Au fixed point development at NRC

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1007/s10765-017-2186-x
AuthorSearch for: 1; Search for: 1; Search for: 1
Name affiliation
  1. National Research Council of Canada. Measurement Science and Standards
FormatText, Article
Journal titleInternational Journal of Thermophysics
ISSN0195-928X
1572-9567
Volume38
Issue4
SubjectGold; Metal fixed point; Pt/Pd thermocouple
Abstract
Two Au fixed points filled using metal of different nominal purities in carbon crucibles have been developed at the National Research Council Canada (NRC). The primary motivation behind this project was to provide the means for direct thermocouple calibrations at the Au freezing point (1064.18∘C). Using a Au fixed point filled with the metal of maximum available purity [99.9997 % pure according to glow discharge mass spectroscopy (GDMS)], multiple freezing plateaus were measured in a commercial high-temperature furnace. Four Pt/Pd thermocouples constructed and calibrated in-house were used to measure the freezing plateaus. From the calibration at Sn, Zn, Al and Ag fixed points, the linear deviation function from the NIST-IMGC reference function (IEC 62460:2008 Standard) was determined and extrapolated to the freezing temperature of Au. For all the Pt/Pd thermocouples used in this study, the measured EMF values agree with the extrapolated values within expanded uncertainty, thus substantiating the use of 99.9997 % pure Au fixed point cell for thermocouple calibrations at NRC. Using the Au fixed point filled with metal of lower purity (99.99 % pure according to GDMS), the effect of impurities on the Au freezing temperature measured with Pt/Pd thermocouple was further investigated.
Publication date
PublisherSpringer
LanguageEnglish
Peer reviewedYes
NPARC number23002612
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Record created2017-12-06
Record modified2020-03-16
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