Spectral Emissivity at High Temperatures
Abstract
The status of the high-temperature emissometer at the Properties Research Laboratory is summarized. The emissometer is an adjunct to the Multiproperty Apparatus which provides simultaneous measurement of ten thermophysical properties on the same sample of an electrically-conducting solid under various environmental conditions. The apparatus features rapid time-to- temperature and data acquisition under minicomputer control yielding state-of- the-art accuracy. The calibration of the emissometer, including the incorporation of some new devices and the modification of the calibration data, has been more thoroughly studied. Spectral emissivity measurements in the spectral range 2 to 12 micrometers have been made on tantalum (reference material), silicon nitride (Si3N4), silicon carbide (SiC), and a graphite composite from 1400 deg K to their degradation temperatures. The new data on the ceramics provides better understanding of their high temperature behavior including the effect of fabrication process and impurities. A model has been developed for relating the observed spectral radiance from a small cylindrical sample mounted within a heating tube to the optical properties (indices of refraction and absorption) and emissivity of the sample.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1978
- Accession Number
- ADA062072
Entities
People
- D. P. Dewitt
- Philip E. Johnson
- R. E. Taylor
Organizations
- Purdue University