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Electrophoretic deposition of chitosan-bioglass^(■)-hydroxyapatite-halloysite nanotube composite coating

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Rare Metals 2022年第11期41卷 3850-3857页

作者： Arman molaei MardAli Yousefpour Department of Materials Engineering Tehran Science and Research BranchIslamic Azad UniversityTehran***Iran Faculty of Materials Science and Metallurgical Engineering Semnan UniversitySemnan***Iran

The composite coatings of chitosan(CS)-bioglass^(■)(BG)-hydroxyapatite(HA)-halloysite nanotube(HNT)were investigated and produced via electrophoretic deposition(EPD)*** utilization of CS as a dispersing,blending and charging agent for ceramic particles,including BG,HA and HNT,allowed the formation of CS-BG/HA/HNT composite,functionally graded composite(FGC)and bilayer film containing different *** results of scanning electron microscopy(SEM),energy-dispersive spectrometry(EDS),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)illustrate the composite in the form of the optimum distribution of ceramic components in the CS matrix with thickness of 28μm on titanium(Ti)*** impedance spectroscopy(EIS)and potentiodynamic polarization tests indicate that the corrosion resistance of the coated sample increases in corrected simulated body fluid(C-SBF)at 37℃.Finally,the apatiteinducing ability of CS-BG-HA-HNT is proved by the formation of carbonated hydroxyapatite particles on composite coating in C-SBF.

关键词： Four-component coating Composites Biomaterials Electrophoretic deposition Corrosion

Development of a new correlation to calculate permeability for flows with high Knudsen number

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Chinese Physics B 2016年第2期25卷 271-277页

作者： esmaeil Dehdashti Department of Mechanical Engineering University of Tehran

Flows with high Knudsen number play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow with high Knudsen number using modified lattice Boltzmann method （LBM） through a porous medium in a channel. The effect of collision between molecules and solid walls, which is required to accurately simulate transition flow regime, is taken into account using a modified relaxation time. Slip velocity on the wall, which is another significant difficulty in simulating transition flow regime, is captured using the slip reflection boundary condition （SRBC）. The geometry of porous medium is considered as in-line and staggered. The results are in good agreement with previous works. A new correlation is obtained between permeability, Knudsen number and porosity for flows in transition flow regimes.

关键词： flow in porous micro-channel lattice Boltzmann method high Knudsen number permeability

Corrosion Behaviors of Two Types of Commercial Stainless Steel after Plastic Deformation

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Journal of Materials Science & Technology 2010年第9期26卷 833-838页

作者： esmaeil Jafari Materials Science and Engineering Department Islamic Azad University Shiraz Branch

The influence of deformation temperature,strain rate and alloying elements such as chromium,nickel,copper,on corrosion resistance of a 304 stainless steel after plastic deformation was *** techniques employed were tensile test at room and elevated temperature,deep drawing tests at various strain rates,X-ray diffraction test and potentiodynamic and cyclic polarization,metallography by optical and scanning electron *** showed that chromium,nickel and copper had a significant effect on corrosion resistance of steel after plastic *** was observed that corrosion resistance after plastic deformation was a function of deformation temperature and alloying elements.

关键词： Corrosion resistance Plastic deformation Stainless steel Phase transformation Polarization test

Effect of Bainite Morphology on Mechanical Properties of the Mixed Bainite-martensite Microstructure in D6AC Steel

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Journal of Materials Science & Technology 2012年第4期28卷 336-342页

作者： Khodamorad abbaszadeh Hassan Saghafian Shahram Kheirandish School of Metallurgy and Materials Engineering Iran University of Science and Technology Tehran *** Iran

The effect of bainite morphology on mechanical properties of the mixed bainite-martensite microstructure in D6AC low alloy ultra-high strength steel has been studied in the present work. For this purpose, samples austenitized at 910℃ for 40 min were quenched in three different ways. Some of the samples were directly oil-quenched, some others were quenched in salt bath at 330 ℃ and the remaining samples were quenched in salt bath at 425 ℃ for various holding times. All samples were tempered at 200 ℃ for 2 h. Microstructures were examined by optical microscopy （OM） and scanning electron microscopy （SEM）. Fracture surfaces also were studied by SEM. Results showed that the mixed microstructure containing martensite and 28 vol.% of the lower bainite exhibited higher yield and tensile strengths than the fully martensitic microstructure. This could be mainly attributed to the partitioning of the prior austenite grains by the lower bainite and enhancing the strength of lower bainite in the mixed microstructure by plastic constraint. Charpy V-notch （CVN） impact energy and ductility were improved by increasing the volume fraction of the lower bainite. This is not the case about the mixed microstructure containing the upper bainite and martensite. As a result, the tensile and CVN impact properties of mixed upper bainite-martensite microstructure are lower than those of the fully martensitic microstructure. Finally, fractography studies showed cleavage fracture at the surface of CVN impact specimens with martensitic and upper bainitic microstructures confirming the tendency to brittle behavior.

关键词： Upper bainite Lower bainite Microstructure D6AC Mechanical properties

A Design Concept and Kinematic Model for a Soft Aquatic Robot with Complex Bio-mimicking Motion

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Journal of Bionic Engineering 2022年第1期19卷 16-28页

作者： Shokoofeh abbaszadeh Roberto Leidhold Stefan Hoerner Institute of Electrical Power Systems Department of Electrical Engineering and Information TechnologyOtto-Von-Guericke University of MagdeburgUniversitätsplatz 239106MagdeburgGermany Institute of Fluid Dynamics and Thermodynamics Department of Process and Systems EngineeringOtto-Von-Guericke University of MagdeburgUniversitätsplatz 239106MagdeburgGermany

Fish mortality assessments for turbine passages are currently performed by live-animal testing with up to a hundred thousand fish per year in Germany.A propelled sensor device could act as a fish *** this context,the study presented here investigates the state of the art via a thorough literature review on propulsion systems for aquatic *** evaluation of propulsion performance,weight,size and complexity of the motion achievable allows for the selection of an optimal concept for such a fish mimicking device carrying the *** the second step,the design of a bioinspired soft robotic fish driven by an unconventional drive system is *** is based on piezoceramic actuators,which allow for motion with five degrees of freedom(DOF)and the creation of complex bio-mimicking body motions.A kinematic model for the motion’s characteristics is developed,to achieve accurate position feedback with the use of strain *** measurements validate the complex deformation of the body and deliver the basis for the calibration of the kinematic ***,it can be shown,that the calibrated model presented allows the tracking of the deformation of the entire body with an accuracy of 0.1 mm.

关键词： Unconventional drive system Biologically inspired robots Biomimetics Flexible robots

Improving the wear resistance of plasma electrolytic oxidation(PEO)coatings applied on Mg and its alloys under the addition of nano-and micro-sized additives into the electrolytes:A review

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Journal of Magnesium and Alloys 2021年第4期9卷 1167-1189页

作者： Maryam molaei Kazem Babaei Arash Fattah-alhosseini Department of Materials Engineering Bu-Ali Sina UniversityHamedan 65178-38695Iran

As an efficient surface modification approach,the plasma electrolytic oxidation(PEO)technique can boost the capability of wear protection in Mg and its alloys by applying a hard and thick ceramic *** this procedure,more efficient protection can be acquired via adding additives(in the form of particle,powder,sheet,etc.)into solutions and producing composite *** additives result in more efficient protection against wear via getting stuck in the cracks and pores of coatings and rising the thickness,hardness,and diminishing the porosity size and *** efficiency of each additive can be changed owing to its intrinsic properties like melting point,size,participation type(reactive,partly reactive,or inert)and potential of *** this review,the effects of distinct additives in nano-and micro-scale size on wear behavior of PEO coatings on Mg and its alloys is going to be reviewed.

关键词： Plasma electrolytic oxidation(PEO) Mg alloys Wear behavior Nano-sized additives Micro-sized additives

Numerical investigation of gas bubble behavior in tapered fluidized beds

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Particuology 2018年第3期16卷 152-164页

作者： Ramin Khodabandehlou Hossein Askaripour Asghar molaei Dehkordi Department of Chemical and Petroleum Engineering Sharif University of Technology P.O. Box 11155-9465 Tehran Iran

In this article, the behavior of gas bubbles in tapered fluidized beds is investigated with the use of a two- fluid model incorporating kinetic theory of granular flow. The effects of various parameters such as apex angle, particle size, and particle density on the size distribution and the rise velocity of gas bubbles were examined. In addition, the simulation results for the bubble fraction and axial velocity of gas bubbles were compared with experimental data reported in the literature and good agreement was observed. As the apex angle was increased, the fraction of gas bubbles with large sizes increased and the fraction of bubbles with small sizes decreased. As the particle size increased, the fraction of gas bubbles with large diameters decreased; however, the fraction of bubbles with medium diameters increased. The obtained results clearly indicate that an increased solid density increased the bubble rise velocity up to a specified height and reduced the velocity at larger heights, in tapered fluidized beds.

关键词： Tapered fluidized beds Apex angle Particle size and density Bubble size distribution Rise velocity of bubbles

Effect of copper slag recovery on hydrometallurgical cut-off grades considering environmental aspects

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Journal of Central South University 2016年第4期23卷 798-807页

作者： AFSHIN AKBARI esmaeil RAHIMI Department of Mining Engineering Islamic Azad University-Central Tehran Branch Department of Mining Engineering Islamic Azad University-South Tehran Branch

Determining the hydrometallurgical cut-off grades specifies the destination of low grade materials and this is subjected to more benefits in mining. Copper production rate is considered as one of the fundamental issues in hydrometallurgical cut-off grades determination. Slags are remarked as one of the main sources of copper. It is not only regarded as a waste but also identified as another resource extracting base metals. Slags are characterized by copper high grade. Thus, slag copper recovery can be led to different cut-off grades and net present value(NPV). The current research scrutinizes the effect of slag recovery by both flotation and hydrometallurgical methods on the hydrometallurgical cut-off grades. For this purpose, the optimum cut-off grade algorithms of hydrometallurgical methods are developed by considering associated environmental parameters, incomes and also the costs. Then, their optimum amounts are calculated with NPV maximization as an objective function. The results indicate that considering slag copper recovery in the hydrometallurgical cut-off grade algorithms reduces the environmental costs caused by slag dumping and leads to more NPV by 9%.

关键词： hydrometallurgy cut-off grades low grade materials waste floatation slag copper recovery environmental parameters slag dumping NPV maximization

Simply synthesized TiO_2 nanorods as an effective scattering layer for quantum dot sensitized solar cells

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Chinese Physics B 2014年第4期23卷 531-538页

作者： Mahmoud Samadpour Azam Iraji zad Mehdi molaei Department of Physics Faculty of Science K. N. Toosi University of Technology Institute for Nanoscience and Nanotechnology Sharif University of Technology Department of Physics Sharif University of Technology Department of Physics Faculty of ScienceVali-e-Asr University

TiO2 nanorod layers are synthesized by simple chemical oxidation of Ti substrates. Diffuse reflectance spectroscopy measurements show effective light scattering properties originating from nanorods with length scales on the order of one micron. The films are sensitized with CdSe quantum dots （QDs） by successive ionic layer adsorption and reaction （SILAR） and integrated as a photoanode in quantum dot sensitized solar cells （QDSCs）. Incorporating nanorods in photoanode structures provided 4- to 8-fold enhancement in light scattering, which leads to a high power conversion efficiency, 3.03% （Voc = 497 mV, Jsc = 11.32 mA/cm2, FF = 0.54）, in optimized structures. High efficiency can he obtained just by tuning the photoanode structure without further treatments, which will make this system a promising nanostructure for efficient quantum dot sensitized solar cells.

关键词： solar cell nanorod quantum dot scattering