%0 Journal Article %A Trubert, Jean-Francois %A Lambert, Dominique %A Orlandi, Olivier %D 2007 %I Begell House %N 5 %P 529-550 %R 10.1615/IntJEnergeticMaterialsChemProp.v6.i5.10 %T SIZE EFFECT OF ALUMINUM NANO-PARTICLES ON HTPB/AP PROPELLANT COMBUSTION %U https://www.dl.begellhouse.com/journals/17bbb47e377ce023,6b745dc027a9ade2,23a4766714b734bc.html %V 6 %X For a few years, nano-aluminum was supposed to bring about better combustion and ballistic properties to propellants. The actual published results seem a little disappointing. For the purpose of evaluating the properties of such particles, experiments were conducted to complete existing information from literature review.
A specific nano-aluminum powder has been selected because of its well-adapted chemical properties. A HTPB/AP/Al propellant has been processed by traditional techniques and tests were performed to ensure the good dispersion of the nano-Al.
By means of quenching and particle collection, it is observed that agglomeration phenomena takes place at the propellant combustion surface, limiting the initially expected effect of nano-aluminum. Interpretation of the particles' size and X-ray identification analyses are compared to the agglomeration prediction model (typically called 'pocket model') to verify whether this approach can be used in the nanometric domain or not. ONERA application of the Cohen-Beckstead's pocket model leads to a better agreement between experimental and predicted agglomeration globules. It appears that a few remaining overestimated cases, not foreseen by the model, can be attributed to rapid combustion of the finest Al particles.
Visualization experiments show the evolution of the combustion zone of the composite propellant versus the aluminum particles' sizes. As expected, the first visualization results outline the aluminum combustion zone coming closer to the propellant combustion surface. This distance is correlated with the aluminum particle diameter. The Al combustion model proposed by Widener-Beckstead provided a good validation on a wide micrometric size range and in various experimental conditions. New combustion time measurements, extracted from ONERA visualization tests of very fine, yet visible, particles, allow validation of the model down to the particle size limit of 3−5 μm. %8 2007-09-01