JPH031790Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is applicable to pressure sintering furnaces, hot isostatic pressing equipment (hereinafter abbreviated as HIP equipment), etc. under a gas pressurized atmosphere at 2000℃. The present invention relates to a high-temperature measuring device used at nearby temperatures, and in particular to the configuration of a thermocouple for high-temperature measurement.

(Conventional technology) In recent years, silicon nitride (Si ₃ N ₄ ) and silicon carbide (SiC)
Non-oxide ceramics such as
For _{Si3N4 , N2} atmosphere, temperature 1800-2100℃, pressure 0
~100Kgf/ ^cm2 pressure sintering furnace, _N2 atmosphere, temperature
The use of HIP equipment with a temperature of 1700 to 1800°C and a pressure of 1000 to 2000 Kgf/cm ² is being considered.

By the way, as a means of measuring the temperature inside these pressurized sintering furnaces or HIP equipment, it is preferable to use optical temperature measuring means such as a radiation thermometer because they are used in a high temperature range exceeding 1700°C. Since it is necessary to directly guide the emitted light from the furnace chamber to the sensor section, for example, in the HIP device shown in FIG.
Furthermore, it is necessary to provide openings 28 and 29 in the heat insulating layer 24 that provides thermal insulation between the inner wall of the pressure vessel and the furnace chamber 23 including the support member 25 and heater 26, respectively.

However, in this case, the opening 28 is located inside the pressure vessel 20.
In addition, the openings 29 expose the inner wall of the container to high temperatures due to the circulation of internal pressure gas and cause large heat loss, making it virtually impossible to apply optical temperature measurement means. Even in pressure sintering furnaces, applications up to about 10 Kgf/cm ² G are seen at best.

^Therefore , the currently commercially available W-
Re-based thermocouple (e.g., manufactured by HOSKINS, USA,
The only option left is to apply a Φ0.5, W-Re5/26 thermocouple).

Therefore, in the HIP device, etc., the commercially available thermocouple is inserted into an insulated tube, held at the upper end of the insulated tube, and the insulated tube and thermocouple are housed in a protective tube whose tip is closed. Attempts have been made to place it inside the insulation layer inside the pressure vessel.
Improvements have been made to the mounting means.

However, in the conventional method described above, the insulating tube and the thermocouple are always in contact with each other in a wide area of the high-temperature area, so it is virtually impossible to avoid shunt errors due to the deterioration of the electrical insulation properties of the insulating tube at high temperatures. , it was difficult.

Furthermore, the commercially available W-Re thermocouple mentioned above usually has a small wire diameter of about 0.5 mm, and when it is applied to a HIP device of 200 mmΦ and 500 mm length with a temperature range of 2000°C, the above thermocouple is Because the wires are small in diameter, wire breakage is likely to occur due to coarsening of the crystal grains, and in the end, the lifespan of the wires is limited to just one operation. This has become a major obstacle in bringing it to production.

Therefore, in order to solve the problems of the conventional method, the inventors of the present invention have conducted repeated studies, and have developed a high-temperature, high-pressure furnace in which thermocouple wires are housed in a vertically erected protective tube for protecting the atmosphere. In the temperature measuring device, the thermocouple wire is formed into large-diameter rod members on both the positive side and the negative side, and the thermocouple wire made of the rod member is held in the upper part of the protective tube, and both the rod members are connected at a point other than the temperature measuring junction. The present invention has proposed a device in which the rod members are suspended and held in the protective tube in a state where there is no mutual contact between the two rod members and the protective tube is not in contact with the protective tube at least in a high temperature region. (Jitsugan 59-
(No. 112928) However, in the above device, the protection tube is usually BN.
Since it was made of materials, the following drawbacks were discovered.

(1) Impurity components contained in the BN protection tube, such as low melting point substances such as B ₂ O ₃ used as sintering aids, evaporate at high temperatures and react with the thermocouple wire, reducing the service life. .

(2) Because the BN protection tube is not 100% dense, it is gas permeable, and impurity components generated when processing items in a high-temperature, high-pressure furnace mix into the atmospheric gas, and even enter the protection tube and cause thermoelectric conversion. It reacts with the wire and reduces the lifespan.

(3) The strength of BN protection tubes is not necessarily high, and therefore there are problems in terms of stability and durability as a structure.

(4) When a temperature measuring device is used in an electric furnace, electrical noise may be generated depending on the furnace configuration, but a BN protection tube does not have a shielding effect against electrical noise.

etc.

(Problems to be solved by the invention) Therefore, in view of the above-mentioned actual situation, the present invention addresses this problem and improves the accuracy of temperature measurement using thermocouples.
Our goal is to prevent the lifespan of W-Re thermocouples from decreasing, improve the efficiency of temperature measurement means for high-temperature and high-pressure furnaces, and eliminate obstacles to industrial production. The present invention aims to solve the above-mentioned drawbacks by focusing on the wire diameter and material of the protective tube, as well as the constituent material and support mode of the protective tube.

(Means for Solving the Problems) Therefore, the features of the present invention that are suitable for solving the above problems will be explained with reference to FIG. 1 showing its basic configuration. ,12
In a temperature measuring device for a high-temperature, high-pressure furnace, which is constructed by vertically erecting thermocouple wires 2 and 3 and housing thermocouple wires 2 and 3 therein, the thermocouple wires 2 and 3 are connected to the positive side 2 with a diameter larger than that of the conventional wire. and three negative side rod members, and a structure is provided for holding the thermocouple 1 made of the above rod members suspended above the protection tubes 11 and 12, so that the thermocouple 1 can be connected to the rod members other than at the temperature measuring junction. There is no contact between the rods and the protective tubes 11 and 12 except for the suspension holding part 13, and the thermocouples are held in a suspended state. −Re
The protection tubes 11 and 12 are made of a Mo-based or W-based high-melting point metal material, at least in their high-temperature regions.

Hereinafter, to explain this in more detail, firstly, the thermocouple is mainly composed of W or/and W-Re based materials, and the rod members on the plus side and minus side, which are the main parts, are usually the conventional thermocouple wires. Although it has a diameter of about 0.5mm, it has a much thicker and more rigid diameter,
Both the positive and negative sides are 3mm or more.

Each of these rod members is threaded at both ends, and is screwed into a rod member fastening button, or connected by interference fit, other mechanical means, or welding to form a thermocouple.

In this case, the material of the rod member fastening button may be either the material constituting the positive side or the negative side of the rod member of the thermocouple, but from the viewpoint of thread processing and strength, the material on the negative side has more ductility. It is preferable to use it as a material. However, it goes without saying that the thermocouple can be constructed using materials other than those on the positive side and negative side, and it is also possible to use materials with compositions intermediate between the two.

In addition, it is also preferable to use a tightening nut to further strengthen the screw connection between the rod member and the fastening button. In this case, the positive side of the nut is made of positive material and the negative side is made of negative material. It is preferable to manufacture such a material in order to prevent loosening caused by differences in thermal expansion coefficients of the materials and to stably generate thermoelectromotive force.

The thermocouple of the present invention, which has the above-mentioned configuration, has a large diameter, so disconnections due to coarsening of crystal grains are unlikely to occur, but it does not have the flexibility of a conventional thermocouple made of wire. Therefore, if one end of each rod member that serves as a temperature measurement junction is connected and the other end or the middle is fixed via an insulating member, the difference in thermal expansion coefficients of both rod members will cause deformation like that of a bimetal. In extreme cases, the thermal stress at this time may damage the rod member. Incidentally, W5
The linear expansion coefficient of %Re alloy is about 5×10 ^-5 /℃,
The linear expansion coefficient of W26%Re alloy is about 8×10 ^-5 /°C, and when both rod members are 1 m long at 2000°C,
The difference in elongation due to thermal expansion between the two rod members reaches approximately 6 mm. Therefore, in order to avoid problems caused by such a difference in thermal expansion between the two rod members, it is desirable that the end opposite to the temperature measuring contact be a free end so as to absorb this elongation.

Therefore, the thermocouple is supported inside the protective tube by a thermocouple suspension holding section provided at the upper part of the protective tube, so that there is no mutual contact between the two rod members other than at the temperature measuring junction.
Furthermore, the thermocouple is held suspended vertically downward in a state where there is no contact between each rod member and the protective tube other than the above-mentioned holding portion.

Here, the texture of the protective tube is an important feature of the present invention, together with the constituent material of the thermocouple.
Resistance at the 2000°C level, workability, cost, and securing an atmosphere for the thermocouple wires. Mo-based or W-based high melting point metal materials are preferably used.

Note that it is also possible to limit the use of the high melting point metal material to only a high temperature region of the 2000° C. level, and to use a low melting point metal material in the 100° C. or lower region.

On the other hand, in order to exhibit correct performance as a thermocouple, it is necessary to suspend the rod members on both the positive and negative sides without contacting each other other than at the temperature measuring junction, as described above. As mentioned above, since the member has a large diameter of 3 mm or more and sufficient rigidity, this can be easily achieved by controlling the verticality of the suspension holding part. Similarly, contact between each rod member and the protective tube at areas other than the suspension holding portion can be easily avoided.

By controlling the verticality of the above-mentioned suspension holding part, non-contact between the positive and negative side rod members and non-contact between the protective tube and both rod members other than at the temperature measuring junction can be easily achieved, but In order to achieve a stable structure, it is desirable to provide a structure below the suspension holding portion to restrict the distance between the two.

More preferably, the HIP apparatus includes a thermocouple rod member which has rigidity by providing the distance restraint part in a low temperature region below the upper end position of the sample installation table that serves as a heat insulator in the lower part of the furnace chamber; It is effective to limit contact with other third parties in the high-temperature furnace chamber area to the suspension holding part of the thermocouple rod member to avoid shunt errors due to the decrease in electrical insulation of the distance restraint member at high temperatures. It is.

Thus, as described above, for a protection tube unit in which a thermocouple made of a rod member is vertically suspended, a protection tube with one end closed to protect the atmosphere is arranged above the protection tube unit, and these The thermocouple unit 7 for high temperature measurement according to the present invention is ultimately constructed by vertically installing the entire unit in the furnace chamber 23 as shown in FIG. Suspension retention is achieved by making the upper part of the protective tube have an appropriate shape, or by placing a member with an appropriate shape on the upper part of the protective tube, such as an annular or a plurality of protrusions protruding inside the protective tube.
This can be easily achieved by bringing a thermocouple fastening button into contact with the same portion.

However, in this case, in the thermocouple suspension holding part, contact between the thermocouple and the holding member that suspends the thermocouple is unavoidable, and the thermocouple constituent material and the protection tube constituent material may interdiffuse based on the contact part. This results in disadvantages such as a decrease in thermoelectromotive force, or it becomes difficult to replace the thermocouple after its life has been reached due to adhesion to the protective tube.

Therefore, as a means to improve this problem, it is preferable to insert an appropriate material into the thermocouple suspension holding part, taking reactivity into consideration. In particular, the amount of this part can be reduced by making the structure appropriate, so pressure properties, costs, etc. can be relatively ignored, and the material can be selected with priority given to performance. For example, BeO, which has excellent electrical insulation properties but has toxicity issues, ThO ₂ , which has radioactivity issues, and HfO ₂ , which is expensive in terms of cost.
It is _also possible to use _Y2O3 . Furthermore, Al ₂ O ₃ and ZrO ₂ can also be used depending on the temperature.

Note that these materials can be installed as structural materials, for example, as a ring-shaped part on the suspension holder, or as a button-shaped part and attached to the bottom surface of the thermocouple fastening button. It is also possible to coat the bottom surface of the button.

As a coating method, vacuum deposition, sputtering, PVD, CVD, thermal spraying, etc. are used.

Furthermore, once a thermocouple is removed from an assembled protection tube after its life has been reached, there is a high possibility that the high melting point metal parts that make up the protection tube will stick together and become impossible to disassemble, so protect the thermocouple. It is preferable to have a structure in which the pipe can be suspended by inserting it into the suspension holding part from below and hooking it there.

Furthermore, in the thermocouple unit configured as described above, it is effective to ground the protective tube from the viewpoint of avoiding electrical noise to the thermocouple.

(Embodiments) Hereinafter, embodiments of the present invention will be described further based on the accompanying drawings.

Fig. 1 shows an example of a thermocouple unit that forms the main part of the device of the present invention. In the figure, T is the thermocouple unit, 1 is a thermocouple configured with a screw fastening structure, and 2 is the positive side of the thermocouple. The rod member 3 is also a minus side rod member of the thermocouple, and both of these rod members 2 and 3 are threaded at both their upper and lower ends, and female threads are machined at two places to screw both rod members 2 and 3. A protective tube 12 whose upper threaded portion is screwed into a fastening button 4 provided with a screw thread, and further tightened with fastening nuts 5 and 6 to further strengthen the screw connection, and both rod members 2 and 3 are accommodated therein. It is a distance restraining member that is suspended vertically downward in the protection tube 12 by a suspension holding part 13 provided at the inner upper part, and has an insulating property to maintain a stable distance between both rod members 2 and 3. The thermocouple 1 is formed by disposing the lower spacer 14 in a lower low-temperature region where the spacer maintains sufficient insulation, and the lower end of the rod member protruding downward also connects the nut 5 to the lower threaded portion. By tightening nuts 7 and 8 made of the same material and shape as 6, it is connected to lead wires 9 and 10 (not shown) which facilitate connection to a temperature recorder or the like.

Therefore, the thermocouple configured as described above further has a protective tube 11 with a closed tip on the upper part of the protective tube 12.
The atmosphere is protected by placing

In the above configuration, the materials of both rod members 2 and 3 are W and W- for the positive rod member 2.
The negative side rod member 3 is made of a material corresponding to the positive side rod member 2, such as positive side material W and W-5%Re. Correspondingly W-26% Re, W
Corresponding to -3%Re, W-25%Re materials are usually used, and the rod diameter is determined to ensure rigidity, facilitate thread processing, especially female thread processing for mating, and expectations when applied to industrial equipment. 3mm from the viewpoint of lifespan
That's all.

Further, the fastening button 4 into which the rod member is screwed
As shown in FIG. , 7, and 8 are made of the same material as the positive rod member 2 on the positive side, and the same material as the negative rod member 3 on the negative side.

Further, as the lead wires 9 and 10 for facilitating connection from the large diameter rod members 2 and 3 to a temperature recorder, etc., for example, a commercially available 0.5 mmΦ W-Re compensation conductor made by HOSKINS may be used. used.

FIGS. 2 to 5 show other embodiments of the present invention, the basic configuration of which is the same as that described with respect to FIG. 1 above, and the same parts are designated by the same reference numerals. ing.

First of all, FIG. 2 shows a suspension holding section 13a for holding the protection tube in order to facilitate the processing of the thermocouple suspension holding section 13 provided at the upper part of the protection tube, compared to FIG. 1.
A protection tube 12a with a protection tube 12a and a protection tube 1 without it.
It is constructed by combining both of 2b.

On the other hand, in FIG. 3, a ring-shaped upper spacer 14 made of a different material from the protective tube is inserted between the thermocouple suspension holding part 13 and the fastening button 4, and contact is made between the thermocouple and the suspension holding part 13. This prevents a decrease in the thermoelectromotive force due to mutual diffusion of metal materials, or the impossibility of replacing the thermocouple after its life has been reached due to adhesion of the metal materials.

Further, in FIG. 4, a button-shaped upper spacer 4 is attached to the thermocouple side, thereby achieving the same effect as in FIG. 3.

It should be noted that these different materials can be inserted by installing them as parts as shown in FIGS. It is also possible to achieve the same structure as shown in FIG. 1 by fixing different materials to the lower and side surfaces of the structure.

FIG. 5 shows that by making the planar shapes of the thermocouple suspension holding part 13 and the fastening button 4 as shown in FIG. This is made possible by rotating it 90 degrees.

By applying this structure to the configurations shown in Figures 3 and 4, even if it becomes impossible to disassemble the assembled protection tube after high-temperature use, the thermocouple can be easily replaced from below the protection tube. can be carried out, which helps reduce costs.

The configuration of the thermocouple unit used in the device of the present invention is as described above, and it goes without saying that in addition to the above examples, it can be modified as appropriate without changing the gist of the thermocouple unit.
It is installed inside a high-temperature, high-pressure furnace such as a HIP device to measure the temperature inside the furnace.

FIG. 6 shows, as an example, a mode in which the HIP device is installed in a high-temperature, high-pressure furnace, and is attached to the inner side of the heater 26 inside the heat insulating layer 24 by a support member 27.

In this case, by constructing the support member 27 from a metal material and further electrically short-circuiting it to the lower lid of the pressure vessel, it is possible to make the protective tube exhibit an electrical shielding effect, thereby providing protection to the heating device. It is possible to construct a stable temperature measurement device that is not affected by electrical noise caused by power input.

Thus, the device of the present invention achieves the purpose of temperature measurement at high temperatures without using an insulating tube by using the above-mentioned thermocouple unit, and is effective for temperature measurement inside high-temperature and high-pressure furnaces.

Next, an actual test situation using the temperature measuring device of the present invention will be described.

(Test example 1) W with a rod diameter of 3 mm and a length of 800 mm as a thermocouple wire
Prototype of -5%Re and W-26%Re rod members,
M3 x 0.5 screws were machined on both ends. In addition, W-26%Re is used as a fastening button, and W- is used as a nut.
A prototype of 5% Re and W-26% Re was made using the same lot as the thermocouple rod member manufacturing material.

On the other hand, we prototyped a protection tube made of tungsten to hold the thermocouple rod member suspended and protect the atmosphere.The thermocouple was held vertically in the protection tube, and the distance between the thermocouple rod members was fixed at the bottom of the protection tube. A thermocouple unit was constructed by arranging an insulating spacer for restraint. Thus, with the above configuration, contact between the thermocouple rod member and the protective tube is limited to only the suspension holding portion. Then, this thermocouple unit was incorporated into the HIP equipment, and Ar1000Kgf/cm ² ×
A repeated durability test was conducted at 2000°C for 1 hour. At this time, for comparison, 0.5mmΦ manufactured by HOSKINS,
A W-Re5/26 thermocouple, a 1.0 mmΦ thermocouple, and a W-Re5/26 thermocouple are each inserted into an insulating tube as is commonly done, and held at the upper end of the insulating tube. A thermocouple unit was created in which the thermocouple was housed in a protective tube with a closed end, and a similar test was conducted using these as a control product. As a result, the life of a 0.5mmΦ thermocouple is 1 cycle at most, 1.0
While the lifespan of the mmΦ thermocouple was 2 to 3 cycles, the prototype thermocouple was able to secure a lifespan of at least 23 cycles within a guaranteed accuracy range of ±1.0%.

(Test Example 2) Next, in addition to the above configuration, BeO was added as a spacer between the thermocouple suspension holding part and the fastening button.
A durability test was conducted using ThO ₂ , HfO ₂ , and Y ₂ O ₃ .

This result is true for any of the above combinations.
In a repeated durability test of Ar1000Kgf/ ^cm2 x 2000℃ x 1hr, it was possible to secure a life of at least 25 cycles with an accuracy guarantee of ±1%, and the thermocouple could be easily removed after use.

(Effects of the invention) As described above, the present invention makes the thermocouple wire a rod member with a larger diameter than usual in a temperature measurement device for a high-temperature and high-pressure furnace, and also provides a suspension holding section on the upper part of the protective tube to create a thermocouple made of the rod member. is held in the upper part of the protection tube, and is suspended so that there is no mutual contact between the two rod members except at the temperature measuring contact, and there is no contact with the protection tube except at the suspension holding part. The use of this thermocouple rod member prolongs the life of the thermocouple wire until it breaks due to coarsening of the crystal grains, and increases resistance to contamination by impurity gas components in the atmosphere, resulting in a significant improvement in life. This reduces the frequency of thermocouple replacement and increases the effectiveness of the temperature measuring device under high temperature and high pressure.
In addition to having the remarkable effect of facilitating the industrial production of high-temperature, high-pressure furnaces such as HIP equipment, this invention allows thermocouples to be suspended in the protective tube using a suspension holding section, and at least the conventional insulated tube is used in the high-temperature section. This is not only economical, but also prevents the occurrence of shunt errors due to the deterioration of the electrical insulation properties of the insulating tubes at high temperatures, which was a problem in the past. It also prevents power loss and enables extremely stable and highly accurate temperature measurement.

Moreover, in the present invention, the thermocouple rod member is suspended from the upper part of the protection tube, so that the lower part is free, and therefore the elongation due to thermal expansion of the individual rod members can be absorbed below, unlike the conventional thermocouple rod member. It has the feature that it does not cause damage due to thermal expansion, which is often seen in thermocouples using insulated tubes.
Re-based material and Mo-based or W as a protective tube.
Because it uses a high-melting point metal material, it has durability at 2000℃ level, workability, cost, and ensuring an atmosphere for thermocouple wires.In other words, it is possible to prevent impurities in the gas from entering the furnace interior gas through the protective tube wall, and to prevent thermocouples from entering the furnace. Prevention of deterioration of the thermocouple due to reaction with the pair of wires, prevention of deterioration of the thermocouple due to impurity components contained in the protection tube evaporating at high temperatures and reacting with the thermocouple wire, and furthermore, shielding effect against electrical noise. The following effects are expected.

[Brief explanation of the drawing]

Figure 1A shows one of the thermocouple units in this invention.
A partially omitted internal structure diagram showing an example, FIG. 1B is a view taken along the arrow A-A in FIG. FIG. 5A is a partially omitted internal structure diagram showing another embodiment of the thermocouple unit used in the present invention; FIG.
The figure is a cross-sectional schematic diagram showing the arrangement of thermocouples in a HIP device. Figure 7 shows a conventional temperature measurement method.
FIG. 2 is a cross-sectional schematic diagram of the HIP device. T...Thermocouple unit, 1...Thermocouple, 2...
Positive side rod member, 3... Minus side rod member, 4... Rod member fastening button, 5, 6...
Upper nut, 7, 8...Lower nut, 9, 1
0... Lead wire, 11, 12, 12a, 12b...
...Protection tube, 13, 13a... Suspension holding part, 14,
14, 14... Spacer, 20... Pressure vessel,
23... Furnace room.

Claims (1)

[Claims for Utility Model Registration] 1. A thermocouple wire is housed in a vertically erected protective tube for protecting the atmosphere, and the thermocouple wire is made into a rod member with a large diameter on both the positive and negative sides,
In addition, the thermocouple consisting of both rod members is held at the upper part of the protective tube so that there is no mutual contact between the two rod members other than at the temperature measuring junction, and furthermore, there is no contact between each rod member and the protective tube other than at the above-mentioned holding part. In a temperature measuring device for a high-temperature and high-pressure furnace, which is suspended in a protective tube, the thermocouple is
A temperature measuring device for a high-temperature and high-pressure furnace, characterized in that the protection tube is made of a Mo-based or W-based high-melting point metal material at least in its high-temperature region. 2. The temperature measuring device for a high-temperature and high-pressure furnace according to claim 1, wherein the diameter of the rod member of the thermocouple is 3 mm or more. 3. Scope of claim for utility model registration, Paragraph 1, in which the non-contact of the thermocouple rod member other than the temperature measuring junction and the non-contact between the rod member and the protective tube are achieved by restricting the distance between the two in the lower low temperature region Or a temperature measuring device in a high-temperature, high-pressure furnace according to item 2. 4. The temperature measuring device for a high-temperature and high-pressure furnace according to claim 3, wherein the means for restricting the distance between the two for non-contact in the lower low-temperature region is an electrically insulating spacer having a rod member insertion hole. 5. The temperature measuring device for a high-temperature, high-pressure furnace according to any one of claims 1 to 4, wherein the protection tube is provided with a suspension holding part for holding a thermocouple suspended in the upper part of the tube. 6. Utility model registration as described in any one of claims 1 to 5, in which the thermocouple is held suspended in the protective tube by bringing the lower surface of the rod member fastening button into contact with the suspension holding part at the upper part of the tube. Temperature measurement device for high-temperature and high-pressure furnaces. 7 Utility model registration claims 5 or 6, in which the suspension holding part at the upper part of the protection tube that holds the thermocouple in suspension and/or the lower surface of the button for fastening the rod member of the thermocouple are made of a different material from the protection tube. Temperature measuring device for a high-temperature, high-pressure furnace as described in 2. 8 Claim No. 7 for Utility Model Registration in which the means for constructing the protective tube and a different material is the attachment or coating of a different material spacer to each of the suspension holding part at the upper part of the protective tube and the button for fastening the rod member.
Temperature measuring device for a high-temperature, high-pressure furnace as described in 2. 9 Different materials include BeO, ThO ₂ , HfO ₂ , Y ₂ O ₃ ,
The temperature measuring device for a high-temperature, high-pressure furnace according to claim 7 or 8, which is at least one member selected from the group consisting of Al ₂ O ₃ and ZrO ₂ . 10. A temperature measuring device for a high-temperature, high-pressure furnace according to any one of claims 1 to 9, wherein the thermocouple can be suspended from the lower part of the protection tube to the upper suspension holding part within the protection tube. 11. A temperature measuring device for a high-temperature, high-pressure furnace according to any one of claims 1 to 10 of the utility model registration claim, wherein the protective tube is electrically grounded.