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Cost-effective integrated strategy for the fabrication of hard-magnet barium hexaferrite powders from low-grade barite ore

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International Journal of minerals,metallurgy and materials 2016年第9期23卷 991-1000页

作者： m.m.s.sanad m.m.Rashad Central metallurgical R & D Institute

Ultrafine barium hexaferrite（BaFe12O19） powders were synthesized from the metallurgical extracts of low-grade Egyptian barite ore via a co-precipitation route. Hydrometallurgical treatment of barite ore was systematically studied to achieve the maximum dissolution efficiency of Fe（～99.7%） under the optimum conditions. The hexaferrite precursors were obtained by the co-precipitation of Bas produced by the reduction of barite ore with carbon at 1273 K and then dissolved in diluted HCl and FeCl3 solution at pH 10 using NaOH as a base; the product was then annealed at 1273 K in an open atmosphere. The effect of Fe^3＋/Ba^2＋ molar ratio and the addition of hydrogen peroxide（H2O2） on the phase structure, crystallite size, morphology, and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. single-phase BaFe（12）O（19） powder was obtained at an Fe^3＋/Ba^2＋ molar ratio of 8.00. The formed powders exhibited a hexagonal platelet-like structure. Good maximum magnetization（48.3 A×m^2×kg^–1） was achieved in the material prepared at an Fe^3＋/Ba^2＋ molar ratio of 8.0 in the presence of 5% H2O2 as an oxidizer and at 1273 K because of the formation of a uniform, hexagonal-shaped structure.

关键词： chemical process barite ore treatment characterization magnetic properties ferrites

Catalytic effect of srTiO_3 on the hydrogen storage behaviour of mgH_2

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Journal of Energy Chemistry 2019年第1期28卷 46-53页

作者： m.s.Yahya m.Ismail school of Ocean Engineering University Malaysia Terengganu

The effects of sr TiO_3 on the hydrogen storage properties of mgH_2 have been studied for the first *** onset dehydrogenation temperature of the mgH_2-10 wt% srTiO_3 is found to be 275 ℃, which is 55 ℃ lower as compared to the as-milled mgH_2. The composite is able to absorb 4.3 wt% of hydrogen in 60 min instead of 1.1 wt% for the as-milled mg H_2. meanwhile, the composite is able to release 5.3 wt% of hydrogen in 17 min compared to 1.9 wt% by the as-milled mg H_2 at 320 ℃. The calculated Eaof the mg H_2-10 wt% srTiO_3 is 109 k J/mol, which is 26.3 kJ/mol lower than the calculated Eaof the as-milled mgH_2. The sr TiO_3 is not decomposed during the ball milling and the re/dehydrogenation processes. The catalytic effect shown by the srTiO_3 is owing to its ability to change the physical structure of the mgH_2 particles during the ball milling process.

关键词： Hydrogen storage magnesium hydride Catalytic effect sorption properties

Effects of Zr substitution on structural,morphological,and magnetic properties of bismuth iron oxide phases

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Chinese Physics B 2017年第8期26卷 450-455页

作者： A Asif m Hassan s Riaz s Naseem s s Hussain materials Growth and simulation Laboratory Department of PhysicsUniversity of the PunjabLahore-54590Pakistan Center of Excellence in solid state Physics University of the PunjabLahore-54590Pakistan

The present study involves co-precipitation method to grow un-doped and Zr-doped bismuth iron oxide with x_（Zr）=0.10–0.30. The molar solutions of ferric chloride（FeCl_3）, zirconyle chloride（ZrOCl_2）, and bismuth chloride（BiCl_3） are prepared in distilled water, and are allowed to react with sodium hydroxide（Na OH）. The synthesized powders are then converted into pellets, which are sintered at 500℃ for two hours in a muffle furnace. X-ray diffraction（XRD） shows multi-phase formation in un-doped and Zr doped samples. scanning electron microscope（sEm） depicts layered structure at low Zr concentration x_（Zr）= 0.10, while uniform surface with smaller grains and voids is observed at x_（Zr）= 0.20, but at x_（Zr）= 0.30, cracks and voids become prominent. The ferromagnetic nature of the un-doped sample is observed by vibrating sample magnetometer（Vsm）, while paramagnetic behavior appears due to Zr doping. The ferromagnetism in un-doped sample is lost by Zr doping, which is due to the formation of additional Fe–O–Zr bonds that induce paramagnetic behavior.

关键词： co-precipitation multi-phases ferromagnetism paramagnetism BiFeO3

Thermal Fatigue Behaviour of a Chromium Electroplated 32NiCrmo145 steel

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Journal of materials science & Technology 2004年第3期20卷 269-273页

作者： A.Abdollah-zadeh m.s.Jamshidi s.m.m.Hadavi Department of materials Engineering Tarbiat Modarres UniversityP.O.Box 14115-143TehranIranGST Research CenterP.O.Box 13185-665TehranIranSchool of Materials science and EngineeringMalekashtar UniversityP.O.Box 17665-3197TehranIran

Thermal fatigue behavior of hard chromium electroplated steel in three different crack intensities of high contraction(HC), medium contraction (mC) and low contraction (LC) was studied. maximum and minimum temperaturesduring thermal cycle were 800 and 100℃, respectively. The topography and cross sections of the samples exposedto 50, 100 and 200 thermal cycles were studied. The thermal fatigue behavior was analyzed using the data obtainedfrom surface roughness, crack networks and stress induced during cycles. Although the as-coated sample with LCchromium contained no crack, it appeared to have a high crack density after only 50 cycles. The crack depth andwidth in cyclically oxidized LC coating were much less than those in mC and HC coatings. It was concluded that theLC coating protected the substrate from having cracks or subsurface oxidation during thermal fatigue. The cracksin the HC and mC coatings increased in density as well as in depth by thermal cycles. moreover, the opening of thecracks to the substrate resulted in sub-surface oxidation.

关键词： Thermal fatigue Hard chromium plating 32NiCrmo145 steel

Electrical features of radio-frequency atmospheric pressure helium discharge with and without dielectric electrodes

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Plasma science and Technology 2019年第2期21卷 60-67页

作者： H AsHRAF s Z A sHAH H I A QAZI m A KHAN s HUssAIN m A BADAR s NIAZ m sHAFIQ Department of Physics University of Sargodha Department of Physics Quaid-i-Azam University

A comparative study of radio-frequency atmospheric pressure glow discharge(rf APGD)generated in helium with and without dielectric electrodes to investigate the effect of electrodes insulation on electrical features of APGD is presented. In the α mode, both the rf APGDs remain volumetric, stable and uniform. In the γ mode, the APGD without dielectric electrodes shrinks into a constricted plasma column whereas APGD with dielectric electrodes remains stable and retains the same volume without plasma constriction even at higher densities of discharge current. A comparison of electrical features of both rf APGDs in normal and abnormal glow discharge regimes is presented. In both APGDs with and without dielectric electrodes,impedance measurements have been performed and compared with equivalent circuit *** measured impedance data is found to be in good agreement with simulated data.

关键词： radiofrequency atmospheric pressure glow discharge dielectric electrodes plasma stability control

Influence of cold plasma treatment on insecticidal properties of wheat seeds against red flour beetles

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Plasma science and Technology 2019年第8期21卷 97-102页

作者： s AFsHEEN U FATImA T IQBAL m ABRAR s mUHAmmAD A sAEED m IsA m F mALIK s sHAmAs Department of Zoology Faculty of ScienceUniversity of GujratHafiz Hayat CampusGujrat50700Pakistan Department of Physics Faculty of ScienceUniversity of GujratHafiz Hayat CampusGujrat50700Pakistan3Department of PhysicsHazara University MansehraMansehra21300Pakistan4Department of PhysicsGovernment College Women UniversitySialkot51310Pakistan

For the long-term fortification of warehoused crops, the insecticidal impact of cold plasma treated wheat seeds against red flour beetles are *** this study, the gain weight loss,mortality and repellency tests of cold plasma treated seeds are investigated and statistical analysis is carried out by sPss *** plasma treatment is carried out at 800 V for 1 and 4 *** results show that the minimum grain weight loss is observed in plasma treated seeds as compared to controlled *** is also observed that the mortality rate is minimum in the controlled seed while maximum at 4 min plasma ***, the repellent effect has a very small variation as compared to the controlled seed for Tribolium ***, plasma treatment can be considered as a practical and effective method for seed protection against red floor beetles particularly during long-term storage by controlling the insecticidal effects.

关键词： cold plasma mortality repellency grain weight loss quality stored seeds protection

Thermal-hydraulic performance analysis of a subchannel with square and triangle fuel rod arrangements using the entropy generation approach

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Nuclear science and Techniques 2017年第10期28卷 95-101页

作者： s.Talebi m.m.Valoujerdi Department of Energy Engineering and Physics AmirkabirUniversity of Technology424 Hafez AvenueP.O.Box 15875-4413TehranIran

The present paper discusses entropy generation in fully developed turbulent flows through a subchannel,arranged in square and triangle arrays. Entropy generation is due to contribution of both heat transfer and pressure drop. Our main objective is to study the effect of key parameters such as spacer grid, fuel rod power distribution,Reynolds number Re, dimensionless heat power ω, lengthto-fuel-diameter ratio λ, and pitch-to-diameter ratio ξ on subchannel entropy generation. The analysis explicitly shows the contribution of heat transfer and pressure drop to the total entropy generation. An analytical formulation is introduced to total entropy generation for situations with uniform and sinusoidal rod power distribution. It is concluded that power distribution affects entropy generation.A smoother power profile leads to less entropy *** entropy generation of square rod array bundles is more efficient than that of triangular rod arrays, and spacer grids generate more entropy.

关键词：熵产生子信道燃料棒三角形正方形性能分析热工水力生成方法

Approximate energies and thermal properties of a position-dependent mass charged particle under external magnetic fields

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Chinese Physics B 2017年第6期26卷 22-30页

作者： m Eshghi H mehraban s m Ikhdair Young Researchers and Elite Club Central Tehran BranchIslamic Azad UniversityTehranIran Faculty of Physics Semnan UniversitySemnanIran Department of Physics Faculty of ScienceAn-Najah National UniversityNablusWest BankPalestine Department of Electrical Engineering Near East UniversityNicosiaNorthern CyprusMersin 10Turkey

We solve the schrodinger equation with a position-dependent mass（PDm） charged particle interacted via the superposition of the morse-plus-Coulomb potentials and is under the influence of external magnetic and Aharonov–Bohm（AB） flux fields. The nonrelativistic bound state energies together with their wave functions are calculated for two spatially-dependent mass distribution functions. We also study the thermal quantities of such a system. Further, the canonical formalism is used to compute various thermodynamic variables for second choosing mass by using the Gibbs formalism. We give plots for energy states as a function of various physical parameters. The behavior of the internal energy, specific heat, and entropy as functions of temperature and mass density parameter in the inverse-square mass case for different values of magnetic field are shown.

关键词： schr?dinger equation morse-plus-Coulomb potentials position-dependent mass distribution functions perpendicular magnetic and Aharonov–Bohm flux fields

Relativistic effect of pseudospin symmetry and tensor coupling on the mie-type potential via Laplace transformation method

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Chinese Physics B 2014年第12期23卷 44-49页

作者： m.Eshghi s.m.Ikhdair Young Researchers and Elite Club Central Tehran Branch Islamic Azad University Department of Physics Faculty of Science An-Najah National University

A relativistic mie-type potential for spin-1/2 particles is studied. The Dirac Hamiltonian contains a scalar s（r） and a vector V（r） mie-type potential in the radial coordinates, as well as a tensor potential U（r） in the form of Coulomb potential. In the pseudospin（p-spin） symmetry setting Σ = Cps and Δ = V（r）, an analytical solution for exact bound states of the corresponding Dirac equation is found. The eigenenergies and normalized wave functions are presented and particular cases are discussed with any arbitrary spin–orbit coupling number κ. special attention is devoted to the caseΣ = 0 for which p-spin symmetry is exact. The Laplace transform approach（LTA） is used in our calculations. some numerical results are obtained and compared with those of other methods.

关键词： Dirac equation mie-type potential Laplace transform approach tensor interaction p-spin symmetry