuracy, and the partial pressure of the target gas component in the processing gas atmosphere can be managed in real time, eliminating problems associated with repeated use of gas. Is done. These effects also facilitate the control of the composition of oxide ceramics and nitride ceramics, sintering in a high-temperature, high-pressure gas atmosphere, and expanding the field of application of surface treatment. It is expected that it will contribute to the development of industrial production of new materials.
[Brief description of the drawings]
FIG. 1 is a sectional front view of a hot isostatic pressing apparatus according to the present invention.
[Explanation of symbols]
1: High pressure cylinder 2: Upper lid 3: Lower lid 4: High pressure vessel 5: Heat insulation structure 6: Processing chamber 7: Through hole 8: Processing product shelf 9: Rectifying cylinder 10: Processing product 11: Through hole 12: Processing product Table 13: Heating heater 14: Stirring fan 15: Motor 16: Lower heat insulating member 17-19: Gas collecting device 20: Partial pressure control device 21: Gas analyzer 22: Gas supply line 23: Opening 24: Gas Recovery line 25: Gas release line 26: Pressure gauge 27: Compressor 28: Shutoff valve 29: Pressurization controller 30: Manual shutoff valve 31: Release pipe 32: Pressure gauge 33: Shutoff valve 34: Pressure control Device 35: gas supply line 36: manual shutoff valve 37: gas supply line 38: opening 39: pressure gauge 40: compressor 41: shutoff valve 42: pressurization control device 43: sampling Tube 44: stop valve 45: pressure regulator 46: opening

Claims (5)

Two or more kinds of gases are separately supplied into a high-pressure vessel, each gas is mixed in the high-pressure vessel, and a partial pressure of each component of the mixed gas is determined based on a result of sampling and analyzing the obtained mixed gas. In a hot isostatic pressurizing device that isotropically pressurizes the processed product disposed in the high-pressure container at a high temperature with a mixed gas of high temperature and high pressure while adjusting
A cylindrical rectifying tube is arranged between the high-pressure vessel and the processing product in a state surrounding the processing product, and an opening of each gas supply pipe is located below the inner periphery of the high-pressure container in the high-pressure container. And a stirring fan is arranged below the high-pressure vessel and closer to the center, and an opening of a mixed gas sampling pipe is arranged near the stirring fan. Isotropic pressure press. The hot isostatic pressurizing apparatus according to claim 1, wherein the supply pipes for the respective gases can independently control the supply amounts. Two or more kinds of gases are separately supplied into a high-pressure vessel, each gas is mixed in the high-pressure vessel, and a partial pressure of each component of the mixed gas is determined based on a result of sampling and analyzing the obtained mixed gas. In the hot isostatic pressing method of isotropically pressurizing the processing product disposed in the high-pressure container at a high temperature with a high-temperature and high-pressure mixed gas while adjusting
Along the outer peripheral surface of the cylindrical rectifying cylinder disposed between the high-pressure vessel and the processing product in a state surrounding the processing product, the lower-side high pressure container is disposed below the inner peripheral surface of the high-pressure container. The mixing gas supplied from the opening of the supply pipe is raised, and the mixed gas is processed from the inside of the rectifying cylinder by the stirring fan disposed below the high-pressure vessel and at the center from the inside of the rectifying cylinder. A hot gas isostatic pressurizing method, wherein the mixture is adjusted by sampling the mixed gas component from a mixed gas sampling pipe arranged near the stirring fan. At least one of the two or more gases is an argon gas, and at least the other is a mixed gas of an argon gas and an oxygen gas. The hot isostatic pressing method according to claim 3, characterized in that: 5. The hot isostatic pressing method according to claim 4, wherein the mixed gas after processing the processed product is returned to an argon gas supply pipe and reused.

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