Higher manganese silicide (HMS) and magnesium silicide are considered promising thermoelectric materials to generate electricity from waste-heat recovery. However, a critical issue is their stability over time and their oxidation resistance at temperatures above 500°C. Glass-based materials, due to their low electrical and thermal conductivity, are good candidates as protective coatings. In this work, MnSi1.74 and Mg2Si0.487Sn0.5Sb0.013 substrates, densified by spark plasma sintering, were coated with silica-based glass-ceramic materials in order to provide oxidation protection. The thermal cycling stability (from room temperature to 600°C in air) of as-sintered and glass-ceramic coated HMS was studied, with respect to changes in their chemical composition and electrical properties. The formation of a Si-deficient layer on the uncoated HMS, due to the reaction between HMS and oxygen at 600°C, led to a higher electrical resistivity as well as a reduced power factor. The coated samples did not show variations in electrical properties compared to the as-sintered one, thus demonstrating that the use of a glass-ceramic coating is an efficient oxidation protective system during cyclic working conditions. Moreover, a new silica-based glass-ceramic coating for magnesium silicide was designed in order to improve the long-term reliability of the thermoelectric module and its efficiency.

Glass-ceramic oxidation protective coatings for manganese- and magnesium-based thermoelectric silicides / D’Isanto, F.; Salvo, M.; Smeacetto, F.; Gucci, F.; Chen, K.; Reece, M.. - ELETTRONICO. - UNICO:(2019), pp. 134-134. (Intervento presentato al convegno 43rd International Conference & Exposition on Advanced Ceramics and Composites tenutosi a Daytona, Florida (USA) nel 27 gennaio – 1 Febbraio , 2019).

Glass-ceramic oxidation protective coatings for manganese- and magnesium-based thermoelectric silicides

F. D’Isanto;M. Salvo;F. Smeacetto;
2019

Abstract

Higher manganese silicide (HMS) and magnesium silicide are considered promising thermoelectric materials to generate electricity from waste-heat recovery. However, a critical issue is their stability over time and their oxidation resistance at temperatures above 500°C. Glass-based materials, due to their low electrical and thermal conductivity, are good candidates as protective coatings. In this work, MnSi1.74 and Mg2Si0.487Sn0.5Sb0.013 substrates, densified by spark plasma sintering, were coated with silica-based glass-ceramic materials in order to provide oxidation protection. The thermal cycling stability (from room temperature to 600°C in air) of as-sintered and glass-ceramic coated HMS was studied, with respect to changes in their chemical composition and electrical properties. The formation of a Si-deficient layer on the uncoated HMS, due to the reaction between HMS and oxygen at 600°C, led to a higher electrical resistivity as well as a reduced power factor. The coated samples did not show variations in electrical properties compared to the as-sintered one, thus demonstrating that the use of a glass-ceramic coating is an efficient oxidation protective system during cyclic working conditions. Moreover, a new silica-based glass-ceramic coating for magnesium silicide was designed in order to improve the long-term reliability of the thermoelectric module and its efficiency.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2744832
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