Government College

About: Government College is a based out in . It is known for research contribution in the topics: Population & Ring (chemistry). The organization has 4481 authors who have published 5986 publications receiving 57398 citations.

Accelerated Hot Corrosion Studies of D-Gun-Sprayed Cr 2 O 3 –50% Al 2 O 3 Coating on Boiler Steel and Fe-Based Superalloy

Abstract: In the current investigation, Cr2O3–50% Al2O3 coating was deposited on ASTM-SA213-T-22 boiler steel and Fe-based superalloy Superfer 800H by D-gun spray process. The high-temperature corrosion performance of the coated as well as bare alloys was evaluated in Na2SO4–60%V2O5 molten salt, an aggressive environment at 900 °C under cyclic conditions. The kinetics of the corrosion were analyzed by the change in weight measurements which were taken after each cycle (i.e., 1-h heating in a tube furnace followed by 20-min cooling in ambient air) for a total period of 50 cycles. The X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray analysis techniques were used for the analysis of corrosion products. During investigations, it was found that both the selected bare alloys have suffered intensive spallation in the form of removal of their oxide scales, which may be attributed to the formation of non-protective Fe2O3-dominated oxide scales, whereas the coated alloys have shown lesser weight gains along with better adhesiveness of the oxide scales with the substrate till the end of the experiment. The oxides of chromium and aluminum were the main phases revealed in the oxide scales of the coated specimens, which are reported to be protective against the hot corrosion.

A new signature of the triaxial region in even nuclei

Abstract: The mechanisms by which atomic nuclei generate angular momentum of the γ-band are surface oscillations in the γ-soft structure or nuclear rotation in the γ-rigid structure. We propose that if the experimental γ-band energies are found to obey the formula E=(I(I+1)/J0(1+αI)), the nucleus may be said to belong to the γ-rigid triaxial region at low spin and low energy.

C-H functionalisation through carbene and fluorocarbene insertion : ab initio and DFT investigations

Abstract: The insertion reactions of singlet methylene and fluorocarbenes ( 1 CH2, 1 CHF and 1 CF2) into 1°, 2° and 3° non-polar C–H bonds of alkanes (methane, ethane, propane, n -butane, iso -butane, n -pentane and iso -pentane) have been investigated at ab initio(MP2) and DFT levels invoking 6-31g(d,p) basis set. Additionally, the 6-311++g (d, p) basis set has been used for DFT calculations only. The transition states formed during the σ and π insertions of fluorocarbenes into the alkane C–H have been investigated in this study. Transition states of σ approach in the potential energy surface have been located by complete optimization while those of π approach have been subjected to constrained relaxations. Both MP2 and DFT predict that the σ approach is slightly favored over the π approach. Wide variations in the barrier heights (∼2 to ∼10 kcal/mol for 1 CHF and ∼27 to ∼40 kcal/mol for 1 CF 2 at MP2; ∼1 to ∼7 kcal/mol for 1 CHF and ∼26 to ∼35 kcal/mol at B3LYP) have been observed for the insertions of fluorocarbenes investigated. For inverted σ approach of 1 CHF and 1 CF 2 , the barrier heights have been found to be ca. 2–5 times that of normal σ approach. In all these insertion reactions, the singlet–triplet energy gaps correlate positively with the barrier heights while neither HOMO/LUMO energies nor HOMO–LUMO energy gaps (HLEG) correlate.

Electron microprobe study of deposition and diffusion of tool material in electrical discharge machining

Abstract: Electron microprobe analysis for the surface deposition and diffusion of tool material was carried out on mild steel (MS), high-carbon steel (HCS) and high-speed steel (HSS) work samples, machined by an electrical discharge process using a relaxation circuit in distilled water and kerosene at 225 and 56·25 mJ pulse energy, with copper and brass as tools. It was observed that high-energy machining results in lower surface deposition but more depth of diffusion. MS-HCS-HSS showed increasing surface deposition but decreasing depth of diffusion in the same order. Machining in distilled water at high-pulse energy resulted in lower surface deposition and depth of diffusion as compared to machining in kerosene. At low-pulse energy kerosene showed similar results. Tool material was found to deposit preferentially along the crater rims. The possibility of a certain typical geometry of crater formation in multi-spark machining is concluded. It is felt that each large crater is a result of three to four small crater...