NOPR Collection:

Desulphurization study of Assam coking coal by sodium hydroxide leaching

1996-08-01T00:00:00Z

Title: Desulphurization study of Assam coking coal by sodium hydroxide leaching Authors: Kumar, M; Singh, A K; Singh, T N Abstract: Sulphur removal from Assam coking coal and its coke (made at 1300^o C) by caustic leaching at four different temperatures of 50, 85, 105 and 120^oC by varying soak periods from 30 to 180 min has been determined. Carbonization of Assam coking coal at 1300^oC considerable recued its sulphur content from 7.9 to 3.85%. The total sulphur removed increase with increasing leaching temperature and time. The first 30 min of leaching has been found to be the optimum leaching time for all the temperature. Coke offered more resistance to NaOH leaching for sulfur removal compared to coal. Page(s): 171-173

Boron-lined ion chambers for reactor applications

1996-08-01T00:00:00Z

Title: Boron-lined ion chambers for reactor applications Authors: Prasad, K R; Alex, Mary; Dighe, P M; Balagi, V Abstract: Ion chambers for reactor control and safety instrumentation have been indigenously developed. The chambers are used for on-line neutron flux measurement in reactor out-of-core location. The chambers have a rugged mechanical design with integral mineral insulated cable assembly capable of operating in hostile environment. The electrodes were coated with 350 mg of 92% enriched elemental boron-10 and the theoretically expected neutron sensitivity of 2.9 x 10^-14A/nv has been achieved. Tests on one of the chambers show good saturation at 1.o x 10⁸nv. If necessary, the chamber can be operated at neutron flux of the order of 1.0 x 10¹¹nv. Page(s): 167-170

ERMO Cluster calculations on hyperstoichiometric Laves phase alloys and hydrides

1996-08-01T00:00:00Z

Title: ERMO Cluster calculations on hyperstoichiometric Laves phase alloys and hydrides Authors: Babu, R S Achyuthlal; Viswanathan, B; Murthy, S Srinivasa Abstract: Extended Huckel molecular orbital (EHMO) cluster calculation has been performed on zirconium containing hyperstoichiometric ZrB_2+X (where B→3d transition metal atom) hydrogen storage alloys to examine the preferential position of B atoms corresponding to hyperstoichiometry. Binding energies of clusters indicate tetrahedral sites as the preferential site for occupation by excess B atoms. Among the available sites hydrogen prefers to occupy A₂B₂ sites with partial negative charge. Energy values-show the order of stability of the hydrides to be ZrV₂> ZrMn₂ > ZrCr₂. Page(s): 163-166

Phosphorus containing nadicimide oligomers: Synthesis and characterization

1996-08-01T00:00:00Z

Title: Phosphorus containing nadicimide oligomers: Synthesis and characterization Authors: Alama, Sarfaraz; Jayakumari, V G; Kandpala, L D; Varma, I K Abstract: The paper describes the synthesis and characterization of several nadicimide oligomers derived from tris [3-(4-aminobenzamido) phenyl] phosphine oxide (TABP), pyromellitic dianhydride (PMDA)/3,3',4,4'-benzophenone tracarboxylic acid dianhydride (BTDA). Structural characterization of the resins has been done by elemental analysis, IR and ¹H NMR spectroscopy Curing behaviour of these oligomers depends on the structure. Exothermic transitions due to curing have been observed in the temperature range of 250 ± 20 to 295 ± 25°C. Isothermal curing of the resins has been done at 340°C for 1h in air atmosphere. The cured resins are stable up to 300°C and decompose in a single step above this temperature. Page(s): 158-162