Research On Equipment And Technology Of Organics-Coated Aluminum Nanopowders

Nano-aluminum instead of micron aluminum used in solid rocket propellants canovercome the defects such as long ignition time, agglomerate and incomplete combustion.High activity and large specific surface of nano-aluminum can improve the burning rate,pressure index, and combustion performance. However, highly active nano-aluminummade it easy to react with oxygen, carbon dioxide and steam in the around environmentand result in inactivation. Therefore, coating technology which could keep high activity ofnano-aluminum had significant application prospect in solid rocket propellants. This paperincluded two inspects: first, we designed and manufactured a continuous preparation andcoating equipment which is used to prepare high active organics-coated nano-aluminum;second is the processing and performance characterization of organics-coatednano-aluminum.A2.5L kneading machine with electricity heating was manufactured based on theoutput of a day by hybrid laser-induce complex heating equipment, assembly and highvacuum degree,which was put in a vacuum operation box. Both of them were connectedwith the collecting room after they were assembled.The organic agent we used were hydroxyl-terminated polybutadiene(HTPB) anddioctyl sebacate(DOS) with proportion of21.6%,24.5%,27.3%and29.8%, respectively.The diameter of particles were about50～100nm.The heat release of D5(the proportion is29.8%) and H8(the proportion is21.6%) from TG-DSC were4.955KJ/g and4.954KJ/g,respectively. The possible mechanism of combination between organics andnano-aluminum was also discussed.Permanganatometry is used to determine active aluminum content of organics–coatednano-aluminum. We obtain the active aluminum content of different proportionDOS-coated nano-aluminum were75.6%and74.8%.The active aluminum content ofHTPB-coated and DOS-coated samples and WBF samples were lower than50%. Thethree main factors such as stirring time, the solution decision of potassium permanganateand the decision of titration end point on the results of active aluminum content were also discussed.The activity energy of WBF and H8samples was calculated based on the results ofTG-DTA with heating rate of5℃/min,10℃/min,15℃/min,20℃/min and25℃/min andthe Kissinger method and Ozawa method. The activity energy values of WBF sample were232.4KJ/mol and233.98KJ/mol; while H8sample were253.21KJ/g and253.88KJ/g,respectively. The organics-coated nano-aluminum slightly increased the activity energyand starting combustion temperature. However, it had little effects on the combustioncharacteristics and application of nano-aluminum in solid rocket propellants.