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Fabrication and Thermoelectric Properties of n‑Type CoSb2.85Te0.15 Using Selective Laser Melting

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journal contribution
posted on 04.04.2018, 00:00 by Yonggao Yan, Hongquan Ke, Jihui Yang, Ctirad Uher, Xinfeng Tang
We report a nonequilibrium fabrication method of n-type CoSb2.85Te0.15 skutterudites using selective laser melting (SLM) technology. A powder of CoSb2.85Te0.15 was prepared by self-propagating high-temperature synthesis (SHS) and served as the raw material for the SLM process. The effect of SLM processing parameters such as the laser power and scanning speed on the quality of the forming CoSb2.85Te0.15 thin layers was systematically analyzed, and the optimal processing window for SLM was determined. A brief postannealing at 450 °C for 4 h, following the SLM process, has resulted in a phase-pure CoSb2.85Te0.15 bulk material deposited on a Ti substrate. The Seebeck coefficient of the annealed SLM prepared bulk material is close to that of the sample prepared by the traditional sintering method, and its maximum ZT value reached 0.56 at 823 K. Moreover, a Ti–Co–Sb ternary compound transition layer of about 70 μm in thickness was found at a dense interface between CoSb2.85Te0.15 and the Ti substrate. The contact resistivity was measured as 37.1 μΩcm2. The results demonstrate that SLM, coupled with postannealing, can be used for fabrication of incongruently melting skutterudite compounds on heterogeneous substrates. This lays an important foundation for the follow-up research utilizing energy efficient SHS and SLM processes in rapid printing of thermoelectric modules.