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A Review on Diverse silver Nanostructures

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Journal of Materials science & Technology 2010年第6期26卷 487-522页

作者： s.Vongehr National Laboratory of solid state Microstructures Department of Materials Science and EngineeringNanjing University

This article reviews recent advances in the utilization of various water based synthesis routes towards the shape-controlled synthesis of silver nanoparticles and microstructures in a diverse range of shapes and sizes from several nanometers to micrometers. A variety of very simple one-pot methods, at times employing com- mercial microwave ovens, inexpensive low power ultrasound cleaners, or two-electrode electro-chemistry, can be surprisingly effective in the controlled synthesis of a wide range of nanostructured products, if only parameters are carefully chosen. Many approaches which are adopted include synthesis of Ag nanostructures with various shapes in solution, doping of Ag nanoparticles on unmodified silica and on/inside carbon spheres, kinetically controlled growth of Ag micro-particles with novel nanostructures on flat substrates, and galvanic replace- ment towards bimetallic Ag-Au dendrites and carbon composites. Characterizations of shape, composition and microstructure are carried out via scanning and transmission electron microscopy, various spectroscopy methods, N2 absorption measurements and suchlike. The involved growth mechanisms are investigated in order to discover new means towards better control. size, location and shape control, including micro- and nanostructure features, allows tuning the products properties towards desired applications. We focus on the optical properties and catalytic activities, but also the stability of compounds can be an issue of interest.

关键词： silver Nanostructures synthesis Thermal stability surface plasmon resonance Catalysis

Tribological behavior of lubricant-impregnated porous polyimide

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Friction 2024年第4期12卷 711-725页

作者： Jinbang LI Ningning ZHOU Janet s.s.WONG school of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Beijing Key Laboratory of Long-life Technology of Precise Rotation and Transmission Mechanisms Beijing Institute of Control EngineeringBeijing 100029China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK

Porous materials impregnated with lubricants can be used in conditions where limited lubricant is *** this work,three porous polyimides(PPI)with different densities were ***(PAO)impregnated PPI(iPPI)discs were rubbed against steel and sapphire *** operando observations of the iPPI-sapphire contacts show that oil is released under an applied load,forming a meniscus around *** at the outlet is created at high sliding *** amount of released oil increases with increasing PPI *** moduli,E*,estimated based on the actual contact size show that trapped oil in iPPIs contributes to load *** higher speeds,tribological rehydration of the contact occurs in low density iPPI,with that E*rises with *** high density PPIs,high speeds give a constantly high E*which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil *** of iPPI-steel contacts is governed by the mechanical properties of the PPI,the flow of the lubricant,and the roughness of the PPI *** low-and medium-density(highly porous,high roughness)PPIs,large amount of oil is released,and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological *** high density(low porosity)PPI,with lower roughness,hydrodynamic lubrication is achieved which gives the lowest *** results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness,stiffness,oil flow,and oil retentions.

关键词： polyimide porous material friction mechanism polymer limited lubrication

In depth fusion flame spreading with a deuterium-tritium plane fuel density profile for plasma block ignition

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Chinese Physics B 2012年第12期21卷 317-321页

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

solid-state fuel ignition was given by Chu and Bobin according to the hydrodynamic theory at x = 0 qualitatively. A high threshold energy flux density, i.e., E＊ = 4.3 × 10^12 J/m2, has been reached. Recently, fast ignition by employing clean petawatt-picosecond laser pulses was performed. The anomalous phenomena were observed to be based on suppression of prepulses. The accelerated plasma block was used to ignite deuterium tritium fuel at solid-state density. The detailed analysis of the thermonuclear wave propagation was investigated. Also the fusion conditions at x ≠ 0 layers were clarified by exactly solving hydrodynamic equations for plasma block ignition. In this paper, the applied physical mechanisms are determined for nonlinear force laser driven plasma blocks, thermonuclear reaction, heat transfer, electro,ion equilibration, stopping power of alpha particles, bremsstrahlung, expansion, density dependence, and fluid dynamics. New ignition conditions may be obtained by using temperature equations, including the density profile that is obtained by the continuity equation and expansion velocity. The density is only a function of x and independent of time. The ignition energy flux density, Et＊, for the x ≠ 0 layers is 1.95 × 1012 J/m2. Thus threshold ignition energy in comparison with that at x =0 layers would be reduced to less than 50 percent.

关键词： plasma block solid-state fuel ignition expansion

In-situ fabrication of Al(Zn)-Al_2O_3 graded composite using the aluminothermic reaction during hot pressing

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International Journal of Minerals,Metallurgy and Materials 2018年第7期25卷 832-839页

作者： s.m.a.haghi s.a.sajjadi a.babakhani Department of Materials science and Engineering Engineering facultyFerdowsi University of MashhadMashhadIra

In INs study, the fabrication of multilayer AI（Zn）-A1203 with different volume fractions of A1203 was investigated. A1 and ZnO powders were milled by a plaaetaxy ball mill, after which five-layer functionally graded samples were produced flarough hot pressing at 580~C and 90 MPa pressure for 30 min. Formation of reinforcing A1203 particles occurred in the aluminum matrix via the aluminolkermic reaction. Determination of the ignition temperature of the aluminolkennic reaction was accomplished using differential lkermal and lkermo- gravimelric amlyses. scaaming electron microscopy, energy dispersive spectroscopy, and X-ray diffractometery amlyses were utilized to characterize the specimens. The lkermal amlysis results showed that the ignition temperatures for the aluminolkennic reaction of layers with the highest and lowest ZnO contents were 667 and 670~C, respectively. Microslxuctural observation and chemical amlysis confirmed the fa- brication of AI（Zn）-A1203 functionally graded materials composites with precipitation of additional Zn in the matrix. Moreover, nearly dense functionally graded samples demonstrated minimum and maximum hacdness values of HV 75 and HV 130, respectively.

关键词： metal-matrix composites functionally graded composites fllermogravimet^ic analysis powder processing sintering

smart composite antibacterial coatings with active corrosion protection of magnesium alloys

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Journal of Magnesium and Alloys 2022年第12期10卷 3589-3611页

作者： A.s.Gnedenkov s.L.sinebryukhov V.s.Filonina N.G.Plekhova s.V.Gnedenkov Institute of Chemistry of FEB RAs 159 Pr.100-letiya VladivostokaVladivostok690022Russia

A new method of the formation of composite coatings with the function of active corrosion protection of magnesium alloys was developed using the plasma electrolytic oxidation(PEO) method. susceptibility of PEO-layers to pitting formation was evaluated using localized electrochemical methods(sVET/sIET). The morphological features and electrochemical properties of composite coatings were studied using sEM/EDX, XRD, micro-Raman spectroscopy and EIs/PDP measurements, respectively. The effect of surface layers impregnation with corrosion inhibitor on their protective properties in a corrosive environment was established. Additional protection was achieved using controllable coating pore sealing with polymer. It was found that the polymer treatment of the PEO-layer does not reduce the inhibitor’s efficiency. The formed protective composite inhibitor-and-polymer-containing layers decrease the corrosion current density of a magnesium alloy in a 3 wt.% Na Cl solution to three orders of magnitude. This predetermines the prospect of new smart coatings formation that significantly expand the field of application of electrochemically active materials. The mechanism of smart composite coating corrosion degradation was established. The antibacterial activity of the inhibitor-containing coatings against s. aureus methicillin-resistant strain was proved using the in vitro model. These protective layers are promising for reducing the incidence of implant-associated infections.

关键词： Magnesium alloy Plasma electrolytic oxidation Corrosion inhibitor self-healing Protective coatings

Tm^(3+) interactions in LiYF_4 studied by high-resolution spectroscopy

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Journal of Rare Earths 2009年第4期27卷 633-636页

作者： s.A.Klimin D.s.Pytalev Institute of spectroscopy Russian Academy of Sciences 5 Fizicheskaya Str. 142190 Troitsk Moscow region 142190 Russia

We used the high-resolution spectroscopy to study the interactions that Tm3＋ ion in a LiYF4 crystal is subjected to. several crystal field transitions with low integral intensity were found not registered before by means of ordinary spectroscopy. spectral evidences for interionic, hyperfine, isotopic interactions, and for a resonant broadening of the ground state are presented.

关键词： high-resolution Fourier-transform speclroscopy hyperfme structure isotopic structure pair centers rare earths

MgO-attached graphene nanosheet(MgO@GNs)reinforced magnesium matrix nanocomposite with superior mechanical,corrosion and biological performance

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International Journal of Minerals,Metallurgy and Materials 2024年第9期31卷 2062-2076页

作者： s.Abazari A.shamsipur H.R.Bakhsheshi-Rad M.s.soheilirad F.Khorashadizade s.s.Mirhosseini Department of Materials and Metallurgical Engineering Amirkabir University of TechnologyTehran ***Iran Iranian National standards Organization of Hormozgan HormozganIran Advanced Materials Research Center Department of Materials EngineeringNajafabad BranchIslamic Azad UniversityNajafabadIran Department of Materials and Metallurgical Engineering Iran University of Science and TechnologyTehranIran

Magnesium(Mg)alloys are gaining great consideration as body implant materials due to their high biodegradability and ***,they suffer from low corrosion resistance and antibacterial *** this research,semi-powder metallurgy followed by hot extrusion was utilized to produce the magnesium oxide@graphene nanosheets/magnesium(MgO@GNs/Mg)composite to improve mechanical,corrosion and cytocompatibility *** have revealed that the incorporation of MgO@GNs nanohybrids into Mg-based composite enhanced microhardness and compressive *** vitro,osteoblast cell culture tests show that using MgO@GNs nanohybrid fillers enhances osteoblast adhesion and apatite *** presence of MgO@GNs nanoparticles in the composites decreased the opening defects,micro-cracks and micro-pores of the composites thus preventing the penetration of the corrosive solution into the *** demonstrated that the MgO@GNs/Mg composite possesses excellent antibacterial properties because of the combination of the release of MgO and physical damage to bacterium membranes caused by the sharp edges of graphene nanosheets that can effectively damage the cell wall thereby facilitating penetration into the bacterial lipid ***,the MgO@GNs/Mg composite with high mechanical strength,antibacterial activity and corrosion resistance is considered to be a promising material for load-bearing implant applications.

关键词： metal matrix composites MgO@GNs nanohybrid strengthening mechanisms antibacterial activity biocompatibility

Low cycle fatigue properties and cyclic deformation behavior of as-extruded AZ31 magnesium alloy

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Transactions of Nonferrous Metals society of China 2010年第B07期20卷 533-539页

作者： s.KWON K.sONG K.s.sHIN s.I.KWUN Department of Materials science and Engineering Korea University school of Materials science and Engineering Seoul National University

The low cycle fatigue(LCF)properties of as-extruded AZ31 Mg alloy were investigated under total strain amplitudes in the range of 0.4%-1.2%with strain rate of 1×10- 2s -*** to the twinning effect in compression during loading and the detwinning effect during unloading,the alloy showed an asymmetric hysteresis *** cyclic stress response exhibited cyclic hardening at high total strain *** cyclic deformation behaviors were discussed using the Coffin-Manson plot,which divided the plastic strain amplitudes into the tension side and the compression *** the LCF tests that were started from either tension or compression under a total strain amplitude of 1.0%,the interaction between the twinning effect and dislocation was *** twinning effect during the LCF test and the variation of the dislocation density were investigated using optical microscopy and transmission electron microscopy,respectively.

关键词： AZ31 magnesium alloy low cycle fatigue twinning dislocation

spin synthesis of monolayer of siO_2 thin films

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Journal of semiconductors 2015年第4期36卷 16-25页

作者： s.s.shinde s.Park J.shin Korea Research Institute of standards and science

The highly ordered monolayer of submicron size silica （siO2） particles （235 nm） is developed on p-silicon by using three-step spin-coating in colloidal suspension, which has significant potential in various applications. The influence of three-step spin speeds, spinning time, acceleration time between different steps, concentration of siO2 particles in the solution, solution quantity, and the ambient humidity （relative humidity） on the properties ofmonolayer siO2 are studied in order to achieve a large area monolayer film. A relatively high surface coverage and uniform monolayer film of siO2 particles in the range of 85%-90% are achieved by appropriate control of the preparative parameters. We conclude that this method can be useful in industrial applications, because of the fabrication speed, surface coverage and cost of the process.

关键词： thin films spin synthesis electron microscopy