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Stabilized Superthermite Gelled Kerosene : towards Advanced Green Propellant Systems

Elbasuney Sherif, Ramzy Hesham, Maraden Ahmed, Attwa Mohamed

Central European Journal of Energetic Materials

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2024

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Vol. 21, no. 3

338--355

EN

Although hydrazine is the most common liquid propellant fuel, it is highly toxic and cancerogenic. Gelled hydrocarbons could be the greener substitute. Kerosene was gelled using fumed silica nanoparticles (NPs). Reactive metal particles can act as a high energy dense material (HEDM). With this aim, gelled kerosene was loaded with aluminum (Al) NPs. In combustion, SiO2/Al can induce vigorous exothermic superthermite reaction. Gelled kerosene demonstrated shear thinning behaviour, with high gel stability at 90 g centrifugal acceleration. The silica NPs could form a network via hydrogen bonding of Si‒OH groups; this network could be broken down under a high shear rate. Aluminized gelled kerosene formulation (8 wt.% SiO2 + 8 wt.% Al) preserves the shear thinning behaviour, i.e. it reached the viscosity of liquid kerosene at a shear rate below 25000 S‒1. This value lies within the range of pumping systems in rocket engines. Metallized gelled formulations demonstrated yield stress that is required to avoid phase separation and sedimentation during storage. Stabilised superthermite NPs not only offered enhanced characteristic exhaust velocity by 6% using the ICT thermodynamic code. Furthermore, they could induce vigorous exothermic superthermite reactions.

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Explosively Formed Penetrators Inflight Heating Compared to Hemispherical Copper Shaped Charge Jet

Abdelkhalek Sherif M., Abdelhafiz Mahmoud, Ismael Shukri, Elbasuney Sherif, Elshenawy Tamer

Central European Journal of Energetic Materials

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2024

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Vol. 21, no. 2

188--209

EN

Performance of shaped charges jet and explosive formed penetrators (EFP) can be tailored based on initial liner design and geometry. In addition, the jet temperature gradients during liner collapse and jet stretching mechanisms are different in both cases; the EFP and the traditional jet due to the different strain rates caused by the velocity gradient. In the current research work, oxygen free high conductivity copper (OFHC) was employed with two different liner geoemtries including hemispherical and dish-shaped liners of 2 mm thickness and 33 mm charge diameter. Autodyn numerical modeling was employed to study the impact of liner geometry on the characteristics of produced jet. Moreover, the jet heating mechanisms have been investigated numerically; the ratio between the collapse heating temperature to the plastic deformation temperature was found to be 1.61 and 0.43 for the dish-shaped and hemispherical jet respectively. This finding means that the jet heating due to stretching is not predominant one in both EFP and jet as it has already been confirmed in the papers published so far. Furthermore, EFP and jet penetration performances were assessed by the static firing against 4340 steel targets; while dish-shaped demonstrated shallow but enhanced wide crater at large standoff distance (D), i.e. 30D. Hemispherical jet has achieved large penetration depth with small crater diameter at small standoff distance, i.e. 4D.

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Novel Composite Solid Propellant with High Resistance to Thermo-oxidative Degradation Reactions, Extended Shelf Life, and Superior Combustion Characteristics

Elbasuney Sherif, Elsaka Eslam, Elbeih Ahmed, Mostafa Hosam E.

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 1

143--158

EN

Hydroxy-terminated polybutadiene (HTPB) pre-polymer is the main constituent that is responsible for conferring high mechanical properties on composite solid propellants. However, HTPB pre-polymer suffers from oxidative degradation reactions that diminish its mechanical properties and shelf life. Composite solid propellant formulations based on an advanced stabilizing agent (anti-oxidant), Flexzone 6-H, with different curing ratios, 0.7 and 1.1, were developed via mixing and casting under vacuum. The developed formulations were subjected to artificial ageing using Vant Hoff,s formula by isothermal heating at 80 °C for up to 35 days. The change in strain with ageing was evaluated using a uni-axial tensile test. The propellant formulation based on a curing ratio of 0.7 demonstrated a high ageing resistance coefficient and an extended service life of up to 15 years, compared with 5 years for higher curing ratio. A propellant grain is considered to be ‘aged out’ at 30% reduction in its maximum strain value. The propellant formulation based on the 0.7 curing ratio exhibited superior thermal stability as it offered a minimum decrease in heat released after ageing using DSC. Additionally, the 0.7 curing ratio formulations exhibited a minimum change in burning rate and pressure exponent with ageing time. It can be concluded that the propellant with 0.7 curing ratio can maintain its mechanical, thermal, and ballistic properties with ageing.

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Hemispherical Zirconium Liner for Advanced Shaped Charge with Enhanced Behind Armour Effect

Elshenawy Tamer Abd Elazim, Elbasuney Sherif

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 3

293--321

EN

Armour penetration is an essential outcome for shaped charges, especially when the behind-armour effect is considered. Hemispherical liners produce superior jet mass compared with those of traditional conical shape. In this paper two different materials have been studied as hemispherical shaped charge liners. The reference liner was hemispherical oxygen-free high-conductivity copper (OFHC); the other liner material was zirconium. These liners were experimentally tested against 4340 steel targets in shaped charges loaded with the same amount of Composition B explosive. Zirconium liners were found to offer superior performance with experimental penetration and crater diameter respectively 16% and 20% greater than OFHC. Ansys Autodyn hydrocode simulation results demonstrated that both liners produced superior jet masses exceeding 50% of the total liner mass. Moreover, zirconium had a jet tip velocity of 4869 m/s compared with 3886 m/s for OFHC. Additionally, zirconium had a superior average jet collapse to plastic deformation temperature ratio of 0.73 compared with 0.34 for OFHC. This is the first time the relation between the jet temperature during collapse and jet stretching has been reported.