A wide-temperature-range directional spectral emissivity measuring device

Abstract

The application discloses a wide-temperature-range directional spectral emissivity measuring device, a heating device is used for heating a sample, the heating device is rotatable to adjust a measuring angle of the sample; a partition is arranged between a normal-temperature black body, a variable-temperature black body and the heating device; the normal-temperature black body is connected to a black body constant-temperature water tank, and the water in the black body constant-temperature water tank circulates heat exchange with the normal-temperature black body to keep the temperature of the normal-temperature black body constant; the normal-temperature black body, the variable-temperature black body and the heating device are respectively connected with temperature measuring mechanisms for measuring the temperatures of the normal-temperature black body, the variable-temperature black body and the heating device; the heating device and each temperature measuring mechanism are in communication connection with a temperature measuring instrument, the temperature measuring instrument obtains the temperatures of the normal-temperature black body and the variable-temperature black body and the heating temperature of the heating device from each temperature measuring mechanism, and controls the variable-temperature black body and the heating device to start or stop heating. By using the device, the wide-temperature-range directional spectral emissivity of the material can be measured, and the measuring temperature can reach 1000 DEG C.

Description

Technical Field

[0001] This invention relates to the field of material spectral emissivity measurement technology, and specifically to a wide-temperature-range directional spectral emissivity measurement device. Background Technology

[0002] The spectral emissivity of materials is not only a prerequisite for numerous studies and applications, but also has significant scientific research value and practical application value. It is indispensable in quantitative temperature measurement and precise calculations to determine thermal equilibrium. [1-5] Furthermore, many materials used in fields such as infrared remote sensing, industrial production, aerospace, and military require accurate measurement of their spectral emissivity. [6-13] However, spectral emissivity is not only affected by factors such as the material's composition, surface morphology, roughness, and oxidation state, but is also closely related to temperature, wavelength, and orientation. [14-17] Therefore, accurately measuring the spectral emissivity of a material is not easy.

[0003] In recent years, many researchers and scholars both domestically and internationally have dedicated themselves to building devices for measuring the spectral emissivity of materials. The National Institute of Standards and Technology (NIST) in the United States has developed a device based on an FTIR spectrometer. [18,19] It is used to measure transparent materials, with a measurement temperature range of 327℃-1127℃ and a spectral range of 1-20μm. (S. Hatzl et al., Federal Armed Forces University of Munich, Germany)

[20] A device for measuring the normal spectral emissivity of high-temperature solid materials under atmospheric conditions was developed. The sample surface temperature is determined by comparing its spectrum with that of a reference blackbody and calculating the spectral ratio numerically. The measurement temperature range is 500℃-1350℃, and the wavelength range is 0.6μm-15μm. The National Institute of Metrology (NMIJ) of Japan has also developed a high-precision near-room temperature infrared spectral emissivity measurement device.

[21] The measurement spectral range is 5-12 μm, the temperature range is -20℃ to 100℃, and the measurement accuracy is 3%. Cai et al. established a material spectral emissivity measurement device based on a dual-reference blackbody.

[22] The background function of the spectrometer was measured and calibrated in real time using a double blackbody, enabling spectral emissivity measurements from 50℃ to 1000℃. Furthermore, the spectral emissivity of conductive silicon dioxide thin films and silicon carbide at different temperatures within the wavelength range of 1μm-25μm was measured, with an expanded uncertainty of less than 5%. Guo et al. constructed a directional spectral emissivity measurement device based on a Fourier transform infrared spectrometer.

[23] The normal spectral emissivity of silicon carbide wafers in the temperature range of 727℃-1127℃ was measured by adjusting the measurement angle (0-60°) by rotating the sample heater.

[0004] In summary, current research largely focuses on measuring normal spectral emissivity, with very little attention paid to measuring the directional spectral emissivity of materials, especially over a wide temperature range. However, the study of directional spectral emissivity is equally important in fields such as infrared remote sensing, solar energy, radiation thermometry, and military camouflage. For example, directional spectral emissivity research is crucial for achieving infrared stealth for military targets such as aircraft skins, tank shells, and missiles, and the radiation characteristics of solar panels in different directions determine their performance.

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[0026]

[21] J.Ishii, A.Ono, STISFOEngineering, Fourier transformspectrometer for htermal-infrared emissivity measurements near roomtemperatures, in: Conference on optical diagnostic methods for inorganic materials, 2000.

[0027]

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[0028]

[23] YMGuo, SJPang, ZJLuo, Y.Shuai, HPTan, H.Qi, Measurement of Directional Spectral Emissivity at High Temperatures, International Journal of Thermophysics, 40 (2018). Summary of the Invention

[0029] To address the shortcomings of existing technologies, this invention aims to provide a wide-temperature-range directional spectral emissivity measurement device.

[0030] To achieve the above objectives, the present invention adopts the following technical solution:

[0031] A wide-temperature-range directional spectral emissivity measurement device includes a room-temperature blackbody, a variable-temperature blackbody, a heating device, a temperature measuring instrument, an FTIR spectrometer, an optical system, and a host computer;

[0032] The heating device is used to heat the sample and is rotatable to adjust the measurement angle of the sample. A partition is provided between the room-temperature blackbody, the variable-temperature blackbody, and the heating device. The room-temperature blackbody is connected to a constant-temperature water bath, and the water in the constant-temperature water bath circulates and exchanges heat with the room-temperature blackbody to maintain a constant temperature of the room-temperature blackbody. The room-temperature blackbody, the variable-temperature blackbody, and the heating device are each connected to a temperature measuring mechanism for measuring the temperature of the room-temperature blackbody, the variable-temperature blackbody, and the heating device. The heating device and each temperature measuring mechanism are communicatively connected to a thermometer. The thermometer obtains the temperature of the room-temperature blackbody, the variable-temperature blackbody, and the heating temperature of the heating device from each temperature measuring mechanism, and controls the variable-temperature blackbody and the heating device to start or stop heating.

[0033] The optical system includes a thermostatic aperture and a sealed optical path structure. The sealed optical path structure includes an outer shell and a gold-plated off-axis parabolic mirror and a plane mirror disposed within the outer shell. The outer shell has an optical path inlet and an optical path outlet on its two sides, respectively. The optical path inlet corresponds to the thermostatic aperture, and the optical path outlet corresponds to the FTIR spectrometer. The thermostatic aperture is hollow inside and connected to a thermostatic water bath. The water in the thermostatic water bath circulates and exchanges heat with the thermostatic aperture to maintain a constant temperature of the thermostatic aperture.

[0034] The host computer is connected to the thermometer for collecting and recording temperature data; the host computer is also connected to the FTIR spectrometer for collecting spectral signals.

[0035] Furthermore, the heating device, the room-temperature blackbody, and the variable-temperature blackbody are all arranged horizontally on the electric moving platform. The electric moving platform and the optical system are arranged opposite each other, and can drive the heating device, the room-temperature blackbody, and the variable-temperature blackbody to move horizontally and vertically.

[0036] Furthermore, the variable-temperature blackbody includes a medium-temperature blackbody and a high-temperature blackbody; the heating device includes a medium-temperature sample heater and a high-temperature sample heater, which are used to heat and obtain medium-temperature samples and high-temperature samples, respectively.

[0037] Furthermore, the operating temperature of a medium-temperature blackbody is 50-450℃, and the operating temperature of a high-temperature blackbody is 400-1000℃.

[0038] Furthermore, the medium-temperature sample heater includes an iron-chromium-aluminum coil and a quartz glass heat-conducting plate, which are connected and heated. The quartz glass heat-conducting plate is used to fix the medium-temperature sample. The surface of the quartz glass heat-conducting plate is coated with a high-emissivity black paint.

[0039] Furthermore, the high-temperature sample heater includes a U-shaped silicon molybdenum rod, a metal shell, mullite refractory material, and a heat-conducting plate. The interior of the metal shell is filled with the mullite refractory material. The heat-conducting plate is located on the front side of the metal shell, and the U-shaped silicon molybdenum rod is located on the back side of the heat-conducting plate for heating the heat-conducting plate. The back side of the heat-conducting plate is connected to a temperature measuring mechanism, and the high-temperature sample is fixed on the front side of the heat-conducting plate.

[0040] Furthermore, the temperature measuring mechanisms connected to the intermediate-temperature blackbody, the normal-temperature blackbody, and the intermediate-temperature sample are all platinum resistance thermometers. The temperature measuring mechanisms connected to the high-temperature blackbody and the high-temperature sample include S-type thermocouples and containers containing ice-water mixtures. The high-temperature blackbody and the high-temperature sample are each connected to an S-type thermocouple, and the reference end of the S-type thermocouple is placed inside the container containing the ice-water mixture.

[0041] Furthermore, the heating device is connected to an electric rotary table, which can drive the heating device and the sample to rotate together.

[0042] Furthermore, both the room-temperature blackbody and the variable-temperature blackbody adopt a cavity structure, which has a cavity inside and a cone-shaped structure with a cone angle of 120° at the bottom. The cavity of the blackbody is coated with a high emissivity coating, and the emissivity of the coating is not less than 0.95 in the range of 3-14μm.

[0043] The beneficial effects of the present invention are as follows: the device of the present invention can realize convenient directional spectral emissivity measurement of materials. By setting up a medium-temperature blackbody, a high-temperature blackbody, a medium-temperature sample heater and a high-temperature sample heater, the measurement temperature can reach 1000℃, thereby realizing wide temperature range measurement. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the wide-temperature-range directional spectral emissivity measurement device in an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram showing the arrangement of the blackbody and heating device in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram illustrating the blackbody temperature stability in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of the high-temperature sample heater in an embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram illustrating the temperature stability of the sample in an embodiment of the present invention;

[0049] Figure 6 This is a schematic diagram of the normal spectral emissivity of silicon carbide at 600°C in an experiment according to an embodiment of the present invention;

[0050] Figure 7 This is a schematic diagram of the normal spectral emissivity of silicon carbide in a temperature range during an experiment according to an embodiment of the present invention. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0052] The relevant measurement principles will be explained below.

[0053] According to Planck's equation, the spectral radiance of an ideal blackbody is determined by the temperature and wavelength of the blackbody:

[0054]

[0055] Where h is Planck's constant, c is the speed of light in a vacuum, and k is the velocity of light. B It is Boltzmann's constant. Wave number, unit: cm -1 T is the temperature of the blackbody, measured in Kelvin (K). The emissivity of a practically used blackbody is less than 1. The signal actually radiated from a blackbody includes both the signal emitted by the blackbody itself and the background radiation reflected by the blackbody.

[0056]

[0057] ε bb The emissivity of a blackbody T is the signal emitted by the blackbody calculated according to formula (2-1). bb Let L(T) be the temperature of the blackbody. en T represents the effective radiation received by the blackbody from the environment. en The effective ambient temperature.

[0058] During emissivity measurement, the sample under test and the standard blackbody source are set to similar temperatures. A spectrometer is used to measure the spectral signals of the low-temperature standard blackbody, the high-temperature standard blackbody, and the sample under test, respectively. Detector drift and background radiation are eliminated by continuously measuring the zero-point blackbody cooled by liquid nitrogen. For variable-temperature blackbodies, the spectrometer measures the wavenumber. Lower signal It can be given by the following formula:

[0059]

[0060] Where ρ1 is the reflectivity of the plane mirror, ρ2 is the reflectivity of parabolic mirror 1, ρ3 is the reflectivity of parabolic mirror 2, and s is the wavenumber of the spectrometer. The spectral responsivity under L. BackgroundL is the background radiance reaching the detector at wavenumber v within the spectrometer. Detector L(T) is the spectral radiance of the detector at wavenumber v. stbb ) is the blackbody at wavenumber The actual spectral radiance under the given conditions is calculated according to formula (2-2), thus for low-temperature standard blackbodies and high-temperature standard blackbodies, we have:

[0061]

[0062]

[0063] L(T stbb1 ) is the low-temperature standard blackbody at wavenumber The actual spectral radiance under the given conditions, L(T) stbb2 ) is the high-temperature standard blackbody at wavenumber The actual spectral radiance under the following conditions;

[0064] For the sample, since it is symmetrically arranged with the standard blackbody, all three have the same measurement optical system, therefore the measurement signal of its spectrometer can be given by the following formula:

[0065]

[0066] Among them, T samp The radiance of the sample is denoted as .

[0067] Subtracting formula (2-4) from formula (2-5) yields:

[0068]

[0069] The same formula can be obtained for the sample:

[0070]

[0071] By dividing formula (2-8) and formula (2-7), we obtain:

[0072]

[0073] In formula (2-9), all terms on the left side of the equation are signals measured by the spectrometer, and the spectral radiance L(T) of the standard blackbody on the right side of the equation represents the spectral radiance of the standard blackbody. stbb2 ) and L(T stbb1 The radiance L(T) of the sample can be calculated using formula (2-2). samp ), as shown below:

[0074]

[0075] The contact temperature of the sample was obtained during the measurement process, and the spectral radiance L of the ideal blackbody at the contact temperature of the sample was calculated using Planck's equation (2-1). P (T samp Then, the radiance L(T) of the blackbody (sample) measured by the spectrometer is calculated according to formula (2-10). samp At the same time, the blackbody receives effective radiation L(T) from the environment. en Ambient temperature T en The temperature can be calculated based on that of a blackbody at room temperature, therefore L(T) can be obtained. en For the sample to be tested, we have:

[0076] L(T samp )=ε λ,T L p (T samp )+(1-ε λ,T )L(T en (2-11)

[0077] This allows us to obtain the spectral emissivity ε of the sample at temperature T. λ,T for:

[0078]

[0079] Based on the above measurement principle, this embodiment provides a wide-temperature-range directional spectral emissivity measurement device, such as... Figure 1 The system includes a room-temperature blackbody 1, a variable-temperature blackbody 2, a heating device 3, a thermometer 14, an FTIR spectrometer 5, an optical system, and a host computer 10.

[0080] The heating device 3 is used to heat the sample and is rotatable to adjust the measurement angle of the sample. A partition 4 is provided between the room temperature blackbody 1, the variable temperature blackbody 2, and the heating device 3. The room temperature blackbody 1 is connected to the blackbody constant temperature water bath 9. The water in the blackbody constant temperature water bath 9 circulates and exchanges heat with the room temperature blackbody 1 to maintain the temperature of the room temperature blackbody 1 constant. The room temperature blackbody 1, the variable temperature blackbody 2, and the heating device 3 are respectively connected to temperature measuring mechanisms for measuring the temperature of the room temperature blackbody 1, the variable temperature blackbody 2, and the heating device 3. The heating device 3 and each temperature measuring mechanism are communicatively connected to the thermometer 14. The thermometer 14 obtains the temperature of the room temperature blackbody 1, the variable temperature blackbody 2, and the heating temperature of the heating device 3 from each temperature measuring mechanism, and controls the variable temperature blackbody 2 and the heating device 3 to start or stop heating.

[0081] The optical system includes a thermostatic aperture 6 and a sealed optical path structure 7. The sealed optical path structure 7 includes an outer housing 71 and a gold-plated off-axis parabolic mirror 72 and a plane mirror 73 disposed within the outer housing 71. The outer housing 71 has an optical path inlet and an optical path outlet on its two sides, respectively. The optical path inlet corresponds to the thermostatic aperture 6, and the optical path outlet corresponds to the FTIR spectrometer 5. The thermostatic aperture 6 is hollow inside and connected to a thermostatic water bath 8. The water in the thermostatic water bath 8 circulates and exchanges heat with the thermostatic aperture 6 to maintain a constant temperature of the thermostatic aperture 6.

[0082] The host computer 10 is communicatively connected to the thermometer 14 for collecting and recording temperature data; the host computer 10 is also communicatively connected to the FTIR spectrometer 5 for collecting spectral signals. Before testing, the corresponding options are set on the host computer to enable the host computer to automatically test and collect spectral signals and temperature information, and automatically generate and save spectral emissivity values ​​according to the calculation formula.

[0083] First, the spectral signal of the room-temperature blackbody 1 is measured to calibrate the FTIR spectrometer 5. Then, the variable-temperature blackbody 2 is heated to the target measurement temperature and its spectral signal is measured. Finally, the sample is heated to the target measurement temperature using the heating device 3 and its spectral signal is measured.

[0084] When measuring spectral signals, a room-temperature blackbody 1, a variable-temperature blackbody 2, or a sample is positioned relative to the optical system. The target signal first passes through a constant-temperature aperture, then enters a sealed optical path structure. After refraction by a gold-plated off-axis parabolic mirror and a plane mirror, it reaches the FTIR spectrometer, where the spectral signal is measured. This setup ensures that the optical path is identical when measuring the blackbody and the sample, guaranteeing a consistent measurement environment and avoiding errors caused by different background conditions.

[0085] In this embodiment, as Figure 2 As shown, the heating device 3, the room temperature blackbody 1, and the variable temperature blackbody 2 are all arranged horizontally on the electric moving platform 11. The electric moving platform 11 is arranged opposite to the optical system and can drive the heating device 3, the room temperature blackbody 1, and the variable temperature blackbody 2 to move horizontally and move up and down.

[0086] The electric moving platform can drive the heating device 3 (including the sample), the room temperature blackbody 1, and the variable temperature blackbody 2 to move horizontally and vertically, thereby adjusting the horizontal position and height of the room temperature blackbody 1, the variable temperature blackbody 2, and the sample, so that the room temperature blackbody 1, the variable temperature blackbody 2, or the sample can accurately correspond with the optical system to complete the measurement.

[0087] In this embodiment, the variable-temperature blackbody 2 includes a medium-temperature blackbody 21 and a high-temperature blackbody 22; the heating device 3 includes a medium-temperature sample heater 31 and a high-temperature sample heater 32, which are used to heat and obtain a medium-temperature sample 16 and a high-temperature sample 17, respectively. By selecting either the medium-temperature sample 16 or the high-temperature sample 17 and either the medium-temperature blackbody 21 or the high-temperature blackbody 22 for measurement, spectral signal measurements within different temperature ranges can be achieved.

[0088] Furthermore, in this embodiment, the operating temperature of the intermediate-temperature blackbody is 50-450℃, and the operating temperature of the high-temperature blackbody is 400-1000℃. When the measurement temperature is between 400-450℃, either the intermediate-temperature blackbody or the high-temperature blackbody can be used.

[0089] Furthermore, in this embodiment, the medium-temperature sample heater includes an iron-chromium-aluminum coil and a quartz glass heat-conducting plate. The iron-chromium-aluminum coil and the quartz glass heat-conducting plate are connected and heated. The quartz glass heat-conducting plate is used to fix the medium-temperature sample. The surface of the quartz glass heat-conducting plate is coated with high-emissivity black paint to increase its thermal conductivity.

[0090] Furthermore, in this embodiment, as Figure 4 As shown, the high-temperature sample heater 32 includes a U-shaped silicon molybdenum rod 324, a metal shell 321, mullite refractory material 322, and a heat-conducting plate 323. The interior of the metal shell 321 is filled with the mullite refractory material 322. The heat-conducting plate 323 is located on the front side of the metal shell 321, and the U-shaped silicon molybdenum rod 324 is located on the back side of the heat-conducting plate 323 for heating the heat-conducting plate 323. One end of the S-type thermocouple 14 of the temperature measuring mechanism connected to the high-temperature sample heater 32 is located on the back side of the heat-conducting plate 323, and the high-temperature sample 17 is fixed on the front side of the heat-conducting plate 323. The heat-conducting plate 323 is a quartz heat-conducting plate.

[0091] The U-shaped silicon molybdenum rod can be heated to 1800℃ in the atmosphere and is stable and not easily oxidized. The heater is filled with mullite refractory material, which can play a role in heat preservation and reduce heat loss.

[0092] Furthermore, in this embodiment, the temperature measuring mechanisms connected to the intermediate-temperature blackbody 21, the room-temperature blackbody 1, and the intermediate-temperature sample 16 are all platinum resistance thermometers 12. The temperature measuring mechanisms connected to the high-temperature blackbody 22 and the high-temperature sample 17 include an S-type thermocouple 14 and a container 15 containing an ice-water mixture. The high-temperature blackbody 22 and the high-temperature sample 17 are each connected to an S-type thermocouple 14, and the reference end of the S-type thermocouple 14 is placed inside the container 15 containing the ice-water mixture. The measurement accuracy of the platinum resistance thermometer is 0.05℃, and the measurement accuracy of the S-type thermocouple in conjunction with the ice-water mixture is 0.5℃.

[0093] Furthermore, the heating device 3 is connected to the electric rotary table 13, which can drive the heating device 3 and the sample to rotate together. The electric rotary table allows the heating device 3 and the sample to rotate together, adjusting the angle of the sample towards the optical system, thereby adjusting the measurement angle of the sample. The rotatable angle range of the electric rotary table is 0-60°.

[0094] Specifically, the positioning accuracy of the electric moving stage 11 is better than 0.05 mm, and the repeatability of the electric rotating stage 13 is better than 0.1°.

[0095] In this embodiment, both the room-temperature blackbody and the variable-temperature blackbody adopt a cavity structure, which has an internal cavity and a conical structure with a cone angle of 120° at the bottom. The cavity of the blackbody is coated with a JSC-3 high emissivity coating. The emissivity of the coating is not less than 0.95 in the range of 3-14μm. The emissivity of the blackbody cavity calculated by simulation based on the Monte Carlo algorithm is higher than 0.995.

[0096] The following provides further explanation of each part of the above-mentioned device.

[0097] As a standard radiation source, the performance of a blackbody directly determines the reliability of the emissivity measurement device. The radiation sources in this embodiment include a room-temperature blackbody (RTBB) and a variable-temperature blackbody (VTBB). The room-temperature blackbody is connected to a constant-temperature water bath to maintain a constant temperature and is used to calibrate the spectrometer signal. Due to different operating temperature ranges, the variable-temperature blackbody in this embodiment is further divided into a middle-temperature blackbody (MTBB) and a high-temperature blackbody (HTBB). Table 1 shows the specific parameter indicators of the three types of blackbody in this embodiment.

[0098] Table 1

[0099]

[0100]

[0101] It should be noted that the thermometer in this embodiment uses a high-precision PID temperature controller, which can achieve temperature control over a wide temperature range. The thermometer measures and records the temperature performance of three blackbodies at different temperatures. Figure 3Images (a) and (b) show the temperature performance of the mid-temperature blackbody at 50°C, 200°C, and 400°C, and the temperature performance of the high-temperature blackbody at 400°C, 700°C, and 1000°C, respectively, measured over 15 minutes after temperature stabilization. The data shows that the stability of both the mid-temperature and high-temperature blackbody in this embodiment is better than 0.5°C within their operating temperature range, ensuring the consistency of the blackbody radiation signal during the measurement process. Furthermore, the room-temperature blackbody (RT) is connected to a constant-temperature water bath, set to 21°C, by... Figure 3 As shown in (a), the temperature stability of a blackbody at room temperature is better than that at 0.1℃ at 21℃.

[0102] It should be noted that the heating device in this embodiment includes a medium-temperature sample heater (MTSH) and a high-temperature sample heater (HTSH), and the operating temperatures of the medium-temperature sample heater and the high-temperature sample heater are room temperature - 450℃ and 400-1000℃, respectively.

[0103] In this embodiment, the heating temperature of the heating device is also controlled using a thermometer. In this embodiment, the thermometer measures and records the temperature of the medium-temperature sample at 50℃, 200℃, and 400℃. Figure 5 (as shown in (a)) and high-temperature samples at 400℃, 700℃, and 1000℃ (e.g.) Figure 5 The temperature performance within 15 minutes after temperature stabilization is shown in (b) below. Figure 5 As shown, the temperature stability of the sample in the medium temperature range is better than 0.5℃. Due to the influence of atmospheric convection on the sample temperature, the temperature fluctuation of the sample increases at high temperatures, but the overall temperature stability is better than 1℃.

[0104] It should be noted that the Fourier Transform Infrared Spectrometer (FTIR) measures spectral signals by using its built-in DLaTGS detector, a detachable liquid nitrogen-cooled MCT detector, and an InSb detector. As shown in Table 2, the three detectors are used to detect sample signals in different wavelength bands and temperature ranges.

[0105] Table 2

[0106]

[0107] It should be noted that at lower temperatures, the DLaTGS detector measures poor signals in the short-wave 3-5μm and 5-8μm bands (affected by atmospheric absorption). Therefore, below 400℃, the DLaTGS detector only measures spectral data in the 8-14μm band.

[0108] The effectiveness of the device in this embodiment is verified through experiments.

[0109] Although there is currently no standard material for comparing emissivity values ​​measured by different devices, silicon carbide exhibits high emissivity above 500℃ and stable emissivity under repeated atmospheric heating. Some researchers believe that silicon carbide could be used as a potential reference material to verify the reliability of devices. Therefore, a silicon carbide sample measuring 30mm*30mm*2.2mm was prepared, and its spectral emissivity in the 3-14μm wavelength range at 600℃ was measured. Figure 6 Data shows that the spectral emissivity of silicon carbide is approximately 0.9 in the short-wavelength range of 3-6 μm, while the fluctuation in spectral emissivity near 4 μm is due to the absorption of atmospheric carbon dioxide. It then increases continuously in the 6-10.2 μm range, reaching a maximum emissivity of 0.98 at the Christiansen wavelength of 10.2 μm. Afterward, the spectral emissivity decreases sharply to 0.15 at 12 μm, and finally rises to around 0.6 at 14 μm. The spectral emissivity measurements of silicon carbide at high temperatures are consistent with those of Cagran, Claus P., et al.

[19] The silicon carbide emissivity characteristics measured in the literature show good agreement, verifying the reliability of the device. Figure 7 The spectral emissivity of silicon carbide in the temperature range of 25℃-400℃ was shown. The spectral emissivity of silicon carbide in the mid-temperature range was basically consistent, showing a characteristic that is almost independent of temperature, which is consistent with the spectral emissivity law of silicon carbide materials in this temperature range.

[0110] Furthermore, the uncertainties of the apparatus mainly originate from the blackbody radiation source, the sample, background noise, and measurement repeatability. The uncertainty of the blackbody radiation source primarily stems from the cavity emissivity, temperature measurement accuracy, temperature stability, and uniformity. The sample uncertainty mainly arises from the sample temperature measurement accuracy, temperature stability, and uniformity. The uncertainty of the background noise arises from changes in background temperature. Since the temperature performance of the blackbody and the sample differs at different temperatures, uncertainty analyses of the spectral emissivity of silicon carbide at 10 μm at 50℃, 500℃, and 1000℃ are presented. Taking 50℃ as an example, Table 3 shows that the uncertainties for measuring the spectral emissivity of silicon carbide at 5 μm and 10 μm at 50℃ are 1.849% and 1.529%, respectively. The uncertainty in measuring the spectral emissivity of silicon carbide at 500 °C is 1.427% (5 μm) and 0.885% (10 μm), and the uncertainty at 1000 °C is 1.078% (5 μm) and 0.747% (10 μm).

[0111] Table 3

[0112]

[0113]

[0114] In summary, the wide-temperature-range directional spectral emissivity measurement device provided in this embodiment can measure the directional spectral emissivity of solid materials within a temperature range of room temperature to 1000℃, with a wavelength range of 3-14μm and a measurement angle adjustment range of 0-60°. The reliability of the device was verified by measuring the spectral emissivity of silicon carbide at high temperatures. Finally, the uncertainty composition of the spectral emissivity measurements at different wavelengths (5μm and 10μm) at 50℃, 500℃, and 1000℃ was analyzed, revealing that the spectral emissivity of the device in this embodiment is better than 3% within its measurement temperature range.

[0115] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. A wide-temperature-range directional spectral emissivity measurement device, characterized in that, This includes a room-temperature blackbody, a variable-temperature blackbody, a heating device, a temperature measuring instrument, an FTIR spectrometer, an optical system, and a host computer; The heating device is used to heat the sample and is rotatable to adjust the measurement angle of the sample. A partition is provided between the room-temperature blackbody, the variable-temperature blackbody, and the heating device. The room-temperature blackbody is connected to a constant-temperature water bath, and the water in the constant-temperature water bath circulates and exchanges heat with the room-temperature blackbody to maintain a constant temperature of the room-temperature blackbody. The room-temperature blackbody, the variable-temperature blackbody, and the heating device are each connected to a temperature measuring mechanism for measuring the temperature of the room-temperature blackbody, the variable-temperature blackbody, and the heating device. The heating device and each temperature measuring mechanism are communicatively connected to a thermometer. The thermometer obtains the temperature of the room-temperature blackbody, the variable-temperature blackbody, and the heating temperature of the heating device from each temperature measuring mechanism, and controls the variable-temperature blackbody and the heating device to start or stop heating. The optical system includes a thermostatic aperture and a sealed optical path structure. The sealed optical path structure includes an outer shell and a gold-plated off-axis parabolic mirror and a plane mirror disposed within the outer shell. The outer shell has an optical path inlet and an optical path outlet on its two sides, respectively. The optical path inlet corresponds to the thermostatic aperture, and the optical path outlet corresponds to the FTIR spectrometer. The thermostatic aperture is hollow inside and connected to a thermostatic water bath. The water in the thermostatic water bath circulates and exchanges heat with the thermostatic aperture to maintain a constant temperature of the thermostatic aperture. The host computer is connected to the thermometer for collecting and recording temperature data; the host computer is also connected to the FTIR spectrometer for collecting spectral signals.

2. The wide-temperature-range directional spectral emissivity measuring device according to claim 1, characterized in that, The heating device, the room-temperature blackbody, and the variable-temperature blackbody are all arranged horizontally on the electric moving platform. The electric moving platform and the optical system are arranged opposite each other, and can drive the heating device, the room-temperature blackbody, and the variable-temperature blackbody to move horizontally and vertically.

3. The wide-temperature-range directional spectral emissivity measuring device according to claim 1 or 2, characterized in that, The variable-temperature blackbody includes a medium-temperature blackbody and a high-temperature blackbody; the heating device includes a medium-temperature sample heater and a high-temperature sample heater, which are used to heat and obtain medium-temperature samples and high-temperature samples, respectively.

4. The wide-temperature-range directional spectral emissivity measuring device according to claim 3, characterized in that, The operating temperature of a medium-temperature blackbody is 50-450℃, while that of a high-temperature blackbody is 400-1000℃.

5. The wide-temperature-range directional spectral emissivity measuring device according to claim 3, characterized in that, The medium-temperature sample heater includes an iron-chromium-aluminum coil and a quartz glass heat-conducting plate. The iron-chromium-aluminum coil and the quartz glass heat-conducting plate are connected and heated. The quartz glass heat-conducting plate is used to fix the medium-temperature sample. The surface of the quartz glass heat-conducting plate is coated with high-emissivity black paint.

6. The wide-temperature-range directional spectral emissivity measuring device according to claim 3, characterized in that, The high-temperature sample heater includes a U-shaped silicon molybdenum rod, a metal shell, mullite refractory material, and a heat-conducting plate. The interior of the metal shell is filled with the mullite refractory material. The heat-conducting plate is located on the front side of the metal shell, and the U-shaped silicon molybdenum rod is located on the back side of the heat-conducting plate for heating the heat-conducting plate. The back side of the heat-conducting plate is connected to a temperature measuring mechanism, and the high-temperature sample is fixed on the front side of the heat-conducting plate.

7. The wide-temperature-range directional spectral emissivity measuring device according to claim 3, characterized in that, The temperature measuring mechanisms connected to the intermediate-temperature blackbody, the normal-temperature blackbody, and the intermediate-temperature sample are all platinum resistance thermometers. The temperature measuring mechanisms connected to the high-temperature blackbody and the high-temperature sample include S-type thermocouples and containers containing ice-water mixtures. The high-temperature blackbody and the high-temperature sample are each connected to an S-type thermocouple, and the reference end of the S-type thermocouple is placed inside the container containing the ice-water mixture.

8. The wide-temperature-range directional spectral emissivity measuring device according to claim 1, characterized in that, The heating device is connected to an electric rotary table, which can drive the heating device and the sample to rotate together.

9. The wide-temperature-range directional spectral emissivity measuring device according to claim 1 or 2, characterized in that, Both the room-temperature blackbody and the variable-temperature blackbody adopt a cavity structure, which has an internal cavity and a cone-shaped structure with a cone angle of 120° at the bottom. The cavity of the blackbody is coated with a high emissivity coating, and the emissivity of the coating is not less than 0.95 in the range of 3-14μm.

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