A technique for evaluation of long-term stability of thermocouples at high temperatures above 1000℃

摘要

Thermocouples are widely used in industry to measure high temperatures. However, their electromotive force changes (drifts) when exposed to high temperatures, and therefore the evaluation of the drift is very important to establish reliable measurements. To monitor the drifts accurately, a stable fixed point is usually used as a reference. As recently reported, the metal-carbon eutectic points are found to be practical reference points for the calibration of thermometers. In our project, cobalt-carbon (Co-C) eutectic (1324℃) cells for thermocouple calibration were constructed and evaluated. Based upon this development, thermocouple calibration service is provided at the Co-C eutectic point by National Metrology Institute of Japan, AIST.