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1

Nickelization Effect on the High Temperature Tensile Properties of Mg-0.7Y2O3 Nanocomposite

Hassan S. F., Tun K. S., Patel F., Al-Aqeeli N., Gupta M.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1411--1415

EN

In this study, high performance magnesium-yttria nanocomposite’s room temperature, strength and ductility were significantly enhanced by the dispersion of nano-sized nickel particles using powder blending and a microwave sintering process. The strengthening effect of the dispersed nano-sized nickel particles was consistent up to 100°C and then it gradually diminished with further increases in the test temperature. The ductility of the magnesium-yttria nanocomposite remained unaffected by the dispersed nano-sized nickel particles up to 100°C. Impressively, it was enhanced at 150°C and above, leading to the possibility of the near net shape fabrication of the nanocomposite at a significantly low temperature.

2

A Study on Creep Behavior of Composite Solid Propellants Using the Kelvin-Voigt Model

Bihari B. K., Rao N. P. N., Gupta M., Murthy K. P. S.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

742--756

EN

A Kelvin-Voigt model consisting of a spring and a dashpot in parallel was applied for the viscoelastic characterization of solid rocket propellants. Suitable values of spring constants and damping coefficients were employed by a least squares fit of the errors to generate creep curves using a Dynamic Mechanical Analyzer (DMA) for composite solid propellants. Three different composite propellant formulations based on HTPB/AP/Al having burning rates of 5 mm/s, 15 mm/s and 20 mm/s were tested under different stress levels varying from 0.1 MPa to 3 MPa and at different temperatures varying from 35 °C to 85 °C. Creep behavior with recovery was studied and analyzed to evaluate the viscoelastic properties. The change in spring constants, representing elastic deformation, was very small compared to the damping coefficients for the propellants studied. For a typical propellant formulation, when the stress level was increased, the spring and damping coefficient both increased significantly whereas for an increase in temperature, they remained nearly constant. However, the ratio E/η was observed to be constant and independent of stress level. It was also observed that the variation of E and η varied linearly with increase in stress whereas their ratio showed a logarithmic variation. A mathematical correlation was developed to evaluate the viscoelastic properties during creep of composite propellants.

3

Integrated biostratigraphy of the Jurassic strata of the Wagad Uplift, Kachchh, western India

Rai J., Garg S., Gupta M., Singh A., Pandey D. K., Fürsich F. T., Alberti M., Garg R.

Volumina Jurassica

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2015

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Vol. 13, no. 2

55--80

EN

An integrated study based on calcareous nannofossils, organic-walled dinoflagellate cysts, and ammonites from the Washtawa and Kanthkot formations of the Wagad Uplift have allowed a detailed documentation of the stratigraphic position of these formations within the Oxfordian and Kimmeridgian sediments of the Kachchh Basin, western India. The nannofossil assemblages from the lower part of the Nara Shale Member exposed in the Nara and Washtawa domes, the Kanthkot Ammonite Beds along the Trambau River section, and the Patasar Shale Member exposed along the Trambau River section and the Patasar Tank section in the eastern part of the Wagad Uplift belong to the NJ 14 Cyclagelosphaera margerelli Zone of the Early Oxfordian, the NJ 15a Lotharingius sigillatus Zone of the Middle Oxfordian, and the NJ 15b Cretarhabdus conicus of Early Kimmeridgian age, respectively. Zonation schemes, based on calcareous nannofossils, dinoflagellate cysts, and ammonites were calibrated highlighting their biostratigraphic potential. These studies may represent a reference biochronology for Oxfordian–Kimmeridgian age strata applicable to the Tethyan realm of which India was a part during Late Jurassic times.

4

Studies on Aluminized, High Burning Rate, Butacene® Based, Composite Propellants

Ghosh K., Behera S., Kumar A., Padale B. G., Deshpande D. G., Kumar A., Gupta M.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 3

323--333

EN

This paper reports on a Butacene® based composite propellant with high burning rate. The effect of replacing HTPB with Butacene® on the physical, mechanical and ballistic properties, and sensitivity towards impact and friction, has been studied. The ballistic properties were evaluated as burning rates at various pressures (7-11 MPa), pressure exponents, ignition temperatures etc. As expected, a remarkable enhancement in burning rate at low pressures was observed with increasing percentage of Butacene®. Comparatively lower n-values were observed for compositions containing Butacene® than for HTPB based propellants. The sensitivity of Butacene® based compositions, in terms of impact and friction, was found to be increased with an increasing percentage of Butacene®.

5

Biuret: a Potential Burning Rate Suppressant in Ammonium Chlorate(VII) Based Composite Propellants

Dey A., Ghorpade V. G., Kumar A., Gupta M.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 1

3--13

EN

Several composite propellant compositions containing various concentrations of biuret, a new burning rate suppressant, were formulated and studied to optimize the concentration of biuret in the composite propellant. Biuret was used here for the first time in a composite propellant as a burning rate suppressant. The theoretical properties of the compositions containing different concentrations of biuret were computed by using the NASA CEC-71 programme and the burning rate performances were evaluated. In addition, the sensitivity, thermal and mechanical properties of the compositions were also evaluated. The composition containing ammonium chlorate(VII) (AP) 65%, Al 15%, binder 20% and biuret 0-6% over the batch were prepared. The composition containing 6% biuret over the batch was insensitive to friction and impact. As the amount of biuret was increased, the energy, burning rate and sensitivity decreased, whilst the auto ignition temperature increased. The formulation containing 4% biuret over the batch was found to be the optimum with respect to energy, burning rate, pressure index, and sensitivity.

6

Optimization of network forming agents for different types of composite propellant grain

Sangtyani R., Kumar A., Kumar A., Gupta M.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 3

409--417

EN

There has been a constant endeavour to improve the mechanical properties of hydroxyterminated polybutadiene (HTPB)-based, composite solid propellants. In order to have a better understanding of the requirements, a systematic study has been conducted on the effects of varying the network forming agents on the mechanical properties of nitramine based composite propellants. Under this scheme, a series of compositions was formulated using various chain extenders [1,6-hexanediol (HD) and 1,4-butanediol (BD)] and cross linkers [1,2,6-hexanetriol (HT) and trimethylolpropane (TMP)] in different proportions. Propellant formulation experiments were conducted wherein the network forming agent composition was systematically varied to achieve the maximum possible strain capability and moderately high tensile strength, keeping the weight % of the network forming agents and other ingredients constant. The mechanical properties (% elongation, tensile strength and elastic-modulus) of the finished propellant have been plotted vs. formulation number; this can be used to select a suitable network forming agent composition for a specified grain architecture and application. Network forming agents containing 1,2,6-hexanetriol provide a high elastic-modulus (120 kg/cm2) and a high tensile strength (~12 kg/cm2), which can be used in free standing grains. Network forming agents based on 1,6-hexanediol and 1,2,6-hexanetriol (in 1:1 proportion by weight) give high elongation (~50%) and a moderately high tensile strength (~9 kg/cm2), useful for case bonded propellant grains.