| Aluminum as a good flammable agent has high combustion energies and is widelyused as a fuel additive in propellants, explosives and pyrotechnic formulations. However,due to the slow reaction kinetics, long ignition delays and incomplete combustion issues,the potential high calorific value of micron Al powder can not be fully used. In addition,due to the high activity of nanometer Al powder, the surface of nano-Al can be easilyoxidized into alumina, lowering the content of “effective aluminum”. In this paper,chemical liquid deposition and chemical vapor deposition have been used in the surfacecoating of the two kinds of aluminum powder to improve the combustion efficiency.Through chemical liquid deposition, a kind of core-shell Fe/μAl composites has beensuccessfully prepared with iron carbonyl (Fe(CO)5) as precursor and kerosine as oil phasemedium. The research indicates that the Fe/μAl composite powder produced through themethod show a significant improvement in the oxidation kinetics compared to pure micronAl powders, heat can be released in a faster and more concentrated way after coating inthe same temperature, the whole combustion process is greatly improved. On the basis ofthe results, a possible formation of the coating is proposed and the thermal reactionmechanism is also discussed. Besides, using nanometer Al powder as matrix, the Fe-nAlintermetallic compound can be prepared through the same method, which can improve thestability of nanometer Al powder.Through chemical vapor deposition, using Fe(CO)5as precursor and micron Al asmatrix, Fe/Al composite powder with uniform and compact coating layer has beenfabricated in the fluid bed of our own design. We also have remade the fluid bed of ourown design and coated the nanometer Al with Fe decomposed from Fe(CO)5. The researchindicates that nano-Fe densely wrapped on the surface of nano-Al. |
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