溶射法によるSi-Ge系熱電皮膜の作製と特性改善

抄録

For the energy saving, thermoelectric conversion materials (TEC) are attracting much attention. However, the conversion efficiency of thermoelectric materials is remarkably low in the single element compared to the other conventional power generations. Therefore, the thermoelectric elements have to be composed as the thermo-module in which the huge numbers of the elements are connected. In many configurations of TEC, the thick coating may be advantageous in joining or laminating.
The plasma spraying, which was characterized to be a high deposition rate process, was used to fabricate the thick coating of the thermoelectric elements. We previously reported that β-FeSi₂ thermoelectric coating could be fabricated by plasma spraying, and the thermoelectric property was the same as the bulk material.
In this study, the Si-Ge system was focused because of its excellent thermoelectric property in a high temperature range. Moreover, the spraying and some treatments were applied for improving the thermoelectric properties with the aim of clarifying the conditions to fabricate high performance Si-Ge TEC coating.
The results obtained are summerized as follows;
(1) MA-spraying process could be applied for the fabrication of SiGe thermoelectric coating.
(2) The boundary at the joined layers in the case of FGM coating was diminished by polishing the coating surface before spraying the next layer. Joint type FGM coating of Si-Ge doped with different fractions of P could be fabricated by plasma spraying.
(3) The thermoelectric coating made from the granulated powder had a quite fine and dense microstructure. The resistivity of the coating decreased to one-tenth of coating made from the conventional MA powder, and consequently its power factor reached the level over than that of the sintered body.