Details

Autor(en) / Beteiligte

• Pearce, Jonathan V.

Titel

Optimising Platinum-Rhodium Thermocouple Wire Composition to Minimise Composition Change Due to Evaporation of Oxides

Ist Teil von

• Johnson Matthey Technology Review, 2016-10, Vol.60 (4), p.238-242

Ort / Verlag

Johnson Matthey

Erscheinungsjahr

2016

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Barring the presence of significant amounts of impurities, an important cause of thermoelectric inhomogeneity and therefore calibration drift of platinum-rhodium thermocouples at high temperatures is the vaporisation and transport of the oxides of Pt and Rh, which causes local changes in wire composition. By examining the vapour pressures of Pt and Rh oxides and their temperature dependence, it is shown that at a given temperature there is an optimal wire composition at which evaporation of the oxides has no effect on the wire composition, provided the vapour does not leave the vicinity of the wire. This may also have applications for Pt-Rh heater elements.