Off-line temperature measurement material and preparation method thereof

Abstract

The invention provides an off-line temperature measurement material and a preparation method thereof. The off-line temperature measurement material is a Te-Sn eutectic alloy composed of metal tellurium and metal tin. The off-line temperature measuring material is in a filament shape, and the diameter of the off-line temperature measuring material is 1.5-3 mm. The melting point of the obtained off-line temperature measuring material is about 400 DEG C, the difference value between the initial melting temperature TS and the complete melting temperature TL is smaller than 6 DEG C, the off-line temperature measuring material has the advantages of being accurate in melting point and small in melting temperature interval, and the blank that no off-line temperature measuring material for accurate temperature measurement exists at the temperature measuring point of 400 DEG C is filled.

Description

Technical Field

[0001] This invention relates to the field of offline temperature measurement materials and their preparation technology, and particularly to an offline temperature measurement material and its preparation method. Background Technology

[0002] Nuclear reactors operate in environments characterized by high temperatures, intense neutron radiation, and confined space. Before the reactor reaches its operating temperature, repeated temperature resistance assessments of the stability of each component within the reactor are necessary to ensure safety. A specific testing method involves placing a set of temperature sensing components within the confined space of the nuclear reactor, using metals or alloys with precise melting points at 30-50°C gradients. Based on the state of the sensing materials after simulating the temperature (either fully fused droplets or maintained filamentous form), effective offline temperature estimation is achieved.

[0003] Currently, there is a lack of thermometric materials with accurate melting points and small melting temperature ranges around 400 ℃, resulting in blind spots in nuclear reactor safety monitoring. Summary of the Invention

[0004] To address the problems existing in the background technology, the present invention provides an offline temperature measurement material and its preparation method. The temperature measurement material has the characteristics of accurate melting point, small melting range and high stability, filling the gap in offline temperature measurement materials around 400 ℃.

[0005] The specific details of the invention are as follows: In a first aspect, the present invention provides an offline temperature measurement material, wherein the offline temperature measurement material is a Te-Sn eutectic alloy composed of metallic tellurium and metallic tin; The offline temperature measuring material is filamentous with a diameter of 1-3 mm.

[0006] Optionally, the atomic percentage of tellurium in the offline temperature measurement material is 85±0.5%.

[0007] Optionally, the impurity content in the offline temperature measurement material satisfies the following: B atomic percentage ≤ 0.01%, Cd atomic percentage ≤ 0.01%, Fe atomic percentage ≤ 0.01%, O content ≤ 800 ppm, other impurity atomic percentage ≤ 0.02%.

[0008] Optionally, the initial melting temperature of the offline temperature measuring material is 401.67 ℃-401.75 ℃, and the complete melting temperature is 406.42 ℃-407.51 ℃.

[0009] In a second aspect, the present invention provides a method for preparing an offline temperature measuring material, wherein the offline temperature measuring material is the offline temperature measuring material provided in the first aspect above, and the preparation method includes: According to the atomic percentage composition of the Te-Sn eutectic alloy, weigh the required high-purity tellurium and high-purity tin, and perform vacuum induction melting with the assistance of electromagnetic stirring to obtain the alloy melt. The alloy melt is injected into a mold under pressure, and ultrasonic waves are applied to the mold to cool and crystallize the alloy melt injected into the mold with the assistance of ultrasonic waves, thereby obtaining an alloy ingot. The alloy ingot is annealed at 350 ℃-380 ℃ for 1-2 h, and after being cooled in the furnace, it is wire cut into 1-3 mm fine wires to obtain the offline temperature measuring material.

[0010] Optionally, the temperature of the vacuum induction melting is 800 ℃-900 ℃, and the melting time is 10-30 min.

[0011] Optionally, the frequency of the ultrasound is 15-25 kHz.

[0012] Optionally, the cooling and crystallization can be carried out by furnace cooling or water quenching.

[0013] Optionally, the high-purity tellurium and high-purity tin need to undergo impurity removal treatment before being used in the vacuum induction melting process. The impurity removal treatment includes: The high-purity tellurium and high-purity tin were ultrasonically cleaned in nitric acid solution for 5-15 minutes, then rinsed alternately with deionized water and anhydrous ethanol until neutral, and finally dried in an inert atmosphere.

[0014] Optionally, the frequency of the ultrasound is 15-25 kHz.

[0015] Compared with the prior art, the present invention has the following advantages: This invention provides an offline temperature sensing material, which is a Te-Sn eutectic alloy composed of metallic tellurium and metallic tin; the offline temperature sensing material is filamentous with a diameter of 1.5-3 mm; the offline temperature sensing material obtained by this invention has a melting point around 400 °C and an initial melting temperature T S and complete melting temperature T L The difference between them is less than 6 ℃, which has the advantages of accurate melting point and small melting temperature range, so as to fill the gap of no accurate offline temperature measurement material for measuring temperature at 400 ℃. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating the preparation method of the offline temperature measurement material provided in an embodiment of the present invention is shown; Figure 2 The microstructure of the Te-Sn eutectic alloy provided in the embodiment of the present invention is shown. Figure 3 The DSC measurement results of the Te-Sn eutectic alloy provided in the embodiments of the present invention are shown. Figure 4 The microstructure of a Te-Sn eutectic alloy provided in another embodiment of the present invention is shown. Figure 5 The DSC measurement results of a Te-Sn eutectic alloy provided in another embodiment of the present invention are shown; Figure 6 The microstructure of a Te-Sn eutectic alloy provided in another embodiment of the present invention is shown. Figure 7 The DSC measurement results of a Te-Sn eutectic alloy provided by another embodiment of the present invention are shown. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0019] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0020] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0021] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Among related existing technologies, patent CN 115449664 A proposes a Pb-Sb thermometric material with a temperature measurement range of 290.8~609.8 ℃ depending on the Sb content. Another example is patent CN116481667A, which discloses a thermometric material and its preparation method. This method uses hypoeutectic alloys, hypereutectic alloys, or single-phase binary alloys. By adjusting the mass percentages of the two components (e.g., x=2-90 in Ag-xBi and x=13-65 in Al-xSi), a linear and continuous change in melting point is achieved, ultimately covering a wide temperature range of 300 ℃-1200 ℃. This solves the problem that traditional thermometric materials are difficult to adapt to the neutron irradiation temperature requirements of various types of fusion materials, providing a rich selection of materials for wide-range scenarios.

[0023] However, since the aforementioned thermometric materials are all hypoeutectic or hypereutectic structures, their measured temperatures represent the complete melting temperature of the alloy. Hypereutectic or hypoeutectic alloys, on the other hand, have an initial melting temperature T. S and complete melting temperature T L Two melting points, T L -T S This refers to the melting temperature range within which the alloy exists in a liquid + solid state. Therefore, in practical applications, it's impossible to accurately determine the actual operating temperature of this type of alloy; for example, the T value of Al-90Sn thermometric material... S The temperature is 227℃, T L The temperature is 407℃, and the melting temperature range reaches 180℃. This "temperature range phase transition" results in a large temperature measurement error, which is far from meeting the requirements for accurate temperature judgment in scenarios such as nuclear reactor operating condition monitoring (requiring a resolution of ≤3℃) and motor thermal runaway early warning. It is easy to misjudge the operating condition due to excessive error.

[0024] To ensure the accuracy of offline temperature measurement results, a temperature-sensing material system with a melting point gradient is composed of different temperature-sensing materials with fixed melting points. This system is used for offline temperature measurement in a narrow temperature range at medium and high temperatures, effectively solving the problem of temperature ambiguity caused by temperature-range phase transitions. Meanwhile, pure metals or binary eutectic alloys... S and T L It is the same point, ideally, T S =T LThe melting temperature range is 0°C, making it an ideal choice for temperature measurement materials. This invention addresses the issue of a lack of temperature measurement materials with accurate melting points and narrow melting temperature ranges around 400°C for offline temperature measurement. It provides a novel offline temperature measurement material: a Te-Sn eutectic alloy. Based on the phase diagram of the Te-Sn eutectic alloy, its theoretical melting point is determined to be 400°C. In actual measurements, the initial melting temperature T of this material is... S and complete melting temperature T L The difference between them is less than 6 °C, which has the advantages of accurate melting point and small melting temperature range.

[0025] The offline temperature measurement material provided by this invention will be described in detail below: In a first aspect, the present invention provides an offline temperature measurement material, wherein the offline temperature measurement material is a Te-Sn eutectic alloy composed of metallic tellurium and metallic tin; the offline temperature measurement material is filamentous and has a diameter of 1-3 mm.

[0026] Analysis of the phase diagram of the Te-Sn eutectic alloy shows that its melting point is 400℃. In actual melting point tests, the initial melting temperature T of the Te-Sn eutectic alloy is... S The complete melting temperature T is between 401.67 ℃ and 401.75 ℃. L The melting point deviation is less than 2℃ between 406.42℃ and 407.51℃. S With T L The difference between the values ​​is no greater than 6 ℃, which meets the accuracy requirements for offline temperature measurement.

[0027] In some implementations, based on the eutectic composition design of the Te-Sn binary phase diagram, and combined with the requirements for nuclear temperature measurement at 400 °C, experimental verification, and process feasibility, the atomic percentage of metallic tellurium in the offline temperature measurement material is 85 ± 0.5%.

[0028] In some implementations, the impurity content in the offline temperature measurement material needs to be strictly controlled to ensure the accuracy of temperature measurement, irradiation stability, and structural reliability in nuclear applications. This is crucial for ensuring the material's compatibility with the offline temperature measurement requirements of a 400°C nuclear reactor. Strictly limiting the content of impurities such as B, Cd, and Fe, as well as the total impurity content, can avoid melting point fluctuations caused by compositional deviations. This maintains the core performance of an initial melting temperature of 401.67°C-401.75°C, a melting range of <6°C, and a melting point deviation of <2°C, ensuring accurate temperature measurement data. Furthermore, nuclear reactors operate under strong neutron irradiation. Both B and Cd are strong neutron absorbers; excessive amounts will increase neutron absorption, not only interfering with the reactor's operating environment but also potentially leading to material activation and the generation of radioactive impurities. Specifically, the impurity content must meet the following requirements: B atomic percentage ≤ 0.01%, Cd atomic percentage ≤ 0.01%, Fe atomic percentage ≤ 0.01%, O content ≤ 800 ppm, other impurity atomic percentage ≤ 0.02%.

[0029] As a specific application example, the offline temperature measuring material provided by this invention can be combined with five other temperature measuring materials—Zn-Al eutectic alloy, pure zinc, Mg-Al eutectic alloy, and Mg-Cu eutectic alloy—to form a temperature measuring material system. Based on the phase transition temperatures of Zn-Al eutectic alloy, Te-Sn eutectic alloy, pure zinc, Mg-Al eutectic alloy, and Mg-Cu eutectic alloy, which are 381 ℃, 398 ℃, 420 ℃, 448 ℃, and 490 ℃ respectively, the resulting temperature measuring material system has a rated temperature range of 381 ℃ to 490 ℃. Furthermore, the temperature measurement error within this rated temperature range is reduced to 17-42 ℃.

[0030] Because the alloy formed by Te and Sn is quite brittle, it is difficult to prepare it into wires with a diameter of only 1.5-3 mm using conventional methods. This invention improves the preparation method and further utilizes the following preparation scheme to prepare the Te-Sn eutectic alloy into wires: Secondly, the present invention provides a method for preparing an offline temperature measurement material, wherein the offline temperature measurement material is the offline temperature measurement material provided in the first aspect above. Figure 1 A flowchart illustrating the preparation method of the offline temperature measurement material provided in an embodiment of the present invention is shown, as follows: Figure 1 As shown, the preparation method includes: S1. Weigh out the required high-purity tellurium and high-purity tin according to the atomic percentage composition of the Te-Sn eutectic alloy, and perform vacuum induction melting with the assistance of electromagnetic stirring to obtain the alloy melt. S2. The alloy melt is injected into a mold under pressure, and ultrasonic waves are applied to the mold to cool and crystallize the alloy melt injected into the mold with the assistance of ultrasonic waves, thereby obtaining an alloy ingot. S3. The alloy ingot is annealed at 350 ℃-380 ℃ for 1-2 h, and after being cooled in the furnace, it is wire cut into 1-3 mm fine wires to obtain the offline temperature measuring material.

[0031] In practice, the particle size of the high-purity tellurium and high-purity tin raw materials is 0.3 mm. The 3mm thickness facilitates close packing within the crucible, promoting uniform heating and melting. This invention, by employing electromagnetic stirring during vacuum induction melting, effectively promotes homogenization of the melt composition, preventing localized segregation of Te and Sn elements and ensuring the alloy strictly adheres to the eutectic ratio of 85±0.5%Te and 15±0.5%Sn. Electromagnetic stirring also accelerates the escape of bubbles and the volatilization of low-boiling-point impurities in the melt, reducing interference from impurities on the formation of the eutectic structure and indirectly ensuring melting point stability. Furthermore, it ensures uniform melt temperature distribution, preventing localized overheating or incomplete melting, and providing a homogeneous melt environment for subsequent crystallization.

[0032] It should be noted that the mold used in this invention is preferably made of quartz. The opening diameter of the mold is slightly larger than the diameter of the offline temperature measuring material. When the alloy melt is poured into the mold, the alloy melt is pressed into the mold by pressurizing with inert gas at a pressure of 50-200 kPa.

[0033] In practice, the alloy melt obtained from smelting is assisted by ultrasonic waves during the pouring into the mold and crystallization process. The ultrasonic cavitation effect and vibration refine the grains, break the coarse eutectic structure, obtain a fine and uniform microstructure, and reduce structural defects. During the casting and crystallization stage, the composition remains uniform to ensure a consistent distribution of the eutectic phase.

[0034] In some embodiments, the temperature of the vacuum induction melting is 800 ℃-900 ℃, and the melting time is 10-30 min.

[0035] In some embodiments, the ultrasonic generator provides ultrasonic waves at a frequency of 15-25 kHz, and the power of the ultrasonic generator is preferably 0.5-2.0 kW.

[0036] In some embodiments, the cooling and crystallization are carried out by furnace cooling or water quenching. Furnace cooling has a lower cooling rate than water quenching. Water quenching produces an alloy with a fine, non-equilibrium eutectic structure, which helps improve the alloy's machinability. Furnace cooling produces an alloy with a balanced eutectic structure, reducing thermal stress. Furthermore, the casting mold can be preheated before use, with a preheating temperature of 300 °C, which helps to obtain a balanced eutectic structure.

[0037] In some embodiments, the high-purity tellurium and high-purity tin need to undergo a purification process before being used in the vacuum induction melting process. This purification process includes: The high-purity tellurium and high-purity tin were ultrasonically cleaned in nitric acid solution for 5-15 minutes, then rinsed alternately with deionized water and anhydrous ethanol until neutral, and finally dried in an inert atmosphere.

[0038] In practice, high-purity tellurium (Te) and high-purity tin (Sn) are used as initial raw materials with a purity of at least 5N (99.999%). They are soaked in dilute nitric acid, then repeatedly rinsed with deionized water and anhydrous ethanol, and dried at low temperature under vacuum or inert atmosphere (such as argon) to remove possible oxides and organic contaminants and ensure that they meet the purity requirements.

[0039] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to provide a detailed description of the offline temperature measurement material and its preparation method.

[0040] Example 1 This embodiment provides a Te-Sn alloy nuclear temperature measuring material, the composition of which is a Te-Sn alloy with an atomic percentage of 15% Sn and the remainder Te. Sn particles (2 mm) and Te particles (3 mm) are taken and ultrasonically cleaned in a 10% dilute nitric acid solution for 10 minutes; then rinsed repeatedly with ultrapure water until neutral; finally dehydrated with anhydrous ethanol and thoroughly dried in a drying oven at 60°C under argon protection.

[0041] After the above pretreatment, the raw materials are loaded into a clean crucible (high-purity graphite) in a vacuum induction furnace. After sealing the furnace, the vacuum system is activated, and the furnace vacuum level is evacuated to <1×10⁻⁶. -3 A high vacuum of Pa is established to minimize the influence of gaseous impurities (especially oxygen). After reaching high vacuum, the crucible and raw materials are slowly preheated at 20% of the rated power of the induction furnace for approximately 15 minutes to remove adsorbed trace gases and ensure uniform heating of the raw materials. Once the current stabilizes, the power is rapidly increased to the rated power for rapid melting. After the raw materials are completely melted and a homogeneous melt is formed, the melt temperature is controlled within the range of 800℃, and refining is carried out at this temperature for 30 minutes. During this period, the electromagnetic stirring effect generated by the induced current keeps the melt in motion, promoting initial homogenization of the composition and facilitating the volatilization of low-boiling-point impurities.

[0042] The mold is preheated and kept at a constant temperature of 300℃. Argon gas is then introduced into the furnace to a positive pressure of 200 kPa. The introduction of argon gas allows the refined melt to be injected into the mold quickly and smoothly, reducing oxidation and splashing during casting. Simultaneously, ultrasonic stirring is activated, applying ultrasonic waves to the mold. The ultrasonic generator has a power of 2.0 kW and a frequency of 25 kHz. This ultrasonic stirring effectively affects the alloy's crystallization process, significantly refining the metal grains, homogenizing the alloy composition, and accelerating the escape of tiny bubbles from the melt.

[0043] The melt, along with the mold, is cooled in a vacuum or protective atmosphere to form a Te-Sn alloy ingot, with a cooling rate of less than 10°C / min. This method is beneficial for obtaining a balanced eutectic structure and reducing thermal stress.

[0044] The Te-Sn alloy ingot was held at 350℃ for 1 hour with a heating rate of 3℃ / min. After holding, it was cooled in the furnace to below 80℃ before being removed from the furnace. The vacuum degree was required to be ≤1×10⁻⁶. -3 Pa, after heat treatment, was machined into 1-3 mm fine wires by wire cutting. The wires were then polished smooth using 400-1000 grit sandpaper. The microstructure of the obtained Te-Sn eutectic alloy is shown in [reference needed]. Figure 2 .

[0045] The prepared filaments were tested using differential scanning calorimetry (DSC). Test conditions: heating rate 10℃ / min, nitrogen protection.

[0046] Figure 3 The DSC measurement results of the Te-Sn eutectic alloy provided in the embodiments of the present invention are shown, such as... Figure 3 As shown, the initial melting temperature of this material is 401.67℃, and the complete melting temperature is 407.51℃.

[0047] Example 2 This embodiment provides a Te-Sn alloy nuclear temperature measuring material, the composition of which is a Te-Sn alloy with an atomic percentage of 15% Sn and the remainder Te. Sn particles (2 mm) and Te particles (3 mm) are taken and ultrasonically cleaned in a 10% dilute nitric acid solution for 10 minutes; then rinsed repeatedly with ultrapure water until neutral; finally dehydrated with anhydrous ethanol and thoroughly dried in a drying oven at 60°C under argon protection.

[0048] After the above pretreatment, the raw materials are loaded into a clean crucible (high-purity graphite) in a vacuum induction furnace. After sealing the furnace, the vacuum system is activated, and the furnace vacuum level is evacuated to <1×10⁻⁶. -3 A high vacuum of Pa is established to minimize the influence of gaseous impurities (especially oxygen). After reaching high vacuum, the crucible and raw materials are slowly preheated at 30% of the rated power of the induction furnace for approximately 10 minutes to remove adsorbed trace gases and ensure uniform heating of the raw materials. Once the current stabilizes, the power is rapidly increased to the rated power for rapid melting. After the raw materials are completely melted and a homogeneous melt is formed, the melt temperature is controlled within the range of 850°C, and refining is carried out at this temperature for 20 minutes. During this period, the electromagnetic stirring effect generated by the induced current keeps the melt in motion, promoting initial homogenization of the composition and facilitating the volatilization of low-boiling-point impurities.

[0049] After refining, argon gas is introduced into the furnace to a positive pressure of 100 kPa. The introduction of argon gas allows the melt to be injected quickly and smoothly into the pre-placed mold, reducing oxidation and splashing during casting. Simultaneously, ultrasonic stirring is activated to apply ultrasonic waves to the mold. The ultrasonic generator is preferably 1.0 kW with a frequency of 20 kHz. This ultrasonic stirring effectively affects the alloy's crystallization process, significantly refining the metal grains, homogenizing the alloy composition, and accelerating the escape of tiny bubbles from the melt.

[0050] The melt, along with the mold, is naturally cooled in a vacuum furnace to obtain a Te-Sn alloy ingot. The ingot is held at 365℃ for 2 hours with a heating rate of 3℃ / min. After holding, it is cooled in the furnace to below 80℃ before being removed from the furnace. The vacuum degree is required to be ≤1×10⁻⁶. - 3 Pa, after heat treatment, was machined into 1-3 mm fine wires by wire cutting. The wires were then polished smooth using 400-1000 grit sandpaper. The microstructure of the obtained Te-Sn eutectic alloy is shown in [reference needed]. Figure 4 .

[0051] The prepared filaments were tested using differential scanning calorimetry (DSC). Test conditions: heating rate 10℃ / min, nitrogen protection.

[0052] Figure 5 The following is an illustration of DSC measurement results for a Te-Sn eutectic alloy provided by another embodiment of the present invention, such as... Figure 5 As shown, the initial melting temperature of this material is 401.73℃, and the complete melting temperature is 407.38℃.

[0053] Example 3 This embodiment provides a Te-Sn alloy nuclear temperature measuring material, the composition of which is a Te-Sn alloy with an atomic percentage of 15% Sn and the remainder Te. Sn particles (2 mm) and Te particles (3 mm) are taken and ultrasonically cleaned in a 10% dilute nitric acid solution for 10 minutes; then rinsed repeatedly with ultrapure water until neutral; finally dehydrated with anhydrous ethanol and thoroughly dried in a drying oven at 60°C under argon protection.

[0054] After the above pretreatment, the raw materials are loaded into a clean crucible (high-purity graphite) in a vacuum induction furnace. After sealing the furnace, the vacuum system is activated, and the furnace vacuum level is evacuated to <1×10⁻⁶. -3A high vacuum of Pa is established to minimize the influence of gaseous impurities (especially oxygen). After reaching high vacuum, the crucible and raw materials are slowly preheated at 40% of the rated power of the induction furnace for approximately 15 minutes to remove adsorbed trace gases and ensure uniform heating of the raw materials. Once the current stabilizes, the power is rapidly increased to the rated power for rapid melting. After the raw materials are completely melted and a homogeneous melt is formed, the melt temperature is controlled within 900°C, and refining is performed at this temperature for 10 minutes. During this period, the electromagnetic stirring effect generated by the induced current keeps the melt in motion, promoting initial homogenization of the composition and facilitating the volatilization of low-boiling-point impurities.

[0055] After refining, argon gas is introduced into the furnace to a positive pressure of 50 kPa. The introduction of argon gas allows the melt to be injected quickly and smoothly into the pre-placed mold, reducing oxidation and splashing during casting. Simultaneously, ultrasonic stirring is activated to apply ultrasonic waves to the mold. The ultrasonic generator is preferably 0.5 kW with a frequency of 15 kHz. This ultrasonic stirring effectively affects the alloy's crystallization process, significantly refining the metal grains, homogenizing the alloy composition, and accelerating the escape of tiny bubbles from the melt.

[0056] Water-cooled copper molds were used for casting, with a cooling rate greater than 100℃ / s. This method yields a fine, non-equilibrium eutectic structure, improving the alloy's machinability. This resulted in a Te-Sn alloy ingot.

[0057] The ingot was held at 380℃ for 3 hours, with a heating rate of 3℃ / min. After holding, it was cooled to below 80℃ in the furnace before being removed from the furnace. The vacuum degree was required to be ≤1×10⁻⁶. -3 Pa, after heat treatment, was machined into 1-3 mm fine wires by wire cutting. The wires were then polished smooth using 400-1000 grit sandpaper. The microstructure of the obtained Te-Sn eutectic alloy is shown in [reference needed]. Figure 6 .

[0058] The prepared filaments were tested using differential scanning calorimetry (DSC). Test conditions: heating rate 10℃ / min, nitrogen protection.

[0059] Figure 7 The following is an illustration of DSC measurement results for a Te-Sn eutectic alloy provided by another embodiment of the present invention, such as... Figure 7 As shown, the initial melting temperature of this material is 401.75℃, and the complete melting temperature is 406.42℃.

[0060] The DSC results of the three implementation cases above demonstrate that the Te-Sn eutectic alloy exhibits excellent melting point accuracy and stability, with a melting temperature range all <6℃ and a melting point deviation of less than 2℃. It possesses advantages such as accurate melting point, narrow melting temperature range, and high stability. It can be used in nuclear reactor temperature sensing components as a gradient temperature sensing point near 400℃. This invention, through compositional design and strict impurity control, provides a Te-Sn-based nuclear temperature sensing material with accurate melting point and stable performance. Its preparation method is simple, has good repeatability, and is suitable for the field of nuclear reactor safety monitoring.

[0061] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0062] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0063] The above provides a detailed description of the offline temperature measurement material and its preparation method provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An offline temperature measurement material, characterized in that, The offline temperature measurement material is a Te-Sn eutectic alloy composed of tellurium and tin. The offline temperature measuring material is filamentous with a diameter of 1.5-3 mm.

2. The offline temperature measurement material according to claim 1, characterized in that, In the offline temperature measurement material, the atomic percentage of metallic tellurium is 85±0.5%.

3. The offline temperature measurement material according to claim 1, characterized in that, The impurity content in the offline temperature measurement material meets the following requirements: B atomic percentage ≤ 0.01%, Cd atomic percentage ≤ 0.01%, Fe atomic percentage ≤ 0.01%, O content ≤ 800ppm, other impurity atomic percentage ≤ 0.02%.

4. The offline temperature measurement material according to claim 1, characterized in that, The initial melting temperature of the offline temperature measuring material is 401.67 ℃-401.75 ℃, and the complete melting temperature is 406.42 ℃-407.51 ℃.

5. A method for preparing an offline temperature measurement material, characterized in that, The offline temperature measuring material is any one of the offline temperature measuring materials described in claims 1-4 above, and the preparation method includes: According to the atomic percentage composition of the Te-Sn eutectic alloy, weigh the required high-purity tellurium and high-purity tin, and perform vacuum induction melting with the assistance of electromagnetic stirring to obtain the alloy melt. The alloy melt is injected into a mold under pressure, and ultrasonic waves are applied to the mold to cool and crystallize the alloy melt injected into the mold with the assistance of ultrasonic waves, thereby obtaining an alloy ingot. The alloy ingot is annealed at 350 ℃-380 ℃ for 1-2 h, and after being cooled in the furnace, it is wire cut into fine wires of 1-3 mm to obtain the offline temperature measuring material.

6. The method for preparing the offline temperature measurement material according to claim 5, characterized in that, The vacuum induction melting temperature is 800 ℃-900 ℃, and the melting time is 10-30 min.

7. The method for preparing the offline temperature measurement material according to claim 5, characterized in that, The frequency of the ultrasound is 15-25 kHz.

8. The method for preparing the offline temperature measurement material according to claim 5, characterized in that, The cooling and crystallization are carried out by furnace cooling or water quenching.

9. The method for preparing the offline temperature measurement material according to claim 5, characterized in that, Before being used in the vacuum induction melting process, the high-purity tellurium and high-purity tin need to undergo a purification treatment, which includes: The high-purity tellurium and high-purity tin were ultrasonically cleaned in nitric acid solution for 5-15 minutes, then rinsed alternately with deionized water and anhydrous ethanol until neutral, and finally dried in an inert atmosphere.

10. The method for preparing the offline temperature measurement material according to claim 5, characterized in that, The frequency of the ultrasound is 15-25 kHz.

Images