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High temperature reflectometer for spatially resolved spectral directional emissivity of laser powder bed fusion processes

Published

Author(s)

David C. Deisenroth, Leonard M. Hanssen, Sergey Mekhontsev

Abstract

Additive manufacturing involving layer-wise selective laser melting of a powder material, or laser powder bed fusion (LPBF), is a fast-growing industry. At the Additive Manufacturing Metrology Testbed (AMMT) at the United States National Institute of Standards and Technology (NIST) an integrating hemispherical reflectometer has recently been developed to facilitate measurements of spatially resolved reflectance of the laser-melting heat affected zone (HAZ) during the LPBF process. Reflectance is then used to determine spatially resolved emissivity. The design features of the hemispherical-directional reflectometer are discussed. Then, the reflectometer performance and measurement uncertainties are detailed. A two-dimensional map of emissivity and emissivity uncertainty of the HAZ around a meltpool of high-purity nickel are presented. It is found that emissivity measurements are in good agreement with literature values at the melting point of high-purity nickel with acceptable uncertainty.
Volume
11485
Conference Dates
August 24-28, 2020
Conference Location
san diego, CA
Conference Title
Reflection, Scattering, and Diffraction from Surfaces VII

Keywords

High-temperature baffle-less reflectometer, emissivity of high-temperature metals, laser powder bed fusion
Created August 25, 2020, Updated October 21, 2020