scholarly journals The Effect of Al Particles Size on the Thermal Behavior and Kinetics of Al-MnO2 Thermite System

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jia-xing Song ◽  
Tao Guo ◽  
Wen Ding ◽  
Miao Yao ◽  
Li Yang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Thermal Behavior ◽  
Exothermic Reaction ◽  
Exothermic Peak ◽  
Decomposition Process ◽  
Particle Sizes ◽  
Ultrasonic Dispersion ◽  
Thermal Decomposition Process ◽  
Al Powder

Micron-MnO2 powder has unique thermal decomposition process compared with other metal oxides, and the different characteristics of components in thermite could affect the thermal performance of the whole system directly. In this work, the Al powder with different three particle sizes was combined with micron-MnO2 to prepare the Al-MnO2 thermite system, and the effect of Al powder particle sizes on the whole thermal behavior was studied. Firstly, the thermal decomposition process of micron-MnO2 and purity of Al powder are tested by TG-DSC. By using ultrasonic dispersion method, the fuel-rich thermite samples were prepared and characterized by SEM and TG-DSC at different heating rates. The Kissinger method was also employed to calculate the activation energy for the first exothermic peak. It was found that the thermal decomposition process of MnO2 in the thermite system can be significantly disturbed by different Al particles size. In other words, the effect of Al particle sizes on the thermite can be magnified due to the unique decomposition properties of micron-MnO2 instead of onset temperature of exothermic reaction changing simply. The activation energy of thermite system decreased with the reduction of Al particle sizes in micron-level, while in nanolevel the activation energy markedly increased. Finally, the possible reasons for phenomenon were discussed.

scholarly journals Thermal behavior and decomposition kinetics of rifampicin polymorphs under isothermal and non-isothermal conditions

2010 ◽  
Vol 46 (2) ◽  
pp. 343-351 ◽  
Author(s):  
Ricardo Alves ◽  
Thaís Vitória da Silva Reis ◽  
Luis Carlos Cides da Silva ◽  
Silvia Storpírtis ◽  
Lucildes Pita Mercuri ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Thermal Behavior ◽  
Melting Process ◽  
Decomposition Process ◽  
Stable Form ◽  
Thermal Decomposition Process ◽  
Mean Values ◽  
Conversion Level ◽  
Polymorphic Forms ◽  
Crystalline Forms

The thermal behavior of two polymorphic forms of rifampicin was studied by DSC and TG/DTG. The thermoanalytical results clearly showed the differences between the two crystalline forms. Polymorph I was the most thermally stable form, the DSC curve showed no fusion for this species and the thermal decomposition process occurred around 245 ºC. The DSC curve of polymorph II showed two consecutive events, an endothermic event (Tpeak = 193.9 ºC) and one exothermic event (Tpeak = 209.4 ºC), due to a melting process followed by recrystallization, which was attributed to the conversion of form II to form I. Isothermal and non-isothermal thermogravimetric methods were used to determine the kinetic parameters of the thermal decomposition process. For non-isothermal experiments, the activation energy (Ea) was derived from the plot of Log β vs 1/T, yielding values for polymorph form I and II of 154 and 123 kJ mol-1, respectively. In the isothermal experiments, the Ea was obtained from the plot of lnt vs 1/T at a constant conversion level. The mean values found for form I and form II were 137 and 144 kJ mol-1, respectively.

Thermal Decomposition of Phosphate Ore by Using Differential Scanning Calorimetric Method

2014 ◽  
Vol 887-888 ◽  
pp. 1005-1009
Author(s):  
Lin Zhuan Ma ◽  
Chao Huang ◽  
Jun Ming Guo ◽  
Zhi Ying Wang
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Weight Loss ◽  
Loss Rate ◽  
Decomposition Process ◽  
Differential Scanning Calorimetric ◽  
Heating Rates ◽  
Thermal Decomposition Process ◽  
Phosphate Ore ◽  
Dsc Curves

Phosphate ore was decomposed by using thermogravimetric (TG) and differential scanning calorimetric (DSC). The TG-DSC curves contained different sizes and heating rates. The results showed that phosphate ore had four weight loss stages at the range of 40 ~ 1100°C. With the particle size decreasing, the third weight loss stage became more obvious in TG curves and the endothermic peak became sharper in DSC curve ; the starting and ending temperature of thermal decomposition process moved to higher,the weight loss rate also tended to increase; the activation energy of phosphate ore endothermic decomposition process was calculated by Owaza method in 600~800°C, the average activation energy was 202.80 kJ / mol. It provided a basis for the utilizing of phosphate ore.

scholarly journals Thermal Decomposition of the HXeCl···H2O Complex in Solid Xenon: Experimental Characterization of the Two-body Decomposition Channel

2019 ◽  
Author(s):  
Masashi Tsuge ◽  
Markku Räsänen ◽  
Leonid Khriachtchev
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Water Molecule ◽  
Decomposition Product ◽  
Decomposition Process ◽  
Experimental Characterization ◽  
Thermal Decomposition Product ◽  
Thermal Decomposition Process ◽  
Theoretical Predictions

The thermal decomposition process of HXeCl···H2O in solid Xe is studied, and HCl···H2O is identified as a decomposition product. The production is due to the two-body (2B) decomposition of HXeCl moiety, in agreement with theoretical predictions. Two types of 2B decomposition paths are predicted: catalytic and unimolecular 2B decompositions, where water molecule plays different roles. In an experiment to selectively produce HXeCl···D2O, only HCl···D2O is observed as a thermal decomposition product, indicating the occurrence of unimolecular 2B decomposition, where water molecule serves as a spectator. The activation energy for this decomposition process is experimentally determined to be 15 kJ mol−1.<br>

Electron paramagnetic resonance and microstructural insights into the thermal behavior of simonkolleite nanoplatelets

2020 ◽  
Vol 22 (17) ◽  
pp. 9503-9512
Author(s):  
Arpad Mihai Rostas ◽  
Andrei Cristian Kuncser ◽  
Daniela Ghica ◽  
Alexandra Palici ◽  
Valentin Adrian Maraloiu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Experimental Data ◽  
Thermal Decomposition ◽  
Electron Paramagnetic Resonance ◽  
Thermal Behavior ◽  
Decomposition Process ◽  
Thermal Decomposition Process ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

The thermal decomposition process of simonkolleite, at 500 °C was monitored by EPR and electron microscopy. The experimental data indicate that after an 1 h at 500 °C, three morphologies can be observed from the thermal decomposition of ZHC.

The Thermal Decomposition Behavior of Graphene Oxide/HMX Composites

2015 ◽  
Vol 645-646 ◽  
pp. 110-114 ◽  
Author(s):  
Gui Yu Zeng ◽  
Jian Hua Zhou ◽  
Cong Mei Lin
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Graphene Oxide ◽  
Interlayer Space ◽  
Decomposition Process ◽  
Thermal Decomposition Process ◽  
Hummers Method ◽  
Thermal Decomposition Behavior ◽  
Decomposition Behavior ◽  
Decomposition Activation Energy

Graphene oxide (GO) was prepared by Hummers method and GO/1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) composite was prepared via an ultrasonic compounding method. The structure of GO was characterized using XRD and SEM, the thermal decomposition of HMX and GO/HMX composite was analyzed by DSC/TG test. The results show that interlayer space of GO increases markedly, the thermal decomposition process of HMX can be promoted with the nanolayer structure of GO, resulting the reduced thermal decomposition activation energy of about 50 kJ/mol with 1% GO.

scholarly journals Thermal Decomposition of the HXeCl···H2O Complex in Solid Xenon: Experimental Characterization of the Two-body Decomposition Channel

2019 ◽  
Author(s):  
Masashi Tsuge ◽  
Markku Räsänen ◽  
Leonid Khriachtchev
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Water Molecule ◽  
Decomposition Product ◽  
Decomposition Process ◽  
Experimental Characterization ◽  
Thermal Decomposition Product ◽  
Thermal Decomposition Process ◽  
Theoretical Predictions

The thermal decomposition process of HXeCl···H2O in solid Xe is studied, and HCl···H2O is identified as a decomposition product. The production is due to the two-body (2B) decomposition of HXeCl moiety, in agreement with theoretical predictions. Two types of 2B decomposition paths are predicted: catalytic and unimolecular 2B decompositions, where water molecule plays different roles. In an experiment to selectively produce HXeCl···D2O, only HCl···D2O is observed as a thermal decomposition product, indicating the occurrence of unimolecular 2B decomposition, where water molecule serves as a spectator. The activation energy for this decomposition process is experimentally determined to be 15 kJ mol−1.<br>

scholarly journals Study of the thermal behavior in solid state of Mn(II)-Diclofenac Complex

2018 ◽  
Vol 43 (1) ◽  
pp. 59 ◽  
Author(s):  
Marcelo Kobelnik ◽  
Valdecir Ângelo Quarcioni ◽  
Adélia Emília De Almeida ◽  
Clóvis Augusto Ribeiro ◽  
Marisa Spirandeli Crespi
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Solid State ◽  
Thermal Behavior ◽  
Isoconversional Method ◽  
Exothermic Peak ◽  
X Ray ◽  
Purge Gas ◽  
Dsc Curves

The preparation, characterization and thermal behavior of Mn(II)-diclofenac solid-state complex was investigated by simultaneous TG/DTA and DTG curves, DSC, X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques. The thermal evaluation was carried out with sample masses of 2 and 5 mg, with the purpose of comparing the values of activation energy regarding dehydration, monotropic phase transition and thermal decomposition in both samples mass. The DSC curves were obtained in opened and with crimped lids crucibles of aluminum under oxygen purge gas and static air (without purge gas). The DTA and DSC curves show an exothermic peak between 150-180 °C depending on heating rate, which can be attributed to the monotropic non-reversible reaction. The activation energy (Ea/kJ mol-1) to dehydration, the monotropic phase transition and the first thermal decomposition step were determined by Capela-Ribeiro nonlinear isoconversional method. The activation energy under oxygen dynamic purge gas shows lower values compared to those obtained under static air.

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