Elaboration of p-type Ge doped MnSiy (1.73 < y < 1.77) thermoelectric legs with complex shapes by binder jetting additive manufacturing technique

Thermoelectric legs with complex geometries exhibit high potential interest for fatal heat conversion into electricity due to higher thermal dissipation. Additive manufacturing (AM)is a solution of choice to decrease the manufacturing cost of thermoelectric legs that are historically requiring lengthy and costly fabrication processes and it gives the possibility of custom legs geometry. Nevertheless, microcracks and high porosity are commonly present by using this kind of process for thermoelectric materials leading to by limited performances. This work reports the possibility to manufacture n type Ge doped MnSi y (1.73 < y < 1.77) thermoelectric legs with various shapes without microcracks and with low porosity using the binder jetting AM technique followed by a Spark Plasma Sintering (SPS) step. The Mn$₁₅$Si$₂₆$ phase in the samples is systematically present, the samples density can reach 98 %. A power factor of 1130 µW.m$^-1$K$^-2$ was reached at 350° C which is within the range of those obtained by the conventional technique of elaboration, proving that the material is not degraded using this novel route. It is mainly due to the good density and the absence of microcracks. Elaboration of legs with various geometry (cuboid and layered) was done to demonstrate the interest of this innovation manufacturing route. The benefit impact of the geometry was evaluated in term of voltages by a comparison measurement between a cuboid and a layered sample for which a remarkable gain of 16.5 % (at an applied temperature of 74.7° C) was obtained for the layered sample due to a better thermal dissipation.