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3853 |
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Friday, May 23, 2014, Hall H2 9:20 AM Power Generation - Steam |
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Technological approach for a full thermally sprayed thermoelectric generator |
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Maria Manuel Barbosa / Fraunhofer Institut für Werkstoff- und Strahltechnik (IWS)
Abt. Thermische Beschichtungsverfahren, Deutschland Roberto Puschmann* / Fraunhofer IWS, Germany Stefan Scheitz/ Fraunhofer IWS, Germany Lutz-Michael Berger/ Fraunhofer IWS, Germany Christoph Leyens/ Fraunhofer IWS, Germany Eckhard Beyer/ Fraunhofer IWS, Germany |
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The manufacture of economic profitable thermoelectric generators (TEG) requires effective manufacturing technologies. Thermal spraying represents such a potential efficient technology, but meets challenges both from material and technological side. Basically four classes of materials are required for the manufacture of a TEG, which can be prepared as a thermally sprayed multilayer. These are electrical insulators, electrical conductors and the thermoelectric materials the p- and n-semiconductors. Properties of the sprayed materials depend both on the spray process and the feedstock powder properties. In this paper, different thermal spray processes (APS, HVOF, HVAF) using feedstock powders and suspensions) were used to deposit the four classes of materials previously described. A particular challenge is to obtain a perfect bonding between the different coatings, which is most difficult for spraying metallic coatings on to previously deposited ceramic coatings. In addition, for the manufacture of a fully thermally sprayed TEG, several layers, such as the n- and p-semiconductors, have to be located on one level in the multilayer. This requires the development of effective masks. Indirect masking and direct masking (fixed directly on the substrate) can be used. After process optimization for each individual material, different complex multilayered systems were produced by using unique masks. The multilayer cross sections have been studied by optical microscopy. |