Particle aspect-ratio effects on the thermal conductivity of micro- and nanoparticle suspensions

The influence of particle anisotropy on the effective thermal conductivity of a suspension is experimentally investigated. Suspensions of micron-sized, silicon-carbide particles with varying aspect-ratio distributions were prepared and measured. It is shown that the conductivity of the silicon-carbide suspensions can be quantitatively predicted by the effective medium theory of Nan (1997, Effective Thermal Conductivity of Particulate Composites With Interfacial Thermal Resistance, J. Appl. Phys. 81(10), pp. 6692-6699), provided the volume-weighted aspect ratio of the particles is used. Recent experimental data on multiwalled-nanotube-in-oil suspensions by Yang (2006, Thermal and Rheological Properties of Carbon Nanotube-in-Oil Dispersions, J. Appl. Phys., 99(11), 114307) are also analyzed and shown to be in at least qualitative agreement with the effective-medium-theory prediction that the thermal conductivity of suspensions is enhanced by large aspect-ratio particles.