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Preparation and Thermal Characterization of Fe/Al_p Composite Powders

Author: ChenZhiAn
Tutor: TangShaoYan
School: Hunan University
Course: Materials Processing Engineering
Keywords: core-shell structure Fe/Al composites fluidized bed chemical vapor deposition exothermic reaction
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Type: Master's thesis
Year: 2013
Downloads: 32
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Abstract


In order to solve the micro aluminum combustion issues of lowreaction kinetics, incomplete combustion and the nano aluminum issuesof agglomeration, low effective aluminum content, high activity evenleading to auto-ignition, in this paper, Core-shell structure Fe/Alcomposites were successfully prepared by fluidized bed chemical vapordeposition (FB-CVD) with different particle size of micro/nanoaluminums in Ar atmosphere.In this work, Aluminum powders of three different particle sizenamed Q1(average particle size is29μm),Q3(average particle size is13μm), Q5(average particle size is2μm) have been successfully coated byfluidized bed chemical vapor deposition iron with iron carbonyl(Fe(CO)5) as precursor and Ar as Carrier gas，the amount of iron coatedwas controlled by the injection volume of the carbonyl iron. In order toimprovement the fluidization properties of sticky particle Q3and Q5,motor stirrer were added in the fluidized bed reactor. The characterizationof the as-prepared composites was carried out using SEM, XRD, andsimultaneous TG-DSC. It was found that the aluminum core was coatedcompactly and uniformly by an iron layer, the amount of iron coatedincreases with the increase of the injection volume of the carbonyl iron.Although the coating of iron reduce the content of effective aluminum,exothermic reaction of the obtained composite powders showed asignificant improvement compared to pure aluminum powders, heatrelease is obviously improved, Exothermic process is more quickly andconcentrated. Q3and Q5was completely oxidized before1400℃and1200℃, respectively. The exothermic performance influences of thedifferent amount of iron coated on different particle size micro aluminumwere different, and the reasons for this phenomenon also showed in thisthesis.In the nano part, nano-Al named L1(150nm) as base material,processed by fluidized bed chemical vapor deposition for coating，in order to improve the fluidization performance of nano-aluminum powder,rotation mode was changed and nano-Al and Q1mixed fluidization alsowas used. The characterization of the as-prepared composites was carriedout using TEM, XRD, and simultaneous TG-DSC. The iron coated on thenano-Al effectively improved exothermic performance of nano-Al.

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