Heat release measurements on micron and nano-scale aluminum powders

Aluminum nanoparticles are a focus of active research largely due to their attractive oxidation energetics and fast reaction kinetics compared with micron-scale or larger particles. A large number of different aluminum powders are currently available and the present study reports the results from a side-by-side comparison of several representative types of aluminum nanoparticles. Conventional oxide-passivated micron-scale and nano-scale powders, as well as organically passivated nanoparticles were studied using pyrolysis combustion flow calorimetry (PCFC) at temperatures up to 700 °C. The reaction onset temperature and extent of oxidation were observed to depend on particle size. A multi-step oxidation process was observed, with the individual steps becoming increasingly pronounced at smaller particle sizes. The results from PCFC testing gave useful insight into the oxidation behavior of these materials, especially the organic passivated particles, but, under these oxidation conditions the materials were not fully oxidized.