Effective thermal conductivity of metallic foams determined with the transient plane source technique

Abstract

This article presents experimental results of thermal conductivity in metal foams. The thermal conductivity of cellular solids differs from those of their corresponding dense material. Therefore, the various pore size level effects contributing to the thermal conductivity are comprised by introducing an effective thermal conductivity. In this work we investigated metallic foams with a porosity ranging from 0.65 to 0.82 manufactured by the Slip Reaction Foam Sintering (SRFS) Process using a nickel-based powder. For the determination of the effective thermal conductivity at room temperature, we employed the Transient Plane Source Technique also known as Hot Disk. We verified the influence of the porosity and the thermal conductivity of the solid phase on the effective conductivity and compared the measured values of the effective conductivity with theoretical ones calculated using the thermal conductivity of the solid phase and the solid volume fraction. We present here a simple model that demonstrates the influence of the geometry of the grid elements qualitatively, discuss the applicability of the method to heterogeneous materials such as metallic foams and give an outlook about further investigations at higher temperatures.