A calculation of E.M.F. Drift from the Rh contents for platinum based thermocouples

It is well known that the platinum based thermocouples´ E.M.F. drifts by exposing at high temperatures. The drift occurs by the vapor of the elements mainly, i.e. a branch element vapors and piles up another element. The phenomenon brings the rhodium content difference between each branch smaller. So that the E.M.F. becomes more and more small. In the present study, the amount of the E.M.F. drift is estimated by the rhodium contents analysis and it is compared with the experimentally measured value. Both of the result shows the relatively good agreement. The method will be useful at least in the glass melting industry.