Small Multiple Fixed-Point Cell as Calibration Reference for a Dry Block Calibrator

A small multiple fixed-point cell (SMFPC) was designed to be used as in situ calibration reference of the internal temperature sensor of a dry block calibrator, which would allow its traceable calibration to the International Temperature Scale of 1990 (ITS-90) in the operating range of the block calibrator from \(70\,^{\circ }\hbox {C}\) to \(430\,^{\circ }\hbox {C}\). The ITS-90 knows in this temperature range, three fixed-point materials (FPM) indium, tin and zinc, with their respective fixed-point temperatures (\(\vartheta _\mathrm {FP}\)), In (\(\vartheta _\mathrm {FP}\,{=}\,156.5985\,^{\circ }\hbox {C}\)), Sn (\(\vartheta _\mathrm {FP}\,{=}\,231.928\,^{\circ }\hbox {C}\)) and Zn (\(\vartheta _\mathrm {FP}\,{=}\,419.527\,^{\circ }\hbox {C}\)). All of these FPM are contained in the SMFPC in a separate chamber, respectively. This paper shows the result of temperature measurements carried out in the cell within a period of 16 months. The test setup used here has thermal properties similar to the dry block calibrator. The aim was to verify the metrological properties and functionality of the SMFPC for the proposed application.     

便携温度校验仪的评价及应用

介绍了评价便携温度校验仪性能的方法,并且提出了其使用时应该注意的问题.在100℃测试点,试验表明,如果不注意热传导的影响,其可能带来4.36℃的误差.     

Experimental and Numerical Investigation of the Temperature Field of a Fixed-Point Cavity

The temperature field non-uniformity of a blackbody cavity is one of the components of uncertainty of fixed-point realization. Here a study of the design and opportunities of the temperature furnace used in VNIIM is described. The dependence of the uniformity of a temperature field on various factors is shown by results of numerical calculations of a temperature field of VNIIM??s copper and gold fixed-point cells, realized with the software packages Elcut 5.3 and Ansys 11.0. A thermophysical model of the phase transition considered as steady state with convection and radiation heat exchange to an environment is applied. The basic focus is made on calculation of the radiation heat exchange between crucible elements and the environment and a furnace cavity, as a dominating component of the heat transfer. Results using analytically and numerically calculated angular factors of radiation of heat exchange are discussed. The data obtained in measurements of a temperature field of a cavity fixed point during phase transitions of copper and gold by a spectrocomparator with high sensitivity, are also shown here. Both theoretical calculation and experiment were realized at various distributions of temperature along an external surface of a crucible. Good agreement of results between steady-state calculation of a temperature field and the measured data with the best entry conditions is observed. The average value of non-uniformity of a temperature field along a cavity for points of phase transition of copper and gold for an 88?mm long graphite crucible with a 54?mm deep, 8?mm diameter cavity was 40?mK, and the temperature drop across the graphite wall was 20 mK. In this paper the reasons for occurrence of large gradients inside a fixed-point cavity during the phase transition, received during some experimental research, are also discussed.     

Long-Term Monitoring of Thermocouple Stability with Miniature Fixed-Point Cells

In the framework of the European Metrology Research Programme ENG08 “MetroFission” project, two National Measurement Institutes, LNE-Cnam (France) and NPL (UK), have cooperatively developed methods of in situ validation of thermocouple output for application in next-generation nuclear fission power plants. Miniature fixed-point cells for use at three temperatures were constructed in the first step of this project: at the freezing point of silver ( \(961.78\,^{\circ }\mathrm{C}\) ), the freezing point of copper ( \(1084.62\,^{\circ }\mathrm{C}\) ), and the melting point of the iron–carbon eutectic ( \(1154\,^{\circ }\mathrm{C}\) ). This paper reports the results of a second step in the study, where the robustness of the self-validation method has been investigated. Typical industrial Type N thermocouples have been employed with each of the miniature fixed-point devices installed, and repeatedly thermally cycled through the melting and freezing transitions of the fixed-point ingots. The devices have been exposed to a total of up to 90 h in the molten state. Furthermore, the LNE-Cnam devices were also subjected to fast cool-down rates, on five occasions, where the rate is estimated to have been between \(150\,^{\circ }\mathrm{C}\,{\cdot }\min ^{-1}\) and \(200\,^{\circ }\mathrm{C}\,{\cdot } \min ^{-1}\) . The devices are shown to be repeatable, reliable, and robust over the course of these tests. The drift of the Type N thermocouple has been identified separately to the behavior of the device. A reliable method for improving thermocouple performance and process control is therefore demonstrated. Requirements for implementation and the advantages of each approach for monitoring and correcting thermocouple drift are discussed, and an uncertainty budget for self-validation is presented.     

高速干切削温度场的测量及仿真研究

分析了切削热的产生、热的传导以及切削温度的测量方法.对目前切削温度实验测量技术及数值模拟仿真技术的优缺点进行了比较.采用平面应变热力耦合切削模型,重点研究在高速干切削过程中,工件已加工表面的温度变化过程.根据试验测定工件材料的力学性能以及刀具-工件之间的摩擦特性,建立材料在切削变形过程中热产生以及热传导模型,并采用点跟踪的方法获取工件材料上任意位置点温度的变化过程.并将模拟计算得到的切削温度与实验测量结果进行了比较,两者具有较好的一致性.     

温度校准仪及其输出参数的校准方法

对温度校准仪输出参数的校准提出一种有效的方法.仪器在模拟热电偶输出时通常均具有参考端温度自动补偿,由于参考端温度的变化且不易测量给校准带来困难.本方法利用热电偶的测量原理将仪器的输出端引至冰点,可以得到稳定的输出值.至于热电偶对分度表的偏差,则可以通过校准得出在常温下的修正值,以此对测量结果进行修正.通过不确定度评定得出,在具有高精度数字电压表的前提下,补偿导线的制作和使用占有较大的不确定度分量,应予重视.     

Correlation Between Immersion Profile and Measured Value of Fixed-Point Temperature

Assessment of thermal immersion effects in the melting and freezing points defined by the International Temperature Scale of 1990 is one of the vital issues of modern thermometry. In documents of the Consultative Committee for Thermometry, the deviation of the experimental immersion profile from the theoretical value of the hydrostatic effect at a height of about 3 cm to 5 cm from the thermometer well bottom is used for the estimation of the uncertainty due to unwanted thermal effects. This estimation assumes the occurrence of solely the hydrostatic effect all along the height of the well inner wall. Real distortions of the temperature gradient at the bottom and at the top part of the well caused by the change of heat-exchange conditions are not taken into account. To define more precisely the temperature gradient along the height of the well, a miniature PRT with a 30 mm sensitive element and a sheath length and diameter of about 60 mm and 6 mm, respectively, were used. Also, the measurements of fixed-points temperature at noticeably different slopes of immersion profiles due to variations of the thermometer heat exchange and phase transition realization conditions were produced by means of a standard platinum resistance thermometer (SPRT). The measurements were carried out at the tin and zinc freezing points. The immersion curves measured with a miniature thermometer demonstrated an increase of the temperature during its lifting in the first 1 cm to 3 cm above the bottom of the well. The measurement results at the zinc freezing point by means of the SPRT have not confirmed the correlation between the immersion curves, the received value of the Zn freezing temperature, and the estimation of its uncertainty.     

不同测温标准器及填充介质对消解实验仪温度测量影响的探讨

使用不同测温标准器及填充介质进行水解实验仪的温度实验,探讨不同条件下对温度测量结果的影响。经实验验证,推荐使用热电偶测温标准器进行温度测量,同时可使用填充介质作为导热辅助,以减少非紧密接触产生的误差。     

干法刻蚀制作场发射阴极阵列

利用离子束刻蚀(IBE)和反应离子刻蚀(RIE)等干法刻蚀方法来制造带栅极的场发射阴极阵列。本文描述了其制作的流程工艺,并对制作中的一些关键问题和技术进行了讨论。采用SF6作为反应气体的RIE用来制作硅尖,而用CF4 H2为反应气体的RIE用来清除SiO2,离子束刻蚀用来形成栅极。采用干法刻蚀,可以制造出栅极开口小的场发射阴极阵列。     

Bilateral Comparison of Mercury and Gallium Fixed-Point Cells Using Standard Platinum Resistance Thermometer

The objective of project EURAMET 1127 (Bilateral comparison of triple point of mercury and melting point of gallium) in the field of thermometry is to compare realization of a triple point of mercury (?38.8344 °C) and melting point of gallium (29.7646 °C) between the Slovenian national laboratory MIRS/UL-FE/LMK and the Croatian national laboratory HMI/FSB-LPM using a long-stem 25 ?? standard platinum resistance thermometer (SPRT). MIRS/UL/FE-LMK participated in a number of intercomparisons on the level of EURAMET. On the other hand, the HMI/LPM-FSB laboratory recently acquired new fixed-point cells which had to be evaluated in the process of intercomparisons. A quartz-sheathed SPRT has been selected and calibrated at HMI/LPM-FSB at the triple point of mercury, the melting point of gallium, and the water triple point. A second set of measurements was made at MIRS/UL/FE-LMK. After its return, the SPRT was again recalibrated at HMI/LPM-FSB. In the comparison, the W value of the SPRT has been used. Results of the bilateral intercomparison confirmed that the new gallium cell of the HMI/LPM-FSB has a value that is within uncertainty limits of both laboratories that participated in the exercise, while the mercury cell experienced problems. After further research, a small leakage in the mercury fixed-point cell has been found.     

热电偶温度校准器计量性能的校准及不确定度评定

介绍了一种热电偶温度校准器的基本结构、工作原理以及其计量性能的校准方法和校准结果测量不确定度的评定。利用高精度数字电压表和标准温度计,采用补偿导线法对校准器计量性能进行校准,经对其测量不确定度的分析与计算,得到测量不确定度的值未超过校准器输出值允差的1／3,证实了校准方法是合理、可靠的。     

Influence of Temperature and High Electric Field on Power Consumption by Piezoelectric Actuated Integrated Structure

The influence of electric field and temperature on power consumption of piezoelectric actuated integrated structure is studied by using a single degree of freedom mass-spring-damper system model coupled with a piezoactuator. The material lead zirconate titanate, is considered as it is capable of producing relatively high strains (e.g., 3000με). Actuators are often subject to high electric fields to increase the induced strain produced, resulting in field dependant piezoelectric coefficient d₃₁, dielectric coefficient ε₃₃ and dissipation factor δ. Piezostructures are also likely to be used across a wide range of temperatures in aerospace and undersea operations. Again, the piezoelectric properties can vary with temperature. Recent experimental studies by physics researchers have looked at the effect of high electric field and temperature on piezoelectric properties. These properties are used together with an impedance based power consumption model. Results show that including the nonlinear variation of dielectric permittivity and dissipation factor with electric field is important. Temperature dependence of the dielectric constant also should be considered.     

温度与量块长度光波干涉测量的相关性

温度从测量标准和被测对象两个方面作用于量块长度光波干涉测量.以测量不确定度为线索,在理论计算与实验结果的基础上,就影响量块长度测量的各温度影响源及其相互关系,以及相应的具体控制方法及边界进行了讨论.     

Large- and Small-Aperture Fixed-Point Cells of Cu,Pt–C,and Re–C

Extending the application of metal (carbide)–carbon eutectic fixed-point cells to radiometry, e.g., for measurements in irradiance mode, requires fixed-point cells with large apertures. In order to make large-aperture cells more readily usable in furnace systems with smaller furnace tubes commonly used for small-aperture fixed-point cells, a novel cell design was developed. For each of Cu, Pt–C, and Re–C fixed points, two types of fixed-point cells were manufactured, the small- and large-aperture cell. For Pt–C and Re–C, the large-aperture cells were filled with a hyper-eutectic metal–carbon mixture; for the small cells, a hypo-eutectic mixture was used for filling. For each material, the small and large cells were compared with respect to radiometric differences. Whereas plateau shape and melting temperature are in good agreement for the small- and large-aperture Cu cells, a larger difference was observed between small- and large-aperture cells of Pt–C and Re–C, respectively. The origin of these observations, attributed to the temperature distribution inside the furnace, ingot contamination during manufacture, and non-uniform ingot formation for the larger cells, is discussed. The comparison of measurements by a radiation thermometer and filter radiometer of the Re–C and Pt–C large-aperture cells showed large differences that could be explained only by a strong radiance distribution across the cavity bottom. Further investigations are envisaged to clarify the cause.     

Comparison of Re�CC Fixed-Point Cells and Their T90 Temperatures Between NMIJ and VNIIOFI

The comparison of Re?CC fixed-point cells built at NMIJ and VNIIOFI was carried out. Both cells were built using 5N purity rhenium of the same supplier, and the crucibles had similar dimensions. The cells were heated in the same furnace and measured on consecutive days using a radiation thermometer. To eliminate the effect of possible instability of the thermometer, a third Re?CC cell was used as a reference: it was placed in another furnace and was measured each day just after the cell to be compared. The melting-temperature difference of the NMIJ cell to the VNIIOFI cell was 0.045 °C with a standard uncertainty of 0.033 °C. In the course of this comparison, a comparison of the temperature scales between the NMIJ and the VNIIOFI at the Re?CC point (2475 °C) was performed using the NMIJ Re?CC cells as transfer standards. The difference between the NMIJ and the VNIIOFI scales was found to be ?0.8 °C, which was within the combined uncertainty of 1.4 °C (k = 2).     

Simultaneous Contact and Non-contact Measurements of the Melting Temperature of a Ni–C Fixed-Point Cell

A novel fixed-point cell design that allows simultaneous measurements using contact and non-contact thermometers was developed and investigated at PTB to realize the nickel-carbon (Ni–C) fixed-point. The melting temperature indicated by the LP3 radiation thermometer amounted to (1328.86 ± 0.52)°C (k = 2). The melting temperature of the Ni–C fixed-point cell was also calculated by extrapolating the emf-temperature characteristics of two Pt/Pd thermocouples based on their calibrations at conventional fixed points of the ITS-90. The melting temperature of the Ni–C eutectic amounts to (1328.44 ± 0.45)°C using thermocouple Pt/Pd 01/04, and to (1328.53 ± 0.46)°C using thermocouple Pt/Pd 01/05, with uncertainties for k = 2. The contact and non-contact thermometers agree well within the combined uncertainties.