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Plasma synthesized nano-aluminum powders

Structure, thermal properties and combustion behavior

Journal of Thermal Analysis and Calorimetry
Authors: Alla Pivkina, D. Ivanov, Yu. Frolov, Svetlana Mudretsova, Anna Nickolskaya, and J. Schoonman

Abstract  

The plasma electro-condensation process was used to synthesize nano-sized aluminum powders. Adding different chemicals modified the physical and chemical properties of these powders. To characterize the nano-sized powders, X-ray diffraction, TEM, BET analyses, and simultaneous TG/DSC analyses were performed. TG/DSC analyses revealed a dramatic degradation of the aluminum oxide layer after storage of the aluminum powder in air for a period of several months. The burning rate of the model solid propellant with nano-sized aluminum was experimentally examined. The combustion behavior of nano-sized aluminum will be presented and will be compared with the combustion behavior of the micron-sized powders.

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chemicals in authorized atom bomb manufacturing. Some research studies have been carried out in Aluminium powder with coal and the results show that DSC studies on the effect of Aluminium particle size led to multiple exothermic activities and

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Abstract

The dinitramide salts of ammonia (ADN), hexamethylenetetramine (HDN), potassium (KDN), and sodium (NaDN) showed a linear relationship between the DSC rate of decomposition at the peak maximum and the DEA tanδ value at the low temperature transition peak. As the cation basicity increased in the series ADN<HDN<KDN<NaDN, there was an increase in the low temperature transition peak, the energy barrier for relaxation, and the decomposition peak temperature, and a decrease in the tanδ value at the low temperature transition peak, specific heat capacity, and the rate and enthalpy of decomposition. The more basic salts were more thermally stable (i.e., higher decomposition temperature) and less energetic (i.e., lower enthalpy of decomposition). The more internal free volume (disorder) present in these salts, the higher the rates of relaxation and decomposition. Five aluminum powders of different surface areas were analyzed by DSC in platinum sample pans, and it was found that the enthalpy and rate of oxidation increased as the particle size of Al decreased while the enthalpy of the Al melt decreased. TG showed a two-step weight gain in the oxidation of Al with plateaus in the 650 and 1130°C regions and the percent weight gain increased as the particle size of Al decreased. Variable DSC and TG heating rate studies showed that the activation energies for the first step in the oxidation process increased as the particle size of Al increased.

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Abstract  

The thermal properties of Alex, a nanosized Al powder, were determined using various techniques, including DSC, TG, simultaneous TG-DTA (SDT) and accelerating rate calorimetry (ARC). The results demonstrate that the specific heat capacities of nano and micron size Al powders are similar between 30 and 400C. Dynamic and isothermal methods were used to determine the kinetic parameters for the oxidation reaction of Alex, which was detected at an onset temperature of 481C. The results obtained were in good agreement with each other. From the ARC experiments, exotherms were detected near 340 and 260C for experiments started at ambient pressure and at 0.72 MPa, respectively.

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Journal of Thermal Analysis and Calorimetry
Authors: Lin-Quan Liao, Hong-Jian Wei, Ji-Zhen Li, Xue-Zhong Fan, Ya Zheng, Yue-Ping Ji, Xiao-Long Fu, Ya-Jun Zhang, and Fang-Li Liu

-nitrodihydroxyethylaminedinitrate (DINA) and aluminum powder (Al, d 50 = 10.48 μm) as common energetic materials were all industrially produced; 3,4-dinitrofurzanfuroxan (DNTF), 1,3,3-trinitroazetidine (TNAZ), hexanitrohexazaisowurtzitane (CL-20), 4,6-dinitro-5,7-diamino

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Comparative study of HMX and CL-20

Thermal analysis, combustion and interaction with aluminium

Journal of Thermal Analysis and Calorimetry
Authors: O. Ordzhonikidze, A. Pivkina, Yu. Frolov, N. Muravyev, and K. Monogarov

thermal analysis confinement. Burn rate data of neat nitramines show considerable enhancement of CL-20 combustion velocity as compared to HMX. This tendency remains when aluminium powder is added to nitramines, i.e. CL-20-based systems have higher burning

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, consequently, more intense exothermic peak is observed in this region. For this purpose, 5 wt.% of aluminum powder was added to a part of the powder mixture of Mo + 2Si, and this powder mixture was thermally analyzed at different rates (10, 15, and 20 °C

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Abstract  

Thermogravimetry (TG) and differential thermal analysis (DTA) in the non-isothermal mode have been used to examine the thermal behaviour of the micron sized aluminum (Al) powder/potassium chlorate pyrotechnic systems in air, in relation to the behaviour of the individual constituents. The effects of different parameters of Al powder, such as particle size and its content in the mixtures, on their thermal property were investigated. The results showed that, the reactivity of Al powder in air increases as the particle size decreases. Also, it was found that neat Al with 5 m particle sizes (Al5) has a fusion temperature of about 647C, that for 18 m powder (Al18) is 660C. Pure potassium chlorate has a fusion temperature around 356C and decomposes at 472C. DTA curves for Al5/KClO3 (30:70) mixture showed a maximum peak temperature for the ignition of mixture at 485C. Also, by increasing the particle size of Al powder, the ignition temperature of the mixture increased. On the other hand, the oxidation temperature increased by enhancing the Al content of the mixtures. In this particular study, we observed that the width of reaction peak for the mixtures corresponds to their Al contents of samples.

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Abstract  

Heats of explosion of non-ideal RDX-based compositions in four various atmospheres (argon, nitrogen, air and argon/oxygen mixture) were measured. Charges of phlegmatized RDX containing 30% of two types of aluminium powders, coarse aluminium oxide, or fine lithium fluoride particles were fired in a calorimetric bomb of 5.6 dm3 in volume. The influence of inert and reactive additives and the atmosphere filling the bomb on the heat outcome was examined. To estimate the degree of afterburning of the detonation products and reactive particles, thermochemical calculations were also performed for the tested explosive compositions.

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