Study of the Radiative Properties of Heat Resisting Metals and Alloys : (1st Report, Optical Constants and Emissivities of Nickel, Cobalt and Chromium)

Ellipsometric Determination of Normal Spectral Emissivities at 632.8 nm for Solid Ni–Co Alloys at High Temperature

“…8) by less than 10 % difference, and the value at 1 700 K extrapolated from the present experimental data is greater by about 10 % than the value reported by Watanabe et al 6) The emissivity data for Ni-65.6%Co are also in good agreement with those reported for Ni-65%Co by Wahlin and Knop 3) including the complicated behaviour around its Curie point: Wahlin and Knop measured the emissivities using a disappearing filament optical pyrometer and thus the measured wavelength cannot be specified. For Co, the value measured for room temperature in the present work is in very good agreement with the corresponding value reported by Makino et al 4) However, the measurement could not be made at temperatures higher than its Curie point due to the surface roughness arising from the phase transformation from hcp to fcc structures at 673 K, and the temperature dependence of the emissivity has not been obtained clearly. Furthermore, when samples were oxidised due to improper atmosphere control, emissivity values obtained were approximately twice as large as those shown in the figure.…”

“…There is only one report available for emissivity data of the alloy 3) although several studies have been made on nickel and cobalt. [3][4][5][6][7][8] Furthermore, emissivity measurements on Ni-Co alloys are of scientific interest because these alloys form complete solid solution in certain temperature ranges, in which the alloys experience magnetic transformation. Table 1 gives nominal chemical compositions (in at%) of Ni-Co alloy samples used in the present work.…”

Normal spectral emittance of a nickel metal surface with rectangular microcavities

“…The normal spectral emittance of the microcavity surface was estimated as follows: Figure 6 shows the normal spectral emittances of the microcavity and flat surfaces over a wide range of wavelengths from 0.78 to 4.0 µm at a temperature of 1052 K. It also shows the results for the flat surface obtained through the reflection method at temperatures of 699 K, 902 K, 1102 K, and 1302 K [12] and obtained at 1428 K after a long-duration thermal treatment at a temperature above 1256 K in a vacuum chamber [13].…”

New Spectrophotometer System for Measuring Thermal Radiation Characteristics of Real Surfaces of Thermal Engineering Entirely

“…In the spectral measurement, reflection spectra of 93 wavelength points of λ=0.30~11 µm and emission spectra of 42 wavelength points of λ=2.0~11 µm are measured simultaneously and repeatedly with a cycle time of 6 s. Absolute values of normal reflectance R HN for hemispherically homogeneous incidence and normal incidence specular reflectance R NN are determined on the basis of a specular reflection spectrum measured on a clean optically smooth nickel surface and a published spectra of the optical constants (10) .…”

“…The diffuse reflectance R ND is zero over the spectral region of the present experiment. The hemispherical reflectance R NH is equal to specular reflectance R NN , and the specular reflectance R NN is calculated by the spectra of optical constants of nickel (10) . With an increase of wavelength λ, specular reflectance R NN increases monotonously and absorptance A N (=1-R NH ) decreases monotonously.…”