Performance Characteristics of Custom Thermocouples for Specialized Applications

This work reports the performance characteristics of custom thermocouples developed for use in elevated temperatures such as metal casting operations. The scope of this research is limited to thermocouples designed using pyrolytic graphite (PG) as the primary thermoelement in connection with aluminum, copper, steel, and tungsten. The Seebeck coefficients of the sensors were determined from experimental data after heating to similar to 500 degrees C. Cooling from similar to 500 degrees C to room temperature enabled us to compare the characteristic behaviors of the sensors from the obtained near-linear responses in the voltage-temperature plots. Tungsten being a refractory metal produced the highest sensitivity of the sensors. The sensitivity of the PG-tungsten thermocouple upon heating measured up to 26 mu V/degrees C and a slightly lower value of 24.2 mu V/degrees C was obtained upon cooling. Conversely, the PG-steel thermocouple rather produced the lowest Seebeck coefficients of 13.8 mu V/degrees C during heating and 14.0 mu V/degrees C for the cooling experiments though steel has a high melting temperature than most of the other thermoelements.

Automated summary

This study reports the performance characteristics of custom thermocouples developed for use in elevated temperatures, with pyrolytic graphite as the primary thermoelement. The thermocouples were tested at around 500 degrees C, with tungsten thermocouples showing the highest sensitivity and steel thermocouples showing the lowest Seebeck coefficients.