Search

To investigate the effect of different structures of MOF on the catalytic performance of ammonium perchlorate (AP) thermal decomposition. By adding 2-methylimidazole (2-MI) as an inhibitor during the synthesis of MOF-5, a two-dimensional (2D) MOF material was prepared and characterized by SEM, EDS, XRD, FT-IR and other means. The prepared two-dimensional material was added to the AP raw material to investigate its effect on the AP thermal decomposition process. After DSC and TG test, it was found that the addition of this kind of 2D MOF material can completely eliminate the low-temperature decomposition peak of the AP-based composite and advance the high temperature decomposition peak to 296.5 °C, and the apparent heat of decomposition increase to 905.6 J/g, which has a better catalytic effect than the bulk MOF-5. In addition, through the combustion test, it was found that 2D MOF, as a burning rate catalyst, can effectively enhance the burning rate of AP based solid propellant.

The modified attachment energy model was applied to predict the crystal morphology of hexanitrohexaazaisowurtzitane/1,3-dinitrobenzene (HNIW/DNB) cocrystal in ethanol. A double-layer interface structure was established based on experiments. Molecular dynamics simulation was employed to investigate the interaction of flat faces and ethanol solvents. We used periodic bond chains and roughness calculations to analyze the characteristics of the HNIW/DNB cocrystal. The crystal morphology of the HNIW/DNB cocrystal is mainly composed of the (001), (010), (102), and (111) faces in vacuum. The (001) face occupies the largest area (49.54%). In ethanol, the area of the (001) face increases to 68.58%. Ethanol molecules are adsorbed on the polar face through hydrogen bonding. In the slowest growth direction, two HNIW layers and one DNB layer alternately appear. The higher molecular recognition of the (001) face of HNIW/DNB resulted in this face becoming the most important growth face. Meanwhile, we also predicted the crystal morphologies of [epsilon]-HNIW and DNB in ethanol. The prediction morphologies are in excellent agreement with the experimental shapes. These simulation results can provide guidance for the recrystallization of HNIW/DNB. Key words: hexanitrohexaazaisowurtzitane, 1,3-dinitrobenzene, crystal morphology, molecular dynamics simulation, attachment energy model. Nous avons employe le modele d'energie de fixation modifie pour predire la morphologie cristalline du cocristal de HNIW/DNB dans l'ethanol. A partir de donnees experimentales, nous avons etabli que la structure de l'interface se presentait sous forme de double couche. Nous avons effectue une simulation de dynamique moleculaire pour etudier l'interaction entre les faces planes et le solvant, soit l'ethanol. Nous avons utilise la theorie des chaines de liaisons periodiques et le calcul de rugosite pour analyser les caracteristiques du cocristal de HNIW/DNB. La morphologie cristalline du cocristal de HNIW/DNB dans le vide est principalement decrite par les faces (001), (010), (102) et (111). La face (001) constitue la majorite de la surface, soit 49,54 %. Dans l'ethanol, le pourcentage de surface de la face (001) passe a 68,58 %. Les molecules d'ethanol sont adsorbees par liaison hydrogene sur la face polaire. Dans la direction de croissance la plus lente, deux couches de HNIW et une couche de DNB se succedent en alternance. Une meilleure reconnaissance moleculaire de la face (001) du cocristal de HNIW/DNB a revele que cette face devenait la face de croissance la plus importante. Parallelement, nous avons egalement predit les morphologies cristallines du [epsilon]-HNIW et du DNB dans l'ethanol. Les morphologies predites par le modele montrent une excellente concordance avec les formes observees experimentalement. Ces resultats de simulation peuvent servir a orienter les conditions de recristallisation du HNIW/DNB. [Traduit par la Redaction] Mots-cles : hexanitrohexaazaisowurtzitane, 1,3-dinitrobenzene, morphologie cristalline, simulation de dynamique moleculaire, modele d'energie de fixation., Introduction The crystal habit depends directly on the composition of crystals and become associated more closely with the physical and chemical conditions. (1-3) The study of growth habits not only [...]

Based on different optical theories, the principles of laser-induced fluorescence(LIF), coherent anti-Stokes Raman scattering(CARS), tunable diode laser absorption spectroscopy(TDLAS), laser absorption spectroscopy(LIBS), radiation method, remote sensing Fourier transform infrared spectroscopy(RS-FTIR), particle imaging velocity measurement(PIV) and schlieren technique applied to the testing of combustion of energetic materials are reviewed. The superiority of optical diagnostic techniques over conventional contact methods in combustion testing, the applicability, measurement objectives, strengths, and limitations of each optical method are analyzed. The development prospect of measuring techniques on combustion products, flame temperature, combustion flow field velocity, and flame structure in the combustion diagnosis of energetic materials is also prospected. It is pointed out that future work should combine multi-diagnostic methods to develop multi-dimensional measurements, to obtain more multidimensional micro-data information. There are 102 references attached. [ABSTRACT FROM AUTHOR]

In order to increase the burning rate and decrease the sensitivities of composite modified double-base(CMDB)propellant, supersonic jet milling technology was used to in-situ dispersion of nano catalysts(nano copper chromite and nano cadmium oxide)on the surface of ultrafine ammonium perchlorate(AP)to prepare nano-catalytic materials/ultrafine AP composites for using in high burning rate CMDB propellant with GATo. The scanning electron microscopy(SEM), differential scanning calorimetry(DSC)test, mechanical sensitivity test and the electrostatic spark sensitivity tests were used to analyze the nano catalytic materials/ultrafine AP composites. The combustion performance, mechanical performance, mechanical sensitivity and stability of GATo propellant containing nano catalytic materials/ultrafine AP composites were also studied. The results show that with the help of the supersonic jet pulverization force field, while the ultrafine AP was achieved, the nano catalytic materials were uniformly in situ dispersed on its surface, which not only increased the thermal decomposition rate of the ultrafine AP, but also reduced the mechanical sensitivity of ultrafine AP. Compared with the blank GATo propellant, the burning rate of GATo propellants containing nano catalytic materials/ultrafine AP composites increased from 55mm/s to 70.27mm/s(20°C, 10MPa), the mechanical properties and stability were basically maintained, the friction sensitivity was reduced from 95% to 80%, and the impact sensitivity characteristic drop height value was increased from 13.9cm to 14.7cm, achieving an effective balance between high burning rate and low sensitivity of CMDB propellant. [ABSTRACT FROM AUTHOR]

A series of guanidine cations and azole anions were designed for use as energetic salts. Their geometrical structures were optimized by the density functional theory (DFT) method. The counter ions were matched by the similar magnitude of the electron affinity (EA) of the cation and the ionization potential (IP) of the anion. The densities, heats of formation, detonation parameters, and impact sensitivity were predicted. The incorporation of guanidine cations and diazole anions are favorable to form thermal stable salts except cation A1. The diaminoguanidine cation has greater impact on the density and detonation properties of the salts than the triaminoguanidine cation. 2-Amino-3-nitroamino-4,5-nitro-dinitropyrazole is the best anion for advancing the detonation performance among all the anions. Incorporating the C=0 bond into the guanidine cations enhances the density and detonation performance of the guanidine-azole salts. The salts containing III1-III4 anion have better detonation properties than HMX, indicating that these salts are potential energetic compounds. Compared with RDX or HMX, some salts with diaminoguanidine cation display lower impact sensitivity. Key words: energetic salts, density functional theory, detonation properties, heats of formation. Nous avons imaginé une série de cations à base de guanidine et d'anions à base d'azole en vue d'une utilisation comme sels énergétiques. Nous avons optimisé leur structure géométrique au moyen d'une méthode basée sur la théorie de la fonctionnelle de la densité (DFT). Nous avons jumelé les contrions selon la similitude des valeurs d'affinité électronique (AE) des cations et de potentiel d'ionisation (PI) des anions. Nous avons calculé les valeurs prédictives de la densité, de la chaleur de formation, des paramètres de détonation et de la sensibilité à l'impact. L'incorporation des cations à base de guanidine et des anions à base de diazole s'est révélée favorable pour la formation de sels thermiquement stables, sauf pour ce qui est du cation A1. Le cation diaminoguanidinium a une plus grande influence sur la densité et les propriétés de détonation des sels que le cation triaminoguanidinium. Parmi tous les anions étudiés, le 2-amino-3-nitroamino-4,5-dinitropyrazole est celui qui a donné lieu à la plus grande amélioration de la performance de détonation. L'incorporation de la liaison C=O dans les cations guanidinium augmente la densité et améliore la performance de détonation des sels de type guanidine-azole. Les sels contenant les anions III1-III4 présentent de meilleures propriétés de détonation que le HMX, ce qui indique que ces sels pourraient éventuellement être employés comme composés énergétiques. Comparativement au RDX ou au HMX, certains sels contenant le cation diaminoguanidinium présentent une plus faible sensibilité à l'impact. [Traduit par la Rédaction] Mots-clés : sels énergétiques, théorie de la fonctionnelle de la densité, propriétés de déprotonation, chaleurs de formation., Introduction In the last decade, considerable attention was paid to the nitrogen-rich energetic salts. High nitrogen energetic materials are another area of advanced high energy density materials (HEDMs) aimed at [...]