Temperature-Resolved Infrared Spectral Emissivity of SiC and Pt–10Rh for Temperatures up to 900°C

Abstract

This article reports the first comprehensive results obtained from a fully functional, recently established infrared spectral-emissivity measurement facility at the National Institute of Standards and Technology (NIST). First, sample surface temperatures are obtained with a radiometer using actual emittance values from a newly designed sphere reflectometer and a comparison between the radiometer temperatures and contact thermometry results is presented. Spectral emissivity measurements are made by comparison of the sample spectral radiance to that of a reference blackbody at a similar (but not identical) temperature. Initial materials selected for measurement are potential candidates for use as spectral emissivity standards or are of particular technical interest. Temperature-resolved measurements of the spectral directional emissivity of SiC and Pt-10Rh are performed in the spectral range of 2-20 µm, over a temperature range from 300 to 900 • C at normal incidence.Further, a careful study of the uncertainty components of this measurement is presented.

Apparatus for measuring the emittance of materials from far infrared to visible wavelengths in extreme conditions of temperature

“…This is also a specific wavenumber for which the emissivity does not evolve with temperature. In the case of platinum, a X point occurs at 2.5 lm [19,20] A measurement of the reflectivity of the material versus temperature is a mean to obtain the emissivity at the X point if it is not already known. Fig.…”

Use of a High-Temperature Integrating Sphere Reflectometer for Surface-Temperature Measurements

“…[7], of which only a short summary is presented within this section. The uncertainty consists primarily of four different components, from the repeatability of the temperature measurement, the reflectance measurement, the radiometer calibration, and the size-of-source-effect (scatter) of the interface optics; and each of these four components may have different contributions.…”

“…The results were used to finalize the sphere design that is being used in the facility. In a companion paper [7], we describe the results of spectral directional emittance measurements of two materials using the facility. In this paper, we describe the sample temperature measurements used in the emittance calculation for the materials.…”

Measurements of the directional spectral emissivity based on a radiation heating source with alternating spectral distributions

“…Many measurement methods have been developed to measure the spectral emissivity of materials at various temperatures and spectral ranges. The direct measurement method of the spectral emissivity was widely used that compare the sample spectral intensity to the blackbody spectral intensity at the same temperature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For example, Rozenbaum et al [4] used a spectroscopic method to measure the directional spectral emissivity of semi-transparent materials for wavelengths of 10-12000 cm À1 and temperatures of 600-3000 K with the sample heated by a carbon dioxide laser.…”