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。     

-80～300℃铂电阻温度计在0℃的热迟滞性研究

针对两种不同类型的工业铂电阻温度计(IPRTs),使其在-80℃和300℃下恒温一定时间后再测量其0℃下的电阻偏移,由此来确定其在该温度下的热迟滞性。试验结果表明:薄膜型铂电阻温度计在0℃的热迟滞性远大于铂丝型铂电阻温度计,并且随着测量次数的增多,热迟滞性会逐渐减小。     

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.     

铂丝位错特性对标准铂电阻温度计稳定性影响的研究

铂丝的位错是影响标准铂电阻温度计性能稳定性的重要因素之一。从微观角度出发,借助X射线衍射(XRD)分析方法,开展了退火时间对铂丝位错密度影响的研究,并利用标准铂电阻温度计退火实验数据进行了验证。结果表明:实际用于标准铂电阻温度计直径为0.07mm的新制铂丝(纯度99.999%)平均位错密度随着退火时间呈指数减小,经过100h退火后位错密度从1012cm^-2下降到1011cm^-2,300h后其位错密度基本保持稳定;新制标准铂电阻温度计在退火前300h其水三相点电阻值明显减小,退火300h后水三相点值变化量小于3mK并趋于平稳,此结果从热处理时间上与铂丝位错实验结果基本吻合。研究结果为标准铂电阻温度计制作工艺的提升及计量检定规程的修订提供技术支撑     

在0～660.323℃温区标准铂电阻温度计的两个二次偏差函数

给出了在0～660．323℃温区标准铂电阻温度计(SPRT)的两个二次偏差函数：一个是由水三相点、锡凝固点和铝凝固点的检定值来确定;另一个由水三相点、锌凝固点和铝凝固点来确定。这两个二次偏差函数是ITS-90温标在0～660．323℃温区标准铂电阻温度计偏差函数的一个很好的近似。使用70支标准铂电阻温度计检验了这两个偏差函数,其误差一般不超过2．4mK,最大不超过4．7mK。     

工业铂电阻温度计使用ITS-90温标分度方法可行性分析

国内外大多数工业铂电阻的标准(包括IEC 60751标准)均采用Callendar-Van Dusen (CVD)方程的方法来分度工业铂电阻温度计.而现行国际温标ITS-1990采用不同温区的内插公式来分度铂电阻温度计,研究表明,在CVD方程和ITS-90温标的内插公式之间存在系统差异,采用ITS-90国际温标的方法用于工业铂电阻温度计理论上是可行,但需要进一步的数据支持和实验验证,而如何有效的使用则需要更广泛和深入的研究探讨.     

空气环境下PtO2分解实验的研究

标准铂电阻温度计的感温元件高纯铂丝的氧化是影响其测温性能的重要因素之一。利用差示量热扫描仪(DSC)和X射线光电子能谱技术(XPS),研究铂丝氧化的主要产物PtO2在不同温度下的生成产物,以及不同产物的生成和分解温度。结果表明:当温度在550～820 ℃范围内时,随着温度的升高,PtO2会逐渐分解生成PtO和Pt,且温度越高生成的Pt含量越多;当温度高于820 ℃时,PtO2会快速分解为Pt和O2。该研究结果对标准铂电阻温度计的制作技术和使用提供了理论支撑。     

标准铂电阻温度计测量结果不确定度评定

本文以最常用的温度段（0-429．527）℃,以一等标准铂电阻温度计检定二等标准铂电阻温度计为例来分析标准铂电阻温度计的测量结果不确定度。     

标准铂电阻温度计自热效应对测量结果的影响

为了研究自热效应对标准铂电阻温度计测量结果的影响,分别从定点法和比较法两方面开展研究.针对定点法,统计中国计量科学研究院近3年检定的标准铂电阻温度计数据,计算不同温区的铂电阻温度计自热效应修正前后的测量结果并进行对比,结果表明,在溯源标准铂电阻温度计时自热效应修正与否对测量结果的影响达到了1.5 mK以上,最大达到了6...     

419.527～961.78℃范围新的国家温度基准

挑选三支高温铂电阻温度计组成基准温度计组。研制了铝凝固点和银凝固点密封容器及整套定点装置。采用“诱导低速率”凝固技术,实现了这两个固定点,复现性分别为0.6mK和1.0mK,年稳定性分别为1.3mK和4mK,不同容器间的差别分别为0.3mK和1.1mK。与德国PTB进行了比对,这两个固定点的一致性都在1mK以内。在419.527～961.78℃范围内,置信概率为0.99的总不确定度为2.5～6mK。     

Thermal Hysteresis in Thin-Film Platinum Resistance Thermometers

Thin-film platinum resistance thermometers (PRTs) are generally manufactured using the deposition of a thin platinum film on an alumina substrate and a laser-trimming method. Because of the strong adhesion between the platinum thin film and the alumina substrate, the PRTs inevitably have strain over the operating temperature range. This causes anomalies and instabilities in the resistance versus temperature characteristics (R?CT). The most prominent and observable effect of thermally induced strain is the thermal hysteresis in the R?CT characteristics. Thermal hysteresis is one of the main uncertainty factors in the calibration of industrial platinum resistance thermometers in laboratories. The thermal hysteresis for 30 thin-film PRTs was measured in the range of 0 °C to 500 °C in 100 °C steps. The thermal hysteresis was measured repeatedly using the same process, and the hysteresis decreased drastically with the repeated measurements. The thermal hysteresis was distributed from 16 mK to 156 mK for all sensors, and the lowest hysteresis was 1 mK to 11 mK in the test temperature range.     

Determination of PRT Hysteresis in the Temperature Range from −50 °C to 300 °C

This paper discusses the contribution of hysteresis to the measurement uncertainty of industrial platinum resistance thermometers (IPRTs). Hysteresis is one of the sources of uncertainty that has so far not been sufficiently researched and documented. The term hysteresis applies to any system that is path dependent; the output depends on the history of the input. In our case, thermal hysteresis results in different resistance values at the same temperature point, depending on whether the temperature was increasing or decreasing. The reason for such behavior is related to the construction of the thermometer (strain due to thermal expansion and contraction) and also to possible moisture inside the encapsulation. In the process of evaluation of the calibration and measurement capabilities (CMCs) of IPRTs within Working Group 8, the Consultative Committee for Thermometry (CCT WG8) concluded that the uncertainty due to hysteresis is not uniformly defined and not always added to the total uncertainty of the resistance thermometer under calibration. In order to estimate the uncertainty contribution due to the hysteresis and compare different procedures, resistance measurements were carried out on a number of IPRTs of different qualities and tolerance classes. The temperature span was between ?50 °C and 300 °C, which is the most frequent temperature range in the practical use of IPRTs. The hysteresis was then determined in different ways (change of resistance at the ice point and at the midpoint temperature according to the ASTM International Standard E644 and according to the new version of IEC Standard 60751), and a comparison of results was made.     

Evaluation of Small-Sized Platinum Resistance Thermometers with ITS-90 Characteristics

Many platinum resistance thermometers (PRTs) are applied for high precision temperature measurements in industry. Most of the applications use PRTs that follow the industrial standard of PRTs, IEC 60751. However, recently, some applications, such as measurements of the temperature distribution within equipments, require a more precise temperature scale at the 0.01 °C level. In this article the evaluation of remarkably small-sized PRTs that have temperature?Cresistance characteristics very close to that of standard PRTs of the International Temperature Scale of 1990 (ITS-90) is reported. Two types of the sensing element were tested, one is 1.2 mm in diameter and 10 mm long, the other is 0.8 mm and 8 mm. The resistance of the sensor is 100 ?? at the triple-point-of-water temperature. The resistance ratio at the Ga melting-point temperature of the sensing elements exceeds 1.11807. To verify the closeness of the temperature?Cresistance characteristics, comparison measurements up to 157 °C were employed. A pressure-controlled water heat-pipe furnace was used for the comparison measurement. Characteristics of 19 thermometers with these small-sized sensing elements were evaluated. The deviation from the temperature measured using a standard PRT used as a reference thermometer in the comparison was remarkably small, when we apply the same interpolating function for the ITS-90 sub-range to these small thermometers. Results including the stability of the PRTs and the uncertainty evaluation of the comparison measurements, and the comparison results showing the small deviation from the ITS-90 temperature?Cresistance characteristics are reported. The development of such a PRT might be a good solution for applications such as temperature measurements of small objects or temperature distribution measurements that need the ITS-90 temperature scale.     

Typical R(T 90) Characteristics of Platinum Thin-Film Resistance Thermometers in the Temperature Range from ?50?��C to +660?��C

Today most of the available platinum thin-film (TF) resistance thermometers tend to exceed the IEC 60751 Class A tolerances for temperatures above about 400 °C and below about ?50 °C. The main reason for this behavior is their specific R(T ₉₀) characteristic which systematically and reproducibly differs from the standard characteristic to IEC 60751. This could be proven in the context of an extensive comparison test. However, just recently the first types of a new generation of Pt TF sensors that no longer show this typical characteristic deviation but which adhere to the tolerance class A according to the IEC 60751 standard in the temperature range of ???50 °C to 660 °C have become available.     

-38.8344~156.5985℃温区温标偏差方程外推和内插研究

根据90国际温标定义,对0~29.7646℃和-38.8344~29.7646℃两个子温区偏差方程使用范围的外推进行研究,给出了-38.8344~156.5985℃温区的新偏差方程,采用15支和23支标准铂电阻温度计的标定数据对偏差方程的外推和新方程进行验证。结果表明:在0~29.7646℃与-38.8344~29.7646℃温区内的偏差方程分别外推到100℃与-80℃时,外推结果与温标偏差方程计算结果的最大差值为1.1 mK与2.6 mK,新的偏差方程在1.5 mK内与温标定义偏差方程等效,两个子温区偏差方程使用范围外推及新偏差方程在一定程度具备可行性。     

Calibration of Industrial Platinum Resistance Thermometers up to 700\,^{\circ }\mathrm{C}

Industrial grade platinum resistance thermometers were calibrated in the temperature range from \(200\,^{\circ }\mathrm{C}\) to \(700\,^{\circ }\mathrm{C}\) . Both wire-wound and thin-film sensor-based thermometers were investigated. The purpose of the study was to investigate thermometers which could be used in future coal power plants. The calibrations were performed in a vertical cesium heat-pipe furnace and in a horizontal and vertical sodium heat-pipe furnace. The reference thermometer was a standard platinum resistance thermometer calibrated at fixed points up to the aluminum point. In addition to calibration, various thermal tests including immersion measurements and thermal-cycling tests were performed. The stability of the sensors was determined by monitoring the ice-point resistance. Possible contamination of the sensors was determined by measuring the resistance ratio \(R(30\,^{\circ }\mathrm{C})/R(10\,^{\circ }\mathrm{C})\) several times during the measurement period. The calibration curves were compared with the ICE 60751 standard and International Temperature Scale 1990 (ITS-90) reference functions. Considerable changes were found in all tested thermometers. The wire-wound sensors were more stable than the thin-film sensors.     

A Sub-millikelvin Calibration Facility in the Range 0 $$^{\circ }$$C to 30 $$^{\circ }$$C

A new sub-millikelvin calibration facility for the range 0 \(^{\circ }\)C to 30 \(^{\circ }\)C is described, that allows calibration of customer thermometers, other than standard platinum resistance thermometers, with an uncertainty lower than 1 millikelvin. The improvements with respect to the traditional calibration facility are reported with particular emphasis on the temperature control (better than 0.2 mK), resistance measurement and calibration procedure. The new facility was validated by using 6 standard platinum resistance thermometers and the calibration uncertainty in the range from 0 \(^{\circ }\)C to 30 \(^{\circ }\)C amounted to 0.31 mK–0.35 mK. To demonstrate the potentiality of this facility, two oceanographic thermometers, Sea-Bird Electronics SBE 3 and SBE 35, were calibrated with an expanded uncertainty of 0.8 mK (\(k=2\)).     

一种超长杆铂电阻温度计校准装置

核电站所用的铂电阻温度计总长度超过3m,温度计的感温元件长度接近3m,常规的校准系统不能用于此类超长杆温度计的性能评估。介绍了一种用于核电站的超长杆铂电阻温度计的校准实验装置,通过实验验证,该系统的温度稳定性优于±0.015℃,水平和垂直温度均匀性分别优于0.05℃和0.02℃,标准不确定度和扩展不确定度分别为0.016℃和0.032℃,该实验系统可有效地评估长杆铂电阻温度计的性能。     

The Hysteresis Characteristics of Some Industrial PRTs

Hysteresis in industrial platinum resistance thermometers (IPRT) is caused by tension and compression induced in the wire due to differential thermal expansion of the platinum wire and the substrate. This article reports the measurement of hysteresis in a wide range of IPRTs including thin-film, glass-encapsulated, ceramic-encapsulated, and low-hysteresis partially-supported sensors, over the temperature range from ?20 °C to 180 °C. The study confirms previous findings that the amount of hysteresis is very dependent on the design of the sensing element and the temperature range. In addition, some sensors exhibit a large change in resistance on first use, whereas others showed a slow increase in resistance with use. The observed hysteresis ranged between 0.2 % of the temperature range for one glass-encapsulated sensor and 0.002 % for the best of the partially-supported ceramic sensors.     

微型双温度固定点容器研制

基准固定点传递技术应用于现场温度校准已成为提高工业温度测量水平的一种重要途径。采用多孔石墨坩埚半包围结构,内部对称填充了高纯铟(In)和锡(Sn)2种金属,研制了一种应用于现场校准的微型双温度固定点容器。实验结果表明,In点熔化温坪持续时间约为2 h,Sn点熔化温坪持续时间约为3 h,In和Sn的温坪复现的扩展不确定度分别为4.0 mK 和4.4 mK(k=2),可满足工业现场对精密铂电阻温度计的校准需求。