Contacts for PbTe
Environment-friendly thermoelectric (TE) materials have begun to gain attention due to the capability of power regeneration and its negligible carbon emission so as to transform industrial and automotive waste heat into renewable clean energy. Conventionally, commercially available TE modules are based on planar structures. It is of interests that the idea of "ring-shaped" TE legs have been carried out for tubular TE modules for automotive waste heat recovery. The main reliability concerns of TE modules are the thermomechanical stresses from CTE mismatches, the intermetallic growth at the interface, and the sublimation of TE material. Pure Nb foil was also bonded to PbTe-based TE materials as the hot-side contact via hot pressing method. Consequently, appropriate bonding materials and fabrication methods should be developed for PbTe TE modules that allow reliable long-term operation. Similar to Silver Cu was also selected as a bonding material for both PbTe due to its close CTE as well as its well-known electrode properties.