Controlled Preparation And Catalytic Properties Of Copper-based Nano Combustion Catalysts

In this dissertation,a series of copper-based nano combustion catalysts were controlly prepared,including unary copper-based nano combustion catalysts(nano CuO and nano?-Cu(Copper ?-resorcylate)),binary copper-based nano combustion catalysts(nano CuCr2O4 and nano Cu-Cr composite metal oxides(CuO/Cr2O3)),and ternary copper-based nano combustion catalysts(nano Cu-Cr-Fe composite metal oxides(CuO/Cr2O3/Fe2O3)and nano Cu-Cr-Pb composite metal oxides(CuO/Cr2O3/PbO)).The catalytic effects of copper-based nano combustion catalysts on the AP(ammonium perchlorate),AP/HTPB(hydroxyl-terminated polybutadiene)composite propellants and AP-CMDB(composite modified double base)propellants were investigated.The details were as follows:Firstly,basing on the principle of 'tiny force being exactly given to materials' driven by a HLG-5 type nanometer grinder which designed by National Special Superfine Powder Engineering Research Center of Nanjing University of Science and Technology,and the principle of 'expansion and separation' for anti-agglomeration arising from 'expansion by inner force' and 'expansion by outer force' of vacuum freeze drying process when selecting an appropriate dispersing agent,a series of copper-based nano combustion catalysts were controlly prepared with uniform particle size distribution good dispersion,including unary copper-based nano combustion catalysts(nano CuO:15 nm and nano ?-Cu:100 nm),binary copper-based nano combustion catalysts(nano CuCr2O4:30 nm and nano Cu-Cr composite metal oxides:10?20 nm),and ternary copper-based nano combustion catalysts(nano Cu-Cr-Fe composite metal oxides:30 nm and nano Cu-Cr-Pb composite metal oxides:30 nm).Secondly,the effects of different factors(particle size,preparation method/drying method/composite method and content)of nano combustion catalysts on the thermal decomposition performance of AP and the innuences of nano combustion catalysts on the thermal decomposition properties of AP with different particle size were studied.For unary copper-based nano combustion catalysts,nano CuO prepared by mechanical grinding method has better catalytic effect for AP as compared to raw CuO and nano CuO prepared by coprecipitation method,and nano ?-Cu prepared by vacuum freeze drying method is better than raw ?-Cu and nano ?-Cu prepared by vacuum drying method in accelerating the thermal decomposition of AP.For binary copper-based nano combustion catalysts,nano CuCr2O4 prepared by mechanical grinding method has better catalytic effect for AP as compared to raw CuCr2O4 and nano CuCr2O4 prepared by coprecipitation method,and when the molar ratio of CuO to Cr2O3 is 1:0.25,nano Cu-Cr composite metal oxides prepared by mechanical grinding method show better catalytic activity for AP than those with other molar ratios of CuO to Cr2O3(1:2,1:1 and 1:0.5).Nano Cu-Cr composite metal oxides reflect the synergistic effect between different metal oxides,and the catalytic effect on the thermal decomposition of AP is better than that of single nanocatalyst and nano composite catalyst by simple mixing.For ternary copper-based nano combustion catalysts,when the molar ratio of Cu/Cr/Fe is 5:2:8,nano Cu-Cr-Fe composite metal oxides prepared by mechanical grinding method show better catalytic activity for AP than those with other molar ratios of Cu/Cr/Fe(5:4:6,5:6:4 and 5:8:2).Nano Cu-Cr-Fe composite metal oxides prepared by mechanical grinding method reflect the synergistic effect between different metal oxides,and the catalytic effect on the thermal decomposition of AP is not less than that of nano CuO,and better than that of single nanocatalyst and nano composite catalyst prepared by coprecipitation method and simple mixing.Similarly,when the molar ratio of Cu/Cr/Pb is 5:8:2,nano Cu-Cr-Pb composite metal oxides prepared by mechanical grinding method show better catalytic activity for AP than those with other molar ratios of Cu/Cr/Pb(5:2:8,5:4:6 and 5:6:4).Nano Cu-Cr-Pb composite metal oxides prepared by mechanical grinding method reflect the synergistic effect between different metal oxides,and the catalytic effect on the thermal decomposition of AP is not less than that of nano CuO,and better than that of single nanocatalyst and nano composite catalyst prepared by coprecipitation method and simple mixing.In addition,the copper-based nano combustion catalysts with the content of?2%exhibit much better effect on the thermal decomposition of AP.With the decrease of particle size of AP,ultrafine AP has a strong tendency for aggregation and it is difficult to form a homogeneous mixture between ultrafine AP and nano combustion catalysts.In this case,it is necessary to improve the mixing uniformity of nano combustion catalysts and ultrafine AP to enlarge the catalytic performance of nano combustion catalysts.Lastly,the applications nano CuO,nano CuCr2O4 and nano Cu-Cr-Fe=5:2:8 prepared by mechanical grinding method in AP/HTPB composite propellants and AP-CMDB propellants were researched.The AP/HTPB composite propellants containing nano combustion catalysts have good moldability and almost no defects with a density of about 1.7 g/cm3,and The AP-CMDB propellants containing nano combustion catalysts have good moldability and very few defects with a density of about 1.6 g/cm3.With the addition of nano CuO,nano CuCr2O4 and nano Cu-Cr-Fe=5:2:8 prepared by mechanical grinding method,the thermal decomposition and combustion performance of AP/HTPB composite propellants and AP-CMDB propellants are increased as compared to the addition of raw CuO,raw CuCr2O4 and nano Cu-Cr-Fe=5:2:8 prepared by coprecipitation method,respectively.The order of catalytic activity of nano combustion catalysts on the thermal decomposition and combustion performance of AP/HTPB composite propellants and AP-CMDB propellants is nano Cu-Cr-Fe=5:2:8>nano CuCr2O4>nano CuO,which indicates multiple catalyst emerge the synergistic effect between different metal oxides.The controlled preparation of copper-based nano combustion catalysts would be very helpful to promote the application process of nano combustion catalysts in AP based propellants and improve the combustion performance of the propellants.