Processing and Thermal Properties of Multiwall Carbon Nanotube/Bismuth Antimony Telluride Composites for Nuclear Energy Applications

Abstract

In this work the effects of ball milling and carbon nanotubes incorporation on the thermal conductivities of the bulk BiSbTe composites were evaluated. The coarse BiSbTe particles were obtained by crushing BiSbTe lumps and subsequently high energy ball milling was employed in an inert environment to form the fine BiSbTe powder. Multiwall carbon nanotubes in different (0.0, 0.5 and 1.5) vol. % were uniformly mixed in the BiSbTe powder through a combination of ultra-sonication and ball milling, and then processed by rapid high frequency induction heated sintering (HFIHS) to achieve fully dense nanocomposite. Thermal diffusivity of the composites was evaluated and heat capacity was approximated using Pyrocerarm as a reference material. The effect of carbon nanotubes inclusion and BiSbTe particle size reduction on the thermal conductivity was studied from 300 to 500 K. The results show a significant reduction in the thermal conductivity due to the enhanced thermal boundary interface resistance correlated with the fine microstructure/nanostructure in the composites as compared to pristine bulk bismuth antimony telluride.