مجله تحقیق و توسعه مواد پرانرژی
سال دهم شماره 1 (پیاپی 22، بهار و تابستان 1393)

In this study, firstly all methods for increasing of blast temperature and pressure of explosive materials have been investigated, then by introducing the general principles of thermobaric explosives (TBXs), various types of additives used in TBXs are identified and their general properties are presented and analyzed. Furthermore, the limitations arising from the incomplete combustion of aluminum metal in the blast systems and useful approaches to improve the performance of metallic additives used in TBXs have been introduced as well. The results of these studies suggest using of high energy metal alloys, halogenic binders, metal oxide catalysts or small amount of dense mineral oxidizers in the plastic bonded thermobaric explosives.

Composite solid propellant is composed of crystalline oxidizer particles dispersed in polymeric fuel binder. Ammonium perchlorate (AP) is used as the most common oxidizer and hydroxyl terminated polybutadiene (HTPB) as the fuel binder. The ballistics of a composite propellant can be improved by adding a catalyst such as, nanosized metals, metal oxides, alloys, spinels and etc, which accelerates the rate of decomposition of AP. This review represents an attempt to summarize literature data on thermal decomposition of ammonium perchlorate, the mechanism of thermal decomposition and various factors which influence on the thermal decomposition of ammonium perchlorate. Also in this study, an attempt to collect summarized literature data on catalytic effect of nanosized spinels compound on the thermal decomposition of ammonium perchlorates is made. However, our literature survey was shown that spinels nanoparticles of transition metal oxides, can be remarkably affect the kinetics of decomposition of ammonium perchlorate and increase the burning rate of composite solid propellants.

Double base solid propellant burning rate is highly dependent on the pressure, so that the combustion duration propellant rocket engines, combustion vibration leads to considerable changes in pressure. This could lead to an explosion in rocket engines. The best case is propellant combustion independent of pressure. Ballistic modifiers added to propellant formulation for reduce pressure sensitivity and reduce or increase of burning rate also. Lead and copper salts are materials that create plateau and mesa in double base propellant. In this article, effective ingredient in creation of plateau effect in double base propellant investigated. Some of these ingredients are particle size, concentration, dispersal, decomposition temperature and ability of ultraviolet ray of catalyst. In addition to, mechanism of create plateau and mesa in noncatalysed double base propellant and also empirical, radically and preckel mechanisms of create plateau and mesa for lead catalysts in double base propellant investigated.

In this article charging of explosives through casting has been investigated. Melt casting of TNT-based explosives is one of the most common techniques to economic and mass production of explosives. TNT is the only molten explosive at low temperature (80.4 C), so it is a convenient matrix for casting. Shrinkage of TNT in amount of 11-12% during solidification causes some problems in melt casting. In this article a description of different aspects of melt casting including material, common formulations, Meisner process, numerical simulation and comparison of advantages and disadvantages have been discussed. Studies show that the melt casting is a simple and feasible technique which can be safely used at industrial scale.

Investigation shows that the some complex and expanded parameters are effective on the burning rate. In this paper we evaluate the effect of particles dispersion, size of AP particle, the size of Al particles, Fe2O3, viscosity, shape factor, the size of mixer and the mechanical parameters such as tensile and stress on the burning rate. These studies show that the decrease of AP particles, size distribution, using nano-size Al particles, decreasing the mixer size and adding burning rate catalysts such as Fe2O3 can increase the burning rate of composite propellant. Also loaded stress and strain can increase this parameter.

In this article, to obtain water resistant ANFO explosive, the effect of some components were investigated. To reach this aim, four components including guar gum, borax, eremurus (as glue) and superabsorbent sodium polyacrylate were selected. To determine and optimize the percentage of components in the mixture, design of experiments in Minitab software was used. Finally, the optimized product including 90% ANFO and 10% of mixture of four compounds were obtained, which the water penetration into 100gr of this product (in 250ml graduated cylinder, after 12 hours) was about 10 mm.

Liquid hydrogen is used as a powerful and efficient propellant in spacecraft industries. This paper first presents the main principles of hydrogen liquefaction. Then, different methods for hydrogen liquefaction, including four general categories: precooled Linde-Hampson process, Claude process, helium-precooled Claude process and liquefaction by small cryo-coolers, are expressed along with their advantages and disadvantages. Considering native technology, the precooled Linde-Hampson process for small scale hydrogen liquefaction has been selected.