Determination of influence of al powders adding on performance of double base solid propellants in rockets

Solid propellant for rockets are primarily of two types. The more common type is a double-base composition consisting principally of a collided mixture of nitro-cellulose (NC) and nitro-glycerine (NG). The other type consists of a heterogeneous mixture of an organic fuel, an inorganic oxidising agent, and a binding agent. Present propellant of higher energy along with superior mechanical properties to with-stand stresses during high acceleration. Composite modified double-base (CMDB) propellants take advantage of both double-base (DB) and composite propellants (CP), where in oxidisers, high energy materials and metallic powders are incorporated in NC - NG matrix. CMDB propellants are being increasingly used for the propulsion of military and space vehicles. DB compositions are used in cannon, small arms, mortars, rockets and jet propulsion units. Composite compositions are used in rocket assemblies and jet propulsion units. CMDB propellants take the advantage of both double-base and composite propellants systems. The propellants comprise of and oxidiser (AP, KP, AN) and/or high energy materials (RDX, HMX, PETN) and metallic fuel (aluminium) dispersed in DPB matrix. Light metal powders especially aluminium extensively employed in composite and CMDB propellant formulations for both to enhance the ballistic performance and to damp acoustically unstable burning. On burning the aluminium particles, aluminium oxide formed in the composition region diffuses on to the particle surface as well as outward of the flame zone, and condenses. The large amount of energy liberated by subsequent reactions of Al with the primary detonation products will, however, maintain a high pressure for a longer period of time then would be optioned without Al. Powdered Al usually is 14 to 18 % of the propellant by weight. Boron, even though it appears as one of the high energy fuels and is lighter than aluminium has not proven to be a practical fuel because it is so difficult to burn with high efficiency in combustion chambers of reasonable length. Beryllium burns much more easily than boron, but it is highly toxic powder absorbed by humans and animals when inhaled. Perchlorates and inorganic nitrates are used crystalline oxidiser in solid propellants. AP is the most widely used oxidiser. Other solid oxidiser, AN and KP were used in production rockets. The oxidising potential of the perchlorates is high. The inorganic nitrates are relatively low performance oxidisers compared with perchlorates. Small percentages of additives are used to control the physical and chemical properties of the solid propellants.Additives have been used for the following typical purposes:(1) Accelerate or decelerate the burning (catalyst), (2) Increase chemical stability to avoid deterioration during storage, (3) Control variaous processing properties of propellant during fabrication (curing time, fluidity for casting, wetting agent,etc.),(4) Control radiation absorption properties of burning propellant, (5) Increase physical strength and decrease elastic deformation, (6) Minimize temperature sensitivity.Solid propellants are chemicals which produce hot, high gases can therefore be used to provide the reaction force for rocket propulsion a typical solid propellant rocket engine has three principal components; (1) The propellant grain, (2) The igniter and (3) The hardware (the case and nozzle).Most rocket motors are constructed to accommodate maximum pressures developed by the propellants. When the propellant charge is ignited,the pressure within the rocket chamber generally increases within 0.005 to 0.05 second to a maximum value determined by the burning rate of the propellant and the diameter of the nozzle orifice.The velocity of the rocket and its ballistics may be affected by change in initial temperature,so that uniformity is poorer at low and high temperatures than at normal temperatures. In this study, varying amounts of Al powder were added to DB propellant formulation to the determine the effect of aluminium on the propellant's extinction characteristics. The aluminium concentrations where changed, 0,2 % to 12 %. The linear burning rate of aluminium added mixture decreases with increasing amount of Al. In addition to explosion heat, density of this mixtures are increasing to depending on Al. The stability of propellant wasn't changed in the and of investigation. Furthermore, mechanical properties and shore hardness examined on the aluminised mixture specimens. The results are compared with the value of composite, double-base and CMDB propellant.