镉凝固点

本文介绍的镉凝固点定点装置具有结构简单，操作方便，复现控温程序可一次到位的特点．其中密封容器性能很好，经凝熔温差法检验，证明封装后的镉样品仍然保持着很高的纯度．用三支工作基准级铂电阻温度计复现镉凝固点的实测结果为：（１）短期复现性为０．５ｍＫ；（２）总不确定度为１．４ｍＫ；（３）同级温度计的非一致性值为０．９ｍＫ．研制的镉凝固点定点装置可作为一个高稳定度固定点装置使用．     

中法银凝固点温度的比对

本文介绍了中国（ＮＩＭ）与法国（ＩＮＭ）在银凝固点温度处的比对过程及结果。两国比对结果在１ｍＫ内相一致。     

锌凝固点的比较

哈特公司为建立锌的凝固点专门设计了一种密封容器，这种客器有诸多优点，例如使用方便，寿命较长等。纯度为９９．９９９９％的锌样品放入石墨坩锅后被封入一个充满纯氩气的熔融石英容器中，经测定，其复现性为０．２４ｍＫ。本文概述了实现固定点的方法，并将测试结果与经ＮＩＳＴ标定过的标准铂电阻温度计的结果进行了比较，二者之间数据之差小于０．３ｍＫ．凝固点附近的扩展不确定度（包含系数ｋ＝２）为１．０ｍＫ，满足ＮＩＳＴ最高准确度的要求．     

高温凝固点的国际比对

从1990年起全世界要统一采用新的国际温标(ITS-90)。本文介绍了为做好准备工作,中国计量科学研究院和联邦德国技术物理研究院所进行的银凝固点容器和铝凝固点容器直接比对的情况。所用银样品和铝样品的名义纯度均为99.9999％(按重量)。结果表明,所有参加比对的银凝固点和铝凝固点分别在1mk范围内相一致。     

用黑体辐射法复现铝凝固点

本文叙述用精密直流光电温度计昨现纯金属铝凝固点的实验装置和实验方法，复现铝凝固点的总不确定度小于50mK，置信度为99%。实验中对3个铝点黑体石墨坩埚容器的凝固温度进行了多次测量，3个容器的铝凝固点温度之差不大于10mK。在8个月的时间内，对同一铝点坩埚容器的铝凝固点温度进行了11次测量，其标准偏差为15mK，长期重复性也很好。     

银、铝、锌和锡凝固点的高精度复现

我们成功复现了90国家温标定义的固定点：银、铝、锌和锡凝固点。本文介绍了这些凝固点的是现方法和实验结果，表明能满足建立0－961．78范围内90国际温标的高精度复现系统的要求。     

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。     

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。     

便携式锡凝固点装置的研制

研制了小尺寸金属壳锡凝固点容器,配合干体炉使用,温度计插入深度为250 mm,锡凝固点复现性为0.22mK,与参考容器的差值小于0.2mK,温坪持续时间16h,复现方法简单,便于携带,满足了短杆铂电阻温度计高精度校准的需求。     

铟凝固点复现装置

铟凝固点是９０年国际温标新增加的定义点之一，凝固点温度为１５６．５９８５℃，可代替水沸点，在我们建立的装置上，实现了铟凝固点温度的复现，复现性为０．１４ｍＫ，总不确定度为０．８ｍＫ，优于课题计划１．５ｍＫ的技术指标，圆满地完成了任务。可作为温度副基准的保存和用于量传。     

Intercomparison of the Realization of the ITS-90 at the Freezing Points of Al and Ag among European NMIs

The EUROMET.T-K4 comparison is the regional extension of CCT-K4, an intercomparison of the realizations of the freezing points of Al (660.323°C) and Ag (961.78°C). The intercomparison was organized in four loops. Long-stem standard platinum resistance thermometers (SPRTs) were used as traveling standards: 25 Ω thermometers to be used only at the Al freezing point and two high-temperature standard platinum resistance thermometers (HTSPRTs) to be used only at the Ag freezing point in each loop. Parallel to the measurements with thermometers, the pilots and sub-pilots organized an internal intercomparison using an Ag fixed-point cell. Most HTSPRTs showed a strong drift which is mainly due to mechanical stress and poisoning of the sensor by impurities. This drift can be partially compensated by a correction based on Matthiessen’s rule. An evaluation of the data taking into account both HTSPRTs in each loop, the linkage of the sub-pilots by measurements at the Ag freezing point, and a possible compensation according to Matthiessens’s rule, allows calculation of the results of the participants’ measurements at the Ag freezing point. The results of the participating laboratories are summarized, and proposals for key comparison reference values and linking of the results to CCT-K3 and CCT-K4 are presented.     

An analysis of the conditions for the formation of an internal interface and their effect on the freezing point of zinc

The effect of the conditions for the formation of an internal interface on the freezing point of zinc of 99.9999% purity for different intensities of the removal of heat from the zinc in the thermometer channel is investigated. Comparative measurements without the formation of an internal interface were carried out. The difference between the maximum values of the measured temperatures reached approximately 1 mK. The reasons for these differences are considered.Translated from Izmeritelnaya Tekhnika, No. 11, pp. 43–45, November, 2004.     

A method for calculating the freezing point of dairy products

Using the method of Leighton, an approximate method of predicting the freezing point of milk products, including ice cream, is developed. It takes account only of the concentrations of sugar and serum. Predictions are tested against a range of experimental measurements and the error is found to be generally less than 0.05°C.     

The Influence of Antimony on the Tin Point

In 2005, an agreement was reached on how to estimate uncertainties and how to correct fixed-point temperatures for the influence of chemical impurities. Although the general procedure is now specified, some problems remain. The slope of the liquidus line at very low-impurity concentrations must be extracted either from binary-phase diagrams or from doping experiments. Apart from this, there is little experimental evidence to prove that the models used to characterize the freezing and the melting plateaux are adequate, especially for impurities that increase the fixed-point temperature. Therefore, a series of measurements were carried out using a tin fixed-point cell doped with antimony. By varying the freezing and the melting conditions, some useful experimental data were collected.     

手持式冰点测定仪(折射率法)校准方法

简述了目前手持式折射率法冰点测定仪的用途,国内外防冻液标准现状。现有计量技术规范无法满足手持式折射率法冰点测定仪的计量校准需求,且国内暂无专门针对手持式冷却液冰点测定仪(折射率法)的计量技术规范、标准溶液的配制参考方法。介绍了手持式折射率法冰点测定仪的原理和结构,探讨了此类仪器的校准方法,讨论了主要的校准项目,同时还介绍了校准用溶液的配制方法和校准时的注意事项。     

三段控温固定点炉复现铝凝固点研究

固定点炉垂直温场均匀性是影响ITS-90国际温标固定点温坪质量的重要因素.为了提高铝凝固温坪的复现水平,设计了三段控温固定点炉,利用金属外壳铝固定点容器,研究了垂直温场均匀性及其影响因素;在此基础上,采用连续热流密度法高精度复现了铝凝固点.实验结果表明:通过调整上部、中部、下部炉温的设置,可改善固定点炉温场均匀性,铝凝...     

Intercomparison of Copper Fixed-Point Cells by Using Pt/Pd Thermocouples

The objective of the EUROMET Project No. 844 in the field of thermometry was the intercomparison of the freezing temperatures of the copper fixed-point cells (t ₉₀ = 1084.62°C) of the participating laboratories by using Pt/Pd thermocouples. For most of the 13 participating laboratories, agreement of the freezing temperatures of the different copper fixed points within ±0.06 K was found. Furthermore, the results of the intercomparison show that Pt/Pd thermocouples are suitable for use as transfer standards for the dissemination of temperatures and to approximate the ITS-90, at least up to the freezing point of copper.     

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。