Impact and Friction Sensitivity of Energetic Materials：Methodical Evaluation of Technological Safety Features

Key methods developed and used in the USSR and in the Russian Federation to determine the impact and friction sensitivity of energetic materials and explosives have been discussed.Experimental methodologies and instruments that underlie the assessment of their production and handling safety have been described.Studies of a large number of compounds have revealed relationships between their sensitivity parameters and structure of individual compounds and compositions.The range of change of physical and chemical characteristics for the compounds we examined covers the entire region of their existence.Theoretical methodology and equations have been formulated to estimate the impact and friction sensitivity parameters of energetic materials and to evaluate the technological safety in use.The developed methodology is characterized by high-accuracy calculations and prediction of sensitivity parameters.

An overview on importance, synthetic strategies and studies of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW)

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW), commonly called as CL-20, is a high energy and high density material of keen interest to both commercial and scientific worlds due to its greater insensitivity(reduced sensitivity) along with a positive high heat of formation, which is due to the azanitro groups attached to the skeleton of HNIW and its highly strained cage structure. It plays a remarkable role in modification and replacement of most of the propellant(gun and rocket) preparations. In this report we present the comparative strategies involved in the syntheses of HNIW with respect to economical and environmental aspects. Various methods reported in the literature on the purification of the crude HNIW(α-HNIW) to obtain ε-form of HNIW(high dense/more potential) are consolidated. Understanding of the structure, morphology, energetics, thermal behavior and their modification to meet the applicability(decreased impact sensitivity) determines the industrial application of HNIW. A compilation of the available literature on the aforementioned characteristic properties for obtaining a value added ε-HNIW is discussed here. This overview also reports the literature available on newer forms of HNIW including derivatives and cocrystals,which increase the performance of HNIW.

The effect of al particle size on thermal decomposition,mechanical strength and sensitivity of Al/ZrH_(2)/PTFE composite

To study the thermal decomposition of Al/Zr H_(2)/PTFE with different Al particle size as well as mechanical strength and impact sensitivity under medium and low strain rates,molding-vacuum sintering was adopted to prepare four groups of power materials and cylindrical specimens with different Al particle size.The active decomposition temperature of Zr H_(2) was obtained by TG-DSC,and the quasi-static mechanics/reaction characteristics as well as the impact sensitivity of the specimen were studied respectively by quasi-static compression and drop-hammer test.The results show that the yield strength of the material decreased with the increase of the Al particle size,while the compressive strength,failure strain and toughness increased first and then decreased,which reached the maximum values of 116.61 MPa,191%,and 119.9 MJ/m respectively when the Al particle size is 12-14 mm because of particle size grading.The specimens with the highest strength and toughness formed circumferential open cracks and reacted partly when pressed.Those with developmental cracks formed inside did not react.It is considered that fracture of specimens first triggered initial reaction between Al and PTFE to release an amount of heat.Then ZrH_(2) was activated and decomposed,and participated in subsequent reaction to generate Zr C.The impact sensitivity of the specimens decreased with the increase of Al particle size.

Sonochemically assisted synthesis of nano HMX

Nanotechnology has played an influential role in improving the energetic content without subsiding the performance of high energy materials in the current era.In this work,HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)nanoparticles were prepared by sonochemically assisted solvent-antisolvent spray technique focussing the reduction in its size so as to improve its energetic properties.In order to fabricate nano HMX various parameters such as different solvents and temperature were investigated.Sonication is one of the strategies recently explored in this regard;so time dependent study of sonication using probe sonicator was performed.It has been postulated that bubble formed during sonication when collapses generate high temperature and many nucleation sites which leads to the formation of uniform spherical particles with small size and fast transition phase.XRD studies depicted phase transformation from a toβas a result of sonication.The TEM images revealed that the rise in the sonication time resulted into decrease in the particle size from 300 to 10 nm.Differential scanning calorimetry(DSC)was employed to determine the heat release of the samples and enhancement in the heat release with the decrease in the particle size.A decrease in the spark sensitivity was observed from 2 J(regular HMX)to 50 mJ(nano HMX).

Theoretical Studies on Two Possible Conformers of TNDAIW at Hartree-Fock Level

Tetranitrodiazidoacetylhexaazaisowurtzitane (TNDAIW) is a novel polyazapolycyclic caged polyazidonitramine explosive first synthesized in our laboratory. Two possible conformers of TNDAIW with C_s symmetry were fully optimized using the HF/6-31G(d) level of theory. TNDAIW with the optimized geometries probably exists, and is predicted to be more stable than epsilon-hexanitrohexaazoisowurtzitane (epsilon-CL-20) based on the lengths of N-N, C-C and C-N bonds. The impact and shock sensitivities are lower for the possible conformers of TNDAIW than those for epsilon-CL-20. TNDAIW with the optimized possible conformers is estimated to be a promising novel high energy density explosive.