Spectral Emissivity and Its Prediction Models for Metals and Alloys in Solid and Liquid States

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The aims of the present work are to determine normal spectral emissivities for metals and alloys in solid and liquid states using self-produced emissivity measurement apparatuses utilizing an ellipsometer and a cold crucible and to formulate prediction equations for the emissivities on the basis of thermal radiation mechanisms, the achievements for which are itemized as follows :(1)Normal spectral emissivities for pure Cu,Ag,Au,Fe,Co and Ni in solid and liquid states have been measured at the melting points over the wavelength range 500-2500 nm, which has indicated that the emissivities increase on melting of the metals. The prediction equation has been formulated for the emissivities in the wavelength range higher then 1000 nm.(2)Normal spectral emissivities for FZ-Si and pot scrap Si containing about 900 ppm Sb as impurity have been measured at the melting points over the wavelength range 500-1000 nm, which has indicated :・The emissivity of solid Si is larger than that of liquid Si.・ … More Solid Si has positive wavelength dependence but liquid Si has negative.・Additions of Sb of about 900 ppm does not affect emissivity values of Si in both solid and liquid states.In addition, the emissivity of solid silicon has been described using the restrained electron model, whereas that of liquid silicon using the free electron model with damping.(3)Normal spectral emissivities for Ni-Cu binary alloys in solid and liquid states have been measured over the temperature range 800-2000 K, which has indicated・The emissivities for both the solid and the liquid have positive temperature coefficients and are on quadratic functions of the Ni concentration.・The emissivity for the liquid has negative wavelength dependence.Calculation of emissivity using the free electron model with damping could well have described the temperature and compositional dependencies, and contribution from d-electrons to the emissivity has been estimated from the difference between the measured and calculated values. From these findings, the prediction equation has been formulated for the emissivity of this alloy system.(4)Normal spectral emissivities for Ni-Co binary alloys in solid state have been measured for a wavelength of 632.8 nm over the temperature range 300-1600 K, which has indicated that the emissivities decrease with increasing temperature up to the Curie points, above which the emissivities increase.(5)Normal spectral emissivities for Ni-Cr binary alloys in liquid state have been measured over the temperature range 1600-2000 K, which has indicated :・The emissivities for the liquid have positive temperature dependence and negative wavelength dependence, similarly to Ni-Cu alloys.・The compositional dependence can not be expressed by quadratic functions of the Ni concentration, especially at lower wavelengths, differently from Ni-Cu alloys. Less