Characterization of nal powders for rocket propulsion

Abstract

Nanosized metal powders are known to signi¦cantly improve both solid and hybrid rocket performance, but have some drawbacks in terms of cost, safety, and possible in §uence on propellant mechanical properties. Performance enhancement through nanosized metal or metal hydride addition to solid fuels is currently under investigation also for hybrid propulsion. Therefore, a preburning characterization of the powders used in solid propellant or fuel manufacturing is useful to assess their e¨ects on the ballistic properties and engine performance. An investigation concerning the comparative characterization of several aluminum powders having di¨erent particle size, age, and coating is presented. Surface area, morphology, chemical species concentration and characteristics, surface passivation layers, surface and subsurface chemical composition, ignition temperature and ignition delay are investigated. The aim of this characterization is to experimentally assess the e¨ect of the nAl powder properties on ballistic characteristics of solid fuels and solidrocket composite-propellant performance, showing an increase in terms of I s caused by the decrease of two-phase losses in solid and a possible signi¦cant r f increase in hybrid rockets. NOMENCLATURE

Effects of Nano-Sized Al on the Combustion Performance of Fuel Rich Solid Rocket Propellants

“…Burning rates herein are obtained experimentally by burning small propellant strands and measuring the surface regression versus time. Literature on combustion of metal particles indicates that ignition could probably take place via two potential pathways [17][18][19][20][21]. One is the destruction of the metal oxide layer due to cracking, and the other is self-heating due to oxidizer diffusion through the oxide layer, and hence melting of the layer.…”

“…The heat from the gas phase reaction could be increased because more and more UFAl can take part in the gas phase reaction due to its small particle size [12][13][14]. Signifi cant increases in propellant burning rates, shorter ignition delays, and shorter agglomerate burning times were recently obtained for composite solid propellant formulations containing ultra -fi ne energetic particles, particularly nano-Al particles [15][16][17][18]. Chemical composition and grain size distribution strongly affect the physicochemical properties and morphology of the residues.…”

Combustion Characteristics of HTPB-Based Hybrid Rocket Fuels: Using Nickel Oxide as the Polymer Matrix Pyrolysis Catalyst

“…Hybrid rocket propulsion is wisely investigated for its safety, reliability, environment friendliness, and low cost, hence regarded as a promising candidate in suborbital flight, space tourism, and small satellite orbital injection [1][2][3][4][5][6][7]. Resulting from their superior mechanical properties, the hydroxyl-terminated polybutadiene (HTPB)-based fuels are extensively investigated polymer matrix in hybrid rocket propulsion [1,[8][9][10][11].…”