Abstract
To measure total hemispherical emissivities eTH(T) of metals at low temperatures, a new transient calorimetric technique is developed to improve its accuracy. The accuracy of this technique mainly depends upon heat loss Qt through a thermocouple (TC) which suspends a specimen and measures its temperature. To reduce Qt, an Iron. Constantan TC with diameter of about 20μm is used, and the temperature profile of TC is controlled by a guard heater attached to the other sides of TC. eTH(T) of aluminum specimens which shaped wire (99.9994% purity) and plate (99.988%) are measured in the temperature range from 125 to 350K. The specimens are mechanically polished. The roughness of the plate surface is measured. Qt, evaluated by a combined radiation and conduction heat transfer analysis, is less than 1% of the total power loss of the specimen. eTH(T) for wire and annealed plate are in good agreement with each other, and close to the values extrapolated from the date obtained above room temperature. An increase in eTH(T) of the plate without annealing may be due to the Beilby/damaged surfaces formed by mechanical polishing.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
