Research On The Oxidation Properties Of Al-Mg And Al-Mg-Li Alloy Fuels

Metal-based, binary, mechanically alloyed and nanocomposite materials offer advantageous performance as fuel additives in energetic formulations for propellants, explosives, and pyrotechnics. In this paper, Al-Mg-Li and Al-Mg alloy powders were prepared using a close-coupled gas atomization instrument. The exothermic process of Al-Mg/H2 O reaction systems and the oxidation property of Al-Mg-Li alloys were studied.The computer system was employed to monitor the reaction processes of Al0.5Mg0.5/H2 O systems and the T-t curves of the Al0.5Mg0.5/H2 O reaction systems were analyzed. Three characteristic temperature points(including the initial reaction temperature, the reaction maximum rate temperature, and the temperature of the reaction end) and three reaction characteristics(including the initial reaction temperature, the reaction heat releasing rate, and the reaction heat release) were extracted and defined. An evaluation system of Al0.5Mg0.5/H2 O reactions based on these was established to study the properties of the systems. The effects of particle size, storage conditions of the Al-Mg powders, heating power, mole ratio of Al0.5Mg0.5/H2 O and solution PH on the reactions were investigated according to the established evaluation standard. The results showed that the Al0.5Mg0.5 alloy powder could react completely with H2 O, indicating the addition of Mg could improve the reactivity of Al powder, which is of great significance in improving the traditional Al/H2 O system performance and provides data support for the future application of metal powder/water reaction fuel.The excellent oxidation performance of Al-Mg/H2 O system showed a great significance in improving the application of Al/H2 O system. To further improve the oxidation property of Al-Mg alloy, Li has been added into the Al-Mg alloy and the oxidation property of Al-Mg-Li alloys is studied.Oxidation behaviors of atomized Al-Mg-Li alloys with compositions ranging from Al0.85Mg0.1Li0.05 to Al0.55Mg0.4Li0.05(wt.%) were examined by Thermogravimetry/Differential Thermal Analysis(TG/DTA). For alloys with magnesium content from 10% to 30%, the temperature of the first oxidation peak is 417-480 °C and the second exothermic peak occurred over a wide range of temperature(989-1098 °C). The temperature of the second peak decreased slightly with increasing magnesium content. For Al0.55Mg0.4Li0.05 alloy, the first exothermic peak occurred at 458 °C while the second exothermic peak occurred at 540 °C, and no exothermic peak was observed at higher temperature. During the oxidation of the alloys, lithium and magnesium were oxidized preferentially and removed from the metallic phase. The porous structure formed during the selective oxidation promotes the oxidation of residual Al in the alloy. Al0.55Mg0.4Li0.05 was oxidized completely at 1100 °C, lower than the temperature of the other alloys. The thermite reaction experiment of Al0.55Mg0.4Li0.05-Fe2O3 system conducted in Ar showed a reaction temperature of 587 °C, significantly lower than the reaction temperature observed for Al-Fe2O3 system.