The formulation of the composite propellant is constituted of solid particles of (ammonium perchlorate) as well as metal fuel such as aluminum particles which are all dispersed homogenously within the Binder matrix. The availability of these solid particles affects the combustion mechanism of the composite propellant and causes the betterment in the performance parameters of rocket such as: increasing in specific impulse and burning time. The very accentuation of this paper is upon the acceleration effect and the derived phenomena of its (including agglomeration, pit formation by means of solid particles within propellant matrix, heat feedback, heat transferring -made of agglomerates- unto the surface of propellant which is being burnt) on the combustion mechanism of composite solid fuels which is conducive to increase in the burning rate of propellant. The rest of the paper is devoted to effects of miscellanies of factors such as pressure, static burning rate, and Al content upon increasing the burning rate of propellant.

In this Article the use of nanoaluminum particles in solid propellant based on ammonium perchlorate (AP) have been reviewed. The effect of aluminum nanoparticles as metallic fuels in solid propellants on performance parameter such as burning rate, initiation temperature combustion and residual ash particle size reduction are investigated. Significant increases in propellant burning rates, shorter ignition delays and shorter agglomerates burning times were recently obtained for composite solid propellant formulations containing nanoaluminum particles. As Al particle size is decreased, the Al combustion takes place closer to the propellant burning surface, with a corresponding large increase in burning rate.

Composite solid propellants are materials that constitute from an oxidizer, an organic binder, a metallic fuel, additives and etc. Nowadays the size of energetic particles is attended because of their effects on propellants performance. Size reduction is well known way to increasing reactivity of additives in propellant formulations. Nanoparticles have considerable effects on composite solid propellants properties due to their high surface area to volume ratio. The results of using of nanoparticles in composite solid propellants include increase of burning rate, ignition delay shortening, burning quality improvement, decomposition temperature decreasing, viscosity increasing and various effects on mechanical and sensitivity properties.

Metallic nanoparticles are widely used in high energy materials (explosives, propellants and pyrotechnics). Nanoparticles are used in solid propellants as fuel additives in order to improve the performance. In this paper, the role of nano-aluminum particles on burning behavior of solid composite propellant has been investigated. Nano-aluminum particles are considered as one of the most important energetic components of metallic fuel in the solid composite propellants. Studies showed that the addition of nano-aluminum particles increases the burning rate, reducing the amount of agglomeration, decreasing diameter of burning particles, falling combustion temperature and reducing the amount and size of residual ash. The use of nano-aluminium particles leads to reduction the pressure exponent in the burning rate law. Based on reviews size reduction of
nano-aluminium particles from micron to nano, increases the burning rate of solid composite propellants about 100 percent.

Composite solid propellants have found wide spread applications in missile industries, such as high density, high specific impulse, and possibility of producing large scale grains. These solid propellants consist of three main chemical ingredients, including oxidizer, fuel, and binder. Recently ,Hydroxyethyl Terminal Poly-Butadiene (HTPB) has been used abundantly for these propellants due to its good mechanical properties and ability to high solid loading (88 to 90% of solid loading, including Al and AP). The mechanical properties of solid rocket propellants are crucial for proper functioning of rocket engines. In this study, the effect of T313 (chain extender) and MAPO (bonding agent) on mechanical properties of propellant is investigated. In addition tothe necessity of these substances in the propellant, the formulation and the reasons for utilizing MAPO and T313 are discussed. Different compositions havebeen prepared by incorporating different percents of MAPO and T313 for evaluation. Also, their effects on pot life, mechanical properties, and density are studied. Based on the results, the amount of MAPO and T313 should be used in optimum amount and these compounds have great influence on the rheological and mechanical properties.

Concentrated suspension of binders in composite propellant causes a complex phenomena so that controlling of rheology properties is difficult due to high percentage of fillers. Composite solid propellant contains paste suspension of mixtures of different components, e.g. oxidizer, fuel and binder. Increasing the percentage of solid phase without increment of viscosity is an important subject in the production of solid propellant. This problem can be solved using two different particle sizes distribution. Five samples of composite solid propellants on the basis of hydroxyl terminated polybutadiene (HTPB) with 85% of solid phase containing dual sizes of ammonium perchlorate (AP) have been prepared. These samples have different coarse/fine ratios between 80/20 to 60/40. It was found that optimum temperature for casting of propellant is greater than 40C. The best ratio for obtaining the least viscosity is 70/30 coarse/fine ratio.

HTPB based composite Solid propellants are the source of power for the propulsion of rockets and missiles. Since composite solid rocket propellants, used in rockets and missiles is the fastest degrading component of the complete system, shelf life of the system is mainly governed by the life of the propellants. During storage and transportation, the propellant grains are subjected to various conditions such as humidity, temperature, vibration, and shocks. This condition causes significant changes in mechanical properties of the propellant. In this paper the effects of parameters such as particle size of metallic fuel, grain shape, temperature, humidity and migration on the aging composite solid propellant was studied. The Investigations showed that the Nanoaluminum (nano vs micro) is very susceptible to ageing phenomena. The free standing grains have less aging than case-bonded grains. In general, the temperature, humidity, plasticizer migration and gaseous diffusion have negative effects on the chemical and physical properties of propellant.

Metallized propellants are kind of propellant that have metal powder as fuel. Because of high specific impulse, high density and combustion products with low molecular weight, these poropellants have multiple advantages (such as higher performance) compared to conventional propellants. Metal powders such as Al, B, Be, Li, Mg, and Zr are the most important metal powders that are used in these kinds of propellants. Al powders, because of its convenient density, high combustion energy and specific impulse are more used. In this article, the effect of metal powders on the properties of solid propellants is investigated.

Gel propellants are an optimum state from of liquid propellants. The advantages of liquid and also solid propellants are kept in gel propellants but their disadvantages were mainly omitted. According to published informations, different kinds of gellants are used to make gel propellants. Among them, Silica is known as a good gellants for IRFNA oxidant and kerosene fuels. This gellant due to Si-OH groups on its surface can produce hydrogen bonds when mixed with mentioned oxidant and fuels which lead to production of a stable physical gel. Cellulosic gellants are suitable for amine fuels. They produce physical gel through hydrophobic interactions of substituted groups on glucopyranose units and also by hydrogen interaction. In this paper the types of gellants and gelation mechanism are discussed.

In this paper, the factors affecting on shock wave and impact Sensitivity such as oxygen balance, porosity and components particle size on composite solid propellants have been investigated. The energetic components of propellants such as oxidizer and fuel usually effect shock wave sensitivity. changing inpropellant composition, particle size and manufacturing process, determine the sensitivity properties of propellants. The studies show that, shock wave sensitivity of composite solid propellants have been increased by increasing the oxygen balance, porosity and ammonium percholorate particle size. shock wave sensitivity increased with increasing nitramine particles size. The impact sensitivity of composite solid propellants also depends on oxygen balance and porosity.