JP2008202961A - Heating furnace, and thermophysical property value measuring device using heating furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress thinning of a heater and occurrence of spark, also prevent occurrence of cyanogen, and efficiently raise temperature. <P>SOLUTION: Body space that is surrounded by a furnace material and has the heater is shut off into a sample space and a heating space outside it with a soaking cylinder, a sample gas supplying means supplies sample atmosphere to the sample space, and a heater gas supplying means supplies heater atmosphere to the heating space. As the heater atmosphere, inert gas that does not invade the heater, for example helium gas, is used. In this case, for preventing heat dissipation from a furnace peripheral wall from increasing, the furnace peripheral wall is covered with a vacuum insulation layer allowing achievement of the thermal conductivity of about 1/10 of that of the atmospheric pressure. Thus, the temperature is raised more efficiently. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heating furnace and a thermophysical property measuring apparatus, and more particularly to a heating furnace that can withstand measurements up to about 2,000 ° C. and a thermophysical property measuring apparatus including the heating furnace.

  In order to measure the physical properties of a substance at a high temperature, it is necessary to put the substance into a heating furnace.

  FIG. 7 shows a conventional thermophysical property measuring apparatus equipped with a heating furnace.

  A heater 5 is disposed in the interior space of the furnace body 4, and a sample stage 8 is disposed in the center surrounded by the heater 5, and an optical window for laser irradiation provided outside the furnace body 4. The sample is irradiated with a laser from 71 for a short time. As a result, the temperature of the sample changes slightly, but the state of this temperature change is analyzed by measuring the intensity of the infrared radiation from the measurement optical window 72 provided outside the furnace body 4. It is configured.

  The furnace body 4 is kept in a vacuum, or atmospheric gas is circulated to keep the temperature in the furnace uniform.

In this configuration, a sample is placed on the sample stage 8 during measurement, and a pulse laser is emitted from the laser irradiation optical window 71 in a state where nitrogen gas or Ar gas is circulated in the internal space of the furnace body 4 as an atmospheric gas. To do. As a result, the temperature on the side irradiated with the laser (the front side of the sample) rises by 1 to 2 degrees, and this temperature gradually propagates to the entire sample. This temperature change also appears on the back side of the sample, and its state is measured by measuring infrared light emitted from the back side of the sample through the optical window 72 for measurement, thereby allowing the sample to have thermal properties such as thermal conductivity, specific heat, and the like. Etc. can be measured.
Japanese Patent Laid-Open No. 2004-132587

  In the above conventional configuration, a common atmosphere is used for the sample and the heater, and nitrogen gas or Ar gas is used as the sample gas. However, when Ar gas is used, when the furnace temperature reaches around 2000 ° C., Ar gas is ionized, and a phenomenon (spark) in which a large current flows suddenly between the heaters occurs, which is in a dangerous state. . This phenomenon is solved by mixing a small amount of nitrogen into Ar.

  When graphite is used as the heater material, the thickness (about 10 mm) increases, so the volume of the apparatus increases. Therefore, the C / C composite (carbon / carbon composite material) with a small thickness (about 1 mm) is used to reduce the volume of the equipment, but if a C / C composite heater is used, 2000 is the same as graphite. It will produce highly toxic cyanide at high temperatures around 0 ° C, which is also dangerous. Of course, there is a similar danger when using nitrogen gas alone.

  The configuration disclosed in Japanese Patent Laid-Open No. 2004-132587 is an attempt to solve the above problems. That is, the inside of the furnace is separated into a heating space where a C / C composite heater exists and a sample space where a sample to be heated is placed, and by using He gas that is not easily ionized even at high temperatures, sparks are generated between the heaters. The structure which prevents generation | occurrence | production and uses Ar gas for sample space is shown. According to this configuration, since the heat conductivity of the He is high, there is a difficulty that the temperature in the furnace does not increase. Therefore, it has been proposed to cover the outer periphery of the furnace with Ar gas having a low thermal conductivity.

  However, although the thermal conductivity of Ar gas is low, it is 0.018 / mk at room temperature and normal pressure, and is even greater at high temperatures. Therefore, it was insufficient to expect an efficient temperature rise.

  The present invention suppresses the occurrence of sparks due to the thinning of the heater and the ionization of the atmosphere even at 2000 ° C. or higher, further prevents the generation of cyan, and further enables an efficient temperature increase to be obtained. An object of the present invention is to provide a furnace and a thermophysical property measuring apparatus.

  The present invention employs the following means in order to achieve the above object.

  The main body space surrounded by the furnace material and provided with a heater is shut off by a soaking tube between the sample space and the external heating space, and the sample gas supply means supplies the sample atmosphere to the sample space. Furthermore, the heater gas supply means is a heater gas supply means for supplying a heater atmosphere to the heating space.

  An inert gas that does not attack the heater, such as helium gas, is used as the heater atmosphere. In this case, for the purpose of preventing the heat dissipation from the furnace peripheral wall from increasing, the peripheral wall of the furnace is covered with a vacuum heat insulating layer that can achieve a thermal conductivity of about 1/10 at atmospheric pressure.

  When this furnace is used as a thermophysical property measuring apparatus, an optical window for irradiating the sample with laser light and an optical window for measuring changes in the temperature of the sample are provided.

  Here, the sample gas supply means corresponds to the gas inlet 701, the sample space 401, and the gas outlet 702 in the following description. The heater gas supply means corresponds to the gas inlet 310, the gas inlet space 31, the heating space 402, the gas outlet space 32, and the gas outlet 320 (see FIGS. 2 and 4).

  As described above, by providing a soaking cylinder that cuts off the main body space into the sample space and the external heating space, different atmospheric gases can be used in the sample space and the external heating space. Therefore, when a small and highly efficient C / C composite is used as the heater, even if an oxygen-containing gas is used in the sample space, the oxygen-containing gas does not come into direct contact with the heater by the soaking tube, so the problem of thinning is not Does not occur. Further, as the heater atmosphere, a gas that does not ionize at a high temperature, that is, a gas having a stable heater function, such as helium gas, can be used. Furthermore, when helium gas is used, heat dissipation from the furnace peripheral wall due to high thermal conductivity (furnace temperature does not increase) becomes a problem, but by providing a vacuum heat insulating layer on the peripheral wall of the furnace, Ar gas This can be prevented with less power compared to the thermal insulation layer.

   FIG. 1 is an overall perspective view of a thermophysical property measuring apparatus of the present invention, and FIG. 2 is a longitudinal sectional view of a furnace section.

  A furnace body 4 surrounded by a furnace material is attached to a base 2 fixed to the base plate 1 via a gas introduction space 31 (described later). In addition, a strip-shaped C / C composite heater 5 is disposed along the cylindrical shape in the center of the internal space 40 (furnace space) of the furnace body 4. The soaking cylinder 6 in the vertical direction opening in the floor 42 is arranged.

  Note that the C / C composite heater is a heater formed of a carbon fiber made of carbon and a carbon composite material (C / C composite material) obtained by using carbon fiber as a core material. In addition, as shown in FIG. 5, the C / C composite heater includes six U-shaped plate members 51 of the C / C composite material arranged along a cylindrical shape, and is electrically connected in series. It has a connected shape. The electrode terminals 52a and 52b protrude into the gas outlet space 32 (described later), and are further led out of the furnace through an upper lid 94 (described later).

  The lower end position of the soaking tube 6 is airtightly fixed with respect to the hearth 42, and the upper end of the soaking tube 6 is attached to an upper lid (described later) 94 via the furnace ceiling 41. The boundary between the furnace top 41 and the soaking tube 6 is fixed in an airtight manner. With the configuration of the soaking tube 6, the furnace space 40 is separated into a sample space 401 inside the soaking tube 6 and an external heating space 402.

  The upper end of the cylindrical column 7 penetrates the base plate 1 and the pedestal 2 from the lower side of the base plate 1 and further through the hearth 42, and the sample table 8 at the center of the soaking tube 6 (center of the furnace space). The measurement optical window 72 for measuring the temperature change of the back surface of the sample is provided at the lower end.

  A cylindrical light guide tube 61 is further disposed at the upper end of the soaking tube 6, and an optical window 71 is disposed at the upper end position of the light guide tube 61. With this configuration, the sample S (the front side of the sample S) can be irradiated with laser light from the optical window 71. Further, as described above, the measurement optical window 72 for measuring the intensity of infrared rays radiated from the sample S (the back side of the sample S) (corresponding to the temperature change of the sample S) is provided below the support column 7. The thermophysical properties can be measured.

  A gas introduction space 31 and a gas lead-out space 32 are provided above and below the furnace body 4, and each space communicates with the heating space 402. Further, a gas introduction port 310 communicating with the gas introduction space 31 and a gas discharge port 320 communicating with the gas outlet space 32 are provided, and the heater atmosphere is circulated or sealed in the heating space 402.

  A gas inlet 701 for supplying a sample gas to the sample space 401 is provided near the upper end of the light guide tube 61 (below the irradiation optical window), and the sample gas introduced into the sample space 401 therefrom. Is discharged from a gas discharge port 702 provided at the lower end of the cylindrical column 7. With this configuration, it is possible to flow or seal separate atmospheres in the sample space 401 and the heating space 402, respectively.

  Further, the sample gas can adjust its oxygen partial pressure, and passes through the oxygen partial pressure regulator 510 (see FIG. 6) at a stage before being introduced into the gas inlet 701. become.

Between the outer cylinder 20 that covers the side wall of the furnace and the side wall 43 of the furnace, a vacuum heat insulating layer 21 and a water cooling layer 22 are provided in order from the inside. A pipe 210 for connecting the vacuum heat insulating layer 21 to the vacuum exhaust unit 511 (see FIG. 6) is led out of the furnace. As a result, the vacuum heat insulating layer 21 is evacuated. Further, a water cooling layer 22 is provided between the vacuum heat insulating layer 21 and the outer cylinder 20, and cooling water can be circulated through the water cooling layer 22 using the inlet port 221 and the outlet port 222. (See FIG. 4, H ₂ O (3)). Further, a water cooling layer 301 is also provided at the boundary between the support column 7 and the base plate 1, and the water introduced from the inlet 311 is between the support plate 7 and the base plate 1, and between the base plate 1 and the base 2. (See FIG. 4, H ₂ O (1)).

  The lower end of the outer cylinder 20 is integrated with the receiving ring 91, and the upper end is sealed with an upper lid 94 via a lower receiving ring 92 and an upper receiving ring 93. The introduction port 221 communicates with the cooling layer 22 through a lower receiving ring 91, and the discharge port 222 communicates with the cooling layer 22 through a receiving ring 92. Further, the pipe 210 communicates with the vacuum heat insulating layer 21 through a receiving ring 93.

The upper end of the soaking tube 6 communicates with the light guide tube 61 at the upper end position of the upper lid 94, and the light guide tube 61 protrudes above the upper lid 94. For the purpose of cooling the outer periphery of the protrusion, a water cooling layer 610 and a water introduction port 611 and a discharge port 612 communicating with the water cooling layer 610 are provided. (See FIG. 4, H ₂ O (2)).

  Thermocouples 101 and 102 are inserted into the heating space 402 from the center outside of the outer cylinder 20 so that the temperature of the heating space 402 can be measured. Of the two thermocouples, one is used for control and the other is a spare.

  The outer cylinder 20 is composed of an outer stainless steel layer and an inner heat insulating material layer.

  Further, the furnace body 400 (a configuration centering on the furnace body 4 above the receiving ring 91) is connected to a lifting means (not shown) so that the entire furnace can be lifted and lowered with respect to the base plate 1 by the lifting means. . With this configuration, the sample body can be inserted and removed by raising the furnace body 4 with respect to the base plate 1 and exposing the sample stage 8 to the outside of the furnace. The lower end of the support column 7 is installed on the pedestal 2.

  FIG. 6 is a block diagram showing a system in which the thermophysical property measuring apparatus according to the present invention is used.

  The laser oscillated from the laser unit 501 is collected by the lens 503a, transmitted by the optical fiber 502, further collected by the lens 503b, and incident on the apparatus through the optical window 71. The light transmitted through the optical fiber 502 has a uniform intensity distribution in the optical fiber 502 by the mode mixer 504. The intensity distribution of the laser beam can be observed with the beam profile monitor 521 and the monitor 522.

  As a result, the front side of the sample S placed on the sample stage 7 is irradiated with the pulse laser, whereby the temperature on the front side of the sample S rises by 1 to 2 ° C. and gradually propagates to the back side. As described above, the measurement optical window 72 is provided with the radiation thermometer 505, and this temperature rise state can be grasped by measuring the intensity of infrared rays emitted from the sample S. For this measurement, a differential amplifier 506 and an analysis PC 507 are provided.

  During measurement, He gas is used as a heating atmosphere. While the ionization potential value of He gas is 24.487 eV, the ionization potential value of Ar gas conventionally used is 15.759 eV, and He gas has a higher ionization potential value.

  Therefore, even if the temperature exceeds 2,000 ° C., the He gas is not ionized (ionized), and the C / C composite heater does not spark. On the other hand, because the heat conductivity of He gas is very high (about 10 times that of Ar gas), heat radiation from the furnace body 4 becomes excessive, heat loss increases, and the furnace temperature does not rise. Become.

  Therefore, the vacuum heat insulating layer 21 is evacuated by using the vacuum exhaust unit 511 to reduce the heat loss. In the above configuration, the sample S is placed in an environment of 2000 ° C. or higher. When the composition of the sample S is an oxide, the composition itself of the sample S may change under the above environment. Therefore, in the present invention, the sample space 401 and the heating space 402 are separated, and Ar added with oxygen is used for the sample space 401. The amount of oxygen added can be adjusted by an oxygen partial pressure regulator 510. Of course, when the composition is a binary material containing a substance other than oxygen or a plurality of materials, a gas corresponding thereto can be added to Ar.

  With the above configuration, it is possible to heat the sample S at a high temperature of 2000 ° C. or higher without causing a spark in the heater and without changing the composition of the sample S.

  FIG. 3 shows a differential calorimetry method in which a pulse laser is simultaneously irradiated onto the measurement target sample S2 and the reference sample S1.

  When the measurement target sample S1 and the reference sample S2 placed on the sample stage 8 of the furnace body 4 are irradiated with the pulse laser beam on the front side, the temperature of each sample rises slightly, and the corresponding infrared rays are emitted. . Infrared light emitted from the back side of each of the samples S1 and S2 is received by the light receiving element of the radiation thermometer 505 through the optical system, photoelectrically converted and output. As a result, the differential amplifier 506 can obtain an output change when the temperature of the sample S1 to be measured changes by ΔTm and an output change when the temperature of the reference sample S2 changes by ΔTr. Here, since the specific heat of the reference sample S2 is known in advance, the specific heat of the measurement target sample is obtained from a comparison between the temperature increase of the reference sample S2 and the temperature increase of the measurement target sample S1, and the measurement target sample S1. The thermal diffusivity is obtained from the response time of the temperature rise. Furthermore, thermal conductivity is calculated | required from the said specific heat and thermal diffusivity. That is, the thermal characteristics (thermal conductivity, thermal diffusivity, specific heat) can be obtained.

  As described above, it is possible to use different atmospheric gases in the sample space and the external heating space by providing a soaking cylinder that cuts off the main body space of the furnace into the sample space and the external heating space. . Therefore, when a small and highly efficient C / C composite is used as the heater, even if an oxygen-containing gas is used in the sample space, the oxygen-containing gas does not come into direct contact with the heater by the soaking tube, so the problem of thinning is not Does not occur. As the heater atmosphere, a gas having a stable heater function at a high temperature, such as helium gas, can be used. Further, when helium gas is used, heat dissipation from the furnace peripheral wall due to high thermal conductivity becomes a problem, but this can be prevented by providing a vacuum heat insulating layer on the peripheral wall of the furnace.

  In the above description, only the thermophysical property measuring apparatus has been described, but the present invention can of course be used as a heating furnace by not providing the optical window for laser incidence and the optical window for measurement.

  In the present invention, the main body space covered with the furnace material is separated into the heating space and the sample space, and an atmosphere suitable for each space is supplied. In addition, since a vacuum layer is provided on the peripheral wall of the furnace, heat dissipation from the furnace can be suppressed, and a high temperature can be obtained with a small amount of electric power, and industrial applicability is great.

1 shows an overall perspective view of a thermophysical property measuring apparatus of the present invention. The longitudinal cross-sectional view of the thermophysical property measuring apparatus of this invention is shown. 1 shows a cross-sectional view of a thermophysical property measuring apparatus of the present invention. It is a conceptual diagram which shows the cooling system of the thermophysical property measuring apparatus of this invention. It is a conceptual diagram of the C / C composite used for this invention. 1 shows a system to which a thermophysical property measuring apparatus of the present invention is applied. 1 shows a conventional thermophysical property measuring apparatus.

Explanation of symbols

4 Furnace material 5 Heater 6 Soaking tube 21 Vacuum heat insulating layer 40 Main body space 401 Sample space 402 Heating space 71, 72 Optical window

Claims (7)

A main body space surrounded by furnace materials,
A heater for heating the main body space;
A soaking tube that is arranged inside the heater and that cuts the main body space into a sample space and a heating space outside thereof,
Sample gas supply means for supplying a sample atmosphere to the sample space;
A heater gas supply means for supplying a heater atmosphere to the heating space;
A heating furnace comprising a vacuum heat insulating layer covering the furnace material peripheral wall.   The heating furnace according to claim 1, wherein an inert gas that does not invade the heater is used as the heater atmosphere.   The heating furnace according to claim 2, wherein the inert gas that does not attack the heater is helium. A main body space surrounded by furnace materials,
A heater for heating the main body space;
A soaking tube that is arranged inside the heater and that cuts the main body space into a sample space and a heating space outside thereof,
Sample gas supply means for supplying a sample atmosphere to the sample space;
A heater gas supply means for supplying a heater atmosphere to the heating space;
An optical window for irradiating the sample placed in the sample space with a laser from outside the furnace;
An apparatus for measuring thermophysical properties, comprising: an optical window for measuring a sample temperature changing based on the laser irradiation from outside the furnace; and a vacuum heat insulating layer covering the peripheral wall of the furnace material.   A cylindrical column having the optical window provided at one end of the soaking tube extending outside the furnace, the measurement window being inserted into and withdrawn from the other end of the soaking tube, and a sample stage accommodating the sample at the tip. The thermophysical property measuring apparatus according to claim 4, which is provided at the rear end.   The thermophysical property measuring apparatus according to claim 4, wherein an inert gas that does not invade the heater is used as the heater atmosphere.   The thermophysical property measuring apparatus according to claim 6, wherein the inert gas that does not attack the heater is helium.

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