Processing, Characterization, and Oxidation Resistance of Glass-Ceramic Coating on CoSb3

Abstract

Power generation based on thermoelectric (TE) materials is very attractive due to its low environmental impact and waste heat recovery. Thermoelectric materials based on cobalt triantimonide CoSb3 exhibit one of the highest energy conversion efficiencies, revealing thermoelectric figures of merit, ZTs > 1, but undergo oxidation above 380 °C and sublimation above 500 °C. In this work, a glass-ceramic coating was chosen to match the coefficient of thermal expansion (CTE) of the TE substrate 9.2 × 10−6 K−1 (200–400 °C), deposition temperature (max. 700 °C), and maximum working temperature (600 °C). Coating processing involved the production of glass powder and glass-ceramic sintering. The glass-ceramic and the coating/CoSb3 interface were systematically investigated by means of dilatometry, X-ray diffraction, and scanning and transmission electron microscopy. As a result, a coating with good substrate coverage and adherence was developed. Finally, oxidation tests were carried out at 500 and 600 °C in order to assess the protective properties of the glass-ceramic. Microstructural and chemical composition analysis indicated limited protective properties of the coating.

Low-Cost Magnesium-Based Thermoelectric Materials: Progress, Challenges, and Enhancements

“…120 The most common coatings for high-temperature TE applications include oxides, nitrides, silicides, borides, carbides, or their mixtures. 121 Coatings like Si 3 N 4 , CrSi, Al 2 O 3 , ZrO 2 , NbN, WN, TaN, MgAlO 4 , Enamel, Nano-SiO 2 , Mo/SiO x multilayer, composite glass, aerogel, and heat resistance paint have been used to protect Skutterudites TE legs. [117][118][119]122,123 Silica-based glass and glass− ceramic coatings have been used to protect PbTe up to 773 K, 124 MnSi up to 873 K 125 and Bi 2 Te 3 -based TE materials as well.…”