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What is the reason for the error of the thermocouple of the experimental electric furnace

What is the reason for the error of the thermocouple of the experimental electric furnace

(1) The instability of the thermocouple refers to the division value of the thermocouple, which will change with the time of use and the different conditions of use. In most cases, it may be the main reason for inaccuracy, and the factors that cause instability are: thermocouple volatilization, oxidation, reduction, embrittlement, crystallization, contamination, etc. at high temperature.

(2) If the thermocouple is made of a homogeneous conductor, its thermoelectric potential is only related to the temperature at both ends. If the thermocouple material is not uniform and the thermocouple is in a temperature gradient field, the thermocouple will produce an additional The thermoelectric potential depends on the temperature gradient distribution along the length of the thermoelectrode, the uneven form and degree of the material, and the position of the thermoelectrode in the temperature field.