Spectral-Directional Emittance of CuO at High Temperatures

Spectral-directional emittance measurements for cupric oxide (CuO) are presented. The data cover polar angles of $0-84deg$ from the surface normal, wavelengths between 1.5 and $8μm$⁠, and temperatures between 400 and $700°C$⁠. The data were generated using a radiometric, direct emission measurement method. The oxide was grown on a very clean, smooth, and mirror-like copper surface, heated in air at $700°C$ until emission measurements became constant $(270h)$⁠. X-ray diffraction and EDS analyses were performed to characterize the spatial and molecular composition of the copper oxide layer. It is generally found that CuO emittance decreases with increasing polar angle, increases with increasing wavelength, and increases with increasing temperature. Spectral-directional emittance values calculated from the Fresnel relations show good agreement with the measurements up to polar angles of $72deg$⁠.