Solid propellants comprised of aluminum and water show high theoretical energetic performance and are considered environmentally friendly, since the burning products contain non-toxic and carbon-free materials (aluminum oxide – Al2O3, and hydrogen gas – H2). These propellants may be attractive for different types of propulsion systems (for example: in-space, under-water), and could also be used in other applications, such as hydrogen production, power generation etc. Thermochemical analysis shows that stoichiometric combustion of aluminum-water propellant can yield high performance parameters that exceed those of the highly toxic hydrazine at similar conditions, and are on par with commonly used solid propellants (AP/HTPB, NG/NC and others).
In the present research, solid propellants containing distilled water and different nano‑aluminum powders were filled into consumable strands, and ignited inside a pressure chamber for burning rate measurements at pressures up to 70 bar. Three types of nano aluminum powders were tested: ALEX – uncoated particles; V‑ALEX – Viton coated particles; and L‑ALEX – stearic acid coated particles. All tested compositions presented burning rates similar to those of conventional solid propellants, and the obtained pressure exponents suggest that the combustion of aluminum-water solid propellants will be stable during pressure fluctuations. In addition to burning rate experiments, selected compositions were tested inside a small rocket motor where the operating pressure and the developed thrust were measured, to receive the key performance parameters of the propellant.
The entire process of the research will be covered in the presentation: starting from the powder analysis using TEM/TGA techniques; followed by the preparation process of the different propellant mixtures; description of the experimental setup constructed for the burning rate measurements and the static firing experiments; and the results obtained including the performance parameters for the different propellant compositions.