Microstructure and Wear Resistance of an Arc-Sprayed Fe-Based Coating after Surface Kemelting Treatment

The aim of the study was to improve the lamellar structure and wear resistance of arc-sprayed coatings. FeNiCrAl arc-sprayed coatings were remelted by the tungsten inert gas welding method. The as-sprayed and remelted specimens were subjected to comparative structural phase composition examination using optical microscopy, scanning electron microscopy and X-ray diffraction. Additionally, the effect of the remelting treatment on the wear mechanism of the arc sprayed coatings was also studied. It was found from the experiments that the tungsten inert gas surface process has the potential to form pore- and crack-free coatings. Further investigations showed that the dominant mechanism of wear for the as-sprayed coatings was oxide delamination and for the tungsten inert gas remelted coatings was cutting and ploughingУсовершенствованы пластинчатая структура и износостойкость покрытий, полученных электродуговой металлизацией. С помощью дуговой сварки вольфрамовым электродом в среде инертного газа проведена переплавка покрытий на основе FeNiCrAl, полученных электро-дуговой металлизацией. С использованием методов оптической микроскопии, растровой электронной микроскопии и дифракции рентгеновских лучей осуществлено сравнительное исследование структуры и фазового состава напыленных и переплавленных покрытий. Изучено влияние обработки путем переплавки на механизм износа покрытий, полученных электро-дуговой металлизацией. Установлено, что реализация дуговой сварки вольфрамовым электродом в среде инертного газа позволяет разрабатывать покрытия без пор и трещин. Даль- нейшие исследования показали, что основной признак износа покрытий, полученных электро-дуговой металлизацией, – расщепление оксида, в то время как покрытий, переплавленных с помощью дуговой сварки вольфрамовым электродом в среде инертного газа, – резание и пропахивание.Удосконалено пластинчасту структуру та зносостійкість покриттів, отриманих електро-дуговою металізацією. За допомогою дугового зварювання вольфрамовим електро-дом у середовищі інертного газу проведено переплавку покриттів на основі FeNiCrAl, отриманих електродуговою металізацією. Із використанням методів оптичної мікроскопії, растрової електронної мікроскопії та дифракції рентгенівських променів проведено порівняльне дослідження структури і фазового складу напилених і переплавлених покриттів. Вивчено вплив обробки шляхом переплавки на механізм зношення покриттів, отриманих електродуговою металізацією. Установлено, що реалізація дугового зварювання вольфрамовим електродом у середовищі інертного газу дозволяє розробляти покриття без пор і тріщин. Подальші дослідження показали, що основними ознаками зношення покриттів, отриманих електродуговою металізацією, є розщеплення оксиду, в той час як покриттів, переплавлених за допомогою дугового зварювання вольфрамовим електродом у середовищі інертного газу, – різання і проорюванн

A peroxisome proliferator-activated receptor-δ agonist provides neuroprotection in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model of Parkinson's disease

Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.Peer reviewedPublisher PD

Phase separation and ferroelectric ordering in charge frustrated LuFe2O4-x

The transmission electron microscopy observations of the charge ordering (CO) which governs the electronic polarization in LuFe2O4-x clearly show the presence of a remarkable phase separation at low temperatures. Two CO ground states are found to adopt the charge modulations of Q1 = (1/3, 1/3, 0) and Q2 = (1/3 + y, 1/3 + y, 3/2), respectively. Our structural study demonstrates that the incommensurately Q2-modulated state is chiefly stable in samples with relatively lower oxygen contents. Data from theoretical simulations of the diffraction suggest that both Q1- and Q2-modulated phases have ferroelectric ordering. The effects of oxygen concentration on the phase separation and electric polarization in this layered system are discussed.Comment: 11 pages, 5 figure

Localization by disorder in the infrared conductivity of (Y,Pr)Ba2Cu3O7 films

The ab-plane reflectivity of (Y{1-x}Prx)Ba2Cu3O7 thin films was measured in the 30-30000 cm-1 range for samples with x = 0 (Tc = 90 K), x = 0.4 (Tc = 35 K) and x = 0.5 (Tc = 19 K) as a function of temperature in the normal state. The effective charge density obtained from the integrated spectral weight decreases with increasing x. The variation is consistent with the higher dc resistivity for x = 0.4, but is one order of magnitude smaller than what would be expected for x = 0.5. In the latter sample, the conductivity is dominated at all temperatures by a large localization peak. Its magnitude increases as the temperature decreases. We relate this peak to the dc resistivity enhancement. A simple localization-by-disorder model accounts for the optical conductivity of the x = 0.5 sample.Comment: 7 pages with (4) figures include

Density functional method for nonequilibrium electron transport

We describe an ab initio method for calculating the electronic structure, electronic transport, and forces acting on the atoms, for atomic scale systems connected to semi-infinite electrodes and with an applied voltage bias. Our method is based on the density functional theory (DFT) as implemented in the well tested Siesta approach (which uses non-local norm-conserving pseudopotentials to describe the effect of the core electrons, and linear combination of finite-range numerical atomic orbitals to describe the valence states). We fully deal with the atomistic structure of the whole system, treating both the contact and the electrodes on the same footing. The effect of the finite bias (including selfconsistency and the solution of the electrostatic problem) is taken into account using nonequilibrium Green's functions. We relate the nonequilibrium Green's function expressions to the more transparent scheme involving the scattering states. As an illustration, the method is applied to three systems where we are able to compare our results to earlier ab initio DFT calculations or experiments, and we point out differences between this method and existing schemes. The systems considered are: (1) single atom carbon wires connected to aluminum electrodes with extended or finite cross section, (2) single atom gold wires, and finally (3) large carbon nanotube systems with point defects.Comment: 18 pages, 23 figure

Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta

Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector, the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and (7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure

BESII Detector Simulation

A Monte Carlo program based on Geant3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM