Experimental analysis on the thermal anisotropy of syntactic hollow sphere structures

This research addresses the measurement of the effective thermal conductivity of metallic hollow sphere structures. These structures are fabricated by embedding sintered hollow steel spheres in a polymer matrix. The resulting syntactic foam combines attractive properties such as high specific strength, structural damping and controlled energy absorption with versatile thermal properties. In the present paper, the thermal properties of this material are determined. A novel experimental setup is used that allows the measurement of the directional conductivities in order to investigate thermal anisotropy. The experiment is based on the accurate time-dependent temperature control of a heater plate inside a thermally controlled environment. The effective thermal conductivities are obtained by fitting finite element data to measured transient temperature profiles. By interchanging the alignment of the specimen, thermal anisotropy can be analysed. In addition, the heat capacity of syntactic hollow sphere structures is estimated based on computed tomography data. Results indicate a slight anisotropy of the thermal conductivity that is most likely caused by deformation of the hollow spheres during manufacturing.

► Experimental analysis of thermal conductivity of syntactic hollow sphere structures.
► Analysis of thermal anisotropy.
► Novel experimental setup.
► Micro-computed tomography based calculation of effective specific heat capacity.