Abstract
To improve the interfacial stability at high temperatures, n-type skutterudite (SKD) thermoelectric joints with sandwich structures of Ti/Mo/Yb0.3Co4Sb12 were successfully designed and fabricated. In this structure, Mo and Ti were introduced as the barrier layer with the goal of suppressing the interfacial diffusion and the buffer layer with the goal of enhancing the bonding strength, respectively. To evaluate the high temperature interfacial behavior of the Ti/Mo/Yb0.3Co4Sb12 joints, thermal shocking between 0 °C and 600 °C and isothermal aging at a temperature range of 550 °C to 650 °C were carried out in vacuum. During the isothermal aging process, Ti penetrates across the Mo layer, and finally diffuses into the Yb0.3Co4Sb12 matrix. By increasing the isothermal aging time, Ti continuously diffuses and reacts with the elements of Sb and Co in the matrix, consequently forming the multilayer-structured intermetallic compounds of Ti3Sb/Ti2Sb/TiCoSb. Diffusion kinetics was investigated and it was found that the interfacial evolution of the Ti/Mo/Yb0.3Co4Sb12 joints was a diffusion-controlling process. During the diffusion process, the formed Mo-Ti buffer layer acts as a damper, which greatly decelerates the diffusion of Ti towards the Yb0.3Co4Sb12 matrix at high temperatures. Meanwhile, it was found that the increase in the contact resistivity of the joints mainly derives from the inter-diffusion between Ti and Yb0.3Co4Sb12. As a result, the Ti/Mo/Yb0.3Co4Sb12 joint demonstrates the excellent stability of the interfacial contact resistivity. Service life prediction was made based on the stability of the contact resistivity, and it was found that the Ti/Mo/Yb0.3Co4Sb12 joint is qualified for practical applications at 550 °C.
Highlights
Diffusion kinetics was investigated and it was found that the interfacial evolution of the Ti/Mo/Yb0.3 Co4 Sb12 joints was a diffusion-controlling process
It was found that the increase in the contact resistivity of the joints mainly derives from the inter-diffusion between Ti and
Service life prediction was made based on the stability of the contact resistivity, and it was found that the Ti/Mo/Yb0.3 Co4 Sb12 joint is qualified for practical applications at 550 ◦ C
Summary
Unlike traditional power generation systems, a thermoelectric power generator (TEG) produces electrical power based on the Seebeck effect, via the movement of charge carriers within thermoelectric materials under a temperature difference. Using the heat from radioisotopes, TEGs can supply electrical power for tens of years, and are the only choice of power source for deep space explorers which fly far from the sun and can no longer obtain sufficient sunlight energy [1,2]. TEGs have been regarded as one of the most promising candidates to recover waste heat from industries or automobiles and turn them into electricity [3,4], which can benefit from the remission of the fossil energy shortage and global warming.
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