JP2005214858A - Method and apparatus for measuring principal axis thermophysical property value of two-dimensional anisotropic substance using heat flowmeter type multipoint temperature measurent method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure three constants of principal axis thermophysical property values (i.e., principal axis thermal conductivity, principal axis thermal diffusivity and specific heat) of a two-dimensional anisotropic substance, using a heat flowmeter type multipoint temperature measurement method. <P>SOLUTION: It is known that when the center of a sample to be measured is loaded with a certain amount of heat generated by a point-like heat source, the heat from the point-like heat source is propagated, while indicating a specific thermal propagation pattern reflecting the characteristics of the two-dimensional anisotropic substance and depending on its crystal structure. Consequently, a nine pieces of thermocouple assembly, composed of three sets/three pairs of thermocouples arranged at identical distances from the center point, is mounted on the surface of an anisotropic thermal conductive substance, and temperature changes are measured, thereby simultaneously and precisely separating/measuring the principal axis angle and the principal axis thermophysical property values, i.e., the principal axis thermal conductivity, principal axis thermal diffusivity and specific heat of the two-dimensional anisotropic substance, by carrying out one measurement operation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for measuring a principal axis thermal conductivity, a principal axis thermal diffusivity, and a principal axis angle, which are principal axis thermophysical properties of a two-dimensional anisotropic substance, and a measuring apparatus therefor.

  It is important to establish an efficient and highly accurate separation and measurement method for principal axis thermophysical properties (such as principal axis thermal conductivity and principal axis thermal diffusivity) of two-dimensional anisotropic materials.

  In other words, with the current technology, it is extremely difficult to perform separate measurement of the main spindle thermophysical property values (main axis thermal conductivity, main axis thermal diffusivity, etc.) of a two-dimensional anisotropic material with high accuracy.

  An object of the present invention is to provide a method and an apparatus for measuring an efficient and highly accurate principal axis thermophysical property (principal thermal conductivity, principal axis thermal diffusivity, etc.) of a two-dimensional anisotropic material.

  The gist of the present invention will be described with reference to the accompanying drawings.

  The surface of the object 1 to be measured is heated by the point heat source probe 2, and the unsteady temperature distribution of the multipoints in which the principal axis thermophysical value of the two-dimensional anisotropic heat conducting material is distributed in a specific shape, A main axis thermophysical property measurement method characterized by measuring with a temperature sensor 4 and measuring a main axis thermophysical property value (main axis thermal conductivity, main axis thermal diffusivity) of a two-dimensional anisotropic thermal conductive material with high accuracy. Is.

  Further, at least a large number of temperature measurement elements of the temperature sensor 4 (measurement temperature elements of a temperature sensor such as a thermocouple) are distributed on the surface of the object to be measured 1, and heat conduction is determined from temperature changes with respect to time at each measurement point. By constructing an approximate expression for the partial differential equation, which is a Taylor expansion of the heat conduction equation representing the phenomenon, and using the temperature change at each temperature measurement point placed on the surface, the thermal conductivity and thermal diffusivity in each measurement axis direction are calculated. 2. The spindle thermal property measurement method according to claim 1, wherein the spindle thermal conductivity, spindle thermal diffusivity, and spindle angle are calculated and measured using these results as experimental values. It is.

  Further, a thin wire-like thermal conductor 12a is wound with a thin resistance wire 12b at a constant interval, and a constant current is passed through the thin resistance wire 12b, and the generated Joule heat is stored in the thin rod-like heat conductor 12a. The point heat source probe 2 is configured to make point contact with the measured object 1 to be measured at a constant pressure, and the point heat source probe 2 is brought into contact with the measured object 1 at a constant pressure. The main axis thermophysical property value is measured by using a non-steady temperature change such as a temperature gradient reflecting a two-dimensional anisotropic material by flowing heat radially on the surface. This relates to the method for measuring the principal thermophysical property value described in the paragraph.

  In addition, two temperature measuring points are provided on the heating rod heater 12 serving as the point heat source probe 2, the temperature change is measured at any time, and the total heat quantity Q flowing into the measured object 1 is detected to detect the thermal conductivity of the sample. The thermophysical property value measurement method according to claim 3, wherein the thermophysical property value is measured with high accuracy.

  In order to measure the thermophysical properties, the temperature measurement elements of the point heat source probe 2 and the temperature sensor 4 are isolated by the holder 5 using the confidentiality of the surface of the object 1 to be measured. The thermophysical property value measuring method according to any one of claims 1 to 4, wherein the thermophysical property value is measured by evacuating the vacuum to eliminate heat loss due to convection or the like.

  Further, a point heat source probe 2 having a small area which is a point heat source for generating a certain amount of heat generated from the heating element 12b and heating the surface of the object 1 to be measured, and the point heat source probe 2 of the object 1 to be measured. A temperature sensor 4 such as a thermocouple for heating the surface and measuring the principal axis thermophysical value of the two-dimensional anisotropic heat conductive material as a multipoint unsteady temperature distribution distributed in a specific shape. The main axis thermophysical property measuring device is characterized in that the main axis thermophysical property value (main axis thermal conductivity, main axis thermal diffusivity) of the two-dimensional anisotropic thermal conductive material can be measured with high accuracy. Is.

  In addition, the temperature sensor 4 is configured to measure the temperature measurement element (measurement temperature element of the temperature sensor 4 such as a thermocouple) by distributing at least a number of points on the surface of the object 1 to be measured. The approximate equation for the partial differential equation, which is a Taylor expansion of the heat conduction equation representing the heat conduction phenomenon, is constructed from the temperature change with respect to the time, and the temperature change at each temperature measurement point placed on the surface is used to The thermal conductivity and thermal diffusivity are calculated as experimental values, and the spindle thermal conductivity, spindle thermal diffusivity, and spindle angle are calculated and measured using these results. This relates to the main spindle thermophysical property measuring device according to Item 6.

  Further, the point heat source probe 2 is wound around a thin rod-shaped heat conductor 12a with a resistance thin wire 12b at regular intervals, and Joule heat generated by applying a constant current to the resistance thin wire 12b is applied to the rod-shaped thin heat conductor. The thermal conductor 12a that stores the Joule heat is brought into contact with the object to be measured 1 whose thermal physical properties are to be measured and contacted at a constant pressure so that heat can flow radially on the surface of the object to be measured 1 Then, the point heat source probe 2 causes heat to flow radially to the surface of the measured object 1 to form a change in the unsteady temperature gradient reflecting the two-dimensional anisotropic material, and measure the thermophysical property value of the spindle. It is comprised, It concerns on the principal-axis thermophysical-value measuring apparatus of any one of Claim 6, 7 characterized by the above-mentioned.

  The heating rod-like heater 12 composed of the heat conductor 12a and the resistance thin wire 12b is provided with two temperature measurement points B and C, and the temperature of the temperature measurement points B and C is measured as needed, 9. The spindle thermophysical property measuring apparatus according to claim 8, wherein the total heat inflow amount Q flowing into the measuring object 1 is detected and the thermophysical property value is measured with high accuracy. .

  In order to measure the thermophysical value without processing the surface of the object 1 to be measured, in order to reduce the influence of the atmosphere measurement atmosphere of the point heat source probe 2 as much as possible, the point heat source probe 2, In addition, the temperature measurement element (measurement temperature element of temperature sensor 4 such as a thermocouple) is isolated on the surface with a holder 5 having good adhesion, and the portion is evacuated to a vacuum to eliminate heat loss due to convection, etc. 10. The spindle thermophysical property measuring apparatus according to claim 6, wherein the spindle thermophysical property measuring apparatus is measured.

  Since the present invention is as described above, it is possible to measure the spindle thermal property values (spindle thermal conductivity, spindle thermal diffusivity, etc.) of a two-dimensional anisotropic material with high accuracy and high accuracy.

  Embodiments of the present invention that are considered suitable (how to carry out the invention) will be briefly described with reference to the drawings, illustrating the operation of the present invention.

  In the measuring method according to the present invention, for example, a resistive element 12b such as a nichrome wire that is a heating element 12b is evenly wound around a metal body 12a that is a rod-like heat conductor 12a that has been processed into a small diameter, and a constant current is applied. Then, the point heat source 2 (point heat source probe 2) which is a heater 12 is brought into contact with the object 1 to be measured which is a two-dimensional anisotropic substance, and heat is uniformly diffused around one heating point of the sample surface. Therefore, since heat diffuses in a form that reflects the characteristics of the two-dimensional anisotropic material, by measuring the unsteady temperature distribution on the surface of the two-dimensional measurement sample that takes into account the anisotropic characteristics, Thus, the principal axis thermal conductivity and the principal axis thermal diffusivity of the two-dimensional anisotropic substance can be measured.

  That is, according to the present invention, a constant current is applied to the heater 12 by the thermocouple 4 set directly on the surface of the two-dimensional anisotropic solid, and the generated Joule heat is transferred from the point heat source probe 12 having a small area to the surface of the measurement sample. Heat is applied to the surface of the measurement sample and the situation in which heat diffuses. For example, the thermal conductivity and thermal diffusivity are measured by thermocouples 4 arranged at equal intervals in three directions. Using the geometrical relationship, the direction of the main axis angle from the thermal conductivity in three directions and the thermal diffusivity, and the two main axis thermal conductivity values and the two main axis thermal diffusivities, which are the respective main axis thermal properties It can be decided directly.

  Therefore, the present invention can measure an efficient and highly accurate principal axis thermophysical value (principal thermal conductivity, principal axis thermal diffusivity, etc.) of a two-dimensional anisotropic material.

  Further, as described above, the apparatus used in the present invention is the one in which the electric wire 12b is wound around the rod-shaped metal body 12a which becomes the heat conductor 12a having a constant shape, and Joule heat is generated when a constant current is passed. This rod-shaped metal body 12a becomes a point-like heat source 2 and forms a heat flow field in which heat flows on the surface of the measurement sample that is in point contact, and is equiangular at three positions away from the point heat source 2 at the same interval. Nine temperature measurement points are provided (for example, 30 degrees, 45 degrees, 60 degrees, etc.), unsteady temperature changes at these temperature measurement points are measured, and heat flows according to the heat conduction equation of the cylindrical seat system. Therefore, this equation is approximated by a difference, and the thermal conductivity and thermal diffusivity in three directions at equal intervals are measured. From these measured values, the principal axis direction is calculated, and finally, the principal axis thermal conductivity, The main axis thermal diffusivity and main axis angle are measured. There.

  The temperature measurement at each temperature measurement point set on the surface of the two-dimensional anisotropic material measures how the amount of heat applied by the point heat source 2 is absorbed and diffused by the sample.

  In this experiment, in order to prevent heat leakage loss of the two-dimensional anisotropic substance, the entire sample and the heater 12 heating part are covered with the holder 5 and controlled and held so that the temperature is always constant.

  In the measurement of the main shaft thermophysical properties, it is necessary to measure nine measurement temperature point temperatures on the solid surface by the point heat source 2 at a high resolution temperature of mK. The present apparatus sufficiently satisfies this requirement, and has a configuration including means for measuring and calculating the physical property values of the principal axis of the two-dimensional anisotropic heat conductive material.

  Specific embodiments of the present invention will be described with reference to the drawings.

  In this embodiment, the surface of the object to be measured 1 (sample 1) is heated by the point heat source probe 2, and the principal axis thermophysical property values of the two-dimensional anisotropic heat conductive material are distributed in a specific shape. Main axis thermal constant measurement that can be measured with temperature sensor 4 such as thermocouple as unsteady temperature distribution and can measure main axis thermophysical property (main axis thermal conductivity, main axis thermal diffusivity) of two-dimensional anisotropic heat conductive material with high accuracy It concerns the method.

  First, a measuring device used in the spindle thermal constant measuring method according to the present embodiment, that is, a two-dimensional thermophysical property measuring unit, a measuring device, and the entire measuring device will be described with reference to FIGS.

FIG. 1 shows a point heat source 2 of a principal axis thermal constant measuring device for a two-dimensional anisotropic material by the heat flow meter type multi-point temperature measuring method, and nine temperature measuring points (r ₁ , r ₂ , points 4 a to 4 i, shows the disposition of an attachment) to the position of r _3. Although the radius D of the sample 1 and the mounting position of the thermocouple 4 are indicated by an angle α and α = 45 degrees, three different axes on the same angle of α = 45 degrees, that is, 0 degrees and 45 degrees are shown. By measuring the temperature change at nine points on the measurement axis at 90 degrees, the measured thermal conductivity (the following formula (1)) and the measured thermal diffusivity (the following formula (5)) are obtained. Different spindle thermal conductivity (following formulas (2) and (3)), spindle thermal diffusivity (following formulas (6) and (7)), and spindle angle position φ _λ (following formula (4)) It shows what you can do.

  FIG. 2 shows details of the heater / sample holder section. A constant current is applied to the resistance thin wire 12b of the heater 12 to generate an inflow heat quantity Q, and the point heat source 2 is brought into contact with the sample 1 to apply heat. The inflow heat quantity Q is obtained by measuring the temperature at points B and C of the heat flow meter 3 and using the known heat conductivity of the heater, Q from the Fourier law. The surface portion of the sample 1 is evacuated by the evacuation system 6 in order to reduce heat loss due to convection, and the measurement accuracy of the main shaft thermophysical property value can be improved.

  FIG. 3 shows an overall schematic diagram of the measuring apparatus. The sample 1 which is a two-dimensional anisotropic material is placed on the sample setting table 10, and the entire sample is covered with the holder 5, and then the sample 1 is locally heated using the point heat source 2 and placed on the surface of the sample 1 9 The temperature change of the point thermocouple 4 is measured using the multi-thermometer 11, and these measurement data are stored in the computer 7. These measured temperature values are immediately analyzed by the computer 7 as the principal axis thermal conductivity, the principal axis thermal diffusivity, the specific heat, and the principal axis angle of the two-dimensional anisotropic heat conductive material, and displayed on the CRT 9.

  The spindle thermal constant measurement method according to the present embodiment is performed using the measurement apparatus.

  That is, Joule heat is generated in the heater part of the point heat source 2 at the center of the three sets × 3 pairs of thermocouples 4 installed on the surface of the measurement sample of the two-dimensional anisotropic object, and the heat of the point heat source 3 is contacted. When heat is applied, the heat diffuses and shows a temperature distribution that reflects the properties of the two-dimensional anisotropic material, and the change in temperature is measured to determine the principal axis thermal conductivity and the principal axis heat of the two-dimensional anisotropic material. Theoretically clarify that the diffusivity can be measured.

  The thermal conductivity in one direction by the three pairs of thermocouples 4 can be expressed by the equation (1) of the distance from the point heat source 2 of the thermocouple 4 and the measured temperature difference.

Here, Q: the amount of heat supplied from the point heat source, h ₁ : sample thickness of the two-dimensional anisotropic material, λ _i : measured thermal conductivity in the measurement axis direction, r ₁ , r ₂ : up to the temperature measurement position Represents the radius.

The thermal conductivity at 0 °, 45 °, and 90 ° experimentally obtained by the equation (1) represents the thermophysical value of two-dimensional anisotropy. λ _p1 is calculated by equation (2).

Here, λ _p1 : one main shaft thermal conductivity, λ ₁ , λ ₂ , λ ₃ : measured values of thermal diffusivity at 0 degrees, 45 degrees, and 90 degrees, respectively.

Similarly, λ _p2 is calculated by the following equation (3).

Here, λ _p2 represents the other principal axis thermal conductivity.

Further, the principal axis angle φ _λ of the two-dimensional anisotropic material is obtained by the equation (4).

Here, φ _λ is a principal axis angle determined experimentally by measured thermal conductivities λ ₁ , λ ₂ , and λ ₃ at angles of 0 degrees, 45 degrees, and 90 degrees.

  On the other hand, by measuring nine temperatures of 0 degree, 45 degrees, and 90 degrees in the unsteady state, the thermal diffusivity in each of these axial directions can be obtained using the following equation (5).

Here, Δr: distance between installed thermocouples represented by r ₂ -r ₁ or r ₃ -r ₂ , Δt: measured time interval of temperature, κ _i : measured value of measured thermal diffusivity in measurement axis direction Show.

From the measured values of the thermal diffusivity at 0 degrees, 45 degrees, and 90 degrees, one main shaft thermal diffusivity κ _p1 can be obtained using the following equation (6).

Here, κ _p1 : one main axis thermal diffusivity, κ ₁ , κ ₂ , κ ₃ : each measured value of thermal diffusivity at 0 degree, 45 degree, and 90 degree.

Similarly, the other principal axis thermal diffusivity κ _p2 can be obtained by the following equation (7).

Here, λ _p2 is the other principal axis thermal conductivity.

  Furthermore, the specific heat of the sample can be calculated from the principal axis thermal conductivity and the principal axis thermal diffusivity according to the following equation.

  Here, c is the specific heat and ρ is the sample density.

  In accordance with the principal axis thermal conductivity equations (2) and (3), the principal axis thermal diffusivity (6) and (7), and the principal axis angle calculation formula (4), the principal axis thermal conductivity of the two-dimensional anisotropic material Rate, principal axis thermal diffusivity, and principal axis angle.

  Therefore, in this embodiment, a constant current is applied to the heater 12 by the thermocouple 4 set directly on the surface of the two-dimensional anisotropic solid, and the generated Joule heat is transferred from the point heat source 2 having a small area to the surface of the measurement sample 1. Heat is applied to the surface of the measurement sample 1 and the state of heat diffusing, and the thermal conductivity and thermal diffusivity are measured by thermocouples 4 arranged at equal intervals in three directions. Using the geometrical relationship, the direction of the main axis angle from the thermal conductivity in three directions and the thermal diffusivity, and the two main axis thermal conductivity values and the two main axis thermal diffusivities, which are the respective main axis thermal properties Can be determined directly.

  In addition, this invention is not restricted to Example 1, The specific structure of each component can be designed suitably.

It is explanatory drawing which shows the detail of the arrangement | positioning condition of the measurement temperature point with respect to the point heat source heating point of a two-dimensional anisotropic substance. It is explanatory drawing which shows the outline | summary of the point heat source part and holder part in a two-dimensional anisotropic substance. It is explanatory drawing which shows the structure outline | summary of the principal-axis thermal conductivity of a two-dimensional anisotropic substance, a principal-axis thermal diffusivity, and a principal-axis angle measuring apparatus.

Explanation of symbols

1 Object to be measured 2 Point heat source probe 4 Temperature sensor 5 Holder
12 Heating rod heater
12a Thermal conductor
12b Resistance wire, heating element Q Total heat B Temperature measuring point C Temperature measuring point

Claims (10)

  A temperature sensor such as a thermocouple is used as a multipoint unsteady temperature distribution in which the surface of the object to be measured is heated with a point heat source probe and the principal axis thermophysical values of a two-dimensional anisotropic heat conducting material are distributed in a specific shape. And measuring the principal axis thermophysical property value (principal axis thermal conductivity, principal axis thermal diffusivity) of the two-dimensional anisotropic thermal conductive material with high accuracy.   The temperature measurement element of the temperature sensor (measurement temperature element of a temperature sensor such as a thermocouple) is distributed at least on the surface of the object to be measured, and the heat representing the heat conduction phenomenon from the temperature change with respect to time at each measurement point. Construct an approximate equation for the partial differential equation, which is a Taylor expansion of the conduction equation, and calculate the thermal conductivity and thermal diffusivity in the direction of each measurement axis as experimental values using the temperature change at each temperature measurement point placed on the surface. The main shaft thermophysical property measurement method according to claim 1, wherein the main shaft thermal conductivity, the main shaft thermal diffusivity, and the main shaft angle are calculated and measured using these results.   A thin wire-like heat conductor is wound with a thin resistance wire at regular intervals, a constant current is passed through the thin wire, the generated Joule heat is stored in the thin stick-shaped heat conductor, and the physical properties to be measured are to be measured. The point heat source probe is configured to make point contact with an object at a constant pressure, the point heat source probe is brought into contact with the object to be measured at a constant pressure, and heat is flowed radially on the surface of the object to be measured, so The spindle thermophysical property value measurement method according to any one of claims 1 and 2, wherein the spindle thermophysical property value is measured using an unsteady temperature change such as a temperature gradient reflecting an isotropic substance.   Two temperature measurement points are provided on the heating rod heater as the point heat source probe, the temperature change is measured at any time, the total amount of heat flowing into the object to be measured is detected, and the thermal properties such as the thermal conductivity of the sample are obtained. 4. The spindle thermophysical property measurement method according to claim 3, wherein the measurement is performed with high accuracy.   In order to measure thermophysical properties, using the confidentiality of the surface of the object to be measured, the point heat source probe and the temperature measuring element of the temperature sensor are isolated by a holder, and then the entire space is evacuated to a vacuum. 5. The method for measuring a spindle thermophysical property value according to any one of claims 1 to 4, wherein the thermophysical property value is measured by eliminating heat loss due to convection or the like.   A point heat source probe having a small area that is a point heat source for generating a certain amount of heat generated from the heating element and heating the surface of the object to be measured, and the surface of the object to be measured by the point heat source probe to be two-dimensional A temperature sensor such as the thermocouple for measuring the principal axis thermophysical property value of the anisotropic heat conductive material as a multipoint unsteady temperature distribution distributed in a specific shape, and a two-dimensional anisotropic heat A main spindle thermophysical property measuring apparatus configured to measure a main spindle thermophysical property value (main shaft thermal conductivity, main shaft thermal diffusivity) of a conductive material with high accuracy.   The temperature sensor is configured to measure the temperature measurement element (measurement temperature element of a temperature sensor such as a thermocouple) by distributing at least a plurality of points on the surface of the object to be measured, and the temperature change with respect to time of each measurement point From the above, the approximate equation for the partial differential equation, which is a Taylor expansion of the heat conduction equation representing the heat conduction phenomenon, is constructed, and using the temperature change at each temperature measurement point placed on the surface, the thermal conductivity in the direction of each measurement axis, and 7. The spindle according to claim 6, wherein the thermal diffusivity is calculated as an experimental value, and the spindle thermal conductivity, the spindle thermal diffusivity, and the spindle angle are calculated and measured using these results. Thermophysical property measuring device.   The point heat source probe is wound around a thin rod-shaped heat conductor at a constant interval, and Joule heat generated by applying a constant current to the resistance thin wire is stored in the thin rod-shaped heat conductor, and thermophysical properties are obtained. A heat conductor storing the Joule heat is brought into contact with the object to be measured at a constant pressure so that heat can flow radially to the surface of the object to be measured, and the point heat source probe is used to measure the object to be measured. 8. A structure in which a main body thermophysical property value is measured by causing a heat flow radially on the surface of the object to constitute a change in an unsteady temperature gradient reflecting a two-dimensional anisotropic material. The main-axis thermophysical property value measuring apparatus according to any one of the above.   The heating rod-shaped heater consisting of the heat conductor and the resistive thin wire is provided with two temperature measurement points, and the temperature at the temperature measurement points is measured at any time to detect the total heat inflow flowing into the object to be measured. 9. The spindle thermophysical property measuring apparatus according to claim 8, wherein the thermophysical property value is measured with high accuracy. In order to measure the thermophysical value without processing the surface of the object to be measured, in order to reduce the influence of the atmosphere measurement atmosphere of the point heat source probe as much as possible, the point heat source probe and the temperature measuring element ( The temperature element of the temperature sensor such as a thermocouple) is isolated on the surface with a holder with good adhesion, and the part is evacuated to a vacuum so that heat loss due to convection is eliminated and the thermophysical properties are measured. 10. The spindle thermophysical property value measuring apparatus according to any one of claims 6 to 9.

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