A higher manganese silicide (HMS) thermoelectric, with composition MnSi1.74, densified by spark plasma sintering, was successfully coated with a glass-ceramic, in order to be used at temperatures higher than 500°C. Compositional changes in both the HMS substrate and the glass-ceramic coating are reviewed and discussed with respect to the electrical properties of the uncoated and coated HMS before and after thermal cycles from RT to 600°C in air. The formation of a Si-deficient layer (MnSi) on the uncoated HMS surface is due to the reaction between the HMS and oxygen at 600°C, thus contributing to a lower power factor in comparison with the as-sintered HMS. Coated HMS samples (after thermal cycles RT-600°C) show a lower electrical resistivity and a significantly higher power factor in comparison with the uncoated ones. The glass-ceramic coating is self-reparable at 600°C, as demonstrated by the complete sealing of an induced scratch on its surface.
|Titolo:||Glass-ceramic oxidation protection of higher manganese silicide thermoelectrics|
|Data di pubblicazione:||2019|
|Digital Object Identifier (DOI):||10.1016/j.jeurceramsoc.2018.01.007|
|Appare nelle tipologie:||1.1 Articolo in rivista|