Thermoelectric modules based on silicides - development and characterization

Besides half-Heusler compounds, skutterudites, and lead salts, silicides (especially higher manganese silicides and magnesium silicides) are very promising thermoelectric materials regarding medium temperature applications. Higher manganese silicides and magnesium silicides offer suitable ZT values and are synthesized of non-toxic, cheap and abundant raw materials. In this paper, different contact fabrication strategies for silicides and progress on the development of modules based on silicides for medium temperature application up to 550 °C are discussed. Therefore, several contact materials, brazing solders as well as brazing and soldering methods were investigated. Thermoelectric modules with one to 31 unicouples and a maximum size of 50 mm × 50 mm were assembled. The thermoelectric modules for automotive applications were characterized and compared. Their performances are presented as well as cycling and stability test results.