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Corrosion of Inconel 690 in N2-0.1%H2S Gas at 700-800 °C
Poonam Yadav,이동복 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.5
Inconel 690 superalloy was corroded at 700 °C and 800 °C for up to 70 h in N2-0.1% H2S gas. It corroded almostlinearly with large weight gains, displaying little protectiveness. Its corrosion rates were quite fast when comparedwith its corrosion in air or Ar-1%SO2 gas. The formed scales were thick, fragile, and nonadherent. They consistedprimarily of Cr2O3 with some NiCr2O4, Ni3S2, CrS, and Cr2S3. The H2S gas accelerated the corrosion significantlyby forming nonprotective sulfides and dissolving hydrogen in the scale and in the internal corrosion zone that consistedof discrete chromium-sulfides and some oxide particles. The marker test indicated that the scales grew by theoutward diffusion of metallic ions such as Ni, Cr, Fe, and Mn, whilst the internal corrosion zone thickened by theinward migration of oxygen and sulfur through the lattice, grain boundaries, and microcracks.
Dispersion and Degradation of Polycarbonate/MWCNT Nanocomposites with Melt Extrusion
Yadav, Poonam,Lee, Dong Bok Trans Tech Publications, Ltd. 2014 Advanced materials research Vol.1044 No.-
<P>Polycarbonate/Multi-wall Carbon Nanotubes (PC/MWCNT) nanocomposites with 0.55% and 0.77% of MWCNT were prepared by twin-screw compounding extruder. The morphology and dispersion were characterized by SEM. The Raman analysis confirmed the good interaction between carbon nanotubes (CNTs) and Polycarbonate (PC). The TGA result showed that the PC/MWCNT nanocomposites degraded in two time extrusion (TTE) as compared to one time extrusion (OTE), which was attributed to the temperature effect. Inspite of degradation, TTE nanocomposite showed good dispersion of MWCNT in PC.</P>
High-Temperature Corrosion of NiCrAlY/YSZ Coatings in Ar-1%SO<sub>2</sub> Gas
Yadav, Poonam,Abro, Muhammad Ali,Lee, Dong Bok Trans Tech Publications, Ltd. 2016 Materials science forum Vol.844 No.-
<P>The thermal barrier coating that consisted of ZrO2-8Y2O3 top-coat and Ni-22Cr-10Al-1Y bond-coat corroded in Ar-1%SO2 gas at 1000-1200°C for up to 300 h. The top-coat and bond-coat consisted primarily of β-ZrO2 and (γ-Ni, α-Al2O3), respectively. During corrosion, Al oxidized preferentially to α-Al2O3 to protect TBC, and sulfidation occurred to a small extent.</P>
High-temperature Corrosion of AlCrTiSiN Film in Ar-1%SO2 Gas
Poonam Yadav,권식철,Yue Lin,Shihong Zhang,이동복 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.4
An AlCrTiSiN film composed of 31Al-15Cr-1.7Ti-0.5Si-51.8N (at%) was deposited on a steel substrate by arc ion plating to a thickness of 1 μm. It consisted of nano crystalline hcp-AlN and fcc-CrN. Its corrosion behavior in Ar-1%SO2 gas at 800 ℃ for 5-50 h was studied. The resulting scales consisted primarily of Al2O3 and Cr2O3, which effectively suppressed the corrosion. No sulfides formed, because Al and Cr oxidized competitively from the surface. The film was primarily corroded by the inward diffusion of oxygen and a much smaller amount of sulfur.
Poonam Parashar,Naresh Diwaker,Jovita Kanoujia,Mahendra Singh,Abhishek Yadav,Indu Singh,Shubhini A. Saraf 한국약제학회 2020 Journal of Pharmaceutical Investigation Vol.50 No.1
Purpose Treatment of epilepsy faces immense challenge and often fails due to pharmaco-resistance and incapability of antiepileptic drug to cross the blood brain barrier (BBB). This problem demands an alternate, newer effective delivery approach. The intranasal drug delivery has emerged as a preferential route because of its ability to deliver drug directly to brain, facilitated through unique anatomy of the nasal cavity. The purpose of present study was to formulate and characterize in situ gel of lamotrigine (LGT) for delivery via nasal route. Methods The in situ gel was prepared using cold method utilizing sodium alginate, chitosan and methyl cellulose. The in vitro characterization of gel was performed for pH, gelation, drug content, viscosity, gel strength, in vitro release, and mucoadhesive strength. Results The clear in situ gel consisting of sodium alginate (0.05% w/v) and chitosan (0.25% w/v), showed 76.05% drug release in 8 h with pH 5.30 ± 0.07, drug content 94.93% and gel strength 46.00 ± 2.00 s. Further, the optimized (IG8) formulation was subjected for ex vivo permeation study and histopathological analysis. The amount of LGT in brain and plasma was determined pharmacokinetically in rat model. An enhanced brain concentration (200% approximately) of LGT was achieved (AUC last 9.33 ± 2.54 μg h/mL, Cmax 1.41 ± 0.15 μg/mL) in case of in situ gel when compared with oral drug suspension (AUC last 4.78 ± 1.98 mcg h/mL, Cmax 0.84 ± 0.28 μg/mL). Conclusion In situ gel of LGT via intranasal route can be taken as a viable alternative to the conventional antiepileptic drug delivery.