A method for reproducing a peritectic point at high temperature

Abstract

The application discloses a high-temperature eutectic point reproduction method and belongs to the technical field of temperature standards.The application realizes the method by dividing the reproduction process into six stages, i.e., a heating section 1, a heating section 2, a correction section, a reproduction melting section, a reproduction solidification section and a cooling section.The starting and ending temperatures and the heating / cooling rates of each stage are different, the reliability of the reproduction test is improved by adjusting the parameters, high-quality reproduction results are obtained, and the risk of crucible rupture is reduced, and the high-temperature eutectic point reproduction parameter adjustment method comprises parameter range adjustment, parameter correction model construction and quantitative control and the like.If a single test needs to be performed for multiple times, the operation of the reproduction melting section is repeated after the reproduction solidification section according to the test requirements until the required number of reproduction times is completed.The application can realize the high-temperature eutectic point reproduction and is used for performing reproduction tests on various high-temperature eutectic points.The application has the advantages of good reproduction quality and high crucible safety.

Description

Technical Field

[0001] This invention relates to a method for reproducing high-temperature eutectic points, used to conduct reproduction tests on various high-temperature eutectic points, and belongs to the field of temperature standard technology. Background Technology

[0002] High-temperature eutectic points, a key technology for the next generation of temperature scales, will add several high-temperature reference temperature points to the existing ITS-90 temperature scale. This will change the calibration of standard radiation thermometers from extrapolation to linear interpolation, significantly reducing the uncertainty in high-temperature measurement. High-temperature eutectic point technology includes pouring and reproduction techniques. The former mainly involves the fabrication of high-temperature eutectic points by rationally designing the crucible structure and pouring method to create crucibles that meet reproduction requirements. Reproduction techniques primarily aim to accurately realize the nominal temperature of the eutectic point for the calibration and adjustment of standard radiation thermometers.

[0003] Currently, the CCT-WG5 (International Committee on Temperature Advisory Working Group on Radiation Thermometry) has set specific requirements for the main structure and key dimensions of the crucible, as well as the characteristics of the filling material, to ensure that the high-temperature eutectic points produced by various countries are capable of international comparison. Regarding reproduction techniques, it only specifies requirements for some special temperature points, such as the lower plateau temperature point and the upper plateau temperature point, but does not provide specific requirements for the entire reproduction process. The main reason for this is that the reproduction devices used by different metrology institutions have varying performance, control methods, and reproduction parameter settings, leading to significant variations in reproduction methods. A good reproduction method is crucial for the quality of eutectic point temperature reproduction, overcoming inherent defects in reproduction devices, and reducing the risk of crucible breakage. Summary of the Invention

[0004] The main objective of this invention is to provide a method for reproducing high-temperature eutectic points, addressing the commonly used graphite heating-radiation thermometer temperature control type reproduction device. This method enables the reproduction of high-temperature eutectic points and is suitable for conducting reproduction experiments on various high-temperature eutectic points used in radiation thermometry. This invention offers advantages such as high reproduction quality and high crucible safety.

[0005] The objective of this invention is achieved through the following technical solution.

[0006] This invention discloses a high-temperature eutectic point reproduction method, which divides the reproduction process into six stages: heating stage 1, heating stage 2, correction stage, reproduction melting stage, reproduction solidification stage, and cooling stage. The starting and ending temperatures and heating / cooling rates of each stage are different. By adjusting the above parameters, the reliability of the reproduction test can be improved, high-quality reproduction results can be obtained, and the risk of crucible breakage can be reduced.

[0007] The high-temperature eutectic point reproduction method disclosed in this invention is as follows:

[0008] Before the experiment begins, the high-temperature eutectic point crucible is placed in the center of the furnace tube of the reproduction device. Before heating, the high-temperature eutectic point crucible is aimed for the first time using a standard photoelectric pyrometer, focusing the aiming position of the photoelectric pyrometer on the blackbody cavity opening of the crucible.

[0009] Turn on the reproduction device and raise the temperature by adjusting the parameters of the temperature control instrument. The starting temperature of the first heating stage is room temperature, and the ending temperature is 750℃ (the value displayed by the temperature control radiation thermometer). The heating rate is ≤15℃ / min. After reaching the ending temperature, use a standard photoelectric pyrometer to aim the high-temperature eutectic point crucible a second time to reduce the aiming deviation caused by thermal expansion and contraction.

[0010] After aiming is complete, continue heating to enter heating stage 2, with an initial temperature of 750℃. The termination temperature is 100℃ below the nominal phase transition temperature of the eutectic point (the value displayed by the temperature-controlled radiation thermometer), which is the initial correction temperature, and the heating rate is ≤25℃ / min.

[0011] After reaching the initial correction temperature, the correction phase begins. It is necessary to read the standard photoelectric pyrometer reading T. 光电 and temperature-controlled radiation thermometer reading T 控温 The two will show a large difference, and by repeatedly and slightly increasing the target temperature of the temperature control device, T 光电 The temperature is continuously approaching the lower plateau temperature (20°C below the nominal eutectic point phase transition temperature) T. 下平台 And ultimately led T 光电 =T 下平台 At this time, the temperature-controlled radiation thermometer reads as T. 下平台控温 .

[0012] When the standard photoelectric pyrometer reading reaches T 下平台 It stabilizes until it enters the re-melting stage, with the termination temperature being the upper plateau temperature T. 上平台 (Generally, this is 20°C above the nominal phase transition temperature of the eutectic point, but can be adjusted according to experimental needs). Adjust the temperature controller of the reproduction device to T. 上平台控温 T 上平台控温 =T 下平台控温 +(T 上平台 -T 下平台 The heating rate is set to the equipment's maximum rate, meaning the heating rate limitation is lifted, allowing the reproduction device to reach its fastest heating capacity. The standard photoelectric pyrometer reading reaches T... 上平台 Then, adjust the temperature controller of the reproduction device to T. 下平台控温 Entering the reproduction solidification stage, the cooling rate is at the equipment's maximum rate, meaning the cooling rate limitation is lifted, allowing the reproduction device to utilize its fastest cooling capacity. This continues until the standard photoelectric pyrometer reading reaches T... 下平台 After that, a reproduction test is completed.

[0013] When the standard photoelectric pyrometer reading reaches T 下平台 And stabilize until entering the reproducible melting stage, preferably, the stabilization time range is 10 min to 15 min.

[0014] If a single test needs to be reproduced multiple times, repeat the operation of reproducing the solidification section and then the melting section according to the test requirements, until the required number of reproductions is completed.

[0015] After completing the reproduction test, adjust the temperature controller of the reproduction device to room temperature and enter the cooling stage, with a cooling rate ≤15℃ / min. Once the furnace temperature reaches room temperature, turn off the power to end the high-temperature eutectic point reproduction test.

[0016] Beneficial effects:

[0017] This invention discloses a method for reproducing high-temperature eutectic points. By analyzing the characteristics of high-temperature eutectic point crucibles and high-temperature eutectic point reproduction methods, the reproduction process is divided into six stages: heating stage 1, heating stage 2, correction stage, reproduction melting stage, reproduction solidification stage, and cooling stage. By adjusting parameters such as the start and end temperatures and heating / cooling rates of each stage, combined with timing control, the reliability of the reproduction test can be improved, high-quality reproduction results can be obtained, and the risk of crucible breakage can be reduced. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the stage division of a high-temperature eutectic point reproduction method disclosed in this invention.

[0019] Figure 2 Schematic diagram of the high-temperature eutectic point reproduction system. Detailed Implementation

[0020] To facilitate understanding of the present invention, embodiments of the present invention will be described below. Those skilled in the art should understand that the following description is only for the purpose of explaining the invention and is not intended to limit its scope.

[0021] Taking the reproduction of the Co-C high-temperature eutectic point as an example (nominal phase transition temperature is 1324℃).

[0022] like Figure 1 As shown in the figure, the implementation method of the high-temperature eutectic point reproduction method disclosed in this embodiment is as follows:

[0023] Before the experiment began, the high-temperature eutectic point crucible was placed at the center of the furnace tube of the reproduction device. Before heating, a standard photoelectric pyrometer was used to aim the crucible for the first time, focusing the aiming position of the pyrometer at the blackbody cavity opening of the crucible. The reproduction device was turned on, and the temperature was increased by adjusting the parameters of the temperature control instrument. The starting temperature of heating section 1 was room temperature, and the ending temperature was 750℃ (the value displayed by the temperature control radiation thermometer), with a heating rate ≤15℃ / min. After reaching the ending temperature, the high-temperature eutectic point crucible was aimed a second time using the standard photoelectric pyrometer. After completion, the temperature control instrument of the reproduction device was set to 1224℃, and heating section 2 began with a heating rate ≤25℃ / min. After reaching the set temperature, the correction section began.

[0024] At this time, the standard photoelectric pyrometer measured 1268℃. The temperature controller of the reproduction device was set to 1246℃, and the temperature was increased at a rate of ≤25℃ / min.

[0025] After stabilization, the standard photoelectric pyrometer reading was 1286℃. The temperature controller of the reproduction device was set to 1262℃, and the temperature was increased at a rate of ≤25℃ / min.

[0026] After stabilization, the standard photoelectric pyrometer reading was 1301℃. The temperature of the reproduction device was set to 1265℃, and the temperature was increased at a rate of ≤25℃ / min.

[0027] After stabilization, the standard photoelectric pyrometer reading was 1303℃. The temperature of the reproduction device was set to 1266℃, and the temperature was increased at a rate of ≤25℃ / min.

[0028] After stabilization, the standard photoelectric pyrometer reading is 1304℃, which is the lower plateau temperature (20℃ below the nominal phase transition temperature of the Co-C eutectic point). Therefore, T... 下平台控温 The temperature is 1266℃. Assuming that the required plateau temperature for this experiment is 20℃ higher than the nominal phase transition temperature of the Co-C eutectic point, then T 上平台控温 It is 1306℃.

[0029] After stabilizing for 10 minutes, the heating rate limit of the reproduction device was removed, and the thermometer was set to 1306℃ to enter the melting stage of the reproduction device. Measurement data was continuously recorded using a standard photoelectric pyrometer. When the photoelectric pyrometer reading reached 1344℃, the thermometer was set to 1266℃ to enter the solidification stage of the reproduction device. Measurement data was continuously recorded using a standard photoelectric pyrometer. One reproduction test was completed when the photoelectric pyrometer reading reached 1304℃.

[0030] This experiment requires four consecutive repetitions, so the above operation is repeated three more times to obtain four sets of repetition curves. This can achieve high-quality repetition results while reducing the risk of crucible breakage.

[0031] After completing the test, set the temperature gauge of the reproduction device to 25℃ (room temperature), with a cooling rate ≤15℃ / min. After the furnace temperature drops to room temperature, turn off the power and other auxiliary equipment to complete the test.

[0032] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for reproducing high-temperature eutectic points, characterized in that: The reproduction process is divided into six stages: heating stage 1, heating stage 2, correction stage, reproduction melting stage, reproduction solidification stage, and cooling stage. Before the experiment begins, the high-temperature eutectic point crucible is placed in the center of the furnace tube of the reproduction device. Before heating, the high-temperature eutectic point crucible is aimed for the first time using a standard photoelectric pyrometer, and the aiming position of the photoelectric pyrometer is focused on the position of the crucible blackbody cavity opening. Turn on the reproduction device and raise the temperature by adjusting the temperature control instrument parameters. The starting temperature of the first heating stage is room temperature, and the ending temperature is 750℃. The heating rate is ≤15℃ / min. After reaching the ending temperature, use a standard photoelectric pyrometer to aim the high-temperature eutectic point crucible a second time to reduce the aiming deviation caused by thermal expansion and contraction. After aiming is completed, continue heating to enter heating section 2, with an initial temperature of 750℃; the termination temperature is 100℃ below the nominal phase transition temperature of the eutectic point, i.e., the initial correction temperature, and the heating rate is ≤25℃ / min. After reaching the initial correction temperature, the correction phase begins; it is necessary to read the standard photoelectric pyrometer reading T. 光电 and temperature-controlled radiation thermometer reading T 控温 The two will show a large difference, and by repeatedly and slightly increasing the target temperature of the temperature control device, T 光电 The temperature of the lower plateau is constantly approaching T. 下平台 And ultimately led T 光电 =T 下平台 At this time, the temperature-controlled radiation thermometer reads as T. 下平台控温 ; When the standard photoelectric pyrometer reading reaches T 下平台 It stabilizes until it enters the re-melting stage, with the termination temperature being the upper plateau temperature T. 上平台 Adjust the temperature of the reproduction device's temperature controller to T. 上平台控温 T 上平台控温 =T 下平台控温 +(T 上平台 -T 下平台 The heating rate is the equipment's maximum rate, meaning the heating rate limitation is lifted, allowing the reproduction device to reach its fastest heating capacity; the standard photoelectric pyrometer reading reaches T... 上平台 Then, adjust the temperature controller of the reproduction device to T. 下平台控温 Entering the reproduction solidification stage, the cooling rate is at the equipment's maximum rate, meaning the cooling rate limitation is lifted, allowing the reproduction device to utilize its fastest cooling capacity; this continues until the standard photoelectric pyrometer reading reaches T... 下平台 After that, a reproduction test is completed; If the experiment requires multiple consecutive reproductions, repeat the above operation after completing one reproduction, re-enter the reproduction melting stage, and start the next reproduction. After completing the reproduction test, adjust the temperature controller of the reproduction device to room temperature and enter the cooling stage. The cooling rate is ≤15℃ / min. After the temperature inside the furnace reaches room temperature, turn off the power and end the high-temperature eutectic point reproduction test.

2. The method for reproducing high-temperature eutectic points as described in claim 1, characterized in that: When the standard photoelectric pyrometer reading reaches T 下平台 It is then stabilized until it enters the reproducible melting stage, with the stabilization time ranging from 10 to 15 minutes.

Images