N. Batista, A. El Desouky, J. Crandall, S. Wang, J. Yang, S. LeBlanc
The George Washington University,
Keywords: thermoelectric, selective laser melting, 3D printing, powder metallurgy
Summary:Thermoelectric materials are semiconductors capable of converting heat into electrical energy. Traditional manufacturing of thermoelectric devices involves machining and assembly steps which limit device geometries, result in material loss, and introduce parasitic thermal and electrical resistances . Selective laser melting is an alternative manufacturing method that could eliminate the need for arduous assembly steps, enable unique device geometries, and facilitate effective material-to-device integration . While selective laser melting is well-established for processing metals, ceramics, and polymers, it has not been demonstrated on semiconductor materials. Previous work showed melting of compacted bismuth telluride powder using pulsed and continuous wave lasers [2-3]. The study discussed here provides the first-ever analysis of thermoelectric material powders for layer-by-layer manufacturing. The results include analysis of two thermoelectric materials, bismuth telluride (Bi2Te3) and a half-Heusler compound (ZrNiSn), which are optimal for low and high temperature applications, respectively. Particle size distribution and particle morphology are analyzed using optical and scanning electron microscope images. The ability of the powder to flow and spread in 100-300 µm thick layers is assessed using both blade and roller approaches. Preliminary results on the first-ever, 3D-printed thermoelectric material powder using selective laser melting are described.  S. LeBlanc, “Thermoelectric generators: Linking material properties and systems engineering for waste heat recovery applications,” Sustainable Materials and Technologies, 2014.  A. El Desouky, M. Carter, M.A. Andre, P.M. Bardet, S. LeBlanc, “Rapid processing and assembly of semiconductor thermoelectric materials for energy conversion devices,” Materials Letters, 2016.  A. El Desouky, M. Carter, M. Mahmoudi, A. Elwany, S. LeBlanc, “Influences of energy density on microstructure and consolidation of selective laser melted bismuth telluride thermoelectric powder,” Journal of Manufacturing Processes, 2016.