Variations in the Thermoelectric Behavior of Palladium Following Heat Treatment

Published

June 1, 2001

Author(s)

Dean C. Ripple, G W. Burns

Abstract

In order to identify limitations on the use of Pt/Pd thermocouples as high-accuracy thermometers, we have studied the change in thermocouple emf at the Al and Ag freezing points following a series of heat treatments at various temperatures for several lots of Pd wire. Reversible changes in the thermocouple emf at the Ag point (962 C) occur after heat treatments in the approximate temperature range 550 C to 1000 C, and slower, irreversible changes in emf occur after exposure to higher temperatures. Surprisingly, the sign of the reversible change was different for thermocouples fabricated from two lots of Pd of different purity. The magnitude of the changes in emf can be as high as the equivalent of 0.7 K per 200 h of heat treatment for the irreversible changes and 0.07 K per 200 h for the reversible changes. The consequences of these effects for metrology applications of Pt/Pd thermocouples are discussed.

Proceedings Title

International Symposium on Temperature and Thermal Measurements in Industry and Science | 8th ||VDE

Conference Dates

June 1, 2001

Conference Location

Berlin, GE

Conference Title

TEMPMEKO

Pub Type

Conferences

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Keywords

anneal, drift, palladium, thermocouple, thermoelectric

Citation

Ripple, D. and Burns, G. (2001), Variations in the Thermoelectric Behavior of Palladium Following Heat Treatment, International Symposium on Temperature and Thermal Measurements in Industry and Science | 8th ||VDE, Berlin, GE, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=830733 (Accessed April 25, 2024)