Investigation on the melting and freezing behaviours of pure Si cell for thermocouple calibration
Abstract
The melting and freezing behaviours of pure Si contained in alumina crucible were investigated using a monitoring Pt/Pd thermocouple. To induce melting and freezing, furnace temperatures were controlled from ± 3 °C to ± 10 °C. The melting and freezing temperatures coincided within 10 mK at the offset temperature of ± 3 °C, showing a good consistency. The melting and freezing plateau temperature varied with offset temperature, and melting had much smaller offset temperature dependence. The freezing temperature showed a good reproducibility of about 20 mK (1 σ) regardless of the offset temperature. After repeated 9 phase transitions at high temperature, it turned out that it was not mechanically broken. One drawback of pure Si cell is the formation of white and finite powders inside. This is probably due to evaporation of molten Si and deposition on the surface of alumina components. Finally it is recommended to calibrate high temperature noble metal thermocouples of about 1412 ° C using the freezing point of a pure Si cell made of alumina crucibles.
- Publication:
-
Journal of Physics Conference Series
- Pub Date:
- August 2018
- DOI:
- 10.1088/1742-6596/1065/12/122007
- Bibcode:
- 2018JPhCS1065l2007K