Dynamic measuring device and measuring method for heat conductivity coefficient under high-temperature condition

Abstract

The invention provides a dynamic measurement device and a dynamic measurement method for a heat conductivity coefficient under a high-temperature condition. The dynamic measurement device for the heat conductivity coefficient under the high-temperature condition comprises a furnace body; the heat preservation layer is located in the furnace body; the sample sleeve assembly is used for installing the sample disc and forming a uniform temperature surface, and the sample sleeve assembly comprises a heat protection plate which is used for being installed at one axial end of the sample disc; the heating assemblies comprise heating units located in the heat preservation layer, the heating units are arranged at the two ends of the sample sleeve assembly, the heat protection plate is located between the sample disc and one heating unit, the two heating assemblies are independently controlled, and the power is adjustable; and the temperature measuring probes are located at the two ends of the furnace body, and the heat preservation layer and the heating assembly are provided with light path channels avoiding the detection paths of the temperature measuring probes. In this way, the heating assemblies at the two ends of the sample sleeve assembly can provide enough heating power, and a uniform temperature field can be formed easily. And the heat protection plate at only one end is convenient for carrying out temperature rise control on a single shaft end.

Description

Technical Field

[0001] The present application relates to the field of thermal conductivity measurement, and in particular to a dynamic measurement device and method for thermal conductivity under high temperature conditions. Background Art

[0002] Thermal conductivity is a key thermophysical property of materials. It is a basic and important design input parameter for material selection, heat transfer design, temperature field analysis and calculation, etc.

[0003] High temperature resistant materials are increasingly used in many cutting-edge fields such as nuclear energy utilization, aerospace, and metallurgy. Cutting-edge space rockets and space shuttles must use such materials when re-entering the atmosphere to isolate ultra-high temperature gases and avoid the disintegration of the cabin shell. The Columbia Space Shuttle of the United States disintegrated because the surface insulation tiles fell off and failed when re-entering the atmosphere. These application fields often require the selection of high temperature resistant materials, thermal insulation materials, etc., and heat transfer design. The thermal conductivity of high temperature resistant thermal insulation materials is an important basic data for these works, so it has become an urgent technical need to conveniently and accurately measure the thermal conductivity of materials at high temperatures.

[0004] Generally speaking, the thermal conductivity of a material is a function that changes with temperature, rather than a constant, so it is usually necessary to measure the thermal conductivity of the material at different temperatures. The measurement method known to the inventor is generally a static measurement method based on the steady-state thermal conductivity law, that is, the material to be measured is processed into a workpiece with a certain regular shape, heated on one side and cooled on the other end, and after the temperature stabilizes, the thermal conductivity of the material is calculated by power, temperature difference and workpiece size. There are also dynamic thermal conductivity measurement methods, such as using laser pulses to heat a part of the material in a short period of time, and then observing the change of the temperature field over time, and then inferring the thermal diffusion coefficient and thermal conductivity of the material.

[0005] The static method for measuring thermal conductivity known to the inventors often has low measurement accuracy under high temperature conditions, because when using the static method to measure thermal conductivity, it is inevitable to measure the heat power conducted by the material being measured. However, due to the heat dissipation problem, it is impossible to ensure that all heating power passes through the material being measured, and the heat dissipated at the boundary of heat conduction cannot be accurately measured. Moreover, the heat transfer path is often not entirely along the direction of heat flux density, so the measurement accuracy of the static method is relatively low. In addition, the static method is also difficult to apply to high-temperature fields, because under high temperature conditions, in order to prevent the material from being oxidized, the test needs to be carried out under closed conditions of vacuum or inert gas protection, and it is difficult to create heat dissipation conditions at the cold end of the material being measured. Under high temperature conditions above 1200°C, the heat dissipation loss of the static method is large, resulting in inaccurate measurement of the measured thermal power and reduced measurement accuracy.

[0006] The inventors are aware of a technology for measuring thermal conductivity using a dynamic method of laser heating. Since thermal insulation materials are all in the form of porous media with low thermal diffusion coefficients, the heat generated by the laser pulse cannot be completely absorbed at the surface, and thus cannot form effective pulse heat diffusion inside the thermal insulation material. Therefore, it is generally not used for testing thermal insulation materials.

[0007] In addition, as a thermal conductivity meter for measuring thermal conductivity. The more common thermal conductivity meter is the hot wire method thermal conductivity meter. The hot wire method thermal conductivity meter calculates the thermal conductivity by burying a hot wire in the sample, passing a constant current to make it heat up, and measuring the hot wire temperature and related parameters. It is suitable for a variety of materials, especially for anisotropic materials and low thermal conductivity materials. A constant current heat source is often set in the thermal conductivity meter. For example, the Chinese invention patent with publication number "CN107589148A" discloses "a controllable atmosphere non-steady-state hot wire method thermal conductivity tester". The tester includes a test furnace in a closed state, a furnace chamber surrounded by a refractory lining is provided in the furnace cavity, and the test furnace is installed on a furnace frame. The tester also includes a control cabinet, a computer connected to the control cabinet, a lifting mechanism and a furnace door platform. A pressure sensor, a safety pressure regulating valve, and a temperature control thermocouple are provided on the furnace cover. The hot wire unit provided on the furnace door includes a heating lead, a pressure measuring lead, and a differential thermocouple. The heating lead of the hot wire unit in the tester is arranged on one side, and the hot wire unit forms a heat source on one side. And the hot wire unit generates heat at constant power. There are inherent deficiencies in heating efficiency and heating uniformity by only using a constant power heat source on one side. The hot wire heater itself also has to be used as a central temperature measuring thermocouple, and most of them are made of materials such as copper-constantan and platinum-platinum-rhodium. Their melting points limit their high-temperature applications, and their materials are prone to chemical reactions with insulation materials at high temperatures and become ineffective. Summary of the invention

[0008] In view of the above-mentioned state of the prior art, this application is made. In a first aspect, this application provides a dynamic measurement device for thermal conductivity under high temperature conditions.

[0009] A dynamic measurement device according to one embodiment of the present application includes: a furnace body; a thermal insulation layer, wherein the thermal insulation layer is located in the furnace body; a sample sleeve assembly, used to install a sample disk, wherein the sample sleeve assembly includes a heat protection plate, wherein the heat protection plate is used to be installed on one axial end of the sample disk; a heating assembly, wherein the heating assembly includes a heating unit located in the thermal insulation layer, wherein the heating units are provided at both ends of the sample sleeve assembly, the heat protection plate is located between the sample disk and one of the heating units, and the two heating assemblies are independently controlled and have adjustable power; a temperature measuring probe, wherein the temperature measuring probe is located at both ends of the furnace body, and the thermal insulation layer and the heating assembly have an optical path channel that avoids the detection path of the temperature measuring probe.

[0010] As a further improvement of the present application, the sample sleeve assembly includes a sleeve for wrapping the sample disk and the heat shield plate.

[0011] As a further improvement of the present application, the sample sleeve assembly includes graphite paper for clamping between the sample disc and the heat shield.

[0012] As a further improvement of the present application, the sample sleeve assembly also includes emissivity tubes for being arranged at both ends of the sample disk, the facing surfaces of the two emissivity tubes are in a closed state, and the facing back surfaces of the two emissivity tubes are in an open state, and the emissivity tubes pass through the sleeve and the heat shield.

[0013] As a further improvement of the present application, the material of the thermal insulation layer includes carbon fiber felt, and the material of the sleeve includes graphite; the furnace body is evacuated or filled with an inert gas.

[0014] As a further improvement of the present application, the sample disk, the heat protection plate, the graphite paper, and the emissivity tube are coaxially arranged; the furnace body, the thermal insulation layer, the heating unit, the sample sleeve assembly, and the temperature measuring probe are coaxially arranged; the furnace body includes furnace body units that are opened and butted against each other, and the thermal insulation layer includes thermal insulation layer units that are opened and butted against each other.

[0015] As a further improvement of the present application, the temperature measuring probe is a non-contact infrared temperature measuring probe, the non-contact infrared temperature measuring probe is located outside the furnace body, and the non-contact infrared temperature measuring probe is connected to the furnace body through a spyglass.

[0016] As a further improvement of the present application, the heating unit is an electric heater, which is in the shape of a round pancake and includes a winding heating wire; graphite electrodes are connected to both ends of the heating wire, and water-cooled copper electrodes are connected to the opposite ends of the two graphite electrodes, and the water-cooled copper electrodes pass through the inner and outer walls of the furnace body.

[0017] As a further improvement of the present application, the mutually open butt joints of the furnace body units are provided with flange rings; the mutually open butt joints of the insulation layer units are provided with mutually matching annular concave-convex structures; the insulation layer units include mutually open butt joint accommodating cavities, the sample sleeve assembly and the heating unit are located in the accommodating cavity, the bottom surface of the accommodating cavity is connected to a through channel, the inner diameter of the through channel is smaller than the inner diameter of the accommodating cavity, and the optical path channel includes the through channel.

[0018] In the second aspect, a method for dynamic measurement of thermal conductivity under high temperature conditions is provided. Using the dynamic measurement device for thermal conductivity under high temperature conditions as described in any of the above items, the method for dynamic measurement of thermal conductivity under high temperature conditions includes: step S1: using the heating components arranged at both ends of the sample sleeve assembly to raise the temperature of the sample disk and the heat shield as a whole; step S2: when the insulation layer is heated to a specified uniform temperature, the heating component at one end adjacent to the heat shield maintains the power unchanged, and the heating component at the other end increases the power and continues to heat up; step S3: using the temperature measuring probe to non-contactly measure the sample disk as the material to be measured, measure the dynamic temperature rise curve at the center points of both ends of the sample disk, and obtain the thermal diffusion coefficient and thermal conductivity of the material to be measured.

[0019] The beneficial effects of the dynamic measurement device of thermal conductivity under high temperature conditions of the present application include: providing a test device that can accurately and quickly measure the thermal conductivity of materials under high temperature conditions. First, compared with a single heat source, heating components are provided at both ends of the sample sleeve assembly, which can provide sufficient heating power and enable the insulation material to produce a significant temperature rise curve in a short time. Secondly, the two heating components are arranged at both ends, which is convenient for heating the two ends of the sample sleeve assembly to a uniform temperature field with the same temperature. Thirdly, the power of the two heating components is adjustable, and each can be controlled independently. It is convenient for the two heating components to be in different working conditions, and different temperature field conditions are provided for the two ends of the sample sleeve assembly, which is then convenient for observing dynamic temperature changes. The sample sleeve assembly can allow the radiant heat from the heating component to form a uniform surface heat source and transfer it to the surface of the material being tested, and the sample sleeve assembly can increase the boundary temperature of the side of the material being tested, significantly prevent the heat loss of the material being tested along the radial side, improve the uniformity of the temperature field in the central area of ​​the material being tested, and reduce the measurement error. Secondly, only one end of the sample disk is attached with a heat shield, which only provides insulation for one axial end of the sample disk, and is used to slow down the heat loss along the axial direction during dynamic heating. Finally, the insulation layer and the furnace body play a multi-layer insulation effect, which facilitates the formation of a stable and uniform high-temperature temperature field inside the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 is an axial view of an embodiment of a dynamic measurement device for thermal conductivity under high temperature conditions of the present application;

[0022] Figure 2 yes Figure 1AA section view;

[0023] Figure 3 yes Figure 1 BB cross-sectional view;

[0024] Figure 4 is a three-dimensional diagram of an embodiment of a dynamic measurement device for thermal conductivity under high temperature conditions of the present application;

[0025] Figure 5 is an exploded view of an embodiment of a dynamic measurement device for thermal conductivity under high temperature conditions of the present application;

[0026] Figure 6 is a three-dimensional diagram of a heating assembly of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions of the present application;

[0027] Figure 7 It is an exploded view of a sample sleeve assembly of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions of the present application;

[0028] Figure 8 It is an axial view of a sample sleeve assembly of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions of the present application;

[0029] Fig. 9 yes Figure 8 CC cross-sectional view.

[0030] Description of Reference Numerals

[0031] 1- non-contact infrared temperature probe; 2- peephole; 3- furnace body; 31- flange seat; 32- upper through pipe; 33- lower through pipe; 34- support foot; 35- compartment; 36- flange ring; 4- insulation layer; 41- accommodating cavity; 42- through passage; 43- annular concave-convex structure; 5- heating assembly; 51- electric heater; 511- center hole; 52- graphite electrode; 53- water-cooled copper electrode; 531- radial flange; 6- sample sleeve assembly; 61- first sleeve; 62- second sleeve; 63- sample disk; 64- heat protection plate; 65- graphite paper; 66- first emissivity tube; 67- second emissivity tube; 6a- groove. DETAILED DESCRIPTION

[0032] The exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0033] The following is a further detailed description of the dynamic measurement device for thermal conductivity under high temperature conditions and the dynamic measurement method for thermal conductivity under high temperature conditions of the present application in conjunction with specific embodiments.

[0034] See also Figures 1 to 9 , the embodiment of the present application provides a dynamic measurement device for thermal conductivity under high temperature conditions. Figure 5 As shown, the dynamic measurement device includes a furnace body 3, a heat-insulating layer 4, a sample sleeve assembly 6, a heating assembly 5, and a temperature measuring probe. The heat-insulating layer 4 is located inside the furnace body 3. Figure 7 , Fig. 9 As shown, the sample sleeve assembly 6 is used to install the sample pan 63 and form a uniform temperature surface. A heat shield 64 is also provided at one end of the sample pan 63. The heating assembly 5 includes a heating unit located in the thermal insulation layer 4. A heating assembly 5 is provided at each end of the sample sleeve assembly 6. The heating assembly 5 and the sample sleeve assembly 6 are spaced apart. The heat shield 64 is located between the sample pan 63 and one of the heating assemblies 5. The two heating assemblies 5 are independently controlled and have adjustable power. The heating assembly 5 heats the sample sleeve assembly 6 in the entire thermal insulation layer 4. The temperature probe is located at both ends of the furnace body 3. The furnace body 3, the thermal insulation layer 4, and the heating assembly 5 have an optical path channel that avoids the detection path of the temperature probe, that is, the temperature probe can directly point to the sample sleeve assembly 6.

[0035] The heat shield 64 is used for unilateral heat preservation in the axial direction. The heat shield 64 is only provided at one end of the sample disk 63. The heat shield 64 may be in contact with the sample disk 63. This is because during dynamic measurement, the heating assembly 5 is heated only at the end without the heat shield 64, and the power of the heating assembly 5 at the end with the heat shield 64 remains unchanged. The heat shield 64 is used to slow down the heat loss along the axial direction during dynamic heating. The heat shield 64 is a component to prevent the heat from being lost too quickly.

[0036] In a non-limiting example, the thermal conductivity of the heat shield 64 is similar to or the same as the thermal conductivity of the sample disk 63 as the object to be measured.

[0037] like Figure 7 , Fig. 9 As shown, in one embodiment, the sample sleeve assembly 6 includes a sleeve for wrapping the sample disc 63 and the heat shield 64. The sleeve includes a first sleeve 61 and a second sleeve 62 that are opened and docked with each other, and the sample disc 63 and the heat shield 64 are respectively located in the first sleeve 61 and the second sleeve 62. The first sleeve 61 and the second sleeve 62 are similar to cover-shaped parts, and the inner diameters of the first sleeve 61 and the second sleeve 62 can be equal, and the outer diameters of the first sleeve 61 and the second sleeve 62 can be equal.

[0038] The beneficial effects of the above embodiment are as follows: the sleeve can quickly form a uniform surface heat source from the radiant heat source of the heating assembly 5, conduct heat to the sample disc 63 and the heat shield 64, and ensure that the temperature of the sample disc 63 and the heat shield 64 is uniform within a certain period. In addition, the temperature-uniform sleeve can increase the boundary temperature of the side of the material being tested, and enhance the radial temperature uniformity of the central area of ​​the material being tested.

[0039] In a non-limiting example, the insulation layer 4 can be fixed to the inner wall of the furnace body 3, the thickness of the insulation layer 4 can be greater than the wall thickness of the furnace body 3, and the material of the insulation layer 4 includes carbon fiber felt. The material of the sleeve is selected from a material with high thermal conductivity, such as graphite. The furnace body 3 is evacuated or filled with an inert gas.

[0040] like Figure 7 , Fig. 9 As shown, in one embodiment, graphite paper 65 is sandwiched between the sample disk 63 and the heat shield 64. The sample sleeve assembly 6 also includes emissivity tubes located at both ends of the sample disk 63, and the emissivity tubes include a first emissivity tube 66 and a second emissivity tube 67. Fig. 9 As shown, the facing surfaces of the first emissivity tube 66 and the second emissivity tube 67 are blocked, and the facing surfaces of the first emissivity tube 66 and the second emissivity tube 67 are open. The axial length of the second emissivity tube 67 may be about three times the axial length of the first emissivity tube 66.

[0041] The beneficial effects of the above embodiment are as follows: the heat shield 64 can be made of porous media, and the graphite paper 65 is used to reduce the contact thermal resistance of the porous media, and also to provide a standard surface emissivity for infrared measurement. The first emissivity tube 66 and the second emissivity tube 67 both have one end blocked, which is used to set a standardized surface emissivity to improve the repeatability of infrared temperature measurement. The emissivity tube is used to form a standard emissivity surface, which is convenient for standardizing the temperature measured by infrared means.

[0042] like Fig. 9 As shown, in one embodiment, the first emissivity tube 66 passes through the first sleeve 61, and one end of the first emissivity tube 6 abuts against the sample disk 63. The second emissivity tube 67 passes through the second sleeve 62 and the heat shield 64. One end of the second emissivity tube 67 abuts against the graphite paper 65.

[0043] The beneficial effect of adopting the above embodiment is that the through design of the first emissivity tube 66 and the second emissivity tube 67 is just to form a standard emissivity surface.

[0044] In one embodiment, the first sleeve 61, the second sleeve 62, the sample disk 63, the heat shield 64, the graphite paper 65, the first emissivity tube 66, and the second emissivity tube 67 are all coaxially arranged. Figure 7As shown, the edges of the first sleeve 61, the second sleeve 62, the sample disk 63, the heat shield 64, the graphite paper 65, the first emissivity tube 66, and the second emissivity tube 67 are all circular.

[0045] The outer diameters of the sample disk 63, the heat shield 64, and the graphite paper 65 may be equal, and the inner diameters of the first sleeve 61 and the second sleeve 62 may be equal to the outer diameters of the sample disk 63, the heat shield 64, and the graphite paper 65. The thickness of the graphite paper 65 is much smaller than that of the sample disk 63 and the heat shield 64.

[0046] like Figure 5 As shown, in one embodiment, the furnace body 3 includes furnace body units that are opened and butted against each other, the insulation layer 4 includes insulation layer units that are opened and butted against each other, and the furnace body 3, the insulation layer 4, the heating unit, the sample sleeve assembly 6, and the temperature measuring probe are all coaxially arranged. The two temperature measuring probes are arranged facing each other.

[0047] The beneficial effect of adopting the above embodiment is that it is convenient for the temperature measuring probe to be accurately aligned with the center of the two axial ends of the sample sleeve assembly 6 .

[0048] In one embodiment, the temperature measuring probe is a non-contact infrared temperature measuring probe 1, and the non-contact infrared temperature measuring probe 1 is connected to the furnace body 3 through a viewing mirror 2. The non-contact infrared temperature measuring probe 1 and the viewing mirror 2 are both located outside the furnace body 3.

[0049] The beneficial effect of the above embodiment is that the chemical reaction at high temperature caused by direct contact between the non-contact infrared temperature measuring probe 1 and the insulation layer 4 is avoided. The sight glass 2 plays the role of sealing the furnace body 3 locally, and also plays the role of light transmission, so that the infrared light passes through the sight glass 2, so that the optical path between the non-contact infrared temperature measuring probe 1 and the surface of the material to be measured is unobstructed.

[0050] like Figure 6 As shown, in one embodiment, the heating component 5 includes an electric heater 51, which is in the shape of a round pancake and is composed of a winding heating wire. Electrodes are connected to both ends of the electric heater 51, and the electrodes may include a graphite electrode 52 and a water-cooled copper electrode 53. The two graphite electrodes 52 are connected to the water-cooled copper electrodes 53 at their ends facing away from each other, respectively, and the water-cooled copper electrodes 53 pass through the inner and outer walls of the furnace body 3.

[0051] The beneficial effect of the above embodiment is that the electric heaters 51 at both ends form a double-sided resistance radiation surface heat source. The water-cooled copper electrode 53 led out of the furnace body 3 is convenient for connecting to an external high-power power source to input electric energy to the electric heater 51. At the same time, it also has the effect of cooling the electrode to generate heat.

[0052] In a non-limiting example, Figure 6As shown, the heating wire of the electric heater 51 is zigzag-shaped, and gaps are formed between adjacent heating wires. The gap at the centroid of the electric heater 51 is partially widened to form a center hole 511. The center hole 511 facilitates the optical path channel for detection by the temperature measuring probe.

[0053] In one embodiment, if Figure 3 , Figure 4 As shown, the mutual opening joints of the furnace body units are provided with flange rings 36 .

[0054] The beneficial effect of adopting the above embodiment is that the flange ring 36 facilitates the two furnace body units to fit closely with each other.

[0055] In one embodiment, the flange ring 36 can be connected to the sample sleeve assembly 6, especially to the sample disk 63 in the axial direction of the dynamic measurement device ( Figure 3 The two furnace units are staggered in the up-down direction, which makes it less likely for the docking position of the two furnace units to affect the operation of the sample sleeve assembly 6.

[0056] In one embodiment, if Figure 5 As shown, the mutually opening joints of the thermal insulation layer units are provided with annular concave-convex structures 43 that match each other.

[0057] The beneficial effects of the above embodiment are: heat can be isolated and the gas released from the material can be prevented from directly contacting the steel structure furnace body 3. The annular concave-convex structures 43 interlock with each other to improve the sealing and heat preservation of the insulation layer 4, and also facilitate the alignment and installation of the two insulation layer units.

[0058] In a non-limiting example, Figure 3 As shown, the top of one of the two furnace body units is provided with an upper through pipe 32, and the bottom of the other furnace body unit is provided with a lower through pipe 33, and both the upper through pipe 32 and the lower through pipe 33 are connected to the inside and outside of the furnace body 3. Both the upper through pipe 32 and the lower through pipe 33 can be used for vacuuming, controlling the vacuum degree in the furnace body 3, and can also be used for introducing inert gas.

[0059] In a non-limiting example, Figure 4 , Figure 5 As shown, the bottom of the outer wall of the furnace body 3 also protrudes with a support leg 34. The support leg 34 is convenient for improving the stability of the furnace body 3 as a whole.

[0060] In a non-limiting example, Figure 3 As shown, along the axial direction of the furnace body 3, the furnace body 3 is further provided with a hollow compartment 35 between the heat-insulating layer 4 and the non-contact infrared temperature measuring probe 1. The compartment 35 can increase the axial distance between the non-contact infrared temperature measuring probe 1 and the sample sleeve assembly 6. The compartment 35 can also further improve the heat-insulating performance of the furnace body 3 in the axial direction.

[0061] In one embodiment, if Figure 3 As shown, the insulation layer unit includes a receiving cavity 41 that is opened and docked with each other, the sample sleeve assembly 6 and the heating unit are located in the receiving cavity 41, and the bottom surface of the receiving cavity 41 is connected to a through channel 42, the inner diameter of the through channel 42 is smaller than the inner diameter of the receiving cavity 41, and the through channel 42 avoids the detection path of the temperature measuring probe, and the detection path is the optical path channel of the insulation layer 4.

[0062] The beneficial effect of the above embodiment is that the accommodating cavity 41 provides enough space to accommodate the sample sleeve assembly 6 and the electric heater 51, forming a heating cavity, and the relatively narrow aperture of the through channel 42 takes into account both heat preservation and smooth light path.

[0063] In a non-limiting example, Figure 3 As shown, the outer diameters of the first sleeve 61 and the second sleeve 62 are larger than the inner diameter of the accommodating cavity 41. The inner diameter of the accommodating cavity 41 may be larger than the diameter of the heating unit. The cavity surrounded by the accommodating cavity 41 may be cylindrical.

[0064] In a non-limiting example, Figure 4 As shown, the furnace body 3 also has a flange seat 31 that penetrates the inner and outer walls of the furnace body. Figure 2 As shown, the water-cooled copper electrode 53 includes a raised radial flange 531 , and the flange seat 31 is sealingly matched with the radial flange 531 .

[0065] In a non-limiting example, Figure 7 As shown, the surface of the heat shield 64 and other parts in the sample sleeve assembly 6 is provided with radially extending grooves 6a, and the grooves 6a are for facilitating the installation of thermocouples, which are used to calibrate and verify the accuracy of the non-contact infrared temperature measuring probe 1. This is a design considering the nature of the test verification. The final product may not be provided with grooves 6a.

[0066] On the other hand, the present application also provides a dynamic measurement method of thermal conductivity under high temperature conditions, including: Step S1: Using the heating components 5 arranged at both ends of the sample sleeve assembly 6, the sample disk 63 and the heat protection plate 64 are heated as a whole. Step S2: When the insulation layer 4 is heated to a specified uniform temperature, the heating component 5 at one end where the heat protection plate 64 is not set increases the power to continue to heat up, while the heating component 5 at the other end maintains the power unchanged. Step S3: Use a temperature measuring probe to measure the dynamic temperature rise curve at the center points of both ends of the sample disk 63 to obtain the thermal diffusion coefficient and thermal conductivity of the material being measured.

[0067] The dynamic measurement method of thermal conductivity under high temperature conditions of the present application is to realize the dynamic measurement of thermal conductivity and thermal diffusion coefficient under high temperature conditions. It can avoid the problems of low accuracy and low temperature range of the static method for measuring thermal conductivity, and avoid the problem that the dynamic method using laser heat source cannot form an effective temperature pulse in the porous medium insulation material.

[0068] The first thing that needs to be achieved in dynamic measurement is a uniform temperature field of the material being measured under high temperature. A symmetrical heating component 5 is used to achieve overall heating of the sample disk 63, sleeve, and heat shield 64, which are the material being measured. The strong thermal conductivity of the graphite sleeve on the outside is combined to achieve temperature uniformity inside the sample disk 63, sleeve, and heat shield 54.

[0069] Then, on the basis of achieving a high-temperature uniform temperature field, the power and temperature of the heating component 5 at the end without the heat protection plate 64 are increased, while the power of the heating component 5 at the other end remains unchanged, so that the sample disk 63 is only subjected to a single-sided heat pulse. The dynamic temperature rise curve at the center points of the two axial ends of the sample disk 63 is measured using a non-contact infrared temperature measurement probe 1, thereby obtaining the thermal diffusion coefficient and thermal conductivity of the material.

[0070] The preferred solution of the furnace body 3 is to have two sections of metal shells, i.e., two furnace body units, which are connected in the middle of the furnace body 3 by a flange ring 36, and the furnace body 3 is a pressure-bearing metal container. The interior of the furnace body 3 is lined with a thicker layer of carbon fiber felt insulation material, i.e., the insulation layer 4. The sample sleeve assembly 6 is a core assembly, and the sample disc 63 in the sample sleeve assembly 6 is the material to be tested. The sample disc 63 is processed into a round cake with a certain thickness. One end of the sample disc 63 is tightly attached to a heat protection plate 64 with the same outer diameter. The heat protection plate 6 is made of a high-temperature resistant material with a lower thermal conductivity. The sample disc 63 and the heat protection plate 6 are sandwiched as a whole between the first sleeve 61 and the second sleeve 62 made of graphite. At a certain position from each end of the sample sleeve assembly 6, a comb-shaped graphite electric heater 51 is arranged. The conductor of the electric heater 51 passes through the insulation layer 4 and the furnace body 3, and is then connected to a high-power power supply outside the furnace body 3. There are small holes in the middle of the first sleeve 61 and the second sleeve 62 of the sample sleeve assembly 6 and in the center of the heat shield 6. A non-contact infrared temperature measuring probe 1 is installed at each end outside the furnace body 3, and the two non-contact infrared temperature measuring probes 1 are arranged facing each other. The non-contact infrared temperature measuring probes 1 detect the temperature of the small holes at the center of the two sides of the sample sleeve assembly 6 in real time and accurately through the viewing mirror 2, that is, the temperature of the sample plate 63 of the material to be tested.

[0071] The first half of the process of the dynamic measurement method of thermal conductivity under high temperature conditions of the present application is as follows: first, assemble the sample sleeve assembly 6 and install it in the accommodating cavity 41 opened in the middle of the thermal insulation layer 4, then merge the two sections of the furnace unit, and tightly connect them through the flange ring 36. Before starting heating, evacuate the furnace body 3 into a vacuum state. After evacuation, a certain chemically inert gas, such as nitrogen, helium, etc., can be filled into the container according to specific test requirements. After the above operation is completed, turn on the heating assembly 5, and heat the sample sleeve assembly 6 to the temperature of the thermal conductivity measurement condition to be implemented, and the maximum temperature can reach 2000°C. After the temperature of the sample sleeve assembly 6 is constant, the thermal conductivity test process begins.

[0072] The working temperature of the furnace body 3 can reach a high temperature of 2000°C, which is guaranteed by the following three aspects: First, the thickness of the insulation layer 4 in all directions is relatively thick, so that the center temperature of the furnace body 3 can reach 2000°C, forming a sufficiently large temperature gradient, that is, decreasing from 2000°C inside to about 100°C of the steel on the surface of the furnace body 3. Second, the design power of the two heating components 5 ensures that sufficient heating power is provided, and is greater than the heat dissipation power at 2000°C in a steady state. Third, the non-contact infrared temperature measuring probe 1 used is a non-contact temperature measurement method, which can achieve temperature measurement up to 2000°C, rather than the traditional armored thermocouple, which is easily damaged.

[0073] The second half of the dynamic measurement method of thermal conductivity under high temperature conditions of the present application is as follows: the heating power of one of the heating components 5 is increased stepwise and kept constant, while the heating power of the other heating component 5 is kept unchanged. The temperature changes at both ends of the sample disk 63 of the material under test are continuously recorded. This test process does not have to continue until the temperature of the material under test reaches another equilibrium state. Finally, by recording the temperature change process, the inverse problem calculation method of the heat conduction problem is used to calculate the thermal conductivity value of the sample disk 63 of the material under test at this temperature. Specifically, the thermal diffusion coefficient is measured first, and then the thermal conductivity is converted. The above-mentioned structural setting ensures the ideal measurement boundary and measurement conditions, improves the accuracy of the material thermal conductivity measurement, and also improves the temperature conditions for the thermal conductivity measurement. The test speed is also improved, which facilitates the rapid and accurate measurement of the thermal conductivity of high-temperature resistant materials under high temperature conditions.

[0074] The above embodiments are only for illustrating the technical concept and features of the present application, and their purpose is to enable people familiar with this technology to understand the content of the present application and implement it. They cannot be used to limit the scope of protection of the present application. All equivalent changes or modifications made according to the spirit of the present application should be included in the scope of protection of the present application.

Claims

1. A dynamic measurement device for thermal conductivity under high temperature conditions, characterized in that: include: Furnace body (3); A heat-insulating layer (4), the heat-insulating layer (4) being located inside the furnace body (3); A sample sleeve assembly (6) for mounting a sample disc (63), wherein the sample sleeve assembly (6) comprises a heat shield (64), wherein the heat shield (64) is mounted on one axial end of the sample disc (63); A heating assembly (5), wherein the heating assembly (5) comprises a heating unit located in the thermal insulation layer (4), the heating units are arranged at both ends of the sample sleeve assembly (6), the heat protection plate (64) is located between the sample disk (63) and one of the heating units, and the two heating assemblies (5) are independently controlled and have adjustable power; The temperature measuring probes are located at two ends of the furnace body (3); the thermal insulation layer (4) and the heating component (5) are provided with optical path channels that avoid the detection path of the temperature measuring probes.

2. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 1, characterized in that: The sample sleeve assembly (6) comprises a sleeve for wrapping the sample disc (63) and the heat shielding plate (64).

3. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 2, characterized in that: The sample sleeve assembly (6) includes a graphite paper (65) for being sandwiched between the sample disc (63) and the heat shielding plate (64).

4. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 3, characterized in that: The sample sleeve assembly (6) also includes emissivity tubes for being arranged at both ends of the sample disk (63), the facing surfaces of the two emissivity tubes being in a blocked state, the facing surfaces of the two emissivity tubes being in an open state, and the emissivity tubes passing through the sleeve and the heat shield (64).

5. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 2, characterized in that: The material of the thermal insulation layer (4) includes carbon fiber felt, and the material of the sleeve includes graphite; The furnace body (3) is evacuated or filled with inert gas.

6. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 4, characterized in that: The sample plate (63), the heat shield (64), the graphite paper (65), and the emissivity tube are coaxially arranged; The furnace body (3), the heat-insulating layer (4), the heating unit, the sample sleeve assembly (6), and the temperature measuring probe are coaxially arranged; The furnace body (3) comprises furnace body units which are opened and butted against each other, and the heat-insulating layer (4) comprises heat-insulating layer units which are opened and butted against each other.

7. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 1, characterized in that: The temperature measuring probe is a non-contact infrared temperature measuring probe (1), the non-contact infrared temperature measuring probe (1) is located outside the furnace body (3), and the non-contact infrared temperature measuring probe (1) is connected to the furnace body (3) via a viewing mirror (2).

8. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 1, characterized in that: The heating unit is an electric heater (51), the electric heater (51) is in the shape of a round pancake, and the electric heater (51) comprises a meandering heating wire; The two ends of the heating wire are connected to graphite electrodes (52), and the opposite ends of the two graphite electrodes (52) are connected to water-cooled copper electrodes (53), and the water-cooled copper electrodes (53) pass through the inner and outer walls of the furnace body (3).

9. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 6, characterized in that: The mutual openings of the furnace units are connected at the joints with flange rings (36); The mutually opening joints of the thermal insulation layer units are provided with mutually matching annular concave-convex structures (43); The thermal insulation layer unit comprises a receiving cavity (41) that is opened and connected to each other, the sample sleeve assembly (6) and the heating unit are located in the receiving cavity (41), the bottom surface of the receiving cavity (41) is connected to a through channel (42), the inner diameter of the through channel (42) is smaller than the inner diameter of the receiving cavity (41), and the optical path channel includes the through channel (42).

10. A method for dynamic measurement of thermal conductivity under high temperature conditions, characterized in that: Using the dynamic measurement device for thermal conductivity under high temperature conditions according to any one of claims 1 to 9, the dynamic measurement method for thermal conductivity under high temperature conditions comprises: Step S1: using the heating components (5) arranged at both ends of the sample sleeve component (6) to raise the temperature of the sample disk (63) and the heat shield (64) as a whole; Step S2: when the insulation layer (4) is heated to a specified uniform temperature, the power of the heating component (5) at one end adjacent to the heat protection plate (64) is kept unchanged, and the power of the heating component (5) at the other end is increased and the temperature continues to rise; Step S3: using the temperature measuring probe to non-contactly measure the sample disk (63) as the material to be measured, measuring the dynamic temperature rise curve at the center points of both ends of the sample disk (63), and obtaining the thermal diffusion coefficient and thermal conductivity coefficient of the material to be measured.

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