Several aluminum nanopowders were examined and compared with the final goal to evaluate their application in solid rocket propulsion. A detailed investigation of pre-burning properties by the Brunauer-Emmet-Teller method, electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy was carried out. Ballistic properties and the combustion mechanism of several aluminized propellant formulations were investigated. In particular, aggregation and agglomeration of metal particles at and near the burning surface were analyzed by high-speed high-resolution color digital video recordings. All tested nano-powders are of Russian production; their physical characterization was carried out at the Istituto Donegani (Novara, Italy); ballistic studies were performed at the Solid Propulsion Laboratory (Milano, Italy) using laboratory and, for comparison, industrial composite propellants based on ammonium perchlorate as an oxidizer. Results obtained under a fair variety of operating conditions typical of rocket propulsion indicate, for increasing nano-Al mass fraction or decreasing nano-Al size, larger steady burning rates with essentially the same pressure sensitivity. While aggregation and agglomeration phenomena still occur, their significance may be reduced by using nano-Al instead of micro-Al.

Fine and ultra‐fine powders are actively studied in pyrotechnics, explosives and propellants. The important questions are how to produce a powder with specified characteristics and how to use the powder produced.

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The data produced shed new light on particle formation under fast Joule heating: the particle size depends on the initial size of the crystallites of a metal. The size of crystallites has been determined by the x-ray diffraction method as the size of the region of coherent scattering d(RCS). Median-surface particle sizes d(S) of the powder have been evaluated from the specific surface area S (BET). Such different metals as Al, In, Cu, Ti have been investigated. For the given metals, d(RCS) varies from 25 to 77 nm, d(S) of the powder varies from 45 to 200 nm, and d(S) is the smaller, the smaller is d(RCS). On this evidence, from the beginning of heating, the power of Joule dissipation is higher at the boundaries of crystallites. As a result, even at the energy introduced in the wire equal to the sublimation energy, 'a gas of drops' is formed instead of 'a gas of atoms'.