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Normal total emittance of nickel at its melting point


K. Boboridis1, A. Seifter2 and A. Obst3

1Joint Research Centre of the European Commission, Institute for Transuranium Elements, Karlsruhe, Germany
2Prinsegracht 7, The Hague, The Netherlands
3Los Alamos National Laboratory, New Mexico, USA

Keywords: emissivity, emittance, melting, pulse heating, infrared pyrometry;
property: total emittance
material: nickel

Ribbon-shaped nickel specimens were resistively self-heated from room temperature to their melting point in less than 1 s by the passage of a large electric-current pulse provided by a battery-based pulse-heating system. The thermal radiance emitted by a specimen during heating was measured as a function of time in four spectral bands (in the nominal range of 1.5 to 5 um) using a high-speed fiber-coupled four-channel infrared pyrometer. Melting of a specimen was indicated by a plateau in the recorded radiance-versus-time traces. From the measured radiances along the melting plateau and the accepted melting temperature of nickel we derived the melting-point normal spectral emittance (NSE) of liquid nickel at the effective wavelengths of the four pyrometer channels [1]. Our measurements were then combined with shorter-wavelength data acquired in the past at the same pulse-heating facility [2], in order to provide a fit of the melting-point NSE of liquid nickel down to 0.53 um. We also extrapolated our data to longer wavelengths based on the prediction of the Hagen-Rubens relation and on a room-temperature measurement of the NSE of one specimen up to 18 um. Having covered the spectral range in which a blackbody at the melting point of nickel emits over 99% of its total radiance, we obtained the normal total emittance of liquid nickel at its melting point by integration.

References
  1. K. Boboridis, A. Seifter, A.W. Obst, D. Basak, Int. J. Thermophys. 28, 683 (2007)

  2. E. Kaschnitz, J.L. McClure, A. Cezairliyan, Int. J. Thermophys. 19, 1637 (1998)

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