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Abstract  

Thermal analysis is routinely used to characterize pyrotechnic fuels, oxidants and fuel/oxidant mixtures [1]. Thermomagnetometry (TM) can provide additional information if the magnetic properties of the materials change during reaction. TG, TM and DTA results for the iron/potassium permanganate, iron/barium peroxide, and iron/strontium peroxide systems as loose powders or pressed pellets indicate predominantly solid-gas mechanisms for reactions in these systems.

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Abstract

Studies have been carried out on the boron-potassium perchlorate-nitrocellulose pyrotechnic system by DSC, simultaneous TG-DTA-mass spectrometry and chemical analysis. Quantitative measurements have been made on the exothermic pre-ignition reaction which took place above 360°C and the results have been compared with those obtained previously for the corresponding systems containing zirconium and a zirconium/nickel alloy.

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Abstract  

In order to investigate relative reactivity of different oxidants in solid-state reactions of pyrotechnic mixtures, thermal properties of Sn + Sr(NO3)2, Sn + Ba(NO3)2, and Sn + KNO3 pyrotechnic systems have been studied by means of TG, DTA, and DSC methods and the results compared with those of pure oxidants. The apparent activation energy (E), ΔG #, ΔH #, and ΔS # of the combustion processes were obtained from the DSC experiments. The results showed that the nature of oxidant has a significant effect on ignition temperature, and the kinetic of the pyrotechnic mixtures’ reactions, and the relative reactivity of these mixtures was found to obey in the following order: Sn + Sr(NO3)2 > Sn + Ba(NO3)2 > Sn + KNO3.

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the each mixture were obtained [ 31 , 32 ]. Table 3 gives the calculated kinetics parameters for the studied pyrotechnic systems. Critical ignition temperature The critical ignition temperature ( T b ) is an

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Simultaneous TG-DTA-MS and TG-DSC have been used to investigate the complex reaction which takes place in the region of 300°C when the chlorinated rubber Alloprene is added to pyrotechnic compositions containing equal parts by weight of titanium and sodium nitrate. The results have been compared with those obtained for the titanium-strontium nitrate-Alloprene system.

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The acceleratory effect of potassium perchlorate on the reactivity of the red lead-silicon system has been studied by employing DTA and DSC. Supporting investigations on pure potassium perchlorate and the binary system red lead-potassium perchlorate suggest that the complex decomposition kinetics of potassium perchlorate drastically influences the oxidation of silicon. Further, the ternary system also undergoes a transition from exothermic smooth decomposition to ignition at a certain critical mass, as noted in the red lead-silicon and iron(III) oxide system. The criticality should be a result of the rise in temperature expressed as a perturbation of the steady-state energy conservation conditions, as postulated by Gray.

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Abstract  

Some applications of thermal analysis (TA) and temperature profile analysis (TPA) to the study of a variety of binary pyrotechnic systems are described. Factors that effect the combustion of such fuel/oxidant mixtures are discussed. Trends in burning behaviour and the experimental limitations of the techniques available are identified.

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Thermogravimetry (TG) and differential scanning calorimetry (DSC) have been used to examine the thermal behaviour, in N2 and in air, of the Si/Sb2O3, Si/KNO3, Si/Fe2O3 and Si/SnO2 pyrotechnic systems, in relation to the behaviour of the individual constituents.

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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  

The ageing characteristics of pyrotechnic compositions are influenced not only by temperature, but also by surrounding effects as humidity and vibrations. In this paper the thermal stability of the pyrotechnic system magnesium–sodium nitrate will be investigated. In an inert helium atmosphere two steps of mass loss, which were not completely separated from each other, were observed in the temperature range from 65 to 265C: a mass loss of about 15% between 65 and 160C and about 34% between 160 and 265C. It is assumed that these two steps are caused by different processes. The separation between the two steps was not or hardly detectable for measurements that were performed in a nitrogen atmosphere. Using MS and FTIR (mass spectrometry/Fourier transform infrared spectroscopy) the evolved gases were analysed. Only above about 170C evolving gases were detected (which means that during the first step no gases were detectable). The detected gas mainly consists of CO2, CO and N2O, with smaller amounts of NO2, NO and possibly HCN. A third step of mass loss (8–9%) was observed above 314C. The process which caused this step of mass loss is considered not to contribute significantly to the ageing of the material at much lower temperatures of maximum 80C, which is of interest in view of the use of the materials. Kinetic parameters for the processes which caused the first and the second step of mass loss were evaluated from kinetic analysis of the measured TG curves. By using these results the conversion can be predicted as a function of time and temperature. However, it must be considered that the inaccuracy of the predictions increases if the temperature for which the prediction is calculated is further away from the temperature at which the experiments were performed. This is caused by the exponential form of the kinetic equations. The calculations show that in particular the reaction which causes the first step of mass loss can run relatively quickly in the temperature range 25–80C, which could result in ageing of the material during storage at these conditions. The reaction which causes the second step of mass loss clearly runs at a much lower rate.

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