Self-assembly Preparation And Catalytic Performance Of Graphene Oxide-supported Magnesium-based Metal Composite Oxides

Solid propellant is the power source of missile and rocket engine,and its combustion is the core of the propulsion technology.The addition of a small dosage of catalysts can significantly improve the combustion performance of propellant.Some nanoscale metal composite oxides have been widely used as combustion catalysts.However,these materials inevitably suffer from the aggregation,thereby weakening their catalytic activities.Due to its large specific surface area and superb mechanical flexibility,graphene oxide?GO?can serve as an ideal catalyst support and the assembled nanocomposites?NCs?can exert incredible catalytic behaviors.In this paper,two magnesium-based metal composite oxides and series of GO-loaded NCs were synthesized,and then studied their catalytic effects on the thermal decomposition of energetic components used in propellant.This thesis mainly consists of these following sections:?1?MgWO₄ and MgFe₂O₄ have been successfully prepared by solvothermal method.The results from SEM revealed it is severe aggregation that is comprised of the sample.The method of solution blending was used for preparing GO-based NCs:Tuning the suspension concentrations of GO and MgWO₄ leads the formation of GO-MgWO₄?1:1?,GO-MgWO₄?1:3?and GO-MgWO₄?1:5?NCs;The adjustment of potential of MgFe₂O₄ and GO generated GO-loaded MgFe₂O₄ and GO-coated MgFe₂O₄ NCs.The SEM results demonstrated the aggregation of nanoparticles is reduced in the presence of GO,further characterized by TEM,Raman,XPS,FT-IR and BET analysis techniques.?2?The catalytic effects of GO-MgWO₄?1:1?,GO-MgWO₄?l:3?and GO-MgWO₄?l:5?with different morphologies on the thermal decomposition of RDX,HMX and AP were studied,and the results indicated that GO,MgWO₄?1:5?show the most efficient catalytic activities.The exothermic peak temperatures of RDX and HMX were decreased by 28.7 and 10.5?,and the apparent activation values of RDX and HMX were reduced by 43.4 and 56.4 kJ mol^-1 with addition of GO-MgWO₄?1:5?,respectively.Moreover,we also studied the role that GO-loaded MgFe₂O₄ and GO-coated MgFe₂O₄ played in the thermal decomposition of AP,and the results revealed that GO-coated MgFe₂O₄ possess superior catalytic activity,which could remarkably reduce the high decomposition peak temperature of AP by 95.05?,and decrease the apparent activation energy of AP by 21.8 kJ mol^-1,enhance the energy release of AP by 876.4 J g-1,respectively.The catalytic effects of GO-based NCs are even better than those of their monocomponents?metal composite oxides or GO?,which may be explained by the "synergetic effect" between them.?3?The thermal decomposition behavior of GO-loaded MgFe₂O₄/RDX and GO-loaded MgFe₂O₄/HMX composites were studied by DSC methods.The thermal decomposition kinetics of GO-loaded MgFe₂O₄/RDX based on the kinetics calculation,was determined for?da?/?dT?=6?1-a?2/3[1-?1 a?1/3]1/2 exp(-?1.6716×10⁵?/?RT??1015.41?/? and the thermal decomposition kinetics of GO-loaded MgFe₂O₄/HMX was determined for:?da/dT?=4(10^14.99)/??1-a?3/4 exp?-1.7505×10⁵?/?RT?.