Ultra-High Temperature Thermoelectrics

Hypersonic vehicles need compact, high temperature capable power sources since batteries are not sufficiently compact and require insulation. A thermoelectric (TE) energy-harvesting system converts thermal energy into electricity by taking advantage of the temperature difference between two surfaces. The objective of this effort is to increase the temperature limits of current TE materials from approximately 600 ?C to 1250 ?C while achieving a figure of merit (ZT) above 1. During Phase I we will develop thermoelectric generator concepts using thermally stable silicon carbide nanofibers. The nanofibers will be aligned and encapsulated in thermally stable aerogel to insulate the hot from the cold side and improve the figure of merit. The materials will be characterized by determining electrical conductivity, thermal conductivity, and the Seebeck coefficient as a function of temperature up to the expected maximum use temperature. We will develop predictions of expected TE figure of merit and thermoelectric efficiency. If awarded a Phase I Option, the materials will be characterized by SEM and TEM to image grain and lattice structure of materials heated to a maximum of 1250 ?C and the images will be used to understand the morphology and structure of the TE devices.