Preparation and Properties of 1, 3, 5, 7-Tetranitro-1, 3, 5, 7-Tetrazocane-based Nanocomposites

A new insensitive explosive based on octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine (HMX) was prepared by spray drying using Viton A as a binder. The HMX sample without binder (HMX-1) was obtained by the same spray drying process also. The samples were characterised by Scanning Electron Microscope, and X-ray diffraction. The Differential Scanning Calorimetry and the impact sensitivity of HMX-1 and nanocomposites were also being tested. The nanocomposite morphology was found to be microspherical (1 μm to 7 μm diameter) and composed of many tiny particles, 100 nm to 200 nm in size. The crystal type of HMX-1 and HMX/Viton A agrees with raw HMX. The activation energy of raw HMX, HMX-1 and HMX/Viton A is 523.16 kJ mol-1, 435.74 kJ mol-1 and 482.72 kJ mol-1, respectively. The self-ignition temperatures of raw HMX, HMX-1 and HMX/Viton A is 279.01 °C, 277.63 °C, and 279.34 °C, respectively. The impact sensitivity order of samples is HMX/Viton A < HMX-1 < raw HMX from low to high.Defence Science Journal, Vol. 65, No. 2, March 2015, pp.131-134, DOI:http://dx.doi.org/10.14429/dsj.65.784

Thermochemical properties of nanometer CL-20 and PETN fabricated using a mechanical milling method

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and pentaerythritol tetranitrate (PETN), with mean sizes of 73.8 nm and 267.7 nm, respectively, were fabricated on a high-energy ball-mill. Scanning electron microscope (SEM) analysis was used to image the micron-scale morphology of nano-explosives, and the particle size distribution was calculated using the statistics of individual particle sizes obtained from the SEM images. Analyses, such as X-ray diffractometer (XRD), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS), were also used to confirm whether the crystal phase, molecular structure, and surface elements changed after a long-term milling process. The results were as expected. Thermal analysis was performed at different heating rates. Parameters, such as the activation energy (ES), activation enthalpy (ΔH≠), activation free energy (ΔG≠), activation entropy (ΔS≠), and critical temperature of thermal explosion (Tb), were calculated to determine the decomposition courses of the explosives. Moreover, the thermal decomposition mechanisms of nano CL-20 and nano PETN were investigated using thermal-infrared spectrometry online (DSC-IR) analysis, by which their gas products were also detected. The results indicated that nano CL-20 decomposed to CO2 and N2O and that nano PETN decayed to NO2, which implied a remarkable difference between the decomposition mechanisms of the two explosives. In addition, the mechanical sensitivities of CL-20 and PETN were tested, and the results revealed that nano-explosives were more insensitive than raw ones, and the possible mechanism for this was discussed. Thermal sensitivity was also investigated with a 5 s bursting point test, from which the 5 s bursting point (T5s) and the activation of the deflagration were obtained

Preparation and Characterization of HMX/Estane Nanocomposites Central

Abstract: A new insensitive explosive based on octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was prepared by spray drying using Estane 5703 as a binder. Scanning electron microscopy was used to characterize the morphology and particle size of the HMX/Estane 5703 nanocomposites. The composites were analyzed by X-ray diffractometry and differential scanning calorimetry and their impact sensitivity was determined. For comparison, raw HMX was also tested using these three methods. The nanocomposite morphology was found to be microspherical (1 to 8 μm diameter) and composed of many tiny particles, 30 to 150 nm in size. The crystal type of the HMX/Estane 5703 nanocomposites was unchanged. The activation energy, self-ignition temperature and average drop height of the raw HMX were 515.66 kJ·mo

Nano-CL-20/HMX Cocrystal Explosive for Significantly Reduced Mechanical Sensitivity

Spray drying method was used to prepare cocrystals of hexanitrohexaazaisowurtzitane (CL-20) and cyclotetramethylene tetranitramine (HMX). Raw materials and cocrystals were characterized using scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, Raman spectroscopy, and Fourier transform infrared spectroscopy. Impact and friction sensitivity of cocrystals were tested and analyzed. Results show that, after preparation by spray drying method, microparticles were spherical in shape and 0.5–5 µm in size. Particles formed aggregates of numerous tiny plate-like cocrystals, whereas CL-20/HMX cocrystals had thicknesses of below 100 nm. Cocrystals were formed by C–H⋯O bonding between –NO2 (CL-20) and –CH2– (HMX). Nanococrystal explosives exhibited drop height of 47.3 cm, and friction demonstrated explosion probability of 64%. Compared with raw HMX, cocrystals displayed significantly reduced mechanical sensitivity

Reduce the Sensitivity of CL-20 by Improving Thermal Conductivity Through Carbon Nanomaterials

Abstract The graphene (rGO) and carbon nanotube (CNT) were adopted to enhance the thermal conductivity of CL-20-based composites as conductive fillers. The microstructure features were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and tested the properties by differential scanning calorimeter (DSC), static electricity accumulation, special height, thermal conductivity, and detonation velocity. The results showed that the mixture of rGO and CNT had better effect in thermal conductivity than rGO or CNT alone under the same loading (1 wt%) and it formed a three-dimensional heat-conducting network structure to improve the heat property of the system. Besides, the linear fit proved that the thermal conductivity of the CL-20-based composites were negatively correlated with the impact sensitivity, which also explained that the impact sensitivity was significantly reduced after the thermal conductivity increased and the explosive still maintained better energy

Carbon-coated copper nanoparticles prepared by detonation method and their thermocatalysis on ammonium perchlorate

Carbon-coated copper nanoparticles (CCNPs) were prepared by initiating a high-density charge pressed with a mixture of microcrystalline wax, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and copper nitrate hydrate (Cu(NO3)2·3H2O) in an explosion vessel filled with nitrogen gas. The detonation products were characterized by transmission electron microcopy (TEM), high resolution transmission electron microcopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Raman spectroscopy. The effects of CCNPs on thermal decomposition of ammonium perchlorate (AP) were also investigated by differential scanning calorimeter (DSC). Results indicated that the detonation products were spherical, 25-40 nm in size, and had an apparent core-shell structure. In this structure, the carbon shell was 3-5 nm thick and mainly composed of graphite, C8 (a kind of carbyne), and amorphous carbon. When 5 wt.% CCNPs was mixed with 95 wt.% AP, the high-temperature decomposition peak of AP decreased by 95.97, 96.99, and 96.69 °Cat heating rates of 5, 10, and 20 °C/min, respectively. Moreover, CCNPs decreased the activation energy of AP as calculated through Kissinger’s method by 25%, which indicated outstanding catalysis for the thermal decomposition of AP

Catalysis of a Nanometre Solid Super Acid of SO42-/TiO2 on the Thermal Decomposition of Ammonium Nitrate

Raw TiO2 nanoparticles were prepared using the hydroly‐ sis of TiCl4. The nanoparticles were subjected to a surface treatment in diluted sulphuric acid and, subsequently, calcined at different temperatures. Then, a type of super solid acid (SO42-/TiO2) with particle sizes of 20∼30 nm was fabricated. The catalysis of SO42-/TiO2 on the thermolysis of ammonium nitrate (AN) was probed using thermal analysis. For SO42-/TiO2 (AN doped with 3%SO42-/TiO2), the onset temperature decreased by 19°C and the peak tem‐ perature decreased by 15.8°C. For TiO2 (AN doped with 3%TiO2), the peak temperature decreased by only 0.5°C. Using the DSC-IR technology, the gas products of the decomposition of 3%SO42-/TiO2-doped AN were detected. We found that the products were mainly N2O (g) and a small amount of H2O (g), and that no NH3 (g) or HNO3 (g) was detected, which ascertained the decomposition reaction of NH4NO3→N2O(g)+H2O(g). In addition, the catalysis mechanism of SO42-/TiO2 on the AN decomposi‐ tion was discussed in detail