Graded thermoelectric materials by plasma spray forming

Abstract

Plasma spraying is a consolidation process for powders with the additional capability of a composition control of the spray formed structures. The paper reports on the first steps to adapt this method to the production of functionally graded thermoelectric materials with a locally maximized figure of merit. Iron disilicide (FeSi2) was used to test the performance of the technique on thermoelectric material. It was found that plasma spray forming is applicable to produce dense materials with thermoelectric properties comparableto hot pressed ones. Problems were however found with the thermal stability of the microstructure. Final goal is the employment of plasma spraying to form compositionally graded materials of the Mg2(Si,Ge,Sn) system. This chapter reports on the preparation and thermoelectric transport properties of Si-rich quasibinary Mg2(Si,Ge) and Mg2(Si,Sn) mixed crystals by mechanical alloying.