JP3547046B2 - Probe for measuring thermal conductivity - Google Patents

Description

【００２４】
図６は、実施例１において測定した、温度上昇ー対数時間線図である。線図１は測定試料の温度が７００℃の場合であり、線図２は測定試料の温度が１０００℃の場合である。また、熱伝導率の測定結果は図７の通りある。他の実施例でも同様の結果が得られ、精度の良い測定ができることを確認した。
【００２５】
【発明の効果】
本発明の熱伝導率測定装置により、高温における材料の熱伝導率が測定でき、製造条件を検討するための貴重なデータを得ることを可能にした。
【図面の簡単な説明】
【図１】測定用プローブと試料容器の配置を示す概略側面図。
【図２】本発明の測定用プローブの断面を示す図。
【図３】図２Ａ−Ａ’の断面を示す図。
【図４】本発明の実施例の結果を示す図。
【図５】熱伝導率測定装置の全体を示す概略側面図。
【図６】時間経過に対する温度変化を示すグラフ。
【図７】実施例１で測定した、試料温度に対する熱伝導率を示すグラフ。
【符号の説明】
１ 電源
２ 加熱用配線
３ 試料容器
４ 電気炉
５ 測定用プローブ
６ 温度測定用配線
７ データ収録装置
８ データ処理装置
９ 測定用プローブ管
１０ 熱電対温度計
１１ 保護管
１２ 加熱線
１３ 充填剤
１４ 測定試料
１５ 蓋
１６ ストッパー[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe for measuring the thermal conductivity of glass in a temperature range from a liquid state molten at a high temperature to a solid state , particularly for a glass material.
[0002]
[Prior art]
Thermal conductivity measurement methods include a flat plate steady state method, an unsteady laser flash method, and an unsteady fine wire heating method. Particularly in the measurement of the thermal conductivity of a fluid, it is important to remove the influence of thermal convection of the fluid, and the unsteady fine wire heating method is often used.
[0003]
[Problems to be solved by the invention]
In order to accurately measure the thermal conductivity of a material such as glass that changes from a solid to a liquid at high temperatures, it is difficult to make a cell that can continuously measure from a solid to a liquid using the steady-state flat plate method. In the transient laser flash method, although the measurement accuracy is good for a solid at room temperature, it is difficult to measure the thermal conductivity reliably in a liquid state at a high temperature. When measuring the thermal conductivity in such a high-temperature liquid, it has been difficult to obtain highly reliable results.
[0004]
[Means for Solving the Problems]
A probe for measuring the thermal conductivity of glass in the temperature range from the liquid state melted at a high temperature to the solid state by the unsteady fine wire heating method, having both a heating element and a thermocouple for temperature measurement . The thermocouple for temperature measurement is connected in series, the measurement distance of the thermocouple for temperature measurement is 50 times or less of the wire diameter of the thermocouple, and the outer diameter of the probe for measurement is 1.5 mm or more. This is a probe for measuring the thermal conductivity of glass having a size of 5 mm or less.
[0005]
This is a probe for measuring the thermal conductivity of the above glass having a thermocouple wire diameter of 0.5 mm or more and 1 mm or less.
Further, the inside of the protective tube of the measuring probe is filled with magnesium oxide powder , and the protective tube is a probe for measuring the thermal conductivity of the above glass made of a platinum-rhodium alloy.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic side view of a sample container 3 for storing a measurement probe 5 and a measurement sample 14. 2 and 3 are schematic views of a cross section of the measurement probe of the present invention using two thermocouples. Two or more thermocouples are used to increase the temperature measurement sensitivity. The outer diameter dp of the measurement probe tube 9 is set in a range of 1.5 mm to 5 mm. The measurement probe tube 9 is provided with a thermocouple thermometer 10, 10 ′ and a heating wire 12 in a protective tube 11, with a gap filled with a filler 13. The thermocouple thermometers 10 and 10 ′ include a chromer-almer thermocouple, a platinum-platinum rhodium thermocouple, a nickel-silyl-nisyl-based thermocouple, a tungsten-rhenium thermocouple, or an iridium-rhodium-based thermocouple in accordance with JIS Z8704. It is desirable to use a metal protective tube made of a heat-resistant steel containing Cr as a main component, a corrosion-resistant steel containing Mo as a main component, or a protective tube made of platinum or a platinum-rhodium alloy.
[0007]
As the heating wire 12, the aforementioned thermocouple wire or resistance metal wire is used. Similarly to the thermocouple thermometer, the heating wire 12 is a metal protective tube made of a heat-resistant steel mainly composed of Cr or a corrosion-resistant steel mainly composed of Mo described in JIS Z8704, or platinum or platinum rhodium. It is desirable to use one installed in a protective tube made of an alloy.
[0008]
The filler 13 is a material having excellent thermal conductivity and good heat resistance at high temperatures, and is preferably a magnesium oxide powder.
[0009]
The protective tube 11 is made of a material that has heat resistance and does not react with the measurement sample and has a high thermal conductivity that does not affect the measurement accuracy. When measuring the thermal conductivity of glass, a platinum-rhodium alloy is one of the preferred materials.
[0010]
The distance dt between the temperature measurement positions of the thermocouple thermometers 10 and 10 'is set to be 50 times or less the wire diameter dc of a thermocouple (not shown).
[0011]
When the measurement sample 14 is a liquid, the outer diameter ds of the measurement sample 14 is the same as the inner diameter of the container 3 for storing the measurement sample. Even if the measurement sample 14 is a solid, the sample container 3 is used when the sample is softened at a temperature at which the thermal conductivity is measured and the shape is not maintained. When the sample is not softened, it is desirable to apply a heat-resistant metal oxide film or a metal film that does not oxidize, such as gold or platinum, on the entire surface of the measurement sample in order to eliminate measurement errors due to radiation.
[0012]
When the measurement sample 14 is a solid, a hole having substantially the same diameter as the outer diameter of the measurement probe tube 9 is made in the measurement sample 14, and the measurement probe tube is inserted into the hole. Further, the gap between the hole formed in the measurement sample and the inserted measurement probe tube 9 is filled with the powder of the measurement sample to reduce the measurement error.
[0013]
When the measurement sample 14 becomes a liquid at a high temperature, the measurement sample 14 is put in the measurement container 3, the temperature is raised, and the measurement probe tube 9 is inserted into the liquid measurement sample 14, and the temperature is lowered. It is better to carry out the measurement in a solid state at low temperature.
[0014]
When the sample container 3 is used, the sample container is covered with a lid 15 so that the influence of radiation on accuracy can be easily examined. As shown in FIG. 1, the lid 15 is preferably provided with an appropriate stopper 16 inside the sample container 3 and placed so as to be in contact with the measurement sample 14, but it may be simply placed on the sample container 3.
[0015]
The sample container 3 and the lid 15 do not react with the measurement sample, and are made of a material having durability to the measurement temperature. In the case of high-temperature molten glass, it is desirable that the sample container 3 be made of platinum.
[0016]
The measurement probe 5 and the sample container 3 shown in FIG. 1 are placed in an electric furnace 4 as shown in FIG. The temperature of the measurement sample 14 is maintained by the electric furnace 4 at a predetermined temperature at which the thermal conductivity is measured. The temperature of the measurement sample 14 is measured by the measurement probe 5.
[0017]
After the temperature of the measurement sample 14 reaches a predetermined temperature at which the thermal conductivity is measured, an electric current is supplied from the power supply 1 to the heating wire 12 through the heating wire 2 to generate heat per unit length and per unit time. Is heated so that is constant. Simultaneously with the start of heating, the heating wire temperature θ of the heating wire 12 is measured by the thermometer 10 installed on the measurement probe tube 9.
[0018]
The heat conductivity λ of the measurement sample 14 is calculated by the following equation (1) using the amount of heat q generated by flowing a current through the heating wire 12.
[0019]
λ = (q / 4π) / (Δθ / ln (t ₂ / t ₁ )) (1)
Here, a [Delta] [theta] = theta ₂ over theta _1. Further, θ ₁ is the heating line temperature at time t ₁ after the start of the measurement, θ ₂ is the heating line temperature at the measurement start time t ₂ , and t ₁ and t ₂ are the temperature rise of the heating line 12-logarithmic time diagram. Is the time within the area of the straight line portion where the gradient of is constant.
[0020]
In the thin wire heating method, the relationship between Δθ and ln (t ₂ / t ₁ ) is approximately as shown in FIG. 6, and from the part A where the slope of the temperature rise-logarithmic time diagram is described, the measurement sample is shown. Is determined by the equation (1). When the temperature of the glass is high, the temperature rise-logarithmic time curve deviates from a straight line and becomes gentle like a curved portion B after a certain measurement time has elapsed. In this part, convection occurs in the glass material, and the equation (1) cannot be applied.
[0021]
The heating line temperature θ is recorded in the data recording device 7 via the temperature measurement wiring 6, and the data processing device 8 performs an arithmetic process and the like according to the equation (1) together with the time t measured using a clock. The data recording device 7 is a temperature measuring device corresponding to the thermometer 10, and the measurement is performed electrically by voltage or current. Further, the measured temperature value is subjected to A / D conversion, and is taken into the data processing device 8. When a personal computer is used for the data processing device 8, it is preferable to automatically read the times t1 and t0 with a clock built in the personal computer in terms of accuracy.
[0022]
【Example】
The distance between the diameter dp of the probe tube for measurement and the distance dt between the temperature measurement positions was measured in Examples 1 to 4 adapted to the present invention and in Comparative Examples 1 to 3 which were not adapted to the present invention. went. The results are summarized in Table 1. Float glass was used as a measurement sample. In addition, a chromer-almer thermocouple wire was used as a heating wire, and a chromer-almer thermocouple was used as a thermocouple.
[0023]
[Table 1]

[0024]
FIG. 6 is a temperature rise-logarithmic time diagram measured in Example 1. The diagram 1 shows the case where the temperature of the measurement sample is 700 ° C., and the diagram 2 shows the case where the temperature of the measurement sample is 1000 ° C. The measurement results of the thermal conductivity are as shown in FIG. Similar results were obtained in other examples, and it was confirmed that accurate measurement was possible.
[0025]
【The invention's effect】
The thermal conductivity measuring device of the present invention can measure the thermal conductivity of a material at a high temperature, and can obtain valuable data for studying manufacturing conditions.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing the arrangement of a measurement probe and a sample container.
FIG. 2 is a diagram showing a cross section of a measurement probe of the present invention.
FIG. 3 is a view showing a cross section of FIG. 2A-A ′;
FIG. 4 is a diagram showing the results of an example of the present invention.
FIG. 5 is a schematic side view showing the entire thermal conductivity measuring device.
FIG. 6 is a graph showing a temperature change with time.
FIG. 7 is a graph showing the thermal conductivity with respect to the sample temperature measured in Example 1.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power supply 2 Heating wiring 3 Sample container 4 Electric furnace 5 Measurement probe 6 Temperature measurement wiring 7 Data recording device 8 Data processing device 9 Measurement probe tube 10 Thermocouple thermometer 11 Protection tube 12 Heating wire 13 Filler 14 Measurement Sample 15 Lid 16 Stopper

Claims (3)

A probe for measuring the thermal conductivity of glass in the temperature range from the liquid state melted at a high temperature to the solid state by the unsteady fine wire heating method, having both a heating element and a thermocouple for temperature measurement . The thermocouple for temperature measurement is connected in series, the distance measured by the thermocouple for temperature measurement is 50 times or less the wire diameter of the thermocouple, and the outer diameter of the probe for measurement is 1.5 mm or more. A probe for measuring the thermal conductivity of glass, which is set to 5 mm or less. The probe for measuring the thermal conductivity of glass according to claim 1, wherein the wire diameter of the thermocouple is 0.5 mm or more and 1 mm or less . The measurement of the thermal conductivity of glass according to claim 1 or 2, wherein the inside of the protection tube of the measurement probe is filled with magnesium oxide powder , and the protection tube is made of a platinum-rhodium alloy. For probes.

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