Nano Lett. 2015 Jul 08;15(7):4745-51. doi: 10.1021/acs.nanolett.5b01664. Epub 2015 Jun 18.

The Origin of High Thermal Conductivity and Ultralow Thermal Expansion in Copper-Graphite Composites.

Nano letters

Izabela Firkowska, André Boden, Benji Boerner, Stephanie Reich

PMID: 26083322 DOI: 10.1021/acs.nanolett.5b01664

Abstract

We developed a nanocomposite with highly aligned graphite platelets in a copper matrix. Spark plasma sintering ensured an excellent copper-graphite interface for transmitting heat and stress. The resulting composite has superior thermal conductivity (500 W m(-1) K(-1), 140% of copper), which is in excellent agreement with modeling based on the effective medium approximation. The thermal expansion perpendicular to the graphite platelets drops dramatically from ∼20 ppm K(-1) for graphite and copper separately to 2 ppm K(-1) for the combined structure. We show that this originates from the layered, highly anisotropic structure of graphite combined with residual stress under ambient conditions, that is, strain-engineering of the thermal expansion. Combining excellent thermal conductivity with ultralow thermal expansion results in ideal materials for heat sinks and other devices for thermal management.

Keywords: Metal−matrix composites; graphene; graphite; strain; thermal conductivity; thermal expansion; thermal stress

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't