WorldWideScience

Sample records for surface engineer metals

  1. Cell surface engineering of microorganisms towards adsorption of heavy metals.

    Science.gov (United States)

    Li, Peng-Song; Tao, Hu-Chun

    2015-06-01

    Heavy metal contamination has become a worldwide environmental concern due to its toxicity, non-degradability and food-chain bioaccumulation. Conventional physical and chemical treatment methods for heavy metal removal have disadvantages such as cost-intensiveness, incomplete removal, secondary pollution and the lack of metal specificity. Microbial biomass-based biosorption is one of the approaches gaining increasing attention because it is effective, cheap, and environmental friendly and can work well at low concentrations. To enhance the adsorption properties of microbial cells to heavy metal ions, the cell surface display of various metal-binding proteins/peptides have been performed using a cell surface engineering approach. The surface engineering of Gram-negative bacteria, Gram-positive bacteria and yeast towards the adsorption of heavy metals are reviewed in this article. The problems and future perspectives of this technology are discussed.

  2. Surface interactions affect the toxicity of engineered metal oxide nanoparticles toward Paramecium.

    Science.gov (United States)

    Li, Kungang; Chen, Ying; Zhang, Wen; Pu, Zhichao; Jiang, Lin; Chen, Yongsheng

    2012-08-20

    To better understand the potential impacts of engineered metal oxide nanoparticles (NPs) in the ecosystem, we investigated the acute toxicity of seven different types of engineered metal oxide NPs against Paramecium multimicronucleatum, a ciliated protozoan, using the 48 h LC(50) (lethal concentration, 50%) test. Our results showed that the 48 h LC(50) values of these NPs to Paramecium ranged from 0.81 (Fe(2)O(3) NPs) to 9269 mg/L (Al(2)O(3) NPs); their toxicity to Paramecium increased as follows: Al(2)O(3) Paramecium; this implies that metal oxide NPs with strong association with the cell surface might induce more severe cytotoxicity in unicellular organisms.

  3. Surface engineering glass-metal coatings designed for induction heating of ceramic components

    International Nuclear Information System (INIS)

    Khan, Amir Azam; Labbe, Jean Claude

    2014-01-01

    The term Surface Engineering is of relatively recent origin and use, however, the use of coatings and treatments to render surfaces of materials more suitable for certain application or environment is not new. With the advent of Vacuum Technology, Surface Engineering has gained a whole new impetus, whereby expensive materials with adequate mechanical, chemical and thermal properties are being coated or treated on their surfaces in order to achieve what is called as Surface Engineered materials. The present paper presents an overview of recent achievements in Surface Engineering and gives a detailed view of a specific application where glass-metal composite coatings were deposited on ceramic components in order to render them sensitive to induction heating. Sintered glaze coatings containing silver particles in appropriate concentration can be used for the induction heating of porcelain. Mixtures of glass ceramic powders with silver are used to prepare self-transfer patterns, which are deposited over porcelain. Several configurations of these coatings, which are aesthetic to start with, are employed and heating patterns are recorded. The microstructure of these coatings is discussed in relation to the heating ability by a classical household induction system. The results show that this technique is practical and commercially viable

  4. Engineering of microorganisms towards recovery of rare metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, Kouichi; Ueda, Mitsuyoshi [Kyoto Univ. (Japan). Div. of Applied Life Sciences

    2010-06-15

    The bioadsorption of metal ions using microorganisms is an attractive technology for the recovery of rare metal ions as well as removal of toxic heavy metal ions from aqueous solution. In initial attempts, microorganisms with the ability to accumulate metal ions were isolated from nature and intracellular accumulation was enhanced by the overproduction of metal-binding proteins in the cytoplasm. As an alternative, the cell surface design of microorganisms by cell surface engineering is an emerging strategy for bioadsorption and recovery of metal ions. Cell surface engineering was firstly applied to the construction of a bioadsorbent to adsorb heavy metal ions for bioremediation. Cell surface adsorption of metal ions is rapid and reversible. Therefore, adsorbed metal ions can be easily recovered without cell breakage, and the bioadsorbent can be reused or regenerated. These advantages are suitable for the recovery of rare metal ions. Actually, the cell surface display of a molybdate-binding protein on yeast led to the enhanced adsorption of molybdate, one of the rare metal ions. An additional advantage is that the cell surface display system allows high-throughput screening of protein/peptide libraries owing to the direct evaluation of the displayed protein/peptide without purification and concentration. Therefore, the creation of novel metal-binding protein/ peptide and engineering of microorganisms towards the recovery of rare metal ions could be simultaneously achieved. (orig.)

  5. Nano Surface Engineering in the 21st Century

    Institute of Scientific and Technical Information of China (English)

    Xu Bin-shi; Wang Hai-dou; Dong Shi-yun; Shi Pei-jing; Xu Yi

    2004-01-01

    Nano surface engineering is the new development of surface engineering, and is the typical representation that the advanced nano technology improves the traditional surface engineering. The connotation of nano surface engineering is profound. The initial stage of nano surface engineering is realized at present day. The key technologies of nano surface engineering are the support to the equipment remanufacturing. Today the relatively mature key technologies are: nano thermal spraying technology, nano electric-brush plating technology, nano self-repairing anti-friction technology and metal surface nanocrystallization, etc. Many scientific issues have been continuously discovered. Meanwhile they have been applied in the practice more and more, and have archived the excellent remanufacturing effect.

  6. An introduction to surface alloying of metals

    CERN Document Server

    Hosmani, Santosh S; Goyal, Rajendra Kumar

    2014-01-01

    An Introduction to Surface Alloying of Metals aims to serve as a primer to the basic aspects of surface alloying of metals. The book serves to elucidate fundamentals of surface modification and their engineering applications. The book starts with basics of surface alloying and goes on to cover key surface alloying methods, such as carburizing, nitriding, chromizing, duplex treatment, and the characterization of surface layers. The book will prove useful to students at both the undergraduate and graduate levels, as also to researchers and practitioners looking for a quick introduction to surface alloying.

  7. Surface- and interface-engineered heterostructures for solar hydrogen generation

    Science.gov (United States)

    Chen, Xiangyan; Li, Yanrui; Shen, Shaohua

    2018-04-01

    Photoelectrochemical (PEC) water splitting based on semiconductor photoelectrodes provides a promising platform for reducing environmental pollution and solving the energy crisis by developing clean, sustainable and environmentally friendly hydrogen energy. In this context, metal oxides with their advantages including low cost, good chemical stability and environmental friendliness, have attracted extensive attention among the investigated candidates. However, the large bandgap, poor charge transfer ability and high charge recombination rate limit the PEC performance of metal oxides as photoelectrodes. To solve this limitation, many approaches toward enhanced PEC water splitting performance, which focus on surface and interface engineering, have been presented. In this topical review, we concentrate on the heterostructure design of some typical metal oxides with narrow bandgaps (e.g. Fe2O3, WO3, BiVO4 and Cu2O) as photoelectrodes. An overview of the surface- and interface-engineered heterostructures, including semiconductor heterojunctions, surface protection, surface passivation and cocatalyst decoration, will be given to introduce the recent advances in metal oxide heterostructures for PEC water splitting. This article aims to provide fundamental references and principles for designing metal oxide heterostructures with high activity and stability as photoelectrodes for PEC solar hydrogen generation.

  8. Surface engineering by ion implantation

    International Nuclear Information System (INIS)

    Nielsen, Bjarne Roger

    1995-01-01

    Awidespread commercial applica tion iof particle accelerators is for ion implantation. Accelerator beams are used for ion implantation into metals, alloying a thin surface layer with foreign atoms to concentrations impossible to achieve by thermal processes, making for dramatic improvements in hardness and in resistance to wear and corrosion. Traditional hardening processes require high temperatures causing deformation; ion implantation on the other hand is a ''cold process'', treating the finished product. The ionimplanted layer is integrated in the substrate, avoiding the risk of cracking and delamination from normal coating processes. Surface properties may be ''engineered'' independently of those of the bulk material; the process does not use environmentally hazardous materials such as chromium in the surface coating. The typical implantation dose required for the optimum surface properties of metals is around 2 x 10 17 ion/cm 2 , a hundred times the typical doses for semiconductor processing. When surface areas of more than a few square centimetres have to be treated, the implanter must therefore be able to produce high beam currents (5 to 10 mA) to obtain an acceptable treatment time. Ion species used include nitrogen, boron, carbon, titanium, chromium and tantalum, and beam energies range from 50 to 200 keV. Since most components are three dimensional, it must be possible to rotate and tilt them in the beam, and control beam position over a large area. Examples of industrial applications are: - surface treatment of prostheses (hip and knee joints) to reduce wear of the moving parts, using biocompatible materials; - ion implantation into high speed ball bearings to protect against the aqueous corrosion in jet engines (important for service helicopters on oil rigs); - hardening of metal forming and cutting tools; - reduction of corrosive wear of plastic moulding tools, which are expensive to produce

  9. Engineering noble metal nanomaterials for environmental applications

    Science.gov (United States)

    Li, Jingguo; Zhao, Tingting; Chen, Tiankai; Liu, Yanbiao; Ong, Choon Nam; Xie, Jianping

    2015-04-01

    Besides being valuable assets in our daily lives, noble metals (namely, gold, silver, and platinum) also feature many intriguing physical and chemical properties when their sizes are reduced to the nano- or even subnano-scale; such assets may significantly increase the values of the noble metals as functional materials for tackling important societal issues related to human health and the environment. Among which, designing/engineering of noble metal nanomaterials (NMNs) to address challenging issues in the environment has attracted recent interest in the community. In general, the use of NMNs for environmental applications is highly dependent on the physical and chemical properties of NMNs. Such properties can be readily controlled by tailoring the attributes of NMNs, including their size, shape, composition, and surface. In this feature article, we discuss recent progress in the rational design and engineering of NMNs with particular focus on their applications in the field of environmental sensing and catalysis. The development of functional NMNs for environmental applications is highly interdisciplinary, which requires concerted efforts from the communities of materials science, chemistry, engineering, and environmental science.

  10. Engineering noble metal nanomaterials for environmental applications.

    Science.gov (United States)

    Li, Jingguo; Zhao, Tingting; Chen, Tiankai; Liu, Yanbiao; Ong, Choon Nam; Xie, Jianping

    2015-05-07

    Besides being valuable assets in our daily lives, noble metals (namely, gold, silver, and platinum) also feature many intriguing physical and chemical properties when their sizes are reduced to the nano- or even subnano-scale; such assets may significantly increase the values of the noble metals as functional materials for tackling important societal issues related to human health and the environment. Among which, designing/engineering of noble metal nanomaterials (NMNs) to address challenging issues in the environment has attracted recent interest in the community. In general, the use of NMNs for environmental applications is highly dependent on the physical and chemical properties of NMNs. Such properties can be readily controlled by tailoring the attributes of NMNs, including their size, shape, composition, and surface. In this feature article, we discuss recent progress in the rational design and engineering of NMNs with particular focus on their applications in the field of environmental sensing and catalysis. The development of functional NMNs for environmental applications is highly interdisciplinary, which requires concerted efforts from the communities of materials science, chemistry, engineering, and environmental science.

  11. Engineering Metal Nanostructure for SERS Application

    Directory of Open Access Journals (Sweden)

    Yanqin Cao

    2013-01-01

    Full Text Available Surface-enhanced Raman scattering (SERS has attracted great attention due to its remarkable enhancement and excellent selectivity in the detection of various molecules. Noble metal nanomaterials have usually been employed for producing substrates that can be used in SERS because of their unique local plasma resonance. As the SERS enhancement of signals depends on parameters such as size, shape, morphology, arrangement, and dielectric environment of the nanostructure, there have been a number of studies on tunable nanofabrication and synthesis of noble metals. In this work, we will illustrate progress in engineering metallic nanostructures with various morphologies using versatile methods. We also discuss their SERS applications in different fields and the challenges.

  12. A solar engine using the thermal expansion of metals.

    Science.gov (United States)

    Beam, R.; Jedlicka, J.

    1973-01-01

    A thermal engine which uses solid metal as the single-phase working substance to convert solar energy into small amounts of mechanical energy is described. Test data are given for an engine whose working substance was annealed 304-type steel welded into a thin-walled tube that was mounted in a bearing at each end (making it free to rotate about its axis) with a flywheel mass at its midpoint. When heated on its upper surface, the tube rotates producing steady power. The theory of the engine is outlined.

  13. Modular assembly of low-dimensional coordination architectures on metal surfaces

    International Nuclear Information System (INIS)

    Stepanow, Sebastian; Lin, Nian; Barth, Johannes V

    2008-01-01

    The engineering of highly organized molecular architectures has attracted strong interest because of its potential for novel materials and functional nanoscopic devices. An important factor in the development, integration, and exploitation of such systems is the capability to prepare them on surfaces or in nanostructured environments. Recent advances in supramolecular design on metal substrates provide atomistic insight into the underlying self-assembly processes, mainly by scanning tunneling microscopy observations. This review summarizes progress in noncovalent synthesis strategies under ultra-high vacuum conditions employing metal ions as coordination centers directing the molecular organization. The realized metallosupramolecular compounds and arrays combine the properties of their constituent metal ions and organic ligands, and present several attractive features: their redox, magnetic and spin-state transitions. The presented exemplary molecular level studies elucidate the arrangement of organic adsorbates on metal surfaces, demonstrating the interplay between intermolecular and molecule-substrate interactions that needs to be controlled for the fabrication of low-dimensional structures. The understanding of metallosupramolecular organization and metal-ligand interactions on solid surfaces is important for the control of structure and concomitant function

  14. 29 CFR 1926.758 - Systems-engineered metal buildings.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Systems-engineered metal buildings. 1926.758 Section 1926... Systems-engineered metal buildings. (a) All of the requirements of this subpart apply to the erection of systems-engineered metal buildings except §§ 1926.755 (column anchorage) and 1926.757 (open web steel...

  15. Engineering metallic nanostructures for plasmonics and nanophotonics

    Science.gov (United States)

    Lindquist, Nathan C.; Nagpal, Prashant; McPeak, Kevin M.; Norris, David J.; Oh, Sang-Hyun

    2012-03-01

    Metallic nanostructures now play an important role in many applications. In particular, for the emerging fields of plasmonics and nanophotonics, the ability to engineer metals on nanometric scales allows the development of new devices and the study of exciting physics. This review focuses on top-down nanofabrication techniques for engineering metallic nanostructures, along with computational and experimental characterization techniques. A variety of current and emerging applications are also covered.

  16. Corrosion-resistant metal surfaces

    Science.gov (United States)

    Sugama, Toshifumi [Wading River, NY

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  17. Are Vicinal Metal Surfaces Stable?

    DEFF Research Database (Denmark)

    Frenken, J. W. M.; Stoltze, Per

    1999-01-01

    We use effective medium theory to demonstrate that the energies of many metal surfaces are lowered when these surfaces are replaced by facets with lower-index orientations. This implies that the low-temperature equilibrium shapes of many metal crystals should be heavily faceted. The predicted...... instability of vicinal metal surfaces is at variance with the almost generally observed stability of these surfaces. We argue that the unstable orientations undergo a defaceting transition at relatively low temperatures, driven by the high vibrational entropy of steps....

  18. The implementation of tribological principles in an expert-system (``PRECEPT``) for the selection of metallic materials, surface treatments and coatings in engineering design

    Energy Technology Data Exchange (ETDEWEB)

    Franklin, S.E. [Philips Electronics N.V., Centre for Mfg. Technology, Eindhoven (Netherlands); Dijkman, J.A. [Philips Electronics N.V., Centre for Mfg. Technology, Eindhoven (Netherlands)

    1995-02-01

    Many of the component failures occurring in service can be avoided or delayed by better incorporation of tribological principles into engineering design. However, the concept of tribology has not yet penetrated successfully into industry in general and there remains an urgent need for the provision of practical tribology design criteria and the transference of tribology knowledge to engineering designers. Knowledge-based computer systems offer great potential for effecting tribology knowledge transfer and promoting improved design practice. Here we report the development and implementation of eight wear design rules in an expert system for assisting the selection of metallic materials, surface treatments and coatings during the initial stages of engineering design. These rules, which are intended principally for engineering designers involved with fine mechanical constructions operating at temperatures at or close to room temperature, allow the tribological reliability of a candidate design to be assessed on the basis of the most likely wear-related problems that can arise in service. (orig.)

  19. Liquid Metal Engineering and Technology. Volume 1

    International Nuclear Information System (INIS)

    1988-01-01

    These proceedings of the fourth international conference on liquid metal engineering and technology volume 1, are devided into 3 sections bearing on: - Apparatus and components for liquid metal (29 papers) - Liquid metal leaks, fires and fumes (10 papers) - Cleaning, decontamination, waste disposal (14 papers) [fr

  20. Bioinspired surface functionalization of metallic biomaterials.

    Science.gov (United States)

    Su, Yingchao; Luo, Cheng; Zhang, Zhihui; Hermawan, Hendra; Zhu, Donghui; Huang, Jubin; Liang, Yunhong; Li, Guangyu; Ren, Luquan

    2018-01-01

    Metallic biomaterials are widely used for clinical applications because of their excellent mechanical properties and good durability. In order to provide essential biofunctionalities, surface functionalization is of particular interest and requirement in the development of high-performance metallic implants. Inspired by the functional surface of natural biological systems, many new designs and conceptions have recently emerged to create multifunctional surfaces with great potential for biomedical applications. This review firstly introduces the metallic biomaterials, important surface properties, and then elaborates some strategies on achieving the bioinspired surface functionalization for metallic biomaterials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The ion implantation of metals and engineering materials

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1978-01-01

    An entirely new method of metal finishing, by the process of ion implantation, is described. Introduced at first for semiconductor device applications, this method has now been demonstrated to produce major and long-lasting improvements in the durability of material surfaces, as regards both wear and corrosion. The process is distinct from that of ion plating, and it is not a coating technique. After a general description of ion implantation examples are given of its effects on wear behaviour (mostly in steels and cemented carbides) and on corrosion, in a variety of metals and alloys. Its potential for producing decorative finishes is mentioned briefly. The equipment necessary for carrying out ion implantation for engineering applications has now reached the prototype stage, and manufacture of plant for treating a variety of tools and components is about to commence. These developments are outlined. (author)

  2. Surface Finish after Laser Metal Deposition

    Science.gov (United States)

    Rombouts, M.; Maes, G.; Hendrix, W.; Delarbre, E.; Motmans, F.

    Laser metal deposition (LMD) is an additive manufacturing technology for the fabrication of metal parts through layerwise deposition and laser induced melting of metal powder. The poor surface finish presents a major limitation in LMD. This study focuses on the effects of surface inclination angle and strategies to improve the surface finish of LMD components. A substantial improvement in surface quality of both the side and top surfaces has been obtained by laser remelting after powder deposition.

  3. Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin

    2016-05-01

    Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

  4. Thermochemical surface engineering of steels

    DEFF Research Database (Denmark)

    Thermochemical Surface Engineering of Steels provides a comprehensive scientific overview of the principles and different techniques involved in thermochemical surface engineering, including thermodynamics, kinetics principles, process technologies and techniques for enhanced performance of steels...

  5. Liquid metals fire control engineering handbook

    International Nuclear Information System (INIS)

    Ballif, J.L.

    1979-02-01

    This handbook reviews the basic requirements of the use of liquid metals with emphasis on sodium which has the greatest current usage. It delineates the concepts necessary to design facilities both radioactive and nonradioactive for use with liquid metals. It further reviews the state-of-the-art in fire extinguishers and leak detection equipment and comments on their application and sensitivity. It also provides details on some engineering features of value to the designer of liquid metal facilities

  6. Nanoscale surface modifications of medically relevant metals: state-of-the art and perspectives

    Science.gov (United States)

    Variola, Fabio; Brunski, John B.; Orsini, Giovanna; Tambasco de Oliveira, Paulo; Wazen, Rima; Nanci, Antonio

    2011-02-01

    Evidence that nanoscale surface properties stimulate and guide various molecular and biological processes at the implant/tissue interface is fostering a new trend in designing implantable metals. Cutting-edge expertise and techniques drawn from widely separated fields, such as nanotechnology, materials engineering and biology, have been advantageously exploited to nanoengineer surfaces in ways that control and direct these processes in predictable manners. In this review, we present and discuss the state-of-the-art of nanotechnology-based approaches currently adopted to modify the surface of metals used for orthopedic and dental applications, and also briefly consider their use in the cardiovascular field. The effects of nanoengineered surfaces on various in vitro molecular and cellular events are firstly discussed. This review also provides an overview of in vivo and clinical studies with nanostructured metallic implants, and addresses the potential influence of nanotopography on biomechanical events at interfaces. Ultimately, the objective of this work is to give the readership a comprehensive picture of the current advances, future developments and challenges in the application of the infinitesimally small to biomedical surface science. We believe that an integrated understanding of the in vitro and particularly of the in vivo behavior is mandatory for the proper exploitation of nanostructured implantable metals and, indeed, of all biomaterials.

  7. Novel metal ion surface modification technique

    International Nuclear Information System (INIS)

    Brown, I.G.; Godechot, X.; Yu, K.M.

    1990-10-01

    We describe a method for applying metal ions to the near-surface region of solid materials. The added species can be energetically implanted below the surface or built up as a surface film with an atomically mixed interface with the substrate; the metal ion species can be the same as the substrate species or different from it, and more than one kind of metal species can be applied, either simultaneously or sequentially. Surface structures can be fabricated, including coatings and thin films of single metals, tailored alloys, or metallic multilayers, and they can be implanted or added onto the surface and ion beam mixed. We report two simple demonstrations of the method: implantation of yttrium into a silicon substrate at a mean energy of 70 keV and a dose of 1 x 10 16 atoms/cm 2 , and the formation of a titanium-yttrium multilayer structure with ion beam mixing to the substrate. 17 refs., 3 figs

  8. Microorganisms in heavy metal bioremediation: strategies for applying microbial-community engineering to remediate soils

    Directory of Open Access Journals (Sweden)

    Jennifer L. Wood

    2016-06-01

    Full Text Available The remediation of heavy-metal-contaminated soils is essential as heavy metals persist and do not degrade in the environment. Remediating heavy-metal-contaminated soils requires metals to be mobilized for extraction whilst, at the same time, employing strategies to avoid mobilized metals leaching into ground-water or aquatic systems. Phytoextraction is a bioremediation strategy that extracts heavy metals from soils by sequestration in plant tissues and is currently the predominant bioremediation strategy investigated for remediating heavy-metal-contaminated soils. Although the efficiency of phytoextraction remains a limiting feature of the technology, there are numerous reports that soil microorganisms can improve rates of heavy metal extraction.This review highlights the unique challenges faced when remediating heavy-metal-contaminated soils as compared to static aquatic systems and suggests new strategies for using microorganisms to improve phytoextraction. We compare how microorganisms are used in soil bioremediation (i.e. phytoextraction and water bioremediation processes, discussing how the engineering of microbial communities, used in water remediation, could be applied to phytoextraction. We briefly outline possible approaches for the engineering of soil communities to improve phytoextraction either by mobilizing metals in the rhizosphere of the plant or by promoting plant growth to increase the root-surface area available for uptake of heavy metals. We highlight the technological advances that make this research direction possible and how these technologies could be employed in future research.

  9. Surface engineering and heat treatment

    International Nuclear Information System (INIS)

    Morton, P.H.

    1991-01-01

    This book is the proceedings of a Conference organised jointly by The Institute of Metals and The Centre for Exploitation of Science and Technology (CEST). It sets out to review this role and point the way to the future by collecting together a series of invited papers written by noted authorities in their fields. The opening review by CEST highlights the economic and industrial importance of Surface Engineering and is followed by a group of four articles devoted to specific branches of industry. Several technical papers then describe various aspects of the development of heat treatment over the last twenty-five years. These are followed by papers describing advances made possible by new technologies such as plasma, laser and ion beam. A separate abstract has been prepared for a paper on materials aspects of ion beam technology. (author)

  10. Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces

    Science.gov (United States)

    Dussinger, Peter M.; Lindemuth, James E.

    1997-01-01

    The principal objective of this Phase 2 SBIR program was to develop and demonstrate a practically insoluble coating for nickel-based superalloys for Stirling engine heat pipe applications. Specific technical objectives of the program were: (1) Determine the solubility corrosion rates for Nickel 200, Inconel 718, and Udimet 72OLI in a simulated Stirling engine heat pipe environment, (2) Develop coating processes and techniques for capillary groove and screen wick structures, (3) Evaluate the durability and solubility corrosion rates for capillary groove and screen wick structures coated with an insoluble coating in cylindrical heat pipes operating under Stirling engine conditions, and (4) Design and fabricate a coated full-scale, partial segment of the current Stirling engine heat pipe for the Stirling Space Power Convertor program. The work effort successfully demonstrated a two-step nickel aluminide coating process for groove wick structures and interior wall surfaces in contact with liquid metals; demonstrated a one-step nickel aluminide coating process for nickel screen wick structures; and developed and demonstrated a two-step aluminum-to-nickel aluminide coating process for nickel screen wick structures. In addition, the full-scale, partial segment was fabricated and the interior surfaces and wick structures were coated. The heat pipe was charged with sodium, processed, and scheduled to be life tested for up to ten years as a Phase 3 effort.

  11. Nanosecond multi-pulse laser milling for certain area removal of metal coating on plastics surface

    Science.gov (United States)

    Zhao, Kai; Jia, Zhenyuan; Ma, Jianwei; Liu, Wei; Wang, Ling

    2014-12-01

    Metal coating with functional pattern on engineering plastics surface plays an important role in industry applications; it can be obtained by adding or removing certain area of metal coating on engineering plastics surface. However, the manufacturing requirements are improved continuously and the plastic substrate presents three-dimensional (3D) structure-many of these parts cannot be fabricated by conventional processing methods, and a new manufacturing method is urgently needed. As the laser-processing technology has many advantages like high machining accuracy and constraints free substrate structure, the machining of the parts is studied through removing certain area of metal coating based on the nanosecond multi-pulse laser milling. To improve the edge quality of the functional pattern, generation mechanism and corresponding avoidance strategy of the processing defects are studied. Additionally, a prediction model for the laser ablation depth is proposed, which can effectively avoid the existence of residual metal coating and reduces the damage of substrate. With the optimal machining parameters, an equiangular spiral pattern on copper-clad polyimide (CCPI) is machined based on the laser milling at last. The experimental results indicate that the edge of the pattern is smooth and consistent, the substrate is flat and without damage. The achievements in this study could be applied in industrial production.

  12. Metal Surface Modification for Obtaining Nano- and Sub-Nanostructured Protective Layers

    Science.gov (United States)

    Ledovskykh, Volodymyr; Vyshnevska, Yuliya; Brazhnyk, Igor; Levchenko, Sergiy

    2017-03-01

    Regularities of the phase protective layer formation in multicomponent systems involving inhibitors with different mechanism of protective action have been investigated. It was shown that optimization of the composition of the inhibition mixture allows to obtain higher protective efficiency owing to improved microstructure of the phase layer. It was found that mechanism of the film formation in the presence of NaNO2-PHMG is due to deposition of slightly soluble PHMG-Fe complexes on the metal surface. On the basis of the proposed mechanism, the advanced surface engineering methods for obtaining nanoscaled and sub-nanostructured functional coatings may be developed.

  13. Metrology and properties of engineering surfaces

    CERN Document Server

    Greenwood, J; Chetwynd, D

    2001-01-01

    Metrology and Properties of Engineering Surfaces provides in a single volume a comprehensive and authoritative treatment of the crucial topics involved in the metrology and properties of engineering surfaces. The subject matter is a central issue in manufacturing technology, since the quality and reliability of manufactured components depend greatly upon the selection and qualities of the appropriate materials as ascertained through measurement. The book can in broad terms be split into two parts; the first deals with the metrology of engineering surfaces and covers the important issues relating to the measurement and characterization of surfaces in both two and three dimensions. This covers topics such as filtering, power spectral densities, autocorrelation functions and the use of Fractals in topography. A significant proportion is dedicated to the calibration of scanning probe microscopes using the latest techniques. The remainder of the book deals with the properties of engineering surfaces and covers a w...

  14. Microjetting from grooved surfaces in metallic samples subjected to laser driven shocks

    Science.gov (United States)

    de Rességuier, T.; Lescoute, E.; Sollier, A.; Prudhomme, G.; Mercier, P.

    2014-01-01

    When a shock wave propagating in a solid sample reflects from a free surface, geometrical effects predominantly governed by the roughness and defects of that surface may lead to the ejection of tiny jets that may breakup into high velocity, approximately micrometer-size fragments. This process referred to as microjetting is a major safety issue for engineering applications such as pyrotechnics or armour design. Thus, it has been widely studied both experimentally, under explosive and impact loading, and theoretically. In this paper, microjetting is investigated in the specific loading conditions associated to laser shocks: very short duration of pressure application, very high strain rates, small spatial scales. Material ejection from triangular grooves in the free surface of various metallic samples is studied by combining transverse optical shadowgraphy and time-resolved velocity measurements. The influences of the main parameters (groove angle, shock pressure, nature of the metal) on jet formation and ejection velocity are quantified, and the results are compared to theoretical estimates.

  15. Microjetting from grooved surfaces in metallic samples subjected to laser driven shocks

    International Nuclear Information System (INIS)

    Rességuier, T. de; Lescoute, E.; Sollier, A.; Prudhomme, G.; Mercier, P.

    2014-01-01

    When a shock wave propagating in a solid sample reflects from a free surface, geometrical effects predominantly governed by the roughness and defects of that surface may lead to the ejection of tiny jets that may breakup into high velocity, approximately micrometer-size fragments. This process referred to as microjetting is a major safety issue for engineering applications such as pyrotechnics or armour design. Thus, it has been widely studied both experimentally, under explosive and impact loading, and theoretically. In this paper, microjetting is investigated in the specific loading conditions associated to laser shocks: very short duration of pressure application, very high strain rates, small spatial scales. Material ejection from triangular grooves in the free surface of various metallic samples is studied by combining transverse optical shadowgraphy and time-resolved velocity measurements. The influences of the main parameters (groove angle, shock pressure, nature of the metal) on jet formation and ejection velocity are quantified, and the results are compared to theoretical estimates

  16. Microjetting from grooved surfaces in metallic samples subjected to laser driven shocks

    Energy Technology Data Exchange (ETDEWEB)

    Rességuier, T. de, E-mail: resseguier@ensma.fr [Institut PPRIME, UPR 3346, CNRS, ENSMA, Université de Poitiers, 1 ave. Clément Ader, 86961 Futuroscope Cedex (France); Lescoute, E.; Sollier, A.; Prudhomme, G.; Mercier, P. [CEA, DAM, DIF, 91297 Arpajon (France)

    2014-01-28

    When a shock wave propagating in a solid sample reflects from a free surface, geometrical effects predominantly governed by the roughness and defects of that surface may lead to the ejection of tiny jets that may breakup into high velocity, approximately micrometer-size fragments. This process referred to as microjetting is a major safety issue for engineering applications such as pyrotechnics or armour design. Thus, it has been widely studied both experimentally, under explosive and impact loading, and theoretically. In this paper, microjetting is investigated in the specific loading conditions associated to laser shocks: very short duration of pressure application, very high strain rates, small spatial scales. Material ejection from triangular grooves in the free surface of various metallic samples is studied by combining transverse optical shadowgraphy and time-resolved velocity measurements. The influences of the main parameters (groove angle, shock pressure, nature of the metal) on jet formation and ejection velocity are quantified, and the results are compared to theoretical estimates.

  17. Polymer Surface Engineering for Efficient Printing of Highly Conductive Metal Nanoparticle Inks.

    Science.gov (United States)

    Agina, Elena V; Sizov, Alexey S; Yablokov, Mikhail Yu; Borshchev, Oleg V; Bessonov, Alexander A; Kirikova, Marina N; Bailey, Marc J A; Ponomarenko, Sergei A

    2015-06-10

    An approach to polymer surface modification using self-assembled layers (SALs) of functional alkoxysilanes has been developed in order to improve the printability of silver nanoparticle inks and enhance adhesion between the metal conducting layer and the flexible polymer substrate. The SALs have been fully characterized by AFM, XPS, and WCA, and the resulting printability, adhesion, and electrical conductivity of the screen-printed metal contacts have been estimated by cross-cut tape test and 4-point probe measurements. It was shown that (3-mercaptopropyl)trimethoxysilane SALs enable significant adhesion improvements for both aqueous- and organic-based silver inks, approaching nearly 100% for PEN and PDMS substrates while exhibiting relatively low sheet resistance up to 0.1 Ω/sq. It was demonstrated that SALs containing functional -SH or -NH2 end groups offer the opportunity to increase the affinity of the polymer substrates to silver inks and thus to achieve efficient patterning of highly conductive structures on flexible and stretchable substrates.

  18. Effect of engine-based thermal aging on surface morphology and performance of Lean NOx Traps

    International Nuclear Information System (INIS)

    Toops, Todd J.; Bunting, Bruce G.; Nguyen, Ke; Gopinath, Ajit

    2007-01-01

    A small single-cylinder diesel engine is used to thermally age model (Pt + Rh/Ba/γ-Al 2 O 3 ) lean NO x traps (LNTs) under lean/rich cycling at target temperatures of 600 C, 700 C, and 800 C. During an aging cycle, fuel is injected into the exhaust to achieve reproducible exotherms under lean and rich conditions with the average temperature approximating the target temperature. Aging is performed until the cycle-average NO x conversion measured at 400 C is approximately constant. Engine-based NO x conversion decreased by 42% after 60 cycles at 600 C, 36% after 76 cycles at 700 C and 57% after 46 cycles at 800 C. The catalyst samples were removed and characterized by XRD and using a microreactor that allowed controlled measurements of surface area, precious metal size, NO x storage, and reaction rates. Three aging mechanisms responsible for the deactivation of LNTs have been identified: (1) loss of dispersion of the precious metals, (2) phase transitions in the washcoat materials, and (3) loss of surface area of the storage component and support. These three mechanisms are accelerated when the aging temperature exceeds 850 C - the γ to (delta) transition temperature of Al 2 O 3 . Normalization of rates of NO reacted at 400 C to total surface area demonstrates the biggest impact on performance stems from surface area losses rather than from precious metal sintering. (author)

  19. Excimer laser irradiation of metal surfaces

    Science.gov (United States)

    Kinsman, Grant

    In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

  20. Plastic Deformation of Metal Surfaces

    DEFF Research Database (Denmark)

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2013-01-01

    of metal components. An optimization of processes and material parameters must be based on a quantification of stress and strain gradients at the surface and in near surface layer where the structural scale can reach few tens of nanometers. For such fine structures it is suggested to quantify structural...... parameters by TEM and EBSD and apply strength-structural relationships established for the bulk metal deformed to high strains. This technique has been applied to steel deformed by high energy shot peening and a calculated stress gradient at or near the surface has been successfully validated by hardness...

  1. Selective metal-vapor deposition on solvent evaporated polymer surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Koji; Tsujioka, Tsuyoshi, E-mail: tsujioka@cc.osaka-kyoiku.ac.jp

    2015-12-31

    We report a selective metal-vapor deposition phenomenon based on solvent printing and evaporation on polymer surfaces and propose a method to prepare fine metal patterns using maskless vacuum deposition. Evaporation of the solvent molecules from the surface caused large free volumes between surface polymer chains and resulted in high mobility of the chains, enhancing metal-vapor atom desorption from the surface. This phenomenon was applied to prepare metal patterns on the polymer surface using solvent printing and maskless metal vacuum deposition. Metal patterns with high resolution of micron scale were obtained for various metal species and semiconductor polymer substrates including poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] and poly(3-hexylthiophene-2,5-diyl). - Highlights: • Selective metal-vapor deposition using solvent evaporation on polymer was attained. • Metal patterns with high resolution were obtained for various metal species. • This method can be applied to achieve fine metal-electrodes for polymer electronics.

  2. Organometallic chemistry of metal surfaces

    International Nuclear Information System (INIS)

    Muetterties, E.L.

    1981-06-01

    The organometallic chemistry of metal surfaces is defined as a function of surface crystallography and of surface composition for a set of cyclic hydrocarbons that include benzene, toluene, cyclohexadienes, cyclohexene, cyclohexane, cyclooctatetraene, cyclooctadienes, cyclooctadiene, cycloheptatriene and cyclobutane. 12 figures

  3. Process for cleaning radioactively contaminated metal surfaces

    International Nuclear Information System (INIS)

    Mihram, R.G.; Snyder, G.A.

    1975-01-01

    A process is described for removing radioactive scale from a ferrous metal surface, including the steps of initially preconditioning the surface by contacting it with an oxidizing solution (such as an aqueous solution of an alkali metal permanganate or hydrogen peroxide), then, after removal or decomposition of the oxidizing solution, the metallic surface is contacted with a cleaning solution which is a mixture of a mineral acid and a complexing agent (such as sulfuric acid and oxalic acid), and which preferably contains a corrosion inhibitor. A final step in the process is the treatment of the spent cleaning solution containing radioactive waste materials in solution by adding a reagent selected from the group consisting of calcium hydroxide or potassium permanganate and an alkali metal hydroxide to thereby form easily recovered metallic compounds containing substantially all of the dissolved metals and radioactivity. (auth)

  4. Geometry of surfaces a practical guide for mechanical engineers

    CERN Document Server

    Radzevich, Stephen P

    2012-01-01

    Presents an in-depth analysis of geometry of part surfaces and provides the tools for solving complex engineering problems Geometry of Surfaces: A Practical Guide for Mechanical Engineers is a comprehensive guide to applied geometry of surfaces with focus on practical applications in various areas of mechanical engineering. The book is divided into three parts on Part Surfaces, Geometry of Contact of Part Surfaces and Mapping of the Contacting Part Surfaces. Geometry of Surfaces: A Practical Guide for Mechanical Engineers combines differential geometry and gearing theory and presents new developments in the elementary theory of enveloping surfaces. Written by a leading expert of the field, this book also provides the reader with the tools for solving complex engineering problems in the field of mechanical engineering. Presents an in-depth analysis of geometry of part surfaces Provides tools for solving complex engineering problems in the field of mechanical engineering Combines differential geometry an...

  5. Assessment of engineered surfaces roughness by high-resolution 3D SEM photogrammetry.

    Science.gov (United States)

    Gontard, L C; López-Castro, J D; González-Rovira, L; Vázquez-Martínez, J M; Varela-Feria, F M; Marcos, M; Calvino, J J

    2017-06-01

    We describe a methodology to obtain three-dimensional models of engineered surfaces using scanning electron microscopy and multi-view photogrammetry (3DSEM). For the reconstruction of the 3D models of the surfaces we used freeware available in the cloud. The method was applied to study the surface roughness of metallic samples patterned with parallel grooves by means of laser. The results are compared with measurements obtained using stylus profilometry (PR) and SEM stereo-photogrammetry (SP). The application of 3DSEM is more time demanding than PR or SP, but it provides a more accurate representation of the surfaces. The results obtained with the three techniques are compared by investigating the influence of sampling step on roughness parameters. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Surface engineering and environmental issues

    International Nuclear Information System (INIS)

    Aguero, A.

    2007-01-01

    Surface engineering addresses the modification of the microstructure and/or composition of the surface of components by mechanical, physical or chemical methods that may imply adding a material in order to change the surface properties of said components. One of its most important consequences is the significant increase of the useful life of a variety of components in a large number of industrial applications. Moreover, it contributes to energy savings by increasing efficiencies as it allows higher combustion temperatures, by allowing the use of lighter components and by significant friction reduction. In this paper, surface engineering is introduced, as well as its different modalities, examples of industrial applications and positive and negative environmental impacts. (Author) 29 refs

  7. Nano-metal Oxides: Exposure and Engineering Control Assessment

    OpenAIRE

    Garcia, Alberto; Sparks, Christopher; Martinez, Kenneth; Topmiller, Jennifer L.; Eastlake, Adrienne; Geraci, Charles L.

    2017-01-01

    This paper discusses the evaluation of a facility that produces high quality engineered nanomaterials. These ENMs consist of various metals including iron, nickel, silver, manganese, and palladium. Although occupational exposure levels are not available for these metals, studies have indicated that it may be prudent to keep exposures to the nano-scale metal as low as possible. Previous In vitro studies indicated that in comparison with a material’s larger (parent) counterpart, nanomaterials c...

  8. Metal/graphite - composites in fusion engineering

    International Nuclear Information System (INIS)

    Staffler, R.; Kneringer, G.; Kny, E.; Reheis, N.

    1995-01-01

    Metal/graphite composites have been well known in medical industry for many years. X-ray tubes used in modern radiography, particulary in computerized tomography are equipped with rotating targets able to absorb a maximum of heat in a given time. Modern rotating targets consist of a refractory metal/graphite composite. Today the use of graphite as a plasma facing material is one predominant concept in fusion engineering. Depending on the thermal load, the graphite components have to be directly cooled (i.e. divertor plates) or inertially cooled (i.e. firstwall tiles). In case of direct cooling a metallurgical joining such as high temperature brazing between graphite and a metalic cooling structure shows the most promising results /1/. Inertially cooled graphite tiles have to be joined to a metallic backing plate in order to get a stable attachment to the supporting structure. The main requirements on the metallic partner of a metal/graphite composite and in the first wall area are: high melting point, high thermal strength, high thermal conductivity, low vapour pressure and a thermal expansion matching that of graphite. These properties are typical for the refractory metals such as molybdenum, tungsten and their alloys. (author)

  9. Engineering kinetic barriers in copper metallization

    International Nuclear Information System (INIS)

    Huang Hanchen; Wei, H.L.; Woo, C.H.; Zhang, X.X.

    2002-01-01

    In metallization processes of integrated circuits, it is desirable to deposit the metal lines (aluminum or copper) fast and at low temperatures. However, the lines (films) usually consist of undesirable columns and voids, because of the absence of sufficient diffusion--a direct result of large kinetic barriers. Following the proposal and realization of the three-dimensional Ehrlich-Schwoebel (3D ES) barrier, we present here a method to engineer this kinetic barrier so as to improve quality of deposited copper films. We deposit copper films by magnetron sputtering, characterize the film structure and texture by using the scanning electron microscope and the x-ray diffraction, respectively. Taking indium as surfactant during copper deposition, we have achieved much better density and bottom coverage of copper filled trenches. The characterizations show that the improvement is the result of the 3D ES barrier reduction caused by indium addition. Engineering the 3D ES barrier therefore leads to improved film quality

  10. The surface energy of metals

    DEFF Research Database (Denmark)

    Vitos, Levente; Ruban, Andrei; Skriver, Hans Lomholt

    1998-01-01

    We have used density functional theory to establish a database of surface energies for low index surfaces of 60 metals in the periodic table. The data may be used as a consistent starting point for models of surface science phenomena. The accuracy of the database is established in a comparison...

  11. Laser modification of macroscopic properties of metal surface layer

    Science.gov (United States)

    Kostrubiec, Franciszek

    1995-03-01

    Surface laser treatment of metals comprises a number of diversified technological operations out of which the following can be considered the most common: oxidation and rendering surfaces amorphous, surface hardening of steel, modification of selected physical properties of metal surface layers. In the paper basic results of laser treatment of a group of metals used as base materials for electric contacts have been presented. The aim of the study was to test the usability of laser treatment from the viewpoint of requirements imposed on materials for electric contacts. The results presented in the paper refer to two different surface treatment technologies: (1) modification of infusible metal surface layer: tungsten and molybdenum through laser fusing of their surface layer and its crystallization, and (2) modification of surface layer properties of other metals through laser doping of their surface layer with foreign elements. In the paper a number of results of experimental investigations obtained by the team under the author's supervision are presented.

  12. Surface engineering for enhanced performance against wear

    CERN Document Server

    2013-01-01

    Surface Engineering constitutes a variety of processes and sub processes. Each chapter of this work covers specific processes by experts working in the area. Included for each topic are tribological performances for each process as well as results of recent research. The reader also will benefit from in-depth studies of diffusion coatings, nanocomposite films for wear resistance, surfaces for biotribological applications, thin-film wear, tribology of thermal sprayed coatings, hardfacing, plating for tribology and high energy beam surface modifications. Material scientists as well as engineers working with surface engineering for tribology will be particularly interested in this work.

  13. Engineering Metallic Nanoparticles for Enhancing and Probing Catalytic Reactions.

    Science.gov (United States)

    Collins, Gillian; Holmes, Justin D

    2016-07-01

    Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications. The engineering of future heterogenous catalysts is also moving beyond size, shape and composition considerations. Advancements in understanding structure-property relationships have enabled incorporation of complex features such as tuning surface strain to influence the behavior of catalytic NPs. Exploiting plasmonic properties and altering colloidal surface chemistry through functionalization are also emerging as important areas for rational design of catalytic NPs. This news article will highlight the key developments and challenges to the future design of catalytic NPs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Surface energy of metal alloy nanoparticles

    Science.gov (United States)

    Takrori, Fahed M.; Ayyad, Ahmed

    2017-04-01

    The measurement of surface energy of alloy nanoparticles experimentally is still a challenge therefore theoretical work is necessary to estimate its value. In continuation of our previous work on the calculation of the surface energy of pure metallic nanoparticles we have extended our work to calculate the surface energy of different alloy systems, namely, Co-Ni, Au-Cu, Cu-Al, Cu-Mg and Mo-Cs binary alloys. It is shown that the surface energy of metallic binary alloy decreases with decreasing particle size approaching relatively small values at small sizes. When both metals in the alloy obey the Hume-Rothery rules, the difference in the surface energy is small at the macroscopic as well as in the nano-scale. However when the alloy deviated from these rules the difference in surface energy is large in the macroscopic and in the nano scales. Interestingly when solid solution formation is not possible at the macroscopic scale according to the Hume-Rothery rules, it is shown it may form at the nano-scale. To our knowledge these findings here are presented for the first time and is challenging from fundamental as well as technological point of views.

  15. Ultra-fast boriding of metal surfaces for improved properties

    Science.gov (United States)

    Timur, Servet; Kartal, Guldem; Eryilmaz, Osman L.; Erdemir, Ali

    2015-02-10

    A method of ultra-fast boriding of a metal surface. The method includes the step of providing a metal component, providing a molten electrolyte having boron components therein, providing an electrochemical boriding system including an induction furnace, operating the induction furnace to establish a high temperature for the molten electrolyte, and boriding the metal surface to achieve a boride layer on the metal surface.

  16. Effect of heavy metals on soil mineral surfaces and bioretention pond performance

    Science.gov (United States)

    Zhang, H.; Olson, M. S.

    2009-12-01

    Haibo Zhang and Mira S. Olson Department of Civil, Architectural, and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 As urban stormwater runoff flows across impervious surfaces, it collects and accumulates pollutants that are detrimental to the quality of local receiving water bodies. Heavy metal pollution, such as copper, lead and zinc, has been a concern in urban stormwater runoff. In addition, the presence of bacteria in stormwater has been frequently reported. The co-existence of both heavy metals and bacteria in stormwater and their complex interactions determine their transport and removal through bioretention pond. Stormwater runoff was sampled from a bioretention pond in Philadelphia, PA. The concentration of copper, lead and zinc were measured as 0.086ppm, 0.083ppm and 0.365ppm, respectively. Batch experiments were conducted with solutions of pure copper, lead and zinc, and with a synthetic stormwater solution amended with copper, lead and zinc. The solution was buffered to pH 7, within the range of the observed stormwater pH. In pure heavy metal solutions, the sorption of copper, lead and zinc onto soil are 96%, 99% and 85%, respectively. In synthetic stormwater containing nutrients and all three metals, the sorption of lead is 97%, while copper and zinc decrease to 29% and 71%, respectively. Mineralogy of a soil sample taken from the bioretention pond was analyzed using a scanning electron microscope (SEM) and compared before and after sorption experiments. Sorption and complexation of heavy metals is likely to change the mineralogy of soil particle surfaces, which will affect the attachment of bacteria and therefore its transport through soil. This study will benefit long-term predictions of the performance of bioretention ponds for urban stormwater runoff treatment. Keyword: Heavy metal pollution, sorption, surface complexation, urban stormwater runoff, bioretention pond

  17. Product Surfaces in Precision Engineering, Micorengineering and Nanotechnology

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Kunzmann, H.; Peggs, G. N.

    2005-01-01

    This paper is and excerpt from a recently published CIRP Key-Note paper on surfaces in Precision Engineering, Micorengineering and Nanotechnology [1]. It is focussed on the relevance of surface metrology at the micrometric and nanometric length scales. The applied measurement technologies...... are strongly dependent from the functional requirements on those surfaces. Examples of surfaces obtained with precision engineering, microengineering and nanotechnology are mentioned, encompassing surfaces in computers, MEMS, biomedical systems, ligth and X-ray optics, as well as in chemical systems. Surface...... in surface metrology at micro and nanoscale are strongly required for future progress of Precision Engineering, Microengineering, and Nanotechnology; and their fundamental importance can not be overestimated....

  18. Metal/graphite - composites in fusion engineering

    International Nuclear Information System (INIS)

    Staffler, R.; Kneringer, G.; Kny, E.; Reheis, N.

    1989-01-01

    Metal/graphite composites have been well known in medical industry for many years. X-ray tubes used in modern radiography, particularly in computerized tomography are equipped with rotating targets able to absorb a maximum of heat in a given time. Modern rotating targets consist of a refractory metal/graphite composite. Today the use of graphite as a plasma facing material is one predominant concept in fusion engineering. Depending on the thermal load, the graphite components have to be directly cooled (i.e. divertor plates) or inertially cooled (i.e. firstwall tiles). In case of direct cooling a metallurgical joining such as high temperature brazing between graphite and a metallic cooling structure shows the most promising results /1/. Inertially cooled graphite tiles have to be joined to a metallic backing plate in order to get a stable attachment to the supporting structure. The main requirements on the metallic partner of a metal/graphite composite used in the first wall area are: high melting point, high thermal strength, high thermal conductivity, low vapor pressure and a thermal expansion matching that of graphite. These properties are typical for the refractory metals such as molybdenum, tungsten and their alloys. 4 refs., 13 figs., 1 tab

  19. Plasmonic engineering of metal-oxide nanowire heterojunctions in integrated nanowire rectification units

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Luchan; Zhou, Y. Norman, E-mail: liulei@tsinghua.edu.cn, E-mail: nzhou@uwaterloo.ca [Department of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Zou, Guisheng; Liu, Lei, E-mail: liulei@tsinghua.edu.cn, E-mail: nzhou@uwaterloo.ca [Department of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Duley, Walt W. [Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2016-05-16

    We show that irradiation with femtosecond laser pulses can produce robust nanowire heterojunctions in coupled non-wetting metal-oxide Ag-TiO{sub 2} structures. Simulations indicate that joining arises from the effect of strong plasmonic localization in the region of the junction. Strong electric field effects occur in both Ag and TiO{sub 2} resulting in the modification of both surfaces and an increase in wettability of TiO{sub 2}, facilitating the interconnection of Ag and TiO{sub 2} nanowires. Irradiation leads to the creation of a thin layer of highly defected TiO{sub 2} in the contact region between the Ag and TiO{sub 2} nanowires. The presence of this layer allows the formation of a heterojunction and offers the possibility of engineering the electronic characteristics of interfacial structures. Rectifying junctions with single and bipolar properties have been generated in Ag-TiO{sub 2} nanowire circuits incorporating asymmetrical and symmetrical interfacial structures, respectively. This fabrication technique should be applicable for the interconnection of other heterogeneous metal-oxide nanowire components and demonstrates that femtosecond laser irradiation enables interfacial engineering for electronic applications of integrated nanowire structures.

  20. Plasmonic engineering of metal-oxide nanowire heterojunctions in integrated nanowire rectification units

    Science.gov (United States)

    Lin, Luchan; Zou, Guisheng; Liu, Lei; Duley, Walt W.; Zhou, Y. Norman

    2016-05-01

    We show that irradiation with femtosecond laser pulses can produce robust nanowire heterojunctions in coupled non-wetting metal-oxide Ag-TiO2 structures. Simulations indicate that joining arises from the effect of strong plasmonic localization in the region of the junction. Strong electric field effects occur in both Ag and TiO2 resulting in the modification of both surfaces and an increase in wettability of TiO2, facilitating the interconnection of Ag and TiO2 nanowires. Irradiation leads to the creation of a thin layer of highly defected TiO2 in the contact region between the Ag and TiO2 nanowires. The presence of this layer allows the formation of a heterojunction and offers the possibility of engineering the electronic characteristics of interfacial structures. Rectifying junctions with single and bipolar properties have been generated in Ag-TiO2 nanowire circuits incorporating asymmetrical and symmetrical interfacial structures, respectively. This fabrication technique should be applicable for the interconnection of other heterogeneous metal-oxide nanowire components and demonstrates that femtosecond laser irradiation enables interfacial engineering for electronic applications of integrated nanowire structures.

  1. Effect of Strain on the Reactivity of Metal Surfaces

    DEFF Research Database (Denmark)

    Mavrikakis, Manos; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Self-consistent density functional calculations for the adsorption of O and CO, and the dissociation of CO on strained and unstrained Ru(0001) surfaces are used to show how strained metal surfaces have chemical properties that are significantly different from those of unstrained surfaces. Surface...... reactivity increases with lattice expansion, following a concurrent up-shift of the metal d states. Consequences for the catalytic activity of thin metal overlayers are discussed....

  2. The Performance of Chrome-Coated Copper as Metallic Catalytic Converter to Reduce Exhaust Gas Emissions from Spark-Ignition Engine

    Science.gov (United States)

    Warju; Harto, S. P.; Soenarto

    2018-01-01

    One of the automotive technologies to reduce exhaust gas emissions from the spark-ignition engine (SIE) is by using a catalytic converter. The aims of this research are firstly to conduct a metallic catalytic converter, secondly to find out to what extend chrome-coated copper plate (Cu+Cr) as a catalyst is efficient. To measure the concentration of carbon monoxide (CO) and hydrocarbon (HC) on the frame there are two conditions required. First is when the standard condition, and second is when Cu+Cr metallic catalytic converter is applied using exhaust gas analyzer. Exhaust gas emissions from SIE are measured by using SNI 19-7118.1-2005. The testing of CO and HC emissions were conducted with variable speed to find the trend of exhaust gas emissions from idle speed to high speed. This experiment results in the fact that the use of Cu+Cr metallic catalytic converter can reduce the production of CO and HC of a four-stroke gasoline engine. The reduction of CO and HC emission are 95,35% and 79,28%. Using active metal catalyst in form of metallic catalytic converter, it is gained an optimum effective surface of a catalyst which finally is able to decrease the amount of CO and HC emission significantly in every spinning happened in the engine. Finally, this technology can be applied to the spark ignition engine both car and motorcycle to support blue sky program in Indonesia.

  3. Determination of Surface Properties of Liquid Transition Metals

    International Nuclear Information System (INIS)

    Korkmaz, S. D.

    2008-01-01

    Certain surface properties of liquid simple metals are reported. Using the expression derived by Gosh and coworkers we investigated the surface entropy of liquid transition metals namely Fe, Co and Ni. We have also computed surface tensions of the metals concerned. The pair distribution functions are calculated from the solution of Ornstein-Zernike integral equation with Rogers-Young closure using the individual version of the electron-ion potential proposed by Fioalhais and coworkers which was originally developed for solid state. The predicted values of surface tension and surface entropy are in very good agreement with available experimental data. The present study results show that the expression derived by Gosh and coworkers is very useful for the surface entropy by using Fioalhais pseudopotential and Rogers-Young closure

  4. Modeling nanostructural surface modifications in metal cutting by an approach of thermodynamic irreversibility: Derivation and experimental validation

    Science.gov (United States)

    Buchkremer, S.; Klocke, F.

    2017-01-01

    Performance and operational safety of many metal parts in engineering depend on their surface integrity. During metal cutting, large thermomechanical loads and high gradients of the loads concerning time and location act on the surfaces and may yield significant structural material modifications, which alter the surface integrity. In this work, the derivation and validation of a model of nanostructural surface modifications in metal cutting are presented. For the first time in process modeling, initiation and kinetics of these modifications are predicted using a thermodynamic potential, which considers the interdependent developments of plastic work, dissipation, heat conduction and interface energy as well as the associated productions and flows of entropy. The potential is expressed based on the free Helmholtz energy. The irreversible thermodynamic state changes in the workpiece surface are homogenized over the volume in order to bridge the gap between discrete phenomena involved with the initiation and kinetics of dynamic recrystallization and its macroscopic implications for surface integrity. The formulation of the thermodynamic potential is implemented into a finite element model of orthogonal cutting of steel AISI 4140. Close agreement is achieved between predicted nanostructures and those obtained in transmission electron microscopical investigations of specimen produced in cutting experiments.

  5. Ab initio lattice dynamics of metal surfaces

    International Nuclear Information System (INIS)

    Heid, R.; Bohnen, K.-P.

    2003-01-01

    Dynamical properties of atoms on surfaces depend sensitively on their bonding environment and thus provide valuable insight into the local geometry and chemical binding at the boundary of a solid. Density-functional theory provides a unified approach to the calculation of structural and dynamical properties from first principles. Its high accuracy and predictive power for lattice dynamical properties of semiconductor surfaces has been demonstrated in a previous article by Fritsch and Schroeder (Phys. Rep. 309 (1999) 209). In this report, we review the state-of-the-art of these ab initio approaches to surface dynamical properties of metal surfaces. We give a brief introduction to the conceptual framework with focus on recent advances in computational procedures for the ab initio linear-response approach, which have been a prerequisite for an efficient treatment of surface dynamics of noble and transition metals. The discussed applications to clean and adsorbate-covered surfaces demonstrate the high accuracy and reliability of this approach in predicting detailed microscopic properties of the phonon dynamics for a wide range of metallic surfaces

  6. Tunable reactivity of supported single metal atoms by impurity engineering of the MgO(001) support.

    Science.gov (United States)

    Pašti, Igor A; Johansson, Börje; Skorodumova, Natalia V

    2018-02-28

    Development of novel materials may often require a rational use of high price components, like noble metals, in combination with the possibility to tune their properties in a desirable way. Here we present a theoretical DFT study of Au and Pd single atoms supported by doped MgO(001). By introducing B, C and N impurities into the MgO(001) surface, the interaction between the surface and the supported metal adatoms can be adjusted. Impurity atoms act as strong binding sites for Au and Pd adatoms and can help to produce highly dispersed metal particles. The reactivity of metal atoms supported by doped MgO(001), as probed by CO, is altered compared to their counterparts on pristine MgO(001). We find that Pd atoms on doped MgO(001) are less reactive than on perfect MgO(001). In contrast, Au adatoms bind CO much more strongly when placed on doped MgO(001). In the case of Au on N-doped MgO(001) we find that charge redistribution between the metal atom and impurity takes place even when not in direct contact, which enhances the interaction of Au with CO. The presented results suggest possible ways for optimizing the reactivity of oxide supported metal catalysts through impurity engineering.

  7. Wireless Metal Detection and Surface Coverage Sensing for All-Surface Induction Heating

    Directory of Open Access Journals (Sweden)

    Veli Tayfun Kilic

    2016-03-01

    Full Text Available All-surface induction heating systems, typically comprising small-area coils, face a major challenge in detecting the presence of a metallic vessel and identifying its partial surface coverage over the coils to determine which of the coils to power up. The difficulty arises due to the fact that the user can heat vessels made of a wide variety of metals (and their alloys. To address this problem, we propose and demonstrate a new wireless detection methodology that allows for detecting the presence of metallic vessels together with uniquely sensing their surface coverages while also identifying their effective material type in all-surface induction heating systems. The proposed method is based on telemetrically measuring simultaneously inductance and resistance of the induction coil coupled with the vessel in the heating system. Here, variations in the inductance and resistance values for an all-surface heating coil loaded by vessels (made of stainless steel and aluminum at different positions were systematically investigated at different frequencies. Results show that, independent of the metal material type, unique identification of the surface coverage is possible at all freqeuncies. Additionally, using the magnitude and phase information extracted from the coupled coil impedance, unique identification of the vessel effective material is also achievable, this time independent of its surface coverage.

  8. Surface energy and work function of elemental metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1992-01-01

    and noble metals, as derived from the surface tension of liquid metals. In addition, they give work functions which agree with the limited experimental data obtained from single crystals to within 15%, and explain the smooth behavior of the experimental work functions of polycrystalline samples......We have performed an ab initio study of the surface energy and the work function for six close-packed surfaces of 40 elemental metals by means of a Green’s-function technique, based on the linear-muffin-tin-orbitals method within the tight-binding and atomic-sphere approximations. The results...... are in excellent agreement with a recent full-potential, all-electron, slab-supercell calculation of surface energies and work functions for the 4d metals. The present calculations explain the trend exhibited by the surface energies of the alkali, alkaline earth, divalent rare-earth, 3d, 4d, and 5d transition...

  9. Surface Modification of α-Fe Metal Particles by Chemical Surface Coating

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The structure of α-Fe metal magnetic recording particles coated with silane coupling agents have been studied by TEM, FT-IR, EXAFS, Mossbauer. The results show that a close, uniform, firm and ultra thin layer, which is beneficial to the magnetic and chemical stability, has been formed by the cross-linked chemical bond Si-O-Si. And the organic molecule has chemically bonded to the particle surface, which has greatly affected the surface Fe atom electronic structure. Furthermore, the covalent bond between metal particle surface and organic molecule has obvious effect on the near edge structure of the surface Fe atoms.

  10. Photoionization microscopy of hydrogen atom near a metal surface

    International Nuclear Information System (INIS)

    Yang Hai-Feng; Wang Lei; Liu Xiao-Jun; Liu Hong-Ping

    2011-01-01

    We have studied the ionization of Rydberg hydrogen atom near a metal surface with a semiclassical analysis of photoionization microscopy. Interference patterns of the electron radial distribution are calculated at different scaled energies above the classical saddle point and at various atom—surface distances. We find that different types of trajectories contribute predominantly to different manifolds in a certain interference pattern. As the scaled energy increases, the structure of the interference pattern evolves smoothly and more types of trajectories emerge. As the atom approaches the metal surface closer, there are more types of trajectories contributing to the interference pattern as well. When the Rydberg atom comes very close to the metal surface or the scaled energy approaches the zero field ionization energy, the potential induced by the metal surface will make atomic system chaotic. The results also show that atoms near a metal surface exhibit similar properties like the atoms in the parallel electric and magnetic fields. (atomic and molecular physics)

  11. From metallurgical coatings to surface engineering

    International Nuclear Information System (INIS)

    Sproul, William D.

    2003-01-01

    The history of the Vacuum Metallurgy Division (VMD), which is now the Advanced Surface Engineering Division (ASED), of the American Vacuum Society is reviewed briefly. The focus of the VMD moved from vacuum melting of materials to metallurgical coatings. The division sponsored two conferences, the Conference on Vacuum Metallurgy and the International Conference on Metallurgical Coatings. As the interest in vacuum metallurgy eventually subsided, interest grew in the deposition of metallurgical coatings. However, the emphasis at the Metallurgical Coatings conference has changed from just depositing coatings to surface engineering of a component. Today, the challenge is to use the tools of surface engineering with advances in deposition technology such as high-power pulsed sputtering. To align itself with the changing interests of the majority of its members, the VMD changed its name to the ASED

  12. Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics

    Directory of Open Access Journals (Sweden)

    Shutthanandan V

    2008-06-01

    Full Text Available Abstract Molybdenum disulfide (MoS2, a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia. The present work was performed to understand thermal oxidation and metal-insertion processes of molybdenite surfaces. The analysis was performed using atomic force microscopy (AFM, scanning electron microscopy (SEM, transmission electron microscopy (TEM, Rutherford backscattering spectrometry (RBS, and nuclear reaction analysis (NRA. Structural studies using SEM and TEM indicate the local-disordering of the structure as a result of charge-transfer process between the inserted lithium and the molybdenite layer. Selected area electron diffraction measurements indicate the large variations in the diffusivity of lithium confirming that the charge-transfer is different along and perpendicular to the layers in molybdenite. Thermal heating of molybenite surface in air at 400°C induces surface oxidation, which is slow during the first hour of heating and then increases significantly. The SEM results indicate that the crystals formed on the molybdenite surface as a result of thermal oxidation exhibit regular thin-elongated shape. The average size and density of the crystals on the surface is dependent on the time of annealing; smaller size and high density during the first one-hour and

  13. Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics.

    Science.gov (United States)

    Ramana, C V; Becker, U; Shutthanandan, V; Julien, C M

    2008-06-05

    Molybdenum disulfide (MoS2), a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia.The present work was performed to understand thermal oxidation and metal-insertion processes of molybdenite surfaces. The analysis was performed using atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA).Structural studies using SEM and TEM indicate the local-disordering of the structure as a result of charge-transfer process between the inserted lithium and the molybdenite layer. Selected area electron diffraction measurements indicate the large variations in the diffusivity of lithium confirming that the charge-transfer is different along and perpendicular to the layers in molybdenite. Thermal heating of molybenite surface in air at 400 degrees C induces surface oxidation, which is slow during the first hour of heating and then increases significantly. The SEM results indicate that the crystals formed on the molybdenite surface as a result of thermal oxidation exhibit regular thin-elongated shape. The average size and density of the crystals on the surface is dependent on the time of annealing; smaller size and high density during the first one-hour and significant

  14. Large-Area Direct Laser-Shock Imprinting of a 3D Biomimic Hierarchical Metal Surface for Triboelectric Nanogenerators.

    Science.gov (United States)

    Jin, Shengyu; Wang, Yixiu; Motlag, Maithilee; Gao, Shengjie; Xu, Jin; Nian, Qiong; Wu, Wenzhuo; Cheng, Gary J

    2018-03-01

    Ongoing efforts in triboelectric nanogenerators (TENGs) focus on enhancing power generation, but obstacles concerning the economical and cost-effective production of TENGs continue to prevail. Micro-/nanostructure engineering of polymer surfaces has been dominantly utilized for boosting the contact triboelectrification, with deposited metal electrodes for collecting the scavenged energy. Nevertheless, this state-of-the-art approach is limited by the vague potential for producing 3D hierarchical surface structures with conformable coverage of high-quality metal. Laser-shock imprinting (LSI) is emerging as a potentially scalable approach for directly surface patterning of a wide range of metals with 3D nanoscale structures by design, benefiting from the ultrahigh-strain-rate forming process. Here, a TENG device is demonstrated with LSI-processed biomimetic hierarchically structured metal electrodes for efficient harvesting of water-drop energy in the environment. Mimicking and transferring hierarchical microstructures from natural templates, such as leaves, into these water-TENG devices is effective regarding repelling water drops from the device surface, since surface hydrophobicity from these biomicrostructures maximizes the TENG output. Among various leaves' microstructures, hierarchical microstructures from dried bamboo leaves are preferable regarding maximizing power output, which is attributed to their unique structures, containing both dense nanostructures and microscale features, compared with other types of leaves. Also, the triboelectric output is significantly improved by closely mimicking the hydrophobic nature of the leaves in the LSI-processed metal surface after functionalizing it with low-surface-energy self-assembled-monolayers. The approach opens doors to new manufacturable TENG technologies for economically feasible and ecologically friendly production of functional devices with directly patterned 3D biomimic metallic surfaces in energy

  15. Rigid multipodal platforms for metal surfaces

    Directory of Open Access Journals (Sweden)

    Michal Valášek

    2016-03-01

    Full Text Available In this review the recent progress in molecular platforms that form rigid and well-defined contact to a metal surface are discussed. Most of the presented examples have at least three anchoring units in order to control the spatial arrangement of the protruding molecular subunit. Another interesting feature is the lateral orientation of these foot structures which, depending on the particular application, is equally important as the spatial arrangement of the molecules. The numerous approaches towards assembling and organizing functional molecules into specific architectures on metal substrates are reviewed here. Particular attention is paid to variations of both, the core structures and the anchoring groups. Furthermore, the analytical methods enabling the investigation of individual molecules as well as monomolecular layers of ordered platform structures are summarized. The presented multipodal platforms bearing several anchoring groups form considerably more stable molecule–metal contacts than corresponding monopodal analogues and exhibit an enlarged separation of the functional molecules due to the increased footprint, as well as restrict tilting of the functional termini with respect to the metal surface. These platforms are thus ideally suited to tune important properties of the molecule–metal interface. On a single-molecule level, several of these platforms enable the control over the arrangement of the protruding rod-type molecular structures (e.g., molecular wires, switches, rotors, sensors with respect to the surface of the substrate.

  16. He atom surface spectroscopy: Surface lattice dynamics of insulators, metals and metal overlayers

    International Nuclear Information System (INIS)

    1990-01-01

    During the first three years of this grant (1985--1988) the effort was devoted to the construction of a state-of-the-art He atom scattering (HAS) instrument which would be capable of determining the structure and dynamics of metallic, semiconductor or insulator crystal surfaces. The second three year grant period (1988--1991) has been dedicated to measurements. The construction of the instrument went better than proposed; it was within budget, finished in the proposed time and of better sensitivity and resolution than originally planned. The same success has been carried over to the measurement phase where the concentration has been on studies of insulator surfaces, as discussed in this paper. The experiments of the past three years have focused primarily on the alkali halides with a more recent shift to metal oxide crystal surfaces. Both elastic and inelastic scattering experiments were carried out on LiF, NaI, NaCl, RbCl, KBr, RbBr, RbI, CsF, CsI and with some preliminary work on NiO and MgO

  17. Magical Engineering Plastic

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gwang Ung

    1988-01-15

    This book introduces engineering plastic about advantage of engineering plastic, plastic material from processing method, plastic shock, plastic until now, background of making of engineering plastic, wonderful engineering plastic science such as a high molecule and molecule, classification of high molecule, difference between metal and high molecule, heat and high molecule materials, and property of surface, engineering plastic of dream like from linseed oil to aramid, small dictionary of engineering plastic.

  18. Magical Engineering Plastic

    International Nuclear Information System (INIS)

    Kim, Gwang Ung

    1988-01-01

    This book introduces engineering plastic about advantage of engineering plastic, plastic material from processing method, plastic shock, plastic until now, background of making of engineering plastic, wonderful engineering plastic science such as a high molecule and molecule, classification of high molecule, difference between metal and high molecule, heat and high molecule materials, and property of surface, engineering plastic of dream like from linseed oil to aramid, small dictionary of engineering plastic.

  19. Nano surface engineering of Mn 2 O 3 for potential light-harvesting application

    KAUST Repository

    Kar, Prasenjit; Sardar, Samim; Ghosh, Srabanti; Parida, Manas R.; Liu, Bo; Mohammed, Omar F.; Lemmens, Peter; Pal, Samir Kumar

    2015-01-01

    Manganese oxides are well known applied materials including their use as efficient catalysts for various environmental applications. Multiple oxidation states and their change due to various experimental conditions are concluded to be responsible for their multifaceted functionality. Here we demonstrate that the interaction of a small organic ligand with one of the oxide varieties induces completely new optical properties and functionalities (photocatalysis). We have synthesized Mn2O3 microspheres via a hydrothermal route and characterized them using scanning electron microscopy (SEM), X-ray diffraction (XRD) and elemental mapping (EDAX). When the microspheres are allowed to interact with the biologically important small ligand citrate, nanometer-sized surface functionalized Mn2O3 (NPs) are formed. Raman and Fourier transformed infrared spectroscopy confirm the covalent attachment of the citrate ligand to the dangling bond of Mn at the material surface. While cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) analysis confirm multiple surface charge states after the citrate functionalization of the Mn2O3 NPs, new optical properties of the surface engineered nanomaterials in terms of absorption and emission emerge consequently. The engineered material offers a novel photocatalytic functionality to the model water contaminant methylene blue (MB). The effect of doping other metal ions including Fe3+ and Cu2+ on the optical and catalytic properties is also investigated. In order to prepare a prototype for potential environmental application of water decontamination, we have synthesized and duly functionalized the material on the extended surface of a stainless steel metal mesh (size 2 cm × 1.5 cm, pore size 150 μm × 200 μm). We demonstrate that the functionalized mesh always works as a "physical" filter of suspended particulates. However, it works as a "chemical" filter (photocatalyst) for the potential water soluble contaminant (MB) in the presence

  20. Surface segregation energies in transition-metal alloys

    DEFF Research Database (Denmark)

    Ruban, Andrei; Skriver, Hans Lomholt; Nørskov, Jens Kehlet

    1999-01-01

    We present a database of 24 x 24 surface segregation energies of single transition metal impurities in transition-metal hosts obtained by a Green's-function linear-muffin-tin-orbitals method in conjunction with the coherent potential and atomic sphere approximations including a multipole correction...... to the electrostatic potential and energy. We use the database to establish the major factors which govern surface segregation in transition metal alloys. We find that the calculated trends are well described by Friedel's rectangular state density model and that the few but significant deviations from the simple...

  1. Evaluation of Metal-Fueled Surface Reactor Concepts

    International Nuclear Information System (INIS)

    Poston, David I.; Marcille, Thomas F.; Kapernick, Richard J.; Hiatt, Matthew T.; Amiri, Benjamin W.

    2007-01-01

    Surface fission power systems for use on the Moon and Mars may provide the first use of near-term reactor technology in space. Most near-term surface reactor concepts specify reactor temperatures <1000 K to allow the use of established material and power conversion technology and minimize the impact of the in-situ environment. Metal alloy fuels (e.g. U-10Zr and U-10Mo) have not traditionally been considered for space reactors because of high-temperature requirements, but they might be an attractive option for these lower temperature surface power missions. In addition to temperature limitations, metal fuels are also known to swell significantly at rather low fuel burnups (∼1 a/o), but near-term surface missions can mitigate this concern as well, because power and lifetime requirements generally keep fuel burnups <1 a/o. If temperature and swelling issues are not a concern, then a surface reactor concept may be able to benefit from the high uranium density and relative ease of manufacture of metal fuels. This paper investigates two reactor concepts that utilize metal fuels. It is found that these concepts compare very well to concepts that utilize other fuels (UN, UO2, UZrH) on a mass basis, while also providing the potential to simplify material safeguards issues

  2. Anomalous refraction of light through slanted-nanoaperture arrays on metal surface

    International Nuclear Information System (INIS)

    Kim, Myungji; Jung, Yun Suk; Xi, Yonggang; Kim, Hong Koo

    2015-01-01

    We report a nanoapertured metal surface that demonstrates anomalous refraction of light for a wide range of incident angles. A nanoslit aperture is designed to serve as a tilted vertical-dipole whose radiation pattern orients to a glancing angle direction to substrate. An array of such slanted nanoslits formed in a metal film redirects an incident beam into the direction of negative refraction angle: the aperture-transmitted wave makes a far-field propagation to the tilt-oriented direction of radiation pattern. The thus-designed nanoaperture array demonstrates the −1st order diffraction (i.e., to the negative refraction-angle direction) with well-suppressed background transmission (the zero-order direct transmission and other higher-order diffractions). Engineering the radiation pattern of nanoaperture offers an approach to overcoming the limits of conventional diffractive/refractive optics and complementing metasurface-based nano-optics

  3. Surface modification of metals by ion implantation

    International Nuclear Information System (INIS)

    Iwaki, Masaya

    1988-01-01

    Ion implantation in metals has attracted the attention as a useful technology for the formation of new metastable alloys and compounds in metal surface layers without thermal equilibrium. Current studies of metal surface modification by ion implantation with high fluences have expanded from basic research areas and to industrial applications for the improvement of life time of tools. Many results suggest that the high fluence implantation produces the new surface layers with un-expected microscopic characteristics and macroscopic properties due to implant particles, radiation damage, sputtering, and knock-on doping. In this report, the composition, structure and chemical bonding state in surface layers of iron, iron-based alloy and aluminum sheets implanted with high fluences have been investigated by means of secondary ion mass spectroscopy (SIMS), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Tribological properties such as hardness, friction and wear are introduced. (author)

  4. Direct NO decomposition over stepped transition-metal surfaces

    DEFF Research Database (Denmark)

    Falsig, Hanne; Bligaard, Thomas; Christensen, Claus H.

    2007-01-01

    We establish the full potential energy diagram for the direct NO decomposition reaction over stepped transition-metal surfaces by combining a database of adsorption energies on stepped metal surfaces with known Bronsted-Evans-Polanyi (BEP) relations for the activation barriers of dissociation...

  5. Pore surface engineering in covalent organic frameworks.

    Science.gov (United States)

    Nagai, Atsushi; Guo, Zhaoqi; Feng, Xiao; Jin, Shangbin; Chen, Xiong; Ding, Xuesong; Jiang, Donglin

    2011-11-15

    Covalent organic frameworks (COFs) are a class of important porous materials that allow atomically precise integration of building blocks to achieve pre-designable pore size and geometry; however, pore surface engineering in COFs remains challenging. Here we introduce pore surface engineering to COF chemistry, which allows the controlled functionalization of COF pore walls with organic groups. This functionalization is made possible by the use of azide-appended building blocks for the synthesis of COFs with walls to which a designable content of azide units is anchored. The azide units can then undergo a quantitative click reaction with alkynes to produce pore surfaces with desired groups and preferred densities. The diversity of click reactions performed shows that the protocol is compatible with the development of various specific surfaces in COFs. Therefore, this methodology constitutes a step in the pore surface engineering of COFs to realize pre-designed compositions, components and functions.

  6. A highly efficient surface plasmon polaritons excitation achieved with a metal-coupled metal-insulator-metal waveguide

    Directory of Open Access Journals (Sweden)

    Hongyan Yang

    2014-12-01

    Full Text Available We propose a novel metal-coupled metal-insulator-metal (MC-MIM waveguide which can achieve a highly efficient surface plasmon polaritons (SPPs excitation. The MC-MIM waveguide is formed by inserting a thin metal film in the insulator of an MIM. The introduction of the metal film, functioning as an SPPs coupler, provides a space for the interaction between SPPs and a confined electromagnetic field of the intermediate metal surface, which makes energy change and phase transfer in the metal-dielectric interface, due to the joint action of incomplete electrostatic shielding effect and SPPs coupling. Impacts of the metal film with different materials and various thickness on SPPs excitation are investigated. It is shown that the highest efficient SPPs excitation is obtained when the gold film thickness is 60 nm. The effect of refractive index of upper and lower symmetric dielectric layer on SPPs excitation is also discussed. The result shows that the decay value of refractive index is 0.3. Our results indicate that this proposed MC-MIM waveguide may offer great potential in designing a new SPPs source.

  7. Kansei, surfaces and perception engineering

    Science.gov (United States)

    Rosen, B.-G.; Eriksson, L.; Bergman, M.

    2016-09-01

    The aesthetic and pleasing properties of a product are important and add significantly to the meaning and relevance of a product. Customer sensation and perception are largely about psychological factors. There has been a strong industrial and academic need and interest for methods and tools to quantify and link product properties to the human response but a lack of studies of the impact of surfaces. In this study, affective surface engineering is used to illustrate and model the link between customer expectations and perception to controllable product surface properties. The results highlight the use of the soft metrology concept for linking physical and human factors contributing to the perception of products. Examples of surface applications of the Kansei methodology are presented from sauna bath, health care, architectural and hygiene tissue application areas to illustrate, discuss and confirm the strength of the methodology. In the conclusions of the study, future research in soft metrology is proposed to allow understanding and modelling of product perception and sensations in combination with a development of the Kansei surface engineering methodology and software tools.

  8. Antibacterial Metallic Touch Surfaces

    Directory of Open Access Journals (Sweden)

    Victor M. Villapún

    2016-08-01

    Full Text Available Our aim is to present a comprehensive review of the development of modern antibacterial metallic materials as touch surfaces in healthcare settings. Initially we compare Japanese, European and US standards for the assessment of antimicrobial activity. The variations in methodologies defined in these standards are highlighted. Our review will also cover the most relevant factors that define the antimicrobial performance of metals, namely, the effect of humidity, material geometry, chemistry, physical properties and oxidation of the material. The state of the art in contact-killing materials will be described. Finally, the effect of cleaning products, including disinfectants, on the antimicrobial performance, either by direct contact or by altering the touch surface chemistry on which the microbes attach, will be discussed. We offer our outlook, identifying research areas that require further development and an overview of potential future directions of this exciting field.

  9. Decontamination of U-metal surface by an oxidation etching system

    Energy Technology Data Exchange (ETDEWEB)

    Stout, R.B.; Kansa, E.J.; Shaffer, R.J.; Weed, H.C. [California Univ., Livermore, CA (United States). Lawrence Livermore National Lab

    2001-07-01

    A surface treatment to remove surface contamination from uranium (U) metal and/or hydrides of uranium and heavy metals (HM) from U-metal parts is described. In the case of heavy metal atomic contamination on a surface, and potentially several atomic layers beneath, the surface oxidation treatment combines both chemical and chemically driven mechanical processes. The chemical process is a controlled temperature-time oxidation process to create a thin film of uranium oxide (UO{sub 2} and higher oxides) on the U-metal surface. The chemically driven mechanical process is strain induced by the volume increase as the U-metal surface transforms to a UO{sub 2} surface film. These volume strains are significantly large to cause surface failure spalling/scale formation and thus, removal of a U-oxide film that contains the HM-contaminated surface. The case of a HM-hydride surface contamination layer can be treated similarly by using inert hot gas to decompose the U-hydrides and/or HM-hydrides that are contiguous with the surface. A preliminary analysis to design and to plan for a sequence of tests is developed. The tests will provide necessary and sufficient data to evaluate the effective implementation and operational characteristics of a safe and reliable system. The following description is limited to only a surface oxidation process for HM-decontamination. (authors)

  10. Quasi-one-dimensional metals on semiconductor surfaces with defects

    International Nuclear Information System (INIS)

    Hasegawa, Shuji

    2010-01-01

    Several examples are known in which massive arrays of metal atomic chains are formed on semiconductor surfaces that show quasi-one-dimensional metallic electronic structures. In this review, Au chains on Si(557) and Si(553) surfaces, and In chains on Si(111) surfaces, are introduced and discussed with regard to the physical properties determined by experimental data from scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARPES) and electrical conductivity measurements. They show quasi-one-dimensional Fermi surfaces and parabolic band dispersion along the chains. All of them are known from STM and ARPES to exhibit metal-insulator transitions by cooling and charge-density-wave formation due to Peierls instability of the metallic chains. The electrical conductivity, however, reveals the metal-insulator transition only on the less-defective surfaces (Si(553)-Au and Si(111)-In), but not on a more-defective surface (Si(557)-Au). The latter shows an insulating character over the whole temperature range. Compared with the electronic structure (Fermi surfaces and band dispersions), the transport property is more sensitive to the defects. With an increase in defect density, the conductivity only along the metal atomic chains was significantly reduced, showing that atomic-scale point defects decisively interrupt the electrical transport along the atomic chains and hide the intrinsic property of transport in quasi-one-dimensional systems.

  11. Surface modification of polyester biomaterials for tissue engineering

    International Nuclear Information System (INIS)

    Jiao Yanpeng; Cui Fuzhai

    2007-01-01

    Surfaces play an important role in a biological system for most biological reactions occurring at surfaces and interfaces. The development of biomaterials for tissue engineering is to create perfect surfaces which can provoke specific cellular responses and direct new tissue regeneration. The improvement in biocompatibility of biomaterials for tissue engineering by directed surface modification is an important contribution to biomaterials development. Among many biomaterials used for tissue engineering, polyesters have been well documented for their excellent biodegradability, biocompatibility and nontoxicity. However, poor hydrophilicity and the lack of natural recognition sites on the surface of polyesters have greatly limited their further application in the tissue engineering field. Therefore, how to introduce functional groups or molecules to polyester surfaces, which ideally adjust cell/tissue biological functions, becomes more and more important. In this review, recent advances in polyester surface modification and their applications are reviewed. The development of new technologies or methods used to modify polyester surfaces for developing their biocompatibility is introduced. The results of polyester surface modifications by surface morphological modification, surface chemical group/charge modification, surface biomacromolecule modification and so on are reported in detail. Modified surface properties of polyesters directly related to in vitro/vivo biological performances are presented as well, such as protein adsorption, cell attachment and growth and tissue response. Lastly, the prospect of polyester surface modification is discussed, especially the current conception of biomimetic and molecular recognition. (topical review)

  12. A Fully Non-Metallic Gas Turbine Engine Enabled by Additive Manufacturing

    Science.gov (United States)

    Grady, Joseph E.; Halbig, Michael C.; Singh, Mrityunjay

    2015-01-01

    In a NASA Aeronautics Research Institute (NARI) sponsored program entitled "A Fully Non-Metallic Gas Turbine Engine Enabled by Additive Manufacturing", evaluation of emerging materials and additive manufacturing technologies was carried out. These technologies may enable fully non-metallic gas turbine engines in the future. This paper highlights the results of engine system trade studies which were carried out to estimate reduction in engine emissions and fuel burn enabled due to advanced materials and manufacturing processes. A number of key engine components were identified in which advanced materials and additive manufacturing processes would provide the most significant benefits to engine operation. In addition, feasibility of using additive manufacturing technologies to fabricate gas turbine engine components from polymer and ceramic matrix composite were demonstrated. A wide variety of prototype components (inlet guide vanes (IGV), acoustic liners, engine access door) were additively manufactured using high temperature polymer materials. Ceramic matrix composite components included first stage nozzle segments and high pressure turbine nozzle segments for a cooled doublet vane. In addition, IGVs and acoustic liners were tested in simulated engine conditions in test rigs. The test results are reported and discussed in detail.

  13. Arc-textured metal surfaces for high thermal emittance space radiators

    International Nuclear Information System (INIS)

    Banks, B.A.; Rutledge, S.K.; Mirtich, M.J.; Behrend, T.; Hotes, D.; Kussmaul, M.; Barry, J.; Stidham, C.; Stueber, T.; DiFilippo, F.

    1994-01-01

    Carbon arc electrical discharges struck across the surfaces of metals such as Nb-1% Zr, alter the morphology to produce a high thermal emittance surface. Metal from the surface and carbon from the arc electrode vaporize during arcing, and then condense on the metal surface to produce a microscopically rough surface having a high thermal emittance. Quantitative spectral reflectance measurements from 0.33 to 15 μm were made on metal surfaces which were carbon arc treated in an inert gas environment. The resulting spectral reflectance data were then used to calculate thermal emittance as a function of temperature for various methods of arc treatment. The results of arc treatment on various metals are presented for both ac and dc arcs. Surface characterization data, including thermal emittance as a function of temperature, scanning electron microscopy, and atomic oxygen durability, are also presented. Ac arc texturing was found to increase the thermal emittance at 800 K from 0.05. to 0.70

  14. Effect of CO on surface oxidation of uranium metal

    International Nuclear Information System (INIS)

    Wang, X.; Fu, Y.; Xie, R.

    1997-01-01

    The surface reactions of uranium metal with carbon monoxide at 25 and 200 deg C have been studied by X-ray photoelectron spectroscopy (XPS);respectively. Adsorption of carbon monoxide on the surface layer of uranium metal leads to partial reduction of surface oxide and results in U4f photoelectron peak shifting to the lower binding energy. The content of oxygen in the surface oxide is decreased and O1s/O4f ratio decreases with increasing the exposure of carbon monoxide. The investigation indicates the surface layer of uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide. (author)

  15. Emissions from a Diesel Engine using Fe-based Fuel Additives and a Sintered Metal Filtration System.

    Science.gov (United States)

    Bugarski, Aleksandar D; Hummer, Jon A; Stachulak, Jozef S; Miller, Arthur; Patts, Larry D; Cauda, Emanuele G

    2016-03-01

    A series of laboratory tests were conducted to assess the effects of Fe-containing fuel additives on aerosols emitted by a diesel engine retrofitted with a sintered metal filter (SMF) system. Emission measurements performed upstream and downstream of the SMF system were compared, for cases when the engine was fueled with neat ultralow sulfur diesel (ULSD) and with ULSD treated with two formulations of additives containing Fe-based catalysts. The effects were assessed for four steady-state engine operating conditions and one transient cycle. The results showed that the SMF system reduced the average total number and surface area concentrations of aerosols by more than 100-fold. The total mass and elemental carbon results confirmed that the SMF system was indeed very effective in the removal of diesel aerosols. When added at the recommended concentrations (30 p.p.m. of iron), the tested additives had minor adverse impacts on the number, surface area, and mass concentrations of filter-out (FOut) aerosols. For one of the test cases, the additives may have contributed to measurable concentrations of engine-out (EOut) nucleation mode aerosols. The additives had only a minor impact on the concentration and size distribution of volatile and semi-volatile FOut aerosols. Metal analysis showed that the introduction of Fe with the additives substantially increased Fe concentration in the EOut, but the SMF system was effective in removal of Fe-containing aerosols. The FOut Fe concentrations for all three tested fuels were found to be much lower than the corresponding EOut Fe concentrations for the case of untreated ULSD fuel. The results support recommendations that these additives should not be used in diesel engines unless they are equipped with exhaust filtration systems. Since the tested SMF system was found to be very efficient in removing Fe introduced by the additives, the use of these additives should not result in a measurable increase in emissions of de novo generated

  16. Surface free energy of alkali and transition metal nanoparticles

    International Nuclear Information System (INIS)

    Aqra, Fathi; Ayyad, Ahmed

    2014-01-01

    Graphical abstract: Size dependent surface free energy of spherical, cubic and disk Au nanoparticles. - Highlights: • A model to account for the surface free energy of metallic nanoparticles is described. • The model requires only the cohesive energy of the nanoparticle. • The surface free energy of a number of metallic nanoparticles has been calculated, and the obtained values agree well with existing data. • Surface energy falls down very fast when the number of atoms is less than hundred. • The model is applicable to any metallic nanoparticle. - Abstract: This paper addresses an interesting issue on the surface free energy of metallic nanoparticles as compared to the bulk material. Starting from a previously reported equation, a theoretical model, that involves a specific term for calculating the cohesive energy of nanoparticle, is established in a view to describe the behavior of surface free energy of metallic nanoparticles (using different shapes of particle: sphere, cube and disc). The results indicate that the behavior of surface energy is very appropriate for spherical nanoparticle, and thus, it is the most realistic shape of a nanoparticle. The surface energy of copper, silver, gold, platinum, tungsten, molybdenum, tantalum, paladium and alkali metallic nanoparticles is only prominent in the nanoscale size, and it decreases with the decrease of nanoparticle size. Thus, the surface free energy plays a more important role in determining the properties of nanoparticles than in bulk materials. It differs from shape to another, and falls down as the number of atoms (nanoparticle size) decreases. In the case of spherical nanoparticles, the onset of the sharp decrease in surface energy is observed at about 110 atom. A decrease of 16% and 45% in surface energy is found by moving from bulk to 110 atom and from bulk to 5 atom, respectively. The predictions are consistent with the reported data

  17. Metallic and Ceramic Thin Film Thermocouples for Gas Turbine Engines

    Directory of Open Access Journals (Sweden)

    Otto J. Gregory

    2013-11-01

    Full Text Available Temperatures of hot section components in today’s gas turbine engines reach as high as 1,500 °C, making in situ monitoring of the severe temperature gradients within the engine rather difficult. Therefore, there is a need to develop instrumentation (i.e., thermocouples and strain gauges for these turbine engines that can survive these harsh environments. Refractory metal and ceramic thin film thermocouples are well suited for this task since they have excellent chemical and electrical stability at high temperatures in oxidizing atmospheres, they are compatible with thermal barrier coatings commonly employed in today’s engines, they have greater sensitivity than conventional wire thermocouples, and they are non-invasive to combustion aerodynamics in the engine. Thin film thermocouples based on platinum:palladium and indium oxynitride:indium tin oxynitride as well as their oxide counterparts have been developed for this purpose and have proven to be more stable than conventional type-S and type-K thin film thermocouples. The metallic and ceramic thin film thermocouples described within this paper exhibited remarkable stability and drift rates similar to bulk (wire thermocouples.

  18. Surface energies of metals in both liquid and solid states

    International Nuclear Information System (INIS)

    Aqra, Fathi; Ayyad, Ahmed

    2011-01-01

    Although during the last years one has seen a number of systematic studies of the surface energies of metals, the aim and the scientific meaning of this research is to establish a simple and a straightforward theoretical model to calculate accurately the mechanical and the thermodynamic properties of metal surfaces due to their important application in materials processes and in the understanding of a wide range of surface phenomena. Through extensive theoretical calculations of the surface tension of most of the liquid metals, we found that the fraction of broken bonds in liquid metals (f) is constant which is equal to 0.287. Using our estimated f value, the surface tension (γ m ), surface energy (γ SV ), surface excess entropy (-dγ/dT), surface excess enthalpy (H s ), coefficient of thermal expansion (α m and α b ), sound velocity (c m ) and its temperature coefficient (-dc/dT) have been calculated for more than sixty metals. The results of the calculated quantities agree well with available experimental data.

  19. Ion neutralization at metal surfaces by surface-plasmon excitation

    International Nuclear Information System (INIS)

    Almulhem, A.A.

    1988-01-01

    Electron capture by ions scattered from metal surfaces is usually assumed to occur via resonance tunneling or Auger neutralization. A new mechanism is proposed, wherein a surface plasmon is excited during the electron capture. The Fock-Tani transformation is used to transform the Hamiltonian into a form which explicitly contains a term that corresponds to this process. Using this term, the matrix elements are calculated analytically and used to evaluate the transition rate as a function of distance from the surface. Since this is a rearrangement process, the matrix element contains an orthogonalization term. The theory is applied to the scattering of protons from an aluminum surface in which the proton captures an electron into the 1s state. From the results obtained for the transition rate and neutral fractions, it is concluded that this process is important, at least in the low energy region. When the calculations are done with the orthogonalization term in the matrix element neglected, the transition rate and neutral fraction increased appreciably. This shows the importance of this term, and implies that it cannot be neglected as was done in other theories of neutralization at metal surfaces

  20. State promotion and neutralization of ions near metal surface

    International Nuclear Information System (INIS)

    Zinoviev, A.N.

    2011-01-01

    Research highlights: → Multiply charged ion and the charge induced in the metal form a dipole. → Dipole states are promoted into continuum with decreasing ion-surface distance. → These states cross the states formed from metal atom. → Proposed model explains the dominant population of deep bound states. → Observed spectra of emitted Auger electrons prove this promotion model. -- Abstract: When a multiply charged ion with charge Z approaches the metal surface, a dipole is formed by the multiply charged ion and the charge induced in the metal. The states for such a dipole are promoted into continuum with decreasing ion-surface distance and cross the states formed from metal atom. The model proposed explains the dominant population of deep bound states in collisions considered.

  1. Dynamic interactions of Leidenfrost droplets on liquid metal surface

    Science.gov (United States)

    Ding, Yujie; Liu, Jing

    2016-09-01

    Leidenfrost dynamic interaction effects of the isopentane droplets on the surface of heated liquid metal were disclosed. Unlike conventional rigid metal, such conductive and deformable liquid metal surface enables the levitating droplets to demonstrate rather abundant and complex dynamics. The Leidenfrost droplets at different diameters present diverse morphologies and behaviors like rotation and oscillation. Depending on the distance between the evaporating droplets, they attract and repulse each other through the curved surfaces beneath them and their vapor flows. With high boiling point up to 2000 °C, liquid metal offers a unique platform for testing the evaporating properties of a wide variety of liquid even solid.

  2. Distance of the image plane from metal surfaces

    International Nuclear Information System (INIS)

    Smith, N.V.; Chen, C.T.; Weinert, M.

    1989-01-01

    The data base of surface-state energies on the metals Cu, Ag, Au, Ni, Pd, and Pt is assembled and, with the aid of a simple model, is used to estimate the distance of the image plane and its trends from surface to surface and metal to metal. The model combines a nearly-free-electron representation of the crystal with a Jones-Jennings-Jepsen ansatz for the saturated image barrier. The projected bulk-band gaps are taken from published determinations. Constraints are placed on the surface barrier parameters by appeal to the results of self-consistent first-principles slab calculations. The general experimental trend observed is for the image-plane distance z 0 to decrease in the sequence (111) to (001) to (110), in the same sense but not as rapidly as z J , the distance of the effective jellium edge. This trend is rationalized using a simple model of the tail of the surface charge density. Typical values for z 0 -z J fall in the range -0.2 to +0.5 a.u., with the larger values occurring for the 3d metals Cu and Ni

  3. Surface analysis applied to metal-ceramic and bioceramic interfacial bonding

    International Nuclear Information System (INIS)

    Smart, R.St.C.; Arora, P.S.; Steveson, M.; Kawashima, N.; Cavallaro, G.P.; Ming, H.; Skinner, W.M.

    1999-01-01

    Full text: Low temperature plasma reactions, combined with sol-gel coatings, have been used to produce a variety of ceramic surface layers on metal substrates and interfacial layers between metals and oxides or other ceramics. These layers can be designed to be compositionally and functionally graded from the metal to bulk ceramic material, eg. silica, alumina, hydroxyapatite. The graded layers are generally <50nm thick, continuous, fully bonded to the substrate and deformable without disbonding. The objectives in design of these layers have been to produce: metal surfaces protected from oxidation, corrosion and acid attack; improved metal-ceramic bonding; and bioceramic titanium-based interfaces to bioactive hydroxyapatite for improved dental and medical implants. Modified Auger parameter studies for Si in XPS spectra show that the structure on the metal surfaces grades from amorphous, dehydroxylated silica on the outer surface through layer silicates, chain silicates, pyrosilicates to orthosilicates close to the metal interface. At the metal interface, detached grains of the metal are imaged with interpenetration of the oxide and silicate species linking the layer to the oxidised metal surface. The ∼30nm layer has a substantially increased frictional load compared with the untreated oxidised metal, i.e. behaviour consistent with either stronger adhesion of the coating to the substrate or a harder surface. The composition, structure and thickness of these layers can be controlled by the duration of each plasma reaction and the choice of the final reagent. The mechanisms of reaction in each process step have been elucidated with a combination of XPS, TOF-SIMS, TEM, SEM and FTIR. Similar, graded titanium/oxide/silicate/silica ceramic surface layers have been shown to form using the low temperature plasma reactions on titanium alloys used in medical and dental implants. Thicker (i.e. μm) overlayers of ceramic materials can be added to the graded surface layers

  4. Adhesion, growth and differentiation markers in human osteoblast-like cells cultured on surface-modified metallic materials designed for bone implants

    Czech Academy of Sciences Publication Activity Database

    Bačáková, Lucie; Kabátová, J.; Lisá, Věra; Starý, V.; Fencl, J.

    2006-01-01

    Roč. 9, č. 58-60 (2006), s. 1-3 ISSN 1429-7248 R&D Projects: GA ČR(CZ) GA101/06/0226 Institutional research plan: CEZ:AV0Z50110509 Keywords : bone tissue engineering * metals * surface modifications Subject RIV: EI - Biotechnology ; Bionics

  5. Role of calcium-depositing bacteria Agrobacterium tumefaciens and its influence on corrosion of different engineering metals used in cooling water system.

    Science.gov (United States)

    Narenkumar, Jayaraman; Sathishkumar, Kuppusamy; Selvi, Adikesavan; Gobinath, Rajagopalan; Murugan, Kadarkarai; Rajasekar, Aruliah

    2017-12-01

    The present investigation deals with the role of calcium-depositing bacterial community on corrosion of various engineering metals, namely, brass alloy (BS), copper (Cu), stainless steel (SS) and mild steel (MS). Based on the corrosion behavior, Agrobacterium tumefaciens EN13, an aerobic bacterium is identified as calcium-depositing bacteria on engineering metals. The results of the study are supported with biochemical characterization, 16S rRNA gene sequencing, calcium quantification, weight loss, electrochemical (impedance and polarization) and surface analysis (XRD and FTIR) studies. The calcium quantification study showed carbonate precipitation in abiotic system/biotic system as 50 and 700 ppm, respectively. FTIR results too confirmed the accumulation of calcium deposits from the environment on the metal surface by EN13. Electrochemical studies too supported the corrosion mechanism by showing a significant increase in the charge transfer resistance ( R ct ) of abiotic system (44, 33.6, 45, 29.6 Ω cm 2 ) than compared to biotic system (41, 10.1 29 and 25 Ω cm 2 ). Hence, the outcome of the present study confirmed the enhanced bioaccumulation behavior of calcium by the strain, EN13.

  6. Electron acceleration by surface plasma waves in double metal surface structure

    Science.gov (United States)

    Liu, C. S.; Kumar, Gagan; Singh, D. B.; Tripathi, V. K.

    2007-12-01

    Two parallel metal sheets, separated by a vacuum region, support a surface plasma wave whose amplitude is maximum on the two parallel interfaces and minimum in the middle. This mode can be excited by a laser using a glass prism. An electron beam launched into the middle region experiences a longitudinal ponderomotive force due to the surface plasma wave and gets accelerated to velocities of the order of phase velocity of the surface wave. The scheme is viable to achieve beams of tens of keV energy. In the case of a surface plasma wave excited on a single metal-vacuum interface, the field gradient normal to the interface pushes the electrons away from the high field region, limiting the acceleration process. The acceleration energy thus achieved is in agreement with the experimental observations.

  7. Surface metal standards produced by ion implantation through a removable layer

    International Nuclear Information System (INIS)

    Schueler, B.W.; Granger, C.N.; McCaig, L.; McKinley, J.M.; Metz, J.; Mowat, I.; Reich, D.F.; Smith, S.; Stevie, F.A.; Yang, M.H.

    2003-01-01

    Surface metal concentration standards were produced by ion implantation and investigated for their suitability to calibrate surface metal measurements by secondary ion mass spectrometry (SIMS). Single isotope implants were made through a 100 nm oxide layer on silicon. The implant energies were chosen to place the peak of the implanted species at a depth of 100 nm. Subsequent removal of the oxide layer was used to expose the implant peak and to produce controlled surface metal concentrations. Surface metal concentration measurements by time-of-flight SIMS (TOF-SIMS) with an analysis depth of 1 nm agreed with the expected surface concentrations of the implant standards with a relative mean standard deviation of 20%. Since the TOF-SIMS relative sensitivity factors (RSFs) were originally derived from surface metal measurements of surface contaminated silicon wafers, the agreement implies that the implant standards can be used to measure RSF values. The homogeneity of the surface metal concentration was typically <10%. The dopant dose remaining in silicon after oxide removal was measured using the surface-SIMS protocol. The measured implant dose agreed with the expected dose with a mean relative standard deviation of 25%

  8. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 μm. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  9. Analysis of surface bond lengths reported for chemisorption on metal surfaces

    Science.gov (United States)

    Mitchell, K. A. R.

    1985-01-01

    A review is given of bond length information available from the techniques of surface crystallography (particularly with LEED, SEXAFS and photoelectron diffraction) for chemisorption on well-defined surfaces of metals (M). For adsorbed main-group atoms (X), measured X-M interatomic distances for 38 combinations of X and M have been assessed with a bond order-bond length relation in combination with the Schomaker-Stevenson approach for determining single-bond lengths. When the surface bond orders are fixed primarily by the valency of X, this approach appears to provide a simple framework for predicing X-M surface bond lengths. Further, in cases where agreement has been reached from different surface crystallographic techniques, this framework has the potential for assessing refinements to the surface bonding model (e.g. in determining the roles of the effective surface valency of M, and of coordinate bonding and supplementary π bonding between X and M). Preliminary comparisons of structural data are also given for molecular adsorption (CO and ethylidyne) and for the chemisorption of other metal atoms.

  10. Metal surface corrosion grade estimation from single image

    Science.gov (United States)

    Chen, Yijun; Qi, Lin; Sun, Huyuan; Fan, Hao; Dong, Junyu

    2018-04-01

    Metal corrosion can cause many problems, how to quickly and effectively assess the grade of metal corrosion and timely remediation is a very important issue. Typically, this is done by trained surveyors at great cost. Assisting them in the inspection process by computer vision and artificial intelligence would decrease the inspection cost. In this paper, we propose a dataset of metal surface correction used for computer vision detection and present a comparison between standard computer vision techniques by using OpenCV and deep learning method for automatic metal surface corrosion grade estimation from single image on this dataset. The test has been performed by classifying images and calculating the accuracy for the two different approaches.

  11. Tuning apparent friction coefficient by controlled patterning bulk metallic glasses surfaces

    Science.gov (United States)

    Li, Ning; Xu, Erjiang; Liu, Ze; Wang, Xinyun; Liu, Lin

    2016-12-01

    Micro-honeycomb structures with various pitches between adjacent cells were hot-embossed on Zr35Ti30Cu8.25Be26.75 bulk metallic glass surface. The effect of pitch geometry on the frictional behavior of metallic glass surface was systematically investigated. The results revealed that all textured metallic glass surfaces show a reduction in friction coefficient compared to smooth surface. More intriguingly, the friction coefficient first decreased and then increased gradually with increasing pitches. Such unique behavior can be understood fundamentally from the perspective of competing effects between contact area and local stress level with increasing pitches. This finding not only enhance the in-depth understanding of the mechanism of the significant role of surface topography on the frictional behavior of metallic glass surface, but also opens a new route towards other functional applications for bulk metallic glasses.

  12. Engineering Hyporheic Zones to Attenuate Heavy Metals in Constructed Urban Streams: Performance Data from Constructed Stream Flumes

    Science.gov (United States)

    Halpin, B. N.; Portmann, A. C.; Herzog, S.; Higgins, C.; McCray, J. E.

    2017-12-01

    Urban stormwater runoff is a major cause of water quality impairment along ocean shorelines and in rivers, lakes and estuaries across the United States. In addition to pathogens, nutrients, and organic contaminants, a variety of heavy metals are commonly found at elevated concentrations in urban runoff. Although such metals occur in both dissolved and particulate-bound phases, conventional stormwater controls are typically designed to remove suspended solids, while dissolved phase contaminants remain largely untreated. To address this gap in available stormwater controls, a novel technology, termed Biohydrochemical Enhancements for Streamwater Treatment (BEST), has been developed based on inspiration from the natural hyporheic zone (HZ). BEST utilizes a series of alternating streambed permeabilities to drive efficient surface water-HZ exchange. This is combined with reactive and/or sorptive streambed geomedia designed to remove dissolved phase contaminants from constructed urban drainage channels. Previous research at the Colorado School of Mines has shown that a 15-meter flume modified with BEST exhibits greater hyporheic exchange than an all-sand control flume, though both flumes provided greater contaminant attenuation than a selection of actual urban streams. This study again utilized the 15-meter flumes at Colorado School of Mines to evaluate two configurations of BEST for removal of heavy metals commonly found in stormwater runoff, including cadmium, copper, nickel, lead and zinc. In both BEST configurations, the geomedia consisted of a 30/70 (v/v) mix of woodchips and sand, with one configuration using coarse sand (K=0.48 cm/s) and the other using finer sand (K=0.16 cm/s). Both configurations were compared to an all-sand control. To evaluate metals removal, a suite of aqueous metals solution was spiked into each flume, and aqueous concentrations of the five metals of interest were monitored in both the surface and pore water over 24 hours. Differences in

  13. ELECTROCATALYSIS ON SURFACES MODIFIED BY METAL MONOLAYERS DEPOSITED AT UNDERPOTENTIALS.

    Energy Technology Data Exchange (ETDEWEB)

    ADZIC,R.

    2000-12-01

    The remarkable catalytic properties of electrode surfaces modified by monolayer amounts of metal adatoms obtained by underpotential deposition (UPD) have been the subject of a large number of studies during the last couple of decades. This interest stems from the possibility of implementing strictly surface modifications of electrocatalysts in an elegant, well-controlled way, and these bi-metallic surfaces can serve as models for the design of new catalysts. In addition, some of these systems may have potential for practical applications. The UPD of metals, which in general involves the deposition of up to a monolayer of metal on a foreign substrate at potentials positive to the reversible thermodynamic potential, facilitates this type of surface modification, which can be performed repeatedly by potential control. Recent studies of these surfaces and their catalytic properties by new in situ surface structure sensitive techniques have greatly improved the understanding of these systems.

  14. Surface studies of liquid metals and alloys

    International Nuclear Information System (INIS)

    Bastasz, Robert

    2003-01-01

    Liquid metals and alloys have been proposed for use in nuclear fusion reactors to serve as replaceable plasma-facing surfaces that remove particles and heat from reacting plasmas. Several materials are being considered for this purpose including lithium, gallium, and tin as well as some of the alloys made from these elements. In order to better understand the properties of liquid surfaces, the technique of low-energy ion scattering was used to examine the surface composition of several of these materials in vacuum as a function of temperature. Oxygen is found to rapidly segregate to the surface of several metallic liquids. The segregation process can be interpreted using a simple thermodynamic model based on Gibbs theory. In the case of an alloy of Sn and Li, Li also segregates to the liquid surface. This provides a means to produce a surface enriched in Li, which is more plasma compatible than Sn, without the need to handle large quantities of liquid Li. (author)

  15. Relationship between metal speciation in soil solution and metal adsorption at the root surface of ryegrass.

    Science.gov (United States)

    Kalis, Erwin J J; Temminghoff, Erwin J M; Town, Raewyn M; Unsworth, Emily R; van Riemsdijk, Willem H

    2008-01-01

    The total metal content of the soil or total metal concentration in the soil solution is not always a good indicator for metal availability to plants. Therefore, several speciation techniques have been developed that measure a defined fraction of the total metal concentration in the soil solution. In this study the Donnan Membrane Technique (DMT) was used to measure free metal ion concentrations in CaCl(2) extractions (to mimic the soil solution, and to work under standardized conditions) of 10 different soils, whereas diffusive gradients in thin-films (DGT) and scanning chronopotentiometry (SCP) were used to measure the sum of free and labile metal concentrations in the CaCl(2) extracts. The DGT device was also exposed directly to the (wetted) soil (soil-DGT). The metal concentrations measured with the speciation techniques are related to the metal adsorption at the root surface of ryegrass (Lolium perenne L.), to be able to subsequently predict metal uptake. In most cases the metal adsorption related pH-dependently to the metal concentrations measured by DMT, SCP, and DGT in the CaCl(2) extract. However, the relationship between metal adsorption at the root surface and the metal concentrations measured by the soil-DGT was not-or only slightly-pH dependent. The correlations between metal adsorption at the root surface and metal speciation detected by different speciation techniques allow discussion about rate limiting steps in biouptake and the contribution of metal complexes to metal bioavailability.

  16. Correlations between deformations, surface state and leak rate in metal to metal contact; Correlations entre deformations, etat de surface et debit de fuite au contact metal-metal

    Energy Technology Data Exchange (ETDEWEB)

    Armand, G; Lapujoulade, J; Paigne, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The study of metal to metal contact from the stand-point of the leak rate has been carried on a copper ring located between two hard-steel flanges. The analysis of the results confirms the hysteresis phenomenon already seen. Some curves (leak rate versus force and leak rate versus true deformation) in semi-logarithmic coordinates are straight lines. Likewise some curves (electrical contact resistance versus force) in bi-logarithmic coordinates are straight lines. All these results can be understood by looking at the conductance introduced by the deformations of the micro-geometry of the surfaces in contact. Some tests carried out in rising the temperature confirm these hypothesis. (authors) [French] L'etude du contact metal-metal du point de vue debit de fuite a ete poursuivie en utilisant un anneau de cuivre place entre brides d'acier dur. L'analyse des resultats confirme le phenomene d'hysteresis deja constate, montre l'influence de l'etat de surface des brides et du joint. Certaines courbes (debit de fuite/force et debit de fuite/deformation rationnelle), en coordonnees semi-logarithmiques, sont des droites. De meme, certaines courbes (resistance de contact/force) en coordonnees bi-logarithmiques, sont des droites. Ces resultats s'interpretent en considerant la conductance produite par la deformation des microgeometries des surfaces en contact. Quelques essais d'elevation de temperature confirment ces resultats. (auteurs)

  17. ART AND ENGINEERING IN METAL SCULPTURES

    Directory of Open Access Journals (Sweden)

    COSTIN Georgiana Alexandra

    2016-07-01

    Full Text Available This paper shows how engineering and art are combined in making metal sculptures, referring to artistic creations exhibited in the “Dunărea de Jos” University campus in Galați, in the tradition existing between the Faculty of Engineering and the Visual Art Museum of Galați, with a significant contribution of prestigious artists of Galaţi and beyond. In this context, in order to develop the conception and design of some artistic products, many 2D and 3D graphical representation systems of information have appeared in a virtual environment, in which shaping using dedicated software applications, required that these artworks can be described by a series of shaping operation sequences, package design tools Autodesk Inventor CAD being such a solution.

  18. Interaction of hydrogen and oxygen with bulk defects and surfaces of metals

    International Nuclear Information System (INIS)

    Besenbacher, F.

    1994-05-01

    The thesis deals with the interaction of hydrogen with defects in metals and the interaction of hydrogen and oxygen with metal surfaces studied by ion-beam techniques and scanning tunneling microscopy (STM), respectively. The first part of the thesis discusses the interaction of hydrogen with simple defects in transition metals. The trap-binding enthalpies and the lattice location of hydrogen trapped to vacancies have been determined, and an extremely simple and versatile picture of the hydrogen-metal interaction has evolved, in which the trap strength is mainly determined by the local electron density. Any dilution of the lattice will lead to a trap, vacancies and voids being the strongest trap. It is found that hydrogen trapped to vacancies in fcc metals is quantum-mechanically delocalized, and the excitation energies for the hydrogen in the vacancy potential are a few MeV only. The interaction of hydrogen with metal surfaces is studied by the transmission channeling (TC) technique. It is found that hydrogen chemisorbs in the highest-coordinated sites on the surfaces, and that there is a direct relationship between the hydrogen-metal bond length and the coordination number for the hydrogen. In the final part of the thesis the dynamics of the chemisorption process for oxygen and hydrogen on metal surfaces is studied by STM, a fascinating and powerful technique for exploring the atomic-scale realm of surfaces. It is found that there is a strong coupling between the chemisorption process and the distortion of the metal surface. The adsorbates induce a surface reconstruction, i.e. metal-metal bond breaks and metal-adsorbate bounds form. Whereas hydrogen interacts weakly with the metals and induces reconstructions where only nnn metals bonds are broken, oxygen interacts strongly with the metal, and the driving force for the O-induced reconstructions appears to be the formation of low-coordinated metal-O rows, formed by breaking of nn metal bonds. Finally it is shown

  19. Corrugated metal surface with pillars for terahertz surface plasmon polariton waveguide components

    KAUST Repository

    Yuehong, Xu; Yanfeng, Li; Chunxiu, Tian; Jiaguang, Han; Quan, Xu; Xueqian, Zhang; Xixiang, Zhang; Ying, Zhang; Weili, Zhang

    2018-01-01

    In the terahertz regime, due to perfect conductivity of most metals, it is hard to realize a strong confinement of Surface plasmon polaritons (SPPs) although a propagation loss could be sufficiently low. We experimentally demonstrated a structure with periodic pillars arranged on a thin metal surface that supports bound modes of spoof SPPs at terahertz (THz) frequencies. By using scanning near-field THz microscopy, the electric field distribution above the metal surface within a distance of 130 μm was mapped. The results proved that this structure could guide spoof SPPs propagating along subwavelength waveguides, and at the same time reduce field expansion into free space. Further, for the development of integrated optical circuits, several components including straight waveguide, S-bend, Y-splitter and directional couplers were designed and characterized by the same method. We believe that the waveguide components proposed here will pave a new way for the development of flexible, wideband and compact photonic circuits operating at THz frequencies.

  20. Corrugated metal surface with pillars for terahertz surface plasmon polariton waveguide components

    KAUST Repository

    Yuehong, Xu

    2018-01-12

    In the terahertz regime, due to perfect conductivity of most metals, it is hard to realize a strong confinement of Surface plasmon polaritons (SPPs) although a propagation loss could be sufficiently low. We experimentally demonstrated a structure with periodic pillars arranged on a thin metal surface that supports bound modes of spoof SPPs at terahertz (THz) frequencies. By using scanning near-field THz microscopy, the electric field distribution above the metal surface within a distance of 130 μm was mapped. The results proved that this structure could guide spoof SPPs propagating along subwavelength waveguides, and at the same time reduce field expansion into free space. Further, for the development of integrated optical circuits, several components including straight waveguide, S-bend, Y-splitter and directional couplers were designed and characterized by the same method. We believe that the waveguide components proposed here will pave a new way for the development of flexible, wideband and compact photonic circuits operating at THz frequencies.

  1. Preserving half-metallic surface states in Cr O2 : Insights into surface reconstruction rules

    Science.gov (United States)

    Deng, Bei; Shi, X. Q.; Chen, L.; Tong, S. Y.

    2018-04-01

    The issue of whether the half-metallic (HM) nature of Cr O2 could be retained at its surface has been a standing problem under debate for a few decades, but until now is still controversial. Here, based on the density functional theory calculations we show, in startling contrast to the previous theoretical understandings, that the surfaces of Cr O2 favorably exhibit a half-metallic-semiconducting (SmC) transition driven by means of a surface electronic reconstruction largely attributed to the participation of the unexpected local charge carriers (LCCs), which convert the HM double exchange surface state into a SmC superexchange state and in turn, stabilize the surface as well. On the basis of the LCCs model, a new insight into the surface reconstruction rules is attained. Our novel finding not only provided an evident interpretation for the widely observed SmC character of Cr O2 surface, but also offered a novel means to improve the HM surface states for a variety of applications in spintronics and superconductors, and promote the experimental realization of the quantum anomalous Hall effect in half-metal based systems.

  2. Thermochemical Surface Engineering: A Playground for Science and Innovation

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Dahl, Kristian Vinter; Jellesen, Morten Stendahl

    2017-01-01

    Surface engineering by thermochemical processing is the intentional change of the composition of a material at elevated temperature with the purpose to improve materials performance. In thermochemical processing components from the starting material are essential in the development of the phases...... at the surface. Current research and innovation activities are used to exemplify thermochemical surface engineering and the interplay of science and innovation. The examples given encompass aspects of the synthesis of extremely porous materials, low temperature surface hardening of stainless steel, surface...

  3. Repository Surface Design Engineering Files Report Rev 00 ICN 1

    International Nuclear Information System (INIS)

    2001-01-01

    The objective of the Repository Surface Design Engineering Files Report Supplement [herein known as the Engineering Files (EF)] is to provide the surface design data needed by the Environmental Impact Statement (EIS) contractor to prepare the EIS and evaluate options and alternatives. This document is based on the Repository Surface Design Engineering Files Report, Revision 03 (CRWMS M and O 1999f) (EF Rev 03). Where facility and system designs have been changed for the Site Recommendation (SR) effort they are described in this report. EIS information provided in this report includes the following: (1) Description of program phases; there are no changes that impact this report. (2) A description of the major design requirements and assumptions that drive the surface facilities reference design is provided herein (Section 2.2), including the surface design resulting from recommendations regarding Enhanced Design Alternative (EDA) II, as discussed in the License Application Design Section Report (CRWMS M and O 1999d), and changes to the waste stream. See Section 2, Table 2-2, for the SR waste stream. (3) The major design requirements and assumptions that drive the surface facilities reference design are by reference to EF Rev 03; there are no changes that impact this report. (4) Description of the reference design concept and existing site conditions is by reference to EF Rev 03 (including Table 4-1, which is not included in this supplement); there are no changes that impact this report. (5) Description of alternative design cases is by reference to EF Rev 03; there are no changes that impact this report. (6) Description of optional inventory modules is by reference to EF Rev 03; there are no changes that impact this report. (7) Tabular summary level engineering values (i.e., staffing, wastes, emissions, resources, and land use) for the reference design and the alternative design cases that address construction, emplacement operations, caretaker operations, and

  4. Surface properties of ceramic/metal composite materials for thermionic converter applications

    International Nuclear Information System (INIS)

    Davis, P.R.; Bozack, M.J.; Swanson, L.W.

    1983-01-01

    Ceramic/metal composite electrode materials are of interest for thermionic energy conversion (TEC) applications for several reasons. These materials consist of submicron metal fibers or islands in an oxide matrix and therefore provide a basis for fabricating finely structured electrodes, with projecting or recessed metallic regions for more efficient electron emission or collection. Furthermore, evaporation and surface diffusion of matrix oxides may provide oxygen enhancement of cesium adsorption and work function lowering at both the collecting and emitting electrode surfaces of the TEC. Finally, the high work function oxide matrix or oxide-metal interfaces may provide efficient surface ionization of cesium for space-charge reduction in the device. The authors are investigating two types of ceramic/metal composite materials. One type is a directionally solidified eutectic consisting of a bulk oxide matrix such as UO 2 or stabilized ZrO 2 with parallel metal fibers (W) running through the oxide being exposed at the surface by cutting perpendicular to the fiber direction. The second type of material, called a surface eutectic, consists of a refractory substrate (Mo) with a thin layer of deposited and segregated material (Mo-Cr 2 O 3 -A1 2 O 3 ) on the surface. The final configuration of this layer is an oxide matrix with metallic islands scattered throughout

  5. Corrosion and surface modification on biocompatible metals: A review.

    Science.gov (United States)

    Asri, R I M; Harun, W S W; Samykano, M; Lah, N A C; Ghani, S A C; Tarlochan, F; Raza, M R

    2017-08-01

    Corrosion prevention in biomaterials has become crucial particularly to overcome inflammation and allergic reactions caused by the biomaterials' implants towards the human body. When these metal implants contacted with fluidic environments such as bloodstream and tissue of the body, most of them became mutually highly antagonistic and subsequently promotes corrosion. Biocompatible implants are typically made up of metallic, ceramic, composite and polymers. The present paper specifically focuses on biocompatible metals which favorably used as implants such as 316L stainless steel, cobalt-chromium-molybdenum, pure titanium and titanium-based alloys. This article also takes a close look at the effect of corrosion towards the implant and human body and the mechanism to improve it. Due to this corrosion delinquent, several surface modification techniques have been used to improve the corrosion behavior of biocompatible metals such as deposition of the coating, development of passivation oxide layer and ion beam surface modification. Apart from that, surface texturing methods such as plasma spraying, chemical etching, blasting, electropolishing, and laser treatment which used to improve corrosion behavior are also discussed in detail. Introduction of surface modifications to biocompatible metals is considered as a "best solution" so far to enhanced corrosion resistance performance; besides achieving superior biocompatibility and promoting osseointegration of biocompatible metals and alloys. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Measuring the surface inhomogeneity of metals on accreting white dwarfs

    International Nuclear Information System (INIS)

    Montgomery, M H; Hippel, T von; Thompson, S E

    2009-01-01

    Due to the short settling times of metals in DA white dwarf atmospheres, any white dwarfs with photospheric metals must be actively accreting. It is therefore natural to expect that the metals may not be deposited uniformly on the surface of the star. We present calculations showing how the temperature variations associated with white dwarf pulsations lead to an observable diagnostic of the surface metal distribution, and we show what constraints current data sets are able to provide.

  7. Piston surface heat transfer during combustion in large marine diesel engines

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    In the design process of large marine diesel engines information on the maximum heat load on the piston surface experienced during the engine cycle is an important parameter. The peak heat load occurs during combustion when hot combustion products impinge on the piston surface. Although the maximum...... heat load is only present for a short time of the total engine cycle, it is a severe thermal load on the piston surface. At the same time, cooling of the piston crown is generally more complicated than cooling of the other components of the combustion chamber. This can occasionally cause problems...... with burning off piston surface material. In this work the peak heat load on the piston surface of large marine diesel engines during combustion was investigated. Measurements of the instantaneous surface temperature and surface heat flux on pistons in large marine engines are difficult due to expensive...

  8. Metallization of DNA on silicon surface

    International Nuclear Information System (INIS)

    Puchkova, Anastasiya Olegovna; Sokolov, Petr; Petrov, Yuri Vladimirovich; Kasyanenko, Nina Anatolievna

    2011-01-01

    New simple way for silver deoxyribonucleic acid (DNA)-based nanowires preparation on silicon surface was developed. The electrochemical reduction of silver ions fixed on DNA molecule provides the forming of tightly matched zonate silver clusters. Highly homogeneous metallic clusters have a size about 30 nm. So the thickness of nanowires does not exceed 30–50 nm. The surface of n-type silicon monocrystal is the most convenient substrate for this procedure. The comparative analysis of DNA metallization on of n-type silicon with a similar way for nanowires fabrication on p-type silicon, freshly cleaved mica, and glass surface shows the advantage of n-type silicon, which is not only the substrate for DNA fixation but also the source of electrons for silver reduction. Images of bound DNA molecules and fabricated nanowires have been obtained using an atomic force microscope and a scanning ion helium microscope. DNA interaction with silver ions in a solution was examined by the methods of ultraviolet spectroscopy and circular dichroism.

  9. Plasma immersion surface modification with metal ion plasma

    International Nuclear Information System (INIS)

    Brown, I.G.; Yu, K.M.; Godechot, X.

    1991-04-01

    We describe here a novel technique for surface modification in which metal plasma is employed and by which various blends of plasma deposition and ion implantation can be obtained. The new technique is a variation of the plasma immersion technique described by Conrad and co-workers. When a substrate is immersed in a metal plasma, the plasma that condenses on the substrate remains there as a film, and when the substrate is then implanted, qualitatively different processes can follow, including' conventional' high energy ion implantation, recoil implantation, ion beam mixing, ion beam assisted deposition, and metallic thin film and multilayer fabrication with or without species mixing. Multiple metal plasma guns can be used with different metal ion species, films can be bonded to the substrate through ion beam mixing at the interface, and multilayer structures can be tailored with graded or abrupt interfaces. We have fabricated several different kinds of modified surface layers in this way. 22 refs., 4 figs

  10. Surface modification and functionalization of metal and metal oxide nanoparticles by organic ligands

    NARCIS (Netherlands)

    Neouze, M.A.; Schubert, U.S.

    2008-01-01

    Metal or metal oxide nanoparticles possess unique features compared to equivalent larger-scale materials. For applications, it is often necessary to stabilize or functionalize such nanoparticles. Thus, modification of the surface of nanoparticles is an important chemical challenge. In this survey,

  11. Investigation of the influence of pretreatment parameters on the surface characteristics of amorphous metal for use in power industry

    Science.gov (United States)

    Nieroda, Jolanta; Rybak, Andrzej; Kmita, Grzegorz; Sitarz, Maciej

    2018-05-01

    Metallic glasses are metallic materials, which exhibit an amorphous structure. These are mostly three or more component alloys, and some of them are magnetic metals. Materials of this kind are characterized by high electrical resistivity and at the same time exhibit very good magnetic properties (e.g. low-magnetization loss). The above mentioned properties are very useful in electrical engineering industry and this material is more and more popular as a substance for high-efficiency electrical devices production. This industry area is still evolving, and thus even higher efficiency of apparatus based on amorphous material is expected. A raw material must be carefully investigated and characterized before the main production process is started. Presented work contains results of complementary examination of amorphous metal Metglas 2605. Studies involve two ways to obtain clean and oxidized surface with high reactivity, namely degreasing followed by annealing process and plasma treatment. The amorphous metal parameters were examined by means of several techniques: surface free energy (SFE) measurements by sessile drop method, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and both ex situ and in situ Raman spectroscopy. Additionally, influence of plasma parameters on wetting properties were optimized in systematic way with Design of Experiments (DOE) method. A wide range of used methods allow to fully investigate the amorphous metal material during preliminary preparation of surface. Obtained results provide information about appropriate parameters that should be applied in order to obtain highly reactive surface with functional oxide layer on it.

  12. Gasification of carbon deposits on catalysts and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, J L

    1986-10-01

    'Coke' deposited on catalysts and reactor surfaces includes a variety of carbons of different structures and origins, their reactivities being conveniently assessed by Temperature Programmed Reaction (TPR). The gasification of carbon deposits obtained in the laboratory under well controlled conditions, and the regeneration of coked catalysts from petroleum refining processes are reviewed and discussed. Filamentary carbon deposits, containing dispersed metal particles, behave as supported metal catalysts during gasification, and show high reactivities. Pyrolytic and acid catalysis carbons are less reactive on their own, as the gasification is not catalysed; however, metal components of the catalyst or metal impurities deposited on the surface may enhance gasification. 26 refs., 8 figs., 2 tabs.

  13. Diffusion and surface alloying of gradient nanostructured metals

    Directory of Open Access Journals (Sweden)

    Zhenbo Wang

    2017-03-01

    Full Text Available Gradient nanostructures (GNSs have been optimized in recent years for desired performance. The diffusion behavior in GNS metals is crucial for understanding the diffusion mechanism and relative characteristics of different interfaces that provide fundamental understanding for advancing the traditional surface alloying processes. In this paper, atomic diffusion, reactive diffusion, and surface alloying processes are reviewed for various metals with a preformed GNS surface layer. We emphasize the promoted atomic diffusion and reactive diffusion in the GNS surface layer that are related to a higher interfacial energy state with respect to those in relaxed coarse-grained samples. Accordingly, different surface alloying processes, such as nitriding and chromizing, have been modified significantly, and some diffusion-related properties have been enhanced. Finally, the perspectives on current research in this field are discussed.

  14. Off-line testing of multifunctional surfaces for metal forming applications

    DEFF Research Database (Denmark)

    Godi, A.; Grønbæk, J.; De Chiffre, L.

    2015-01-01

    In this paper, Bending-Under-Tension, an off-line test method simulating deep-drawing, is chosen for investigating the effectiveness of multifunctional (MUFU) surfaces in metal forming operations. Four different MUFU surfaces, characterized by a plateau bearing area and grooves for lubricant...... retention, are manufactured, together with two polished references. During the tests, surface texture is the only variable. The results show how MUFU surfaces perform better than the polished references, which produce severe galling, while MUFU surfaces with low bearing area display no clear evidence...... of galling. Metal-to-metal contact occurs anyway, but the strip material is pulverized and deposited onto the tool instead of cold-welding to it. The pockets create a discontinuity on the texture hindering pick-up propagation....

  15. Ambient pressure photoemission spectroscopy of metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Baikie, Iain D., E-mail: iain@kptechnology.ltd.uk; Grain, Angela C.; Sutherland, James; Law, Jamie

    2014-12-30

    Highlights: • Ambient pressure photoemission spectroscopy of metals. • Rastered photon energy scan overcomes inelastic scattering. • Relationship between photoemission threshold and contact potential difference. - Abstract: We describe a novel photoemission technique utilizing a traditional Kelvin probe as a detector of electrons/atmospheric ions ejected from metallic surfaces (Au, Ag, Cu, Fe, Ni, Ti, Zn, Al) illuminated by a deep ultra-violet (DUV) source under ambient pressure. To surmount the limitation of electron scattering in air the incident photon energy is rastered rather than applying a variable retarding electric field as is used with UPS. This arrangement can be applied in several operational modes: using the DUV source to determine the photoemission threshold (Φ) with 30–50 meV resolution and also the Kelvin probe, under dark conditions, to measure contact potential difference (CPD) between the Kelvin probe tip and the metallic sample with an accuracy of 1–3 meV. We have studied the relationship between the photoelectric threshold and CPD of metal surfaces cleaned in ambient conditions. Inclusion of a second spectroscopic visible source was used to confirm a semiconducting oxide, possibly Cu{sub 2}O, via surface photovoltage measurements with the KP. This dual detection system can be easily extended to controlled gas conditions, relative humidity control and sample heating/cooling.

  16. Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Jared; Bosco, Nick; Dauskardt, Reinhold

    2017-11-01

    Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of ethylene vinyl acetate (EVA) encapsulant to screen-printed silver metallization was evaluated. At room temperature, the fracture energy Gc [J/m2] of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/antireflective (AR) coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 h of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2 while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and chemical byproducts at elevated temperature, which in part accounts for the propensity of metalized surfaces to delaminate in the field.

  17. Vacuum-based surface modification of organic and metallic substrates

    Science.gov (United States)

    Torres, Jessica

    Surface physico-chemical properties play an important role in the development and performance of materials in different applications. Consequently, understanding the chemical and physical processes involved during surface modification strategies is of great scientific and technological importance. This dissertation presents results from the surface modification of polymers, organic films and metallic substrates with reactive species, with the intent of simulating important modification processes and elucidating surface property changes of materials under different environments. The reactions of thermally evaporated copper and titanium with halogenated polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) are used to contrast the interaction of metals with polymers. Results indicate that reactive metallization is thermodynamically favored when the metal-halogen bond strength is greater than the carbon-halogen bond strength. X-ray post-metallization treatment results in an increase in metal-halide bond formation due to the production of volatile halogen species in the polymer that react with the metallic overlayer. The reactions of atomic oxygen (AO) and atomic chlorine with polyethylene (PE) and self-assembled monolayers (SAMs) films were followed to ascertain the role of radical species during plasma-induced polymer surface modification. The reactions of AO with X-ray modified SAMs are initially the dominated by the incorporation of new oxygen containing functionality at the vacuum/film interface, leading to the production of volatile carbon containing species such as CO2 that erodes the hydrocarbon film. The reaction of atomic chlorine species with hydrocarbon SAMs, reveals that chlorination introduces C-Cl and C-Cl2 functionalities without erosion. A comparison of the reactions of AO and atomic chlorine with PE reveal a maximum incorporation of the corresponding C-O and C-Cl functionalities at the polymer surface. A novel method to prepare phosphorous

  18. Metal/metal-oxide interfaces: A surface science approach to the study of adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Peden, C.H.F.; Kidd, K.B.; Shinn, N.D. (Sandia National Laboratories, Albuquerque, New Mexico 87185-5800 (USA))

    1991-05-01

    Metal-oxide/metal interfaces play an important role, for example, in the joining of an oxide ceramic to a metal for sealing applications. In order to probe the chemical and physical properties of such an interface, we have performed Auger electron spectroscopic (AES) and temperature programed desorption (TPD) experiments on a model system composed of very thin films of Cr, Fe, Ni, or Cu evaporated onto a very thin thermally grown oxide on a W single crystal. Monolayer films of Fe and Cr were found (by AES) to completely wet the oxide surface upon deposition, and were stable up to temperatures at which the films desorbed ({approx}1300 K). In contrast, monolayer Ni and Cu films formed three-dimensional islands exposing the oxidized W surface either upon annealing (Ni) or even upon room-temperature deposition (Cu). The relative interfacial interaction between the overlayer metal and the oxide, as assessed by TPD, increases in the series Cu{lt}Ni{lt}Fe{lt}Cr. This trend follows the heats of formation of the various oxides of these metals.

  19. Antibiotic Algae by Chemical Surface Engineering.

    Science.gov (United States)

    Kerschgens, Isabel P; Gademann, Karl

    2018-03-02

    Chemical cell-surface engineering is a tool for modifying and altering cellular functions. Herein, we report the introduction of an antibiotic phenotype to the green alga Chlamydomonas reinhardtii by chemically modifying its cell surface. Flow cytometry and confocal microscopy studies demonstrated that a hybrid of the antibiotic vancomycin and a 4-hydroxyproline oligomer binds reversibly to the cell wall without affecting the viability or motility of the cells. The modified cells were used to inhibit bacterial growth of Gram-positive Bacillus subtilis cultures. Delivery of the antibiotic from the microalgae to the bacterial cells was verified by microscopy. Our studies provide compelling evidence that 1) chemical surface engineering constitutes a useful tool for the introduction of new, previously unknown functionality, and 2) living microalgae can serve as new platforms for drug delivery. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Digitally Milled Metal Framework for Fixed Complete Denture with Metal Occlusal Surfaces: A Design Concept.

    Science.gov (United States)

    AlBader, Bader; AlHelal, Abdulaziz; Proussaefs, Periklis; Garbacea, Antonela; Kattadiyil, Mathew T; Lozada, Jaime

    Implant-supported fixed complete dentures, often referred to as hybrid prostheses, have been associated with high implant survival rates but also with a high incidence of mechanical prosthetic complications. The most frequent of these complications have been fracture and wear of the veneering material. The proposed design concept incorporates the occlusal surfaces of the posterior teeth as part of a digital milled metal framework by designing the posterior first molars in full contour as part of the framework. The framework can be designed, scanned, and milled from a titanium blank using a milling machine. Acrylic resin teeth can then be placed on the framework by conventional protocol. The metal occlusal surfaces of the titanium-countered molars will be at centric occlusion. It is hypothesized that metal occlusal surfaces in the posterior region may reduce occlusal wear in these types of prostheses. When the proposed design protocol is followed, the connection between the metal frame and the cantilever part of the prosthesis is reinforced, which may lead to fewer fractures of the metal framework.

  1. Modelling the appearance of heritage metallic surfaces

    Directory of Open Access Journals (Sweden)

    L. MacDonald

    2014-06-01

    Full Text Available Polished metallic surfaces exhibit a high degree of specularity, which makes them difficult to reproduce accurately. We have applied two different techniques for modelling a heritage object known as the Islamic handbag. Photogrammetric multi-view stereo enabled a dense point cloud to be extracted from a set of photographs with calibration targets, and a geometrically accurate 3D model produced. A new method based on photometric stereo from a set of images taken in an illumination dome enabled surface normals to be generated for each face of the object and its appearance to be rendered, to a high degree of visual realism, when illuminated by one or more light sources from any angles. The specularity of the reflection from the metal surface was modelled by a modified Lorentzian function.

  2. Metal and engineering industry in the Finnish economy

    International Nuclear Information System (INIS)

    Maeenpaeae, I.; Viitanen, M.; Juutinen, A.

    1996-01-01

    The study analyses quantitatively the position, internal structures and environmental aspects of the metal sector (basic metal industry, mechanical engineering, electronics and electrotechnics) in the recent past of the Finnish economy. The changes in the sector by the year 2005 are assessed by means of a macroeconomic simulation model as well. The future development of the metal sector by the year 2005 was assessed by the FMS model system, for which a detailed metal sector sub-model was constructed. The scenario of the general development of the Finnish economy was tuned so that it corresponds as closely as possible to the recent basic projections of the economy made by the government authorities. Three scenarios for the metal sector were constructed: base scenario, rapid and slow growth scenarios. In the base scenario the production volume of the metal sector grows by 6 per cent annually between 1994-2005 while the annual growth rate of the whole industry is 4 per cent and that of the GDP 3 per cent. In the rapid growth scenario, the growth rate of the metal sector goes up to 10 per cent and in the slow growth scenario down to 3 per cent. In the assessment of environmental effects of the metal sector are included energy consumption, emissions into the air, use on natural resources, waste formation and recycling of metals. Although the production volume of the metal sector almost doubles between 1990 - 2000, the consumption of primary energy grows only about one fourth and that of the electricity by 50 per cent

  3. Use of reliability engineering in development and manufacturing of metal parts

    International Nuclear Information System (INIS)

    Khan, A.; Iqbal, M.A.; Asif, M.

    2005-01-01

    The reliability engineering predicts modes of failures and weak links before the system is built instead of failure case study. The reliability engineering analysis will help in the manufacturing economy, assembly accuracy and qualification by testing, leading to production of metal parts in an aerospace industry. This methodology will also minimize the performance constraints in any requirement for the application of metal components in aerospace systems. The reliability engineering predicts the life of the parts under loading conditions whether dynamic or static. Reliability predictions can help engineers in making decisions about design of components, materials selection and qualification under applied stress levels. Two methods of reliability prediction i.e. Part Stress Analysis and Part Count have been used in this study. In this paper we will discuss how these two methods can be used to measure reliability of a system during development phases, which includes the measuring effect of environmental and operational variables. The equations are used to measure the reliability of each type of component, as well as, integration for measuring system applied for the reliability analysis. (author)

  4. Surface plasmon—polaritons on ultrathin metal films

    International Nuclear Information System (INIS)

    Quan Jun; Zhang Jun; Shao Le-Xi; Tian Ying

    2011-01-01

    We discuss the surface plasmon—polaritons used for ultrathin metal films with the aid of linear response theory and make comparisons with the known result given by Economou E N. In this paper we consider transverse electromagnetic fields and assume that the electromagnetic field in the linear response formula is the induced field due to the current of the electrons. It satisfies the Maxwell equation and thus we replace the current (charge) term in the Maxwell equation with the linear response expectation value. Finally, taking the external field to be zero, we obtain the dispersion relation of the surface plasmons from the eigenvalue equation. In addition, the charge-density and current-density in the z direction on the surface of ultrathin metal films are also calculated. The results may be helpful to the fundamental understanding of the complex phenomenon of surface plasmon-polaritons. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  5. Direct transfer of multilayer graphene grown on a rough metal surface using PDMS adhesion engineering

    Science.gov (United States)

    Jang, Heejun; Kang, Il-Suk; Lee, Youngbok; Cha, Yun Jeong; Yoon, Dong Ki; Ahn, Chi Won; Lee, Wonhee

    2016-09-01

    The direct transfer of graphene using polydimethylsiloxane (PDMS) stamping has advantages such as a ‘pick-and-place’ capability and no chemical residue problems. However, it is not easy to apply direct PDMS stamping to graphene grown via chemical vapor deposition on rough, grainy metal surfaces due to poor contact between the PDMS and graphene. In this study, graphene consisting of a mixture of monolayers and multiple layers grown on a rough Ni surface was directly transferred without the use of an adhesive layer. Liquid PDMS was cured on graphene to effect a conformal contact with the graphene. A fast release of graphene from substrate was achieved by carrying out wet-etching-assisted mechanical peeling. We also carried out a thermal post-curing of PDMS to control the level of adhesion between PDMS and graphene and hence facilitate a damage-free release of the graphene. Characterization of the transferred graphene by micro-Raman spectroscopy, SEM/EDS and optical microscopy showed neither cracks nor contamination from the transfer. This technique allows a fast and simple transfer of graphene, even for multilayer graphene grown on a rough surface.

  6. Advances in surface engineering. V. 1. Fundamentals of coatings. Proceedings

    International Nuclear Information System (INIS)

    Datta, P.K.; Burnell-Gray, J.S.

    1997-01-01

    The scientific and technical research papers in these three volumes, on advances in surface engineering, cover the fundamentals of coatings, process technology and engineering applications, and are based on the proceedings of the May 1996 conference of the same name, held at the University of Northumbria. High temperature corrosion, aqueous corrosion, wear and fatigue are covered in Volume 1. Volume 2 includes papers on various surface engineering technologies including physical and chemical vapour deposition, thermal methods, plasmas and welds, lasers, peening and electrochemistry. Applications of surface engineering to the biomedical, aerospace, automotive, cutting tools and manufacturing, power generation and marine industries are discussed in Volume 3. (UK)

  7. Combined use of polymer composites and metals in engineering structures

    International Nuclear Information System (INIS)

    Hoa, S.V.

    2002-01-01

    Polymer matrix composites have found many applications in the construction of light weight structures such as those in aircrafts, automobiles, sports equipment etc. This is because these materials possess high stiffness, high strength and low densities. In applications of polymer matrix composites in the light weight structures, the polymer composites are however, not used by themselves alone in most cases. Usually the polymer composites are used in conjunction with some metal components. The metal components are used either to provide means for joining the composite components or the composites are used to repair the cracked metal structures. The synergistic effect of both metals and composites can provide excellent performance with good economy. This paper presents a few applications where polymer composites are used in conjunction with metals in engineering structures. (author)

  8. Electrolysis of water on (oxidized) metal surfaces

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2005-01-01

    Density functional theory calculations are used as the basis for an analysis of the electrochemical process, where by water is split to form molecular oxygen and hydrogen. We develop a method for obtaining the thermochemistry of the electrochemical water splitting process as a function of the bias...... directly from the electronic structure calculations. We consider electrodes of Pt(111) and Au(111) in detail and then discuss trends for a series of different metals. We show that the difficult step in the water splitting process is the formation of superoxy-type (OOH) species on the surface...... by the splitting of a water molecule on top an adsorbed oxygen atom. One conclusion is that this is only possible on metal surfaces that are (partly) oxidized. We show that the binding energies of the different intermediates are linearly correlated for a number of metals. In a simple analysis, where the linear...

  9. Charge state of ions scattered by metal surface

    International Nuclear Information System (INIS)

    Kishinevsky, L.M.; Parilis, E.S.; Verleger, V.K.

    1976-01-01

    A model for description of charge distributions for scattering of heavy ions in the keV region, on metal surfaces developing and improving the method of Van der Weg and Bierman, and taking into account the connection between the ion charge state and scattering kinematics, is proposed. It is shown that multiple charged particles come from ions with a vacancy in the inner shell while the outer shell vacancies give only single charged ions and neutrals. The approximately linear increase of degree of ionization with normal velocity, and the non-monotonic charge dependence of the energy spectrum established by Chicherov and Buck et al is explained by considering irreversible neutralization in the depth of the metal, taking into account the connection of the charge state with the shape of trajectory and its location relative to the metal surface. The dependence of charge state on surface structure is discussed. Some new experiments are proposed. (author)

  10. Cooperativity in Surface Bonding and Hydrogen Bonding of Water and Hydroxyl at Metal Surfaces

    DEFF Research Database (Denmark)

    Schiros, T.; Ogasawara, H.; Naslund, L. A.

    2010-01-01

    of the mixed phase at metal surfaces. The surface bonding can be considered to be similar to accepting a hydrogen bond, and we can thereby apply general cooperativity rules developed for hydrogen-bonded systems. This provides a simple understanding of why water molecules become more strongly bonded...... to the surface upon hydrogen bonding to OH and why the OH surface bonding is instead weakened through hydrogen bonding to water. We extend the application of this simple model to other observed cooperativity effects for pure water adsorption systems and H3O+ on metal surfaces.......We examine the balance of surface bonding and hydrogen bonding in the mixed OH + H2O overlayer on Pt(111), Cu(111), and Cu(110) via density functional theory calculations. We find that there is a cooperativity effect between surface bonding and hydrogen bonding that underlies the stability...

  11. Surfaces in Precision Engineering, Microengineering and Nanotechnology

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Kunzmann, H.; Peggs, G. N.

    2003-01-01

    with precision engineering, microengineering and nanotechnology are presented, encompassing surfaces in computers, MEMS, biomedical systems, light and X-ray optics, as well as in chemical systems. Surface properties at micro and nanoscale are considered, including geometry as well as physical and chemical...

  12. Study of highly functionalized metal surface treated by plasma ion implantation

    International Nuclear Information System (INIS)

    Ikeyama, Masami; Miyagawa, Soji; Miyagawa, Yoshiko; Nakao, Setsuo; Masuda, Haruho; Saito, Kazuo; Ono, Taizou; Hayashi, Eiji

    2004-01-01

    Technology for processing metal surfaces with hardness, low friction and free from foreign substances was developed with plasma ion implantation. Diamond-like carbon (DLC) coating is a most promising method for realization of hard and smooth metal surface. DLC coating was tested in a metal pipe with 10 mm diameter and 10 cm length by a newly developed plasma ion implantation instrument. The surface coated by DLC was proved to have characteristics equivalent to those prepared with other methods. A computer program simulating a formation process of DLC coating was developed. Experiments for fluorinating the DLC coating surface was performed. (Y. Kazumata)

  13. Surface modification by metal ion implantation forming metallic nanoparticles in an insulating matrix

    International Nuclear Information System (INIS)

    Salvadori, M.C.; Teixeira, F.S.; Sgubin, L.G.; Cattani, M.; Brown, I.G.

    2014-01-01

    Highlights: • Metal nanoparticles can be produced through metallic ion implantation in insulating substrate, where the implanted metal self-assembles into nanoparticles. • The nanoparticles nucleate near the maximum of the implantation depth profile, that can be estimated by computer simulation using the TRIDYN. • Nanocomposites, obtained by this way, can be produced in different insulator materials. More specifically we have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. • The nanocomposites were characterized by measuring the resistivity of the composite layer as function of the dose implanted, reaching the percolation threshold. • Excellent agreement was found between the experimental results and the predictions of the theory. - Abstract: There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We have investigated nanocomposites produced by metal ion implantation into insulating substrates, where the implanted metal self-assembles into nanoparticles. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), which can be estimated by computer simulation using the TRIDYN code. TRIDYN is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study show that the nanoparticles form a bidimentional array buried a few nanometers below the substrate surface. We have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples show that metallic nanoparticles form in

  14. The role of surface morphology in nanocatalyst engineering

    Energy Technology Data Exchange (ETDEWEB)

    Stamenkovic, V. [Argonne National Laboratory, Argonne, IL (United States). Material Science Div.

    2008-07-01

    This study investigated extended polycrystalline platinum (Pt) alloys and PtNi(hkl) and Pt(hkl) single crystalline surfaces for various catalytic reactions. The surfaces were treated in an ultra-high vacuum by sputtering and annealing cycles. Auger electron spectroscopy (AES), low energy ion spectroscopy (LEIS), and ultraviolet photoelectron spectroscopy (UPS) techniques were used to characterize the alloys before they were transferred into an electrochemical environment. The study showed that electronic effect was caused by changes in the metallic d-band centre position. Structural effects were caused by surface roughening. The sputtered surfaces formed a Pt-skeleton on the outermost layers as a result of the dissolution of transition metal atoms. A modification of Pt electronic properties altered the adsorption and catalytic properties of the corresponding bimetallic alloy. The most active systems for the oxygen reduction reaction (ORR) were observed in the Pt-skin near-surface formation. 3 refs.

  15. Surface Modification of Mg and Mg Alloys

    OpenAIRE

    Turhan, Can Metehan

    2012-01-01

    Progressively, the well explored and studied mechanical properties of a bulk metal are compared with the corrosion behaviour obtained from its surface, which enables promising improvements in desired applications. An example is magnesium metal: where, by developing new types of surface modifications by understanding its inconsistent corrosion behaviour, it would be possible to apply this engineering metal safely as a biocompatible metal, in addition to its widely used application areas such a...

  16. Study on surface wave characteristics of free surface flow of liquid metal lithium for IFMIF

    International Nuclear Information System (INIS)

    Hoashi, Eiji; Sugiura, Hirokazu; Yoshihashi-Suzuki, Sachiko; Yamaoka, Nobuo; Horiike, Hiroshi; Kanemura, Takuji; Kondo, Hiroo

    2011-01-01

    The international fusion materials irradiation facility (IFMIF) presents an intense neutron source to develop fusion reactor materials. The free surface flow of a liquid metal Lithium (Li) is planned as a target irradiated by two deuteron beams to generate intense neutrons and it is thus important to obtain knowledge of the surface wave characteristic for the safety and the efficiency of system in the IFMIF. We have been studying on surface wave characteristics experimentally using the liquid metal Li circulation facility at Osaka University and numerically using computational fluid dynamics (CFD) code, FLUENT. This paper reports the results of the surface fluctuation, the wave height and the surface velocity in the free surface flow of the liquid metal Li examined experimentally and numerically. In the experiment, an electro-contact probe apparatus was used to obtain the surface fluctuation and the wave height, and a high speed video was used to measure the surface velocity. We resulted in knowledge of the surface wave growth mechanism. On the other hand, a CFD simulation was also conducted to obtain information on the relation of the free surface with the inner flow. In the simulation, the model included from a two-staged contraction nozzle to a flow channel with a free surface flow region and simulation results were compared with the experimental data. (author)

  17. Decomposition of SnH{sub 4} molecules on metal and metal–oxide surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ugur, D. [TNO, Stieltjesweg 1, 2628 CK Delft (Netherlands); Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands); Storm, A.J.; Verberk, R. [TNO, Stieltjesweg 1, 2628 CK Delft (Netherlands); Brouwer, J.C. [Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands); Sloof, W.G., E-mail: w.g.sloof@tudelft.nl [Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands)

    2014-01-01

    Atomic hydrogen cleaning is a promising method for EUV lithography systems, to recover from surface oxidation and to remove carbon and tin contaminants. Earlier studies showed, however, that tin may redeposit on nearby surfaces due to SnH{sub 4} decomposition. This phenomenon of SnH{sub 4} decomposition during tin cleaning has been quantified for various metallic and metal-oxide surfaces using X-ray photoelectron spectroscopy (XPS). It was observed that the metal oxide surfaces (TiO{sub 2} and ZrO{sub 2}) were significantly less contaminated than metallic surfaces. Tin contamination due to SnH{sub 4} decomposition can thus be reduced or even mitigated by application of a suitable metal-oxide coating.

  18. Calculated surface-energy anomaly in the 3d metals

    DEFF Research Database (Denmark)

    Aldén, M.; Skriver, Hans Lomholt; Mirbt, S.

    1992-01-01

    Local-spin-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method have been used to calculate the surface energy of the 3d metals. The theory explains the variation of the values derived from measurements of the surface tension of liquid metals including...... the pronounced anomaly occurring between vanadium and nickel in terms of a decrease in the d contribution caused by spin polarization....

  19. The law of corresponding states and surface tension of metals

    International Nuclear Information System (INIS)

    Digilov, R.

    2001-01-01

    Full Text: Surface tension of liquid metals is one of fundamental and most important quantities in theory and practice of material processing and its temperature dependence leads to the well-known Marangoni convection. Although currently methods are sufficiently precise to measure the surface tension, there are uncertainties in experimental data and its temperature dependence mainly due to impurity, which even a trace of it strongly affects the results of measurements. The theoretical treatment from the first principles is unwieldy and not always permits one to calculate the surface tension with certainty. Another active research field deals with empirical correlation between the surface tension and bulk thermodynamic properties, which we interpret as a simple consequence of the law of corresponding states. In order to relate the surface tension and to bulk properties of liquid metals the reduced formula is derived by scaling with the melting point T m (0) at p = 0 and atomic volume Ω 0 2/3 at T = 0 K as macroscopic parameters for scaling ε and a characterizing the interatomic potential in metals. The reduced surface tension and the reduced surface entropy obtained in high temperature limit are discussed and compared with the experiment. The reduced temperature coefficient of the surface tension found is a universal constant for the metals of the same structure. It is shown that pressure dependence of the surface tension, so called baric coefficient of the surface tension, can be described by pressure dependence of scaling parameters T m (p) and Ω 0 (p). (author)

  20. Surface effects in metallic iron nanoparticles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Linderoth, Søren

    1994-01-01

    Nanoparticles of metallic iron on carbon supports have been studied in situ by use of Mossbauer spectroscopy. The magnetic anisotropy energy constant increases with decreasing particle size, presumably because of the influence of surface anisotropy. Chemisorption of oxygen results in formation...

  1. Urbanization increased metal levels in lake surface sediment and catchment topsoil of waterscape parks

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hong-Bo [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Yu, Shen, E-mail: syu@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Li, Gui-Lin [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Liu, Yi; Yu, Guang-Bin [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Deng, Hong [Department of Environmental Sciences, Tiantong National Station of Forest Ecosystem, Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai 200062 (China); Wu, Sheng-Chun [State Key Laboratory in Marine Pollution, Biology and Chemistry Department, City University of Hong Kong, Hong Kong (China); Wong, Ming-Hung [Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Hong Kong (China)

    2012-08-15

    Lake surface sediment is mainly derived from topsoil in its catchment. We hypothesized that distribution of anthropogenic metals would be homogenous in lake surface sediment and the lake's catchment topsoil. Anthropogenic metal distributions (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) in fourteen waterscape parks were investigated in surface sediments and catchment topsoils and possible source homogeneity was tested using stable Pb isotopic ratio analysis. The parks were located along an urbanization gradient consisting of suburban (SU), developing urban (DIU), developed urban (DDU), and central urban core (CUC) areas in Shanghai, China. Results indicated that surface lake sediments and catchment topsoils in the CUC parks were highly contaminated by the investigated anthropogenic metals. Total metal contents in surface sediment and topsoil gradually increased along the urbanization gradient from the SU to CUC areas. Generally, the surface sediments had greater total metal contents than their catchment topsoils. These results suggest that urbanization drives the anthropogenic metal enrichment in both surface sediment and its catchment topsoil in the waterscape parks. Soil fine particles (< 63 {mu}m) and surface sediments had similar enrichment ratios of metals, suggesting that surface runoff might act as a carrier for metals transporting from catchment to lake. Stable Pb isotope ratio analysis revealed that the major anthropogenic Pb source in surface sediment was coal combustion as in the catchment topsoil. Urbanization also correlated with chemical fractionation of metals in both surface sediment and catchment topsoil. From the SU to the CUC parks, amounts of labile metal fractions increased while the residual fraction of those metals remained rather constant. In short, urbanization in Shanghai drives anthropogenic metal distribution in environmental matrices and the sources were homogenous. -- Highlights: Black-Right-Pointing-Pointer Obvious

  2. Urbanization increased metal levels in lake surface sediment and catchment topsoil of waterscape parks

    International Nuclear Information System (INIS)

    Li, Hong-Bo; Yu, Shen; Li, Gui-Lin; Liu, Yi; Yu, Guang-Bin; Deng, Hong; Wu, Sheng-Chun; Wong, Ming-Hung

    2012-01-01

    Lake surface sediment is mainly derived from topsoil in its catchment. We hypothesized that distribution of anthropogenic metals would be homogenous in lake surface sediment and the lake's catchment topsoil. Anthropogenic metal distributions (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) in fourteen waterscape parks were investigated in surface sediments and catchment topsoils and possible source homogeneity was tested using stable Pb isotopic ratio analysis. The parks were located along an urbanization gradient consisting of suburban (SU), developing urban (DIU), developed urban (DDU), and central urban core (CUC) areas in Shanghai, China. Results indicated that surface lake sediments and catchment topsoils in the CUC parks were highly contaminated by the investigated anthropogenic metals. Total metal contents in surface sediment and topsoil gradually increased along the urbanization gradient from the SU to CUC areas. Generally, the surface sediments had greater total metal contents than their catchment topsoils. These results suggest that urbanization drives the anthropogenic metal enrichment in both surface sediment and its catchment topsoil in the waterscape parks. Soil fine particles (< 63 μm) and surface sediments had similar enrichment ratios of metals, suggesting that surface runoff might act as a carrier for metals transporting from catchment to lake. Stable Pb isotope ratio analysis revealed that the major anthropogenic Pb source in surface sediment was coal combustion as in the catchment topsoil. Urbanization also correlated with chemical fractionation of metals in both surface sediment and catchment topsoil. From the SU to the CUC parks, amounts of labile metal fractions increased while the residual fraction of those metals remained rather constant. In short, urbanization in Shanghai drives anthropogenic metal distribution in environmental matrices and the sources were homogenous. -- Highlights: ► Obvious urbanization effect on metal

  3. Characterisation of nanomaterial hydrophobicity using engineered surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Desmet, Cloé; Valsesia, Andrea; Oddo, Arianna; Ceccone, Giacomo; Spampinato, Valentina; Rossi, François; Colpo, Pascal, E-mail: pascal.colpo@ec.europa.eu [Directorate Health, Consumer and Reference Materials, Consumer Products Safety Unit (Italy)

    2017-03-15

    Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques. In this work, we developed a method for the direct characterisation of NM hydrophobicity. The determination of the nanomaterial hydrophobic character is carried out by the direct measurement of the affinity of the NMs for different collectors. Each collector is an engineered surface designed in order to present specific surface charge and hydrophobicity degrees. Being thus characterised by a combination of surface energy components, the collectors enable the NM immobilisation with surface coverage in relation to their hydrophobicity. The experimental results are explained by using the extended DLVO theory, which takes into account the hydrophobic forces acting between NMs and collectors.

  4. Influence of metallic surface states on electron affinity of epitaxial AlN films

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Monu; Krishna, Shibin; Aggarwal, Neha [Advanced Materials and Devices Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-NPL Campus, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Gupta, Govind, E-mail: govind@nplindia.org [Advanced Materials and Devices Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-NPL Campus, Dr. K.S. Krishnan Marg, New Delhi 110012 (India)

    2017-06-15

    The present article investigates surface metallic states induced alteration in the electron affinity of epitaxial AlN films. AlN films grown by plasma-assisted molecular beam epitaxy system with (30% and 16%) and without metallic aluminium on the surface were probed via photoemission spectroscopic measurements. An in-depth analysis exploring the influence of metallic aluminium and native oxide on the electronic structure of the films is performed. It was observed that the metallic states pinned the Fermi Level (FL) near valence band edge and lead to the reduction of electron affinity (EA). These metallic states initiated charge transfer and induced changes in surface and interface dipoles strength. Therefore, the EA of the films varied between 0.6–1.0 eV due to the variation in contribution of metallic states and native oxide. However, the surface barrier height (SBH) increased (4.2–3.5 eV) adversely due to the availability of donor-like surface states in metallic aluminium rich films.

  5. Forces, surface finish and friction characteristics in surface engineered single- and multiple-point cutting edges

    International Nuclear Information System (INIS)

    Sarwar, M.; Gillibrand, D.; Bradbury, S.R.

    1991-01-01

    Advanced surface engineering technologies (physical and chemical vapour deposition) have been successfully applied to high speed steel and carbide cutting tools, and the potential benefits in terms of both performance and longer tool life, are now well established. Although major achievements have been reported by many manufacturers and users, there are a number of applications where surface engineering has been unsuccessful. Considerable attention has been given to the film characteristics and the variables associated with its properties; however, very little attention has been directed towards the benefits to the tool user. In order to apply surface engineering technology effectively to cutting tools, the coater needs to have accurate information relating to cutting conditions, i.e. cutting forces, stress and temperature etc. The present paper describes results obtained with single- and multiple-point cutting tools with examples of failures, which should help the surface coater to appreciate the significance of the cutting conditions, and in particular the magnitude of the forces and stresses present during cutting processes. These results will assist the development of a systems approach to cutting tool technology and surface engineering with a view to developing an improved product. (orig.)

  6. Surface modification of nanodiamond through metal free atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Deng, Fengjie, E-mail: fengjiedeng@aliyun.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

    2016-12-30

    Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by {sup 1}H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

  7. Surface modification of nanodiamond through metal free atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2016-01-01

    Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by 1 H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

  8. Local Chemical Reactivity of a Metal Alloy Surface

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Scheffler, Matthias

    1995-01-01

    The chemical reactivity of a metal alloy surface is studied by density functional theory investigating the interaction of H2 with NiAl(110). The energy barrier for H2 dissociation is largely different over the Al and Ni sites without, however, reflecting the barriers over the single component metal...

  9. COATING OF POLYMERIC SUBSTRATE CATALYSTS ON METALLIC SURFACES

    Directory of Open Access Journals (Sweden)

    H. HOSSEINI

    2010-12-01

    Full Text Available This article presents results of a study on coating of a polymeric substrate ca-talyst on metallic surface. Stability of coating on metallic surfaces is a proper specification. Sol-gel technology was used to synthesize adhesion promoters of polysilane compounds that act as a mediator. The intermediate layer was coated by synthesized sulfonated polystyrene-divinylbenzene as a catalyst for production of MTBE in catalytic distillation process. Swelling of catalyst and its separation from the metal surface was improved by i increasing the quantity of divinylbenzene in the resin’s production process and ii applying adhesion pro¬moters based on the sol-gel process. The rate of ethyl silicate hydrolysis was intensified by increasing the concentration of utilized acid while the conden¬sation polymerization was enhanced in the presence of OH–. Sol was formed at pH 2, while the pH should be 8 for the formation of gel. By setting the ratio of the initial concentrations of water to ethyl silicate to 8, the gel formation time was minimized.

  10. Understanding the biological responses of nanostructured metals and surfaces

    Science.gov (United States)

    Lowe, Terry C.; Reiss, Rebecca A.

    2014-08-01

    Metals produced by Severe Plastic Deformation (SPD) offer distinct advantages for medical applications such as orthopedic devices, in part because of their nanostructured surfaces. We examine the current theoretical foundations and state of knowledge for nanostructured biomaterials surface optimization within the contexts that apply to bulk nanostructured metals, differentiating how their microstructures impact osteogenesis, in particular, for Ultrafine Grained (UFG) titanium. Then we identify key gaps in the research to date, pointing out areas which merit additional focus within the scientific community. For example, we highlight the potential of next-generation DNA sequencing techniques (NGS) to reveal gene and non-coding RNA (ncRNA) expression changes induced by nanostructured metals. While our understanding of bio-nano interactions is in its infancy, nanostructured metals are already being marketed or developed for medical devices such as dental implants, spinal devices, and coronary stents. Our ability to characterize and optimize the biological response of cells to SPD metals will have synergistic effects on advances in materials, biological, and medical science.

  11. Understanding the biological responses of nanostructured metals and surfaces

    International Nuclear Information System (INIS)

    Lowe, Terry C; A Reiss, Rebecca

    2014-01-01

    Metals produced by Severe Plastic Deformation (SPD) offer distinct advantages for medical applications such as orthopedic devices, in part because of their nanostructured surfaces. We examine the current theoretical foundations and state of knowledge for nanostructured biomaterials surface optimization within the contexts that apply to bulk nanostructured metals, differentiating how their microstructures impact osteogenesis, in particular, for Ultrafine Grained (UFG) titanium. Then we identify key gaps in the research to date, pointing out areas which merit additional focus within the scientific community. For example, we highlight the potential of next-generation DNA sequencing techniques (NGS) to reveal gene and non-coding RNA (ncRNA) expression changes induced by nanostructured metals. While our understanding of bio-nano interactions is in its infancy, nanostructured metals are already being marketed or developed for medical devices such as dental implants, spinal devices, and coronary stents. Our ability to characterize and optimize the biological response of cells to SPD metals will have synergistic effects on advances in materials, biological, and medical science

  12. Time-dependent image potential at a metal surface

    International Nuclear Information System (INIS)

    Alducin, M.; Diez Muino, R.; Juaristi, J.I.

    2003-01-01

    Transient effects in the image potential induced by a point charge suddenly created in front of a metal surface are studied. The time evolution of the image potential is calculated using linear response theory. Two different time scales are defined: (i) the time required for the creation of the image potential and (ii) the time it takes to converge to its stationary value. Their dependence on the distance of the charge to the surface is discussed. The effect of the electron gas damping is also analyzed. For a typical metallic density, the order of magnitude of the creation time is 0.1 fs, whereas for a charge created close to the surface the convergence time is around 1-2 fs

  13. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Joel Glenn [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

  14. The Impact of Road Maintenance Substances on Metals Surface Corrosion

    Directory of Open Access Journals (Sweden)

    Jolita Petkuvienė

    2011-04-01

    Full Text Available The purpose of research is to assess changes in the visual metal surface due to the exposure of road maintenance salts and molasses (‘Safecote’. Chlorides of deicing salts (NaCl, CaCl2 are the main agents affecting soil and water resources as well as causing the corrosion of roadside metallic elements. Molasses (‘Safecote’ is offered as an alternative to deice road pavement by minimizing the corrosion of metal elements near the road. A laboratory experiment was carried out to immerse and spray metals with NaCl, CaCl2, NaCl:CaCl2 and NaCl:Safecote solutions. The obtained results showed that NaCl:Safecote solution had the lowest coating with corrosion products (the average 17±4 % of the surface. The solutions of NaCl, CaCl2 and NaCl:CaCl2 had the highest percentage rate of the corrosion product on the metal surface reaching an average of 33±5 %. Article in English

  15. Adsorption and migration of single metal atoms on the calcite (10.4) surface

    International Nuclear Information System (INIS)

    Pinto, H; Haapasilta, V; Lokhandwala, M; Foster, Adam S; Öberg, S

    2017-01-01

    Transition metal atoms are one of the key ingredients in the formation of functional 2D metal organic coordination networks. Additionally, the co-deposition of metal atoms can play an important role in anchoring the molecular structures to the surface at room temperature. To gain control of such processes requires the understanding of adsorption and diffusion properties of the different transition metals on the target surface. Here, we used density functional theory to investigate the adsorption of 3 d (Ti, Cr, Fe, Ni, Cu), 4 d (Zr, Nb, Mo, Pd, Ag) and 5 d (Hf, W, Ir, Pt, Au) transition metal adatoms on the insulating calcite (10.4) surface. We identified the most stable adsorption sites and calculated binding energies and corresponding ground state structures. We find that the preferential adsorption sites are the Ca–Ca bridge sites. Apart from the Cr, Mo, Cu, Ag and Au all the studied metals bind strongly to the calcite surface. The calculated migration barriers for the representative Ag and Fe atoms indicates that the metal adatoms are mobile on the calcite surface at room temperature. Bader analysis suggests that there is no significant charge transfer between the metal adatoms and the calcite surface. (paper)

  16. Cell surface engineering with polyelectrolyte multilayer thin films.

    Science.gov (United States)

    Wilson, John T; Cui, Wanxing; Kozlovskaya, Veronika; Kharlampieva, Eugenia; Pan, Di; Qu, Zheng; Krishnamurthy, Venkata R; Mets, Joseph; Kumar, Vivek; Wen, Jing; Song, Yuhua; Tsukruk, Vladimir V; Chaikof, Elliot L

    2011-05-11

    Layer-by-layer assembly of polyelectrolyte multilayer (PEM) films represents a bottom-up approach for re-engineering the molecular landscape of cell surfaces with spatially continuous and molecularly uniform ultrathin films. However, fabricating PEMs on viable cells has proven challenging owing to the high cytotoxicity of polycations. Here, we report the rational engineering of a new class of PEMs with modular biological functionality and tunable physicochemical properties which have been engineered to abrogate cytotoxicity. Specifically, we have discovered a subset of cationic copolymers that undergoes a conformational change, which mitigates membrane disruption and facilitates the deposition of PEMs on cell surfaces that are tailorable in composition, reactivity, thickness, and mechanical properties. Furthermore, we demonstrate the first successful in vivo application of PEM-engineered cells, which maintained viability and function upon transplantation and were used as carriers for in vivo delivery of PEMs containing biomolecular payloads. This new class of polymeric film and the design strategies developed herein establish an enabling technology for cell transplantation and other therapies based on engineered cells. © 2011 American Chemical Society

  17. Improvements in or relating to surface treatment of metals

    International Nuclear Information System (INIS)

    Dearnaley, G.; Hartley, N.E.W.

    1975-01-01

    A method is described for surface treating metals so as to reduce their coefficients of friction. The metal is subjected to bombardment by a beam of ions of dry lubricant material, or material that forms a dry lubricant. The ions should have energies sufficient to cause them to be implanted into the surface region of the metal. The metal may be heated to facilitate assimilation of the ions, and implantation may be enhanced by means of irradiation of the article with radiation of energy sufficient to enhance diffusion of the ions into the article. The dry lubricant ions may comprise Mo + , In + , or Sn + . Where the article is of steel suitable ions are Mo + and S + deposited in the ratio of 1:2. Examples of application of the method are given, using a 500 Kv Cockcroft-Walton accelerator for the implantation. (U.K.)

  18. Electron-phonon coupling at metal surfaces

    International Nuclear Information System (INIS)

    Hellsing, B.; Eiguren, A.; Chulkov, E.V.

    2002-01-01

    Chemical reactions at metal surfaces are influenced by inherent dissipative processes which involve energy transfer between the conduction electrons and the nuclear motion. We shall discuss how it is possible to model this electron-phonon coupling in order to estimate its importance. A relevant quantity for this investigation is the lifetime of surface-localized electron states. A surface state, quantum well state or surface image state is located in a surface-projected bandgap and becomes relatively sharp in energy. This makes a comparison between calculations and experimental data most attractive, with a possibility of resolving the origin of the lifetime broadening of electron states. To achieve more than an order of magnitude estimate we point out the importance of taking into account the phonon spectrum, electron surface state wavefunctions and screening of the electron-ion potential. (author)

  19. Recommended values of clean metal surface work functions

    International Nuclear Information System (INIS)

    Derry, Gregory N.; Kern, Megan E.; Worth, Eli H.

    2015-01-01

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  20. Recommended values of clean metal surface work functions

    Energy Technology Data Exchange (ETDEWEB)

    Derry, Gregory N., E-mail: gderry@loyola.edu; Kern, Megan E.; Worth, Eli H. [Department of Physics, Loyola University Maryland, 4501 N. Charles St., Baltimore, Maryland 21210 (United States)

    2015-11-15

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  1. Plasma cleaning and the removal of carbon from metal surfaces

    International Nuclear Information System (INIS)

    Baker, M.A.

    1980-01-01

    In an investigation of the plasma cleaning of metals and the plasma etching of carbon, a mass spectrometer was used as a sensitive process monitor. CO 2 produced by the plasma oxidation of carbon films or of organic contamination and occluded carbon at the surfaces of metals proved to be the most suitable gas to monitor. A good correlation was obtained between the measured etch rate of carbon and the resulting CO 2 partial pressure monitored continuously with the mass spectrometer. The rate of etching of carbon in an oxygen-argon plasma at 0.1 Torr was high when the carbon was at cathode potential and low when it was electrically isolated in the plasma, thus confirming the findings of previous workers and indicating the importance of ion bombardment in the etching process. Superficial organic contamination on the surfaces of the metals aluminium and copper and of the alloy Inconel 625 was quickly removed by the oxygen-argon plasma when the metal was electrically isolated and also when it was at cathode potential. Occluded carbon (or carbides) at or near the surfaces of the metals was removed slowly and only when the metal was at cathode potential, thus illustrating again the importance of ion bombardment. (Auth.)

  2. Multi-surface topography targeted plateau honing for the processing of cylinder liner surfaces of automotive engines

    Science.gov (United States)

    Lawrence, K. Deepak; Ramamoorthy, B.

    2016-03-01

    Cylinder bores of automotive engines are 'engineered' surfaces that are processed using multi-stage honing process to generate multiple layers of micro geometry for meeting the different functional requirements of the piston assembly system. The final processed surfaces should comply with several surface topographic specifications that are relevant for the good tribological performance of the engine. Selection of the process parameters in three stages of honing to obtain multiple surface topographic characteristics simultaneously within the specification tolerance is an important module of the process planning and is often posed as a challenging task for the process engineers. This paper presents a strategy by combining the robust process design and gray-relational analysis to evolve the operating levels of honing process parameters in rough, finish and plateau honing stages targeting to meet multiple surface topographic specifications on the final running surface of the cylinder bores. Honing experiments were conducted in three stages namely rough, finish and plateau honing on cast iron cylinder liners by varying four honing process parameters such as rotational speed, oscillatory speed, pressure and honing time. Abbott-Firestone curve based functional parameters (Rk, Rpk, Rvk, Mr1 and Mr2) coupled with mean roughness depth (Rz, DIN/ISO) and honing angle were measured and identified as the surface quality performance targets to be achieved. The experimental results have shown that the proposed approach is effective to generate cylinder liner surface that would simultaneously meet the explicit surface topographic specifications currently practiced by the industry.

  3. New Engineering Solutions in Creation of Mini-BOF for Metallic Waste Recycling

    Science.gov (United States)

    Eronko, S. P.; Gorbatyuk, S. M.; Oshovskaya, E. V.; Starodubtsev, B. I.

    2017-12-01

    New engineering solutions used in design of the mini melting unit capable of recycling industrial and domestic metallic waste with high content of harmful impurities are provided. High efficiency of the process technology implemented with its use is achieved due to the possibility of the heat and mass transfer intensification in the molten metal bath, controlled charge into it of large amounts of reagents in lumps and in fines, and cut-off of remaining process slag during metal tapping into the teeming ladle.

  4. Self-excitation of Rydberg atoms at a metal surface

    DEFF Research Database (Denmark)

    Bordo, Vladimir

    2017-01-01

    The novel effect of self-excitation of an atomic beam propagating above a metal surface is predicted and a theory is developed. Its underlying mechanism is positive feedback provided by the reflective surface for the atomic polarization. Under certain conditions the atomic beam flying in the near...... field of the metal surface acts as an active device that supports sustained atomic dipole oscillations, which generate, in their turn, an electromagnetic field. This phenomenon does not exploit stimulated emission and therefore does not require population inversion in atoms. An experiment with Rydberg...... atoms in which this effect should be most pronounced is proposed and the necessary estimates are given....

  5. Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

    Science.gov (United States)

    Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

    2014-06-01

    A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al2O3 and Fe3O4, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

  6. Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

    International Nuclear Information System (INIS)

    Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

    2014-01-01

    A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al 2 O 3 and Fe 3 O 4 , on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

  7. Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An, E-mail: lian2010@lut.cn

    2014-06-01

    A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al{sub 2}O{sub 3} and Fe{sub 3}O{sub 4}, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

  8. Electronic properties of adsorbates and clean surfaces of metals and semiconductors

    International Nuclear Information System (INIS)

    Lecante, J.

    1980-01-01

    This paper surveys recent progress in experimental studies on electronic properties of adsorbates and clean metal surfaces. Electron spectroscopy and particularly angle resolved photoelectron spectroscopy appears to be a very powerful tool to get informations on electronic levels of adsorbates or clean surfaces. Moreover this technique may also give informations about the atomic geometry of the surface. Experimental investigation about surface plasmons, surface states, core level shifts are presented for clean surfaces. As examples of adsorbate covered surfaces two typical cases are chosen: two dimensional band structure and oriented molecules. Finally the photoelectron diffraction may be used for surface structure determination either in the case of an adsorbate or a clean metal surface [fr

  9. Process of treating surfaces of metals

    International Nuclear Information System (INIS)

    Kimura, T.; Murao, A.; Kuwahara, T.

    1975-01-01

    Both higher corrosion resistance and paint adherence are given to films formed on the surfaces of metals by treating the surfaces with aqueous solutions of one or more materials selected from the group consisting of water soluble vinyl monomer or water soluble high polymer and then irradiating with ionizing radioactive rays on the nearly dried surface film. When a water soluble inorganic compound is mixed with the above mentioned aqueous solution, the film properties are greatly improved. The inorganic ionic material should contain a cation from the group consisting of Ca, Mg, Zn, Cr, Al, Fe, and Ni. Electron beams may be used. (U.S.)

  10. Theory of the reaction dynamics of small molecules on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Bret [Univ. of Massachusetts, Amherst, MA (United States)

    2016-09-09

    The objective of this project has been to develop realistic theoretical models for gas-surface interactions, with a focus on processes important in heterogeneous catalysis. The dissociative chemisorption of a molecule on a metal is a key step in many catalyzed reactions, and is often the rate-limiting step. We have explored the dissociative chemisorption of H2, H2O and CH4 on a variety of metal surfaces. Most recently, our extensive studies of methane dissociation on Ni and Pt surfaces have fully elucidated its dependence on translational energy, vibrational state and surface temperature, providing the first accurate comparisons with experimental data. We have explored Eley-Rideal and hot atom reactions of H atoms with H- and C-covered metal surfaces. H atom interactions with graphite have also been explored, including both sticking and Eley-Rideal recombination processes. Again, our methods made it possible to explain several experiments studying these reactions. The sticking of atoms on metal surfaces has also been studied. To help elucidate the experiments that study these processes, we examine how the reaction dynamics depend upon the nature of the molecule-metal interaction, as well as experimental variables such as substrate temperature, beam energy, angle of impact, and the internal states of the molecules. Electronic structure methods based on Density Functional Theory are used to compute each molecule-metal potential energy surface. Both time-dependent quantum scattering techniques and quasi-classical methods are used to examine the reaction or scattering dynamics. Much of our effort has been directed towards developing improved quantum methods that can accurately describe reactions, as well as include the effects of substrate temperature (lattice vibration).

  11. Cohesion and coordination effects on transition metal surface energies

    Science.gov (United States)

    Ruvireta, Judit; Vega, Lorena; Viñes, Francesc

    2017-10-01

    Here we explore the accuracy of Stefan equation and broken-bond model semiempirical approaches to obtain surface energies on transition metals. Cohesive factors are accounted for either via the vaporization enthalpies, as proposed in Stefan equation, or via cohesive energies, as employed in the broken-bond model. Coordination effects are considered including the saturation degree, as suggested in Stefan equation, employing Coordination Numbers (CN), or as the ratio of broken bonds, according to the bond-cutting model, considering as well the square root dependency of the bond strength on CN. Further, generalized coordination numbers CN bar are contemplated as well, exploring a total number of 12 semiempirical formulations on the three most densely packed surfaces of 3d, 4d, and 5d Transition Metals (TMs) displaying face-centered cubic (fcc), body-centered cubic (bcc), or hexagonal close-packed (hcp) crystallographic structures. Estimates are compared to available experimental surface energies obtained extrapolated to zero temperature. Results reveal that Stefan formula cohesive and coordination dependencies are only qualitative suited, but unadvised for quantitative discussion, as surface energies are highly overestimated, favoring in addition the stability of under-coordinated surfaces. Broken-bond cohesion and coordination dependencies are a suited basis for quantitative comparison, where square-root dependencies on CN to account for bond weakening are sensibly worse. An analysis using Wulff shaped averaged surface energies suggests the employment of broken-bond model using CN to gain surface energies for TMs, likely applicable to other metals.

  12. Slurry erosion induced surface nanocrystallization of bulk metallic glass

    Science.gov (United States)

    Ji, Xiulin; Wu, Jili; Pi, Jinghong; Cheng, Jiangbo; Shan, Yiping; Zhang, Yingtao

    2018-05-01

    Microstructure evolution and phase transformation of metallic glasses (MGs) could occur under heating condition or mechanical deformation. The cross-section of as-cast Zr55Cu30Ni5Al10 MG rod was impacted by the solid particles when subjected to erosion in slurry flow. The surface microstructure was observed by XRD before and after slurry erosion. And the stress-driven de-vitrification increases with the increase of erosion time. A microstructure evolution layer with 1-2 μm thickness was formed on the topmost eroded surface. And a short range atomic ordering prevails in the microstructure evolution layer with crystalline size around 2-3 nm embedded in the amorphous matrix. The XPS analysis reveals that most of the metal elements in the MG surface, except for Cu, were oxidized. And a composite layer with ZrO2 and Al2O3 phases were formed in the topmost surface after slurry erosion. The cooling rate during solidification of MG has a strong influence on the slurry erosion induced nanocrystallization. And a lower cooling rate favors the surface nanocrystallization because of lower activation energy and thermo-stability. Finally, the slurry erosion induced surface nanocrystallization and microstructure evolution result in surface hardening and strengthening. Moreover, the microstructure evolution mechanisms were discussed and it is related to the cooling rate of solidification and the impact-induced temperature rise, as well as the combined effects of the impact-induced plastic flow, inter-diffusion and oxidation of the metal elements.

  13. Application of Volta potential mapping to determine metal surface defects

    International Nuclear Information System (INIS)

    Nazarov, A.; Thierry, D.

    2007-01-01

    As a rule, stress or fatigue cracks originate from various surface imperfections, such as pits, inclusions or locations showing a residual stress. It would be very helpful for material selection to be able to predict the likelihood of environment-assisted cracking or pitting corrosion. By using Scanning Kelvin Probe (the vibrating capacitor with a spatial resolution of 80 μm) the profiling of metal electron work function (Volta potential) in air is applied to the metal surfaces showing residual stress, MnS inclusions and wearing. The Volta potential is influenced by the energy of electrons at the Fermi level and drops generally across the metal/oxide/air interfaces. Inclusions (e.g. MnS) impair continuity of the passive film that locally decreases Volta potential. The stress applied gives rise to dislocations, microcracks and vacancies in the metal and the surface oxide. The defects decrease Volta and corrosion potentials; reduce the overvoltage for processes of passivity breakdown and anodic metal dissolution. These 'anodic' defects can be visualized in potential mapping that can help us to predict locations with higher risk of pitting corrosion or cracking

  14. Surface plasmons based terahertz modulator consisting of silicon-air-metal-dielectric-metal layers

    Science.gov (United States)

    Wang, Wei; Yang, Dongxiao; Qian, Zhenhai

    2018-05-01

    An optically controlled modulator of the terahertz wave, which is composed of a metal-dielectric-metal structure etched with circular loop arrays on both the metal layers and a photoexcited silicon wafer separated by an air layer, is proposed. Simulation results based on experimentally measured complex permittivities predict that modification of complex permittivity of the silicon wafer through excitation laser leads to a significant tuning of transmission characteristics of the modulator, forming the modulation depths of 59.62% and 96.64% based on localized surface plasmon peak and propagating surface plasmon peak, respectively. The influences of the complex permittivity of the silicon wafer and the thicknesses of both the air layer and the silicon wafer are numerically studied for better understanding the modulation mechanism. This study proposes a feasible methodology to design an optically controlled terahertz modulator with large modulation depth, high speed and suitable insertion loss, which is useful for terahertz applications in the future.

  15. Surface effects in metal oxide-based nanodevices

    KAUST Repository

    Lien, Der Hsien; Duran Retamal, Jose Ramon; Ke, Jr Jian; Kang, Chen Fang; He, Jr-Hau

    2015-01-01

    As devices shrink to the nanoscale, surface-to-volume ratio increases and the surface-environment interaction becomes a major factor for affecting device performance. The variation of electronic properties, including the surface band bending, gas chemisorption or photodesorption, native surface defects, and surface roughness, is called "surface effects". Such effects are ambiguous because they can be either negative or beneficial effects, depending on the environmental conditions and device application. This review provides an introduction to the surface effects on different types of nanodevices, offering the solutions to respond to their benefits and negative effects and provides an outlook on further applications regarding the surface effect. This review is beneficial for designing nano-enabled photodetectors, harsh electronics, memories, sensors and transistors via surface engineering.

  16. Surface effects in metal oxide-based nanodevices

    KAUST Repository

    Lien, Der Hsien

    2015-10-29

    As devices shrink to the nanoscale, surface-to-volume ratio increases and the surface-environment interaction becomes a major factor for affecting device performance. The variation of electronic properties, including the surface band bending, gas chemisorption or photodesorption, native surface defects, and surface roughness, is called "surface effects". Such effects are ambiguous because they can be either negative or beneficial effects, depending on the environmental conditions and device application. This review provides an introduction to the surface effects on different types of nanodevices, offering the solutions to respond to their benefits and negative effects and provides an outlook on further applications regarding the surface effect. This review is beneficial for designing nano-enabled photodetectors, harsh electronics, memories, sensors and transistors via surface engineering.

  17. Engineering of Surface Chemistry for Enhanced Sensitivity in Nanoporous Interferometric Sensing Platforms.

    Science.gov (United States)

    Law, Cheryl Suwen; Sylvia, Georgina M; Nemati, Madieh; Yu, Jingxian; Losic, Dusan; Abell, Andrew D; Santos, Abel

    2017-03-15

    We explore new approaches to engineering the surface chemistry of interferometric sensing platforms based on nanoporous anodic alumina (NAA) and reflectometric interference spectroscopy (RIfS). Two surface engineering strategies are presented, namely (i) selective chemical functionalization of the inner surface of NAA pores with amine-terminated thiol molecules and (ii) selective chemical functionalization of the top surface of NAA with dithiol molecules. The strong molecular interaction of Au 3+ ions with thiol-containing functional molecules of alkane chain or peptide character provides a model sensing system with which to assess the sensitivity of these NAA platforms by both molecular feature and surface engineering. Changes in the effective optical thickness of the functionalized NAA photonic films (i.e., sensing principle), in response to gold ions, are monitored in real-time by RIfS. 6-Amino-1-hexanethiol (inner surface) and 1,6-hexanedithiol (top surface), the most sensitive functional molecules from approaches i and ii, respectively, were combined into a third sensing strategy whereby the NAA platforms are functionalized on both the top and inner surfaces concurrently. Engineering of the surface according to this approach resulted in an additive enhancement in sensitivity of up to 5-fold compared to previously reported systems. This study advances the rational engineering of surface chemistry for interferometric sensing on nanoporous platforms with potential applications for real-time monitoring of multiple analytes in dynamic environments.

  18. Friction and surface chemistry of some ferrous-base metallic glasses

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The friction properties of some ferrous-base metallic glasses were measured both in argon and in vacuum to a temperature of 350 C. The alloy surfaces were also analyzed with X-ray photoelectron spectroscopy to identify the compounds and elements present on the surface. The results of the investigation indicate that even when the surfaces of the amorphous alloys, or metallic glasses, are atomically clean, bulk contaminants such as boric oxide and silicon dioxide diffuse to the surfaces. Friction measurements in both argon and vacuum indicate that the alloys exhibit higher coefficients of friction in the crystalline state than they do in the amorphous state.

  19. Study of structure and surface morphology of two-layer contact Ti/Al metallization

    Directory of Open Access Journals (Sweden)

    Kirill D. Vanyukhin

    2016-06-01

    Full Text Available Ti/Al/Ni/Au metallization widely used in the technology of GaN base devices have a very important imperfection i.e. rough surface. There are different opinions about the causes of this imperfection: balling-up of molten aluminum or the appearance of intermetallic melt phases in the Au–Al system. To check the effect of the former cause, we have studied the formation of rough surface after annealing of Ti/Al metallization which is used as a basis of many metallization systems for GaN. The substrates were made from silicon wafers covered with Si3N4 films (0.15 μm. On these substrates we deposited the Ti(12 nm/Al(135 nm metallization system. After the deposition the substrates were annealed in nitrogen for 30 s at 850 °С. The as-annealed specimens were tested for metallization sheet resistivity, appearance and surface morphology. We have shown that during annealing of the Ti/Al metallization system, mutual diffusion of the metals and their active interaction with the formation of intermetallic phases occur. This makes the metallization system more resistant to subsequent annealing, oxidation and chemical etching. After annealing the surface of the Ti/Al metallization system becomes gently matted. However, large hemispherical convex areas (as in the Ti/Al/Ni/Au metallization system do not form. Thus, the hypothesis on the balling-up of molten aluminum on the surface of the Ti/Al metallization system has not been confirmed.

  20. Surface modes at metallic an photonic crystal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Weitao [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    A surface mode is an electromagnetic field distribution bounded at a surface. It decays exponentially with the distance from the surface on both sides of the surface and propagates at the surface. The surface mode exists at a metal-dielectric interface as surface plasmon (1) or at a photonic crystal surface terminated properly (34; 35; 36). Besides its prominent near-filed properties, it can connect structures at its propagation surface and results in far-field effects. Extraordinary transmission (EOT) and beaming are two examples and they are the subjects I am studying in this thesis. EOT means the transmission through holes in an opaque screen can be much larger than the geometrical optics limitation. Based on our everyday experience about shadows, the transmission equals the filling ratio of the holes in geometrical optics. The conventional diffraction theory also proved that the transmission through a subwavelength circular hole in an infinitely thin perfect electric conductor (PEC) film converges to zero when the hole's dimension is much smaller than the wavelength (40). Recently it is discovered that the transmission can be much larger than the the filling ratio of the holes at some special wavelengths (41). This cannot be explained by conventional theories, so it is called extraordinary transmission. It is generally believed that surface plasmons play an important role (43; 44) in the EOT through a periodic subwavelength hole array in a metallic film. The common theories in literatures are based on these arguments. The surface plasmons cannot be excited by incident plane waves directly because of momentum mismatch. The periodicity of the hole arrays will provide addition momentum. When the momentum-matching condition of surface plasmons is satisfied, the surface plasmons will be excited. Then these surface plasmons will collect the energy along the input surface and carry them to the holes. So the transmission can be bigger than the filling ratio. Based

  1. Optical transparency of graphene layers grown on metal surfaces

    International Nuclear Information System (INIS)

    Rut’kov, E. V.; Lavrovskaya, N. P.; Sheshenya, E. S.; Gall, N. R.

    2017-01-01

    It is shown that, in contradiction with the fundamental results obtained for free graphene, graphene films grown on the Rh(111) surface to thicknesses from one to ~(12–15) single layers do not absorb visible electromagnetic radiation emitted from the surface and influence neither the brightness nor true temperature of the sample. At larger thicknesses, such absorption occurs. This effect is observed for the surfaces of other metals, specifically, Pt(111), Re(1010), and Ni(111) and, thus, can be considered as being universal. It is thought that the effect is due to changes in the electronic properties of thin graphene layers because of electron transfer between graphene and the metal substrate.

  2. Optical transparency of graphene layers grown on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rut’kov, E. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Lavrovskaya, N. P. [State University of Aerospace Instrumentation (Russian Federation); Sheshenya, E. S., E-mail: sheshenayket@gmail.ru; Gall, N. R. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2017-04-15

    It is shown that, in contradiction with the fundamental results obtained for free graphene, graphene films grown on the Rh(111) surface to thicknesses from one to ~(12–15) single layers do not absorb visible electromagnetic radiation emitted from the surface and influence neither the brightness nor true temperature of the sample. At larger thicknesses, such absorption occurs. This effect is observed for the surfaces of other metals, specifically, Pt(111), Re(1010), and Ni(111) and, thus, can be considered as being universal. It is thought that the effect is due to changes in the electronic properties of thin graphene layers because of electron transfer between graphene and the metal substrate.

  3. Heavy metal removal from aqueous solutions using engineered magnetic biochars derived from waste marine macro-algal biomass.

    Science.gov (United States)

    Son, Eun-Bi; Poo, Kyung-Min; Chang, Jae-Soo; Chae, Kyu-Jung

    2018-02-15

    Despite the excellent sorption ability of biochar for heavy metals, it is difficult to separate and reuse after adsorption when applied to wastewater treatment process. To overcome these drawbacks, we developed an engineered magnetic biochar by pyrolyzing waste marine macro-algae as a feedstock, and we doped iron oxide particles (e.g., magnetite, maghemite) to impart magnetism. The physicochemical characteristics and adsorption properties of the biochar were evaluated. When compared to conventional pinewood sawdust biochar, the waste marine algae-based magnetic biochar exhibited a greater potential to remove heavy metals despite having a lower surface area (0.97m 2 /g for kelp magnetic biochar and 63.33m 2 /g for hijikia magnetic biochar). Although magnetic biochar could be effectively separated from the solution, however, the magnetization of the biochar partially reduced its heavy metal adsorption efficiency due to the biochar's surface pores becoming plugged with iron oxide particles. Therefore, it is vital to determine the optimum amount of iron doping that maximizes the biochar's separation without sacrificing its heavy metal adsorption efficiency. The optimum concentration of the iron loading solution for the magnetic biochar was determined to be 0.025-0.05mol/L. The magnetic biochar's heavy metal adsorption capability is considerably higher than that of other types of biochar reported previously. Further, it demonstrated a high selectivity for copper, showing two-fold greater removal (69.37mg/g for kelp magnetic biochar and 63.52mg/g for hijikia magnetic biochar) than zinc and cadmium. This high heavy metal removal performance can likely be attributed to the abundant presence of various oxygen-containing functional groups (COOH and OH) on the magnetic biochar, which serve as potential adsorption sites for heavy metals. The unique features of its high heavy metal removal performance and easy separation suggest that the magnetic algae biochar can potentially

  4. Surface passivation of high purity granular metals: zinc, cadmium, lead

    Directory of Open Access Journals (Sweden)

    Pirozhenko L. A.

    2017-10-01

    Full Text Available For the high purity metals (99.9999%, such as zinc, cadmium, and lead, which are widely used as initial components in growing semiconductor and scintillation crystals (CdTe, CdZnTe, ZnSe, (Cd, Zn, Pb WO4, (Cd, Zn, Pb MoO4 et al., it is very important to ensure reliable protection of the surface from oxidation and adsorption of impurities from the atmosphere. The specific features of surface passivation of high purity cadmium, lead and zinc are not sufficiently studied and require specific methodologies for further studies. The use of organic solutions in the schemes of chemical passivation of the investigated metals avoids hydrolysis of the obtained protective films. The use of organic solvents with pure cation and anion composition as the washing liquid prevents chemisorption of ions present in the conventionally used distilled water. This keeps the original purity of the granular metals. Novel compositions of etchants and etching scheme providing simultaneous polishing and passivation of high purity granular Zn, Cd and Pb are developed. Chemical passivation allows storing metals in the normal atmospheric conditions for more than half a year for Zn and Cd and up to 30 days for Pb without changing the state of the surface. The use of the glycerol-DMF solution in the processes for obtaining Pb granules provides self-passivation of metal surfaces and eliminates the additional chemical processing while maintaining the quality of corrosion protection.

  5. Hydrogen collisions with transition metal surfaces: Universal electronically nonadiabatic adsorption

    Science.gov (United States)

    Dorenkamp, Yvonne; Jiang, Hongyan; Köckert, Hansjochen; Hertl, Nils; Kammler, Marvin; Janke, Svenja M.; Kandratsenka, Alexander; Wodtke, Alec M.; Bünermann, Oliver

    2018-01-01

    Inelastic scattering of H and D atoms from the (111) surfaces of six fcc transition metals (Au, Pt, Ag, Pd, Cu, and Ni) was investigated, and in each case, excitation of electron-hole pairs dominates the inelasticity. The results are very similar for all six metals. Differences in the average kinetic energy losses between metals can mainly be attributed to different efficiencies in the coupling to phonons due to the different masses of the metal atoms. The experimental observations can be reproduced by molecular dynamics simulations based on full-dimensional potential energy surfaces and including electronic excitations by using electronic friction in the local density friction approximation. The determining factors for the energy loss are the electron density at the surface, which is similar for all six metals, and the mass ratio between the impinging atoms and the surface atoms. Details of the electronic structure of the metal do not play a significant role. The experimentally validated simulations are used to explore sticking over a wide range of incidence conditions. We find that the sticking probability increases for H and D collisions near normal incidence—consistent with a previously reported penetration-resurfacing mechanism. The sticking probability for H or D on any of these metals may be represented as a simple function of the incidence energy, Ein, metal atom mass, M, and incidence angle, 𝜗i n. S =(S0+a ṡEi n+b ṡM ) *(1 -h (𝜗i n-c ) (1 -cos(𝜗 i n-c ) d ṡh (Ei n-e ) (Ei n-e ) ) ) , where h is the Heaviside step function and for H, S0 = 1.081, a = -0.125 eV-1, b =-8.40 ṡ1 0-4 u-1, c = 28.88°, d = 1.166 eV-1, and e = 0.442 eV; whereas for D, S0 = 1.120, a = -0.124 eV-1, b =-1.20 ṡ1 0-3 u-1, c = 28.62°, d = 1.196 eV-1, and e = 0.474 eV.

  6. Removing roughness on metal surface by irradiation of intense short-pulsed ion beams

    International Nuclear Information System (INIS)

    Hashimoto, Y.

    1995-01-01

    Surface modification of metals with an intense pulsed ion beam (IPIB) was studied experimentally. When the temperature rise of metal surfaces by IPIB irradiation exceeds their boiling point, it is found that machining roughness on surfaces is removed. The experiments were performed with the pulsed power generator HARIMA-II at Himeji Institute of Technology. The main components of the ion beam were carbon and fluorine ions. The IPIB was irradiated to metal plates (Al, Cu and Ti) which were placed at the focal point. Machining roughness on Ti surface was removed after IPIB irradiation, while roughness on Al and Cu plates was not removed. Using the present experimental parameters (beam power density: 32 W/cm 2 , pulse width: 25 ns), the temperature rise of the Ti surface was estimated to be 8,100 K which exceed its boiling point (3,000 K). However, the estimated temperatures of Al and Cu surfaces was 2,500 and 1,500 K, respectively, that are less than their boiling points. These studies above suggests that temperature rise over the boiling point of metals is necessary for removing machining roughness on metal surfaces

  7. Calculation of the surface energy of hcp-metals with the empirical electron theory

    International Nuclear Information System (INIS)

    Fu Baoqin; Liu Wei; Li Zhilin

    2009-01-01

    A brief introduction of the surface model based on the empirical electron theory (EET) and the dangling bond analysis method (DBAM) is presented in this paper. The anisotropy of spatial distribution of covalent bonds of hexagonal close-packed (hcp) metals such as Be, Mg, Sc, Ti, Co, Zn, Y, Zr, Tc, Cd, Hf, and Re, has been analyzed. And under the first-order approximation, the calculated surface energy values for low index surfaces of these hcp-metals are in agreement with experimental and other theoretical values. Correlated analysis showed that the anisotropy of surface energy of hcp-metals was related with the ratio of lattice constants (c/a). The calculation method for the research of surface energy provides a good basis for models of surface science phenomena, and the model may be extended to the surface energy estimation of more metals, alloys, ceramics, and so on, since abundant information about the valence electronic structure (VES) is generated from EET.

  8. Spectral force analysis using atomic force microscopy reveals the importance of surface heterogeneity in bacterial and colloid adhesion to engineered surfaces.

    Science.gov (United States)

    Ma, Huilian; Winslow, Charles J; Logan, Bruce E

    2008-04-01

    Coatings developed to reduce biofouling of engineered surfaces do not always perform as expected based on their native properties. One reason is that a relatively small number of highly adhesive sites, or the heterogeneity of the coated surface, may control the overall response of the system to initial bacterial deposition. It is shown here using an approach we call spectral force analysis (SFA), based on force volume imaging of the surface with atomic force microscopy, that the behavior of surfaces and coatings can be better understood relative to bacterial adhesion. The application of vapor deposited TiO(2) metal oxide increased bacterial and colloid adhesion, but coating the surface with silica oxide reduced adhesion in a manner consistent with SFA based on analysis of the "stickiest" sites. Application of a TiO(2)-based paint to a surface produced a relatively non-fouling surface. Addition of a hydrophilic layer coating to this surface should have decreased fouling. However, it was observed that this coating actually increased fouling. Using SFA it was shown that the reason for the increased adhesion of bacteria and particles to the hydrophilic layer was that the surface produced by this coating was highly heterogeneous, resulting in a small number of sites that created a stickier surface. These results show that while it is important to manufacture surfaces with coatings that are relatively non-adhesive to bacteria, it is also essential that these coatings have a highly uniform surface chemistry.

  9. Surface chemistry and fundamental limitations on the plasma cleaning of metals

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Bin, E-mail: bindong@my.unt.edu [Department of Chemistry, University of North Texas, 1155 Union Circle 305070, Denton, TX, 76203 (United States); Driver, M. Sky, E-mail: Marcus.Driver@unt.edu [Department of Chemistry, University of North Texas, 1155 Union Circle 305070, Denton, TX, 76203 (United States); Emesh, Ismail, E-mail: Ismail_Emesh@amat.com [Applied Materials Inc., 3050 Bowers Ave, Santa Clara, CA, 95054 (United States); Shaviv, Roey, E-mail: Roey_Shaviv@amat.com [Applied Materials Inc., 3050 Bowers Ave, Santa Clara, CA, 95054 (United States); Kelber, Jeffry A., E-mail: Jeffry.Kelber@unt.edu [Department of Chemistry, University of North Texas, 1155 Union Circle 305070, Denton, TX, 76203 (United States)

    2016-10-30

    Highlights: • O{sub 2}-free plasma treatment of air-exposed Co or Cu surfaces yields remnant C layers inert to further plasma cleaning. • The formation of the remnant C layer is graphitic (Cu) or carbidic (Co). • The formation of a remnant C layer is linked to plasma cleaning of a metal surface. - Abstract: In-situ X-ray photoelectron spectroscopy (XPS) studies reveal that plasma cleaning of air-exposed Co or Cu transition metal surfaces results in the formation of a remnant C film 1–3 monolayers thick, which is not reduced upon extensive further plasma exposure. This effect is observed for H{sub 2} or NH{sub 3} plasma cleaning of Co, and He or NH{sub 3} plasma cleaning of Cu, and is observed with both inductively coupled (ICP) and capacitively-coupled plasma (CCP). Changes in C 1 s XPS spectra indicate that this remnant film formation is accompanied by the formation of carbidic C on Co and of graphitic C on Cu. This is in contrast to published work showing no such remnant carbidic/carbon layer after similar treatments of Si oxynitride surfaces. The observation of the remnant carbidic C film on Co and graphitic film on Cu, but not on silicon oxynitride (SiO{sub x}N{sub y}), regardless of plasma chemistry or type, indicates that this effect is due to plasma induced secondary electron emission from the metal surface, resulting in transformation of sp{sup 3} adventitious C to either a metal carbide or graphite. These results suggest fundamental limitations to plasma-based surface cleaning procedures on metal surfaces.

  10. Heavy Metals Pollution on Surface Water Sources in Kaduna ...

    African Journals Online (AJOL)

    This study examine the effects of heavy metal pollutants to aquatic ecosystems and the environment by considering the role of urban, municipal, agricultural, industrial and other anthropogenic processes as sources of heavy metal pollution in surface water sources of Kaduna metropolis. Samples of the polluted water were ...

  11. Enhanced photochemistry on metal surfaces

    International Nuclear Information System (INIS)

    Goncher, G.M.; Parsons, C.A.; Harris, C.B.

    1984-01-01

    Due to the fast relaxation of molecular excited states in the vicinity of a metal or semiconductor surface, few observations of surface photochemistry have been reported. The following work concerns the surface-enhanced photo-reactions of a variety of physisorbed molecules on roughened Ag surfaces. In summary, photodecomposition leads to a graphitic surface carbon product which is monitored via surface-enhanced Raman scattering. In most cases an initial two-photon molecular absorption step followed by further absorption and fragmentation is thought to occur. Enhancement of the incident fields occurs through roughness-mediated surface plasmon resonances. This mechanism provides the amplified electromagnetic surface fields responsible for the observed photodecomposition. The photodecomposition experiments are performed under ultra-high vacuum. Surface characterization of the roughened surfaces was done by Scanning Electron Microscopy (SEM), and electron-stimulated emission. The SEM revealed morphology on the order of 300-400 A. This size of roughness feature, when modelled as isolated spheres should exhibit the well-known Mie resonances for light of the correct wavelengths. For protrusions existing on a surface these Mie resonances can be thought of as a coupling of the light with the surface plasmon. Experimental verification of these resonances was provided by the electron-stimulated light emission results. These showed that a polished Ag surface emitted only the expected transition radiation at the frequency of the Ag bulk plasmon. Upon roughening, however, a broad range of lower frequencies extending well into the visible are seen from electron irradiation of the surface. Large enhancements are expected for those frequencies which are able to couple into the surface modes

  12. Resonant Excitation of Terahertz Surface Plasmons in Subwavelength Metal Holes

    Directory of Open Access Journals (Sweden)

    Weili Zhang

    2007-01-01

    Full Text Available We present a review of experimental studies of resonant excitation of terahertz surface plasmons in two-dimensional arrays of subwavelength metal holes. Resonant transmission efficiency higher than unity was recently achieved when normalized to the area occupied by the holes. The effects of hole shape, hole dimensions, dielectric function of metals, polarization dependence, and array film thickness on resonant terahertz transmission in metal arrays were investigated by the state-of-the-art terahertz time-domain spectroscopy. In particular, extraordinary terahertz transmission was demonstrated in arrays of subwavelength holes made even from Pb, a generally poor metal, and having thickness of only one-third of skin depth. Terahertz surface plasmons have potential applications in terahertz imaging, biosensing, interconnects, and development of integrated plasmonic components for terahertz generation and detection.

  13. Surface modifying method for metal member

    International Nuclear Information System (INIS)

    Amano, Kazuo; Enomoto, Kunio; Hirano, Akihiko; Hirano, Atsuya; Hattori, Shigeo; Hayashi, Eisaku; Ueyama, Toshiharu; Hayashi, Makoto

    1998-01-01

    A surface of a metal member such as carbon steel to be used in a corrosion circumstance such as in a nuclear power plant and a thermoelectric plant are polished. A printing method is conducted for removing obstacles on the surface of the member. Namely, a photographing printing paper immersed in a diluted sulfuric acid solution is appended tightly to the portion with its surface polished smoothly. Sulfur present in the form of an obstacle of MnS or present alone in the material reacts with the sulfuric acid to form a sulfuric acid gas, and reacts with Ag of the printing paper to discolor the printing paper to brown. When a peeled printing paper is discolored to brown, sulfur printing is repeated. After conforming that the peeled printing paper is white, the surface is washed. Subsequently, surface plasticization is conducted by water jet peening or shot peening. (I.N.)

  14. Fractal modeling of fluidic leakage through metal sealing surfaces

    Science.gov (United States)

    Zhang, Qiang; Chen, Xiaoqian; Huang, Yiyong; Chen, Yong

    2018-04-01

    This paper investigates the fluidic leak rate through metal sealing surfaces by developing fractal models for the contact process and leakage process. An improved model is established to describe the seal-contact interface of two metal rough surface. The contact model divides the deformed regions by classifying the asperities of different characteristic lengths into the elastic, elastic-plastic and plastic regimes. Using the improved contact model, the leakage channel under the contact surface is mathematically modeled based on the fractal theory. The leakage model obtains the leak rate using the fluid transport theory in porous media, considering that the pores-forming percolation channels can be treated as a combination of filled tortuous capillaries. The effects of fractal structure, surface material and gasket size on the contact process and leakage process are analyzed through numerical simulations for sealed ring gaskets.

  15. Optimized Hypernetted-Chain Solutions for Helium -4 Surfaces and Metal Surfaces

    Science.gov (United States)

    Qian, Guo-Xin

    This thesis is a study of inhomogeneous Bose systems such as liquid ('4)He slabs and inhomogeneous Fermi systems such as the electron gas in metal films, at zero temperature. Using a Jastrow-type many-body wavefunction, the ground state energy is expressed by means of Bogoliubov-Born-Green-Kirkwood -Yvon and Hypernetted-Chain techniques. For Bose systems, Euler-Lagrange equations are derived for the one- and two -body functions and systematic approximation methods are physically motivated. It is shown that the optimized variational method includes a self-consistent summation of ladder- and ring-diagrams of conventional many-body theory. For Fermi systems, a linear potential model is adopted to generate the optimized Hartree-Fock basis. Euler-Lagrange equations are derived for the two-body correlations which serve to screen the strong bare Coulomb interaction. The optimization of the pair correlation leads to an expression of correlation energy in which the state averaged RPA part is separated. Numerical applications are presented for the density profile and pair distribution function for both ('4)He surfaces and metal surfaces. Both the bulk and surface energies are calculated in good agreement with experiments.

  16. Image-potential states on the metallic (111) surface of bismuth

    International Nuclear Information System (INIS)

    Muntwiler, Matthias; Zhu, X-Y

    2008-01-01

    An extended series (up to n=6, in quantum beats) of image-potential states (IPS) is observed in time-resolved two-photon photoelectron (TR-2PPE) spectroscopy of the Bi(111) surface. Although mainly located in the vacuum, these states probe various properties of the electronic structure of the surface as reflected in their energetics and dynamics. Based on the observation of IPS a projected gap in the surface normal direction is inferred in the region from 3.57 to 4.27 eV above the Fermi level. Despite this band gap, the lifetimes of the IPS are shorter than on comparable metals, which is an indication of the metallic character of the Bi(111) surface.

  17. Palladium mixed-metal surface-modified AB5-type intermetallides enhance hydrogen sorption kinetics

    Directory of Open Access Journals (Sweden)

    Roman V. Denys

    2010-09-01

    Full Text Available Surface engineering approaches were adopted in the preparation of advanced hydrogen sorption materials, based on ‘low-temperature’, AB5-type intermetallides. The approaches investigated included micro-encapsulation with palladium and mixed-metal mantles using electroless plating. The influence of micro-encapsulation on the surface morphology and kinetics of hydrogen charging were investigated. It was found that palladium-nickel (Pd-Ni co-deposition by electroless plating significantly improved the kinetics of hydrogen charging of the AB5-type intermetallides at low hydrogen pressure and temperature, after long-term pre-exposure to air. The improvement in the kinetics of hydrogen charging was credited to a synergistic effect between the palladium and nickel atoms in the catalytic mantle and the formation of an ‘interfacial bridge’ for hydrogen diffusion by the nickel atoms in the deposited layer. The developed surface-modified materials may find application in highly selective hydrogen extraction, purification, and storage from impure hydrogen feeds.

  18. A comparison of surface properties of metallic thin film photocathodes

    CERN Document Server

    Mistry, Sonal; Valizadeh, Reza; Jones, L.B; Middleman, Keith; Hannah, Adrian; Militsyn, B.L; Noakes, Tim

    2017-01-01

    In this work the preparation of metal photocathodes by physical vapour deposition magnetron sputtering has been employed to deposit metallic thin films onto Cu, Mo and Si substrates. The use of metallic cathodes offers several advantages: (i) metal photocathodes present a fast response time and a relative insensitivity to the vacuum environment (ii) metallic thin films when prepared and transferred in vacuum can offer smoother and cleaner emitting surfaces. The photocathodes developed here will ultimately be used in S-band Normal Conducting RF (NCRF) guns such as that used in VELA (Versatile Electron Linear Accelerator) and the proposed CLARA (Compact Linear Accelerator for Research and Applications) Free Electron Laser test facility. The samples grown on Si substrates were used to investigate the morphology and thickness of the film. The samples grown onto Cu and Mo substrates were analysed and tested as photocathodes in a surface characterisation chamber, where X-Ray Photoelectron spectroscopy (XPS) was emp...

  19. Terahertz plasmon and surface-plasmon modes in cylindrical metallic nanowires

    International Nuclear Information System (INIS)

    Wu Ping; Xu Wen; Li Long-Long; Lu Tie-Cheng; Wu Wei-Dong

    2014-01-01

    We present a theoretical study on collective excitation modes associated with plasmon and surface-plasmon oscillations in cylindrical metallic nanowires. Based on a two-subband model, the dynamical dielectric function matrix is derived under the random-phase approximation. An optic-like branch and an acoustic-like branch, which are free of Landau damping, are observed for both plasmon and surface-plasmon modes. Interestingly, for surface-plasmon modes, we find that two branches of the dispersion relation curves converge at a wavevector q z = q max beyond which no surface-plasmon mode exists. Moreover, we examine the dependence of these excitation modes on sample parameters such as the radius of the nanowires. It is found that in metallic nanowires realized by state-of-the-art nanotechnology the intra- and inter-subband plasmon and surface-plasmon frequencies are in the terahertz bandwidth. The frequency of the optic-like modes decreases with increasing radius of the nanowires, whereas that of the acoustic-like modes is not sensitive to the variation of the radius. This study is pertinent to the application of metallic nanowires as frequency-tunable terahertz plasmonic devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Multifunctional methacrylate-based coatings for glass and metal surfaces

    Science.gov (United States)

    Pospiech, Doris; Jehnichen, Dieter; Starke, Sandra; Müller, Felix; Bünker, Tobias; Wollenberg, Anne; Häußler, Liane; Simon, Frank; Grundke, Karina; Oertel, Ulrich; Opitz, Michael; Kruspe, Rainer

    2017-03-01

    In order to prevent freshwater biofouling glass and metal surfaces were coated with novel transparent methacrylate-based copolymers. The multifunctionality of the copolymers, such as adhesion to the substrate, surface polarity, mechanical long-term stability in water, and ability to form metal complexes was inserted by the choice of suitable comonomers. The monomer 2-acetoacetoxy ethyl methacrylate (AAMA) was used as complexing unit to produce copper(II) complexes in the coating's upper surface layer. The semifluorinated monomer 1H,1H,2H,2H-perfluorodecyl methacrylate was employed to adjust the surface polarity and wettability. Comprehensive surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surface compositions and properties can be easily adjusted by varying the concentrations of the comonomers. The formation of copper(II) complexes along the copolymer chains and their stability against washing out with plenty of water was proven by XPS. Copolymers containing semifluorinated comonomers significantly inhibited the growth of Achnanthidium species. Copolymers with copper-loaded AAMA-sequences were able to reduce both the growth of Achnanthidium spec. and Staphylococcus aureus.

  1. Probing molecular dynamics of metal borohydrides on the surface of mesoporous scaffolds by multinuclear high resolution solid state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Son-Jong, E-mail: Sonjong@cheme.caltech.edu [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Hyun-Sook [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); To, Magnus [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Young-Su; Cho, Young Whan [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Choi, Hyungkeun; Kim, Chul [Department of Chemistry, Hannam University, Daejeon 305-811 (Korea, Republic of)

    2015-10-05

    Graphical abstract: In situ variable temperature multinuclear solid state NMR allows to probe surface wetting, diffusivity, and confinement of metal borohydrides into nanopores. - Abstract: Understanding of surface interactions between borohydride molecules and the surfaces of porous supports have gained growing attention for successful development of nano-confinement engineering. By use of in situ variable temperature (VT) magic angle spinning (MAS) NMR, molecular mobility changes of LiBH{sub 4} crystalline solid has been investigated in the presence of silica based and carbonaceous surfaces. Spin–spin J-coupling of {sup 1}H–{sup 11}B in LiBH{sub 4} was monitored in series of VT NMR spectra to probe translational mobility of LiBH{sub 4} that appeared to be greatly enhanced upon surface contact. Such enhanced diffusivity was found to be effective in the formation of solid solution and co-confinement with other metal borohydrides. Co-confinement of LiBH{sub 4}–Ca(BH{sub 4}){sub 2} mixture was demonstrated at temperature as low as 100 °C, much lower than the reported bulk eutectic melting temperature. The discovery adds a novel property of LiBH{sub 4} that has been proven to be highly versatile in many energy related applications.

  2. Asperity interaction in adhesive contact of metallic rough surfaces

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    The analysis of adhesive contact of metallic rough surfaces considering the effect of asperity interaction is the subject of this investigation. The micro-contact model of asperity interactions developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64) is combined with the elastic plastic adhesive contact model developed by Chang et al (1988 Trans. ASME: J. Tribol. 110 50-6) to consider the asperity interaction and elastic-plastic deformation in the presence of surface forces simultaneously. The well-established elastic adhesion index and plasticity index are used to consider the different contact conditions. Results show that asperity interaction influences the load-separation behaviour in elastic-plastic adhesive contact of metallic rough surfaces significantly and, in general, adhesion is reduced due to asperity interactions

  3. Exploring liquid metal plasma facing component (PFC) concepts-Liquid metal film flow behavior under fusion relevant magnetic fields

    International Nuclear Information System (INIS)

    Narula, M.; Abdou, M.A.; Ying, A.; Morley, N.B.; Ni, M.; Miraghaie, R.; Burris, J.

    2006-01-01

    The use of fast moving liquid metal streams or 'liquid walls' as a plasma contact surface is a very attractive option and has been looked upon with considerable interest over the past several years, both by the plasma physics and fusion engineering programs. Flowing liquid walls provide an ever replenishing contact surface to the plasma, leading to very effective particle pumping and surface heat flux removal. A key feasibility issue for flowing liquid metal plasma facing component (PFC) systems, pertains to their magnetohydrodynamic (MHD) behavior under the spatially varying magnetic field environment, typical of a fusion device. MHD forces hinder the development of a smooth and controllable liquid metal flow needed for PFC applications. The present study builds up on the ongoing research effort at UCLA, directed towards providing qualitative and quantitative data on liquid metal free surface flow behavior under fusion relevant magnetic fields

  4. Application Of Holographic Interferometry For Investigation Of Microroughness Of Engineering Surfaces

    Science.gov (United States)

    Lech, Marek; Mruk, Irena; Stupnicki, Jacek

    1985-01-01

    The paper describes an improved immersion method of holographic interferometry /IMHI/ adjusted for studies of roughness of engineering surfaces. Special optical arrangement, with two types of immersion cells and adequate technique of preparing transparent replicas reproducting with high fidelity details of differently machined surfaces was elaborated. It permits to obtain the contour maps of the surface asperities with intervals between the planes of succesive contour lines within a range of 1 μm. The results obtained for some engineering surfaces are given.

  5. Insights into the superhydrophobicity of metallic surfaces prepared by electrodeposition involving spontaneous adsorption of airborne hydrocarbons

    International Nuclear Information System (INIS)

    Liu, Peng; Cao, Ling; Zhao, Wei; Xia, Yue; Huang, Wei; Li, Zelin

    2015-01-01

    Graphical abstract: - Highlights: • Several superhydrophobic metallic surfaces were fabricated by fast electrodeposition. • Both micro/nanostructures and adsorption of airborne hydrocarbons make contributions. • XPS analyses confirm presence of airborne hydrocarbons on these metallic surfaces. • The adsorption of airborne hydrocarbons on the clean metal Au surface was very quick. • UV-O 3 treatment oxidized the hydrocarbons to hydrophilic oxygen-containing organics. - Abstract: Electrochemical fabrication of micro/nanostructured metallic surfaces with superhydrophobicity has recently aroused great attention. However, the origin still remains unclear why smooth hydrophilic metal surfaces become superhydrophobic by making micro/nanostructures without additional surface modifications. In this work, several superhydrophobic micro/nanostructured metal surfaces were prepared by a facile one-step electrodeposition process, including non-noble and noble metals such as copper, nickel, cadmium, zinc, gold, and palladium with (e.g. Cu) or without (e.g. Au) surface oxide films. We demonstrated by SEM and XPS that both hierarchical micro/nanostructures and spontaneous adsorption of airborne hydrocarbons endowed these surfaces with excellent superhydrophobicity. We revealed by XPS that the adsorption of airborne hydrocarbons at the Ar + -etched clean Au surface was rather quick, such that organic contamination can hardly be prevented in practical operation of surface wetting investigation. We also confirmed by XPS that ultraviolet-O 3 treatment of the superhydrophobic metal surfaces did not remove the adsorbed hydrocarbons completely, but mainly oxidized them into hydrophilic oxygen-containing organic substances. We hope our findings here shed new light on deeper understanding of superhydrophobicity for micro/nanostructured metal surfaces with and without surface oxide films

  6. RFID Label Tag Design for Metallic Surface Environments

    Directory of Open Access Journals (Sweden)

    Ki Hwan Eom

    2011-01-01

    Full Text Available This paper describes a metal mount RFID tag that works reliably on metallic surfaces. The method proposes the use of commercial label type RFID tags with 2.5 mm thick Styrofoam103.7 with a relative permittivity of 1.03 attached on the back of the tag. In order to verify the performance of the proposed method, we performed experiments on an electric transformer supply chain system. The experimental results showed that the proposed tags can communicate with readers from a distance of 2 m. The recognition rates are comparable to those of commercial metallic mountable tags.

  7. Spoof surface plasmon modes on doubly corrugated metal surfaces at terahertz frequencies

    International Nuclear Information System (INIS)

    Liu, Yong-Qiang; Kong, Ling-Bao; Du, Chao-Hai; Liu, Pu-Kun

    2016-01-01

    Spoof surface plasmons (SSPs) have many potential applications such as imaging and sensing, communications, innovative leaky wave antenna and many other passive devices in the microwave and terahertz (THz) spectrum. The extraordinary properties of SSPs (e.g. extremely strong near field, enhanced beam–wave interaction) make them especially attractive for developing novel THz electronic sources. SSP modes on doubly corrugated metal surfaces are investigated and analyzed both theoretically and numerically in this paper. The analytical SSP dispersion expressions of symmetric and anti-symmetric modes are obtained with a simplified modal field expansion method; the results are also verified by the finite integration method. Additionally, the propagation losses are also considered for real copper surfaces with a limited constant conductivity in a THz regime. It is shown that the asymptotical frequency of the symmetric mode at the Brillouin boundary decreases along with the decreased gap size between these two corrugated metal surfaces while the asymptotical frequency increases for the anti-symmetric mode. The anti-symmetric mode demonstrates larger propagation losses than the symmetric mode. Further, the losses for both symmetric and anti-symmetric modes decrease when this gap size enlarges. By decreasing groove depth, the asymptotical frequency increases for both the symmetric and the anti-symmetric mode, but the variation of propagation losses is more complicated. Propagation losses increase along with the increased period. Our studies on the dispersion characteristics and propagation losses of SSP modes on this doubly corrugated metallic structure with various parameters is instructive for numerous applications such as waveguides, circuitry systems with high integration, filters and powerful electronic sources in the THz regime. (paper)

  8. Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering

    Science.gov (United States)

    Renaud, Gilles

    Experimental determinations of the atomic structure of insulating oxide surfaces and metal/oxide interfaces are scarce, because surface science techniques are often limited by the insulating character of the substrate. Grazing incidence X-ray scattering (GIXS), which is not subject to charge effects, can provide very precise information on the atomic structure of oxide surfaces: roughness, relaxation and reconstruction. It is also well adapted to analyze the atomic structure, the registry, the misfit relaxation, elastic or plastic, the growth mode and the morphology of metal/oxide interfaces during their growth, performed in situ. GIXS also allows the analysis of thin films and buried interfaces, in a non-destructive way, yielding the epitaxial relationships, and, by variation of the grazing incidence angle, the lattice parameter relaxation along the growth direction. On semi-coherent interfaces, the existence of an ordered network of interfacial misfit dislocations can be demonstrated, its Burger's vector determined, its ordering during in situ annealing cycles followed, and sometimes even its atomic structure can be addressed. Careful analysis during growth allows the modeling of the dislocation nucleation process. This review emphasizes the new information that GIXS can bring to oxide surfaces and metal/oxide interfaces by comparison with other surface science techniques. The principles of X-ray diffraction by surfaces and interfaces are recalled, together with the advantages and properties of grazing angles. The specific experimental requirements are discussed. Recent results are presented on the determination of the atomic structure of relaxed or reconstructed oxide surfaces. A description of results obtained during the in situ growth of metal on oxide surfaces is also given, as well as investigations of thick metal films on oxide surfaces, with lattice parameter misfit relaxed by an array of dislocations. Recent work performed on oxide thin films having

  9. Designing porous metallic glass compact enclosed with surface iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jae Young; Park, Hae Jin; Hong, Sung Hwan; Kim, Jeong Tae; Kim, Young Seok; Park, Jun-Young; Lee, Naesung [Hybrid Materials Center (HMC), Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Seo, Yongho [Graphene Research Institute (GRI) & HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, Jin Man, E-mail: jinman_park@hotmail.com [Global Technology Center, Samsung Electronics Co., Ltd, 129 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-742 (Korea, Republic of); Kim, Ki Buem, E-mail: kbkim@sejong.ac.kr [Hybrid Materials Center (HMC), Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2015-06-25

    Highlights: • Porous metallic glass compact was developed using electro-discharge sintering process. • Uniform PMGC can only be achieved when low electrical input energy was applied. • Functional iron-oxides were formed on the surface of PMGCs by hydrothermal technique. - Abstract: Porous metallic glass compact (PMGC) using electro-discharge sintering (EDS) process of gas atomized Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} metallic glass powder was developed. The formation of uniform PMGC can only be achieved when low electrical input energy was applied. Functional iron-oxides were formed on the surface of PMGCs by hydrothermal technique. This finding suggests that PMGC can be applied in the new area such as catalyst via hydrothermal technique and offer a promising guideline for using the metallic glasses as a potential functional application.

  10. HEAVY METALS IN SURFACE MUD SEDIMENT IN EKATERINBURG (RUSSIA

    Directory of Open Access Journals (Sweden)

    A. A. Seleznev

    2018-03-01

    Full Text Available Problem Statement. Now the most part of the world’s population lives in cities, thus, it is relevant the search for universal, low-cost and express methods for environmental geochemical investigations of an urban environment. The objective of the study is the assessment of content and properties of surface mud sediment at the urban territory (on the example of Ekaterinburg, Russia. Methods of the study. The 30 samples of surface mud sediment, soils and ground were collected in the residential area of the city. Particle size composition, measurements of heavy metals content, correlation analysis was conducted for the samples. Results. Surface mud sediment at the residential territories can be classified as surface facie of the recent anthropogenic sediment. Samples of the environmental compartments were collected at the territories of six blocks of houses of various years of construction, located in various parts of the city and at the various geological units. Five samples were collected in each block: 3 samples within the block and 2 samples – outside. The content of Pb, Zn, Cu, Ni, Co, and Mn was measured in particle size fractions of the samples. Particle size composition of the surface mud sediment in Ekaterinburg is similar to the particle size composition of the grounds formed on the sediments of Holocene age in Urals region. The positive statistically significant correlation was found between the couples of metals: Zn and Pb, Zn and Cu, Co and Ni. The distribution of concentrations of Pb, Zn and Cu over particle size fractions of surface mud sediment is heterogeneous. Pollution of the ground and soil in urban areas is due to the transition of heavy metals with particles of dust and fine sand. Typical geochemical association of metals for particle size fraction of surface mud sediment 0.002–0.01 mm – Mn-Zn-Ni-Cu-Pb-Co, that is similar to the association for sediments of surface puddles in local zones of relief, soils and bottom

  11. Adaptation of metal arc plasma source to plasma source ion implantation

    International Nuclear Information System (INIS)

    Shamim, M.M.; Fetherston, R.P.; Conrad, J.R.

    1995-01-01

    In Plasma Source Ion Implantation (PSII) a target is immersed in a plasma and a train of high negative voltage pulses is applied to accelerate ions into the target and to modify the properties in the near surface region. In PSII, until now the authors have been using gaseous species to generate plasmas. However metal ion plasma may be used to modify the surface properties of material for industrial applications. Conventionally the ion implantation of metal ions is performed using beam line accelerators which have complex engineering and high cost. The employment of a metal arc source to PSII has tremendous potential due to its ability to process the conformal surfaces, simple engineering and cost effectiveness. They have installed metal arc source for generation of titanium plasma. Currently, they are investigating the properties of titanium plasma and material behavior of titanium implanted aluminum and 52100 steel. The recent results of this investigation are presented

  12. Geometrically induced surface polaritons in planar nanostructured metallic cavities

    Energy Technology Data Exchange (ETDEWEB)

    Davids, P. S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Intravia, F [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalvit, Diego A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-01-14

    We examine the modal structure and dispersion of periodically nanostructured planar metallic cavities within the scattering matrix formulation. By nanostructuring a metallic grating in a planar cavity, artificial surface excitations or spoof plasmon modes are induced with dispersion determined by the periodicity and geometric characteristics of the grating. These spoof surface plasmon modes are shown to give rise to new cavity polaritonic modes at short mirror separations that modify the density of modes in nanostructured cavities. The increased modal density of states form cavity polarirons have a large impact on the fluctuation induced electromagnetic forces and enhanced hear transfer at short separations.

  13. Stabilized Lithium-Metal Surface in a Polysulfide-Rich Environment of Lithium-Sulfur Batteries.

    Science.gov (United States)

    Zu, Chenxi; Manthiram, Arumugam

    2014-08-07

    Lithium-metal anode degradation is one of the major challenges of lithium-sulfur (Li-S) batteries, hindering their practical utility as next-generation rechargeable battery chemistry. The polysulfide migration and shuttling associated with Li-S batteries can induce heterogeneities of the lithium-metal surface because it causes passivation by bulk insulating Li2S particles/electrolyte decomposition products on a lithium-metal surface. This promotes lithium dendrite formation and leads to poor lithium cycling efficiency with complicated lithium surface chemistry. Here, we show copper acetate as a surface stabilizer for lithium metal in a polysulfide-rich environment of Li-S batteries. The lithium surface is protected from parasitic reactions with the organic electrolyte and the migrating polysulfides by an in situ chemical formation of a passivation film consisting of mainly Li2S/Li2S2/CuS/Cu2S and electrolyte decomposition products. This passivation film also suppresses lithium dendrite formation by controlling the lithium deposition sites, leading to a stabilized lithium surface characterized by a dendrite-free morphology and improved surface chemistry.

  14. Surface core-level shifts for simple metals

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1994-01-01

    screening, whereby a SCLS becomes equivalent to the surface segregation energy of a core-ionized atom, a quantity we obtain by separate bulk and surface impurity calculations. The results are in good agreement with experiment in most of those cases where the data originates from single-crystal measurements....... We discuss the surface shifts of the electrostatic potentials and the band centers in order to trace the microscopic origin of the SCLS in the simple metals and find that the anomalous subsurface core-level shifts in beryllium are caused by charge dipoles, which persist several layers into the bulk...

  15. Reactive solute transport in streams: A surface complexation approach for trace metal sorption

    Science.gov (United States)

    Runkel, Robert L.; Kimball, Briant A.; McKnight, Diane M.; Bencala, Kenneth E.

    1999-01-01

    A model for trace metals that considers in-stream transport, metal oxide precipitation-dissolution, and pH-dependent sorption is presented. Linkage between a surface complexation submodel and the stream transport equations provides a framework for modeling sorption onto static and/or dynamic surfaces. A static surface (e.g., an iron- oxide-coated streambed) is defined as a surface with a temporally constant solid concentration. Limited contact between solutes in the water column and the static surface is considered using a pseudokinetic approach. A dynamic surface (e.g., freshly precipitated metal oxides) has a temporally variable solid concentration and is in equilibrium with the water column. Transport and deposition of solute mass sorbed to the dynamic surface is represented in the stream transport equations that include precipitate settling. The model is applied to a pH-modification experiment in an acid mine drainage stream. Dissolved copper concentrations were depressed for a 3 hour period in response to the experimentally elevated pH. After passage of the pH front, copper was desorbed, and dissolved concentrations returned to ambient levels. Copper sorption is modeled by considering sorption to aged hydrous ferric oxide (HFO) on the streambed (static surface) and freshly precipitated HFO in the water column (dynamic surface). Comparison of parameter estimates with reported values suggests that naturally formed iron oxides may be more effective in removing trace metals than synthetic oxides used in laboratory studies. The model's ability to simulate pH, metal oxide precipitation-dissolution, and pH-dependent sorption provides a means of evaluating the complex interactions between trace metal chemistry and hydrologic transport at the field scale.

  16. Surface-enhanced Raman scattering from metal and transition metal nano-caped arrays

    Science.gov (United States)

    Sun, Huanhuan; Gao, Renxian; Zhu, Aonan; Hua, Zhong; Chen, Lei; Wang, Yaxin; Zhang, Yongjun

    2018-03-01

    The metal and transition metal cap-shaped arrays on polystyrene colloidal particle (PSCP) templates were fabricated to study the surface-enhanced Raman scattering (SERS) effect. We obtained the Ag and Fe complex film by a co-sputtering deposition method. The size of the deposited Fe particle was changed by the sputtering power. We also study the SERS enhancement mechanism by decorating the PATP probe molecule on the different films. The SERS signals increased firstly, and then decreased as the size of Fe particles grows gradually. The finite-difference time domain (FDTD) simulation and experimental Raman results manifest that SERS enhancement was mainly attributed to surface plasma resonance (SPR) between Ag and Ag nanoparticles. The SERS signals of PATP molecule were enhanced to reach a lowest detectable concentration of 10-8 mol/L. The research demonstrates that the SERS substrates with Ag-Fe cap-shaped arrays have a high sensitivity.

  17. Raising the shields: PCR in the presence of metallic surfaces protected by tailor-made coatings.

    Science.gov (United States)

    Scherag, Frank D; Brandstetter, Thomas; Rühe, Jürgen

    2014-10-01

    The implementation of PCR reactions in the presence of metallic surfaces is interesting for the generation of novel bioanalytical devices, because metals exhibit high mechanical stability, good thermal conductivity, and flexibility during deformation. However, metallic substrates are usually non-compatible with enzymatic reactions such as PCR due to poisoning of the active center of the enzyme or nonspecific adsorption of the enzymeto the metal surface, which could result in protein denaturation. We present a method for the generation of polymer coatings on metallic surfaces which are designed to minimize protein adsorption and also prevent the release of metal ions. These coatings consist of three layers covalently linked to each other; a self-assembled monolayer to promote adhesion, a photochemically generated barrier layer and a photochemically generated hydrogel. The coatings can be deposited onto aluminum, stainless steel, gold and copper surfaces. We compare PCR efficiencies in the presence of bare metallic surfaces with those of surfaces treated with the novel coating system. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. TXRF study of electrochemical deposition of metals on glass-ceramic carbon electrode surfaces

    International Nuclear Information System (INIS)

    Alov, N.; Oskolok, K.; Wittershagen, A.; Mertens, M.; Rittmeyer, C.; Kolbesen, B.O.

    2000-01-01

    Nowadays the methods of solid surface analysis are widely used to study the thermodynamic and kinetic aspects of joint electrochemical deposition of metals on solid substrates. In this work the surfaces of some binary and ternary metal electrodeposits on disc glass-ceramic carbon electrodes were studied by total-reflection x-ray fluorescence spectroscopy (TXRF). Metal alloys were obtained as a result of electrochemical co-deposition of copper, cadmium and lead from n x 10 -4 M (Cu, Cd, Pb)(NO 3 ) 2 + 0.01 M HNO 3 solutions under mixing. TXRF measurements were performed with an ATOMIKA EXTRA II A spectrometer using Mo K α and W (Brems) primary excitation. The serious advantage of TXRF as a method of near-surface analysis is very high element sensitivity. Apart from main elements (Cu, Cd, Pb) we have detected trace elements (Cl, Ag, Pt, Hg) which are present in working solution and has an effect to the electrodeposit formation. The comparison of TXRF data with information obtained by X-ray photoelectron spectroscopy and electron-probe x-ray microanalysis permits to realize depth profiling electrochemical alloys. In particular it was found that in binary systems Cu-Pb and Cu-Cd the relative lead and cadmium content on the electrodeposit surface is considerably greater than in the bulk. These phenomena are due to the features of metal nucleation and growth mechanisms. High sensitivity of TXRF to surface morphology and the correlation of TXRF and scanning electron microscopy data allow to determine the area of prevailing location of metal in the heterogeneous alloy surface. So we have established that in Cu-Pb and Cu-Cd-Pb systems solid solution of copper and lead is formed: significant part of lead is deposited not only in specific 3D-clusters but also in copper thin film. It was demonstrated that the near-surface TXRF analysis of metal electrodeposits on solid electrodes is highly effective to study the mechanisms of metal nucleation, metal cluster and thin film

  19. Photodetachment of negative ion in a gradient electric field near a metal surface

    International Nuclear Information System (INIS)

    Liu Tian-Qi; Wang De-Hua; Han Cai; Liu Jiang; Liang Dong-Qi; Xie Si-Cheng

    2012-01-01

    Based on closed-orbit theory, the photodetachment of H − in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H − near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps. (atomic and molecular physics)

  20. Superhydrophobic Zr-based metallic glass surface with high adhesive force

    Science.gov (United States)

    Li, Ning; Xia, Ting; Heng, Liping; Liu, Lin

    2013-06-01

    Micro/nano hierarchical structures were constructed on Zr35Ti30Be26.75Cu8.25 metallic glass surface by silicon moulding and subsequently chemical etching. The as-formed surface exhibited both superhydrophobicity and high adhesive force towards water. The superhydrophobicity is rationalized based on the modified Cassie-Baxter model [A. B. D. Cassie and S. Baxter, Trans. Faraday Soc. 40, 546 (1944)]. The origin of the robust adhesion is described in terms of intermolecular capillary forces. The present results not only provide a method to fabricate superhydrophobic metallic glasses surface but also explore an important industrial application as dry adhesives and transport of liquid microdroplets.

  1. High Density Periodic Metal Nanopyramids for Surface Enhanced Raman Spectroscopy

    NARCIS (Netherlands)

    Jin, Mingliang

    2012-01-01

    The work presented in this thesis is focused on two areas. First, a new type of nanotextured noble-metal surface has been developed. The new nanotextured surface is demonstrated to enhance inelastic (Raman) scattering, called surface enhanced Raman scattering (SERS), from molecules adsorbed on the

  2. Heavy metal concentration of settled surface dust in residential building

    International Nuclear Information System (INIS)

    Nor Aimi abdul Wahab; Fairus Muhamad Darus; Norain Isa; Siti Mariam Sumari; Nur Fatihah Muhamad Hanafi

    2012-01-01

    The concentrations of heavy metals (Cu, Ni, Pb and Zn) in settled surface dust were collected from nine residential buildings in different areas in Seberang Prai Tengah District, Pulau Pinang. The samples of settled surface dust were collected in 1 m 2 area by using a polyethylene brush and placed in the dust pan by sweeping the living room floor most accessible to the occupants. Heavy metals concentrations were determined by using inductively coupled plasma optical emission spectrometer (ICP-OES) after digestion with nitric acid and sulphuric acid. The results show that the range of heavy metals observed in residential buildings at Seberang Prai Tengah were in the range of 2.20-14.00 mg/ kg, 1.50-32.70 mg/ kg, 1.50-76.80 mg/ kg and 14.60-54.40 mg/ kg for Cu, Ni, Pb and Zn respectively. The heavy metal concentration in the investigated areas followed the order: Pb > Zn > Ni > Cu. Statistical analysis indicates significant correlation between all the possible pairs of heavy metal. The results suggest a likely common source for the heavy metal contamination, which could be traced most probably to vehicular emissions, street dust and other related activities. (author)

  3. The potential of genetic engineering of plants for the remediation of soils contaminated with heavy metals.

    Science.gov (United States)

    Fasani, Elisa; Manara, Anna; Martini, Flavio; Furini, Antonella; DalCorso, Giovanni

    2018-05-01

    The genetic engineering of plants to facilitate the reclamation of soils and waters contaminated with inorganic pollutants is a relatively new and evolving field, benefiting from the heterologous expression of genes that increase the capacity of plants to mobilize, stabilize and/or accumulate metals. The efficiency of phytoremediation relies on the mechanisms underlying metal accumulation and tolerance, such as metal uptake, translocation and detoxification. The transfer of genes involved in any of these processes into fast-growing, high-biomass crops may improve their reclamation potential. The successful phytoextraction of metals/metalloids and their accumulation in aerial organs have been achieved by expressing metal ligands or transporters, enzymes involved in sulfur metabolism, enzymes that alter the chemical form or redox state of metals/metalloids and even the components of primary metabolism. This review article considers the potential of genetic engineering as a strategy to improve the phytoremediation capacity of plants in the context of heavy metals and metalloids, using recent case studies to demonstrate the practical application of this approach in the field. © 2017 John Wiley & Sons Ltd.

  4. Conversion of tritiated hydrogen to tritiated water on heated metal surfaces

    International Nuclear Information System (INIS)

    Dickson, R.S.

    1993-05-01

    The conversion of tritium to tritiated water on metal surfaces was studied under conditions relevant to releases into a fusion reactor hall (metal temperatures between 473 K and 623 K, air or inert gas atmospheres). The rate constant of oxidation per unit geometric surface area was found to be about a factor of ten higher than the rate constant per unit gas adsorption surface area for H 2 to H 2 O conversion on metal oxides in excess oxygen, probably because of the roughness of the metal surfaces on a gas adsorption scale. Surface roughness and oxides were found to have a major influence on the reaction rate. The reaction exhibited a first-order dependence on Q 2 concentration. Changing the dew point of the atmosphere did not affect the rate significantly, and rate constants for most metals were independent of whether the atmosphere was argon or air. Coatings of hydrocarbon and silicone polymers did not significantly affect the reaction rate on carbon steel and ferrous metals and brass all had about the same conversion rate constant. Aluminum alloy gave about three times lower and copper in Ar gave ten times higher conversion rate constants. Based on these data, an accident scenario involving exposure of 1000 m 2 of stainless steel at 573 K to a 10 4 m 3 room would cause conversion of ca. 0.1% of the Q 2 present to Q 2 O in 24 hours, while air ingress to the torus without leakage of the tritium into the room would cause 1.2% conversion in that time. The rate values are only accurate within a multiplicative factor of three, so they should be applied cautiously in model calculations. (author). 27 refs., 4 tabs., 4 figs

  5. Implementation of Statistical Methods and SWOT Analysis for Evaluation of Metal Waste Management in Engineering Company

    Directory of Open Access Journals (Sweden)

    Záhorská Renáta

    2016-12-01

    Full Text Available This paper presents the results of the waste management research in a selected engineering company RIBE Slovakia, k. s., Nitra factory. Within of its manufacturing programme, the mentioned factory uses wide range of the manufacturing technologies (cutting operations, metal cold-forming, thread rolling, metal surface finishing, automatic sorting, metrology, assembly, with the aim to produce the final products – connecting components (fasteners delivered to many industrial fields (agricultural machinery manufacturers, car industry, etc.. There were obtained data characterizing production technologies and the range of manufactured products. The key attention is paid to the classification of waste produced by engineering production and to waste management within the company. Within the research, there were obtained data characterizing the time course of production of various waste types and these data were evaluated by means of statistical method using STATGRAPHICS. Based on the application of SWOT analysis, there is objectively assessed the waste management in the company in terms of strengths and weaknesses, as well as determination of the opportunities and potential threats. Results obtained by the SWOT analysis application have allowed to come to conclusion that the company RIBE Slovakia, k. s., Nitra factory has well organized waste management system. The fact that the waste management system is incorporated into the company management system can be considered as an advantage.

  6. Surface half-metallicity and stability of zinc-blende sodium monoselenide

    International Nuclear Information System (INIS)

    Tabatabaeifar, A.; Davatolhagh, S.; Moradi, M.

    2017-01-01

    Highlights: • Density functional study reveals. • Robust half-metallicity of zinc-blende NaSe (001) surfaces. • Stable against phase separation as indicated by negative formation energy. • Magnetically stable at room temperature because of high Curie temperature. • Surfaces are stable as indicated by low surface energies. • Therefore, zinc-blende NaSe promising candidate as spin injection material. - Abstract: The electronic structure and magnetic properties of relaxed (001) surfaces of the sp-electron half-metallic ferromagnet NaSe in the zinc-blende phase, are calculated on the basis of first principle density functional theory within the framework of self-consistent field plane wave pseudo-potential method, using the generalized gradient approximation for the exchange-correlation functional. The results of this study reveal that both Na- and Se-terminated surfaces retain the robust bulk half-metallic property. The negative value found for the bulk formation energy indicates that this material is stable against phase separation. We also obtain the surface energies and discuss their stability via the calculated bulk formation energy. The Curie temperature is estimated to be 920 K within mean field approximation, which is well above the room temperature. In the light of the above, zinc-blende NaSe appears to be a good candidate for spintronic applications as spin injection material.

  7. Spectral and physical properties of metal in meteorite assemblages - implications of asteroid surface materials

    International Nuclear Information System (INIS)

    Gaffey, M.J.

    1986-01-01

    One of the objectives of the present paper is related to a definition of the spectral contribution of the nickel-iron metal component in meteoritic assemblages. Another objective is the elucidation of the chemical, physical, and petrographic properties of the metal grains which affect the spectral signature in asteroid surface materials. It is pointed out that an improved understanding of the spectral and physical properties of metal in asteroid regoliths should permit an improved characterization of these objects, and, in particular, a better evaluation of the differentiated or undifferentiated nature of the S-type and M-type asteroids. Attention is given to the spectra of iron and nickel-iron metals, the spectral effects of metal in chondritic assemblages, the spectral reflectance of metal grains in ordinary chondrites, the nature of the surfaces of chondritic metal grains, the origin of coats on chondritic metal grains, and the fragmentation of metal on asteroid surfaces. 57 references

  8. Effect of metallic and hyperbolic metamaterial surface on electric and magnetic dipole emission

    DEFF Research Database (Denmark)

    Ni, Xingjie; Naik, Gururaj V.; Kildishev, Alexander V.

    2010-01-01

    Spontaneous emission patterns of electric and magnetic dipoles on different material surfaces were studied numerically and experimentally. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces.......Spontaneous emission patterns of electric and magnetic dipoles on different material surfaces were studied numerically and experimentally. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces....

  9. Surface plasmon microscopy with low-cost metallic nanostructures for biosensing I

    Science.gov (United States)

    Lindquist, Nathan; Oh, Sang-Hyun; Otto, Lauren

    2012-02-01

    The field of plasmonics aims to manipulate light over dimensions smaller than the optical wavelength by exploiting surface plasmon resonances in metallic films. Typically, surface plasmons are excited by illuminating metallic nanostructures. For meaningful research in this exciting area, the fabrication of high-quality nanostructures is critical, and in an undergraduate setting, low-cost methods are desirable. Careful optical characterization of the metallic nanostructures is also required. Here, we present the use of novel, inexpensive nanofabrication techniques and the development of a customized surface plasmon microscopy setup for interdisciplinary undergraduate experiments in biosensing, surface-enhanced Raman spectroscopy, and surface plasmon imaging. A Bethel undergraduate student performs the nanofabrication in collaboration with the University of Minnesota. The rewards of mentoring undergraduate students in cooperation with a large research university are numerous, exposing them to a wide variety of opportunities. This research also interacts with upper-level, open-ended laboratory projects, summer research, a semester-long senior research experience, and will enable a large range of experiments into the future.

  10. Metal-insulator-metal diodes with sub-nanometre surface roughness for energy-harvesting applications

    KAUST Repository

    Khan, A.A.; Jayaswal, Gaurav; Gahaffar, F.A.; Shamim, Atif

    2017-01-01

    For ambient radio-frequency (RF) energy harvesting, the available power levels are quite low, and it is highly desirable that the rectifying diodes do not consume any power at all. Contrary to semiconducting diodes, a tunnelling diode – also known as a metal-insulator-metal (MIM) diode – can provide zero-bias rectification, provided the two metals have different work functions. This could result in a complete passive rectenna system. Despite great potential, MIM diodes have not been investigated much in the GHz-frequency regime due to challenging nano-fabrication requirements. In this work, we investigate zero-bias MIM diodes for RF energy-harvesting applications. We studied the surface roughness issue for the bottom metal of the MIM diode for various deposition techniques such as sputtering, atomic layer deposition (ALD) and electron-beam (e-beam) evaporation for crystalline metals as well as for an amorphous alloy, namely ZrCuAlNi. A surface roughness of sub-1nm has been achieved for both the crystalline metals as well as the amorphous alloy, which is vital for the reliable operation of the MIM diode. An MIM diode comprising of a Ti-ZnO-Pt combination yields a zero-bias responsivity of 0.25V−1 and a dynamic resistance of 1200Ω. Complete RF characterisation has been performed by integrating the MIM diode with a coplanar waveguide transmission line. The input impedance varies from 100Ω to 50Ω in the frequency range of between 2GHz and 10GHz, which can be easily matched to typical antenna impedances in this frequency range. Finally, a rectified DC voltage of 4.7mV is obtained for an incoming RF power of 0.4W at zero bias. These preliminary results of zero-bias rectification indicate that complete, passive rectennas (a rectifier and antenna combination) are feasible with further optimisation of MIM devices.

  11. Metal-insulator-metal diodes with sub-nanometre surface roughness for energy-harvesting applications

    KAUST Repository

    Khan, A.A.

    2017-07-27

    For ambient radio-frequency (RF) energy harvesting, the available power levels are quite low, and it is highly desirable that the rectifying diodes do not consume any power at all. Contrary to semiconducting diodes, a tunnelling diode – also known as a metal-insulator-metal (MIM) diode – can provide zero-bias rectification, provided the two metals have different work functions. This could result in a complete passive rectenna system. Despite great potential, MIM diodes have not been investigated much in the GHz-frequency regime due to challenging nano-fabrication requirements. In this work, we investigate zero-bias MIM diodes for RF energy-harvesting applications. We studied the surface roughness issue for the bottom metal of the MIM diode for various deposition techniques such as sputtering, atomic layer deposition (ALD) and electron-beam (e-beam) evaporation for crystalline metals as well as for an amorphous alloy, namely ZrCuAlNi. A surface roughness of sub-1nm has been achieved for both the crystalline metals as well as the amorphous alloy, which is vital for the reliable operation of the MIM diode. An MIM diode comprising of a Ti-ZnO-Pt combination yields a zero-bias responsivity of 0.25V−1 and a dynamic resistance of 1200Ω. Complete RF characterisation has been performed by integrating the MIM diode with a coplanar waveguide transmission line. The input impedance varies from 100Ω to 50Ω in the frequency range of between 2GHz and 10GHz, which can be easily matched to typical antenna impedances in this frequency range. Finally, a rectified DC voltage of 4.7mV is obtained for an incoming RF power of 0.4W at zero bias. These preliminary results of zero-bias rectification indicate that complete, passive rectennas (a rectifier and antenna combination) are feasible with further optimisation of MIM devices.

  12. Nanotubular surface modification of metallic implants via electrochemical anodization technique.

    Science.gov (United States)

    Wang, Lu-Ning; Jin, Ming; Zheng, Yudong; Guan, Yueping; Lu, Xin; Luo, Jing-Li

    2014-01-01

    Due to increased awareness and interest in the biomedical implant field as a result of an aging population, research in the field of implantable devices has grown rapidly in the last few decades. Among the biomedical implants, metallic implant materials have been widely used to replace disordered bony tissues in orthopedic and orthodontic surgeries. The clinical success of implants is closely related to their early osseointegration (ie, the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant), which relies heavily on the surface condition of the implant. Electrochemical techniques for modifying biomedical implants are relatively simple, cost-effective, and appropriate for implants with complex shapes. Recently, metal oxide nanotubular arrays via electrochemical anodization have become an attractive technique to build up on metallic implants to enhance the biocompatibility and bioactivity. This article will thoroughly review the relevance of electrochemical anodization techniques for the modification of metallic implant surfaces in nanoscale, and cover the electrochemical anodization techniques used in the development of the types of nanotubular/nanoporous modification achievable via electrochemical approaches, which hold tremendous potential for bio-implant applications. In vitro and in vivo studies using metallic oxide nanotubes are also presented, revealing the potential of nanotubes in biomedical applications. Finally, an outlook of future growth of research in metallic oxide nanotubular arrays is provided. This article will therefore provide researchers with an in-depth understanding of electrochemical anodization modification and provide guidance regarding the design and tuning of new materials to achieve a desired performance and reliable biocompatibility.

  13. Nanostructure formation on refractory metal surfaces irradiated by helium plasmas

    International Nuclear Information System (INIS)

    Takamura, Shuichi; Kajita, Shin; Ohno, Noriyasu

    2013-01-01

    Helium defects on plasma-facing refractory metals like tungsten have been studied in fusion sciences from the view point of the effects on metal surface properties, concentrating on the bubble formation. However, the surface morphology over the lower surface temperature range was found recently to be changed drastically, something like cotton down or arborescence, sometimes called as “fuzz”. The formation process, although still open problem, would be discussed in terms of viscoelastic model with the effect of surface tension, taking account of its thermal properties and nano-bubbles inside the thin fibers. Some physical surface characteristics like electron emission, radiation emissivity and sputtering are quite influenced by its forest-like structure. Unipolar arcing has been newly studied by using such a surface structure which makes its initiation controllable. In the present report, other examples of nanostructure formation in a variety of particle incident conditions have been introduced as well as the possibility of its industrial applications to enhance interdisciplinary interests. (author)

  14. Metals on graphene and carbon nanotube surfaces: From mobile atoms to atomtronics to bulk metals to clusters and catalysts

    KAUST Repository

    Sarkar, Santanu C.

    2014-01-14

    In this Perspective, we present an overview of recent fundamental studies on the nature of the interaction between individual metal atoms and metal clusters and the conjugated surfaces of graphene and carbon nanotube with a particular focus on the electronic structure and chemical bonding at the metal-graphene interface. We discuss the relevance of organometallic complexes of graphitic materials to the development of a fundamental understanding of these interactions and their application in atomtronics as atomic interconnects, high mobility organometallic transistor devices, high-frequency electronic devices, organometallic catalysis (hydrogen fuel generation by photocatalytic water splitting, fuel cells, hydrogenation), spintronics, memory devices, and the next generation energy devices. We touch on chemical vapor deposition (CVD) graphene grown on metals, the reactivity of its surface, and its use as a template for asymmetric graphene functionalization chemistry (ultrathin Janus discs). We highlight some of the latest advances in understanding the nature of interactions between metals and graphene surfaces from the standpoint of metal overlayers deposited on graphene and SWNT thin films. Finally, we comment on the major challenges facing the field and the opportunities for technological applications. © 2013 American Chemical Society.

  15. Numerical simulation on the explosive boiling phenomena on the surface of molten metal

    International Nuclear Information System (INIS)

    Chen Deqi; Peng Cheng; Wang Qinghua; Pan Liangming

    2014-01-01

    In this paper, numerical simulation was carried out to investigate the explosive boiling phenomenon on high temperature surface also the influence of vapor growth rate during explosive boiling, vapor condensation in sub-cooled water and the subsequent effect on flowing and heat transfer. The simulation result indicates that the steam on the molten metal surface grows with very high speed, and it pushes away the sub-cooled water around and causes severe flowing. The steam clusters which block the sub-cooled water to rewet the molten metal surface are appearing at the same time. During the growth, lifting off as well as condensation of the steam clusters, the sub-cooled water around is strongly disturbed, and obvious vortexes appear. Conversely, the vortex will influence the steam cluster detachment and cub-cooled water rewetting the metal surface. This simulation visually displays the complex explosive boiling phenomena on the molten metal surface with high temperature. (authors)

  16. Synthesis and surface engineering of nanomaterials by atmospheric-pressure microplasmas

    Science.gov (United States)

    McKenna, J.; Patel, J.; Mitra, S.; Soin, N.; Švrček, V.; Maguire, P.; Mariotti, D.

    2011-11-01

    Two different atmospheric pressure microplasma systems are discussed and used for the synthesis and surface engineering of a range of nanomaterials. Specifically a gas-phase approach from vaporized tetramethylsilane has been used to synthesize silicon carbide nanoparticles with diameters below 10 nm. A different microplasma system that interfaces with a liquid solution has then been used for the synthesis of surfactant-free electrically stabilized gold nanoparticles with varying size. A similar microplasma-liquid system has been finally successfully used to tailor surface properties of silicon nanoparticles and to reduce graphene oxide into graphene. The synthesis and surface engineering mechanisms are also discussed.

  17. Internal and surface phenomena in metal combustion

    Science.gov (United States)

    Dreizin, Edward L.; Molodetsky, Irina E.; Law, Chung K.

    1995-01-01

    Combustion of metals has been widely studied in the past, primarily because of their high oxidation enthalpies. A general understanding of metal combustion has been developed based on the recognition of the existence of both vapor-phase and surface reactions and involvement of the reaction products in the ensuing heterogeneous combustion. However, distinct features often observed in metal particle combustion, such as brightness oscillations and jumps (spearpoints), disruptive burning, and non-symmetric flames are not currently understood. Recent metal combustion experiments using uniform high-temperature metal droplets produced by a novel micro-arc technique have indicated that oxygen dissolves in the interior of burning particles of certain metals and that the subsequent transformations of the metal-oxygen solutions into stoichiometric oxides are accompanied with sufficient heat release to cause observed brightness and temperature jumps. Similar oxygen dissolution has been observed in recent experiments on bulk iron combustion but has not been associated with such dramatic effects. This research addresses heterogeneous metal droplet combustion, specifically focusing on oxygen penetration into the burning metal droplets, and its influence on the metal combustion rate, temperature history, and disruptive burning. A unique feature of the experimental approach is the combination of the microgravity environment with a novel micro-arc Generator of Monodispersed Metal Droplets (GEMMED), ensuring repeatable formation and ignition of uniform metal droplets with controllable initial temperature and velocity. The droplet initial temperatures can be adjusted within a wide range from just above the metal melting point, which provides means to ignite droplets instantly upon entering an oxygen containing environment. Initial droplet velocity will be set equal to zero allowing one to organize metal combustion microgravity experiments in a fashion similar to usual microgravity

  18. Metal decontamination for waste minimization using liquid metal refining technology

    International Nuclear Information System (INIS)

    Joyce, E.L. Jr.; Lally, B.; Ozturk, B.; Fruehan, R.J.

    1993-01-01

    The current Department of Energy Mixed Waste Treatment Project flowsheet indicates that no conventional technology, other than surface decontamination, exists for metal processing. Current Department of Energy guidelines require retrievable storage of all metallic wastes containing transuranic elements above a certain concentration. This project is in support of the National Mixed Low Level Waste Treatment Program. Because of the high cost of disposal, it is important to develop an effective decontamination and volume reduction method for low-level contaminated metals. It is important to be able to decontaminate complex shapes where surfaces are hidden or inaccessible to surface decontamination processes and destruction of organic contamination. These goals can be achieved by adapting commercial metal refining processes to handle radioactive and organic contaminated metal. The radioactive components are concentrated in the slag, which is subsequently vitrified; hazardous organics are destroyed by the intense heat of the bath. The metal, after having been melted and purified, could be recycled for use within the DOE complex. In this project, we evaluated current state-of-the-art technologies for metal refining, with special reference to the removal of radioactive contaminants and the destruction of hazardous organics. This evaluation was based on literature reports, industrial experience, plant visits, thermodynamic calculations, and engineering aspects of the various processes. The key issues addressed included radioactive partitioning between the metal and slag phases, minimization of secondary wastes, operability of the process subject to widely varying feed chemistry, and the ability to seal the candidate process to prevent the release of hazardous species

  19. Transfer of metallic debris from the metal surface of an acetabular cup to artificial femoral heads by scraping: comparison between alumina and cobalt-chrome heads.

    Science.gov (United States)

    Chang, Chong Bum; Yoo, Jeong Joon; Song, Won Seok; Kim, Deug Joong; Koo, Kyung-Hoi; Kim, Hee Joong

    2008-04-01

    We aimed to investigate the transfer of metal to both ceramic (alumina) and metal (cobalt-chrome) heads that were scraped by a titanium alloy surface under different load conditions. The ceramic and metal heads for total hip arthroplasties were scraped by an acetabular metal shell under various loads using a creep tester. Microstructural changes in the scraped area were visualized with a scanning electron microscope, and chemical element changes were assessed using an energy dispersive X-ray spectrometry. Changes in the roughness of the scraped surface were evaluated by a three-dimensional surface profiling system. Metal transfer to the ceramic and metal heads began to be detectable at a 10 kg load, which could be exerted by one-handed force. The surface roughness values significantly increased with increasing test loads in both heads. When the contact force increased, scratching of the head surface occurred in addition to the transfer of metal. The results documented that metallic debris was transferred from the titanium alloy acetabular shell to both ceramic and metal heads by minor scraping. This study suggests that the greatest possible effort should be made to protect femoral heads, regardless of material, from contact with metallic surfaces during total hip arthroplasty.

  20. Biopolymer nanostructures induced by plasma irradiation and metal sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Slepička, P., E-mail: petr.slepicka@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Juřík, P. [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Malinský, P.; Macková, A. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez, Prague 25068 (Czech Republic); Faculty of Science, J.E. Purkyně University, Ústí nad Labem (Czech Republic); Kasálková, N. Slepičková; Švorčík, V. [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic)

    2014-08-01

    Modification based on polymer surface exposure to plasma treatment exhibits an easy and cheap technique for polymer surface nanostructuring. The influence of argon plasma treatment on biopolymer poly(L-lactide acid (PLLA) will be presented in this paper. The combination of Ar{sup +} ion irradiation, consequent sputter metallization (platinum) and thermal annealing of polymer surface will be summarized. The surface morphology was studied using atomic force microscopy. The Rutherford Backscattering Spectroscopy and X-ray Photoelectron Spectroscopy were used as analytical methods. The combination of plasma treatment with consequent thermal annealing and/or metal sputtering led to the change of surface morphology and its elemental ratio. The surface roughness and composition has been strongly influenced by the modification parameters and metal layer thickness. By plasma treatment of polymer surface combined with consequent annealing or metal deposition can be prepared materials applicable both in tissue engineering as cell carriers, but also in integrated circuit manufacturing.

  1. Demonstrating electromagnetic control of free-surface, liquid-metal flows relevant to fusion reactors

    Science.gov (United States)

    Hvasta, M. G.; Kolemen, E.; Fisher, A. E.; Ji, H.

    2018-01-01

    Plasma-facing components (PFC’s) made from solid materials may not be able to withstand the large heat and particle fluxes that will be produced within next-generation fusion reactors. To address the shortcomings of solid PFC’s, a variety of liquid-metal (LM) PFC concepts have been proposed. Many of the suggested LM-PFC designs rely on electromagnetic restraint (Lorentz force) to keep free-surface, liquid-metal flows adhered to the interior surfaces of a fusion reactor. However, there is very little, if any, experimental data demonstrating that free-surface, LM-PFC’s can actually be electromagnetically controlled. Therefore, in this study, electrical currents were injected into a free-surface liquid-metal that was flowing through a uniform magnetic field. The resultant Lorentz force generated within the liquid-metal affected the velocity and depth of the flow in a controllable manner that closely matched theoretical predictions. These results show the promise of electromagnetic control for LM-PFC’s and suggest that electromagnetic control could be further developed to adjust liquid-metal nozzle output, prevent splashing within a tokamak, and alter heat transfer properties for a wide-range of liquid-metal systems.

  2. Studies on metal-dielectric plasmonic structures.

    Energy Technology Data Exchange (ETDEWEB)

    Chettiar, Uday K. (Purdue University, West Lafayette, IN); Liu, Zhengtong (Purdue University, West Lafayette, IN); Thoreson, Mark D. (Purdue University, West Lafayette, IN); Shalaev, Vladimir M. (Purdue University, West Lafayette, IN); Drachev, Vladimir P. (Purdue University, West Lafayette, IN); Pack, Michael Vern; Kildishev, Alexander V. (Purdue University, West Lafayette, IN); Nyga, Piotr (Purdue University, West Lafayette, IN)

    2010-01-01

    The interaction of light with nanostructured metal leads to a number of fascinating phenomena, including plasmon oscillations that can be harnessed for a variety of cutting-edge applications. Plasmon oscillation modes are the collective oscillation of free electrons in metals under incident light. Previously, surface plasmon modes have been used for communication, sensing, nonlinear optics and novel physics studies. In this report, we describe the scientific research completed on metal-dielectric plasmonic films accomplished during a multi-year Purdue Excellence in Science and Engineering Graduate Fellowship sponsored by Sandia National Laboratories. A variety of plasmonic structures, from random 2D metal-dielectric films to 3D composite metal-dielectric films, have been studied in this research for applications such as surface-enhanced Raman sensing, tunable superlenses with resolutions beyond the diffraction limit, enhanced molecular absorption, infrared obscurants, and other real-world applications.

  3. Assessment of engineered surfaces roughness by high-resolution 3D SEM photogrammetry

    Energy Technology Data Exchange (ETDEWEB)

    Gontard, L.C., E-mail: lionelcg@gmail.com [Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Universidad de Cádiz, Puerto Real 11510 (Spain); López-Castro, J.D.; González-Rovira, L. [Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Escuela Superior de Ingeniería, Laboratorio de Corrosión, Universidad de Cádiz, Puerto Real 11519 (Spain); Vázquez-Martínez, J.M. [Departamento de Ingeniería Mecánica y Diseño Industrial, Escuela Superior de Ingeniería, Universidad de Cádiz, Puerto Real 11519 (Spain); Varela-Feria, F.M. [Servicio de Microscopía Centro de Investigación, Tecnología e Innovación (CITIUS), Universidad de Sevilla, Av. Reina Mercedes 4b, 41012 Sevilla (Spain); Marcos, M. [Departamento de Ingeniería Mecánica y Diseño Industrial, Escuela Superior de Ingeniería, Universidad de Cádiz, Puerto Real 11519 (Spain); and others

    2017-06-15

    Highlights: • We describe a method to acquire a high-angle tilt series of SEM images that is symmetrical respect to the zero tilt of the sample stage. The method can be applied in any SEM microscope. • Using the method, high-resolution 3D SEM photogrammetry can be applied on planar surfaces. • 3D models of three surfaces patterned with grooves are reconstructed with high resolution using multi-view freeware photogrammetry software as described in LC Gontard et al. Ultramicroscopy, 2016. • From the 3D models roughness parameters are measured • 3D SEM high-resolution photogrammetry is compared with two conventional methods used for roughness characetrization: stereophotogrammetry and contact profilometry. • It provides three-dimensional information with high-resolution that is out of reach for any other metrological technique. - Abstract: We describe a methodology to obtain three-dimensional models of engineered surfaces using scanning electron microscopy and multi-view photogrammetry (3DSEM). For the reconstruction of the 3D models of the surfaces we used freeware available in the cloud. The method was applied to study the surface roughness of metallic samples patterned with parallel grooves by means of laser. The results are compared with measurements obtained using stylus profilometry (PR) and SEM stereo-photogrammetry (SP). The application of 3DSEM is more time demanding than PR or SP, but it provides a more accurate representation of the surfaces. The results obtained with the three techniques are compared by investigating the influence of sampling step on roughness parameters.

  4. Pb, Cu, and Zn distributions at humic acid-coated metal-oxide surfaces

    Science.gov (United States)

    Wang, Yingge; Michel, F. Marc; Choi, Yongseong; Eng, Peter J.; Levard, Clement; Siebner, Hagar; Gu, Baohua; Bargar, John R.; Brown, Gordon E.

    2016-09-01

    Mineral surfaces are often coated by natural organic matter (NOM), which has a major influence on metal-ion sorption and sequestration because of the abundance of binding sites in such coatings and the changes they cause in local nanoscale environments. The effects of NOM coatings on mineral surfaces are, however, still poorly understood at the molecular level due to the complexity of these systems. In this study, we have applied long-period X-ray standing wave-fluorescence yield (LP-XSW-FY) spectroscopy to measure the partitioning of naturally present Cu(II) (0.0226%), Zn(II) (0.009%), and Pb(II) (∼0.0004%) between Elliott Soil Humic Acid (ESHA) coatings and three model single-crystal metal-oxide substrates: α-Al2O3 (0 0 0 1), α-Al2O3 (1 -1 0 2), and α-Fe2O3 (0 0 0 1). The competitive sorption effects among these metal ions for binding sites in the ESHA coatings and on the metal-oxide surfaces were investigated as a function of reaction time, calcium content, and solution pH. Pb(II) ions present in the ESHA coatings were found to redistribute to reactive α-Al2O3 (1 -1 0 2) and α-Fe2O3 (0 0 0 1) surfaces after 3 h of reaction (pH = 6.0, [Ca(II)] = 2 mM). Pb(II) partitioning onto these reactive metal-oxide surfaces increased with increasing reaction time (up to 7 d). In addition, the partitioning of Cu(II) and Zn(II) from the ESHA coating to the α-Fe2O3 (0 0 0 1) substrate increased slightly with reaction time (2.4% and 3.7% for Cu(II) and Zn(II), respectively, after 3 h and 6.4% and 7.7% for Cu(II) and Zn(II), respectively, after 72 h of reaction time). However, no changes in the partitioning of Cu(II) and Zn(II) onto the α-Al2O3 (1 -1 0 2) surface were observed with increasing reaction time, suggesting that these ions strongly complex with functional groups in the ESHA coatings. Similar results were obtained for Cu(II) and Zn(II) on the ESHA-coated α-Al2O3 (1 -1 0 2) surfaces in samples without the addition of calcium. However, the amounts of Pb

  5. Engineering of bone fixation metal implants biointerface-Application of parylene C as versatile protective coating

    Energy Technology Data Exchange (ETDEWEB)

    Cieslik, Monika, E-mail: cieslik@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Institute of Metallurgy and Materials Science, PAS, W. Reymonta 25, 30-059 Krakow (Poland); Zimowski, Slawomir [AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Golda, Monika [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Institute of Metallurgy and Materials Science, PAS, W. Reymonta 25, 30-059 Krakow (Poland); Engvall, Klas [KTH Royal Institute of Technology, Department of Chemical Engineering and Technology, Division of Chemical Technology, Drottning Kristinas vaeg. 42, SE-100 44 Stockholm (Sweden); Pan, Jinshan [KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas vaeg. 51, SE-100 44 Stockholm (Sweden); Rakowski, Wieslaw [AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Kotarba, Andrzej, E-mail: kotarba@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

    2012-12-01

    The tribological and protective properties of parylene C coatings (2-20 {mu}m) on stainless steel 316L implant materials were investigated by means of electrochemical measurements and wear tests. The thickness and morphology of the CVD prepared coatings were characterized by scanning electron and laser confocal microscopy. The stability of the coatings was examined in contact with Hanks' solution and H{sub 2}O{sub 2} (simulating the inflammatory response). It was concluded that silane-parylene C coating with the optimum thickness of 8 {mu}m exhibits excellent wear resistance properties and limits the wear formation. The engineered versatile coating demonstrates sufficient elastomer properties, essential to sustain the implantation surgery strains and micromotions during long-term usage in the body. - Highlights: Black-Right-Pointing-Pointer A versatile coating for protection of metal implant surface is proposed. Black-Right-Pointing-Pointer The protective properties of 2-20 {mu}m silane-parylene C coating were examined. Black-Right-Pointing-Pointer The engineered material proves its high anticorrosive and wear resistance. Black-Right-Pointing-Pointer The practical implications of the coating properties were discussed.

  6. Origin of metallic surface core-level shifts

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Abrikosov, I. A.

    1995-01-01

    The unique property of the open 4f energy shell in the lanthanide metals is used to show that the initial-state energy shift gives an insufficient description of surface core-level shifts. Instead a treatment, which fully includes the final-state screening, account for the experimentally observed...

  7. Surface cleaning of metal wire by atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Nakamura, T.; Buttapeng, C.; Furuya, S.; Harada, N.

    2009-01-01

    In this study, the possible application of atmospheric pressure dielectric barrier discharge plasma for the annealing of metallic wire is examined and presented. The main purpose of the current study is to examine the surface cleaning effect for a cylindrical object by atmospheric pressure plasma. The experimental setup consists of a gas tank, plasma reactor, and power supply with control panel. The gas assists in the generation of plasma. Copper wire was used as an experimental cylindrical object. This copper wire was irradiated with the plasma, and the cleaning effect was confirmed. The result showed that it is possible to remove the tarnish which exists on the copper wire surface. The experiment reveals that atmospheric pressure plasma is usable for the surface cleaning of metal wire. However, it is necessary to examine the method for preventing oxidization of the copper wire.

  8. The passivation of uranium metal surfaces by nitrogen bombardment - the formation of uranium nitride

    International Nuclear Information System (INIS)

    Allen, G.C.; Holmes, N.R.

    1987-08-01

    As part of a detailed investigation of the behaviour of metallic uranium in various atmospheres, we have examined the reaction between nitrogen gas and uranium metal. At room temperature there was no evidence of reaction between nitrogen gas and a clean metal surface; the only changes observed could be attributed to reaction between the metal and traces of oxygen (less than 0.1 ppm) in the nitrogen gas. Reaction between the metal and nitrogen was induced however by accelerating nitrogen towards the surface using a fast atom gun. The resulting nitrided surface was characterised by X-ray photoelectron spectroscopy, and its oxidation behaviour was monitored over an extended period in UHV and in air. (author)

  9. The passivation of uranium metal surfaces by nitrogen bombardment - the formation of uranium nitride

    International Nuclear Information System (INIS)

    Allen, G.C.; Holmes, N.R.

    1988-01-01

    As part of a detailed investigation of the behaviour of metallic uranium in various atmospheres, we have examined the reaction between nitrogen gas and uranium metal. At room temperature there was no evidence of reaction between nitrogen gas and a clean metal surface; the only changes observed could be attributed to reaction between the metal and traces of oxygen (less than 0.1 ppm) in the nitrogen gas. Reaction between the metal and nitrogen was induced, however, by accelerating nitrogen towards the surface using a fast atom gun. The resulting nitrided surface was characterized by X-ray photoelectron spectroscopy, and its oxidation behaviour was monitored over an extended period in UHV and in air. (orig.)

  10. Influence of carbon monoxide to the surface layer of uranium metal and its oxides

    International Nuclear Information System (INIS)

    Wang Xiaoling; Fu Yibei; Xie Renshou; Huang Ruiliang

    1996-09-01

    The surface structures of uranium metal and triuranium octaoxide (U 3 O 8 ) and the influence of carbon monoxide to the surface layers have been studied by X-ray photoelectron spectroscopy (XPS). After exposure to carbon monoxide, contents of oxygen in the surface oxides of uranium metal and U 3 O 8 are decreased and O/U ratios decrease 7.2%, 8.0% respectively. The investigation indicated the surface layers of uranium metal and its oxides were forbidden to further oxidation in the atmosphere of carbon monoxide. (11 refs., 9 figs., 2 tabs.)

  11. Voltammetric determination of metal impurities on semiconductor surface

    International Nuclear Information System (INIS)

    Knyazeva, E.P.; Mokrousov, G.M.; Volkova, V.N.

    1995-01-01

    A modification of voltamperometric method used for analysis of semiconductor surfaces which make it possible to exclude a contact between surface and background solution. This technique is based on solubility of elemental metal forms in low melting electroconductor systems (e.g., in mercury. The voltampere characteristics of amalgams formed are then studied. The suggested method is simple, rapid, and makes it possible to perform a nondestructive qualitative analysis of the sample surface area measuring about 10 -3 cm -2 and more. 4 refs.; 2 figs

  12. Tritiated hydrogen conversion on heated metallic surfaces

    International Nuclear Information System (INIS)

    Ionita, G.; Mihaila, V.; Purghel, L.; Rebigan, F.

    1995-01-01

    This work reports investigations on tritiated hydrogen conversion to tritiated water on heated metallic surfaces. The HT conversion process has been revealed for copper, aluminium and stainless steel W4541 surfaces in the temperature range 150 to 300 o C, in case of the static regime and in the range 250 to 400 o C for the dynamic case. The most significant catalytic activity was shown by the copper sample. Studies on this subject are used as input information for different nuclear accident scenarios implying tritium leakage

  13. Adsorption of metals and protons on Gloeocapsa sp. cyanobacteria: A surface speciation approach

    Energy Technology Data Exchange (ETDEWEB)

    Pokrovsky, O.S. [Geochimie et Biogeochimie Experimentale, LMTG, Universite de Toulouse, CNRS-IRD-OMP, 14 Avenue Edouard Belin, 31400 Toulouse (France)], E-mail: oleg@lmtg.obs-mip.fr; Martinez, R.E.; Golubev, S.V. [Geochimie et Biogeochimie Experimentale, LMTG, Universite de Toulouse, CNRS-IRD-OMP, 14 Avenue Edouard Belin, 31400 Toulouse (France); Kompantseva, E.I. [Winogradsky Institute of Microbiology, Russian Academy of Science, Moscow (Russian Federation); Shirokova, L.S. [Institute of Ecological Problems of the Northern Regions, Russian Academy of Science, 29 Naberezhnaja Sev. Dviny, Arkhangelsk (Russian Federation)

    2008-09-15

    The purpose of the present work is to extend our knowledge of metal-cyanobacteria interactions and to contribute to the database on adsorption parameters of aquatic microorganisms with respect to metal pollutants. To this end, the surface properties of the cyanobacteria (Gloeocapsa sp. f-6gl) were studied using potentiometric acid-base titration methods and ATR-FTIR (attenuated total reflection infrared) spectroscopy. The electrophoretic mobility of viable cells was measured as a function of pH and ionic strength (0.01 and 0.1 M). Surface titrations at 0.01-1.0 M NaCl were performed using limited residence time reactors (discontinuous titration) with analysis of Ca, Mg and dissolved organic C for each titration point in order to account for alkali-earth metal-proton exchange and cell degradation, respectively. Results demonstrate that the cell-wall bound Ca and Mg from the culture media contribute to the total proton uptake via surface ion-exchange reactions. This has been explicitly taken into account for net proton balance calculations. Adsorption of Zn, Cd, Pb and Cu was studied at 25 deg. C in 0.01 M NaNO{sub 3} as a function of pH and metal concentration. The proportion of adsorbed metal increases as a function of culture age with cells of 44 days old having the largest adsorption capacities. A competitive Langmuir sorption isotherm in conjunction with a linear programming method (LPM) was used to fit experimental data and assess the number of surface sites and adsorption reaction constants involved in the binding of metals to the cyanobacteria surface. These observations allowed the determination of the identity and concentration of the major surface functional groups (carboxylate, amine, phosphoryl/phosphodiester and hydroxyl) responsible for the amphoteric behavior of cyanobacterial cell surfaces in aqueous solutions and for metal adsorption. Results of this work should allow better optimizing of metal bioremediation/biosequestration processes as they help

  14. Adsorption of metals and protons on Gloeocapsa sp. cyanobacteria: A surface speciation approach

    International Nuclear Information System (INIS)

    Pokrovsky, O.S.; Martinez, R.E.; Golubev, S.V.; Kompantseva, E.I.; Shirokova, L.S.

    2008-01-01

    The purpose of the present work is to extend our knowledge of metal-cyanobacteria interactions and to contribute to the database on adsorption parameters of aquatic microorganisms with respect to metal pollutants. To this end, the surface properties of the cyanobacteria (Gloeocapsa sp. f-6gl) were studied using potentiometric acid-base titration methods and ATR-FTIR (attenuated total reflection infrared) spectroscopy. The electrophoretic mobility of viable cells was measured as a function of pH and ionic strength (0.01 and 0.1 M). Surface titrations at 0.01-1.0 M NaCl were performed using limited residence time reactors (discontinuous titration) with analysis of Ca, Mg and dissolved organic C for each titration point in order to account for alkali-earth metal-proton exchange and cell degradation, respectively. Results demonstrate that the cell-wall bound Ca and Mg from the culture media contribute to the total proton uptake via surface ion-exchange reactions. This has been explicitly taken into account for net proton balance calculations. Adsorption of Zn, Cd, Pb and Cu was studied at 25 deg. C in 0.01 M NaNO 3 as a function of pH and metal concentration. The proportion of adsorbed metal increases as a function of culture age with cells of 44 days old having the largest adsorption capacities. A competitive Langmuir sorption isotherm in conjunction with a linear programming method (LPM) was used to fit experimental data and assess the number of surface sites and adsorption reaction constants involved in the binding of metals to the cyanobacteria surface. These observations allowed the determination of the identity and concentration of the major surface functional groups (carboxylate, amine, phosphoryl/phosphodiester and hydroxyl) responsible for the amphoteric behavior of cyanobacterial cell surfaces in aqueous solutions and for metal adsorption. Results of this work should allow better optimizing of metal bioremediation/biosequestration processes as they help to

  15. Metal-on-metal hip joint tribology.

    Science.gov (United States)

    Dowson, D; Jin, Z M

    2006-02-01

    The basic tribological features of metal-on-metal total hip replacements have been reviewed to facilitate an understanding of the engineering science underpinning the renaissance of these hard-on-hard joints. Metal-on-polymer hip replacements operate in the boundary lubrication regime, thus leading to the design guidance to reduce the femoral head diameter as much as is feasible to minimize frictional torque and volumetric wear. This explains why the gold-standard implant of this form from the past half-century had a diameter of only 22.225 mm (7/8 in). Metal-on-metal implants can operate in the mild mixed lubrication regime in which much of the applied load is supported by elastohydrodynamic films. Correct tribological design leads to remarkably low steady state wear rates. Promotion of the most effective elastohydrodynamic films calls for the largest possible head diameters and the smallest clearances that can reasonably be adopted, consistent with fine surface finishes, good sphericity and minimal structural elastic deformation of the cup on its foundations. This guidance, which is opposite in form to that developed for metal-on-polymer joints, is equally valid for solid (monolithic) metallic heads on metallic femoral stems and surface replacement femoral shells. Laboratory measurements of friction and wear in metal-on-metal joints have confirmed their potential to achieve a very mild form of mixed lubrication. The key lies in the generation of effective elastohydrodynamic lubricating films of adequate thickness compared with the composite roughness of the head and cup. The calculation of the film thickness is by no means easy, but the full procedure is outlined and the use of an empirical formula that displays good agreement with calculations based upon the full numerical solutions is explained. The representation of the lambda ratio, lambda, embracing both film thickness and composite roughness, is described.

  16. A modular approach to creating large engineered cartilage surfaces.

    Science.gov (United States)

    Ford, Audrey C; Chui, Wan Fung; Zeng, Anne Y; Nandy, Aditya; Liebenberg, Ellen; Carraro, Carlo; Kazakia, Galateia; Alliston, Tamara; O'Connell, Grace D

    2018-01-23

    Native articular cartilage has limited capacity to repair itself from focal defects or osteoarthritis. Tissue engineering has provided a promising biological treatment strategy that is currently being evaluated in clinical trials. However, current approaches in translating these techniques to developing large engineered tissues remains a significant challenge. In this study, we present a method for developing large-scale engineered cartilage surfaces through modular fabrication. Modular Engineered Tissue Surfaces (METS) uses the well-known, but largely under-utilized self-adhesion properties of de novo tissue to create large scaffolds with nutrient channels. Compressive mechanical properties were evaluated throughout METS specimens, and the tensile mechanical strength of the bonds between attached constructs was evaluated over time. Raman spectroscopy, biochemical assays, and histology were performed to investigate matrix distribution. Results showed that by Day 14, stable connections had formed between the constructs in the METS samples. By Day 21, bonds were robust enough to form a rigid sheet and continued to increase in size and strength over time. Compressive mechanical properties and glycosaminoglycan (GAG) content of METS and individual constructs increased significantly over time. The METS technique builds on established tissue engineering accomplishments of developing constructs with GAG composition and compressive properties approaching native cartilage. This study demonstrated that modular fabrication is a viable technique for creating large-scale engineered cartilage, which can be broadly applied to many tissue engineering applications and construct geometries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. RIKEN 200 kV high current implanter for metal surface modification

    International Nuclear Information System (INIS)

    Iwaki, M.; Yoshida, K.; Sakudo, N.

    1985-01-01

    A high current, metal ion implanter was constructed in order to aid the formation of a new metastable surface alloy. This implanter, called a RIKEN 200 kV high current implanter, is a modified Lintott high current machine (Series III), which has the advantages of having its own microwave ion source and an extra target chamber. The microwave discharge ion source without a hot-filament has a comparatively long lifetime because the chloride ions and radicals in a plasma during discharge of metal chlorides might prevent metal to deposit on the inner walls of the discharge chamber by bombarding and chemically cleaning them. An extra target chamber for metal modification is able to control the surface composition by utilizing the sputtering effect of the ion beam during ion implantation. The use of this ion source and the extra target chamber is suggested to be suitable for the production of metallic ions and for the implantation into metals. The case study will be introduced for TI implantation into Fe. (orig.)

  18. Guiding spoof surface plasmon polaritons by infinitely thin grooved metal strip

    Directory of Open Access Journals (Sweden)

    Xiang Wan

    2014-04-01

    Full Text Available In this paper, the propagation characteristics of spoof surface plasmon polaritons (SPPs on infinitely thin corrugated metal strips are theoretically analyzed. Compared with the situations of infinitely thick lateral thickness, the infinitely thin lateral thickness leads to lower plasma frequency according to the analyses. The propagation lengths and the binding capacity of the spoof SPPs are evaluated based on the derived dispersion equation. The effects of different lateral thicknesses are also investigated. At the end, a surface wave splitter is presented using infinitely thin corrugated metal strip. Other functional planar or flexible devices can also be designed using these metal strips in microwave or terahertz regimes.

  19. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    Science.gov (United States)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2015-07-01

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O2 = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  20. The interaction of H2O with strained uranium metal surfaces

    International Nuclear Information System (INIS)

    Tiferet, E.; Mintz, M. H.; Zalkind, S.; Jacob, I.; Shamir, N.

    2014-01-01

    The interaction of water vapor was studied on uranium metal surfaces, with various degrees of strain (relieved by different degrees of heating). The main features of dissociation, adsorption and initial oxidation for the studied surfaces will be presented. Common to all strained surfaces, on the metal surface a full dissociation occurs, while after oxidation only on most of them the water dissociation is full and on one of them, it is only partial. The oxygen dissociation product adsorbs (with sticking coefficient decreasing with strain relief), forming clusters, for all strains, while the hydrogen product clusters only on the strain relieved and recrystallized surface. The most interesting phenomenon, revealed for these surfaces, is the inhibition of hydrogen adsorption by traces of water vapor , changing from 10% for the mostly strained (defected) surface down to 1% for the strain relieved one. The suggested mechanism for this inhibition will be discussed

  1. Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

    Science.gov (United States)

    Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

    2015-08-01

    The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Integrating Surface Modeling into the Engineering Design Graphics Curriculum

    Science.gov (United States)

    Hartman, Nathan W.

    2006-01-01

    It has been suggested there is a knowledge base that surrounds the use of 3D modeling within the engineering design process and correspondingly within engineering design graphics education. While solid modeling receives a great deal of attention and discussion relative to curriculum efforts, and rightly so, surface modeling is an equally viable 3D…

  3. Influence of metallic based fuel additives on performance and exhaust emissions of diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    Keskin, Ali [Tarsus Technical Education Faculty, Mersin University, 33500 Mersin (Turkey); Guerue, Metin, E-mail: mguru@gazi.edu.t [Engineering and Architectural Faculty, Gazi University, 06570 Maltepe, Ankara (Turkey); Altiparmak, Duran [Technical Education Faculty, Gazi University, 06500 Ankara (Turkey)

    2011-01-15

    In this experimental study, influence of the metallic-based additives on fuel consumption and exhaust emissions of diesel engine were investigated. The metallic-based additives were produced by synthesizing of resin acid (abietic acid) with MnO{sub 2} or MgO. These additives were doped into diesel fuel at the rate of 8 {mu}mol/l and 16 {mu}mol/l for preparing test fuels. Both additives improved the properties of diesel fuel such as viscosity, flash point, cloud point and pour point. The fuels with and without additives were tested in a direct injection diesel engine at full load condition. Maximum reduction of specific fuel consumption was recorded as 4.16%. CO emission and smoke opacity decreased by 16.35% and by 29.82%, respectively. NO{sub x} emission was measured higher and CO{sub 2} emission was not changed considerably with the metallic-based additives.

  4. Surface-adaptable all-metal micro-four-point probe with unique configuration

    Science.gov (United States)

    Kim, J. K.; Choi, Y. S.; Lee, D. W.

    2015-07-01

    In this paper, we propose a surface-adaptable all-metal micro-four-point probe (μ4PP) with a unique configuration. The μ4PP consists of four independent metallic sub-cantilevers with sharp Cu tips, and an SU-8 body structure to support the sub-cantilevers. The tip height is approximately 15 μm, and the tips are fabricated by anisotropic wet-etching of silicon followed by Cu electroplating. Each metallic cantilever connected to the SU-8 body structure acts as a flexible spring, so that the conducting tip can make gentle, non-destructive contact with fragile surfaces. To enhance the adhesion between the metallic sub-cantilevers and the SU-8 body, mushroom-shaped Cu structures were fabricated using an under-baked and under-exposed photolithography process. Various μ4PPs were designed and fabricated to verify their diverse range of applications, and preliminary experiments were performed using these fabricated μ4PPs. The resultant flexibility and reliability were experimentally confirmed on several samples, such as a polymer cantilever, a graphene flake, and curved metallic surfaces. We also expect that the proposed μ4PP will be suitable for measuring the anisotropic characteristics of crystal materials or the Hall effect in semiconductors.

  5. Heavy metals uptake by sonicated activated sludge: Relation with floc surface properties

    International Nuclear Information System (INIS)

    Laurent, Julien; Casellas, Magali; Dagot, Christophe

    2009-01-01

    The effects of sonication of activated sludge on heavy metal uptake were in a first time investigated in respect with potential modifications of floc surface properties. The treatment led to the simultaneous increase of specific surface area and of the availability of negative and/or hydrophilic sites. In parallel, organic matter was released in the soluble fraction. Sorption isotherms of cadmium and copper showed that uptake characteristics and mechanisms were highly dependent on both heavy metal species and specific energy supplied. The increase of both specific surface area and fixation sites availability led to the increase of Cd(II) uptake. For Cu(II), organic matter released in soluble phase during the treatment seemed to act as a ligand and to limit adsorption on flocs surface. Three different heavy metals uptake mechanisms have been identified: proton exchange, ion exchange and (co)precipitation

  6. Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

    Energy Technology Data Exchange (ETDEWEB)

    Valizadeh, R., E-mail: reza.valizadeh@stfc.ac.uk [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Malyshev, O.B. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Wang, S. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sian, T. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); The Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom); Cropper, M.D. [Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sykes, N. [Micronanics Ltd., Didcot, Oxon OX11 0QX (United Kingdom)

    2017-05-15

    Highlights: • SEY below 1 can be achieved with Laser ablation surface engineering. • SEY <1 surface can be produced with different types of nanosecond lasers. • Both microstructure (groves) and nano-structures are playing a role in reducing SEY. - Abstract: Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators. In our previous publications, a low SEY < 0.9 for as-received metal surfaces modified by a nanosecond pulsed laser was reported. In this paper, the SEY of laser-treated blackened copper has been investigated as a function of different laser irradiation parameters. We explore and study the influence of micro- and nano-structures induced by laser surface treatment in air of copper samples as a function of various laser irradiation parameters such as peak power, laser wavelength (λ = 355 nm and 1064 nm), number of pulses per point (scan speed and repetition rate) and fluence, on the SEY. The surface chemical composition was determined by x-ray photoelectron spectroscopy (XPS) which revealed that heating resulted in diffusion of oxygen into the bulk and induced the transformation of CuO to sub-stoichiometric oxide. The surface topography was examined with high resolution scanning electron microscopy (HRSEM) which showed that the laser-treated surfaces are dominated by microstructure grooves and nanostructure features.

  7. Teaching - methodical and research center of hydrogen power engineering and platinum group metals in the former Soviet Union countries

    International Nuclear Information System (INIS)

    Evdokimov, A.A; Sigov, A.S; Shinkarenko, V.V.

    2005-01-01

    Full text: Teaching - Methodical and Research Center (TMRC) 'Sokolinaja Gora' is founded in order to provide methodical-information and scientific support of institutes of higher education in the field of hydrogen power engineering and platinum group metals in Russia and in the countries of the Former Soviet union. It is independent association of creative communities of scientist of higher educational specialists. The main directions of the Center activity are: 1. Teaching-methodological support and development of teaching in the field of hydrogen power engineering and platinum group metals in Russia in the countries of the Former Soviet Union. Themes of teaching includes the basic of safe using of hydrogen technologies and devices, ecological, economic and law aspects of new hydrogen power engineering, transition to which in 21 century is one of the central problems of mankind survival; 2. Organizing of joint researches by independent creative communities of scientists in the field of hydrogen power engineering and platinum group metal; 3. Independent scientific examination, which is made by Advisory Committee of High Technologies consisting of representatives of the countries of Former Soviet Union, which are standing participants of an Annual International Symposia 'Hydrogen Power Engineering and Platinum Group Metals in the Former Soviet Union Countries'. Structure of the Center: 1. Center of strategic development in the field of high technologies; 2. Scientific Research Institute of Hydrogen Power Engineering and Platinum Group Metals; 3. Teaching-Methodical Association in specialization 'Hydrogen Power Engineering and economics' and hydrogen wide spread training; 4. Media Center 'Hydrogen Power Engineering and Platinum Group Metals', 5. Organizational Center; 6. Administrative Center. The Center will be established step-by-step in 2005-2010 on the basis of the following programs: Teaching-methodological program. On the basis of this program it is planned to

  8. Influence of refraction of p-polarized light on photoemission from metallic surface states

    International Nuclear Information System (INIS)

    Bagchi, A.; Barrera, R.G.

    1979-01-01

    The refraction of p-polarized light at a metal surface leads, under certain circumstances, to a large peak in the spatial distribution of the normal component of the electric field near the surface. The origin of this peak is explained both in terms of a classical correspondence and in terms of a theory based on the non-local dielectric response of the metal surface. The significance of the large magnitude and rapid variation of the surface electric field in exciting photoelectrons from surface states is discussed [pt

  9. Laser decontamination and cleaning of metal surfaces: modelling and experimental studies

    International Nuclear Information System (INIS)

    Leontyev, A.

    2011-01-01

    Metal surface cleaning is highly required in different fields of modern industry. Nuclear industry seeks for new methods for oxidized surface decontamination, and thermonuclear installations require the cleaning of plasma facing components from tritium-containing deposited layer. The laser ablation is proposed as an effective and safe method for metal surface cleaning and decontamination. The important factor influencing the laser heating and ablation is the in-depth distribution of laser radiation. The model of light propagation in a scattering layer on a metal substrate is developed and applied to analyse the features of light distribution. To simulate the contaminated surfaces, the stainless steel AISI 304L was oxidized by laser and in a furnace. Radioactive contamination of the oxide layer was simulated by introducing europium and/or sodium. The decontamination factor of more than 300 was demonstrated with found optimal cleaning regime. The decreasing of the corrosion resistance was found after laser cleaning. The ablation thresholds of ITER-like surfaces were measured. The cleaning productivity of 0.07 m 2 /hour.W was found. For mirror surfaces, the damage thresholds were determined to avoid damage during laser cleaning. The possibility to restore reflectivity after thin carbon layer deposition was demonstrated. The perspectives of further development of laser cleaning are discussed. (author) [fr

  10. A Liquid Metal Flume for Free Surface Magnetohydrodynamic Experiments

    International Nuclear Information System (INIS)

    Nornberg, M.D.; Ji, H.; Peterson, J.L.; Rhoads, J.R.

    2008-01-01

    We present an experiment designed to study magnetohydrodynamic effects in free-surface channel flow. The wide aspect ratio channel (the width to height ratio is about 15) is completely enclosed in an inert atmosphere to prevent oxidization of the liquid metal. A custom-designed pump reduces entrainment of oxygen, which was found to be a problem with standard centrifugal and gear pumps. Laser Doppler Velocimetry experiments characterize velocity profiles of the flow. Various flow constraints mitigate secondary circulation and end effects on the flow. Measurements of the wave propagation characteristics in the liquid metal demonstrate the surfactant effect of surface oxides and the damping of fluctuations by a cross-channel magnetic field

  11. NON-POLLUTING METAL SURFACE FINISHING PRETREATMENT AND PRETREATMENT/CONVERSION COATING

    Science.gov (United States)

    Picklex, a proprietary formulation, is an alterantive to conventional metal surface pretreatments and is claimed not to produce waste or lower production or lower performance. A laboratory program was designed to evaluate Picklex in common, large scale, polluting surface finishin...

  12. Friction stir processed Al - Metal oxide surface composites: Anodization and optical appearance

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Jensen, Flemming; Canulescu, Stela

    2014-01-01

    Multiple-pass friction stir processing (FSP) was employed to impregnate metal oxide (TiO2, Y2O3 and CeO2) particles into the surface of an Aluminium alloy. The surface composites were then anodized in a sulphuric acid electrolyte. The effect of anodizing parameters on the resulting optical...... dark to greyish white. This is attributed to the localized microstructural and morphological differences around the metal oxide particles incorporated into the anodic alumina matrix. The metal oxide particles in the FSP zone electrochemically shadowed the underlying Al matrix and modified the local...

  13. Simulated BRDF based on measured surface topography of metal

    Science.gov (United States)

    Yang, Haiyue; Haist, Tobias; Gronle, Marc; Osten, Wolfgang

    2017-06-01

    The radiative reflective properties of a calibration standard rough surface were simulated by ray tracing and the Finite-difference time-domain (FDTD) method. The simulation results have been used to compute the reflectance distribution functions (BRDF) of metal surfaces and have been compared with experimental measurements. The experimental and simulated results are in good agreement.

  14. Remote Control of Tissue Interactions via Engineered Photo-switchable Cell Surfaces

    Science.gov (United States)

    Luo, Wei; Pulsipher, Abigail; Dutta, Debjit; Lamb, Brian M.; Yousaf, Muhammad N.

    2014-09-01

    We report a general cell surface molecular engineering strategy via liposome fusion delivery to create a dual photo-active and bio-orthogonal cell surface for remote controlled spatial and temporal manipulation of microtissue assembly and disassembly. Cell surface tailoring of chemoselective functional groups was achieved by a liposome fusion delivery method and quantified by flow cytometry and characterized by a new cell surface lipid pull down mass spectrometry strategy. Dynamic co-culture spheroid tissue assembly in solution and co-culture tissue multilayer assembly on materials was demonstrated by an intercellular photo-oxime ligation that could be remotely cleaved and disassembled on demand. Spatial and temporal control of microtissue structures containing multiple cell types was demonstrated by the generation of patterned multilayers for controlling stem cell differentiation. Remote control of cell interactions via cell surface engineering that allows for real-time manipulation of tissue dynamics may provide tools with the scope to answer fundamental questions of cell communication and initiate new biotechnologies ranging from imaging probes to drug delivery vehicles to regenerative medicine, inexpensive bioreactor technology and tissue engineering therapies.

  15. Near-Surface Engineered Environmental Barrier Integrity

    International Nuclear Information System (INIS)

    Piet, S.J.; Breckenridge, R.P.

    2002-01-01

    The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R and D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combine s selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo-transpiration, capillary, and grout-based barriers will be examined

  16. Evaluation of Encapsulant Adhesion to Surface Metallization of Photovoltaic Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Jared; Dauskardt, Reinhold; Bosco, Nick

    2017-06-14

    Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of EVA encapsulant to screen printed silver metallization was evaluated. At room temperature, the fracture energy, Gc [J/m2], of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/AR coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 hours of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2, while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and elevated temperature, and may explain the propensity for delamination to occur at metallized surfaces in the field.

  17. Proceedings of the symposium on chemistry and physics of surface of metals and their oxides

    Energy Technology Data Exchange (ETDEWEB)

    1976-01-01

    Topics covered include: structure of crystalline surfaces; thermodynamic, electrostatic, and physicochemical considerations on defect structure and metal to metal interfaces; physical properties of metal surfaces; stress corrosion cracking; corrosion; passivation; mass transfer across interfaces; electrodeposition; Auger electron spectroscopy; electron microscopy; and catalysis. (GHT)

  18. Isolation and dispersion of reduced metal particles using the surface dipole moment of F-terminated diamond electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, M.; Tanaka, Y.; Furuta, M. [Department of Chemistry and Earth Sciences, School of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan); Kondo, T. [Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Fujishima, A. [Kanagawa Advanced Science and Technology (KAST), 3-2-1, Sakato, Takastu-ku, Kawasaki-shi, Kanagawa 213-0012 (Japan); Honda, K. [Department of Chemistry and Earth Sciences, School of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan)], E-mail: khonda@yamaguchi-u.ac.jp

    2009-04-30

    Cu particles that have been reductively generated at the oxidized surface of a boron-doped diamond electrode (O-BDD) can be removed from the electrode's surface by the repulsive electrostatic force of the surface dipole moment during a potential cycle of a solution of Cu{sup 2+} ions. The objective of this study was to isolate various metal particles other than Cu by use of a fluorine-terminated BDD surface (F-BDD) with a stronger surface dipole moment than O-BDD, and to clarify the mechanism of the metal particles' separation from the electrode. During the potential cycle treatment of Cu{sup 2+} ions using F-BDD, the reionization of the reduced Cu could be suppressed in the presence of dissolved oxygen, and the Cu particles were separated from the electrode surface as CuO. A similar result was seen with O-BDD. The degree of separation of the Cu particles could be drastically enhanced by raising the upper potential limit in the potential cycle from +0.2 to +0.8 V. By setting the upper potential to a potential greater than the metal-metal oxide equilibrium line in the potential-pH equilibrium diagram of the Cu-water system (Pourbaix Diagram), oxidation of the reduced metal surface by reaction with dissolved oxygen could be accelerated and the surface of metal particles could be insulated. The Cu particles were forced from the BDD surface by the electrostatic repulsion from the surface dipole moment of F-BDD. Also, it turned out that the physical adsorption of chloride ions (Cl{sup -}) on the electrode surface intensified the electrostatic repulsive force between the F- or O-BDD surface and the metal particles, and thus increased the degree of the metal particles' separation. For Zn with a metal-metal oxide equilibrium potential of approximately -0.8 V at pH 7, complete separation of the Zn particles was achieved with F-BDD by setting the upper potential limit to +0.8 V (vs. Ag/AgCl), decreasing the Zn{sup 2+} concentration (1/10 that of Cu{sup 2

  19. Surface Engineering for Bone Implants: A Trend from Passive to Active Surfaces

    Directory of Open Access Journals (Sweden)

    John Jansen

    2012-07-01

    Full Text Available The mechanical and biological properties of bone implants need to be optimal to form a quick and firm connection with the surrounding environment in load bearing applications. Bone is a connective tissue composed of an organic collagenous matrix, a fine dispersion of reinforcing inorganic (calcium phosphate nanocrystals, and bone-forming and -degrading cells. These different components have a synergistic and hierarchical structure that renders bone tissue properties unique in terms of hardness, flexibility and regenerative capacity. Metallic and polymeric materials offer mechanical strength and/or resilience that are required to simulate bone tissue in load-bearing applications in terms of maximum load, bending and fatigue strength. Nevertheless, the interaction between devices and the surrounding tissue at the implant interface is essential for success or failure of implants. In that respect, coatings can be applied to facilitate the process of bone healing and obtain a continuous transition from living tissue to the synthetic implant. Compounds that are inspired by inorganic (e.g., hydroxyapatite crystals or organic (e.g., collagen, extracellular matrix components, enzymes components of bone tissue, are the most obvious candidates for application as implant coating to improve the performance of bone implants. This review provides an overview of recent trends and strategies in surface engineering that are currently investigated to improve the biological performance of bone implants in terms of functionality and biological efficacy.

  20. Contamination by urban superficial runoff: accumulated heavy metals on a road surface

    Directory of Open Access Journals (Sweden)

    Carlos Alfonso Zafra Mejía

    2007-01-01

    Full Text Available Studying the behaviour of accumulated contamination on urban surfaces is important in designing control methods minimising the impacts of surface runoff on the environment. This paper presents data regarding the sediment collected on the surface of an urban road in the city of Torrelavega in northern Spain during a period of 65 days during which 132 samples were collected. Two types of sediment collection samples were obtained: vacuumed dry samples (free load and those swept up following vacuuming (fixed load. The results showed that heavy metal concentration in the collected sediment (Pb, Zn, Cu and Cd was inversely proportional to particle diameter. High heavy metal concentrations were found in the smaller fraction (63 pm. Regression equations were calculated for heavy metal concentration regarding particle diameter. Large heavy metal loads were found in the larger fraction (125 pm. The results provide information for analysing runoff water quality in urban areas and designing treatment strategies.

  1. Optimization of transition-metal dichalcogenides based field-effecttransistors via contact engineering

    Science.gov (United States)

    Perera, Meeghage Madusanka

    Layered transition Metal Dichalcogenides (TMDs) have demonstrated a wide range of remarkable properties for applications in next generation nano-electronics. These systems have displayed many "graphene-like" properties including a relatively high carrier mobility, mechanical flexibility, chemical and thermal stability, and moreover offer the significant advantage of a substantial band gap. However, the fabrication of high performance field-effect transistors (FETs) of TMDs is challenging mainly due to the formation of a significant Schottky barrier at metal/TMD interface in most cases. The main goal of this study is to develop novel contact engineering strategies to achieve low-resistance Ohmic contacts. Our first approach is to use Ionic Liquid (IL) gating of metal contacted MoS2 FETs to achieve highly transparent tunneling contacts due to the strong band banding at metal/MoS2 interface. The substantially reduced contact resistance in ionic-liquid-gated bilayer and few-layer MoS 2 FETs results in an ambipolar behavior with high ON/OFF ratios, a near-ideal subthreshold swing, and significantly improved field-effect mobility. Remarkably, the mobility of a 3-nm-thick MoS2 FET with an IL gate was found to increase from ˜ 100 cm2V-1s-1 to ˜ 220 cm2V-1s-1 as the temperature decreased from 180 K to 77 K. This finding is in quantitative agreement with the true channel mobility measured by four-terminal measurement, suggesting that the mobility is predominantly limited by phonon-scattering. To further improve the contacts of TMD devices, graphene was used as work function tunable electrodes. In order to achieve low Schottky barrier height, both IL gating and surface charge transfer doping were used to tune the work function of graphene electrodes close to the conduction band edge of MoS 2. As a result, the performance of our graphene contacted MoS2 FETs is limited by the channel rather than contacts, which is further verified by four-terminal measurements. Finally

  2. Molecular metal catalysts on supports: organometallic chemistry meets surface science.

    Science.gov (United States)

    Serna, Pedro; Gates, Bruce C

    2014-08-19

    Recent advances in the synthesis and characterization of small, essentially molecular metal complexes and metal clusters on support surfaces have brought new insights to catalysis and point the way to systematic catalyst design. We summarize recent work unraveling effects of key design variables of site-isolated catalysts: the metal, metal nuclearity, support, and other ligands on the metals, also considering catalysts with separate, complementary functions on supports. The catalysts were synthesized with the goal of structural simplicity and uniformity to facilitate incisive characterization. Thus, they are essentially molecular species bonded to porous supports chosen for their high degree of uniformity; the supports are crystalline aluminosilicates (zeolites) and MgO. The catalytic species are synthesized in reactions of organometallic precursors with the support surfaces; the precursors include M(L)2(acetylacetonate)1-2, with M = Ru, Rh, Ir, or Au and the ligands L = C2H4, CO, or CH3. Os3(CO)12 and Ir4(CO)12 are used as precursors of supported metal clusters, and some such catalysts are made by ship-in-a-bottle syntheses to trap the clusters in zeolite cages. The simplicity and uniformity of the supported catalysts facilitate precise structure determinations, even in reactive atmospheres and during catalysis. The methods of characterizing catalysts in reactive atmospheres include infrared (IR), extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and nuclear magnetic resonance (NMR) spectroscopies, and complementary methods include density functional theory and atomic-resolution aberration-corrected scanning transmission electron microscopy for imaging of individual metal atoms. IR, NMR, XANES, and microscopy data demonstrate the high degrees of uniformity of well-prepared supported species. The characterizations determine the compositions of surface metal complexes and clusters, including the ligands and the metal

  3. Electrosprayed Heavy Ion and Nanodrop Beams for Surface Engineering and Electrical Propulsion

    Science.gov (United States)

    2014-09-10

    Studies At the macroscale, the surface of a Taylor cone just before ion emission is an equipotential with a normal electric field strength found from...AFRL-OSR-VA-TR-2014-0246 Electrosprayed Heavy Ion and Nanodrop Beams for Surface Engineering M Gamero-Castano UNIVERSITY OF CALIFORNIA IRVINE Final...298 (Re . 8-98) v Prescribed by ANSI Std. Z39.18 1 Electrosprayed Heavy Ion and Nanodrop Beams for Surface Engineering and Electrical Propulsion

  4. Optical response of a flat metallic surface coated with a monolayer array of latex spheres

    International Nuclear Information System (INIS)

    Shi Lei; Liu Xiaohan; Yin Haiwei; Zi Jian

    2010-01-01

    We report on the fabrication, characterization and simulation of a structure consisting of a flat metallic surface coated with a monolayer array of latex spheres. This structure shows interesting optical response: over flat metallic surfaces a series of reflection minima appear in reflection spectra. Numerical simulations revealed that the structure can support two types of surface modes: surface plasmon-polaritons bound at the metallic surface and guided modes confined to the array of latex spheres, or their hybrids. Both experimental and theoretical results indicated that these surface modes show well-defined band structures due to the introduced periodicity by the monolayer array of latex spheres.

  5. Phase engineering of monolayer transition-metal dichalcogenide through coupled electron doping and lattice deformation

    International Nuclear Information System (INIS)

    Ouyang, Bin; Lan, Guoqiang; Song, Jun; Guo, Yinsheng; Mi, Zetian

    2015-01-01

    First-principles calculations were performed to investigate the phase stability and transition within four monolayer transition-metal dichalcogenide (TMD) systems, i.e., MX 2 (M = Mo or W and X = S or Se) under coupled electron doping and lattice deformation. With the lattice distortion and electron doping density treated as state variables, the energy surfaces of different phases were computed, and the diagrams of energetically preferred phases were constructed. These diagrams assess the competition between different phases and predict conditions of phase transitions for the TMDs considered. The interplay between lattice deformation and electron doping was identified as originating from the deformation induced band shifting and band bending. Based on our findings, a potential design strategy combining an efficient electrolytic gating and a lattice straining to achieve controllable phase engineering in TMD monolayers was demonstrated

  6. Methanol Oxidation on Model Elemental and Bimetallic Transition Metal Surfaces

    DEFF Research Database (Denmark)

    Tritsaris, G. A.; Rossmeisl, J.

    2012-01-01

    Direct methanol fuel cells are a key enabling technology for clean energy conversion. Using density functional theory calculations, we study the methanol oxidation reaction on model electrodes. We discuss trends in reactivity for a set of monometallic and bimetallic transition metal surfaces, flat...... sites on the surface and to screen for novel bimetallic surfaces of enhanced activity. We suggest platinum copper surfaces as promising anode catalysts for direct methanol fuel cells....

  7. Characterizing heavy metal build-up on urban road surfaces: Implication for stormwater reuse

    International Nuclear Information System (INIS)

    Liu, An; Liu, Liang; Li, Dunzhu; Guan, Yuntao

    2015-01-01

    Stormwater reuse is increasingly popular in the worldwide. In terms of urban road stormwater, it commonly contains toxic pollutants such as heavy metals, which could undermine the reuse safety. The research study investigated heavy metal build-up characteristics on urban roads in a typical megacity of South China. The research outcomes show the high variability in heavy metal build-up loads among different urban road sites. The degree of traffic congestion and road surface roughness was found to exert a more significant influence on heavy metal build-up rather than traffic volume. Due to relatively higher heavy metal loads, stormwater from roads with more congested traffic conditions or rougher surfaces might be suitable for low-water-quality required activities while the stormwater from by-pass road sections could be appropriate for relatively high-water-quality required purposes since the stormwater could be relatively less polluted. Based on the research outcomes, a decision-making process for heavy metals based urban road stormwater reuse was proposed. The new finding highlights the importance to undertaking a “fit-for-purpose” road stormwater reuse strategy. Additionally, the research results can also contribute to enhancing stormwater reuse safety. - Highlights: • Heavy metal (HM) build-up varies with traffic and road surface conditions. • Traffic congestion and surface roughness exert a higher impact on HM build-up. • A “fit-for-purpose” strategy could suit urban road stormwater reuse

  8. Characterizing heavy metal build-up on urban road surfaces: Implication for stormwater reuse

    Energy Technology Data Exchange (ETDEWEB)

    Liu, An [Research Centre of Environmental Engineering and Management, Graduate School at Shenzhen, Tsinghua University, 518055 Shenzhen (China); Cooperative Research and Education Centre for Environmental Technology, Kyoto University–Tsinghua University, 518055 Shenzhen (China); Liu, Liang; Li, Dunzhu [Research Centre of Environmental Engineering and Management, Graduate School at Shenzhen, Tsinghua University, 518055 Shenzhen (China); Guan, Yuntao, E-mail: guanyt@tsinghua.edu.cn [Research Centre of Environmental Engineering and Management, Graduate School at Shenzhen, Tsinghua University, 518055 Shenzhen (China); School of Environment, Tsinghua University, Beijing 100084 (China)

    2015-05-15

    Stormwater reuse is increasingly popular in the worldwide. In terms of urban road stormwater, it commonly contains toxic pollutants such as heavy metals, which could undermine the reuse safety. The research study investigated heavy metal build-up characteristics on urban roads in a typical megacity of South China. The research outcomes show the high variability in heavy metal build-up loads among different urban road sites. The degree of traffic congestion and road surface roughness was found to exert a more significant influence on heavy metal build-up rather than traffic volume. Due to relatively higher heavy metal loads, stormwater from roads with more congested traffic conditions or rougher surfaces might be suitable for low-water-quality required activities while the stormwater from by-pass road sections could be appropriate for relatively high-water-quality required purposes since the stormwater could be relatively less polluted. Based on the research outcomes, a decision-making process for heavy metals based urban road stormwater reuse was proposed. The new finding highlights the importance to undertaking a “fit-for-purpose” road stormwater reuse strategy. Additionally, the research results can also contribute to enhancing stormwater reuse safety. - Highlights: • Heavy metal (HM) build-up varies with traffic and road surface conditions. • Traffic congestion and surface roughness exert a higher impact on HM build-up. • A “fit-for-purpose” strategy could suit urban road stormwater reuse.

  9. Surface modification of nanodiamond through metal free atom transfer radical polymerization

    Science.gov (United States)

    Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2016-12-01

    Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by 1H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

  10. A novel fabrication method for surface integration of metal structures into polymers (SIMSIP)

    Science.gov (United States)

    Carrion-Gonzalez, Hector

    Recently developed flexible electronics applications require that the thin metal films embedded on elastomer substrates also be flexible. These electronic systems are radically different in terms of performance and functionality than conventional silicon-based devices. A key question is whether the metal deposited on flexible films can survive large strains without rupture. Cumbersome macro-fabrication methods have been developed for functional and bendable electronics (e.g., interconnects) encapsulated between layers of polymer films. However, future electronic applications may require electronic flexible devices to be in intimate contact with curved surfaces (e.g., retinal implants) and to be robust enough to withstand large and repeated mechanical deformations. In this research, a novel technique for surface integration of metal structures into polymers (SIMSIP) was developed. Surface embedding, as opposed to placing metal on polymers, provides better adherence while leaving the surface accessible for contacts. This was accomplished by first fabricating the micro-scale metal patterns on a quartz or Teflon mother substrate, and then embedding them to a flexible polyimide thin film. The technique was successfully used to embed micro-metal structures of gold (Au), silver (Ag), and copper (Cu) into polyimide films without affecting the functional properties of the either the metals or the polymers. Experimental results confirm the successful surface-embedding of metal structures as narrow as 0.6 microm wide for different geometries commonly used in circuit design. Although similar approaches exist in literature, the proposed methodology provides a simpler and more reliable way of producing flexible circuits/electronics that is also suitable for high volume manufacturing. In order to demonstrate the flexibility of metal interconnects fabricated using the SIMSIP technique, multiple Au electrodes (5 microm and 2.5 microm wide) were tested using the X-theta bending

  11. Viscous surface flow induced on Ti-based bulk metallic glass by heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kun [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Hu, Zheng [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Science and Technology on Vehicle Transmission Laboratory, China North Vehicle Research Institute, Beijing 100072 (China); Li, Fengjiang [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wei, Bingchen, E-mail: weibc@imech.ac.cn [Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-12-30

    Highlights: • Obvious smoothing and roughening phases on the Ti-based MG surface resulted, which correspond respectively to the normal and off-normal incidence angles. • Atomic force microscopy confirms two types of periodic ripples distributed evenly over the rough surface. • The irradiation-induced viscosity of MG is about 4×10{sup 12} Pa·s, which accords with the theoretical prediction for metallic glasses close to glass transition temperature. • Surface-confined viscous flow plays a dominant quantitative role, which is due to radiation-induced softening of the low-viscosity surface layer. - Abstract: Ti-based bulk metallic glass was irradiated by a 20 MeV Cl{sup 4+} ion beam under liquid-nitrogen cooling, which produced remarkable surface smoothing and roughening that respectively correspond to normal and off-normal incidence angles of irradiation. Atomic force microscopy confirms two types of periodic ripples distributed evenly over the rough glass surface. In terms of mechanism, irradiation-induced viscosity agrees with the theoretical prediction for metallic glasses near glass transition temperature. Here, a model is introduced, based on relaxation of confined viscous flow with a thin liquid-like layer, that explains both surface smoothing and ripple formation. This study demonstrates that bulk metallic glass has high morphological instability and low viscosity under ion irradiation, which assets can pave new paths for metallic glass applications.

  12. Thermally generated metals for plasmonic coloring and surface-enhanced Raman sensing

    Science.gov (United States)

    Huang, Zhenping; Chen, Jian; Liu, Guiqiang; Wang, Yan; Liu, Yi; Tang, Li; Liu, Zhengqi

    2018-03-01

    Spectral coloring glass and its application on the surface-enhanced Raman scattering are demonstrated experimentally via a simple and moderate heat-treating of the top ultrathin gold film to create discrete nanoparticles, which can produce localized surface plasmon resonances and strong plasmonic near-field coupling effects. Ultrathin metal films with a wide range of thicknesses are investigated by different heat-treatment processes. The annealed metal films have been demonstrated with a series of spectral coloring responses. Moreover, the microscopy images of the metal film structures confirm the formation of distinct geometry features in these operation procedures. Densely packed nanoparticles are observed for the ultrathin metal film with the single-digit level of thickness. With increasing the film thickness over 10 nm, metallic clusters and porous morphologies can be obtained. Importantly, the metallic resonators can provide enhanced Raman scattering with the detection limit down to 10 - 7 molL - 1 of Rhodamine 6G molecules due to the excitation of plasmon resonances and strong near-field coupling effects. These features hold great potential for large-scale and low-cost production of colored glass and Raman substrate.

  13. Ductile fracture surface morphology of amorphous metallic alloys

    NARCIS (Netherlands)

    Miskuf, J; Csach, K; Ocelik, [No Value; Bengus, VZ; Tabachnikova, ED; Duhaj, P; Ocelik, Vaclav

    1999-01-01

    Fracture surfaces of ductile failure of two types bulk amorphous metallic alloys were studied using quantitative and qualitative fractographic analysis. The observed fractographic behaviour of ductile failure in comparison with the ductile failure of amorphous alloy ribbons shows signs of the same

  14. 21 CFR 178.3910 - Surface lubricants used in the manufacture of metallic articles.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Surface lubricants used in the manufacture of... lubricants used in the manufacture of metallic articles. The substances listed in this section may be safely used in surface lubricants employed in the manufacture of metallic articles that contact food, subject...

  15. Direct electrodeposition of metal nanowires on electrode surface

    International Nuclear Information System (INIS)

    Gambirasi, Arianna; Cattarin, Sandro; Musiani, Marco; Vazquez-Gomez, Lourdes; Verlato, Enrico

    2011-01-01

    A method for decorating the surface of disk electrodes with metal nanowires is presented. Cu and Ni nanowires with diameters from 1.0 μm to 0.2 μm are directly deposited on the electrode surface using a polycarbonate membrane filter template maintained in contact with the metal substrate by the soft homogeneous pressure of a sponge soaked with electrolyte. The morphologic and structural properties of the deposit are characterized by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The latter shows that the head of nanowires with diameter of 0.4 μm is ordinarily polycrystalline, and that of nanowires with diameter of 0.2 μm is almost always monocrystalline for Cu and frequently also for Ni. Cyclic voltammetries and impedance investigations recorded in alkaline solutions at representative Ni electrodes decorated with nanowires provide consistent values of roughness factor, in the range 20-25.

  16. Adventitious Carbon on Primary Sample Containment Metal Surfaces

    Science.gov (United States)

    Calaway, M. J.; Fries, M. D.

    2015-01-01

    Future missions that return astromaterials with trace carbonaceous signatures will require strict protocols for reducing and controlling terrestrial carbon contamination. Adventitious carbon (AC) on primary sample containers and related hardware is an important source of that contamination. AC is a thin film layer or heterogeneously dispersed carbonaceous material that naturally accrues from the environment on the surface of atmospheric exposed metal parts. To test basic cleaning techniques for AC control, metal surfaces commonly used for flight hardware and curating astromaterials at JSC were cleaned using a basic cleaning protocol and characterized for AC residue. Two electropolished stainless steel 316L (SS- 316L) and two Al 6061 (Al-6061) test coupons (2.5 cm diameter by 0.3 cm thick) were subjected to precision cleaning in the JSC Genesis ISO class 4 cleanroom Precision Cleaning Laboratory. Afterwards, the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.

  17. Investigations of thin p-GaN light-emitting diodes with surface plasmon compatible metallization

    DEFF Research Database (Denmark)

    Fadil, Ahmed; Ou, Yiyu; Iida, Daisuke

    2016-01-01

    We investigate device performance of InGaN light-emitting diodes with a 30-nm p-GaN layer. The metallization used to separate the p-contact from plasmonic metals, reveals limitations on current spreading which reduces surface plasmonic enhancement.......We investigate device performance of InGaN light-emitting diodes with a 30-nm p-GaN layer. The metallization used to separate the p-contact from plasmonic metals, reveals limitations on current spreading which reduces surface plasmonic enhancement....

  18. High-power spallation target using a heavy liquid metal free surface flow

    International Nuclear Information System (INIS)

    Litfin, K.; Fetzer, J.R.; Batta, A.; Class, A.G.; Wetzel, Th.

    2015-01-01

    A prototype of a heavy liquid metal free surface target as proposed for the multi-purpose hybrid research reactor for high-tech applications in Mol, Belgium, has been set up and experimentally investigated at the Karlsruhe Liquid Metal Laboratory. A stable operation was demonstrated in a wide range of operating conditions and the surface shape was detected and compared with numerical pre-calculations employing Star-CD. Results show a very good agreement of experiment and numerical predictions which is an essential input for other windowless target designs like the META:LIC target for the European Spallation Source. (author)

  19. Safety analysis of dual purpose metal cask subjected to impulsive loads due to aircraft engine crash

    International Nuclear Information System (INIS)

    Shirai, Koji; Namba, Kosuke; Saegusa, Toshiari

    2009-01-01

    In Japan, the first Interim Storage Facility of spent nuclear fuel away from reactor site is being planned to start its commercial operation around 2010, in use of dual-purpose metal cask in the northern part of Main Japan Island. Business License Examination for safety design approval has started since March, 2007. To demonstrate the more scientific and rational performance of safety regulation activities on each phase for the first license procedure, CREPEI has executed demonstration tests with full scale casks, such as drop tests onto real targets without impact limiters and seismic tests subjected to strong earthquake motions. Moreover, it is important to develop the knowledge for the inherent security of metal casks under extreme mechanical-impact conditions, especially for increasing interest since the terrorist attacks from 11th September 2001. This paper presents dynamic mechanical behavior of the metal cask lid closure system caused by direct aircraft engine crash and describes calculated results (especially, leak tightness based on relative dynamic displacements between metallic seals). Firstly, the local penetration damage of the interim storage facility building by a big passenger aircraft engine research (diameter 2.7m, length 4.3m, weight 4.4ton, impact velocity 90m/s) has been examined. The reduced velocity is calculated by the local damage formula for concrete structure with its thickness of 70cm. The load vs. time function for this reduced velocity (60m/s) is estimated by the impact analysis using Finite Element code LS-DYNA with the full scale engine model onto a hypothetically rigid target. Secondly, as the most critical scenarios for the metal cask, two impact scenarios (horizontal impact hitting the cask and vertical impact onto the lid metallic seal system) are chosen. To consider the geometry of all bolts for two lids, the gasket reaction forces and the inner pressure of the cask cavity, the detailed three dimensional FEM models are developed

  20. Safety Analysis of Dual Purpose Metal Cask Subjected to Impulsive Loads due to Aircraft Engine Crash

    Science.gov (United States)

    Shirai, Koji; Namba, Kosuke; Saegusa, Toshiari

    In Japan, the first Interim Storage Facility of spent nuclear fuel away from reactor site is being planned to start its commercial operation around 2010, in use of dual-purpose metal cask in the northern part of Main Japan Island. Business License Examination for safety design approval has started since March, 2007. To demonstrate the more scientific and rational performance of safety regulation activities on each phase for the first license procedure, CREPEI has executed demonstration tests with full scale casks, such as drop tests onto real targets without impact limiters(1) and seismic tests subjected to strong earthquake motions(2). Moreover, it is important to develop the knowledge for the inherent security of metal casks under extreme mechanical-impact conditions, especially for increasing interest since the terrorist attacks from 11th September 2001(3)-(6). This paper presents dynamic mechanical behavior of the metal cask lid closure system caused by direct aircraft engine crash and describes calculated results (especially, leak tightness based on relative dynamic displacements between metallic seals). Firstly, the local penetration damage of the interim storage facility building by a big passenger aircraft engine crash (diameter 2.7m, length 4.3m, weight 4.4ton, impact velocity 90m/s) has been examined. The reduced velocity is calculated by the local damage formula for concrete structure with its thickness of 70cm. The load vs. time function for this reduced velocity (60m/s) is estimated by the impact analysis using Finite Element code LS-DYNA with the full scale engine model onto a hypothetically rigid target. Secondly, as the most critical scenarios for the metal cask, two impact scenarios (horizontal impact hitting the cask and vertical impact onto the lid metallic seal system) are chosen. To consider the geometry of all bolts for two lids, the gasket reaction forces and the inner pressure of the cask cavity, the detailed three dimensional FEM models are

  1. An orbital-overlap model for minimal work functions of cesiated metal surfaces

    International Nuclear Information System (INIS)

    Chou, Sharon H; Bargatin, Igor; Howe, Roger T; Voss, Johannes; Vojvodic, Aleksandra; Abild-Pedersen, Frank

    2012-01-01

    We introduce a model for the effect of cesium adsorbates on the work function of transition metal surfaces. The model builds on the classical point-dipole equation by adding exponential terms that characterize the degree of orbital overlap between the 6s states of neighboring cesium adsorbates and its effect on the strength and orientation of electric dipoles along the adsorbate-substrate interface. The new model improves upon earlier models in terms of agreement with the work function-coverage curves obtained via first-principles calculations based on density functional theory. All the cesiated metal surfaces have optimal coverages between 0.6 and 0.8 monolayers, in accordance with experimental data. Of all the cesiated metal surfaces that we have considered, tungsten has the lowest minimum work function, also in accordance with experiments.

  2. Trends in catalytic NO decomposition over transition metal surfaces

    DEFF Research Database (Denmark)

    Falsig, Hanne; Bligaard, Thomas; Rass-Hansen, Jeppe

    2007-01-01

    The formation of NOx from combustion of fossil and renewable fuels continues to be a dominant environmental issue. We take one step towards rationalizing trends in catalytic activity of transition metal catalysts for NO decomposition by combining microkinetic modelling with density functional...... theory calculations. We show specifically why the key problem in using transition metal surfaces to catalyze direct NO decomposition is their significant relative overbinding of atomic oxygen compared to atomic nitrogen....

  3. Replication of surface features from a master model to an amorphous metallic article

    Science.gov (United States)

    Johnson, William L.; Bakke, Eric; Peker, Atakan

    1999-01-01

    The surface features of an article are replicated by preparing a master model having a preselected surface feature thereon which is to be replicated, and replicating the preselected surface feature of the master model. The replication is accomplished by providing a piece of a bulk-solidifying amorphous metallic alloy, contacting the piece of the bulk-solidifying amorphous metallic alloy to the surface of the master model at an elevated replication temperature to transfer a negative copy of the preselected surface feature of the master model to the piece, and separating the piece having the negative copy of the preselected surface feature from the master model.

  4. A local leaky-box model for the local stellar surface density-gas surface density-gas phase metallicity relation

    Science.gov (United States)

    Zhu, Guangtun Ben; Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Yan, Renbin; Brinkmann, Jonathan

    2017-07-01

    We revisit the relation between the stellar surface density, the gas surface density and the gas-phase metallicity of typical disc galaxies in the local Universe with the SDSS-IV/MaNGA survey, using the star formation rate surface density as an indicator for the gas surface density. We show that these three local parameters form a tight relationship, confirming previous works (e.g. by the PINGS and CALIFA surveys), but with a larger sample. We present a new local leaky-box model, assuming star-formation history and chemical evolution is localized except for outflowing materials. We derive closed-form solutions for the evolution of stellar surface density, gas surface density and gas-phase metallicity, and show that these parameters form a tight relation independent of initial gas density and time. We show that, with canonical values of model parameters, this predicted relation match the observed one well. In addition, we briefly describe a pathway to improving the current semi-analytic models of galaxy formation by incorporating the local leaky-box model in the cosmological context, which can potentially explain simultaneously multiple properties of Milky Way-type disc galaxies, such as the size growth and the global stellar mass-gas metallicity relation.

  5. Research on Lessening of Bonding Effects Between the Metallic and Non-Metallic Surfaces Through the Graphite Films Deposited with Pulsed Electrical Discharges Process

    Science.gov (United States)

    Marin, L.; Topala, P.

    2017-06-01

    The paper presents the results of experimental research on the physics of natural graphite film formation, the establishment of chemical composition and functional properties of the graphite films, formed on metal surfaces, as a result of the action of plasma in the air environment, at a normal pressure, under the electrical discharge in impulse conditions (EDI). The researchings were performed in the frame of doctoral thesis “Research on lessening of the bonding effects between the metallic and nonmetallic surfaces through the graphite films” and aimed to identify the phenomena that occur at the interface metal/ film of graphite, and to identify also the technological applications that it may have the surface treatment for submitting the films of graphite on metallic surfaces achieved through an innovative process of electrical pulsed discharges. After the research works from the PhD theme above mentioned, a number of interesting properties of graphite pellicle have been identified ie reducing of metal surface polarity. This led to drastic decreases for the values of adhesion when bonding of metal surfaces was performed using a structural polyurethane adhesive designed by ICECHIM. Following the thermo-gravimetric analysis, performed of the graphite film obtained by process of electrical pulsed discharges, have been also discovered other interesting properties for this, ie reversible mass additions at specific values of the working temperature Chemical and scanning electron microscopy analysis have revealed that on the metallic surface subjected to electrical pulsed discharges process, outside the graphite film, it is also obtained a series of spatial formation composed of carbon atoms fullerenes type which are responsible for the phenomenon of addition of mass.

  6. SURFACE ENGINEERING FOR PARTS MADE BY ADDITIVE MANUFACTURING

    OpenAIRE

    Nutal, Nicolas; Rochus, Pierre; Collette, Jean-Paul; Crahay, Jean; Larnicol, Maiween; Jochem, Helen; Magnien, Julien; Masse, Christian; Rigo, Olivier; Vanhumbeeck, Jean-François; Pambaguian, Laurent

    2015-01-01

    the surface preparation of metal parts made by additive manufacturing (AM). AM is a technology of choice for manufacturing of parts with complex shapes (heat exchangers, RF supports, optical parts…) and integrated functions such as conformal cooling channels, clips, hinges, etc. This opens the door for lightweight parts which are of prime importance for space applications. The potential of the AM technologies is however impeded by the quite rough surface finish that is observed on the as-m...

  7. The passivation of uranium metal surfaces by nitrogen bombardment — the formation of uranium nitride

    Science.gov (United States)

    Allen, Geoffrey C.; Holmes, Nigel R.

    1988-05-01

    As part of a detailed investigation of the behaviour of metallic uranium in various atmospheres, we have examined the reaction between nitrogen gas and uranium metal. At room temperature there was no evidence of reaction between nitrogen gas and a clean metal surface; the only changes observed could be attributed to reaction between the metal and traces of oxygen (less than 0.1 ppm) in the nitrogen gas. Reaction between the metal and nitrogen was induced, however, by accelerating nitrogen towards the surface using a fast atom gun. The resulting nitrided surface was characterized by X-ray photoelectron spectroscopy, and its oxidation behaviour was monitored over an extended period in UHV and in air.

  8. An Integrated Surface Engineering Technology Development for Improving Energy Efficiency of Engine Components

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Hsu; Liming Chang; Huan Zhan

    2009-05-31

    Frictional losses are inherent in most practical mechanical systems. The ability to control friction offers many opportunities to achieve energy conservation. Over the years, materials, lubricants, and surface modifications have been used to reduce friction in automotive and diesel engines. However, in recent years, progress in friction reduction technology has slowed because many of the inefficiencies have been eliminated. A new avenue for friction reduction is needed. Designing surfaces specifically for friction reduction with concomitant enhanced durability for various engine components has emerged recently as a viable opportunity due to advances in fabrication and surface finishing techniques. Recently, laser ablated dimples on surfaces have shown friction reduction properties and have been demonstrated successfully in conformal contacts such as seals where the speed is high and the load is low. The friction reduction mechanism in this regime appears to depend on the size, patterns, and density of dimples in the contact. This report describes modeling efforts in characterizing surface textures and understanding their mechanisms for enhanced lubrication under high contact pressure conditions. A literature survey is first presented on the development of descriptors for irregular surface features. This is followed by a study of the hydrodynamic effects of individual micro-wedge dimples using the analytical solution of the 1-D Reynolds equation and the determination of individual components of the total friction resistance. The results obtained provide a better understanding of the dimple orientation effects and the approach which may be used to further compare the friction reduction provided by different texture patterns.

  9. Liquid metal actuator driven by electrochemical manipulation of surface tension

    Science.gov (United States)

    Russell, Loren; Wissman, James; Majidi, Carmel

    2017-12-01

    We examine the electrocapillary properties of a fluidic actuator composed of a liquid metal droplet that is submerged in electrolytic solution and attached to an elastic beam. The beam deflection is controlled by electrochemically driven changes in the surface energy of the droplet. The metal is a eutectic gallium-indium alloy that is liquid at room temperature and forms an nm-thin Ga2O3 skin when oxidized. The effective surface tension of the droplet changes dramatically with oxidation and reduction, which are reversibly controlled by applying low voltage to the electrolytic bath. Wetting the droplet to two copper pads allows for a controllable tensile force to be developed between the opposing surfaces. We demonstrate the ability to reliably control force by changing the applied oxidizing voltage. Actuator forces and droplet geometries are also examined by performing a computational fluid mechanics simulation using Surface Evolver. The theoretical predictions are in qualitative agreement with the experimental measurements and provide additional confirmation that actuation is driven by surface tension.

  10. Surface-Emitting Distributed Feedback Terahertz Quantum-Cascade Lasers in Metal-Metal Waveguides

    Science.gov (United States)

    Kumar, Sushil; Williams, Benjamin S.; Qin, Qi; Lee, Alan W. M.; Hu, Qing; Reno, John L.

    2007-01-01

    Single-mode surface-emitting distributed feedback terahertz quantumcascade lasers operating around 2.9 THz are developed in metal-metal waveguides. A combination of techniques including precise control of phase of reflection at the facets, and u e of metal on the sidewalls to eliminate higher-order lateral modes allow robust single-mode operation over a range of approximately 0.35 THz. Single-lobed far-field radiation pattern is obtained using a pi phase-shift in center of the second-order Bragg grating. A grating device operating at 2.93 THz lased up to 149 K in pulsed mode and a temperature tuning of 19 .7 GHz was observed from 5 K to 147 K. The same device lased up to 78 K in continuous-wave (cw) mode emitting more than 6 m W of cw power at 5 K. ln general, maximum temperature of pulsed operation for grating devices was within a few Kelvin of that of multi-mode Fabry-Perot ridge lasers

  11. Multifunctional methacrylate-based coatings for glass and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pospiech, Doris, E-mail: pospiech@ipfdd.de [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Jehnichen, Dieter [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Starke, Sandra; Müller, Felix [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Technische Universität Dresden, Organic Chemistry of Polymers, Dresden (Germany); Bünker, Tobias [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Wollenberg, Anne [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Technische Universität Dresden, Organic Chemistry of Polymers, Dresden (Germany); Häußler, Liane; Simon, Frank; Grundke, Karina; Oertel, Ulrich [Leibniz-Institut für Polymerforschung Dresden e. V., Dresden (Germany); Opitz, Michael; Kruspe, Rainer [IDUS Biologisch Analytisches Umweltlabor GmbH, Ottendorf-Okrilla (Germany)

    2017-03-31

    Highlights: • New methacrylate-based copolymers synthesized by free radical polymerization. • Comonomer AAMA was able to complex Cu (II) ions in solvent annealing procedure. • Coatings had efficient anti-biofouling efficacy. - Abstract: In order to prevent freshwater biofouling glass and metal surfaces were coated with novel transparent methacrylate-based copolymers. The multifunctionality of the copolymers, such as adhesion to the substrate, surface polarity, mechanical long-term stability in water, and ability to form metal complexes was inserted by the choice of suitable comonomers. The monomer 2-acetoacetoxy ethyl methacrylate (AAMA) was used as complexing unit to produce copper(II) complexes in the coating’s upper surface layer. The semifluorinated monomer 1H,1H,2H,2H-perfluorodecyl methacrylate was employed to adjust the surface polarity and wettability. Comprehensive surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surface compositions and properties can be easily adjusted by varying the concentrations of the comonomers. The formation of copper(II) complexes along the copolymer chains and their stability against washing out with plenty of water was proven by XPS. Copolymers containing semifluorinated comonomers significantly inhibited the growth of Achnanthidium species. Copolymers with copper-loaded AAMA-sequences were able to reduce both the growth of Achnanthidium spec. and Staphylococcus aureus.

  12. Multifunctional methacrylate-based coatings for glass and metal surfaces

    International Nuclear Information System (INIS)

    Pospiech, Doris; Jehnichen, Dieter; Starke, Sandra; Müller, Felix; Bünker, Tobias; Wollenberg, Anne; Häußler, Liane; Simon, Frank; Grundke, Karina; Oertel, Ulrich; Opitz, Michael; Kruspe, Rainer

    2017-01-01

    Highlights: • New methacrylate-based copolymers synthesized by free radical polymerization. • Comonomer AAMA was able to complex Cu (II) ions in solvent annealing procedure. • Coatings had efficient anti-biofouling efficacy. - Abstract: In order to prevent freshwater biofouling glass and metal surfaces were coated with novel transparent methacrylate-based copolymers. The multifunctionality of the copolymers, such as adhesion to the substrate, surface polarity, mechanical long-term stability in water, and ability to form metal complexes was inserted by the choice of suitable comonomers. The monomer 2-acetoacetoxy ethyl methacrylate (AAMA) was used as complexing unit to produce copper(II) complexes in the coating’s upper surface layer. The semifluorinated monomer 1H,1H,2H,2H-perfluorodecyl methacrylate was employed to adjust the surface polarity and wettability. Comprehensive surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surface compositions and properties can be easily adjusted by varying the concentrations of the comonomers. The formation of copper(II) complexes along the copolymer chains and their stability against washing out with plenty of water was proven by XPS. Copolymers containing semifluorinated comonomers significantly inhibited the growth of Achnanthidium species. Copolymers with copper-loaded AAMA-sequences were able to reduce both the growth of Achnanthidium spec. and Staphylococcus aureus.

  13. Observation of the adsorption and desorption of vibrationally excited molecules on a metal surface

    Science.gov (United States)

    Shirhatti, Pranav R.; Rahinov, Igor; Golibrzuch, Kai; Werdecker, Jörn; Geweke, Jan; Altschäffel, Jan; Kumar, Sumit; Auerbach, Daniel J.; Bartels, Christof; Wodtke, Alec M.

    2018-06-01

    The most common mechanism of catalytic surface chemistry is that of Langmuir and Hinshelwood (LH). In the LH mechanism, reactants adsorb, become thermalized with the surface, and subsequently react. The measured vibrational (relaxation) lifetimes of molecules adsorbed at metal surfaces are in the range of a few picoseconds. As a consequence, vibrational promotion of LH chemistry is rarely observed, with the exception of LH reactions occurring via a molecular physisorbed intermediate. Here, we directly detect adsorption and subsequent desorption of vibrationally excited CO molecules from a Au(111) surface. Our results show that CO (v = 1) survives on a Au(111) surface for 1 × 10-10 s. Such long vibrational lifetimes for adsorbates on metal surfaces are unexpected and pose an interesting challenge to the current understanding of vibrational energy dissipation on metal surfaces. They also suggest that vibrational promotion of surface chemistry might be more common than is generally believed.

  14. Surface Termination of the Metal-Organic Framework HKUST-1: A Theoretical Investigation.

    Science.gov (United States)

    Amirjalayer, Saeed; Tafipolsky, Maxim; Schmid, Rochus

    2014-09-18

    The surface morphology and termination of metal-organic frameworks (MOF) is of critical importance in many applications, but the surface properties of these soft materials are conceptually different from those of other materials like metal or oxide surfaces. Up to now, experimental investigations are scarce and theoretical simulations have focused on the bulk properties. The possible surface structure of the archetypal MOF HKUST-1 is investigated by a first-principles derived force field in combination with DFT calculations of model systems. The computed surface energies correctly predict the [111] surface to be most stable and allow us to obtain an unprecedented atomistic picture of the surface termination. Entropic factors are identified to determine the preferred surface termination and to be the driving force for the MOF growth. On the basis of this, reported strategies like employing "modulators" during the synthesis to tailor the crystal morphology are discussed.

  15. Roll-to-Roll Manufacturing of Robust Superhydrophobic Coating on Metallic Engineering Materials.

    Science.gov (United States)

    Dong, Shuliang; Wang, Zhenlong; Wang, Yukui; Bai, Xuelin; Fu, Yong Qing; Guo, Bin; Tan, Chaoliang; Zhang, Jia; Hu, PingAn

    2018-01-17

    Creating a robust superhydrophobic surface on the conventional engineering materials at mass production is of great importance for a self-cleaning, anti-icing, nonwetting surface and low flow resistance in industrial applications. Herein, we report a roll-to-roll strategy to create durable and robust superhydrophobic surfaces with designed micro-/nanoscale hierarchical structures on many conventional engineering materials by combining electrical discharge machining and coating of carbon nanoparticles, followed by oil penetration and drying. The treated surface shows good superhydrophobic properties with a static water contact angle of 170 ± 2° and slide angle of 3 ± 1°. The treated surface also exhibits good resilience and maintains the performance after being tested in various harsh conditions, including water flushing for several days, sand abrasion, scratching with sandpapers, and corrosive solution. Significantly, the superhydrophobic surfaces also show a high efficiency of self-cleaning properties even after oil contamination during applications.

  16. Half-metallic properties of the (1 1 0) surface of alkali earth metal monosilicides in the zinc blende phase

    International Nuclear Information System (INIS)

    Bialek, B; Lee, J I

    2011-01-01

    An all electron ab initio method was employed to study the electronic and magnetic properties of the (1 1 0) surface of alkaline-earth metal silicides: CaSi, SrSi and BaSi, in the zinc blende structure. The three surfaces are found to conserve the half-metallic properties of their bulk structures with a wide semiconducting energy gap in the spin-up channel. Half-metallic energy gap at the surfaces is small. In the CaSi surface it is of the order of k B T, which indicates that in the CaSi (1 1 0) a transition to a metallic state is possible due to temperature fluctuations. At the same time, the CaSi surface exhibits the strongest magnetic properties with 0.91 μ B magnetic moment on the Si atom in the topmost layer and 0.21 μ B magnetic moment on the Ca atom. In each of the three surfaces we observe a reduction of magnetic moments on the atoms in the subsurface layer and the enhancement of the magnetic moment on the atoms in the topmost layer, as compared with the properties of atoms in the bulk. An analysis of the calculated total and atom projected densities of states leads to a conclusion that the surface effects in the structures are short-range phenomena

  17. Chemical bonding of water to metal surfaces studied with core-level spectroscopies

    DEFF Research Database (Denmark)

    Schiros, T.; Andersson, Klas Jerker; Pettersson, L.G.M.

    2010-01-01

    The nature of the contact layer of water on surfaces is of relevance for many practical fields, including corrosion, electrochemistry, environmental science and heterogeneous catalysis. Here we focus on the geometric and electronic structure of the water contact layer on transition metal surfaces......-specific information on the partial local density of states, local atomic structure, geometrical parameters and molecular orientation, allowing general principles for water-metal interaction to be derived....

  18. Determination of wear metals in engine oil by PIXE and RBS technique

    Energy Technology Data Exchange (ETDEWEB)

    Alkofahi, M M [Physics Dept., Yarmouk university, Irbid, (Jordan)

    1995-10-01

    The constituents of fresh and used engine oil were determined by PIXE and RBS techniques using 2 MeV He{sup ++} ion beams. The concentration of generated wear metals in used engine oil was measured as a function of running kilometers. The fresh oil was found to contain the elements: Si, P, S, Cl, K, Ca, and Fe. In addition to theses elements, Pb and Br were found in the used oil. Changes in the concentrations of S, Zn and Br were noticed as the running kilometers increased. 6 figs., 2 tabs.

  19. Effects of Surface Alloying and Laser Beam Treatment on the Microstructure and Wear Behaviour of Surfaces Modified Using Submerged Metal Arc Welding

    Directory of Open Access Journals (Sweden)

    Regita BENDIKIENE

    2016-05-01

    Full Text Available In this study, the effects of surface alloying of cheap plain carbon steel using submerged metal arc technique and subsequent laser beam treatment on the microstructure and wear behaviour of surfaced layers were studied. This method is the cheapest one to obtain high alloyed coatings, because there is no need to apply complex technologies of powder making (metal powder is spread on the surface of base metal or inserted into the flux, it is enough to grind, granulate and blend additional materials. On the other hand, strengthening of superficial layers of alloys by thermal laser radiation is one of the applications of laser. Surface is strengthened by concentrated laser beam focused into teeny area (from section of mm till some mm. Teeny area of metal heat up rapidly and when heat is drain to the inner metal layers giving strengthening effect. Steel surface during this treatment exceeds critical temperatures, if there is a need to strengthen deeper portions of the base metal it is possible even to fuse superficial layer. The results presented in this paper are based on micro-structural and micro-chemical analyses of the surfaced and laser beam treated surfaces and are supported by analyses of the hardness, the wear resistance and resultant microstructures. Due to the usage of waste raw materials a significant improvement (~ 30 % in wear resistance was achieved. The maximum achieved hardness of surfaced layer was 62 HRC, it can be compared with high alloyed conventional steel grade. Wear properties of overlays with additional laser beam treatment showed that weight loss of these layers was ~10 % lower compared with overlays after welding; consequently it is possible to replace high alloyed conventional steel grades forming new surfaces or restoring worn machine elements and tools.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7621

  20. Photoelectric work function measurement of a cesiated metal surface and its correlation with the surface-produced H- ion flux

    International Nuclear Information System (INIS)

    Wada, M.; Berkner, K.H.; Pyle, R.V.; Stearns, J.W.

    1982-09-01

    For application in plasma heating, fueling, and current drive of magnetic fusion devices, high current negative deuterium ion sources for intense neutral beam injectors are being developed using efficient production of negative hydrogen isotope ions on low work function metal surfaces imbedded in hydrogen plasmas. In order to investigate the correlation between work function and negative hydrogen ion production, photoelectron emission from a cesiated metal surface, which is immersed in a hydrogen plasma with an electron density less than 5 x 10 10 /cc, was measured in the photon energy range of 1.3 to 4.1 eV. The work function determination was based on Fowler's analysis, and at the optimum coverage a work function of less than 1.5 eV was observed for a Cs-Cu surface. Measured values of work functions for different Cs coverages were compared to the negative hydrogen currents produced at the metal surface in the discharge; the surface production of negative hydrogen ion current is monotonically increasing with decreasing work function

  1. The Impact of Road Maintenance Substances on Metals Surface Corrosion

    OpenAIRE

    Jolita Petkuvienė; Dainius Paliulis

    2011-01-01

    The purpose of research is to assess changes in the visual metal surface due to the exposure of road maintenance salts and molasses (‘Safecote’). Chlorides of deicing salts (NaCl, CaCl2) are the main agents affecting soil and water resources as well as causing the corrosion of roadside metallic elements. Molasses (‘Safecote’) is offered as an alternative to deice road pavement by minimizing the corrosion of metal elements near the road. A laboratory experiment was carried out to immerse and s...

  2. Study on the surface oxidation resistance of uranium metal in the atmosphere of carbon monoxide

    International Nuclear Information System (INIS)

    Wang Xiaolin; Fu Yibei; Xie Renshou

    1999-01-01

    The surface reactions of different layers on uranium metal with carbon monoxide at 25, 80 and 200 degree C are studied by X-ray photoelectron spectroscopy (XPS). The experimental results show that the carbon monoxide is adsorbed on the surface oxide layer of uranium and interacted each other. The content of oxygen in the surface oxide and O/U ratio are decreased with increasing the exposure of carbon monoxide to the surface layer. The effect of reduction on the metal surface is more obviously with a higher temperature and increasing of layer thickness. The investigation indicates the uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide

  3. Radiative decay engineering: the role of photonic mode density in biotechnology

    International Nuclear Information System (INIS)

    Lakowicz, Joseph R; Malicka, Joanna; Gryczynski, Ignacy; Gryczynski, Zygmunt; Geddes, Chris D

    2003-01-01

    Fluorescence detection is a central technology in biological research and biotechnology. A vast array of fluorescent probes are available with diverse spectral properties. These properties were 'engineered' into fluorophores by modification of the chemical structures. Essentially, all present uses of fluorescence rely on the radiation of energy into optically transparent media, the free space which surrounds the fluorophores. In this paper, we summarize an opportunity for novel fluorescence technology based on modification of the photonic mode density around the fluorophore and thus control of its spectral properties. This modification can be accomplished by proximity of fluorophores to metallic particles of gold, silver and possibly others. By engineering the size and shape of the metal particles, and the location of the fluorophores relative to the surfaces, fluorophores can be quenched, display increases in quantum yield, and changes in lifetime. Fluorophore-metal surface combinations can even display directional rather than isotropic emission. We describe recent experimental results and suggest potential biomedical applications of fluorophore-metal particle interactions. (topical review)

  4. Bulk-surface relationship of an electronic structure for high-throughput screening of metal oxide catalysts

    International Nuclear Information System (INIS)

    Kweun, Joshua Minwoo; Li, Chenzhe; Zheng, Yongping; Cho, Maenghyo; Kim, Yoon Young; Cho, Kyeongjae

    2016-01-01

    Graphical abstract: - Highlights: • Bulk-surface relationship was predicted by the ligand field nature of metal oxides. • Antibonding and bonding d-bands occupancy clarified the bulk-surface relationship. • Different surface relaxations were explained by the bulk electronic structures. • Transition from the bulk to the surface state was simulated by oxygen adsorption. - Abstract: Designing metal-oxides consisting of earth-abundant elements has been a crucial issue to replace precious metal catalysts. To achieve efficient screening of metal-oxide catalysts via bulk descriptors rather than surface descriptors, we investigated the relationship between the electronic structure of bulk and that of the surface for lanthanum-based perovskite oxides, LaMO_3 (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu). Through density functional theory calculations, we examined the d-band occupancy of the bulk and surface transition-metal atoms (n_B_u_l_k and n_S_u_r_f) and the adsorption energy of an oxygen atom (E_a_d_s) on (001), (110), and (111) surfaces. For the (001) surface, we observed strong correlation between the n_B_u_l_k and n_S_u_r_f with an R-squared value over 94%, and the result was interpreted in terms of ligand field splitting and antibonding/bonding level splitting. Moreover, the E_a_d_s on the surfaces was highly correlated with the n_B_u_l_k with an R-squared value of more than 94%, and different surface relaxations could be explained by the bulk electronic structure (e.g., LaMnO_3 vs. LaTiO_3). These results suggest that a bulk-derived descriptor such as n_B_u_l_k can be used to screen metal-oxide catalysts.

  5. Recent advances in engineering topography mediated antibacterial surfaces

    Science.gov (United States)

    Hasan, Jafar; Chatterjee, Kaushik

    2015-09-01

    The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria-material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces.

  6. Electronic structure and dynamics of metal and metal-covered surfaces

    International Nuclear Information System (INIS)

    Yang, Shu.

    1992-01-01

    The unoccupied electronic states of;Ni(111) and Al(111) have been studied using angle-resolved inverse-photoemission (IPE) spectroscopy. We have characterized the n = 1 image potential state on Ni(111) measuring an effective mass of m * /m = 1, consistent with recent two-photon photoemission results as well as theoretical calculations using a phase-analysis model, but differing considerably from the earlier angle-resolved IPE measurements. The bulk related features on Ni(111) observed in our experiment agree very well with an empirical Ni band structure calculation. On Al(111), we have conducted an extensive study of the image potential resonance using both angle-resolved IPE spectroscopy and tunneling spectroscopy with the scanning tunneling microscope. We have used Al as a testing case for both nearly-free-electron model and first-principles calculations were needed to obtain a semi-quantitative account of the bulk features of Al, a simple metal. Improved quantitative agreement occurred when excitation effects were considered. In addition, several surface resonance features have been identified and characterized on Al(111). We have also conducted a geometric structural investigation of a metal overlayer system, Ni/Cu(111), using high-resolution electron energy loss spectroscopy with CO as a probe molecule. The results indicate island formation and two-dimensional mixing at the initial stage of bimetallic interface formation. A new adsorption site with CO bonded to both Ni and Cu has been discovered on the Ni-Cu intermixed surface. IPE results for the Cu-covered Ni(111) surface show an enhanced angular range for the Cu image state. Finally, the unique ability of Auger-photoelectron coincidence spectroscopy to probing local valence electronic structure has been tested in a case study of TaC(111). A novel Auger decay channel has also been observed

  7. Corrosion of metallic materials. Dry corrosion, aqueous corrosion and corrosion by liquid metal, methods of protection

    International Nuclear Information System (INIS)

    Helie, Max

    2015-01-01

    This book is based on a course on materials given in an engineering school. The author first gives an overview of metallurgy issues: metallic materials (pure metals, metallic alloys), defects of crystal lattices (point defects, linear defects or dislocations), equilibrium diagrams, steels and cast, thermal processing of steels, stainless steels, aluminium and its alloys, copper and its alloys. The second part addresses the properties and characterization of surfaces and interfaces: singularity of a metal surface, surface energy of a metal, energy of grain boundaries, adsorption at a material surface, metal-electrolyte interface, surface oxide-electrolyte interface, techniques of surface analysis. The third chapter addresses the electrochemical aspects of corrosion: description of the corrosion phenomenon, free enthalpy of a compound and free enthalpy of a reaction, case of dry corrosion (thermodynamic aspect, Ellingham diagram, oxidation mechanisms, experimental study, macroscopic modelling), case of aqueous corrosion (electrochemical thermodynamics and kinetics, experimental determination of corrosion rate). The fourth part addresses the different forms of aqueous corrosion: generalized corrosion (atmospheric corrosion, mechanisms and tests), localized corrosion (galvanic, pitting, cracking, intergranular, erosion and cavitation), particular cases of stress cracking (stress corrosion, fatigue-corrosion, embrittlement by hydrogen), and bi-corrosion (of non alloyed steels, of stainless steels, and of aluminium and copper alloys). The sixth chapter addresses the struggle and the protection against aqueous corrosion: methods of prevention, scope of use of main alloys, geometry-based protection of pieces, use of corrosion inhibitors, use of organic or metallic coatings, electrochemical protection. The last chapter proposes an overview of corrosion types in industrial practices: in the automotive industry, in the oil industry, in the aircraft industry, and in the

  8. Mechanical Engineering Department engineering research: Annual report, FY 1986

    International Nuclear Information System (INIS)

    Denney, R.M.; Essary, K.L.; Genin, M.S.; Highstone, H.H.; Hymer, J.D.; Taft, S.O.

    1986-12-01

    This report provides information on the five areas of research interest in LLNL's Mechanical Engineering Department. In Computer Code Development, a solid geometric modeling program is described. In Dynamic Systems and Control, structure control and structure dynamics are discussed. Fabrication technology involves machine cutting, interferometry, and automated optical component manufacturing. Materials engineering reports on composite material research and measurement of molten metal surface properties. In Nondestructive Evaluation, NMR, CAT, and ultrasound machines are applied to manufacturing processes. A model for underground collapse is developed. Finally, an alternative heat exchanger is investigated for use in a fusion power plant. Separate abstracts were prepared for each of the 13 reports in this publication

  9. Modification of metallic surfaces by positive ion bombardment

    International Nuclear Information System (INIS)

    Rickards C, J.

    1989-01-01

    Reported are the fundamentals and recent advances in the use of ion implantation techniques and gaseous emissions to modify metal surfaces. The physical phenomena involved, the necessary equipment and some applications which have been successful on an industrial scale are described. (Author). 13 refs, 1 fig

  10. Polishing Metal Mirrors to 0,025 Micron Surface Finish

    DEFF Research Database (Denmark)

    Pedersen, P. E.

    1978-01-01

    A research program undertaken by the Danish Atomic Energy Commission required the fabrication of metal mirrors measuring 1 m long by 53 mm wide, which had to be finished to extremely tight tolerances on thickness, plane-parallelism and surface characteristics. Progressively finer diamond compound...... are employed to achieve a high gloss finish on the metal mirrors, which are used in polarized neutron experiments. This article describes the fabrication techniques developed at the Commission's Ris phi Central Workshop....

  11. Engineered Metallic Nanostructures: Fabrication, Characterization, and Applications

    Science.gov (United States)

    Bohloul, Arash

    Metallic nanostructures have garnered a great deal of attention due to their fascinating optical properties, which differ from the bulk metal. They have been proven to exceed expectations in wide variety of applications including chemical and biological sensing. Nevertheless, high-throughput and low cost nanofabrication techniques are required to implant metallic nanostructures in widespread applications. With that vision, this thesis presents a versatile and reliable method for scalable fabrication of gold nanostructures. In this approach, a plasma-treated ordered array of polystyrene nanospheres acts as an initial mask. The key step in this process is the vapor-deposition of nickel as a sacrificial mask. Thereby, gold nanostructures are directly formed on the substrate through the nickel mask. This is an easy, powerful, and straightforward method that offers several degrees of freedom to precisely control the shape and size of nanostructures. We made a library of nanostructures including gold nanocrescents, double crescents, nanorings, and nanodisks with the ability to tune the size in the range of 150 to 650 nm. The fabricated nanostructures are highly packed and uniformly cover the centimeter scale substrate. The optical properties of metallic nanostructures were extensively studied by a combination of UV-Vis-NIR and Fourier transform infrared (FTIR) spectroscopies, and correlation between optical response and geometrical parameters were investigated. In the next part of this thesis, highly sensitive surface enhanced infrared absorption (SEIRA) analysis was demonstrated on gold nanocrescent arrays. Theoretical modeling was confirmed that these substrates provide highly dense and strong hot-spots over the substrate, which is required for surface enhanced spectroscopic studies. Gold nanocrescent arrays exhibit highly tunable plasmon resonance to cover desired molecular vibrational bands. These substrates experimentally illustrated 3 orders of magnitude

  12. Analysis of Terminal Metallic Armor Plate Free-Surface Bulging

    National Research Council Canada - National Science Library

    Rapacki, Jr, E. J

    2008-01-01

    An analysis of the bulge formed on the free-surface of the terminal metallic plate of an armor array is shown to lead to reasonable estimates of the armor array's remaining penetration/perforation resistance...

  13. Design of microreactor by integration of reverse engineering and direct metal laser sintering process

    Energy Technology Data Exchange (ETDEWEB)

    Bineli, Aulus Roberto Romao; Gimenez Perez, Ana Paula; Bernardes, Luiz Fernando; Munhoz, Andre Luiz Jardini; Maciel Filho, Rubens [Universidade de Campinas (LOPCA/UNICAMP), SP (Brazil). School of Chemical Engineering. Laboratory of Optimization, Design and Advanced Process Control], Email: aulus@feq.unicamp.br

    2010-07-01

    The propose of this work is to present high precision microfabrication facilities using computer aided technologies as Reverse Engineering (RE) and Rapid Manufacturing (RM) to analyze, design and construct micro reactors to produce high content hydrogen gas. Micro reactors are very compact, have a high surface to volume ratio, exhibit enhanced heat and mass transfer rates, denotes extremely low pressure drop and allow improved thermal integration in the processes involved. The main goals of micro reactors are the optimization of conventional chemical plants and low footprint, opening different ways to research new process technologies and synthesis of new products. In this work, a microchannels plate and housing structure of these plates were fabricated using DMLS method (Direct Metal Laser Sintering). The plates were analyzed to verify the minimum thickness wall that machine can produce, and the housing structure were digitalized, using a 3D scanning, to perform a 3D inspection and to verify the deflection of the constructed part in comparison with original CAD design models. It was observed that DMLS systems are able to produce micro reactors and microchannels plates with high precision at different metallic materials. However, it is important to choose appropriate conditions to avoid residual stresses and consequently warping parts. (author)

  14. Surface treatments of metal supports for photocatalysis applications

    Energy Technology Data Exchange (ETDEWEB)

    Montecchio, Francesco, E-mail: fmon@kth.se [KTH, Royal Institute of Technology, Dept. of Chemical Engineering and Technology, 100 44 Stockholm (Sweden); Chinungi, Don [KTH, Royal Institute of Technology, Dept. of Chemical Engineering and Technology, 100 44 Stockholm (Sweden); Lanza, Roberto [Verdant Chemical Technologies AB, 114 28 Stockholm (Sweden); Engvall, Klas [KTH, Royal Institute of Technology, Dept. of Chemical Engineering and Technology, 100 44 Stockholm (Sweden)

    2017-04-15

    Highlights: • Treated metals can be used as photocatalyst support in full-scale applications. • Various electrochemical treatments were performed, checking the surface corrugation. • Stainless steel etched in DC and aqua regia shows the highest surface modification. • P25 coated on the DC etched sample has a high stability, with constant activity. • The support modification increases the UV irradiated area and the activity of P25. - Abstract: One of the most important challenges, for scaling up a photocatalytic system for VOCs abatement to full-scale, is the design of a suitable photocatalyst support. The support has to firmly immobilize the photocatalyst, without using an organic adhesive, and should also withstand relatively high mechanical stresses. Metals may be effectively implemented as a support material, after a corrugation of the surface with electrochemical treatments. In the present work, we treated stainless steel and aluminum supports, evaluating the surface modifications due to the electrochemical treatments, with scanning electron microscopy (SEM) and confocal microscopy. Five samples showing the highest degree of restructuring were selected and spray coated with P25, a TiO{sub 2} photocatalyst, evaluating the mechanical stability of the coating with a standard tape test method. One particular stainless steel sample presented a superior surface restructuring and coating stability. The photocatalytic activity of this sample, evaluated measuring the complete oxidation of acetaldehyde, was tested for 15 h, and compared with sample of TiO{sub 2}-P25 on a ceramic support. The stainless steel exhibited a constant performance after an initial stabilization period. The stainless steel sample showed a slightly higher activity, due to the surface restructuring, increasing the irradiated area available for the coated photocatalyst.

  15. Study of surface modifications for improved selected metal (II-VI) semiconductor based devices

    Science.gov (United States)

    Blomfield, Christopher James

    Metal-semiconductor contacts are of fundamental importance to the operation of all semiconductor devices. There are many competing theories of Schottky barrier formation but as yet no quantitative predictive model exists to adequately explain metal-semiconductor interfaces. The II-VI compound semiconductors CdTe, CdS and ZnSe have recently come to the fore with the advent of high efficiency photovoltaic cells and short wavelength light emitters. Major problems still exist however in forming metal contacts to these materials with the desired properties. This work presents results which make a significant contribution to the theory of metal/II-VI interface behaviour in terms of Schottky barriers to n-type CdTe, CdS and ZnSe.Predominantly aqueous based wet chemical etchants were applied to the surfaces of CdTe, CdS and ZnSe which were subsequently characterised by X-ray photoelectron spectroscopy. The ionic nature of these II-VI compounds meant that they behaved as insoluble salts of strong bases and weak acids. Acid etchants induced a stoichiometric excess of semiconductor anion at the surface which appeared to be predominantly in the elemental or hydrogenated state. Alkaline etchants conversely induced a stoichiometric excess of semiconductor cation at the surface which appeared to be in an oxidised state.Metal contacts were vacuum-evaporated onto these etched surfaces and characterised by current-voltage and capacitance-voltage techniques. The surface preparation was found to have a clear influence upon the electrical properties of Schottky barriers formed to etched surfaces. Reducing the native surface oxide produced near ideal Schottky diodes. An extended study of Au, Ag and Sb contacts to [mathematical formula] substrates again revealed the formation of several discrete Schottky barriers largely independent of the metal used; for [mathematical formula]. Deep levels measured within this study and those reported in the literature led to the conclusion that Fermi

  16. Cytocompatible in situ forming chitosan/hyaluronan hydrogels via a metal-free click chemistry for soft tissue engineering.

    Science.gov (United States)

    Fan, Ming; Ma, Ye; Mao, Jiahui; Zhang, Ziwei; Tan, Huaping

    2015-07-01

    Injectable hydrogels are important cell scaffolding materials for tissue engineering and regenerative medicine. Here, we report a new class of biocompatible and biodegradable polysaccharide hydrogels derived from chitosan and hyaluronan via a metal-free click chemistry, without the addition of copper catalyst. For the metal-free click reaction, chitosan and hyaluronan were modified with oxanorbornadiene (OB) and 11-azido-3,6,9-trioxaundecan-1-amine (AA), respectively. The gelation is attributed to the triazole ring formation between OB and azido groups of polysaccharide derivatives. The molecular structures were verified by FT-IR spectroscopy and elemental analysis, giving substitution degrees of 58% and 47% for chitosan-OB and hyaluronan-AA, respectively. The in vitro gelation, morphologies, equilibrium swelling, compressive modulus and degradation of the composite hydrogels were examined. The potential of the metal-free hydrogel as a cell scaffold was demonstrated by encapsulation of human adipose-derived stem cells (ASCs) within the gel matrix in vitro. Cell culture showed that this metal-free hydrogel could support survival and proliferation of ASCs. A preliminary in vivo study demonstrated the usefulness of the hydrogel as an injectable scaffold for adipose tissue engineering. These characteristics provide a potential opportunity to use the metal-free click chemistry in preparation of biocompatible hydrogels for soft tissue engineering applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Graphene on metal surfaces and its hydrogen adsorption

    DEFF Research Database (Denmark)

    Andersen, Mie; Hornekær, L.; Hammer, B.

    2012-01-01

    The interaction of graphene with various metal surfaces is investigated using density functional theory and the meta-generalized gradient approximation (MGGA) M06-L functional. We demonstrate that this method is of comparable accuracy to the random-phase approximation (RPA). With M06-L we study...... large systems inaccessible to RPA with H adsorbed on graphene on a selected strongly (Ni) and a selected weakly (Pt) interacting substrate. Very stable graphane-like clusters, where every other C atom binds to a H atom above and every other to a metal atom below, are found on both substrates...

  18. Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces

    NARCIS (Netherlands)

    Schmage, P; Nergiz, [No Value; Herrmann, W; Ozcan, M; Nergiz, Ibrahim; �zcan, Mutlu

    With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface

  19. Low temperature formation of electrode having electrically conductive metal oxide surface

    Science.gov (United States)

    Anders, Simone; Anders, Andre; Brown, Ian G.; McLarnon, Frank R.; Kong, Fanping

    1998-01-01

    A low temperature process is disclosed for forming metal suboxides on substrates by cathodic arc deposition by either controlling the pressure of the oxygen present in the deposition chamber, or by controlling the density of the metal flux, or by a combination of such adjustments, to thereby control the ratio of oxide to metal in the deposited metal suboxide coating. The density of the metal flux may, in turn, be adjusted by controlling the discharge current of the arc, by adjusting the pulse length (duration of on cycle) of the arc, and by adjusting the frequency of the arc, or any combination of these parameters. In a preferred embodiment, a low temperature process is disclosed for forming an electrically conductive metal suboxide, such as, for example, an electrically conductive suboxide of titanium, on an electrode surface, such as the surface of a nickel oxide electrode, by such cathodic arc deposition and control of the deposition parameters. In the preferred embodiment, the process results in a titanium suboxide-coated nickel oxide electrode exhibiting reduced parasitic evolution of oxygen during charging of a cell made using such an electrode as the positive electrode, as well as exhibiting high oxygen overpotential, resulting in suppression of oxygen evolution at the electrode at full charge of the cell.

  20. Engineering MerR for Sequestration and MerA for Reduction of Toxic Metals and Radionuclides

    International Nuclear Information System (INIS)

    Summers, Anne O.

    2008-01-01

    The objectives of this project were (1) to alter a metalloregulatory protein (MerR) so that it would bind other toxic metals or radionuclides with similar affinity so that the engineered protein itself and/or bacteria expressing it could be deployed in the environment to specifically sequester such metals and (2) to alter the mercuric reductase, MerA, to reduce radionuclides and render them less mobile. Both projects had a basic science component. In the first case, such information about MerR illuminates how proteins discriminate very similar metals/elements. In the second case, information about MerA reveals the criteria for transmission of reducing equivalents from NADPH to redox-active metals. The work involved genetic engineering of all or parts of both proteins and examination of their resultant properties both in vivo and in vitro, the latter with biochemical and biophysical tools including equilibrium and non-equilibrium dialysis, XAFS, NMR, x-ray crystallography, and titration calorimetry. We defined the basis for metal specificity in MerR, devised a bacterial strain that sequesters Hg while growing, characterized gold reduction by MerA and the role of the metallochaperone domain of MerA, and determined the 3-D structure of MerB, the organomercurial lyase.

  1. Modeling surface roughness scattering in metallic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Moors, Kristof, E-mail: kristof@itf.fys.kuleuven.be [KU Leuven, Institute for Theoretical Physics, Celestijnenlaan 200D, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Sorée, Bart [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); KU Leuven, Electrical Engineering (ESAT) Department, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Magnus, Wim [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2015-09-28

    Ando's model provides a rigorous quantum-mechanical framework for electron-surface roughness scattering, based on the detailed roughness structure. We apply this method to metallic nanowires and improve the model introducing surface roughness distribution functions on a finite domain with analytical expressions for the average surface roughness matrix elements. This approach is valid for any roughness size and extends beyond the commonly used Prange-Nee approximation. The resistivity scaling is obtained from the self-consistent relaxation time solution of the Boltzmann transport equation and is compared to Prange-Nee's approach and other known methods. The results show that a substantial drop in resistivity can be obtained for certain diameters by achieving a large momentum gap between Fermi level states with positive and negative momentum in the transport direction.

  2. FDTD/TDSE study of surface-enhanced infrared absorption by metal nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Chang, S.-H.; Schatz, G. C.; Gray, S. K.; Chemistry; Northwestern Univ.; National Cheng-Kung Univ.

    2006-01-01

    We study surface-enhanced infrared absorption, including multiphoton processes, due to the excitation of surface plasmons on metal nanoparticles. The time-dependent Schroedinger equation and finite-difference time-domain method are self-consistently coupled to treat the problem.

  3. First-principles study on half-metallic zinc-blende CrS and its (001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Bin, E-mail: hnsqxb@163.com [Department of Mathematics and Information Sciences, North China university of Water Resources and Electric Power, Zhengzhou 450011 (China); Chen, Leiming [Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou, 450015 (China)

    2016-11-01

    Half-metallic magnets with complete (100%) spin polarization have attracted growing interest due to the potential in spintronic applications. In this paper, we use the first-principles calculations to explain the seeming contradiction between the recent experimental ferromagnetism (Demper et al., 2012 [22]) and the previous theoretical antiferromagnetic ground state for half-metallic zinc-blende CrS, and the experimental ferromagnetism of zinc-blende CrS arises from the substrate effect. We also show that both Cr- and S-terminated (001) surfaces of CrS preserve the bulk half-metallicity. The calculated surface energy indicates that the S-terminated (001) surface is more stable than the Cr-terminated (001) surface within the whole effective Cr chemical potentials, and thus the S-terminated (001) surface is more likely than the Cr-terminated (001) surface when the CrS thin films are grown on ZnSe substrate.

  4. Adsorption on metal surfaces: Final report

    International Nuclear Information System (INIS)

    Einstein, T.L.; Glover, R.E. III; Park, R.L.

    1987-01-01

    This report discusses the progress at the University of Maryland Department of Physics on the adsorption of atoms or molecules on the surfaces of metals. Also discussed are: Phase transformation studies; the use of transfer matrices to study the 2-d, 3-state chiral Potts model; electron-induced ionization of core electrons of atoms; the reflected electron energy loss fine structure above the M/sub 2,3/ core excitation edge of Cu; and other research in atomic and solid state physics

  5. Selective metallization of polymers using laser induced surface activation (LISA)—characterization and optimization of porous surface topography

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; De Grave, Arnaud

    2011-01-01

    Laser induced selective activation (LISA) is a molded interconnected devices technique for selective metallization of polymers. On the working piece, only the laser-machined area can be metalized in the subsequent plating. The principle of the technology is introduced. Surface analysis was perfor...

  6. Simultaneous surface engineering and bulk hardening of precipitation hardening stainless steel

    DEFF Research Database (Denmark)

    Frandsen, Rasmus Berg; Christiansen, Thomas; Somers, Marcel A. J.

    2006-01-01

    This article addresses simultaneous bulk precipitation hardening and low temperature surface engineering of two commercial precipitation hardening stainless steels: Sandvik Nanoflex® and Uddeholm Corrax®. Surface engineering comprised gaseous nitriding or gaseous carburising. Microstructural....... The duration and temperature of the nitriding/carburising surface hardening treatment can be chosen in agreement with the thermal treatment for obtaining optimal bulk hardness in the precipitation hardening stainless steel....... characterisation of the cases developed included X-ray diffraction analysis, reflected light microscopy and micro-hardness testing. It was found that the incorporation of nitrogen or carbon resulted in a hardened case consisting of a combination of (tetragonal) martensite and expanded (cubic) austenite...

  7. Worker exposures from recycling surface contaminated radioactive scrap metal

    International Nuclear Information System (INIS)

    Kluk, A.; Phillips, J.W.; Culp, J.

    1996-01-01

    Current DOE policy permits release from DOE control of real property with residual levels of surficial radioactive contamination if the contamination is below approved guidelines. If the material contains contamination that is evenly distributed throughout its volume (referred to as volumetric contamination), then Departmental approval for release must be obtained in advance. Several DOE sites presently recycle surface contaminated metal, although the quantities are small relative to the quantities of metal processed by typical mini-mills, hence the potential radiation exposures to mill workers from processing DOE metals and the public from the processed metal are at present also a very small fraction of their potential value. The exposures calculated in this analysis are based on 100% of the scrap metal being processed at the maximum contamination levels and are therefore assumed to be maximum values and not likely to occur in actual practice. This paper examines the relationship between the surface contamination limits established under DOE Order 5400.5, open-quotes Radiation Protection of the Public and the Environment,close quotes and radiation exposures to workers involved in the scrap metal recycling process. The analysis is limited to surficial contamination at or below the guideline levels established in DOE Order 5400.5 at the time of release. Workers involved in the melting and subsequent fabrication of products are not considered radiation workers (no requirements for monitoring) and must be considered members of the public. The majority of the exposures calculated in this analysis range from tenths of a millirem per year (mrem/yr) to less than 5 mrem/yr. The incremental risk of cancer associated with these exposures ranges from 10 -8 cancers per year to 10 -6 cancers per year

  8. Structural coloration of metallic surfaces with micro/nano-structures induced by elliptical vibration texturing

    Science.gov (United States)

    Yang, Yang; Pan, Yayue; Guo, Ping

    2017-04-01

    Creating orderly periodic micro/nano-structures on metallic surfaces, or structural coloration, for control of surface apparent color and optical reflectivity has been an exciting research topic over the years. The direct applications of structural coloration include color marking, display devices, and invisibility cloak. This paper presents an efficient method to colorize metallic surfaces with periodic micro/nano-gratings using elliptical vibration texturing. When the tool vibration is coupled with a constant cutting velocity, controlled periodic ripples can be generated due to the overlapping tool trajectory. These periodic ripples with a wavelength near visible spectrum can act as micro-gratings to introduce iridescent colors. The proposed technique also provides a flexible method for color marking of metallic surfaces with arbitrary patterns and images by precise control of the spacing distance and orientation of induced micro/nano-ripples. Theoretical analysis and experimental results are given to demonstrate structural coloration of metals by a direct mechanical machining technique.

  9. Thermal Diffusion Processes in Metal-Tip-Surface Interactions: Contact Formation and Adatom Mobility

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Jacobsen, Karsten Wedel; Jonsson, Hannes

    1996-01-01

    and the surface can occur by a sequence of atomic hop and exchange processes which become active on a millisecond time scale when the tip is about 3-5 Angstrom from the surface. Adatoms on the surface are stabilized by the presence of the tip and energy barriers for diffusion processes in the region under the tip......We have carried out computer simulations to identify and characterize various thermally activated atomic scale processes that can play an important role in room temperature experiments where a metal tip is brought close to a metal surface. We find that contact formation between the tip...

  10. A calculation of the surface recombination rate constant for hydrogen isotopes on metals

    International Nuclear Information System (INIS)

    Baskes, M.J.

    1980-01-01

    The surface recombination rate constant for hydrogen isotopes on a metal has been calculated using a simple model whose parameters may be determined by direct experimental measurements. Using the experimental values for hydrogen diffusivity, solubility, and sticking coefficient at zero surface coverage a reasonable prediction of the surface recombination constant may be made. The calculated recombination constant is in excellent agreement with experiment for bcc iron. A heuristic argument is developed which, along with the rate constant calculation, shows that surface recombination is important in those metals in which hydrogen has an exothermic heat of solution. (orig.)

  11. Surface electromyography physiology, engineering and applications

    CERN Document Server

    Farina, Dario

    2016-01-01

    The book presents a quantitative approach to the study and use of noninvasively detected electromyographic (EMG) signals, as well as their numerous applications in various aspects of the life sciences. Surface Electromyography: Physiology, Engineering, and Applications is an update of Electromyography: Physiology, Engineering, and Noninvasive Applications (Wiley-IEEE Press, 2004) and focuses on the developments that have taken place over the last decade. The first nine chapters deal with the generation, detection, understanding, interpretation, and modeling of EMG signals. Detection technology, with particular focus on EMG imaging techniques that are based on two-dimensional electrode arrays are also included in the first half of the book. The latter 11 chapters deal with applications, which range fro monitoring muscle fatigue, electrically elicited contractions, posture analysis, prevention of work-related and child-delivery-related neuromuscular disorders, ergonomics, movement analysis, physical therapy, ex...

  12. Stability of surface plastic flow in large strain deformation of metals

    Science.gov (United States)

    Viswanathan, Koushik; Udapa, Anirduh; Sagapuram, Dinakar; Mann, James; Chandrasekar, Srinivasan

    We examine large-strain unconstrained simple shear deformation in metals using a model two-dimensional cutting system and high-speed in situ imaging. The nature of the deformation mode is shown to be a function of the initial microstructure state of the metal and the deformation geometry. For annealed metals, which exhibit large ductility and strain hardening capacity, the commonly assumed laminar flow mode is inherently unstable. Instead, the imposed shear is accommodated by a highly rotational flow-sinuous flow-with vortex-like components and large-amplitude folding on the mesoscale. Sinuous flow is triggered by a plastic instability on the material surface ahead of the primary region of shear. On the other hand, when the material is extensively strain-hardened prior to shear, laminar flow again becomes unstable giving way to shear banding. The existence of these flow modes is established by stability analysis of laminar flow. The role of the initial microstructure state in determining the change in stability from laminar to sinuous / shear-banded flows in metals is elucidated. The implications for cutting, forming and wear processes for metals, and to surface plasticity phenomena such as mechanochemical Rehbinder effects are discussed.

  13. Electron emission during multicharged ion-metal surface interactions

    International Nuclear Information System (INIS)

    Zeijlmans van Emmichoven, P.A.; Havener, C.C.; Hughes, I.G.; Overbury, S.H.; Robinson, M.T.; Zehner, D.M.; Meyer, F.W.

    1992-01-01

    The electron emission during multicharged ion-metal surface interactions will be discussed. The interactions lead to the emission of a significant number of electrons. Most of these electrons have energies below 30 eV. For incident ions with innershell vacancies the emission of Auger electrons that fill these vacancies has been found to occur mainly below the surface. We will present recently measured electron energy distributions which will be used to discuss the mechanisms that lead to the emission of Auger and of low-energy electrons

  14. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  15. Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Dapeng [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) surface. Some general conclusions can be drawn as follows. First, Ag, a bulk-crystalline material, initially forms a disordered wetting layer up to 4-5 monolayers on Zr-Ni-Cu-Al metallic glass. Above this coverage, crystalline 3D clusters grow, in parallel with the flatter regions. The cluster density increases with decreasing temperature, indicating that the conditions of island nucleation are far-from-equilibrium. Within a simple model where clusters nucleate whenever two mobile Ag adatoms meet, the temperature-dependence of cluster density yields a (reasonable) upper limit for the value of the Ag diffusion barrier on top of the Ag wetting layer of 0.32 eV. Overall, this prototypical study suggests that it is possible to grow films of a bulk-crystalline metal that adopt the amorphous character of a glassy metal substrate, if film thickness is sufficiently low. Next, the first study of coarsening and decay of bilayer islands has been presented. The system was Ag on NiAl(110) in the temperature range from 185 K to 250 K. The coarsening behavior, has some similarities to that seen in the Ag(110) homoepitaxial system studied by Morgenstern and co-workers. At 185 K and 205 K, coarsening of Ag islands follows a Smoluchowski ripening pathway. At 205 K and 250 K, the terrace diffusion limited Ostwald ripening dominants. The experimental observed temperature for the transition from SR to OR is 205 K. The SR exhibits anisotropic island diffusion and the OR exhibits 1D decay of island

  16. Preparation of surface conductive and highly reflective silvered polyimide films by surface modification and in situ self-metallization technique

    International Nuclear Information System (INIS)

    Wu Zhanpeng; Wu Dezhen; Qi Shengli; Zhang Teng; Jin Riguang

    2005-01-01

    Double surface conductive and reflective flexible silvered polyimide films have been prepared by alkali hydroxylation of polyimide film surface and incorporation of silver ions through subsequent ion exchange. Thermal curing of silver(I) polyamate precursor leads to re-cycloimidization of modified surface with concomitant silver reduction, yielding a reflective and conductive silver surface approaching that of native metal. The reflective and conductive surface evolves only when the cure temperature rises to 300 deg. C. The metallized films usually retain the essential mechanical properties of the parent films. Films were characterized by transmission electron microscopy (TEM), scanning electron microscopy and tapping mode atomic force microscopy (AFM). AFM demonstrates that the diameter of close-packed silver particles of the silver layers was about 50-150 nm. TEM shows that thickness of silver layer on the polyimide film surface is about 400-600 nm

  17. Understanding interaction of curcumin and metal ions on electrode surfaces using EDXRF

    Science.gov (United States)

    Joseph, Daisy; Kumar, K. Krishna; Narayanan, S. Sriman

    2018-04-01

    A chemically modified electrode was developed for determination of metal ions (Cd, Pb, Zn, Co, Hg). The modifier used for the study was Curcumin. Curcumin acts as a complexing agent at the surface of the electrode for preconcentration of metal ions from electrolyte to electrode surface and stripped back to electrolyte during analysis. EDXRF was used to analyze these electrodes and it was concluded that the PCR modified electrode favored effective chelation for lead and mercury.

  18. Chemical Engineering of Photoactivity in Heterometallic Titanium-Organic Frameworks by Metal Doping.

    Science.gov (United States)

    Castells-Gil, Javier; Padial, Natalia M; Almora-Barrios, Neyvis; Albero, Josep; Ruiz-Salvador, A Rabdel; González-Platas, Javier; García, Hermenegildo; Martí-Gastaldo, Carlos

    2018-06-06

    We report a new family of titanium-organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi-gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post-synthetic metallation of MOFs, our approach is well-fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band-gap and electronic properties of the porous solid. Changes in the band-gap are also rationalized with computational modelling and experimentally confirmed by photocatalytic H 2 production. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Hydrogen Storage Engineering Center of Excellence Metal Hydride Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Motyka, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-05-31

    The Hydrogen Storage Engineering Center of Excellence (HSECoE) was established in 2009 by the U.S. Department of Energy (DOE) to advance the development of materials-based hydrogen storage systems for hydrogen-fueled light-duty vehicles. The overall objective of the HSECoE is to develop complete, integrated system concepts that utilize reversible metal hydrides, adsorbents, and chemical hydrogen storage materials through the use of advanced engineering concepts and designs that can simultaneously meet or exceed all the DOE targets. This report describes the activities and accomplishments during Phase 1 of the reversible metal hydride portion of the HSECoE, which lasted 30 months from February 2009 to August 2011. A complete list of all the HSECoE partners can be found later in this report but for the reversible metal hydride portion of the HSECoE work the major contributing organizations to this effort were the United Technology Research Center (UTRC), General Motors (GM), Pacific Northwest National Laboratory (PNNL), the National Renewable Energy Laboratory (NREL) and the Savannah River National Laboratory (SRNL). Specific individuals from these and other institutions that supported this effort and the writing of this report are included in the list of contributors and in the acknowledgement sections of this report. The efforts of the HSECoE are organized into three phases each approximately 2 years in duration. In Phase I, comprehensive system engineering analyses and assessments were made of the three classes of storage media that included development of system level transport and thermal models of alternative conceptual storage configurations to permit detailed comparisons against the DOE performance targets for light-duty vehicles. Phase 1 tasks also included identification and technical justifications for candidate storage media and configurations that should be capable of reaching or exceeding the DOE targets. Phase 2 involved bench-level testing and

  20. Radionuclides and trace metals in surface air. Appendix C

    International Nuclear Information System (INIS)

    Feely, H.W.; Toonkel, L.E.; Larsen, R.J.

    1981-01-01

    Since January 1963, the Environmental Measurements Laboratory (EML), formerly the Health and Safety Laboratory (HASL), has been conducting the Surface Air Sampling Program. This study is a direct outgrowth of a program initiated by the US Naval Research Laboratory (NRL) in 1957 and continued through 1962. The primary objective of this program is to study the spatial and temporal distribution of specific natural and man-made radioisotopes, and of trace metals in the surface air. Other special studies of surface air contamination have been performed during the course of the program

  1. Pollution distribution of heavy metals in surface soil at an informal electronic-waste recycling site.

    Science.gov (United States)

    Fujimori, Takashi; Takigami, Hidetaka

    2014-02-01

    We studied distribution of heavy metals [lead (Pb), copper (Cu) and zinc (Zn)] in surface soil at an electronic-waste (e-waste) recycling workshop near Metro Manila in the Philippines to evaluate the pollution size (spot size, small area or the entire workshop), as well as to assess heavy metal transport into the surrounding soil environment. On-site length-of-stride-scale (~70 cm) measurements were performed at each surface soil point using field-portable X-ray fluorescence (FP-XRF). The surface soil at the e-waste recycling workshop was polluted with Cu, Zn and Pb, which were distributed discretely in surface soil. The site was divided into five areas based on the distance from an entrance gate (y-axis) of the e-waste recycling workshop. The three heavy metals showed similar concentration gradients in the y-axis direction. Zn, Pb and Cu concentrations were estimated to decrease to half of their maximum concentrations at ~3, 7 and 7 m from the pollution spot, respectively, inside the informal e-waste recycling workshop. Distance from an entrance may play an important role in heavy metal transport at the soil surface. Using on-site FP-XRF, we evaluated the metal ratio to characterise pollution features of the solid surface. Variability analysis of heavy metals revealed vanishing surficial autocorrelation over metre ranges. Also, the possibility of concentration prediction at unmeasured points using geostatistical kriging was evaluated, and heavy metals had a relative "small" pollution scales and remained inside the original workshop compared with toxic organohalogen compounds. Thus, exposure to heavy metals may directly influence the health of e-waste workers at the original site rather than the surrounding habitat and environmental media.

  2. Facile creation of bio-inspired superhydrophobic Ce-based metallic glass surfaces

    Science.gov (United States)

    Liu, Kesong; Li, Zhou; Wang, Weihua; Jiang, Lei

    2011-12-01

    A bio-inspired synthesis strategy was conducted to fabricate superhydrophobic Ce-based bulk metallic glass (BMG) surfaces with self-cleaning properties. Micro-nanoscale hierarchical structures were first constructed on BMG surfaces and then modified with the low surface energy coating. Surface structures, surface chemical compositions, and wettability were characterized by combining scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and contact angle measurements. Research indicated that both surface multiscale structures and the low surface free energy coating result in the final formation of superhydrophobicity.

  3. Magnetic engineering in 3d transition metals on phosphorene by strain

    International Nuclear Information System (INIS)

    Cai, Xiaolin; Niu, Chunyao; Wang, Jianjun; Yu, Weiyang; Ren, XiaoYan; Zhu, Zhili

    2017-01-01

    Using first-principles density functional theory (DFT) calculations, we systematically investigate the strain effects on the adsorption energies, magnetic ordering and electronic properties of 3d transition metal (TM) atoms (from Sc to Co) adsorbed on phosphorene (P). We find that the adsorption energy of TM can be enhanced by compressive strain whereas weakened by tensile strain. Our results show that strain plays a decisive role in the magnetic moments as well as the magnetic coupling states of TM adatoms. Importantly, the transitions from antiferromagnetic (AFM) state to ferromagnetic (FM) state or to another different AFM ordering can be induced by strain effect. In addition, we observe the semiconductor to metal or half-metal transitions in some TM@P systems by applying strain. Our findings shed a new light on precisely engineering the magnetic properties and electronic properties of the TM@P systems, which will have great potential applications in spin electronics and other related fields. - Highlights: • The adsorption of TM atoms on phosphorene can be enhanced by compressive strain whereas weakened by tensile strain. • Strain plays a decisive role in the magnetic moments as well as the magnetic coupling states of TM adatoms. • Applying strain can induce the semiconductor to metal or half-metal transitions in some TM@P systems.

  4. Magnetic engineering in 3d transition metals on phosphorene by strain

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Xiaolin [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001 (China); School of Physics and Electronic Information Engineering, Henan Polytechnic University, Jiaozuo, 454000 (China); Niu, Chunyao, E-mail: niuchunyao@zzu.edu.cn [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001 (China); Wang, Jianjun [College of Science, Zhongyuan University of Technology, Zhengzhou 450007 (China); Yu, Weiyang [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001 (China); School of Physics and Electronic Information Engineering, Henan Polytechnic University, Jiaozuo, 454000 (China); Ren, XiaoYan; Zhu, Zhili [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001 (China)

    2017-04-11

    Using first-principles density functional theory (DFT) calculations, we systematically investigate the strain effects on the adsorption energies, magnetic ordering and electronic properties of 3d transition metal (TM) atoms (from Sc to Co) adsorbed on phosphorene (P). We find that the adsorption energy of TM can be enhanced by compressive strain whereas weakened by tensile strain. Our results show that strain plays a decisive role in the magnetic moments as well as the magnetic coupling states of TM adatoms. Importantly, the transitions from antiferromagnetic (AFM) state to ferromagnetic (FM) state or to another different AFM ordering can be induced by strain effect. In addition, we observe the semiconductor to metal or half-metal transitions in some TM@P systems by applying strain. Our findings shed a new light on precisely engineering the magnetic properties and electronic properties of the TM@P systems, which will have great potential applications in spin electronics and other related fields. - Highlights: • The adsorption of TM atoms on phosphorene can be enhanced by compressive strain whereas weakened by tensile strain. • Strain plays a decisive role in the magnetic moments as well as the magnetic coupling states of TM adatoms. • Applying strain can induce the semiconductor to metal or half-metal transitions in some TM@P systems.

  5. Bioavailability and Bioaccumulation of Metal-Based Engineered Nanomaterials in Aquatic Environments

    DEFF Research Database (Denmark)

    Luoma, Samuel; Khan, Farhan R.; Croteau, Marie-Noelle

    2014-01-01

    Bioavailability of Me-ENMs to aquatic organisms links their release into the environment to ecological implications. Close examination shows some important differences in the conceptual models that define bioavailability for metals and Me-ENMs. Metals are delivered to aquatic animals from Me......-ENMs via water, ingestion, and incidental surface exposure. Both metal released from the Me-ENM and uptake of the nanoparticle itself contribute to bioaccumulation. Some mechanisms of toxicity and some of the metrics describing exposure may differ from metals alone. Bioavailability is driven by complex...... interaction of particle attributes, environmental transformations, and biological traits. Characterization of Me-ENMs is an essential part of understanding bioavailability and requires novel methodologies. The relative importance of the array of processes that could affect Me-ENM bioavailability remains...

  6. Surface and Interface Engineering of Organometallic and Two Dimensional Semiconductor

    Science.gov (United States)

    Park, Jun Hong

    For over half a century, inorganic Si and III-V materials have led the modern semiconductor industry, expanding to logic transistor and optoelectronic applications. However, these inorganic materials have faced two different fundamental limitations, flexibility for wearable applications and scaling limitation as logic transistors. As a result, the organic and two dimensional have been studied intentionally for various fields. In the present dissertation, three different studies will be presented with followed order; (1) the chemical response of organic semiconductor in NO2 exposure. (2) The surface and stability of WSe2 in ambient air. (3) Deposition of dielectric on two dimensional materials using organometallic seeding layer. The organic molecules rely on the van der Waals interaction during growth of thin films, contrast to covalent bond inorganic semiconductors. Therefore, the morphology and electronic property at surface of organic semiconductor in micro scale is more sensitive to change in gaseous conditions. In addition, metal phthalocyanine, which is one of organic semiconductor materials, change their electronic property as reaction with gaseous analytes, suggesting as potential chemical sensing platforms. In the present part, the growth behavior of metal phthalocyanine and surface response to gaseous condition will be elucidated using scanning tunneling microscopy (STM). In second part, the surface of layered transition metal dichalcogenides and their chemical response to exposure ambient air will be investigated, using STM. Layered transition metal dichalcogenides (TMDs) have attracted widespread attention in the scientific community for electronic device applications because improved electrostatic gate control and suppression of short channel leakage resulted from their atomic thin body. To fabricate the transistor based on TMDs, TMDs should be exposed to ambient conditions, while the effect of air exposure has not been understood fully. In this part

  7. Plasma-implantation-based surface modification of metals with single-implantation mode

    Science.gov (United States)

    Tian, X. B.; Cui, J. T.; Yang, S. Q.; Fu, Ricky K. Y.; Chu, Paul K.

    2004-12-01

    Plasma ion implantation has proven to be an effective surface modification technique. Its biggest advantage is the capability to treat the objects with irregular shapes without complex manipulation of target holder. Many metal materials such as aluminum, stainless steel, tool steel, titanium, magnesium etc, has been treated using this technique to improve their wear-resistance, corrosion-resistance, fatigue-resistance, oxidation-resistance, bio-compatiblity etc. However in order to achieve thicker modified layers, hybrid processes combining plasma ion implantation with other techniques have been frequently employed. In this paper plasma implantation based surface modification of metals using single-implantation mode is reviewed.

  8. Electronic detection of surface plasmon polaritons by metal-oxide-silicon capacitor

    Directory of Open Access Journals (Sweden)

    Robert E. Peale

    2016-09-01

    Full Text Available An electronic detector of surface plasmon polaritons (SPPs is reported. SPPs optically excited on a metal surface using a prism coupler are detected by using a close-coupled metal-oxide-silicon (MOS capacitor. Incidence-angle dependence is explained by Fresnel transmittance calculations, which also are used to investigate the dependence of photo-response on structure dimensions. Electrodynamic simulations agree with theory and experiment and additionally provide spatial intensity distributions on and off the SPP excitation resonance. Experimental dependence of the photoresponse on substrate carrier type, carrier concentration, and back-contact biasing is qualitatively explained by simple theory of MOS capacitors.

  9. Bare and protected sputtered-noble-metal films for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Talaga, David; Bonhommeau, Sébastien

    2014-11-01

    Sputtered silver and gold films with different surface morphologies have been prepared and coated with a benzenethiol self-assembled monolayer. Rough noble metal films showed strong Raman features assigned to adsorbed benzenethiol molecules upon irradiation over a wide energy range in the visible spectrum, which disclosed the occurrence of a significant surface-enhanced Raman scattering with maximal enhancement factors as high as 6 × 106. In addition, the adsorption of ethanethiol onto silver surfaces hinders their corrosion over days while preserving mostly intact enhancement properties of naked silver. This study may be applied to develop stable and efficient metalized probes for tip-enhanced Raman spectroscopy.

  10. Electromechanical performance of an ionic polymer–metal composite actuator with hierarchical surface texture

    International Nuclear Information System (INIS)

    He, Qingsong; Yu, Min; Zhang, Xiaoqing; Dai, Zhendong

    2013-01-01

    Two stainless steel templates were fabricated using electric-spark machining, and a hierarchical surface texture of ionic polymer was produced using both polishing and replication methods, which produced microscale and nanoscale groove-shaped microstructures at the surface of the polymer. The surface morphology of the Nafion membrane and metal electrode were observed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). SEM and EDS line-scan analysis indicated that the interfacial surface area was considerably increased and an excellent metal electrode was obtained with the production of a hierarchical surface texture. The displacement, blocking force, and electric current were measured using home-built apparatus. The results revealed that the combined polishing and replication method significantly improved the electromechanical performance of the ionic polymer–metal composite (IPMC). Compared with sandblasted Nafion-based IPMC, the blocking force, displacement, and electric current of the replicated Nafion-based IPMC were 4.39, 2.35, and 1.87 times higher, respectively. The IPMC fabricated in this work exhibited a competitive blocking force compared with recently reported actuators. (paper)

  11. Experimental study on the surface characteristics of Pd-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiang; Sun, Bingli [School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001 (China); National Center for International Joint Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001 (China); Key Laboratory for Micro Molding Technology of Henan Province, Zhengzhou University, Zhengzhou, 450001 (China); Zhao, Na [National Center for International Joint Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001 (China); Key Laboratory for Micro Molding Technology of Henan Province, Zhengzhou University, Zhengzhou, 450001 (China); National Engineering Research Center for Advanced Polymer Processing Technology, Zhengzhou University, Zhengzhou 450002 (China); Li, Qian, E-mail: qianli@zzu.edu.cn [School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001 (China); National Center for International Joint Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001 (China); Key Laboratory for Micro Molding Technology of Henan Province, Zhengzhou University, Zhengzhou, 450001 (China); National Engineering Research Center for Advanced Polymer Processing Technology, Zhengzhou University, Zhengzhou 450002 (China); Hou, Jianhua; Feng, Weina [School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001 (China); National Center for International Joint Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001 (China); Key Laboratory for Micro Molding Technology of Henan Province, Zhengzhou University, Zhengzhou, 450001 (China)

    2014-12-01

    Highlights: • Wetting behavior of four polymer melts on Pd-based bulk metallic glass was investigated. • From results, in general, the contact angle of polymer on Pd-based BMG decreases with temperature increasing. • We find a critical temperature for each polymer, above this temperature, contact angle on Pd-based BMG does not decrease with temperature increasing. • Surface free energy of Pd-based BMG was estimated by Owens–Wendt method. - Abstract: The metallic glass has many unique and desirable physical and chemical characteristics for their long-range disordered atomic structure, among them the interfacial properties of the metallic glasses are crucial for their applications and manufacturing. In this work, the contact wetting angles between the polymer melts and Pd{sub 40}Cu{sub 30}Ni{sub 10}P{sub 20} bulk metallic glass (Pd-BMG) with four kinds of roughness were analyzed. Experiments show the order of four polymers wettability on Pd-BMG was PP > HDPE > COC > PC. The surface free energy of Pd-BMG was estimated by Owens–Wendt method using the contact angles of three testing liquids. Neumann method was also used to further evidence the surface free energy of Pd-BMG comparing with PTFE, mold steels NAK80 and LKM2343ESR. The results provide theoretical and technical supports for the fabrication of metallic glass micro mold and the parameter optimization of polymer micro injection molding.

  12. Computational studies of experimentally observed structures of sulfur on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Alfonso, Dominic

    2011-09-01

    First-principles electronic structure calculations were carried out to examine the experimentally observed structures of sulfur on close packed surfaces of a number of important metals - Ag(111), Cu(111), Ni(111), Pt(111), Rh(111), Re(0001) and Ru(0001). At low coverages ({le} 1/3 ML), the prediction is consistent with the typical pattern of preferred sulfur occupancy of threefold hollow sites, notably the fcc site on the (111) surfaces and the hcp site on the (0001) surfaces. Theoretical confirmation for the existence of pure sulfur overlayer phases on Pt(111), Rh(111), Re(0001) and Ru(0001) at higher coverages (> 1/3 ML) was provided. For the ({radical}7 x {radical}7) phase seen on Ag(111), the most preferred structure identified for adsorbed S trimer consists of an S atom on the top site bonded to two S atoms situated on the nearest neighbor off-bridge site positions. Among the different densely packed mixed sulfur-metal overlayer models suggested for the ({radical}7 x {radical}7) phase on Cu(111), the structure which consists of metal and S atoms in a hexagonal-like arrangement on the top substrate was found to be the most energetically favorable. For the (5{radical}3 x 2) phase on Ni(111), the calculations confirm the existence of clock-reconstructed top layer metal atoms onto which sulfur atoms are adsorbed.

  13. The role of substrate electrons in the wetting of a metal surface

    DEFF Research Database (Denmark)

    Schiros, T.; Takahashi, O.; Andersson, Klas Jerker

    2010-01-01

    We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution...

  14. Spatial Gradients in Trace Metal Concentrations in the Surface Microlayer of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Antonio eTovar-Sanchez

    2014-12-01

    Full Text Available The relationship between dust deposition and surface water metal concentrations is poorly understood. Dissolution, solubility, and partitioning reactions of trace metals from dust particles are governed by complex chemical, biological, and physical processes occurring in the surface ocean. Despite that, the role of the sea surface microlayer (SML, a thin, but fundamental component modulating the air-sea exchange of materials has not been properly evaluated. Our study revealed that the SML of the Mediterranean Sea is enriched with bioactive trace metals (i.e., Cd, Co, Cu and Fe, ranging from 8 (for Cd to 1000 (for Fe times higher than the dissolved metal pool in the underlying water column. The highest enrichments were spatially correlated with the atmospheric deposition of mineral particles. Our mass balance results suggest that the SML in the Mediterranean Sea contains about 2 tonnes of Fe. However, we did not detect any trends between the concentrations of metals in SML with the subsurface water concentrations and biomass distributions. These findings suggest that future studies are needed to quantify the rate of metal exchange between the SML and the bioavailable pool and that the SML should be considered to better understand the effect of atmospheric inputs on the biogeochemistry of trace metals in the ocean.

  15. Some characteristics of metal migration in or on the surface of insulators

    International Nuclear Information System (INIS)

    Shields, R.B.

    1978-03-01

    This report reviews the migration of metals, principally silver, in or on the surface of insulating materials, by electrolytic processes. These processes are described for various metals, insulating materials and physical conditions, with numerous examples from the literature. While it is concluded that the only sure way to prevent degradation of insulation due to metal migration is to avoid the use of migration-prone metals, some other measures are mentioned which have been reported to reduce the extent of the growth. (author)

  16. Tailoring of the PS surface with low energy ions: Relevance to growth and adhesion of noble metals

    International Nuclear Information System (INIS)

    Zaporojtchenko, V.; Zekonyte, J.; Wille, S.; Schuermann, U.; Faupel, F.

    2005-01-01

    Ion-polymer interaction induces different phenomena in the near surface layer of polymers, and promotes its adhesion to metals. Using XPS, TEM and AFM, polystyrene surface was examined after 1 keV ion-beam treatments with oxygen, nitrogen and argon ions in the ion fluence range from 10 12 to 10 16 cm -2 to clarify the following points: chemical reaction after treatment in vacuum and after exposure to air, identification of adsorption-relevant species for metal atoms, formation of cross-links in the outermost polymer layer. The early stages of metal-polymer interface formation during metallization play a crucial role in the metal-polymer adhesion. Therefore, the influence of the ion fluence and ion chemistry on the condensation of noble metals, film growth and peel strength were measured. The peel strength showed a maximum at a certain fluence depending on ion chemistry. For example, the surface treatment with very low fluence of oxygen ions improved the adhesion between copper and polystyrene by two orders of magnitude without significantly increasing the surface roughness measured with AFM. The locus of failure changed at the same time from interfacial failure for untreated polymer surfaces to cohesive failure in the polymer for modified surfaces. A multilayer model of the metal-polymer interface after ion treatment is suggested

  17. Adhesive bonding of resin composite to various titanium surfaces using different metal conditioners and a surface modification system

    Directory of Open Access Journals (Sweden)

    Hercules Jorge ALMILHATTI

    2013-12-01

    Full Text Available Objective: This study evaluated the effect of three metal conditioners on the shear bond strength (SBS of a prosthetic composite material to cpTi grade I having three surface treatments. Material and Methods: One hundred sixty eight rivet-shaped specimens (8.0x2.0 mm were cast and subjected to polishing (P or sandblasting with either 50 mm (50SB or 250 mm (250SB Al2O3. The metal conditioners Metal Photo Primer (MPP, Cesead II Opaque Primer (OP, Targis Link (TL, and one surface modification system Siloc (S, were applied to the specimen surfaces, which were covered with four 1-mm thick layers of resin composite. The resin layers were exposed to curing light for 90 s separately. Seven specimens from each experimental group were stored in water at 37ºC for 24 h while the other 7 specimens were subjected to 5,000 thermal cycles consisting of water baths at 4ºC and 60ºC (n=7. All specimens were subjected to SBS test (0.5 mm/min until failure occurred, and further 28 specimens were analyzed using scanning electron microscope (SEM and X-ray energy-dispersive spectroscopy (EDS. Data were analyzed by 3-way ANOVA followed by post-hoc Tukey's test (α=0.05. Results: On 50SB surfaces, OP groups showed higher SBS means than MPP (P<0.05, while no significant difference was found among OP, S, and TL groups. On 250SB surfaces, OP and TL groups exhibited higher SBS than MPP and S (P<0.05. No significant difference in SBS was found between OP and TL groups nor between MPP and S groups. The use of conditioners on 250SB surfaces resulted in higher SBS means than the use of the same products on 50SB surfaces (P<0.05. Conclusion: Sandblasting associated with the use of metal conditioners improves SBS of resin composites to cpTi.

  18. Coordination to transition metal surfaces : a theoretical study

    NARCIS (Netherlands)

    Santen, van R.A.

    1985-01-01

    A theoretical framework is developed that describes the chemisorption of CO to transition metal surfaces analogous to the HOMO-LUMO concept of MO theory. An explanation is given for the exptl. observation that CO adsorbs on top at the (111), face of Pt, but bridge at the (111) face of Ni. One is due

  19. Versatile Surface Functionalization of Metal-Organic Frameworks through Direct Metal Coordination with a Phenolic Lipid Enables Diverse Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wei [Univ. of New Mexico, Albuquerque, NM (United States); Xiang, Guolei [Univ. of Cambridge (United Kingdom); Shang, Jin [Univ. of Hong Kong (China); Guo, Jimin [Univ. of New Mexico, Albuquerque, NM (United States); Motevalli, Benyamin [Monash Univ., Clayton, VIC (Australia); Durfee, Paul [Univ. of New Mexico, Albuquerque, NM (United States); Agola, Jacob Ongudi [Univ. of New Mexico, Albuquerque, NM (United States); Coker, Eric N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brinker, C. Jeffrey [Univ. of New Mexico, Albuquerque, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-02-22

    Here, a novel strategy for the versatile functionalization of the external surface of metal-organic frameworks (MOFs) has been developed based on the direct coordination of a phenolic-inspired lipid molecule DPGG (1,2-dipalmitoyl-sn-glycero-3-galloyl) with metal nodes/sites surrounding MOF surface. X-ray diffraction and Argon sorption analysis prove that the modified MOF particles retain their structural integrity and porosity after surface modification. Density functional theory calculations reveal that strong chelation strength between the metal sites and the galloyl head group of DPGG is the basic prerequisite for successful coating. Due to the pH-responsive nature of metal-phenol complexation, the modification process is reversible by simple washing in weak acidic water, showing an excellent regeneration ability for water-stable MOFs. Moreover, the colloidal stability of the modified MOFs in the nonpolar solvent allows them to be further organized into 2 dimensional MOF or MOF/polymer monolayers by evaporation-induced interfacial assembly conducted on an air/water interface. Lastly, the easy fusion of a second functional layer onto DPGG-modified MOF cores, enabled a series of MOF-based functional nanoarchitectures, such as MOFs encapsulated within hybrid supported lipid bilayers (so-called protocells), polyhedral core-shell structures, hybrid lipid-modified-plasmonic vesicles and multicomponent supraparticles with target functionalities, to be generated. for a wide range of applications.

  20. Assembly, Structure, and Functionality of Metal-Organic Networks and Organic Semiconductor Layers at Surfaces

    Science.gov (United States)

    Tempas, Christopher D.

    Self-assembled nanostructures at surfaces show promise for the development of next generation technologies including organic electronic devices and heterogeneous catalysis. In many cases, the functionality of these nanostructures is not well understood. This thesis presents strategies for the structural design of new on-surface metal-organic networks and probes their chemical reactivity. It is shown that creating uniform metal sites greatly increases selectivity when compared to ligand-free metal islands. When O2 reacts with single-site vanadium centers, in redox-active self-assembled coordination networks on the Au(100) surface, it forms one product. When O2 reacts with vanadium metal islands on the same surface, multiple products are formed. Other metal-organic networks described in this thesis include a mixed valence network containing Pt0 and PtII and a network where two Fe centers reside in close proximity. This structure is stable to temperatures >450 °C. These new on-surface assemblies may offer the ability to perform reactions of increasing complexity as future heterogeneous catalysts. The functionalization of organic semiconductor molecules is also shown. When a few molecular layers are grown on the surface, it is seen that the addition of functional groups changes both the film's structure and charge transport properties. This is due to changes in both first layer packing structure and the pi-electron distribution in the functionalized molecules compared to the original molecule. The systems described in this thesis were studied using high-resolution scanning tunneling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy. Overall, this work provides strategies for the creation of new, well-defined on-surface nanostructures and adds additional chemical insight into their properties.

  1. Mechanical Engineering Department engineering research: Annual report, FY 1986

    Energy Technology Data Exchange (ETDEWEB)

    Denney, R.M.; Essary, K.L.; Genin, M.S.; Highstone, H.H.; Hymer, J.D.; Taft, S.O. (eds.)

    1986-12-01

    This report provides information on the five areas of research interest in LLNL's Mechanical Engineering Department. In Computer Code Development, a solid geometric modeling program is described. In Dynamic Systems and Control, structure control and structure dynamics are discussed. Fabrication technology involves machine cutting, interferometry, and automated optical component manufacturing. Materials engineering reports on composite material research and measurement of molten metal surface properties. In Nondestructive Evaluation, NMR, CAT, and ultrasound machines are applied to manufacturing processes. A model for underground collapse is developed. Finally, an alternative heat exchanger is investigated for use in a fusion power plant. Separate abstracts were prepared for each of the 13 reports in this publication. (JDH)

  2. Reaction pathways of biomass-derived oxygenates on noble metal surfaces

    Science.gov (United States)

    McManus, Jesse R.

    As the global demand for energy continues to rise, the environmental concerns associated with increased fossil fuel consumption have motivated the use of biomass as an alternative, carbon-renewable energy feedstock. Controlling reactive chemistry of the sugars that comprise biomass through the use of catalysis becomes essential in effectively producing green fuels and value-added chemicals. Recent work on biomass conversion catalysts have demonstrated the efficacy of noble metal catalyst systems for the reforming of biomass to hydrogen fuel, and the hydrodeoxygenation of biomass-derived compounds to value-added chemicals. In particular, Pt and Pd surfaces have shown considerable promise as reforming catalysts in preliminary aqueous phase reforming studies. It becomes important to understand the mechanisms by which these molecules react on the catalyst surfaces in order to determine structure-activity relationships and bond scission energetics as to provide a framework for engineering more active and selective catalysts. Fundamental surface science techniques provide the tools to do this; however, work in this field has been so far limited to simple model molecules like ethanol and ethylene glycol. Herein, temperature programmed desorption and high resolution electron energy loss spectroscopy are utilized in an ultra-high vacuum surface science study of the biomass-derived sugar glucose on Pt and Pd single crystal catalysts. Overall, it was determined that the aldehyde function of a ring-open glucose molecule plays an integral part in the initial bonding and reforming reaction pathway, pointing to the use of aldoses glycolaldehyde and glyceraldehyde as the most appropriate model compounds for future studies. Furthermore, the addition of adatom Zn to a Pt(111) surface was found to significantly decrease the C-H and C-C bond scission activity in aldehyde containing compounds, resulting in a preferred deoxygenation pathway in opposition to the decarbonylation pathway

  3. The secondary electron yield of noble metal surfaces

    Directory of Open Access Journals (Sweden)

    L. A. Gonzalez

    2017-11-01

    Full Text Available Secondary electron yield (SEY curves in the 0-1000 eV range were measured on polycrystalline Ag, Au and Cu samples. The metals were examined as introduced in the ultra-high vacuum chamber and after having been cleaned by Ar+ ion sputtering. The comparison between the curves measured on the clean samples and in the presence of contaminants, due to the permanence in atmosphere, confirmed that the SEY behavior is strongly influenced by the chemical state of the metal surface. We show that when using very slow primary electrons the sample work function can be determined with high accuracy from the SEY curves. Moreover we prove that SEY is highly sensitive to the presence of adsorbates even at submonolayer coverage. Results showing the effect of small quantities of CO adsorbed on copper are presented. Our findings demonstrate that SEY, besides being an indispensable mean to qualify technical materials in many technological fields, can be also used as a flexible and advantageous diagnostics to probe surfaces and interfaces.

  4. Nanoporous metals for advanced energy technologies

    CERN Document Server

    Ding, Yi

    2016-01-01

    This book covers the state-of-the-art research in nanoporous metals for potential applications in advanced energy fields, including proton exchange membrane fuel cells, Li batteries (Li ion, Li-S, and Li-O2), and supercapacitors. The related structural design and performance of nanoporous metals as well as possible mechanisms and challenges are fully addressed. The formation mechanisms of nanoporous metals during dealloying, the microstructures of nanoporous metals and characterization methods, as well as miscrostructural regulation of nanoporous metals through alloy design of precursors and surface diffusion control are also covered in detail. This is an ideal book for researchers, engineers, graduate students, and government/industry officers who are in charge of R&D investments and strategy related to energy technologies.

  5. Photoelectron emission from metal surfaces by ultrashort laser pulses

    International Nuclear Information System (INIS)

    Faraggi, M. N.; Gravielle, M. S.; Silkin, V. M.

    2006-01-01

    Electron emission from metal surfaces produced by short laser pulses is studied within the framework of the distorted-wave formulation. The proposed approach, named surface-Volkov (SV) approximation, makes use of the band-structure based (BSB) model and the Volkov phase to describe the interaction of the emitted electron with the surface and the external electric field, respectively. The BSB model provides a realistic representation of the surface, based on a model potential that includes the main features of the surface band structure. The SV method is applied to evaluate the photoelectron emission from the valence band of Al(111). Angular and energy distributions are investigated for different parameters of the laser pulse, keeping in all cases the carrier frequency larger than the plasmon one

  6. Removal of foreign atoms from a metal surface bombarded with fast atomic particles

    Energy Technology Data Exchange (ETDEWEB)

    Dolotov, S.K.; Evstigneev, S.A.; Luk' yanov, S.Yu.; Martynenko, Yu.V.; Chicherov, V.M.

    1976-07-01

    A metal surface coated with foreign atoms was irradiated with periodically repeating ion current pulses. The energy of the ions bombarding the target was 20 to 30 keV, and inert gas ions were used. A study of the time dependences of the current of the dislodged foreign atoms showed that the rate of their removal from the target surface is determined by the sputtering coefficient of the substrate metal.

  7. Removal of foreign atoms from a metal surface bombarded with fast atomic particles

    International Nuclear Information System (INIS)

    Dolotov, S.K.; Evstigneev, S.A.; Luk'yanov, S.Yu.; Martynenko, Yu.V.; Chicherov, V.M.

    A metal surface coated with foreign atoms was irradiated with periodically repeating ion current pulses. The energy of the ions bombarding the target was 20 to 30 keV, and inert gas ions were used. A study of the time dependences of the current of the dislodged foreign atoms showed that the rate of their removal from the target surface is determined by the sputtering coefficient of the substrate metal

  8. Polydopamine-mediated surface-functionalization of graphene oxide for heavy metal ions removal

    International Nuclear Information System (INIS)

    Dong, Zhihui; Zhang, Feng; Wang, Dong; Liu, Xia; Jin, Jian

    2015-01-01

    By utilizing polydopamine (PD) nano-thick interlayer as mediator, polyethylenimine (PEI) brushes with abundant amine groups were grafted onto the surface of PD coated graphene oxide (GO) uniformly via a Michael-Addition reaction and produced a PEI–PD/GO composite nanosheets. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions as compared to PEI-coated GO and pure GO. The adsorption capacities for Cu 2+ , Cd 2+ , Pb 2+ , Hg 2+ are up to 87, 106, 197, and 110 mg/g, respectively. To further make the GO based composite operable, PEI–PD/RGO aerogel was prepared through hydrothermal and achieved a high surface area up to 373 m 2 /g. Although the adsorption capacity of PEI–PD/RGO aerogel for heavy metal ions decreases a little as compared to PEI–PD/GO composite dispersion (38, 32, 95, 113 mg/g corresponding to Cu 2+ , Cd 2+ , Pb 2+ , and Hg 2+ , respectively), it could be recycled several times in a simple way by releasing adsorbed metal ions, indicating its potential application for cleaning wastewater. - Graphical abstract: Polyethylenimine (PEI) brushes were grafted onto the surface of graphene oxide (GO) uniformly via a Michael-Addition reaction between the PEI and polydopamine interlayer coated on GO surface. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions compared to PEI-coated GO and pure GO. - Highlights: • We prepared polyethylenimine grafted polydopamine-mediated graphene oxide composites. • Introduction of PD layer increases metal ions adsorption capacity. • PEI–PD/RGO aerogel exhibited a superior adsorption performance. • PEI–PD/RGO aerogel can be recycled several times in a simple way

  9. Surface engineering with ion beams: from self-organized nanostructures to ultra-smooth surfaces

    International Nuclear Information System (INIS)

    Frost, F.; Ziberi, B.; Schindler, A.; Rauschenbach, B.

    2008-01-01

    Low-energy ion-beam sputtering, i.e. the removal of atoms from a surface due to the impact of energetic ions or atoms, is an inherent part of numerous surface processing techniques. Besides the actual removal of material, this surface erosion process often results in a pronounced alteration of the surface topography. Under certain conditions, sputtering results in the formation of well-ordered patterns. This self-organized pattern formation is related to a surface instability between curvature-dependent sputtering that roughens the surface and smoothing by different surface relaxation mechanisms. If the evolution of surface topography is dominated by relaxation mechanisms, surface smoothing can occur. In this presentation the current status of self-organized pattern formation and surface smoothing by low-energy ion-beam erosion of Si and Ge is summarized. In detail it will be shown that a multitude of patterns as well as ultra-smooth surfaces can develop, particularly on Si surfaces. Additionally, the most important experimental parameters that control these processes are discussed. Finally, examples are given for the application of low-energy ion beams as a novel approach for passive optical device engineering for many advanced optical applications. (orig.)

  10. Fracture Surface Morphology Under Ductile Tearing of Metal Plates

    DEFF Research Database (Denmark)

    Kacar, Muhammet F.; Tekoglu, Cihan; Nielsen, Kim Lau

    2017-01-01

    The present work takes as offset the hypothesis that microstructural parameters, related to particle size and distribution, govern the transition between crack surface morphologies observed in experiments. The key question is; why does tearing of a given metal plate leave a specific morphology...

  11. Theoretical study of n-alkane adsorption on metal surfaces

    DEFF Research Database (Denmark)

    Morikawa, Yoshitada; Ishii, Hisao; Seki, Kazuhiko

    2004-01-01

    The interaction between n-alkane and metal surfaces has been studied by means of density-functional theoretical calculations within a generalized gradient approximation (GGA). We demonstrate that although the GGA cannot reproduce the physisorption energy well, our calculations can reproduce the e...

  12. Metallic surfaces decontamination by using laser light

    International Nuclear Information System (INIS)

    Moggia, Fabrice; Lecardonnel, Xavier

    2013-01-01

    Metal surface cleaning appears to be one of the major priorities for industries especially for nuclear industries. The research and the development of a new technology that is able to meet the actual requirements (i.e. waste volume minimization, liquid effluents and chemicals free process...) seems to be the main commitment. Currently, a wide panel of technologies already exists (e.g. blasting, disk sander, electro-decontamination...) but for some of them, the efficiency is limited (e.g, Dry Ice blasting) and for others, the wastes production (liquid and/or solid) remains an important issue. One answer could be the use of a LASER light process. Since a couple of years, the Clean- Up Business Unit of the AREVA group investigates this decontamination technology. Many tests have been already performed in inactive (i.e. on simulants such as paints, inks, resins, metallic oxides) or active conditions (i.e. pieces covered with a thick metallic oxide layer and metallic pieces covered with grease). The paper will describe the results obtained in term of decontamination efficiency during all our validation process. Metallographic characterizations (i.e. SEM, X-ray scattering) and radiological analysis will be provided. We will also focus our paper on the future deployment of the LASER technology and its commercial use at La Hague reprocessing facility in 2013. (authors)

  13. Making metals transparency for white light by surface plasmons

    Science.gov (United States)

    Peng, Ru-Wen; Huang, Xian-Rong; Fan, Ren-Hao; Li, Jia; Hu, Qing; Wang, Mu

    2012-02-01

    We demonstrate both experimentally and theoretically that metallic gratings consisting of narrow slits become transparent for extremely broad bandwidths under oblique incidence. This phenomenon can be explained by a concrete picture in which the incident wave drives free electrons on the conducting surfaces and part of the slit walls to form surface plasmons (SPs). The SPs then propagate on the slit walls but are abruptly discontinued by the bottom edges to form oscillating charges that emit the transmitted wave. This picture explicitly demonstrates the conversion between light and SPs and indicates clear guidelines for enhancing SP excitation and propagation. Making structured metals transparent may lead to a variety of applications. References: Xian-Rong Huang, Ru-Wen Peng, and Ren-Hao Fan, Phys. Rev. Lett. (2010)105, 243901; and Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Jia Li, Qing Hu, and Mu Wang, manuscript prepared(2011).

  14. Research of state of metal welded joint by deformation and corrosion surface projection parameters

    Directory of Open Access Journals (Sweden)

    Demchenko Maria Vyacheslavovna

    2017-10-01

    Full Text Available At industrial enterprises in building structures and equipment one can see corrosion damage, as well as damage accumulated during operation period. The areas of stress concentration are welded joints as their structure is heterogeneous. From the point of view of the scale hierarchy, the welded joint represents the welded and base metal zones at the meso-macrolevel, the weld zone, the thermal zone, the base metal at the micro-mesolevel, the grain constituents at the nano-microlevel. Borders are the stress concentrators at different scale levels, thus they becomes the most dangerous places of metal structure. Modeling by the molecular dynamics method at the atomic level has shown nanocracks initiation in triple junctions of grain boundaries and on the ledges of the grain boundaries. Due to active development of nanotechnology, it became possible to evaluate the state of the weld metal at the nanoscale, where irreversible changes take place from the very beginning. Existing methods of nondestructive testing can detect damage only at the meso- and macrolevel. Modern equipment makes it possible to use other methods of control and approaches. For example, according to GOST R55046-2012 and R57223-2016, the analysis of the parameters of the surface projection deformation performed by confocal laser scanning microscopy should be taken into account when the evaluation of state of metal pipelines is carried out. However, there is a problem to monitore it due to various factors affecting the surface during operation. The paper proposes an additional method to estimate the state of weld metal at any stage of deformation that uses 3D analysis of the parameters of the «artificial» corrosion relief of surface. During the operation period changes in the stress-strain state and structure of the metal take place, as the result the character and depth of etching of the grains of the structural components and their boundaries change too. Evaluation of the

  15. Effect of metallic and hyperbolic metamaterial surfaces on electric and magnetic dipole emission transitions

    DEFF Research Database (Denmark)

    Ni, X.; Naik, G. V.; Kildishev, A. V.

    2011-01-01

    Spontaneous emission patterns of electric and magnetic dipoles on different metallic surfaces and a hyperbolic metamaterial (HMM) surface were simulated using the dyadic Green’s function technique. The theoretical approach was verified by experimental results obtained by measuring angular......-dependent emission spectra of europium ions on top of different films. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces. The results of numerical calculations agree well with experimental data....

  16. Development of stress corrosion cracking resistant welds of 321 stainless steel by simple surface engineering

    Science.gov (United States)

    Mankari, Kamal; Acharyya, Swati Ghosh

    2017-12-01

    We hereby report a simple surface engineering technique to make AISI grade 321 stainless steel (SS) welds resistant to stress corrosion cracking (SCC) in chloride environment. Heat exchanger tubes of AISI 321 SS, welded either by (a) laser beam welding (LBW) or by (b) metal inert gas welding (MIG) were used for the study. The welds had high magnitude of tensile residual stresses and had undergone SCC in chloride environment while in service. The welds were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Subsequently, the welded surfaces were subjected to buffing operation followed by determination of residual stress distribution and surface roughness by XRD and surface profilometer measurements respectively. The susceptibility of the welds to SCC was tested in buffed and un-buffed condition as per ASTM G-36 in boiling MgCl2 for 5 h and 10 h, followed by microstructural characterization by using optical microscope and FESEM. The results showed that the buffed surfaces (both welds and base material) were resistant to SCC even after 10 h of exposure to boiling MgCl2 whereas the un-buffed surfaces underwent severe SCC for the same exposure time. Buffing imparted high magnitude of compressive stresses on the surface of stainless steel together with reduction in its surface roughness and reduction in plastic strain on the surface which made the welded surface, resistant to chloride assisted SCC. Buffing being a very simple, portable and economic technique can be easily adapted by the designers as the last step of component fabrication to make 321 stainless steel welds resistant to chloride assisted SCC.

  17. Stripping scattering of fast atoms on surfaces of metal-oxide crystals and ultrathin films

    International Nuclear Information System (INIS)

    Blauth, David

    2010-01-01

    In the framework of the present dissertation the interactions of fast atoms with surfaces of bulk oxides, metals and thin films on metals were studied. The experiments were performed in the regime of grazing incidence of atoms with energies of some keV. The advantage of this scattering geometry is the high surface sensibility and thus the possibility to determine the crystallographic and electronic characteristics of the topmost surface layer. In addition to these experiments, the energy loss and the electron emission induced by scattered projectiles was investigated. The energy for electron emission and exciton excitation on Alumina/NiAl(110) and SiO 2 /Mo(112) are determined. By detection of the number of projectile induced emitted electrons as function of azimuthal angle for the rotation of the target surface, the geometrical structure of atoms forming the topmost layer of different adsorbate films on metal surfaces where determined via ion beam triangulation. (orig.)

  18. Surface coating affects behavior of metallic nanoparticles in a biological environment

    Directory of Open Access Journals (Sweden)

    Darija Domazet Jurašin

    2016-02-01

    Full Text Available Silver (AgNPs and maghemite, i.e., superparamagnetic iron oxide nanoparticles (SPIONs are promising candidates for new medical applications, which implies the need for strict information regarding their physicochemical characteristics and behavior in a biological environment. The currently developed AgNPs and SPIONs encompass a myriad of sizes and surface coatings, which affect NPs properties and may improve their biocompatibility. This study is aimed to evaluate the effects of surface coating on colloidal stability and behavior of AgNPs and SPIONs in modelled biological environments using dynamic and electrophoretic light scattering techniques, as well as transmission electron microscopy to visualize the behavior of the NP. Three dispersion media were investigated: ultrapure water (UW, biological cell culture medium without addition of protein (BM, and BM supplemented with common serum protein (BMP. The obtained results showed that different coating agents on AgNPs and SPIONs produced different stabilities in the same biological media. The combination of negative charge and high adsorption strength of coating agents proved to be important for achieving good stability of metallic NPs in electrolyte-rich fluids. Most importantly, the presence of proteins provided colloidal stabilization to metallic NPs in biological fluids regardless of their chemical composition, surface structure and surface charge. In addition, an assessment of AgNP and SPION behavior in real biological fluids, rat whole blood (WhBl and blood plasma (BlPl, revealed that the composition of a biological medium is crucial for the colloidal stability and type of metallic NP transformation. Our results highlight the importance of physicochemical characterization and stability evaluation of metallic NPs in a variety of biological systems including as many NP properties as possible.

  19. Metallic surface description in a localized representation

    International Nuclear Information System (INIS)

    Kirtman, B.; Melo, C.P. de

    1981-01-01

    Binding orders for a three-dimensional system (cubium) are obtained. The study of convergence of these values with the progressive interiorization in the solid gives an indication of the perturbation magnitude introduced with the surface creation. Following Goddard's hint in which the nickel reactivity is denominated by the 4s orbitals, such a model is applied to this metal. The base transformation of atomic orbitals for the correspondent Wannier functions is obtained. (L.C.) [pt

  20. Surface flow in severe plastic deformation of metals by sliding

    International Nuclear Information System (INIS)

    Mahato, A; Yeung, H; Chandrasekar, S; Guo, Y

    2014-01-01

    An in situ study of flow in severe plastic deformation (SPD) of surfaces by sliding is described. The model system – a hard wedge sliding against a metal surface – is representative of surface conditioning processes typical of manufacturing, and sliding wear. By combining high speed imaging and image analysis, important characteristics of unconstrained plastic flow inherent to this system are highlighted. These characteristics include development of large plastic strains on the surface and in the subsurface by laminar type flow, unusual fluid-like flow with vortex formation and surface folding, and defect and particle generation. Preferred conditions, as well as undesirable regimes, for surface SPD are demarcated. Implications for surface conditioning in manufacturing, modeling of surface deformation and wear are discussed

  1. Metal Recovery and Preconcentration by Edta and Dtpa Modified Silica Surfaces

    Directory of Open Access Journals (Sweden)

    Eveliina Repo

    2017-03-01

    Full Text Available This study focuses on the adsorption and preconcentration of various metals by silica gel surfaces modified with aminopolycarboxylic acids namely ethylenediaminetetraacetic acid or diethylenetriamine-pentaacetic acid. The adsorption performance of the studied materials was determined in mixed metal solutions and the adsorption isotherm studies were conducted for cobalt, nickel, cadmium, and lead. The results were modeled using various theoretical isotherm equations, which suggested that two different adsorption sites were involved in metal removal although lead showed clearly different adsorption behavior attributed to its lowest hydration tendency. Efficient regeneration of the adsorbents and preconcentration of metals was conducted with nitric acid. Results indicated that the metals under study could be analyzed rather accurately after preconcentration from both pure, saline and ground water samples.

  2. Comparison of catalytic converter performance in internal combustion engine fueled with Ron 95 and Ron 97 gasoline

    Science.gov (United States)

    Leman, A. M.; Rahman, Fakhrurrazi; Jajuli, Afiqah; Feriyanto, Dafit; Zakaria, Supaat

    2017-09-01

    Generating ideal stability between engine performance, fuel consumption and emission is one of the main challenges in the automotive industry. The characteristics of engine combustion and creation of emission might simply change with different types of operating parameters. This study aims in investigating the relationship between two types of fuels on the performance and exhaust emission of internal combustion engine using ceramic and metallic catalytic converters. Experimental tests were performed on Mitsubishi 4G93 engine by applying several ranges of engine speeds to determine the conversion of pollutant gases released by the engine. The obtained results specify that the usage of RON 97 equipped with metallic converters might increase the conversion percentage of 1.31% for CO and 126 ppm of HC gases. The metallic converters can perform higher conversion compared to ceramic because in the high space velocities, metallic has higher surface geometry area and higher amount of transverse Peclet number (Pi). Ceramic converters achieved conversion at 2496 ppm of NOx gas, which is higher than the metallic converter.

  3. Biomolecular strategies for cell surface engineering

    Science.gov (United States)

    Wilson, John Tanner

    Islet transplantation has emerged as a promising cell-based therapy for the treatment of diabetes, but its clinical efficacy remains limited by deleterious host responses that underlie islet destruction. In this dissertation, we describe the assembly of ultrathin conformal coatings that confer molecular-level control over the composition and biophysicochemical properties of the islet surface with implications for improving islet engraftment. Significantly, this work provides novel biomolecular strategies for cell surface engineering with broad biomedical and biotechnological applications in cell-based therapeutics and beyond. Encapsulation of cells and tissue offers a rational approach for attenuating deleterious host responses towards transplanted cells, but a need exists to develop cell encapsulation strategies that minimize transplant volume. Towards this end, we endeavored to generate nanothin films of diverse architecture with tunable properties on the extracellular surface of individual pancreatic islets through a process of layer-by-layer (LbL) self assembly. We first describe the formation of poly(ethylene glycol) (PEG)-rich conformal coatings on islets via LbL self assembly of poly(L-lysine)-g-PEG(biotin) and streptavidin. Multilayer thin films conformed to the geometrically and chemically heterogeneous islet surface, and could be assembled without loss of islet viability or function. Significantly, coated islets performed comparably to untreated controls in a murine model of allogenic intraportal islet transplantation, and, to our knowledge, this is the first study to report in vivo survival and function of nanoencapsulated cells or cell aggregates. Based on these findings, we next postulated that structurally similar PLL-g-PEG copolymers comprised of shorter PEG grafts might be used to initiate and propagate the assembly of polyelectrolyte multilayer (PEM) films on pancreatic islets, while simultaneously preserving islet viability. Through control of PLL

  4. Metal concentration at surface water using multivariate analysis and ...

    African Journals Online (AJOL)

    Metal concentration at surface water using multivariate analysis and human health risk assessment. F Azaman, H Juahir, K Yunus, A Azid, S.I. Khalit, A.D. Mustafa, M.A. Amran, C.N.C. Hasnam, M.Z.A.Z. Abidin, M.A.M. Yusri ...

  5. Scaling Relationships for Adsorption Energies of C2 Hydrocarbons on Transition Metal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G

    2011-08-18

    Using density functional theory calculations we show that the adsorption energies for C{sub 2}H{sub x}-type adsorbates on transition metal surfaces scale with each other according to a simple bond order conservation model. This observation generalizes some recently recognized adsorption energy scaling laws for AH{sub x}-type adsorbates to unsaturated hydrocarbons and establishes a coherent simplified description of saturated as well as unsaturated hydrocarbons adsorbed on transition metal surfaces. A number of potential applications are discussed. We apply the model to the dehydrogenation of ethane over pure transition metal catalysts. Comparison with the corresponding full density functional theory calculations shows excellent agreement.

  6. Surface plasmons in metallic nanoparticles: fundamentals and applications

    International Nuclear Information System (INIS)

    Garcia, M A

    2011-01-01

    The excitation of surface plasmons (SPs) in metallic nanoparticles (NPs) induces optical properties hardly achievable in other optical materials, yielding a wide range of applications in many fields. This review presents an overview of SPs in metallic NPs. The concept of SPs in NPs is qualitatively described using a comparison with simple linear oscillators. The mathematical models to carry on calculations on SPs are presented as well as the most common approximations. The different parameters governing the features of SPs and their effect on the optical properties of the materials are reviewed. Finally, applications of SPs in different fields such as biomedicine, energy, environment protection and information technology are revised. (topical review)

  7. Surface plasmons in metallic nanoparticles: fundamentals and applications

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M A, E-mail: magarcia@icv.csic.es [Department of Electroceramics, Institute for Ceramic and Glass, CSIC, C/Kelsen 5, 28049 Madrid (Spain) and IMDEA Nanociencia, Madrid 28049 (Spain)

    2011-07-20

    The excitation of surface plasmons (SPs) in metallic nanoparticles (NPs) induces optical properties hardly achievable in other optical materials, yielding a wide range of applications in many fields. This review presents an overview of SPs in metallic NPs. The concept of SPs in NPs is qualitatively described using a comparison with simple linear oscillators. The mathematical models to carry on calculations on SPs are presented as well as the most common approximations. The different parameters governing the features of SPs and their effect on the optical properties of the materials are reviewed. Finally, applications of SPs in different fields such as biomedicine, energy, environment protection and information technology are revised. (topical review)

  8. Performance evaluation of a biodiesel fuelled transportation engine retrofitted with a non-noble metal catalysed diesel oxidation catalyst for controlling unregulated emissions.

    Science.gov (United States)

    Shukla, Pravesh Chandra; Gupta, Tarun; Agarwal, Avinash Kumar

    2018-02-15

    In present study, engine exhaust was sampled for measurement and analysis of unregulated emissions from a four cylinder transportation diesel engine using a state-of-the-art FTIR (Fourier transform infrared spectroscopy) emission analyzer. Test fuels used were Karanja biodiesel blend (B20) and baseline mineral diesel. Real-time emission measurements were performed for raw exhaust as well as exhaust sampled downstream of the two in-house prepared non-noble metal based diesel oxidation catalysts (DOCs) and a baseline commercial DOC based on noble metals. Two prepared non-noble metal based DOCs were based on Co-Ce mixed oxide and Lanthanum based perovskite catalysts. Perovskite based DOC performed superior compared to Co-Ce mixed oxide catalyst based DOC. Commercial noble metal based DOC was found to be the most effective in reducing unregulated hydrocarbon emissions in the engine exhaust, followed by the two in-house prepared non-noble metal based DOCs. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Modification of metallic corrosion by ion implantation

    International Nuclear Information System (INIS)

    Clayton, C.R.

    1981-01-01

    This review will consider some of the properties of surface alloys, formed by ion implantation, which are effective in modifying corrosion behaviour. Examples will be given of the modification of the corrosion behaviour of pure metals, steels and other engineering alloys, resulting from implantation with metals and metalloids. Emphasis will be given to the modification of anodic processes produced by ion implantation since a review will be given elsewhere in the proceedings concerning the modification of cathodic processes. (orig.)

  10. Metal contact engineering and registration-free fabrication of complementary metal-oxide semiconductor integrated circuits using aligned carbon nanotubes.

    Science.gov (United States)

    Wang, Chuan; Ryu, Koungmin; Badmaev, Alexander; Zhang, Jialu; Zhou, Chongwu

    2011-02-22

    Complementary metal-oxide semiconductor (CMOS) operation is very desirable for logic circuit applications as it offers rail-to-rail swing, larger noise margin, and small static power consumption. However, it remains to be a challenging task for nanotube-based devices. Here in this paper, we report our progress on metal contact engineering for n-type nanotube transistors and CMOS integrated circuits using aligned carbon nanotubes. By using Pd as source/drain contacts for p-type transistors, small work function metal Gd as source/drain contacts for n-type transistors, and evaporated SiO(2) as a passivation layer, we have achieved n-type transistor, PN diode, and integrated CMOS inverter with an air-stable operation. Compared with other nanotube n-doping techniques, such as potassium doping, PEI doping, hydrazine doping, etc., using low work function metal contacts for n-type nanotube devices is not only air stable but also integrated circuit fabrication compatible. Moreover, our aligned nanotube platform for CMOS integrated circuits shows significant advantage over the previously reported individual nanotube platforms with respect to scalability and reproducibility and suggests a practical and realistic approach for nanotube-based CMOS integrated circuit applications.

  11. A comparative evaluation on the emission characteristics of ceramic and metallic catalytic converter in internal combustion engine

    Science.gov (United States)

    Leman, A. M.; Jajuli, Afiqah; Rahman, Fakhrurrazi; Feriyanto, Dafit; Zakaria, Supaat

    2017-09-01

    Enforcement of a stricter regulation on exhaust emission by many countries has led to utilization of catalytic converter to reduce the harmful pollutant emission. Ceramic and metallic catalytic converters are the most common type of catalytic converter used. The purpose of this study is to evaluate the performance of the ceramic and metallic catalytic converter on its conversion efficiency using experimental measurement. Both catalysts were placed on a modified exhaust system equipped with a Mitshubishi 4G93 single cylinder petrol engine that was tested on an eddy current dynamometer under steady state conditions for several engine speeds. The experimental results show that the metallic catalytic converter reduced a higher percentage of CO up to 98.6% reduction emissions while ceramic catalytic converter had a better reduction efficiency of HC up to 85.4% and 87.2% reduction of NOx.

  12. Development of engineering parameters for the design of metal biosorption waste treatment systems

    Energy Technology Data Exchange (ETDEWEB)

    Graham, W.S.

    1991-12-03

    Untreated landfill leachates and wastes from metal plating and mining operations are sources of environmental contamination by heavy metals. Because of their toxicity and potential for accumulation, the discharge of heavy metals must be controlled. Standard physical and chemical treatments used to remove metals from wastes such as concentration by electro-precipitation, ion exchange, solvent extraction, evaporative recovery, and conventional precipitation, are usually expensive and produce high quantities of sludge. Biosorption is the removal of metals from aqueous solutions by microorganisms. It is called biosorption rather than bioadsorption or bioaccumulation because the mechanisms of removal are not restricted to adsorption or metabolic uptake and so the more general term is preferable and has come to be accepted. In this thesis the focus is one two microorganisms and two metals. However, the possible combinations of conditions such as pH, relative metal molarities, time of contact, and organism are numerous. These experiments are designed to provide optimized parameters to facilitate the design of a functioning biosorption system. The two metals chosen for study are copper and lead in aqueous solution. The two types of microorganisms chosen for testing include an actinomycete and a fungus. The purpose of this research is to identify the significant engineering parameters to be evaluated include reaction rates, equilibrium partitioning of metal ions between those in solution and those removed to the cells, optimum pH for achieving the removal or recovery goal, and biosorption selectivity for one metal over another.

  13. An AES Study of the Room Temperature Surface Conditioning of Technological Metal Surfaces by Electron Irradiation

    OpenAIRE

    Scheuerlein, C; Hilleret, Noël; Taborelli, M; Brown, A; Baker, M A

    2002-01-01

    The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis resu...

  14. Adsorption of metals on metal surfaces and the possibilities of its application in nuclear chemistry

    International Nuclear Information System (INIS)

    Roesch, F.; Eichler, B.

    1986-01-01

    Starting with values of differential enthalpies of adsorption ΔH-bar/sub a/ the desorption temperatures of 65 adsorptive metals as to 40 adsorbens metals have been obtained according to a model calculation. With regard to their potential separation by means of selective desorption from solid metal surfaces the desorption behaviour of combinations of radionuclides Me 1 (proton number Z)/Me 2 (proton number Z+1) and Me 1 (proton number Z)/Me 2 (proton number Z+2) was calculated. Basing on the parameters of the model assumptions, the results of the calculations allow estimations about the desorption temperatures of the adsorptive Me 1 as well as the temperature differences to the desorption of the adsorptive Me 2 and about the efficiency of the potential separation process. (author)

  15. Localized surface plasmon modes in a system of two interacting metallic cylinders

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Vergeles, Sergey S.; Vorobev, Petr E.

    2012-01-01

    We study an optical response of a system of two parallel close metallic cylinders having nanoscale dimensions. Surface plasmon excitation in the gap between the cylinders are specifically analyzed. In particular, resonance frequencies and field enhancement were investigated as functions of geomet......We study an optical response of a system of two parallel close metallic cylinders having nanoscale dimensions. Surface plasmon excitation in the gap between the cylinders are specifically analyzed. In particular, resonance frequencies and field enhancement were investigated as functions...... of geometrical characteristics of the system and Ohmic losses in the metal. The results of numerical simulations were systematically compared with the analytical theory, obtained in the quasi-static limit. The analytical method was generalized in order to take into account the retardation effects. We also...

  16. Metal-in-metal localized surface plasmon resonance

    Energy Technology Data Exchange (ETDEWEB)

    Smith, G B; Earp, A A, E-mail: g.smith@uts.edu.au [Department of Physics and Advanced Materials and Institute of Nanoscale Technology, University of Technology, Sydney, PO Box 123, Broadway NSW 2007 (Australia)

    2010-01-08

    Anomalous strong resonances in silver and gold nanoporous thin films which conduct are found to arise from isolated metal nano-islands separated from the surrounding percolating metal network by a thin loop of insulator. This observed resonant optical response is modelled. The observed peak position is in agreement with the observed average dimensions of the silver core and insulator shell. As the insulating ring thickness shrinks, the resonance moves to longer wavelengths and strengthens. This structure is the Babinet's principle counterpart of dielectric core-metal shell nanoparticles embedded in dielectric. Like for the latter, tuning of resonant absorption is possible, but here the matrix reflects rather than transmits, and tuning to longer wavelengths is more practical. A new class of metal mirror occurring as a single thin layer is identified using the same resonances in dense metal mirrors. Narrow band deep localized dips in reflectance result.

  17. Metal-in-metal localized surface plasmon resonance

    Science.gov (United States)

    Smith, G. B.; Earp, A. A.

    2010-01-01

    Anomalous strong resonances in silver and gold nanoporous thin films which conduct are found to arise from isolated metal nano-islands separated from the surrounding percolating metal network by a thin loop of insulator. This observed resonant optical response is modelled. The observed peak position is in agreement with the observed average dimensions of the silver core and insulator shell. As the insulating ring thickness shrinks, the resonance moves to longer wavelengths and strengthens. This structure is the Babinet's principle counterpart of dielectric core-metal shell nanoparticles embedded in dielectric. Like for the latter, tuning of resonant absorption is possible, but here the matrix reflects rather than transmits, and tuning to longer wavelengths is more practical. A new class of metal mirror occurring as a single thin layer is identified using the same resonances in dense metal mirrors. Narrow band deep localized dips in reflectance result.

  18. The interaction of bacteria and metal surfaces

    International Nuclear Information System (INIS)

    Mansfeld, Florian

    2007-01-01

    This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E corr became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V)-current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions

  19. The interaction of bacteria and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mansfeld, Florian [Corrosion and Environmental Effects Laboratory (CEEL), The Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241 (United States)

    2007-10-10

    This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E{sub corr} became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V) - current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions. (author)

  20. First-principles study of hydrogen dissociation and diffusion on transition metal-doped Mg(0 0 0 1) surfaces

    International Nuclear Information System (INIS)

    Wang, Zhiwen; Guo, Xinjun; Wu, Mingyi; Sun, Qiang; Jia, Yu

    2014-01-01

    First-principles calculations within the density functional theory (DFT) have been carried out to study hydrogen molecules dissociation and diffusion on clean and transition metals (TMs) doped Mg(0 0 0 1) surfaces following Pozzo et al. work. Firstly, the stability of Mg(0 0 0 1) surface doped with transition metals atom has been studied. The results showed that transition metals on the left of the table tend to substitute Mg in the second layer, while the other transition metals prefer to substitute Mg in the first layer. Secondly, we studied hydrogen molecules dissociation and diffusion on clean and Mg(0 0 0 1) surfaces which the transition metal atoms substituted both in the first layer and second layer. When transition metal atoms substitute in the first layer, the results agree with the Pozzo et al. result; when transition metal atoms substitute in the second layer, the results showed that the transition metals on the left of the periodic table impact on the dissociation barriers is less. However, for the transition metals (Mn, Fe, Co, Ni) on the right, there is a great impact on the barriers. The transition metals doped surfaces bind the dissociated H atoms loosely, making them easily diffused. The results further reveal that the Fe dopant on the Mg surface is the best choice for H 2 dissociation and hydrogen storage.

  1. Metals in bulk deposition and surface waters at two upland locations in northern England

    Energy Technology Data Exchange (ETDEWEB)

    Lawlor, A.J.; Tipping, E

    2003-02-01

    Surface water concentrations of potentially-toxic metals depend upon atmospheric deposition and catchment biogeochemical processes. - Concentrations of aluminium and minor metals (Mn, Ni, Cu, Zn, Sr, Cd, Ba, Pb) were measured in precipitation and surface water at two upland locations (Upper Duddon Valley, UDV; Great Dun Fell, GDF) in northern England for 1 year commencing April 1998. At both locations, the loads in bulk precipitation were at the lower ends of ranges reported for other rural and remote sites, for the period 1985-1995. The deposited metals were mostly in the dissolved form, and their concentrations tended to be greatest when rainfall volumes were low. The concentrations of Cu, Zn and Pb in deposition were correlated (r{sup 2}{>=}0.40) with concentrations of non-marine sulphate. Three streams, ranging in mean pH from 5.07 to 7.07, and with mean concentrations of dissolved organic carbon (DOC) <1 mg l{sup -1}, were monitored at UDV, and two pools (mean pH 4.89 and 6.83, mean DOC 22 and 15 mg l{sup -1}) at GDF. Aluminium and the minor metals were mainly in the dissolved form, and in the following ranges (means of 49-51 samples, {mu}g l{sup -1}): Al 36-530, Mn 4.4-36, Ni 0.26-2.8, Cu 0.25-1.7, Zn 2.1-30, Cd 0.03-0.16, Ba 1.9-140, Pb 0.10-4.5. Concentrations were generally higher at GDF. Differences in metal concentrations between the two locations and between waters at each location, and temporal variations in individual waters, can be explained qualitatively in terms of sorption to solid-phase soil organic matter and mineral surfaces, complexation and transport by DOC, and chemical weathering. The UDV catchments are sinks for Pb and sources of Al, Mn, Sr, Cd and Ba. The GDF catchments are sources of Al, Mn, Ni, Zn, Sr, Cd and Ba. Other metals measured at the two locations are approximately in balance. Comparison of metal:silicon ratios in the surface waters with values for silicate rocks indicates enrichment of Ni and Cu, and substantial enrichment of

  2. Modification of solid surface by intense pulsed light-ion and metal-ion beams

    Science.gov (United States)

    Nakagawa, Y.; Ariyoshi, T.; Hanjo, H.; Tsutsumi, S.; Fujii, Y.; Itami, M.; Okamoto, A.; Ogawa, S.; Hamada, T.; Fukumaru, F.

    1989-03-01

    Metal surfaces of Al, stainless-steel and Ti were bombarded with focused intense pulsed proton and carbon ion beams (energy ˜ 80 keV, current density ≲ 1000 A/cm 2, pulse width ˜ 300 ns). Thin titanium carbide layers were produced by carbon-ion irradiation on the titanium surface. The observed molten surface structures and recrystallized layer (20 μm depth) indicated that the surfaces reached high temperatures as a result of the irradiation. The implantation of intense pulsed metal ion beams (Al +, ˜ 20 A/cm 2) with simultaneous deposition of anode metal vapor on Ti and Fe made a mixed layer of AlTi and AlFe of about 0.5 μm depth. Ti and B multilayered films evaporated on glass substrates were irradiated by intense pulsed proton beams of relatively lower current density (10-200 A/cm 2). Ti films containing B atoms above 10 at.% were obtained. When the current density was about 200 A/cm 2 diffraction peaks of TiB 2 appeared.

  3. Protein consensus-based surface engineering (ProCoS): a computer-assisted method for directed protein evolution.

    Science.gov (United States)

    Shivange, Amol V; Hoeffken, Hans Wolfgang; Haefner, Stefan; Schwaneberg, Ulrich

    2016-12-01

    Protein consensus-based surface engineering (ProCoS) is a simple and efficient method for directed protein evolution combining computational analysis and molecular biology tools to engineer protein surfaces. ProCoS is based on the hypothesis that conserved residues originated from a common ancestor and that these residues are crucial for the function of a protein, whereas highly variable regions (situated on the surface of a protein) can be targeted for surface engineering to maximize performance. ProCoS comprises four main steps: ( i ) identification of conserved and highly variable regions; ( ii ) protein sequence design by substituting residues in the highly variable regions, and gene synthesis; ( iii ) in vitro DNA recombination of synthetic genes; and ( iv ) screening for active variants. ProCoS is a simple method for surface mutagenesis in which multiple sequence alignment is used for selection of surface residues based on a structural model. To demonstrate the technique's utility for directed evolution, the surface of a phytase enzyme from Yersinia mollaretii (Ymphytase) was subjected to ProCoS. Screening just 1050 clones from ProCoS engineering-guided mutant libraries yielded an enzyme with 34 amino acid substitutions. The surface-engineered Ymphytase exhibited 3.8-fold higher pH stability (at pH 2.8 for 3 h) and retained 40% of the enzyme's specific activity (400 U/mg) compared with the wild-type Ymphytase. The pH stability might be attributed to a significantly increased (20 percentage points; from 9% to 29%) number of negatively charged amino acids on the surface of the engineered phytase.

  4. Science and engineering of nanodiamond particle surfaces for biological applications (Review).

    Science.gov (United States)

    Shenderova, Olga A; McGuire, Gary E

    2015-09-05

    Diamond has outstanding bulk properties such as super hardness, chemical inertness, biocompatibility, luminescence, to name just a few. In the nanoworld, in order to exploit these outstanding bulk properties, the surfaces of nanodiamond (ND) particles must be accordingly engineered for specific applications. Modification of functional groups on the ND's surface and the corresponding electrostatic properties determine their colloidal stability in solvents, formation of photonic crystals, controlled adsorption and release of cargo molecules, conjugation with biomolecules and polymers, and cellular uptake. The optical activity of the luminescent color centers in NDs depends on their proximity to the ND's surface and surface termination. In order to engineer the ND surface, a fundamental understanding of the specific structural features and sp(3)-sp(2) phase transformations on the surface of ND particles is required. In the case of ND particles produced by detonation of carbon containing explosives (detonation ND), it should also be taken into account that its structure depends on the synthesis parameters and subsequent processing. Thus, for development of a strategy of surface modification of detonation ND, it is imperative to know details of its production. In this review, the authors discuss ND particles structure, strategies for surface modification, electrokinetic properties of NDs in suspensions, and conclude with a brief overview of the relevant bioapplications.

  5. Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

    International Nuclear Information System (INIS)

    Chen, Chih-Hao; Lee, Ming-Yih; Shyu, Victor Bong-Hang; Chen, Yi-Chieh; Chen, Chien-Tzung; Chen, Jyh-Ping

    2014-01-01

    Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction. - Highlights: • Selective laser sintered polycaprolactone scaffolds are prepared. • Scaffolds are surface modified through immersion coating with gelatin or collagen. • Collagen-scaffold is the best for cartilage tissue engineering in vitro. • Chondrocytes/collagen-scaffold reveals enhanced cartilage tissue formation in vivo

  6. Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chih-Hao [Department of Chemical and Materials Engineering, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Craniofacial Research Center, Chang Gung University, Kweishann, Taoyuan 333, Taiwan, ROC (China); Lee, Ming-Yih [Graduate Institute of Medical Mechatronics, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Shyu, Victor Bong-Hang; Chen, Yi-Chieh; Chen, Chien-Tzung [Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Craniofacial Research Center, Chang Gung University, Kweishann, Taoyuan 333, Taiwan, ROC (China); Chen, Jyh-Ping, E-mail: jpchen@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kweishan, Taoyuan 333, Taiwan, ROC (China)

    2014-07-01

    Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction. - Highlights: • Selective laser sintered polycaprolactone scaffolds are prepared. • Scaffolds are surface modified through immersion coating with gelatin or collagen. • Collagen-scaffold is the best for cartilage tissue engineering in vitro. • Chondrocytes/collagen-scaffold reveals enhanced cartilage tissue formation in vivo.

  7. Finite Element Method Simulations of the Near-Field Enhancement at the Vicinity of Fractal Rough Metallic Surfaces

    International Nuclear Information System (INIS)

    Micic, Miodrag; Klymyshyn, Nicholas A.; Lu, H Peter

    2004-01-01

    Near-field optical enhancement at metal surfaces and methods such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescent quenching and enhancement, and various near-field scanning microscopies (NSOM) all depend on a metals surface properties, mainly on its morphology and SPR resonant frequency. We report on simulations of the influence of different surface morphologies on electromagnetic field enhancements at the rough surfaces of noble metals and also evaluate the optimal conditions for the generation of a surface-enhanced Raman signal of absorbed species on a metallic substrate. All simulations were performed with a classical electrodynamics approach using the full set of Maxwells equations, which were solved with the three-dimensional finite element method (FEM). Two different classes of surfaces where modeled using fractals, representing diffusion limited aggregation growth dendritic structures, such as one on the surface of electrodes, and second one representing the sponge-like structure used to model surfaces of particles with high porosity, such as metal coated catalyst supports. The simulations depict the high inhomogeneity of an enhanced electromagnetic field as both a field enhancement and field attenuation near the surface. While the diffusion limited aggregation dendritical fractals enhanced the near-field electromagnetic field, the sponge fractals significantly reduced the local electromagnetic field intensity. Moreover, the fractal orders of the fractal objects did not significantly alter the total enhancement, and the distribution of a near-field enhancement was essentially invariant to the changes in the angle of an incoming laser beam

  8. Atomistic modeling of metal surfaces under electric fields: direct coupling of electric fields to a molecular dynamics algorithm

    CERN Document Server

    Djurabekova, Flyura; Pohjonen, Aarne; Nordlund, Kai

    2011-01-01

    The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms of ionization of surface atoms observed at very high electric fields, as well as the general behavior of a metal surface in this condition. However, the derivation of analytical models does not include explicitly the structural properties of metals, missing the link between the instantaneous effects owing to the applied field and the consequent response observed in the metal surface as a result of an extended application of an electric field. In the present work, we have developed a concurrent electrodynamic–molecular dynamic model for the dynamical simulation of an electric-field effect and subsequent modification of a metal surface in the framework of an atomistic molecular dynamics (MD) approach. The partial charge induced on the surface atoms by the electric field is assessed by applying the classical Gauss law. The electric forces acting on the partially...

  9. Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

    Science.gov (United States)

    Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

    2013-10-01

    Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10-40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage.

  10. Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

    Science.gov (United States)

    Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

    2013-01-01

    Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10–40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage. PMID:24145684

  11. Laser assisted decontamination of metal surface: Evidence of increased surface absorptivity due to field enhancement caused by transparent/semi-transparent contaminant particulates

    International Nuclear Information System (INIS)

    Nilaya, J. Padma; Biswas, Dhruba J.

    2010-01-01

    Small signal absorption measurements of the incident coherent radiation by the metal surface have revealed an increase in the absorption by the surface in presence of transparent/semi-transparent particulates on it. This effect, identified as field enhanced surface absorption, has been found to increase with reduction in the average particulate size. Consequently higher laser assisted removal efficiency of contamination from a metal surface has been observed for smaller contaminant particulates. These measurements have been carried out utilizing coherent radiations of two different wavelengths so chosen that for one the particulates are totally transparent while for the other they are partially transparent.

  12. Adsorption and dissociation of dinitrogen on transition metal (Ta, W and Re) doped MgO surface

    KAUST Repository

    Yadav, Manoj Kumar; Vovusha, Hakkim; Sanyal, Biplab

    2016-01-01

    The adsorption and dissociation of dinitrogen on transition metal (Ta, W and Re) doped MgO(100) surface has been studied employing density functional theory. It is found that all these transition metals (TM) on MgO(100) surface are capable

  13. Structural and vibrational studies of clean and chemisorbed metal surfaces

    International Nuclear Information System (INIS)

    Jiang, Qing-Tang.

    1992-01-01

    Using Medium Energy Ion Scattering, we have studied the structural and vibrational properties of a number of clean and chemisorbed metal surfaces. The work presented in this thesis is mainly of a fundamental nature. However, it is believed that an atomistic understanding of the forces that affect surface structural and vibrational properties can have a beneficial impact on a large number of areas of applied nature. We find that the surface structure of Cu(001) follows the common trend for metal surfaces, where a small oscillatory relaxation exists beginning with a slight contraction in the top layer. In addition, the surface vibrational amplitude is enhanced (as s usually the case) by ∼80%. A detailed analysis of our data shows an unexpected anisotropy of the vibrational amplitude, such that the out-of-plane vibrational amplitude is 30% smaller than the in-plane vibrational amplitude. The unexpected results may imply a large tensile stress on Cu(001). Upon adsorption of 1/4 of a monolayer of S, a p(2 x 2)-S/Cu(001) surface is created. This submonolayer amount of S atoms makes the surface bulk-like, in which the anisotropy of the surface vibrations is removed and the first interlayer contraction is lifted. By comparing our model to earlier contradictory results on this controversial system. We find excellent agreement with a recent LEED study. The presence of 0.1 monolayer of Ca atoms on the Au(113) surface induces a drastic atomic rearrangements, in which half of the top layer Au atoms are missing and a (1 x 2) symmetry results. In addition, the first interlayer spacing of Au(113) is significantly reduced. Our results are discussed in terms of the energy balance between competing surface electronic charge densities

  14. Many-body dispersion effects in the binding of adsorbates on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, Reinhard J. [Department of Chemistry, Yale University, New Haven, Connecticut 06520 (United States); Ruiz, Victor G.; Tkatchenko, Alexandre [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

    2015-09-14

    A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic–inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate–surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches.

  15. Surface layers in the 4A group metals with implanted silicon ions

    International Nuclear Information System (INIS)

    Kovneristyj, Yu.K.; Vavilova, V.V.; Krasnopevtsev, V.V.; Galkin, L.N.; Kudyshev, A.N.; Klechkovskaya, V.V.

    1987-01-01

    A study was made on the change of structure and phase composition of fine near the surface layers of 4A group metals (Hf, Zr, Ti) during ion Si implantation and successive thermal annealing at elevated temperatures. Implantation of Si + ions with 30 or 16 keV energy in Ti, Zr and Hf at room temperature results to amorphization of metal surface layer. The surface hafnium and titanium layer with implanted Si atoms due to interaction with residual atmosphere of oxygen turns during annealing at 870 K to amorphous solid solution of HfO 2m or TiO 2 with Si, preventing further metal oxidation; layers of amorphous alloy are characterized by thermal stability up to 1270 K. Oxidation of the surface amorphous layer in residual oxygen atmosphere and its crystallization in ZrO 2 take place in result of Zr annealing with implanted Si ions at temperature not exceeding 870 K. Similar phenomena are observed in the case of hafnium with implanted oxygen ions or small dose of silicon ions. Thermal stability of amorphous layers produced during ion implantation of Si in Ti, Zr and Hf corresponds to scale resistance of monolithic alloys in Ti-Si, Zr-Si and Hf-Si systems

  16. In situ metalation of free base phthalocyanine covalently bonded to silicon surfaces

    Directory of Open Access Journals (Sweden)

    Fabio Lupo

    2014-11-01

    Full Text Available Free 4-undecenoxyphthalocyanine molecules were covalently bonded to Si(100 and porous silicon through thermic hydrosilylation of the terminal double bonds of the undecenyl chains. The success of the anchoring strategy on both surfaces was demonstrated by the combination of X-ray photoelectron spectroscopy with control experiments performed adopting the commercially available 2,3,9,10,16,17,23,24-octakis(octyloxy-29H,31H-phthalocyanine, which is not suited for silicon anchoring. Moreover, the study of the shape of the XPS N 1s band gave relevant information on the interactions occurring between the anchored molecules and the substrates. The spectra suggest that the phthalocyanine ring interacts significantly with the flat Si surface, whilst ring–surface interactions are less relevant on porous Si. The surface-bonded molecules were then metalated in situ with Co by using wet chemistry. The efficiency of the metalation process was evaluated by XPS measurements and, in particular, on porous silicon, the complexation of cobalt was confirmed by the disappearance in the FTIR spectra of the band at 3290 cm−1 due to –NH stretches. Finally, XPS results revealed that the different surface–phthalocyanine interactions observed for flat and porous substrates affect the efficiency of the in situ metalation process.

  17. Predicting supramolecular self-assembly on reconstructed metal surfaces

    Science.gov (United States)

    Roussel, Thomas J.; Barrena, Esther; Ocal, Carmen; Faraudo, Jordi

    2014-06-01

    The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule-molecule interactions are enhanced in a way that long-range order is promoted. Also, the presence of a distortion in a reconstructed surface pattern not only induces the presence of long-range order but also is able to drive the organization of DIP into two coexisting homochiral domains, in quantitative agreement with STM experiments. On the other hand, only short range order is obtained in other reconstructions of the Au(111) surface. The simulation strategy opens interesting perspectives to tune the supramolecular structure by simulation design and surface engineering if choosing the right molecular building blocks and stabilising the chosen reconstruction pattern.The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule

  18. Study of UV surface plasmons on metallic nanostructures and its applications to nanophotonics

    Science.gov (United States)

    Zhou, Liangcheng

    Modern nanotechnology requires the characterization ability in the order of 100 nm or smaller. This resolution requirement cannot be met by using conventional optical microscopy. Nowadays, the mainstream technique that is universally adopted to characterize optical properties on this length scale is Near-field Scanning Optical Microscopy (NSOM). In the effort to improve the resolution and efficiency of NSOM techniques, both nanoscopic fabrication and imaging techniques are critical because the light field strongly intereacts with the metallic NSOM probe or other surfaces to form surface plasmons (SPs). However, much is still unknown about the behavior of light interacting with metallic nanostructures. This calls for research that develops the tool set, methodology and that includes both experimental characterization, and numerical simulations, for the investigation of SPs. The short wavelength of UV light makes it particularly desirable for many industrial processes. So far, little research has been carried out to understand surface plasmon in the UV spectral region. Like conventional optics, UV SPs have unique properties and optical behavior. For this purpose, we modified our existing NSOM into a Photon Scanning Tunneling Microscope (PTSM) and demonstrate its power for the imaging of UV SPs. We present what we believe to be the first direct mapping of the UV SPs on an Al2O3/Al surface. UV SP modes launched by one-dimensional slits or two-dimensional groove arrays and corresponding interference phenomenon were both observed. We then use the same methodology in the engineering of optimized nano aperture such as UV bowtie nanoantenna. For the latter, we find a strong UV intensity profile which is localized to less than 50nm caused by a localized surface plasmon resonance. The relationship of optical field enhancement and antenna geometric shape is studied using numerical simulations and NSOM experiments. In another project, we examine the propagation of light from

  19. Colonization by Cladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

    Science.gov (United States)

    Ahearn, D. G.; Simmons, R. B.; Switzer, K. F.; Ajello, L.; Pierson, D. L.

    1991-01-01

    Cladosporium cladosporioides and C. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.

  20. Interference effects in plasom excitation by particles reflected near a metal surface

    International Nuclear Information System (INIS)

    Denton, C.D.; Gervasoni, J.L.; Barrachina, R.O.; Arista, N.R.; Universidad Nacional de Cuyo, Mendoza

    1993-01-01

    Using the dielectric formalism and the specular reflection model, we evaluate the probability of surface and bulk plasmon excitation by particles reflected in the proximity of a metal surface. We obtain a strong oscillatory behaviour as a function of the penetration distance. (author)

  1. Laser surface alloying of aluminium with WC+Co+NiCr for improved wear resistance

    CSIR Research Space (South Africa)

    Nath, S

    2012-03-01

    Full Text Available Department of Metallurgical & Materials Engineering, IIT Kharagpur, West Bengal, India 2National Laser Centre, CSIR, Pretoria, South Africa Abstract In the present study, laser surface alloying of aluminium with WC+Co+NiCr (in the ratio of 70... be used for dispersion of ceramic materials into metallic matrix and hence, form a ceramic dispersed metal matrix composite on metallic substrate [3]. The advantages of laser surface alloying include refinement of the microstructure, uniform dispersion...

  2. Topological states in a two-dimensional metal alloy in Si surface: BiAg/Si(111)-4 ×4 surface

    Science.gov (United States)

    Zhang, Xiaoming; Cui, Bin; Zhao, Mingwen; Liu, Feng

    2018-02-01

    A bridging topological state with a conventional semiconductor platform offers an attractive route towards future spintronics and quantum device applications. Here, based on first-principles and tight-binding calculations, we demonstrate the existence of topological states hosted by a two-dimensional (2D) metal alloy in a Si surface, the BiAg/Si(111)-4 ×4 surface, which has already been synthesized experimentally. It exhibits a topological insulating state with an energy gap of 71 meV (˜819 K ) above the Fermi level and a topological metallic state with quasiquantized conductance below the Fermi level. The underlying mechanism leading to the formation of such nontrivial states is revealed by analysis of the "charge-transfer" and "orbital-filtering" effect of the Si substrate. A minimal effective tight-binding model is employed to reveal the formation mechanism of the topological states. Our finding opens opportunities to detect topological states and measure its quantized conductance in a large family of 2D surface metal alloys, which have been or are to be grown on semiconductor substrates.

  3. Metals content in surface waters of an upwelling system of the northern Humboldt Current (Mejillones Bay, Chile)

    Science.gov (United States)

    Valdés, Jorge; Román, Domingo; Alvarez, Gabriel; Ortlieb, Luc; Guiñez, Marcos

    Physical-chemical parameters (temperature, salinity, dissolved oxygen, nutrients, and chlorophyll concentration) of surface waters were used to evaluate the influence of biological and physical processes over the metal concentrations (Cd, Ni, V, Mo, Mn, and Fe) in different periods of a normal annual cycle (June 2002 and April 2003), in Mejillones Bay (23° S), one of northern Chile's strongest upwelling cells. Two points were sampled every 2 months, but statistical analysis of these parameters did not show any spatial differences in surface water composition (annual average) in this bay. The order of total and dissolved metals by abundance (annual mean) in the Mejillones Bay surface waters during the sampling period was Cd Oxygen Minimum Zone which characterizes the Mejillones bay should have an important influence on surface distribution of trace metals and can explain the high temporal variability observed in most of the metals analyzed in this work. A two-box conceptual model is proposed to suggest possible influences on metals in surface waters of this coastal ecosystem.

  4. Ion beam analysis of metal ion implanted surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.

  5. Ion beam analysis of metal ion implanted surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P J; Chu, J W; Johnson, E P; Noorman, J T [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D K [Royal Melbourne Inst. of Tech., VIC (Australia)

    1994-12-31

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.

  6. Ion beam analysis of metal ion implanted surfaces

    International Nuclear Information System (INIS)

    Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T.; Sood, D.K.

    1993-01-01

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs

  7. Topography evolution of rough-surface metallic substrates by solution deposition planarization method

    Science.gov (United States)

    Chu, Jingyuan; Zhao, Yue; Liu, Linfei; Wu, Wei; Zhang, Zhiwei; Hong, Zhiyong; Li, Yijie; Jin, Zhijian

    2018-01-01

    As an emerging technique for surface smoothing, solution deposition planarization (SDP) has recently drawn more attention on the fabrication of the second generation high temperature superconducting (2G-HTS) tapes. In our work, a number of amorphous oxide layers were deposited on electro-polished or mirror-rolled metallic substrates by chemical solution route. Topography evolution of surface defects on these two types of metallic substrates was thoroughly investigated by atomic force microscopy (AFM). It was showed that root mean square roughness values (at 50 × 50 μm2 scanning scale) on both rough substrates reduced to ∼5 nm after coating with SDP-layer. The smoothing effect was mainly attributed to decrease of the depth at grain boundary grooving on the electro-polished metallic substrate. On the mirror-rolled metallic substrates, the amplitude and frequency of the height fluctuation perpendicular to the rolling direction were gradually reduced as depositing more numbers of SDP-layer. A high Jc value of 4.17 MA cm-2 (at 77 K, s.f.) was achieved on a full stack of YBCO/CeO2/IBAD-MgO/SDP-layer/C276 sample. This study enhanced understanding of the topography evolution on the surface defects covered by the SDP-layer, and demonstrated a low-cost route for fabricating IBAD-MgO based YBCO templates with a simplified architecture.

  8. Morphing and vectoring impacting droplets by means of wettability-engineered surfaces.

    Science.gov (United States)

    Schutzius, Thomas M; Graeber, Gustav; Elsharkawy, Mohamed; Oreluk, James; Megaridis, Constantine M

    2014-11-13

    Driven by its importance in nature and technology, droplet impact on solid surfaces has been studied for decades. To date, research on control of droplet impact outcome has focused on optimizing pre-impact parameters, e.g., droplet size and velocity. Here we follow a different, post-impact, surface engineering approach yielding controlled vectoring and morphing of droplets during and after impact. Surfaces with patterned domains of extreme wettability (high or low) are fabricated and implemented for controlling the impact process during and even after rebound--a previously neglected aspect of impact studies on non-wetting surfaces. For non-rebound cases, droplets can be morphed from spheres to complex shapes--without unwanted loss of liquid. The procedure relies on competition between surface tension and fluid inertial forces, and harnesses the naturally occurring contact-line pinning mechanisms at sharp wettability changes to create viable dry regions in the spread liquid volume. Utilizing the same forces central to morphing, we demonstrate the ability to rebound orthogonally-impacting droplets with an additional non-orthogonal velocity component. We theoretically analyze this capability and derive a We(-.25) dependence of the lateral restitution coefficient. This study offers wettability-engineered surfaces as a new approach to manipulate impacting droplet microvolumes, with ramifications for surface microfluidics and fluid-assisted templating applications.

  9. Production of metal fullerene surface layer from various media in the process of steel carbonization

    Directory of Open Access Journals (Sweden)

    KUZEEV Iskander Rustemovich

    2018-04-01

    Full Text Available Studies devoted to production of metal fullerene layer in steels when introducing carbon from organic and inorganic media were performed. Barium carbonate was used as an inorganic medium and petroleum pitch was used as an organic medium. In order to generate the required amount of fullerenes in the process of steel samples carbonization, optimal temperature mode was found. The higher temperature, absorption and cohesive effects become less important and polymeric carbon structures destruction processes become more important. On the bottom the temperature is limited by petroleum pitch softening temperature and its transition to low-viscous state in order to enhance molecular mobility and improve the possibility of their diffusion to metal surface. Identification of fullerenes in the surface modified layer was carried out following the methods of IR-Fourier spectrometry and high-performance liquid chromatography. It was found out that nanocarbon structures, formed during carbonization in barium carbonate and petroleum pitch mediums, possess different morphology. In the process of metal carbonization from carbonates medium, the main role in fullerenes synthesis is belonged to catalytic effect of surface with generation of endohedral derivatives in the surface layer; but in the process of carbonization from pitch medium fullerenes are formed during crystallization of the latter and crystallization centers are of fullerene type. Based on theoretical data and dataof spectral and chromatographic analysis, optimal conditions of metal fullerene layer formation in barium carbonate and petroleum pitch mediums were determined. Low cohesion of layer, modified in barium carbonate medium, with metal basis was discovered. That was caused by limited carbon diffusion in the volume of α-Fe. According to the detected mechanism of fullerenes formation on steel surface in gaseous medium, fullerenes are formed on catalytic centers – ferrum atoms, forming thin metal

  10. Engineering the metal sensitive sites in Macrolampis sp2 firefly luciferase and use as a novel bioluminescent ratiometric biosensor for heavy metals.

    Science.gov (United States)

    Gabriel, Gabriele V M; Viviani, Vadim R

    2016-12-01

    Most luminescent biosensors for heavy metals are fluorescent and rely on intensity measurements, whereas a few are ratiometric and rely on spectral changes. Bioluminescent biosensors for heavy metals are less common. Firefly luciferases have been coupled to responsive promoters for mercury and arsenium, and used as light on biosensors. Firefly luciferase bioluminescence spectrum is naturally sensitive to heavy metal cations such as zinc and mercury and to pH. Although pH sensitivity of firefly luciferases was shown to be useful for ratiometric estimation of intracellular pH, its potential use for ratiometric estimation of heavy metals was never considered. Using the yellow-emitting Macrolampis sp2 firefly luciferase and site-directed mutagenesis, we show that the residues H310 and E354 constitute two critical sites for metal sensitivity that can be engineered to increase sensitivity to zinc, nickel, and mercury. A linear relationship between cation concentration and the ratio of bioluminescence intensities at 550 and 610 nm allowed, for the first time, the ratiometric estimation of heavy metals concentrations down to 0.10 mM, demonstrating the potential applicability of firefly luciferases as enzymatic and intracellular ratiometric metal biosensors.

  11. Deposition and characterization of noble metal onto surfaces of 304l stainless steel

    International Nuclear Information System (INIS)

    Contreras R, A.; Arganis J, C. R.; Aguilar T, J. A.; Medina A, A. L.

    2010-10-01

    Noble metal chemical addition (NMCA) plus hydrogen water chemistry is an industry-wide accepted approach for potential intergranular stress corrosion cracking mitigation of BWR internals components. NMCA is a method of applying noble metal onto BWR internals surfaces using reactor water as the transport medium that causes the deposition of noble metal from the liquid onto surfaces. In this work different platinum concentration solutions were deposited onto pre-oxidized surfaces of 304l steel at 180 C during 48 hr in an autoclave. In order to simulate the zinc water conditions, deposits of Zn and Pt-Zn were also carried out. The solutions used to obtain the deposits were: sodium hexahydroxyplatinate (IV), zinc nitrate hydrate and zinc oxide. The deposits obtained were characterized by scanning electron microscopy and X-ray diffraction. Finally, the electrochemical corrosion potential of pre-oxidized samples with Pt deposit were obtained and compared with the electrochemical corrosion potential of only pre-oxidized samples. (Author)

  12. Engineered Chimeric Peptides as Antimicrobial Surface Coating Agents toward Infection-Free Implants.

    Science.gov (United States)

    Yazici, Hilal; O'Neill, Mary B; Kacar, Turgay; Wilson, Brandon R; Oren, E Emre; Sarikaya, Mehmet; Tamerler, Candan

    2016-03-02

    Prevention of bacterial colonization and consequent biofilm formation remains a major challenge in implantable medical devices. Implant-associated infections are not only a major cause of implant failures but also their conventional treatment with antibiotics brings further complications due to the escalation in multidrug resistance to a variety of bacterial species. Owing to their unique properties, antimicrobial peptides (AMPs) have gained significant attention as effective agents to combat colonization of microorganisms. These peptides have been shown to exhibit a wide spectrum of activities with specificity to a target cell while having a low tendency for developing bacterial resistance. Engineering biomaterial surfaces that feature AMP properties, therefore, offer a promising approach to prevent implant infections. Here, we engineered a chimeric peptide with bifunctionality that both forms a robust solid-surface coating while presenting antimicrobial property. The individual domains of the chimeric peptides were evaluated for their solid-binding kinetics to titanium substrate as well as for their antimicrobial properties in solution. The antimicrobial efficacy of the chimeric peptide on the implant material was evaluated in vitro against infection by a variety of bacteria, including Streptococcus mutans, Staphylococcus. epidermidis, and Escherichia coli, which are commonly found in oral and orthopedic implant related surgeries. Our results demonstrate significant improvement in reducing bacterial colonization onto titanium surfaces below the detectable limit. Engineered chimeric peptides with freely displayed antimicrobial domains could be a potential solution for developing infection-free surfaces by engineering implant interfaces with highly reduced bacterial colonization property.

  13. Possibilities of a metal surface radioactive decontamination using a pulsed CO2 laser

    Science.gov (United States)

    Milijanic, Scepan S.; Stjepanovic, Natasa N.; Trtica, Milan S.

    2000-01-01

    There is a growing interest in the laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. A main mechanism of cleaning in by lasers is ablation. In this work a pulsed TEA CO2 laser was used for surface cleaning, primarily in order to demonstrate that the ablation from metal surfaces with this laser is possible even with relatively low pulse energies, and secondary, that it could be competitive with other lasers because of much higher energy efficiencies. The laser pulse contains two parts, one strong and shot peak at the beginning, followed with a tail. The beam was focused onto a contaminated surface with a KBr lens. The surface was contaminated with 137Cs. Three different metals were used: stainless steel, copper and aluminum. The evaporated material was pumped out in air atmosphere and transferred to a filter. Presence of the activity on the filter was proved by a germanium detector-multichannel analyzer. Activity levels were measured by a GM counter. Calculated decontamination factors as well as collection factors have shown that ablation takes place with relatively high efficiency of decontamination. This investigation suggests that decontamination using the CO2 laser should be seriously considered.

  14. Enhancement of Engine Oil Wear and Friction Control Performance Through Titanium Additive Chemistry

    International Nuclear Information System (INIS)

    Guevremont, J.; Guinther, G.; Szemenyei, D.; Devlin, M.; Jao, T.; Jaye, C.; Woicik, J.; Fischer, D.

    2008-01-01

    Traditionally, wear protection and friction modification by engine oil is provided by zinc dithiophosphate (ZDDP) or other phosphorus compounds. These additives provide effective wear protection and friction control on engine parts through formation of a glassy polyphosphate antiwear film. However, the deposition of phosphorus species on automotive catalytic converters from lubricants has been known for some time to have a detrimental effect of poisoning the catalysts. To mitigate the situation, the industry has been making every effort to find ZDDP-replacement additives that are friendly to catalysts. Toward this goal we have investigated a titanium additive chemistry as a ZDDP replacement. Fully formulated engine oils incorporating this additive component have been found to be effective in reducing wear and controlling friction in a high-frequency reciprocating rig (HFRR), 4-ball bench wear, Sequence IIIG, and Sequence IVA engine tests. Surface analysis of the tested parts by Auger electron spectroscopy, secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS) have shown that Ti species have been incorporated into the wear tracks and can only be found on the wear tracks. We used synchrotron based near edge X-ray absorption fine structure (NEXAFS) to investigate the chemical bonding mechanism of the Ti additive with the metal surface that affects the wear improvement mechanism. We postulate that Ti provides antiwear enhancement through inclusion in the metal/metal oxide structure of the ferrous surface by forming FeTiO3.

  15. No contaminant methods for the bio films formation control on metallic surfaces of industrial interest

    International Nuclear Information System (INIS)

    Gomez de Saravia, S. G.; Guiamet, P. S.

    2003-01-01

    The aim of this paper was the control of aerobic and anaerobic bacterial biofilms formation on metal surfaces of industrial interest such as stainless steel and mild steel. A natural biocida obtained of an aqueous extract of seeds of black mustard (Brassica nigra) and mixtures of immunoglobulins IgA, IgG, and IgM were used. Microscopic techniques like scanning electron microscopy (SEM) and epifluorescens microscopy were used for observing bacterial adhesion of the metal surfaces. A marked inhibition of bacterial adherence was observed when an immunoglobulin film was formed on the metal surface. When the natural biocide was used, an important decrease in the number of microorganisms in the biofilms was observed. (Author) 8 refs

  16. Nanoscale patterning of two metals on silicon surfaces using an ABC triblock copolymer template.

    Science.gov (United States)

    Aizawa, Masato; Buriak, Jillian M

    2006-05-03

    Patterning technologically important semiconductor interfaces with nanoscale metal films is important for applications such as metallic interconnects and sensing applications. Self-assembling block copolymer templates are utilized to pattern an aqueous metal reduction reaction, galvanic displacement, on silicon surfaces. Utilization of a triblock copolymer monolayer film, polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO), with two blocks capable of selective transport of different metal complexes to the surface (PEO and P2VP), allows for chemical discrimination and nanoscale patterning. Different regions of the self-assembled structure discriminate between metal complexes at the silicon surface, at which time they undergo the spontaneous reaction at the interface. Gold deposition from gold(III) compounds such as HAuCl4(aq) in the presence of hydrofluoric acid mirrors the parent block copolymer core structure, whereas silver deposition from Ag(I) salts such as AgNO3(aq) does the opposite, localizing exclusively under the corona. By carrying out gold deposition first and silver second, sub-100-nm gold features surrounded by silver films can be produced. The chemical selectivity was extended to other metals, including copper, palladium, and platinum. The interfaces were characterized by a variety of methods, including scanning electron microscopy, scanning Auger microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy.

  17. Promotion effect of monovalent metals (K and Cs) on the GaAs (110) surface oxidation

    International Nuclear Information System (INIS)

    Valeri, S.; Sberveglieri, P.; Angeli, E.

    1987-01-01

    The effect of thin (∼ 1 monolayer) overlayers of low electronegativity metals (Cs and K) on the RT oxidation behaviour of GaAs(110) cleavage surface is studied. This study was with Auger and Photoemission spectroscopies. Attention has been focused on the core-valence-valence and Auger lineshapes on the Ga and As 3d peaks. Presence of the alkali metal enhances the GaAs (110) oxidation rate several orders of magnitude above the clean surface value has been found. The range 0-100 Langmuir is investigated in detail. The oxidation process of the GaAs(110) surface in the presence of both K and Cs overlayer follows a multi-step kinetic and reaches a saturation at exposure lower than 100 Langmuir. Both Ga and As atoms are involved in the oxygen bonding. The metal enhanced semiconductor oxidation is generally reported to be a process involving predominantly the semiconductor surface atoms. However in the Cs - and K - GaAs case, an involvement of the alkali metal atoms too, reflected in the shape modification of their Auger line has been found. The promotion effect of K and Cs is discussed in terms of their low electronegativity and in comparison with the results recently reported in the literature for the other low electronegativity metals

  18. Electrostatic energy and screened charge interaction near the surface of metals with different Fermi surface shape

    Science.gov (United States)

    Gabovich, A. M.; Il'chenko, L. G.; Pashitskii, E. A.; Romanov, Yu. A.

    1980-04-01

    Using the Poisson equation Green function for a self-consistent field in a spatially inhomogeneous system, expressions for the electrostatic energy and screened charge interaction near the surface of a semi-infinite metal and a thin quantizing film are derived. It is shown that the decrease law and Friedel oscillation amplitude of adsorbed atom indirect interaction are determined by the electron spectrum character and the Fermi surface shape. The results obtained enable us to explain, in particular, the submonolayer adsorbed film structure on the W and Mo surfaces.

  19. Phase structuring in metal alloys: Ultrasound-assisted top-down approach to engineering of nanostructured catalytic materials.

    Science.gov (United States)

    Cherepanov, Pavel V; Andreeva, Daria V

    2017-03-01

    High intensity ultrasound (HIUS) is a novel and efficient tool for top-down nanostructuring of multi-phase metal systems. Ultrasound-assisted structuring of the phase in metal alloys relies on two main mechanisms including interfacial red/ox reactions and temperature driven solid state phase transformations which affect surface composition and morphology of metals. Physical and chemical properties of sonication medium strongly affects the structuring pathways as well as morphology and composition of catalysts. HIUS can serve as a simple, fast, and effective approach for the tuning of structure and surface properties of metal particles, opening the new perspectives in design of robust and efficient catalysts. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Cold Gas-Sprayed Deposition of Metallic Coatings onto Ceramic Substrates Using Laser Surface Texturing Pre-treatment

    Science.gov (United States)

    Kromer, R.; Danlos, Y.; Costil, S.

    2018-04-01

    Cold spraying enables a variety of metals dense coatings onto metal surfaces. Supersonic gas jet accelerates particles which undergo with the substrate plastic deformation. Different bonding mechanisms can be created depending on the materials. The particle-substrate contact time, contact temperature and contact area upon impact are the parameters influencing physicochemical and mechanical bonds. The resultant bonding arose from plastic deformation of the particle and substrate and temperature increasing at the interface. The objective was to create specific topography to enable metallic particle adhesion onto ceramic substrates. Ceramic did not demonstrate deformation during the impact which minimized the intimate bonds. Laser surface texturing was hence used as prior surface treatment to create specific topography and to enable mechanical anchoring. Particle compressive states were necessary to build up coating. The coating deposition efficiency and adhesion strength were evaluated. Textured surface is required to obtain strong adhesion of metallic coatings onto ceramic substrates. Consequently, cold spray coating parameters depend on the target material and a methodology was established with particle parameters (diameters, velocities, temperatures) and particle/substrate properties to adapt the surface topography. Laser surface texturing is a promising tool to increase the cold spraying applications.

  1. CW substrate-free metal-cavity surface microemitters at 300 K

    International Nuclear Information System (INIS)

    Lu, Chien-Yao; Chang, Shu-Wei; Chuang, Shun Lien; Germann, Tim D; Pohl, Udo W; Bimberg, Dieter

    2011-01-01

    In this paper substrate-free metal-cavity surface microemitters are demonstrated. The optical cavity is formed by a metal reflector, metal-surrounded sidewall and n-doped distributed-Bragg reflector, which provides optical feedback and carrier injection. We describe a simple design principle with the modal properties modified by geometry and metal-insulator cladding. Both resonant cavity light-emitting diodes (1.85 µm diameter and 0.6 µm height) and lasers (2.0 µm diameter and 2.5 µm height) are successfully fabricated and characterized. These two types of devices operate at room temperature under continuous-wave (CW) operation. Since the devices are substrate-free, they can be bonded to any substrates. From the threshold currents of the lasers, we obtain a high characteristic temperature of 425 K in the range of 10–27 °C. We also discuss a general approach to improve the diffraction from small-aperture devices

  2. The interaction of trace heavy metal with lipid monolayer in the sea surface microlayer.

    Science.gov (United States)

    Li, Siyang; Du, Lin; Tsona, Narcisse T; Wang, Wenxing

    2018-04-01

    Lipid molecules and trace heavy metals are enriched in sea surface microlayer and can be transferred into the sea spray aerosol. To better understand their impact on marine aerosol generation and evolution, we investigated the interaction of trace heavy metals including Fe 3+ , Pb 2+ , Zn 2+ , Cu 2+ , Ni 2+ , Cr 3+ , Cd 2+ , and Co 2+ , with dipalmitoylphosphatidylcholine (DPPC) monolayers at the air-water interface. Phase behavior of the DPPC monolayer on heavy metal solutions was probed with surface pressure-area (π-A) isotherms. The conformation order and orientation of DPPC alkyl chains were characterized by infrared reflection-absorption spectroscopy (IRRAS). The π-A isotherms show that Zn 2+ and Fe 3+ strongly interact with DPPC molecules, and induce condensation of the monolayers in a concentration-dependent manner. IRRAS spectra show that the formation of cation-DPPC complex gives rise to conformational changes and immobilization of the headgroups. The current results suggest that the enrichment of Zn 2+ in sea spray aerosols is due to strong binding to the DPPC film. The interaction of Fe 3+ with DPPC monolayers can significantly influence their surface organizations through the formation of lipid-coated particles. These results suggest that the sea surface microlayer is capable of accumulating much higher amounts of these metals than the subsurface water. The organic and metal pollutants may transfer into the atmosphere by this interaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Self-consistent density functional calculation of the image potential at a metal surface

    International Nuclear Information System (INIS)

    Jung, J; Alvarellos, J E; Chacon, E; GarcIa-Gonzalez, P

    2007-01-01

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z 0 ), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z 0 , and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description

  4. Self-consistent density functional calculation of the image potential at a metal surface

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Alvarellos, J E [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Chacon, E [Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); GarcIa-Gonzalez, P [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain)

    2007-07-04

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z{sub 0}), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z{sub 0}, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.

  5. Changes of electrical conductivity of the metal surface layer by the laser alloying with foreign elements

    Science.gov (United States)

    Kostrubiec, Franciszek; Pawlak, Ryszard; Raczynski, Tomasz; Walczak, Maria

    1994-09-01

    Laser treatment of the surface of materials is of major importance for many fields technology. One of the latest and most significant methods of this treatment is laser alloying consisting of introducing foreign atoms into the metal surface layer during the reaction of laser radiation with the surface. This opens up vast possibilities for the modification of properties of such a layer (obtaining layers of increased microhardness, increased resistance to electroerosion in an electric arc, etc.). Conductivity of the material is a very important parameter in case of conductive materials used for electrical contacts. The paper presents the results of studies on change in electrical conductivity of the surface layer of metals alloyed with a laser. A comparative analysis of conductivity of base metal surface layers prior to and following laser treatment has been performed. Depending on the base metal and the alloying element, optical treatment parameters allowing a required change in the surface layer conductivity have been selected. A very important property of the contact material is its resistance to plastic strain. It affects the real value of contact surface coming into contact and, along with the material conductivity, determines contact resistance and the amount of heat generated in place of contact. These quantities are directly related to the initiation and the course of an arc discharge, hence they also affect resistance to electroerosion. The parameter that reflects plastic properties with loads concentrated on a small surface, as is the case with a reciprocal contact force of two real surfaces with their irregularities being in contact, is microhardness. In the paper, the results of investigations into microhardness of modified surface layers compared with base metal microhardness have been presented.

  6. Work functions and surface charges at metallic facet edges

    International Nuclear Information System (INIS)

    Fall, C.J.; Binggeli, N.; Baldereschi, A.

    2002-04-01

    The electronic charge densities and work functions at sharp metallic facet edges are determined from ab initio calculations, combined with macroscopic averaging techniques. In particular, we examine how two different work functions coexist at close range near edges between inequivalent facets. The surface ionic relaxation at facet edges is shown to influence appreciably the local electrostatic potential in the vacuum. Various edges between Al(100) and Al(111) facets are studied, as well as between Na(110) facets. We also develop a model of electronic surface dipoles, which accounts for the surface charge transfer between inequivalent facets, and which allows us to predict the influence of the shape and size of a macroscopic crystal on its work functions. (author)

  7. Early human bone response to laser metal sintering surface topography: a histologic report.

    Science.gov (United States)

    Mangano, Carlo; Piattelli, Adriano; d'Avila, Susana; Iezzi, Giovanna; Mangano, Francesco; Onuma, Tatiana; Shibli, Jamil Awad

    2010-01-01

    This histologic report evaluated the early human bone response to a direct laser metal sintering implant surface retrieved after a short period of healing. A selective laser sintering procedure using a Ti-6Al-4V alloy powder with a particle size of 25-45 microm prepared this surface topography. One experimental microimplant was inserted into the anterior mandible of a patient during conventional implant surgery of the jaw. The microimplant and surrounding tissues were removed after 2 months of unloaded healing and were prepared for histomorphometric analysis. Histologically, the peri-implant bone appeared in close contact with the implant surface, whereas marrow spaces could be detected in other areas along with prominently stained cement lines. The mean of bone-to-implant contact was 69.51%. The results of this histologic report suggest that the laser metal sintering surface could be a promising alternative to conventional implant surface topographies.

  8. Liquid Metals as Plasma-facing Materials for Fusion Energy Systems: From Atoms to Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Howard A. [Princeton Univ., NJ (United States); Koel, Bruce E. [Princeton Univ., NJ (United States); Bernasek, Steven L. [Princeton Univ., NJ (United States); Carter, Emily A. [Princeton Univ., NJ (United States); Debenedetti, Pablo G. [Princeton Univ., NJ (United States); Panagiotopoulos, Athanassios Z. [Princeton Univ., NJ (United States)

    2017-06-23

    The objective of our studies was to advance our fundamental understanding of liquid metals as plasma-facing materials for fusion energy systems, with a broad scope: from atoms to tokamaks. The flow of liquid metals offers solutions to significant problems of the plasma-facing materials for fusion energy systems. Candidate metals include lithium, tin, gallium, and their eutectic combinations. However, such liquid metal solutions can only be designed efficiently if a range of scientific and engineering issues are resolved that require advances in fundamental fluid dynamics, materials science and surface science. In our research we investigated a range of significant and timely problems relevant to current and proposed engineering designs for fusion reactors, including high-heat flux configurations that are being considered by leading fusion energy groups world-wide. Using experimental and theoretical tools spanning atomistic to continuum descriptions of liquid metals, and bridging surface chemistry, wetting/dewetting and flow, our research has advanced the science and engineering of fusion energy materials and systems. Specifically, we developed a combined experimental and theoretical program to investigate flows of liquid metals in fusion-relevant geometries, including equilibrium and stability of thin-film flows, e.g. wetting and dewetting, effects of electromagnetic and thermocapillary fields on liquid metal thin-film flows, and how chemical interactions and the properties of the surface are influenced by impurities and in turn affect the surface wetting characteristics, the surface tension, and its gradients. Because high-heat flux configurations produce evaporation and sputtering, which forces rearrangement of the liquid, and any dewetting exposes the substrate to damage from the plasma, our studies addressed such evaporatively driven liquid flows and measured and simulated properties of the different bulk phases and material interfaces. The range of our studies

  9. Laser-induced surface modification of metals and alloys in liquid argon medium

    International Nuclear Information System (INIS)

    Kazakevich, V S; Kazakevich, P V; Yaresko, P S; Kamynina, D A

    2016-01-01

    Micro and nanostructuring of metals and alloys surfaces (Ti, Mo, Ni, T30K4) was considered by subnanocosecond laser radiation in stationary and dynamic mode in the liquid argon, ethanol and air. Depending of structures size on the samples surface from the energy density and the number of pulses were built. Non-periodic (NSS) and periodic (PSS) surface structures with periods about λ-λ/2 were obtained. PSS formation took place as at the target surface so at the NSS surface. (paper)

  10. The secondary electron yield of air exposed metal surfaces at the example of niobium

    CERN Document Server

    Scheuerlein, C; Taborelli, M

    2002-01-01

    The secondary electron yield (SEY) variation of atomically clean metal surfaces due to air exposures and during subsequent heat treatments is described with the example of a sputter-deposited Nb thin film. Corresponding variations of the surface chemical composition have been monitored using AES and SSIMS. On the basis of these results and of previously obtained SEY results on metals and metal oxides the origin of the SEY variations is discussed. The SEY increase, which is generally observed during long lasting air exposures of clean metals, is mainly caused by the adsorption of an airborne carbonaceous contamination layer. The estimated value of about 3 for the maximum SEY of this layer is higher than that of all pure metals. Only in some cases the air-formed oxide can contribute to the air exposure induced SEY increase while many oxides have a lower SEY than their parent metals. From the experimental data it can also be excluded that the SEY increase during air exposures is mainly due to an increased second...

  11. An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces

    OpenAIRE

    MILAN S. TRTICA; SCEPAN S. MILJANIC; NATASA N. STJEPANOVIC

    2000-01-01

    There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lase...

  12. Surface half-metallicity of half-Heusler compound FeCrSe and interface half-metallicity of FeCrSe/GaP

    Energy Technology Data Exchange (ETDEWEB)

    Khalaf Al-zyadi, Jabbar M., E-mail: jabbar_alzyadi@yahoo.com [Department of Physics, College of Education for Pure Sciences, University of Basrah (Iraq); Jolan, Mudhahir H. [Department of Physics, College of Education for Pure Sciences, University of Basrah (Iraq); Yao, Kai-Lun, E-mail: klyao@mail.hust.edu.cn [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); International Center of Materials Physics, Chinese Academy of Sciences, Shenyang 110015 (China)

    2016-04-01

    Recent studies showed that half-Heusler FeCrSe exhibits half-metallic ferromagnetism (Huang et al. [20]). In this paper, we investigate extensively the electronic, magnetic, and half-metallic properties of the half-Heusler alloy FeCrSe (111) and (001) surfaces and the interface with GaP (111) substrate by using the first-principles calculations within the density functional theory. The atomic density of states demonstrates that the half-me tallicity verified in the bulk FeCrSe is maintained at the CrSe-terminated (001) and Se-terminated (111) surfaces, but lost at both Cr- and Fe-terminated (111) surfaces and the Fe-terminated (001) surface. Alternatively, for the interface of FeCrSe/GaP (111), the bulk half-metallicity is destroyed at Se–P configuration while Se–Ga interface and subinterface show nearly 100% spin polarization. Moreover, the calculated interfacial adhesion energies exhibit that Se–Ga shape is more stable than the Se–P one. The calculated magnetic moments of Se, Ga at the Se–Ga (111) interface and P at the Se–P (111) interface increase with respect to the corresponding bulk values while the atomic magnetic moment of Se atom at the Se–P (111) interface decreases. We also notice that the magnetic moments of subinterface Fe at both Se–Ga and Se–P (111) interfaces decrease compared to the bulk values. - Highlights: • The half-metallicity verified in the bulk FeCrSe is kept at the CrSe-terminated (001) and Se-terminated (111) surfaces. • The calculated interfacial adhesion energies exhibit that Se–Ga shape is more stable than Se–P. • The magnetic moments of Se, Ga and P atoms at the interface increase. • The Se–Ga interface shows nearly 100% spin polarization.

  13. Methods for surface treating metals, ceramics, and plastics before adhesive bonding

    International Nuclear Information System (INIS)

    Althouse, L.P.

    1976-01-01

    Methods for pretreating the surfaces of metals, ceramics, and plastics before they are coated with adhesive and used in assembly are described. The treatments recommended have been used successfully in the laboratory at LLL. Many are used in the assembly of nuclear devices. However, an unusual alloy or complex configuration may require trials before a specific surface treatment is chosen

  14. Possibility of surface carburization of refractory metals of electric spark alloying

    International Nuclear Information System (INIS)

    Verkhoturov, A.D.; Isaeva, L.P.; Timofeeva, I.I.; Tsyban', V.A.

    1981-01-01

    The paper is concerned with a study in the alloying layer formation under electric spark alloying of refractory (Ti, Zr, Nb, Mo, W, Co, Fe) metals with graphite in argon and in air using the EhFI-46A installation. It is shown that in electric spark alloying with graphite there appear certain specific conditions for the alloying layer formation manifested in the cathode mass decrease during treatment. In this case an alloying layer consisting of carbides, oxides of the corresponding metals and material of the base is formed on the metal surface. The best carburization conditions in the process of electric spark alloying are realized for group 4 metals when treating them in ''soft'' regime, specific time of alloying being 1-3 min/sm 2 and for group 5 and 6 metals - in ''rigid'' regime of treatment and specific time of alloying 3-5 min/cm 2 [ru

  15. Realization of N-Type Semiconducting of Phosphorene through Surface Metal Doping and Work Function Study

    Directory of Open Access Journals (Sweden)

    Haocheng Sun

    2018-01-01

    Full Text Available Phosphorene becomes an important member of the layered nanomaterials since its discovery for the fabrication of nanodevices. In the experiments, pristine phosphorene shows p-type semiconducting with no exception. To reach its full capability, n-type semiconducting is a necessity. Here, we report the electronic structure engineering of phosphorene by surface metal atom doping. Five metal elements, Cu, Ag, Au, Li, and Na, have been considered which could form stable adsorption on phosphorene. These elements show patterns in their electron configuration with one valence electron in their outermost s-orbital. Among three group 11 elements, Cu can induce n-type degenerate semiconducting, while Ag and Au can only introduce localized impurity states. The distinct ability of Cu, compared to Ag and Au, is mainly attributed to the electronegativity. Cu has smaller electronegativity and thus denotes its electron to phosphorene, upshifting the Fermi level towards conduction band, resulting in n-type semiconducting. Ag and Au have larger electronegativity and hardly transfer electrons to phosphorene. Parallel studies of Li and Na doping support these findings. In addition, Cu doping effectively regulates the work function of phosphorene, which gradually decreases upon increasing Cu concentration. It is also interesting that Au can hardly change the work function of phosphorene.

  16. Annotated bibliography for liquid metal surface tensions of groups III-A, IV-A, and V-A metals

    International Nuclear Information System (INIS)

    Murtha, M.J.; Burnet, G.

    1976-04-01

    An annotated bibliography has been prepared which includes summaries of 82 publications dating from 1920 and dealing with the measurement of the surface tensions of Groups III-A, IV-A, and V-A metals in the liquid state. The bibliography is organized by key element investigated, and contains a tabulation of correlations for surface tension as a function of temperature. A brief discussion dealing with variables and methods has been included

  17. New trends for non-ferrous metals in the electrical engineering industry

    International Nuclear Information System (INIS)

    Singer, R.F.

    1989-01-01

    The non-ferrous metals copper, aluminium and nickel are of major importance to the electrical engineering industry. Copper is used for magnet wire, underground cable and overhead contact wire, and aluminium is important for overhead power transmission lines. Nickel alloys are employed as gas turbine blades in power generation. An important new trend in the conductor area is rapid solidification for improved combinations of strength and conductivity. Another new trend is the Conform continuous extrusion process which can decrease cost and increase quality. New high temperature superconductors might change the conductor market completely, but only on the long run. Nickel base blading materials will see considerable improvements from oxide dispersion strengthening and directional solidification. In summary, non-ferrous materials technology for electrical engineering applications is on the move and considerable improvements can be expected within the next decade. (orig.) [de

  18. Development of micro-engineered textured tungsten surfaces for high heat flux applications

    Energy Technology Data Exchange (ETDEWEB)

    Sharafat, Shahram, E-mail: shahrams@ucla.edu [University of California Los Angeles, CA (United States); Aoyama, Aaron [University of California Los Angeles, CA (United States); Williams, Brian, E-mail: brian.williams@ultramet.com [Ultramet Inc., Pacoima, CA (United States); Ghoniem, Nasr [University of California Los Angeles, CA (United States)

    2013-11-15

    Surface micro-engineering can enhance the thermo-mechanical performance of plasma facing components (PFCs). For example, castellation of a surface can reduce thermal stress due to high heat loads and thus provide higher thermo-mechanical resilience. Recently, fabrication of a variety of micro-sized refractory dendrites with reproducible geometric characteristics (e.g., density, length, height, and aspect ratio) has been demonstrated. In contrast to flat surfaces exposed to high heat loads, dendrites deform independently to minimize near-surface thermal stress, which results in improved thermo-mechanical performance. Thus, the use of dendrites offers a unique micro-engineering approach to enhance the performance of PFC structures. A brief overview of W, Re, and Mo dendritic structures is given along with micrographs that show dendrite-coated surfaces. The thermal responses of representative dendrite structures are analyzed as a function of aspect ratios and dendrite geometry. The heat-management capability of needle-like dendrites exposed to a surface energy of up to 1 MJ/m{sup 2} is analyzed and compared to a flat surface. It is concluded that dendrite structures can significantly reduce thermal stress in the substrate when compared to flat surfaces. Implications of dendritic surfaces on sputter erosion rates are also discussed briefly.

  19. Application of a modified electrochemical system for surface decontamination of radioactive metal waste

    International Nuclear Information System (INIS)

    Lee, J.H.; Lim, Y.K.; Yang, H.Y.; Shin, S.W.; Song, M.J.

    2003-01-01

    Conventional and modified electrolytic decontamination experiments were performed in a solution of sodium sulfate for the decontamination of carbon steel as the simulated metal wastes which are generated in large amounts from nuclear power plants. The effect of reaction time, current density and concentration of electrolytes in the modified electrolytic decontamination system were examined to remove the surface contamination of the simulated radioactive metal wastes. As for the results of this research, the modified electrochemical decontamination process can decontaminate more effectively than the conventional decontamination process by applying different anode material which causes higher induced electro-motive forces. When 0.5 M sodium sulfate, 0.4 A/cm 2 current density and 30 minutes reaction time were applied in the modified process, a 16 μm thickness change that is expected to remove most surface contamination in radioactive metal wastes was achieved on carbon steel which is the main material of radioactive metal waste in nuclear power plants. The decontamination efficiency of metal waste showed similar results with the small and large lab-scale modified electrochemical system. The application of this modified electrolytic decontamination system is expected to play a considerable role for decontamination of radioactive metal waste in nuclear power plants in the near future. (author)

  20. Seasonal Distribution of Trace Metals in Ground and Surface Water of Golaghat District, Assam, India

    Directory of Open Access Journals (Sweden)

    M. Boarh

    2010-01-01

    Full Text Available A study has been carried out on the quality of ground and surface water with respect to chromium, manganese, zinc, copper, nickel, cadmium and arsenic contamination from 28 different sources in the predominantly rural Golaghat district of Assam (India. The metals were analysed by using atomic absorption spectrometer. Water samples were collected from groundwater and surface water during the dry and wet seasons of 2008 from the different sources in 28 locations (samples. The results are discussed in the light of possible health hazards from the metals in relation to their maximum permissible limits. The study shows the quality of ground and surface water in a sizeable number of water samples in the district not to be fully satisfactory with respect to presence of the metals beyond permissible limits of WHO. The metal concentration of groundwater in the district follows the trend As>Zn>Mn>Cr>Cu>Ni>Cd in both the seasons.