精密铂电阻温度计的校准方法

介绍了精密铂电阻温度计的特性及0~660.323℃温度范围内精密铂电阻温度计的校准方法。提出对测量上限温度高于450℃的精密铂电阻温度计可参考使用说明书要求进行上限温度退火,进行定点法校准时,可采用熔化点温坪替代凝固点温坪,对于无法进行定点法校准的精密铂电阻温度计,可采用比较法校准及采用简化公式计算各项参数的可行性,同时指出自热效应对测量的影响。     

0～29.7646℃温区定点法分度精密铂电阻温度计外推使用的探讨

精密铂电阻温度计是介于标准铂电阻温度计与工业铂电阻温度计之间的测温传感器,利用ITS-90国际温标定义的固定点分度精密铂电阻温度计可以提高测温准确性和稳定性,但经常会出现超出内插方程所规定的温度范围以致无法用定点法分度的问题.本文对精密铂电阻温度计利用水三相点及镓熔点进行分度,调研了通过0～29.7646℃温区内插方程直接外推到70℃的可行性.实验以两支精密铂电阻温度计为对象,对定点法外推结果与直接比较法进行比较,结果显示:外推结果与标准值最大差值为1.5mK,表明精密铂电阻温度计利用水三相点及镓熔点进行分度并外推至70℃在一定的测量水平要求下是可行的.     

铂电阻温度计的自热效应研究

对铂电阻温度计在冰水混合物和真空中的自热效应进行了实验研究,提出应用多电流法修正自热效应引起的测量误差.与传统的二电流法和改进的二电流法相比大大降低了自热效应修正给测量结果引入的不确定度.该研究成果对提高真空环境中温度测量的准确度具有重要意义.     

一种高精度薄膜铂电阻温度计测量迟滞性的研究

为了研究热迟滞性对工业铂电阻温度计测量不确定度的影响,选取了8支高精度铂电阻温度计进行实验。在-50～150℃内,选择3个温度区间,采用两种标准方法(IEC 60751,ASTM E644)测量水三相点(0.01℃)和所选温度范围内的中间点的迟滞性变化。实验结果表明:4支薄膜铂电阻温度计在两种标准方法测量下,随着温度区间跨度增大,热迟滞性影响增大,IEC 60751标准方法测量的热迟滞性最大值为14.2mK,ASTM E644标准方法测量的热迟滞性最大值为20.5mK;选取4支铂丝铂电阻温度计在温度范围为-50～150℃测量时,IEC 60751和ASTM E644标准方法测量的热迟滞性数据最大值分别为1.1mK和0.9mK;铂丝铂电阻温度计热迟滞性明显小于薄膜铂电阻温度计。     

试论提高工业铂电阻测量结果准确性的方法

<正>在实际测量中,工业铂电阻的测量结果容易受到各种因素的影响而产生附加误差。为避免和减小附加误差,提高工业铂电阻测量结果的准确性,现将误差的产生原因及解决方法总结如下:一、自热效应引起的误差利用铂电阻温度计测温时,必须对感温元件的电阻通入工作电流,因此会产生焦耳热,引起温度示值升高,产生测量误差。这种现象叫做自热效应。通过铂电阻的电流越大,其灵敏度和分辨力也越高,由自热效应引起的测温误差也越大。     

PPRTs偏差方程外推至-189.3442~156.5985℃温区的研究

由于ITS-90定义固定点数量少且温度间隔大,基于偏差方程的外推是解决超出温区范围的温度计标定问题的有效方法。实验对16支精密铂电阻温度计在超出温区范围标定,验证了固定点法和比较法偏差方程从窄温区范围外推至-189.3442~156.5985℃温区的可行性。实验结果表明:-38.8344~0.01℃温区新偏差方程外推至 -189.3442℃ 的平均最大差值为5.2mK;0~29.7646℃温区偏差方程外推至156.5985℃的平均最大差值为 2.0mK;基于比较法的偏差方程在-189.3442~156.5985℃温区的平均差值小于3.3mK。3种方程均提高了精密铂电阻温度计在超出温区范围的外推精度,为星载黑体辐射源的量值溯源提供了数据支撑。     

高精度复现银凝固点

建立了包括银点容器、高精度定点炉、微型机炉温群控与数据采集系统和真空充氩系统等在内的整套复现银凝固点的装置。用这套装置分度高温铂电阻温度计的复现性(标准偏差)为±1.3mK。对不同纯度的银样品的液相点温度进行了比较,纯度为99.999％的银的液相点温度比纯度为99.9999％的银低6.8mK,两个不同来源名义纯度均为99.999％的银样品的液相点温度之差小于1mK。用四支温度计考察了银凝固点的长期稳定性,年变化均不超过2.2mK。对银固、液两相平衡温度的压力系数进行了测量,结果为5.8mK/atm。大量实验数据表明,高温铂电阻温度计在银凝固点温度的稳定性很好,现有的高温铂电阻温度计就可以代替铂10％铑-铂热电偶作为实用温标630.74℃以上的内插仪器,其上限至少可达银凝固点。     

超长型玻璃液体温度计的计量方法及不确定度评定

超长型玻璃液体温度计受测量条件限制导致测量结果误差较大,需要对露出液柱部分进行修正。为保证量值传递的准确性,通过搭建包含标准铂电阻温度计、标准水银温度计和辅助温度计的测量系统,对长度为2 m、分度值为1.0、量程为0~150℃的超长型玻璃液体温度计进行测量,并对露出液柱所造成的温度误差进行了准确修正,并在此基础上,完成测量结果的不确定度分析。最后测试结果显示,系统测量的合成标准不确定度达到U=0.18℃,k=2,测量系统对超长型玻璃液体温度计的计量结果最大相对误差为0.53%,满足计量检定规程JJG 130-2011所要求的最大允许误差1.5%。     

工业铂电阻温度计校准结果的测量不确定度传播律

利用工业铂电阻温度计的内插方程和标准铂电阻温度计的参考方程推导出测量不确定度传播律方程式,给校准过程中的不确定度实时计算提供了便捷的方法,该方法对采用比较法进行温度校准的测量具有普遍的适用性。     

退火对标准铂电阻温度计性能影响的研究

退火是消除铂电阻温度计内部由于机械振动等因素带来应力的最有效手段,同时也可能改变铂电阻温度计内部铂丝的氧化状态。选用不同国家生产的4支标准铂电阻温度计,分别在600 ℃、500 ℃、450 ℃、420 ℃、350 ℃进行退火,研究铂电阻温度计退火后在室温下随时间的变化规律。结果表明,不同的退火温度对铂电阻温度计阻值产生不同影响,对应温度变化量可达1 mK,退火后在室温下0~6 h内变化显著,保持同一个热状态可有效提高铂电阻温度计的测量水平。     

基于微型镓固定点的精密铂电阻温度计原位校准的研究

基于固定点温标传递技术,设计可在镓熔点原位校准的精密铂电阻温度计,并对微型固定点相变温坪特性进行实验分析.实验结果表明:微型镓固定点温坪可持续最大时长为1.2h,温坪在20 min内稳定性优于2.8 mK,复现性优于2.3 mK;微型固定点温坪值与加热温度之间存在线性关系,并且随着加热温度的升高,固定点温坪值越高,通过...     

高精密测温电桥的标定与评估

使用RTU和RBC两种精密仪器对中国计量科学研究院中温基准实验室的F900高精密测温电桥进行了标定和评估,分析了不同工作频率、不同输出电流在长杆标准铂电阻温度计测温范围内对测量精度的影响。结果表明:电桥在不同的工作频率下精度的差异比较明显。工作频率为25 Hz时,使用RTU和RBC进行标定的最大测量偏差分别约为0.01 mK和0.06 mK;工作频率为75 Hz时,使用RTU和RBC进行标定的最大测量偏差约为0.08 mK和0.2 mK,且相比出厂时有了较大的漂移。电桥在不同的输出电流下精度的差异非常小,在15 μK以内。采用RTU及RBC对F900测温电桥评价的结果之间相互印证,该结果对中温固定点基准复现过程的不确定度评定提供了数据支撑。     

Effect of Impurities on the Freezing Point of Zinc

The knowledge of the liquidus slope of impurities in fixed-point metal defined by the International Temperature Scale of 1990 is important for the estimation of uncertainties and correction of fixed point with the sum of individual estimates method. Great attentions are paid to the effect of ultra-trace impurities on the freezing point of zinc in the National Institute of Metrology. In the present work, the liquidus slopes of Ga–Zn, Ge–Zn were measured with the slim fixed-point cell developed through the doping experiments, and the temperature characteristics of the phase diagram of Fe–Zn were furthermore investigated. A quasi-adiabatic Zn fixed-point cell was developed with the thermometer well surrounded by the crucible with the pure metal, and the temperature uniformity of less than 20 mK in the region where the metal is located was obtained. The previous doping experiment of Pb–Zn with slim fixed-point cell was checked with quasi-adiabatic Zn fixed-point cell, and the result supports the previous liquidus slope measured with the traditional fixed-point realization.     

Quasi-Adiabatic Investigations of Lead in Indium

The use of melting or freezing temperatures of high-purity substances as thermometric fixed points requires a knowledge of the binary phase diagrams of these substances and remaining impurities at very small impurity concentrations. In this paper, a calorimetric apparatus for the measurement of the change in liquidus temperature of fixed-point metals due to dissolved impurities at quasi-adiabatic conditions is presented. This approach combines advantages of the fixed-point method and adiabatic calorimetry. It is more efficient for the screening of a range of impurity concentrations than a fixed-point cell, requires less constructional and experimental expenditure compared with an adiabatic calorimeter, but provides similar small uncertainties on the millikelvin level. Measurements were carried out to determine the influence of lead on the melting temperature of indium at mass fractions up to 6.93 %. The results are in very good agreement with previous measurements by means of slim fixed-point cells in the Physikalisch-Technische Bundesanstalt and confirm a minimum of the freezing point of \(-\) 178 mK at a mass fraction of about 3.7 %. It was demonstrated that this setup allows the investigation of binary phase diagrams with uncertainties less than 8 mK.     

A New Method for the Quantification and Correction of Thermal Effects on the Realization of Fixed Points

The temperature and flatness (shape) of a fixed-point plateau depend on both the amount and nature of specific impurities and on thermal effects that are influenced by the fixed-point cell design and furnace properties. A better understanding and experimental proof of the influence of specific impurities on fixed-point realizations require the separation of impurity influences from thermal effects. In this paper the influence of heat exchange between the thermometer and furnace is quantified via a method based on changing the furnace temperature during the fixed-point measurement. It will be shown that the corresponding correction of this thermal effect has a dominant influence on the plateau shape compared to the influence of impurities. This leads to an explanation for why the maximum of an induced freeze is the most reproducible temperature. A secondary outcome is an explanation of why natural freezes have less flat plateaux compared to induced freezes, resulting in fixed-point temperatures that are too low. Furthermore, the suggested procedure is the basis of the direct and quantitative comparison of fixed-point cells and the detection of weak points within a specific design. It allows optimization of fixed-point cells and furnaces, and helps to deepen the common understanding of the phase transition in fixed-point cells.     

Study on the Impurity Effect in the Realization of Silver Fixed Point

The application of a thermal analysis model to estimate the temperature depression from the ideal fixed-point temperature is important, especially when the chemical analysis of the sample in a cell is insufficient or the cell might have been contaminated during fabrication. This study extends previous work, on thermal analysis with the tin point, to an investigation of the impurity dependence of the silver-point temperature. Close agreement was found between the temperature depression (\(-0.36\) mK) inferred from the thermal analysis of the measured fixed-point plateau and the temperature depression (\(-0.32\) mK) inferred using the sum of individual estimates (SIE) method with an impurity analysis based on glow discharge mass spectrometry. Additionally, the results of the thermal analysis manifest no significant dependence on the rate of solidification, and the scatter of observed gradients was within 0.36 mK among five plateaux with different temperature settings of the furnace. Although the results support the application of both the SIE method and thermal analysis for the silver point, further experiments with cell-to-cell comparisons linked to thermal analysis, a study of the thermometer-furnace systematic effects, the oxygen effect, and the locus of the freezing plateau should be investigated to reach a firm conclusion.     

硅基微腔光子学测温技术研究进展

硅基微腔光子学测温包括基于热折变效应的协议温度测量以及基于光机谐振原理的热力学温度测量,国际温度咨询委员会（CCT）在2018-2027战略规划中,将硅基微腔光子学测温确定为接触测温新兴技术的主要发展方向。本文简要介绍上述两种测温理论机理,综述近年来美国国家标准与技术研究院（NIST）、欧洲计量合作组织（EURAMET）等发达国家计量院与计量组织在上述领域的研究进展,以及来自于学术界的探索性研究内容;最后介绍中国计量科学研究院在毫开尔文（mK）级微腔光子温度计制备与测试、基于法诺共振的亚mK级分辨力提升方法、基于氮化硅微腔的亚mK级自热温升抑制等研究进展。     

Bi-In-Sn合金熔化温坪优化方法探索

为了提高红外遥感高精度测量水平,研发适用于红外遥感测温范围的次级固定点已成为提高在轨温度标定精度的重要手段.针对红外遥感领域涉及的温度范围(190～350 K),研制了Bi-In-Sn三元合金固定点.为提高三元合金温坪复现水平,采用预熔方法对三元合金固定点进行预处理,分析不同热工况对三元合金温坪的影响,获得适用于该三元...     

Ga-In共晶固定点复现及赋值研究

次级固定点进一步分度温度计应用于温度校准已成为减小温度量值传递不确定度的重要方法.围绕Ga-In二元合金,以高复现水平为目标,详细介绍了大尺寸固定点容器研制、固定点灌注过程,开展了固定点复现性、亚配比剩余镓温坪验证实验研究;采用了切线交点法、均值法、三次多项式拟合法3种相变温度取值方法对Ga-In固定点进行了评价和分析...     

Bilateral Comparison of Aluminum Fixed-Point Cells Using Standard Platinum Resistance Thermometer

The objective of Project EURAMET 1114 (Bilateral comparison of a freezing point of aluminum) in the field of thermometry is to compare realization of a freezing point of aluminum (660.323???C) between the Dutch national laboratory VSL and the Slovenian national laboratory MIRS/UL-FE/LMK using a long-stem 25 ?? standard platinum resistance thermometer (SPRT). Both laboratories had participated in a number of inter-comparisons on the level of EURAMET and also on BIPM CCT level (VSL). MIRS/UL-FE/LMK laboratory recently acquired a new fixed-point cell which had to be validated in the process of intercomparison. A quartz-sheathed SPRT was selected and calibrated at MIRS/UL-FE/LMK at the aluminum freezing point and at the water triple point. A second set of measurements was made on the same SPRT and at the same fixed points at VSL (NL). After its return, the SPRT was again recalibrated at MIRS/UL-FE/LMK. In the comparison the W value of the SPRT was used. The results of the internal and external intercomparisons confirmed that the new aluminum cell of the MIRS/UL/FE-LMK realizes a temperature that agrees with the VSL aluminum fixed point within the uncertainty limits of both laboratories. Furthermore, the results of this bilateral-comparison were compared with results that both laboratories achieved in the EURAMET K4 (Project 820) and were found to be in agreement.