Few large and many small, how to control the thermal behavior of composite materials

Abstract

Here we show that the distribution of the pore sizes within a solid matrix can contribute to improving the thermal insulation of composite materials. Building on the analogy between species diffusion through saturated porous materials and heat conduction through composite materials made of a solid matrix and air spheres, we develop a methodology to allocate the air space in such a way that the thermal conductivity decreases. The methodology relies on the few-large-and-many-small approach in which the largest air spheres are step-by-step replaced by smaller ones while maintaining the overall porosity constant. Finally, a numerical example highlights the potential of such composite material to act as a thermal barrier in high temperature applications.