Method for manufacturing graphite material

Abstract

To prevent a gas blocking a light path and to prevent the inside of a temperature measurement pipe from oxidizing.SOLUTION: There is provided a temperature measurement pipe 10 which measures a temperature of an object of temperature measurement, and comprises: a pipe part 1 which is hollow and made of graphite; a first end part member 2 which is provided at a first end part 1a of the pipe part 1 coming into contact with the object of temperature measurement and made of graphite, and closes the first end part 1a; and a light-transmissive window 3 which is installed nearby a second end part 1b on the opposite side from the first end part 1a of the pipe part 1 coming into contact with the object of temperature measurement, and transmits light in the space in the pipe part 1, wherein the second end part 1b is closed and a gas introduction hole 4 for introducing the gas into the internal space from outside is formed nearby the second end part 1b.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to a temperature measuring pipe, a temperature measuring method, and a method for manufacturing a graphite material.

Background Art

[0002] Graphite is an industrially important material that is widely used in various fields because it has excellent heat resistance, thermal conductivity, and corrosion resistance, and relatively large blocks can be easily obtained.

[0003] In the production of such graphite, in order to obtain large blocks, it is difficult to apply an atmosphere furnace that requires blocking the atmosphere. Since the processing temperature is high, instead of an atmosphere furnace, a graphitization treatment is performed using an Acheson furnace or an induction furnace that is blocked from the atmosphere with a packing material. Also, the temperature of the graphitization treatment is an important parameter that greatly affects the physical properties of the material, and grasping the accurate processing temperature is an important matter in the production of graphite.

[0004] Patent Document 1 discloses a temperature measuring sleeve made of a carbon fiber reinforced carbon composite material (hereinafter also referred to as "C / C") used when carbonizing or graphitizing an organic substance or when manufacturing a ceramic. Such a temperature measuring sleeve for measuring the temperature of a high-temperature treatment furnace is lightweight, has low heat conduction, and suppresses the load on the attachment part because it has excellent mechanical properties and is easy to thin. Also, it is described that C / C is suitable for a temperature measuring sleeve because it has a higher impact strength, better handleability, and a lower thermal conductivity than ordinary graphite materials.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, Patent Document 1 states that when a temperature-measuring pipe (temperature-measuring sleeve) composed of C / C is applied to an Acheson furnace or an induction furnace (graphitization furnace) used for the production of graphite, when it is subjected to heat of 2500 °C or higher, graphitization of C / C proceeds, and problems such as deterioration of strength and increase in thermal conductivity occur.

[0007] In addition, the structure of the C / C temperature-measuring pipe described in Patent Document 1 is such that decomposition products such as nitrogen and sulfur contained inside, and gases of metal oxides and metal carbides are generated as graphitization progresses, which may obstruct the optical path of the light used for temperature measurement and make it impossible to measure the temperature.

[0008] In view of the above problems, an object of the present invention is to provide a temperature-measuring pipe, a temperature measurement method, and a method for manufacturing a graphite material that can be suitably used in a high-temperature treatment furnace such as a graphitization furnace.

Means for Solving the Problems

[0009] The above object is achieved by the temperature-measuring pipe according to the following (1) of the present invention.

[0010] (1) A temperature-measuring pipe for measuring the temperature of a temperature-measuring object, which is hollow and composed of a pipe portion made of graphite, a first end member provided at a first end of the pipe portion in contact with the temperature-measuring object, made of graphite and closing the first end, and a light-transmissive window installed in the vicinity of a second end opposite to the first end of the pipe portion in contact with the temperature-measuring object, and transmitting light in the internal space of the pipe portion, the second end being closed, and a gas introduction hole for introducing gas from the outside into the internal space being formed in the vicinity of the second end, temperature-measuring pipe.

[0011] The temperature-measuring pipe of the present invention can prevent the generation of light-absorbing gases or fog that block the optical path used for measurement by the radiation thermometer, and prevent oxidation inside the temperature-measuring pipe, because the internal space of the closed pipe part forms an optical path and an inert gas can be introduced into the internal space through the gas introduction hole.

[0012] Moreover, the temperature-measuring pipe according to the present invention preferably has the following (2) to (4).

[0013] (2) The temperature-measuring pipe according to (1), wherein the light-transmissive window and the gas introduction hole are provided in a second end member that closes the second end.

[0014] By providing the window and the gas introduction hole in the second end member, the window and the gas introduction hole can be easily provided in the vicinity of the second end.

[0015] (3) The temperature-measuring pipe according to (1) or (2), wherein at least one of the pipe part or the first end member is made of a porous body.

[0016] When the pipe part or the first end member is a porous body, a flow can be formed to push out the generated light-absorbing gas or fog to the outside, allowing for rapid ventilation and ensuring a highly permeable optical path in the internal space of the pipe part. Also, when the temperature-measuring pipe is placed on a packing material, it can prevent the temperature rise near the second end by flowing the gas downward against the convection of the gas heated in the internal space.

[0017] (4) The temperature-measuring pipe according to any one of (1) to (3), further comprising a protective pipe that covers the outer surface of the pipe part.

[0018] By having the protective pipe, it is possible to lower the temperature of the part in contact with oxygen in the pipe part and prevent the oxidation and consumption of the temperature-measuring pipe. In particular, by providing the protective pipe at a position where it is easily oxidized and consumed, only the protective pipe can be replaced, extending the life of the temperature-measuring pipe.

[0019] Further, the above object is achieved by the temperature measurement method of the following (5) according to the present invention.

[0020] (5) A temperature measurement method for measuring the temperature of a temperature measurement object using a temperature measurement pipe, the temperature measurement pipe comprising: a pipe portion that is hollow and made of graphite; a first end member that is provided at a first end of the pipe portion in contact with the temperature measurement object, is made of graphite, and closes the first end; and a light-transmissive window that is installed near a second end opposite to the first end of the pipe portion in contact with the temperature measurement object and transmits light in the internal space of the pipe portion, wherein the second end is closed, and a gas introduction hole for introducing gas into the internal space from the outside is formed near the second end, the method comprising: a step of burying the first end in the temperature measurement object; a step of introducing an inert gas from the gas introduction hole into the internal space to make the internal space in a positive pressure state; a step of measuring the temperature of the first end through the window; and having the steps.

[0021] An optical path for a radiation thermometer to measure is formed in the internal space of the closed pipe portion, and an inert gas can be introduced into the internal space from the gas introduction hole, so that it is possible to prevent the generation of a light-absorbing gas or cloudiness that blocks the optical path and to prevent oxidation inside the temperature measurement pipe. Further, since the first end located at a position away from the second end is made of graphite, it receives heat transfer and the temperature rises substantially equally to the temperature measurement object. Therefore, even at a high temperature, other influences can be excluded and measurement can be performed.

[0022] Further, the temperature measurement method according to the present invention is preferably the following (6) or (7).

[0023] (6) At least one of the pipe portion or the first end member is composed of a porous body, the inert gas introduced from the gas introduction hole is discharged to the outside from at least one of the pipe portion or the first end member, so that the gas in the temperature measurement pipe is ventilated, and the temperature measurement method according to (5).

[0024] When the pipe part or the first end member is a porous body, a flow that pushes the generated gas to the outside can be formed, enabling prompt ventilation and ensuring a highly permeable optical path in the internal space of the pipe part. Also, when the temperature measurement pipe is arranged on the packing material, it can counter the convection of the warmed gas to flow the gas downward and prevent the temperature rise near the second end.

[0025] (7) The temperature measurement pipe further includes a protection pipe that covers the outer surface of the pipe part, One end of the protection pipe is buried in the packing material arranged around the object to be temperature-measured, and the other end of the protection pipe is exposed outside the packing material. The temperature measurement method according to (5) or (6).

[0026] By having the protection pipe, the temperature of the part in contact with oxygen in the pipe part can be lowered, and oxidation consumption of the temperature measurement pipe can be prevented. In particular, by providing the protection pipe at a position where it is easily oxidized and consumed, only the protection pipe can be replaced, and the life of the temperature measurement pipe can be extended.

[0027] Also, the above object is achieved by the method for manufacturing a graphite material according to the following (8) of the present invention.

[0028] (8) A graphitization step of packing the carbonaceous block, which is the object to be temperature-measured, in a graphitization furnace, covering it with a packing material, and then heating it by energization heating, (5) Measuring the processing temperature in the graphitization step by the temperature measurement method according to any one of (5) to (7), A method for manufacturing a graphite material having the above steps.

[0029] According to the method for manufacturing a graphite material of the present invention, the processing temperature of graphitization can be measured while eliminating the influence of the decomposition gas generated during the graphitization step.

Effects of the Invention

[0030] According to the temperature measurement pipe of the present invention, since the internal space of the closed pipe portion forms an optical path and an inert gas can be introduced into the internal space from the gas introduction hole, it is possible to prevent the generation of a light-absorbing gas or cloudiness that blocks the optical path and to prevent the oxidation inside the temperature measurement pipe.

Brief Description of the Drawings

[0031]

Figure 1A

Figure 1B

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Figure 8

[0032] (Detailed Description of the Invention) Figure 1A is a cross-sectional view of the temperature measuring pipe 10 according to the first embodiment of the present invention, and Figure 1B is a plan view of the temperature measuring pipe 10 according to the same embodiment. The temperature measuring pipe 10 is a device for measuring the temperature of various temperature measurement objects, and includes a pipe portion 1, a first end member 2 provided at the first end 1a of the pipe portion and closing the first end 1a, a light transmissive window 3 installed near the second end 1b opposite to the first end 1a, and a gas introduction hole 4 formed near the second end 1b.

[0033] The pipe portion 1 is the main body of the temperature measuring pipe 10, is a long member made of graphite, is hollow and has an internal space extending in the longitudinal direction inside. The pipe portion 1 has a cylindrical shape, but the shape is not particularly limited.

[0034] The first end member 2 is provided at the first end 1a of the pipe portion 1 in contact with the temperature measurement object, is made of graphite, and serves to close the first end 1a. The illustrated first end member 2 is a separate member from the pipe portion 1, is driven into the open first end 1a to seal the first end 1a, and functions like a so-called end plug. However, the fixing method of the first end 1a is not limited to driving, and may be screw fixing, adhesion with a carbon-based adhesive, etc., and the fixing method is not limited. Also, the first end 1a does not necessarily need to be a separate member from the pipe portion 1, and may be made into a bottomed shape during the processing of the pipe portion 1 and integrated with the pipe portion 1.

[0035] The density of the graphite used for the pipe portion 1 and the first end member 2 is not particularly limited, but for example, it is preferably 1.70 to 1.85 g / cm 3 It is. When the density of graphite is 1.70 g / cm 3 or more, the amount of pores in the pipe portion 1 and the first end member 2 can be reduced, and it is easy to prevent the inflow of generated gas into the internal space of the pipe portion 1. Also, when the density of graphite is 1.85 g / cm 3If it is as follows, heat transfer by the pipe portion 1 can be suppressed, so that the temperature rise of the second end portion 1b can be suppressed, and the inert gas introduced by the ventilation resistance can be stored in the internal space to maintain the positive pressure state of the internal space. Further, since the specific surface area of graphite becomes small, air oxidation of the portion exposed to the atmosphere can be suppressed.

[0036] Further, at least one of the pipe portion 1 or the first end member 2 is preferably composed of a porous body. When it is the pipe portion 1 or the first end member 2, a flow can be generated to push out the gas generated during heating to the outside of the pipe portion 1, ventilation can be performed promptly, and a light path with good permeability can be secured in the internal space of the pipe portion 1.

[0037] The porosity of the temperature measuring pipe 10 or the first end member 2 is preferably 5 to 20%. By being 5% or more, it is easy to pass the inert gas. Further, by being 20% or less, it is easy to maintain the pressure difference between the internal space and the outside world, and it is possible to prevent the intrusion of gas that causes fogging and light absorption from the outside to the inside of the temperature measuring pipe.

[0038] Further, in order to suppress heat transfer and prevent the inflow of generated gas, an impermeable coating layer (impermeable film) may be provided on the pipe portion 1. Examples of the impermeable coating layer include pyrolytic carbon and vitreous carbon. The impermeable coating layer is for preventing the inflow of generated gas. The impermeable coating layer can prevent the inflow of inert gas from the pipe portion 1 and prevent the intrusion of generated gas that causes fogging and light absorption into the inside.

[0039] The window 3 is installed near the second end portion 1b on the side opposite to the first end portion 1a in contact with the temperature measurement object, has light transmissibility for transmitting the light in the internal space of the pipe portion 1, and is composed of a light transmissive material such as glass, but its form is not particularly limited. Since the window 3 is light transmissive, the internal space of the pipe portion 1 can be observed through the window 3 using predetermined light.

[0040] Further, the second end portion 1b of the pipe portion 1 is closed by the window 3. More specifically, a cylindrical second end member 7 having the window 3 is put on the second end portion 1b to close the second end portion 1b. However, the second end member 7 is not an essential member, and the window 3 may be directly attached near the second end portion 1b.

[0041] Through the window 3, in order to measure the temperature of the internal space of the pipe portion 1 as described later, in order not to affect the temperature measurement, for example, quartz glass having a transmission wavelength range of 0.4 to 4 μm, CaF2 having a transmission wavelength range of 0.4 to 10 μm, BaF2 having a transmission wavelength range of 0.4 to 10 μm, etc. can be used, but the material is not particularly limited and can be appropriately selected according to the element of the radiation thermometer used for the measurement. When using quartz glass, since the thermal expansion coefficient is lower than that of fluoride-based materials and it is resistant to thermal shock, although the available wavelength range is narrow, it can be preferably used as a window, and by applying a radiation thermometer with a utilization wavelength of 0.4 to 4 μm, highly reliable temperature measurement can be performed. Also, since BaF2 and CaF2 have a wide wavelength range of transmission, more accurate measurement can be performed.

[0042] Furthermore, the second end member 7 is provided with a gas introduction hole 4 for introducing gas from the outside into the internal space of the pipe portion 1. However, the gas introduction hole 4 may be formed near the second end portion 1b in the same manner as the window 3, and it is not necessarily provided in the second end member 7.

[0043] The gas introduction hole 4 opens near the second end portion 1b and can be connected to a tube for introducing an inert gas. The connection form between the gas introduction hole 4 and the tube is not particularly limited. When the gas introduction hole 4 has a tapered screw, the two can be connected by inserting the socket of the tube into the tapered screw. However, the gas introduction hole is not limited to the form having a tapered screw and may be a straight hole. In the case of a straight hole, it can be connected to the tube of the inert gas by methods such as fitting and adhesion.

[0044] Since the second end member 7 is a part where the temperature rise is small, the material is not particularly limited. For example, ceramics such as graphite and alumina, metals such as stainless steel, iron, and aluminum, and heat-resistant resins such as polyimide, polyether ether ketone, and polyphenylene sulfide can be used. When the second end member 7 has the window 3 and the gas introduction hole 4, by attaching the second end member 7 to the pipe portion 1, the window 3 and the gas introduction hole 4 can be easily provided. However, the window 3 and the gas introduction hole 4 are not necessarily provided in the second end member 7, and at least one of the window 3 and the gas introduction hole 4 may be directly provided in the pipe portion 1.

[0045] Figure 2 shows a temperature measurement method using the temperature measurement pipe 10 of the first embodiment and a method for manufacturing a graphite material. The temperature measurement pipe 10 is inserted into the inside of a graphitization furnace 20 for manufacturing a graphite material. The graphitization furnace 20 includes a furnace wall 21, a heat insulating material 23 disposed inside the furnace wall 21, a packing material 25 disposed inside the heat insulating material 23, and a carbonaceous block 27 embedded inside the packing material 25.

[0046] The carbonaceous block 27 is embedded in the packing material 25 composed of artificial graphite particles, and the heat insulating material 23 forms a heat insulating layer between the furnace wall 21 and the packing material 25. For example, carbon black is used for the heat insulating material 23.

[0047] The temperature measurement pipe 10 has its first end 1a inserted into the gap between the carbonaceous blocks 27 which are the objects to be temperature-measured, and its second end 1b exposed outside the packing material 25. Also, a radiation thermometer 30 is installed in front of the window 3, and the temperature of the internal space of the pipe portion 1, and thus the surface temperature of the first end 1a inserted between the carbonaceous blocks 27, is measured through the window 3. Further, a tube 40 for introducing an inert gas into the internal space of the pipe portion 1 is connected to the gas introduction hole 4.

[0048] The carbonaceous block 27 is packed into the graphitization furnace 20, covered with the packing material 25, and then the temperature measuring pipe 10 is inserted into the carbonaceous block 27 and the packing material 25 and heated by energization. An inert gas is introduced into the internal space of the pipe portion 1 from the gas introduction hole 4 of the temperature measuring pipe 10 to make the internal space in a positive pressure state. Then, the temperature of the first end portion 1a is measured using the radiation thermometer 30 through the window 3. That is, the processing temperature in the graphitization process can be measured.

[0049] When at least one of the pipe portion 1 or the first end member 2 is composed of a porous body, a flow can be formed to push out the gas generated during heating to the outside of the pipe portion 1, allowing for rapid ventilation and ensuring a light path with good permeability in the internal space of the pipe portion 1.

[0050] From the carbonaceous block 27, as the temperature of the graphitization furnace 20 rises, impurity components such as hydrogen, sulfur, and metal contained therein are desorbed. Hydrogen is desorbed in the form of hydrogen gas, hydrocarbons, etc., and sulfur is desorbed in the form of sulfur gas, hydrogen sulfide, sulfur oxides, etc. The gas containing sulfur, hydrocarbon gas, and the gas of the metal compound aggregate as the temperature rises and then decreases, and block the light path in the internal space of the temperature measuring pipe 10. Therefore, by introducing an inert gas from the gas introduction hole 4, it is possible to prevent oxidation inside the temperature measuring pipe 10 and prevent the intrusion of gas derived from impurities that aggregate and block the light path.

[0051] FIG. 3 shows a method and an apparatus for manufacturing a graphite material using the temperature measuring pipe 10 of the first embodiment. The manufacturing apparatus is an Acheson furnace 50, which is a type of graphitization furnace. The Acheson furnace 50 includes a power source 51, a bus bar 53 connected to the power source 51, an electrode 55 connected to the bus bar 53, and a plurality of carbonaceous blocks 57 disposed between the two electrodes 55.

[0052] In the production of graphite materials, current is supplied from a power source 51, through a bus bar 53 and electrodes 55, to a plurality of carbonaceous blocks 57 arranged between two electrodes 55. As a result, mainly the packing material (see FIG. 2) filled between the carbonaceous blocks 57 generates heat and the temperature rises, and the carbonaceous blocks 57 are graphitized.

[0053] The graphitization furnace is not limited to an Acheson furnace 50 that passes current from an external electrode, and may also be an induction furnace that passes current through carbonaceous blocks by mutual induction from induction coils provided around the furnace, and its type is not limited.

[0054] FIG. 4 shows a cross-sectional view of the temperature measurement pipe 10 of the first embodiment in the usage environment in the graphitization furnace 20 of FIG. 2. The temperature measurement pipe 10 is used buried in the packing material 25 and the carbonaceous block 27. The carbonaceous block 27 is heated to 2500 to 3000 °C for graphitization, while the upper part (periphery) of the graphitization furnace 20 is the atmosphere, and a temperature gradient of about 2500 to 3000 °C is created in the packing material 25. As a result, the packing material 25 itself oxidizes, placing the carbonaceous block 27 in a reducing atmosphere. That is, an oxidation reaction always occurs at the upper part of the packing material 25, preventing the oxidation of the carbonaceous block 27.

[0055] Also, a temperature gradient occurs in the temperature measurement pipe 10. Since the temperature measurement pipe 10 is more likely to conduct heat than the packing material 25, oxidation always occurs in the region where oxygen penetrates, and it is gradually consumed. Even if a coating such as pyrolytic carbon is applied, consumption still occurs. Therefore, it is preferable to flow an inert gas inside the temperature measurement pipe 10 and release the gas from the pipe part 1 constituted by a porous body and the first end member 2 to the outside of the temperature measurement pipe 10. By adopting such a method, the internal space of the temperature measurement pipe 10 can always be filled with fresh inert gas without fog, and a light path with good permeability can be ensured in the internal space of the pipe part 1. Further, by introducing the inert gas, a flow of inert gas downward from the exposed second end 1b to the outside is formed against the warmed convection, preventing the temperature rise at the upper part of the temperature measurement pipe 10 and thus preventing the oxidation of the outer surface of the pipe part 1.

[0056] Fig. 5A is a cross-sectional view of a temperature measuring pipe 10 according to a second embodiment of the present invention, and Fig. 5B is a plan view of the temperature measuring pipe 10 according to the same embodiment. The temperature measuring pipe 10 of this embodiment further includes a protective pipe 9 that covers the outer surface of the pipe section 1 in addition to the configuration of the first embodiment. The protective pipe 9 is provided at the center position in the longitudinal direction of the pipe section 1, but the attachment position is not particularly limited.

[0057] FIG. 6 shows a method of measuring temperature using the temperature measuring pipe 10 of the second embodiment, and FIG. 7 shows an environment in which the temperature measuring pipe 10 of the second embodiment is used. The configuration of the graphitization furnace 20 is the same as that of FIG. 2 and FIG. 4. The temperature measuring pipe 10 is connected to a protection pipe 9. is The protective pipe 9 is embedded in the packing material 25 and the carbonaceous block 27 so as to be located at the boundary between the upper part of the packing material 25 and the atmosphere. That is, one end of the protective pipe 9 is embedded in the packing material 25 arranged around the carbonaceous block 27, and the other end of the protective pipe 9 is exposed to the outside of the packing material 25.

[0058] With this arrangement, the protective pipe 9 can protect the outer surface of the pipe section 1, which is easily oxidized, by the protective pipe 9 itself being oxidized. 。Protect Since the protective pipe 9 is selectively oxidized, the pipe portion 1, which requires a long length and requires a lot of work to process, is protected, and the temperature measuring pipe 10 can be used for a long period of time by replacing only the protective pipe 9.

[0059] (Mode for carrying out the invention) A specific example will be described below. A temperature measuring pipe with a protective pipe was inserted into an Acheson furnace as shown in Fig. 3, electricity was applied, and graphitization was performed at about 3000°C while checking the temperature with a radiation thermometer while nitrogen gas was flowing from the gas inlet. When the introduction of nitrogen gas was stopped, the gas generated from the carbonaceous block filled the internal space inside the temperature measuring pipe, causing fogging, and the measured temperature decreased and became unstable. When inert gas was introduced again, the fogging disappeared and the temperature could be measured stably.

[0060] After the power supply was turned off, the temperature measurement pipe and the protection pipe were quickly removed, and the surface condition was checked. Fig. 8 is an external appearance photograph of the protection pipe of the temperature measurement pipe of Example 1 after use. Although the area above the furnace and inside the packing material are hardly consumed, the boundary region is selectively consumed. Also, there are white deposits on the surface inside the packing material. This is considered to be an oxide of metallic impurities contained in the carbonaceous block or the like. Also, it was confirmed that the surface of the temperature measurement pipe hardly changed and was protected from consumption by the protection pipe.

Explanation of Signs

[0061] 1 Pipe part 1a First end 1b Second end 2 First end member 3 Window 4 Gas introduction hole 7 Second end member 9 Protection pipe 10 Temperature measurement pipe 20 Graphitization furnace 21 Furnace wall 23 Heat insulating material 25 Packing material 27 Carbonaceous block 50 Acheson furnace 51 Power supply 53 Bus bar 55 Electrode 57 Carbonaceous block

Claims

【Claim 1】 A graphitization step of packing a carbonaceous block, which is an object to be temperature-measured, into a graphitization furnace, covering it with a packing material, and then heating it by energization heating; A step of measuring the processing temperature in the graphitization step by a temperature measurement method; A method for manufacturing a graphite material, comprising: The temperature measurement method is: A temperature measurement pipe that is hollow and made of graphite, a first end member that is provided at a first end of the pipe portion in contact with the object to be temperature-measured, is made of graphite, and closes the first end, and a light-transmitting window that is installed near a second end opposite to the first end of the pipe portion in contact with the object to be temperature-measured and transmits light in the internal space of the pipe portion. The second end is closed, and a gas introduction hole for introducing gas from the outside into the internal space is formed near the second end. The temperature of the object to be temperature-measured is measured using the temperature measurement pipe, A step of burying the first end in the object to be temperature-measured; A step of introducing an inert gas from the gas introduction hole into the internal space to make the internal space in a positive pressure state; A step of measuring the temperature of the first end through the window; having; and at least one of the pipe portion or the first end member is composed of a porous body, The inert gas introduced from the gas introduction hole is discharged to the outside from at least one of the pipe portion or the first end member, so that the gas in the temperature measurement pipe is ventilated, Further, the temperature measurement pipe further includes a protection pipe that covers the outer surface of the pipe portion, The protection pipe is embedded in the packing material and the object to be temperature-measured so that the protection pipe is located at the boundary position between the upper part of the packing material and the atmosphere. One end of the protection pipe is buried in the packing material arranged around the object to be temperature-measured, and the other end of the protection pipe is exposed outside the packing material. A method for manufacturing a graphite material.

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