Enhancement of high temperature thermoelectric performance of cobaltite based materials for automotive exhaust thermoelectric generators

Thermoelectric (TE) generators can directly convert exhaust waste heat into electricity in vehicles. However, the low conversion efficiency of TE generators is the main obstacle to their commercialization in automotive. Their efficiency mainly depends on the performance of the used materials which is quantified by the figure of merit (ZT value). In the present study, single- and co-doped calcium cobaltites(CCO) with rare-earth (Tb) and transition metals (Cu, Fe, Ni, Mn, Cr) were produced using sol-gel technique in order to improve their high temperature thermoelectric properties for heat recovery in exhaust manifold applications. By the combined effect of doping approach and the production technique used in this study, a remarkable decrease in the grain size of CCO was obtained, and thus its thermal conductivity dramatically decreased. Besides, thermopower values were improved significantly. The reduction in thermal conductivity and the increase in thermopower led to an enhancement in ZT value of CCO ceramics. Among all the co-doped samples, Tb-Cu co-doped CCO displayed the maximum ZT value of 0.116 at 873 K which is 2.5 times larger than that of pure CCO. The high thermal stability and the enhanced thermoelectric performance make Tb-Cu co-doped CCO material a potential candidate for heat recovery in automotive exhaust thermoelectric generators.

OUTOKUMPU MODA 439/4510

Outokumpu Moda 439/4510 is a titanium-stabilized 17% chromium ferritic stainless steel that exhibits improved corrosion resistance, formability, and weldability when compared to Outokumpu Moda 430/4016. It is best suited for mildly corrosive environments. Because of its titanium alloying, Outokumpu Moda 439/4510 can be welded in all dimensions without becoming susceptible to intergranular corrosion. It is possible to use Outokumpu Moda 439/4510 at elevated temperatures, for example the cold end of automotive exhaust systems. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1341. Producer or source: Outokumpu Oyj.