Glass-ceramic oxidation protection of higher manganese silicide thermoelectrics. Issue 1 (January 2019)

• Record Type: Journal Article
• Authors: Salvo, M.; Smeacetto, F.; D'Isanto, F.; Viola, G.; Demitri, P.; Gucci, F.; Reece, M.J.
• Is Part Of: Journal of the European Ceramic Society. Volume 39:Issue 1(2019)
• Page Start: 66
• Page End: 71
• Publication Date: 2019-01
• Subjects: Glass-ceramic -- Coating -- Thermoelectric -- Oxidation; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2018.01.007
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: 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.