Nano The Abo <sub> 3 </ Sub>-type Rare Earth Oxides In The Preparation And Its Catalytic Performance

In this paper, solution combustion synthesis of nano-sized perovskite LaMnO₃ andNdCoO₃ as well as their catalytic effects on thermal decomposition of ammoniumparchlorate (AP) were investigated firstly. Then large scale synthesis of nano-sizedperovskite NdCoO₃ via a salt-assisted mechanochemical process and their effects onthermal decomposition of AP, thermal decomposition, combustion performace and safetyproperty of composite solid propellants were explored.In Chapter 2, perovskite LaMnO₃ powders with an average crystallite size of 12.5nm were rapidly synthesized via a microwave-induced auto-combustion reaction usingglycine as a fuel and nitrate as an oxidant. Then the solution combustion synthesis ofNdCoO₃ nanopowders using glycine as a fuel was studied. The results show that theas-combusted products are still amorphous after calcination at 500℃and have severeagglomeration and that the addition of NaC1 not only can improve the dispersibility butalso promote the formation of perovskite.In an effort to synthesize nano-sized NdCoO₃ a on a large scale, we investigated thatthe preparation of NdCoO₃ via a mechanochemical reaction using hydrate chloride as araw material. It is shown that the NaC1 derived in-situ during milling and the added NaClcan improve the dispersibility and morphology of the as-synthesized particles owing toinhibiting agglomeration. And an increasing added of NaCl can increase the dispersibilityand the specific surface area of the product, which can also promote the formation ofperovskite and nanocubes in the same time. The preparative method is characterized byavailability in raw materials, convenient operation, simple process, high yield and potentialindustrialization.The nano-sized LaMnO₃ and NdCoO₃ show excellent catalytic efforts on the thethermal decomposition of AR Especially, the amorphous NdCoO₃ prepared via amechanochemical reaction decreases the temperature of the second AP decompositionpeak to 308℃. The addition of the amorphous NdCoO₃ nanoparticles into the AP/HTPBcomposite solid propellant incorporates two exothermic peaks of the composite solidpropellant into one exothermic peak, decreases the temperature of the exothermic peakby 38℃, enhances the burning rate at the pressure of 7MPa by 26.9％and decreases thepressure exponents in the pressure scopes of 5～10MPa by 35％. The tests on safetyproperties reveal that the addition of the amorphous NdCoO₃ nanoparticles into APgreatly decreases shock sensitivity and friction sensitivity of AE In summary, the amorphous nano-sized NdCoO₃ is expected to be an excellent and promising modifier forcombustion of the AP/HTPB composite solid propellant.