JPH0617489B2 - Method and apparatus for manufacturing high-density sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a safe operation method of hot isostatic pressing (hereinafter abbreviated as HIP) means applied to industrial production of high density carbon materials, and It relates to a safety device.

(Prior art) Carbon materials (excluding diamond) are divided into amorphous carbon and graphite. There are various forms such as molded bodies and fibers, and their excellent heat resistance, safety against chemicals,
Due to their unique electrical properties, their fields of use have recently been widespread, from space materials such as rocket nozzles to artificial valves of the heart, and their application fields tend to expand.

Particularly, in recent years, unlike conventional graphite and the like, carbon fibers having high density or high elasticity have been developed, and the use as structural members has been rapidly increasing.

However, members used as these functional structural materials are generally required to have high density, and particularly high density, isotropic and large size members are urgently developed. For example, by increasing the density, the strength and corrosion resistance of the material are dramatically improved, and it is expected that the use thereof will be expanded to applications such as chemical equipment and biomaterials used at high temperatures. Further, in the electric discharge machining electrode, which has been in increasing demand for several years, if the electrical characteristics are different depending on the cutting direction, the performance as the electrode is affected, and therefore it is required to be isotropic.

By the way, heretofore, these carbon materials have been obtained by kneading a filler material such as coke and a binder such as tar / pitch,
Since it is manufactured in a step of heating and carbonizing the binder after molding, it inevitably contains pores from which the decomposed gas of the binder has escaped. Therefore, in order to reduce the amount of these pores and increase the density, impregnation with tar pitch,
The operation of carbonizing this is repeatedly performed.

However, in such a process, if the binder is not decomposed at a low speed during firing, the product will crack, and the carbon yield will be low, resulting in a large number of repetitions. As a result, it will take several months to complete the product. The problem is derived.

Further, in order to obtain the isotropic property, a means of forming fine coke by a cold fresh water pressure forming method (rubber press method) is adopted, but if the amount of the binder is not mixed with 20% or more, the formability is improved. However, it was difficult to reduce the porosity after the first firing.

In such a situation, as a method for solving each of the above problems, among the gas components decomposed and produced, the molded body is housed in a can body such as palladium that permeates only hydrogen and isotropically isotropic from the outside of the can body. A method of carbonizing while compressing (see US Pat. No. 3,249,964), a method of JP-A-51-8503 utilizing the HIP method, or Japanese Patent Application No. 59-46076 in which the drawbacks of the invention are improved. Have been proposed.

In the HIP method, a sinterable material is enclosed in an airtight container called a capsule and inserted into a high-pressure container, and the sinterable material is heated by an electric heating element incorporated in the high-pressure container while the pressure in the high-pressure container is increased. At the time of applying so-called HIP for pressurizing by a isotropic compression force of a medium, for example, pressure medium gas, an adjusting pipe line that communicates with the inside of the capsule and extends its end to the outside of the high-pressure container is provided. This is a method of heating and pressurizing the sinterable material while adjusting the type and / or pressure of the gas in the capsule through a pipeline, and is extremely useful because the heating and pressurizing treatment can be performed while adjusting the pressure in the capsule.

(Problems to be Solved by the Invention) However, in the process of actually applying the above method, the present inventors have found that a sintering material containing an organic material such as tar and pitta encapsulated in a capsule is heated. It becomes a coexisting system with hydrogen gas and hydrocarbons that are generated by decomposing at 1. At this time, if there is no abnormality in the capsule, a high density carbon material can be obtained by adjusting the internal and external pressure of the capsule. However, when there are welding defects or pinholes in the capsule, or when cracks occur during the compression process, etc., the above-mentioned decomposed gas flows out of the capsule, and a pressure medium gas outside the capsule, for example, in argon gas is usually used. The hydrogen concentration in the high-pressure container increases significantly compared to the normal state, and there is a risk of causing hydrogen embrittlement or damage due to hydrogen erosion in the high-pressure container. It becomes a serious problem for the first time, and the leaked hydrocarbon is further decomposed, and the decomposed carbon adheres to the electric heating device part, causing dielectric breakdown,
We experienced that the electric heating device and other structural materials were damaged.

Under such circumstances, development of a HIP method and an apparatus which avoids the above-mentioned dangers and problems and guarantees practically perfect safety has become a major technical issue.

That is, the present invention has been completed after intensive research to solve the above technical problems, and its purpose is to provide a coexisting system with an active gas such as hydrogen gas or hydrocarbon in a capsule. Some sinterable materials, especially carbon materials
Completely eliminates the risk of damage to the HIP device or its structural material when obtaining a high-density sintered material by IP treatment,
To ensure safe work.

Another object is to prevent damage to the device in activating the emergency control mechanism or safety device.

(Means for Solving the Problems) A feature of the method of the present invention for achieving the above-mentioned object is that the sinterable material is contained in a capsule in a coexisting system with an active gas such as hydrogen gas or hydrocarbon. When performing hot isostatic pressing in a high-pressure container, the internal pressure (P
₁ ) and the external pressure (P ₂ ) difference (P ₂ −P ₁ ) value is compared with the set value to control at least one of the (P ₁ ) and (P ₂ ) values. In the method for operating the means for maintaining the differential pressure at an appropriate level, the supply of heat to the electric heating device in the high pressure vessel is provided by the emergency output signal when the differential pressure value reaches a predetermined minimum limit value. It is to cut off and release the gas in the capsule to the outside air through an independent adjusting pipe.

The apparatus used for carrying out the method of the present invention is the first to third
High pressure cylinder (1) and top and bottom lids (2)
(3) A high-pressure vessel defined by and a heat insulation layer inside
(6) and a furnace chamber (7) defined by the heating element (4) (4 '), and means for supplying electric power to the heating element (4) (4') A high-temperature high-pressure device comprising means for supplying a pressure medium gas into the high-pressure container, wherein the high-pressure container is arranged in the furnace chamber (7) and communicates with the inside of a capsule that is airtight to the pressure-medium gas. A detector (19) (20) that connects the gas adjustment pipe in the capsule whose end extends to the outside and detects the pressure gas (P ₂ ) in the furnace chamber and the gas pressure (P ₁ ) in the capsule, respectively.
And a processor (28) that compares the detected pressure value difference (P ₂ −P ₁ ) with a set value and converts it into an output signal, and the signal supplies the power supply amount, the pressure medium gas supply amount, and A hot-tube hydrostatic pressing device having a control mechanism for controlling at least one of the gas discharge amount in the capsule to maintain the differential pressure value at an appropriate level is used as a basic configuration, and the difference between the pressure values is set to a predetermined minimum limit. It is an apparatus for producing a high-density sintered body, which is provided with an emergency control mechanism for cutting off the electric power supply to the electric heating body by an emergency output signal when reaching the value and opening the adjusting pipe.

Hereinafter, specific embodiments of the manufacturing method of the present invention will be described in detail with reference to the accompanying drawings together with examples of the apparatus of the present invention.

FIG. 1 shows a cross section of a main body of a high-temperature high-pressure apparatus suitable for carrying out the method of the present invention, that is, a HIP apparatus, and an object to be processed arranged therein.

In the figure, the high-pressure container is partitioned by a high-pressure cylinder (1) and an upper lid (2) and a lower lid (3) that close the upper and lower ends thereof, and each fitting portion is hermetically sealed by a seal (10) (10 '). The gas pressure acting on the lid is supported by a press frame (not shown). Inside the high-pressure container, an electric heating element (4) (4 ') consisting of an electric heating resistance wire for heating and heating the object (13) made of a sinterable material and a high-pressure cylinder by heat from these electric heating elements A heat insulating layer (6) that suppresses the dissipation of heat to the (1), upper lid (2), and lower lid (3) is incorporated.

The object to be processed (13) is housed in a capsule (12) made of a metal material. The capsule (12) has a gas adjustment tube (1
4) is attached, and this pipe (14) is detachable so as to communicate with the gas adjusting hole (11) in the capsule provided in the lower lid (3) via the joint (15) and the furnace chamber (7) It is connected to the pressure medium gas inside by a seal ring (16) so as to maintain airtightness, and an independent adjusting conduit is formed.

The object to be treated (13) is a compact of a sinterable material made of a mixture of a carbon-based filler material such as petroleum coke, anthracene coke, carbon fiber and an organic material binder such as coal tar pitch or phenol. . On the other hand, as the material of the capsule 12, not only steel materials such as mild steel and stainless steel but also platinum and palladium can be used.

Further, the adjusting pipe (14) is usually made of a steel material because it is made of the same material as the capsule (12) or can be easily combined with the joint (15). Then, the inside of the tube (14) is filled with a ceramic powder (14) which is difficult to sinter so as not to be clogged by being crushed by the pressure of the pressure medium gas during processing.

A wire mesh filter is provided at the joint between the in-capsule gas adjusting tube (14) and the adjusting hole (11) in order to prevent the ceramic powder from becoming a low temperature part and solidifying with the liquid component.

The mixed compact with the organic material such as carbon tar and pitch in the present invention is decomposed when the temperature is raised in the HIP treatment process to generate hydrogen and hydrocarbon gas components. If such a substance is treated by an ordinary encapsulation method, the pressure inside the capsule rises due to the above gas components, and it cannot be sufficiently compressed by the pressure of the inert atmosphere gas outside the capsule, or the capsule bursts. Therefore, not only the high density cannot be achieved, but the above-mentioned danger may occur.

Therefore, it is required to control the pressure inside and outside the capsule during the HIP treatment, which enables the above-mentioned molded product to be made into a high-density product.

Such pressure control can be performed by detecting the pressure difference between the inside and outside of the capsule, comparing the result with a set value, and instructing the result to the adjustment pipeline operation system or the temperature / pressure adjustment system. A piping system diagram for controlling the medium gas pressure is shown in FIG.

In order to supply pressure medium gas, for example, argon gas to the high-pressure container (1), a pipe connected to the pressure medium gas introduction hole (8) from the argon gas collecting device (17) through the compressor (18) is provided, and the supply pressure is increased. The detector (P ₂ ) or pressure gauge (19) is attached to the output side of the compressor. A blocking valve may be appropriately arranged in this pressure medium gas supply system, and pressure medium gas recovery pipes may be connected and provided side by side to form independent circuits. Further, the high-pressure container also has a vacuum pump (25) which communicates with a vacuum drawing hole (9) in the upper lid for vacuuming the inside.

On the other hand, the adjusting pipe from the capsule can be communicated with the outside air through the stop valve (22) by the pipe connected to the gas adjusting hole in the capsule (11), and the stop valve (23). And is connected to the vacuum pump (21). Further, the adjustment hole and the pressure medium gas supply system are connected via a check valve (27) and a stop valve (24) in series, and a detection unit for detecting the pressure inside the capsule (P ₁ ) is provided in the conduit. It is equipped with a pressure gauge (20).

Pressure (P ₂ ) detected by pressure gauges (19), (20) and
(P ₁ ) is input to a processor, for example, an electronic processing circuit (28) having a function of detecting a differential pressure and a function of comparing with a set value and a function of converting the result into an output signal by an electric signal, and outputs from the processor. The signals are the power supply control mechanism to the electric heating element, the operation mechanism of the stop valve (22), the copressor (1
It is selectively sent to the power system of 8).

In this case, as the processor, the pressure detection unit or pressure gauge (1
9), (20) Not only an electric differential pressure detector that receives electrical signals from each, but also a direct differential pressure (P ₂ −P ₁ )
You can also use a mechanical differential pressure detector to detect
A known mechanism for processing the detection signals into an output signal by an electronic circuit or a fluid mechanism is appropriately used.

(Operation) Next, a procedure and an operation for densifying a compact by the above-mentioned apparatus will be described. The compact of the sinterable carbon material can be manufactured by various methods. For example, 20 to 30 parts by weight of coal tar pitch is mixed with petroleum coke powder, and the mixture is kneaded at about 100 ° C. and molded with a mold.

When carbon fibers are used and the anisotropy is not so large, the object is achieved by mixing an appropriate amount of a binder such as tar pitch and then isostatically molding in cold or warm. It is also possible to heat the resin molded product and partially carbonize it to use as the molded product.

Then, the molded body is stored in a capsule.

The sinterable material (molded body) stored in the capsule is then
As shown in FIG. 1, it is airtightly mounted and fixed on the pedestal in the furnace chamber (7). The heating element held in the heating element holding cylinder (5)
(4) When the (4) and the heat insulation layer (6) are made of molybdenum graphite, which has poor oxidation resistance, the furnace chamber should be fixed when the capsule is fixed.
(7) The inside of the high pressure vessel is evacuated through the evacuation hole (9) in order to exhaust the air mixed therein. Thereafter, if necessary, a pressure medium gas of several to several tens kgf / cm ^{2 is} introduced and discharged from the pressure medium gas introduction hole (8) to replace and clean the gas in the high-pressure container.

Next, the pressure medium gas is filled and the temperature rise is gradually started. At this time, it is preferable to remove the moisture adsorbed on the inner surface of the capsule and the sinterable material by evacuation of the inside of the capsule during the initial period of temperature increase, that is, until reaching a temperature of over 100 ° C. Further, when the mixture is further heated and heated, the polymerization and carbonization of the binder starts, but in order to obtain a densified product, after the polymerization is started, compression by the pressure of the pressure medium gas from the outside of the capsule and Carbon producing components,
For example, it is preferable that the hydrocarbon finally decomposes into carbon and hydrogen, and that this carbon remains in the voids of the molded body as much as possible, that is, an operation that improves the yield of carbon is performed. From the latter point of view, several tens of kilograms in a capsule
Good results are obtained by raising the temperature with f / cm ² of Ar gas filled.

Since the pressure (P ₁ ) in this capsule fluctuates due to the pressure increase accompanying the expansion of Ar gas at the time of temperature rise and the pressure of the gas component generated by the decomposition of the binder, the above-mentioned object to be processed, that is, the sinterable material The pressure (P ₂ ) of the compressed gas for compressing the molded body needs to be kept higher than the pressure inside the capsule. Especially 45
From around 0 ° C, the pressure of the gas (mainly CH ₄ ) generated by the decomposition of the binder rises sharply, the pressure inside the capsule (P ₁ ) becomes higher than the pressure medium gas pressure (P ₂ ) and the capsule is damaged. Be careful not to let it happen.

In the piping system diagram for controlling the pressure and atmosphere in the capsule shown in FIG. 2, first, the vacuum exhaust in the capsule in the initial stage is stopped with the stop valve (22) and the stop valve (24) closed. Open the valve (23) and operate the vacuum pump (21).

The operation of introducing several tens of kgf / cm ² of Ar into the capsule is
It is preferable that the stop valves (22) and (23) are closed, the stop valve (24) is opened, and the argon gas is allowed to flow into the furnace chamber at the same time. After this, the stop valve (24) is closed, and a predetermined temperature raising / pressurizing operation is performed.

The control of the relationship between the pressure in the capsule (P ₁ ) and the pressure of the pressure medium gas in the furnace (P ₂ ), that is, the control of the compression force of the object to be processed by the pressure medium gas, was provided in the pressure system of the compressed gas. A pressure gauge (19),
It can be realized by comparing the indicated value of the pressure gauge (20) provided in the capsule pressure system with the processor.

When the difference between the two (P ₁ -P ₁ ) is becoming smaller than the set value during the temperature rising process, the compressor (18) is driven to increase the pressure of the pressure medium gas (P ₂ ) or to close it. By opening the stop valve (22) and decreasing the gas pressure inside the capsule (P ₁ ) the pressure difference
It is possible maintenance in (P ₂ -P ₁₎ of the proper level.

From the middle stage of the treatment process, it is more effective to control the heating rate in order to improve the carbon yield.
This can be easily realized by controlling the input power to the electric heating elements (4) (4 ') while observing the change in the indicated value of the pressure gauge (20) in the capsule pressure system.

Further, in order to automatically perform the input power control, a heating power control device is used, and a pressure signal from the pressure gauge (20) is taken into the device through a processor through a pressure electrical signal line. , If the target pressure set value is compared with this pressure signal value, and if it is less than the set value, the input power is increased, and in the opposite case, a control device that increases it is sufficient to achieve the purpose. it can.

Pressure in the capsule (P ₁ ) and pressure of pressure medium gas in the furnace
If the difference between _{(P 2) (P 2 -P} 1) becomes extremely small, for example, if it is smaller than 20 kg _{f /} cm ^2, from the viewpoint of preventing rupture of the capsule, and, There is also an urgent need to shut down the device in order to deal with the possibility that the hermeticity of the capsule has been destroyed for some reason. Therefore, appropriate minimum limit value for the pressure difference (P ₂ -P _1),
For example, 20 kgf / cm ² is set in advance, and a differential pressure detection function and a comparison function such as a differential pressure detector (28) which receives an electric signal from the pressure gauge (19) and the pressure gauge (20) are provided. The output signal from the processor cuts off the power supply to the heating element and opens the shut-off valve (22) to release the decomposed gas in the capsule to the outside air through the adjustment pipe and there was an abnormality in the capsule. At this time, a path for releasing the pressure medium gas in the furnace chamber, for example, argon gas, to the atmosphere through the inside of the capsule is formed to prevent the decomposed gas in the capsule from flowing out into the furnace chamber.

If the gas is released too quickly, the structure may be damaged inside the high-pressure vessel or the piping system may be damaged due to the passage of high-temperature gas. It is preferable to provide a throttle valve (26).

Further, if necessary, a discharge pipe system, that is, a cooling means such as water cooling of the adjusting pipe is provided, or the adjusting pipe is provided with a high pressure chamber through a blocking valve (29) as shown in FIG. It is preferable from the viewpoint of device protection that a pipe system (30) communicating with the low temperature part of the device is provided, and the stop valve (22) is opened and the stop valve (29) is opened at the same time. .

The emergency control mechanism, that is, the safety device described above, can be used only when the blocking valve (24) is closed when there is a piping system for communicating the inside of the capsule with the inside of the high pressure container as shown in FIG. Since it should function, it is preferable that the closure valve (22) be opened based on the closure signal of the closure valve (24) and the differential pressure limit signal inside and outside the capsule.

In addition to this, the heat insulating layer (6) in the high-pressure vessel is composed of an inverted cup-type airtight casing, that is, a casing having an airtightness such that a leak is not detected by a halogen or helium detector. Hydrogen gas, which is usually lighter than argon gas, is retained in the upper part of the casing even if it outflows from the capsule and does not reach the pressure vessel wall immediately. Is suitable as

Furthermore, it is a safer device to take appropriate measures such as sampling and analyzing the hydrogen concentration in the pressure medium gas during the treatment process, and if the hydrogen concentration exceeds the specified value, cut off the power supply to the heating device. This is preferable in that respect.

It should be noted that the above is HI for treating a carbon material as a sinterable material
Although it has been described as a safety device for the P device, a method and a device for other processing purposes, in which the sinterable material in the capsule is compressed in a coexisting system with hydrogen gas while introducing hydrogen gas into the capsule. It goes without saying that the present invention can be applied to the above.

(Example) 30 parts by weight of coal tar pitch was added to 70 parts by weight of petroleum coke having an average particle size of 20 μm, and the mixture was kneaded at 140 ° C., then cooled to room temperature and ground. The obtained powder was put in a rubber bag and molded by a rubber press machine at a pressure of 3000 kgf / cm ² . A cylindrical sample (diameter 50 mm × height 50 mm, weight 126.9 g) obtained by turning was placed in a mild steel capsule. This capsule was mounted in a high temperature and high pressure apparatus in the state as shown in FIG. After the inside of the furnace of the equipment is evacuated and replaced with argon gas, 120 kgf / cm ²
Was charged into the furnace chamber, and the temperature and pressure in the furnace chamber were changed to compress and carbonize the molded body.

At this time, the pressure in the capsule is automatically controlled by the control circuit to automatically operate the stop valve for releasing it mainly to the atmospheric pressure.
The pressure was adjusted so that the range of 0 kgf / cm ² was not exceeded, and the difference between the pressure of the pressure medium gas and the furnace pressure was 100 kgf / cm ² so as not to exceed the level.

After cooling and lowering the pressure, the mild steel capsule was removed and the fired body was taken out. The size and weight of the obtained sintered body were 44 mm in diameter, 45 mm in height, and 107.4 g in weight. Bulk density is 1.56
The generation of cracks was also slight at g / cm ² .

Next, a sinterable material molded under the same conditions was similarly installed in a high temperature and high pressure device to increase the electric power input to the electric heating element to rapidly raise the temperature and intentionally reduce the pressure rising rate of the pressure medium gas. Let me drive.

When the standard value of the difference between the internal pressure and the external pressure of the capsule was set to 100 kgf / cm ² and the minimum limit value was set to 50 kgf / cm ² , the amount of gas released due to the rapid generation of gas around the temperature of 450 ° C due to the rapid decomposition of the compact. However, the balance became unbalanced, the pressure difference reached 50 kgf / cm ² beyond the automatic control limit, and the emergency control mechanism worked. As a result, the control conduit was fully opened when the power supply to the electric heating element was stopped, and the emergency itself could be avoided.

After that, since the mixing of hydrogen gas was not detected by the sampling and analysis of the pressure medium gas in the furnace, the temperature and pressure increase programs were returned to normal, and a sintered body similar to the above was obtained.

(Effects of the Invention) The present invention uses a capsule made of a metal having a gas adjusting pipeline in the capsule when firing a sinterable compact made of an organic material such as carbon and tar pitch as described above. The molded body is stored in the capsule, the temperature is increased while being compressed by the pressure on the outside of the capsule, and at the same time, the pressure difference between the inside and the outside of the capsule is detected. Safety that quickly detects abnormalities in the above pressure difference due to loss of the isolation performance of the capsule due to rising, abnormal deformation of the capsule, etc., suppresses gas generation, and discharges the gas inside the capsule to the outside through an independent adjustment pipeline. Since the measures were taken, the decomposition gas such as hydrogen and hydrocarbon is mixed in the pressure medium gas, which causes the embrittlement of hydrogen on the vessel wall of the high-pressure vessel or the destruction due to hydrogen erosion. Can be completely avoided.

Further, it is possible to prevent the dielectric breakdown caused by the carbon adhering to the heating device portion caused by the decomposition of hydrocarbons and the damage to other structural materials.

As described above, according to the present invention, a high-strength, high-density and isotropic carbon molded body can be obtained by HIP molding with perfect safety. The invention, when handling high-voltage equipment,
It is a useful invention that makes it possible to assure the safety that pays strict attention and attention and prevent accidents, accidents, losses, etc.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a system diagram for controlling the pressure inside the capsule and the pressure medium gas pressure, and FIG. 3 is another example of the control mechanism of the present invention. It is a piping system diagram of an apparatus. (1) …… High-pressure cylinder, (2) …… Upper lid, (3) …… Lower lid, (4) (4 ′) …… Electric heating element, (6) …… Insulating layer, (7) …… Furnace chamber , (8) …… Pressure medium gas introduction hole, (9) …… Vacuum suction hole, (11) …… Capsule gas adjustment hole, (12) …… Capsule, (13) …… Molded body (object to be treated) ), (14) …… Conduit for gas adjustment in capsule, (14) …… Stainless ceramic powder, (15) …… Fitting, (17) …… Argon gas collector, (18) …… Compressor , (19) (20) …… Pressure gauge (detector), (21) (25) …… Vacuum pump, (22) (23) (24) (29) …… Stop valve, (26) …… Throttle valve, (27) …… Check valve, (28) …… Processor,

Claims (11)

[Claims] 1. A sinterable material is housed in a capsule in a coexisting system with an active gas such as hydrogen gas or hydrocarbon, and when the hot isostatic pressing process is performed in a high-pressure container, the internal pressure (P ₁ ) And the external pressure (P ₂ ), the output signal obtained by comparing the value of the differential pressure (P ₂ −P ₁ ) with the set value controls at least one of the values of (P ₁ ) and (P ₂ ). In the method of operating the means for maintaining the differential pressure at an appropriate level, when the differential pressure value reaches a predetermined minimum limit value, supply of heat to the electric heating device in the high pressure vessel by an emergency output signal. And a gas in the capsule is discharged to the outside air through an independent adjusting pipe, and a method for producing a high-density sintered body. 2. The method for producing a high density sintered body according to claim 1, wherein the gas is released at a limited flow rate. 3. The method for producing a high-density sintered body according to claim 1, wherein the gas is released while cooling the gas in the adjusting pipe. 4. The high density according to claim 1, wherein the gas is released by allowing the gas in the capsule to merge with the gas in the low temperature section in the high pressure container in the adjusting pipeline. Manufacturing method of sintered body. 5. The production of the high-density sintered body according to claim 1, wherein the emergency output signal is actuated after confirming the closure of the conduit connecting the interior of the capsule and the interior of the high-pressure container. Method. 6. A high-pressure container defined by a high-pressure cylinder and upper and lower lids, and a furnace chamber defined by an electric heating element disposed inside the high-pressure container via a heat insulating layer, and electric power is supplied to the electric heating element. A high-temperature high-pressure device comprising means for supplying a pressure medium and a means for supplying a pressure medium gas into a high-pressure container, the high-pressure device communicating with the inside of a capsule that is arranged in the furnace chamber and is airtight to the pressure medium gas. A detection unit that detects the gas pressure inside the reactor chamber (P ₂ ) and the gas pressure inside the capsule (P ₁ ) while connecting the gas adjustment pipeline inside the capsule whose end extends outside the container was detected. A processor that compares the pressure value difference (P ₂ −P ₁ ) with a set value and converts it into an output signal, and at least one of the power supply amount, pressure medium gas supply amount, and capsule gas discharge amount by the signal. Control mechanism for controlling the pressure difference and maintaining the differential pressure value at an appropriate level. In the isostatic pressing apparatus, an emergency control mechanism that shuts off the electric power supply to the electric heating body by the emergency output signal when the difference between the pressure values reaches a predetermined minimum limit value and opens the adjustment pipeline is provided. An apparatus for producing a high-density sintered body, characterized by being attached. 7. An apparatus for producing a high-density sintered body according to claim 6, wherein the adjusting pipe comprises a throttle valve. 8. An apparatus for producing a high-density sintered body according to claim 6 or 7, wherein said adjusting pipe is provided with a cooling means for cooling it. 9. The method according to claim 6, wherein the adjusting pipe communicates with a low temperature portion in the high pressure vessel through a stop valve, and the stop valve is opened by the emergency output signal. An apparatus for manufacturing a high-density sintered body according to any one of items 8 to 8. 10. The adjusting pipe is connected to a pressure medium gas supply pipe to a high-pressure container through a stop valve and a check valve, and the emergency control mechanism confirms that the stop valve is closed. 10. The apparatus for producing a high-density sintered body according to any one of claims 6 to 9, wherein the manufacturing apparatus for a high-density sintered body operates according to any one of claims 6 to 9. 11. The manufacturing apparatus for a high-density sintered body according to claim 6, wherein the heat insulating layer is an inverted cup-type airtight casing.