An experimental study on the thermal conductivity of aluminium foams by using the transient plane source method

The thermal conductivity of a collection of AlSi7 foams with porosities between 0.5 and 0.8 produced throughout the powder metallurgical route has been determined using the transient plane source technique (TPS). Several measurements have been performed on different surfaces of the foam blocks. The values obtained have shown an increase of effective thermal conductivity with density and a significant dependency with the zone of the foam where the experiments were performed. The results obtained have been explained in terms of local density trough images obtained from computed tomography, showing that the TPS technique is sensitive to in-homogeneities derived from the foaming process. Finally, several theoretical models for thermal conductivity have been unified, after suitable simplifications for this kind of materials, and have been compared with the experimental results.