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Effect of Colouring Process on Pitting susceptibility of Austenitic stainless steel

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Journal of Materials science & Technology 2008年第3期24卷 400-406页

作者： s.s.Mahmoud M.M.Ahmed Chemistry Department University College of Girls for ArtsScience and EducationAin Shams University

Colouring of the austenitic stainless steel alloy （20.45% Cr, 8.57% Ni） was carried out in NaNO3-KNO3 eutectic melt without and with additions of Na2O2, NaCl and their mixtures at different temperatures ranging from 400-600℃, under open-circuit and galvanostatic anodic polarization conditions. The produced colours greatly depend on the thickness of oxide films, which in turn depends on the composition of the molten bath and its temperature. The more attractive, bright, adherent and uniform coloured oxide films can be obtained at 400, 450 and 500℃ in molten nitrate bath containing NaCl and Na2O2 mixtures. The pitting corrosion susceptibility of the coloured oxide films was tested in FeCl3 and NaCl as corrosive media. The obtained results indicate that the pitting corrosion susceptibility of the coloured oxide films greatly depends on the previous operating conditions of the colouring process of the stainless steel specimens such as the composition of molten bath, temperature and technique of colouring process.

关键词： stainless steel alloy Pitting corrosion Colouring processes

LINEARIZATION OF A NONLINEAR PERIODIC BOUNDARY CONDITION RELATED TO CORROsION MODELING

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Journal of Computational Mathematics 2007年第6期25卷 645-660页

作者： Y. s. Bhat s. Moskow Institute for Mathematics and its Applications Univ. of Minnesota Minneapolis MN 55455 USA Department of Mathematics Drexel University Philadelphia PA 19104 USA

We study galvanic currents on a heterogeneous surface. In electrochemistry, the oxidation-reduction reaction producing the current is commonly modeled by a nonlinear elliptic boundary value problem. The boundary condition is of exponential type with periodically varying parameters. We construct an approximation by first homogenizing the problem, and then linearizing about the homogenized solution. This approximation is far more accurate than both previous approximations or direct linearization. We establish convergence estimates for both the two and three-dimensional case and provide two-dimensional numerical experiments.

关键词： Galvanic corrosion Homogenization Nonlinear elliptic boundary value problem Butler-Volmer boundary condition Robin boundary condition.

Mn_(3)O_(4) based materials for electrochemical supercapacitors: Basic principles, charge storage mechanism, progress, and perspectives

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Journal of Materials science & Technology 2022年第35期130卷 227-248页

作者： s.A.Beknalkar A.M.Teli T.s.Bhat K.K.Pawar s.s.Patil N.s.Harale J.C.shin P.s.Patil Thin Film Materials Laboratory Department of PhysicsShivaji UniversityKolhapur 416-009India Division of Electronics and Electrical Engineering Dongguk University-SeoulSeoul 04620South Korea school of Nano-science and Technology Shivaji UniversityKolhapur 416-009India Department of Physics Sadguru Gadage MaharajCollege KaradSataraMississippi 415110India

The captivating properties of supercapacitors(sCs) such as high power and reasonably high energy densities made them stand up as a versatile solution to emerging energy storage ***,everyone is in pursuit of improvisation of the energy storage characteristics of *** or manganese oxide(Mn_(3)O_(4)) is a widely studied electrode material considering its fascinating features such as high theoretical capacitance(1370 F/g),variable oxidization states,prominent Jahn-Teller effect,broad potential window,environmentally benign and cost-effectiveness.A lot of research has been carried out on this material to unfold and improve its electrochemical *** this review,comprehensive knowledge and innovative attempts taken to improve its energy storage of Mn_(3)O_(4)material are ***,the basic properties concerned with electrochemical charge storage such as valance states,crystal structure,band diagram and energy storage mechanism are discussed,followed by putting forth the limitations of Mn_(3)O_(4).Later on,various strategies adopted to improve the electrochemical attributes of Mn_(3)O_(4)such as making composite with carbon-based materials,metal-based materials,polymers or doping metal atoms are ***,remarks on key scientific points and perspectives for further development of energy storage in Mn_(3)O_(4)conclude this review.

关键词： supercapacitors Nanostructures Mn_(3)O_(4)based composites

Comparative study on high temperature deformation behavior and processing maps of Mg-4Zn-1RE-0.5Zr alloy with and without in-situ sub-micron sized TiB2 reinforcement

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Journal of Magnesium and Alloys 2022年第12期10卷 3520-3541页

作者： s.K.sahoo s.K.Panigrahi Department of Mechanical Engineering Indian Institute of Technology MadrasChennai-600036India Applied Magnesium Research Group Center of Excellence in Materials and Manufacturing for Futuristic Mobility Indian Institute of Technology MadrasChennai-600036India

Mg-4Zn-1RE-0.5Zr (ZE41) Mg alloy is extensively used in the aerospace and automobile *** order to improve the applicability and performance,this alloy was engineered with in-situ Ti B2reinforcement to form Ti B2/ZE41 *** high temperature deformation behavior and manufacturability of the newly developed Ti B2/ZE41 composite and the parent ZE41 Mg alloy were studied via establishing constitutive modeling of flow stress,deformation activation energy and processing map over a temperature range of 250℃-450℃ and strain rate range of 0.001 s-1-10 *** predicted flow stress behavior of both materials were found to be well consistent with the experimental values.A significant improvement in activation energy was found in Ti B2/ZE41 composite (171.54 k J/mol) as compared to the ZE41 alloy (148.15 k J/mol) due to the dispersed strengthening of in-situ Ti *** processing maps were developed via dynamic material modeling.A wider workability domain and higher peak efficiency (45%) were observed in Ti B2/ZE41 composite as compared to ZE41 alloy (41%).The Dynamic recrystallization is found to be the dominating deformation mechanism for both materials;however,particle stimulated nucleation was found to be an additional mode of deformation in Ti B2/ZE41 *** twinning and stress induced cracks were observed in both the materials at low temperature and high strain rate.A narrow range of instability zone is found in the present Ti B2/ZE41 composite among the existing published literature on Mg based *** detailed microstructural characterization was carried out in both workability and instability domains to establish the governing deformation mechanisms.

关键词： ZE41 Mg composite In-situ TiB2 particles ZE41 Mg alloy Constitutive equations Processing map Dynamic recrystallization

Cu, Mn, Fe, and Zn Levels in soils of shika Area, Nigeria

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Biomedical and Environmental sciences 2004年第4期17卷 426-431页

作者： s.A.MAsHI s.A.YARO A.s.HAIBA DepartmentofGeography UniversityofAbujaP.M.B.117AbujaNIGERIA DepartmentofMetallurgicalEngineering AhmaduBelloUniversityZariaNigeria DepartmentofGeography AhmaduBelloUniversityZariaNigeria

Objective Heavy metals presented in toxic amounts can become injurious to human health. In areas where there is a high level of human activities on soils (such as agriculture and grazing) studies are therefore required from time to time to monitor levels of such metals in the soils in order to identify the point in time when toxicity problems become real. The objective of this paper is to determine the concentrations of some trace metals (Cu, Mn, Fe, and Zn) in soils under cultivation and grazing practices in shika, a rural area of Kaduna state of Nigeria. Method In this study, soil samples collected from three different categories of locations (cultivated, grazed, and uncultivated/non- grazed serving as a control) across shika area, Nigeria, were analysed for some trace metal levels (Cu, Mn, Fe, and Zn) using atomic absorption spectrophotometry. For each category, multiple sites were chosen to accommodate all possible intra-category variations, especially in terms of land use and management history and topographic characteristics. Topsoil (0-15 cm) and subsoil (20-30 cm) samples were collected from every site and analysed for the above metals. Averaged values of the metals for the three categories revealed that Zn is the most abundant metal, followed by Fe, then Mn and Cu the least. Results The results obtained indicate that the cultivation practices, and to a lesser extent grazing, in the area result in higher levels of all the metals than in the control, suggesting that crop immobilization of the metals from soils of the area is low, and that their systematic accumulation is taking place in cultivated soils of the area. Prospects of having elevated soil levels of the metals due to cultivation practices in the area therefore seem quite high. Conclusion On the basis of the results obtained, it was concluded that grazing and cultivation practices have in general caused some significant elevations in the bioavailable (i.e the plant available forms) levels of Z

关键词： Trace Metals soil Contamination Cultivation Grazing Control Nigeria

The internal propagation of fusion flame with the strong shock of a laser driven plasma block for advanced nuclear fuel ignition

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Chinese Physics B 2013年第5期22卷 369-374页

作者： B. Malekynia s. s. Razavipour Department of Physics Gachsaran BranchIslamic Azad University

An accelerated skin layer may be used to ignite solid state fuels. Detailed analyses were clarified by solving the hydrodynamic equations for nonlinear force driven plasma block ignition. In this paper, the complementary mechanisms are included for the advanced fuel ignition： external factors such as lasers, compression, shock waves, and sparks. The other category is created within the plasma fusion as reheating of an alpha particle, the Bremsstrahlung absorption, expansion, conduction, and shock waves generated by explosions. With the new condition for the control of shock waves, the spherical deuterium-tritium fuel density should be increased to 75 times that of the solid state. The threshold ignition energy flux density for advanced fuel ignition may be obtained using temperature equations, including the ones for the density profile obtained through the continuity equation and the expansion velocity for the r≠ 0 layers. These thresholds are significantly reduced in comparison with the ignition thresholds at x = 0 for solid advanced fuels. The quantum correction for the collision frequency is applied in the case of the delay in ion heating. Under the shock wave condition, the spherical proton- boron and proton-lithium fuel densities should be increased to densities 120 and 180 times that of the solid state. These plasma compressions are achieved through a longer duration laser pulse or X-ray.

关键词： block ignition advanced fuel quantum correction shock wave

Daily variation of radon gas and its short-lived progeny concentration near ground level and estimation of aerosol residence time

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Chinese Physics B 2016年第5期25卷 111-118页

作者： M Mohery A M Abdallah A Ali s s Baz Physics Department Faculty of Science University of Jeddah Physics Department Faculty of Science Sohag University Astronomy Department Faculty of Science King Abdulaziz University Astronomy Department Faculty of Science Cairo University Physics Department Girls Faculty of Science King Abdulaziz University

Atmospheric concentrations of radon（^（222）Rn） gas and its short-lived progenies^（218）Po,^（214）Pb, and^（214）Po were continuously monitored every four hours at the ground level in Jeddah city, Kingdom of saudi Arabia. The measurements were performed three times every week, starting from November 2014 to October 2015. A method of electrostatic precipitation of positively charged^（218）Po and ^（214）Po by a positive voltage was applied for determining^（222）Rn gas concentration. The short-lived^（222）Rn progeny concentration was determined by using a filter holder connected with the alpha-spectrometric technique. The meteorological parameters（relative air humidity, air temperature, and wind speed） were determined during the measurements of^（222）Rn and its progeny concentrations.^（222）Rn gas as well as its short-lived progeny concentration display a daily and seasonal variation with high values in the night and early morning hours as compared to low values at noon and in the afternoon. The observed monthly atmospheric concentrations showed a seasonal trend with the highest values in the autumn/winter season and the lowest values in the spring/summer season. Moreover, and in parallel with alphaspectrometric measurements, a single filter-holder was used to collect air samples. The deposited activities of^（214）Pb and the long-lived^（222）Rn daughter ^（210）Pb on the filter were measured with the gamma spectrometric technique. The measured activity concentrations of^（214）Pb by both techniques were found to be relatively equal largely. The highest mean seasonally activity concentrations of ^（210）Pb were observed in the autumn/winter season while the lowest mean were observed in the spring/summer season. The mean residence time（MRT） of aerosol particles in the atmospheric air could be estimated from the activity ratios of ^（210）Pb/^（214）Pb.

关键词： daily variation radon progeny concentration meteorological variables

Effects of the partial replacement of La by M(M=Ce,Ca and sr) in La_(2-x)M_xCuO_4 perovskites on catalysis of the water-gas shift reaction

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Journal of Natural Gas Chemistry 2010年第6期19卷 567-574页

作者： s.s.Maluf E.M.Assaf Institute de Química de so Carlos Universidade de So PauloAv.Trabalhador Socarlense400 So CarlosSP 13560-970Brazil

The performance of La2-x M x CuO4 perovskites （where M=Ce,Ca or sr） as catalysts for the water-gas shift reaction was investigated at 290℃ and 360℃.The catalysts were characterized by EDs,XRD,N2 adsorption-desorption,XPs and *** XRD results showed that all the perovskites exhibited a single phase （the presence of perovskite structure）,suggesting the incorporation of metals in the perovskite *** XPs and XANEs results showed the presence of Cu2＋ on the *** perovskites that exhibited the best catalytic performance were La 2 x Ce x CuO 4 perovskites,with CO conversions of 85% 90%.Moreover,these perovskites have higher surface areas and larger amounts of Cu on the *** Ce has a higher filled energy level than the other metals,increasing the energy of the valence band of Ce and providing more electrons for the ***,the La1.80Ca0.20CuO4 perovskite showed a good catalytic performance.

关键词： perovskites water-gas shift reaction lanthanum copper calcium cerium strontium

The influence of stimulated temperature-dependent emission cross section on intracavity optical parametric oscillator

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Chinese Physics B 2017年第2期26卷 238-241页

作者： s samimi A Keshavarz Department of Physics Shiraz University of Technology Shiraz Ira

In this paper, the influence of temperature on the intracavity optical parametric oscillator（IOPO） is investigated by using the stimulated temperature-dependent emission cross section of laser crystal. The rate equations under plane wave approximation have been used for simulation of signal output pulse. Results show that the signal output pulse width is decreased by increasing the laser crystal temperature. Also, the signal output energy is increased by the increasing of the laser crystal temperature. The simulation results for IOPO based on Nd：YAG and Nd：YVO_4, show that the signal pulse energies are increased by 3.2 and 5.6 times respectively when the laser crystal temperature increased from 15℃ to 300℃. The presented model indicates that the temperature sensitivity of Nd：YVO_4-based IOPOs is more than that of Nd：YAG-based IOPOs which is expected from a physical point of view.

关键词： nonlinear optic two-wave mixing parametric oscillators and amplifiers