Improving the oxidation resistance of thermoelectric Mg2Si leg with silica coating

Due to the volatile and oxidation nature of Mg, Mg2Si based thermoelectric legs degrade faster when exposed to ppm level of oxygen during mid-temperature range operation. Here, we have established a modified sol-gel technique to get an oxidation-resistant SiO2 coating on the Mg2Si thermoelectric legs. The cyclic thermal ageing stability, oxidation resistance, and thermoelectric properties of the SiO2 coated Mg2Si have been investigated. The SiO2 coated Mg2Si is stable after ageing for 200 h at 823 K in air, and there is no degradation in the thermoelectric properties due to atmospheric exposure. It is thus a promising technique to increase the life span of Mg2Si based thermoelectric materials for waste heat recovery in automobiles and heavy industries.