NDLI: Flash spark plasma sintering of magnesium silicide stannide with improved thermoelectric properties

Content Provider	Royal Society of Chemistry (RSC)
Author	Porwal, Harshit Reece, Mike J. Gucci, Francesco Mahajan, Amit Grasso, Salvatore Du, Baoli
Copyright Year	2017
Abstract	Spark plasma sintering has become a routine method for the densification of thermoelectric (TE) materials. However, the impacts and details of direct Joule heating within TE materials have not been fully quantified and clarified. Here we investigated the feasibility of flash-sintering (high heating rate Joule heating) magnesium silicide stannide (MSS) using a spark plasma sintering furnace. A Mg2.1Si0.487Sn0.5Sb0.013 (MSS) green compact was sandwiched between two graphite punches without a die. Then a DC pulse voltage was applied between the punches and the current passed completely though the compact, without any of the current bypassing through a graphite die as occurs with a convectional SPS die–punch system. The direct heating was so efficient that a heating rate of ∼1000 °C was achieved and the sample was fully sintered in less than 45 s. Due to the high local Joule heating at the contacts of the particles, the MgO distribution pattern was modified and optimised, which broke the coated passivation layer on the MSS aggregates. The onset densification temperature was 170 to 350 °C lower than that in convectional SPS (750 °C). Importantly, it was possible to produce dense samples in a wide sintering window of ∼6 s, and the flash-sintering was controllable and repeatable. Flash sintering could open a new way for rapid densification of dense nanostructured and/or textured TE materials with low electrical resistivity by optimising the distribution or removal of the surface oxidation of the powder grains.
Starting Page	1514
Ending Page	1521
Page Count	8
File Format	HTM / HTML PDF
ISSN	20507526
Volume Number	5
Issue Number	6
Journal	Journal of Materials Chemistry C
DOI	10.1039/c6tc05197a
Language	English
Publisher	Royal Society of Chemistry
Access Restriction	Subscribed
Subject Keyword	Joule SPS Spark plasma sintering Thermoelectric effect Joule heating Magnesium silicide Stannide Graphite Super Proton Synchrotron Sintering Passivation (chemistry) The Onset Electrical resistivity and conductivity
Content Type	Text
Resource Type	Article
Subject	Chemistry Materials Chemistry

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