树枝状纳米钴微晶对高氯酸铵热分解的影响

采用化学还原法制备了纳米钴微晶,并对产物进行了XRD、SEM、TEM和EDAX表征,结果表明,纳米钴微晶呈树枝状、结晶度高、颗粒尺寸均匀;运用DTA分析研究了纳米钴微晶对AP分解的催化性能,结果显示AP的高低温放热峰相连且合并成一个高而大的放热峰,峰温最大幅度降低了180℃,表观分解热显著增大.表明纳米钴微晶对AP热分解有着极强的催化活性.     

负载型纳米NiO催化高氯酸铵热分解的DSC/TG-MS研究

采用浸渍法制备出纳米NiO/MgO,运用X射线衍射(XRD)、透射电子显微镜(TEM),X射线能谱仪(EDS)等对产物的物相和组成进行了表征,利用DSC/TGMS研究了纳米NiO/MgO对高氯酸按(AP)热分解的催化作用.结果表明,在纳米NiO/Mgo的催化作用下,AP的热分解高温分解峰温度降低92.2℃,表观分解热增...     

Cu/Fe hydrotalcite derived mixed oxides as new catalyst for thermal decomposition of ammonium perchlorate

Cu/Fe mixed oxides (Cu/Fe-MOs) were prepared by calcination of Cu/Fe hydrotalcite (Cu/Fe-HT) precursors. They were used as new catalyst for thermal decomposition of ammonium perchlorate (AP) and their catalytic activity was studied by thermal gravimetric and differential thermal analysis. With the addition of 4 wt.% Cu/Fe-MOs, thermal decomposition of AP was accelerated by 104 °C. Higher catalyst addition favors further decomposition of AP. The catalytic activity order is: Cu/Fe-MOs-500 > Cu/Fe-MOs-800 > CuO·Fe₂O₃. The proposed catalytic mechanism is the presence of O₂⁻ on the surface of Cu/Fe-MOs which can simplify thermal decomposition of AP.     

Preparation,characterization and catalytic behavior of copper oxide nanoparticles on thermal decomposition of ammonium perchlorate particles

In this study, copper oxide nanoparticles (CuO NPs) with mean particle size of 43–32?nm were prepared by wet grinding of commercial micronized CuO powders in a high-energy wet ball-milling apparatus during 20 and 30?h, respectively. X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) analyses were used to characterize the structure, mean particle size and morphology of the resulting CuO NPs. The results confirmed that the CuO NPs obtained at different milling times consist of nanostructures with nearly spherical morphology and by increasing the milling time, smaller particle size was obtained. The catalytic activities of the synthesized CuO NPs on the thermal decomposition of ammonium perchlorate (AP) particles were examined through differential scanning calorimetry and thermogravimetry (DSC/TG) analyses. Evaluation of the experimental results illustrated that the surfaces of CuO NPs were effectively coated with AP particles and by adding 5%CuO NPs with 32?nm, the thermal decomposition temperature of the treated particles reduced by 83.0°C and the heat of decomposition reached 1553.7?Jg^?1. Moreover, the kinetic and thermodynamic parameters of the thermal decomposition of pure and AP?+?5%CW30 nanocomposites have been investigated by using the Kissinger, Boswell and Ozawa methods.     

Copper loaded carbon aerogel from chitosan-precursor promotes thermal decomposition of ammonium perchlorate for solid propellants

Chitosan (CS) was used as a carrier, in which copper particles were loaded, and CS-Cu carbon aerogel was obtained by freeze-drying and high-temperature carbonization, which was characterized by scanning electron microscopy test, Fourier transform infrared spectroscopy test, X-ray diffraction test, X-ray photoelectron spectroscopy, and gas adsorption method. Results show that CS-Cu carbon aerogel is a 3D porous material, and its 3D porous structure provides more active sites for the copper nanoparticles, effectively preventing the agglomeration phenomenon caused by the large surface energy of copper nanoparticles. The CS-Cu carbon aerogel was introduced into the solid propellant system, and the catalytic performance of the CS-Cu carbon aerogel on ammonium perchlorate (AP) was investigated by differential thermal analysis. The results show that the CS-Cu carbon aerogel has good catalytic performance, the high temperature decomposition peak of AP is reduced by 92.4 K and the activation energy is reduced from 215.9 ± 1.3 kJ/mol to 173.7 ± 1.5 kJ/mol for pure AP.     

纳米NiFe2O4的制备及其对高氯酸铵的热分解催化性能

采用水热法制备出纯相的NiFe2O4纳米颗粒。利用X射线衍射仪(XRD),透射电镜(TEM)和傅里叶变换红外光谱仪(FT-IR)对样品进行了表征,并运用热分析法和质谱仪研究了样品对高氯酸铵的热分解催化性能。结果表明,制备的NiFe2O4纳米颗粒粒径约为5.0nm,对高氯酸铵的热分解具有很高的催化活性。当NiFe2O4纳米颗粒的添加量达到10%时,对高氯酸铵的热分解催化性能最好,可使高氯酸铵的高温分解温度降低89.8℃。     

Transition metal oxide nanoparticles: Potential nano-modifier for rocket propellants

ABSTRACT

TiO₂, ZnO₂, and CrO₂ nanoparticles were prepared by novel quick precipitation method, where transition metal oxides were used as catalyst. All nanoparticles were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The average particle size for TiO₂, ZnO₂, and CrO₂ was 44.8, 13.4, and 77.6 nm, respectively. Catalytic properties of these nanomaterials were studied using ammonium perchlorate (AP)/hydroxy-terminated polybutadiene (HTPB) propellant by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Both experimental results reveal that there is an increase in the thermal decomposition of propellants in the presence of transition metal oxide nanoparticles. Activation energy of high-temperature decomposition (HTD) of propellant with transition metal oxide nanoparticles was calculated by Kissinger equation. Burning rates of propellants were also calculated.     

热解一维链状铜络合物单晶制备纳米氧化铜

采用Cu(NO3)2、吡啶与5-磺基水杨酸反应制得了具有一维链状结构的铜络合物单晶{[Cu(HSSA)(py)3]·H2O}n(H3SSA=5-磺基水杨酸,py=吡啶).采用X-射线衍射(XRD)、热重(TG)分析和透射电子显微镜(TEM)等手段表征了其在900℃下焙烧后的产物.X-射线衍射的结果表明焙烧后的产物是氧化铜.TG分析结果表明,该络合物的起始分解温度为80℃.TEM表征结果表明,氧化铜纳米颗粒的直径在50 mm～200 nm之间.该热解铜络合物制备纳米氧化铜的方法具有产率高、无毒、无害、廉价等优点.     

Isothermal thermal diffusivity of iron oxide

Using the flash technique, the thermal diffusivity of iron oxide has been measured as a function of time at temperatures ranging from 623 to 753 K to study the isothermal decomposition of wustite to magnetite and iron. The results are briefly discussed in terms of transformation kinetics and it is shown that the data are consistent with the growth of a fixed number of nuclei, all of which are present at the start of transformation.     

纳米钴酸铜的制备以及对高氯酸铵的催化性能

采用盐助溶液燃烧法,以硝酸铜和硝酸钴为原料,尿素为燃烧剂,KCl为反应惰性盐制备尖晶石型纳米钴酸铜。采用XRD、FT-IR、Raman和TEM等测试手段对产物进行了表征。结果表明,制得的纳米粒子具有较完美的晶体结构,分散性较好,粒径约为50nm。利用热分析法考察了纳米钴酸铜对高氯酸铵热分解的催化作用。结果显示纳米钴酸铜具有较高的催化活性,添加2%的纳米钴酸铜热分解温度降低136℃,催化效果优于单一组分的纳米金属氧化物。     

聚丙烯的热分解与超临界水分解对比实验研究

为了寻求一种更为有效的聚合物分解回收方法，采用热分解和超临界水分解方式对聚丙烯(PP)的分解行为和分解产物进行了对比实验研究，并利用红外光谱、热分析仪等分析手段对反应残留物进行分析，用气相色谱和质谱对液相成分进行表征．结果表明：在反应温度为420℃的条件下，PP经热分解全部转化成液体油状物，而超临界水分解只有63％的分解率，反应较热分解进程缓慢；超临界水分解时，压力越高，PP分解率越低；压力的存在对于某些小分子分解产物的生成有一定的抑制作用。     

Preparation and characterization of rice-shaped MnO2/CNTs composite and superior catalytic activity on thermal decomposition of ammonium perchlorate

Manganese dioxides (MnO₂) were successfully deposited on carbon nanotubes (CNTs) surface by redox reaction between potassium permanganate and CNTs. The characterization results showed that the MnO₂ exhibited the rice-shaped nanostructure with about 5～10 nm in width and 10～30 nm in the length on CNTs. The solvothermal temperature of composite can greatly affected its morphology and structure to improve the thermal catalytic on ammonium perchlorate (AP) decomposition. Compared with other samples, the prepared composite at 120°C exhibited superior catalytic performance, as 3wt% of composite added in AP, the second exothermic peak temperature decreased by 160.2°C and the apparent release heat of the thermal decomposition of AP which is four times of that of pure AP. A possible mechanism for formation the rice shaped MnO₂/CNTs composite is also presented.     

Aloe vera vs. poly(ethylene)glycol-based synthesis and relative catalytic activity investigations of ZnO nanorods in thermal decomposition of potassium perchlorate

The green synthesis approach using ecofriendly biological precursors has gained world-wide popularity, reputation and recognition in the synthesis of several inorganic nanomaterials. This work demonstrates that a proper selection of biological precursor from the sustainable natural resources can effectively replace the commercial surfactant for fabrication of nanomaterials. Through this work, the green biotemplate Aloe vera plant extract has emerged as a better substitute of industrial surfactant poly(ethylene)glycol of molecular weight 8000 (PEG8000) in synthesis of ZnO nanorods using a simple sonoemulsion route. The colloidal growth of ZnO nanorods in PEG8000/Aloe vera -assisted sonoemulsion route has been elaborated in the context of relative supremacy of ultrasonic-assisted self-aggregation rate with steric-hindrance effect imposed by PEG8000/Aloe vera . The relative catalytic activity of PEG8000/Aloe vera synthesized ZnO nanorods, Co₃O₄ nanobelts and CuO nanorods in thermal decomposition of potassium perchlorate has been studied by thermo-gravimetric analysis and differential thermal analysis of pure potassium perchlorate and its mixture with nanoscale ZnO/Co3O4/CuO by 2% weight. The ZnO nanorods formulated through Aloe vera route demonstrated higher catalytic activity than that of ZnO nanorods prepared through PEG8000 route. The relative order of catalytic effect of nanoscale metal oxides in thermal decomposition of potassium perchlorate was found in descending order as CuO nanorods > Co₃O₄ nanobelts > ZnO nanorods.     

Oriented Assembled Prussian Blue Analogue Framework for Confined Catalytic Decomposition of Ammonium Perchlorate

The design of highly dispersed active sites of hollow materials and unique contact behavior with the components to be catalyzed provide infinite possibilities for exploring the limits of catalyst capacity. In this study, the synthesis strategy of highly open 3-dimensional frame structure Prussian blue analogues (CoFe-PBA) was explored through structure self-transformation, which was jointly guided by template mediated epitaxial growth, restricted assembly and directional assembly. Additionally, good application prospect of CoFe-PBA as combustion catalyst was discussed. The results show that unexpected thermal decomposition behavior can be achieved by limiting AP(ammonium perchlorate) to the framework of CoFe-PBA. The high temperature decomposition stage of AP can be advanced to 283.6 °C and the weight loss rate can reach 390.03% min⁻¹. In-situ monitoring shows that CoFe-PBA can accelerate the formation of NO and NO₂. The calculation of reaction kinetics proved that catalytic process was realized by increasing the nucleation factor. On this basis, the catalytic mechanism of CoFe-PBA on the thermal decomposition of AP was discussed, and the possible interaction process between AP and CoFe-PBA during heating was proposed. At the same time, another interesting functional behavior to prevent AP from caking was discussed.     

Effect of crystallization parameters and presence of surfactant on ammonium perchlorate crystal characteristics

ABSTRACT

Ammonium perchlorate is an exceptional oxidizer in composite solid rocket propellant formulations. Crystallization is the most critical step in the manufacture of ammonium perchlorate, which determines the size, shape, morphological characteristics, crystal strength, grinding characteristics, and thermal characteristics of the crystals. Attempts are made in the present study to establish the effect of crystallization parameters such as cooling patterns, agitator rpm, retention of crystals in the mother liquor, and presence of surfactant, on the morphological, thermal, and physical characteristics of ammonium perchlorate crystals. Based on the trials conducted in a 5-L capacity laboratory glass crystallizer, it is found that spherical, transparent, and smooth-surface crystals are obtained by crystallization having a slow cooling pattern and an agitator rpm of 600. Irregular-shaped crystals are obtained under fast cooling pattern and/or lower agitator rpm. It is also seen from XRD patterns that ammonium perchlorate crystals made in the present study do not have any amorphous phase on the surface. Porous nature of the crystals made in the presence of surfactant was verified by scanning electron microscopy images, bulk density, transparency of crystals, and change in the low temperature decomposition pattern in Differential Scanning Calorimeter (DSC) curves.     

Synthesis,characterisation and catalytic activity of cadmium cobaltite nanoparticles: part 87

In this paper, we report the synthesis of cadmium cobaltite nanoparticles (CCNs) and their characterisation by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The particles are spherical in shape and the average particle size is of the order of 20–30 nm. Its catalytic activity was investigated through the thermal decomposition of ammonium perchlorate (AP), composite solid propellants (CSPs), 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) using thermogravimetry (TG), TG coupled with differential scanning calorimetry (TG-DSC) and ignition delay measurements. The kinetics of thermal decomposition of AP + CCNs has also been investigated using isoconversional and model-fitting approaches, which have been applied to data for isothermal TG decomposition. The burning rate of CSPs was considerably enhanced by these nanoparticles. The ignition delays and activation energies are found to decrease when CCNs were incorporated in the system. The addition of CCNs to AP led to a shifting of the high-temperature decomposition peak towards lower temperature. All these studies show enhancement in the rate of decomposition of AP, NTO, HMX and CSPs.     

A novel approach for the biosynthesis of silver oxide nanoparticles using aqueous leaf extract of Callistemon lanceolatus (Myrtaceae) and their therapeutic potential

This study describes a novel biological route for the biosynthesis of silver oxide nanoparticles utilising the aqueous extract of Callistemon lanceolatus D.C. leaves. Formation of silver oxide nanoparticles was confirmed by UV–visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope–energy dispersive X-ray spectroscopy and X-ray diffraction spectroscopy analysis. The biologically synthesised silver oxide nanoparticles were found to be 3–30 nm in size with spherical and hexagonal shape by high-resolution transmission electron microscope analysis. Furthermore, the biogenic silver oxide nanoparticles demonstrated significant (p?in vitro antioxidant methods. These particles also exhibited significant (p?相似文献   

从废铅膏制备超细碳酸铅的表征及热分解性能研究

利用废铅膏为原料,采用脱硫、浸出、碳化的湿法工艺制备了超细碳酸铅。碳酸铅为斜方晶体,粒径在0.5～5μm。采用TG-DSC、XRD、SEM对碳酸铅的热分解机理进行研究,结果表明碳酸铅的失重与理论计算相符,整个热处理过程分4个阶段,产物分别是PbCO3.2PbO、α-PbO、Pb3O4和β-PbO。产物PbO为均匀的球形,粒径<0.5μm。     

膨化高氯酸铵的制备及其性能研究

使用膨化剂在减压条件下制备出膨化高氯酸铵（AP）。利用扫描电镜、粒度分析仪、傅里叶红外光谱仪、比表面积仪、差示扫描量热仪、热失重分析仪及感度仪分别对膨化AP进行形貌分析和性能测试。结果表明:膨化AP颗粒表面具有沟壑,内部具有孔洞结构,粒径D₅₀=22.559 μm;与未膨化的原料AP相比,膨化AP低温分解温度提高16.0 ℃,高温分解温度提高6.7 ℃,分解热提高322.3 J/g;比表面积增大92.2%,吸湿性增大;极限撞击能为10 J,撞击感度提高。制备AP/HTPB(端羟基聚丁二烯)和膨化AP/HTPB复合推进剂并测定其燃速,膨化AP/HTPB复合推进剂燃速提高4.1%。