فصلنامه مواد پر انرژی
سال هفتم شماره 2 (پیاپی 15، تابستان 1391)

Experimental tests were carried out to explosively clad solution annealed Inconel 718 super alloy on quench-tempered AISI H13 hot tool steel. The tests were carried out using various stand-off distances and explosive ratios. Various interface geometries were obtained from these experiments. In this paper, all the experiments were simulated using ABAQUS version 6.9 finite element software. Experiments were carried out with Ammatol explosive mixture. The integrity of the bond interface was examined by shear test. The micro hardness profiles at the interface for all samples were performed. Metallographic inspections of the bond interfaces were also carried out. Numerical results showed that high localized plastic deformation was produced at the bond interface. The shape of interface fell roughly into two classes, wavy or wavy with some vortex shedding. In some case, a gradual change in wavelength along the direction of welding was observed which was due to a change in impact angle following plate contacts. Hardness was increased at the interface. The increase of hardness near the interface was more pronounced in super alloy than in steel. Shear strength was found to be functions of interface morphology and wave amplitude. Kinetic energy loss could be criteria for transition of interface morphology. Welding window of alloys was also developed.

Uses of antioxidants in composite propellants formulation is unavoidable. These materials are added to propellants to afford stability during storage time. In this paper, synthesis of 2-t-butyl p-cresol intermediate for the preparation of A.O.2246 using Bronsted acidic ionic liquids as catalyst and solvent were investigated. Methyl-tert-butyl ether was used for tert butylation of para cresol and variable reaction parameters such as temperature, mole ratio, type and catalyst composition and time were optimized. Tert butylation of p-cresol gives two products, 2-tert-butyl p-cresol and 2,6-di-tert-butyl p-cresol. Among ionic liquids, triphenyl(butyl-4-sulphonyl) phosphonium sulfonate, irrespective of the alkylating agent, is the most active catalyst. In the presence of triphenyl(butyl-4-sulphonyl) phosphonium sulfonate, 2-t-butyl p-cresol was the main product of reaction with 91.7% of selectivity and 73.2% of p-cresol conversion.

Ammonium perchlorate is one of the most important oxidants being used in the production of composite solid propellant whose shape and particle size have a great impact on its characteristics. In this research, in order to produce the nano-particles, the micro-emulsion of ammonium perchlorate salt in the presence of active surfactant materials has been produced and frozen in the liquid nitrogen before finally turned in the nano-particles using the freeze drying technique. The experiment results show that the parameters such as the emulsion stability, the type of active surfactant material, co-activator, type of oil, the mass ratio of the components in the emulsion, mixing rate, freezing method, and the temperature have a great influence on the particles’ shape and size. Having considered and examined all the above mentioned parameters, the nano-particles with the average diameter of 40-150 nm with spherical shape have been finally produced.

In this paper, a fault in the main duct of oxidizer in liquid rocket engine has been simulated. The procedure is based on a nonlinear mathematical model that dynamically describes sound operation of engine. In other word, when engine operates abnormally during a fault, fault descriptive equations are added to the engine equations. Differential equation system involves linear and nonlinear equations that describe sound and fault operation of engine. This system consists of 34 algebraic and 59 differential equations. The fourth order Runge-Kutta method has been used for numerical solution of equations set. Finally, results of engine hot test are compared with model and shows acceptable accuracy of simulator code.

Concentration of hydrogen peroxide from 35% to 98 wt% is performed via the methods such as vacuum distillation and cooling crystallization, but hydrogen peroxide with concentration of ≥90%, is very sensitive to impurities and may be decompose. Therefore, the solution should be quite pure before concentration process. Herein, separation of Magnesium (Mg) cation from the commercial hydrogen peroxide solution (35 wt%) by ion exchange method using strong acid cation resin Amberlite IR-120 H+ with styrene divinylbenzene copolymer matrix and sulfunic acid functional group is investigated. Effect of the amount of resin and contact time on the separation of cation is considered. The metal ion concentration in the original solution and the metal ions left unabsorbed were determined by Inductive Coupled Plasma Spectrometry technique. Experimental results obtained from the separation of Magnesium were compared with Freundlich, Langmuir and Jovanovic adsorption isothermal models. Results show that, these isotherm models only in a certain range of concentrations, are consistent with experimental results. Although, the Langmuir equation of adsorption isotherm gives the best results.

A variety of polymer such as: ethyl cellulose, Cellulose acetate, polyester and etc have been served widely in insulation of double-base solid propellant. Proper insulation of double base propellants should have features such as: 1- low absorption NG; 2- Without or low producion of smoke; 3- good adhesion of insulator to propellants surface; 4- with suitable vanished and thermal parameters and etc. In this paper polymer used in insulation of double base propellant are reviewed and their physical and chemical characteristic are investigated and compared. Then hydroxyl terminated poly dimethylsiloxane was synthesized and the effect of temperature, reaction time, ratio of raw material, type and intensity of agitation, type of catalyst, solvent and quenching reagents on molecular weight of poly dimethysiloxane was studied. Also a new method for one step synthesis of a hydroxyl terminated polydimethylsiloxane is presented.

The burning rate of single base propellant can be increased if they are used or stored in warm climates area. The use of inhibitors in this type of propellants, reduces the burning rate and finally the pressure and muzzle rate at high temperatures and improve the ballistic performance of propellant. Several inhibitors, e.g. camphor, dibutyl phthalate, cellulose or unsaturated organic esters compounds, have been used but preferred inhibitors are thermoplastics cellulose containing repeated units of the anhydroglucose. In this study, 1.5, 3, 7, 10, 12% wt of cellulose acetate butyrate (CAB) were deposited on the surface of single base propellant and then the ballistic performance (pressure and muzzle rate) have been evaluated.