Method and system for determining peak temperature and time based on neutron irradiated silicon carbide absorption band blue shift

Abstract

This invention provides a method for determining peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation. The method includes the following steps: S1, selecting and processing a silicon carbide crystal, specifically including irradiation, slicing, annealing, and polishing; S2, determining the absorption band edge of the silicon carbide; S3, determining the relationship between the annealing temperature and the absorption band edge; S4, establishing a duration evaluation model; S5, measuring the peak temperature and the duration of the peak temperature using the silicon carbide crystal. This invention utilizes the blue shift of the absorption band edge to evaluate the peak temperature and its duration, filling the gap in existing technologies that cannot measure the duration of peak temperature. Furthermore, the temperature sensing crystal exhibits stable physicochemical properties, is not prone to chemical reactions at high temperatures, has a stable phase, and provides accurate measurement results, making it suitable for temperature testing in various high-temperature scenarios.

Description

Technical Field

[0001] This invention relates to the field of temperature and duration measurement, specifically to a method and system for determining peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation. Background Technology

[0002] Obtaining the peak temperature and duration of peak temperature for critical components in high-temperature environments is crucial for equipment design and performance improvement, providing reliable technical support for material selection and geometric design of critical components. Existing temperature measurement technologies, including thermocouples, fiber optic thermometry, temperature-indicating paint, and fluorescent thermometry, play an important role in routine environmental temperature testing. However, temperature testing of critical components subjected to extreme and harsh environments such as high-speed airflow, strong heat flux, high rotational speed, and ultra-high temperatures, such as turbine blades in aero-engines, presents significant challenges. Applying conventional temperature measurement technologies to these scenarios still faces considerable difficulties.

[0003] Crystal thermometry provides a new approach for temperature testing of critical components under extreme environments. National invention patents 101598606A ("A Temperature Measurement Method Using Neutron-Irradiated Silicon Carbide Crystal as Sensor"), 109030544B ("A Maximum Temperature Measurement Method Based on Changes in Microcrystalline Lattice Parameters"), and CN114184303A ("A Temperature Measurement Method and System Based on the Half-Maximum Width of Silicon Carbide Raman Scattering") respectively select cubic and hexagonal silicon carbide. They obtain parameters such as the position of diffraction peaks or interplanar spacing using X-ray diffraction, or establish a mapping between the peak temperature and the measured physical quantity by observing the change in the full width at half maximum (FWHM) of the Raman characteristic peak with annealing temperature, thus forming a temperature measurement criterion. The upper limits for testing reach 1450℃ and 1750℃, respectively. Both peak temperature and duration can affect the aforementioned physical quantities, with peak temperature having a primary influence. Anastasia Thomas et al. from LG Tech-Link Global proposed a method for high-temperature annealing of 3C-silicon carbide under neutron irradiation. The method describes the relationship between the diffraction peak position 2θ of a certain crystal plane and the peak temperature and duration, given the known peak temperature and duration.

[0004] 2θ = A + B × T + C × lgt

[0005] Where A, B, and C are constants, T is the peak temperature, and t is the duration of the peak temperature.

[0006] Yutai Katoh et al. from Oak Ridge National Laboratory in the United States proposed a similar relationship:

[0007]

[0008] This represents the volumetric swelling rate of the crystal after irradiation. The volumetric swelling rate is the volumetric swelling rate at a peak temperature T for a duration of t. This represents the change in swelling rate. Peak temperature has the primary effect on the measured physical quantity, while the duration of the duration has a significantly reduced effect on the physical quantity, decreasing to an order of magnitude compared to peak temperature.

[0009] As can be seen from the above-disclosed technologies, the above methods can be used to determine the peak temperature, but it is difficult to quantify the impact of the duration of the peak temperature. Moreover, the evaluation method for the peak temperature is also quite complex and cannot be adapted to various scenarios. Summary of the Invention

[0010] Based on the shortcomings of the existing technology, the purpose of this invention is to overcome the limitation that existing crystal temperature measurement technology cannot simultaneously obtain peak temperature and peak temperature duration. It provides a method for evaluating peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation. This method can evaluate peak temperature and peak temperature duration in complex high-temperature environments ranging from 1000-1650℃. Unlike existing technologies that select the position of the crystal diffraction peak as the measurement parameter, this method selects the absorption band edge as both the measurement parameter and the model input parameter. The absorption band edge response time is short, the test data is stable, the duration reading model is simple to construct, the temperature measurement range is wide, and the temperature measurement speed is fast, ensuring both efficiency and accuracy in measuring peak temperature and peak temperature duration.

[0011] Specifically, the present invention provides a method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation, which includes the following steps:

[0012] S1. Selecting and processing silicon carbide crystals: The specific processing of silicon carbide crystals includes irradiation, slicing, annealing, and polishing.

[0013] S2. Determine the absorption band edge of silicon carbide: Collect the absorption spectrum of silicon carbide crystal by spectrophotometer, and determine the absorption band edge of silicon carbide based on the collected absorption spectrum.

[0014] S3. Determine the relationship between annealing temperature and absorption band edge: Measure the absorption band edge λ of silicon carbide crystals with a fixed annealing time at all annealing temperatures. 1-n And establish a one-to-one correspondence between the absorption band edge and the annealing temperature, that is, the absorption band edge λ. 1-1 Corresponding annealing temperature T C-1 Absorption band edge λ 1-2 Corresponding annealing temperature T C-2 Absorption band edge λ 1-3 Corresponding annealing temperature T C-3 ...absorption band edge λ 1-n Corresponding annealing temperature TC-n As the annealing temperature increases, the absorption band edge shifts towards shorter wavelengths in the blue direction;

[0015] S4. Establish a duration evaluation model, which includes the following sub-steps:

[0016] S41. Establish the relationship curve between the absorption band edge and the annealing temperature and duration: Determine the annealing temperature T. C-n Absorption band edge λ of silicon carbide crystals with different annealing times t 2-n , with λ 2-n Plot the annealing temperature T at a fixed annealing temperature with t as the x-axis. C-n The absorption band edge λ below 2-n The curve showing how the annealing time t changes;

[0017] S42. Based on the curve data distribution from step S41, establish λ. 2-n =f(t) is the polynomial isothermal temperature calibration equation, i.e., the duration evaluation model. Based on the duration evaluation model, the absorption band edge λ is input. 2-n The annealing time t can be obtained by calculating the value. The specific evaluation model for the time is as follows:

[0018] λ 2-n =f(t)=a+b(t);

[0019] Where a and b are the fitting coefficients;

[0020] S5. Measure the peak temperature and the duration of the peak temperature using a silicon carbide crystal, specifically including the following sub-steps:

[0021] S51. Determine the peak temperature: Fix the silicon carbide crystal at the target temperature position. After the high-temperature process is completed, measure the absorption band edge λ3 of the silicon carbide crystal, and compare the measured absorption band edge λ3 with the absorption band edge λ of silicon carbide crystals annealed for 2 minutes at all annealing temperatures. 1-n By comparing the measured absorption band edge λ3, the range of the measured absorption band edge λ3 is determined, and the high temperature peak temperature corresponding to that range is obtained based on the range of the measured absorption band edge λ3.

[0022] S52. Determine the duration of peak temperature: Based on the determined peak temperature, determine the fitting coefficient of the duration evaluation model, input the measured absorption band edge λ3 as the input value into the duration evaluation model and output the calculation result. The output value within the threshold range is taken as the effective value, which is the duration of peak temperature.

[0023] Preferably, the silicon carbide crystal in step S1 is a nitrogen-doped 6H-silicon carbide crystal.

[0024] Preferably, step S1 specifically includes the following sub-steps:

[0025] S11. Selection of silicon carbide crystal: Select nitrogen-doped 6H-silicon carbide crystal with a nitrogen doping concentration ≥ 10. 19 / cm 3 ;

[0026] S12. Irradiate the silicon carbide crystal: Irradiate the silicon carbide crystal obtained in step S11 with neutrons, the irradiation dose being greater than or equal to 1.0 × 10⁻⁶. 21 Irradiation temperature less than or equal to 100℃, to obtain irradiated silicon carbide crystals;

[0027] S13. Segment the silicon carbide crystal: Segment the silicon carbide crystal obtained in step S12 and process it into square crystals with a side length of 5 mm-10 mm.

[0028] S14. Annealing the silicon carbide crystal: Annealing the silicon carbide crystal obtained in step S13 at different temperatures.

[0029] S15. Polishing the silicon carbide crystal: Polish the silicon carbide crystal after annealing in step S14.

[0030] Preferably, in step S12, the silicon carbide crystal obtained in step S11 is irradiated with neutrons using a full-energy spectrum.

[0031] Preferably, the polishing process in step S15 includes mechanical polishing and chemical polishing to remove the surface oxide layer.

[0032] Preferably, the spectrophotometer in step S2 is equipped with both deuterium and xenon light sources, with a spectral resolution range of 0.5-2 nm, a set absorption spectrum wavelength range of 300-1500 nm, and baseline calibration of the absorption spectrum, and the number of times the absorption spectrum of silicon carbide crystal is collected is greater than or equal to 5.

[0033] Preferably, in step S51, the value in the range of 1000-1650℃ is the effective peak temperature. In step S52, the absorption band edge λ3 is input into the model, and the output value in the range of 2-150min is taken as the effective output value, i.e., the duration of the peak temperature.

[0034] Preferably, in step S51, the interval of the measured absorption band edge λ3 is determined, and the high-temperature peak temperature corresponding to the interval is obtained based on the measured absorption band edge λ3 as follows: when λ 1-n >λ3>λ 1-(n+1) When the absorption band edge λ3 is reached, the high-temperature peak temperature corresponding to it is determined to be T. C-n .

[0035] Preferably, in step S14, the annealing temperature range is 1000-1650℃, the annealing temperature gradient increases at 50℃ intervals, and the annealing temperature T is recorded.C In step S3, the annealing time is 2 minutes.

[0036] Preferably, a system for determining peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation includes a module for determining the relationship between the absorption band edge and annealing temperature, a duration evaluation model establishment module, a peak temperature calculation module, and a peak temperature duration calculation module. The module for determining the relationship between the absorption band edge and annealing temperature is used to determine the relationship between different annealing temperatures and the absorption band edge under a certain annealing duration. The duration evaluation model establishment module is used to establish a duration evaluation model based on the fitting curve between the annealing temperature duration and the absorption band edge at a certain annealing temperature. Using the absorption band edge as the input of the duration evaluation model, the model can output the annealing duration at that annealing temperature. The peak temperature calculation module is used to determine the peak temperature based on the absorption band edge measured when the thermometric silicon carbide crystal is working. The peak temperature duration calculation module, based on the determined peak temperature, takes the measured absorption band edge as input and outputs an effective value within a threshold range as the output value, which is the peak temperature duration.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) The method for evaluating peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation provided by this invention can accurately evaluate the peak temperature and the duration of the peak temperature by utilizing the blue shift of the absorption band edge, providing a new approach for measuring peak temperature, especially the duration of the peak temperature, and making up for the shortcomings of the prior art. The measurement method described in this invention can evaluate the peak temperature and duration within 2-150 minutes of high-temperature operation. The measured peak temperature and duration of the peak temperature are almost identical to the actual annealing temperature and duration, ensuring the accuracy of the measurement results.

[0039] (2) The temperature sensing crystal in this invention has stable physical and chemical properties, is not prone to chemical reaction at high temperatures, and has a stable phase. It is suitable for temperature testing in high-temperature scenarios with multiple atmospheres. It has important application prospects in high-temperature testing of working systems containing turbines and internal combustion engines in many closed working systems, such as aircraft, ships, automobiles, and power equipment and facilities. It has strong applicability and can be applied to various temperature measurement scenarios. Furthermore, selecting the absorption band edge as the input parameter can ensure the accuracy of the peak temperature and the duration of the peak temperature.

[0040] (3) The present invention selects the absorption band edge of silicon carbide crystal for temperature and duration evaluation, which can ensure the accuracy of the measurement results. The absorption band edge can reflect the energy level and concentration distribution of irradiation defects, thus accurately ensuring the peak temperature and peak temperature duration. In addition, the absorption band edge also has the advantages of short response time and stable test data, and will not interfere with the predicted peak temperature and peak temperature duration.

[0041] (4) The peak temperature constructed by this invention has a long duration, the calculation model is simple and does not require complex model parameters, the prepared silicon carbide crystal has a wide temperature measurement range and fast temperature measurement speed, and can be applied to a variety of application fields such as aviation. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the overall method flow of the present invention;

[0043] Figure 2 This is a schematic diagram showing the light transmittance of 6H-silicon carbide crystals under neutron irradiation at different annealing temperatures in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the edge distribution of the 6H-silicon carbide absorption band after annealing at 1000-1650℃ for 2 min in an embodiment of the present invention.

[0045] Figure 4 This is a schematic diagram showing the change of the 6H-silicon carbide absorption band edge with annealing time at different annealing temperatures in an embodiment of the present invention;

[0046] Figure 5 Different annealing temperatures T in the embodiments of the present invention C-n Lower absorption band edge λ 2-n Fit λ to the duration of peak temperature t 2-n A schematic diagram of the curve data of the multinomial distribution of f(t);

[0047] Figure 6 λ is the annealing temperature in some embodiments of the present invention. 2-n A schematic diagram of the fitted equation for f(t);

[0048] Figure 7 This is a system block diagram of the present invention; Detailed Implementation

[0049] The embodiments of the present invention will now be described with reference to the accompanying drawings and specific application examples.

[0050] like Figure 1 As shown, this invention provides a method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation, which includes the following steps:

[0051] S1. Selecting and processing silicon carbide crystals: The specific processing of silicon carbide crystals includes irradiation, slicing, annealing, and polishing.

[0052] In practical applications, step S1 specifically includes the following sub-steps:

[0053] S11. Selection of silicon carbide crystal: Select nitrogen-doped 6H-silicon carbide crystal, with a nitrogen doping concentration ≥ 10. 19 / cm 3 .

[0054] S12. Irradiation of silicon carbide crystal: The silicon carbide crystal obtained in step S11 is irradiated with neutrons using a full-energy spectral neutron radiation method, with an irradiation dose of not less than 1.0 × 10⁻⁶. 21 Irradiation temperature less than or equal to 100℃ is used to obtain irradiated silicon carbide crystals.

[0055] S13. Segment the silicon carbide crystal: Segment the silicon carbide crystal obtained in step S12 into square crystals with a side length of 5 mm to 10 mm.

[0056] S14. Annealing the silicon carbide crystal: The silicon carbide crystal obtained in step S13 is annealed at different temperatures, ranging from 1000 to 1650℃, with an increasing temperature gradient at 50℃ intervals. The annealing temperature T for each annealing is recorded. C .

[0057] In this step, the interval between adjacent annealing temperatures is 50℃, meaning that the accuracy of this method in evaluating high-temperature temperatures is ±50℃.

[0058] S15. Polishing the silicon carbide crystal: Perform mechanical and chemical polishing on the silicon carbide crystal after annealing in step S14 to remove the surface oxide layer, avoid the oxide layer from affecting the performance of the silicon carbide crystal, and ensure the accuracy of silicon carbide crystal measurement.

[0059] S2. Determine the absorption band edge of the silicon carbide crystal: Set the absorption spectrum wavelength range to 300-1500 nm and perform baseline calibration on the absorption spectrum. Acquire the absorption spectrum of the silicon carbide crystal using a spectrophotometer, and determine the absorption band edge of the silicon carbide based on the acquired absorption spectrum. The spectrophotometer is equipped with both deuterium and xenon light sources, with a spectral range of 300-1500 nm and a spectral resolution range of 0.5-2 nm. To ensure measurement accuracy, the absorption spectrum of the silicon carbide crystal is acquired at least five times.

[0060] S3. Determine the relationship between annealing temperature and absorption band edge: Measure the absorption band edge λ of silicon carbide crystals annealed for 2 minutes at all annealing temperatures. 1-n And establish a one-to-one correspondence between the absorption band edge and the annealing temperature, that is, the absorption band edge λ. 1-1 Corresponding annealing temperature T C-1 Absorption band edge λ 1-2 Corresponding annealing temperature T C-2 Absorption band edge λ 1-3 Corresponding annealing temperature TC-3 ...absorption band edge λ 1-n Corresponding annealing temperature T C-n As the annealing temperature increases, the absorption band edge shifts towards shorter wavelengths in a blue shift. Here, n represents the number of annealing temperatures, typically with a 50°C interval between two annealing temperatures. With a fixed annealing time, each annealing temperature corresponds to one absorption band edge.

[0061] In this step, the crystal absorption band edge with an annealing time of 2 minutes is used as the annealing temperature evaluation standard. The basis is that when annealing is performed at temperatures above 1000℃, the response time of blue shift of the crystal absorption band edge is less than 2 minutes.

[0062] For example, a fixed annealing temperature T C The absorption band edge of silicon carbide crystals exhibits a continuous blue shift with increasing annealing time. When the annealing temperature range is 1000-1650℃, with annealing temperature intervals of 50℃, and within an annealing time range of 2-150 min, the absorption band edge of the silicon carbide crystal shows a continuous blue shift. C -50℃, T C T C At three adjacent annealing temperatures of +50℃, the absorption band edges of the crystal do not overlap.

[0063] In summary, during the actual implementation process, the annealing temperature must be greater than 1000℃. Therefore, the crystal absorption band edge with an annealing time of 2 minutes is selected as the annealing temperature evaluation standard, which can not only meet the requirements of the annealing temperature interval, but also shorten the test time as much as possible.

[0064] S4. Establish a duration evaluation model, which includes the following sub-steps:

[0065] S41. Establish the relationship curve between the absorption band edge and the annealing temperature and duration. The specific process is as follows: Measure the annealing temperature T. C-n Absorption band edge λ of silicon carbide crystals with different annealing times t 2-n , with λ 2-n Plot the annealing temperature T at a fixed annealing temperature with t as the x-axis. C-n The absorption band edge λ below 2-n A curve showing the change in annealing time t; where the annealing temperature T is... C-n The absorption band edge λ of the silicon carbide crystal annealed for 2 minutes in step S3 1-n They correspond to each other, that is, the absorption band edge is λ. 1-n The corresponding annealing temperature.

[0066] S42. Based on the curve data distribution from step S41, establish λ. 2-n =f(t) is the polynomial isothermal temperature calibration equation, i.e., the duration evaluation model. Based on the duration evaluation model, the absorption band edge λ is input. 2-nThe annealing time t can be obtained by calculating the value. The specific evaluation model for the time is as follows:

[0067] λ 2-n =f(t)=a+b(t);

[0068] Where a and b are the fitting coefficients;

[0069] In the actual temperature measurement process, the absorption band edge λ is measured. 2-n The values ​​are used as input to the model, and the model is solved. Output values ​​within the threshold range are considered valid values, which represent the actual duration of the peak temperature measured. In this invention, output values ​​within the range of 2-150 minutes are considered valid and thus represent the peak temperature duration. In practice, this duration assessment model is embedded in application software to automatically output the peak temperature duration.

[0070] S5. Measure the peak temperature and the duration of the peak temperature using a silicon carbide crystal, specifically including the following sub-steps:

[0071] S51. Determine the peak temperature: Fix the silicon carbide crystal at the target temperature position. After the high-temperature process is completed, measure the absorption band edge λ3 of the silicon carbide crystal in real time using the method in step S2. Compare the measured absorption band edge λ3 with the absorption band edge λ of silicon carbide crystals annealed for 2 minutes at all annealing temperatures. 1-n By comparing the measured absorption band edge λ3, the range of the measured absorption band edge λ3 is determined, and the corresponding high-temperature peak temperature is obtained based on this range; for example, when λ 1-n >λ3>λ 1-(n+1) When the absorption band edge λ3 is reached, the high-temperature peak temperature corresponding to it is determined to be T. C-n .

[0072] In this step, according to the test results and theoretical analysis, the measured absorption band edge λ3 range must be between the absorption band edge of the unirradiated silicon carbide crystal and the absorption band edge of the irradiated silicon carbide crystal. Annealing at different temperatures can decompose the space of this absorption band edge into n consecutive intervals. The measured absorption band edge λ3 must be within one of these intervals, that is, the measured absorption band edge λ3 must correspond to an annealing temperature.

[0073] S52. Determine the duration of peak temperature: Based on the determined peak temperature, determine the fitting coefficient of the duration evaluation model. After obtaining the required fitting coefficient, input the measured absorption band edge λ3 as the input value into the duration evaluation model and output the calculated value. The output value within the threshold range is taken as the effective value, which is the duration of peak temperature.

[0074] Based on the above method, the present invention can also provide a system for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation, such as... Figure 7 As shown, it includes a module 1 for determining the relationship between the absorption band edge and the annealing temperature, a module 2 for establishing a duration evaluation model, a module 3 for calculating the peak temperature, and a module 4 for calculating the duration of the peak temperature. The module 1 for determining the relationship between the absorption band edge and the annealing temperature is used to determine the relationship between different annealing temperatures and the absorption band edge under a certain annealing time. The module 2 for establishing a duration evaluation model is used to establish a duration evaluation model based on the fitting curve between the annealing temperature duration and the absorption band edge under a certain annealing temperature. Using the absorption band edge as the input of the duration evaluation model, it can output the annealing time at that annealing temperature. The module 3 for calculating the peak temperature is used to determine the peak temperature based on the absorption band edge measured when the temperature-measuring silicon carbide crystal is working. The module 4 for calculating the duration of the peak temperature is based on the determined peak temperature, takes the measured absorption band edge as input, and outputs an effective value within the threshold range as the output value. This output value is the duration of the peak temperature. Specific Implementation

[0076] This embodiment describes the method of the present invention in detail by measuring the peak temperature of an aero-engine and the duration of the peak temperature.

[0077] In high-temperature testing of aero-engines, existing commonly used temperature measurement methods, such as thermocouples, require lead wires and cannot be applied to rotor blades. Infrared radiation methods cannot be applied to shielded or concealed areas. Accurate measurement of temperature and duration is crucial for assessing the lifespan of engine blades. Therefore, a novel passive, leadless method is needed to measure the surface temperature of complex workpieces and assess the duration of high temperatures. The method of this invention can use silicon carbide crystals to measure the temperature of aero-engines and calculate and predict the duration of peak temperatures. Furthermore, the calculated peak temperature and duration of temperature have very small errors compared to the actual values, meeting the requirements for precision measurement.

[0078] The specific implementation steps are as follows:

[0079] S1. Preparation of thermometric silicon carbide crystals:

[0080] Nitrogen-doped 6H-silicon carbide crystal was selected as the temperature sensing crystal, with a thickness of 0.3~0.5 mm;

[0081] S2. Irradiate the thermometric silicon carbide crystal selected in step S1 with neutrons:

[0082] The silicon carbide crystal was subjected to neutron irradiation in a full neutron irradiation mode, with an irradiation temperature not exceeding 100℃ and an irradiation dose not less than 1×10⁻⁶. 21 n / cm 2 .

[0083] Depending on the testing scenario, neutron-irradiated 6H-silicon carbide crystals are typically divided into appropriately sized silicon carbide crystal slices. To ensure the accuracy of spectral measurements, the silicon carbide crystal slices are generally no smaller than 5×5 mm. Therefore, after neutron irradiation, the silicon carbide crystal needs to be divided and further processed to obtain the thermometric crystal. The subsequent processing mainly includes polishing and annealing the silicon carbide crystal. Polishing includes mechanical and physical polishing. During annealing, multiple annealing temperatures are selected at a certain annealing time for multiple silicon carbide crystals, and all annealing temperatures are recorded. The absorption band edges of the silicon carbide crystals at multiple different annealing temperatures are measured and recorded.

[0084] S3. Determine the relationship between annealing temperature and absorption band edge. As the annealing temperature increases, the absorption band edge shifts blue towards shorter wavelengths. Figure 2 The diagram illustrates the light transmittance of 6H-silicon carbide crystals irradiated with neutrons at different annealing temperatures in embodiments of the present invention. Figure 3 The diagram shows the edge distribution of the 6H-silicon carbide absorption band after annealing for 2 minutes at a temperature range of 1000-1650°C in an embodiment of the present invention.

[0085] S4. Fit and establish a temperature duration evaluation model:

[0086] The prepared silicon carbide crystal wafer was placed in a high-temperature environment, and the duration of placement was controlled by an external timer within the range of 2-150 minutes. After the high-temperature process, the silicon carbide crystal was removed, and the absorption band edge position λ3 of the silicon carbide crystal at this time was obtained. The absorption band edge position λ3 was compared with... Figure 3 The absorption band edge is compared. For example, if λ3 = 850 nm, the highest temperature the wafer experienced is determined to be 1300 °C by using the relationship curve between the absorption band edge and the annealing temperature. λ3 is then substituted into... Figure 5 and Figure 6 The equation shown is λ3=λ 2-n =f(t), and the duration t of the peak temperature is obtained by parsing.

[0087] The duration assessment model is as follows:

[0088] λ 2-n =f(t)=a+b(t);

[0089] In practical applications, the analytical formula for the duration of peak temperature is shown in Table 1 below.

[0090]

[0091] Table 1

[0092] Figure 4 This diagram illustrates the variation of the 6H-silicon carbide absorption band edge with annealing time at different annealing temperatures in embodiments of the present invention. Figure 5 Different annealing temperatures T are shown in embodiments of the present invention. C-n Lower absorption band edge λ 2-n Fit λ to the duration of peak temperature t 2-n A schematic diagram of the curve data of the multinomial distribution of f(t);

[0093] This method assesses peak temperature and its duration, solving the measurement challenges of peak temperature and its duration in complex environments. Through multiple experiments, this invention selects the absorption band edge as the parameter for measuring temperature and duration. The absorption band edge reflects the energy level and concentration distribution of irradiated defects. High temperatures reduce defect concentration; under isothermal annealing conditions, the annealing time affects the migration of irradiated defects, altering the crystal's light absorption properties and changing the position of defect energy levels. Changes in defect concentration and energy level positions directly affect the absorption band edge distribution. Therefore, by observing changes in the absorption band edge, the effects of temperature and duration can be identified to some extent. During testing, the absorption band edge also offers advantages such as short test response time and stable test data. After extensive research, this method selects the absorption band edge as the input parameter for the peak temperature duration assessment model, enabling accurate and rapid acquisition of peak temperature and its duration. The peak temperature duration calculation model is simple to construct, has a wide temperature range, and offers fast temperature measurement.

[0094] To verify the feasibility of this method, the duration of the peak temperature obtained above is verified below:

[0095] The verification process is as follows:

[0096] The annealing temperature of silicon carbide crystal was set to 1470℃ and the annealing time was set to 40 min. The absorption band edge λ3 was measured to be 511.5 nm.

[0097] Temperature and duration assessment: by Figure 3 As can be seen from the data, the measured absorption band edge of 511.5 nm is located at... Figure 3 Between 1450-1500℃, the peak temperature corresponding to the absorption band edge is found to be 1450℃. Then, the absorption band edge λ3 = 511.5nm is substituted into the annealing time calculation model corresponding to the peak temperature of 1450℃, i.e., λ3 = λ 2-n In the equation f(t), appropriate fitting coefficients were selected according to Table 1 above, and t = 43.5 min was obtained analytically. This shows that the error between the peak temperature obtained by measuring the absorption band edge and the silicon carbide crystal temperature assessment is 20℃, and the error between the peak temperature duration and the annealing time assessment is 3.5 min. From this result, it can be concluded that this method determines the peak temperature duration by measuring the absorption band edge, and the result is almost identical to the actual result, demonstrating that the measurement process is fast and accurate.

[0098] In summary, the method for evaluating peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation provided by this invention can utilize the blue shift of the absorption band edge to evaluate the peak temperature and its duration, offering a new approach to measuring peak temperature duration and overcoming the shortcomings of existing technologies. The measurement method described in this invention can accurately evaluate the peak temperature and its duration within a high-temperature operation range of 2-150 minutes.

[0099] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation, characterized in that: It includes the following steps: S1. Selecting and processing silicon carbide crystals: The specific processing of silicon carbide crystals includes irradiation, slicing, annealing, and polishing. S2. Determine the absorption band edge of silicon carbide: Collect the absorption spectrum of silicon carbide crystal by spectrophotometer, and determine the absorption band edge of silicon carbide based on the collected absorption spectrum. S3. Determine the relationship between annealing temperature and absorption band edge: Measure the absorption band edge λ of silicon carbide crystals with a fixed annealing time at all annealing temperatures. 1-n And establish a one-to-one correspondence between the absorption band edge and the annealing temperature, that is, the absorption band edge λ. 1-1 Corresponding annealing temperature T C-1 Absorption band edge λ 1-2 Corresponding annealing temperature T C-2 Absorption band edge λ 1-3 Corresponding annealing temperature T C-3 ...absorption band edge λ 1-n Corresponding annealing temperature T C-n As the annealing temperature increases, the absorption band edge shifts towards shorter wavelengths in the blue direction; S4. Establish a duration evaluation model, which includes the following sub-steps: S41. Establish the relationship curve between the absorption band edge and the annealing temperature and duration: Determine the annealing temperature T. C-n Absorption band edge λ of silicon carbide crystals with different annealing times t 2-n , with λ 2-n Plot the annealing temperature T at a fixed annealing temperature with t as the x-axis. C-n The absorption band edge λ below 2-n The curve showing how the annealing time t changes; S42. Based on the curve data distribution from step S41, establish λ. 2-n =f(t) is the polynomial isothermal temperature calibration equation, i.e., the duration evaluation model. Based on the duration evaluation model, the absorption band edge λ is input. 2-n The annealing time t can be obtained by calculating the value. The specific evaluation model for the time is as follows: λ 2-n =f(t)=a+b(t); Where a and b are the fitting coefficients; S5. Measure the peak temperature and the duration of the peak temperature using a silicon carbide crystal, specifically including the following sub-steps: S51. Determine the peak temperature: Fix the silicon carbide crystal at the target temperature position. After the high-temperature process is completed, measure the absorption band edge λ3 of the silicon carbide crystal, and compare the measured absorption band edge λ3 with the absorption band edge λ of silicon carbide crystals annealed for 2 minutes at all annealing temperatures. 1-n By comparing the measured absorption band edge λ3, the range of the measured absorption band edge λ3 is determined, and the high temperature peak temperature corresponding to that range is obtained based on the range of the measured absorption band edge λ3. S52. Determine the duration of peak temperature: Based on the determined peak temperature, determine the fitting coefficient of the duration evaluation model, input the measured absorption band edge λ3 as the input value into the duration evaluation model and output the calculation result. The output value within the threshold range is taken as the effective value, which is the duration of peak temperature.

2. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 1, characterized in that: The silicon carbide crystal mentioned in step S1 is a nitrogen-doped 6H-silicon carbide crystal.

3. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 2, characterized in that: Step S1 specifically includes the following sub-steps: S11. Selection of silicon carbide crystal: Select nitrogen-doped 6H-silicon carbide crystal with a nitrogen doping concentration ≥ 10. 19 / cm 3 ; S12. Irradiate the silicon carbide crystal: Irradiate the silicon carbide crystal obtained in step S11 with neutrons, the irradiation dose being greater than or equal to 1.0 × 10⁻⁶. 21 Irradiation temperature less than or equal to 100℃, to obtain irradiated silicon carbide crystals; S13. Segment the silicon carbide crystal: Segment the silicon carbide crystal obtained in step S12 and process it into square crystals with a side length of 5 mm-10 mm. S14. Annealing the silicon carbide crystal: Annealing the silicon carbide crystal obtained in step S13 at different temperatures. S15. Polishing the silicon carbide crystal: Polish the silicon carbide crystal after annealing in step S14.

4. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 3, characterized in that: In step S12, the silicon carbide crystal obtained in step S11 is irradiated with neutrons using a full-energy spectrum.

5. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 3, characterized in that: The polishing process in step S15 includes mechanical polishing and chemical polishing, which are used to remove the surface oxide layer.

6. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 3, characterized in that: The spectrophotometer described in step S2 is equipped with both deuterium and xenon light sources, with a spectral resolution range of 0.5-2 nm, an absorption spectrum wavelength range of 300-1500 nm, and baseline calibration of the absorption spectrum. The number of times the absorption spectrum of silicon carbide crystal is acquired is greater than or equal to 5.

7. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 3, characterized in that: In step S51, the value in the range of 1000-1650℃ is the effective peak temperature. In step S52, the absorption band edge λ3 is input into the model, and the output value in the range of 2-150min is taken as the effective output value, i.e., the duration of the peak temperature.

8. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 1, characterized in that: In step S51, the interval of the measured absorption band edge λ3 is determined, and the high-temperature peak temperature corresponding to this interval is obtained based on the measured absorption band edge λ3 interval as follows: When λ 1-n >λ3>λ 1-(n+1) When the absorption band edge λ3 is reached, the high-temperature peak temperature corresponding to it is determined to be T. C-n .

9. The method for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation according to claim 3, characterized in that: In step S14, the annealing temperature range is 1000-1650℃, with an increasing annealing temperature gradient at 50℃ intervals, and the annealing temperature T is recorded. C In step S3, the annealing time is 2 minutes.

10. A system for determining the peak temperature and duration based on the blue shift of the absorption band edge of silicon carbide under neutron irradiation as described in claim 1, characterized in that: It includes a module for determining the relationship between the absorption band edge and the annealing temperature, a module for establishing a duration evaluation model, a module for calculating the peak temperature, and a module for calculating the duration of the peak temperature. The module for determining the relationship between the absorption band edge and the annealing temperature is used to determine the relationship between different annealing temperatures and the absorption band edge under a certain annealing duration. The module for establishing a duration evaluation model is used to establish a duration evaluation model based on the fitting curve between the annealing temperature duration and the absorption band edge under a certain annealing temperature. If the absorption band edge is used as the input of the duration evaluation model, the annealing duration at that annealing temperature can be output. The peak temperature calculation module is used to determine the peak temperature based on the absorption band edge measured when the temperature-measuring silicon carbide crystal is working. The peak temperature duration calculation module takes the measured absorption band edge as input based on the determined peak temperature and outputs an effective value within the threshold range as the output value, which is the peak temperature duration.

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