Fabrication of large size FeSi2 thermoelectric device by thermal spraying process

To apply a thermoelectric device to power generation from waste heat from an incinerator or steel factory, large size thermoelectric device or module is required. Thermal spraying is the potential candidate as a processing tool for such a device because it enables a thick layer (to 5 mm or more) to be formed with a simple and short process on large plates or long pipes, which can be inserted directly within the furnace or heat exchanger. Co-doped n-type FeSi₂ powder was prepared, and a thermoelectric device was formed by plasma spraying with 43 kW plasma under inert atmosphere. FeSi₂ layer with the thickness of 3-5 mm was formed on a stainless steel (SUS430) plate (100×100 mm) and pipe (diameter: 25 mm). The properties, microstructure and performance of thermal sprayed beta-FeSi ₂ thermoelectric device was evaluated