A rare earth-doped cobalt-rhenium ultrahigh temperature temperature-regulating alloy and its preparation method and application

Abstract

The present invention belongs to the field of alloy technology, specifically a rare earth cobalt-rhenium ultra-high temperature temperature-correcting alloy and its preparation method and application. The rare earth cobalt-rhenium ultra-high temperature temperature-correcting alloy, calculated by mass percentage, includes: Co 0-99.995wt%, RE 0.005-1.5wt%, and the balance is Re and unavoidable impurity elements, and its melting point range is 1494-3180℃. A plurality of the above-mentioned cobalt-rhenium ultra-high temperature temperature-correcting alloys are placed in a container to form an alloy temperature-correcting device. The above-mentioned alloy temperature-correcting device is placed at a location where temperature correction and temperature measurement are required, and the state of the temperature-correcting alloy is checked afterwards. The actual temperature of the location of the alloy temperature-correcting device is determined based on whether the shape of the temperature-correcting alloy changes. The present invention has the characteristics of fast detection, convenient and flexible operation, in-situ, and no need for wiring. The melting point of the temperature-correcting alloy is not easily affected by a small amount of oxygen in the atmosphere, nor is it affected by various particle radiations, electromagnetic interference, or pressure changes. It is suitable for temperature calibration and measurement of industrial furnaces with various atmosphere pressures, ensuring the accuracy of temperature measurement in scientific research and production processes.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloys, and in particular relates to a rare earth cobalt-rhenium doped ultrahigh temperature temperature-regulating alloy and a preparation method and application thereof. Background Art

[0002] Temperature is a physical quantity that indicates the degree of hotness or coldness of an object. It reflects the intensity of the thermal motion of molecules within an object at the microscopic level. Temperature measurement is widely used, for example, to measure the temperature of various gases, liquids, and solids. Temperature measurement and control are crucial in industrial furnaces, such as those used to sinter magnetic materials, carbide, and ceramic materials. Temperature measurement and control are directly related to process success, product quality, and energy efficiency.

[0003] Industrial furnaces typically use thermocouples, RTDs, optical pyrometers, and other devices for temperature measurement and control. The most widely used industrial temperature measurement and control systems primarily consist of thermocouples, compensation wires, and instrumentation. Numerous factors affect the accuracy of these systems, including errors inherent in thermocouples, compensation wires, and instrumentation. In particular, thermocouples inevitably deteriorate over time due to high-temperature volatilization of the thermocouple wire, oxidation, corrosion and contamination, and changes in grain structure. This gradually alters the thermoelectric properties of the thermocouple, leading to significant errors in the temperature measurement and control system. Thermocouples and instrumentation are also susceptible to interference from external factors such as neutron radiation and electromagnetic interference, which can affect temperature measurement accuracy.

[0004] Pure metals (single element metals) and some alloys have definite melting points. If a series of pure metals or alloys with different melting points are placed in a container, such as ceramic or glass, and then placed in an industrial furnace, if the ambient temperature of the container exceeds the melting point of certain pure metals or alloys, they will melt and undergo a noticeable change in shape after becoming liquid. This shape change occurs within a few seconds, and they will retain their molten shape after cooling to room temperature. If the ambient temperature is below the melting point of certain pure metals or alloys, these metals or alloys will not melt or change shape significantly. By directly observing the shape change of these pure metals or alloys in a transparent container at high temperatures or after cooling to room temperature, it can be determined whether they have melted and the actual temperature of the furnace where these containers are located can be easily determined. For example, prior art has found that the temperature inside a dry quenching furnace can reach over 1000°C. Conventional temperature measurement methods are difficult to accurately measure the operating temperature of the corbel bricks. This, coupled with the inability to correctly select the materials for the corbel bricks in different locations, can lead to stress accumulation within the corbel bricks, ultimately manifesting as cracks on the brick surface. To address the above-mentioned issues, a temperature measurement device and method for accurately measuring the three-dimensional temperature field of a corbel brick has been proposed. The method involves placing multiple metal or alloy blocks with melting points arranged in an arithmetic progression within a refractory box divided into multiple compartments. The refractory box is then positioned at the corbel brick location. Based on whether the metal or alloy melts and changes shape, the true temperature at that location can be determined. This true temperature lies between the melting points of the highest melting point of the melted metal blocks and the lowest melting point of the unmelted metal blocks. For example, if a metal block with a melting point of 1045°C melts in a refractory box, but a metal block with a melting point of 1048°C does not, the temperature at that location can be accurately determined to be between 1045°C and 1048°C. Such metals are considered temperature-sensitive metals. The above technical solution does not address the specific atmosphere surrounding the corbel brick and the effect of any oxygen in the atmosphere on the melting point of the temperature-sensitive metal.

[0005] High-radiation environments, such as reactor cores, or extreme environments, such as neutron irradiation experiments, require more precise temperature monitoring methods. Under the harsh conditions of intense neutron irradiation, conventional temperature measurement methods, such as thermocouples, cannot accurately measure or assess the ambient temperature. Because the melting point of metals is not easily affected by high-energy radiation and high-dose neutron irradiation, a series of temperature-measuring alloys and application methods have been developed. These alloys, such as silver-lithium alloys, antimony-containing alloys, and lead-bismuth alloys, utilize the alloys' shape changes and flow properties after melting to effectively address this issue, enabling temperature measurement in environments ranging from 180°C to 1200°C under intense neutron irradiation. These metals, known as temperature-measuring alloys, typically contain relatively active elements that react easily with oxygen in the environment, reducing their temperature measurement accuracy or even rendering the alloy completely ineffective. To avoid problems such as oxidation, the temperature measuring alloy needs to be sealed with a quartz tube or a corrosion-resistant metal tube, and filled with inert gas or evacuated to form a temperature measuring device. After use, the temperature measurement value is obtained by measuring the change in the center of gravity of the temperature measuring device or by dissecting the device to check the state of the temperature measuring alloy and the dripping situation. This method of using quartz tubes or metal tubes to completely seal the temperature measuring metal and completely isolate the influence of oxygen in the external environment on the melting point of the alloy has limitations. When the furnace changes from high temperature and high pressure to high temperature and high vacuum atmosphere, the pressure difference between the inside and outside of the temperature measuring device is too large, which may cause the device to collapse or burst, posing a risk of failure.

[0006] Industrial furnaces typically use temperature measurement and control systems to achieve automatic heating. However, as temperature sensors and other temperature measurement and control system components age, system errors gradually increase, causing the temperature displayed and controlled by the system to deviate increasingly from the actual temperature. Without timely temperature calibration and compensation, the actual temperature of various industrial furnaces will increasingly deviate from the target value (the temperature required by the process), leading to fluctuations in product quality and performance. Therefore, to ensure the measurement accuracy and reliable temperature values ​​of industrial furnace temperature measurement and control systems, regular or irregular temperature calibration is required for operating furnaces. Existing temperature measurement systems often cannot detect the actual temperature of the processed materials because their probes are located far away from the location of the processed materials in the furnace. Therefore, the development of methods that can detect the actual temperature of the materials is urgently needed.

[0007] To comprehensively and accurately monitor and calibrate furnace temperatures, ensure internal temperature uniformity, and guarantee consistent product quality, the aerospace and automotive industries widely utilize on-site high-temperature measurement calibration procedures, namely AMS2750 and CQI-9, for regular calibration of industrial furnace temperatures. Both procedures detail requirements for instrumentation, thermal processing equipment, thermocouples, temperature uniformity measurements, and system accuracy testing. These procedures require a rectangular or cylindrical stand installed inside the furnace, on which multiple calibration thermocouples are mounted. These are then connected to calibration instruments outside the furnace via leads for on-site calibration of furnace temperature and uniformity. This calibration method allows for simultaneous calibration of furnace temperature and temperature uniformity. However, its disadvantages include a relatively complex calibration procedure, requiring specialized operator training, interrupting normal furnace production, cleaning the furnace, and installing the stand and temperature calibration equipment. Calibration also requires a dry run, which wastes significant energy, is labor-intensive, and results in high calibration costs. Furthermore, the calibration thermocouples and connecting leads are installed directly inside the furnace, making thermal insulation difficult in high-temperature environments. Therefore, this method is difficult to use for calibrations above 1200°C.

[0008] The temperatures involved in heating furnaces are generally categorized based on industrial thermometric limits as medium (antimony-copper melting point: 631-1084°C), high (copper-palladium melting point: 1084-1554°C), and ultra-high (palladium melting point: 1554°C or higher). In industrial production, many materials, such as silicon carbide (SiC) and silicon nitride (Si3N4), are heat treated and sintered in furnaces exceeding 1554°C.

[0009] SiC ceramics possess exceptional properties, including high strength and hardness, high-temperature oxidation resistance, excellent wear resistance, excellent thermal stability and thermal shock resistance, low thermal expansion coefficient, high thermal conductivity, and chemical corrosion resistance. They have been widely used in fields such as metallurgy, automotive, machinery, environmental protection, aerospace technology, information electronics, and energy, becoming irreplaceable structural ceramics with excellent performance in many industrial sectors. Reaction sintering, a key method for the industrial production of SiC materials, offers advantages such as low sintering temperatures, minimal deformation and shrinkage, high density, and low cost. Reaction sintering typically requires a temperature of 1550-1650°C, and the actual sintering temperature significantly influences the grain size, structure, and properties of the final SiC ceramic.

[0010] Si3N4, a compound with extremely strong covalent bonds, plays an indispensable role in numerous high-end industries thanks to its exceptional properties, including high hardness, high strength, high-temperature resistance, wear resistance, oxidation resistance, and excellent chemical stability. In the aerospace sector, its lightweight and high-strength properties are used in the manufacture of aircraft engine components and wing structures, helping to reduce aircraft weight and improve flight performance and fuel efficiency. In the automotive industry, it is used in the manufacture of engine pistons, valves, turbocharger rotors, and other components, significantly improving engine thermal efficiency, reducing fuel consumption, and extending service life. In the electronics field, its high insulation and excellent thermal conductivity make it an ideal electronic packaging material and substrate material, effectively solving the heat dissipation issues of electronic devices and improving the stability and reliability of electronic equipment. In recent years, Si3N4 ceramic substrates have been recognized as the best overall ceramic material due to their excellent properties, including high hardness, high mechanical strength, high-temperature resistance and thermal stability, low dielectric constant and dielectric loss, and wear and corrosion resistance. They have been used in insulated gate bipolar transistor (IGBT) module packaging and are gradually replacing Al2O3 and AlN ceramic substrates. The sintering temperature of silicon nitride Si3N4 ceramics is usually above 1800℃. The actual sintering temperature has an important influence on the microstructure, mechanical properties and thermal conductivity of the ceramics.

[0011] Due to factors such as the equipment structure, it's difficult to achieve uniform temperature across the effective space of SiC and Si3N4 ceramic sintering furnaces. During use, the temperature distribution within the furnace can also change due to aging of the heating element and insulation materials. As temperature sensors and temperature controllers age, errors gradually increase, causing the temperature displayed and controlled by the system to deviate increasingly from the actual temperature. Therefore, confirming the actual temperature of the sintering furnace and detecting the uniformity of the temperature field have become key indicators for process quality control and sintering furnace equipment performance evaluation during the production of these materials, contributing to the stable production of ceramic materials with excellent overall performance.

[0012] Currently, there is no effective method for accurately calibrating the temperatures of these furnaces, which operate at temperatures exceeding 1554°C. This has led to urgent concerns among technical personnel regarding how to quickly and accurately calibrate the temperatures of these furnaces and accurately measure the actual temperatures of processed materials and workpieces in situ. Summary of the Invention

[0013] In order to solve the problems existing in the prior art, the present invention proposes a rare earth cobalt-rhenium doped temperature-controlled alloy and its preparation method and application, which can be used in ultra-high temperature environments.

[0014] n pure metals and alloys with non-spherical shapes and increasing melting points (e.g., the melting point difference between adjacent alloys is about 2-20°C) are grouped together. These melting points will cover a certain range, denoted as {T a(1) 、T a(2) ,…,Ta(n)}, where T a(1) ℃ represents the melting point of alloy a(1) with the lowest melting point in this group of metals, T a(n) ℃ represents the melting point of the alloy a(n) with the highest melting point in this group, T a(1) <T a(2) <T a(3) <…<T a(n-2) <T a(n-1) <T a(n) These alloys were placed in small containers and combined to form a device, labeled {T a(1) ~T a(n)}, place this device in a furnace where the real temperature needs to be detected. When the real furnace temperature is within the range covered by the melting points of these alloys, after these alloys placed in small containers have undergone the furnace heat process, the metals with a melting point lower than the real furnace temperature will melt and undergo obvious shape changes, such as alloys numbered 1, 2, ..., n-3 have undergone obvious shape changes and are spherical after melting; metals with a melting point higher than the real furnace temperature will not melt and their shapes will not change significantly, such as alloys numbered n-2, n-1, and n have not undergone obvious shape changes and are still non-spherical. Therefore, the real furnace temperature can be determined based on whether the shape of the alloy has changed significantly after use, that is, the real furnace temperature is [T a(n-3) ,T a(n-2) ]℃, this range depends on the difference in melting point temperature of adjacent alloys, and can be preferably controlled within 2-5℃, thus achieving accurate temperature measurement. The device is called an alloy temperature measuring device, and these alloys are called temperature measuring alloys. The alloy temperature measuring device is placed together with the materials and workpieces to be processed. The temperature measurement does not affect the normal production of the furnace. The actual temperature measurement of the materials and workpieces is achieved during the process or after the process is completed. This temperature measurement method is called in-situ temperature measurement, and the alloy temperature measuring device can easily achieve in-situ temperature measurement. The actual furnace temperature obtained by the above method is recorded as T z ℃, in the present invention, it is defined as T z =(T a(n-3) +T a(n-2) ) / 2. The above phenomenon can also be achieved by assembling the alloy temperature measuring device in descending order of alloy melting points without affecting the final effect.

[0015] If the furnace itself is equipped with a temperature measurement and control system, the maximum process temperature in the temperature control system is set to T s ℃, which is the process target temperature; during operation, the corresponding temperature measurement system will measure a maximum measurement temperature, recorded as T c ℃, under normal circumstances, these two values ​​should be very close, so it can be considered that T s =T c The actual furnace temperature value T obtained using the alloy temperature measuring device z and Ts 、T c There is a difference, T z -T s =T z -T c = ΔT, where ΔT°C is the temperature the system needs to compensate for. This achieves furnace temperature calibration. A device capable of this function is called an alloy temperature calibration device, and the alloy is called a temperature calibration alloy. The method of using an alloy temperature calibration device to calibrate furnace temperature is called an alloy temperature calibration method. Placing the temperature calibration device and the material to be processed together allows for calibration without affecting normal furnace production. This method achieves true material temperature calibration during or after the process is complete. This is called in-situ temperature calibration, and the alloy temperature calibration method of the present invention can achieve in-situ temperature calibration.

[0016] The temperature calibration alloy in the present invention can measure ambient temperature and is primarily used in alloy temperature calibration devices to achieve in-situ temperature calibration. When the temperature calibration alloy is used for temperature calibration, temperature measurement is also performed. Therefore, the concepts of "temperature measuring alloy" and "temperature calibration alloy" are considered synonymous in the present invention and can be used interchangeably. Similarly, in this application, "temperature calibration" and "temperature measurement" are generally interchangeable, and "alloy temperature measuring device" and "alloy temperature calibration device" are also interchangeable.

[0017] Cobalt-rhenium alloys, when the mass percentage of cobalt is between 100% and 0% by weight, and the mass percentage of rhenium is between 0% and 100%, form a homogeneous alloy with minimal difference in composition between the liquidus and solidus. Alloys within this composition range exhibit a specific melting point. The melting point gradually increases with increasing rhenium content, from 1494°C for pure cobalt to 3180°C for approximately pure rhenium. Therefore, cobalt-rhenium alloys have great potential as ultra-high temperature calibration alloys for calibrating industrial furnaces operating in the ultra-high temperature range, such as those used in sintering furnaces for SiC and Si3N4 ceramics.

[0018] When the inventor tried to use the temperature calibration alloy to accurately calibrate the temperature of the sintering furnace, he found that even if the temperature calibration device was strictly fixed at the same position in the sintering furnace and the sintering process settings were exactly the same, that is, T s 、T c Similarly, when the temperature is calibrated for multiple days and multiple batches, the measured actual temperature T z ℃ difference is large. Preliminary analysis found that T z The fluctuation of the value is related to the atmosphere pressure during the operation of the sintering furnace. After careful inspection, it was found that many factors affect the atmosphere pressure in this sintering furnace, including the amount of material loaded in each batch and even the operation of the furnace door seal by different workers. Further analysis found that the atmosphere pressure value in the furnace itself does not directly affect the melting point of the temperature-controlled alloy. Instead, it is the trace oxygen in the atmosphere that affects the melting point of the temperature-controlled alloy, thus causing T zThe value fluctuates; the oxygen partial pressure value in the atmosphere is usually directly related to the atmosphere pressure. The greater the atmosphere pressure, the greater the oxygen partial pressure. At this time, the melting point of the temperature-calibrating alloy changes significantly under the action of oxygen in the atmosphere, resulting in the inability to achieve accurate temperature calibration.

[0019] Professionals involved in heat treatment, sintering, and other processes generally know that trace amounts of oxygen are always present in the atmosphere within industrial furnaces. The main reasons are as follows: air consists of 78.08 vol% nitrogen, 20.95 vol% oxygen, 0.93 vol% argon, 0.038 vol% carbon dioxide, and 0.002 vol% of other gases. During the loading and unloading process, air enters the furnace chamber. Purging or vacuuming cannot completely remove this air, leaving a certain amount of air. Furthermore, workpieces, refractory materials, and insulation materials absorb oxygen from the air, which is released during heating. Industrial gases such as nitrogen, argon, and hydrogen can retain and mix with small amounts of air during production, storage, and transportation, leading to trace amounts of oxygen entering the furnace atmosphere. Over time, the sealing performance of industrial furnaces deteriorates and the wear of vacuum systems increases, which can also lead to a gradual increase in oxygen levels within the furnace atmosphere.

[0020] Therefore, when the atmosphere inside an industrial furnace is in a vacuum, inert, or reducing atmosphere, it contains a certain amount of oxygen. In other words, oxygen is ubiquitous; the only difference is the oxygen content, or the oxygen partial pressure. The inventors discovered that during use, the temperature-corrected alloy tends to absorb impurities such as oxygen from the furnace atmosphere. These impurities enter the alloy lattice, becoming interstitial or replacement atoms (which can be considered as absorbed and dissolved oxygen in the lattice), thus altering the alloy's melting point. For example, the eutectic temperature of cobalt and oxygen is 1451°C, and the mass percentage of oxygen in the eutectic is approximately 0.23% (see "Binary Alloy Phase Diagram and Interphase Crystal Structure," published by Central South University Press in 2009, ISBN: 9787811058314). Rhenium is a high-melting-point metal with a melting point of 3180°C, second only to tungsten. However, the melting point and boiling point of its oxide are very low. For example, the boiling points of rhenium dioxide, rhenium tetroxide, and rhenium heptoxide are 1363°C, 220°C, and 362°C, respectively.

[0021] The amount of dissolved oxygen that can be absorbed into the alloy lattice for a specific alloy composition depends on a variety of factors, including the temperature of the environment in which the alloy is located, the oxygen partial pressure, the alloy surface condition, the type and content of alloying elements, and the reaction time. This is a very complex process and is not explored in depth in this invention. For details on the results and mechanisms of the interaction between specific alloy systems and atmospheric oxygen, please refer to the relevant published literature.

[0022] After extensive research and temperature calibration practices, the inventors discovered that using the alloy temperature calibration method to accurately calibrate furnace temperature requires solving the following key issues: (1) the effect of trace oxygen in the furnace atmosphere on the melting point of the temperature calibration alloy; (2) the method used to determine whether the temperature calibration alloy has melted; and (3) the effect of changes in the atmosphere pressure in the industrial furnace on the temperature measuring device. Only by solving the above problems can the alloy temperature calibration method ensure temperature calibration accuracy and be widely used in the field of industrial furnace temperature calibration. The above three issues are mutually influential. When designing an alloy temperature calibration solution, the above three issues should be considered and solved as a whole to make the alloy temperature calibration technology solution more optimal and have wide applicability.

[0023] To overcome the effect of atmospheric oxygen on the melting point of the temperature-calibration alloy, existing technologies typically seal the alloy in a vacuum or protective gas-filled container to isolate the temperature-calibration alloy from the furnace atmosphere. This approach results in complex, bulky, and costly temperature measurement equipment, making it suitable only for certain furnaces with small pressure fluctuations. If the pressure of a high-temperature furnace fluctuates significantly during the process, the sealed temperature-calibration device can collapse or crack at high temperatures due to the large pressure fluctuations. For example, if a glass container is filled with the temperature-calibration alloy, the interior is evacuated and sealed, and then placed in the furnace, the sealed glass container may collapse when the furnace temperature exceeds 1000°C and the pressure exceeds 10 atmospheres, causing the temperature calibration to fail. SiC and Si3N4 ceramics typically sinter at temperatures above 1600°C. To achieve a nearly fully dense material, the furnace atmosphere pressure can sometimes reach as high as 100 bar. Under such harsh conditions, it is difficult to find suitable materials to seal the temperature-calibration alloy.

[0024] If the temperature measuring device is not sealed, the oxygen in the atmosphere outside the device can fully contact the temperature calibration alloy, and more oxygen will enter the matrix lattice of the temperature calibration alloy, which will greatly affect the melting point of the temperature calibration alloy, thereby resulting in low temperature calibration and measurement accuracy. Professional and technical personnel in this field are not fully aware that trace oxygen in the atmosphere inside the furnace will greatly affect the melting point of the temperature calibration alloy and affect the temperature calibration accuracy.

[0025] After extensive research, the inventors discovered that when trace amounts of oxygen in the atmosphere contact the surface of a cobalt-rhenium temperature-calibration alloy without other elements, the cobalt and rhenium elements in the alloy matrix are insufficiently active at high temperatures to secure the oxygen and form a second oxide phase. Consequently, the trace oxygen enters the alloy matrix lattice, becoming interstitial and replacing atoms, lowering the alloy's melting point. For example, the eutectic temperature of cobalt and oxygen is 1451°C, resulting in reduced temperature calibration accuracy. However, the addition of highly reactive rare earth elements (RE) to the cobalt-rhenium alloy effectively reduces and controls the adverse effects of atmospheric oxygen on the alloy's melting point during temperature calibration.

[0026] Formation enthalpy of metal oxides ΔH fIt is a physical quantity that reflects the stability of its oxide. The lower its value, the more stable it is. It also indicates that the metal element is more active and more likely to react with oxygen. Traditional (structural) steel usually uses active elements such as Mn, Si, and Al to remove oxygen from the steel liquid during smelting. For example, the oxygen content of silicon-deoxidized steel can reach 30×10 -6 The oxygen content of aluminum-deoxidized killed steel can reach 20×10 -6 Below; in order to further deoxidize, more active rare earth elements need to be added, such as cerium (Ce), lanthanum (La), yttrium (Y), etc. The deoxidation performance of these rare earth elements is much higher than that of aluminum.

[0027] The present invention has found that if a small amount of rare earth metal elements are added to the cobalt-rhenium temperature-controlled alloy, the rare earth can form intermetallic compounds with cobalt and rhenium, and mainly precipitate at the grain boundaries to form a dispersed and fine second phase. When trace oxygen in the atmosphere contacts the temperature-controlled alloy and enters the alloy matrix, the rare earth metal elements are more active than cobalt and rhenium elements, and RE m O n More stable than ReO2 and CoO (see Table 1), the formation enthalpies of Y2O3, ReO2, and CoO are -627kJ / mol, -213kJ / mol, and -239kJ / mol, respectively. At high temperatures, the rare earth elements in cobalt-rhenium alloys preferentially react with oxygen in the cobalt-rhenium lattice. Because rare earth elements have relatively large atomic radii (144-204pm), their solid solubility and diffusion rate in the cobalt-rhenium matrix are very low. At the same time, the atomic radius of oxygen is relatively small (66pm), making it easier for oxygen to diffuse into the alloy matrix. The rare earth elements at the grain boundaries capture oxygen that diffuses into the alloy from the atmosphere, forming a precipitate of fine rare earth oxide particles at the grain boundaries within the cobalt-rhenium alloy matrix, which acts as a purifier. The above principle is similar to the deoxidation principle in the production of killed steel. The difference is that rare earth is added to the cobalt-rhenium temperature-correcting alloy to control the amount of free oxygen in the cobalt-rhenium solid lattice before the temperature-correcting alloy is melted during use, so that the melting point of the cobalt-rhenium temperature-correcting alloy is not affected by oxygen in the atmosphere before melting.

[0028] Rare earth elements react with oxygen without reducing the cobalt and rhenium content in the cobalt-rhenium matrix, and will not affect the melting point of the cobalt-rhenium matrix; rare earth elements are very active and can reduce the free oxygen in the alloy matrix to below 5ppm (with such a low oxygen content, it can be assumed that oxygen will not affect the melting point of the alloy), eliminating the influence of oxygen in the lattice on the melting point of the cobalt-rhenium alloy and stabilizing the melting point of the temperature-calibrated alloy; fine rare earth oxides are mainly dispersed at the grain boundaries and will not form a dense and strong surface film. The melting point of rare earth oxides is above 2200°C, and they are stable at high temperatures. They will not dissolve or decompose in the alloy matrix, will not change the melting point of the matrix, will not affect the surface tension of the alloy when it melts and the wettability with the container, and thus will not affect the shape change of the alloy after melting, and can ensure the accuracy of temperature calibration.

[0029] Based on the above mechanism, adding rare earth elements to the cobalt-rhenium alloy can better solve the influence of oxygen in the atmosphere on the melting point of the temperature-controlled alloy.

[0030] Table 1 Formation enthalpy ΔH of solid oxides of metal elements such as RE, Co, and Re f (0.5 mol of oxygen is consumed)

[0031]

[0032] The data in Table 1 are quoted from the literature: DTA and Heat-flux DSC Measurements of Alloy Melting and Freezing: NIST Recommended Practice Guide, Special Publication 960-15. National Institute of Standards and Technology, Washington, DC, USA 2006.

[0033] The present invention discovered that when an alloy containing 2% by mass of rare earth is used for temperature calibration, the alloy will adhere strongly to the container wall regardless of whether the alloy is melted. This is because the container holding the rare earth-doped cobalt-rhenium temperature calibration alloy is itself made of oxides, such as zirconium oxide and aluminum oxide. RE is very active. The higher concentration of RE in the temperature calibration alloy will react violently with the container at high temperatures, seizing some of the oxygen in the container material to form complex oxides, causing the container to change color, reduce strength, a large amount of container material elements entering the temperature calibration alloy to change its melting point, and the temperature calibration alloy to strongly adhere to the container. Although temperature calibration alloys with a rare earth content higher than 2% can be used to achieve temperature calibration and measurement when low temperature calibration and measurement accuracy is required, the preferred rare earth content in the temperature calibration alloy should not exceed 2% by mass.

[0034] Rare earth metals rarely form interstitial or substitutional solid solutions with the cobalt-rhenium matrix, resulting in low solid solubility. However, rare earths, rhenium, and cobalt can form low-melting-point eutectic alloys. For example, the eutectic temperature of yttrium (Y) with cobalt at a mass percentage of approximately 72% by weight is approximately 735°C, while the eutectic temperature of rhenium with Y at a mass percentage of approximately 90% by weight is approximately 1450°C. Therefore, adding large amounts of rare earth metals significantly alters the melting point of the cobalt-rhenium matrix, reducing temperature calibration accuracy. The present invention found that ideal temperature calibration accuracy can be achieved by controlling the rare earth metal addition to within 1.5% by mass.

[0035] In addition, the RE content in the alloy cannot be too low. For example, if the mass percentage is lower than 0.005%, during use, the rare earth in the temperature calibration alloy is quickly consumed by oxygen and cannot continue to react with the oxygen in the atmosphere that enters the cobalt-rhenium alloy matrix lattice. These oxygens become lattice filling atoms and replacement atoms, which lowers the melting point of the alloy and reduces the temperature calibration accuracy.

[0036] After extensive research and alloy temperature calibration practice, the inventors found that the best rare earth incorporation mass percentage in the temperature calibration alloy is 0.005-1.5%, the second best rare earth incorporation mass percentage is 0.08-1.00%, the better rare earth incorporation mass percentage is 0.09-0.60%, and the optimal rare earth incorporation mass percentage is 0.10-0.35%.

[0037] During the development of this invention, it was discovered that the initial shape of a metal or alloy sample before temperature calibration can vary greatly. From a processing perspective, the sample shape primarily depends on the metal or alloy material and the sample preparation method. However, regardless of the significant difference in initial shape, the shape after melting and solidification is not necessarily related to the initial sample shape. The key factors determining the shape of the temperature-calibrated alloy sample after melting and solidification are the container material, container shape and size, and the amount of temperature-calibrated alloy sample used.

[0038] By selecting an appropriate container material, designing the container shape and size, and controlling the amount of alloy sample used, the final shape of the temperature-calibrated alloy sample after the melting-solidification process can be controlled, achieving a variety of shapes from simple to complex. The shape after temperature calibration can also be used to determine whether the alloy has melted, thereby obtaining the temperature information that needs to be calibrated. Among these feasible solutions, the inventors believe that designing a solution that controls the final shape of the temperature-calibrated alloy sample after melting and solidification to be spherical or quasi-spherical is a preferred solution, possibly the best solution. In this case: the amount of temperature-calibrated alloy sample used is small; the sample will eventually become spherical or quasi-spherical after melting, making it easier for technicians to determine whether the alloy has melted; the alloy will hardly stick to the container after melting, and the container can be reused after simple cleaning.

[0039] Based on the above principles of the present invention, after extensive experiments and optimized designs, the inventors have invented a better alloy temperature control device. The alloy temperature control device consists of a small container, a small container cover, a large container, a large container cover, and a temperature control alloy.

[0040] The material of the small container is selected based on the fact that no reaction occurs between the temperature-correcting alloy and the small container at high temperatures, or the reaction is very slight and does not affect the inherent melting point of the temperature-correcting alloy and the change in its morphology after melting. Therefore, the preferred container material is a high-temperature resistant oxide.

[0041] Furthermore, the small container can be shaped in any form that is easily processed and readily available, with a preferred shape being a cylindrical crucible with a lid. The large container should be shaped and sized to prevent multiple small containers from tipping over when stacked within it, and the large container should include a lid. The large container should be made of a high-temperature-resistant oxide ceramic or metal.

[0042] The shape of the temperature calibration alloy can be various non-spherical shapes that are easy to process and crush. Furthermore, the preferred shape is a short filament or thin sheet with any dimension less than 6 mm, which is convenient for distinguishing from the spherical shape that the alloy will become after melting due to the action of surface tension. This allows the operator to determine the temperature of the test position without the need for professional tools and professional knowledge, thereby achieving accurate temperature calibration.

[0043] Throughout the entire process of processing workpieces and products in industrial furnaces, the same process may require complex and variable atmospheres, such as low temperature, high temperature, and low temperature, as well as vacuum, low pressure, normal pressure, and high pressure. While using sealed vacuum or gas-filled protective seals on the temperature-calibrating alloy can protect it from trace oxygen in the external atmosphere, they cannot adapt to such complex pressure and temperature variations. For example, if the temperature measuring device is sealed and vacuumed at low temperatures, it may collapse and crack under high temperatures and high pressures, causing it to fail. If the temperature measuring device is sealed and gas-filled at low temperatures, it may expand and crack when the furnace is in a vacuum at high temperatures, causing it to fail. The alloy temperature calibration device of the present invention, during the processes of heating, cooling, pressurizing, etc., when there is a pressure difference between the small container and the large container, and between the large container and the external environment, the atmosphere can be exchanged between the two through the gap driven by the pressure difference, that is, the gas can enter and exit the container through the gap between the container and the cover, thereby achieving pressure balance between the atmosphere inside the container and the external atmosphere, avoiding damage to the alloy temperature calibration device of the present invention caused by changes in the pressure of the atmosphere inside the furnace, and solving the problem that the temperature calibration device is complicated and has narrow adaptability due to complete sealing, so that the alloy temperature calibration device of the present invention can achieve accurate temperature calibration and temperature measurement under various pressure conditions from negative pressure to positive pressure in a low-oxygen atmosphere, and can be widely used in the temperature calibration and temperature measurement of industrial furnaces.

[0044] For example, in a process, when the oxygen partial pressure is ≤400Pa, the absolute vacuum pressure is sometimes less than 0.001Pa, and the pressurized pressure sometimes exceeds 2500bar. Because the alloy temperature calibration device adopts the solution of the present invention, precise temperature calibration and temperature measurement can be achieved. If a completely sealed solution is adopted, it is difficult to find a suitable sealing material that can withstand the extreme changes in external high temperature and pressure without failure.

[0045] To ensure the lifespan of temperature sensors installed in industrial furnaces, facilitate material loading and unloading, and ensure sensor cleanliness, these sensors are typically located far from the materials and workpieces being processed. Furthermore, it is difficult to penetrate deep into the materials and workpieces. As a result, the temperatures measured by these sensors often deviate from the true temperatures of the materials and workpieces, with significant errors. The alloy temperature calibration device developed in this invention can be placed alongside, or even within, the materials and workpieces being processed. After the heating process is complete, the shape change of the calibration alloy can be used to determine the true temperature of the materials and workpieces in situ.

[0046] The above-mentioned alloy temperature calibration device and method are based on the use of an appropriate amount of temperature calibration alloy and a suitable container shape design, so that the alloy melts and becomes spherical under the action of surface tension, thereby achieving temperature calibration and temperature measurement functions. If the amount of temperature calibration alloy used is large and the volume of the small container is small, the amount of liquid after the temperature calibration alloy melts exceeds the amount required to fill the entire bottom of the small container. In this case, the shape of the temperature calibration alloy after melting and solidification depends on the shape of the bottom of the small container. In this case, based on the state of filling the bottom of the container after solidification, it can also be determined whether the temperature calibration alloy is melted, thereby achieving the temperature calibration and temperature measurement purposes solved by the present invention.

[0047] Based on the above principles, the present invention has the following beneficial effects:

[0048] (1) A small amount of active rare earth metal elements is added to the cobalt-rhenium temperature-calibration alloy to solve the problem that the melting point is easily affected by oxygen in the atmosphere. It has high temperature calibration accuracy and wide adaptability.

[0049] (2) The amount of temperature calibration alloy used is small; after the alloy is melted, it does not wet the container but spheroidizes. Whether the alloy is melted can be judged intuitively based on whether the alloy is spheroidized, without the need for other detection methods.

[0050] (3) The alloy temperature calibration device formed by assembling the temperature calibration alloy and large and small containers with lids does not require vacuum or inert gas packaging. The pressure inside the container and the pressure inside the furnace can be freely balanced, and the speed at which oxygen in the external environment atmosphere diffuses into the alloy temperature calibration device is controlled, making it suitable for industrial furnace temperature calibration and temperature measurement under various pressure conditions with oxygen partial pressure ≤400Pa.

[0051] (4) The alloy temperature calibration device is small and not affected by other factors, and can realize in-situ temperature calibration and temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0053] Figure 1 This is a schematic diagram of the cross-sectional structure of an alloy temperature calibration device provided by the present invention.

[0054] Figure 2 This is a partial enlarged view of the cross-sectional structural diagram of an alloy temperature calibration device provided by the present invention.

[0055] Figure 3 This is a schematic diagram of the cross-sectional structure of an alloy temperature calibration device provided by the present invention after use.

[0056] Figure 4 This is the SEM of the ECR-13 alloy sample after the P1633-20-40 atmosphere sensitivity evaluation in Example 1 of the present invention.

[0057] Figure 5 This is the surface micro-SEM of the ECR-13 alloy sample after the P1633-20-40 atmosphere sensitivity evaluation in Example 1 of the present invention.

[0058] Figure 6 This is the surface micro-SEM of the ECR-13 alloy sample after the P1633-20-40 atmosphere sensitivity evaluation in Example 1 of the present invention. Figure 5 Surface energy spectrum analysis results of the middle 1# area.

[0059] Figure 7 This is the surface micro-SEM of the ECR-13 alloy sample after the P1633-20-40 atmosphere sensitivity evaluation in Example 1 of the present invention. Figure 5 Surface energy spectrum analysis results of the middle 2# area.

[0060] In the figure, 1-small container, 2-small container cover, 3-large container, 4-large container cover, 5-temperature-calibrating alloy, 6-alloy temperature-calibrating device, 7-space one, 8-space two, 9-outside of alloy temperature-calibrating device, 10-gap structure one, 11-gap structure two.

[0061] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0062] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0063] According to the above principles of the present invention, after a lot of experiments and optimization design, the inventors invented a better alloy temperature control device, such as Figure 1 shown. Figure 1 This is a schematic diagram of the cross-sectional structure of this preferred alloy temperature calibration device. The alloy temperature calibration device 6 consists of a small container 1, a small container cover 2, a large container 3, a large container cover 4, and a temperature calibration alloy 5. Figure 1 The cross-sectional structural diagram of the alloy temperature-regulating device shown is only an example of the alloy temperature-regulating device structure proposed in the present invention. Its purpose is only to intuitively demonstrate the components of the alloy temperature-regulating device of the present invention. The actual alloy temperature-regulating device structure can be optimized according to the principles of the present invention.

[0064] The material of the small container is selected based on the fact that no reaction occurs between the temperature-correcting alloy 5 and the small container 1 at high temperatures, or the reaction is very slight and does not affect the inherent melting point of the temperature-correcting alloy and the change in its morphology after melting. Therefore, the preferred container material is a high-temperature resistant oxide, such as zirconium oxide, yttrium oxide, cerium oxide, lanthanum oxide, etc.; at the same time, the molten liquid of the temperature-correcting alloy 5 should not be completely wetted with the container, that is, the contact angle is greater than 60°, preferably greater than 90°, and most preferably greater than 110°, to ensure that it becomes spherical or quasi-spherical under the action of surface tension after melting.

[0065] Furthermore, the small container 1 can be shaped in a variety of easily machined and readily available shapes, with a preferred shape being a cylindrical crucible with a lid. Furthermore, the dimensions of the small container 1 can be minimized while still meeting the requirements of its intended use. A preferred volume of the small container 1 is 50-250 μL. After the temperature calibration alloy 5 is placed, the total volume of space 7 (space 7 being the remaining space after the small container and lid are added, minus the volume of the contained temperature calibration alloy) is small, thereby minimizing the amount of oxygen contained in space 7. This allows the total gas volume contained in the small container 1 to be less than 200 μL. During the temperature calibration process, the rare earth elements in the temperature calibration alloy 5 consume oxygen from the atmosphere, creating a localized, nearly oxygen-free environment within the small container 1.

[0066] The shape and size of the large container 3 should ensure that multiple small containers 1 stacked therein do not tip over, and the large container 3 must be equipped with a large container lid 4. Furthermore, the large container 3 can be shaped in a variety of easily machined and readily available forms, with a preferred shape being a cylindrical crucible with a lid. Furthermore, the preferred dimensions of the large container 3 are: its inner diameter is 1-6 mm larger than the outer diameter of the small containers 1. This creates a relatively small space 8 (space 8 being the remaining space after deducting the total volume of all small containers with lids contained within the large container after adding the lid), while also facilitating the stacking and removal of small containers 1 within the large container 3. The large container 3 should be made of a high-temperature-resistant oxide ceramic or metal.

[0067] The shape of the temperature calibration alloy 5 can be various non-spherical shapes that are easy to process and crush. Furthermore, the preferred shape is a short filament or thin sheet with any dimension less than 6 mm, which is convenient for distinguishing from the spherical shape that the alloy will become under the action of surface tension after melting. This allows the operator to determine the temperature of the test position without professional tools and professional knowledge, thereby achieving accurate temperature calibration.

[0068] Furthermore, the volume of the rare earth cobalt-rhenium doped ultra-high temperature temperature-correcting alloy placed in the small container 1 should be 1 / 20-1 / 2 of the volume of the small container 1, ensuring that the temperature-correcting alloy 5 placed in the small container 1 will not occupy the entire bottom of the small container 1 after melting, so that the temperature-correcting alloy 5 forms a spherical or quasi-spherical shape under the action of surface tension after melting. In the subsequent process, this shape will be maintained, especially after cooling down, it can still maintain the spherical or quasi-spherical shape.

[0069] Adding active rare earth metals to the temperature-calibration alloy can control the amount of oxygen absorbed from the external atmosphere and dissolved in the alloy matrix lattice, thus unaffecting the alloy matrix's melting point. However, there is an upper limit to the amount of rare earth metals permitted in the alloy matrix. Over time, the rare earth metals in the temperature-calibration alloy may be completely consumed by the atmospheric oxygen. Furthermore, if the oxygen content in the space 7 in contact with the temperature-calibration alloy can be reduced relative to the ambient atmosphere outside the entire alloy temperature-calibration device 9, the amount of oxygen entering the alloy matrix lattice from this atmosphere can be reduced, achieving a similar function to that of rare earth metal doping, or equivalently, adding more rare earth metals to the alloy matrix. Furthermore, if the oxygen content (oxygen partial pressure) in the space 7 in contact with the temperature-calibration alloy can be reduced to an extremely low level, the alloy matrix will no longer absorb dissolved oxygen from the atmosphere, effectively eliminating any effect of atmospheric oxygen on the alloy matrix's melting point.

[0070] right Figure 1 The partial structure in the cross-sectional structural diagram of the alloy temperature calibration device provided by the present invention is partially enlarged, and the partial structure enlarged diagram is as follows: Figure 2 As shown, the gap structure 10 is formed by the small container 1 and the small container cover 2; the gap structure 2 11 is formed by the large container 3 and the large container cover 4. Figure 2 From the gap structure 10, it can be seen that after the small container 1 is covered with the small container cover 2, there is still a slight gap between the two; Figure 2 From the gap structure 11, it can be seen that after the large container 3 is covered with the large container cover 4, there is also a slight gap between the two.

[0071] In such Figure 1In the illustrated alloy temperature-calibration device 6, after the temperature-calibration alloy 5 is placed, the volume of space 1 (7) is small. The active rare earth elements in the temperature-calibration alloy absorb trace oxygen in the atmosphere of space 1 (7) to form rare earth oxides, resulting in an extremely low oxygen content in the atmosphere of space 1 (7). The oxygen concentration in the ambient atmosphere 9 outside the alloy temperature-calibration device is relatively high, while the oxygen concentration in space 2 (8) is relatively low, and the oxygen concentration in space 7 is the lowest. This oxygen concentration gradient exists between the two. The higher concentration of oxygen in the ambient atmosphere outside the alloy temperature-calibration device 9 must first diffuse through gap structure 2 (11) into space 2 (8), then through gap structure 1 (10) before slowly diffusing into the interior of small container 1, ultimately having a chance to enter the temperature-calibration alloy matrix. Compared to direct contact between the alloy and the external ambient atmosphere, this oxygen diffusion process takes longer due to high resistance. Even if some oxygen does enter the temperature-calibration alloy matrix, the rare earth metal elements in the temperature-calibration alloy react with oxygen in the crystal lattice to form a stable high-melting-point oxide precipitate. This ensures that the melting point of the temperature-calibration alloy is not affected by trace oxygen in the furnace atmosphere for a long period of time during use, thus ensuring temperature calibration accuracy.

[0072] Throughout the entire process of processing workpieces and products in industrial furnaces, the same process may require complex and variable atmospheres, such as low temperature, high temperature, and low temperature, as well as vacuum, low pressure, normal pressure, and high pressure. While using sealed vacuum or gas-filled protective seals on the temperature-calibrating alloy can protect it from trace oxygen in the external atmosphere, they cannot adapt to such complex pressure and temperature variations. For example, if the temperature measuring device is sealed and vacuumed at low temperatures, it may collapse and crack under high temperatures and high pressures, causing it to fail. If the temperature measuring device is sealed and gas-filled at low temperatures, it may expand and crack when the furnace is in a vacuum at high temperatures, causing it to fail. The alloy temperature calibration device of the present invention has gap structure 10 and gap structure 2 11. During the heating, cooling, pressurization and other processes, when there is a pressure difference between the small container 1 and the large container 3, and between the large container 3 and the external environment, the atmosphere can be exchanged through the gap driven by the pressure difference, that is, the gas can enter and exit the container through the gap between the container and the cover, thereby achieving pressure balance between the internal atmosphere of the container and the external atmosphere, avoiding damage to the alloy temperature calibration device of the present invention caused by changes in the internal atmosphere pressure of the furnace, and solving the problem that the temperature calibration device is complicated and has narrow adaptability due to complete sealing, so that the alloy temperature calibration device 6 of the present invention can achieve accurate temperature calibration and temperature measurement under various pressure conditions from negative pressure to positive pressure in a low-oxygen atmosphere, and can be widely used in the temperature calibration and temperature measurement of industrial furnaces.

[0073] For example, in a process, when the oxygen partial pressure is ≤400Pa, the absolute vacuum pressure is sometimes less than 0.001Pa, and the pressurized pressure sometimes exceeds 2500bar. Because the alloy temperature calibration device adopts the solution of the present invention, precise temperature calibration and temperature measurement can be achieved. If a completely sealed solution is adopted, it is difficult to find a suitable sealing material that can withstand the extreme changes in external high temperature and pressure without failure.

[0074] To ensure the lifespan of temperature sensors installed in industrial furnaces, facilitate material loading and unloading, and ensure sensor cleanliness, these sensors are typically located far from the materials and workpieces being processed. Furthermore, it is difficult to penetrate deep into the materials and workpieces. As a result, the temperatures measured by these sensors often deviate from the true temperatures of the materials and workpieces, with significant errors. The alloy temperature calibration device developed in this invention can be placed alongside, or even within, the materials and workpieces being processed. After the heating process is complete, the shape change of the calibration alloy can be used to determine the true temperature of the materials and workpieces in situ.

[0075] The alloy temperature calibration device and method described above utilizes an appropriate amount of temperature calibration alloy and a suitable container shape, allowing the alloy to melt and become spherical due to surface tension, thus achieving temperature calibration and temperature measurement. If a large amount of temperature calibration alloy 5 is used and the volume of the small container 1 is small, the amount of liquid in the melted temperature calibration alloy 5 exceeds the amount required to fill the entire bottom of the small container 1. In this case, the shape of the temperature calibration alloy 5 after melting and solidification will be determined by the shape of the bottom of the small container 1. In this case, the melting of the temperature calibration alloy can also be determined based on how much it fills the bottom of the container after solidification, thus achieving the temperature calibration and measurement purposes addressed by the present invention.

[0076] Based on the above principles, the detailed implementation process of the present invention is summarized as follows:

[0077] According to the first aspect of the present invention, the present invention provides the following technical solutions:

[0078] A rare earth cobalt-rhenium doped ultrahigh temperature temperature-regulating alloy comprises, by mass percentage, 0-99.995wt% of Co, 0.005-1.5wt% of RE, and the balance being Re and unavoidable impurity elements.

[0079] Specifically, the mass percentage of Co in the rare earth cobalt-rhenium ultrahigh temperature temperature-correcting alloy can be any one of 0wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, 99.995wt% or the range between any two of them; The mass percentage of RE in the cobalt-rhenium ultrahigh temperature temperature-correcting alloy can be any one of 0.005wt%, 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, or the range between any two of them.

[0080] As a preferred embodiment of the rare earth cobalt-rhenium doped ultra-high temperature temperature-regulating alloy described in the present invention, the rare earth cobalt-rhenium doped ultra-high temperature temperature-regulating alloy has a fixed melting point (i.e., the melting point of the rare earth cobalt-rhenium doped ultra-high temperature temperature-regulating alloy with a fixed composition is fixed, and its melting point is determined by the composition of the alloy), and its melting point range is 1494-3180°C.

[0081] As a preferred embodiment of the rare earth cobalt-rhenium-doped ultra-high temperature temperature-controlled alloy described in the present invention, RE is one or any combination of at least two of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

[0082] The four rare earth elements (samarium, europium, thulium, and ytterbium) have relatively high vapor pressures (see Table 2 for specific data). When these elements are added to prepare a rare earth-doped cobalt-rhenium ultrahigh-temperature calibration alloy and used to calibrate ultrahigh-temperature furnaces, these rare earth elements volatilize strongly at high temperatures, causing a sharp drop in the rare earth content in the alloy and reducing the accuracy of the calibration alloy. The most preferred embodiment of the rare earth-doped cobalt-rhenium calibration alloy described herein comprises: RE, which is one or any combination of at least two of lanthanum, cerium, praseodymium, neodymium, promethium, gadolinium, terbium, dysprosium, holmium, erbium, lutetium, scandium, and yttrium.

[0083] Table 2 Melting point, boiling point, vapor pressure and melting point of corresponding oxides of RE, Co, Re metal elements

[0084]

[0085] As a preferred embodiment of the rare earth cobalt-rhenium temperature-calibration alloy described in the present invention, the rare earth in the rare earth cobalt-rhenium temperature-calibration alloy can react with oxygen in the alloy lattice to form a stable high-melting-point oxide precipitate, thereby ensuring that the melting point of the temperature-calibration alloy is not affected by trace oxygen in the atmosphere inside the furnace during use, thereby ensuring the temperature calibration accuracy.

[0086] According to the second aspect of the present invention, the present invention provides the following technical solutions:

[0087] A method for preparing the above-mentioned rare earth cobalt-rhenium doped ultrahigh temperature temperature-controlled alloy comprises:

[0088] Step 0: Based on the target melting point, formulate a rare earth cobalt-rhenium ultrahigh temperature calibration alloy formula, and record the formula number as x.

[0089] Step 1: According to the requirements of recipe x, weigh the required amount of cobalt, rhenium, and rare earth raw materials by mass percentage. The purity of the cobalt and rhenium raw materials must be above 99.99%. The shapes are not limited; preferred shapes for easy smelting include granules, blocks, and flakes. The purity of the rare earth raw materials must be above 99.5%. Preferred shapes for easy smelting include the corresponding rare earth hydride powders, rare earth granules, or rare earth cobalt master alloys.

[0090] Step 2: Melt the cobalt, rhenium, and rare earth raw materials to alloy and homogenize them, producing a rare earth-doped cobalt-rhenium alloy ingot a(x). If the raw materials are in powder form, weigh Co, Re, and RE (e.g., rare earth hydride, in powder form) according to the specified composition ratio. Mix the weighed raw powders in a clean container. To avoid contamination from vigorous mixing, manually mix them. Pour the mixed raw powders into a pressing mold with an inner diameter of 40-60 mm and press them into a rough pressed blank. If necessary, this operation can be performed under inert gas. The pressed rough billet is then pre-sintered: the pressed rough billet is placed in a melting crucible of a vacuum induction melting furnace, the vacuum induction melting furnace lid is covered, the vacuum induction melting furnace control panel and the air inlet valve are operated to perform vacuum and gas washing operations, and the air in the furnace cavity of the vacuum induction melting furnace is replaced with argon gas of a purity of 5N or above. Finally, the vacuum is evacuated to a vacuum degree below 10Pa, and the power is slowly increased to heat the pressed rough billet in the melting crucible until a tendency of the pressed rough billet to melt into a mass is observed. The power is then slowly adjusted to 0, and the temperature of the melting furnace is waited for to drop to room temperature. The pre-sintered billet with a certain strength is taken out from the melting crucible; or the pressed rough billet is kept warm at about 1400°C for 60 minutes under vacuum or argon atmosphere in a heat treatment furnace or sintering furnace to be made into a pre-sintered billet with a certain mechanical strength.

[0091] Open the front door of the vacuum chamber of the high vacuum arc melting furnace, place the pre-sintered blank in the casting and melting crucible tank of the high vacuum arc melting furnace, close the front door of the vacuum chamber. Turn on the vacuum pump and vacuum gauge, and perform vacuum purge operation on the vacuum chamber. Wait until the required vacuum degree is reached (10 -4 Pa), turn off the vacuum pump and vacuum gauge, open the inlet valve, and fill with argon gas of 5N purity or higher until the vacuum reading reaches -0.05 to -0.02 MPa. Then close the inlet valve. Repeat the vacuum purge operation three times. Then, turn on the arc starting power supply and adjust the current to approximately 200-250A. Use the lifting handle to move the tungsten needle to a height of 3-5mm above the upper surface of the pre-sintered blank. Press the "arc start" button and control the handle to move the arc back and forth toward the pre-sintered blank sample. Once the sample is completely melted, use the left handle of the vacuum chamber to tilt it forward and pour the molten sample from the casting crucible into the casting mold, controlling the casting time to less than 10 seconds. After casting, wait for the sample to completely cool before removing it to obtain a rare earth-doped cobalt-rhenium alloy ingot. To obtain an ingot with uniform microstructure, repeat the above melting process 3-5 times, ultimately obtaining a rare earth-doped cobalt-rhenium alloy ingot a(x).

[0092] Melting methods are not limited to the vacuum arc melting method described above; other methods, such as levitation melting and vacuum induction furnace melting, can also be used to melt the alloy. The goal of melting is to melt rhenium, cobalt, and rare earth elements at high temperatures to form a microscopically uniform alloy. High-purity raw materials are also required, and the melting atmosphere must be carefully controlled to minimize impurities such as oxygen and nitrogen. This reduces rare earth loss during smelting and reduces the impurity content of the final alloy. To reduce oxygen in the alloy and improve the rare earth yield in the ingot, a rapid flow of dry hydrogen can be introduced below 800°C during the preparation of the pre-sintered billet.

[0093] It is generally known to those skilled in the art of smelting that during the smelting process of alloys such as steel, a certain amount of RE is sometimes intentionally added for purification. The purifying effect of rare earths during alloy smelting is primarily manifested in a profound reduction in the contents of oxygen and sulfur, and can also reduce the contents of low-melting-point elements such as phosphorus, hydrogen, arsenic, tin, antimony, bismuth, and lead. When smelting the rare earth-doped cobalt-rhenium temperature-correcting alloy of the present invention, the added rare earths also have a similar effect, purifying and reducing the impurity elements in the cobalt-rhenium temperature-correcting alloy, particularly having significant deoxidation and desulfurization effects, which is beneficial for making the melting point of the cobalt-rhenium temperature-correcting alloy more stable.

[0094] Step 3: Annealing the smelted alloy ingot a(x) in a vacuum atmosphere, an inert atmosphere, or a hydrogen atmosphere to further homogenize the alloy. The maximum holding temperature during the annealing process can be 20-400°C below the melting point of the ingot a(x), and the holding time is not limited. The annealing temperature is typically controlled at 30-200°C below the melting point, preferably 30-150°C below, and optimally 50-100°C below. The holding time is typically 2-48 hours, preferably 4-24 hours, and optimally 6-12 hours.

[0095] Step 4: Using machining equipment to remove the surface layer of the alloy ingot a(x) after annealing and homogenization treatment, which is thicker than 1 mm and contains a lot of impurities and is easily dirty, to obtain a pure and uniform alloy ingot a(x).

[0096] Step 5: Process the pure and uniform alloy ingot a(x) into a wire or sheet, and use a shearing tool or equipment to break the wire or sheet alloy into short wires or thin sheets with any dimension less than 6 mm to obtain a usable rare earth cobalt-rhenium doped ultra-high temperature temperature-controlled alloy a(x).

[0097] In steps 4 and 5, coolant and other media are not used during machining to avoid introducing impurities that could contaminate the alloy. The machining speed must be controlled to prevent the alloy from overheating and causing severe oxidation. When shearing tools or equipment are used to break the alloy, care must also be taken to avoid contamination from other foreign impurities.

[0098] Step 6: Measure the melting point of rare earth cobalt-rhenium-doped temperature-calibrated alloy a(x). The melting point of alloy a(x) is determined using methods well known to those skilled in the art, such as using a DSC thermal analyzer. The specific method is as follows:

[0099] The melting points of the calibration alloys were measured using a SETARAM THEMYS thermal analyzer (using a W5-type DTA stand, with a maximum operating temperature of 2400°C). The shielding and carrier gases used were 99.999% pure argon. After passing through a gas purification system, the oxygen content in the argon was maintained below 1 ppm. A trace oxygen analyzer monitored the oxygen content in the gas system in real time. The argon flow rate was 20 mL / min, the heating rate was 10 K / min, and a high-purity zirconia crucible was used. The thermal analyzer was calibrated according to ASTM E967 using pure palladium, platinum, and rhodium with a purity of at least 99.999%. According to the ITS-90 International Temperature Scale, the melting points of high-purity palladium, platinum, and rhodium are 1554°C, 1772°C, and 1963°C, respectively.

[0100] When measuring the melting point of rare earth cobalt-rhenium temperature calibration alloy a(x), take 15-20 mg of alloy sample each time, measure 3 times according to ASTM E794 standard, take the average value as the melting point of the alloy being tested, and use Ta(x) Indicated in ℃.

[0101] Step 7: Use the "temperature calibration alloy atmosphere sensitivity evaluation program" developed by the present invention to evaluate the sensitivity of the melting point of the rare earth cobalt-rhenium temperature calibration alloy a(x) to oxygen in the atmosphere. The specific evaluation method is as follows:

[0102] The sensitivity of the temperature-calibrated alloy to the atmosphere was evaluated using a SETARAM THEMYS thermal analyzer (with a Pt-Rh6% / 30% alumina protected DTA holder and a maximum operating temperature of 1750°C). During the measurement, the protective gas and carrier gas sources were argon. After passing through a gas purification system or an oxygenation system, the oxygen content in the argon gas can be adjusted in the range of less than 1ppm to 500ppm. A trace oxygen analyzer was provided in the gas system to monitor the oxygen content in the gas in real time. During the measurement, the ASTM E794 standard was followed. The alloy sample weighed 15-20 mg and was loaded into an uncovered high-purity zirconia crucible. The sample was calcined at 1400°C in clean air for 3 hours before use. The argon flow rate was 30mL / min, and the oxygen content in the argon gas was controlled at E ppm. The temperature was raised from room temperature to T at a rate of 30°C / min. h °C, at T h ℃ for a certain time S min, so that the alloy sample and the oxygen in the argon atmosphere can fully react at a temperature close to the melting point of the alloy, in order to evaluate the sensitivity of the alloy melting point to oxygen; then the temperature is raised to (T h +80)℃, measure the melting point of the alloy; at (T h Keep the temperature at +80)℃ for 5 minutes, then cool directly to 50℃. End the measurement, remove the crucible and sample from the thermal analyzer, and observe whether the sample is spherical and the surface color. The above evaluation method is marked as PT h -ES, such as P1054.5-5-20, where 1054.5 means the holding temperature is 1054.5°C, 5 means the oxygen content in the argon is 5 ppm, and 20 means the holding time is 20 min.

[0103] The melting point temperature of alloy a(x) measured under the above conditions is recorded as T a(x) [PT h -ES]℃. When evaluating the atmosphere sensitivity of a specific alloy, such as alloy a(x), (T h +30)℃ is usually equal to or close to the melting point of the alloy T a(x) ℃; E represents the oxygen content in argon gas. When testing, select 0, 5, 20 ppm, etc. The larger the value, the greater the oxygen content in the atmosphere. "0" means that the oxygen content in the atmosphere is zero during measurement (strictly speaking, the oxygen content should be extremely low), that is, the oxygen content of the purified argon gas before entering the thermal analyzer is less than 0.5 ppm; S represents the oxygen content in the atmosphere at T h℃ holding time, usually 20, 40 minutes, etc. are selected. The larger the value, the longer the time the temperature-controlled alloy reacts with oxygen in the atmosphere when the temperature is close to the melting point but not melted.

[0104] Before the formal measurement, the DTA thermal analyzer temperature was calibrated according to ASTM E967 standard using palladium, platinum, and rhodium with a purity of more than 99.999% to ensure the accuracy of melting point measurement.

[0105] Measure three times under the same conditions and take the average value as the melting point of the alloy under the above conditions, which is recorded as T a(x) [PT h -ES]℃, and the normal melting point of the alloy T a(x) ℃, compare the deviation values, and evaluate the sensitivity of the alloy to oxygen in the atmosphere.

[0106] After the alloy specimens have undergone the above-mentioned atmosphere sensitivity evaluation measurement, if necessary, especially when obvious oxidation phenomena are observed on the specimen surface, a scanning electron microscope (SEM) can be used to confirm the microscopic state of the specimen surface, and an energy dispersive X-ray spectroscopy (EDS) can be used to analyze the surface composition.

[0107] According to the third aspect of the present invention, the present invention provides the following technical solutions:

[0108] A temperature calibration and temperature measurement method using the above-mentioned rare earth-doped cobalt-rhenium temperature calibration alloy comprises the following steps:

[0109] Step 1: Estimate the ambient temperature range of the location where the temperature needs to be calibrated and measured, and determine the lower limit of the temperature range as T min ℃, the upper limit temperature is T max ℃, if it is estimated that the ambient temperature range of the temperature measurement location where temperature calibration is required may be 1630-1670℃, then T min ℃=1630℃、T max ℃=1670℃.

[0110] Step 2: According to the temperature calibration and temperature measurement accuracy requirements, select n rare earth cobalt-rhenium temperature calibration alloys with increasing melting points. The lowest melting point of these alloys is T a(1) ℃, the highest melting point is T a(n) ℃, T a(1) <T a(2) <T a(3) <…<T a(n-2) <T a(n-1) <T a(n) , T a(1) <1630, T a(n) >1670. Alloys can also be arranged in descending order of melting point without affecting the final temperature calibration and measurement results.

[0111] Step 3: Take appropriate amounts of n temperature-calibrating alloys with different melting points selected in step 2 and place them in n small containers. Each small container is covered with a container lid. Then, the small containers (containing alloys) are stacked in a large container in the order of increasing or decreasing melting point temperature of the alloys. The large container is covered with a container lid to assemble an alloy temperature-calibrating device. a(1) ~T a(n)},like Figure 1 shown.

[0112] Step 4: Place the single or multiple alloy temperature calibration devices {T a(1) ~T a(n) Placed at the point in the equipment where temperature calibration and measurement are required. The alloy temperature calibration device can be placed together with the material to be processed, or if necessary, placed inside the material for in-situ temperature calibration.

[0113] Step 5: Set the heating program according to the normal production process requirements and start the equipment to enter the operating state. If the equipment has its own temperature measurement and control system, set the maximum process temperature T s ℃, the highest temperature measured is T c ℃.

[0114] Step 6: After the equipment cools down to room temperature, take out the alloy temperature calibration device, observe the state of the temperature calibration alloy, and determine the actual temperature T where the alloy temperature calibration device is located. z ℃, such as Figure 3 As shown. The actual temperature T z Determined by:

[0115] If it is observed that the alloy temperature calibration device {T a(1) ~T a(n) Alloys numbered 1, 2, ..., n-3 melt into spheres, while alloys n-2, n-1, and n remain unmelted and in their original flake form. Determine the true temperature T at this location. z ℃ in [T a(n-3) ,T a(n-2) ]℃, in the present invention, it is considered that T z =(T a(n-3) +T a(n-2) ) / 2.

[0116] For example, 6 temperature-calibrating alloys with increasing melting points are placed in a small container and stacked in a large container according to their melting points from low to high. Figure 1 As shown, the alloy temperature calibration device {T a(1) ~T a(6) The device is placed in the furnace where temperature calibration and temperature measurement are required. After the heat process, the alloy temperature calibration device is taken out to determine the melting state of the alloy in the small container. The cross-sectional structure diagram of the alloy temperature calibration device after use is shown in the figure below. Figure 3 As shown, from Figure 3It can be found that three alloys a(1), a(2), and a(3) melted and spheroidized, while three alloys a(4), a(5), and a(6) did not melt and their shapes did not change significantly, so the true temperature value T was determined. z =(T a(3) +T a(4) ) / 2.

[0117] Step 7: The highest temperature T is measured by the temperature measurement system of the device according to Steps 5 and 6. c ℃ and the actual temperature T where the alloy temperature calibration device is located z ℃, we can get a temperature difference ΔT = T z -T c , ΔT℃ is the temperature that the equipment needs to compensate for. The equipment temperature is adjusted according to ΔT, such as setting process temperature compensation or performing maintenance on the furnace.

[0118] After use, the alloy temperature calibration device can be reused if the containers and container covers are not damaged and are cleaned.

[0119] As a preferred solution of the present invention for using the rare earth cobalt-rhenium temperature calibration alloy for temperature calibration and temperature measurement, the rare earth cobalt-rhenium temperature calibration alloy can be used for temperature calibration and temperature measurement in a low oxygen atmosphere with an oxygen partial pressure of ≤400Pa.

[0120] As a preferred embodiment of the present invention for using a rare earth cobalt-rhenium-doped temperature calibration alloy for temperature calibration and measurement, the low-oxygen atmosphere includes a vacuum atmosphere, an inert gas atmosphere, and a reducing atmosphere. Preferably, the low-oxygen atmosphere includes a vacuum atmosphere, an inert gas atmosphere (inert gases refer to Group 0 elements on the periodic table, including helium, neon, argon, krypton, xenon, and radon), and a reducing atmosphere (such as hydrogen). Further preferably, the low-oxygen atmosphere refers to an atmosphere with an oxygen partial pressure of ≤200 Pa. The atmosphere pressure can range from negative to positive, such as an absolute pressure of less than 0.001 Pa in a vacuum furnace and exceeding 2000 bar in a hot isostatic pressing furnace.

[0121] Compared with the prior art, the temperature calibration and temperature measurement method using the rare earth cobalt-rhenium doped temperature calibration alloy of the present invention has the following characteristics:

[0122] (1) The comprehensive cost of temperature calibration and temperature measurement is low: the alloy temperature calibration device does not require vacuum or protective gas sealing. After use, the small and large containers in the alloy temperature calibration device can be reused many times after cleaning, and the temperature calibration and temperature measurement process does not require interruption of normal production work of the equipment.

[0123] (2) Temperature calibration and measurement are simple: The temperature measuring device has a simple structure. The temperature calibration and measurement process does not require loading and unloading thermocouples, installing temperature measuring devices, or other complicated operations. The temperature calibration and measurement data can be obtained by visually observing whether the temperature calibration alloy is melted and spheroidized. The temperature calibration and measurement process can be carried out together with normal production to achieve in-situ temperature calibration and measurement.

[0124] (3) Wide applicability of temperature calibration and temperature measurement: The rare earth in the rare earth-doped cobalt-rhenium temperature calibration alloy can absorb oxygen in the atmosphere of the alloy temperature calibration device, so that the oxygen content in the atmosphere of the small container of the alloy temperature calibration device is lower than that of the external environment. At the same time, the small container with a lid and the large container with a lid slow down the diffusion of oxygen from the environment into the small container, so that the temperature calibration alloy in the alloy temperature calibration device is not easily affected by oxygen in the atmosphere, so that the alloy temperature calibration device can be used for temperature calibration and temperature measurement of various industrial furnaces under low oxygen atmosphere (including vacuum atmosphere, inert gas atmosphere, reducing atmosphere) with an oxygen partial pressure of ≤400Pa. In addition, the alloy temperature calibration device can exchange atmosphere with the external environment through a small gap between the container and the container cover to achieve pressure balance, and can control the speed at which oxygen in the atmosphere enters the interior, so as to achieve temperature calibration and temperature measurement under various pressure conditions from negative pressure to positive pressure of the low oxygen atmosphere, thereby avoiding damage to the temperature measuring device caused by changes in the pressure of the atmosphere inside the furnace, so that the temperature calibration and temperature measurement method of the present invention can be widely applied in temperature calibration and temperature measurement of industrial furnaces.

[0125] The technical solution of the present invention is further described below with reference to specific embodiments.

[0126] Example 1

[0127] This example determines the optimal rare earth addition amount by evaluating the sensitivity of cobalt-rhenium alloys with different rare earth addition amounts to oxygen in the atmosphere.

[0128] According to the method for preparing rare earth-doped cobalt-rhenium ultrahigh-temperature temperature-controlled alloys described herein, five cobalt-rhenium alloy ingots containing 0.00%, 0.10%, 0.25%, 1.00%, and 2.00% rare earth Lu by mass were prepared using a vacuum arc melting furnace. These five cobalt-rhenium alloy ingots were then individually processed and sheared into short, wire-like specimens of any dimension not exceeding 6 mm using machining equipment and shearing tools or equipment to facilitate various tests. The melting points of these five alloys were determined using the alloy melting point measurement method described herein. The specific alloy compositions and corresponding melting points are shown in Table 3.

[0129] Table 3 Melting points of prepared cobalt-rhenium temperature-calibrated alloys with different rare earth Lu contents

[0130]

[0131] Comparing the alloys in Table 3, we find that the melting point of the cobalt-rhenium alloy is virtually unaffected when Lu is added to the alloy up to 0.25%. In other words, the melting points of alloys ECR-11, ECR-12, and ECR-13 are virtually identical. Adding 1.00% Lu lowers the melting point of the Co-Re alloy by approximately 8°C. Increasing the Lu content to 2.00% significantly lowers the melting point of the cobalt-rhenium alloy by approximately 19°C (see Table 3). This alloy can still be used for temperature measurement and calibration in specific applications, such as furnaces requiring lower precision, faster heating rates, and a low oxygen atmosphere.

[0132] The sensitivity of ECR-11, ECR-12, ECR-13, ECR-14, and ECR-15 alloys to oxygen in the atmosphere was evaluated according to the "Atmosphere Sensitivity Evaluation Procedure for Temperature-Calibrated Alloys" described in the present invention. The evaluation results are shown in Table 4.

[0133] Table 4 Evaluation data on the sensitivity of prepared cobalt-rhenium alloys with different rare earth Lu contents to oxygen in the atmosphere

[0134]

[0135] Note: “ / ” in the table indicates no exact value. The more “+” in the column of sensitivity evaluation to oxygen in the atmosphere, the greater the influence of oxygen in the atmosphere.

[0136] As can be seen from Table 4, when the atmosphere sensitivity evaluation condition is set to P1633-0-40, that is, the first step holding temperature is set to 1633℃, the holding time is 40 min, the second step holding temperature is set to 1713℃, the holding time is 5 min, and the oxygen content in the atmosphere is 0 ppm (strictly speaking, the oxygen content should be extremely low), the melting points (i.e., T a(x) [PT h -ES]℃) remains almost unchanged, with a melting endothermic peak, which becomes hemispherical, and its sensitivity to atmospheric oxygen is evaluated as "+"; the melting temperature of ECR-14 alloy changes slightly, with a melting endothermic peak, which becomes spherical, but slightly sticks to the crucible, and its sensitivity to atmospheric oxygen is evaluated as "++"; the endothermic peak of ECR-15 is significantly broadened and hemispherical, and it strongly sticks to the crucible after the evaluation test. This is because there is a relatively large amount of active rare earth Lu in the ECR-15 alloy. After reacting with the zirconia crucible at high temperature, it shows strong adhesion to the crucible wall and prevents it from forming a spherical shape. Its sensitivity to atmospheric oxygen is evaluated as "++++".

[0137] When the evaluation conditions are set to P1633-20-40, that is, the oxygen content in the atmosphere is 20 ppm, the T a(x) [PT h-ES]℃ vs. T a(x) The temperature dropped by 10-12°C, and a hemispherical melting endotherm was observed. Its sensitivity to atmospheric oxygen was rated "+++." The ECR-12 alloy, with a trace amount of rare earth element Lu (0.10% by mass), exhibited similar performance to the ECR-11 alloy. This is because the ECR-12 alloy contains a low rare earth element. After the rare earth element is completely consumed by the reaction with oxygen, the excess oxygen enters the cobalt-rhenium alloy matrix lattice as free oxygen, lowering the alloy's melting point.

[0138] The ECR-13 alloy with 0.25% rare earth Lu was evaluated under the same conditions. a(x) [PT h -ES]℃ vs. T a(x) The temperature of the alloy decreased by 1.3℃ (within the tolerance of melting point), and there was a melting endothermic peak, which was spherical. The oxygen in the atmosphere did not affect its melting point and shape after melting. The sensitivity to oxygen in the atmosphere was evaluated as "+". The SEM of the entire ECR-13 alloy sample after the atmosphere sensitivity evaluation is as follows: Figure 4 As shown in the figure, it can be found that the sample has become a relatively perfect sphere, but the surface is not smooth; the surface microstructure is as follows Figure 5 As shown in the figure, it can be observed that there are many nearly spherical particles with a size of about 10 microns precipitated on the surface. The energy spectrum analysis shows that (see Figure 6 ) These particles are lutetium oxide, and generally have a higher content of Lu on the surface, indicating that during the heating process, Lu in the cobalt-rhenium matrix tends to migrate to the surface, but does not form a dense oxide shell on the surface; the smoother area is the cobalt-rhenium alloy matrix (see Figure 7 The results show that an appropriate amount of rare earth Lu can absorb oxygen entering the alloy from the ambient atmosphere, turning it into a high-melting-point, highly stable rare earth oxide precipitate (see Table 2), purifying the free oxygen in the alloy lattice and controlling the effect of atmospheric oxygen on the alloy's melting point.

[0139] Under these conditions, the ECR-14 alloy with 1.00% rare earth Lu added showed a significantly broadened endothermic peak, hemispherical, and slight crucible sticking. The sensitivity to oxygen in the atmosphere was evaluated as "+++". The ECR-15 alloy with excessive rare earth Lu (2.00% by mass) could not be judged. a(x) [PT h -ES] is mainly due to the presence of relatively more rare earth Lu in the alloy, which is more active than rhenium and cobalt. When kept at a high temperature of 1633℃ for a long time, the rare earth Lu reacts with the oxygen in the zirconia crucible and the atmosphere, and is strongly adhered to the crucible wall, preventing it from forming a spherical shape. The sensitivity to oxygen in the atmosphere is evaluated as "++++".

[0140] This shows that when 0.25% by mass of rare earth is added to the rare earth-doped cobalt-rhenium temperature-controlled alloy, its melting temperature and melting state are almost unaffected by oxygen in the atmosphere, that is, it has good gas sensitivity resistance.

[0141] Example 2

[0142] This embodiment provides a series of rare earth cobalt-rhenium doped ultra-high temperature temperature-controlled alloys with different melting points.

[0143] According to the method for preparing a rare earth-doped cobalt-rhenium ultrahigh-temperature temperature-regulating alloy described herein, a series of rare earth-doped cobalt-rhenium ultrahigh-temperature temperature-regulating alloys with different melting points were prepared by varying the cobalt content in the alloy using a vacuum arc melting furnace and shearing tools or equipment. The rare earth content was 0.25% by weight, and the added rare earth metals were Lu, La, and others.

[0144] According to the alloy melting point measurement method of the present invention, the melting points of this series of alloys were measured using a Netzsch DSC 449 F5 thermal analyzer. The specific results are shown in Table 5.

[0145] Table 5 A series of rare earth-doped cobalt-rhenium ultrahigh temperature temperature-controlled alloys with different melting points

[0146]

[0147] Example 3

[0148] The temperature calibration and temperature measurement method of the rare earth cobalt-rhenium-doped ultrahigh temperature alloy disclosed in the present invention is used to calibrate the actual temperature at the center of a SiC ceramic reaction sintering furnace.

[0149] The short filaments of alloys numbered RCR-15, RCR-16, RCR-17, RCR-18, RCR-19, and RCR-20 prepared in Example 2 were assembled into a similar alloy temperature measuring device {1633.3-1673.6}, according to the alloy temperature calibration device described in the specification. This alloy temperature calibration device {1633.3-1673.6} was placed in the center of a SiC ceramic reaction sintering furnace numbered T-11#, with ceramic compacts to be sintered placed elsewhere. Based on the requirements of the SiC ceramic sintering process, the maximum sintering temperature was set to 1630.0°C. After the sintering furnace exceeded 1450°C, the temperature control and measurement device used was a high-temperature infrared thermometer. After the furnace temperature dropped below 50°C, the SiC ceramic material and the alloy temperature calibration device were taken out together to observe the shape changes of these alloys. It was found that the shapes of RCR-15, RCR-16, RCR-17, and RCR-18 alloys changed significantly and became spherical; the shapes of RCR-19 and RCR-20 alloys did not change significantly and remained in the shape of long strips. The melting points of RCR-18 and RCR-19 alloys were 1658.8°C and 1666.4°C respectively. According to the shape changes, the highest true temperature at the center of the sintering furnace was determined to be between 1658.8-1666.4°C. The middle value was taken and it was considered that the highest true temperature at the center was T z ℃ is 1662.6±3.8℃, and T z ℃-T c ℃ = ΔT℃ is 32.6℃. When sintering the product next time, by setting the maximum sintering temperature of the T-11# furnace to 1597.4℃ in the control software, the required actual sintering temperature of 1630.0℃ can be achieved.

[0150] Example 4

[0151] The temperature calibration and temperature measurement method of the rare earth cobalt-rhenium-doped ultrahigh temperature alloy disclosed in the present invention is used to calibrate the actual temperature at the center of the Si3N4 ceramic sintering furnace.

[0152] The short filaments of alloy numbered RCR-53, RCR-54, RCR-55, RCR-56, RCR-57, and RCR-58 prepared in Example 2 were assembled into a similar alloy temperature measuring device {1837.8-1883.9}, according to the alloy temperature calibration device described in the specification. This alloy temperature calibration device {1837.8-1883.9} was placed in the center of a Si3N4 ceramic sintering furnace, with Si3N4 ceramic blanks to be sintered placed elsewhere. According to the requirements of the Si3N4 ceramic sintering process, the maximum sintering temperature was set to 1850.0°C, and the sintering atmosphere pressure was set to 6 MPa. The temperature control and temperature measuring probes of the sintering furnace were tungsten-rhenium thermocouples protected by pure tungsten sheaths. After the furnace temperature dropped below 50°C, the metal ceramic products and alloy temperature control device were taken out together to observe the shape changes of these alloys. It was found that the shapes of RCR-53 and RCR-54 alloys changed significantly and became spherical; the shapes of RCR-55, RCR-56, RCR-57, and RCR-58 alloys did not change significantly and remained in the form of short strips. The melting points of RCR-54 and RCR-55 alloys were 1847.4°C and 1856.6°C respectively. Based on the shape changes, the highest true temperature T at the center of the sintering furnace was determined. z ℃ is between 1847.4-1856.6℃. According to the temperature calibration error, it is believed that the set temperature of the sintering furnace is consistent with the actual temperature. Therefore, there is no need to perform temperature compensation calibration on the temperature of the measured temperature point.

[0153] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An application of a rare earth cobalt-rhenium alloy in the field of ultra-high temperature temperature control, characterized in that: The rare earth cobalt-rhenium alloy doped with rare earth comprises, by mass percentage, 0-99.995wt% Co, 0.005-1.5wt% RE, and the balance being Re and unavoidable impurity elements. The melting point range of the rare earth cobalt-rhenium alloy doped with rare earth is 1494-3180°C.

2. The use of the rare earth cobalt-rhenium alloy doped with claim 1 in the field of ultra-high temperature temperature control, characterized in that: RE is one of lanthanum, cerium, praseodymium, neodymium, promethium, gadolinium, terbium, dysprosium, holmium, erbium, lutetium, scandium, and yttrium, or any combination of at least two of them.

3. The use of the rare earth-doped cobalt-rhenium alloy according to any one of claims 1-2 in the field of ultra-high temperature temperature control, characterized in that: The method for preparing the rare earth-doped cobalt-rhenium alloy comprises the following steps: Step 0: Formulate an alloy formula based on the target melting point, and record the formula number as x; Step 1: According to the requirements of formula x, weigh the required mass of cobalt, rhenium and rare earth raw materials according to mass percentage; Step 2: smelting cobalt, rhenium and rare earth raw materials to alloy and homogenize the materials to obtain a rare earth-doped cobalt-rhenium alloy ingot a(x); Step 3: Processing the rare earth-doped cobalt-rhenium alloy ingot a(x), crushing it into a non-spherical shape, and preparing the rare earth-doped cobalt-rhenium alloy a(x) to be used; Step 4: Measure the melting point T of rare earth cobalt-rhenium alloy a(x) a(x) ℃; Step 5: Evaluate the sensitivity of the rare earth-doped cobalt-rhenium alloy a(x) to oxygen in the atmosphere.

4. A temperature calibration and temperature measurement method, using the rare earth cobalt-rhenium alloy doped with rare earth according to any one of claims 1-2 in the field of ultra-high temperature calibration, characterized in that: The steps include: Step 1: Estimate the ambient temperature range of the location where the temperature needs to be calibrated and measured, and determine the lower limit of the temperature range as T min ℃, the upper limit temperature is T max ℃; Step 2: According to the temperature calibration and temperature measurement accuracy requirements, select n rare earth cobalt-rhenium alloys with increasing melting points, the lowest melting point of these alloys is T a(1) ℃, the highest melting point is T a(n) ℃, T a(1) <T a(2) <T a(3) <…<T a(n-2) <T a(n-1) <T a(n) , T a(1) <T min 、T a(n) >T max ; Step 3, assembling the n rare earth cobalt-rhenium alloys with increasing melting points and a container into an alloy temperature calibration device; Step 4: Place one or more alloy temperature calibration devices described in step 3 at the location where temperature calibration or measurement is required; Step 5: Set the heating program according to the normal production process requirements, start the equipment and enter the running state. The equipment has its own temperature measurement system, and the highest temperature measured is T c ℃; Step 6: After the equipment has finished running and cooled to room temperature, take out the alloy temperature calibration device, observe the state of the alloy in the container, and determine the actual temperature T of the environment where the alloy temperature calibration device is located. z ℃, thus achieving temperature measurement; Step 7, T z -T c =ΔT, ΔT℃ is the temperature that the device needs to compensate for. The device temperature is adjusted according to ΔT, thus achieving temperature calibration.

5. The temperature calibration and measurement method according to claim 4, characterized in that: The alloy temperature calibration device in step 3 includes: N rare earth-doped cobalt-rhenium alloys with different melting points are placed in n small containers, each small container is covered with a container cover and placed in a large container, and the large container is covered with a container cover.

6. The temperature calibration and measurement method according to claim 5, characterized in that: The alloy does not wet the small container; the volume of the rare earth-doped cobalt-rhenium alloy placed in the small container is 1 / 20-1 / 2 of the volume of the small container.

7. The temperature calibration and measurement method according to claim 4, characterized in that: The temperature calibration and measurement process is carried out together with normal production. The alloy temperature calibration device is placed together with the workpiece to be processed, which does not affect normal production work and realizes in-situ temperature calibration and measurement.

8. The temperature calibration and measurement method according to claim 4, characterized in that: The actual temperature T in step 6 z ℃ is determined by: It was observed that the alloys numbered 1, 2, ..., n-3 in the alloy temperature calibration device melted into spherical shapes, while the alloys numbered n-2, n-1, and n remained unmelted and kept their original shapes. The actual temperature at the temperature calibration and measurement location is [T a(n-3) ,T a(n-2) ]℃, it is considered that T z =(T a(n-3) +T a(n-2) ) / 2.

9. The temperature calibration and measurement method according to claim 4, characterized in that: The alloy temperature calibration device can be used for temperature calibration and temperature measurement of various industrial furnaces in low oxygen atmosphere; the alloy temperature calibration device does not require vacuum or protective gas sealing and can also protect the melting point of the internal alloy from being affected by oxygen in the external environment.

10. The temperature calibration and measurement method according to claim 9, characterized in that: The alloy temperature calibration device can realize the temperature calibration and temperature measurement of industrial furnaces under various pressure conditions from negative pressure to positive pressure in the low oxygen atmosphere; the low oxygen atmosphere is an atmosphere with an oxygen partial pressure of ≤400Pa, and the low oxygen atmosphere includes a vacuum atmosphere, an inert gas atmosphere, and a reducing atmosphere.

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