مجله تحقیق و توسعه مواد پرانرژی
سال هفتم شماره 1 (پیاپی 13، بهار و تابستان1390)

Oxidizer is one of the important components in liquid bipropellants. Different oxidizers such as liquid oxygen, ammonia, fluorine or chlorine derivatives, nitric acid, nitrogen tetroxide have been used together with different fuels. Among these oxidizers, nitrogen tetroxide is a more important oxidizer because of good storable conditions, a high impulse especially in combination with nitric oxide and low corrosion. In this paper physical, chemical and performance properties of these oxidizers and preparation methods of nitrogen oxide are reviewed and according to advantages and disadvantage of each methods, its manufacturing is from reaction of FeSO4 and NaNO2 presented.

According to the fact that CL-20 has better thermodynamic properties (energy content, density, flame temperature, etc.) and oxygen balance in comparison to HMX and RDX, CL-20-based propellants are also expected to have better thermodynamic properties than the propellants containing HMX and RDX. Since other parameters such as ballistic properties, mechanical properties, stability, sensitivity, etc. have an important role in evaluation of the performance of a propellant, all of these parameters should be considered so that the performance of a propellant can be correctly judged. This article reviews the main features of propellants containing CL-20 compared to propellants containing RDX and HMX.

Burning rate catalysts or burning rate modifiers, are classes of materials that improve the burning rate of the propellant by adjusting the rate of burning at the burning surface. These materials have important roles in grain tailoring and also in desirable thrust-time curves. Their main role, is reducing dependency of burning rate to temperature and chamber pressure, because creating plateau and mesa zones that modify ballistic properties. Hence, propellants that have high performance in wide pressure range, but with constant burning rate are desirable for scientists. Burning rate modifiers, are the most effective materials that can make such properties. In this paper, we reviewed the mechanisms of burning rate modifiers and their effect on performance of propellants.

One of the most important objective of gun propellant research is to increase muzzle kinetic energy and system performances (enhanced rang, hit probability and terminal effectiveness on target). Researches show that the solid propellants for barreled weapons are used in several temperature conditions. For example, when a weapon is fired, the propellant is submitted to temperatures ranges of - 40 °C to +50 °C. The main result is a loss in the shoot precision due to the material degradation. In the case of conventional propellants (single base, double base and triple base), ballistic parameters (as chamber pressure and muzzle velocity) are highly dependent to the temperature variation. In these propellants, there is a great change in chamber pressure and muzzle velocity by variation of temperature in a specific range. Therefore by reducing or eliminating the temperature coefficient of propellant, performance of propulsion system increases significantly. In This kind of novel propellant named low temperature coefficient (LTC) gun propellant, there is a reduction in temperature coefficient by change of formulation. In this paper meanwhile introduction of this new propellant and investigation of adjusting factor of temperature coefficient, we have compared ballistic performance and safety parameters of this new propellant with conventional 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.

Liquid rocket thrust chambers are used widely in military crafts and space crafts because of their high specific impulse and thrust management capability. Combustion of liquid propellants in combustion chambers produces required thrust for shooting and movement of rocket in space. A thrust chamber is formed from three main parts: injector, combustion chamber and nozzle. Although there is a lot of a paper in field of rheology, atomization and combustion of liquid propellant, but there is limited published research in the field of design of liquid thrust chamber. In this article, the combustion chamber and different parts of liquid rocket motor are presented, then different types of prevalent injectors and their important design parameters and also common various methods for cooling of liquid motors are expressed.

Hydrogen peroxide in high concentrations (about 98%) is considered as an important energetic substance. In this paper, the methods for the separation of impurities and ions and concentrating of commercial solution of hydrogen peroxide is investigated. The results showed that the purification has been well done via the ion exchange and distillation techniques. Also vacuum distillation and then cooling crystallization are suitable methods for the concentration of hydrogen peroxide.