Dynamic measurement device and method for thermal conductivity coefficient under high temperature condition

Abstract

A dynamic measurement device and method for thermal conductivity under high-temperature conditions are provided. The dynamic measurement device for thermal conductivity under high-temperature conditions includes: a furnace body; an insulation layer located inside the furnace body; a sample sleeve assembly for mounting the sample pan and forming a uniform temperature surface, the sample sleeve assembly including a heat shield plate for mounting to one axial end of the sample pan; a heating assembly including heating units located within the insulation layer, with heating units at both ends of the sample sleeve assembly, the heat shield plate located between the sample pan and one of the heating units, the two heating assemblies being independently controlled and having adjustable power; and temperature probes located at both ends of the furnace body. The insulation layer and heating assembly have optical paths that avoid the detection path of the temperature probes. This ensures that the heating assemblies at both ends of the sample sleeve assembly can provide sufficient heating power, which is beneficial for forming a uniform temperature field. The heat shield plate at only one end facilitates temperature rise control only at a single axial end.

Description

Technical Field

[0001] This 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 Technology

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

[0003] High-temperature resistant materials are increasingly used in cutting-edge fields such as nuclear energy, aerospace, and metallurgy. Advanced space rockets and space shuttles must use these materials during atmospheric reentry to isolate them from extremely hot gases, thus preventing the spacecraft from disintegrating. The Space Shuttle Columbia disintegrated during reentry because its surface thermal insulation tiles failed. These applications often require the selection of high-temperature resistant materials and insulation materials, along with appropriate heat transfer design. The thermal conductivity of high-temperature resistant insulation materials is a crucial fundamental data point for these applications; therefore, convenient and accurate measurement of the thermal conductivity of materials at high temperatures has become an urgent technical requirement.

[0004] Generally, the thermal conductivity of a material is a function of temperature, not a constant. Therefore, it is usually necessary to measure the thermal conductivity of materials at different temperatures. The measurement methods known to the inventors are generally static methods based on the steady-state thermal conductivity law. This involves processing the material into a workpiece with a certain regular shape, heating one side while cooling the other, and calculating the material's thermal conductivity after the temperature stabilizes using power, temperature difference, and workpiece dimensions. There are also dynamic thermal conductivity measurement methods, such as using laser pulses to heat a localized area of ​​the material for a short time, then observing the temperature field changes over time, and subsequently calculating the material's thermal diffusivity and thermal conductivity.

[0005] The inventor's understanding of static methods for measuring thermal conductivity often results in low accuracy at high temperatures. This is because static methods inevitably involve measuring the heat power conducted by the material under test. However, due to heat dissipation issues, it's impossible to guarantee that all heating power passes through the material. Heat dissipated at the thermal boundaries cannot be accurately measured, and the heat transfer path is often not entirely along the direction of heat flux density. Therefore, the accuracy of static methods is relatively low. Furthermore, static methods are difficult to apply to high-temperature applications. To prevent material oxidation at high temperatures, testing must be conducted in a closed environment protected by a vacuum or inert gas, making it difficult to create the necessary heat dissipation conditions at the cold end of the material. At temperatures above 1200°C, the heat dissipation loss of static methods is significant, leading to inaccurate heat power measurements and reduced accuracy.

[0006] The inventor's understanding of the dynamic method for measuring thermal conductivity using laser heating is limited because insulation materials are porous media with low thermal diffusivity. The heat generated by the laser pulse cannot be completely absorbed on the surface, thus failing to form effective pulsed heat diffusion within the insulation material. Therefore, it is generally not used for testing insulation materials.

[0007] In addition, thermal conductivity meters are commonly used to measure thermal conductivity. The hot-wire thermal conductivity meter is a common type. This method involves embedding a hot wire in the sample, passing a constant current through it to generate heat, and then measuring the temperature of the hot wire and related parameters to calculate the thermal conductivity. It is suitable for a variety of materials, especially anisotropic materials and materials with low thermal conductivity. Thermal conductivity meters typically use a constant current heat source. For example, Chinese invention patent CN107589148A discloses a "Controllable Atmosphere Unsteady-State Hot-Wire Thermal Conductivity Tester." This tester includes a sealed test furnace with a furnace chamber lined with a refractory lining, mounted 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. The furnace cover is equipped with a pressure sensor, a safety pressure regulating valve, and a temperature-controlled thermocouple. The hot-wire unit on the furnace door includes heating leads, pressure measuring leads, and a differential thermocouple. In this testing instrument, the heating leads, which serve as the hot wire unit, are arranged on one side, forming a heat source located on that side. Furthermore, the hot wire unit generates heat at a constant power. However, relying solely on a constant power heat source on one side inherently suffers from deficiencies in heating efficiency and uniformity. The hot wire heater itself also functions as the central temperature-sensing thermocouple, often employing materials such as copper-constantan or platinum-platinum-rhodium. The melting points of these materials limit their high-temperature applications, and they are prone to chemical reactions with insulation materials at high temperatures, leading to failure. Summary of the Invention

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

[0009] One embodiment of the dynamic measurement device of this application includes: a furnace body; a heat insulation layer located inside the furnace body; a sample sleeve assembly for mounting a sample tray, the sample sleeve assembly including a heat shield plate for mounting to one axial end of the sample tray; a heating assembly including heating units located within the heat insulation layer, with heating units provided at both ends of the sample sleeve assembly, the heat shield plate located between the sample tray and one of the heating units, the two heating assemblies being independently controlled and having adjustable power; and a temperature probe located at both ends of the furnace body, the heat insulation layer and the heating assembly having optical path channels that avoid the detection path of the temperature probe.

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

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

[0012] As a further improvement of this application, the sample sleeve assembly also includes emissivity tubes for being disposed at both ends of the sample disk, the opposing surfaces of the two emissivity tubes being in a blocked state, the opposing surfaces of the two emissivity tubes being in an open state, and the emissivity tubes penetrating the sleeve and the heat shield.

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

[0014] As a further improvement of this application, the sample tray, the heat shield, the graphite paper, and the emissivity tube are arranged coaxially; the furnace body, the insulation layer, the heating unit, the sample sleeve assembly, and the temperature probe are arranged coaxially; the furnace body includes furnace body units with mutual openings and connections, and the insulation layer includes insulation layer units with mutual openings and connections.

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

[0016] As a further improvement of this application, the heating unit is an electric heater, which is disc-shaped and includes a meandering heating wire; graphite electrodes are connected to both ends of the heating wire, and a water-cooled copper electrode is connected to one end of each graphite electrode facing away from each other, the water-cooled copper electrode passing through the inner and outer walls of the furnace body.

[0017] As a further improvement of this application, the furnace body units have flange rings at their inter-opening joints; the insulation layer units have matching annular concave-convex structures at their inter-opening joints; the insulation layer units include inter-opening cavities, the sample sleeve assembly and the heating unit are located in the cavities, the bottom surface of the cavities is connected to a through channel, the inner diameter of the through channel is smaller than the inner diameter of the cavities, and the optical path channel includes the through channel.

[0018] Secondly, a dynamic measurement method for 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 preceding claims, the dynamic measurement method for thermal conductivity under high-temperature conditions includes: Step S1: using the heating components arranged at both ends of the sample sleeve assembly to heat the sample pan 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 a constant power, while the heating component at the other end increases its power and continues to heat; Step S3: using the temperature probe to non-contactly measure the sample pan, which is the material being tested, and measuring the dynamic temperature rise curve at the center points at both ends of the sample pan to obtain the thermal diffusivity and thermal conductivity of the material being tested.

[0019] The beneficial effects of the dynamic measurement device for thermal conductivity under high-temperature conditions proposed in this application include: providing a testing device capable of accurately and rapidly measuring the thermal conductivity of materials under high-temperature conditions. First, compared to a single heat source, the sample sleeve assembly has heating components at both ends, providing sufficient heating power to generate a significant temperature rise curve in the insulation material within a short time. Second, the two heating components positioned at both ends facilitate heating both ends of the sample sleeve assembly to a uniform temperature field with the same temperature. Third, the power of the two heating components is adjustable, and each can be controlled independently. This allows the two heating components to operate under different conditions, providing different temperature field conditions for both ends of the sample sleeve assembly, thus facilitating the observation of dynamic temperature changes. The sample sleeve assembly allows the radiant heat from the heating components to form a uniform surface heat source and transfer it to the surface of the tested material. Furthermore, the sample sleeve assembly can increase the boundary temperature of the side surface of the tested material, significantly preventing heat loss along the radial direction of the side surface, improving the temperature field uniformity in the central region of the tested material, and reducing measurement errors. Therefore, the heat-insulating plate is only attached to one end of the sample tray, providing insulation only for one axial end of the sample tray to reduce axial heat loss during dynamic heating. Finally, the insulation layer and furnace body provide multi-layer insulation, facilitating the formation of a stable and uniform high-temperature field inside the equipment. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is an axial view of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions according to this application;

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

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

[0024] Figure 4 This is a perspective view of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions according to this application;

[0025] Figure 5 This is an exploded view of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions according to this application;

[0026] Figure 6 This is a perspective view of the heating component of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions of this application;

[0027] Figure 7 This is an exploded view of the sample sleeve assembly of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions of this application.

[0028] Figure 8 This is an axial view of the sample sleeve assembly of one embodiment of the dynamic measurement device for thermal conductivity under high temperature conditions of this application.

[0029] Figure 9 yes Figure 8 CC section view.

[0030] Explanation of reference numerals in the attached figures

[0031] 1-Non-contact infrared temperature probe; 2-Eyepiece; 3-Furnace body; 31-Flange seat; 32-Upper pipe; 33-Lower pipe; 34-Support leg; 35-Cavity; 36-Flange ring; 4-Insulation layer; 41-Receiving cavity; 42-Through channel; 43-Annular concave-convex structure; 5-Heating component; 51-Electric heater; 511-Central hole; 52-Graphite electrode; 53-Water-cooled copper electrode; 531-Radial flange; 6-Sample sleeve assembly; 61-First sleeve; 62-Second sleeve; 63-Sample tray; 64-Heat protection plate; 65-Graphite paper; 66-First emissivity tube; 67-Second emissivity tube; 6a-Groove. Detailed Implementation

[0032] Exemplary embodiments of this application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement this application only, and are not intended to exhaustively describe all possible methods of this application, nor to limit the scope of this application.

[0033] The following detailed description, with reference to specific embodiments, provides further explanation of the dynamic measurement device and method for thermal conductivity under high temperature conditions of this application.

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

[0035] The heat shield 64 is used for axial one-sided heat preservation. The heat shield 64 is only set at one end of the sample pan 63, and the heat shield 64 can be in contact with and attached to the sample pan 63. This is because during dynamic measurement, only the heating component 5 at the end without the heat shield 64 is heated, while the power of the heating component 5 at the end with the heat shield 64 remains unchanged. The heat shield 64 is used to reduce axial heat loss during dynamic heating and is a component that prevents heat from being dissipated too quickly.

[0036] In a non-limiting example, the thermal conductivity of the heat shield 64 is similar to or the same as that of the sample plate 63, which is the test piece.

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

[0038] The beneficial effects of using the above embodiments are: the sleeve can quickly form a uniform surface heat source from the radiant heat source of the heating component 5, achieving heat conduction and uniform heating of the sample plate 63 and the heat shield 64, ensuring the uniform temperature of the sample plate 63 and the heat shield 64 within a certain period. Furthermore, the uniformly heated sleeve can increase the boundary temperature of the side of the tested material and enhance the radial temperature uniformity of the central region of the tested material.

[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. The material of the insulation layer 4 can include carbon fiber felt. The sleeve is made of a material with high thermal conductivity, such as graphite. The furnace body 3 is evacuated or filled with inert gas.

[0040] like Figure 7 , Figure 9 As shown, in one embodiment, graphite paper 65 is sandwiched between the sample tray 63 and the heat shield 64. The sample sleeve assembly 6 also includes emissivity tubes located at both ends of the sample tray 63, the emissivity tubes including a first emissivity tube 66 and a second emissivity tube 67. Figure 9 As shown, the opposing surfaces of the first emissivity tube 66 and the second emissivity tube 67 are in a blocked state, while the opposing surfaces of the first emissivity tube 66 and the second emissivity tube 67 are in an open state. The axial length of the second emissivity tube 67 can be approximately three times the axial length of the first emissivity tube 66.

[0041] The beneficial effects of using the above embodiments are as follows: the heat shield 64 can be made of a porous medium, and the graphite paper 65 is used to reduce the contact thermal resistance of the porous medium, while also providing a standard surface emissivity for infrared measurement. Both the first emissivity tube 66 and the second emissivity tube 67 have one end sealed to set a standardized surface emissivity, thereby improving the repeatability of infrared temperature measurement. The emissivity tubes are used to form a standard emissivity surface, facilitating the standardization of infrared temperature measurements.

[0042] like Figure 9 As shown, in one embodiment, a first emissivity tube 66 passes through a first sleeve 61, and one end of the first emissivity tube 66 abuts against a sample tray 63. A second emissivity tube 67 passes through a second sleeve 62 and a heat shield 64. One end of the second emissivity tube 67 abuts against 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 precisely to form a standard emissivity surface.

[0044] In one embodiment, the first sleeve 61, the second sleeve 62, the sample tray 63, the heat shield 64, the graphite paper 65, the first emissivity tube 66, and the second emissivity tube 67 are all arranged coaxially. Figure 7As shown, the edges of the first sleeve 61, the second sleeve 62, the sample plate 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 tray 63, the heat shield 64, and the graphite paper 65 can be equal, and the inner diameters of the first sleeve 61 and the second sleeve 62 can be equal to the outer diameters of the sample tray 63, the heat shield 64, and the graphite paper 65. The thickness of the graphite paper 65 is much smaller than the thickness of the sample tray 63 and the heat shield 64.

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

[0047] The beneficial effect of using the above embodiments is that it facilitates the precise alignment of the temperature probe with the center of the two shaft ends in the sample sleeve assembly 6.

[0048] In one embodiment, the temperature probe is a non-contact infrared temperature probe 1, which is connected to the furnace body 3 via a sight glass 2. Both the non-contact infrared temperature probe 1 and the sight glass 2 are located outside the furnace body 3.

[0049] The beneficial effect of adopting the above embodiment is that it avoids the chemical reaction at high temperature caused by direct contact between the non-contact infrared temperature measuring probe 1 and the insulation layer 4. The endoscope 2 serves to seal a part of the furnace body 3, and also serves to transmit light. In order to allow infrared light to pass through the endoscope 2, the optical path between the non-contact infrared temperature measuring probe 1 and the surface of the material being measured is unobstructed.

[0050] like Figure 6 As shown, in one embodiment, the heating assembly 5 includes an electric heater 51, which is disc-shaped and is composed of a meandering heating wire. Electrodes are connected to both ends of the electric heater 51. The electrodes may include graphite electrodes 52 and water-cooled copper electrodes 53. The two graphite electrodes 52 are opposite to each other, and one end is connected to a water-cooled copper electrode 53. The water-cooled copper electrode 53 passes through the inner and outer walls of the furnace body 3.

[0051] The beneficial effects of the above embodiment are: the electric heaters 51 at both ends form a double-sided resistive radiation heat source. The water-cooled copper electrodes 53, led out of the furnace body 3, facilitate connection to a high-power external power source to input electrical energy into the electric heaters 51. Simultaneously, it also has the effect of cooling the heating electrodes.

[0052] In a non-restrictive example, such as Figure 6As shown, the heating wire of the electric heater 51 is zigzag or Z-shaped, and gaps are formed between adjacent heating wires. The gaps at the centroid of the electric heater 51 are locally widened to form a central hole 511, which facilitates the optical path of the temperature probe.

[0053] In one embodiment, such as Figure 3 , Figure 4 As shown, the furnace body units have flange rings 36 at their inter-opening joints.

[0054] The beneficial effect of adopting the above embodiment is that the flange ring 36 facilitates the close cooperation between the two furnace body units.

[0055] In one embodiment, the flange 36 can be coupled to the sample sleeve assembly 6, particularly to the sample disc 63, along the axial direction of the dynamic measuring device. Figure 3 The two furnace units are staggered in the vertical 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, such as Figure 5 As shown, the openings of the insulation layer units have matching annular concave-convex structures 43.

[0057] The beneficial effects of using the above embodiments are: it can insulate heat and prevent the gas released from the material from directly contacting the furnace body 3 of the steel structure. The interlocking of the annular concave-convex structure 43 improves the sealing and heat preservation of the insulation layer 4, and also facilitates the alignment and installation of the two insulation layer units.

[0058] In a non-restrictive example, such as Figure 3 As shown, one of the two furnace units has an upper through pipe 32 at the top, and the other furnace unit has a lower through pipe 33 at the bottom. Both the upper through pipe 32 and the lower through pipe 33 connect the inside and outside of the furnace body 3. Both the upper through pipe 32 and the lower through pipe 33 can be used to evacuate and control the vacuum level inside the furnace body 3, and can also be used to introduce inert gas.

[0059] In a non-restrictive example, such as Figure 4 , Figure 5 As shown, the bottom of the outer wall of the furnace body 3 also protrudes to the support leg 34. The support leg 34 helps to improve the overall stability of the furnace body 3.

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

[0061] In one embodiment, such as Figure 3 As shown, the insulation layer unit includes a receiving cavity 41 with openings and joints. The sample sleeve assembly 6 and the heating unit are located inside 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. The through channel 42 avoids the detection path of the temperature measuring probe. The detection path is the optical path channel of the insulation layer 4.

[0062] The beneficial effects of the above embodiments are: the receiving cavity 41 provides sufficient space to accommodate the sample sleeve assembly 6 and the electric heater 51, forming a heating cavity. Meanwhile, the relatively narrow aperture of the through channel 42 balances heat preservation with unobstructed optical path.

[0063] In a non-restrictive example, such as 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 receiving cavity 41. The inner diameter of the receiving cavity 41 can be larger than the diameter of the heating unit. The cavity enclosed by the receiving cavity 41 can be cylindrical.

[0064] In a non-restrictive example, such as Figure 4 As shown, the furnace body 3 also has a flange seat 31 that extends through its inner and outer walls. (As indicated...) Figure 2 As shown, the water-cooled copper electrode 53 includes a raised radial flange 531, and the flange seat 31 is sealed to the radial flange 531.

[0065] In a non-restrictive example, such as Figure 7 As shown, the surface of components such as the heat shield 64 in the sample sleeve assembly 6 is provided with radially extending grooves 6a. Grooves 6a are provided to facilitate the installation of thermocouples, which are used to calibrate and verify the accuracy of the non-contact infrared temperature probe 1. This design takes into account the nature of the test verification. The final product may not have grooves 6a.

[0066] On the other hand, this application also provides a dynamic measurement method for thermal conductivity under high temperature conditions, including: Step S1: Using heating components 5 arranged at both ends of the sample sleeve assembly 6, the sample plate 63 and the heat shield 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 the end without the heat shield 64 increases its power to continue heating, while the heating component 5 at the other end maintains a constant power. Step S3: Using a temperature probe, the dynamic temperature rise curve at the center point of both ends of the sample plate 63 is measured to obtain the thermal diffusivity and thermal conductivity of the material being tested.

[0067] The dynamic measurement method for thermal conductivity under high-temperature conditions proposed in this application aims to achieve dynamic measurement of thermal conductivity and thermal diffusivity under high-temperature conditions. This avoids the problems of low accuracy and limited temperature range in static thermal conductivity measurements, as well as the inability to generate effective temperature pulses in porous insulating materials using dynamic methods with laser heat sources.

[0068] The first requirement for dynamic measurement is to achieve a uniform temperature field of the test material at high temperature. A symmetrical heating component 5 is used to raise the overall temperature of the sample plate 63, sleeve, and heat shield 64, which are the test materials. Combined with the strong thermal conductivity of the graphite sleeve on the outside, the temperature inside the sample plate 63, sleeve, and heat shield 54 is made uniform.

[0069] Next, based on the achievement of a high temperature uniform temperature field, the power and temperature of the heating component 5 at the end without the heat shield 64 are increased, while the power of the heating component 5 at the other end remains unchanged, so that the sample plate 63 is only subjected to a single heat pulse. The dynamic temperature rise curve at the center point of the two axial ends of the sample plate 63 is measured using a non-contact infrared temperature probe 1, thereby obtaining the thermal diffusivity and thermal conductivity of the material.

[0070] The preferred embodiment of furnace body 3 is a two-section metal shell, i.e., two furnace body units, connected in the middle by a flange ring 36. Furnace body 3 is a pressure-bearing metal container. A thick layer of carbon fiber felt insulation material, i.e., insulation layer 4, is lined inside furnace body 3. The sample sleeve assembly 6 is the core component. The sample disc 63 within the sample sleeve assembly 6 is the material to be tested. The sample disc 63 is machined into a disc shape with a certain thickness. One end of the sample disc 63 is tightly attached to a heat-protecting plate 64 with the same outer diameter. The heat-protecting plate 6 is made of a high-temperature resistant material with low thermal conductivity. The sample disc 63 and the heat-protecting plate 6 are sandwiched between a first sleeve 61 and a second sleeve 62 made of graphite. At certain positions at both ends 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. Small holes are present in the middle of the first sleeve 61 and the second sleeve 62 of the sample sleeve assembly 6, as well as in the center of the heat shield 6. A non-contact infrared temperature probe 1 is installed at each end of the furnace body 3, with the two non-contact infrared temperature probes 1 facing each other. The non-contact infrared temperature probes 1 use a viewing lens 2 to detect the temperature at the small holes in the center of both sides of the sample sleeve assembly 6 in real time and accurately, which is the temperature of the sample plate 63 of the material being tested.

[0071] The first half of the dynamic measurement method for thermal conductivity under high-temperature conditions in this application is as follows: First, the sample sleeve assembly 6 is assembled and installed in the cavity 41 cut in the middle of the insulation layer 4. Then, the two furnace body units are merged and tightly connected by flange ring 36. Before heating begins, the furnace body 3 is evacuated to a vacuum state. After evacuation, a chemical inert gas, such as nitrogen or helium, can be introduced into the container according to specific test requirements. After the above operations are completed, the heating component 5 is turned on to heat the sample sleeve assembly 6 to the temperature required for thermal conductivity measurement, with a maximum temperature of 2000℃. Once the temperature of the sample sleeve assembly 6 stabilizes, the thermal conductivity testing process begins.

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

[0073] The latter half of the dynamic measurement method for thermal conductivity under high-temperature conditions in this application is as follows: The heating power of one heating component 5 is increased in a stepwise manner and kept constant, while the heating power of the other heating component 5 remains unchanged. The temperature changes at both ends of the sample plate 63 of the tested material are continuously recorded. This test process does not need to continue until the temperature of the tested material reaches another equilibrium state. Finally, by recording the temperature change process, the thermal conductivity value of the sample plate 63 of the tested material at this temperature is calculated using the inverse problem calculation method of thermal conductivity. Specifically, the thermal diffusivity is measured first, and then the thermal conductivity is calculated. The above structural setup ensures ideal measurement boundaries and conditions, improves the accuracy of thermal conductivity measurement, enhances the temperature conditions for thermal conductivity measurement, and increases the testing speed, facilitating 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 this application. Their purpose is to enable those skilled in the art to understand the content of this application and implement it. They should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be covered within the scope of protection of this application.

Claims

1. A dynamic measuring device for thermal conductivity under high temperature conditions, characterized in that, include: Furnace body (3); Insulation layer (4), the insulation layer (4) is located inside the furnace body (3); The sample sleeve assembly (6) is used to install the sample tray (63). The sample sleeve assembly (6) includes a heat shield (64) which is used to be installed on one axial end of the sample tray (63). Heating assembly (5), the heating assembly (5) includes a heating unit located in the insulation layer (4), the heating unit is provided at both ends of the sample sleeve assembly (6), the heat protection plate (64) is located between the sample plate (63) and one of the heating units, and the two heating assemblies (5) are independently controlled and have adjustable power. Temperature probes are located at both ends of the furnace body (3). The insulation layer (4) and the heating assembly (5) have optical paths that avoid the detection path of the temperature probes. The sample sleeve assembly (6) includes a sleeve for wrapping the sample disc (63) and the heat shield (64). The sample sleeve assembly (6) also includes emissivity tubes for being disposed at both ends of the sample disk (63). The opposing surfaces of the two emissivity tubes are in a blocked state, and the opposing surfaces of the two emissivity tubes are in an open state. The emissivity tubes penetrate the sleeve and the heat protection plate (64).

2. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 1, characterized in that: The sample sleeve assembly (6) includes graphite paper (65) for clamping between the sample disc (63) and the heat shield (64).

3. The dynamic measuring device for thermal conductivity under high temperature conditions according to claim 1, characterized in that: The insulation layer (4) is made of carbon fiber felt, and the sleeve is made of graphite. The furnace body (3) is either evacuated or filled with inert gas.

4. The dynamic measuring device for thermal conductivity under high temperature conditions according to claim 2, characterized in that: The sample tray (63), the heat shield (64), the graphite paper (65), and the emissivity tube are arranged coaxially. The furnace body (3), the insulation layer (4), the heating unit, the sample sleeve assembly (6), and the temperature measuring probe are arranged coaxially. The furnace body (3) includes furnace body units that are connected to each other through openings, and the insulation layer (4) includes insulation layer units that are connected to each other through openings.

5. The dynamic measuring 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). The non-contact infrared temperature measuring probe (1) is connected to the furnace body (3) through a viewing lens (2).

6. The dynamic measuring device for thermal conductivity under high temperature conditions according to claim 1, characterized in that: The heating unit is an electric heater (51), which is disc-shaped and includes a meandering heating wire. The two ends of the heating wire are connected to graphite electrodes (52), and the two graphite electrodes (52) are connected to a water-cooled copper electrode (53) at opposite ends. The water-cooled copper electrode (53) passes through the inner and outer walls of the furnace body (3).

7. The dynamic measuring device for thermal conductivity under high temperature conditions according to claim 4, characterized in that: The furnace body units are provided with flange rings (36) at their inter-opening joints. The openings of the insulation layer units have matching annular concave-convex structures (43). The insulation layer unit includes a receiving cavity (41) with openings 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). The optical path channel includes the through channel (42).

8. A method for dynamically measuring 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 7, the dynamic measurement method for thermal conductivity under high temperature conditions includes: Step S1: The sample plate (63) and the heat shield (64) are heated as a whole by using the heating components (5) arranged at both ends of the sample sleeve assembly (6); Step S2: When the insulation layer (4) is heated to a specified uniform temperature, the heating component (5) at one end adjacent to the heat protection plate (64) maintains a constant power, while the heating component (5) at the other end increases its power and continues to heat up. Step S3: Use the temperature probe to non-contactly measure the sample plate (63) as the test material, measure the dynamic temperature rise curve at the center points of both ends of the sample plate (63), and obtain the thermal diffusivity and thermal conductivity of the test material.

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