Volume

Volume 56 - Year :2006

(101)

Issue 3-July 2006- Spl. Issue on High Energy Materials

(18)

	Guest Editorial Author : Agrawal, J.P. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp Subject : Keywords : Abstract :
	Back Cover Author : Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp Subject : Keywords : Abstract :
	Contents Author : Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp Subject : Keywords : Abstract :
	Front Cover Author : Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp Subject : Keywords : Abstract :
	Ethylene-propylene Diene Rubber as a Futuristic Elastomer for Insulation of Solid Rocket Motors Author : Bhuvaneswari, C.M. ;Sureshkumar, M.S.;Kakade, S.D.;Gupta, Manoj Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 309-320 Subject : 623.4 Armaments and Ballistics;662.3 Propellants;629.76 Rockets and Missiles Keywords : Solid rocket motors;Insulation;Ethylene-propylene diene rubber;Ablation resistance;EPDM;Case-bonded solid rocket motors Abstract : The study carried out so far on the application of ethylene-propylene diene rubber (EPDM) in the field of insulation of case bonded solid rocket motors has been reviewed. The various studies by the authors (unpublished work) have also been reported. All these findings bring out the excellent potential of EPDM as insulator in view of its ageing resistance, low-temperature flexibility, low erosion rate, and low specific gravity.
	Effect of Fuel Properties on the Specific Thrust of a Ramjet Engine Author : Gany, Alon Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 321-328 Subject : 621.1 Engines;629.7 Aeronautics;629.76 Rockets and Missiles Keywords : Ramjet engine;Specific thrust;Specific impulse;Ramjet propulsion;Fuel-air ratio;Specific heat release;Fuels;Fuel efficiency;Fuel rich propellant Abstract : Various aspects of specific thrust in ramjet propulsion have been considered. It is shown that while the peak specific impulse of ideal ramjet is theoretically obtained for fuel/air ratio f 0, the specific thrust which determines the thrust level of a given engine at certain operating conditions, increases with increasing fuel/air ratio up to (approximately) the stoichiometric ratio. Furthermore, in general, the specific thrust is related to the heat release per unit mass of air fqR, where the theoretical maximum is approximately proportional to its square root in stoichiometric conditions, fstqR. This can be the basis for selecting an appropriate fuel according to its potential specific thrust. It should be noted that certain metals such as magnesium, aluminum, and zirconium can provide about three-times higher specific heat release than hydrocarbons or hydrogen. Thus, these may be the better candidates for missions requiring high specific thrusts.
	Addition of RDX/HMX on the Ignition Behaviour of Boron-Potassium Nitrate Pyrotechnic Charge Author : Rani Krishnan, K.R. ;Anandavally Ammal, R. ;Hariharanath, B. ;Rajendran, A.G.;Kartha, C.B. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 329-338 Subject : 620.261 Explosives Keywords : Pyrotechnic compostion;Boron potassium nitrate;Thermal decomposition;Ignition behaviour;Pyrotechnic change;RDX;HMX;Fuel-oxidiser mixture Abstract : Boron-potassium nitrate (B-KNO3) (25/75) is a well-known pyrotechnic composition which finds application as energy-release system for small-calibre rockets and pyrogen igniters for larger motors. The decomposition of the oxidiser in this composition is endothermic which can be activated by the addition of high explosives, which decompose exothermically. This paper describes the influence of two nitramine explosives, RDX and HMX, on the ignition characteristics of B-KNO3 composition using thermogravimetry, differential scanning calorimetry, heat and pressure output measurements. Different compositions were prepared by varying the amount of RDX/HMX from 10 per cent to 50 per cent. Thermal studies on the B-KNO3/high explosive mixtures reveal that these undergo two-stage decomposition. The first stage corresponds to the decomposition of high explosive and the second stage corresponds to that of the reaction between B and KNO3. Kinetic parameters were calculated for both the stages of TG curves using Coats- Redfern and Mac Callum-Tanner methods. Ignition temperature of B-KNO3 decreases on the addition of RDX/HMX while the onset of RDX or HMX decomposition is not significantly affected by B-KNO3. The pressure output of B-KNO3 increases on adding RDX/HMX. The heat output of B-KNO3 is not much affected by the addition of RDX or HMX, even though the heat of explosion of RDX and HMX are low. This is due to the reaction between the combustion products of RDX/HMX and reaction products of B-KNO3 to form more exothermic products like B2O3, releasing extra heat. The flame temperature of the charge increases while the average molecular weight of the products of combustion decreases as the RDX/HMX content increases. Thus, the charge, on addition of RDX or HMX, produces higher pressure output, maintaining the heat output at comparable levels.
	Luminous Efficient Compositions Based on Epoxy Resin Author : Palaiah, R.S. ;Joshi, P.H.;Deo, S.S.;Jawale, D.K. ;Valiv, M.H.;Somayajulu, M.R. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 339-343 Subject : 665 Resins Keywords : Epoxy resins;Luminous efficiency;Compositions;Polyster-based compositions;Magnesium nitrate;Sodium nitrate Abstract : Magnesium/sodium nitrate illuminating compositions with epoxy resin - E 605 have been studied for luminosity and luminous efficiency by varying fuel oxidizer ratio and binder content. The compositions have been evaluated for impact and friction sensitivities, burn rate, thermal characteristics, and mechanical properties. Flame temperature and combustion products are evaluated theoretically by using REAL program. Experimental results show that, luminosity, burn rate, and calorimetric value are higher for polyester resin-based compositions. The high luminous efficiency composition is achieved with magnesium/sodium nitrate ratio of 70/30 with 4 per cent epoxy resin.
	Influence of Cellulosic Binders on Sensitivity and Combustion Behaviour of B-KNO3 Ignition System Author : Bhingarkar, Varsha ;Singh, Haridwar Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 345-351 Subject : 620.261 Explosives Keywords : Ballistic properties;Cal-Val;Thermal analysis;Sensitivity;Binders;Ignition system;Solid rocket propellants;Rocket propellants;Nitrocellulose;Cellulogic binders;Combustion behaviour Abstract : Boron-potassium nitrate (B-KNO3)-based compositions have been used as an effective igniter system for solid rocket propellants. A systematic study was undertaken to generate exhaustive data on B-KNO3 (25:65)-based ignition systems with cellulosic binders, viz., nitrocellulose, ethyl cellulose and plasticised ethyl cellulose. In addition, detailed investigations were carried out with PEC as binder by varying its concentration from 2-10 per cent in the same system. The experimental compositions (B-KNO3: binder) were evaluated by closed-vessel firing, thermal analysis, sensitivity, mechanical properties and cal-val determination. The binders significantly influenced the sensitivity and combustion behaviour of B-KNO3 compositions. The composition with nitrocellulose as binder produced high flame temperature and cal-val as compared to ethyl cellulose and plasticised ethyl cellulose-based compositions. The data indicated that the calculated flame temperature for all compositions was in the range 2716 K to 2957 K. As the plasticised ethyl cellulose content increased from 2 per cent to 10 per cent, the maximum pressure increased with decrease in heat of combustion.
	Burn-rate Measurement on Small-scale Rocket Motors Author : Maggi, F. ;Bandera, A;DeLuca, L. T. ;Subith, V.S. ;Annovazzi, A. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 353-367 Subject : 623.5 Armaments and Ballistics;629.76 Rockets and Missiles ;662.3 Propellants Keywords : Burn-rate measurement;Rocket motors;Small-scale rocket motors;Data reduction ;Ballistic behaviour;Ballistics Abstract : Small-scale rocket motors are widely used by propulsion industries to carry out burn rate measurement for a variety of needs. Several automated data-reduction procedures have been implemented to derive burn rate from pressure-time profiles resulting from experimentation. Even if these are easy and fast to use, these procedures are not completely reliable in that these measure only the average behaviour of a motor. A new model has recently been proposed to overcome this problem. However, it was soon noticed that the results depend on the propellant grain production and forming processes even if the motor hardware is the same. A series of propellant grains has been produced to be sampled to map the local ballistic behaviour and changes introduced by the manufacturing process. In this study, sampling and testing procedures are reported and the results of an almost complete grain mapping are discussed.
	Smoke Composition to Disseminate Capsaicinoids in Atmosphere as Sensory Irritant Author : Kulkarni,M. P.;Phapale,U.G.;Swarge,N.G.;Somayajulu, M.R. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 369-375 Subject : 623.459 Chemical Weapons;623.459 War Gases Keywords : Red pepper ;Oleoresin;Ortho benzylidene melanonitrile;1- chloroacetophenone;Tear gas;Dibenz (b, f)-1,4 oxazepine;Lactose-KClO3;Capsaicinoids Abstract : Dissemination of sensory irritants in the atmosphere with the help of an evaporating mixture is adopted. Experiments were carried out to find an alternative sensory irritant which is more irritating and less toxic than the existing sensory irritating agents and originating from a natural source. Extract of red pepper, the oleoresin, is less toxic than the existing sensory irritants and is analysed for its constituents. Thermal studies of capsaicin and the composition indicate that the composition ignites at 190 °C whereas capsaicinoids boil at 214 °C. Lactose-KClO3 reaction was found to release sufficient thermal energy to evaporate capsaicinoids into the atmosphere without degeneration. The compositions are both friction and impact insensitive. The dissemination of capsaicinoids into the atmosphere was confirmed using HPLC technique.
	Radiometric Screening of Red Phosphorus Smoke for its Obscuration Characteristics Author : Gautam,G.K.;Joshi,A.D.;Joshi,S.A.;Arya,P.R.;Somayajulu, M.R. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 377-381 Subject : 623.459 Chemical Weapons;623.459 War Gases Keywords : Smoke screen;Pyrotechnic compositions;Red phosphorus;Obscuration characteristics;Radiometric screening Abstract : Red phosphorus and potassium nitrate-based compositions exhibit favorable smoke screen formation with high obscuration characteristics at low oxidiser content. The rapid vaporisation of excess red phosphorus at higher flame temperature leads to quick aerodispersion. The obscuration characteristics are due to formation of P2O5 and subsequent reaction with moisture/ humidity in the atmosphere. Obscuration increases with increasing humidity. Extinction coefficient, the shadow cast per unit mass of the composition, is higher in visible and comparatively lower in far infrared.
	Detonator using Nickel Hydrazine Nitrate as Primary Explosive Author : Hariharanath,B.;Chandrabhanu,K.S.;Rajendran,A.G.;Ravindran,M.;Kartha,C.B. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 383-389 Subject : 620.261 Explosives Keywords : Detonator;Nickel hydrazine nitrate;Primary explosive;Deflagration-to-detonation transition;Squib Abstract : Nickel hydrazine nitrate is an energetic coordination compound having explosive properties in between that of primary and secondary. This compound was used to develop a new type of detonator by replacing the sensitive primary explosive, lead azide in conventional detonators and keeping RDX (cyclotrimethylenetrinitramine) as the output secondary explosive. The detonator consists of three regions, viz., initiation, deflagration-to-detonation transition (DDT), and output. The initiation and the electrical rating of 1A/1W no-fire were achieved using a suitable squib. The DDT and the output were taken care of, by pressing requisite quantities of Nickel hydrazine nitrate and RDX, respectively at required densities in a stainless steel stem channel. The detonator assembly involves crimping the squib and the stem channel in a stainless steel housing and applying a suitable resin at the crimped-end for leak tightness. The output was assessed from the dent depth on aluminium plate, volume expansion on lead block, and by achieving veloctiy of detonation of 8200 m/s in mild detonating cords, containing 0.95 g/m of RDX, which indicates full-order detonation. The detonators were tested at system level and found to perform satisfactorily.
	Transition Metal Carbohydrazide Nitrates: Burn-rate Modifiers for Propellants Author : Sonawane,S.H.;Gore,G.M.;Polke,B.G.;Nazare,A.N.;Asthana,S.N. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 391-398 Subject : 662.3 Propellants Keywords : Burn rate modifier;Carbohydrazide complexes;Propellants;Double-base propellants;Thermal stability;Composite propellants;Ligand fuel Abstract : This paper discusses the synthesis and characterisation of cobalt (Co), nickel (Ni) and copper (Cu) carbohydrazide nitrates. In differential scanning calorimetry (DSC), the complexes exhibited exothermic decomposition indicating their energetic nature. The commencement of decomposition was observed at 220 °C for Ni complex, and at 160 °C for Co complex whereas that of Cu complex occurred at 75 °C. In view of the better thermal stability, Ni and Co complexes were selected for further study. The activation energy of decomposition of Ni and Co complexes were found to be 47 kcal/mol and 60 kcal/mol respectively. Impact and friction sensitivity test results revealed relatively lower vulnerability of carbohydrazide cobalt nitrate. Its incorporation in an ammonium perchlorate (AP)-based composite propellant led to 9-19 per cent enhancement whereas that of carbohydrazide nickel nitrate resulted in 28-74 per cent enhancement in burning rates in the pressure range 1.9 MPa to 8.8 MPa. Exothermic decomposition of the coordination complexes on propellant surface and involvement of metal at molecular level formed on decomposition of the complexes in combustion environment of composite propellant may be attributed to the catalytic effect of this class of compounds on the lines of reported literature.
	Synthesis and Characterisation of Bis-(chloromethyl) Oxetane, its Homopolymer and Copolymer with Tetrahydrofuran Author : Reddy, T.S.;Jayakumar, K.K.;Nair, J.K.;Satpute, R.S.;Mukundan, T. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 399-406 Subject : 662.3 Propellants;662.1 Pyrotechnics;620.261 Explosives Keywords : Poly-BCMO;BCMO–THF copolymer;HTPB;Flame retardant;Limiting oxygen index;Filler;Tetrahydrofuran copolymer;Energetic binders;Propellant binders;Energetic polymers;Bis- (chloromethyl) oxetane;Thermoplastic elastomers Abstract : Bis-(chloromethyl) oxetane (BCMO) was synthesised from pentaerythritol by chlorination, followed by ring closure. It was polymerised using BF3-etherate and butanediol system, similarly the BCMO–THF (tetrahydrofuran) copolymer was also synthesised. The monomers and the polymers were characterised by IR, 1H-NMR and molecular weight. Flame retardant properties of the poly-BCMO were also investigated.
	Glycidyl Azide Polymer-based Enhanced Energy LOVA Gun Propellant Author : Sanghavi, R.R.;Kamale, P.J.;Shaikh, M.A.R.;Chakraborthy, T.K.;Asthana, S.N.;Singh, Amarjit Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 407-416 Subject : 662.3 Propellants Keywords : Low vulnerable ammunition;LOVA;Glycidyl azide polymer;GAP;Gun propellant;Triacetin;Cellulose acetate;Energetic plasticiser;Force constant;Combustion characteristics;HFCI;Hot fragment conductive ignition Abstract : In this study, cyclotrimethylene trinitramine propellants with triacetin (TA)-plasticised cellulose acetate (CA) and nitrocellulose (NC) combination as binders were evaluated for low vulnerable ammunition (LOVA). Triacetin was replaced by energetic plasticiser; glycidyl azide polymer (GAP) in increments to enhance the performance in terms of force constant . In addition to ballistics, parameters like vulnerability, mechanical and thermal properties of GAP-based propellants in comparison to those of TA-based propellants, were also determined. The study brings out that the incorporation of 2-6 per cent GAP in place of TA resulted in the enhancement of force constant by 22-70 J/g and improved overall combustion characteristics. DSC revealed that thermal decomposition of GAP-LOVA propellants evolved more energy than TA-LOVA propellants. GAP-based LOVA propellant similar to TA-plasticised LOVA propellant, was found superior to NQ propellant in vulnerability tests as well as in hot fragment conductive ignition (HFCI) studies. As regards mechanical properties, incorporation of GAP resulted in improved compression strength.
	Prediction of Maximum Strain in Finocyl Port Case-bonded Solid Propellants under Pressure Loading Author : Shekhar, Himanshu Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 417-422 Subject : 662.3 Propellants Keywords : Case-bonded solid propellants;Solid propellants;Finite element analysis;Finocyl port propellant configuration;Propulsion unit;Propellant port;Port pressurisation Abstract : Finite element analysis of case-bonded solid propellants in finocyl port configuration has been carried out using finite element method. The parametric studies have also been conducted for loading conditions, material properties, and geometrical configurations. The results are presented in the form of a universal power law, which can be utilised for primary assessment of peak strain in any finocyl port propellant configuration without using finite element software. This eliminates dependence on finite element software for structural integrity analysis of solid propellants in finocyl port configuration under port pressurisation. The results obtained by finite element analysis and power law are in close agreement.
	Prediction of Particle Size of Ammonium Perchlorate during Pulverisation Author : Jain, Sunil;Mulay, M.P.;Mehilal;Singh, P.P.;Bhattacharya, B. Source : Defence Science Journal ; Vol:56(3) ; 2006 ; pp 423-431 Subject : 662.3 Propellants Keywords : Ammonium perchlorate;Grinding;Air classifier mill;Composite propellant;Average particle size;Modelling equation;Burn rate Abstract : Ammonium perchlorate has been pulverised by an impact mill (air classifier mill) to study the influence of different operating parameters, viz., effect of mill speed, classifier speed, feed rate, and damper opening (suction rate) on the particle size. Further based on the different grinding parameters, an empirical equation has been developed and used for the prediction of particle size. The experimental results indicate that the values are very close to the predicted ones. In addition, particle size distribution has also been studied by applying different model equations and it has been found that Rosin-Rammler model is the most suitable model for this operation.