Determination of the Number of Fixture Locating Points for Sheet Metal By Grey Model

Directory of Open Access Journals (Sweden)

Yang Bo

2017-01-01

Full Text Available In the process of the traditional fixture design for sheet metal part based on the "N-2-1" locating principle, the number of fixture locating points is determined by trial and error or the experience of the designer. To that end, a new design method based on grey theory is proposed to determine the number of sheet metal fixture locating points in this paper. Firstly, the training sample set is generated by Latin hypercube sampling (LHS and finite element analysis (FEA. Secondly, the GM(1, 1 grey model is constructed based on the established training sample set to approximate the mapping relationship between the number of fixture locating points and the concerned sheet metal maximum deformation. Thirdly, the final number of fixture locating points for sheet metal can be inversely calculated under the allowable maximum deformation. Finally, a sheet metal case is conducted and the results indicate that the proposed approach is effective and efficient in determining the number of fixture locating points for sheet metal.

Assembly for testing weldability of sheet metal

International Nuclear Information System (INIS)

David, S.A.; Woodhouse, J.J.

1985-01-01

A test assembly for determining the weldability of sheet metal includes a base having a flat side surface with an annular groove in the side surface, a counterbore being formed in the outer wall of the groove and the surface portion of the base circumscribed by the inner wall of the groove being substantially coplanar with the bottom of the counterbore, a test disk of sheet metal the periphery of which is positioned in the counterbore and the outer surface of which is coplanar with one side of the base, and a clamp ring overlying the side surface of the base and the edge portion of the test disk and a plurality of clamp screws which extend through the clamp ring for holding the periphery of the test disk against the bottom of the counterbore

Limit State of Trapezoidal Metal Sheets Exposed to Concentrated Load

OpenAIRE

Kateřina Jurdová

2013-01-01

In most industrial compounds are used trapezoidal metal sheets like a roof decks. These trapezoidal metal sheets are exposed by concentrated loads, usually by service loads arise from installation of air distribution, sanitary distribution, sprinkler system or wiring installation. In objects of public facilities (like shopping centre, tennis hall, etc.) they can be used for hanging advertising posters etc, too. These systems work as “building kit”. These anchoring systems are represented by c...

Process control for sheet-metal stamping process modeling, controller design and shop-floor implementation

CERN Document Server

Lim, Yongseob; Ulsoy, A Galip

2014-01-01

Process Control for Sheet-Metal Stamping presents a comprehensive and structured approach to the design and implementation of controllers for the sheet metal stamping process. The use of process control for sheet-metal stamping greatly reduces defects in deep-drawn parts and can also yield large material savings from reduced scrap. Sheet-metal forming is a complex process and most often characterized by partial differential equations that are numerically solved using finite-element techniques. In this book, twenty years of academic research are reviewed and the resulting technology transitioned to the industrial environment. The sheet-metal stamping process is modeled in a manner suitable for multiple-input multiple-output control system design, with commercially available sensors and actuators. These models are then used to design adaptive controllers and real-time controller implementation is discussed. Finally, experimental results from actual shopfloor deployment are presented along with ideas for further...

Constitutive Modeling for Sheet Metal Forming

International Nuclear Information System (INIS)

Barlat, Frederic

2005-01-01

This paper reviews aspects of the plastic behaviour common in sheet metals. Macroscopic and microscopic phenomena occurring during plastic deformation are described succinctly. Constitutive models of plasticity suitable for applications to forming, are discussed in a very broad manner. Approaches to plastic anisotropy are described in a somewhat more detailed manner

Multi-scale contact modeling of coated steels for sheet metal forming applications

NARCIS (Netherlands)

Shisode, Meghshyam; Hazrati Marangalou, Javad; Mishra, Tanmaya; De Rooij, Matthijn; Van Den Boogaard, Ton; Bay, Niels; Nielsen, Chris V.

2018-01-01

Friction in sheet metal forming is a local phenomenon which depends on continuously evolving contact conditions during the forming process. This is mainly influenced by local contact pressure, surface textures of the sheet metal as well as the forming tool surface profile and material behavior. The

Interfacial delamination in polymer coated metal sheet : a numerical-experimental study

NARCIS (Netherlands)

van den Bosch, M.

2007-01-01

An increasing amount of products are nowadays made of polymer coated metal sheet. Polymer coated metal has several advantages compared to traditionally Sn (tin) coated metal, such as costs savings and a more environmental friendly production process. Beverage and food cans are formed by draw-redraw

Multi Scale Models for Flexure Deformation in Sheet Metal Forming

Directory of Open Access Journals (Sweden)

Di Pasquale Edmondo

2016-01-01

Full Text Available This paper presents the application of multi scale techniques to the simulation of sheet metal forming using the one-step method. When a blank flows over the die radius, it undergoes a complex cycle of bending and unbending. First, we describe an original model for the prediction of residual plastic deformation and stresses in the blank section. This model, working on a scale about one hundred times smaller than the element size, has been implemented in SIMEX, one-step sheet metal forming simulation code. The utilisation of this multi-scale modeling technique improves greatly the accuracy of the solution. Finally, we discuss the implications of this analysis on the prediction of springback in metal forming.

Detection of defects in formed sheet metal using medial axis transformation

Science.gov (United States)

Murmu, Naresh C.; Velgan, Roman

2003-05-01

In the metal forming processes, the sheet metals are often prone to various defects such as thinning, dents, wrinkles etc. In the present manufacturing environments with ever increasing demand of higher quality, detecting the defects of formed sheet metal using an effective and objective inspection system is the foremost norm to remain competitive in market. The defect detection using optical techniques aspire to satisfy its needs to be non-contact and fast. However, the main difficulties to achieve this goal remain essentially on the development of efficient evaluation technique and accurate interpretation of extracted data. The defect like thinning is detected by evaluating the deviations of the thickness in the formed sheet metal against its nominal value. The present evaluation procedure for determination of thickness applied on the measurements data is not without deficiency. To improve this procedure, a new evaluation approach based on medial axis transformation is proposed here. The formed sheet metals are digitized using fringe projection systems in different orientations, and afterwards registered into one coordinate frame. The medial axis transformation (MAT) is applied on the point clouds, generating the point clouds of MAT. This data is further processed and medial surface is determined. The thinning defect is detected by evaluating local wall thickness and other defects like wrinkles are determined using the shape recognition on the medial surface. The applied algorithm is simple, fast and robust.

Review on progressive microforming of bulk metal parts directly using sheet metals (Keynote Paper

Directory of Open Access Journals (Sweden)

Fu M.W.

2015-01-01

Full Text Available Due to the ubiquitous trend of product miniaturization, energy saving and weight reduction, micro/meso-scale parts have been widely used in many industrial clusters. Micromanufacturing processes for production of such micro/meso-scale parts are thus critically needed. Microforming, as one of these micro manufacturing processes, is a promising process and thus got many explorations and researches. Compared with the research on size effect affected deformation behaviours, less attention has been paid to the process development for mass production of micro-parts. The product quality and fabrication productivity of micro-parts depend on the involved process chain. To address the difficulty in handling and transporting of the micro-sized workpiece, development of a progressive microforming process for directly fabricating bulk micro-parts using sheet metals seems quite promising as it avoids or facilitates billet handling, transportation, positioning, and ejection in the process chain. In this paper, an intensive review on the latest development of progressive microforming technologies is presented. First of all, the paper summarizes the characteristic of progressive microforming directly using sheet metal. The size effect-affected deformation behaviour and the dimensional accuracy, deformation load, ductile fracture, and the surface finish of the microformed parts by progressive microforming using sheet metals are then presented. Finally, some research issues from the implementation of mass production perspective are also discussed.

Multiscale friction modeling for sheet metal forming

NARCIS (Netherlands)

Hol, J.; Cid Alfaro, M.V.; de Rooij, Matthias B.; Meinders, Vincent T.; Felder, Eric; Montmitonnet, Pierre

2010-01-01

The most often used friction model for sheet metal forming simulations is the relative simple Coulomb friction model. This paper presents a more advanced friction model for large scale forming simulations based on the surface change on the micro-scale. The surface texture of a material changes when

Working with Design: A Package for Sheet Metal

Science.gov (United States)

Fiebich, Paul D.

1974-01-01

The author describes a design approach used to study sheet metal layout in junior high and high school mechanical drafting courses. Students observe packaging in stores, study package construction, and design and produce their own packages. (EA)

Development of parallel benchmark code by sheet metal forming simulator 'ITAS'

International Nuclear Information System (INIS)

Watanabe, Hiroshi; Suzuki, Shintaro; Minami, Kazuo

1999-03-01

This report describes the development of parallel benchmark code by sheet metal forming simulator 'ITAS'. ITAS is a nonlinear elasto-plastic analysis program by the finite element method for the purpose of the simulation of sheet metal forming. ITAS adopts the dynamic analysis method that computes displacement of sheet metal at every time unit and utilizes the implicit method with the direct linear equation solver. Therefore the simulator is very robust. However, it requires a lot of computational time and memory capacity. In the development of the parallel benchmark code, we designed the code by MPI programming to reduce the computational time. In numerical experiments on the five kinds of parallel super computers at CCSE JAERI, i.e., SP2, SR2201, SX-4, T94 and VPP300, good performances are observed. The result will be shown to the public through WWW so that the benchmark results may become a guideline of research and development of the parallel program. (author)

Process Simulation of Aluminium Sheet Metal Deep Drawing at Elevated Temperatures

International Nuclear Information System (INIS)

Winklhofer, Johannes; Trattnig, Gernot; Lind, Christoph; Sommitsch, Christof; Feuerhuber, Hannes

2010-01-01

Lightweight design is essential for an economic and environmentally friendly vehicle. Aluminium sheet metal is well known for its ability to improve the strength to weight ratio of lightweight structures. One disadvantage of aluminium is that it is less formable than steel. Therefore complex part geometries can only be realized by expensive multi-step production processes. One method for overcoming this disadvantage is deep drawing at elevated temperatures. In this way the formability of aluminium sheet metal can be improved significantly, and the number of necessary production steps can thereby be reduced. This paper introduces deep drawing of aluminium sheet metal at elevated temperatures, a corresponding simulation method, a characteristic process and its optimization. The temperature and strain rate dependent material properties of a 5xxx series alloy and their modelling are discussed. A three dimensional thermomechanically coupled finite element deep drawing simulation model and its validation are presented. Based on the validated simulation model an optimised process strategy regarding formability, time and cost is introduced.

Compression deformation behaviors of sheet metals at various clearances and side forces

OpenAIRE

Zhan Mei; Wang Xianxian; Cao Jian; Yang He

2015-01-01

Modeling sheet metal forming operations requires understanding of plastic behaviors of sheet metals along non-proportional strain paths. The plastic behavior under reversed uniaxial loading is of particular interest because of its simplicity of interpretation and its application to material elements drawn over a die radius and underwent repeated bending. However, the attainable strain is limited by failures, such as buckling and in-plane deformation, dependent on clearances and side forces. I...

Elaboration of the technology of forming a conical product of sheet metal

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W. Matysiak

2010-01-01

Full Text Available The work presents a general knowledge about spinning draw pieces of sheets, one of multi-operational processes of spinning a sheet metal conical product without machining. The objective of the work was to elaborate both the technology of forming conical products of sheet metal and execution of technological tests as well as to determine the technological parameters for the process of spinning a conical insert. As a result of the investigations, the products with improved mechanical properties, stricter execution tolerance and low roughness have been obtained. The series of 200 prototype conical inserts for the shipbuilding industry have been made.

Formability of porous tantalum sheet-metal

International Nuclear Information System (INIS)

Nebosky, Paul S; Schmid, Steven R; Pasang, Timotius

2009-01-01

Over the past ten years, a novel cellular solid, Trabecular Metal T M , has been developed for use in the orthopaedics industry as an ingrowth scaffold. Manufactured using chemical vapour deposition (CVD) on top of a graphite foam substrate, this material has a regular matrix of interconnecting pores, high strength, and high porosity. Manufacturing difficulties encourage the application of bending, stamping and forming technologies to increase CVD reactor throughput and reduce material wastes. In this study, the bending and forming behaviour of Trabecular Metal T M was evaluated using a novel camera-based system for measuring surface strains, since the conventional approach of printing or etching gridded patterns was not feasible. A forming limit diagram was obtained using specially fabricated 1.65 mm thick sheets. A springback coefficient was measured and modeled using effective hexagonal cell arrangements.

Variation simulation for compliant sheet metal assemblies with applications

Science.gov (United States)

Long, Yufeng

Sheet metals are widely used in discrete products, such as automobiles, aircraft, furniture and electronics appliances, due to their good manufacturability and low cost. A typical automotive body assembly consists of more than 300 parts welded together in more than 200 assembly fixture stations. Such an assembly system is usually quite complex, and takes a long time to develop. As the automotive customer demands products of increasing quality in a shorter time, engineers in automotive industry turn to computer-aided engineering (CAE) tools for help. Computers are an invaluable resource for engineers, not only to simplify and automate the design process, but also to share design specifications with manufacturing groups so that production systems can be tooled up quickly and efficiently. Therefore, it is beneficial to develop computerized simulation and evaluation tools for development of automotive body assembly systems. It is a well-known fact that assembly architectures (joints, fixtures, and assembly lines) have a profound impact on dimensional quality of compliant sheet metal assemblies. To evaluate sheet metal assembly architectures, a special dimensional analysis tool need be developed for predicting dimensional variation of the assembly. Then, the corresponding systematic tools can be established to help engineers select the assembly architectures. In this dissertation, a unified variation model is developed to predict variation in compliant sheet metal assemblies by considering fixture-induced rigid-body motion, deformation and springback. Based on the unified variation model, variation propagation models in multiple assembly stations with various configurations are established. To evaluate the dimensional capability of assembly architectures, quantitative indices are proposed based on the sensitivity matrix, which are independent of the variation level of the process. Examples are given to demonstrate their applications in selecting robust assembly

Feature Size Effect on Formability of Multilayer Metal Composite Sheets under Microscale Laser Flexible Forming

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Huixia Liu

2017-07-01

Full Text Available Multilayer metal composite sheets possess superior properties to monolithic metal sheets, and formability is different from monolithic metal sheets. In this research, the feature size effect on formability of multilayer metal composite sheets under microscale laser flexible forming was studied by experiment. Two-layer copper/nickel composite sheets were selected as experimental materials. Five types of micro molds with different diameters were utilized. The formability of materials was evaluated by forming depth, thickness thinning, surface quality, and micro-hardness distribution. The research results showed that the formability of two-layer copper/nickel composite sheets was strongly influenced by feature size. With feature size increasing, the effect of layer stacking sequence on forming depth, thickness thinning ratio, and surface roughness became increasingly larger. However, the normalized forming depth, thickness thinning ratio, surface roughness, and micro-hardness of the formed components under the same layer stacking sequence first increased and then decreased with increasing feature size. The deformation behavior of copper/nickel composite sheets was determined by the external layer. The deformation extent was larger when the copper layer was set as the external layer.

INDUCTION HEATING OF NON-MAGNETIC SHEET METALS IN THE FIELD OF A FLAT CIRCULAR MULTITURN SOLENOID

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Y. Batygin

2016-06-01

Full Text Available The theoretical analysis of electromagnetic processes in the system for induction heating presented by a flat circular multiturn solenoid positioned above a plane of thin sheet non-magnetic metal has been conducted. The calculated dependences for the current induced in a metal sheet blank and ratio of transformation determined have been obtained. The maximal value of the transformation ratio with regard to spreading the eddy-currents over the whole area of the sheet metal has been determined.

Comparison of Two Commercial FE-Codes for Sheet Metal Forming

International Nuclear Information System (INIS)

Revuelta, A.; Larkiola, J.; Kanervo, K.; Korhonen, A. S.; Myllykoski, P.

2007-01-01

There is urgent need to develop new advanced fast and cost-effective mass-production methods for small sheet metal components. Traditionally progressive dies have been designed by using various CAD techniques. Recent results in mass production of small sheet metal parts using progressive dies and a transfer press showed that the tool design time may be cut in up to a half by using 3D finite element simulation of forming. In numerical simulation of sheet metal forming better constitutive models are required to obtain more accurate results, reduce the time for tool design and cut the production costs further. Accurate models are needed to describe the initial yielding, subsequent work hardening and to predict the formability. In this work two commercially available finite element simulation codes, PAM-STAMP and LS-DYNA, were compared in forming of small austenitic stainless steel sheet part for electronic industry. Several constitutive models were used in both codes and the results were compared. Comparisons were made between the same models in each of the codes and also between different models in the same code. Material models ranged from very simple to advanced ones, which took into account anisotropy and both isotropic and kinematic hardening behavior. In order to make a valid comparison we employed similar finite element meshes. The effects of the material models parameters were studied and the results were compared with experiments. The effects of the computational time were also studied

Electromagnetic confinement and movement of thin sheets of molten metal

Science.gov (United States)

Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

1990-01-01

An apparatus capable of producing a combination of magnetic fields that can retain a metal in liquid form in a region having a smooth vertical boundary including a levitation magnet that produces low frequency magnetic field traveling waves to retain the metal and a stabilization magnet that produces a high frequency magnetic field to produce a smooth vertical boundary. As particularly adapted to the casting of solid metal sheets, a metal in liquid form can be continuously fed into one end of the confinement region produced by the levitation and stabilization magnets and removed in solid form from the other end of confinement region. An additional magnet may be included for support at the edges of the confinement region where eddy currents loop.

Tribo-systems for Sheet Metal Forming

DEFF Research Database (Denmark)

Bay, Niels

2009-01-01

The present paper gives an overview of more than 10 years work by the author’s research group through participation in national as well as international framework programmes on developing and testing environmentally friendly lubricants and tool materials and coatings inhibiting galling. Partners ......’s research group has especially been involved in the development of a system of tribo-tests for sheet metal forming and in testing and modelling of friction and limits of lubrication of new, environmentally friendly lubricants and tool materials....

Application of Multivariate Adaptive Regression Splines to Sheet Metal Bending Process for Springback Compensation

Directory of Open Access Journals (Sweden)

Dilan Rasim Aşkın

2016-01-01

Full Text Available An intelligent regression technique is applied for sheet metal bending processes to improve bending performance. This study is a part of another extensive study, automated sheet bending assistance for press brakes. Data related to material properties of sheet metal is collected in an online manner and fed to an intelligent system for determining the most accurate punch displacement without any offline iteration or calibration. The overall system aims to reduce the production time while increasing the performance of press brakes.

Friction and lubrication modelling in sheet metal forming: Influence of lubrication amount, tool roughness and sheet coating on product quality

Science.gov (United States)

Hol, J.; Wiebenga, J. H.; Carleer, B.

2017-09-01

In the stamping of automotive parts, friction and lubrication play a key role in achieving high quality products. In the development process of new automotive parts, it is therefore crucial to accurately account for these effects in sheet metal forming simulations. This paper presents a selection of results considering friction and lubrication modelling in sheet metal forming simulations of a front fender product. For varying lubrication conditions, the front fender can either show wrinkling or fractures. The front fender is modelled using different lubrication amounts, tool roughness’s and sheet coatings to show the strong influence of friction on both part quality and the overall production stability. For this purpose, the TriboForm software is used in combination with the AutoForm software. The results demonstrate that the TriboForm software enables the simulation of friction behaviour for varying lubrication conditions, i.e. resulting in a generally applicable approach for friction characterization under industrial sheet metal forming process conditions.

Observations on Mode I ductile tearing in sheet metals

DEFF Research Database (Denmark)

El-Naaman, Salim Abdallah; Nielsen, Kim Lau

2013-01-01

Cracked ductile sheet metals, subject to Mode I tearing, have been observed to display a variety of fracture surface morphologies depending on the material properties, and a range of studies on the fracture surface appearance have been published in the literature. Whereas classical fractures...

Testing of environmentally friendly lubricants for sheet metal forming

DEFF Research Database (Denmark)

Bay, Niels; Olsson, David Dam; Andreasen, Jan Lasson

2005-01-01

the authors have especially been involved in the development of a system of test methods for sheet metal forming and in testing of friction and limits of lubrication of new, environmentally friendly lubricants. An overview of the developed tests is presented together with selected results....

The Effect of Grinding and Polishing Procedure of Tool Steels in Sheet Metal Forming

DEFF Research Database (Denmark)

Lindvall, F.; Bergström, J.; Krakhmalev, P.

2010-01-01

The surface finish of tools in sheet metal forming has a large influence on the performance of the forming tool. Galling, concern of wear in sheet metal forming, is a severe form of adhesive wear where sheet material is transferred on to the tool surface. By polishing the tools to a fine surface ...... 40 and Vanadis 6 and up to ten different grinding and polishing treatments were tested against AISI 316 stainless steel. The tests showed that an optimum surface preparation might be found at the transition between abrasive and adhesive wear....

Experimental determination of spring back and thinning effect of aluminum sheet metal during L-bending operation

International Nuclear Information System (INIS)

Dilip Kumar, K.; Appukuttan, K.K.; Neelakantha, V.L.; Naik, Padmayya S.

2014-01-01

Highlights: • The spring back and thinning effect during L-bending was determined on aluminum sheet. • Beyond a particular clearance, the above said effects are linearly increasing. • Below the critical clearance scratches will occur on the surface due to wear. • As the clearance reduces, the wear rate increases on the punching surface. - Abstract: In automotive industry, significant efforts are being put forth to replace steel sheets with aluminum sheets for various applications. Besides its higher cost, there are several technical hurdles for wide usage of aluminum sheets in forming. Major problems in aluminum sheet metal forming operations are deformation errors and spring back effect. These problems are dependent on the number of parameters such as die and tool geometry, friction condition, loading condition and anisotropic properties of the metal. To predict the exact shape, the geometry based punch contact program must be used. The shape changes once the punch is withdrawn, because of the materials elasticity. Prediction of such a spring back effect is a major challenging problem in industry involving sheet metal forming operations. It also needs applying appropriate back tension during the forming complex shapes. Slight deformation of the metal leads to non-axisymmetric loading. One can predict the residual stress by determining plastic and elastic deformation. Thus appropriate spring back effect can be investigated. The present investigation was carried out to determine the spring back and thinning effect of aluminum sheet metal during L-bending operation. Number of specimens with thickness varying from 0.5 mm to 3.5 mm were prepared. The experiments were conducted for different clearances between punch and die. It is observed that, beyond a particular clearance for each thickness of the sheet metal, the spring back and thinning effects were linearly increasing. However, below the critical clearance, scratches on the surface of the sheet metal were

Optimal Magnetic Field Shielding Method by Metallic Sheets in Wireless Power Transfer System

Directory of Open Access Journals (Sweden)

Feng Wen

2016-09-01

Full Text Available To meet the regulations established to limit human exposure to time-varying electromagnetic fields (EMFs such as the International Committee on Non-Ionizing Radiation Protection (ICNIRP guidelines, thin metallic sheets are often used to shield magnetic field leakage in high power applications of wireless power transfer (WPT systems based on magnetic field coupling. However, the metals in the vicinity of the WPT coils cause the decrease of self and mutual inductances and increase of effective series resistance; as such, the electric performance including transmission power and the efficiency of the system is affected. With the research objective of further investigating excellent shielding effectiveness associated with system performance, the utilization of the optimal magnetic field shielding method by metallic sheets in magnetic field coupling WPT is carried out in this paper. The circuit and 3D Finite Element Analysis (FEA models are combined to predict the magnetic field distribution and electrical performance. Simulation and experiment results show that the method is very effective by obtaining the largest possible coupling coefficient of the WPT coils within the allowable range and then reducing the value nearest to and no smaller than the critical coupling coefficient via geometric unbroken metallic sheets. The optimal magnetic field shielding method which considers the system efficiency, transmission power, transmission distance, and system size is also achieved using the analytic hierarchy process (AHP. The results can benefit WPT by helping to achieve efficient energy transfer and safe use in metal shielded equipment.

Computer controlled experimental device for investigations of tribological influences in sheet metal forming

Directory of Open Access Journals (Sweden)

Milan Djordjevic

2012-05-01

Full Text Available Sheet metal forming, especially deep drawing process, is influenced by many factors. Blank holding force and drawbead displacement are two of them that can be controlled during the forming process. For this purpose, electro-hydraulic computerized sheet-metal strip sliding device has been constructed. Basic characteristic of this device is realization of variable contact pressure and drawbead height as functions of time or stripe displacement. There are both, pressure and drawbead, ten linear and nonlinear functions. Additional features consist of the ability to measure drawing force, contact pressure, drawbead displacement etc. Presented in the paper are the device overview and the first results of steel sheet stripe sliding over rounded  drawbead.

COMPUTER CONTROLLED EXPERIMENTAL DEVICE FOR INVESTIGATIONS OF TRIBOLOGICAL INFLUENCES IN SHEET METAL FORMING

Directory of Open Access Journals (Sweden)

Tomislav Vujinović

2012-05-01

Full Text Available Sheet metal forming, especially deep drawing process is influenced by many factors. Blank holding force and drawbead displacement are two of them that can be controlled during the forming process.For this purpose, an electro-hydraulic computerized sheet-metal strip sliding device has been constructed. The basic characteristic of this device is realization of variable contact pressure and drawbead height as functions of time or stripe displacement. There are both, pressure and drawbead, ten linear and nonlinear functions. Additional features consist of the ability to measure drawing force, contact pressure, drawbead displacement etc.The device overview and first results of steel sheet stripe sliding over rounded drawbead are presented in the paper.

Springback prediction in sheet metal forming process based on the hybrid SA

International Nuclear Information System (INIS)

Guo Yuqin; Jiang Hong; Wang Xiaochun; Li Fuzhu

2005-01-01

In terms of the intensive similarity between the sheet metal forming-springback process and that of the annealing of metals, it is suggested that the simulation of the sheet metal forming process is performed with the Nonlinear FEM and the springback prediction is implemented by solving the large-scale combinational optimum problem established on the base of the energy descending and balancing in deformed part. The BFGS-SA hybrid SA approach is proposed to solve this problem and improve the computing efficiency of the traditional SA and its capability of obtaining the global optimum solution. At the same time, the correlative annealing strategies for the SA algorithm are determined in here. By comparing the calculation results of sample part with those of experiment measurement at the specified sections, the rationality of the schedule of springback prediction used and the validity of the BFGS-SA algorithm proposed are verified

Development of Multi-Scale Finite Element Analysis Codes for High Formability Sheet Metal Generation

International Nuclear Information System (INIS)

Nnakamachi, Eiji; Kuramae, Hiroyuki; Ngoc Tam, Nguyen; Nakamura, Yasunori; Sakamoto, Hidetoshi; Morimoto, Hideo

2007-01-01

In this study, the dynamic- and static-explicit multi-scale finite element (F.E.) codes are developed by employing the homogenization method, the crystalplasticity constitutive equation and SEM-EBSD measurement based polycrystal model. These can predict the crystal morphological change and the hardening evolution at the micro level, and the macroscopic plastic anisotropy evolution. These codes are applied to analyze the asymmetrical rolling process, which is introduced to control the crystal texture of the sheet metal for generating a high formability sheet metal. These codes can predict the yield surface and the sheet formability by analyzing the strain path dependent yield, the simple sheet forming process, such as the limit dome height test and the cylindrical deep drawing problems. It shows that the shear dominant rolling process, such as the asymmetric rolling, generates ''high formability'' textures and eventually the high formability sheet. The texture evolution and the high formability of the newly generated sheet metal experimentally were confirmed by the SEM-EBSD measurement and LDH test. It is concluded that these explicit type crystallographic homogenized multi-scale F.E. code could be a comprehensive tool to predict the plastic induced texture evolution, anisotropy and formability by the rolling process and the limit dome height test analyses

Research on NC laser combined cutting optimization model of sheet metal parts

Science.gov (United States)

Wu, Z. Y.; Zhang, Y. L.; Li, L.; Wu, L. H.; Liu, N. B.

2017-09-01

The optimization problem for NC laser combined cutting of sheet metal parts was taken as the research object in this paper. The problem included two contents: combined packing optimization and combined cutting path optimization. In the problem of combined packing optimization, the method of “genetic algorithm + gravity center NFP + geometric transformation” was used to optimize the packing of sheet metal parts. In the problem of combined cutting path optimization, the mathematical model of cutting path optimization was established based on the parts cutting constraint rules of internal contour priority and cross cutting. The model played an important role in the optimization calculation of NC laser combined cutting.

Development of a Prediction Model Based on RBF Neural Network for Sheet Metal Fixture Locating Layout Design and Optimization.

Science.gov (United States)

Wang, Zhongqi; Yang, Bo; Kang, Yonggang; Yang, Yuan

2016-01-01

Fixture plays an important part in constraining excessive sheet metal part deformation at machining, assembly, and measuring stages during the whole manufacturing process. However, it is still a difficult and nontrivial task to design and optimize sheet metal fixture locating layout at present because there is always no direct and explicit expression describing sheet metal fixture locating layout and responding deformation. To that end, an RBF neural network prediction model is proposed in this paper to assist design and optimization of sheet metal fixture locating layout. The RBF neural network model is constructed by training data set selected by uniform sampling and finite element simulation analysis. Finally, a case study is conducted to verify the proposed method.

Influence of part orientation on the geometric accuracy in robot-based incremental sheet metal forming

Science.gov (United States)

Störkle, Denis Daniel; Seim, Patrick; Thyssen, Lars; Kuhlenkötter, Bernd

2016-10-01

This article describes new developments in an incremental, robot-based sheet metal forming process (`Roboforming') for the production of sheet metal components for small lot sizes and prototypes. The dieless kinematic-based generation of the shape is implemented by means of two industrial robots, which are interconnected to a cooperating robot system. Compared to other incremental sheet metal forming (ISF) machines, this system offers high geometrical form flexibility without the need of any part-dependent tools. The industrial application of ISF is still limited by certain constraints, e.g. the low geometrical accuracy. Responding to these constraints, the authors present the influence of the part orientation and the forming sequence on the geometric accuracy. Their influence is illustrated with the help of various experimental results shown and interpreted within this article.

Identification of non-linear kinematic hardening with bending and unbending tests in anisotropic sheet-metals

International Nuclear Information System (INIS)

Brunet, M.; Morestin, F.; Godereaux, S.

2000-01-01

An inverse identification technique is proposed based on bending-unbending experiments on anisotropic sheet-metal strips. The initial anisotropy theory of plasticity is extended to include the concept of combined isotropic and non-linear kinematic hardening. This theory is adopted to characterise the anisotropic hardening due to loading-unloading which occurs in sheet-metal forming processes. To this end, a specific bending-unbending apparatus has been built to provide experimental moment-curvature curves. The constant bending moment applied over the length of the specimen to determine numerically the strain-stress behaviour but without Finite Element Analysis. Four constitutive parameters have to be identified by an inverse approach. Our identification results show that bending-unbending tests are suitable to model quite accurately the constitutive behaviour of sheet metals under complex loading paths. (author)

A Collaborative Design Curriculum for Reviving Sheet Metal Handicraft

Science.gov (United States)

Chan, Patrick K. C.

2015-01-01

Galvanised sheet metal was a popular and important material for producing handmade home utensils in Hong Kong from the 1930s onwards. It was gradually replaced by new materials like stainless steel and plastic because similar goods made with these are cheaper, more standardised, more durable and of much better quality. The handicrafts behind sheet…

Development of a Prediction Model Based on RBF Neural Network for Sheet Metal Fixture Locating Layout Design and Optimization

Directory of Open Access Journals (Sweden)

Zhongqi Wang

2016-01-01

Full Text Available Fixture plays an important part in constraining excessive sheet metal part deformation at machining, assembly, and measuring stages during the whole manufacturing process. However, it is still a difficult and nontrivial task to design and optimize sheet metal fixture locating layout at present because there is always no direct and explicit expression describing sheet metal fixture locating layout and responding deformation. To that end, an RBF neural network prediction model is proposed in this paper to assist design and optimization of sheet metal fixture locating layout. The RBF neural network model is constructed by training data set selected by uniform sampling and finite element simulation analysis. Finally, a case study is conducted to verify the proposed method.

Lubricant Test Methods for Sheet Metal Forming

DEFF Research Database (Denmark)

Bay, Niels; Olsson, David Dam; Andreasen, Jan Lasson

2008-01-01

appearing in different sheet forming operations such as stretch forming, deep drawing, ironing and punching. The laboratory tests have been especially designed to model the conditions in industrial production. Application of the tests for evaluating new lubricants before introducing them in production has......Sheet metal forming of tribologically difficult materials such as stainless steel, Al-alloys and Ti-alloys or forming in tribologically difficult operations like ironing, punching or deep drawing of thick plate requires often use of environmentally hazardous lubricants such as chlorinated paraffin...... oils in order to avoid galling. The present paper describes a systematic research in the development of new, environmentally harmless lubricants focusing on the lubricant testing aspects. A system of laboratory tests has been developed to study the lubricant performance under the very varied conditions...

Improvements in FE-analysis of real-life sheet metal forming

NARCIS (Netherlands)

Huetink, Han; van den Boogaard, Antonius H.; Geijselaers, Hubertus J.M.; Meinders, Vincent T.

2000-01-01

An overview will be presented of recent developments concerning the application and development of computer codes for numerical simulation of sheet metal forming processes. In this paper attention is paid to some strategies which are followed to improve the accuracy and to reduce the computation

An expert system for process planning of sheet metal parts produced ...

Indian Academy of Sciences (India)

Sachin Salunkhe

set of production rules and frames for process planning of axisymmetric deep ... parameters for design of stamping die for manufacturing of circular cup with ..... proper sequence of operations to manufacture sheet metal part correctly and ...

Industrial sheet metals for nanocrystalline dye-sensitized solar cell structures

Energy Technology Data Exchange (ETDEWEB)

Toivola, Minna; Ahlskog, Fredrik; Lund, Peter [Laboratory of Advanced Energy Systems, Department of Engineering Physics and Mathematics, Helsinki University of Technology, P.O. Box 4100, FIN-02015 TKK (Finland)

2006-11-06

Direct integration of dye-sensitized solar cells (DSSC) onto industrial sheet metals has been studied. The stability of the metals, including zinc-coated and plain carbon steel, stainless steel and copper in a standard iodine electrolyte was investigated with soaking and encapsulation tests. Stainless and carbon steel showed sufficient stability and were used as the cell counter-electrodes, yielding cells with energy conversion efficiencies of 3.6% and 3.1%, respectively. A DSSC built on flexible steel substrates is a promising approach especially from the viewpoint of large-scale, cost-effective industrial manufacturing of the cells. (author)

Feasibility Study on Flexibly Reconfigurable Roll Forming Process for Sheet Metal and Its Implementation

Directory of Open Access Journals (Sweden)

Jun-Seok Yoon

2014-06-01

Full Text Available A multicurved sheet metal surface for a skin structure has usually been manufactured using a conventional die forming process involving the use of both a die and a press machine in accordance with the product shape. However, such processes are economically inefficient because additional production costs are incurred for the development and management of forming tools. To overcome this drawback, many alternative processes have been developed; however, these still suffer from problems due to defects such as dimples and wrinkles occurring in the sheet. In this study, a new sheet metal forming process called the flexibly reconfigurable roll forming (FRRF process is proposed as an alternative to existing processes. Unlike existing processes, FRRF can reduce additional production costs resulting from material loss and significantly reduce forming errors. Furthermore, it involves the use of a smaller apparatus. The methodology and applicable procedure of the FRRF process are described. Numerical forming simulations of representative multicurved sheet surfaces are conducted using FEM. In addition, a simple apparatus is developed for verifying the feasibility of this process, and a doubly curved metal is formed to verify the applicability of the reconfigurable roller, a critical component in this forming process.

Finite element simulation and Experimental verification of Incremental Sheet metal Forming

Science.gov (United States)

Kaushik Yanamundra, Krishna; Karthikeyan, R., Dr.; Naranje, Vishal, Dr

2018-04-01

Incremental sheet metal forming is now a proven manufacturing technique that can be employed to obtain application specific, customized, symmetric or asymmetric shapes that are required by automobile or biomedical industries for specific purposes like car body parts, dental implants or knee implants. Finite element simulation of metal forming process is being performed successfully using explicit dynamics analysis of commercial FE software. The simulation is mainly useful in optimization of the process as well design of the final product. This paper focuses on simulating the incremental sheet metal forming process in ABAQUS, and validating the results using experimental methods. The shapes generated for testing are of trapezoid, dome and elliptical shapes whose G codes are written and fed into the CNC milling machine with an attached forming tool with a hemispherical bottom. The same pre-generated coordinates are used to simulate a similar machining conditions in ABAQUS and the tool forces, stresses and strains in the workpiece while machining are obtained as the output data. The forces experimentally were recorded using a dynamometer. The experimental and simulated results were then compared and thus conclusions were drawn.

TSCA Chemical Data Reporting Fact Sheet: Reporting Manufactured Chemical Substances from Metal Mining and Related Activities

Science.gov (United States)

This fact sheet provides guidance on the Chemical Data Reporting (CDR) rule requirements related to the reporting of mined metals, intermediates, and byproducts manufactured during metal mining and related activities.

A theoretical study on pure bending of hexagonal close-packed metal sheet

Science.gov (United States)

Mehrabi, Hamed; Yang, Chunhui

2018-05-01

Hexagonal close-packed (HCP) metals have quite different mechanical behaviours in comparison to conventional cubic metals such as steels and aluminum alloys [1, 2]. They exhibit a significant tension-compression asymmetry in initial yielding and subsequent plastic hardening. The reason for this unique behaviour can be attributed to their limited symmetric crystal structure, which leads to twining deformation [3-5]. This unique behaviour strongly influences sheet metal forming of such metals, especially for roll forming, in which the bending is dominant. Hence, it is crucial to represent constitutive relations of HCP metals for accurate estimation of bending moment-curvature behaviours. In this paper, an analytical model for asymmetric elastoplastic pure bending with an application of Cazacu-Barlat asymmetric yield function [6] is presented. This yield function considers the asymmetrical tension-compression behaviour of HCP metals by using second and third invariants of the stress deviator tensor and a specified constant, which can be expressed in terms of uniaxial yield stresses in tension and compression. As a case study, the analytical model is applied to predict the moment-curvature behaviours of AZ31B magnesium alloy sheets under uniaxial loading condition. Furthermore, the analytical model is implemented as a user-defined material through the UMAT interface in Abaqus [7, 8] for conducting pure bending simulations. The results show that the analytical model can reasonably capture the asymmetric tension-compression behaviour of the magnesium alloy. The predicted moment-curvature behaviour has good agreement with the experimental results. Furthermore, numerical results show a better accuracy by the application of the Cazacu-Barlat yield function than those using the von-Mises yield function, which are more conservative than analytical results.

Stretchable and bendable carbon nanotube on PDMS super-lyophobic sheet for liquid metal manipulation

International Nuclear Information System (INIS)

Kim, Daeyoung; Jung, Daewoong; Yoo, Jun Hyeon; Lee, Gil S; Lee, Jeong-Bong; Lee, Yunho; Choi, Wonjae; Yoo, Koangki

2014-01-01

We report a vertically-aligned carbon nanotube (CNT) forest on polydimethylsiloxane (PDMS) sheet as a novel widely stretchable and bendable anti-wetting super-lyophobic surface for naturally oxidized gallium-based liquid metals. The vertically-aligned CNT has inherent chemical inertness and a hierarchical texture combining micro/nanoscale roughness; these two characters render the developed sheet as a super-lyophobic substrate against gallium-based liquid metals. The vertically-aligned CNT forest was first grown on Si substrate and then transferred onto a PDMS sheet by imprinting. It was found that the transferred CNT on the PDMS sheet maintained its vertically-aligned nature as well as hierarchical micro/nano surface morphology. It was found that the static contact angles of the gallium-based liquid metal droplet on the CNT on Si and on the CNT on PDMS were both greater than 155° and the contact angle hysteresis on the CNT on Si was 4° and that on the transferred CNT on PDMS was 19°. These measurement results showed that the surface retains a super-lyophobic property before and after the CNT transfer onto PDMS. We tested the CNT on PDMS sheet for its mechanical flexibility using stretching (50% and 100%) and bending (curvature of 0.1 and 0.4 mm −1 ). We carried out a bouncing test and a rolling test on the stretched/bent CNT on the PDMS sheet and the results confirmed that the flexible sheet maintains anti-wetting characteristics under bending or stretching conditions. (paper)

Metals extraction from sea water

International Nuclear Information System (INIS)

Chryssostomidis, C.; Larue, G.J.; Morgan, D.T.

1981-01-01

A method and system for continuously extracting metals from sea water by deploying adsorber sheets in a suitable current of sea water, recovering the adsorber sheets after they become loaded with metal and eluting the metal from the recovered sheets. The system involves the use of hollow, perforated bobbins on which the sheets are rolled as they are recovered and through which elutant is introduced

Impulse Hydroforming Method for Very Thin Sheets from Metallic or Hybrid Materials

OpenAIRE

Beerwald, C.; Beerwald, M.; Dirksen, U.; Henselek, A.

2010-01-01

Forming of very thin metallic and hybrid material foils is a demanding task in several application areas as for example in food or pharmaceutical packaging industries. Narrow forming limits of very thin sheet metals as well as minor process reliability due to necessary exact tool manufacturing (small punch-die clearance), both, causes abiding interest in new and innovative forming processes. In this contribution a new method using high pressure pulses will be introduced to form small geometry...

48 CFR 53.301-1427 - Standard Form 1427, Inventory Schedule A-Construction Sheet (Metals in Mill Product Form).

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Standard Form 1427, Inventory Schedule A-Construction Sheet (Metals in Mill Product Form). 53.301-1427 Section 53.301-1427... Illustrations of Forms 53.301-1427 Standard Form 1427, Inventory Schedule A—Construction Sheet (Metals in Mill...

Compression deformation behaviors of sheet metals at various clearances and side forces

Directory of Open Access Journals (Sweden)

Zhan Mei

2015-01-01

Full Text Available Modeling sheet metal forming operations requires understanding of plastic behaviors of sheet metals along non-proportional strain paths. The plastic behavior under reversed uniaxial loading is of particular interest because of its simplicity of interpretation and its application to material elements drawn over a die radius and underwent repeated bending. However, the attainable strain is limited by failures, such as buckling and in-plane deformation, dependent on clearances and side forces. In this study, a finite element (FE model was established for the compression process of sheet specimens, to probe the deformation behavior. The results show that: With the decrease of the clearance from a very large value to a very small value, four defects modes, including plastic t-buckling, micro-bending, w-buckling, and in-plane compression deformation will occur. With the increase of the side force from a very small value to a very large value, plastic t-buckling, w-buckling, uniform deformation, and in-plane compression will occur. The difference in deformation behaviors under these two parameters indicates that the successful compression process without failures for sheet specimens only can be carried out under a reasonable side force.

Application of Six Sigma Robust Optimization in Sheet Metal Forming

International Nuclear Information System (INIS)

Li, Y.Q.; Cui, Z.S.; Ruan, X.Y.; Zhang, D.J.

2005-01-01

Numerical simulation technology and optimization method have been applied in sheet metal forming process to improve design quality and shorten design cycle. While the existence of fluctuation in design variables or operation condition has great influence on the quality. In addition to that, iterative solution in numerical simulation and optimization usually take huge computational time or endure expensive experiment cost In order to eliminate effect of perturbations in design and improve design efficiency, a CAE-based six sigma robust design method is developed in this paper. In the six sigma procedure for sheet metal forming, statistical technology and dual response surface approximate model as well as algorithm of 'Design for Six Sigma (DFSS)' are integrated together to perform reliability optimization and robust improvement. A deep drawing process of a rectangular cup is taken as an example to illustrate the method. The optimization solutions show that the proposed optimization procedure not only improves significantly the reliability and robustness of the forming quality, but also increases optimization efficiency with approximate model

Testing and modelling of industrial tribo-systems for sheet metal forming

DEFF Research Database (Denmark)

Friis, Kasper Leth; Nielsen, Peter Søe; Bay, Niels

2008-01-01

Galling is a well-known problem in sheet metal forming of tribological difficult materials such as stainless steel. In this work new, environmentally friendly lubricants and wear resistant tool materials are tested in a laboratory environment using a strip reduction test as well as in a real...

Formability models for warm sheet metal forming analysis

Science.gov (United States)

Jiang, Sen

Several closed form models for the prediction of strain space sheet metal formability as a function of temperature and strain rate are proposed. The proposed models require only failure strain information from the uniaxial tension test at an elevated temperature setting and failure strain information from the traditionally defined strain space forming limit diagram at room temperature, thereby featuring the advantage of offering a full forming limit description without having to carry out expensive experimental studies for multiple modes of deformation under the elevated temperature. The Power law, Voce, and Johnson-Cook hardening models are considered along with the yield criterions of Hill's 48 and Logan-Hosford yield criteria. Acceptable correlations between the theory and experiment are reported for all the models under a plane strain condition. Among all the proposed models, the model featuring Johnson-Cook hardening model and Logan-Hosford yield behavior (LHJC model) was shown to best correlate with experiment. The sensitivity of the model with respect to various forming parameters is discussed. This work is significant to those aiming to incorporate closed-form formability models directly into numerical simulation programs for the purpose of design and analysis of products manufactured through the warm sheet metal forming process. An improvement based upon Swift's diffuse necking theory, is suggested in order to enhance the reliability of the model for biaxial stretch conditions. Theory relating to this improvement is provided in Appendix B.

Multi-Axial Deformation Setup for Microscopic Testing of Sheet Metal to Fracture

NARCIS (Netherlands)

Tasan, C.C.; Hoefnagels, J.P.M.; Dekkers, E.C.A.; Geers, M.G.D.

2012-01-01

While the industrial interest in sheet metal with improved specific-properties led to the design of new alloys with complex microstructures, predicting their safe forming limits and understanding their microstructural deformation mechanisms remain as significant challenges largely due to the

An expert system for process planning of sheet metal parts produced

Indian Academy of Sciences (India)

Process planning of sheet metal part is an important activity in the design of compound die. Traditional methods of carrying out this task are manual, tedious, time-consuming, error-prone and experiencebased. This paper describes the research work involved in the development of an expert system for process planning of ...

Testing of Lubricant Performance in Sheet Metal Forming

DEFF Research Database (Denmark)

Bay, Niels; Olsson, David Dam; Friis, Kasper Leth

2008-01-01

Increasing focus on environmental issues in industrial production has urged a number of sheet metal forming companies to look for new tribo-systems in order to substitute hazardous lubricants such as chlorinated paraffin oils. The problems are especially pronounced, when forming tribologically...... of the lubricant film causing pick-up of work piece material on the tool surface and scoring of subsequent work piece surfaces. The present paper gives an overview of more than 10 years work by the authors’ research group through participation in national as well as international framework programmes on developing...

Validation of formability of laminated sheet metal for deep drawing process using GTN damage model

Energy Technology Data Exchange (ETDEWEB)

Lim, Yongbin; Cha, Wan-gi; Kim, Naksoo [Department of Mechanical Engineering, Sogang University, 1 Sinsu-dong, Mapo-gu, Seoul, 121-742 (Korea, Republic of); Ko, Sangjin [Mold/die and forming technology team, Product prestige research lab, LG electronics, 222, LG-ro, Jinwi-myeon, Pyeongtaek-si, Gyeonggi-do, 451-713 (Korea, Republic of)

2013-12-16

In this study, we studied formability of PET/PVC laminated sheet metal which named VCM (Vinyl Coated Metal). VCM offers various patterns and good-looking metal steel used for appliances such as refrigerator and washing machine. But, this sheet has problems which are crack and peeling of film when the material is formed by deep drawing process. To predict the problems, we used finite element method and GTN (Gurson-Tvergaard-Needleman) damage model to represent damage of material. We divided the VCM into 3 layers (PET film, adhesive and steel added PVC) in finite element analysis model to express the crack and peeling phenomenon. The material properties of each layer are determined by reverse engineering based on tensile test result. Furthermore, we performed the simple rectangular deep drawing and simulated it. The simulation result shows good agreement with drawing experiment result in position, punch stroke of crack occurrence. Also, we studied the fracture mechanism of PET film on VCM by comparing the width direction strain of metal and PET film.

Tuning the p-type Schottky barrier in 2D metal/semiconductor interface:boron-sheet on MoSe2, and WSe2

Science.gov (United States)

Couto, W. R. M.; Miwa, R. H.; Fazzio, A.

2017-10-01

Van der Waals (vdW) metal/semiconductor heterostructures have been investigated through first-principles calculations. We have considered the recently synthesized borophene (Mannix et al 2015 Science 350 1513), and the planar boron sheets (S1 and S2) (Feng et al 2016 Nat. Chem. 8 563) as the 2D metal layer, and the transition metal dichalcogenides (TMDCs) MoSe2, and WSe2 as the semiconductor monolayer. We find that the energetic stability of those 2D metal/semiconductor heterojunctions is mostly ruled by the vdW interactions; however, chemical interactions also take place in borophene/TMDC. The electronic charge transfer at the metal/semiconductor interface has been mapped, where we find a a net charge transfer from the TMDCs to the boron sheets. Further electronic structure calculations reveal that the metal/semiconductor interfaces, composed by planar boron sheets S1 and S2, present a p-type Schottky barrier which can be tuned to a p-type ohmic contact by an external electric field.

Improving resistance welding of aluminum sheets by addition of metal powder

DEFF Research Database (Denmark)

Al Naimi, Ihsan K.; Al-Saadi, Moneer H.; Daws, Kasim M.

2015-01-01

. The improvement obtained is shown to be due to the development of a secondary bond in the joint beside the weld nugget increasing the total weld area. The application of powder additive is especially feasible, when using welding machines with insufficient current capacity for producing the required nugget size......In order to ensure good quality joints between aluminum sheets by resistance spot welding, a new approach involving the addition of metal powder to the faying surfaces before resistance heating is proposed. Three different metal powders (pure aluminum and two powders corresponding to the alloys AA....... In such cases the best results are obtained with pure aluminum powder....

RAPID FREEFORM SHEET METAL FORMING: TECHNOLOGY DEVELOPMENT AND SYSTEM VERIFICATION

Energy Technology Data Exchange (ETDEWEB)

Kiridena, Vijitha [Ford Scientific Research Lab., Dearborn, MI (United States); Verma, Ravi [Boeing Research and Technology (BR& T), Seattle, WA (United States); Gutowski, Timothy [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Roth, John [Pennsylvania State Univ., University Park, PA (United States)

2018-03-31

The objective of this project is to develop a transformational RApid Freeform sheet metal Forming Technology (RAFFT) in an industrial environment, which has the potential to increase manufacturing energy efficiency up to ten times, at a fraction of the cost of conventional technologies. The RAFFT technology is a flexible and energy-efficient process that eliminates the need for having geometry-specific forming dies. The innovation lies in the idea of using the energy resource at the local deformation area which provides greater formability, process control, and process flexibility relative to traditional methods. Double-Sided Incremental Forming (DSIF), the core technology in RAFFT, is a new concept for sheet metal forming. A blank sheet is clamped around its periphery and gradually deformed into a complex 3D freeform part by two strategically aligned stylus-type tools that follow a pre-described toolpath. The two tools, one on each side of the blank, can form a part with sharp features for both concave and convex shapes. Since deformation happens locally, the forming force at any instant is significantly decreased when compared to traditional methods. The key advantages of DSIF are its high process flexibility, high energy-efficiency, low capital investment, and the elimination of the need for massive amounts of die casting and machining. Additionally, the enhanced formability and process flexibility of DSIF can open up design spaces and result in greater weight savings.

Development and pilot production of three ingot-source beryllium sheet metal parts

International Nuclear Information System (INIS)

Floyd, D.R.

1975-01-01

Results of an extensive development program aimed at making three, separate, structural components from beryllium, using sheet-metal fabrication methods, are presented. Ingot-source beryllium sheet at thicknesses of 0.100, 0.125, and 0.170 inch is formed in a fully-recrystallized and in a partially-recrystallized condition. The tensile yield strength is 26,000 psi after full recrystallization. After partial recrystallization, tensile yield strength is between 35,000 and 45,000 psi, depending upon sheet thickness, heat treat temperature, and time at temperature. The high yield strength is retained in the parts after forming. (U.S.)

EXPERIMENTAL TESTING OF DRAW-BEAD RESTRAINING FORCE IN SHEET METAL FORMING

Institute of Scientific and Technical Information of China (English)

J.H. Yang; J. Chen; D.N. He; X. Y. Ruan

2003-01-01

Due to complexities of draw-bead restraining force calculated according to theory anddepending on sheet metal forming properties experiment testing system, a simplifiedmethod to calculate draw-bead restraining force is put forward by experimental methodin cup-shaped drawing process. The experimental results were compared with numer-ical results and proved agreement. It shows the method is effective.

Failure Analysis of a Sheet Metal Blanking Process Based on Damage Coupling Model

Science.gov (United States)

Wen, Y.; Chen, Z. H.; Zang, Y.

2013-11-01

In this paper, a blanking process of sheet metal is studied by the methods of numerical simulation and experimental observation. The effects of varying technological parameters related to the quality of products are investigated. An elastoplastic constitutive equation accounting for isotropic ductile damage is implemented into the finite element code ABAQUS with a user-defined material subroutine UMAT. The simulations of the damage evolution and ductile fracture in a sheet metal blanking process have been carried out by the FEM. In order to guarantee computation accuracy and avoid numerical divergence during large plastic deformation, a specified remeshing technique is successively applied when severe element distortion occurs. In the simulation, the evolutions of damage at different stage of the blanking process have been evaluated and the distributions of damage obtained from simulation are in proper agreement with the experimental results.

Controlling magnetism of MoS2 sheets by embedding transition-metal atoms and applying strain.

Science.gov (United States)

Zhou, Yungang; Su, Qiulei; Wang, Zhiguo; Deng, Huiqiu; Zu, Xiaotao

2013-11-14

Prompted by recent experimental achievement of transition metal (TM) atoms substituted in MoS2 nanostructures during growth or saturating existing vacancies (Sun et al., ACS Nano, 2013, 7, 3506; Deepak et al., J. Am. Chem. Soc., 2007, 129, 12549), we explored, via density functional theory, the magnetic properties of a series of 3d TM atoms substituted in a MoS2 sheet, and found that Mn, Fe, Co, Ni, Cu and Zn substitutions can induce magnetism in the MoS2 sheet. The localizing unpaired 3d electrons of TM atoms respond to the introduction of a magnetic moment. Depending on the species of TM atoms, the substituted MoS2 sheet can be a metal, semiconductor or half-metal. Remarkably, the applied elastic strain can be used to control the strength of the spin-splitting of TM-3d orbitals, leading to an effective manipulation of the magnetism of the TM-substituted MoS2 sheet. We found that the magnetic moment of the Mn- and Fe-substituted MoS2 sheets can monotonously increase with the increase of tensile strain, while the magnetic moment of Co-, Ni-, Cu- and Zn-substituted MoS2 sheets initially increases and then decreases with the increase of tensile strain. An instructive mechanism was proposed to qualitatively explain the variation of magnetism with elastic strain. The finding of the magnetoelastic effect here is technologically important for the fabrication of strain-driven spin devices on MoS2 nanostructures, which allows us to go beyond the current scope limited to the spin devices within graphene and BN-based nanostructures.

Multi-objective optimization under uncertainty for sheet metal forming

Directory of Open Access Journals (Sweden)

Lafon Pascal

2016-01-01

Full Text Available Aleatory uncertainties in material properties, blank thickness and friction condition are inherent and irreducible variabilities in sheet metal forming. Optimal design configurations, which are obtained by conventional design optimization methods, are not always able to meet the desired targets due to the effect of uncertainties. This paper proposes a multi-objective robust design optimization that aims to tackle this problem. Results obtained on a U shape draw bending benchmark show that spring-back effect can be controlled by optimizing process parameters.

A sheet metal forming simulation of automotive outer panels considering the behavior of air in die cavity

Science.gov (United States)

Choi, Kwang Yong; Kim, Yun Chang; Choi, Hee Kwan; Kang, Chul Ho; Kim, Heon Young

2013-12-01

During a sheet metal forming process of automotive outer panels, the air trapped between a blank sheet and a die tool can become highly compressed, ultimately influencing the blank deformation and the press force. To prevent this problem, vent holes are drilled into die tools and needs several tens to hundreds according to the model size. The design and the drilling of vent holes are based on expert's experience and try-out result and thus the process can be one of reasons increasing development cycle. Therefore the study on the size, the number, and the position of vent holes is demanded for reducing development cycle, but there is no simulation technology for analyzing forming defects, making numerical sheet metal forming process simulations that incorporate the fluid dynamics of air. This study presents a sheet metal forming simulation of automotive outer panels (a roof and a body side outer) that simultaneously simulates the behavior of air in a die cavity. Through CAE results, the effect of air behavior and vent holes to blank deformation was analyzed. For this study, the commercial software PAM-STAMP{trade mark, serif} and PAM-SAFE{trade mark, serif} was used.

A System of Test Methods for Sheet Metal Forming Tribology

DEFF Research Database (Denmark)

Bay, Niels; Olsson, David Dam; Andreasen, Jan Lasson

2007-01-01

Sheet metal forming of tribologically difficult materials such as stainless steel, Al-alloys and Ti-alloys or forming in tribologically difficult operations like ironing, punching or deep drawing of thick plate requires often use of environmentally hazardous lubricants such as chlorinated paraffin...... oils in order to avoid galling. The present paper describes a systematic research in the development of new, environmentally harmless lubricants focusing on the lubricant testing aspects. A system of laboratory tests has been developed to study the lubricant performance under the very varied conditions...... appearing in different sheet forming operations such as stamping, deep drawing, ironing and punching. The laboratory tests have been especially designed to model the conditions in industrial production....

Resin infusion of layered metal/composite hybrid and resulting metal/composite hybrid laminate

Science.gov (United States)

Cano, Roberto J. (Inventor); Grimsley, Brian W. (Inventor); Weiser, Erik S. (Inventor); Jensen, Brian J. (Inventor)

2009-01-01

A method of fabricating a metal/composite hybrid laminate is provided. One or more layered arrangements are stacked on a solid base to form a layered structure. Each layered arrangement is defined by a fibrous material and a perforated metal sheet. A resin in its liquid state is introduced along a portion of the layered structure while a differential pressure is applied across the laminate structure until the resin permeates the fibrous material of each layered arrangement and fills perforations in each perforated metal sheet. The resin is cured thereby yielding a metal/composite hybrid laminate.

EXPERIMENTAL TESTING OF DRAW—BEAD RESTRAINING FORCE IN SHEET METAL FORMING

Institute of Scientific and Technical Information of China (English)

J.H.Yang; J.Chen; 等

2003-01-01

Due to complexities of draw-bead restraining force calculated according to theory and depending on sheet metal forming properties experiment testing system,a simplified method to calculate draw-bead restraining force is put forward by experimental method in cup-shaped drawing process.The experimental results were compared with numer-ical results and proved agreement.It shows the method is effective.

Shop Math for the Metal Trades. Combination Welder Apprentice, Machinist Helper, Precision Metal Finisher, Sheet Metal Worker Apprentice. A Report on Metal Trades Industry Certified, Single-Concept, Mathematical Learning Projects to Eliminate Student Math Fears.

Science.gov (United States)

Newton, Lawrence R.

This project (1) identifies basic and functional mathematics skills (shop mathematics skills), (2) provides pretests on these functional mathematics skills, and (3) provides student learning projects (project sheets) that prepare metal trades students to read, understand, and apply mathematics and measuring skills that meet entry-level job…

PHYSICAL BASES OF SYSTEMS CREATION FOR MAGNETIC-IMPULSIVE ATTRACTION OF THIN-WALLED SHEET METALS

Directory of Open Access Journals (Sweden)

Y. Batygin

2009-01-01

Full Text Available The work is dedicated to the physical base of systems creating for the thin-walled sheet metals magnetic pulse attraction. Some practical realization models of the author’s suggestions are represented.

Prediction Of Formability In Sheet Metal Forming Processes Using A Local Damage Model

International Nuclear Information System (INIS)

Teixeira, P.; Santos, Abel; Cesar Sa, J.; Andrade Pires, F.; Barata da Rocha, A.

2007-01-01

The formability in sheet metal forming processes is mainly conditioned by ductile fracture resulting from geometric instabilities due to necking and strain localization. The macroscopic collapse associated with ductile failure is a result of internal degradation described throughout metallographic observations by the nucleation, growth and coalescence of voids and micro-cracks. Damage influences and is influenced by plastic deformation and therefore these two dissipative phenomena should be coupled at the constitutive level. In this contribution, Lemaitre's ductile damage model is coupled with Hill's orthotropic plasticity criterion. The coupling between damaging and material behavior is accounted for within the framework of Continuum Damage Mechanics (CDM). The resulting constitutive equations are implemented in the Abaqus/Explicit code, for the prediction of fracture onset in sheet metal forming processes. The damage evolution law takes into account the important effect of micro-crack closure, which dramatically decreases the rate of damage growth under compressive paths

Metallic nanomesh

Energy Technology Data Exchange (ETDEWEB)

Ren, Zhifeng; Sun, Tianyi; Guo, Chuanfei

2018-02-20

A transparent flexible nanomesh having at least one conductive element and sheet resistance less than 300.OMEGA./.quadrature. when stretched to a strain of 200% in at least one direction. The nanomesh is formed by depositing a sacrificial film, depositing, etching, and oxidizing a first metal layer on the film, etching the sacrificial film, depositing a second metal layer, and removing the first metal layer to form a nanomesh on the substrate.

Improvement of formability for fabricating thin continuously corrugated structures in sheet metal forming process

International Nuclear Information System (INIS)

Choi, Sung Woo; Park, Sang Hu; Park, Seong Hun; Ha, Man Yeong; Jeong, Ho Seung; Cho, Jong Rae

2012-01-01

A stamping process is widely used for fabricating various sheet metal parts for vehicles, airplanes, and electronic devices by the merit of low processing cost and high productivity. Recently, the use of thin sheets with a corrugated structure for sheet metal parts has rapidly increased for use in energy management devices, such as heat exchangers, separators in fuel cells, and many others. However, it is not easy to make thin corrugated structures directly using a single step stamping process due to their geometrical complexity and very thin thickness. To solve this problem, a multi step stamping (MSS) process that includes a heat treatment process to improve formability is proposed in this work: the sequential process is the initial stamping, heat treatment, and final shaping. By the proposed method, we achieved successful results in fabricating thin corrugated structures with an average thickness of 75μm and increased formability of about 31% compared to the single step stamping process. Such structures can be used in a plate-type heat exchanger requiring low weight and a compact shape

Designing a logistic control system : dealing with changes in Fokker's sheet metal unit

NARCIS (Netherlands)

Gomes, Javier

2008-01-01

The following report presents the results of the Logistics Design Project carried out at the sheet metal unit of Stork-Fokker AESP, from October 2007 to March 2008. Stork Fokker AESP designs, develops and produces advanced structures and electrical systems for the aerospace and defense industry. The

Some recent developments in sheet metal forming for production of lightweight automotive parts

Science.gov (United States)

Tisza, M.; Lukács, Zs; Kovács, P.; Budai, D.

2017-09-01

Low cost manufacturing in the automotive industry is one of the main targets due to the ever increasing global competition among car manufacturers all over the World. Sheet metal forming is one of the most important key technologies in the automotive industry; therefore the elaboration of new, innovative low cost manufacturing processes is one of the main objectives in sheet metal forming as well. In 2015 with the initiative of the Imperial College London a research consortium was established under the umbrella Low Cost Materials Processing Technologies for Mass Production of Lightweight Vehicles. The primary aim of this project is to provide affordable low cost weight reduction in mass production of vehicles considering the entire life-cycle. In this project, 19 European Institutions (Universities and Research Institutions) from 9 European countries are participating with the above targets. The University of Miskolc is one of the members of this research Consortium. In this paper, some preliminary results with the contributions of the University of Miskolc will be introduced.

Stress analysis and deformation prediction of sheet metal workpieces based on finite element simulation

OpenAIRE

Ren Penghao; Wang Aimin; Wang Xiaolong; Zhang Yanlin

2017-01-01

After aluminum alloy sheet metal parts machining, the residual stress release will cause a large deformation. To solve this problem, this paper takes a aluminum alloy sheet aerospace workpiece as an example, establishes the theoretical model of elastic deformation and the finite element model, and places quantitative initial stress in each element of machining area, analyses stress release simulation and deformation. Through different initial stress release simulative analysis of deformation ...

NUMISHEET 2016: 10th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes

International Nuclear Information System (INIS)

2016-01-01

The NUMISHEET conference series have been established as a world-class forum through which new intellectual ideas and technologies in the area of sheet metal forming simulation are exchanged. Previous NUMISHEET conferences have given enormous contributions to industry and academia in what regards the development of new methods and ideas for the numerical simulation of sheet metal forming processes. Previous NUMISHEET conferences were held in: Zurich (Switzerland, 1991), Isehara (Japan, 1993), Dearborn (USA, 1996), Besancon (France, 1999), Jeju Island (South Korea, 2002), Detroit (USA, 2005), Interlaken (Switzerland, 2008), Seoul (South Korea, 2011) and Melbourne (Australia, 2014). The NUMISHEET 2016 conference will be held in Bristol, UK. It features technical, keynote and plenary sessions and mini-symposiums in diverse sheet metal forming areas including the recently introduced incremental sheet forming and electromagnetic forming, as well as new prominent numerical methods such as IsoGeometric Analysis and meshless methods for sheet analysis. NUMISHEET 2016 will have eight academic plenary lectures delivered by worldwide recognised experts in the areas of sheet metal forming, material modelling and numerical methods in general. Also, NUMISHEET 2016 will have three industrial plenary lectures which will be addressed by three different companies with strong businesses in sheet metal forming processes: AutoForm, Crown Technology and Jaguar Land Rover. One of the most distinguishing features of NUMISHEET conference series is the industrial benchmark sessions, during which numerical simulations of industrial sheet formed parts are compared with experimental results from the industry. The benchmark sessions provide an extraordinary opportunity for networking, for the exchange of technologies related to sheet metal forming and for the numerical validation of sheet metal forming codes/software. Three benchmark studies have been organised in NUMISHEET 2016: BM1) &apos

Heated Hydro-Mechanical Deep Drawing of Magnesium Sheet Metal

Science.gov (United States)

Kurz, Gerrit

In order to reduce fuel consumption efforts have been made to decrease the weight of automobile constructions by increasing the use of lightweight materials. In this field of application magnesium alloys are important because of their low density. A promising alternative to large surfaced and thin die casting parts has been found in construction parts that are manufactured by sheet metal forming of magnesium. Magnesium alloys show a limited formability at room temperature. A considerable improvement of formability can be achieved by heating the material. Formability increases above a temperature of approximately T = 225 °C.

Ductile Damage and Fatigue Behavior of Semi-Finished Tailored Blanks for Sheet-Bulk Metal Forming Processes

Science.gov (United States)

Besserer, Hans-Bernward; Hildenbrand, Philipp; Gerstein, Gregory; Rodman, Dmytro; Nürnberger, Florian; Merklein, Marion; Maier, Hans Jürgen

2016-03-01

To produce parts from sheet metal with thickened functional elements, bulk forming operations can be employed. For this new process class, the term sheet-bulk metal forming has been established recently. Since sheet-bulk metal forming processes such as orbital forming generates triaxial stress and strain states, ductile damage is induced in the form of voids in the microstructure. Typical parts will experience cyclic loads during service, and thus, the influence of ductile damage on the fatigue life of parts manufactured by orbital forming is of interest. Both the formation and growth of voids were characterized following this forming process and then compared to the as-received condition of the ferritic deep drawing steel DC04 chosen for this study. Subsequent to the forming operation, the specimens were fatigued and the evolution of ductile damage and the rearrangement of the dislocation networks occurring during cyclic loading were determined. It was shown, that despite an increased ductile damage due to the forming process, the induced strain hardening has a positive effect on the fatigue life of the material. However, by analyzing the fatigued specimens a development of the ductile damage by an increasing number of voids and a change in the void shape were detected.

Theories, Methods and Numerical Technology of Sheet Metal Cold and Hot Forming Analysis, Simulation and Engineering Applications

CERN Document Server

Hu, Ping; Liu, Li-zhong; Zhu, Yi-guo

2013-01-01

Over the last 15 years, the application of innovative steel concepts in the automotive industry has increased steadily. Numerical simulation technology of hot forming of high-strength steel allows engineers to modify the formability of hot forming steel metals and to optimize die design schemes. Theories, Methods and Numerical Technology of Sheet Metal Cold and Hot Forming focuses on hot and cold forming theories, numerical methods, relative simulation and experiment techniques for high-strength steel forming and die design in the automobile industry. Theories, Methods and Numerical Technology of Sheet Metal Cold and Hot Forming introduces the general theories of cold forming, then expands upon advanced hot forming theories and simulation methods, including: • the forming process, • constitutive equations, • hot boundary constraint treatment, and • hot forming equipment and experiments. Various calculation methods of cold and hot forming, based on the authors’ experience in commercial CAE software f...

Implementation of virtual models from sheet metal forming simulation into physical 3D colour models using 3D printing

Science.gov (United States)

Junk, S.

2016-08-01

Today the methods of numerical simulation of sheet metal forming offer a great diversity of possibilities for optimization in product development and in process design. However, the results from simulation are only available as virtual models. Because there are any forming tools available during the early stages of product development, physical models that could serve to represent the virtual results are therefore lacking. Physical 3D-models can be created using 3D-printing and serve as an illustration and present a better understanding of the simulation results. In this way, the results from the simulation can be made more “comprehensible” within a development team. This paper presents the possibilities of 3D-colour printing with particular consideration of the requirements regarding the implementation of sheet metal forming simulation. Using concrete examples of sheet metal forming, the manufacturing of 3D colour models will be expounded upon on the basis of simulation results.

Effect of material scatter on the plastic behavior and stretchability in sheet metal forming

NARCIS (Netherlands)

Wiebenga, J.H.; Atzema, E.H.; Atzema, E.H.; An, Y.G.; Vegter, H.; van den Boogaard, Antonius H.

2014-01-01

Robust design of forming processes is gaining attention throughout the industry. To analyze the robustness of a sheet metal forming process using Finite Element (FE) simulations, an accurate input in terms of parameter scatter is required. This paper presents a pragmatic, accurate and economic

Assessing the formability of metallic sheets by means of localized and diffuse necking models

Science.gov (United States)

Comşa, Dan-Sorin; Lǎzǎrescu, Lucian; Banabic, Dorel

2016-10-01

The main objective of the paper consists in elaborating a unified framework that allows the theoretical assessment of sheet metal formability. Hill's localized necking model and the Extended Maximum Force Criterion proposed by Mattiasson, Sigvant, and Larsson have been selected for this purpose. Both models are thoroughly described together with their solution procedures. A comparison of the theoretical predictions with experimental data referring to the formability of a DP600 steel sheet is also presented by the authors.

Agile Production of Sheet Metal Aviation Components Using Disposable Electromagnetic Actuators

OpenAIRE

Carson, B.; Daehn, G.; Psyk, V.; Tekkaya, A. E.; Weddeling, C.; Woodward, S.

2010-01-01

Electromagnetic forming is a process used to produce high strain rates that improve the formability of sheet metal. The objective of this paper is to discuss the feasibility of the use of disposable actuators during electromagnetic forming of two aluminum components: an industry part whose main feature is a convex flange with two joggles, and a simple part with a one-dimensional curve throughout. The main forming complications after the parts were formed using conventional methods were the pr...

Fluid Structure Interaction Analysis in Manufacturing Metal/Polymer Macro-Composites

International Nuclear Information System (INIS)

Baesso, R.; Lucchetta, G.

2007-01-01

Polymer Injection Forming (PIF) is a new manufacturing technology for sheet metal-polymer macro-composites, which results from the combination of injection moulding and sheet metal forming. This process consists on forming the sheet metal according to the boundary of the mould cavity by means of the injected polymer. After cooling, the polymer bonds permanently to the metal resulting in a sheet metal-polymer macro-composite product. Comparing this process to traditional ones (where the polymeric and metal parts are joined together after separate forming) the main advantages are both reduction of production costs and increase of part quality. This paper presents a multi-physics numerical simulation of the process performed in the Ansys/CFX environment

Numerical modelling of microscopic lubricant flow in sheet metal forming. Application to plane strip drawing

DEFF Research Database (Denmark)

Carretta, Y.; Boman, R.; Bech, Jakob Ilsted

2017-01-01

This paper presents a numerical investigation of microscopic lubricant flows from the cavities to the plateaus of the surface roughness of metal sheets during forming processes. This phenomenon, called micro-plasto-hydrodynamic (MPH) lubrication, was observed experimentally in various situations...

Honeycomb metal panel

International Nuclear Information System (INIS)

1979-01-01

Product constituted by a honeycomb metal panel that can be employed to advantage for manufacturing lagging by sandwiching it between two plane sheets, utilized in particular in the nuclear industry where lagging has to have a very long life strength. The honeycomb metal panel is made of an expanded metal extrusion previously cut so as to form, after additional drawing, a honeycomb structure with square or rectangular cells with a plane surface [fr

Rubber pad forming - Efficient approach for the manufacturing of complex structured sheet metal blanks for food industry

Science.gov (United States)

Spoelstra, Paul; Djakow, Eugen; Homberg, Werner

2017-10-01

The production of complex organic shapes in sheet metals is gaining more importance in the food industry due to increasing functional and hygienic demands. Hence it is necessary to produce parts with complex geometries promoting cleanability and general sanitation leading to improvement of food safety. In this context, and especially when stainless steel has to be formed into highly complex geometries while maintaining desired surface properties, it is inevitable that alternative manufacturing processes will need to be used which meet these requirements. Rubber pad forming offers high potential when it comes to shaping complex parts with excellent surface quality, with virtually no tool marks and scratches. Especially in cases where only small series are to be produced, rubber pad forming processes offers both technological and economic advantages. Due to the flexible punch, variation in metal thickness can be used with the same forming tool. The investments to set-up Rubber pad forming is low in comparison to conventional sheet metal forming processes. The process facilitates production of shallow sheet metal parts with complex contours and bends. Different bending sequences in a multiple tool set-up can also be conducted. The planned contribution thus describes a brief overview of the rubber pad technology. It shows the prototype rubber pad forming machine which can be used to perform complex part geometries made from stainless steel (1.4301). Based on an analysis of the already existing systems and new machines for rubber pad forming processes, together with their process properties, influencing variables and areas of application, some relevant parts for the food industry are presented.

Ultrasonic measurement of through-thickness stress gradients in textured sheet metals

International Nuclear Information System (INIS)

Man Chising; Li Jianbo; Fan Xingyan; Lu Weiyang

2000-01-01

The objective of this investigation is to explore the possibility of using the dispersion of high-frequency Rayleigh waves for the evaluation of through-thickness stress gradients at the surface of metal sheets. We consider an orthorhombic sheet of cubic metal with through-thickness inhomogeneities in stress and texture, and adopt a coordinate system under which the rolling (RD), transverse (TD), and normal direction (ND) of the sheet are taken as the 1-, 2-, and 3-direction, respectively. We restrict our attention to the special case where only the stress components T 11 (x 3 ) and T 22 (x 3 ) in the sheet are nonzero, and consider only Rayleigh waves of sufficiently high frequency for which the sheet can be taken as the half-space x 3 ≥0. For Rayleigh waves of two different frequencies (with wave numbers k 1 and k k 2 respectively) propagating on the same wave path along either RD or TD, we appeal to an analysis of J. Li and Man to obtain a high-frequency asymptotic formula which gives the relative change in time-of-flight Δt/t 0 as (1/k 1 -1/k 2 ) times a linear combination of the derivatives T 11 ' (0), T 22 ' (0), W 4m0 ' (0)(m=0,2,4) and W 6m0 (0)(m=0,2,4,6) at the surface are ascertained and the material constants in the acoustoelastic consitutive equation of this polycrystal are known. An experiment was performed on an AA7075-T651 aluminum alloy beam, in which Δt/t 0 was measured for various values of T 11 (0) and T 11 ' (0) produced by beam bending (with (T 22 ≡0). The relevant texture coefficients of the beam were measured by X-ray diffraction. To obtain specific predictions from the aforementioned symptotic formula, we replace the material constants of the sample by their counterparts predicted for polycrystalline (pure) aluminum by the Man-Paroni model. The predictions and Δt/t 0 are then compared with the experimental results

An advanced constitutive model in the sheet metal forming simulation: the Teodosiu microstructural model and the Cazacu Barlat yield criterion

International Nuclear Information System (INIS)

Alves, J.L.; Oliveira, M.C.; Menezes, L.F.

2004-01-01

Two constitutive models used to describe the plastic behavior of sheet metals in the numerical simulation of sheet metal forming process are studied: a recently proposed advanced constitutive model based on the Teodosiu microstructural model and the Cazacu Barlat yield criterion is compared with a more classical one, based on the Swift law and the Hill 1948 yield criterion. These constitutive models are implemented into DD3IMP, a finite element home code specifically developed to simulate sheet metal forming processes, which generically is a 3-D elastoplastic finite element code with an updated Lagrangian formulation, following a fully implicit time integration scheme, large elastoplastic strains and rotations. Solid finite elements and parametric surfaces are used to model the blank sheet and tool surfaces, respectively. Some details of the numerical implementation of the constitutive models are given. Finally, the theory is illustrated with the numerical simulation of the deep drawing of a cylindrical cup. The results show that the proposed advanced constitutive model predicts with more exactness the final shape (medium height and ears profile) of the formed part, as one can conclude from the comparison with the experimental results

Calculation of electromagnetic force in electromagnetic forming process of metal sheet

International Nuclear Information System (INIS)

Xu Da; Liu Xuesong; Fang Kun; Fang Hongyuan

2010-01-01

Electromagnetic forming (EMF) is a forming process that relies on the inductive electromagnetic force to deform metallic workpiece at high speed. Calculation of the electromagnetic force is essential to understand the EMF process. However, accurate calculation requires complex numerical solution, in which the coupling between the electromagnetic process and the deformation of workpiece needs be considered. In this paper, an appropriate formula has been developed to calculate the electromagnetic force in metal work-piece in the sheet EMF process. The effects of the geometric size of coil, the material properties, and the parameters of discharge circuit on electromagnetic force are taken into consideration. Through the formula, the electromagnetic force at different time and in different positions of the workpiece can be predicted. The calculated electromagnetic force and magnetic field are in good agreement with the numerical and experimental results. The accurate prediction of the electromagnetic force provides an insight into the physical process of the EMF and a powerful tool to design optimum EMF systems.

Friction modelling in sheet metal forming simulations: application and validation on an U-Bend product

NARCIS (Netherlands)

Sigvant, Mats; Hol, Johan; Chezan, Toni; van den Boogaard, Ton; Hora, P.

2015-01-01

The accuracy of sheet metal forming simulations strongly depends on, amongst others, friction modelling. The industrial standard is to use the Coulomb friction model with a constant coefficient of friction. However, it is known that the true friction conditions are dependent on the tribology system,

Adaptive scallop height tool path generation for robot-based incremental sheet metal forming

Science.gov (United States)

Seim, Patrick; Möllensiep, Dennis; Störkle, Denis Daniel; Thyssen, Lars; Kuhlenkötter, Bernd

2016-10-01

Incremental sheet metal forming is an emerging process for the production of individualized products or prototypes in low batch sizes and with short times to market. In these processes, the desired shape is produced by the incremental inward motion of the workpiece-independent forming tool in depth direction and its movement along the contour in lateral direction. Based on this shape production, the tool path generation is a key factor on e.g. the resulting geometric accuracy, the resulting surface quality, and the working time. This paper presents an innovative tool path generation based on a commercial milling CAM package considering the surface quality and working time. This approach offers the ability to define a specific scallop height as an indicator of the surface quality for specific faces of a component. Moreover, it decreases the required working time for the production of the entire component compared to the use of a commercial software package without this adaptive approach. Different forming experiments have been performed to verify the newly developed tool path generation. Mainly, this approach serves to solve the existing conflict of combining the working time and the surface quality within the process of incremental sheet metal forming.

Numerical Prediction of Springback Shape of Severely Bent Sheet Metal

International Nuclear Information System (INIS)

Iwata, Noritoshi; Murata, Atsunobu; Yogo, Yasuhiro; Tsutamori, Hideo; Niihara, Masatomo; Ishikura, Hiroshi; Umezu, Yasuyoshi

2007-01-01

In the sheet metal forming simulation, the shell element widely used is assumed as a plane stress state based on the Mindlin-Reissner theory. Numerical prediction with the conventional shell element is not accurate when the bending radius is small compared to the sheet thickness. The main reason is because the strain and stress formulation of the conventional shell element does not fit the actual phenomenon. In order to predict precisely the springback of a bent sheet with a severe bend, a measurement method for through-thickness strain has been proposed. The strain was formulated based on measurement results and calculation results from solid element. Through-thickness stress distribution was formulated based on the equilibrium. The proposed shell element based on the formulations was newly introduced into the FEM code. The accuracy of this method's prediction of the springback shape of two bent processes has been confirmed. As a result, it was found that the springback shape even in severe bending can be predicted with high accuracy. Moreover, the calculation time in the proposed shell element is about twice that in the conventional shell element, and has been shortened to about 1/20 compared to a solid element

Studies in Cup Drawing Behavior of Polymer Laminated Sheet Metal

Science.gov (United States)

Elnagmi, M.; Jain, M.; Bruhis, M.; Nielsen, K.

2011-08-01

Axisymmetric deep drawing behavior of a polymer laminated sheet metal (PLSM) is investigated using an axisymmetric cup drawing test. PLSMs are of interest as a replacement for painted finishes for automotive applications as they have the potential to achieve good quality long lasting and aesthetically appealing surfaces on stamped parts. However, there is limited understanding of PLSMs in automotive deep drawing situations to produce complex 3-D parts. The tests are carried out using well-controlled, laboratory-based, dual-action, servo-hydraulic forming presses under blank-holder force and punch displacement control conditions. An optical strain mapping system is used to measure the surface strains (and to construct 3D strain maps) from the film side of the deformed samples for a range of forming conditions. Deep drawing characteristics such as punch load versus punch displacement traces, strain distribution along the cup profile, flange wrinkling and fracture characteristics are experimentally assessed for stainless steel-plastic film laminated sheet materials. Also the effect of lamination pressure on wrinkling and delamination is investigated for a decorative pressure sensitive adhesive film affixed to the stainless steel sheet.

Chemically-modified graphene sheets as an active layer for eco-friendly metal electroplating on plastic substrates

International Nuclear Information System (INIS)

Oh, Joon-Suk; Hwang, Taeseon; Nam, Gi-Yong; Hong, Jung-Pyo; Bae, Ah-Hyun; Son, Sang-Ik; Lee, Geun-Ho; Sung, Hak kyung; Choi, Hyouk Ryeol; Koo, Ja Choon; Nam, Jae-Do

2012-01-01

Eco-friendly nickel (Ni) electroplating was carried out on a plastic substrate using chemically modified graphene sheets as an active and conductive layer to initiate electroplating without using conventional pre-treatment or electroless metal-seeding processes. A graphene oxide (GO) solution was self-assembled on a polyethylene terephthalate (PET) film followed by evaporation to give GO layers (thickness around 6.5 μm) on PET (GO/PET) film. Then, the GO/PET film was chemically and thermally reduced to convert the GO layers to reduced graphene oxide (RGO) layers on the PET substrate. The RGO-coated PET (RGO/PET) film showed the sheet resistance of 100 Ω per square. On RGO/PET film, Ni electroplating was conducted under the constant-current condition and the entire surface of the PET film was completely metalized with Ni without any voids.

Pore-level determination of spectral reflection behaviors of high-porosity metal foam sheets

Science.gov (United States)

Li, Yang; Xia, Xin-Lin; Ai, Qing; Sun, Chuang; Tan, He-Ping

2018-03-01

Open cell metal foams are currently attracting attention and their radiative behaviors are of primary importance in high temperature applications. The spectral reflection behaviors of high-porosity metal foam sheets, bidirectional reflectance distribution function (BRDF) and directional-hemispherical reflectivity were numerically investigated. A set of realistic nickel foams with porosity from 0.87 to 0.97 and pore density from 10 to 40 pores per inch were tomographied to obtain their 3-D digital cell network. A Monte Carlo ray-tracing method was employed in order to compute the pore-level radiative transfer inside the network within the limit of geometrical optics. The apparent reflection behaviors and their dependency on the textural parameters and strut optical properties were comprehensively computed and analysed. The results show a backward scattering of the reflected energy at the foam sheet surface. Except in the cases of large incident angles, an energy peak is located almost along the incident direction and increases with increasing incident angles. Through an analytical relation established, the directional-hemispherical reflectivity can be related directly to the porosity of the foam sheet and to the complex refractive index of the solid phase as well as the specularity parameter which characterizes the local reflection model. The computations show that a linear decrease in normal-hemispherical reflectivity occurs with increasing porosity. The rate of this decrease is directly proportional to the strut normal reflectivity. In addition, the hemispherical reflectivity increases as a power function of the incident angle cosine.

Off-Line Testing of Tribo-Systems for Sheet Metal Forming Production

DEFF Research Database (Denmark)

Bay, Niels; Ceron, Ermanno

2014-01-01

Off-line testing of new tribo-systems for sheet metal forming production is an important issue, when new, environmentally benign lubricants are to be introduced. To obtain useful results it is, however, vital to ensure similar conditions as in the production process regarding the main tribo...... leading to very high tool/workpiece interface pressure and temperature in the second re-draw. Under such conditions only the best lubricant systems work satisfactory, and the paper shows how the performance of different tribo-systems in production may be predicted by off-line testing combined...

Forming limit diagrams for anisotropic metal sheets with different yield criteria

DEFF Research Database (Denmark)

Kuroda, M.; Tvergaard, Viggo

2000-01-01

For thin metal sheets subject to stretching under various in-plane tensile stress histories, localized necking is analyzed by using the M-K-model approach, and forming limit diagrams are drawn based on the critical strains for localization. The analyses account for plastic anisotropy......, and predictions are shown based on four different anisotropic plasticity models, which have all been fitted to agree with the same set of experimental data. Situations where the tensile axis is along one of the orthotropic axes of the anisotropy are studied, as well as situations where the tensile axis...

Development of dynamic explicit crystallographic homogenization finite element analysis code to assess sheet metal formability

International Nuclear Information System (INIS)

Nakamura, Yasunori; Tam, Nguyen Ngoc; Ohata, Tomiso; Morita, Kiminori; Nakamachi, Eiji

2004-01-01

The crystallographic texture evolution induced by plastic deformation in the sheet metal forming process has a great influence on its formability. In the present study, a dynamic explicit finite element (FE) analysis code is newly developed by introducing a crystallographic homogenization method to estimate the polycrystalline sheet metal formability, such as the extreme thinning and 'earing'. This code can predict the plastic deformation induced texture evolution at the micro scale and the plastic anisotropy at the macro scale, simultaneously. This multi-scale analysis can couple the microscopic crystal plasticity inhomogeneous deformation with the macroscopic continuum deformation. In this homogenization process, the stress at the macro scale is defined by the volume average of those of the corresponding microscopic crystal aggregations in satisfying the equation of motion and compatibility condition in the micro scale 'unit cell', where the periodicity of deformation is satisfied. This homogenization algorithm is implemented in the conventional dynamic explicit finite element code by employing the updated Lagrangian formulation and the rate type elastic/viscoplastic constitutive equation.At first, it has been confirmed through a texture evolution analyses in cases of typical deformation modes that Taylor's 'constant strain homogenization algorithm' yields extreme concentration toward the preferred crystal orientations compared with our homogenization one. Second, we study the plastic anisotropy effects on 'earing' in the hemispherical cup deep drawing process of pure ferrite phase sheet metal. By the comparison of analytical results with those of Taylor's assumption, conclusions are drawn that the present newly developed dynamic explicit crystallographic homogenization FEM shows more reasonable prediction of plastic deformation induced texture evolution and plastic anisotropy at the macro scale

75 FR 15741 - Sheet Metal Workers Internationl Association, Local 292: Troy, MI; Notice of Termination of...

Science.gov (United States)

2010-03-30

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-71,630] Sheet Metal Workers Internationl Association, Local 292: Troy, MI; Notice of Termination of Investigation Pursuant to Section 223..., Troy, Michigan. The petitioning workers were filing on behalf of workers employed by several...

A new constitutive model for prediction of springback in sheet metal forming

International Nuclear Information System (INIS)

Appiah, E.; Jain, M.

2004-01-01

With advances in computer capabilities, cost of sheet metal forming has being reducing mainly due to the reduction of trial and error approaches. At the moment, a complete process can be simulated on computer and appropriate forming conditions optimized before actual industrial forming process is carried out. While formability predictions have improved, the problem of springback exhibited by most metal, including aluminum alloy AA6111-T4, after forming persist and often leads to significant part fit-up problems during assembly. There are a number of factors that affect springback and perhaps the most significant one is constitutive equation. In this paper springback predicted by six advanced kinematic models are evaluated. In addition an improved constitutive kinematic model is presented. It is shown that by adding stress correction term (SCT) to Armstrong-Frederick model a relatively simple and yet accurate stress prediction could be obtained. The SCT was developed with the assumption that the yield surface remains convex, yield center depends on translation, size and shape variations of the yield surface. The model is implemented in a commercial finite element code (ABAQUS/Standard) via its user material interface (UMAT). Numerical simulations of U-bending were performed using automotive aluminum sheet material (AA6111-T4). It was noted that springback has inverse relationship with residual stress

Deformation limits of polymer coated metal sheets

NARCIS (Netherlands)

Van Den Bosch, M.J.W.J.P.; Schreurs, P.J.G; Geers, M.G.D.

2005-01-01

Polymer coated metals are increasingly used by the packaging and automotive industry. During industrial deformation processes (drawing, roll-forming, bending etc.) the polymer-metal laminate is highly deformed at high deformation rates. These forming conditions can affect the mechanical integrity

Research on Liquid Forming Process of Nickel Superalloys Thin Sheet Metals

Directory of Open Access Journals (Sweden)

Hyrcza-Michalska M.

2017-12-01

Full Text Available The paper presents the study of drawability of thin sheet metals made of a nickel superalloy Inconel type. The manufacturing process of axisymmetric cup – cone and a closed section profile in the form of a circular tube were designed and analyzed. In both cases, working fluid-oil was used in place of the rigid tools. The process of forming liquid is currently the only alternative method for obtaining complex shapes, coatings, and especially if we do it with high-strength materials. In the case of nickel superalloys the search for efficient methods to manufacture of the shaped shell is one of the most considerable problems in aircraft industry [1-5]. However, the automotive industries have the same problem with so-called advanced high-strength steels (AHSS. Due to this, both industrial problems have been examined and the emphasis have been put on the process of liquid forming (hydroforming. The study includes physical tests and the corresponding numerical simulations performed, using the software Eta/Dynaform 5.9. Numerical analysis of the qualitative and quantitative forecasting enables the formability of materials with complex and unusual characteristics of the mechanical properties and forming technology. It has been found that only the computer aided design based on physical and numerical modeling, makes efficient plastic processing possible using a method of hydroforming. Drawability evaluation based on the determination of the mechanical properties of complex characteristics is an indispensable element of this design in the best practice of industrial manufacturing products made of thin sheet metals.

Microstructure of bonding interface for resistance welding of Zr-based metallic glass sheets

International Nuclear Information System (INIS)

Kuroda, Toshio; Ikeuchi, Kenji; Shimada, Masahiro; Kobayashi, Akira; Kimura, Hisamichi; Inoue, Akihisa

2009-01-01

Resistance welding of Zr 55 Cu 30 Al 10 Ni 5 metallic glass sheets was investigated at 723 K in a supercooled liquid region. The welding time was changed from 5 s to 20 s at 723 K. The joint interface of the metallic glass was no defect and no crack. X-ray diffraction technique of the bonding interface of specimens was performed. The specimens showed halo patterns showing existence of only glassy phase, when the welding time was 5 s and 10 s. X-ray diffraction patterns of specimen bonded for 20 s showed crystalline peaks with halo patterns for the welding for 20 s. The crystalline phase at the bonding interface was small. Transmission electron micrograph at the bonding interface showed nanostructures of NiZr 2 and Al 5 Ni 3 Zr 2 . (author)

Development of JSTAMP-Works/NV and HYSTAMP for Multipurpose Multistage Sheet Metal Forming Simulation

Science.gov (United States)

Umezu, Yasuyoshi; Watanabe, Yuko; Ma, Ninshu

2005-08-01

Since 1996, Japan Research Institute Limited (JRI) has been providing a sheet metal forming simulation system called JSTAMP-Works packaged the FEM solvers of LS-DYNA and JOH/NIKE, which might be the first multistage system at that time and has been enjoying good reputation among users in Japan. To match the recent needs, "faster, more accurate and easier", of process designers and CAE engineers, a new metal forming simulation system JSTAMP-Works/NV is developed. The JSTAMP-Works/NV packaged the automatic healing function of CAD and had much more new capabilities such as prediction of 3D trimming lines for flanging or hemming, remote control of solver execution for multi-stage forming processes and shape evaluation between FEM and CAD. On the other way, a multi-stage multi-purpose inverse FEM solver HYSTAMP is developed and will be soon put into market, which is approved to be very fast, quite accurate and robust. Lastly, authors will give some application examples of user defined ductile damage subroutine in LS-DYNA for the estimation of material failure and springback in metal forming simulation.

Development of JSTAMP-Works/NV and HYSTAMP for Multipurpose Multistage Sheet Metal Forming Simulation

International Nuclear Information System (INIS)

Umezu, Yasuyoshi; Watanabe, Yuko; Ma, Ninshu

2005-01-01

Since 1996, Japan Research Institute Limited (JRI) has been providing a sheet metal forming simulation system called JSTAMP-Works packaged the FEM solvers of LS-DYNA and JOH/NIKE, which might be the first multistage system at that time and has been enjoying good reputation among users in Japan. To match the recent needs, 'faster, more accurate and easier', of process designers and CAE engineers, a new metal forming simulation system JSTAMP-Works/NV is developed. The JSTAMP-Works/NV packaged the automatic healing function of CAD and had much more new capabilities such as prediction of 3D trimming lines for flanging or hemming, remote control of solver execution for multi-stage forming processes and shape evaluation between FEM and CAD.On the other way, a multi-stage multi-purpose inverse FEM solver HYSTAMP is developed and will be soon put into market, which is approved to be very fast, quite accurate and robust.Lastly, authors will give some application examples of user defined ductile damage subroutine in LS-DYNA for the estimation of material failure and springback in metal forming simulation

Device of connecting the metal sheet lining a concrete enclosure to a pipe opening inside the enclosure

International Nuclear Information System (INIS)

Petit, Guy.

1975-01-01

Said invention relates to a sealed device connecting a metal sheet anchored on the internal side of a concrete vessel containing a hot pressurized fluid, with a metallic pipe opening inside said vessel. It is intended for heat insulating structures so-called 'hot skin' used for the pressure vessels of some boiling water reactors. Said invention is intended for different types of said pipe such as: the penetrations for the inlets and outlets of the primary circuit, or anchoring cylindrical sheaths used as supports of components or other elements located inside said pressure vessel [fr

Control the springback of metal sheets by using an artificial neural network

International Nuclear Information System (INIS)

Crina, Axinte

2007-01-01

One of the greatest challenges of manufacturing sheet metal parts is to obtain consistent parts dimensions. Springback is the major cause of variations and inconsistencies in the final part geometry. Obtaining a consistent and desirable amount of springback is extremely difficult due to the non-linear effects and interactions of process and material parameters. In this work, the ability of an artificial neural network model to predict optimum process parameters and tools geometry which allow to obtain minimum amount of springback is tested, in the case of a cylindrical deep-drawing process

The quantitative representation of fiber-and sheet-texture in metals of cubic system

International Nuclear Information System (INIS)

Kim, H.J.; Kim, S.C.; Chun, B.C.; Lee, C.Y.

1983-01-01

This is the first article of a series dealing with studies on the quantitative representation of fiber-and sheet-type textures in metals of cubic crystal system. Texture measurements by neutron diffraction method are analyzed using Bunge's series expansion method and the effect of series truncation is studied for samples of various texture sharpness. The present article describes two computer programs, TXFIB and TXSHT, develped for the analysis of the respective fiber-and sheet-type texture. Using these computer programs, the orientation distribution function can be expanded in the series of generalized spherical harmonics up to 58th term from 6 experimental pole figures as input. Estimations of various errors involved in the texture analysis and texture sharpness index are also included in the programs. (Author)

Corrosion behaviour of metallic and non-metallic materials in various media in the Anhydrite and Gypsum Mine Felsenau/AG

International Nuclear Information System (INIS)

Laske, D.; Wiedemann, K.H.

1983-10-01

The final underground disposal of radioactive wastes necessitates container materials with a good long-term resistance against corrosion from both external agents and the solidification matrix inside. For low- and medium-level active waste, repositories in anhydrite sites, among others, are under consideration. Sheet and plate samples from 14 metallic and 8 non-metallic materials have been tested for 5 years in a tunnel in the Anhydrite and Gypsum Mine Felsenau/AG for their corrosion resistance in the tunnel atmosphere, anhydrite powder, gypsum powder, gypsum, and cement. From the metallic materials tested, only chromium-nickel steel is corrosion resistant to all the media present. Zinc plated and tin plated iron sheet as well as aluminium and aluminium alloys are corrosion resistant only in the atmosphere of the tunnel, and lead plated iron sheet is resistant also in cement. Aluminium is dissolved in cement. Uncovered iron sheet undergoes severe corrosion. The non-metallic coatings tested (lacquer, stove lacquer, or synthetic resins) partially flake off already after one year's testing and are therefore not appropriate for iron sheet corrosion protection. No influence of the different media has been observed after 5 years on the 8 plastic materials tested (6 without, and 2 with glass fiber reinforcement). (author)

Method for casting thin metal objects

Science.gov (United States)

Pehrson, Brandon P; Moore, Alan F

2015-04-14

Provided herein are various embodiments of systems for casting thin metal plates and sheets. Typical embodiments include layers of mold cavities that are oriented vertically for casting the metal plates. In some embodiments, the mold cavities include a beveled edge such that the plates that are cast have a beveled edge. In some embodiments, the mold cavities are filled with a molten metal through an open horizontal edge of the cavity. In some embodiments, the mold cavities are filled through one or more vertical feed orifices. Further disclosed are methods for forming a thin cast metal plate or sheet where the thickness of the cast part is in a range from 0.005 inches to 0.2 inches, and the surface area of the cast part is in a range from 16 square inches to 144 square inches.

Control of Springback in Sheet Metal U-bending Through Design Experiment

International Nuclear Information System (INIS)

Chirita, Bogdan; Brabie, Gheorghe

2007-01-01

For the U-bending of sheet metals, springback represents the most important failure mode that is affecting the parts. The purpose of this study was to develop a method for the reduction or the elimination of springback from the designing stage of the forming process. This paper describes a numerical procedure that combines simulation of springback by finite element method with a fractional factorial design and proposes the optimization of the forming parameters and tools geometry for the reduction of springback intensity. At the end of the study we were able to obtain an important improvement of part precision using the parameters predicted by the factorial design

Final Air Toxics Standards for Clay Ceramics Manufacturing, Glass Manufacturing, and Secondary Nonferrous Metals Processing Area Sources Fact Sheet

Science.gov (United States)

This page contains a December 2007 fact sheet with information regarding the National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Clay Ceramics Manufacturing, Glass Manufacturing, and Secondary Nonferrous Metals Processing Area Sources

Testing new tribo-systems for sheet metal forming of advanced high strength steels and stainless steels

DEFF Research Database (Denmark)

Bay, Niels; Ceron, Ermanno

2014-01-01

of a methodology for off-line testing of new tribo-systems for advanced high strength steels and stainless steels. The methodology is presented and applied to an industrial case, where different tribo-systems are tested. A universal sheet tribotester has been developed, which can run automatically repetitive......Testing of new tribo-systems in sheet metal forming has become an important issue due to new legislation, which forces industry to replace current, hazardous lubricants. The present paper summarizes the work done in a recent PhD project at the Technical University of Denmark on the development...

Editorial input for the right price: tobacco industry support for a sheet metal indoor air quality manual.

Science.gov (United States)

Campbell, Richard; Balbach, Edith

2013-01-01

Following legal action in the 1990s, internal tobacco industry documents became public, allowing unprecedented insight into the industry's relationships with outside organizations. During the 1980s and 1990s, the National Energy Management Institute (NEMI), established by the Sheet Metal Workers International Association and the Sheet Metal and Air Conditioning Contractors' National Association, (SMACNA) received tobacco industry funding to establish an indoor air quality services program. But the arrangement also required NEMI to serve as an advocate for industry efforts to defeat indoor smoking bans by arguing that ventilation was a more appropriate solution to environmental tobacco smoke. Drawing on tobacco industry documents, this paper describes a striking example of the ethical compromises that accompanied NEMI's collaboration with the tobacco industry, highlighting the solicitation of tobacco industry financial support for a SMACNA indoor air quality manual in exchange for sanitizing references to the health impact of environmental tobacco smoke prior to publication.

High surface area graphene-supported metal chalcogenide assembly

Science.gov (United States)

Worsley, Marcus A.; Kuntz, Joshua D.; Orme, Christine A.

2017-04-25

Disclosed here is a method for hydrocarbon conversion, comprising contacting at least one graphene-supported assembly with at least one hydrocarbon feedstock, wherein the graphene-supported assembly comprises (i) a three-dimensional network of graphene sheets crosslinked by covalent carbon bonds and (ii) at least one metal chalcogenide compound disposed on the graphene sheets, wherein the chalcogen of the metal chalcogenide compound is selected from S, Se and Te, and wherein the metal chalcogenide compound accounts for at least 20 wt. % of the graphene-supported assembly.

Recovery and utilization of valuable metals from spent nuclear fuel. 3: Mutual separation of valuable metals

International Nuclear Information System (INIS)

Kirishima, K.; Shibayama, H.; Nakahira, H.; Shimauchi, H.; Myochin, M.; Wada, Y.; Kawase, K.; Kishimoto, Y.

1993-01-01

In the project ''Recovery and Utilization of Valuable Metals from Spent Fuel,'' mutual separation process of valuable metals recovered from spent fuel has been studied by using the simulated solution contained Pb, Ru, Rh, Pd and Mo. Pd was separated successfully by DHS (di-hexyl sulfide) solvent extraction method, while Pb was recovered selectively from the raffinate by neutralization precipitation of other elements. On the other hand, Rh was roughly separated by washing the precipitate with alkaline solution, so that Rh was refined by chelate resin CS-346. Outline of the mutual separation process flow sheet has been established of the combination of these techniques. The experimental results and the process flow sheet of mutual separation of valuable metals are presented in this paper

Perspective of metal encapsulation of waste

International Nuclear Information System (INIS)

Jardine, L.J.; Steindler, M.J.

1978-01-01

A conceptual flow sheet is presented for encapsulating solid, stabilized calcine (e.g., supercalcine) in a solid lead alloy, using existing or developing technologies. Unresolved and potential problem areas of the flow sheet are outlined and suggestions are made as how metal encapsulation might be applied to other solid wastes from the fuel cycle. It is concluded that metal encapsulation is a technique applicable to many forms of solid wastes and is likely to meet future waste isolation criteria and regulations

Polymer quenched prealloyed metal powder

Science.gov (United States)

Hajaligol, Mohammad R.; Fleischhauer, Grier; German, Randall M.

2001-01-01

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3 % Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Liquid metal steam generator

International Nuclear Information System (INIS)

Wolowodiuk, W.

1975-01-01

A liquid metal heated steam generator is described which in the event of a tube failure quickly exhausts out of the steam generator the products of the reaction between the water and the liquid metal. The steam is generated in a plurality of bayonet tubes which are heated by liquid metal flowing over them between an inner cylinder and an outer cylinder. The inner cylinder extends above the level of liquid metal but below the main tube sheet. A central pipe extends down into the inner cylinder with a centrifugal separator between it and the inner cylinder at its lower end and an involute deflector plate above the separator so that the products of a reaction between the liquid metal and the water will be deflected downwardly by the deflector plate and through the separator so that the liquid metal will flow outwardly and away from the central pipe through which the steam and gaseous reaction products are exhausted. (U.S.)

Metallic witness packs for behind-armour debris characterization

NARCIS (Netherlands)

Verolme, J.L.; Szymczak, M.; Broos, J.P.F.

1999-01-01

For the experimental characterization of behind-armour debris so-called metallic witness packs can be used. A metallic witness pack consists of an array of metallic plates interspaced by polystyrene foam sheets. To quantify the fragment mass and velocity from the corresponding hole area and position

Investigation of fatigue strength of tool steels in sheet-bulk metal forming

Science.gov (United States)

Pilz, F.; Gröbel, D.; Merklein, M.

2018-05-01

To encounter trends regarding an efficient production of complex functional components in forming technology, the process class of sheet-bulk metal forming (SBMF) can be applied. SBMF is characterized by the application of bulk forming operations on sheet metal, often in combination with sheet forming operations [1]. The combination of these conventional process classes leads to locally varying load conditions. The resulting load conditions cause high tool loads, which lead to a reduced tool life, and an uncontrolled material flow. Several studies have shown that locally modified tool surfaces, so-called tailored surfaces, have the potential to control the material flow and thus to increase the die filling of functional elements [2]. A combination of these modified tool surfaces and high tool loads in SBMF is furthermore critical for the tool life and leads to fatigue. Tool fatigue is hardly predictable and due to a lack of data [3], a challenge in tool design. Thus, it is necessary to provide such data for tool steels used in SBMF. The aim of this study is the investigation of the influence of tailored surfaces on the fatigue strength of the powder metallurgical tool steel ASP2023 (1.3344, AISI M3:2), which is typically used in cold forging applications, with a hardness 60 HRC ± 1 HRC. To conduct this investigation, the rotating bending test is chosen. As tailored surfaces, a DLC-coating and a surface manufactured by a high-feed-milling process are chosen. As reference a polished surface which is typical for cold forging tools is used. Before the rotating bending test, the surface integrity is characterized by measuring topography and residual stresses. After testing, the determined values of the surface integrity are correlated with the reached fracture load cycle to derive functional relations. Based on the gained results the investigated tailored surfaces are evaluated regarding their feasibility to modify tool surfaces within SBMF.

Study of the influence between the strength of antibending of working rolls on the widening during hot rolling of thin sheet metal

Directory of Open Access Journals (Sweden)

U. Muhin

2016-07-01

Full Text Available Based on the variation principle of Jourdan was developed a mathematical model of the process of widening freely in hot rolling of thin sheet metal. The principle applies to rigid-plastic materials and for the cinematically admissible area of speeds. The developed model allows to study the distribution of the widening on the length of the deformation zone depending on the parameters of the rolling process and sheet metal. Results are obtained, characterizing the size of the widening and effectiveness of the process control on tension at the entrance and exit from the stand. The widening is dependent on the strength of anti bending.

Tooling solutions for sheet metal forming and punching of lean duplex stainless steel

DEFF Research Database (Denmark)

Wadman, Boel; Madsen, Erik; Bay, Niels

2012-01-01

.4509 and lean duplex EN1.4162 in a production designed for austenitic stainless steels, such as EN1.4301 and 1.4401. The result is a guideline that summarizes how stainless material properties may affect tool degradation, and suggests tool solutions for reduced production disturbances and tool maintenance cost.......For producers of advanced stainless components the choice of stainless material influences not only the product properties, but also the tooling solution for sheet metal stamping. This work describes how forming and punching tools will be affected when introducing the stainless alloys ferritic EN1...

Trapping of point defects and segregation at the free surfaces of a metal sheet under irradiation

International Nuclear Information System (INIS)

Sarce, Alicia

2003-01-01

The migration of irradiation produced vacancies and interstitials to the free surfaces of a sheet of thickness d (pure metal and binary alloys AB of hcp structure) is calculated. For alloys, the irradiation temperature when no segregation exists (critical temperature) is obtained. The anisotropy of the diffusion of point defects in the hcp lattice is explicitly included in the calculations. (author)

Coating of metals

International Nuclear Information System (INIS)

Smith, F.

1978-01-01

A method is described for coating the surface of an article of Ti, Zr or Ta, or an alloy thereof, with a tinning metal or alloy, the article having a shape other than that of a sheet. The method comprises contacting the surface of the article at an elevated temperature with the molten tinning metal and moving an ultrasonically excited probe over the surface to be coated, the probe being in contact with the surface of the article and with the tinning metal. The tinning metal may be Sn or Zn or a binary alloy of Sn with Zn, Cd or Bi at a temperature of 300 0 to 450 0 C. The head of the probe may be shaped to conform with the surface of the article. The method may be used to form composite articles, and may be applied to a pre-tinned steel article. (U.K.)

Tunable color parallel tandem organic light emitting devices with carbon nanotube and metallic sheet interlayers

Energy Technology Data Exchange (ETDEWEB)

Oliva, Jorge; Desirena, Haggeo; De la Rosa, Elder [Centro de Investigaciones en Optica, A.P. 1-948, León, Guanajuato 37160 (Mexico); Papadimitratos, Alexios [Solarno Inc., Coppell, Texas 75019 (United States); University of Texas at Dallas, Richardson, Texas 75080 (United States); Zakhidov, Anvar A., E-mail: Zakhidov@utdallas.edu [Solarno Inc., Coppell, Texas 75019 (United States); University of Texas at Dallas, Richardson, Texas 75080 (United States); Energy Efficiency Center, National University of Science and Technology, MISiS, Moscow 119049 (Russian Federation)

2015-11-21

Parallel tandem organic light emitting devices (OLEDs) were fabricated with transparent multiwall carbon nanotube sheets (MWCNT) and thin metal films (Al, Ag) as interlayers. In parallel monolithic tandem architecture, the MWCNT (or metallic films) interlayers are an active electrode which injects similar charges into subunits. In the case of parallel tandems with common anode (C.A.) of this study, holes are injected into top and bottom subunits from the common interlayer electrode; whereas in the configuration of common cathode (C.C.), electrons are injected into the top and bottom subunits. Both subunits of the tandem can thus be monolithically connected functionally in an active structure in which each subunit can be electrically addressed separately. Our tandem OLEDs have a polymer as emitter in the bottom subunit and a small molecule emitter in the top subunit. We also compared the performance of the parallel tandem with that of in series and the additional advantages of the parallel architecture over the in-series were: tunable chromaticity, lower voltage operation, and higher brightness. Finally, we demonstrate that processing of the MWCNT sheets as a common anode in parallel tandems is an easy and low cost process, since their integration as electrodes in OLEDs is achieved by simple dry lamination process.

Forming Limits in Sheet Metal Forming for Non-Proportional Loading Conditions - Experimental and Theoretical Approach

International Nuclear Information System (INIS)

Ofenheimer, Aldo; Buchmayr, Bruno; Kolleck, Ralf; Merklein, Marion

2005-01-01

The influence of strain paths (loading history) on material formability is well known in sheet forming processes. Sophisticated experimental methods are used to determine the entire shape of strain paths of forming limits for aluminum AA6016-T4 alloy. Forming limits for sheet metal in as-received condition as well as for different pre-deformation are presented. A theoretical approach based on Arrieux's intrinsic Forming Limit Stress Curve (FLSC) concept is employed to numerically predict the influence of loading history on forming severity. The detailed experimental strain paths are used in the theoretical study instead of any linear or bilinear simplified loading histories to demonstrate the predictive quality of forming limits in the state of stress

Hydro mechanical deep-drawing and high pressure sheet metal forming as forming technologies for the production of complex parts made of magnesium sheet metal AZ31B-0; Hydromechanisches Tiefziehen und Hochdruckblechumformung als Verfahren zur Herstellung komplexer Bauteile aus Magnesiumfeinblechen des Typs AZ31B-0

Energy Technology Data Exchange (ETDEWEB)

Viehweger, B.; Richter, G.; Duering, M.; Karabet, A. [Lehrstuhlleiter, BTU Cottbus, Lehrstuhl Konstruktion und Fertigung, Konrad-Wachsmann Allee 1, 03046 Cottbus (Germany); Sviridov, A.; Hartmann, H.; Richter, U. [Forschungs- und Qualitaetszentrum Oderbruecke gGmbH Eisenhuettenstadt (Germany)

2004-07-01

Semi - finished sheet - metal products made of magnesium alloys such as AZ31B are known as better deformable at temperatures in the range of 175 C - 240 C. By means of hydroforming technologies, as there are hydro mechanical deep-drawing and high pressure sheet metal forming, the influence of different forming parameters on the forming results has been investigated. A more complex experimental geometry was deformed applying forming temperatures of 175 C, 200 C, 225 C and 240 C and accordingly adjusted forces of the blank holder. Concerning the applied forming - methods and experimental parameters the forming results have been evaluated and compared regarding the decrease of sheet thickness and the development of small radii. For some experimental parts, which have been deformed by means of high pressure sheet metal forming at temperatures of 175 C and 225 C, supplementary investigations have been carried out in order to determine the evolution of characteristic surface values in dependence on the forming operation. On the basis of these results practical recommendations for the limits of application of aforementioned forming technologies for AZ31B-0 magnesium sheet metal are given. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Eine gute Umformbarkeit von Blechhalbzeugen aus Magnesiumknetlegierungen stellt sich bekanntlich bei Anwendung von Umformtemperaturen im Bereich von 175 C - 240 C ein. Anhand der wirkmedienbasierten Umformverfahren hydromechanisches Tiefziehen und Hochdruckblechumformung ist an handelsueblichen AZ31B-0 Feinblechen die Einstellung unterschiedlicher Umformparameter erprobt worden. Unter Verwendung von Umformtemperaturen von 175 C, 200 C, 225 C und 240 C und entsprechend angepassten Niederhalterdruecken ist eine praxisnahe Versuchsgeometrie ''Minihood'' ausgeformt worden. Im Hinblick auf angewendete Umformverfahren und Versuchsparameter wurde an den Versuchsbauteilen die Blechdickenabnahme und die

A Model Based Approach to Increase the Part Accuracy in Robot Based Incremental Sheet Metal Forming

International Nuclear Information System (INIS)

Meier, Horst; Laurischkat, Roman; Zhu Junhong

2011-01-01

One main influence on the dimensional accuracy in robot based incremental sheet metal forming results from the compliance of the involved robot structures. Compared to conventional machine tools the low stiffness of the robot's kinematic results in a significant deviation of the planned tool path and therefore in a shape of insufficient quality. To predict and compensate these deviations offline, a model based approach, consisting of a finite element approach, to simulate the sheet forming, and a multi body system, modeling the compliant robot structure, has been developed. This paper describes the implementation and experimental verification of the multi body system model and its included compensation method.

Effect of strain path change on limits to ductility of anisotropic metal sheets

DEFF Research Database (Denmark)

Kuroda, M.; Tvergaard, Viggo

2000-01-01

of the anisotropic plasticity models, and it is shown that elastic straining plays a large role, as the stresses quickly move from one point of the yield surface to another. When the load is removed between steps, the stress point moves in a different manner, which results in quite different flow localization......Localized necking in thin metal sheets is analyzed by using the M-K-model approach, and the effect of a number of different non-proportional strain paths prior to the occurrence flow localization are considered. The analyses account for plastic anisotropy, using four different anisotropic...

Formability analysis of sheet metals by cruciform testing

Science.gov (United States)

Güler, B.; Alkan, K.; Efe, M.

2017-09-01

Cruciform biaxial tests are increasingly becoming popular for testing the formability of sheet metals as they achieve frictionless, in-plane, multi-axial stress states with a single sample geometry. However, premature fracture of the samples during testing prevents large strain deformation necessary for the formability analysis. In this work, we introduce a miniature cruciform sample design (few mm test region) and a test setup to achieve centre fracture and large uniform strains. With its excellent surface finish and optimized geometry, the sample deforms with diagonal strain bands intersecting at the test region. These bands prevent local necking and concentrate the strains at the sample centre. Imaging and strain analysis during testing confirm the uniform strain distributions and the centre fracture are possible for various strain paths ranging from plane-strain to equibiaxial tension. Moreover, the sample deforms without deviating from the predetermined strain ratio at all test conditions, allowing formability analysis under large strains. We demonstrate these features of the cruciform test for three sample materials: Aluminium 6061-T6 alloy, DC-04 steel and Magnesium AZ31 alloy, and investigate their formability at both the millimetre scale and the microstructure scale.

Method and mold for casting thin metal objects

Science.gov (United States)

Pehrson, Brandon P; Moore, Alan F

2014-04-29

Provided herein are various embodiments of systems for casting thin metal plates and sheets. Typical embodiments include layers of mold cavities that are oriented vertically for casting the metal plates. In some embodiments, the mold cavities include a beveled edge such that the plates that are cast have a beveled edge. In some embodiments, the mold cavities are filled with a molten metal through an open horizontal edge of the cavity. In some embodiments, the mold cavities are filled through one or more vertical feed orifices. Further disclosed are methods for forming a thin cast metal plate or sheet where the thickness of the cast part is in a range from 0.005 inches to 0.2 inches, and the surface area of the cast part is in a range from 16 square inches to 144 square inches.

Precision machining, sheet-metal work and welding at the heart of CERN

CERN Multimedia

2001-01-01

From the writing of specifications and the production of high-tech components, to technology transfer and call-out work on-site, the MF group in EST Division offers CERN users a wide variety of services. Its full range of activities is presented in a new brochure. In addition to its many physicists and engineers, CERN also has teams of mechanics, welders and sheet-metalworkers whose expertise is a precious asset for the Organization. Within the MF Group (Manufacturing Facilities, EST Division) these teams perform precision machining, sheet-metal work and welding. As an example, the Group has been responsible for producing radiofrequency accelerating cells to a precision of the order of 1/100th mm and with a surface roughness of only 0.1 micron. The Group's workshops also manufactured the stainless steel vacuum chamber for the brand new n-TOF experiment (Bulletin n°47/2000), a 200-m long cylindrical chamber with a diameter of just 800 millimetres! The MF Group is assisted in its task of providing me...

Stress analysis and deformation prediction of sheet metal workpieces based on finite element simulation

Directory of Open Access Journals (Sweden)

Ren Penghao

2017-01-01

Full Text Available After aluminum alloy sheet metal parts machining, the residual stress release will cause a large deformation. To solve this problem, this paper takes a aluminum alloy sheet aerospace workpiece as an example, establishes the theoretical model of elastic deformation and the finite element model, and places quantitative initial stress in each element of machining area, analyses stress release simulation and deformation. Through different initial stress release simulative analysis of deformation of the workpiece, a linear relationship between initial stress and deformation is found; Through simulative analysis of coupling direction-stress release, the superposing relationship between the deformation caused by coupling direction-stress and the deformation caused by single direction stress is found. The research results provide important theoretical support for the stress threshold setting and deformation controlling of the workpieces in the production practice.

Testing and Prediction of Limits of Lubrication in Sheet Metal Forming

DEFF Research Database (Denmark)

Ceron, Ermanno; Bay, Niels

2012-01-01

Increasing focus on environmental issues in industrial production has urged a number of sheet metal forming companies to look for new tribo-systems, here meaning the combination of tool_material/workpiece_material/lubricant, in order to substitute hazardous lubricants such as chlorinated paraffin...... laboratory and production tests as well as numerical analyses in order to evaluate and compare performance of the new tribo-systems. A part is selected from industrial production and analyzed by this methodology in order to substitute the existing tribo-system with a new one....... oils. Testing of new tribo-systems under production conditions is, however, very costly. For preliminary testing it is more feasible to introduce laboratory tests. In this paper a new methodology for testing new tribo-systems is presented. The methodology describes a series of investigations combining...

Analysis of acoustic emission during abrasive waterjet machining of sheet metals

Science.gov (United States)

Mokhtar, Nazrin; Gebremariam, MA; Zohari, H.; Azhari, Azmir

2018-04-01

The present paper reports on the analysis of acoustic emission (AE) produced during abrasive waterjet (AWJ) machining process. This paper focuses on the relationship of AE and surface quality of sheet metals. The changes in acoustic emission signals recorded by the mean of power spectral density (PSD) via covariance method in relation to the surface quality of the cut are discussed. The test was made using two materials for comparison namely aluminium 6061 and stainless steel 304 with five different feed rates. The acoustic emission data were captured by Labview and later processed using MATLAB software. The results show that the AE spectrums correlated with different feed rates and surface qualities. It can be concluded that the AE is capable of monitoring the changes of feed rate and surface quality.

Flexible Engineering Structures from the Corrugated Metal Sheets - Comparison of Costs of Solutions used in the Road Building

Science.gov (United States)

Ołdakowska, E.

2017-11-01

The flexible structures from the corrugated metal sheets are used in particular in the road building, especially as passages for animals. Easy and quick assembly, as well as lower realization costs when compared to the traditional solutions increase interest in such structures. Availability and variety of systems allows for searching for solutions which are the best and optimal in the economical range. The article presents the comparison of costs of the basic materials used in various systems of flexible structures from the corrugated metal sheets. In order to determine the costs of the material solutions the data for two systems used in Poland (for construction of the upper passages for animals) since 2008 have been used. The cost estimation for the basic materials required for realization of 1 m2 of the flexible structure from the corrugated steel sheets have been prepared with use of prices obtained directly from the Polish contractors and manufacturers, as well as process included in the quarterly information (Sekocenbud). The difference of prices of materials available on the market allows the investor for selecting the structure depending on the needs and financial possibilities, as well as for achieving some savings. The savings in case of purchasing sheets of identical parameters (thickness, profile characteristics) are from approx. 4% to 8% per 1 m2 of sheet. The connectors in form of bolts M20 cl. 8.8 of various lengths are an expense from 3.00 PLN to 3.50 PLN. Those values may seem low, but taking into consideration amounts connected with construction of many square meters of structure they may become very important factor in the total investment costs.

Numerical investigation of blanking for metal polymer sandwich sheets

Directory of Open Access Journals (Sweden)

Gutknecht Florian

2016-01-01

Full Text Available Metal polymer sandwich sheets consist of materials with drastically different mechanical properties. Due to this fact and because of high local gradients in the cutting zone during the blanking process, traditional process strategies and empirical knowledge are difficult to apply. A finite-element simulation of the shear cutting process is used to predict the necessary force and the geometry of the cutting surface. A fully-coupled ductile damage model is used for the description of the material behaviour. This model considers the influence of shear and compression-dominated stress states on the initiation of damage. Experimental tensile and compression test data is used for the identification of material parameters. The results of the blanking simulation are compared with experimental data. Furthermore, the evolution of the stress state is analysed to gain understanding of the underlying physics. Finally this model enables the prediction of core compression and other quantities such as the acting stresses and corresponding triaxilities, which provide valuable information for the development of analytical models.

Experimental evaluation of coating delamination in vinyl coated metal forming

International Nuclear Information System (INIS)

Son, Young Ki; Lee, Chan Joo; Kim, Byung Min; Lee, Jung Min; Byoen, Sang Doek; Lee, Soen Bong

2012-01-01

In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications

Experimental evaluation of coating delamination in vinyl coated metal forming

Energy Technology Data Exchange (ETDEWEB)

Son, Young Ki; Lee, Chan Joo; Kim, Byung Min [Pusan National Univ., Busan (Korea, Republic of); Lee, Jung Min [Korea Institute of Industrial Technology, Busan (Korea, Republic of); Byoen, Sang Doek [HA Digital Engineering Gr., Seongsan Gu (Korea, Republic of); Lee, Soen Bong [Keimyung Univ., Daegu (Korea, Republic of)

2012-10-15

In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications.

Hand Book of Metal Material Contrast

International Nuclear Information System (INIS)

Park, Yeong Hui

1989-06-01

This book first gives descriptions of using of this hand book and contents. It tells of steel such as bar steel, section steel, and steel sheet which are steel for general structure and steel for pressure vessel, a steel pipe, carbon steel for machine structure and alloy steel, steel for special things, stainless steel, heat resisting steel, tool steel, spring steel, forging, steel casting, nonferrous metal such as aluminium and aluminium alloy, casting, list of similar steel per metal, list of steel like ASTM, AISI per number, and list of collecting standard per metal material.

Modeling of optimization strategies in the incremental CNC sheet metal forming process

International Nuclear Information System (INIS)

Bambach, M.; Hirt, G.; Ames, J.

2004-01-01

Incremental CNC sheet forming (ISF) is a relatively new sheet metal forming process for small batch production and prototyping. In ISF, a blank is shaped by the CNC movements of a simple tool in combination with a simplified die. The standard forming strategies in ISF entail two major drawbacks: (i) the inherent forming kinematics set limits on the maximum wall angle that can be formed with ISF. (ii) since elastic parts of the imposed deformation can currently not be accounted for in CNC code generation, the standard strategies can lead to undesired deviations between the target and the sample geometry.Several enhancements have recently been put forward to overcome the above limitations, among them a multistage forming strategy to manufacture steep flanges, and a correction algorithm to improve the geometric accuracy. Both strategies have been successful in improving the forming of simple parts. However, the high experimental effort to empirically optimize the tool paths motivates the use of process modeling techniques.This paper deals with finite element modeling of the ISF process. In particular, the outcome of different multistage strategies is modeled and compared to collated experimental results regarding aspects such as sheet thickness and the onset of wrinkling. Moreover, the feasibility of modeling the geometry of a part is investigated as this is of major importance with respect to optimizing the geometric accuracy. Experimental validation is achieved by optical deformation measurement that gives the local displacements and strains of the sheet during forming as benchmark quantities for the simulation

Practical Aspects of CALS in Design and Manufacturing of Sheet Metal Products

DEFF Research Database (Denmark)

Shpitalni, Moshe; Alting, Leo; Bilberg, Arne

1998-01-01

The transition from design to process planning and to the various stages of manufacturing is traditionally sequential. In many cases, practical problems associated with manufacturing cannot be resolved if only individual processes are examined. These problems can be overcome, however, by adopting...... with the design and manufacture of sheet metal parts. It is demonstrated that through implementation of the CALS approach, the overall process can be optimised and products can be manufactured significantly more accurately, faster and less expensively.......The transition from design to process planning and to the various stages of manufacturing is traditionally sequential. In many cases, practical problems associated with manufacturing cannot be resolved if only individual processes are examined. These problems can be overcome, however, by adopting...

Parametric analysis of plastic strain and force distribution in single pass metal spinning

International Nuclear Information System (INIS)

Choudhary, Shashank; Tejesh, Chiruvolu Mohan; Regalla, Srinivasa Prakash; Suresh, Kurra

2013-01-01

Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India

Parametric analysis of plastic strain and force distribution in single pass metal spinning

Science.gov (United States)

Choudhary, Shashank; Tejesh, Chiruvolu Mohan; Regalla, Srinivasa Prakash; Suresh, Kurra

2013-12-01

Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India.

Parametric analysis of plastic strain and force distribution in single pass metal spinning

Energy Technology Data Exchange (ETDEWEB)

Choudhary, Shashank, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Tejesh, Chiruvolu Mohan, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Regalla, Srinivasa Prakash, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Suresh, Kurra, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in [Department of Mechanical Engineering, BITS-Pilani, Hyderabad Campus, Shamirpet, Hyderabad, 500078, Andhra Pradesh (India)

2013-12-16

Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India.

In-situ stress analysis with X-Ray diffraction for yield locus characterization of sheet metals

Energy Technology Data Exchange (ETDEWEB)

Güner, A.; Tekkaya, A. E. [Institute of Forming Technology and Lightweight Construction, TU Dortmund University, Baroper Str. 301, 44227 Dortmund (Germany); Zillmann, B.; Lampke, T. [Institute of Materials Science and Engineering, Chemnitz University of Technology, Erfenschlager Strasse 73 D-09125 Chemnitz (Germany)

2013-12-16

A main problem in the field of sheet metal characterization is the inhomogeneous plastic deformation in the gauge regions of specimens which causes the analytically calculated stresses to differ from the sought state of stress acting in the middle of the gauge region. To overcome this problem, application of X-Ray diffraction is analyzed. For that purpose a mobile X-ray diffractometer and an optical strain measurement system are mounted on a universal tensile testing machine. This enables the recording of the whole strain and stress history of a material point. The method is applied to uniaxial tension tests, plane strain tension tests and shear tests to characterize the interstitial free steel alloy DC06. The applicability of the concepts of stress factors is verified by uniaxial tension tests. The experimentally obtained values are compared with the theoretical values calculated with crystal elasticity models utilizing the orientation distribution functions (ODF). The relaxation problem is addressed which shows itself as drops in the stress values with the strain kept at a constant level. This drop is analyzed with elasto-viscoplastic material models to correct the measured stresses. Results show that the XRD is applicable to measure the stresses in sheet metals with preferred orientation. The obtained yield locus is expressed with the Yld2000–2D material model and an industry oriented workpiece is analyzed numerically. The comparison of the strain distribution on the workpiece verifies the identified material parameters.

Facile conversion of bulk metal surface to metal oxide single-crystalline nanostructures by microwave irradiation: Formation of pure or Cr-doped hematite nanostructure arrays

International Nuclear Information System (INIS)

Cho, Seungho; Jeong, Haeyoon; Lee, Kun-Hong

2010-01-01

We report a method for converting the surfaces of bulk metal substrates (pure iron or stainless steel) to metal oxide (hematite or Cr-doped hematite) nanostructures using microwave irradiation. When microwave radiation (2.45 GHz, single-mode) was applied to a metal substrate under the flow of a gas mixture containing O 2 and Ar, metal oxide nanostructures formed and entirely covered the substrate. The nanostructures were single crystalline, and the atomic ratios of the substrate metals were preserved in the nanostructures. When a pure iron sheet was used as a substrate, hematite nanowires (1000 W microwave radiation) or nanosheets (1800 W microwave radiation) formed on the surface of the substrate. When a SUS410 sheet was used as a substrate, slightly curved rod-like nanostructures were synthesized. The oxidation states of Fe and Cr in these nanorods were Fe 3+ and Cr 3+ . Quantitative analyses revealed an average Fe/Cr atomic ratio of 9.2, nearly identical to the ratio of the metals in the SUS410 substrate.

Radial-rotation profile forming: A new processing technology of incremental sheet metal forming

Science.gov (United States)

Laue, Robert; Härtel, Sebastian; Awiszus, Birgit

2018-05-01

Incremental forming processes (i.e., spinning) of sheet metal blanks into cylindrical cups are suitable for lower lot sizes. The produced cups were frequently used as preforms to produce workpieces in further forming steps with additional functions like profiled hollow parts [1]. The incremental forming process radial-rotation profile forming has been developed to enable the production of profiled hollow parts with low sheet thinning and good geometrical accuracy. The two principal forming steps are the production of the preform by rotational swing-folding [2] and the subsequent radial profiling of the hollow part in one clamping position. The rotational swing-folding process is based on a combination of conventional spinning and swing-folding. Therefore, a round blank rotates on a profiled mandrel and due to the swinging of a cylindrical forming tool, the blank is formed to a cup with low sheet thinning. In addition, thickening results at the edge of the blank and wrinkling occurs. However, the wrinkles are formed into the indentation of the profiled mandrel and can be reshaped as an advantage in the second process step, the radial profiling. Due to the rotation and continuous radial feed of a profiled forming tool to the profiled mandrel, the axial profile is formed in the second process step. Because of the minor relative movement in axial direction between tool and blank, low sheet thinning occurs. This is an advantage of the principle of the process.

Studies on the finite element simulation in sheet metal stamping processes

Science.gov (United States)

Huang, Ying

The sheet metal stamping process plays an important role in modern industry. With the ever-increasing demand for shape complexity, product quality and new materials, the traditional trial and error method for setting up a sheet metal stamping process is no longer efficient. As a result, the Finite Element Modeling (FEM) method has now been widely used. From a physical point of view, the formability and the quality of a product are influenced by several factors. The design of the product in the initial stage and the motion of the press during the production stage are two of these crucial factors. This thesis focuses on the numerical simulation for these two factors using FEM. Currently, there are a number of commercial FEM software systems available in the market. These software systems are based on an incremental FEM process that models the sheet metal stamping process in small incremental steps. Even though the incremental FEM is accurate, it is not suitable for the initial conceptual design for its needing of detailed design parameters and enormous calculation times. As a result, another type of FEM, called the inverse FEM method or one-step FEM method, has been proposed. While it is less accurate than that of the incremental method, this method requires much less computation and hence, has a great potential. However, it also faces a number of unsolved problems, which limits its application. This motivates the presented research. After the review of the basic theory of the inverse method, a new modified arc-length search method is proposed to find better initial solution. The methods to deal with the vertical walls are also discussed and presented. Then, a generalized multi-step inverse FEM method is proposed. It solves two key obstacles: the first one is to determine the initial solution of the intermediate three-dimensional configurations and the other is to control the movement of nodes so they could only slide on constraint surfaces during the search by

Sidewall containment of liquid metal with horizontal alternating magnetic fields

Science.gov (United States)

Pareg, Walter F.

1990-01-01

An apparatus for confining molten metal with a horizontal alternating magnetic field. In particular, this invention employs a magnet that can produce a horizontal alternating magnetic field to confine a molten metal at the edges of parallel horizontal rollers as a solid metal sheet is cast by counter-rotation of the rollers.

Synergistic Effect between Metal-Nitrogen-Carbon Sheets and NiO Nanoparticles for Enhanced Electrochemical Water-Oxidation Performance.

Science.gov (United States)

Wang, Jun; Li, Kai; Zhong, Hai-xia; Xu, Dan; Wang, Zhong-li; Jiang, Zheng; Wu, Zhi-jian; Zhang, Xin-bo

2015-09-01

Identifying effective means to improve the electrochemical performance of oxygen-evolution catalysts represents a significant challenge in several emerging renewable energy technologies. Herein, we consider metal-nitrogen-carbon sheets which are commonly used for catalyzing the oxygen-reduction reaction (ORR), as the support to load NiO nanoparticles for the oxygen-evolution reaction (OER). FeNC sheets, as the advanced supports, synergistically promote the NiO nanocatalysts to exhibit superior performance in alkaline media, which is confirmed by experimental observations and density functional theory (DFT) calculations. Our findings show the advantages in considering the support effect for designing highly active, durable, and cost-effective OER electrocatalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A numerical simulation of thermodynamic processes for cryogenic metal forming of aluminum sheets and comparison with experimental results

International Nuclear Information System (INIS)

Reichl, Ch.; Schneider, R.; Hohenauer, W.; Grabner, F.; Grant, R.J.

2017-01-01

Highlights: • Thermodynamic processes for cryogenic sheet metal forming tools were examined. • Static and transient temperature field simulations are evaluated on a Nakajima tool. • Differently arranged cooling loops lead to homogeneous temperature distribution. • Scaling of the geometry leads to significantly increased heat transfer times. • The temperature management of complex forming tools can be developed numerically. - Abstract: Forming at cryogenic temperatures provides a significant improvement in formability of aluminum sheets. This offers the potential for light, complex and highly integrated one-piece components to be produced out of aluminum alloys at sub-zero temperatures. This would allow weight reduction, environmental conservation and cost reduction of a car body to give one example in the automotive industry. For temperature supported processes special forming tools and cooling strategies are required to be able to reach and maintain process stability. Time dependent numerical simulations of the thermodynamic processes of cryogenic sheet metal forming covering all aspects of heat transfer through conduction, convection and radiation play a vital role in the design and development of future tools and are presented for several geometries. Cooling (and heating) strategies (including selection of the number of cooling loops and their relative positioning) in a Nakajima testing tool were evaluated using computational fluid dynamics. These simulations were performed with static and transient solvers to demonstrate the extraction of tool surface temperature distributions on different forming tool geometries. Comparisons of predicted temperature characteristics of an aluminum sheet and experimentally determined temperature distributions were made. The temperature distribution of the surface of an aluminum sheet could be predicted with high accuracy. Further, the influence of the tool size on the parameters temperature transfer times and

Production of an Amorphous Fe_<75>Si_<10>B_<15> Sheet by a Metallic Mold Casting Method and its Properties

OpenAIRE

Inoue, Akihisa; Yamamoto, Hirokazu; Saito, Takanobu; Masumoto, Tsuyosi

1993-01-01

The application of a metallic mold casting method to an Fe_Si_B_ alloy with the largest glass-forming ability in (Fe, Co, Ni)-Si-B system was found to cause the formation of a mostly single amorphous phase in a sheet form with a thickness of 0.1 mm. No distinct difference in thermal stability (crystallization temperature and heat of crystallization), hardness, Curie temperature and magnetization is detected between the as-cast sheet and the melt-spun amorphous ribbon with a thickness of 0.02 ...

Mechanical properties of sheet metal components with local reinforcement produced by additive manufacturing

Science.gov (United States)

Ünsal, Ismail; Hama-Saleh, R.; Sviridov, Alexander; Bambach, Markus; Weisheit, A.; Schleifenbaum, J. H.

2018-05-01

New technological challenges like electro-mobility pose an increasing demand for cost-efficient processes for the production of product variants. This demand opens the possibility to combine established die-based manufacturing methods and innovative, dieless technologies like additive manufacturing [1, 2]. In this context, additive manufacturing technologies allow for the weight-efficient local reinforcement of parts before and after forming, enabling manufacturers to produce product variants from series parts [3]. Previous work by the authors shows that the optimal shape of the reinforcing structure can be determined using sizing optimization. Sheet metal parts can then be reinforced using laser metal deposition. The material used is a pearlite-reduced, micro-alloyed steel (ZE 630). The aim of this paper is to determine the effect of the additive manufacturing process on the material behavior and the mechanical properties of the base material and the resulting composite material. The parameters of the AM process are optimized to reach similar material properties in the base material and the build-up volume. A metallographic analysis of the parts is presented, where the additive layers, the base material and also the bonding between the additive layers and the base material are analyzed. The paper shows the feasibility of the approach and details the resulting mechanical properties and performance.

Ball lightning from atmospheric discharges via metal nanosphere oxidation: from soils, wood or metals.

Science.gov (United States)

Abrahamson, John

2002-01-15

The slow (diffusion-limited) oxidation of metal nanoparticles has previously been proposed as the mechanism for ball lightning energy release, and argued to be the result of a normal lightning strike on soil. Here this basic model of networked nanoparticles is detailed further, and extended to lightning strikes on metal structures, and also to the action of other storm-related discharges or man-made discharges. The basic model predicted the important properties of "average" observed ball lightning, and the extension in this paper also covers high-energy examples of ball lightning. Laboratory checks of the theory are described, and predictions given of what conditions are necessary for observing ball lightning in the laboratory. Key requirements of the model are a sheltered region near the strike foot and starting materials which can generate a metal vapour under intensive heating, including soil, wood or a metal structure. The evolution of hydrocarbons (often plastics) along with metal vapour can ensure the local survival of the metal vapour even in an oxidizing atmosphere. Subsequent condensation of this vapour to metallic nanoparticles in networks provides the coherence of a ball structure, which also releases light over an extended time. Also discussed is the passage of ball lightning through a sheet of building material, including glass, and its occasional charring of flesh on close contact.

Flexible high-κ/Metal gate metal/insulator/metal capacitors on silicon (100) fabric

KAUST Repository

Rojas, Jhonathan Prieto

2013-10-01

Implementation of memory on bendable substrates is an important step toward a complete and fully developed notion of mechanically flexible computational systems. In this paper, we have demonstrated a simple fabrication flow to build metal-insulator-metal capacitors, key components of dynamic random access memory, on a mechanically flexible silicon (100) fabric. We rely on standard microfabrication processes to release a thin sheet of bendable silicon (area: 18 {\\ m cm}2 and thickness: 25 \\\\mu{\\ m m}) in an inexpensive and reliable way. On such platform, we fabricated and characterized the devices showing mechanical robustness (minimum bending radius of 10 mm at an applied strain of 83.33% and nominal strain of 0.125%) and consistent electrical behavior regardless of the applied mechanical stress. Furthermore, and for the first time, we performed a reliability study suggesting no significant difference in performance and showing an improvement in lifetime projections. © 1963-2012 IEEE.

Towards Industrial Application of Damage Models for Sheet Metal Forming

Science.gov (United States)

Doig, M.; Roll, K.

2011-05-01

Due to global warming and financial situation the demand to reduce the CO2-emission and the production costs leads to the permanent development of new materials. In the automotive industry the occupant safety is an additional condition. Bringing these arguments together the preferable approach for lightweight design of car components, especially for body-in-white, is the use of modern steels. Such steel grades, also called advanced high strength steels (AHSS), exhibit a high strength as well as a high formability. Not only their material behavior but also the damage behavior of AHSS is different compared to the performances of standard steels. Conventional methods for the damage prediction in the industry like the forming limit curve (FLC) are not reliable for AHSS. Physically based damage models are often used in crash and bulk forming simulations. The still open question is the industrial application of these models for sheet metal forming. This paper evaluates the Gurson-Tvergaard-Needleman (GTN) model and the model of Lemaitre within commercial codes with a goal of industrial application.

kW-class direct diode laser for sheet metal cutting based on commercial pump modules

Science.gov (United States)

Witte, U.; Schneider, F.; Holly, C.; Di Meo, A.; Rubel, D.; Boergmann, F.; Traub, M.; Hoffmann, D.; Drovs, S.; Brand, T.; Unger, A.

2017-02-01

We present a direct diode laser with an optical output power of more than 800 W ex 100 μm with an NA of 0.17. The system is based on 6 commercial pump modules that are wavelength stabilized by use of VBGs. Dielectric filters are used for coarse and dense wavelength multiplexing. Metal sheet cutting tests were performed in order to prove system performance and reliability. Based on a detailed analysis of loss mechanisms, we show that the design can be easily scaled to output powers in the range of 2 kW and to an optical efficiency of 80%.

Incremental electrohydraulic forming - A new approach for the manufacture of structured multifunctional sheet metal blanks

Science.gov (United States)

Djakow, Eugen; Springer, Robert; Homberg, Werner; Piper, Mark; Tran, Julian; Zibart, Alexander; Kenig, Eugeny

2017-10-01

Electrohydraulic Forming (EHF) processes permit the production of complex, sharp-edged geometries even when high-strength materials are used. Unfortunately, the forming zone is often limited as compared to other sheet metal forming processes. The use of a special industrial-robot-based tool setup and an incremental process strategy could provide a promising solution for this problem. This paper describes such an innovative approach using an electrohydraulic incremental forming machine, which can be employed to manufacture the large multifunctional and complex part geometries in steel, aluminium, magnesium and reinforced plastic that are employed in lightweight constructions or heating elements.

PREPARATION OF CONSTRUCTION PRODUCTION OF METAL SHEET FOR MEANS OF TRANSPORT

Directory of Open Access Journals (Sweden)

Piotr Penkała

2013-03-01

Full Text Available The design of sheet metal parts, pressed, used in the automotive industry is very complicated. Many factors influence the final shape of the part. Contemporary designer does not need to have the knowledge needed to understand the essence of its all requirements that are placed on parts of the body. It is only important that they are aware of their existence and know who in the company can help them in their fulfilment of the construction. Nowadays, only the constructor creates a CAD model geometry, which is assumed to provide the functionality. The rest of the aspects such as the provision of adequate stiffness, manufacturability, assembly features, vibration analysis, etc., are the arena of other specialists. This is the essence of constructing simultaneous, where many cell companies often work on the same element, giving it a set of features impossible to obtain by one expert on everything. Therefore, the role of the designer is often limited to being only a CAD system operator.

Finishes for Metals. Paintability of Galvanized Steel, Corrosion Resistance of Metallized Coatings.

Science.gov (United States)

Building Research Inst., Inc., Washington, DC.

Two papers are presented. The first, "Report of the AISI Research Project on the Paintability of Galvanized Steel," was a project aimed at determining optimum procedures for painting bright-spangled galvanized sheet steel products using three classes of trade sales paints--metallic zinc-dust, portland cement-in-oil, and water base emulsion paints.…

Die design optimization on sheet metal forming with considering the phenomenon of springback to improve product quality

Directory of Open Access Journals (Sweden)

Darmawan Agung Setyo

2018-01-01

Full Text Available The process of sheet metal forming is one of the very important processes in manufacture of products mainly in the automotive field. In sheet metal forming, it is added a certain size at the die to tolerate a result of the elasticity restoration of material. Therefore, when the product is removed from the die then the process elastic recovery will end within the allowable tolerance size. Extra size of the die is one method to compensate for springback. The aim of this research is to optimize the die by entering a springback value in die design to improve product quality that is associated with accuracy the final size of the product. Simulation processes using AutoForm software are conducted to determine the optimal parameters to be used in the forming process. Variations the Blank Holder Force of 77 N, 97 N, and 117 N are applied to the plate material. The Blank Holder Force application higher than 97 N cannot be conducted because the Forming Limit Diagram indicates the risk of tearing. Then the Blank Holder Force of 37 N, 57 N and 77 N are selected and applied in cup drawing process. Even though a few of wrinkling are appear, however there is no significant deviation of dimension between the product and the design of cup.

Formation of metal clusters in halloysite clay nanotubes

Science.gov (United States)

Vinokurov, Vladimir A.; Stavitskaya, Anna V.; Chudakov, Yaroslav A.; Ivanov, Evgenii V.; Shrestha, Lok Kumar; Ariga, Katsuhiko; Darrat, Yusuf A.; Lvov, Yuri M.

2017-12-01

We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of c.50 nm, a lumen of 15 nm and length 1 μm. This allowed for synthesis of metal nanoparticles at the selected position: (1) on the outer surface seeding 3-5 nm metal particles on the tubes; (2) inside the tube's central lumen resulting in 10-12 nm diameter metal cores shelled with ceramic wall; and (3) smaller metal nanoparticles intercalated in the tube's wall allowing up to 9 wt% of Ru, and Ag loading. These composite materials have high surface area providing a good support for catalytic nanoparticles, and can also be used for sorption of metal ions from aqueous solutions.

Assessment of the vibration on the foam legged and sheet metal-legged passenger seat

Directory of Open Access Journals (Sweden)

L. Dahil

2015-10-01

Full Text Available In this study, it was aim ed to decrease the vibration reaching to passenger from the legs of vehicle seats. In order to determine the levels of vibrations reaching at passengers, a test pad placed under the passenger seat was used, and HVM100 device was used for digitizing the information obtained. By transferring the vibration data to system by using HVM100 device, the acceleration graphics were prepared with Blaze software. As a result, it was determined that the acceleration values of seat legs made of foam material were lower than that of seat legs made of 2 mm thick sheet metal, so they damped the vibration better.

Identification of a process window for tailored carburization of sheet metals in hot stamping

Science.gov (United States)

Horn, Alexander; Merklein, Marion

2018-05-01

Due to governmental regulations concerning the reduction of CO2 emissions and increasing safety standards, hot stamping of high strength boron manganese steel sheets has evolved into a state of the art process for manufacturing structural car body parts. The combined forming and in-die quenching process enables the formation of a fully martensitic microstructure. Therefore, press hardened steels offer high strength, but low ductility. In order to further improve passenger safety, a tailored configuration of mechanical properties is desired. Besides state of the art methods, like the application of locally different heat treatment temperatures or varying quenching rates, the adjustment of mechanical properties of sheet metals by a tailored carburization is a novel approach. For the carburization process, the specimens are first coated with graphite and subsequently heat treated. Within this contribution, different coating strategies as well as heat treatment temperatures and dwell times are investigated. For the determination of a process window, mechanical properties such as tensile strength and microhardness will be analyzed and correlated with the resulting microstructure.

A Fundamental Study of Stretch-Drawing Process of Sheet Metals : Single and Double Operations

Science.gov (United States)

Gotoh, Manabu; Kim, Young-soo; Yamashita, Minoru

1998-05-01

Fundamental and informative data of axisymmetric stretch-drawing of several sheet metals with thichness of 0.7 1.0 mm are presented especially for single and double operations. Very small radius is applied to the die-profile (or -shoulder) in all operations to induce wall-thinning by the effect of bending-under-tension, from which the name `stretch-drawing' comes. It is clearly demonstrated that deeper cups could be formed by the single and double stretch-drawings from smaller cirlcular blanks due to such wall-thinning action than in the usual deep-drawing of larger blanks. From this fact, it is emphasized that the deep-drawability of a sheet metal is not evaluated simply by the conventional LDR (=limiting drawing ratio), but the depth of the drawn cup should also be taken into account. Many experimental data about various metals and thicknesses given in this paper offer a valueable information on this process for more general use which recommends to replace the conventional deep-drawing process by the stretch-drawing process both for single and double operations. In the single stretch-drawing, it is also confirmed that a deeper cup can be produced by raising the blank-holding force at later stage of operation. Fracturing is found to occur at the middle section of the wall part or at the die-profile other than at the punch profile common in the usual deep-drawing process. Numerical simulation of the single stretch-drawing process is also performed by use of DYNA-3D code to confirm that a satisfactory prediction especially in the depth of the drawn-cup can be done at least in a practical sense, although this kind of numerical analysis is very difficult because of the severity or localization of deformation around the die profile. The drawn cup of SUS304 among others fractures in a couple of weeks after the operation due to the residual circumferential tensile stress, whereas that of SUS304L does not. In the double stretch-drawing, it is confirmed that very deeper

Transparent electrode designs based on optimal nano-patterning of metallic films

KAUST Repository

Catrysse, Peter B.

2010-09-10

Transparent conductive electrodes are critical to the operation of optoelectronic devices, such as photovoltaic cells and light emitting diodes. Effective electrodes need to combine excellent electrical and optical properties. Metal oxides, such as indium tin oxide, are commonly used. There is substantial interest in replacing them, however, motivated by practical problems and recent discoveries regarding the optics of nano-patterned metals. When designing nano-patterned metallic films for use as electrodes, one needs to account for both optical and electrical properties. In general, it is insufficient to optimize nano-structured films based upon optical properties alone, since structural variations will also affect the electrical properties. In this work, we investigate the need for simultaneous optical and electrical performance by analyzing the optical properties of a class of nano-patterned metallic electrodes that is obtained by a constant-sheet-resistance transformation. Within such a class the electrical and optical properties can be separated, i.e., the sheet resistance can be kept constant and the transmittance can be optimized independently. For simple one-dimensional periodic patterns with constant sheet-resistance, we find a transmission maximum (polarization-averaged) when the metal sections are narrow (< 40 nm, ~ 10% metal fill-factor) and tall (> 100 nm). Our design carries over to more complex two-dimensional (2D) patterns. This is significant as there are no previous reports regarding numerical studies on the optical and electrical properties of 2D nano-patterns in the context of electrode design.

Metallated metal-organic frameworks

Energy Technology Data Exchange (ETDEWEB)

Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

2017-08-22

Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

Microstructural study of metal-metal composites elaborated by interdiffusion between pure nickel and devitrified Fe-Ni-Mo-B glasses

International Nuclear Information System (INIS)

Ratovondrahona, E.; Bouquet, G.; Portier, R.

1993-01-01

It is well known that amorphous metallic alloys are able to give rise to microcrystallized structures when submitted to the effect of temperature, i.e. when devitrification takes place. These microstructures are particularly interesting for various applications. Materials produced from devitrified amorphous phase generally exhibit good mechanical properties, but are accompanied by some brittleness. In order to avoid this disadvantage, the authors tried to elaborate a composite material resulting from diffusion heat treatments carried out on alternate stackings of amorphous alloys and pure metal sheets. The idea is that by choosing discerning metallic glass and an appropriate diffusion heat treatment temperature, it might be possible to obtain mechanically hard phases, such as metallic borides, and disperse these compounds in the pure metallic matrix to be reinforced. Here, the authors only present the microstructural results of this study, although some preliminary mechanical tests have been preformed

High-performance metal mesh/graphene hybrid films using prime-location and metal-doped graphene.

Science.gov (United States)

Min, Jung-Hong; Jeong, Woo-Lim; Kwak, Hoe-Min; Lee, Dong-Seon

2017-08-31

We introduce high-performance metal mesh/graphene hybrid transparent conductive layers (TCLs) using prime-location and metal-doped graphene in near-ultraviolet light-emitting diodes (NUV LEDs). Despite the transparency and sheet resistance values being similar for hybrid TCLs, there were huge differences in the NUV LEDs' electrical and optical properties depending on the location of the graphene layer. We achieved better physical stability and current spreading when the graphene layer was located beneath the metal mesh, in direct contact with the p-GaN layer. We further improved the contact properties by adding a very thin Au mesh between the thick Ag mesh and the graphene layer to produce a dual-layered metal mesh. The Au mesh effectively doped the graphene layer to create a p-type electrode. Using Raman spectra, work function variations, and the transfer length method (TLM), we verified the effect of doping the graphene layer after depositing a very thin metal layer on the graphene layers. From our results, we suggest that the nature of the contact is an important criterion for improving the electrical and optical performance of hybrid TCLs, and the method of doping graphene layers provides new opportunities for solving contact issues in other semiconductor devices.

Advanced Gradient Based Optimization Techniques Applied on Sheet Metal Forming

International Nuclear Information System (INIS)

Endelt, Benny; Nielsen, Karl Brian

2005-01-01

The computational-costs for finite element simulations of general sheet metal forming processes are considerable, especially measured in time. In combination with optimization, the performance of the optimization algorithm is crucial for the overall performance of the system, i.e. the optimization algorithm should gain as much information about the system in each iteration as possible. Least-square formulation of the object function is widely applied for solution of inverse problems, due to the superior performance of this formulation.In this work focus will be on small problems which are defined as problems with less than 1000 design parameters; as the majority of real life optimization and inverse problems, represented in literature, can be characterized as small problems, typically with less than 20 design parameters.We will show that the least square formulation is well suited for two classes of inverse problems; identification of constitutive parameters and process optimization.The scalability and robustness of the approach are illustrated through a number of process optimizations and inverse material characterization problems; tube hydro forming, two step hydro forming, flexible aluminum tubes, inverse identification of material parameters

Impact Of Elastic Modulus Degradation On Springback In Sheet Metal Forming

International Nuclear Information System (INIS)

Halilovic, Miroslav; Stok, Boris; Vrh, Marko

2007-01-01

Strain recovery after removal of forming loads, commonly defined as springback, is of great concern in sheet metal forming, in particular with regard to proper prediction of the final shape of the part. To control the problem a lot of work has been done, either by minimizing the springback on the material side or by increasing the estimation precision in corresponding process simulations. Unfortunately, by currently available software springback still cannot be adequately predicted, because most analyses of springback are using linear, isotropic and constant Young's modulus and Poisson's ratio. But, as it was measured and reported, none of it is true. The aim of this work is to propose an upgraded mechanical model which takes evolution of damage and related orthotropic stiffness degradation into account. Damage is considered by inclusion of ellipsoidal cavities, and their influence on the stiffness degradation is taken in accordance with the Mori-Tanaka theory, adopting the GTN model for plastic flow. In order to improve the numerical springback prediction, two major things are important: first, the correct evaluation of the stress-strain state at the end of the forming process, and second, correctness of the elastic properties used in the elastic relaxation analysis. Since in modelling of the forming process we adopt a damage constitutive model with orthotropic stiffness degradation considered, a corresponding damage parameters identification upon specific experimental tests data must be performed first, independently of the metal forming modelling. An improved identification of material parameters, which simultaneously considers tensile test results with different type of specimens and using neural network, is proposed. With regard to the case in which damage in material is neglected it is shown in the article how the springback of a formed part differs, when we take orthotropic damage evolution into consideration

Increasing the Robustness of the Sheet Metal Forming Simulation by the Prediction of the Forming Limit Band

Science.gov (United States)

Banabic, D.; Vos, M.; Paraianu, L.; Jurco, P.

2007-05-01

The experimental research on the formability of metal sheets has shown that there is a significant dispersion of the limit strains in an area delimited by two curves: a lower curve (LFLC) and an upper one (UFLC). The region between the two curves defines the so-called Forming Limit Band (FLB). So far, this forming band has only been determined experimentally. In this paper the authors suggested a method to predict the Forming Limit Band. The proposed method is illustrated on the AA6111-T43 aluminium alloy.

Increasing the Robustness of the Sheet Metal Forming Simulation by the Prediction of the Forming Limit Band

International Nuclear Information System (INIS)

Banabic, D.; Paraianu, L.; Vos, M.; Jurco, P.

2007-01-01

The experimental research on the formability of metal sheets has shown that there is a significant dispersion of the limit strains in an area delimited by two curves: a lower curve (LFLC) and an upper one (UFLC). The region between the two curves defines the so-called Forming Limit Band (FLB). So far, this forming band has only been determined experimentally. In this paper the authors suggested a method to predict the Forming Limit Band. The proposed method is illustrated on the AA6111-T43 aluminium alloy

Methanogens predominate in natural corrosion protective layers on metal sheet piles.

NARCIS (Netherlands)

Kip, Nardy; Jansen, S.; Leite, M.F.A.; De Hollander, M.; Afanasyev, M.; Kuramae, E.E.; van Veen, J.A.

2017-01-01

Microorganisms are able to cause, but also to inhibit or protect against corrosion. Corrosion inhibition by microbial processes may be due to the formation of mineral deposition layers on metal objects. Such deposition layers have been found in archaeological studies on ancient metal objects, buried

Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

International Nuclear Information System (INIS)

Resta, V.; Quarta, G.; Farella, I.; Maruccio, L.; Cola, A.; Calcagnile, L.

2014-01-01

The implantation of 1 MeV metal ( 63 Cu + , 107 Ag + , 197 Au + ) and non-metal ( 4 He + , 12 C + ) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 10 13 ions cm −2 , the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated C=C bonds. For fluences around 1 × 10 17 ions cm −2 , the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C 0x clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C 0x cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼10 7 Ω/sq has been measured for implantation with metals at doses higher than 5 × 10 16 ions cm −2 , being 10 17 Ω/sq the corresponding sheet resistance for pristine PC

Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

Energy Technology Data Exchange (ETDEWEB)

Resta, V., E-mail: vincenzo.resta@le.infn.it [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy); Quarta, G. [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy); Farella, I. [Institute for Microelectronics and Microsystems – Unit of Lecce, National Council of Research (IMM/CNR), Lecce I-73100 (Italy); Maruccio, L. [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy); Cola, A. [Institute for Microelectronics and Microsystems – Unit of Lecce, National Council of Research (IMM/CNR), Lecce I-73100 (Italy); Calcagnile, L. [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy)

2014-07-15

The implantation of 1 MeV metal ({sup 63}Cu{sup +}, {sup 107}Ag{sup +}, {sup 197}Au{sup +}) and non-metal ({sup 4}He{sup +}, {sup 12}C{sup +}) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 10{sup 13} ions cm{sup −2}, the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated C=C bonds. For fluences around 1 × 10{sup 17} ions cm{sup −2}, the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C{sub 0x} clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C{sub 0x} cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼10{sup 7} Ω/sq has been measured for implantation with metals at doses higher than 5 × 10{sup 16} ions cm{sup −2}, being 10{sup 17} Ω/sq the corresponding sheet resistance for pristine PC.

Fast for sure: new developments in laser beam cutting of thin sheet metal; Mit Sicherheit schnell: neue Entwicklungen zum Laserstrahlschneiden von Fein- und Feinstblechen

Energy Technology Data Exchange (ETDEWEB)

Petring, D.; Schneider, F.; Thelen, C.; Poprawe, R.l [Fraunhofer-Institut fuer Lasertechnik (ILT), Aachen (Germany)

1999-04-01

Presently laser beam cutting is a rapidly developing technology. New laser sources with higher power and improved beam quality as well as the modern drive and control equipment together with advanced process developments allow a significant increase in cutting speed at excellent quality features. Recent results in laser beam slitting of sheet metal coils and in fast cutting of car body sheets illustrate this trend. It will be continued be even higher powers and new types of lasers. (orig.)

A Comparative Study of Natural Fiber and Glass Fiber Fabrics Properties with Metal or Oxide Coatings

International Nuclear Information System (INIS)

Lusis, Andrej; Pentjuss, Evalds; Bajars, Gunars; Sidorovicha, Uljana; Strazds, Guntis

2015-01-01

Rapidly growing global demand for technical textiles industries is stimulated to develop new materials based on hybrid materials (yarns, fabrics) made from natural and glass fibres. The influence of moisture on the electrical properties of metal and metal oxide coated bast (flax, hemp) fibre and glass fibre fabrics are studied by electrical impedance spectroscopy and thermogravimetry. The bast fibre and glass fiber fabrics are characterized with electrical sheet resistance. The method for description of electrical sheet resistance of the metal and metal oxide coated technical textile is discussed. The method can be used by designers to estimate the influence of moisture on technical data of new metal coated hybrid technical textile materials and products

Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

International Nuclear Information System (INIS)

Quinby, T.C.

1980-01-01

A method for preparing particulate metal or metal oxide of controlled partile size comprises contacting an an aqueous solution containing dissolved metal values with excess urea at a temperature sufficient to cause urea to react with water to provide a molten urea solution containing the metal values; heating the molten urea solution to cause the metal values to precipitate, forming a mixture containing precipitated metal values; heating the mixture containing precipitated metal values to evaporate volatile material leaving a dry powder containing said metal values. The dry powder can be calcined to provide particulate metal oxide or reduced to provide particulate metal. Oxide mixtures are provided when the aqueous solution contains values of more than one metal. Homogeneousmetal-metal oxide mistures for preparing cermets can be prepared by selectively reducing at least one of the metal oxides. (auth)

Canonical Schottky barrier heights of transition metal dichalcogenide monolayers in contact with a metal

Science.gov (United States)

Szcześniak, Dominik; Hoehn, Ross D.; Kais, Sabre

2018-05-01

The transition metal dichalcogenide (M X2 , where M =Mo , W and X =S , Se, Te) monolayers are of high interest for semiconducting applications at the nanoscale level; this interest is due to both their direct band gaps and high charge mobilities. In this regard, an in-depth understating of the related Schottky barrier heights, associated with the incorporation of M X2 sheets into novel low-dimensional metal-semiconductor junctions, is of crucial importance. Herein, we generate and provide analysis of the Schottky barrier heights behavior to account for the metal-induced gap states concept as its explanation. In particular, the present investigations concentrate on the estimation of the charge neutrality levels directly by employing the primary theoretical model, i.e., the cell-averaged Green's function formalism combined with the complex band structure technique. The results presented herein place charge neutrality levels in the vicinity of the midgap; this is in agreement with previous reports and analogous to the behavior of three-dimensional semiconductors. The calculated canonical Schottky barrier heights are also found to be in agreement with other computational and experimental values in cases where the difference between electronegativities of the semiconductor and metal contact is small. Moreover, the influence of the spin-orbit effects is herein considered and supports that Schottky barrier heights have metal-induced gap state-derived character, regardless whether spin-orbit coupling interactions are considered. The results presented within this report constitute a direct and vital verification of the importance of metal-induced gap states in explaining the behavior of observed Schottky barrier heights at M X2 -metal junctions.

Method of producing homogeneous mixed metal oxides and metal--metal oxide mixtures

International Nuclear Information System (INIS)

Quinby, T.C.

1978-01-01

Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution to leave a molten urea solution containing the metal values. The molten urea solution is heated to above about 180 0 C, whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles

Metal nanogrids, nanowires, and nanofibers for transparent electrodes

KAUST Repository

Hu, Liangbing; Wu, Hui; Cui, Yi

2011-01-01

Metals possess the highest conductivity among all room-temperature materials; however, ultrathin metal films demonstrate decent optical transparency but poor sheet conductance due to electron scattering from the surface and grain boundaries. This article discusses engineered metal nanostructures in the form of nanogrids, nanowires, or continuous nanofibers as efficient transparent and conductive electrodes. Metal nanogrids are discussed, as they represent an excellent platform for understanding the fundamental science. Progress toward low-cost, nano-ink-based printed silver nanowire electrodes, including silver nanowire synthesis, film fabrication, wire-wire junction resistance, optoelectronic properties, and stability, are also discussed. Another important factor for low-cost application is to use earth-abundant materials. Copper-based nanowires and nanofibers are discussed in this context. Examples of device integrations of these materials are also given. Such metal nanostructure-based transparent electrodes are particularly attractive for solar cell applications. © 2011 Materials Research Society.

Metal nanogrids, nanowires, and nanofibers for transparent electrodes

KAUST Repository

Hu, Liangbing

2011-10-01

Metals possess the highest conductivity among all room-temperature materials; however, ultrathin metal films demonstrate decent optical transparency but poor sheet conductance due to electron scattering from the surface and grain boundaries. This article discusses engineered metal nanostructures in the form of nanogrids, nanowires, or continuous nanofibers as efficient transparent and conductive electrodes. Metal nanogrids are discussed, as they represent an excellent platform for understanding the fundamental science. Progress toward low-cost, nano-ink-based printed silver nanowire electrodes, including silver nanowire synthesis, film fabrication, wire-wire junction resistance, optoelectronic properties, and stability, are also discussed. Another important factor for low-cost application is to use earth-abundant materials. Copper-based nanowires and nanofibers are discussed in this context. Examples of device integrations of these materials are also given. Such metal nanostructure-based transparent electrodes are particularly attractive for solar cell applications. © 2011 Materials Research Society.

48 CFR 252.225-7009 - Restriction on Acquisition of Certain Articles Containing Specialty Metals.

Science.gov (United States)

2010-10-01

... metal (by mass). (ii) If two metals are specified in the name (e.g., nickel-iron alloy), those metals..., billet, wire, slab, plate, or sheet, and in the grade appropriate for the production of— (i) A finished... of the following elements: Aluminum, chromium, cobalt, molybdenum, nickel, niobium (columbium...

Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes.

Science.gov (United States)

Zhou, Du; Yuan, Xi; Gao, Haoxiang; Wang, Ailing; Liu, Jun; El Fakir, Omer; Politis, Denis J; Wang, Liliang; Lin, Jianguo

2016-12-13

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques. This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

3D finite element modelling of sheet metal blanking process

Science.gov (United States)

Bohdal, Lukasz; Kukielka, Leon; Chodor, Jaroslaw; Kulakowska, Agnieszka; Patyk, Radoslaw; Kaldunski, Pawel

2018-05-01

The shearing process such as the blanking of sheet metals has been used often to prepare workpieces for subsequent forming operations. The use of FEM simulation is increasing for investigation and optimizing the blanking process. In the current literature a blanking FEM simulations for the limited capability and large computational cost of the three dimensional (3D) analysis has been largely limited to two dimensional (2D) plane axis-symmetry problems. However, a significant progress in modelling which takes into account the influence of real material (e.g. microstructure of the material), physical and technological conditions can be obtained by using 3D numerical analysis methods in this area. The objective of this paper is to present 3D finite element analysis of the ductile fracture, strain distribution and stress in blanking process with the assumption geometrical and physical nonlinearities. The physical, mathematical and computer model of the process are elaborated. Dynamic effects, mechanical coupling, constitutive damage law and contact friction are taken into account. The application in ANSYS/LS-DYNA program is elaborated. The effect of the main process parameter a blanking clearance on the deformation of 1018 steel and quality of the blank's sheared edge is analyzed. The results of computer simulations can be used to forecasting quality of the final parts optimization.

METHOD OF HOT ROLLING URANIUM METAL

Science.gov (United States)

Kaufmann, A.R.

1959-03-10

A method is given for quickly and efficiently hot rolling uranium metal in the upper part of the alpha phase temperature region to obtain sound bars and sheets possessing a good surface finish. The uranium metal billet is heated to a temperature in the range of 1000 deg F to 1220 deg F by immersion iii a molten lead bath. The heated billet is then passed through the rolls. The temperature is restored to the desired range between successive passes through the rolls, and the rolls are turned down approximately 0.050 inch between successive passes.

ANALYSIS OF NONMAGNETIC METAL INDUCTION HEATING PROCESSES BY FLAT-TYPE CIRCULAR SOLENOIDAL FIELD

Directory of Open Access Journals (Sweden)

Yu. Batygin

2016-12-01

Full Text Available The article analyzes the electromagnetic processes in the system of induction heating with estimating the main characteristics of heating the non-magnetic sheet metal. The analytical expressions for numerical estimates of the induced current in terms of the phase of the excitation signal are presented. The dependence for the heating temperature of the considered circular sheet metal area for the time corresponding to the interval phase has been determined.

Studies on micro plasto hydrodymic lubrication in metal forming

DEFF Research Database (Denmark)

Bay, Niels; Bech, Jakob Ilsted; Andreasen, Jan Lasson

2002-01-01

The influence of work piece surface topography on friction and lubrication and final surface quality in metal forming operations is well known and has been pointed out by many researchers, see Schey (1983) and Bay and Wanheim (1990). This is especially the case when liquid lubrication is applied...... characterization models the potential entrapment of a lubricant in closed reservoirs is used as a parameter to predetermine the formability of a sheet metal, Steinhoff et al. (1996), Geiger et al. (1997) and Schmoeckel et al. (1997). In experimental studies on friction in metal forming applying the strip drawing...

How much metal can you get? Quantified mass balancing of base metal release during epidosite zone alteration in ophiolite-hosted VMS systems

OpenAIRE

Jowitt, Simon M.; Jenkin, Gawen R.T.; Coogan, Laurence A.; Naden, Jon

2009-01-01

Understanding source-deposit relationships in VMS systems is important for mineral exploration and to increase knowledge of seafloor hydrothermal processes and ocean–crust fluxes. Although it is known that metals are stripped from oceanic crust by hydrothermal fluids and are partly redeposited in orebodies, some aspects are poorly understood. It has been proposed that metal-depleted epidosites (epidote–quartz–chlorite–Fe-oxide–titanite units within sheeted dyke complexes) were the source rock...

Transparent and conductive electrodes by large-scale nano-structuring of noble metal thin-films

DEFF Research Database (Denmark)

Linnet, Jes; Runge Walther, Anders; Wolff, Christian

2018-01-01

grid, and nano-wire thin-films. The indium and carbon films do not match the chemical stability nor the electrical performance of the noble metals, and many metal films are not uniform in material distribution leading to significant surface roughness and randomized transmission haze. We demonstrate...... solution-processed masks for physical vapor-deposited metal electrodes consisting of hexagonally ordered aperture arrays with scalable aperture-size and spacing in an otherwise homogeneous noble metal thin-film that may exhibit better electrical performance than carbon nanotube-based thin-films...... for equivalent optical transparency. The fabricated electrodes are characterized optically and electrically by measuring transmittance and sheet resistance. The presented methods yield large-scale reproducible results. Experimentally realized thin-films with very low sheet resistance, Rsh = 2.01 ± 0.14 Ω...

Overview of AMD (Automotive Metal Division)/USAMP projects

Energy Technology Data Exchange (ETDEWEB)

Demeri, M. [Ford Motor Co., Dearborn, MI (United States)

2001-07-01

This power point presentation described the mission of Ford's Automotive Metal Division (AMD) and presented a list of AMD projects. Their goal is to facilitate the development of improved materials and related manufacturing technologies for the automotive use of metals through cooperative, precompetitive programs, including those supporting PNGV. Some of the projects included: (1) magnesium casting for structural applications, (2) low cost powder metallurgy technology for particle reinforced aluminium, (3) sorting mixed alloys from shredded automobiles, (4) hydroforming aluminium tubes, (5) flexible binder controls for robust sampling, (6) long life electrodes for resistance spot welding of aluminium, sheet alloys, and coated high strength sheet steels, (7) NDE tools for evaluation of laser welded metals, (8) magnesium power train die cast components, (9) improved A206 alloy for cast automotive suspension components, (10) plasma arc welding of lightweight metals such as aluminium/magnesium, and (11) warm forming of aluminium alloys. The objectives, process controls and benefits of each of these projects were illustrated. Some of the issues that still need to be resolved include: an improved alloy with greater grain size and strength, an easily washable lubricant, a process to rapidly heat the blank and feed it into the heated dies, a method to achieve better thermal distribution in dies, and post forming mechanical properties. 5 figs.

Extracting metals directly from metal oxides

International Nuclear Information System (INIS)

Wai, C.M.; Smart, N.G.; Phelps, C.

1997-01-01

A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of β-diketones, halogenated β-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process. 4 figs

EXTREMELY METAL-POOR GALAXIES: THE ENVIRONMENT

Energy Technology Data Exchange (ETDEWEB)

Filho, M. E. [Universidad de Las Palmas de Gran Canaria–Universidad de La Laguna, CIE Canarias: Tri-Continental Atlantic Campus, Canary Islands (Spain); Almeida, J. Sánchez; Muñoz-Tuñón, C. [Instituto Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Nuza, S. E.; Kitaura, F.; Heß, S., E-mail: mfilho@astro.up.pt [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)

2015-04-01

We have analyzed bibliographical observational data and theoretical predictions, in order to probe the environment in which extremely metal-poor dwarf galaxies (XMPs) reside. We have assessed the H i component and its relation to the optical galaxy, the cosmic web type (voids, sheets, filaments and knots), the overdensity parameter and analyzed the nearest galaxy neighbors. The aim is to understand the role of interactions and cosmological accretion flows in the XMP observational properties, particularly the triggering and feeding of the star formation. We find that XMPs behave similarly to Blue Compact Dwarfs; they preferably populate low-density environments in the local universe: ∼60% occupy underdense regions, and ∼75% reside in voids and sheets. This is more extreme than the distribution of irregular galaxies, and in contrast to those regions preferred by elliptical galaxies (knots and filaments). We further find results consistent with previous observations; while the environment does determine the fraction of a certain galaxy type, it does not determine the overall observational properties. With the exception of five documented cases (four sources with companions and one recent merger), XMPs do not generally show signatures of major mergers and interactions; we find only one XMP with a companion galaxy within a distance of 100 kpc, and the H i gas in XMPs is typically well-behaved, demonstrating asymmetries mostly in the outskirts. We conclude that metal-poor accretion flows may be driving the XMP evolution. Such cosmological accretion could explain all the major XMP observational properties: isolation, lack of interaction/merger signatures, asymmetric optical morphology, large amounts of unsettled, metal-poor H i gas, metallicity inhomogeneities, and large specific star formation.

A transparent electrode based on a metal nanotrough network.

Science.gov (United States)

Wu, Hui; Kong, Desheng; Ruan, Zhichao; Hsu, Po-Chun; Wang, Shuang; Yu, Zongfu; Carney, Thomas J; Hu, Liangbing; Fan, Shanhui; Cui, Yi

2013-06-01

Transparent conducting electrodes are essential components for numerous flexible optoelectronic devices, including touch screens and interactive electronics. Thin films of indium tin oxide-the prototypical transparent electrode material-demonstrate excellent electronic performances, but film brittleness, low infrared transmittance and low abundance limit suitability for certain industrial applications. Alternatives to indium tin oxide have recently been reported and include conducting polymers, carbon nanotubes and graphene. However, although flexibility is greatly improved, the optoelectronic performance of these carbon-based materials is limited by low conductivity. Other examples include metal nanowire-based electrodes, which can achieve sheet resistances of less than 10Ω □(-1) at 90% transmission because of the high conductivity of the metals. To achieve these performances, however, metal nanowires must be defect-free, have conductivities close to their values in bulk, be as long as possible to minimize the number of wire-to-wire junctions, and exhibit small junction resistance. Here, we present a facile fabrication process that allows us to satisfy all these requirements and fabricate a new kind of transparent conducting electrode that exhibits both superior optoelectronic performances (sheet resistance of ~2Ω □(-1) at 90% transmission) and remarkable mechanical flexibility under both stretching and bending stresses. The electrode is composed of a free-standing metallic nanotrough network and is produced with a process involving electrospinning and metal deposition. We demonstrate the practical suitability of our transparent conducting electrode by fabricating a flexible touch-screen device and a transparent conducting tape.

Simulation of the ductile damage under the metal forming

International Nuclear Information System (INIS)

Bogatov, A. A.

2003-01-01

Potentiality of metal forming is limited by ductile damage. The damage degree is estimated by the scalar value ω, that is equal to 0(ω=0) before plastic strain and is equal to 1(ω=1) at the macro cracks moment. There are two criteria that describe micro damage. The value ω=ω * corresponds to the generation of micro voids that couldn't be recovered by recrystallization but do not reduce the metal strength. The value ω=ω ** corresponds to the generation of micro voids that reduce the metal strength and material long life. The models of metal damage accumulation under pure and alternate strain also the model of metal damage recovery under the recrystallization are developed. The specimen testing at high loading parameters gives the basic equations of the ductile damage mechanics. All of that gives the method to study ductile damage under the metal forming. The methodology damage nucleation and growing is shown on various examples: the void and crack development in the areas ductile damage and unlimited ductility; mathematical simulation of the metal damage under the sheet and wire drawing and others. The problems of physical simulating at the ductile damage under metal forming are shown too in this paper. The method and equipment of metal damage physical simulation are proposed. (Original)

Metal binding characterization and conformational studies using Raman microscopy of resin-bound poly(aspartic acid).

Science.gov (United States)

Stair, Jacqueline L; Holcombe, James A

2007-03-01

The metal binding capacities, conditional stability constants, and secondary structure of immobilized polyaspartic acid (PLAsp) (n = 6, 20, and 30) on TentaGel resin were determined when binding Mg2+, Co2+, Cd2+, and Ni2+. Metal binding to the synthesized peptides was evaluated using breakthrough curves from a packed microcolumn and flame atomic absorption spectrophotometry (FAAS) detection. The metal capacities reached values of 590, 2160, and 3710 mumol of metal/g of resin for the 6-mer, 20-mer, and 30-mer, respectively, and this resulted in 2-3 residues per metal for all peptides and metals tested. Surprisingly, the concentrated environment of the resin along with the spatial distribution of attachment groups allowed for most residues to participate in metal binding regardless of the peptide length. Conditional stability constants calculated using single metal binding isotherms indicated that binding strength decreased as the chain length increased on the resin. Raman microscopy on single beads was used to determine PLAsp secondary structure, and all peptides were of a mixed conformation (i.e., beta-sheets, alpha-helices, random chain, etc.) during neutral conditioning and metal binding. Uniquely, the longer 20-mer and 30-mer peptides showed a distinct change from a mixed conformation to beta-sheets and alpha-helices during metal release with acid. This study confirms that metal release by longer immobilized peptides is often assisted by a conformational change, which easily spoils the binding cavity, while shorter peptides may release metal primarily by H+ displacement.

Towards nanoprinting with metals on graphene

Science.gov (United States)

Melinte, G.; Moldovan, S.; Hirlimann, C.; Liu, X.; Bégin-Colin, S.; Bégin, D.; Banhart, F.; Pham-Huu, C.; Ersen, O.

2015-08-01

Graphene and carbon nanotubes are envisaged as suitable materials for the fabrication of the new generation of nanoelectronics. The controlled patterning of such nanostructures with metal nanoparticles is conditioned by the transfer between a recipient and the surface to pattern. Electromigration under the impact of an applied voltage stands at the base of printing discrete digits at the nanoscale. Here we report the use of carbon nanotubes as nanoreservoirs for iron nanoparticles transfer on few-layer graphene. An initial Joule-induced annealing is required to ensure the control of the mass transfer with the nanotube acting as a `pen' for the writing process. By applying a voltage, the tube filled with metal nanoparticles can deposit metal on the surface of the graphene sheet at precise locations. The reverse transfer of nanoparticles from the graphene surface to the nanotube when changing the voltage polarity opens the way for error corrections.

Laminated exfoliated graphite composite-metal compositions for fuel cell flow field plate or bipolar plate applications

Science.gov (United States)

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

2014-05-20

An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the first exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.

Experimental formability analysis of bondal sandwich sheet

Science.gov (United States)

Kami, Abdolvahed; Banabic, Dorel

2018-05-01

Metal/polymer/metal sandwich sheets have recently attracted the interests of industries like automotive industry. These sandwich sheets have superior properties over single-layer metallic sheets including good sound and vibration damping and light weight. However, the formability of these sandwich sheets should be enhanced which requires more research. In this paper, the formability of Bondal sheet (DC06/viscoelastic polymer/DC06 sandwich sheet) was studied through different types of experiments. The mechanical properties of Bondal were determined by uniaxial tensile tests. Hemispherical punch stretching and hydraulic bulge tests were carried out to determine the forming limit diagram (FLD) of Bondal. Furthermore, cylindrical and square cup drawing tests were performed in dry and oil lubricated conditions. These tests were conducted at different blank holding forces (BHFs). An interesting observation about Bondal sheet deep drawing was obtaining of higher drawing depths at dry condition in comparison with oil-lubricated condition.

Explicit and implicit springback simulation in sheet metal forming using fully coupled ductile damage and distortional hardening model

Science.gov (United States)

Yetna n'jock, M.; Houssem, B.; Labergere, C.; Saanouni, K.; Zhenming, Y.

2018-05-01

The springback is an important phenomenon which accompanies the forming of metallic sheets especially for high strength materials. A quantitative prediction of springback becomes very important for newly developed material with high mechanical characteristics. In this work, a numerical methodology is developed to quantify this undesirable phenomenon. This methodoly is based on the use of both explicit and implicit finite element solvers of Abaqus®. The most important ingredient of this methodology consists on the use of highly predictive mechanical model. A thermodynamically-consistent, non-associative and fully anisotropic elastoplastic constitutive model strongly coupled with isotropic ductile damage and accounting for distortional hardening is then used. An algorithm for local integration of the complete set of the constitutive equations is developed. This algorithm considers the rotated frame formulation (RFF) to ensure the incremental objectivity of the model in the framework of finite strains. This algorithm is implemented in both explicit (Abaqus/Explicit®) and implicit (Abaqus/Standard®) solvers of Abaqus® through the users routine VUMAT and UMAT respectively. The implicit solver of Abaqus® has been used to study spingback as it is generally a quasi-static unloading. In order to compare the methods `efficiency, the explicit method (Dynamic Relaxation Method) proposed by Rayleigh has been also used for springback prediction. The results obtained within U draw/bending benchmark are studied, discussed and compared with experimental results as reference. Finally, the purpose of this work is to evaluate the reliability of different methods predict efficiently springback in sheet metal forming.

A New Approach for Handling of Micro Parts in Bulk Metal Forming

DEFF Research Database (Denmark)

Mahshid, Rasoul; Hansen, Hans Nørgaard; Arentoft, M.

2012-01-01

of production [1]. This can fulfill the demands for mass production and miniaturization in industries and academic communities. According to the recent studies, topics related to materials, process and simulation have been investigated intensively and well documented. Machines, forming tools and handling...... systems are critical elements to complete micro forming technology for transferring knowledge to industries and toward miniature manufacturing systems (micro factory) [2]. Since most metal forming processes are multi stage, making a new handling system with high reliability on accuracy and speed...... have been optimized or handling systems based on new concepts for gripping and releasing micro parts have been proposed. Making a handling system for micro parts made by sheet metals or foils is easier than those in bulk metal forming because parts are attached to the sheet during the forming process...

First-principles study of the interaction and charge transfer between graphene and metals

NARCIS (Netherlands)

Khomyakov, Petr; Giovannetti, G.; Rusu, P.C.; Brocks, G.; van den Brink, J.; Kelly, Paul J.

2009-01-01

Measuring the transport of electrons through a graphene sheet necessarily involves contacting it with metal electrodes. We study the adsorption of graphene on metal substrates using first-principles calculations at the level of density-functional theory. The bonding of graphene to Al, Ag, Cu, Au,

Progress in cold roll bonding of metals

International Nuclear Information System (INIS)

Li Long; Nagai, Kotobu; Yin Fuxing

2008-01-01

Layered composite materials have become an increasingly interesting topic in industrial development. Cold roll bonding (CRB), as a solid phase method of bonding same or different metals by rolling at room temperature, has been widely used in manufacturing large layered composite sheets and foils. In this paper, we provide a brief overview of a technology using layered composite materials produced by CRB and discuss the suitability of this technology in the fabrication of layered composite materials. The effects of process parameters on bonding, mainly including process and surface preparation conditions, have been analyzed. Bonding between two sheets can be realized when deformation reduction reaches a threshold value. However, it is essential to remove surface contamination layers to produce a satisfactory bond in CRB. It has been suggested that the degreasing and then scratch brushing of surfaces create a strong bonding between the layers. Bonding mechanisms, in which the film theory is expressed as the major mechanism in CRB, as well as bonding theoretical models, have also been reviewed. It has also been showed that it is easy for fcc structure metals to bond compared with bcc and hcp structure metals. In addition, hardness on bonding same metals plays an important part in CRB. Applications of composites produced by CRB in industrial fields are briefly reviewed and possible developments of CRB in the future are also described. Corrections were made to the abstract and conclusion of this article on 18 June 2008. The corrected electronic version is identical to the print version. (topical review)

Durability of metals from archaeological objects, metal meteorites, and native metals

International Nuclear Information System (INIS)

Johnson, A.B. Jr.; Francis, B.

1980-01-01

Metal durability is an important consideration in the multi-barrier nuclear waste storage concept. This study summarizes the ancient metals, the environments, and factors which appear to have contributed to metal longevity. Archaeological and radiochemical dating suggest that human use of metals began in the period 6000 to 7000 BC. Gold is clearly the most durable, but many objects fashioned from silver, copper, bronze, iron, lead, and tin have survived for several thousand years. Dry environments, such as tombs, appear to be optimum for metal preservation, but some metals have survived in shipwrecks for over a thousand years. The metal meteorites are Fe-base alloys with 5 to 60 wt% Ni and minor amounts of Co, I, and S. Some meteoritic masses with ages estimated to be 5,000 to 20,000 years have weathered very little, while other masses from the same meteorites are in advanced stages of weathering. Native metals are natural metallic ores. Approximately five million tonnes were mined from native copper deposits in Michigan. Copper masses from the Michigan deposits were transported by the Pleistocene glaciers. Areas on the copper surfaces which appear to represent glacial abrasion show minimal corrosion. Dry cooling tower technology has demonstrated that in pollution-free moist environments, metals fare better at temperatures above than below the dewpoint. Thus, in moderate temperature regimes, elevated temperatures may be useful rather than detrimental for exposures of metal to air. In liquid environments, relatively complex radiolysis reactions can occur, particularly where multiple species are present. A dry environment largely obviates radiolysis effects

Durability of metals from archaeological objects, metal meteorites, and native metals

Energy Technology Data Exchange (ETDEWEB)

Johnson, A.B. Jr.; Francis, B.

1980-01-01

Metal durability is an important consideration in the multi-barrier nuclear waste storage concept. This study summarizes the ancient metals, the environments, and factors which appear to have contributed to metal longevity. Archaeological and radiochemical dating suggest that human use of metals began in the period 6000 to 7000 BC. Gold is clearly the most durable, but many objects fashioned from silver, copper, bronze, iron, lead, and tin have survived for several thousand years. Dry environments, such as tombs, appear to be optimum for metal preservation, but some metals have survived in shipwrecks for over a thousand years. The metal meteorites are Fe-base alloys with 5 to 60 wt% Ni and minor amounts of Co, I, and S. Some meteoritic masses with ages estimated to be 5,000 to 20,000 years have weathered very little, while other masses from the same meteorites are in advanced stages of weathering. Native metals are natural metallic ores. Approximately five million tonnes were mined from native copper deposits in Michigan. Copper masses from the Michigan deposits were transported by the Pleistocene glaciers. Areas on the copper surfaces which appear to represent glacial abrasion show minimal corrosion. Dry cooling tower technology has demonstrated that in pollution-free moist environments, metals fare better at temperatures above than below the dewpoint. Thus, in moderate temperature regimes, elevated temperatures may be useful rather than detrimental for exposures of metal to air. In liquid environments, relatively complex radiolysis reactions can occur, particularly where multiple species are present. A dry environment largely obviates radiolysis effects.

Electromagnetic confinement for vertical casting or containing molten metal

Science.gov (United States)

Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

1991-01-01

An apparatus and method adapted to confine a molten metal to a region by means of an alternating electromagnetic field. As adapted for use in the present invention, the alternating electromagnetic field given by B.sub.y =(2.mu..sub.o .rho.gy).sup.1/2 (where B.sub.y is the vertical component of the magnetic field generated by the magnet at the boundary of the region; y is the distance measured downward form the top of the region, .rho. is the metal density, g is the acceleration of gravity and .mu..sub.o is the permeability of free space) induces eddy currents in the molten metal which interact with the magnetic field to retain the molten metal with a vertical boudnary. As applied to an apparatus for the continuous casting of metal sheets or rods, metal in liquid form can be continuously introduced into the region defined by the magnetic field, solidified and conveyed away from the magnetic field in solid form in a continuous process.

MetalS(3), a database-mining tool for the identification of structurally similar metal sites.

Science.gov (United States)

Valasatava, Yana; Rosato, Antonio; Cavallaro, Gabriele; Andreini, Claudia

2014-08-01

We have developed a database search tool to identify metal sites having structural similarity to a query metal site structure within the MetalPDB database of minimal functional sites (MFSs) contained in metal-binding biological macromolecules. MFSs describe the local environment around the metal(s) independently of the larger context of the macromolecular structure. Such a local environment has a determinant role in tuning the chemical reactivity of the metal, ultimately contributing to the functional properties of the whole system. The database search tool, which we called MetalS(3) (Metal Sites Similarity Search), can be accessed through a Web interface at http://metalweb.cerm.unifi.it/tools/metals3/ . MetalS(3) uses a suitably adapted version of an algorithm that we previously developed to systematically compare the structure of the query metal site with each MFS in MetalPDB. For each MFS, the best superposition is kept. All these superpositions are then ranked according to the MetalS(3) scoring function and are presented to the user in tabular form. The user can interact with the output Web page to visualize the structural alignment or the sequence alignment derived from it. Options to filter the results are available. Test calculations show that the MetalS(3) output correlates well with expectations from protein homology considerations. Furthermore, we describe some usage scenarios that highlight the usefulness of MetalS(3) to obtain mechanistic and functional hints regardless of homology.

Recent Advances in Antimicrobial Hydrogels Containing Metal Ions and Metals/Metal Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

Fazli Wahid

2017-11-01

Full Text Available Recently, the rapid emergence of antibiotic-resistant pathogens has caused a serious health problem. Scientists respond to the threat by developing new antimicrobial materials to prevent or control infections caused by these pathogens. Polymer-based nanocomposite hydrogels are versatile materials as an alternative to conventional antimicrobial agents. Cross-linking of polymeric materials by metal ions or the combination of polymeric hydrogels with nanoparticles (metals and metal oxide is a simple and effective approach for obtaining a multicomponent system with diverse functionalities. Several metals and metal oxides such as silver (Ag, gold (Au, zinc oxide (ZnO, copper oxide (CuO, titanium dioxide (TiO2 and magnesium oxide (MgO have been loaded into hydrogels for antimicrobial applications. The incorporation of metals and metal oxide nanoparticles into hydrogels not only enhances the antimicrobial activity of hydrogels, but also improve their mechanical characteristics. Herein, we summarize recent advances in hydrogels containing metal ions, metals and metal oxide nanoparticles with potential antimicrobial properties.

Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

KAUST Repository

Chen, Ye; Khashab, Niveen M.; Tao, Jing

2017-01-01

Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets

Characterization and modelling techniques for gas metal arc welding of DP 600 sheet steels

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, K.; Prahl, U.; Bleck, W. [RWTH Aachen University, Department of Ferrous Metallurgy (IEHK) (Germany); Reisgen, U.; Schleser, M.; Abdurakhmanov, A. [RWTH Aachen University, Welding and Joining Institute (ISF) (Germany)

2010-11-15

The objectives of the present work are to characterize the Gas Metal Arc Welding process of DP 600 sheet steel and to summarize the modelling techniques. The time-temperature evolution during the welding cycle was measured experimentally and modelled with the softwaretool SimWeld. To model the phase transformations during the welding cycle dilatometer tests were done to quantify the parameters for phase field modelling by MICRESS {sup registered}. The important input parameters are interface mobility, nucleation density, etc. A contribution was made to include austenite to bainite transformation in MICRESS {sup registered}. This is useful to predict the microstructure in the fast cooling segments. The phase transformation model is capable to predict the microstructure along the heating and cooling cycles of welding. Tensile tests have shown the evidence of failure at the heat affected zone, which has the ferrite-tempered martensite microstructure. (orig.)

White organic light-emitting diodes with 4 nm metal electrode

Science.gov (United States)

Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Gather, Malte C.; Reineke, Sebastian

2015-10-01

We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

Comparison of Conventional Deep Drawing, Hydromechanical Deep-Drawing and High Pressure Sheet Metal Forming by Numerical Experiments

International Nuclear Information System (INIS)

Oender, I. Erkan; Tekkaya, A. Erman

2005-01-01

Increasing use of new technologies in automotive and aircraft applications requires intensive research and developments on sheet metal forming processes. This study focuses on the assessment of sheet hydroforming, hydro-mechanical deep drawing and conventional deep-drawing processes by performing a systematic analysis by numerical simulations. Circular, elliptic, rectangular and square cross-section cups have been selected for the geometry spectrum. Within the range of each cross section, depth, drawing ratio and fillet radii have been altered systematically. St14 stainless steel has been used as the material throughout the study. The deformation behavior has been described by an elasto-plastic material model and all numerical simulations have been carried out by using a dynamic-explicit commercial finite element code. During the analyses each workpiece is produced by the three competing processes. The analyses results such as sheet thickness distribution, necking, forming of radii etc., are used for assessing the success of each forming process alternative. The analyses revealed that depending on the workpiece geometry and dimensional properties certain processes are preferable for obtaining satisfactory products. The process windows for each process have been established based on the analyzed parameters of the three different product geometries. This data is expected to be useful for selecting the appropriate production process for a given workpiece geometry

Springback Simulation and Tool Surface Compensation Algorithm for Sheet Metal Forming

International Nuclear Information System (INIS)

Shen Guozhe; Hu Ping; Zhang Xiangkui; Chen Xiaobin; Li Xiaoda

2005-01-01

Springback is an unquenchable forming defect in the sheet metal forming process. How to calculate springback accurately is a big challenge for a lot of FEA software. Springback compensation makes the stamped final part accordant with the designed part shape by modifying tool surface, which depends on the accurate springback amount. How ever, the meshing data based on numerical simulation is expressed by nodes and elements, such data can not be supplied directly to tool surface CAD data. In this paper, a tool surface compensation algorithm based on numerical simulation technique of springback process is proposed in which the independently developed dynamic explicit springback algorithm (DESA) is used to simulate springback amount. When doing the tool surface compensation, the springback amount of the projected point can be obtained by interpolation of the springback amount of the projected element nodes. So the modified values of tool surface can be calculated reversely. After repeating the springback and compensation calculations for 1∼3 times, the reasonable tool surface mesh is gained. Finally, the FEM data on the compensated tool surface is fitted into the surface by CAD modeling software. The examination of a real industrial part shows the validity of the present method

TOPICAL REVIEW Progress in cold roll bonding of metals

Directory of Open Access Journals (Sweden)

Long Li, Kotobu Nagai and Fuxing Yin

2008-01-01

Full Text Available Layered composite materials have become an increasingly interesting topic in industrial development. Cold roll bonding (CRB, as a solid phase method of bonding same or different metals by rolling at room temperature, has been widely used in manufacturing large layered composite sheets and foils. In this paper, we provide a brief overview of a technology using layered composite materials produced by CRB and discuss the suitability of this technology in the fabrication of layered composite materials. The effects of process parameters on bonding, mainly including process and surface preparation conditions, have been analyzed. Bonding between two sheets can be realized when deformation reduction reaches a threshold value. However, it is essential to remove surface contamination layers to produce a satisfactory bond in CRB. It has been suggested that the degreasing and then scratch brushing of surfaces create a strong bonding between the layers. Bonding mechanisms, in which the film theory is expressed as the major mechanism in CRB, as well as bonding theoretical models, have also been reviewed. It has also been showed that it is easy for fcc structure metals to bond compared with bcc and hcp structure metals. In addition, hardness on bonding same metals plays an important part in CRB. Applications of composites produced by CRB in industrial fields are briefly reviewed and possible developments of CRB in the future are also described.

Production of Liquid Metal Spheres by Molding

Directory of Open Access Journals (Sweden)

Mohammed G. Mohammed

2014-10-01

Full Text Available This paper demonstrates a molding technique for producing spheres composed of eutectic gallium-indium (EGaIn with diameters ranging from hundreds of microns to a couple millimeters. The technique starts by spreading EGaIn across an elastomeric sheet featuring cylindrical reservoirs defined by replica molding. The metal flows into these features during spreading. The spontaneous formation of a thin oxide layer on the liquid metal keeps the metal flush inside these reservoirs. Subsequent exposure to acid removes the oxide and causes the metal to bead up into a sphere with a size dictated by the volume of the reservoirs. This technique allows for the production and patterning of droplets with a wide range of volumes, from tens of nanoliters up to a few microliters. EGaIn spheres can be embedded or encased subsequently in polymer matrices using this technique. These spheres may be useful as solder bumps, electrodes, thermal contacts or components in microfluidic devices (valves, switches, pumps. The ease of parallel-processing and the ability to control the location of the droplets during their formation distinguishes this technique.

Extraction process for removing metallic impurities from alkalide metals

Science.gov (United States)

Royer, Lamar T.

1988-01-01

A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

Perforation of metal sheets

DEFF Research Database (Denmark)

Steenstrup, Jens Erik

simulation is focused on the sheet deformation. However, the effect on the tool and press is included. The process model is based on the upper bound analysis in order to predict the force progress and hole characteristics etc. Parameter analyses are divided into two groups, simulation and experimental tests......The main purposes of this project are:1. Development of a dynamic model for the piercing and performation process2. Analyses of the main parameters3. Establishing demands for process improvements4. Expansion of the existing parameter limitsThe literature survey describes the process influence...

Metal-metal-hofteproteser

DEFF Research Database (Denmark)

Ulrich, Michael; Overgaard, Søren; Penny, Jeannette

2014-01-01

In Denmark 4,456 metal-on-metal (MoM) hip prostheses have been implanted. Evidence demonstrates that some patients develope adverse biological reactions causing failures of MoM hip arthroplasty. Some reactions might be systemic. Failure rates are associated with the type and the design of the Mo...

Development of an in-plane biaxial test for forming limit curve (FLC) characterization of metallic sheets

International Nuclear Information System (INIS)

Zidane, I; Guines, D; Léotoing, L; Ragneau, E

2010-01-01

The main objective of this work is to propose a new experimental device able to give for a single specimen a good prediction of rheological parameters and formability under static and dynamic conditions (for intermediate strain rates). In this paper, we focus on the characterization of sheet metal forming. The proposed device is a servo-hydraulic testing machine provided with four independent dynamic actuators allowing biaxial tensile tests on cruciform specimens. The formability is evaluated thanks to the classical forming limit diagram (FLD), and one of the difficulties of this study was the design of a dedicated specimen for which the necking phenomenon appears in its central zone. If necking is located in the central zone of the specimen, then the speed ratio between the two axes controls the strain path in this zone and a whole forming limit curve can be covered. Such a specimen is proposed through a numerical and experimental validation procedure. A rigorous procedure for the detection of numerical and experimental forming strains is also presented. Finally, an experimental forming limit curve is determined and validated for an aluminium alloy dedicated to the sheet forming processes (AA5086)

Pathway to low-cost metallization of silicon solar cell through understanding of the silicon metal interface and plating chemistry

International Nuclear Information System (INIS)

Ebong, Abasifreke

2014-01-01

Metallization is crucial to silicon solar cell performance. It is the second most expensive process step in the fabrication of a solar cell. In order to reduce the cost of solar cell, the metallization cost has to be cut down by using less metal without compromising the efficiency. Screen-printing has been used in metallizing the commercial solar cell because of the high throughput and low cost at the expense of performance. However, because of the variability in the screen-printed gridlines, the amount of Ag metal used cannot be controlled. More so, the dependence of the contact resistance on doping necessitates the use of low sheet resistance emitters, which exacerbates losses in the blue response and hence the efficiency. To balance the contact resistance and improve blue response, several approaches have been undertaken including, use of Ag pastes incorporating nanoparticle glass frits that will not diffuse excessively into a lightly doped emitter, Ni plating on lightly doped emitter through SiNx dielectric plus NiSi formation followed by Cu and/or Ag plating, light induced plating (LIP) of Ag or Cu on fired through dielectric metal seed layers formed by aerosol or inkjet or screen-printing. All these approaches require excellent adhesion and gridline conductivity to minimize the total series resistance, which impedes the collection of electrons. This paper presents the issues and the pathway to achieving high efficiency using low cost metallization technology involving inkjet-printed Ag fine gridline having 38 μm width and 3 μm height fired through the SiNx followed by Ni and Cu plating. A comprehensive analysis of silicon/metal interface, using high precision microscopy, has shown that the investigated metallization technology is appropriate for the longevity of the device

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)

Leading research on super metal. 2. Aluminium materials; Super metal no sendo kenkyu. 2. Ogata sozai (aluminium kei)

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

Aluminum materials were surveyed to improve aluminum materials drastically so as to play an important role as prospective materials in response to the changing social environment. Aluminum materials have become the following metal materials to iron materials due to their light weight, durability, and profitability. Based on their merits and demerits, it was made clear how the aluminum materials contribute to the future resource saving, energy saving, and global environmental protection. Review was made on the two research and development themes which contribute to the creation of super metals. Hence, the themes proposed are focused on the creation of new aluminum mill products with ultra fine grain structure using very low temperature processing and on the creation of super-formability aluminum alloy sheets by advanced texture control using processing which can enhance the shearing stress. Results of the research and development are expected to provide wide applicability for other metals, ceramics, and polymers. 433 refs., 315 figs., 56 tabs.

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.

Predicting dietborne metal toxicity from metal influxes

Science.gov (United States)

Croteau, M.-N.; Luoma, S.N.

2009-01-01

Dietborne metal uptake prevails for many species in nature. However, the links between dietary metal exposure and toxicity are not well understood. Sources of uncertainty include the lack of suitable tracers to quantify exposure for metals such as copper, the difficulty to assess dietary processes such as food ingestion rate, and the complexity to link metal bioaccumulation and effects. We characterized dietborne copper, nickel, and cadmium influxes in a freshwater gastropod exposed to diatoms labeled with enriched stable metal isotopes. Metal influxes in Lymnaea stagnalis correlated linearly with dietborne metal concentrations over a range encompassing most environmental exposures. Dietary Cd and Ni uptake rate constants (kuf) were, respectively, 3.3 and 2.3 times higher than that for Cu. Detoxification rate constants (k detox) were similar among metals and appeared 100 times higher than efflux rate constants (ke). Extremely high Cu concentrations reduced feeding rates, causing the relationship between exposure and influx to deviate from linearity; i.e., Cu uptake rates leveled off between 1500 and 1800 nmol g-1 day-1. L. stagnalis rapidly takes up Cu, Cd, and Ni from food but detoxifies the accumulated metals, instead of reducing uptake or intensifying excretion. Above a threshold uptake rate, however, the detoxification capabilities of L. stagnalis are overwhelmed.

Metal Matrix Composite Solar Cell Metallization

Directory of Open Access Journals (Sweden)

Wilt David M.

2017-01-01

Full Text Available Advanced solar cells are moving to ever thinner formats in order to save mass and in some cases improve performance. As cells are thinned, the possibility that they may fracture or cleave due to mechanical stresses is increased. Fractures of the cell can degrade the overall device performance if the fracture propagates through the contact metallization, which frequently occurs. To address this problem, a novel semiconductor metallization system based on multi-walled carbon nanotube (CNT reinforcement, termed metal matrix composite (MMC metallization is under investigation. Electro-mechanical characterization of MMC films demonstrate their ability to provide electrical conductivity over >40 micron wide cracks in the underlying semiconductor, with the carbon nanotubes bridging the gap. In addition, these materials show a “self-healing” behaviour, electrically reconnecting at ~30 microns when strained past failure. Triple junction (TJ space cells with MMC metallization demonstrated no loss in Jsc after intentional fracture, whereas TJ cells with conventional metallization suffer up to 50% Jsc loss.

Apparatus for efficient sidewall containment of molten metal with horizontal alternating magnetic fields utilizing low reluctance rims

Science.gov (United States)

Praeg, Walter F.

1999-01-01

A method and apparatus for casting sheets of metal from molten metal. The apparatus includes a containment structure having an open side, a horizontal alternating magnetic field generating structure and rollers including low reluctance rim structures. The magnetic field and the rollers help contain the molten metal from leaking out of the containment structure.

Apparatus for efficient sidewall containment of molten metal with horizontal alternating magnetic fields utilizing a ferromagnetic dam

Science.gov (United States)

Praeg, Walter F.

1997-01-01

An apparatus for casting sheets of metal from molten metal. The apparatus includes a containment structure having an open side, a horizontal alternating magnetic field generating structure and a ferromagnetic dam. The magnetic field and the ferromagnetic dam contain the molten metal from leaking out side portions of the open side of the containment structure.

Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

International Nuclear Information System (INIS)

1980-01-01

Finely divided powders are prepared by first reacting an aqueous solution containing dissolved metal values with excess urea. After the reaction of water in the solution with urea is complete, the resulting molten urea solution is heated to cause metal values in solution to precipitate. The resulting mixture containing precipitated metal values is heated to evaporate volatile material, leaving a dry powder containing the metal values. Detailed examples are given. (U.K.)

A computational study of adsorption of divalent metal ions on graphene oxide

Directory of Open Access Journals (Sweden)

Somphob Thompho

2017-12-01

Full Text Available Adsorption of divalent metal ions (Pb2+,Cd2+, Zn2+,Cu2+ on graphene oxide (GO was studied using density functional theory (DFT. Adsorption geometries and energies, as well as the nature of the binding energy, were calculated for the interaction of divalent metal ions with oxygen-containing groups on the surface of GO. The configurations of the complexes were modeled by placing the divalent metal ions above the center and perpendicular to the surface. Binding of Cu2+ to the GO sheet was predicted to be much stronger than that for other divalent metal ions. Calculated results show good agreement with experimental observations and provide useful information for environmental pollution cleanup.

Infection or metal hypersensitivity? The diagnostic challenge of failure in metal-on-metal bearings.

LENUS (Irish Health Repository)

Galbraith, John G

2011-04-01

The use of second generation metal-on-metal hip articulations has gained favour in the past few years. A hypersensitivity reaction to the metal-on-metal bearing, although rare, is a reported complication and is a novel mode of failure of these implants. Differentiating failure secondary to infection from failure secondary to metal hypersensitivity represents a significant diagnostic challenge. A retrospective review of all cases of hip arthroplasty using metal-on-metal bearings over a 5-year period at a tertiary referral centre identified 3 cases of failure secondary to metal hypersensitivity. Clinical presentation, serological markers, radiological imaging and histological analysis of all cases identified were evaluated. Histological analysis of periprosthetic tissue in all 3 cases identified characteristic features such as perivascular lymphocytic aggregates and chronic inflammation consistent with aseptic lymphocytic vasculitis-associated lesions (ALVAL). This study highlights that failure secondary to metal hypersensitivity must be considered in patients presenting with the reappearance of persistent pain, marked joint effusion, and the development of early osteolysis in the absence of infection.

Alkali metal and alkali metal hydroxide intercalates of the layered transition metal disulfides

International Nuclear Information System (INIS)

Kanzaki, Y.; Konuma, M.; Matsumoto, O.

1981-01-01

The intercalation reaction of some layered transition metal disulfides with alkali metals, alkali metal hydroxides, and tetraalkylammonium hydroxides were investigated. The alkali metal intercalates were prepared in the respective metal-hexamethylphosphoric triamide solutions in vaccuo, and the hydroxide intercalates in aqueous hydroxide solutions. According to the intercalation reaction, the c-lattice parameter was increased, and the increase indicated the expansion of the interlayer distance. In the case of alkali metal intercalates, the expansion of the interlayer distance increased continuously, corresponding to the atomic radius of the alkali metal. On the other hand, the hydroxide intercalates showed discrete expansion corresponding to the effective ionic radius of the intercalated cation. All intercalates of TaS 2 amd NbS 2 were superconductors. The expansion of the interlayer distance tended to increase the superconducting transition temperature in the intercalates of TaS 2 and vice versa in those of NbS 2 . (orig.)

Unusual metal-insulator transition in disordered ferromagnetic films

International Nuclear Information System (INIS)

Muttalib, K.A.; Wölfle, P.; Misra, R.; Hebard, A.F.

2012-01-01

We present a theoretical interpretation of recent data on the conductance near and farther away from the metal-insulator transition in thin ferromagnetic Gd films of thickness b≈2-10 nm. For increasing sheet resistances a dimensional crossover takes place from d=2 to d=3 dimensions, since the large phase relaxation rate caused by scattering of quasiparticles off spin wave excitations renders the dephasing length L φ ≲b at strong disorder. The conductivity data in the various regimes obey fractional power-law or logarithmic temperature dependence. One observes weak localization and interaction induced corrections at weaker disorder. At strong disorder, near the metal-insulator transition, the data show scaling and collapse onto two scaling curves for the metallic and insulating regimes. We interpret this unusual behavior as proof of two distinctly different correlation length exponents on both sides of the transition.

Designing the Color of Hot-Dip Galvanized Steel Sheet Through Destructive Light Interference Using a Zn-Ti Liquid Metallic Bath

Science.gov (United States)

Levai, Gabor; Godzsák, Melinda; Török, Tamas I.; Hakl, Jozsef; Takáts, Viktor; Csik, Attila; Vad, Kalman; Kaptay, George

2016-07-01

The color of hot-dip galvanized steel sheet was adjusted in a reproducible way using a liquid Zn-Ti metallic bath, air atmosphere, and controlling the bath temperature as the only experimental parameter. Coloring was found only for samples cooled in air and dipped into Ti-containing liquid Zn. For samples dipped into a 0.15 wt pct Ti-containing Zn bath, the color remained metallic (gray) below a 792 K (519 °C) bath temperature; it was yellow at 814 K ± 22 K (541 °C ± 22 °C), violet at 847 K ± 10 K (574 °C ± 10 °C), and blue at 873 K ± 15 K (600 °C ± 15 °C). With the increasing bath temperature, the thickness of the adhered Zn-Ti layer gradually decreased from 52 to 32 micrometers, while the thickness of the outer TiO2 layer gradually increased from 24 to 69 nm. Due to small Al contamination of the Zn bath, a thin (around 2 nm) alumina-rich layer is found between the outer TiO2 layer and the inner macroscopic Zn layer. It is proven that the color change was governed by the formation of thin outer TiO2 layer; different colors appear depending on the thickness of this layer, mostly due to the destructive interference of visible light on this transparent nano-layer. A complex model was built to explain the results using known relationships of chemical thermodynamics, adhesion, heat flow, kinetics of chemical reactions, diffusion, and optics. The complex model was able to reproduce the observations and allowed making predictions on the color of the hot-dip galvanized steel sample, as a function of the following experimental parameters: temperature and Ti content of the Zn bath, oxygen content, pressure, temperature and flow rate of the cooling gas, dimensions of the steel sheet, velocity of dipping the steel sheet into the Zn-Ti bath, residence time of the steel sheet within the bath, and the velocity of its removal from the bath. These relationships will be valuable for planning further experiments and technologies on color hot-dip galvanization of steel

Application of liquid metals for the extraction of solid metals

International Nuclear Information System (INIS)

Borgstedt, H.U.

1996-01-01

Liquid metals dissolve several solid metals in considerable amounts at moderate temperatures. The dissolution processes may be based upon simple physical solubility, formation of intermetallic phases. Even chemical reactions are often observed in which non-metallic elements might be involved. Thus, the capacity to dissolve metals and chemical properties of the liquid metals play a role in these processes. Besides the solubility also chemical properties and thermochemical data are of importance. The dissolution of metals in liquid metals can be applied to separate the solutes from other metals or non-metallic phases. Relatively noble metals can be chemically reduced by the liquid phases. Such solution processes can be applied in the extractive metallurgy, for instance to extract metals from metallic waste. The recycling of metals is of high economical and ecological importance. Examples of possible processes are discussed. (author)

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

International Nuclear Information System (INIS)

Richard T. Scalettar; Warren E. Pickett

2005-01-01

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

Energy Technology Data Exchange (ETDEWEB)

Scalettar, Richard T.; Pickett, Warren E.

2004-07-01

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals.

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

Energy Technology Data Exchange (ETDEWEB)

Richard T. Scalettar; Warren E. Pickett

2005-08-02

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (i) Mott transitions in transition metal oxides, (ii) magnetism in half-metallic compounds, and (iii) large volume-collapse transitions in f-band metals.

Interface Modification of Bernal- and Rhombohedral-Stacked Trilayer-Graphene/Metal Electrode on Resistive Switching of Silver Electrochemical Metallization Cells.

Science.gov (United States)

Wang, Jer-Chyi; Chan, Ya-Ting; Chen, Wei-Fan; Wu, Ming-Chung; Lai, Chao-Sung

2017-10-25

Bernal- and rhombohedral-stacked trilayer graphene (B- and r-TLG) on nickel (Ni) and iridium (Ir) films acting as bottom electrodes (BEs) of silver electrochemical metallization cells (Ag-EMCs) have been investigated in this study. Prior to the fabrication of the EMC devices, Raman mapping and atomic force microscopy are applied to identify the B- and r-TLG sheets, with the latter revealing a significant D peak and a rough surface for the Ir film. The Ag-EMCs with the stacked BE of r-TLG on the Ir film show a conductive mechanism of Schottky emission at the positive top electrode bias for both high- and low-resistance states that can be examined by the resistance change with the device area and are modulated by pulse bias operation. Thus, an effective electron barrier height of 0.262 eV at the r-TLG and Ir interface is obtained because of the conspicuous energy gap of r-TLG on the Ir film and the van der Waals (vdW) gap between the r-TLG and Ir contact metal. With the use of Ni instead of Ir contact metal, the Ag-EMCs with TLG BE demonstrate +0.3 V/-0.75 V operation voltages, more than 10 4 s data retention at 115 °C and 250 times endurance testing, making the TLG sheets suitable for low-power nonvolatile memory applications on flexible substrates.

White organic light-emitting diodes with 4 nm metal electrode

Energy Technology Data Exchange (ETDEWEB)

Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Reineke, Sebastian [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden (Germany); Gather, Malte C. [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden (Germany); Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom)

2015-10-19

We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

Process Development And Simulation For Cold Fabrication Of Doubly Curved Metal Plate By Using Line Array Roll Set

International Nuclear Information System (INIS)

Shim, D. S.; Jung, C. G.; Seong, D. Y.; Yang, D. Y.; Han, J. M.; Han, M. S.

2007-01-01

For effective manufacturing of a doubly curved sheet metal, a novel sheet metal forming process is proposed. The suggested process uses a Line Array Roll Set (LARS) composed of a pair of upper and lower roll assemblies in a symmetric manner. The process offers flexibility as compared with the conventional manufacturing processes, because it does not require any complex-shaped die and loss of material by blank-holding is minimized. LARS allows flexibility of the incremental forming process and adopts the principle of bending deformation, resulting in a slight deformation in thickness. Rolls composed of line array roll sets are divided into a driving roll row and two idle roll rows. The arrayed rolls in the central lines of the upper and lower roll assemblies are motor-driven so that they deform and transfer the sheet metal using friction between the rolls and the sheet metal. The remaining rolls are idle rolls, generating bending deformation with driving rolls. Furthermore, all the rolls are movable in any direction so that they are adaptable to any size or shape of the desired three-dimensional configuration. In the process, the sheet is deformed incrementally as deformation proceeds simultaneously in rolling and transverse directions step by step. Consequently, it can be applied to the fabrication of doubly curved ship hull plates by undergoing several passes. In this work, FEM simulations are carried out for verification of the proposed incremental forming system using the chosen design parameters. Based on the results of the simulation, the relationship between the roll set configuration and the curvature of a sheet metal is determined. The process information such as the forming loads and torques acting on every roll is analyzed as important data for the design and development of the manufacturing system

Slip systems, dislocation boundaries and lattice rotations in deformed metals

DEFF Research Database (Denmark)

Winther, Grethe

2009-01-01

Metals are polycrystals and consist of grains, which are subdivided on a finer scale upon plastic deformation due to formation of dislocation boundaries. The crystallographic alignment of planar dislocation boundaries in face centred cubic metals, like aluminium and copper, deformed to moderate...... of the mechanical anisotropy of rolled sheets. The rotation of the crystallographic lattice in each grain during deformation also exhibits grain orientation dependence, originating from the slip systems. A combined analysis of dislocation boundaries and lattice rotations concludes that the two phenomena are coupled...

Alu folija kot pripomoček za toplotno zaščito podhlajenih: da ali ne: Thermal protection offered by metallized platic sheeting:

OpenAIRE

Mekjavić, Igor B.

2002-01-01

This study evaluated the thermal protection provided by suits made of metallized plastic sheeting (MPS) in a variety of environmental conditions. Four healthy male subjects participated in a total of 11 trials, simulating a range of possible outdoor scenarios. The rectal, esophageal and four skin temperatures, oxygen uptake, minute ventilation and heart rate were measured during 2 hour exposures in a climatic chamber. On the basis of these measurements, body heat storage and the rate of heat ...

Transport properties of metal-metal and metal-insulator heterostructures

Energy Technology Data Exchange (ETDEWEB)

Fadlallah Elabd, Mohamed Mostafa

2010-06-09

In this study we present results of electronic structure and transport calculations for metallic and metal-insulator interfaces, based on density functional theory and the non-equilibrium Green's function method. Starting from the electronic structure of bulk Al, Cu, Ag, and Au interfaces, we study the effects of different kinds of interface roughness on the transmission coefficient (T(E)) and the I-V characteristic. In particular, we compare prototypical interface distortions, including vacancies, metallic impurities, non-metallic impurities, interlayer, and interface alloy. We find that vacancy sites have a huge effect on transmission coefficient. The transmission coefficient of non-metallic impurity systems has the same behaviour as the transmission coefficient of vacancy system, since these systems do not contribute to the electronic states at the Fermi energy. We have also studied the transport properties of Au-MgO-Au tunnel junctions. In particular, we have investigated the influence of the thickness of the MgO interlayer, the interface termination, the interface spacing, and O vacancies. Additional interface states appear in the O-terminated configuration due to the formation of Au-O bonds. An increasing interface spacing suppresses the Au-O bonding. Enhancement of T(E) depends on the position and density of the vacancies (the number of vacancies per unit cell). (orig.)

Alkali metals and group IIA metals

International Nuclear Information System (INIS)

Fenton, D.E.

1987-01-01

This chapter on the coordination complexes of the alkali metals of group IIA starts with a historical perspective of their chemistry, from simple monodentate ligands, metal-β-diketonates to the macrocyclic polyethers which act as ligands to the alkali and akaline earth metals. Other macrocyclic ligands include quarterenes, calixarenes, porphyrins, phthalocyanines and chlorophylls. A section on the naturally occurring ionophores and carboxylic ionophores is included. (UK)

Process development study on production of uranium metal from monazite sourced crude uranium tetra-fluoride

International Nuclear Information System (INIS)

Chowdhury, S; Satpati, S.K.; Hareendran, K.N.; Roy, S.B.

2014-01-01

Development of an economic process for recovery, process flow sheet development, purification and further conversion to nuclear grade uranium metal from the crude UF 4 has been a technological challenge and the present paper, discusses the same.The developed flow-sheet is a combination of hydrometallurgical and pyrometallurgical processes. Crude UF 4 is converted to uranium di-oxide (UO 2 ) by chemical conversion route and UO 2 produced is made fluoride-free by repeated repulping, followed by solid liquid separation. Uranium di-oxide is then purified by two stages of dissolution and suitable solvent extraction methods to get uranium nitrate pure solution (UNPS). UNPS is then precipitated with air diluted ammonia in a leak tight stirred vessel under controlled operational conditions to obtain ammonium di-uranate (ADU). The ADU is then calcined and reduced to produce metal grade UO 2 followed by hydro-fluorination using anhydrous hydrofluoric acid to obtain metal grade UF 4 with ammonium oxalate insoluble (AOI) content of 4 is essential for critical upstream conversion process. Nuclear grade uranium metal ingot is finally produced by metallothermic reduction process at 650℃ in a closed vessel, called bomb reactor. In the process, metal-slag separation plays an important role for attaining metal purity as well as process yield. Technological as well economic feasibility of indigenously developed process for large scale production of uranium metal from the crude UF 4 has been established in Bhabha Atomic Research Centre (BARC), India

Performance of metallic fuels in liquid-metal fast reactors

International Nuclear Information System (INIS)

Seidel, B.R.; Walters, L.C.; Kittel, J.H.

1984-01-01

Interest in metallic fuels for liquid-metal fast reactors has come full circle. Metallic fuels are once again a viable alternative for fast reactors because reactor outlet temperature of interest to industry are well within the range where metallic fuels have demonstrated high burnup and reliable performance. In addition, metallic fuel is very tolerant of off-normal events of its high thermal conductivity and fuel behavior. Futhermore, metallic fuels lend themselves to compact and simplified reprocessing and refabrication technologies, a key feature in a new concept for deployment of fast reactors called the Integral Fast Reactor (IFR). The IFR concept is a metallic-fueled pool reactor(s) coupled to an integral-remote reprocessing and fabrication facility. The purpose of this paper is to review recent metallic fuel performance, much of which was tested and proven during the twenty years of EBR-II operation

Studies of Metal-Metal Bonded Compounds in Catalysis

Energy Technology Data Exchange (ETDEWEB)

Berry, John F. [Univ. of Wisconsin, Madison, WI (United States)

2018-01-19

The overall goals of this research are (1) to define the fundamental coordination chemistry underlying successful catalytic transformations promoted by metal-metal bonded compounds, and (2) to explore new chemical transformations that occur at metal-metal bonded sites that could lead to the discovery of new catalytic processes. Transformations of interest include metal-promoted reactions of carbene, nitrene, or nitrido species to yield products with new C–C and C–N bonds, respectively. The most promising suite of transition metal catalysts for these transformations is the set of metal-metal bonded coordination compounds of Ru and Rh of the general formula M₂(ligand)₄, where M = Ru or Rh and ligand = a monoanionic, bridging ligand such as acetate. Development of new catalysts and improvement of catalytic conditions have been stymied by a general lack of knowledge about the nature of highly reactive intermediates in these reactions, the knowledge that is to be supplied by this work. Our three specific objectives for this year have been (A) to trap, isolate, and characterize new reactive intermediates of general relevance to catalysis, (B) to explore the electronic structure and reactivity of these unusual species, and how these two properties are interrelated, and (C) to use our obtained mechanistic knowledge to design new catalysts with a focus on Earth-abundant first-row transition metal compounds.

An experimental investigation of glare and restructured fiber metal laminates

Science.gov (United States)

Benedict, Adelina Vanessa

Fiber Metal Laminates (FMLs) are a group of materials fabricated by bonding glass/epoxy layers within metal layers. This class of materials can provide good mechanical properties, as well as weight savings. An FML known as Glass Laminate Aluminum Reinforced Epoxy (GLARE) was studied. An experimental investigation comprising of microscopy and tensile testing was carried out using different grades of GLARE. Microscopy revealed the construction details of GLARE, while tensile testing provided means of measuring and analyzing its stress-strain responses. Next, different metal surface pretreatment methods were explored. These included sandblasting, Phosphoric Acid Anodizing (PAA), and AC-130 Sol-Gel treatment. Woven S-2 glass, an epoxy adhesive, and aluminum alloy sheet metal were used to fabricate restructured FMLs using time and cost effective procedures. Additional microscopy and tensile testing allowed for comparisons with GLARE and aircraft grade aluminum alloys. The restructured FMLs showed similar behaviors to GLARE with potential significant improvements in fabrication efficiency.

Investigation on cold fusion phenomena using gas-metal loading experiments

International Nuclear Information System (INIS)

Lanza, F.; Bertolini, G.; Vocino, V.; Parnisari, E.; Ronsecco, C.

1992-01-01

Previous experiments have shown that tritium is produced in deuterated titanium. The data obtained are highly scattered and non reproducible. In order to try to define better the phenomenon a series of tests have been performed using various metals and alloys and different deuterating conditions. Sheets and shavings of titanium, zirconium, hafnium, tantalum, zircaloy 2 and Ti-Zr 5O% alloy have been tested. The tritium production is obtained as a difference of the tritium content in the deuterated metal and the initial content of tritium in the deuterium gas. The amount of tritium produced is low and reproducibility is rather poor. A statistical analysis shows that significant differences are obtained varying the type of metal used. In general the tritium production increases with the atomic number of the metal. Moreover significantly higher productions of tritium have been obtained using materials of technical purity as tantalum, zircaloy 2 and Ti-Zr alloy

Robust cladding light stripper for high-power fiber lasers using soft metals.

Science.gov (United States)

Babazadeh, Amin; Nasirabad, Reza Rezaei; Norouzey, Ahmad; Hejaz, Kamran; Poozesh, Reza; Heidariazar, Amir; Golshan, Ali Hamedani; Roohforouz, Ali; Jafari, S Naser Tabatabaei; Lafouti, Majid

2014-04-20

In this paper we present a novel method to reliably strip the unwanted cladding light in high-power fiber lasers. Soft metals are utilized to fabricate a high-power cladding light stripper (CLS). The capability of indium (In), aluminum (Al), tin (Sn), and gold (Au) in extracting unwanted cladding light is examined. The experiments show that these metals have the right features for stripping the unwanted light out of the cladding. We also find that the metal-cladding contact area is of great importance because it determines the attenuation and the thermal load on the CLS. These metals are examined in different forms to optimize the contact area to have the highest possible attenuation and avoid localized heating. The results show that sheets of indium are very effective in stripping unwanted cladding light.

New metals

International Nuclear Information System (INIS)

Bergqvist, U.

1983-12-01

The aim of this report is to estimate the exposure to various metals and metal compounds and discuss the available information of the possible toxic effects of these metals and compounds. In the first section, some metals are defined as those with either a large or a fast increasing exposure to living organisms. The available information on toxicity is discussed in the second section. In the third section interesting metals are defined as compounds having a large exposure and an apparent insufficient knowledge of their possible toxic effects. Comments on each of these metals are also to be found in the third section. (G.B.)

Breast milk metal ion levels in a young and active patient with a metal-on-metal hip prosthesis.

Science.gov (United States)

Nelis, Raymond; de Waal Malefijt, Jan; Gosens, Taco

2013-01-01

Metal-on-metal resurfacing arthroplasty of the hip has been used increasingly over the last 10 years in younger active patients. The dissolution of the metal wear particles results in measurable increases in cobalt and chromium ions in the serum and urine of patients with a metal-on-metal bearing. We measured the cobalt, chromium, and molybdenum ion levels in urine; serum; and breast milk in a young and active patient with a metal-on-metal hip prosthesis after a pathologic fracture of the femoral neck. Metal-on-metal hip prosthesis leads to increasing levels of molybdenum in breast milk in the short-term follow-up. There are no increasing levels of chromium and cobalt ions in breast milk. Besides the already known elevated concentrations in serum of chromium and cobalt after implantation of a metal-on-metal hip prosthesis, we found no increasing levels of chromium and cobalt in urine. Copyright © 2013 Elsevier Inc. All rights reserved.

Combined-load buckling behavior of metal-matrix composite sandwich panels under different thermal environments

Science.gov (United States)

Ko, William L.; Jackson, Raymond H.

1991-01-01

Combined compressive and shear buckling analysis was conducted on flat rectangular sandwich panels with the consideration of transverse shear effects of the core. The sandwich panel is fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that the square panel has the highest combined load buckling strength, and that the buckling strength decreases sharply with the increases of both temperature and panel aspect ratio. The effect of layup (fiber orientation) on the buckling strength of the panels was studied in detail. The metal matrix composite sandwich panel was much more efficient than the sandwich panel with nonreinforced face sheets and had the same specific weight.

Understanding how cells allocate metals using metal sensors and metallochaperones.

Science.gov (United States)

Tottey, Stephen; Harvie, Duncan R; Robinson, Nigel J

2005-10-01

Each metalloprotein must somehow acquire the correct metal. We review the insights into metal specificity in cells provided by studies of ArsR-SmtB DNA binding, metal-responsive transcriptional repressors, and a bacterial copper chaperone. Cyanobacteria are the one bacterial group that have known enzymatic demand for cytoplasmic copper import. The copper chaperone and ATPases that supply cyanobacterial plastocyanin and cytochrome oxidase are reviewed, along with related ATPases for cobalt and zinc. These studies highlight the contributions of protein-protein interactions to metal speciation. Metal sensors and metallochaperones, along with metal transporters and metal-storage proteins, act in concert not only to supply the correct metals but also to withhold the wrong ones.

Structural Differentiation between Layered Single (Ni) and Double Metal Hydroxides (Ni–Al LDHs) Using Wavelet Transformation

Energy Technology Data Exchange (ETDEWEB)

Siebecker, Matthew G. [University of Delaware, Delaware Environmental Institute; Sparks, Donald L. [University of Delaware, Delaware Environmental Institute

2017-09-07

Layered double hydroxides (LDHs) are anionic clays important in disciplines such as environmental chemistry, geochemistry, and materials science. Developments in signal processing of extended X-ray absorption fine structure (EXAFS) data, such as wavelet transformation (WT), have been used to identify transition metals and Al present in the hydroxide sheets of LDHs. The WT plots of LDHs should be distinct from those of isostructural single metal hydroxides. However, no direct comparison of these minerals appears in the literature using WT. This work systematically analyzes a suite of Ni-rich mineral standards, including Ni–Al LDHs, single metal Ni hydroxides, and Ni-rich silicates using WT. The results illustrate that the WT plots for α-Ni(OH)2 and Ni–Al LDHs are often indistinguishable from each other, with similar two-component plots for the different mineral types. This demonstrates that the WT of the first metal shell often cannot be used to differentiate an LDH from a single metal hydroxide. Interlayer anions adsorbed to the hydroxide sheet of α-Ni(OH)2 affect the EXAFS spectra and are not visible in the FT but are clearly resolved and discrete in the WT.

Speciation in Metal Toxicity and Metal-Based Therapeutics

Directory of Open Access Journals (Sweden)

Douglas M. Templeton

2015-04-01

Full Text Available Metallic elements, ions and compounds produce varying degrees of toxicity in organisms with which they come into contact. Metal speciation is critical to understanding these adverse effects; the adjectives “heavy” and “toxic” are not helpful in describing the biological properties of individual elements, but detailed chemical structures are. As a broad generalization, the metallic form of an element is inert, and the ionic salts are the species that show more significant bioavailability. Yet the salts and other chelates of a metal ion can give rise to quite different toxicities, as exemplified by a range of carcinogenic potential for various nickel species. Another important distinction comes when a metallic element is organified, increasing its lipophilicity and hence its ability to penetrate the blood brain barrier, as is seen, for example, with organic mercury and tin species. Some metallic elements, such as gold and platinum, are themselves useful therapeutic agents in some forms, while other species of the same element can be toxic, thus focusing attention on species interconversions in evaluating metal-based drugs. The therapeutic use of metal-chelating agents introduces new species of the target metal in vivo, and this can affect not only its desired detoxification, but also introduce a potential for further mechanisms of toxicity. Examples of therapeutic iron chelator species are discussed in this context, as well as the more recent aspects of development of chelation therapy for uranium exposure.

Nanotoxicity: the toxicity research progress of metal and metal-containing nanoparticles.

Science.gov (United States)

Ding, Lingling; Liu, Zhidong; Aggrey, Mike Okweesi; Li, Chunhua; Chen, Jing; Tong, Ling

2015-01-01

Along with the exuberant development of nanotechnology, a large number of nanoformulations or non materials are successfully applied in the clinics, biomedicine, cosmetics and industry. Despite some unique advantages of nanoformulations, there exist potentially worrying toxic effects, particularly those related to metal and metal-containing nanoparticles (NPs). Although various researches have been conducted to assess the metallic and metal-containing nanoparticles toxic effects, only little is known about the toxicity expressive types and evaluation, reasons and mechanisms, influencing factors and research methods of metal and metal-containing nanotoxicity. Therefore, it is of importance to acquire a better understanding of metal and metal-containing nanoparticles toxicity for medical application. This review presents a summary on the metal and metal-containing nanoparticles toxicity research progress consulting relevant literature.

Heavy metals

OpenAIRE

Adriano, Domy; VANGRONSVELD, Jaco; Bolan, N.S.; Wenzel, W.W.

2005-01-01

- Sources of Metals in the Environment - Environmental Contamination - Retention and Dynamics of Metals in Soils - Adsorption - Complexation - Precipitation - Bioavailability–Natural Attenuation Interactions - Biological Response to Metals - Soil Remediation

The effect of filler metal thickness on residual stress and creep for stainless-steel plate-fin structure

Energy Technology Data Exchange (ETDEWEB)

Jiang Wenchun [School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 210009 (China)], E-mail: jiangwenchun@126.com; Gong Jianming; Chen Hu; Tu, S.T. [School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 210009 (China)

2008-08-15

Stainless-steel plate-fin heat exchanger (PFHE) has been used as a high-temperature recuperator in microturbine for its excellent qualities in compact structure, high-temperature and pressure resistance. Plate-fin structure, as the core of PFHE, is fabricated by vacuum brazing. The main component fins and the parting sheets are joined by fusion of a brazing alloy cladded to the surface of parting sheets. Owing to the material mismatching between the filler metal and the base metal, residual stresses can arise and decrease the structure strength greatly. The recuperator serves at high temperature and the creep would happen. The thickness of the filler metal plays an important role in the joint strength. Hence this paper presented a finite element (FE) analysis of the brazed residual stresses and creep for a counterflow stainless-steel plate-fin structure. The effect of the filler metal thickness on residual stress and creep was investigated, which provides a reference for strength design.

Metal transformation as a strategy for bacterial detoxification of heavy metals.

Science.gov (United States)

Essa, Ashraf M M; Al Abboud, Mohamed A; Khatib, Sayeed I

2018-01-01

Microorganisms can modify the chemical and physical characters of metals leading to an alteration in their speciation, mobility, and toxicity. Aqueous heavy metals solutions (Hg, Cd, Pb, Ag, Cu, and Zn) were treated with the volatile metabolic products (VMPs) of Escherichia coli Z3 for 24 h using aerobic bioreactor. The effect of the metals treated with VMPs in comparison to the untreated metals on the growth of E. coli S1 and Staphylococcus aureus S2 (local isolates) was examined. Moreover, the toxic properties of the treated and untreated metals were monitored using minimum inhibitory concentration assay. A marked reduction of the treated metals toxicity was recorded in comparison to the untreated metals. Scanning electron microscopy and energy dispersive X-ray analysis revealed the formation of metal particles in the treated metal solutions. In addition to heavy metals at variable ratios, these particles consisted of carbon, oxygen, sulfur, nitrogen elements. The inhibition of metal toxicity was attributed to the existence of ammonia, hydrogen sulfide, and carbon dioxide in the VMPs of E. coli Z3 culture that might responsible for the transformation of soluble metal ions into metal complexes. This study clarified the capability of E. coli Z3 for indirect detoxification of heavy metals via the immobilization of metal ions into biologically unavailable species. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light Metal Decorated Graphdiyne (GDY) Nanosheets for Reversible Hydrogen Storage.

Science.gov (United States)

Panigrahi, P; Dhinakaran, A K; Naqvi, S R; Rao, Sankara Gollu; Ahuja, Rajeev; Hussain, Tanveer

2018-05-29

The sensitive nature of molecular hydrogen (H2) interaction with the surfaces of pristine and functionalized nanostructures, especially two-dimensional materials (2D) has been a subject of debate for a while now. An accurate approximation of H2 adsorption mechanism has a vital significance for the specific fields like H2 storage applications. Owing to the importance of this issue, we have performed a comprehensive DFT study by means of several different approximations to investigate the structural, electronic, charge transfer and energy storage properties of pristine and functionalized graphdiyne (GDY) nano sheets. The dopants considered here include light-metals Li, Na, K, Ca, Sc and Ti, which make uniform distribution over GDY even at high doping concentration due to their strong binding and charge transfer mechanism. Upon 11% of metal functionalization, GDY changes into metallic state from being a small band gap semiconductor. Such situations turn the dopants to a partial positive state, which is favorable for adsorption of H2 molecules. The adsorption mechanism of H2 on GDY has been studied and compared by different methods like GGA, vdW-DF and DFT-D3 functionals. It has been established that each functionalized systems anchor multiple H2 molecules with adsorption energies that falls into a suitable range regardless of the functional used for approximations. A significantly high H2 storage capacity would guarantee that light metal-doped GDY nano sheets could serve the purpose of an efficient and reversible H2 storage material. © 2018 IOP Publishing Ltd.

Bacterial metal resistance genes and metal bioavailability in contaminated sediments

International Nuclear Information System (INIS)

Roosa, Stéphanie; Wattiez, Ruddy; Prygiel, Emilie; Lesven, Ludovic; Billon, Gabriel; Gillan, David C.

2014-01-01

In bacteria a metal may be defined as bioavailable if it crosses the cytoplasmic membrane to reach the cytoplasm. Once inside the cell, specific metal resistance systems may be triggered. In this research, specific metal resistance genes were used to estimate metal bioavailability in sediment microbial communities. Gene levels were measured by quantitative PCR and correlated to metals in sediments using five different protocols to estimate dissolved, particle-adsorbed and occluded metals. The best correlations were obtained with czcA (a Cd/Zn/Co efflux pump) and Cd/Zn adsorbed or occluded in particles. Only adsorbed Co was correlated to czcA levels. We concluded that the measurement of czcA gene levels by quantitative PCR is a promising tool which may complement the classical approaches used to estimate Cd/Zn/Co bioavailability in sediment compartments. - Highlights: • Metal resistance genes were used to estimate metal bioavailability in sediments. • Gene levels were correlated to metals using 5 different metal extraction protocols. • CzcA gene levels determined by quantitative PCR is a promising tool for Cd/Zn/Co. - Capsule Bacterial czcA is a potential biomarker of Cd, Zn and Co bioavailability in aquatic sediments as shown by quantitative PCR and sequential metal extraction

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.

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.

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.

Development and Testing of Tailored Tool Surfaces for Sheet Metal Forming

DEFF Research Database (Denmark)

Sulaiman, Mohd Hafis Bin

MPa. The above mentioned simple experimental procedure for determining lubricant bulk modulus gives a first rough estimate, and it is supplemented by a more advanced laboratory test based on a newly designed equipment. The lubricant compressibility experiment with a direct pressure measurement inside...... to achieve this purpose. A simple laboratory test consisting of upsetting a specially designed metal cylinder with a lubricant reservoir together with elasto-plastic, numerical modelling of the metal cylinder is carried out in order to determine the bulk modulus at low pressure regimes of approximately 100...... for the manufacturing. The SRT tools were manufactured with longitudinal, shallow pocket geometries oriented perpendicular to the sliding direction. The pockets have small angles to the workpiece surface and varying distance. The experiments show an optimum distance between the pockets to exist that creates a table...

MetalS2: a tool for the structural alignment of minimal functional sites in metal-binding proteins and nucleic acids.

Science.gov (United States)

Andreini, Claudia; Cavallaro, Gabriele; Rosato, Antonio; Valasatava, Yana

2013-11-25

We developed a new software tool, MetalS(2), for the structural alignment of Minimal Functional Sites (MFSs) in metal-binding biological macromolecules. MFSs are 3D templates that describe the local environment around the metal(s) independently of the larger context of the macromolecular structure. Such local environment has a determinant role in tuning the chemical reactivity of the metal, ultimately contributing to the functional properties of the whole system. On our example data sets, MetalS(2) unveiled structural similarities that other programs for protein structure comparison do not consistently point out and overall identified a larger number of structurally similar MFSs. MetalS(2) supports the comparison of MFSs harboring different metals and/or with different nuclearity and is available both as a stand-alone program and a Web tool ( http://metalweb.cerm.unifi.it/tools/metals2/).

Alkali metal-refractory metal biphase electrode for AMTEC

Science.gov (United States)

Williams, Roger M. (Inventor); Bankston, Clyde P. (Inventor); Cole, Terry (Inventor); Khanna, Satish K. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Wheeler, Bob L. (Inventor)

1989-01-01

An electrode having increased output with slower degradation is formed of a film applied to a beta-alumina solid electrolyte (BASE). The film comprises a refractory first metal M.sup.1 such as a platinum group metal, suitably platinum or rhodium, capable of forming a liquid or a strong surface adsorption phase with sodium at the operating temperature of an alkali metal thermoelectric converter (AMTEC) and a second refractory metal insoluble in sodium or the NaM.sup.1 liquid phase such as a Group IVB, VB or VIB metal, suitably tungsten, molybdenum, tantalum or niobium. The liquid phase or surface film provides fast transport through the electrode while the insoluble refractory metal provides a structural matrix for the electrode during operation. A trilayer structure that is stable and not subject to deadhesion comprises a first, thin layer of tungsten, an intermediate co-deposited layer of tungsten-platinum and a thin surface layer of platinum.

Plasma methods for metals recovery from metal-containing waste.

Science.gov (United States)

Changming, Du; Chao, Shang; Gong, Xiangjie; Ting, Wang; Xiange, Wei

2018-04-27

Metal-containing waste, a kind of new wastes, has a great potential for recycling and is also difficult to deal with. Many countries pay more and more attention to develop the metal recovery process and equipment of this kind of waste as raw material, so as to solve the environmental pollution and comprehensively utilize the discarded metal resources. Plasma processing is an efficient and environmentally friendly way for metal-containing waste. This review mainly discuss various metal-containing waste types, such as printed circuit boards (PCBs), red mud, galvanic sludge, Zircon, aluminium dross and incinerated ash, and the corresponding plasma methods, which include DC extended transferred arc plasma reactor, DC non-transferred arc plasma torch, RF thermal plasma reactor and argon and argon-hydrogen plasma jets. In addition, the plasma arc melting technology has a better purification effect on the extraction of useful metals from metal-containing wastes, a great capacity of volume reduction of waste materials, and a low leaching toxicity of solid slag, which can also be used to deal with all kinds of metal waste materials, having a wide range of applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Half-Metallic Ferromagnetism and Stability of Transition Metal Pnictides and Chalcogenides

Science.gov (United States)

Liu, Bang-Gui

It is highly desirable to explore robust half-metallic ferromagnetic materials compatible with important semiconductors for spintronic applications. A state-of-the-art full potential augmented plane wave method within the densityfunctional theory is reliable enough for this purpose. In this chapter we review theoretical research on half-metallic ferromagnetism and structural stability of transition metal pnictides and chalcogenides. We show that some zincblende transition metal pnictides are half-metallic and the half-metallic gap can be fairly wide, which is consistent with experiment. Systematic calculations reveal that zincblende phases of CrTe, CrSe, and VTe are excellent half-metallic ferromagnets. These three materials have wide half-metallic gaps, are low in total energy with respect to the corresponding ground-state phases, and, importantly, are structurally stable. Halfmetallic ferromagnetism is also found in wurtzite transition metal pnictides and chalcogenides and in transition-metal doped semiconductors as well as deformed structures. Some of these half-metallic materials could be grown epitaxially in the form of ultrathin .lms or layers suitable for real spintronic applications.

Studies on the preparation of thorium metal sponge from thorium oxalate

International Nuclear Information System (INIS)

Vijay, P.L.; Sehra, J.C.; Sundaram, C.V.; Gurumurthy, K.R.; Raghavan, R.V.

1978-01-01

The results of investigations carried out on the production of high purity thorium metal sponge, starting with thorium oxalate are presented. The flow sheet includes chlorination of thorium oxalate, purification of raw thorium tetrachloride, magnesium reduction of anhydrous thorium tetrachloride, slag metal separation, vacuum distillation for removal of residual MgCl 2 and excess magnesium, and consolidation of the metal sponge. Studies have been carried out to investigate the optimum chlorination efficiency and chlorine utilization attainable using different chlorinating agents, and to compare the quality of the sponge obtained with single and double distilled chloride. The overall process efficiency under optimum conditions was 81%. The thorium metal button, prepared from the sponge by arc-melting, analysed : O 2 - 847, N 2 - 20, C - 179, Mg - 100, Fe - 49, Ni<50, Al - 11, Cr - 7 (expressed in parts per million parts of thorium). The button could be further purified by electron beam melting to improve its ductility. (author)

Research on Al-alloy sheet forming formability during warm/hot sheet hydroforming based on elliptical warm bulging test

Science.gov (United States)

Cai, Gaoshen; Wu, Chuanyu; Gao, Zepu; Lang, Lihui; Alexandrov, Sergei

2018-05-01

An elliptical warm/hot sheet bulging test under different temperatures and pressure rates was carried out to predict Al-alloy sheet forming limit during warm/hot sheet hydroforming. Using relevant formulas of ultimate strain to calculate and dispose experimental data, forming limit curves (FLCS) in tension-tension state of strain (TTSS) area are obtained. Combining with the basic experimental data obtained by uniaxial tensile test under the equivalent condition with bulging test, complete forming limit diagrams (FLDS) of Al-alloy are established. Using a quadratic polynomial curve fitting method, material constants of fitting function are calculated and a prediction model equation for sheet metal forming limit is established, by which the corresponding forming limit curves in TTSS area can be obtained. The bulging test and fitting results indicated that the sheet metal FLCS obtained were very accurate. Also, the model equation can be used to instruct warm/hot sheet bulging test.

Recycling of Metals

DEFF Research Database (Denmark)

Damgaard, Anders; Christensen, Thomas Højlund

2011-01-01

Metals like iron and aluminium are produced from mineral ore and used for a range of products, some of which have very short lifetimes and thus constitute a major fraction of municipal waste. Packaging in terms of cans, foils and containers are products with a short lifetime. Other products like...... appliances, vehicles and buildings, containing iron and aluminium metals, have long lifetimes before they end up in the waste stream. The recycling of production waste and postconsumer metals has a long history in the metal industry. Some metal smelters are today entirely based on scarp metals. This chapter...... describes briefly how iron and aluminium are produced and how scrap metal is recycled in the industry. Quality requirements and use of recycled products are discussed, as are the resource and environmental issues of metal recycling. Copper and other metals are also found in waste but in much smaller...

Surface/structure functionalization of copper-based catalysts by metal-support and/or metal-metal interactions

Science.gov (United States)

Konsolakis, Michalis; Ioakeimidis, Zisis

2014-11-01

Cu-based catalysts have recently attracted great attention both in catalysis and electro-catalysis fields due to their excellent catalytic performance and low cost. Given that their performance is determined, to a great extent, by Cu sites local environment, considerable efforts have been devoted on the strategic modifications of the electronic and structural properties of Cu sites. In this regard, the feasibility of tuning the local structure of Cu entities by means of metal-support or metal-metal interactions is investigated. More specifically, the physicochemical properties of Cu entities are modified by employing: (i) different oxides (CeO2, La2O3, Sm2O3), or (ii) ceria-based mixed oxides (Ce1-xSmxOδ) as supporting carriers, and (iii) a second metal (Cobalt) adjacent to Cu (bimetallic Cu-Co/CeO2). A characterization study, involving BET, XRD, TPR, and XPS, reveal that significant modifications on structural, redox and electronic properties of Cu sites can be induced by adopting either different oxide carriers or bimetallic complexes. Fundamental insights into the tuning of Cu local environment by metal-support or metal-metal interactions are provided, paving the way for real-life industrial applications.

Magnetic susceptibility of 244Cm metal and 249Cf metal

International Nuclear Information System (INIS)

Fujita, D.K.; Parsons, T.C.; Edelstein, N.; Noe, M.; Peterson, J.R.

1975-07-01

The first magnetic susceptibility measurements made on the expanded fcc phase of 249 Cf metal are reported. Further measurements are needed on other Cf metal phases. Another measurement of the magnetic susceptibility of 244 Cm metal in a limited temperature range has been reported. The result does not agree with previously reported values. Further work is continuing on the synthesis of 244 Cm metal and 248 Cm metal and magnetic measurements on these samples. (auth)

Catalytic production of metal carbonyls from metal oxides

Science.gov (United States)

Sapienza, Richard S.; Slegeir, William A.; Foran, Michael T.

1984-01-01

This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150.degree.-260.degree. C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO.sub.4 and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect.

Process to separate alkali metal salts from alkali metal reacted hydrocarbons

Energy Technology Data Exchange (ETDEWEB)

Gordon, John Howard; Alvare, Javier; Larsen, Dennis; Killpack, Jeff

2017-06-27

A process to facilitate gravimetric separation of alkali metal salts, such as alkali metal sulfides and polysulfides, from alkali metal reacted hydrocarbons. The disclosed process is part of a method of upgrading a hydrocarbon feedstock by removing heteroatoms and/or one or more heavy metals from the hydrocarbon feedstock composition. This method reacts the oil feedstock with an alkali metal and an upgradant hydrocarbon. The alkali metal reacts with a portion of the heteroatoms and/or one or more heavy metals to form an inorganic phase containing alkali metal salts and reduced heavy metals, and an upgraded hydrocarbon feedstock. The inorganic phase may be gravimetrically separated from the upgraded hydrocarbon feedstock after mixing at a temperature between about 350.degree. C. to 400.degree. C. for a time period between about 15 minutes and 2 hours.

Immunoglobulin classes, metal binding proteins, and trace metals in ...

African Journals Online (AJOL)

, IgA and IgM), metal binding proteins (Transferrin, Caeruloplasmin, Alpha-2- Macroglobulin and Haptoglobin) and nutritionally essential trace metals/heavy metals (Zn, Fe, Se, Cu, Mg, Cd and Pb) in Nigerian cassava processors using single ...

Monitoring concept for structural integration of PZT-fiber arrays in metal sheets: a numerical and experimental study

Science.gov (United States)

Drossel, Welf-Guntram; Schubert, Andreas; Putz, Matthias; Koriath, Hans-Joachim; Wittstock, Volker; Hensel, Sebastian; Pierer, Alexander; Müller, Benedikt; Schmidt, Marek

2018-01-01

The technique joining by forming allows the structural integration of piezoceramic fibers into locally microstructured metal sheets without any elastic interlayers. A high-volume production of the joining partners causes in statistical deviations from the nominal dimensions. A numerical simulation on geometric process sensitivity shows that the deviations have a high significant influence on the resulting fiber stresses after the joining by forming operation and demonstrate the necessity of a monitoring concept. On this basis, the electromechanical behavior of piezoceramic array transducers is investigated experimentally before, during and after the joining process. The piezoceramic array transducer consists of an arrangement of five electrical interconnected piezoceramic fibers. The findings show that the impedance spectrum depends on the fiber stresses and can be used for in-process monitoring during the joining process. Based on the impedance values the preload state of the interconnected piezoceramic fibers can be specifically controlled and a fiber overload.

Plasma metallization

International Nuclear Information System (INIS)

Crowther, J.M.

1997-09-01

Many methods are currently used for the production of thin metal films. However, all of these have drawbacks associated with them, for example the need for UHV conditions, high temperatures, exotic metal precursors, or the inability to coat complex shaped objects. Reduction of supported metal salts by non-isothermal plasma treatment does not suffer from these drawbacks. In order to produce and analyse metal films before they become contaminated, a plasma chamber which could be attached directly to a UHV chamber with XPS capability was designed and built. This allowed plasma treatment of supported metal salts and surface analysis by XPS to be performed without exposure of the metal film to the atmosphere. Non-equilibrium plasma treatment of Nylon 66 supported gold(lll) chloride using hydrogen as the feed gas resulted in a 95% pure gold film, the remaining 5% of the film being carbon. If argon or helium were used as the feed gases during plasma treatment the resultant gold films were 100% pure. Some degree of surface contamination of the films due to plasma treatment was observed but was easily removed by argon ion cleaning. Hydrogen plasma reduction of glass supported silver(l) nitrate and palladium(ll) acetate films reveals that this metallization technique is applicable to a wide variety of metal salts and supports, and has also shown the ability of plasma reduction to retain the complex 'fern-like' structures seen for spin coated silver(l) nitrate layers. Some metal salts are susceptible to decomposition by X-rays. The reduction of Nylon 66 supported gold(lll) chloride films by soft X-rays to produce nanoscopic gold particles has been studied. The spontaneous reduction of these X-ray irradiated support gold(lll) chloride films on exposure to the atmosphere to produce gold rich metallic films has also been reported. (author)

Plan for metal barrier selection and testing for NNWSI

International Nuclear Information System (INIS)

Halsey, W.G.; McCright, R.D.

1987-12-01

The Department of Energy's Nevada Nuclear Waste Storage Investigations (NNWSI) Project is evaluating a site at Yucca Mountain in Nevada as a geological repository for the storage of high-level nuclear waste. The Nuclear Waste Management Projects (NWMP) at Lawrence Livermore National Laboratory (LLNL) has the responsibility for design, testing, and performance analysis of the NNWSI waste packages. One portion of this work is the selection and testing of the material for container construction. The anticipated container design is for this material to be a corrosion resistant metal called the metal barrier. This document is the publication version of the Scientific Investigation Plan (SIP) for the Metal Barrier Selection and Testing Task. The SIP serves as a formal planning document for the investigation and is used to assign quality assurance levels to the activities of the task. This document is an informal version for information distribution and has the sections on ''Schedule and Milestones'' and the ''Quality Assurance Level Assignment Sheets'' removed

Fabrication of micro metallic valve and pump

Science.gov (United States)

Yang, Ming; Kabasawa, Yasunari; Ito, Kuniyoshi

2010-03-01

Fabrication of micro devices by using micro metal forming was proposed by the authors. We developed a desktop servo-press machine with precise tooling system. Precise press forming processes including micro forging and micro joining has been carried out in a progressive die. In this study, micro metallic valve and pump were fabricated by using the precise press forming. The components are made of sheet metals, and assembled in to a unit in the progressive die. A micro check-valve with a diameter of 3mm and a length of 3.2mm was fabricated, and the property of flow resistance was evaluated. The results show that the check valve has high property of leakage proof. Since the valve is a unit parts with dimensions of several millimeters, it has advantage to be adapted to various pump design. Here, two kinds of micro pumps with the check-valves were fabricated. One is diaphragm pump actuated by vibration of the diaphragm, and another is tube-shaped pump actuated by resonation. The flow quantities of the pumps were evaluated and the results show that both of the pumps have high pumping performance.

‘… a metal conducts and a non-metal doesn't’

Science.gov (United States)

Edwards, P. P.; Lodge, M. T. J.; Hensel, F.; Redmer, R.

2010-01-01

In a letter to one of the authors, Sir Nevill Mott, then in his tenth decade, highlighted the fact that the statement ‘… a metal conducts, and a non-metal doesn’t’ can be true only at the absolute zero of temperature, T=0 K. But, of course, experimental studies of metals, non-metals and, indeed, the electronic and thermodynamic transition between these canonical states of matter must always occur above T=0 K, and, in many important cases, for temperatures far above the absolute zero. Here, we review the issues—theoretical and experimental—attendant on studies of the metal to non-metal transition in doped semiconductors at temperatures close to absolute zero (T=0.03 K) and fluid chemical elements at temperatures far above absolute zero (T>1000 K). We attempt to illustrate Mott’s insights for delving into such complex phenomena and experimental systems, finding intuitively the dominant features of the science, and developing a coherent picture of the different competing electronic processes. A particular emphasis is placed on the idea of a ‘Mott metal to non-metal transition’ in the nominally metallic chemical elements rubidium, caesium and mercury, and the converse metallization transition in the nominally non-metal elements hydrogen and oxygen. We also review major innovations by D. A. Goldhammer (Goldhammer 1913 Dispersion und absorption des lichtes) and K. F. Herzfeld (Herzfeld 1927 Phys. Rev. 29, 701–705. (doi:10.1103/PhysRev.29.701)) in a pre-quantum theory description of the metal–non-metal transition, which emphasize the pivotal role of atomic properties in dictating the metallic or non-metallic status of the chemical elements of the periodic table under ambient and extreme conditions; a link with Pauling’s ‘metallic orbital’ is also established here. PMID:20123742

The Production of Uranium Metal by Metal Hydrides Incorporated

Energy Technology Data Exchange (ETDEWEB)

Alexander, P. P.

1943-01-01

Metal Hydrides Incorporated was a pioneer in the production of uranium metal on a commercial scale and supplied it to all the laboratories interested in the original research, before other methods for its production were developed. Metal Hydrides Inc. supplied the major part of the metal for the construction of the first experimental pile which, on December 2, 1942, demonstrated the feasibility of the self-sustaining chain reaction and the release of atomic energy.

Fatigue and fracture of fibre metal laminates

CERN Document Server

Alderliesten, René

2017-01-01

This book contributes to the field of hybrid technology, describing the current state of knowledge concerning the hybrid material concept of laminated metallic and composite sheets for primary aeronautical structural applications. It is the only book to date on fatigue and fracture of fibre metal laminates (FMLs). The first section of the book provides a general background of the FML technology, highlighting the major FML types developed and studied over the past decades in conjunction with an overview of industrial developments based on filed patents. In turn, the second section discusses the mechanical response to quasi-static loading, together with the fracture phenomena during quasi-static and cyclic loading. To consider the durability aspects related to strength justification and certification of primary aircraft structures, the third section discusses thermal aspects related to FMLs and their mechanical response to various environmental and acoustic conditions.

Utility industry evaluation of the metal fuel facility and metal fuel performance for liquid metal reactors

International Nuclear Information System (INIS)

Burstein, S.; Gibbons, J.P.; High, M.D.; O'Boyle, D.R.; Pickens, T.A.; Pilmer, D.F.; Tomonto, J.R.; Weinberg, C.J.

1990-02-01

A team of utility industry representatives evaluated the liquid metal reactor metal fuel process and facility conceptual design being developed by Argonne National Laboratory (ANL) under Department of Energy sponsorship. The utility team concluded that a highly competent ANL team was making impressive progress in developing high performance advanced metal fuel and an economic processing and fabrication technology. The utility team concluded that the potential benefits of advanced metal fuel justified the development program, but that, at this early stage, there are considerable uncertainties in predicting the net overall economic benefit of metal fuel. Specific comments and recommendations are provided as a contribution towards enhancing the development program. 6 refs

Thickness profile measuring device for rolling metal bands or sheets

International Nuclear Information System (INIS)

Campas, J.J.; Terreaux, S.

1995-01-01

Previous radiometric thickness gages were affected by insufficient water proofing and limited cooling performances for the detection subsystem (in general specially designed photodiodes). This resulted in poor reliability and life expectancy, in particular when heavy humidity and constant radiative heat are present as for hot rolling in the metal industry. This new gage design brings enhanced performances for these two factors. (D.L.). 4 refs., 3 figs

Predicting Metal Speciation & Bioavailability via Estimation of Metal-Organic Thermodynamic Properties

Science.gov (United States)

Prasad, A.; Howells, A. E.; Shock, E.

2017-12-01

The biological fate of any metal depends on its chemical form in the environment. Arsenic for example, is extremely toxic in the form of inorganic As+3 but completely benign in the organic form of arsenobetaine. Thus, given an exhaustive set of reactions and their equilibrium constants (logK), the bioavailability of any metal can be obtained for blood plasma, hydrothermal fluids or any system of interest. While many data exist for metal-inorganic ligands, logK data covering the temperature range of life for metal-organic complexes are sparse. Hence, we decided to estimate metal-organic logK values from correlations with the commonly available values of ligand pKa. Metal ion specific correlations were made with ligands classified according to their electron donor atoms, denticity and other chemical factors. While this approach has been employed before (Carbonaro et al. 2007, GCA 71, 3958-3968), new correlations were developed that provide estimates even when no metal-organic logK is available. In addition, we have used the same methods to make estimates of metal-organic entropy of association (ΔaS), which can provide logK for any temperature of biological relevance. Our current correlations employ logK and ΔaS data from 30 metal ions (like the biologically relevant Fe+3 & Zn+2) and 74 ligands (like formate and ethylenediamine), which can be expanded to estimate the metal-ligand reaction properties for these 30 metal ions with a possibly limitless number of ligands that may belong to our categories of ligands. With the help of such data, copper speciation was obtained for a defined growth medium for methanotrophs employed by Morton et al. (2000, AEM 66, 1730-1733) that agrees with experimental measurements showing that the free metal ion may not be the bioavailable form in all conditions. These results encourage us to keep filling the gaps in metal-organic logK data and continue finding relationships between biological responses (like metal-accumulation ratios

Cohesive traction–separation laws for tearing of ductile metal plates

DEFF Research Database (Denmark)

Nielsen, Kim Lau; Hutchinson, John W.

2012-01-01

The failure process ahead of a mode I crack advancing in a ductile thin metal plate or sheet produces plastic dissipation through a sequence of deformation steps that include necking well ahead of the crack tip and shear localization followed by a slant fracture in the necked region somewhat clos...

The effects of high temperature and fiber diameter on the quasi static compressive behavior of metal fiber sintered sheets

Energy Technology Data Exchange (ETDEWEB)

Song, Weidong, E-mail: swdgh@bit.edu.cn [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Liu, Ge [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Wang, Jianzhong; Tang, Huiping [State Key Laboratory of Porous Metal Materials, Northwest Institute for Non-ferrous Metal Research, Xi’an 710016 (China)

2017-04-06

The compressive mechanical properties of the sintered sheets of continuous stainless steel fibers with different fiber diameters (8 µm, 12 µm, 28 µm) are investigated at temperatures from 298 K to 1073 K. The stress-strain curves of metal fiber sintered sheet (MFSS) are obtained by testing under uniaxial compression and 0.2% offset yield stress are determined. Inner micro-structures of the material are revealed by using scanning electron microscope (SEM) and microscopic computer tomography. The results indicates that fabrication technique and porosity are two principle factors affecting the yield strength of MFSS and the strength of MFSS is insensitive to the temperature below 873 K while softening occurs at temperature 1073 K. At relative high porosity (e.g. 77%), the material with small diameter fibers tends to have higher yield strength while at low porosity, MFSS's yield strength becomes high with the increase of the fiber diameter, which is probably attributed to the joint size, the surface appearance of fibers and prehardening generated during the manufacturing of MFSS. A simplified structure model taking joint size into consideration is established to explain the influence of the joint size on the yield strength of MFSS.

Highly improved transparent conductors by combination of TCOs and metallic grids

NARCIS (Netherlands)

Deelen, J. van; Rendering, H.; Mannetje, H.H. 't; Huis in 't Veld, A.J.; Theelen, M.J.; Vroon, Z.A.E.P.; Poodt, P.W.G.; Hovestad, A.

2010-01-01

Transparent conductive oxides (TCOs) are widely used in optoelectronic applications and are a vital part in thin film solar cells. However, these materials have some drawback, such as brittleness and a maximum transmittance for a certain sheet resistance. Alternative materials, such as metal foils,

A Review on Metal Nanoparticles Nucleation and Growth on/in Graphene

Directory of Open Access Journals (Sweden)

Francesco Ruffino

2017-07-01

Full Text Available In this review, the fundamental aspects (with particular focus to the microscopic thermodynamics and kinetics mechanisms concerning the fabrication of graphene-metal nanoparticles composites are discussed. In particular, the attention is devoted to those fabrication methods involving vapor-phase depositions of metals on/in graphene-based materials. Graphene-metal nanoparticles composites are, nowadays, widely investigated both from a basic scientific and from several technological point of views. In fact, these graphene-based systems present wide-range tunable and functional electrical, optical, and mechanical properties which can be exploited for the design and production of innovative and high-efficiency devices. This research field is, so, a wide and multidisciplinary section in the nanotechnology field of study. So, this review aims to discuss, in a synthetic and systematic framework, the basic microscopic mechanisms and processes involved in metal nanoparticles formation on graphene sheets by physical vapor deposition methods and on their evolution by post-deposition processes. This is made by putting at the basis of the discussions some specific examples to draw insights on the common general physical and chemical properties and parameters involved in the synergistic interaction processes between graphene and metals.

Chemistry and physics at liquid alkali metal/solid metal interfaces

International Nuclear Information System (INIS)

Barker, M.G.

1977-01-01

This paper describes the chemistry of processes which take place at the interface between liquid alkali metals and solid metal surfaces. A brief review of wetting data for liquid sodium is given and the significance of critical wetting temperatures discussed on the basis of an oxide-film reduction mechanism. The reactions of metal oxides with liquid metals are outlined and a correlation with wetting data established. The transfer of dissolved species from the liquid metal across the interface to form solid phases on the solid metal surface is well recognised. The principal features of such processes are described and a simple thermodynamic explanation is outlined. The reverse process, the removal of solid material into solution, is also considered. (author)

Research on refractory, reactive and rare metals in BARC

International Nuclear Information System (INIS)

Banerjee, Srikumar

2016-01-01

Material processing activities were given a due thrust in Atomic Energy Programme right from the beginning. Initially research was primarily focused on metals such as uranium, thorium and zirconium which are of direct relevance to the nuclear programme. Having attained the success in processing these metals from the indigenous resources, the scope and range of material processing activities were enhanced and broadened considerably in the subsequent years. Having mastered the Kroll process for zirconium extraction, the same process was adopted in laboratory and in pilot scales for the extraction of titanium. With the experience gained in processing and handling reactive metals, flow sheet development of group V-A and VI-A metals was taken up. This presentation will summarise how different unit operations for the processing of Mo, V, Ta, W and Nb were developed and optimized. These elements have the same crystal structure (bcc), high melting points, similar chemical interactions with other elements, generally exhibiting high ductile to brittle transition temperatures and have similar alloying behavior. The general approach of processing and purification of these metals for improving the strength and ductability are discussed. The principles for the development of protective coatings on these reactive metals are also covered. The manufacturing process for the multi-filamentary superconducting cable made out of Niobium is described to illustrate the success story of the development of entire chain of operations leading to the final deployable product meeting the exacting specifications. The challenges faced in the development of beryllium, another reactive and toxic metal is briefly discussed. In order to exploit the sizeable resources of rare earth elements in India, research on processing of rare earths was initiated quite early. In the recent past there have been efforts on separation of individual rare earth elements and in preparing rare earth compounds and inter-metallics

High Re-Operation Rates Using Conserve Metal-On-Metal Total Hip Articulations

DEFF Research Database (Denmark)

Mogensen, S L; Jakobsen, Thomas; Christoffersen, Hardy

2016-01-01

INTRODUCTION: Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two-center st......INTRODUCTION: Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two...

Microfocus study of metal distribution and speciation in tissue extracted from revised metal on metal hip implants

Energy Technology Data Exchange (ETDEWEB)

Hart, Alister J [Department of Orthopaedic Surgery, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Sandison, Ann [Department of Histopathology, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Quinn, Paul; Mosselmans, J Frederick W [Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0DE (United Kingdom); Sampson, Barry [Department of Clinical Biochemistry, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Atkinson, Kirk D [8 Nuclear Department Defence Academy College of Management and Technology HMS Sultan Military Road Gosport PO12 3BY (United Kingdom); Skinner, John A [Department of Orthopaedics, Royal National Orthopaedic Hospital, HA7 4LP (United Kingdom); Goode, Angela [Dept of Materials, Imperial College London, SW7 2AZ (United Kingdom); Powell, Jonathan J, E-mail: Paul.Quinn@diamond.ac.u [Medical Research Council Human Nutrition Research Centre, Cambridge CB1 9NL (United Kingdom)

2009-11-15

Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr which was localized to the cellular regions. There was co-localisation of Co, were present, to areas of high Cr abundance. XANES of the tissue and appropriate standards revealed that the most common species were Cr(III) and Co(II). EXAFS analysis of the tissue and various metal standards revealed that the most abundant implant-related species was Cr(III) phosphate. Different tissue preparation methods, including frozen sectioning, were examined but were found not to affect the distribution or speciation of the metals in the tissue.

Microfocus study of metal distribution and speciation in tissue extracted from revised metal on metal hip implants

International Nuclear Information System (INIS)

Hart, Alister J; Sandison, Ann; Quinn, Paul; Mosselmans, J Frederick W; Sampson, Barry; Atkinson, Kirk D; Skinner, John A; Goode, Angela; Powell, Jonathan J

2009-01-01

Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr which was localized to the cellular regions. There was co-localisation of Co, were present, to areas of high Cr abundance. XANES of the tissue and appropriate standards revealed that the most common species were Cr(III) and Co(II). EXAFS analysis of the tissue and various metal standards revealed that the most abundant implant-related species was Cr(III) phosphate. Different tissue preparation methods, including frozen sectioning, were examined but were found not to affect the distribution or speciation of the metals in the tissue.

Tool-life prediction under multi-cycle loading during metal forming: a feasibility study

Directory of Open Access Journals (Sweden)

Hu Yiran

2015-01-01

Full Text Available In the present research, the friction and wear behaviour of a hard coating were studied by using ball-on-disc tests to simulate the wear process of the coated tools for sheet metal forming process. The evolution of the friction coefficient followed a typical dual-plateau pattern, i.e. at the initial stage of sliding, the friction coefficient was relatively low, followed by a sharp increase due to the breakdown of the coatings after a certain number of cyclic dynamic loadings. This phenomenon was caused by the interactive response between the friction and wear from a coating tribo-system, which is often neglected by metal forming researchers, and constant friction coefficient values are normally used in the finite element (FE simulations to represent the complex tribological nature at the contact interfaces. Meanwhile, most of the current FE simulations consider single-cycle loading processes, whereas many metal-forming operations are conducted in a form of multi-cycle loading. Therefore, a novel friction/wear interactive friction model was developed to, simultaneously, characterise the evolutions of friction coefficient and the remaining thickness of the coating layer, to enable the wear life of coated tooling to be predicted. The friction model was then implemented into the FE simulation of a sheet metal forming process for feasibility study.

Amorphous metal composites

International Nuclear Information System (INIS)

Byrne, M.A.; Lupinski, J.H.

1984-01-01

This patent discloses an improved amorphous metal composite and process of making the composite. The amorphous metal composite comprises amorphous metal (e.g. iron) and a low molecular weight thermosetting polymer binder. The process comprises placing an amorphous metal in particulate form and a thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite

Semi-metallic polymers

DEFF Research Database (Denmark)

Bubnova, Olga; Khan, Zia Ullah; Wang, Hui

2014-01-01

Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report...... that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being...... a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics....

Crystallochemistry of rhenium compounds with metal-metal bonds

International Nuclear Information System (INIS)

Koz'min, P.A.; Surazhskaya, M.D.

1980-01-01

A review is presented including a brief description of atomic structure of 59 coordination rhenium compounds with metal-metal bond. The most important bond lengths and valent angles are presented for each compound. The dependence of rhenium-rhenium bond length on its multiplicity is discussed and possible causes of deviations from this dependence (namely, axial ligand presence, steric repulsion of ligands) are considered. On the basis of qualitative comparison of electronegativity of ligands in dimer compounds with quarternary bond of rhenium-rhenium a supposition is made on the influence of formal charge of atomic group and summary electro-negativity of ligands on the possibility of the metal-metal bond formation

Numerical analysis of the effect of the TEM00 radiation mode polarisation on the cut shape in laser cutting of thick metal sheets

International Nuclear Information System (INIS)

Zaitsev, A V; Kovalev, O B; Orishich, Anatolii M; Fomin, V M

2005-01-01

The effect of polarisation of a Gaussian beam on the radiation absorption during laser cutting of metals is investigated. A generalised formula is proposed for calculating the absorption coefficient, which describes the polarisation of three types (linear, elliptical, and circular), taking into account the fact that the beam may interact with a metal surface of an arbitrary shape. A comparison with the existing analogues (in the cases of linear and circular radiation polarisation) confirmed the advantage of employing the formula for the spatial description of the shape of the surface produced, which is highly important for processing (cutting, welding, drilling) of thick materials. The effect of laser radiation characteristics on the surface shape and cut depth in cutting stainless steel sheets is investigated numerically. It is shown for the first time that the cutting of materials by the TEM 00 beam is most efficient when the beam has elliptical polarisation directed along the direction of beam displacement and characterised by a specific axial ratio. (laser applications and other topics in quantum electronics)

Magnetic resonance imaging of metal artifact reduction sequences in the assessment of metal-on-metal hip prostheses

Directory of Open Access Journals (Sweden)

Aboelmagd SM

2014-05-01

Full Text Available Sharief M Aboelmagd, Paul N Malcolm, Andoni P Toms Department of Radiology, Norfolk and Norwich University Hospital National Health Service Trust, Norwich, UK Abstract: Recent developments in metal artifact reduction techniques in magnetic resonance (MR have, in large part, been stimulated by the advent of soft tissue complications associated with modern metal-on-metal total hip replacements. Metallic orthopedic implants can result in severe degradation of MR images because ferromagnetic susceptibility causes signal loss, signal pile-up, geometric distortion, and failure of fat suppression. There are several approaches to controlling these susceptibility artifacts. Standard fast spin echo sequences can be adapted by modifying echo times, matrix, receiver bandwidth, slice thickness, and echo trains to minimize frequency encoding misregistration. Short tau inversion recovery and 2-point Dixon techniques are both more resistant to susceptibility artifacts than spectral fat suppression. A number of dedicated metal artifact reduction sequences are now available commercially. The common approach of these multispectral techniques is to generate three dimensional datasets from which the final images are reconstructed. Frequency encoding misregistration is controlled using a variety of techniques, including specific resonant frequency acquisition, view-angle tilting, and phase encoding. Metal artifact reduction MR imaging has been the key to understanding the prevalence, severity, and prognosis of adverse reactions to metal debris in metal-on-metal hip replacements. Conventional radiographs are typically normal or demonstrate minimal change and are unable to demonstrate the often extensive soft tissue abnormalities, which include necrosis, soft tissue masses and fluid collections, myositis, muscle atrophy, tendon avulsions, and osteonecrosis. These MR findings correlate poorly with clinical and serological measures of disease, and therefore MR imaging is

Thin films of metal-organic compounds and metal nanoparticle

Indian Academy of Sciences (India)

Thin films of metal-organic compounds and metal nanoparticle-embedded polymers for nonlinear optical applications. S Philip Anthony Shatabdi Porel D ... Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which ...

The tribology of metal-on-metal total hip replacements.

Science.gov (United States)

Scholes, S C; Unsworth, A

2006-02-01

Total hip surgery is an effective way of alleviating the pain and discomfort caused by diseased or damaged joints. However, in the majority of cases, these joints have a finite life. The main reason for failure is osteolysis (bone resorption). It is well documented that an important cause of osteolysis, and therefore the subsequent loosening and failure of conventional metal- or ceramic-on-ultra-high molecular weight polyethylene joints, is the body's immunological response to the polyethylene wear particles. To avoid this, interest has been renewed in metal-on-metal joints. The intention of this paper is to review the studies that have taken place within different laboratories to determine the tribological performance of new-generation metal-on-metal total hip replacements. These types of joint offer a potential solution to enhance the longevity of prosthetic hip systems; however, problems may arise owing to the effects of metal ion release, which are, as yet, not fully understood.

Analysis of Stainless Steel Sandwich Panels with a Metal Foam Care for Lightweight Fan Blade Design

Science.gov (United States)

Min, James B.; Ghosn, Louis J.; Lerch, Bradley A.; Raj, Sai V.; Holland, Frederic A., Jr.; Hebsur, Mohan G.

2004-01-01

The quest for cheap, low density and high performance materials in the design of aircraft and rotorcraft engine fan and propeller blades poses immense challenges to the materials and structural design engineers. Traditionally, these components have been fabricated using expensive materials such as light weight titanium alloys, polymeric composite materials and carbon-carbon composites. The present study investigates the use of P sandwich foam fan blade made up of solid face sheets and a metal foam core. The face sheets and the metal foam core material were an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. The stiffness of the sandwich structure is increased by separating the two face sheets by a foam core. The resulting structure possesses a high stiffness while being lighter than a similar solid construction. Since the face sheets carry the applied bending loads, the sandwich architecture is a viable engineering concept. The material properties of 17-4 PH metal foam are reviewed briefly to describe the characteristics of the sandwich structure for a fan blade application. A vibration analysis for natural frequencies and P detailed stress analysis on the 17-4 PH sandwich foam blade design for different combinations of skin thickness and core volume %re presented with a comparison to a solid titanium blade.

Silicone metalization

Energy Technology Data Exchange (ETDEWEB)

Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

2008-12-09

A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

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.

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

Energy Technology Data Exchange (ETDEWEB)

Hegde, Ganesh, E-mail: ghegde@purdue.edu; Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard, E-mail: gekco@purdue.edu [Network for Computational Nanotechnology (NCN), Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Boykin, Timothy [Department of Electrical and Computer Engineering, University of Alabama, Huntsville, Alabama (United States)

2014-03-28

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

International Nuclear Information System (INIS)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard; Boykin, Timothy

2014-01-01

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

Science.gov (United States)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

2014-03-01

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

Some thermal analysis aspects of metal encapsulated waste

International Nuclear Information System (INIS)

Jardine, L.J.; Steindler, M.J.

1978-01-01

This paper is to summarize two waste management schemes: (1) packaging for extended storage of LWR spent fuel assemblies, with the capability for simple conversion either to terminal storage if a ''throwaway'' fuel cycle is ultimately adopted or to a form that can be reprocessed and (2) packaging for the terminal storage of solidified high-level wastes when the reprocessing of spent fuel is initiated. Only concepts utilizing metals or metal alloys to encapsulate either spent fuel or solidified high-level waste forms have been considered. Conceptual process flow sheets have been constructed to allow potential advantages and disadvantages of encapsulation alternatives to be identified in comparison with more conventional reference processes. Identification is also made of uncertainties of the analysis due to a lack of fundamental data required to perform evaluations. 3 tables

Investigation of Mechanical Properties and Metallurical Characteristics of a Metallic Chromium and Magnesium Oxide Composite

National Research Council Canada - National Science Library

Manning, Charles

1963-01-01

An experimental investigation has been made to evaluate an uncoated thin composite sheet material containing metallic chromium and magnesium oxide for aerospace applications in the temperature range...

The nonmetal-metal transition in solutions of metals in molten salts

International Nuclear Information System (INIS)

Tosi, M.P.

1997-04-01

Solutions of metals in molten salts present a rich phenomenology: localization of electrons in disordered ionic media, activated electron transport increasing with metal concentration towards a nonmetal-metal (NM-M) transition, and liquid-liquid phase separation. A brief review of progress in the study of these systems is given in this article, with main focus on the NM-M transition. After recalling the known NM-M behaviour of the component elements in the case of expanded fluid alkali metals and mercury and of solid halogens under pressure, the article focuses on liquid metal - molten salt solutions and traces the different NM-M behaviours of the alkalis in their halides and of metals added to polyvalent metal halides. (author). 51 refs, 2 figs

Laser direct joining of metal and plastic

International Nuclear Information System (INIS)

Katayama, Seiji; Kawahito, Yousuke

2008-01-01

We have developed an innovative rapid laser direct joining process of metal and plastic lap plates without adhesives or glues. The joints made between a Type 304 stainless steel plate and a polyethylene terephthalate (PET) plastic sheet of 30 mm width possessed tensile shear loads of about 3000 N. Transmission electron microscope photographs of the joint demonstrated that Type 304 and the PET were bonded on the atomic, molecular or nanostructural level through a Cr oxide film

Heavy metal movement in metal-contaminated soil profiles

Energy Technology Data Exchange (ETDEWEB)

Li, Zhenbin; Shuman, L.M. [Univ. of Georgia, Griffin, GA (United States)

1996-10-01

Heavy metal movement in soil profiles is a major environmental concern because even slow transport through the soil may eventually lead to deterioration of groundwater quality. In this study, three metal-contaminated soil (Fuquay, Dothan, and Clarendon) were selected from cropland were a high-metal flue dust had been applied annually for 6 years to raise soil pH, with application ending 4 years before sampling. One uncontaminated soil (Tifton) from the same physiographic area was also sampled as a control. Soil samples were collected in 15-cm increments from the surface to 105 cm in depth. Total contents of Zn, Cd, and Pb in the soils samples were determined. To better understand metal movement in relation to metal fractions in the soil profile, soil samples were also extracted sequentially for exchangeable (EXC), organic matter (OM), Mn oxide (MNO), amorphous Fe oxide (AFEO), crystalline Fe oxide (CFEO), and residual (RES) fractions. 35 refs., 6 figs., 2 tabs.

Novel Metals and Metal Complexes as Platforms for Cancer Therapy

OpenAIRE

Frezza, Michael; Hindo, Sarmad; Chen, Di; Davenport, Andrew; Schmitt, Sara; Tomco, Dajena; Dou, Q. Ping

2010-01-01

Metals are essential cellular components selected by nature to function in several indispensable biochemical processes for living organisms. Metals are endowed with unique characteristics that include redox activity, variable coordination modes, and reactivity towards organic substrates. Due to their reactivity, metals are tightly regulated under normal conditions and aberrant metal ion concentrations are associated with various pathological disorders, including cancer. For these reasons, coo...

The Alchemist’s Approach to Metal Poisoning: Transforming the Metal Burden

Directory of Open Access Journals (Sweden)

Wayne Briner

2014-06-01

Full Text Available Metal poisoning is a global problem with humans being exposed to a wide range of metals in varying doses and varying time frames. Traditionally, treatment involves removal of the toxic source or chelation therapy. An intermediate approach is needed. This review outlines the argument for the use of essential metal supplementation as a strategy to induce metallothionein expression and displace the toxic metal from important biological systems, improving the metal burden of the patient. Specific recommendations are given for supplementation with calcium, zinc and vitamin E as a broad strategy to improve the status of those exposed to toxic metals.

21 CFR 888.3550 - Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint patellofemorotibial polymer/metal/metal... § 888.3550 Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis. (a) Identification. A knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis is a device...

Infrared plasmonic nano-lasers based on Metal Insulator Metal waveguides

NARCIS (Netherlands)

Hill, M.T.

2010-01-01

We will present our latest results on metal-insulator-metal waveguide devices, in particular reducing the dimensions of devices and distributed feedback lasers. Also we will examine potential useful applications for metal nano-lasers.

Fatigue properties of dissimilar metal laser welded lap joints

Science.gov (United States)

Dinsley, Christopher Paul

This work involves laser welding austenitic and duplex stainless steel to zinc-coated mild steel, more specifically 1.2mm V1437, which is a Volvo Truck Coiporation rephosphorised mild steel. The work investigates both tensile and lap shear properties of similar and dissimilar metal laser welded butt and lap joints, with the majority of the investigation concentrating on the fatigue properties of dissimilar metal laser welded lap joints. The problems encountered when laser welding zinc-coated steel are addressed and overcome with regard to dissimilar metal lap joints with stainless steel. The result being the production of a set of guidelines for laser welding stainless steel to zinc-coated mild steel. The stages of laser welded lap joint fatigue life are defined and the factors affecting dissimilar metal laser welded lap joint fatigue properties are analysed and determined; the findings suggesting that dissimilar metal lap joint fatigue properties are primarily controlled by the local stress at the internal lap face and the early crack growth rate of the material at the internal lap face. The lap joint rotation, in turn, is controlled by sheet thickness, weld width and interfacial gap. Laser welded lap joint fatigue properties are found to be independent of base material properties, allowing dissimilar metal lap joints to be produced without fatigue failure occurring preferentially in the weaker parent material, irrespective of large base material property differences. The effects of Marangoni flow on the compositions of the laser weld beads are experimentally characterised. The results providing definite proof of the stirring mechanism within the weld pool through the use of speeds maps for chromium and nickel. Keywords: Laser welding, dissimilar metal, Zinc-coated mild steel, Austenitic stainless steel, Duplex stainless steel, Fatigue, Lap joint rotation, Automotive.

No association between pseudotumors, high serum metal-ion levels and metal hypersensitivity in large-head metal-on-metal total hip arthroplasty at 5-7-year follow-up

DEFF Research Database (Denmark)

Hjorth, Mette Holm; Stilling, Maiken; Soballe, Kjeld

2015-01-01

-ion concentrations were measured, metal allergy and atopic dermatitis were evaluated, and the questionnaires of the Oxford Hip Score (OHS), Harris Hip Score (HHS) and the Short-Form Health Survey (SF-36) were completed. RESULTS: Pseudotumors were found in eight patients, but they were asymptomatic and their serum...... pseudotumor formation, serum metal-ion levels, metal patch test reactivity, and atopic dermatitis. However, clinicians should be aware of asymptomatic pseudotumors, and we advise further exploration into the mechanisms involved in the pathogenesis of pseudotumors.......OBJECTIVE: The relationship between metal wear debris, pseudotumor formation and metal hypersensitivity is complex and not completely understood. The purpose of this study was to assess the prevalence of pseudotumor formation in a consecutive series of metal-on-metal (MoM) total hip arthroplasty...

Design of conveyor utilization monitoring system: a case study of powder coating line in sheet metal fabrication

Science.gov (United States)

Prasetyo, Hoedi; Sugiarto, Yohanes; Nur Rosyidi, Cucuk

2018-03-01

Conveyor is a very useful equipment to replace manpower in transporting the goods. It highly influences the productivity, production capacity utilization and eventually the production cost. This paper proposes a system to monitor the utilization of conveyor at a low cost through a case study at powder coating process line in a sheet metal fabrication. Preliminary observation was conducted to identify the problems. The monitoring system was then built and executed. The system consists of two sub systems. First is sub system for collecting and transmitting the required data and the second is sub system for displaying the data. The system utilizes sensors, wireless data transfer and windows-based application. The test results showed that the whole system works properly. By this system, the productivity and status of the conveyor can be monitored in real time. This research enriches the development of conveyor monitoring system especially for implementation in small and medium enterprises.

Advances in metal forming expert system for metal forming

CERN Document Server

Hingole, Rahulkumar Shivajirao

2015-01-01

This comprehensive book offers a clear account of the theory and applications of advanced metal forming. It provides a detailed discussion of specific forming processes, such as deep drawing, rolling, bending extrusion and stamping. The author highlights recent developments of metal forming technologies and explains sound, new and powerful expert system techniques for solving advanced engineering problems in metal forming. In addition, the basics of expert systems, their importance and applications to metal forming processes, computer-aided analysis of metalworking processes, formability analysis, mathematical modeling and case studies of individual processes are presented.

Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

KAUST Repository

Chen, Ye

2017-01-26

Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets. The composition has high conductivity and flexibility. The composition can be made by a one-pot synthesis in which a graphene material precursor is converted to the graphene material, and the metal precursor is converted to the metal. A reducing solvent or dispersant such as NMP can be used. Devices made from the composition include a pressure sensor which has high sensitivity. Two two- dimension materials can be combined to form a hybrid material.

Ferrous and common nonferrous metals industries and associated scrap metals: a review

International Nuclear Information System (INIS)

Mautz, E.W.

1975-11-01

Literature on the common metals industries, scrap metal relationships, and transportation aspects has been reviewed as background information in a study to determine the feasibility of a portable melting facility for radioactively contaminated metals. This report draws substantially on government-sponsored studies. Aluminum, copper, iron and steel, and nickel metal industries are discussed from the viewpoints of the general industry characteristics, primary metal production processes, and secondary metal processing aspects. 46 references, 10 tables

Modulating the electronic and magnetic properties of bilayer borophene via transition metal atoms intercalation: from metal to half metal and semiconductor.

Science.gov (United States)

Zhang, Xiuyun; Sun, Yi; Ma, Liang; Zhao, Xinli; Yao, Xiaojing

2018-07-27

Borophene, a two-dimensional monolayer made of boron atoms, has attracted wide attention due to its appealing properties. Great efforts have been devoted to fine tuning its electronic and magnetic properties for desired applications. Herein, we theoretically investigate the versatile electronic and magnetic properties of bilayer borophene (BLB) intercalated by 3d transition metal (TM) atoms, TM@BLBs (TM = Ti-Fe), using ab initio calculations. Four allotropes of AA-stacking (α 1 -, β-, β 12 - and χ 3 -) BLBs with different intercalation concentrations of TM atoms are considered. Our results show that the TM atoms are strongly bonded to the borophene layers with fairly large binding energies, around 6.31 ∼ 15.44 eV per TM atom. The BLBs with Cr and Mn intercalation have robust ferromagnetism, while for the systems decorated with Fe atoms, fruitful magnetic properties, such as nonmagnetic, ferromagnetic or antiferromagnetic, are identified. In particular, the α 1 - and β-BLBs intercalated by Mn or Fe atom can be transformed into a semiconductor, half metal or graphene-like semimetal. Moreover, some heavily doped TM@BLBs expose high Curie temperatures above room temperature. The attractive properties of TM@BLBs entail an efficient way to modulate the electronic and magnetic properties of borophene sheets for advanced applications.

Metal-nanotube composites as radiation resistant materials

Energy Technology Data Exchange (ETDEWEB)

González, Rafael I.; Valencia, Felipe; Mella, José; Kiwi, Miguel, E-mail: m.kiwi.t@gmail.com [Departamento de Física, Facultad de Ciencias, CEDENNA, Universidad de Chile, Casilla 653, Santiago 7800024 (Chile); Duin, Adri C. T. van [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); So, Kang Pyo; Li, Ju [Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bringa, Eduardo M. [CONICET and Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza 5500 (Argentina)

2016-07-18

The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

Metal-nanotube composites as radiation resistant materials

International Nuclear Information System (INIS)

González, Rafael I.; Valencia, Felipe; Mella, José; Kiwi, Miguel; Duin, Adri C. T. van; So, Kang Pyo; Li, Ju; Bringa, Eduardo M.

2016-01-01

The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

Light metal production

Science.gov (United States)

Fan, Qinbai

2016-04-19

An electrochemical process for the production of light metals, particularly aluminum. Such a process involves contacting a light metal source material with an inorganic acid to form a solution containing the light metal ions in high concentration. The solution is fed to an electrochemical reactor assembly having an anode side containing an anode and a cathode side containing a cathode, with anode side and the cathode side separated by a bipolar membrane, with the solution being fed to the anode side. Light metal ions are electrochemically transferred through the bipolar membrane to the cathode side. The process further involves reducing the light metal ions to light metal powder. An associated processing system is also provided.

Possibility of a ferromagnetic and conducting metal-organic network

Science.gov (United States)

Mabrouk, Manel; Hayn, Roland; Denawi, Hassan; Ben Chaabane, Rafik

2018-05-01

In this paper, we present first principles calculations based on the spin-polarized generalized gradient approximation with on-site Coulomb repulsion term (SGGA + U), to explore the electronic and magnetic properties of the novel planar metal-organic networks TM-Pc and TM-TCNB (where TM means a transition metal of the 3d series: Ti, V, Cr, …, or Zn, Pc - Phthalocyanine, and TCNB - Tetracyanobenzene) as free-standing sheets. This work is an extension of two earlier research works dealing with the Mn (Mabrouk et al., 2015) and Fe (Mabrouk et al., 2017) cases. Our theoretical investigations demonstrate that TM-Pc are more stable than TM-TCNB. Our results unveil that all the TM-Pc frameworks have an insulating behavior with the exception of Mn-Pc which is half-metallic and favor antiferromagnetic order in the case of our magnetic systems except for V-Pc which is ferromagnetic. In contrast, the TM-TCNB networks are metallic at least in one spin direction and exhibit long-range ferromagnetic coupling in case for magnetic structures, which represent ideal candidates and an interesting prospect of unprecedented applications in spintronics. In addition, these results may shed light to achieve a new pathway on further experimental research in molecular spintronics.

Drosophila melanogaster Models of Metal-Related Human Diseases and Metal Toxicity.

Science.gov (United States)

Calap-Quintana, Pablo; González-Fernández, Javier; Sebastiá-Ortega, Noelia; Llorens, José Vicente; Moltó, María Dolores

2017-07-06

Iron, copper and zinc are transition metals essential for life because they are required in a multitude of biological processes. Organisms have evolved to acquire metals from nutrition and to maintain adequate levels of each metal to avoid damaging effects associated with its deficiency, excess or misplacement. Interestingly, the main components of metal homeostatic pathways are conserved, with many orthologues of the human metal-related genes having been identified and characterized in Drosophila melanogaster . Drosophila has gained appreciation as a useful model for studying human diseases, including those caused by mutations in pathways controlling cellular metal homeostasis. Flies have many advantages in the laboratory, such as a short life cycle, easy handling and inexpensive maintenance. Furthermore, they can be raised in a large number. In addition, flies are greatly appreciated because they offer a considerable number of genetic tools to address some of the unresolved questions concerning disease pathology, which in turn could contribute to our understanding of the metal metabolism and homeostasis. This review recapitulates the metabolism of the principal transition metals, namely iron, zinc and copper, in Drosophila and the utility of this organism as an experimental model to explore the role of metal dyshomeostasis in different human diseases. Finally, a summary of the contribution of Drosophila as a model for testing metal toxicity is provided.

The coloring problem in the solid-state metal boride carbide ScB{sub 2}C{sub 2}. A theoretical analysis

Energy Technology Data Exchange (ETDEWEB)

Lassoued, Souheila [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Boucher, Benoit [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany); Boutarfaia, Ahmed [Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Gautier, Regis; Halet, Jean-Francois [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques

2016-08-01

The electronic properties of the layered ternary metal boride carbide ScB{sub 2}C{sub 2}, the structure of which consists of B/C layers made of fused five- and seven-membered rings alternating with scandium sheets, are analyzed. In particular, the respective positions of the B and C atoms (the so-called coloring problem) are tackled using density functional theory, quantum theory of atoms in molecules, and electron localizability indicator calculations. Results reveal that (i) the most stable coloring minimizes the number of B-B and C-C contacts and maximizes the number of boron atoms in the heptagons, (ii) the compound is metallic in character, and (iii) rather important covalent bonding occurs between the metallic sheets and the boron-carbon network.

Direct Metal Laser Sintering: A Digitised Metal Casting Technology

OpenAIRE

Venkatesh, K. Vijay; Nandini, V. Vidyashree

2013-01-01

Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons.

Direct metal laser sintering: a digitised metal casting technology.

Science.gov (United States)

Venkatesh, K Vijay; Nandini, V Vidyashree

2013-12-01

Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons.

Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS2

Directory of Open Access Journals (Sweden)

X. D. Li

2015-05-01

Full Text Available Single adsorption of different atoms on pristine two-dimensional monolayer MoS2 have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS2. Additionally, local or long-range magnetic moments of two-dimensional MoS2 sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS2 monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application.

Application of a mixed metal oxide catalyst to a metallic substrate

Science.gov (United States)

Sevener, Kathleen M. (Inventor); Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Wisner, Daniel L. (Inventor)

2009-01-01

A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system.

Metal flows of the circumgalactic medium, and the metal budget in galactic haloes

Science.gov (United States)

Muratov, Alexander L.; Kereš, Dušan; Faucher-Giguère, Claude-André; Hopkins, Philip F.; Ma, Xiangcheng; Anglés-Alcázar, Daniel; Chan, T. K.; Torrey, Paul; Hafen, Zachary H.; Quataert, Eliot; Murray, Norman

2017-07-01

We present an analysis of the flow of metals through the circumgalactic medium (CGM) in the Feedback in Realistic Environments (FIRE) simulations of galaxy formation, ranging from isolated dwarfs to L* galaxies. We find that nearly all metals produced in high-redshift galaxies are carried out in winds that reach 0.25Rvir. When measured at 0.25Rvir the metallicity of outflows is slightly higher than the interstellar medium (ISM) metallicity. Many metals thus reside in the CGM. Cooling and recycling from this reservoir determine the metal budget in the ISM. The outflowing metal flux decreases by a factor of ˜2-5 between 0.25Rvir and Rvir. Furthermore, outflow metallicity is typically lower at Rvir owing to dilution of the remaining outflow by metal-poor material swept up from the CGM. The inflow metallicity at Rvir is generally low, but outflow and inflow metallicities are similar in the inner halo. At low redshift, massive galaxies no longer generate outflows that reach the CGM, causing a divergence in CGM and ISM metallicity. Dwarf galaxies continue to generate outflows, although they preferentially retain metal ejecta. In all but the least massive galaxy considered, a majority of the metals are within the halo at z = 0. We measure the fraction of metals in CGM, ISM and stars, and quantify the thermal state of CGM metals in each halo. The total amount of metals in the low-redshift CGM of two simulated L* galaxies is consistent with estimates from the Cosmic Origin Spectrograph haloes survey, while for the other two it appears to be lower.

Reduction of metal oxides in metal carbide fusion superheated with plasma

Energy Technology Data Exchange (ETDEWEB)

Hedai, L

1981-01-01

A significant part of metals is capable of binding a high quantity of carbon in the form of carbide. The carbide fusion produced as a result of smelting and superheating, metal carbides with the use of plasma might be a medium to be utilized for the reduction of different metal oxides, whilst also the original carbide structure of the metal carbides will be reduced to metallic structure. The experiments conducted by making use of plasma equipment, of 20, 55 and 100 kW performances are described. On the basis of the results of the experiments performed, the following statements are to be made. The oxide reductions taking place in the metal carbide fusion might also be carried out in open-hearth furnaces, because reducing atmosphere is not necessitated during this procedure. The quantity of energy required is basically defined by the energy needed for smelting and superheating the metal carbide. The method for producing the metal described may be mainly applied for the allied production of high-purity steels as well as for that of ferro-alloys.

Metal artifact reduction method using metal streaks image subtraction

International Nuclear Information System (INIS)

Pua, Rizza D.; Cho, Seung Ryong

2014-01-01

Many studies have been dedicated for metal artifact reduction (MAR); however, the methods are successful to varying degrees depending on situations. Sinogram in-painting, filtering, iterative method are some of the major categories of MAR. Each has its own merits and weaknesses. A combination of these methods or hybrid methods have also been developed to make use of the different benefits of two techniques and minimize the unfavorable results. Our method focuses on the in-paitning approach and a hybrid MAR described by Xia et al. Although in-painting scheme is an effective technique in reducing the primary metal artifacts, a major drawback is the reintroduction of new artifacts that can be caused by an inaccurate interpolation process. Furthermore, combining the segmented metal image to the corrected nonmetal image in the final step of a conventional inpainting approach causes an issue of incorrect metal pixel values. Our proposed method begins with a sinogram in-painting approach and ends with an image-based metal artifact reduction scheme. This work provides a simple, yet effective solution for reducing metal artifacts and acquiring the original metal pixel information. The proposed method demonstrated its effectiveness in a simulation setting. The proposed method showed image quality that is comparable to the standard MAR; however, quantitatively more accurate than the standard MAR

Do constructed wetlands remove metals or increase metal bioavailability?

Science.gov (United States)

Xu, Xiaoyu; Mills, Gary L

2018-07-15

The H-02 wetland was constructed to treat building process water and storm runoff water from the Tritium Processing Facility on the Department of Energy's Savannah River Site (Aiken, SC). Monthly monitoring of copper (Cu) and zinc (Zn) concentrations and water quality parameters in surface waters continued from 2014 to 2016. Metal speciation was modeled at each sampling occasion. Total Cu and Zn concentrations released to the effluent stream were below the NPDES limit, and the average removal efficiency was 65.9% for Cu and 71.1% for Zn. The metal-removal processes were found out to be seasonally regulated by sulfur cycling indicated by laboratory and model results. High temperature, adequate labile organic matter, and anaerobic conditions during the warm months (February to August) favored sulfate reduction that produced sulfide minerals to significantly remove metals. However, the dominant reaction in sulfur cycling shifted to sulfide oxidation during the cool months (September to next March). High concentrations of metal-organic complexes were observed, especially colloidal complexes of metal and fulvic acid (FA), demonstrating adsorption to organic matter became the primary process for metal removal. Meanwhile, the accumulation of metal-FA complexes in the wetland system will cause negative effects to the surrounding environment as they are biologically reactive, highly bioavailable, and can be easily taken up and transferred to ecosystems by trophic exchange. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impact of repeated single-metal and multi-metal pollution events on soil quality.

Science.gov (United States)

Burges, Aritz; Epelde, Lur; Garbisu, Carlos

2015-02-01

Most frequently, soil metal pollution results from the occurrence of repeated single-metal and, above all, multi-metal pollution events, with concomitant adverse consequences for soil quality. Therefore, in this study, we evaluated the impact of repeated single-metal and multi-metal (Cd, Pb, Cu, Zn) pollution events on soil quality, as reflected by the values of a variety of soil microbial parameters with potential as bioindicators of soil functioning. Specifically, parameters of microbial activity (potentially mineralizable nitrogen, β-glucosidase and acid phosphatase activity) and biomass (fungal and bacterial gene abundance by RT-qPCR) were determined, in the artificially metal-polluted soil samples, at regular intervals over a period of 26 weeks. Similarly, we studied the evolution over time of CaCl2-extractable metal fractions, in order to estimate metal bioavailability in soil. Different metals showed different values of bioavailability and relative bioavailability ([metal]bio/[metal]tot) in soil throughout the experiment, under both repeated single-metal and multi-metal pollution events. Both repeated Zn-pollution and multi-metal pollution events led to a significant reduction in the values of acid phosphatase activity, and bacterial and fungal gene abundance, reflecting the negative impact of these repeated events on soil microbial activity and biomass, and, hence, soil quality. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of essential work of fracture in a dual phase high strength steel sheet

International Nuclear Information System (INIS)

Gutierrez, D.; Perez, L. I.; Lara, A.; Casellas, D.; Prado, J. M.

2013-01-01

Fracture toughness of advanced high strength steels (AHSS), can be used to optimize crash behavior of structural components. However it cannot be readily measured in metal sheet because of the sheet thickness. In this work, the Essential Work of Fracture (EWF) methodology is proposed to evaluate the fracture toughness of metal sheets. It has been successfully applied in polymers films and some metal sheets. However, their information about the applicability of this methodology to AHSS is relatively scarce. In the present work the fracture toughness of a Dual Phase (strength of 800 MPa) and drawing steel sheets has been measured by means of the EWF. The results show that the test requirements are met and also show the clear influence of notch radii on the measured values, specially for the AHSS grade. Thus, the EWF is postulated as a methodology to evaluate the fracture toughness in AHSS sheets. (Author) 18 refs.

Metal-core@metal oxide-shell nanomaterials for gas-sensing applications: a review

Energy Technology Data Exchange (ETDEWEB)

Mirzaei, A.; Janghorban, K.; Hashemi, B. [Shiraz University, Department of Materials Science and Engineering (Iran, Islamic Republic of); Neri, G., E-mail: gneri@unime.it [University of Messina, Department of Electronic Engineering, Chemistry and Industrial Engineering (Italy)

2015-09-15

With an ever-increasing number of applications in many advanced fields, gas sensors are becoming indispensable devices in our daily life. Among different types of gas sensors, conductometric metal oxide semiconductor (MOS) gas sensors are found to be the most appealing for advanced applications in the automotive, biomedical, environmental, and safety sectors because of the their high sensitivity, reduced size, and low cost. To improve their sensing characteristics, new metal oxide-based nanostructures have thus been proposed in recent years as sensing materials. In this review, we extensively review gas-sensing properties of core@ shell nanocomposites in which metals as the core and metal oxides as the shell structure, both of nanometer sizes, are assembled into a single metal@metal oxide core–shell. These nanostructures not only combine the properties of both noble metals and metal oxides, but also bring unique synergetic functions in comparison with single-component materials. Up-dated achievements in the synthesis and characterization of metal@metal oxide core–shell nanostructures as well as their use in MOS sensors are here reported with the main objective of providing an overview about their gas-sensing properties.

Incorporation of metal bioavailability into regulatory frameworks-metal exposure in water and sediment

Energy Technology Data Exchange (ETDEWEB)

Ahlf, Wolfgang [Inst. of Environmental Tech. and Energy Economics, TUHH, Hamburg (Germany); Drost, Wiebke [Umweltpruefung Chemikalien IV, Umweltbundesamt, Dessau (Germany); Heise, Susanne [Dept. of Life Sciences, HAW, Hamburg (Germany)

2009-10-15

Background, aim, and scope The cause for this position paper is the impression that risk assessors consider primarily the concentration of free metal ions dissolved in solution controlling metal bioavailability in aquatic systems. Aiming at a more realistic risk assessment of metals, bioavailability has to be discussed under the scope of main uptake routes of metals to organisms. Materials and methods On the basis of a review on the literature relating to bioavailability approaches, this work discusses the incorporation of metal bioavailability into the risk assessment of metals in the context of metal exposure. Results The biotic ligand model (BLM) and the concept of sulfide bound metals described by the ratio of simultaneously extracted metals and acid volatile sulfide concept (AVS) have been developed to consider the bioavailability of metals. Both approaches assume that the free ion concentration is the most relevant exposure pathway. However, apart from geochemical conditions, which control free metal concentration, bioavailability is additionally a result of contaminant/particle interaction and of organisms' activity. Asking for the relevant exposure pathways for inorganic metals to organisms, the compartments' water and sediment have been evaluated and also the importance of contaminated food. (orig.)

Literature survey on metal waste form for metallic waste from electrorefiners for the electrometallurgical treatment of spent metallic fuels

International Nuclear Information System (INIS)

Nishimura, Tomohiro

2003-01-01

This report summarizes the recent results of the metal waste form development activities at the Argonne National Laboratory in the USA for high-level radioactive metallic waste (stainless-steel (SS) cladding hulls, zirconium (Zr), noble-metal fission products (NMFPs), etc.) from electrorefiners for the electrometallurgical treatment of spent metallic fuels. Their main results are as follows: (1) SS- 15 wt.% Zr- ∼4 wt.% NMFPs alloy was selected as the metal waste form, (2) metallurgical data, properties, long-term corrosion data, etc. of the alloy have been collected, (3) 10-kg ingots have been produced in hot tests and a 60-kg production machine is under development. The following research should be made to show the feasibility of the metal waste form in Japan: (1) degradation assessment of the metal waste form in Japanese geological repository environments, and (2) clarification of the maximum allowable contents of NMFPs. (author)

PREPARATION OF METAL OXIDE POWDERS FROM METAL LOADED VERSATIC ACID

OpenAIRE

KAKIHATA, Takayuki; USAMI, Kensuke; YAMAMOTO, Hideki; SHIBATA, Junji

1998-01-01

A production process for metal oxide powders was developed using a solvent extraction method. Versatic Acid 10 and D2EHPA solutions containing copper, zinc and nickel were used for a precipitation-stripping process, where oxalic acid was added to the solution as a precipitation reagent.Copper, zinc and nickel oxalates were easily formed in an aqueous phase, and 99.9% of precipitation was obtained for each metal during this process. These metal oxalates were easily converted to metal oxides by...

Single sheet metal oxides and hydroxides

DEFF Research Database (Denmark)

Huang, Lizhi

The synthesis of layered double hydroxides (LDHs) provides a relatively easy and traditional way to build versatile chemical compounds with a rough control of the bulk structure. The delamination of LDHs to form their single host layers (2D nanosheets) and the capability to reassemble them offer......) Delamination of the LDHs structure (oxGRC12) with the formation of single sheet iron (hydr)oxide (SSI). (3) Assembly of the new 2D nanosheets layer by layer to achieve desired functionalities....

Robot-based additive manufacturing for flexible die-modelling in incremental sheet forming

Science.gov (United States)

Rieger, Michael; Störkle, Denis Daniel; Thyssen, Lars; Kuhlenkötter, Bernd

2017-10-01

The paper describes the application concept of additive manufactured dies to support the robot-based incremental sheet metal forming process (`Roboforming') for the production of sheet metal components in small batch sizes. Compared to the dieless kinematic-based generation of a shape by means of two cooperating industrial robots, the supporting robot models a die on the back of the metal sheet by using the robot-based fused layer manufacturing process (FLM). This tool chain is software-defined and preserves the high geometrical form flexibility of Roboforming while flexibly generating support structures adapted to the final part's geometry. Test series serve to confirm the feasibility of the concept by investigating the process challenges of the adhesion to the sheet surface and the general stability as well as the influence on the geometric accuracy compared to the well-known forming strategies.

Recycling of spent noble metal catalysts with emphasis on pyrometallurgical processing

Energy Technology Data Exchange (ETDEWEB)

Hagelueken, C. [Degussa Huels AG, Hanau (Germany)

1999-09-01

Precious metal catalysts for catalytic Naphta Reforming, Isomerization, Hydrogenation and other chemical and petrochemical processes are valuable assets for oil refineries and chemical companies. At the end of the service life of a reactor load of catalyst, the efficient and reliable recovery of the precious metals contained in the catalyst is of paramount importance. More than 150 years of technological advances at Degussa-Huels have resulted in refining methods for all kinds of precious metal containing materials which guarantee an optimum technical yield of the precious metals included. The refining of catalysts today is one of the important activities in the precious metals business unit. In the state-of-the-art precious metal refinery at Hanau in the centre of Germany, a wide variety of processes for the recovery of all precious metals is offered. These processes include accurate preparation, sampling and analysis as well as both wet-chemical and pyrometallurgical recovery techniques. Special emphasis in this presentation is laid on the advantages of pyrometallurgical processes for certain kinds of catalysts. To avoid any risks during transport, sampling and treatment of the spent catalyst, all parties involved in the recycling chain strictly have to follow the relevant safety regulations. Under its commitment to 'Responsible Care' standard procedures have been developed which include pre-shipment samples, safety data sheets/questionnaires and inspection of spent catalysts. These measures not only support a safe and environmentally sound catalyst recycling but also enable to determine the most suitable and economic recovery process - for the benefit of the customer. (orig.)

Evaluation of complexing agents and column temperature in ion chromatographic separation of alkali metals, alkaline earth metals and transition metals ion

International Nuclear Information System (INIS)

Kelkar, Anoop; Pandey, Ashish; Name, Anil B.; Das, D.K.; Behere, P.G.; Mohd Afzal

2015-01-01

The aim of ion chromatography method development is the resolution of all metal ions of interests. Resolution can be improved by changing the selectivity. Selectivity in chromatography can be altered by changes in mobile phase (eg eluent type, eluent strength) or through changes in stationary phase. Temperature has been used in altering the selectivity of particularly in reversed phase liquid chromatography and ion exchange chromatography. Present paper describe the retention behaviour of alkali metals, alkaline earth metals and transition metal ions on a silica based carboxylate function group containing analyte column. Alkali metals, alkaline earth metals and transition metal ions were detected by ion conductivity and UV-VIS detectors respectively

Acetabular bone density and metal ions after metal-on-metal versus metal-on-polyethylene total hip arthroplasty; short-term results

NARCIS (Netherlands)

Zijlstra, Wierd P.; van der Veen, Hugo C.; van den Akker-Scheek, Inge; Zee, Mark J. M.; Bulstra, Sjoerd K.; van Raay, Jos J. A. M.

Information on periprosthetic acetabular bone density is lacking for metal-on-metal total hip arthroplasties. These bearings use cobalt-chromium instead of titanium acetabular components, which could lead to stress shielding and hence periprosthetic bone loss. Cobalt and chromium ions have

Conducting metal oxide and metal nitride nanoparticles

Science.gov (United States)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

2017-12-26

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst support in a fuel cell.

Metal and nutrient dynamics in decomposing tree litter on a metal contaminated site

International Nuclear Information System (INIS)

Van Nevel, Lotte; Mertens, Jan; Demey, Andreas; De Schrijver, An; De Neve, Stefaan; Tack, Filip M.G.; Verheyen, Kris

2014-01-01

In a forest on sandy, metal polluted soil, we examined effects of six tree species on litter decomposition rates and accompanied changes in metal (Cd, Zn) and nutrient (base cations, N, C) amounts. Decomposition dynamics were studied by means of a litterbag experiment lasting for 30 months. The decomposition peak occurred within the first year for all tree species, except for aspen. During litter decomposition, high metal litter types released part of their accumulated metals, whereas low metal litter types were characterized by a metal enrichment. Base cations, N and C were released from all litter types. Metal release from contaminated litter might involve risks for metal dispersion towards the soil. On the other hand, metal enrichment of uncontaminated litter may be ecologically relevant as it can be easily transported or serve as food source. - Highlights: • Litter decomposition peak occurred within the first year for all tree species, except for aspen. • Base cations, N and C were released from all litter types during decomposition. • Cd and Zn were released from the high metal litter types. • Low metal litter types were characterized by a net Cd and Zn enrichment. • Metal and nutrient releases were reflected in topsoil characteristics. - Litter decomposition rates, as well as enrichment and release dynamics of metals and nutrients in decomposing litter were divergent under the different tree species

Weld metal design data for 316L(N)

Energy Technology Data Exchange (ETDEWEB)

Tavassoli, A.A.F. [Commissariat a l' Energie Atoique, CEA, Saclay (France)

2007-07-01

This paper extends the ITER materials properties documentations to weld metal types 316L, 19-12-2 and 16-8-2, used for welding of Type 316L(N), i.e. the structural material retained for manufacturing of ITER main components such as the vacuum vessel. The data presented include those of the low temperature (316L) and high temperature (19-12-2) grades, as well as, the more readily available grade (16-8-2). Weld metal properties data for all three grades are collected, sorted and analyzed according to the French design and construction rules for nuclear components (RCC-MR). Particular attention is paid to the type of weld metal (e.g. wire for TIG, covered electrode for manual arc, flux wire for automatic welding), and the type and the position of welding. Design allowables are derived for each category of weld and compared with those of the base metal. The data sheets established for each physical and mechanical properties follow the presentation established for the ITER Materials Properties Handbook (MPH). They are part of the documentation that when combined with codification and inspection documents should satisfy ITER licensing needs. In most cases, the analyses performed, go beyond conventional analyses required in present international codes and pay attention to specific needs of ITER. These include, possible effects of exposures to high temperatures during various manufacturing stages e.g. HIPing, and effects of irradiation at low and medium temperatures. In general, it is noticed that all three weld metals satisfy the RCC-MR requirements, provided compositions and types of welds used correspond to those specified in RCC-MR. (orig.)

Studies on the optimization of deformation processed metal metal matrix composites

Energy Technology Data Exchange (ETDEWEB)

Ellis, Tim W. [Iowa State Univ., Ames, IA (United States)

1994-01-04

A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New and novel alloying procedures were investigated to extend the range of production methods available for these material. These studies focused on the use of High Pressure Gas Atomization and the development of new containment technologies for the liquid alloy. This allowed the production of alloys with a much more refined starting microstructure and lower contamination than available by other methods. The knowledge gained in the previous studies was used to develop two completely new families of deformation processed metal metal matrix composites. These composites are based on immissible alloys with yttrium and magnesium matrices and refractory metal reinforcement. This work extends the physical property range available in deformation processed metal metal matrix composites. Additionally, it also represents new ways to apply these metals in engineering applications.

Nanoporous metal-carbon composite

Science.gov (United States)

Worsley, Marcus A.; Satcher, Joe; Kucheyev, Sergei; Charnvanichborikarn, Supakit; Colvin, Jeffrey; Felter, Thomas; Kim, Sangil; Merrill, Matthew; Orme, Christine

2017-12-19

Described here is a metal-carbon composite, comprising (a) a porous three-dimensional scaffold comprising one or more of carbon nanotubes, graphene and graphene oxide, and (b) metal nanoparticles disposed on said porous scaffold, wherein the metal-carbon composite has a density of 1 g/cm.sup.3 or less, and wherein the metal nanoparticles account for 1 wt. % or more of the metal-carbon composite. Also described are methods for making the metal-carbon composite.

The Sounds of Metal

DEFF Research Database (Denmark)

Grund, Cynthia M.

2015-01-01

Two, I propose that this framework allows for at least a theoretical distinction between the way in which extreme metal – e.g. black metal, doom metal, funeral doom metal, death metal – relates to its sound as music and the way in which much other music may be conceived of as being constituted...

Effects of heavy metal adsorption on silicene

KAUST Repository

Kaloni, Thaneshwor P.

2014-06-02

Based on first-principles calculations, we study the effects of heavy metal atoms (Au, Hg, Tl, and Pb) adsorbed on silicene. We find that the hollow site is energetically favorable in each case. We particulary address the question how the adsorption modifies the band structure in the vicinity of the Fermi energy. Our results demonstrate that the heavy metal adatoms result in substantial energy gaps and band splittings in the silicene sheet as long as the binding is strong, which, however, is not always the case. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) Carbon nanotube flexible sponge was manufactured as high performance electromagnetic shielding material. Chemical vapour deposition (CVD) synthesized sponges with extreme light weight show an electromagnetic shielding above 20 dB and a specific electromagnetic shielding as high as 1100 dB cm3g-1 in the whole 1-18 GHz range. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lattice Location of Transition Metals in Semiconductors

CERN Multimedia

2002-01-01

%IS366 %title\\\\ \\\\Transition metals (TMs) in semiconductors have been the subject of considerable research for nearly 40 years. This is due both to their role as important model impurities for deep centers in semiconductors, and to their technological impact as widespread contaminants in Si processing, where the miniaturization of devices requires to keep their sheet concentration below 10$^{10}$ cm$^{-2}$. As a consequence of the low TM solubility, conventional ion beam methods for direct lattice location have failed completely in identifying the lattice sites of isolated transition metals. Although electron paramagnetic resonance (EPR) has yielded valuable information on a variety of TM centers, it has been unable to detect certain defects considered by theory, e.g., isolated interstitial or substitutional Cu in Si. The proposed identity of other EPR centers such as substitutional Fe in Si, still needs confirmation by additional experimental methods. As a consequence, the knowledge on the structural propert...

Method and apparatus for dissociating metals from metal compounds extracted into supercritical fluids

Science.gov (United States)

Wai, Chien M.; Hunt, Fred H.; Smart, Neil G.; Lin, Yuehe

2000-01-01

A method for dissociating metal-ligand complexes in a supercritical fluid by treating the metal-ligand complex with heat and/or reducing or oxidizing agents is described. Once the metal-ligand complex is dissociated, the resulting metal and/or metal oxide form fine particles of substantially uniform size. In preferred embodiments, the solvent is supercritical carbon dioxide and the ligand is a .beta.-diketone such as hexafluoroacetylacetone or dibutyldiacetate. In other preferred embodiments, the metals in the metal-ligand complex are copper, silver, gold, tungsten, titanium, tantalum, tin, or mixtures thereof. In preferred embodiments, the reducing agent is hydrogen. The method provides an efficient process for dissociating metal-ligand complexes and produces easily-collected metal particles free from hydrocarbon solvent impurities. The ligand and the supercritical fluid can be regenerated to provide an economic, efficient process.

Transition metal ions mediated tyrosine based short peptide amphiphile nanostructures inhibit bacterial growth.

Science.gov (United States)

Joshi, Khashti Ballabh; Singh, Ramesh; Mishra, Narendra Kumar; Kumar, Vikas; Vinayak, Vandana

2018-05-17

We report the design and synthesis of biocompatible small peptide based molecule for the controlled and targeted delivery of the encapsulated bioactive metal ions via transforming their internal nanostructures. Tyrosine based short peptide amphiphile (sPA) was synthesized which self-assembled into β-sheet like secondary structures. The self assembly of the designed sPA was modulated by using different bioactive transition metal ions which is confirmed by spectroscopic and microscopic techniques. These bioactive metal ions conjugated sPA hybrid structures are further used to develop antibacterial materials. It is due to the excellent antibacterial activity of zinc ions that the growth of clinically relevant bacteria such as E. Coli was inhibited in the presence of zinc-sPA conjugate. The bacterial test demonstrated that owing to high biocompatibility with bacterial cell, the designed sPA worked as metal ions delivery agent and therefore it can show great potential in locally addressing bacterial infections. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trends and Visions in Metal Forming Tribology

DEFF Research Database (Denmark)

Bay, Niels

2011-01-01

operations, which otherwise would require the use of environmentally hazardous lubricant systems. A methodology for prediction of limits of lubrication of new tribo-system for sheet forming production based on numerical modelling and off-line testing in dedicated simulative tribo-tests is proposed....... of structured work piece and tool surfaces to facilitate micro-hydro-dynamic lubrication. Increased knowledge on skin-pass rolling to establish structured sheet surfaces and new automatic polishing equipment to manufacture tailored tool surfaces are important means to improve tribo-conditions in severe forming......Research and development in metal forming tribology is characterized by intensified focus on new tribo-systems such as new lubricants, tool materials and tool coatings in order to substitute environmentally hazardous lubricant systems. Other means to solve these problems include the development...

Soil heavy metals

Energy Technology Data Exchange (ETDEWEB)

Sherameti, Irena [Jena Univ. (Germany). Inst. fuer Allgemeine Botanik und Pflanzenphysiologie; Varma, Ajit (eds.) [Amity Univ., Uttar Pradesh (India). Amity Inst. of Microbial Technology; Amity Science, Technology and Innovation Foundation, Noida, UP (India)

2010-07-01

Human activities have dramatically changed the composition and organisation of soils. Industrial and urban wastes, agricultural application and also mining activities resulted in an increased concentration of heavy metals in soils. How plants and soil microorganisms cope with this situation and the sophisticated techniques developed for survival in contaminated soils is discussed in this volume. The topics presented include: the general role of heavy metals in biological soil systems; the relation of inorganic and organic pollutions; heavy metal, salt tolerance and combined effects with salinity; effects on abuscular mycorrhizal and on saprophytic soil fungi; heavy metal resistance by streptomycetes; trace element determination of environmental samples; the use of microbiological communities as indicators; phytostabilization of lead polluted sites by native plants; effects of soil earthworms on removal of heavy metals and the remediation of heavy metal contaminated tropical land. (orig.)

Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Li, X. D.; Fang, Y. M.; Wu, S. Q., E-mail: zzhu@xmu.edu.cn, E-mail: wsq@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Zhu, Z. Z., E-mail: zzhu@xmu.edu.cn, E-mail: wsq@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen 361005 (China)

2015-05-15

Single adsorption of different atoms on pristine two-dimensional monolayer MoS{sub 2} have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS{sub 2}. Additionally, local or long-range magnetic moments of two-dimensional MoS{sub 2} sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS{sub 2} monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application.

Peroxotitanates for Biodelivery of Metals

Energy Technology Data Exchange (ETDEWEB)

Hobbs, David; Elvington, M.

2009-02-11

Metal-based drugs are largely undeveloped in pharmacology. One limiting factor is the systemic toxicity of metal-based compounds. A solid-phase, sequestratable delivery agent for local delivery of metals could reduce systemic toxicity, facilitating new drug development in this nascent area. Amorphous peroxotitanates (APT) are ion exchange materials with high affinity for several heavy metal ions, and have been proposed to deliver or sequester metal ions in biological contexts. In the current study, we tested a hypothesis that APT are able to deliver metals or metal compounds to cells. We exposed fibroblasts (L929) or monocytes (THP1) to metal-APT materials for 72 h in vitro, then measured cellular mitochondrial activity (SDH-MTT method) to assess the biological impact of the metal-APT materials vs. metals or APT alone. APT alone did not significantly affect cellular mitochondrial activity, but all metal-APT materials suppressed the mitochondrial activity of fibroblasts (by 30-65% of controls). The concentration of metal-APT materials required to suppress cellular mitochondrial activity was below that required for metals alone, suggesting that simple extracellular release of the metals from the metal-APT materials was not the primary mechanism of mitochondrial suppression. In contrast to fibroblasts, no metal-APT material had a measurable effect on THP1 monocyte mitochondrial activity, despite potent suppression by metals alone. This latter result suggested that 'biodelivery' by metal-APT materials may be cell type-specific. Therefore, it appears that APT are plausible solid phase delivery agents of metals or metal compounds to some types of cells for potential therapeutic effect.

Purification of uranium metal

International Nuclear Information System (INIS)

Suzuki, Kenji; Shikama, Tatsuo; Ochiai, Akira.

1993-01-01

We developed the system for purifying uranium metal and its metallic compounds and for growing highly pure uranium compounds to study their intrinsic physical properties. Uranium metal was zone refined under low contamination conditions as far as possible. The degree of the purity of uranium metal was examined by the conventional electrical resistivity measurement and by the chemical analysis using the inductive coupled plasma emission spectrometry (ICP). The results show that some metallic impurities evaporated by the r.f. heating and other usual metallic impurities moved to the end of a rod with a molten zone. Therefore, we conclude that the zone refining technique is much effective to the removal of metallic impurities and we obtained high purified uranium metal of 99.99% up with regarding to metallic impurities. The maximum residual resistivity ratio, the r.r.r., so far obtained was about 17-20. Using the purified uranium, we are attempting to grow a highly pure uranium-titanium single crystals. (author)

Thermomechanical processing of plasma sprayed intermetallic sheets

Science.gov (United States)

Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

2001-01-01

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Dry metal forming of high alloy steel using laser generated aluminum bronze tools

Directory of Open Access Journals (Sweden)

Freiße Hannes

2015-01-01

Full Text Available Regarding the optimization of forming technology in economic and environmental aspects, avoiding lubricants is an approach to realize the vision of a new green technology. The resulting direct contact between the tool and the sheet in non-lubricated deep drawing causes higher stress and depends mainly on the material combination. The tribological system in dry sliding has to be assessed by means on the one hand of the resulting friction coefficient and on the other hand of the wear of the tool and sheet material. The potential to generate tailored tribological systems for dry metal forming could be shown within the investigations by using different material combinations and by applying different laser cladding process parameters. Furthermore, the feasibility of additive manufacturing of a deep drawing tool was demonstrated. The tool was successfully applied to form circular cups in a dry metal forming process.

Bioremediation of Heavy Metals and Organic Toxicants by Composting

Directory of Open Access Journals (Sweden)

Allen V. Barker

2002-01-01

Full Text Available Hazardous organic and metallic residues or by-products can enter into plants, soils, and sediments from processes associated with domestic, municipal, agricultural, industrial, and military activities. Handling, ingestion, application to land or other distributions of the contaminated materials into the environment might render harm to humans, livestock, wildlife, crops, or native plants. Considerable remediation of the hazardous wastes or contaminated plants, soils, and sediments can be accomplished by composting. High microbial diversity and activity during composting, due to the abundance of substrates in feedstocks, promotes degradation of xenobiotic organic compounds, such as pesticides, polycyclic aromatic hydrocarbons (PAHs, and polychlorinated biphenyls (PCBs. For composting of contaminated soils, noncontaminated organic matter should be cocomposted with the soils. Metallic pollutants are not degraded during composting but may be converted into organic combinations that have less bioavailability than mineral combinations of the metals. Degradation of organic contaminants in soils is facilitated by addition of composted or raw organic matter, thereby increasing the substrate levels for cometabolism of the contaminants. Similar to the composting of soils in vessels or piles, the on-site addition of organic matter to soils (sheet composting accelerates degradation of organic pollutants and binds metallic pollutants. Recalcitrant materials, such as organochlorines, may not undergo degradation in composts or in soils, and the effects of forming organic complexes with metallic pollutants may be nonpermanent or short lived. The general conclusion is, however, that composting degrades or binds pollutants to innocuous levels or into innocuous compounds in the finished product.

Recycled Cell Phones - A Treasure Trove of Valuable Metals

Science.gov (United States)

Sullivan, Daniel E.

2006-01-01

This U.S. Geological Survey (USGS) Fact Sheet examines the potential value of recycling the metals found in obsolete cell phones. Cell phones seem ubiquitous in the United States and commonplace throughout most of the world. There were approximately 1 billion cell phones in use worldwide in 2002. In the United States, the number of cell phone subscribers increased from 340,000 in 1985 to 180 million in 2004. Worldwide, cell phone sales have increased from slightly more than 100 million units per year in 1997 to an estimated 779 million units per year in 2005. Cell phone sales are projected to exceed 1 billion units per year in 2009, with an estimated 2.6 billion cell phones in use by the end of that year. The U.S. Environmental Protection Agency estimated that, by 2005, as many as 130 million cell phones would be retired annually in the United States. The nonprofit organization INFORM, Inc., anticipated that, by 2005, a total of 500 million obsolete cell phones would have accumulated in consumers' desk drawers, store rooms, or other storage, awaiting disposal. Typically, cell phones are used for only 1 1/2 years before being replaced. Less than 1 percent of the millions of cell phones retired and discarded annually are recycled. When large numbers of cell phones become obsolete, large quantities of valuable metals end up either in storage or in landfills. The amount of metals potentially recoverable would make a significant addition to total metals recovered from recycling in the United States and would supplement virgin metals derived from mining.

Hybrid microcircuit metallization system for the SLL micro actuator

International Nuclear Information System (INIS)

Hampy, R.E.; Knauss, G.L.; Komarek, E.E.; Kramer, D.K.; Villaueva, J.

1976-03-01

A thin film technique developed for the SLL Micro Actuator in which both gold and aluminum can be incorporated on sapphire or fine grained alumina substrates in a two-level metallization system is described. Tungsten is used as a lateral transition metal permitting electrical contact between the gold and aluminum without the two metals coming in physical contact. Silicon dioxide serves as an insulator between the tungsten and aluminum for crossover purposes, and vias through the silicon dioxide permit interconnections where desired. Tungsten-gold is the first level conductor except at crossovers where tungsten only is used and aluminum is the second level conductor. Sheet resistances of the two levels can be as low as 0.01 ohm/square. Line widths and spaces as small as 0.025 mm can be attained. A second layer of silicon dioxide is deposited over the metallization and opened for all gold and aluminum bonding areas. The metallization system permits effective interconnection of a mixture of devices having both gold and aluminum terminations without creating undesirable gold-aluminum interfaces. Processing temperatures up to 400 0 C can be tolerated for short times without effect on bondability, conductor, and insulator characteristics, thus permitting silicon-gold eutectic die attachment, component soldering, and higher temperatures during gold lead bonding. Tests conducted on special test pattern circuits indicate good stability over the temperature range -55 to +150 0 C. Aging studies indicate no degradation in characteristics in tests of 500 h duration at 150 0 C

TiO2 structures doped with noble metals and/or graphene oxide to improve the photocatalytic degradation of dichloroacetic acid.

Science.gov (United States)

Ribao, Paula; Rivero, Maria J; Ortiz, Inmaculada

2017-05-01

Noble metals have been used to improve the photocatalytic activity of TiO 2 . Noble metal nanoparticles prevent charge recombination, facilitating electron transport due to the equilibration of the Fermi levels. Furthermore, noble metal nanoparticles show an absorption band in the visible region due to a high localized surface plasmon resonance (LSPR) effect, which contributes to additional electron movements. Moreover, systems based on graphene, titanium dioxide, and noble metals have been used, considering that graphene sheets can carry charges, thereby reducing electron-hole recombination, and can be used as substrates of atomic thickness. In this work, TiO 2 -based nanocomposites were prepared by blending TiO 2 with noble metals (Pt and Ag) and/or graphene oxide (GO). The nanocomposites were mainly characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman spectroscopy, and photocurrent analysis. Here, the photocatalytic performance of the composites was analyzed via oxidizing dichloroacetic acid (DCA) model solutions. The influence of the noble metal load on the composite and the ability of the graphene sheets to improve the photocatalytic activity were studied, and the composites doped with different noble metals were compared. The results indicated that the platinum structures show the best photocatalytic degradation, and, although the presence of graphene oxide in the composites is supposed to enhance their photocatalytic performance, graphene oxide does not always improve the photocatalytic process. Graphical abstract It is a schematic diagram. Where NM is Noble Metal and LSPR means Localized Surface Plasmon Resonance.

Polymer-metal hybrid transparent electrodes for flexible electronics

Science.gov (United States)

Kang, Hongkyu; Jung, Suhyun; Jeong, Soyeong; Kim, Geunjin; Lee, Kwanghee

2015-03-01

Despite nearly two decades of research, the absence of ideal flexible and transparent electrodes has been the largest obstacle in realizing flexible and printable electronics for future technologies. Here we report the fabrication of ‘polymer-metal hybrid electrodes’ with high-performance properties, including a bending radius 95% and a sheet resistance solar cells that exhibit a high power conversion efficiency of 10% and polymer light-emitting diodes that can outperform those based on transparent conducting oxides.

Corrosion of valve metals

International Nuclear Information System (INIS)

Draley, J.E.

1976-01-01

A general survey related to the corrosion of valve metals or film-forming metals. The way these metals corrode with some general examples is described. Valve metals form relatively perfect oxide films with little breakdown or leakage when anodized

Metal Nitrides for Plasmonic Applications

DEFF Research Database (Denmark)

Naik, Gururaj V.; Schroeder, Jeremy; Guler, Urcan

2012-01-01

Metal nitrides as alternatives to metals such as gold could offer many advantages when used as plasmonic material. We show that transition metal nitrides can replace metals providing equally good optical performance for many plasmonic applications.......Metal nitrides as alternatives to metals such as gold could offer many advantages when used as plasmonic material. We show that transition metal nitrides can replace metals providing equally good optical performance for many plasmonic applications....

Effect of Thermal Cycling on the Tensile Behavior of CF/AL Fiber Metal Laminates

Directory of Open Access Journals (Sweden)

Muhammad Farhan Noor

2017-09-01

Full Text Available The objective of this research work was to estimate the effect of thermal cycling on the tensile behavior of CARALL composites. Fiber metal laminates (FMLs, based on 2D woven carbon fabric and 2024-T3 Alclad aluminum alloy sheet, was manufactured by pressure molding technique followed by hand layup method. Before fabrication, aluminum sheets were anodized with phosphoric acid to produce micro porous alumina layer on surface. This micro-porous layer is beneficial to produce strong bonding between metal and fiber surfaces in FMLs. The effect of thermal cycling (-65 to +70ºC on the tensile behavior of Cf/Al based FML was studied. Tensile strength was increased after 10 thermal cycles, but it was slightly decreased to some extent after 30, and 50 thermal cycles. Tensile modulus also shown the similar behavior as that of tensile strength.

Metallic DFB lasers

NARCIS (Netherlands)

Marell, M.J.H.; Nötzel, R.; Smit, M.K.; Hill, M.T.; Pozo, J.; Mortensen, M.; Urbach, P.; Leijtens, X.; Yousefi, M.

2010-01-01

In this paper we present our latest results on the design, fabrication and characterization of metal coated DFB lasers. These devices are based on a specialform of the metal-insulator-metal waveguides, which support plasmon gap modes. The distributed feedback provides control over the laser ~

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

Electrical transport through a metal-molecule-metal junction; Transport electrique a travers une jonction metal-molecule-metal

Energy Technology Data Exchange (ETDEWEB)

Kergueris, Ch

1998-12-17

We investigate the electrical transport through a very few molecules connected to metallic electrodes at room temperature. First, the state of the art in molecular electronics is outlined. We present the most convincing molecular devices reported so far in the literature and the theoretical tools available to analyze the electron transport mechanism through a molecular junction. Second, we describe the use of mechanically controllable break junctions to investigate the electron transport properties through a metal-molecule-metal junction. Two kindsof molecules were adsorbed on the two facing gold electrodes, dodecane-thiol (DT) and bis-thiol-ter-thiophene ({alpha},{omega} T3), that are basically expected to behave as an insulator and as a molecular wire, respectively. In the latter case, we study the chemical reactivity of the molecule and show that {alpha},{omega} T3 is chemically adsorbed on gold electrodes. Current-voltage characteristics of the junction were observed at room temperature. The Gold-DT-Gold junction behaves as a simple metal-insulator-metal junction. On the other hand, the electron transport through a Gold-{alpha},{omega} T3-Gold junction explicitly involves the electronic structure of the molecule which gives rise to step-like features in the current-voltage characteristics. The measured zero bias conductance is interpreted using the scattering theory. At high bias, we discuss two different models: a coherent model where the electron has no time to be completely re-localized in the molecule and a sequential model where the electron is localized in the molecule during the transfer. Finally, we show that the mechanical action of decreasing the inter-electrodes spacing can be used to induce a strong modification of the current-voltage characteristics. (author)

Nanochemistry of metals

International Nuclear Information System (INIS)

Sergeev, Gleb B

2001-01-01

The results of studies on the nanochemistry of metals published in recent years are generalised. Primary attention is centred on the methods for the synthesis of nanoparticles and their chemical reactions. The means of stabilisation of nanoparticles which involve individual metals and incorporate atoms of several metals are considered as well as their physicochemical properties. Self-assembling processes of nanoparticles are described. The prospects of using metal nanoparticles in semiconductor devices, catalysis, biology and medicine are discussed. The bibliography includes 165 references.

Inert anode containing base metal and noble metal useful for the electrolytic production of aluminum

Science.gov (United States)

Ray, Siba P.; Liu, Xinghua

2000-01-01

An inert anode for production of metals such as aluminum is disclosed. The inert anode comprises a base metal selected from Cu and Ag, and at least one noble metal selected from Ag, Pd, Pt, Au, Rh, Ru, Ir and Os. The inert anode may optionally be formed of sintered particles having interior portions containing more base metal than noble metal and exterior portions containing more noble metal than base metal. In a preferred embodiment, the base metal comprises Cu, and the noble metal comprises Ag, Pd or a combination thereof.

Metal-metal interaction mediates the iron induction of Drosophila MtnB

International Nuclear Information System (INIS)

Qiang, Wenjia; Huang, Yunpeng; Wan, Zhihui; Zhou, Bing

2017-01-01

Metallothionein (MT) protein families are a class of small and universal proteins rich in cysteine residues. They are synthesized in response to heavy metal stresses to sequester the toxic ions by metal-thiolate bridges. Five MT family members, namely MtnA, MtnB, MtnC, MtnD and MtnE, have been discovered and identified in Drosophila. These five isoforms of MTs are regulated by metal responsive transcription factor dMTF-1 and play differentiated but overlapping roles in detoxification of metal ions. Previous researches have shown that Drosophila MtnB responds to copper (Cu), cadmium (Cd) and zinc (Zn). Interestingly in this study we found that Drosophila MtnB expression also responds to elevated iron levels in the diet. Further investigations revealed that MtnB plays limited roles in iron detoxification, and the direct binding of MtnB to ferrous iron in vitro is also weak. The induction of MtnB by iron turns out to be mediated by iron interference of other metals, because EDTA at even a partial concentration of that of iron can suppress this induction. Indeed, in the presence of iron, zinc homeostasis is altered, as reflected by expression changes of zinc transporters dZIP1 and dZnT1. Thus, iron-mediated MtnB induction appears resulting from interrupted homeostasis of other metals such as zinc, which in turns induced MtnB expression. Metal-metal interaction may more widely exist than we expected. - Highlights: • Metallothionein B expression is regulated by iron in Drosophila melanogaster. • MtnB has limited physiological roles in iron detoxification. • Binding affinity of MtnB to iron is weak in vitro. • Induction of Drosophila MtnB by iron is mediated indirectly through metal-metal interaction.

Flow channel shape optimum design for hydroformed metal bipolar plate in PEM fuel cell

Energy Technology Data Exchange (ETDEWEB)

Peng, Linfa; Lai, Xinmin; Liu, Dong' an; Hu, Peng [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240 (China); Ni, Jun [Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, MI 48109 (United States)

2008-03-15

Bipolar plate is one of the most important and costliest components of polymer electrolyte membrane (PEM) fuel cells. Micro-hydroforming is a promising process to reduce the manufacturing cost of PEM fuel cell bipolar plates made of metal sheets. As for hydroformed bipolar plates, the main defect is the rupture because of the thinning of metal sheet during the forming process. The flow channel section decides whether high quality hydroformed bipolar plates can be successively achieved or not. Meanwhile, it is also the key factor that is related with the reaction efficiency of the fuel cell stacks. In order to obtain the optimum flow channel section design prior the experimental campaign, some key geometric dimensions (channel depth, channel width, rib width and transition radius) of flow channel section, which are related with both reaction efficiency and formability, are extracted and parameterized as the design variables. By design of experiments (DOE) methods and an adoptive simulated annealing (ASA) optimization method, an optimization model of flow channel section design for hydroformed metal bipolar plate is proposed. Optimization results show that the optimum dimension values for channel depth, channel width, rib width and transition radius are 0.5, 1.0, 1. 6 and 0.5 mm, respectively with the highest reaction efficiency (79%) and the acceptable formability (1.0). Consequently, their use would lead to improved fuel cell efficiency for low cost hydroformed metal bipolar plates. (author)

Metallic glass coating on metals plate by adjusted explosive welding technique

International Nuclear Information System (INIS)

Liu, W.D.; Liu, K.X.; Chen, Q.Y.; Wang, J.T.; Yan, H.H.; Li, X.J.

2009-01-01

Using an adjusted explosive welding technique, an aluminum plate has been coated by a Fe-based metallic glass foil in this work. Scanning electronic micrographs reveal a defect-free metallurgical bonding between the Fe-based metallic glass foil and the aluminum plate. Experimental evidence indicates that the Fe-based metallic glass foil almost retains its amorphous state and mechanical properties after the explosive welding process. Additionally, the detailed explosive welding process has been simulated by a self-developed hydro-code and the bonding mechanism has been investigated by numerical analysis. The successful welding between the Fe-based metallic glass foil and the aluminum plate provides a new way to obtain amorphous coating on general metal substrates.

Fabrication of Metallic Hollow Nanoparticles

Science.gov (United States)

Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2016-01-01

Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

Metals and Neurodegeneration

Science.gov (United States)

Chen, Pan; Miah, Mahfuzur Rahman; Aschner, Michael

2016-01-01

Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain–Barré disease, Gulf War syndrome, Huntington’s disease, multiple sclerosis, Parkinson’s disease, and Wilson’s disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration. PMID:27006759

Charging damage in floating metal-insulator-metal capacitors

NARCIS (Netherlands)

Ackaert, Jan; Wang, Zhichun; De Backer, E.; Coppens, P.

2002-01-01

In this paper, charging induced damage (CID) to metal-insulator-metal capacitors (MIMC) is reported. The damage is caused by the build up of a voltage potential difference between the two plates of the capacitor. A simple logarithmic relation is discovered between the damage by this voltage

Liquid metal purification device

International Nuclear Information System (INIS)

Sakai, Takao; Shimoyashiki, Shigehiro.

1992-01-01

The device of the present invention concerns a liquid metal purification device for removing and purifying impuries in liquid metal sodium used as coolants of an FBR type reactor. A vessel having a group of pipes made of hydrogen permeable metal at the inside thereof is disposed to the inlet pipeline of a cold trap. The group of hydrogen permeable metal pipes is connected to an exhaust pipe and a vacuum pump, so that the inside of the pipes is exhausted. Liquid metal sodium branched from the main pipeline of a coolant system passes through the outer side of the group of the hydrogen permeable metal pipes. In this cae, hydrogen contained as impurities in the liquid metal sodium diffuses and permeates the hydrogen permeation metal pipes and enters into the pipe group and is discharged out of the system by the vacuum pump. This can mitigate the hydrogen removing burden of the cold trap, to extend the device life time. (I.N.)

Casimir interactions between graphene sheets and metamaterials

International Nuclear Information System (INIS)

Drosdoff, D.; Woods, Lilia M.

2011-01-01

The Casimir force between graphene sheets and metamaterials is studied. Theoretical results based on the Lifshitz theory for layered, planar, two-dimensional systems in media are presented. We consider graphene-graphene, graphene-metamaterial, and metal-graphene-metamaterial configurations. We find that quantum effects of the temperature-dependent force are not apparent until the submicron range. In contrast to results with bulk dielectric and bulk metallic materials, no Casimir repulsion is found when graphene is placed on top of a magnetically active metamaterial substrate, regardless of the strength of the low-frequency magnetic response. In the case of the metal-graphene-metamaterial setting, repulsion between the metamaterial and the metal-graphene system is possible only when the dielectric response from the metal contributes significantly.

Inflammatory pseudotumor causing deep vein thrombosis after metal-on-metal hip resurfacing arthroplasty.

LENUS (Irish Health Repository)

Memon, Adeel Rasool

2013-01-01

Metal-on-metal hip resurfacings have recently been associated with a variety of complications resulting from adverse reaction to metal debris. We report a case of extensive soft tissue necrosis associated with a huge pelvic mass causing extensive deep vein thrombosis of the lower limb secondary to mechanical compression of the iliac vein. This is a rare and unusual cause of deep vein thrombosis after metal-on-metal hip resurfacing arthroplasty.

Deposition of metal Islands, metal clusters and metal containing single molecules on self-assembled monolayers

NARCIS (Netherlands)

Speets, Emiel Adrianus

2005-01-01

The central topic of this thesis is the deposition of metals on Self-Assembled Monolayers (SAMs). Metals are deposited in the form of submicron scale islands, nanometer scale clusters, and as supramolecular, organometallic coordination cages. Several SAMs on various substrates were prepared and

Metal interactions with boron clusters

International Nuclear Information System (INIS)

Grimes, R.N.

1982-01-01

This book presents information on the following topics: the structural and bonding features of metallaboranes and metallacarboranes; transition-metal derivatives of nido-boranes and some related species; interactions of metal groups with the octahydrotriborate (1-) anion, B 3 H 8 ; metallaboron cage compounds of the main group metals; closo-carborane-metal complexes containing metal-carbon and metal-boron omega-bonds; electrochemistry of metallaboron cage compounds; and boron clusters with transition metal-hydrogen bonds

Fatal Cobalt Toxicity after a Non-Metal-on-Metal Total Hip Arthroplasty

Directory of Open Access Journals (Sweden)

Rinne M. Peters

2017-01-01

Full Text Available This case illustrates the potential for systemic cobalt toxicity in non-metal-on-metal bearings and its potentially devastating consequences. We present a 71-year-old male with grinding sensations in his right hip following ceramic-on-ceramic total hip arthroplasty (THA. After diagnosing a fractured ceramic liner, the hip prosthesis was revised into a metal-on-polyethylene bearing. At one year postoperatively, X-rays and MARS-MRI showed a fixed reversed hybrid THA, with periarticular densities, flattening of the femoral head component, and a pattern of periarticular metal wear debris and pseudotumor formation. Before revision could take place, the patient was admitted with the clinical picture of systemic cobalt toxicity, supported by excessively high serum cobalt and chromium levels, and ultimately died. At autopsy dilated cardiomyopathy as cause of death was hypothesized. A third body wear reaction between ceramic remnants and the metal femoral head very likely led to excessive metal wear, which contributed systemic cobalt toxicity leading to neurotoxicity and heart failure. This case emphasizes that fractured ceramic-on-ceramic bearings should be revised to ceramic-on-ceramic or ceramic-on-polyethylene bearings, but not to metal-on-polyethylene bearings. We aim to increase awareness among orthopedic surgeons for clinical clues for systemic cobalt intoxication, even when there is no metal-on-metal bearing surface.

Plasma damage in floating metal-insulator-metal capacitors

NARCIS (Netherlands)

Ackaert, Jan; Wang, Zhichun; De Backer, E.; Coppens, P.

2002-01-01

In this paper, charging induced damage (CID) to metal-insulator-metal capacitors (MIMCs), is reported. CID does not necessarily lead to direct yield loss, but may also induce latent damage leading to reliability losses. The damage is caused by the build up of a voltage potential difference between

Plasma Damage in Floating Metal-Insulator-Metal Capacitors

NARCIS (Netherlands)

Ackaert, Jan; Wang, Zhichun; Backer, E.; Coppens, P.

2001-01-01

In this paper, charging induced damage (CID) to metal-insulator-metal capacitors (MIMCs), is reported. CID does not necessarily lead to direct yield loss, but may also induce latent damage leading to reliability losses. The damage is caused by the build up of a voltage potential difference between

Chromium metal organic frameworks and synthesis of metal organic frameworks

Science.gov (United States)

Zhou, Hong-Cai; Liu, Tian-Fu; Lian, Xizhen; Zou, Lanfang; Feng, Dawei

2018-04-24

The present invention relates to monocrystalline metal organic frameworks comprising chromium ions and carboxylate ligands and the use of the same, for example their use for storing a gas. The invention also relates to methods for preparing metal organic frameworks comprising chromium, titanium or iron ions and carboxylate ligands. The methods of the invention allow such metal organic frameworks to be prepared in monocrystalline or polycrystalline forms.

Progress in metal-insulator-metal waveguide lasers at near-infrared wavelengths

NARCIS (Netherlands)

Marell, M.J.H.; Hill, M.T.

2009-01-01

Strong light con¯nement can be achieved in metallic cavities which can con¯ne light to volumes with dimensions considerably smaller than the wavelength of light. It was commonly believed, however, that the high losses in metals are prohibitive for laser peration in metallic nano-cavities. Recently

Synthesis, Characterization, and Ultrafast Dynamics of Metal, Metal Oxide, and Semiconductor Nanomaterials

OpenAIRE

Wheeler, Damon Andreas

2013-01-01

SYNTHESIS, CHARACTERIZATION, AND ULTRAFAST DYNAMICS OF METAL, METAL OXIDE, AND SEMICONDUCTOR NANOMATERIALSABSTRACTThe optical properties of each of the three main classes of inorganic nanomaterials, metals, metal oxides, and semiconductors differ greatly due to the intrinsically different nature of the materials. These optical properties are among the most fascinating and useful aspects of nanomaterials with applications spanning cancer treatment, sensors, lasers, and solar cells. One techn...

Metal uptake and acute toxicity in zebrafish: Common mechanisms across multiple metals

Energy Technology Data Exchange (ETDEWEB)

Alsop, Derek, E-mail: alsopde@mcmaster.ca [Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1 (Canada); Wood, Chris M. [Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1 (Canada)

2011-10-15

All metals tested reduced calcium uptake in zebrafish larvae. However, it was whole body sodium loss that was functionally related to toxicity. The zebrafish larvae acute toxicity assay save time, space and resources. - Abstract: Zebrafish larvae (Danio rerio) were used to examine the mechanisms of action and acute toxicities of metals. Larvae had similar physiological responses and sensitivities to waterborne metals as adults. While cadmium and zinc have previously been shown to reduce Ca{sup 2+} uptake, copper and nickel also decreased Ca{sup 2+} uptake, suggesting that the epithelial transport of all these metals is through Ca{sup 2+} pathways. However, exposure to cadmium, copper or nickel for up to 48 h had little or no effect on total whole body Ca{sup 2+} levels, indicating that the reduction of Ca{sup 2+} uptake is not the acute toxic mechanism of these metals. Instead, mortalities were effectively related to whole body Na{sup +}, which decreased up to 39% after 48 h exposures to different metals around their respective 96 h LC50s. Decreases in whole body K{sup +} were also observed, although they were not as pronounced or frequent as Na{sup +} losses. None of the metals tested inhibited Na{sup +} uptake in zebrafish (Na{sup +} uptake was in fact increased with exposure) and the observed losses of Na{sup +}, K{sup +}, Ca{sup 2+} and Mg{sup 2+} were proportional to the ionic gradients between the plasma and water, indicating diffusive ion loss with metal exposure. This study has shown that there is a common pathway for metal uptake and a common mechanism of acute toxicity across groups of metals in zebrafish. The disruption of ion uptake accompanying metal exposure does not appear to be responsible for the acute toxicity of metals, as has been previously suggested, but rather the toxicity is instead due to total ion loss (predominantly Na{sup +}).

Thin lead sheets in the decorative features in Pavia Charterhouse.

Science.gov (United States)

Colombo, Chiara; Realini, Marco; Sansonetti, Antonio; Rampazzi, Laura; Casadio, Francesca

2006-01-01

The facade of the church of the Pavia Charterhouse, built at the end of the 15th century, shows outstanding decorative features made of different stone materials, such as marbles, breccias and sandstones. Magnificent ornamental elements are made of thin lead sheets, and some marble slabs are inlaid with them. Metal elements are shaped in complex geometric and phytomorphic design, to form a Greek fret in black contrasting with the white Carrara marble. Lead pins were fixed to the back of the thin lead sheets with the aim of attaching the metal elements to the marble; in so doing the pins and the lead sheets constitute a single piece of metal. In some areas, lead elements have been lost, and they have been substituted with a black plaster, matching the colour of the metal. To the authors' knowledge, this kind of decorative technique is rare, and confirms the refinement of Renaissance Lombard architecture. This work reports on the results of an extensive survey of the white, orange and yellowish layers, which are present on the external surface of the lead. The thin lead sheets have been characterized and their state of conservation has been studied with the aid of Optical Microscopy, SEM-EDS, FTIR and Raman analyses. Lead sulphate, lead carbonates and oxides have been identified as decay products.

21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint metal/polymer/metal semi-constrained... Devices § 888.3358 Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis. (a) Identification. A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a device...

Static and Dynamic Behavior of High Modulus Hybrid Boron/Glass/Aluminum Fiber Metal Laminates

Science.gov (United States)

Yeh, Po-Ching

2011-12-01

This dissertation presents the investigation of a newly developed hybrid fiber metal laminates (FMLs) which contains commingled boron fibers, glass fibers, and 2024-T3 aluminum sheets. Two types of hybrid boron/glass/aluminum FMLs are developed. The first, type I hybrid FMLs, contained a layer of boron fiber prepreg in between two layers of S2-glass fiber prepreg, sandwiched by two aluminum alloy 2024-T3 sheets. The second, type II hybrid FMLs, contained three layer of commingled hybrid boron/glass fiber prepreg layers, sandwiched by two aluminum alloy 2024-T3 sheets. The mechanical behavior and deformation characteristics including blunt notch strength, bearing strength and fatigue behavior of these two types of hybrid boron/glass/aluminum FMLs were investigated. Compared to traditional S2-glass fiber reinforced aluminum laminates (GLARE), the newly developed hybrid boron/glass/aluminum fiber metal laminates possess high modulus, high yielding stress, and good blunt notch properties. From the bearing test result, the hybrid boron/glass/aluminum fiber metal laminates showed outstanding bearing strength. The high fiber volume fraction of boron fibers in type II laminates lead to a higher bearing strength compared to both type I laminates and traditional GLARE. Both types of hybrid FMLs have improved fatigue crack initiation lives and excellent fatigue crack propagation resistance compared to traditional GLARE. The incorporation of the boron fibers improved the Young's modulus of the composite layer in FMLs, which in turn, improved the fatigue crack initiation life and crack propagation rates of the aluminum sheets. Moreover, a finite element model was established to predict and verify the properties of hybrid boron/glass/aluminum FMLs. The simulated results showed good agreement with the experimental results.

Metal Matrix Composite Material by Direct Metal Deposition

Science.gov (United States)

Novichenko, D.; Marants, A.; Thivillon, L.; Bertrand, P. H.; Smurov, I.

Direct Metal Deposition (DMD) is a laser cladding process for producing a protective coating on the surface of a metallic part or manufacturing layer-by-layer parts in a single-step process. The objective of this work is to demonstrate the possibility to create carbide-reinforced metal matrix composite objects. Powders of steel 16NCD13 with different volume contents of titanium carbide are tested. On the base of statistical analysis, a laser cladding processing map is constructed. Relationships between the different content of titanium carbide in a powder mixture and the material microstructure are found. Mechanism of formation of various precipitated titanium carbides is investigated.

Polymer-supported metals and metal oxide nanoparticles: synthesis, characterization, and applications

International Nuclear Information System (INIS)

Sarkar, Sudipta; Guibal, E.; Quignard, F.; SenGupta, A. K.

2012-01-01

Metal and metal oxide nanoparticles exhibit unique properties in regard to sorption behaviors, magnetic activity, chemical reduction, ligand sequestration among others. To this end, attempts are being continuously made to take advantage of them in multitude of applications including separation, catalysis, environmental remediation, sensing, biomedical applications and others. However, metal and metal oxide nanoparticles lack chemical stability and mechanical strength. They exhibit extremely high pressure drop or head loss in fixed-bed column operation and are not suitable for any flow-through systems. Also, nanoparticles tend to aggregate; this phenomenon reduces their high surface area to volume ratio and subsequently reduces effectiveness. By appropriately dispersing metal and metal oxide nanoparticles into synthetic and naturally occurring polymers, many of the shortcomings can be overcome without compromising the parent properties of the nanoparticles. Furthermore, the appropriate choice of the polymer host with specific functional groups may even lead to the enhancement of the properties of nanoparticles. The synthesis of hybrid materials involves two broad pathways: dispersing the nanoparticles (i) within pre-formed or commercially available polymers; and (ii) during the polymerization process. This review presents a broad coverage of nanoparticles and polymeric/biopolymeric host materials and the resulting properties of the hybrid composites. In addition, the review discusses the role of the Donnan membrane effect exerted by the host functionalized polymer in harnessing the desirable properties of metal and metal oxide nanoparticles for intended applications.

Separating and recycling metals from mixed metallic particles of crushed electronic wastes by vacuum metallurgy.

Science.gov (United States)

Zhan, Lu; Xu, Zhenming

2009-09-15

During the treatment of electronic wastes, a crushing process is usually used to strip metals from various base plates. Several methods have been applied to separate metals from nonmetals. However, mixed metallic particles obtained from these processes are still a mixture of various metals, including some toxic heavy metals such as lead and cadmium. With emphasis on recovering copper and other precious metals, there have hitherto been no satisfactory methods to recover these toxic metals. In this paper, the criterion of separating metals from mixed metallic particles by vacuum metallurgy is built. The results show that the metals with high vapor pressure have been almost recovered completely, leading to a considerable reduction of environmental pollution. In addition, the purity of copper in mixed particles has been improved from about 80 wt % to over 98 wt %.

Metal contamination in water sediments; Contaminacion por metales en sedimentos acuaticos

Energy Technology Data Exchange (ETDEWEB)

Usero Garcia, J.; Morillo Aguado, J.; Gracia Manarillo, I. [Universidad de Sevilla. Sevilla (Spain)

1997-09-01

The origin, distribution, and behaviour of metals in aquatic systems, and factors affecting the solubilization and entry into the water column of metals associated with sediments are examined. Also, the interaction of these metals with and toxic effects on living organisms are studied. Finally, the existing methods for assessing the degree of pollution of sediments and the mobility of the metals associated with the sediments are explained. In the second section of this paper, the methods used for sampling, preparing, and analysing the sediments are described. (Author) 48 refs.

Lotus-like effect for metal filings recovery and particle removal on heated metal surfaces using Leidenfrost water droplets.

Science.gov (United States)

Tan, Cher Lin Clara; Sapiha, Kostantyn; Leong, Yoke Fun Hannah; Choi, Siwon; Anariba, Franklin; Thio, Beng Joo Reginald

2015-07-21

A "lotus-like" effect is applied to demonstrate the ability of the Leidenfrost water droplets to recover Cu particles on a heated Al substrate. Cu particles on the heated surface adhere to the rim of the Leidenfrost droplets and eventually coat the droplets' surface to form an aggregation. When Fe filings are added to the Cu particles, the aggregated mixture can then be collected using a strong rare earth magnet (NdFeB) upon evaporation of the water. We also show that the Leidenfrost effect can be effectively utilized to recover both hydrophobic (dust and activated carbon) and hydrophilic (SiO2 and MgO) particles from heated Al surfaces without any topographical modification or surfactant addition. Our results show that hydrophobic and hydrophilic materials can be collected with >92% and >96% effectiveness on grooved and smooth Al surfaces, respectively. Furthermore, we observed no significant differences in the amount of material collected above the Leidenfrost point within the tested temperature range (240 °C vs. 340 °C) as well as when the Al sheet was replaced with a Cu sheet as the substrate. However, we did observe that the Leidenfrost droplets were able to collect a greater amount of material when the working liquid was water than when it was ethanol. Our findings show promise in the development of an effective precious coinage metal filings recovery technology for application in the mint industry, as well as the self-cleaning of metallic and semiconductor surfaces where manual cleaning is not amenable.

Rare-earth metal transition metal borocarbide and nitridoborate superconductors

Energy Technology Data Exchange (ETDEWEB)

Niewa, Rainer; Shlyk, Larysa; Blaschkowski, Bjoern [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

2011-07-01

Few years after the discovery of superconductivity in high-T{sub c} cuprates, borocarbides and shortly after nitridoborates with reasonably high T{sub c}s up to about 23 K attracted considerable attention. Particularly for the rare-earth metal series with composition RNi{sub 2}[B{sub 2}C] it turned out, that several members exhibit superconductivity next to magnetic order with both T{sub c} above or below the magnetic ordering temperature. Therefore, these compounds have been regarded as ideal materials to study the interplay and coexistence of superconductivity and long range magnetic order, due to their comparably high ordering temperatures and similar magnetic and superconducting condensation energies. This review gathers information on the series RNi{sub 2}[B{sub 2}C] and isostructural compounds with different transition metals substituting Ni as well as related series like RM[BC], RM[BN], AM[BN] and R{sub 3}M{sub 2}[BN]{sub 2}N (all with R = rare-earth metal, A = alkaline-earth metal, M = transition metal) with special focus on synthesis, crystal structures and structural trends in correspondence to physical properties. (orig.)

Propagation Characteristics of Multilayer Hybrid Insulator-Metal-Insulator and Metal-Insulator-Metal Plasmonic Waveguides

Directory of Open Access Journals (Sweden)

M. Talafi Noghani

2014-02-01

Full Text Available Propagation characteristics of symmetrical and asymmetrical multilayer hybrid insulator-metal-insulator (HIMI and metal-insulator-metal (HMIM plasmonic slab waveguides are investigated using the transfer matrix method. Propagation length (Lp and spatial length (Ls are used as two figures of merit to qualitate the plasmonic waveguides. Symmetrical structures are shown to be more performant (having higher Lp and lower Ls, nevertheless it is shown that usage of asymmetrical geometry could compensate for the performance degradation in practically realized HIMI waveguides with different substrate materials. It is found that HMIM slab waveguide could support almost long-range subdiffraction plasmonic modes at dimensions lower than the spatial length of the HIMI slab waveguide.

Heavy metal jako subkultura

OpenAIRE

KOUTNÁ, Daniela

2016-01-01

This bachelor thesis deals with heavy metal subculture. Its aim is to introduce the most important branches and to show broadness of heavy metal. This bachelor thesis describes development and history, briefly shows Czech heavy metal history alongside with the biggest and most popular Czech heavy metal festivals. It shows the most dressing concerns of society against this style.