The effects of density on thermal conductivity and absorption coefficient for consolidated aluminum nanoparticles

Thermal conductivity and absorption coefficients were determined for a range of bulk densities for consolidated aluminum (Al) nanoparticle pellets by a laser flash analysis technique. Samples where heated on their front face using a Nd:YAG laser (1064 nm wavelength) and the temperature was measured on the rear face as a function of time. COMSOL Multiphysics® was used to model the experimental setup to determine the thermal conductivity and absorption coefficients. Thermal conductivity was found to increase with density from 0.2 to 1 W/(mK) for densities from 1.1 to 2.3 g/cm3 due to increase surface contact between particles. The absorption coefficient was found to range from 0.30 to 0.54 and increase with density for the range of bulk densities investigated. These results provide a fundamental understanding of properties influencing ignition mechanisms in aluminum containing materials.