A New Primary Dew-Point Generator at TUBITAK UME

An implementation of a new low-range primary humidity generator as a part of an international collaboration between TUBITAK UME and VTT MIKES was initiated as a EURAMET Project Number 1259. The dew-point generator was designed and constructed within the scope of the cooperation between TUBITAK UME and VTT MIKES in order to extend the dew-point temperature measurement capability of Humidity Laboratory of TUBITAK UME down to ??80 °C. The system was thoroughly characterized and validated at TUBITAK UME to support the evidence for dew-point temperature uncertainties. The new generator has a capability of operating in the range of ??80 °C to +10 °C, but at the moment, it was characterized down to ??60 °C. The core of the generator system is a saturator which is fully immersed in a liquid bath. Dry air is supplied to the saturator through a temperature-controlled pre-saturator. The operation of the system is based on the single-pressure generation method with a single pass, i.e., the dew-point temperature is only controlled by the saturator temperature, and the humidity-controlled air is not returned to the system after leaving of the saturator. The metrological performance of the saturator was investigated thoroughly at both National Metrology Institutes. The pre-saturator was also tested using a thermostatic bath at VTT MIKES prior to sending them to TUBITAK UME. This paper describes the principle and design of the generator in detail. The dew-point measurement system and the corresponding uncertainty analysis of the dew-point temperature scale realized with the generator in the range from ??60 °C to 10 °C is also presented.     

A Determination of the Ratio of the Zinc Freezing Point to the Tin Freezing Point by Noise Thermometry

A Johnson-noise thermometer (JNT) has been used with a quantized voltage noise source (QVNS), as a calculable reference to determine the ratio of temperatures near the Zn freezing point to those near the Sn freezing point. The temperatures are derived in a series of separate measurements comparing the synthesized noise power from the QVNS with that of Johnson noise from a known resistance. The synthesized noise power is digitally programed to match the thermal noise powers at both temperatures and provides the principle means of scaling the temperatures. This produces a relatively flat spectrum for the ratio of spectral noise densities, which is close to unity in the low-frequency limit. The data are analyzed as relative spectral ratios over the 4.8 to 450 kHz range averaged over a 3.2 kHz bandwidth. A three-parameter model is used to account for differences in time constants that are inherently temperature dependent. A drift effect of approximately −6 μK·K⁻¹ per day is observed in the results, and an empirical correction is applied to yield a relative difference in temperature ratios of −11.5 ± 43 μK·K⁻¹ with respect to the ratio of temperatures assigned on the International Temperature Scale of 1990 (ITS-90). When these noise thermometry results are combined with results from acoustic gas thermometry at temperatures near the Sn freezing point, a value of T − T ₉₀ = 7 ± 30 mK for the Zn freezing point is derived.     

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.     

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.     

Effect of Ultra-Trace Impurities on the Freezing Point of Zinc

Impurities are the most significant source of uncertainty in most metal fixed points for the realization of the International Temperature Scale of 1990 (ITS-90). The methods for the estimation of uncertainties and corrections of fixed-point temperatures attributable to the influence of chemical impurities were summarized in 2005, and the sum of individual estimates (SIE) method was recommended to be used with the known concentration and liquidus slope of each impurity. This method requires the concentrations and the liquidus slopes of all impurities. For applying the SIE method, efforts still need to be made to solve a series of problems including the unsatisfactory chemical analysis, inadequate data of the liquidus slopes, and information about the dissolution and precipitation of impurities during the filling and the operation of a fixed-point cell. In the present work at the National Institute of Metrology (NIM), great attention is paid to the effect of ultra-trace impurities on the freezing point of zinc. Five slim graphite crucibles were filled with the same batch of zinc with a nominal purity of 6 N for this research. One of them was used to investigate the concentration and distribution of the impurities in the freezing point of zinc by chemical analysis. The remaining crucibles were used to carry out the ultra-trace impurity doping experiments. The liquidus slopes of Ag–Zn, Pb–Zn, Fe–Zn, and Ni–Zn were measured. All results are reported and discussed.     

锌点炉控温装置的数字化改造

介绍了锌点炉控温设备的改造,成功研制出控温精度高、稳定性好的锌点炉自动控温装置的全过程.着重叙述了控温仪表的程序如何与相变曲线相配合、配套电路的设计以及如何与控温仪表相配合形成合适的加热电流等关键问题.     

锡固定点的凝固点与熔点研究

介绍了锡凝固点的特点,锡熔点及锡凝固点的比较,操作及使用。     

Johnson Noise Thermometry near the Zinc Freezing Point Using Resistance-Based Scaling

Johnson noise thermometry (JNT) is a primary method of measuring temperature which can be applied over wide ranges. The National Institute of Standards and Technology (NIST) is currently using JNT to determine the deviations of the International Temperature Scale of 1990 (ITS-90) from the thermodynamic temperature in the range of 505–933 K, overlapping the ranges of both acoustic gas-based and radiation-based thermometry. Advances in digital electronics have now made viable the computationally intensive and data-volume-intensive processing required for JNT using noise-voltage correlation in the frequency domain. The spectral noise power, and consequently the thermodynamic temperature T, of a high-temperature JNT probe is determined relative to a known reference spectrum using a switched-input digital noise-voltage correlator and simple resistance-scaling relationships. Comparison of the JNT results with standard platinum resistance thermometers calibrated on the ITS-90 gives the deviation of the thermodynamic temperature from the temperature on the ITS-90, T − T ₉₀. Statistical uncertainties under 50 μK·K⁻¹ are achievable in less than 1 day of integration by fitting the effects of transmission-line time constants over bandwidths of 450 kHz. The methods and results in a 3 K interval near the zinc freezing point (T _90-ZnFP ≡ 692.677 K) are described. Preliminary results show agreement between the JNT-derived temperatures and the ITS-90.     

微量杂质对锌凝固点影响的评估

介绍了当前微量杂质对固定点影响的多种评估方法,将这些方法应用到中国计量科学研究院最新研制的开口锌凝固点容器中, 并通过微量元素Sn的添加实验对这些方法给予比较与研究.     

金属杂质对锌凝固点容器融化温坪的影响

本文介绍了不同浓度杂质对锌凝固点容器融化温坪的影响,同时研究了在不同凝固速率下融化温坪的变化。研究表明,融化温坪的区别直接反映了杂质在融化过程中的分布,不同的凝固速率对锌凝固点容器融化温坪斜率影响较大。     

铝凝固点及银凝固点容器国际关键比对评述

介绍了国际计量局（BIPM）温度咨询委员会（CCT）关键比对4即铝凝固点及银凝固点容器国际比对。采用固定点容器直接比对的形式进行，共11个国家实验室参加了该项比对，介绍了比对的组织、比对过程、实验方法以及参考值的选取，同时给出了比对结果及比对等效图。     

新型锡、锌固定点炉的研制

研制了新型的三段式固定点加热炉,建立了ITS-90温标定义的锌凝固点和锡凝固点装置.采用先进的加热和控温技术及合理有效的加热器绕制方式,炉温范围从100℃到500℃,包含了ITS-90温标定义的铟固定点、锡固定点、锌固定点.在该固定点炉装置进行了锌固定点和锡固定点的温场测试,控温精度为0.1℃,垂直温场优于0.05℃,固定点装置可用于标准铂电阻温度计的检定分度使用,提供稳定的温度源.     

用锌凝固点和水沸点检定二等标准铂电阻温度计的扩展不确定度评定

按时规范,ＪＪＦ１０５９－１９９９,对二等标准铂电阻温度计在锌凝固点及水沸点检定的不确定度进行了评定,通过建立测量数学模型确定各标准各不确定度分量,并按不确定度传播公式给出固定点间各温度点的扩展不确定度及包含因子。     

新型碱性锌酸盐镀锌工艺对锌阳极板的要求

针对高分散性能的新型碱性锌酸盐镀锌工艺中形状复杂零件朝上的内腔和低电流密度区镀层严重粗糙、发黑的现象,通过分析故障现象、阳极产物属性、来源、产生机理,确定阳极上的黑色产物为Fe,源于Zn锭在普通碳钢锌锅中熔铸时因高温扩散,因此确定采用低碳痕Si型钢板制作锌锅、控制熔锌温度至450～460 ℃,用耐强碱滤布包覆阳极等方式进行电镀,从而保证了新工艺的正常运转.     

小过冷锡凝固点的研究

在对金属凝固和过冷微观机理分析的基础上,分析了影响过冷的主要因素,计算了过冷时晶核的临界尺寸。专门制作了两个具有不同过冷度的锡凝固点密封容器,着重进行了不同粘度石墨粉的添加对锡凝固点的影响实验。在对比实验实验结果的基础上,提出了“小过冷锡凝固点”概念,对国际上“锡凝固点过冷必须大于４Ｋ才能获得理想的温坪”的观点提出了不同见解,并用实验结果证明了“小过冷锡凝固定点”的可行性。     

Progress Report on the Cooperation Between NMIJ and PTB on Zinc Point Cells

The National Metrology Institute of Japan (NMIJ) and Physikalisch-Technische Bundesanstalt (PTB) have agreed to conduct a collaborative study on zinc point cells. An open-type zinc cell was prepared to act as a transfer cell in this collaboration, and cells were prepared for both institutes to perform experiments using a common cell during the collaboration. The experiments reflect concerns that both institutes have been studying independently over the past several years using an open-type cell. The concerns include the impurity effect, stability of the realized temperature, and the difference in the heat flux due to a change in the filling gas. A part of the zinc sample extracted during the fabrication of this cell was analyzed, and for the purpose of confirmation, the initial sample taken from the same lot as that used in the transfer cell was also analyzed. The stability of the transfer was evaluated from cell comparisons performed by NMIJ before and after the air transportation between PTB and NMIJ. PTB and NMIJ demonstrated an increase in temperature at the zinc point due to a change in the filling gas from argon to helium. The improvement using helium gas was found strongly to depend on the construction of the cell and the fixed-point furnace design. The analysis of the zinc sample confirmed a strong inhomogeneity of Pb and a contamination by some elements. Careful analysis for estimating the impurity effect on the temperature realized using the transfer cell was also conducted based on the latest studies to avoid an improper application of fixed-point correction.     

日本冰温技术发展史略

冰温技术在高品质保持食品的风味,鲜度,口感方面有着独特的优势.本文主要从冰温技术的起源、应用,发展等方面介绍日本冰温技术的发展状况;同时也阐述了冰温技术的基本原理,举例介绍了冰温贮藏、冰温干燥、冰温后熟、冰温浓缩、冰温冷藏链等方面的应用.     

用锑凝固点装置分度超短热电偶的研究

本文介绍了长度在44mm～109mm,直径不大于8mm的各种型号热电偶在锑凝固点(660.323℃)上的一种分度方法.     

用锑凝固点装置分度超短热电偶的研究

本文介绍了长度在44mm-109mm,直径不大于8mm的各种型号热电偶在锑凝固点（660,323℃）上的一种分度方法。