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Effect of addition of Cu on the properties of eutectic Sn-Bi solder alloy

Alam S. N., Jindal N., Naithani N.

Materials Science Poland

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2019

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Vol. 37, No. 2

212--224

EN

The present work reports the effect of Cu addition on the melting point, hardness and electrical resistivity of Sn-57 wt.% Bi eutectic solder alloy. Both binary eutectic Sn-57 wt.% Bi and ternary Sn-(57-x)Bi-xCu (x = 0.1, 0.3, 0.5, 0.7 and 1 wt.%) alloys containing various amounts of Cu were developed by melting casting route. The microstructure of the various solder alloys was analyzed using an optical microscope and a SEM. The variation in melting point, hardness and electrical resistivity of the Sn-Bi eutectic solder alloys with the addition of Cu was determined. The melting point of the eutectic Sn-Bi solder alloy was found to decrease up to the addition of 0.7 wt.% Cu. However, further addition of Cu led to an increase in the melting point of the alloy. Addition of Cu led to an increase in the hardness of the eutectic Sn-Bi solder alloy whereas the electrical resistivity of this alloy was found to increase up to the addition of 0.7 wt.% of Cu beyond which a decrease in the electrical resistivity was observed. A change in the microstructure of the solder alloy was observed when it was reheated above the melting temperature.

2

Detonation Performance of Oxygen-rich Trinitromethylsubstituted Pyrazoles: an in-silico Investigation

Naithani N., George B. K.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 4

537--533

EN

A new class of high energy molecules was designed and their detonation properties were evaluated using thermo-chemical parameters obtained from quantum chemical calculations at B3LYP/6-31G(d,p) level. The designed molecules exhibited high density, positive oxygen balance and excellent detonation properties. The impact sensitivity of these molecules, in terms of H50 values, was also evaluated from structural correlations. Among these, 3,4,5-tris(trinitromethyl)1H-pyrazol-1-amine (N13) showed the highest detonation pressure (40.67 GPa) and highest detonation velocity (9.17 km/s), though it exhibited high impact sensitive (H50 = 15 cm). Interestingly, 4,5-dinitro-3-(trinitromethyl)-1H-pyrazol-1-amine (N01) (detonation pressure 39.69 GPa; detonation velocity 9.23 km/s) was found to be an ideal high energy molecule with a near zero oxygen balance. The H50 value of N01 was predicted to be 64 cm, which is higher in magnitude, indicating a lower sensitivity than that of the conventionally used RDX (H50 = 26 cm).

3

Measurements of radon flux and soil-gas radon concentration along the main central thrust, Garhwal Himalaya, using SRM and RAD7 detectors

Bourai A., Aswal S., Rawat M., Prasad M., Naithani N., Joshi V., Ramola R.C.

Acta Geophysica

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2013

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Vol. 61, no. 4

950--957

EN

Radon in the Earth’s crust or soil matrix is free to move only if its atoms find their way into pores or capillaries of the matrix. 222Rn atoms from solid mineral grains get into air, filling pores through emanation process. Then 222Rn enters into the atmosphere from air-filled pores by exhalation process. The estimation of radon flux from soil surface is an important parameter for determining the source term for radon concentration modeling. In the present investigation, radon fluxes and soil-gas radon concentration have been measured along and around the Main Central Thrust (MCT) in Uttarkashi district of Garhwal Himalaya, India, by using Scintillation Radon Monitor (SRM) and RAD7 devices, respectively. The soil radon gas concentration measured by RAD7 with soil probe at the constant depth was found to vary from 12 ± 3 to 2330 ± 48 Bq m–3 with geometrical mean value of 302 ± 84 Bq m–3. The significance of this work is its usefulness from radiation protection point of view.