Oxidation protective glass coating for magnesium silicide based thermoelectrics

Abstract A Mg2Si–Mg2Sn based thermoelectric material (TE), with composition of Mg2Si0·487Sn0·5Sb0.013, produced by ball-milling combined with spark plasma sintering, is successfully coated with a new silica-based glass, which is specifically designed, characterised and tested as an oxidation protective coating for mid-temperature range (up to 500 °C) applications. Despite the relatively high coefficient of thermal expansion (CTE) of Mg2(Si,Sn) based materials, very good thermo-mechanical compatibility between the substrate and the coating material is obtained. Oxidation tests, performed at 500 °C for 120 h in air, demonstrate the effectiveness of the glass coating for the protection of Sb doped Mg2(Si,Sn) thermoelectric materials.