Ignition, Combustion, and Passivation of Nanopowders

摘要: The nanopowders of metals are pyrophoric, i.e., they capable self-ignite contacting with the air because high chemical activity and large specific surface. There two methods providing explosion safety process: a passive one, based on systems warning undesirable changes in process, an active assuming change technological chain, which leads to maximal process. In chapter, primary attention is paid second method relation processes production, processing, transportation, storage metallic nanopowders. To make safe further processing products, powders passivated. passivation means creation protective thin oxide film surface nanoparticles, prevents self-ignition have been no reliable, scientifically grounded until now. takes tens hours, restrictive factor get increase output However, theoretical models explaining ignition ultra-disperse at room temperature not still developed. These should allow both revealing main parameters influencing critical conditions optimizing process Application developed for description metal particles, take into account interaction particles oxidizer as well diffusion reagents through product layer generally unacceptable. According these models, temperatures close ones impossible low diffusivities. Therefore, development theory pyrophoric behavior considering coalescence nanoparticles role sample much urgent.