水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。     

镓三相点的复现

本文介绍了镓三相点的复现方法,并对镓三相点值进行测量,其温度值为29.7666℃.     

镓三相点的复现

本文介绍了镓三相点的复现方法,并对镓三相点值进行测量,其温度值为29．7666℃。     

快速复现水三相点温度的一种方法

本文介绍了复现水三相点温度的方法.     

汞三相点的复现

利用自制的超高纯汞三相点容器,复现了1990年国际温标(ITS-90)中新设定的汞三相点。结果表明其融化范围和凝固范围均在0.1mK以内,复现性优于0.1mK,两者的符合程度也在0.1mK之内,分别用纯度为99.99999％的超高纯商品汞和实验室清洗的汞经高真空蒸馏制备的两个密封容器,测定结果在实验误差内一致,差异不大于0.1mK。文中介绍了三相点容器的制备工艺要点。     

一种快速冻制水三相点瓶的方法

水的三相点是热力学温度的唯一基准点,也是1990年国际温标(ITS-90)定义的最基本的、及其重要的固定点.水三相点的复现是通过水三相点瓶的冻制和保存来实现的,本文介绍了一种快速且实用的水三相点瓶冻制方法,并阐述了此种方法的优点.     

用密封式三相点容器复现氖三相点

介绍了用密封式三相点容器在低温恒温器中复现氖三相点的方法和结果.在研究中采用了多容器结构,它包含有平衡氢、氖、氧和氩密封三相点容器各一个,可在同一个恒温器中依次进行复现.对应这种多容器结构,中国计量科学研究院设计和建立了新的高精度的低温恒温器.对氖三相点测量结果的复现性为0.1 mK,扩展不确定度为0.14 mK.     

Realization of the Gallium Triple Point at NMIJ/AIST

The triple point of gallium has been realized by a calorimetric method using capsule-type standard platinum resistance thermometers (CSPRTs) and a small glass cell containing about 97 mmol (6.8 g) of gallium with a nominal purity of 99.99999%. The melting curve shows a very flat and relatively linear dependence on 1/F in the region from 1/F = 1 to 1/F = 20 with a narrow width of the melting curve within 0.1 mK. Also, a large gallium triple-point cell was fabricated for the calibration of client-owned CSPRTs. The gallium triple-point cell consists of a PTFE crucible and a PTFE cap with a re-entrant well and a small vent. The PTFE cell contains 780 g of gallium from the same source as used for the small glass cell. The PTFE cell is completely covered by a stainless-steel jacket with a valve to enable evacuation of the cell. The melting curve of the large cell shows a flat plateau that remains within 0.03 mK over 10 days and that is reproducible within 0.05 mK over 8 months. The calibrated value of a CSPRT obtained using the large cell agrees with that obtained using the small glass cell within the uncertainties of the calibrations.     

高准确度水三相点容器

水三相点的高精度复现及准确测量是保证国际温标ITS-90实施的关键。水三相点容器内高纯水的同位素组成会影响复现的水三相点温度值。为了提高水三相点复现水平,减小氢氧同位素的影响,研制了带有氢氧同位素分析的石英及硼硅玻璃高准确度水三相点容器。为了评价容器的性能,开展了硼硅玻璃和石英水三相点容器的比对。实验结果表明:同位素修正前,石英玻璃和硼硅玻璃水三相点容器复现的水三相点在0.058mK范围内一致;同位素修正之后,容器之间的差异在0.017mK范围内一致。采用高准确度水三相点容器复现水三相点的扩展不确定度为0.066mK(k=2)。     

论一种恢复水三相点容器性能的方法

本文介绍了在研究水三相点容器长期可靠性能的实验中，国外所采用的一种恢复水三相点容器性能的方法。我们利用此方法制作两组容器，通过对照实验研究此方法对水三相点温度的影响。实验结果表明：由于此方法不能最大程度除去溶解在容器水中、吸附在容器内壁面的气体，导致所复现的水三相点温度偏低约0．13mK。     

金属外壳水三相点容器

水三相点是ITS-90国际温标中最重要的定义固定点,其复现不确定度是传递到整个温标的.目前,通常采用不同的冻制方法在硼硅玻璃或石英水三相点容器内冻制均匀的冰套来复现水三相点.冻制过程中,由于在水三相点容器内生成冰桥,会造成容器的破裂.为了解决此难题,研制了金属外壳水三相点容器,利用高纯水自发相变原理,在液体槽内自动冻制...     

Vapor Pressure of Water at Its Triple Point

The vapor pressure of water at its triple point was measured with exceptionally high accuracy by realizing it with a special apparatus and measuring the pressure with the NBS precision mercury manometer. The vapor pressure apparatus had a system for circulating the liquid water. Actual triple point conditions were established with a thin sheet of freshly distilled liquid flowing down over an exposed mantle of ice frozen on a vertical well. This technique reduced non-volatile contaminants and the vapor was repeatedly pumped to remove accumulated volatile contaminants. A diaphragm pressure transducer was used to separate the water vapor from the helium used to transmit the pressure to the manometer. The value found for the vapor pressure of water at its triple point was 611.657 Pa with an uncertainty of ± 0.010 Pa from random errors, computed at 99 percent confidence limits. The systematic errors are estimated to be insignificant relative to the random errors.     

Isotopic Effects on the Temperature of the Triple Point of Water

An investigation into the effects of isotopic composition on the triple point temperature of water has been carried out at the National Institute of Metrology (NIM), China, since redefinition of the kelvin with respect to Vienna Standard Mean Ocean Water (V-SMOW) was officially proposed by the Consultative Committee for Thermometry (CCT) in 2005. In this paper, a comparison of four cells with isotopic analyses and relevant results corrected for isotopic composition, employing the isotope correction algorithm recommended by the CCT, is described. The results indicate that, after application of the corrections, the maximum temperature difference between the cells drops from 0.10 mK to 0.02 mK and that these cells are in good agreement within 0.02 mK. Also, temperature deviations arising from isotopic variations fall in the range from −55.9 μK to + 40.7 μK. We consider that the distillation temperature and degassing time of the production procedure lead to isotopic variations.     

Realization of the Triple Point of Water in Metallic Sealed Cells at the LNE-INM/CNAM: A Progress Report

A miniature metallic cell for the water triple point (TPW, temperature 273.16 K) was developed for capsule-type thermometer calibrations for realizations with adiabatic calorimetry techniques. The LNE-INM/Cnam previously developed a copper cell for the water triple point and the techniques for cleaning, filling, and sealing. On the basis of previous work, a new copper cell prototype for the TPW was developed and filled at the LNE-INM/Cnam. Measurements were performed using an appropriate calorimeter and a comparison block containing several thermometers. Preliminary results show a scatter of the temperatures measured at the phase transition of the order of 0.2 mK when measurements are repeated over a short-term period (1 month). A positive drift in the phase transition temperature of about 30μK·month⁻¹ was observed over several months. Studies are in progress to improve the cell, to reduce the reproducibility uncertainty to less than 0.1 mK and to have a phase transition with better temporal stability.     

CCT-K7水三相点容器国际关键比对

在国际互认框架内,国家计量标准的国际等效性是通过国际计量委员会（CIPM）的咨询委员会组织的一系列国际关键比对来确定的。温度咨询委员会（CCT）委托国际计量局（BIPM）作为主导实验室组织了由20个国家实验室参加的CCT-K7水三相点容器国际关键比对。比对结果表明：这些国家基准水三相点值在0．171mK范围内一致。此外,为了减小国家实验室复现水三相点的系统差,需要进一步研究同位素组成对水三相点温度的影响以及同位素修正。     

Evaluation of a Portable Apparatus for the Realization of the Triple Point of Argon

In this paper, the evaluation of the performance of a portable triple-point-of-argon apparatus, via the analysis of the calibration history of selected working (fused silica) standard platinum resistance thermometers (SPRTs), is presented. These have an extensive calibration history, both internally (using different apparatus) and externally at two National Measurement Institutes. A special procedure had to be developed, for the calibration of metal-sheathed SPRTs, in order to ensure adequate thermal contact between the SPRT and the well and to minimize the influence of stem conduction, inherent in the compact design of the maintenance system. The results show good agreement between the measurements performed with this system and those with the previously used apparatus, to a level of uncertainty consistent with the INTA calibration and measurement capability (CMC) of 3.0 mK (k = 2). This CMC is given by the Spanish accreditation body (ENAC), under accreditation No. 16/10.007, for the routine calibration of SPRTs at the triple point of argon. It is concluded that the portable apparatus is suitable for use as a transfer standard for the comparison of local realizations of the triple point of argon. This avoids the need to shipping fragile SPRTs, with a valuable long calibration history, and eliminates the contributions due the long-term stability of the thermometers subjected to transportation. The long-term stability of the portable apparatus reported in this work has only been determined in laboratory conditions.     

4种不同水源的水三相点容器的比对

为了研究水源对水三相点温度的影响,采用4种不同的水源并按照相同的制作工艺研制高质量的水三相点容器.同时,将这些容器进行了比对实验.比对结果表明:这些不同水源的水三相点容器复现的水三相点值在±0.02 mK范围内一致.故推断出水源对水三相点温度的影响很小.     

SF6及CO2三相点替代Hg三相点内插方法可行性探究

在不改变90国际温标内插方程形式的基础上,针对83.8058 K到273.16 K温区,分析了六氟化硫(SF6)和二氧化碳(CO2)三相点替代汞(Hg)三相点后,导致的内插方程变化带来的温度偏差以及传播不确定度变化规律.研究结果表明:SF6和CO2三相点替代Hg三相点后,该方程在该温区仍具有适用性;在复现不确定度相同的...     

套管对水三相点的影响研究

为了研究套管对水三相点的影响,研制了计阱内径分别为16 mm和18 mm的水三相点容器以及直径为15.5 mm的套管。通过在计阱内加套管和不加套管,并利用准确度为0.02×10^-6的交流比较仪电桥测量标准铂电阻温度计在计阱内的电阻值,比较不同直径水三相点容器内套管对水三相点的影响。实验结果表明:实验中套管对水三相点值的影响小于30 μK,且在相同的测量条件下,套管的直径与水三相点容器温度计阱的内径越接近,套管对水三相点值的影响越小。