| Aluminum as the important part of composite propellant, whose thermal propertiescan determine the thermal properties of composite propellant. Large particle Al powderhas limited its application due the slow combustion rate, incomplete combustion, smallheat release and so on. Superfine Al powder has a better combustion rate and relativelylarge heat release compared with large particle Al powder. So, the study of superfine Alpowder will be the main direction in Al additive. But because of the large surface activity,the surface of Al can be easily oxidized to form oxidized layer and reduce the combustionproperties of Al powder, the surface modification of superfine Al will be our point. Wehave coated a layer of Fe on Al powder by MOCVD in fluidized bed reactor. Theoxidization degree can be reduced and the thermal properties of Al can be improved.Using Fe(CO)5as precursor, the surface of Al can be coated by a layer of nano Fe byMOCVD in fluidized bed reactor. Three different sizes of Al (diameter:29μm,13μm,2μm)have been coated. SEM and ESEM have been employed to analyze the surface ofcomposite powder. We find that a uniform and compact Fe layer has been coated on Al.Through the research of the thermal properties of composite powder, we find that thecombustion properties have increased by60%after coating and the total weight gainincreases from20%(before coating) to about80%after the coating process.We have also changed the Fe layer thickness by using different deposition time(30min,1h,1.5h). The combustion properties of composite powder with differentthicknesses of Fe layer have been studied and we conclude that there exists the optimumthickness which has the best combustion properties. |
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