Total Hemispherical Emissivity of Potential Structural Materials for Very High Temperature Reactor Systems: Alloy 617

Abstract

Total hemispherical emissivity of Alloy 617 was measured for applications in very high  temperature reactors with apparatus based on ASTM Standard C835-06. The emissivity data were obtained for the following surface conditions: (1) as-received (rolled sheets) from manufacture, (2) sandblasted with aluminum oxide beads, (3) oxidation in air at temperature of 1153 K, and (4) coated with graphite powder. For the as-received Alloy 617, emissivity increased from 0.26 to 0.34 over the temperatures 593 K to 1164 K. Sandblasting Alloy 617 with alumina beads increased the emissivity to 0.46 to 0.73 in the temperature range 600 to 1300 K (emissivity increased further when higher grit size beads were used). The oxidation of Alloy 617 gave a slight increase in emissivity from 900 to 1250 K with larger increases above 1100 K. Coating of graphite onto as-received and 60-grit sandblasted increased the emissivity by roughly 0.12 and 0.20, respectively, over the measured temperature range.

Keywords:

• Total hemispherical emissivity
• Alloy 617
• Haynes 617

Acknowledgments

This research was supported by the U.S. Department of Energy through grants NERI-C-08-043 and NEUP-5252. Support for Walton and Maynard was provided by the NRC through the NRC Graduate Fellowship Program and by the U.S. Department of Education through the Graduate Assistance in Areas of National Need Fellowship Program.