TWI250458B - Apparatus for measuring coefficient of thermal conductivity - Google Patents

Abstract

The present invention relates to an apparatus for measuring coefficient of thermal conductivity. The apparatus includes a heat-insulated housing which defining an inner space and a vacuum pump connected to the housing for vacuating the inner space. A heat source, two metal plates, a specimen and a cooling unit are accommodated in the space. The housing is made from aluminum oxide ceramic embedded with carbon nanotubes by a spark-plasma sintering process, wherein the carbon nanotubes are perpendicular to a direction of the heat transfer such that heat can be reflected back by the carbon nanotubes. Thus, heat insulation property of the apparatus is improved.

Description

1250458 V. INSTRUCTION DESCRIPTION OF THE INVENTION (1) Technical Field The present invention relates to a measuring device for thermal conductivity of a material, and more particularly to a thermal conductivity measuring device having a good heat insulating effect. [Prior Art] In the development of functional materials, it is often necessary to measure the thermal conductivity of the functional material, particularly for thermally conductive materials, such as thermal conductive adhesives, whose thermal conductivity affects the thermal conductivity of the final product. In the design process of the heat dissipation device of the electronic component, it is necessary to pre-calculate and simulate the thermal conductivity of the electronic component. Accurate measurement of the thermal conductivity of the thermal conductive material can reduce the number of tests and reduce the development cost, thus becoming the key to development and design. ϋ m Currently, there are two main methods for measuring the thermal conductivity of materials. The tenth method is laser scintillation method. This method uses two high-energy lasers as a heat source to quickly deposit a certain amount of heat on the surface of the sample. The temperature change of the other surface of the sample is measured, the thermal diffusivity of the sample is measured, and the thermal conductivity of the sample material is calculated by a formula. This method is expensive and costly, and the measurement error is large due to the density of the material. The second method is a temperature gradient method in which a sample to be tested is placed between a heat source and a low temperature heat sink, and a temperature gradient formed therebetween is measured to calculate a thermal conductivity of the material. The method is relatively simple, easy to operate, and easy to implement. Ideally, all of the heat from the heat source should pass through the sample to be tested to the low temperature heat sink, but in reality it is inevitable that some of the heat will be dissipated from other directions, resulting in measurement errors. Therefore, the measurement accuracy of the above method is mainly

1250458_ V. INSTRUCTIONS (2) Depending on the thermal insulation properties of the insulation layer used in the measuring equipment, the general insulation layer uses insulation materials such as alumina ceramics to isolate the heat source from the external environment and minimize heat loss. However, some of the heat will still be conducted outside through the oxidized ceramic. Please refer to the seventh figure, the mainland China patent published on September 20, 2000. No. 9 3 1 1 5 0 7 6. No. 0 discloses a method for measuring the thermal conductivity of a material and a device thereof. The device 9 includes a casing 13 filled with a heat insulating material to form a heat insulating cover 14; a heat source 15 having a power P; a heating plate 10 having an area S disposed close to the heat source 15; the material to be tested 1 2, the thickness of which is L, one surface is in close contact with the surface of the heating plate 10, and the other surface is in close contact with a heat receiving plate 11; the heating plate 10 and the heat receiving disk 1 1 are respectively provided with a temperature sensor 16 The temperature of the heating plate 10 and the heated disk 11 is sensed separately. 1 In order to improve the measurement accuracy, the radial dimension of the heating plate 10 and the heated disk 1 1 is much larger than the thickness L of the material 12 to be tested. When measuring the thermal conductivity of the material to be tested 12, it is only necessary to measure the temperatures T1 and T2 of the heating plate 10 and the heated disk 1 by the temperature sensor 16 respectively, and the thickness L of the material to be tested 12, the heating plate 10 area S, heat source 15 power P into the heat conduction equation:

P = kS (Tl - T2) / L can get the thermal conductivity k value. Wherein, the heat source 15 can be electrically heated, and the power p can be obtained by using p = I V , I is the current flowing through the heat source 15 , and V is the voltage of the heat source 15 . The method and device disclosed in the above patent are convenient to use and have low measurement cost. However, it has the following disadvantages: First, the device 9 is inevitable inside.

Page 6 1250458 V. Description of the invention (3) It is not possible to leave a material or a porous body. This is not a true measurement. The knowledge of the technology must not meet the requirements of a more abundant housing. Rv, heat insulation is necessary. [Contents] In order to overcome the air that can measure the thermal conductivity of the glue, the object is only brought into the high measurement of the existing thermal material. The shape of the disk is prevailing for the heat, which is good and affects the measurement, such as conducting gas, and the measuring device is as The accuracy of alumina is to be adiabatic to be first coated on the source 1 5 and the temperature is supplied with a measurable precision, especially for hot glue, sample and sample thickness for such sample ceramics, which is absolutely demanding; again, cover 1 4 and Insulation cover 1 4 internal sensor 1 6 measurement of gel-like or higher measurement When the test contains internal gas due to the inability of the thermal performance, it is necessary to heat the source 1 5 to prevent the installation of the porous thermal conductivity sample system has a large amount of weakness; There are still hot materials, temperature heat dissipation, maintenance samples, and the number of rubber-filled gas methods are accurate, and the materials are filled and sensed, and the internship knows technical or porous devices. The invention measures a heat-conducting heat source; the first system is disposed adjacent to the sample to be tested, and a first metal piece is formed; and the first and second metal blocks are cooled, and a sample and a cooling device are formed and the heat is formed The device is connected to the above-mentioned sample coefficient, the block is disposed, but the temperature of the device is internal and can be accommodated and can be disadvantageous. The object of the present invention is to provide a measuring device which is easy to operate and has excellent heat insulation, including: The heat is closely attached to the heat source; a sample to be tested; a second metal block, which is attached to the same; a plurality of temperature sensors for measuring; a heat insulating device is made of a heat insulating material, the heat source and the second metal Block, to be in the internal space; a vacuum system, its internal space is vacuumed;

1250458 V. INSTRUCTIONS (4) The pressure device can be applied to a predetermined medium-weighted thermal insulation material, which is electroformed and has a carbon nanotube system of 5 to 10%. Gas extraction inside the conventional technology, in addition to the accuracy and reliability of air or other gases; the ability to pass to the carbon nanotubes, so that the heat can only be accurate, and the nature is greatly improved. [Embodiment] Hereinafter, description will be made with reference to the drawings. Please first refer to the stereoscopic display of the first embodiment 100 and a pressure _ 2 0 0 which has an activity to put the article into or out of the outer wall 1 0 0 of the heater 100, one end and the vacuum of the vacuuming device. The pressure compresses the components housed in the inner space; it is arranged in an orderly arrangement of the carbon nanotubes in the spark-plasma sintering and arranged in the direction of vertical heat transfer, and the mass content is higher, and the present invention utilizes vacuuming. The system will measure the thickness of the sample and ensure the adverse effect of the measurement accuracy, thus improving the measurement and the non-thermal conductivity of the carbon nanotubes, so that the heat is reflected back and the thermal insulation of the measuring device is improved. The predetermined direction transfer can further improve the final measurement of the invention. The measuring device is easy to open: closed, which can be operated in a detailed manner. The thermal conductivity measuring device of the present invention is first intended. The measuring device 90 comprises an insulated container. The heat insulating container 100 is a square sealed container, and the upper cover 104 is opened or closed to be discharged. In addition, an air suction pipe 106 penetrates the heat insulating capacity such that one end thereof extends into the heat insulating container 100, and the other (not shown) is connected, and the heat insulating container can be evacuated.

1250458 V. INSTRUCTIONS (5) Please refer to the second figure. The insulated container 丨〇 has a double-layer structure, the inner layer is a heat-insulating insulation layer 11 〇, and the outer layer is a protective outer wall 丨〇 2 to prevent wear. The insulating layer 110 includes a heat insulating side wall 丨丨4 and a heat insulating bottom wall 丨丨6, together with the person. A square inner space having an open upper end is formed, and the shape of the heat insulating plate 丨丨 5 matches the shape of the opening and can be moved up and down. The pressure vessel 2 〇 is connected to the heat insulating plate 1 15 ' and a standard pressure can be applied to the heat insulating plate 1 15 . <1 Inside the heat insulating container 10, a cooling device 丨4 〇 is disposed at the bottom end of the inner space, that is, near the heat insulating bottom wall 116. A copper block 126, a test piece 2 130 and a copper block 1 2 4 are sequentially stacked on the cooling device 14 4 such that the sample U0 is between the two copper blocks i Μ; Wherein, the above two steel blocks, the soil 1 and the sample to be tested have the same cross-sectional area A, and the cross-sectional dimension is the thickness 1 of the sample to be tested 1 3 Η. A heat source 1 2 is disposed between the copper block 1 24 and the hot plate 115, and the aforementioned pressure device 2 〇〇 applies a standard pressure to the insulating plate 5 ′ to press the above-mentioned articles. The exhaust pipe 1 0 6 is disposed in the middle of an adiabatic side wall 丨丨4, preferably set to be measured by 1 q η ^ pumping & σ ° 1 3 0 south, which is beneficial to the gas of the sample to be tested 'In particular, when measuring a colloidal or porous sample, the gas is first removed and the thickness is determined. This ensures the accuracy of the measurement results and is reliable. 4 gentleman vacuum installation (not shown) through the suction pipe 1 0 6 The heat-insulating container 1 0 0 can eliminate the adverse effect of air on the measurement results, improve the measurement of copper to reduce the interface thermal resistance, the contact surface of the copper block 126 and the sample 130, and '1 24 The contact surfaces of sample 1 30 should be polished to make the contact surface smooth and smooth.

1250458 V. INSTRUCTION DESCRIPTION (6) The above-mentioned heat insulating side wall 1 14 , bottom wall 1 16 and insulating plate 1 15 are both made of a composite material formed of alumina ceramic 1 13 and carbon nanotube 1 1 2 , The composite material is made of alumina ceramics 1 1 3 and the carbon nanotubes 1 1 2 is a filler which is sintered by spark-plasma sintering. The carbon nanotubes 1 1 2 are arranged perpendicular to the heat transfer direction. In the present embodiment, the carbon nanotubes 1 1 2 are perpendicular to the adiabatic sidewalls 1 1 4 , the bottom wall 1 16 and the heat insulating plates 1 1 5 Arranged in the thickness direction, the mass content of the carbon nanotubes 1 1 2 is 5 to 10%. The carbon nanotubes 1 1 2 are tubular materials obtained by crimping carbon atoms of graphite layers, and generally have a diameter of several nanometers to several tens of nanometers, and may be arranged continuously or discontinuously. Nano carbon tube 1 1 2 has unique thermal conductivity, its axial thermal conductivity is excellent, but it is not thermally conductive in the radial direction. Therefore, when the heat is perpendicular to the carbon nanotubes 1 12, it will not transmit along its radial direction. The carbon nanotube i 1 2 reflects the heat back. Therefore, the insulated container 100 used in the present invention has excellent heat insulating performance, and has higher heat insulating effect than the conventional alumina ceramic, and ensures that the heat generated by the heat source 120 can only be along the copper block 1 2 4 to the sample 1 3 . The 0 direction is transmitted, and heat is prevented from being radiated to the outside of the heat insulating container 100 through the heat insulating side wall 11 4 during the transfer. Covering the outer wall of the outer wall of the insulating wall 1 1 4 protects against damage or wear of the insulating sidewall 1 14 by external force. Please refer to the third and fourth figures together. When the composite material is made into a square insulating sidewall 1 14 , a bottom wall 1 16 or a heat insulating plate 11 5 , the carbon nanotubes 1 1 2 may have Two ways of arrangement. The first type is arranged along the X-axis direction, i.e., the width direction of the heat insulating side wall 1 1 4, and the second type is arranged along the y-axis direction, that is, the longitudinal direction of the heat insulating side wall 1 1 4 . Thus, when heat is transferred in the z-axis direction, that is, the thickness direction of the adiabatic side wall 1 14 , the carbon nanotubes 1 1 2 are not thermally conductive,

Page 10 1250458 V. Description of the invention (7) The heat is reflected back to achieve the excellent effect of thermal insulation. Of course, since the heat insulating container 100 can also have other shapes, such as a commonly used cylindrical measuring device to measure a sample having a circular surface, in this case, the heat insulating container 100 is composed of a cylindrical insulating sidewall and a circular bottom. Wall and insulation board. Referring to FIG. 5, it is a schematic cross-sectional view of a cylindrical insulating sidewall 1 17 according to a second embodiment of the present invention, wherein the carbon nanotubes 1 19 are arranged along the axial direction of the cylinder, that is, perpendicular to the diameter of the cylinder. Direction. The cylindrical heat insulating wall 1 1 7 needs to be used together with a circular bottom wall (not shown) and a circular heat insulating plate (not shown), and can be made of the bottom wall 1 16 of the first embodiment and the heat insulating plate 1 1 5 . The size of the circle can be matched. When the heat is transferred from the inside to the outside of the cylinder, the heat of the carbon nanotubes is not reflected by the diameter of the carbon nanotubes, and the heat is reflected back to the k to achieve the excellent effect of heat insulation. Referring to FIG. 2 and FIG. 6 together, when the thermal conductivity measuring device 90 of the present invention is used, the cooling device 1 16 , the copper block 1 2 6 , the sample to be tested 1 30 , the copper block 1 2 4 and The heat source 120 is placed inside the insulated container 100 and tightly closed. The cooling device 161 may include a cooling water pipe or the like, and the heat source 120 may be electrically heated, so that a temperature gradient field is formed between the heat source 120 and the cooling device 1 16 . Applying a standard pressure to the heat insulating plate 1 15 by the pressure device 2000, the pressure applied by the pressure device 2000 is generally in the range of 2 0~2 5 1 b ί, and is pumped by a vacuuming device (not shown). The air tube 1 0 6 evacuates the adiabatic container 100 to start measuring. On the side of the copper block 1 2 4 - a temperature sensing point D 1 , D 2 , D 3 is respectively disposed from the upper surface a 1 , a 2 , a 3 of the sample 1 3 0, and the temperature sensing device is used.

1250458 ____ V. Description of the invention (8) (not shown) The temperature ΤΙ, T2, T3 of the three-point position can be measured, and the temperature sensing device includes a thermocouple. Similarly, on the side of the copper block 1 2 6 , a temperature sensing point Μ 1, M2, M3 is respectively disposed at a distance from the lower surface s 1 , s 2 , s 3 of the sample 1 3 0, and the temperature sensing device can measure the distance. The temperature of three points Τ4, Τ5, Τ6 〇 according to the Fourier formula:

Q^-kA ΔΤ/ AD where A is the surface area of sample 1 3 0, and Δ D is the distance that heat flows through sample 1 3 0, that is, the thickness of sample 130. To measure the thermal conductivity K value of sample 130, a table is required to determine the heat flux Q value through sample 130 and the difference in temperature between the upper and lower surfaces: ΔΤ-Tlow-Tup 1 ie upper surface temperature Tup and lower surface temperature T low Difference. Since the heat insulating side wall 1 1 4 of the heat insulating container 100 and the heat insulating plate 5 cannot transfer heat, heat can only be transferred from the heat source 12 to the cooling device 6 and no heat is dissipated. Thus, the heat flux Q32 from turbulence, the heat flux Q21 flowing from D2 to D1, the heat flux q flowing through the sample, the heat flux Q12 flowing from M2, and the heat flowing from Μ2 to (10) The flux Q23 is equal, so only need to find any heat flux to know the heat flux of the sample 13〇. The thermal conductivity u of the copper blocks 124, 126 is a known value, and the heat flux value q flowing through the copper blocks 124, 136 can be obtained according to the Fourier formula. - According to the temperature of each point of the copper block 1 24, the sixth figure: the temperature of the D 3 D 2 D1 point T1, T 2, T 3 can be obtained on the sample 1 3 0, the face Tup is the same as ' The temperature of the three points M1, M2, M3 from the copper block 1 26

Page 12 1250458 V. INSTRUCTIONS (9) The lower surface temperature Tlow of the sample can be obtained from T4, T5 and T6. By substituting the above heat flux and temperature T u p and T 1 〇 w into the formula, the thermal conductivity of the sample 130 can be obtained. It should be understood by those skilled in the art that the present invention utilizes the radial non-thermal conductivity of the carbon nanotubes 112, so that the thermal insulation performance of the heat insulating container 1 is greatly improved, so that heat can only be transmitted to a predetermined direction; and the exhaust pipe 1 0 6 And the vacuuming device can vacuum the insulated container 100 to eliminate the influence of air, which can further improve the final measurement accuracy; and the heat source 120 is not limited to electric heating, and other methods capable of providing sufficient heat can be applied. The cooling device 140 is not limited to the cooling water pipe, and other cooling methods such as liquid nitrogen can also be applied to the present invention. The copper blocks 1 2 4 and 1 2 6 can also be replaced by other metals, and the purpose thereof is only based on the material having the known thermal conductivity. The surface temperature Tup and T 1 〇w 〇 of the heat pass and the sample 130 are measured; in summary, the invention has indeed met the requirements of the invention patent, and the patent application is filed according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the present invention are intended to be included within the scope of the following claims. Φ

Page 13 1250458_ BRIEF DESCRIPTION OF THE DRAWINGS The first figure is a perspective view of a thermal conductivity measuring device of the present invention. The second figure is an internal schematic view of the thermal conductivity measuring device of the present invention for removing the upper cover. The third figure is a schematic view of a square insulating sidewall of the thermal conductivity measuring device of the present invention. The fourth figure is a schematic view of a square insulating sidewall of the thermal conductivity measuring device of the present invention. The fifth drawing is a schematic view of the cylindrical adiabatic side wall of the thermal conductivity measuring device of the present invention. The sixth figure is a graph showing the relationship between temperature and distance of copper metal measured by a thermocouple. The seventh figure is a schematic diagram of a conventional thermal conductivity measuring device. [Main component symbol description] 1 Measuring device 90 Insulation container 100 Outer wall 102 Upper cover 104 Exhaust pipe 106 Insulation layer 110 Carbon nanotubes 112, 119 Alumina ceramic 113 Absolutely wide, side wall 114, 117 End plate 115 bottom wall 116 敎源120 copper block 124, 126 sample 130 cooling device 140 pressure 200

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Claims (1)

1250458 VI. Patent Application Range 1. A device for measuring thermal conductivity, comprising: a heat source capable of generating heat; a first metal block attached to the heat source; and a sample to be tested, the system being closely attached thereto a metal block disposed; a second metal block disposed against the sample to be tested; a cooling device attached to the second metal block; and a heat insulating device formed of a heat insulating material to form an internal space The heat source, the first metal block, the sample to be tested, the second metal block and the cooling device can be accommodated in the internal space; and a vacuuming system can evacuate the internal space formed by the heat insulating device. 2. The apparatus for measuring the number of heat conduction systems according to claim 1, wherein the heat insulating material contains carbon nanotubes, and the carbon nanotubes are arranged perpendicular to the direction of heat transfer. 3. The apparatus for measuring thermal conductivity as described in claim 2, wherein the insulating material is an alumina ceramic system as a matrix material, and the carbon nanotubes are arranged in an ordered arrangement and dispersed in the matrix material. 4. The apparatus for measuring thermal conductivity as described in claim 3, wherein the adiabatic household material is formed by plasma-sealing alumina ceramics and carbon nanotubes. 5. The apparatus for measuring thermal conductivity as described in claim 4, wherein the mass of the carbon nanotubes is 5 to 10%. 6. The apparatus for measuring thermal conductivity as recited in claim 1, wherein the heat source is electrically heated. P. </ RTI> </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; 8. The apparatus for measuring thermal conductivity as set forth in claim 1, wherein the second metal block comprises copper. 9. The apparatus for measuring thermal conductivity according to claim 1, wherein the first metal block, the second metal block, and the sample to be tested have the same cross-sectional area. A device for measuring thermal conductivity as recited in claim 1, wherein the device further comprises a plurality of temperature sensors for measuring the shore of the metal block. 11. The apparatus for measuring thermal conductivity as set forth in claim 1, wherein the apparatus further comprises a movable adiabatic seven and a pressure vessel that applies a predetermined pressure to the insulating panel. 1 2. The apparatus for measuring thermal conductivity according to claim 1, wherein the evacuation system comprises an exhaust pipe and an air suction device, the exhaust pipe system extending to an inner space of the heat insulating device. 1 3. A device for measuring thermal conductivity, comprising: an adiabatic device, which is formed by enclosing a plurality of insulating thermal insulation walls, a bottom wall and a movable dance hot plate to form a closed space; a heat source, a metal block, the sample to be tested and the cooling device are housed in the space; a pressure device that applies a predetermined pressure to the top wall; and a vacuum system connected to the heat insulating device, which can close the space of the heat insulating device Vacuuming Page 16 1250458_ VI. Patent application scope, wherein the heat insulating wall, the bottom wall and the heat insulating plate are formed by sequentially arranging a plurality of carbon nanotubes in an oxidized Ming Tauman matrix material and forming the carbon nanotubes It is perpendicular to the direction of heat transfer. 1 . The device for measuring thermal conductivity according to claim 13 , wherein the heat source is disposed adjacent to the heat insulation plate, and the sample to be tested is sandwiched between the two metal blocks, and the cooling device is attached. Set by the bottom wall. 1 5. The apparatus for measuring thermal conductivity as described in claim 14, wherein the two metal is made of copper metal. 1 6. The device for measuring the thermal conductivity as described in claim 14 is further provided with a temperature sensing device for sensing the temperature rv of the metal block. 1 7 . The device for measuring heat conduction and number described in claim 13 of the patent application, wherein the pressure applied by the pressure device is in the range of 20 to 251 bf. 1 8. The apparatus for measuring thermal conductivity as recited in claim 13 wherein the heat source is electrically heated to provide heat. 1 9. The device for measuring thermal conductivity according to claim 13 of the patent application, wherein the carbon nanotube has a mass content of 5 to 10%. Page 17