bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlled Synthesis of Homogeneous Carbon Nano-Capsules Based on Biomaterials
Authors: An Yu Liang , Liu Yan Qiu , Yuan Xia
Published: March 2009

A novel and practical route for preparing carbon nanocapsules using biomass – starch as the starting materials was presented. Carbon nanocapsules can be effectively synthesized by catalytic carbonizing starch in hydrogen flow. The carbohydrate was carbonized in a controllable way that leads to a large amount of carbon cages nanoparticles under Fe catalyst. Transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) were employed to characterizing carbon nanomaterials. The growth mechanism of carbon nanocapsules is briefly discussed in term of composition of precursor.
Effect of Mineral Composite Materials with Far Infrared Radiation on Diesel Oil Combustion
Authors: Xue Gang , Wu Xiao Ming , Liang Jin Sheng , Ding Yan , Liu Li Hua
Published: March 2009

The powders of mineral materials with far infrared radiation (CTTP) were prepared using rare earth cerium nitrate, tourmaline and transition metal oxide by coprecipitation, and calcination at 1073K for 3h. The inorganic-organic mineral composite materials with far infrared radiation (CTTR) were prepared from CTTP and resin according to the weight ratio of 4:6. It was found by characterization with scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscope (FTIR), that the infrared radiance of the CTTR was 93%. The effects of the CTTR on the surface tension and the kinematic viscosity of diesel oil as well as the effects of the CTTR on oil consumption and air pollutant emissions of oil-burning boiler were investigated in this paper. The results showed that the diesel oil dealted with the CTTR resulted in the strengthenty of molecular movement and the decrease of intermolecular contacts. In laboratory, the surface tension of diesel oil was reduced from 27.287 to 27.254 mN/m and the kinematic viscosity of diesel oil was reduced from 2.85 to 2.81 mm2s-1. The oil-saving rate of the RBS•VH-1.5 boiler treated with the CTTR could reach 4.57%, and the reducing rates of CO and NO in the exhaust gas were 1.30 and 4.08%, respectively.
Impact Bending Tests on Selected Refractory Materials
Authors: Rieth Michael , Hoffmann Andreas
Published: March 2009

The possible use of tungsten alloys as structural materials in future fusion reactor divertors strongly depend on their ductile-to-brittle transition temperature (DBTT). The present paper gives an overview on different rod and plate materials fabricated by PLANSEE. It is demonstrated that DBTT is clearly improved compared to commercially available standard materials. Moreover, the significant impact of the microstructure on fracture mode and on toughness is discussed in detail.
Diamond-Based Metal Matrix Composites for Thermal Management Made by Liquid Metal Infiltration — Potential and Limits
Authors: Weber Ludger , Tavangar Reza
Published: March 2009

Diamond-based metal matrix composites have been made based on pure Al and eutectic Ag-3Si alloy by gas pressure infiltration into diamond powder beds with the aim to maximize thermal conductivity and to explore the range of coefficient of thermal expansion (CTE) that can be covered. The resulting composites covered roughly the range between 60 and 75 vol-% of diamond content. For the Al-based composites a maximum thermal conductivity at room temperature of 7.6 W/cmK is found while for the Ag-3Si based composites an unprecedented value of 9.7 W/cmK was achieved. The CTE at room temperature varied as a function of the diamond volume fraction between 3.3 and 7.0 ppm/K and 3.1 and 5.7 ppm/K for the Al-based and the Ag-3Si-based composites, respectively. The CTE was further found to vary quite significantly with temperature for the Al-based composites while the variation with temperature was less pronounced for the Ag-3Si-based composites. The results are compared with prediction by analytical modeling using the differential effective medium scheme for thermal conductivity and the Schapery bounds for the CTE. For the thermal conductivity good agreement is found while for the CTE a transition of the experimental data from Schapery’s upper to Schapery’s lower bound is observed as volume fraction increases. While the thermophysical properties are quite satisfactory, there is a trade-off to be made in these materials between high thermal conductivity and low CTE on the one side and surface quality and machinability on the other.
Comparative Study of Predictive Finite Element Methods for Mechanical Properties in 2D Woven Carbon/Carbon Composites
Authors: Ali Joshim , Buckthorpe Derek , Cheyne Allister , Farooqi Johar , Mummery Paul M.
Published: March 2009

Three-dimensional finite element (FE) methods are used to predict the Young’s modulus
of two types of 2D woven carbon/carbon composites. Tensile tests are performed to validate the
predictions. The results indicate that a novel image-based route in generating FE meshes gave
strong agreement with experimental data, while a comparative unit cell FE model of the structure
was found to be poorer. The differences between the image-based and unit cell methodologies were
the consideration of the finer architectures of the composites and their porosity. The image-based
approach highlighted true porosity in the structure due to meshes forming directly from X-ray
tomographic data. However, the finer fibre architectures of the composites were compromised
because of limitations in the pixel resolutions employed during the initial scanning process. In
comparison, the unit cell models were based solely on idealisations of the composite microstructure,
in which porosity was neglected.
Heat Sink Materials Processing by Pulse Plasma Sintering
Authors: Ciupiński Łukas , Siemiaszko D. , Rosiński Marcin , Michalski Andrzej , Kurzydlowski Krzysztof Jan
Published: March 2009

A Pulse Plasma Sintering (PPS) process was employed to manufacture Cu-diamond composites with a 50% volume fraction of each constituent. Pure and Cr (0.8wt.%) alloyed copper matrices were used and commercial diamond powders. The composites were sintered at temperature of 900°C for 20 min and under pressure of 60 MPa. In these sintering conditions diamond becomes thermodynamically unstable. Cu0.8Cr-diamond and Cu-diamond composites with relative densities of 99,7% and 96% respectively were obtained. The thermal conductivity of Cu0.8Cr-diamond composite is equal to 640 W(mK)-1 whereas that of Cu-diamond is 200 W(mK)-1. The high thermal conductivity and relative density of Cu0.8Cr-diamond composite is due to the formation of a thin chromium carbide layer at the Cu-diamond interface.
Diamond Composites for Power Electronics Application
Authors: Levchuk Svetlana , Poebl Monika , Mitic Gerhard
Published: March 2009

In view of power electronics applications, baseplates made from metal diamond composites have been manufactured and characterised. The surface contours of the baseplates were measured during thermal loads up to 180°C starting at room temperature with help of the TherMoiré technique. X-ray analysis investigation was performed to detect porosity and local inhomogeneities of the baseplates. Al- and Cu-based diamond composite baseplates were Ni-plated and used for manufacturing of 3.3 kV IGBT modules. The solder layer between AlN AMB (active metal brazing) substrates and baseplates was investigated by ultrasonic and X-Ray analyses. Thermal resistance of the manufactured IGBT modules was characterised and compared to that of IGBT modules with AlSiC or Cu baseplates. The influence of thermal cycling on the solder layer and thermal resistance of the manufactured module was investigated.
Micromechanical Model of Interface between Fibre and Matrix of Metal Matrix Composite Reinforced with Continuous Fibre
Authors: Ríos A. , Martín-Meizoso A.
Published: March 2009

A micromechanical model is employed to investigate the influence of the interface between the fibre and the matrix of a metal matrix composite with long fibre, which is elaborated through finite element method. Also, transverse properties of composite are studied in the present work. The interface, between the fibre and the matrix, is studied employing cohesive elements. These elements employ a cohesive zone model, which follows a bilinear law.
FEM Modeling of Structure and Properties of Diamond-SiC-(Al) Composites Developed for Thermal Management Applications
Authors: Unifantowicz Paulina , Boguszewski T. , Ciupiński Łukas , Fortuna E. , Lewandowska Małgorzata , Vaucher Sebastien , Kurzydlowski Krzysztof Jan
Published: March 2009

Thermal management materials frequently have multi-phase composite character with complex architecture of the constituents. As a result, design rules are needed which can be used in selection of the phases and optimizing their volume fractions. The study shows that such are provided by finite element modeling of these composites. This is demonstrated for a diamond-SiC-Si-(Al) composites, which have been optimized in terms of the volume fraction of SiC, contact area between the components and presence of open porosity.
Oxide Layer Formation by Micro-Arc Oxidation on Structurally Modified Al-Si Alloys and Applications for Large-Sized Articles Manufacturing
Authors: Krishtal Mikhail M.
Published: March 2009

The effect of the shape, size and kind of distribution of the silicon inclusions in Al-Si alloys of hypoeutectic, eutectic, and hypereutectic compositions (6–22 % Si) on the quality of oxide layer formed by micro-arc oxidation (MAO) is studied. The hitherto unknown phenomenon of oxide layer growth inhibition by the silicon particles under MAO is discovered and researched. The filling of near-surface pores by oxidation products in MAO process is observed also. The discovered ability to increase the properties of oxide layers obtained by the MAO due to prior directed modifica¬tion of the initial structure provides the good quality of oxide layers for aluminium alloys with high level of silicon content up to hypereutectic compositions of Al-Si alloys. The physical opportunity to get the high quality oxidized layers by MAO on structurally modified Al-Si alloys is confirmed for large-sized Al-Si alloys castings (including cylinder block for engine).
Joining of Superalloys to Intermetallics Using Nanolayers
Authors: Ramos Ana Sofia , Vieira Maria-Teresa Freire , Simões Sonia , Viana Filomena , Vieira Manuel F.
Published: March 2009

Joining nickel based superalloys to gamma-TiAl intermetallic alloys will contribute to a more efficient application of these advanced materials, particularly in extreme environments. In this study, Inconel alloy and gamma-TiAl are joined using as filler alternated nanolayer thin films deposited onto each base material. The nanolayers consisted in Ni/Al exothermic reactive multilayer thin films with periods of 5 and 14 nm deposited by d.c. magnetron sputtering in order to improve the adhesion to the substrates and to avoid the reaction between Ni and Al. Diffusion bonding experiments with multilayer coated alloys were performed under vacuum at 800°C by applying 50 MPa during 1h. Bonding was achieved in large areas of the centre of the joints where regions without cracks or pores were produced, especially when using multilayer thin films with a 14 nm modulation period.
Wetting and Fracture Characteristics of TiCx Coated C/Cu Braze Joints
Authors: Worbs Peter , Grattarola Marco , Maier Hans , Bolt Harald
Published: March 2009

Thin TiCx films with a range from pure Ti to stoichiometric TiC (0 ≤ x ≤ 1) have been deposited on carbon-based materials by dual magnetron sputter deposition. The wetting behaviour of a Cu Ti alloy on TiCx coatings has been characterized using the sessile drop method. For these experiments a contact angle measurement device was constructed and successfully tested. Both, stoichiometric TiC and Ti coatings improve wetting dramatically. In between there was no significant wetting improving effect compared to the uncoated case. Subsequently, TiCx coated C/Cu braze joints have been tested on their ability to withstand mechanical loads and analysed with respect to their fracture behaviour.
Nanoindentation and Micromechanical Testing of Iron-Chromium Alloys Implanted with Iron Ions
Authors: Halliday F.M. , Armstrong David E.J. , Murphy John D. , Roberts Steve G.
Published: March 2009

The mechanical properties of Fe-Cr alloys were investigated in as-grown and in post-ion-implanted conditions. Sets of specimens were produced using dual implantations of Fe+ ions to give 1µm deep damaged layers with average damage levels of 0.35 displacements per atom and 5.33 displacements per atom. Nanoindentation was used to measure hardness as a function of depth and showed that implanted material had a higher hardness than unimplanted material. Additionally, micron-scale cantilevers were fabricated from the ion-damaged surface of the material and were tested using a nanoindenter for AFM-imaging and loading. The mechanical properties deduced from the controlled loading of these cantilevers pertain only to radiation-damaged material, and for the high-dose material show significant changes in Young’s modulus, yield stress and work-hardening.
Bonding and Interfaces and their Thermo-Mechanical Performance on the Example of Plasma Facing Divertor Components for Thermo-Nuclear Fusion Reactors
Authors: Plankensteiner Arno , Tabernig Bernhard
Published: March 2009

The optimization of CFC/Cu-interfaces for plasma facing divertor components in thermo-nuclear fusion reactors is proposed and demonstrated via an integrative numerical-experimental approach mainly comprising a macro-scale to micro-scale finite element modeling technique together with fracture mechanics tests. Results obtained by finite element analyses of real-scale CFC flat tile divertor components under high heat flux loading conditions are verified by the findings of tests in an ion beam high heat flux facility. From the macro-scale FE models of the full component the loading conditions are derived for micro-scale FE models that incorporate principal details of the micro-structured CFC/Cu-interface thus allowing to capture explicitly locally acting dissipative mechanisms which in turn at the macro-scale in fracture mechanics experiments increase the fracture toughness of the CFC/Cu-interface.
Microstructural and Cold Workability Assessment of a New ODS Ferritic Steel
Authors: Olier Patrick , Oksiuta Zbigniew , Melat Jean François , Hamon Didier , Leblond Thomas , de Carlan Yann , Baluc Nadine L.
Published: March 2009

A new ODS composition (Fe-14Cr-2W-0.3Ti-0.3Y2O3) developed in the ExtreMat integrated Project has been produced by mechanical alloying techniques and consolidated by hot extrusion. This study summarizes some results of characterization and cold workability tests carried out at CEA and EPFL.
It appears that the microstructure is fine and uniform after hot extrusion. According to microprobe analysis, solute elements are homogenously distributed in the matrix. However, the relatively high hardness level measured after hot extrusion and heat treatment may be detrimental in case of additional cold processing which is required to produce final shape like thin plates or cladding tubes. An assessment of the cold workability and the effect of the degree of cold work by rolling on recrystallisation temperature are addressed here. It is found that this material can be successfully cold rolled with a high degree of cold work (up to 60% of thickness reduction) without any damage. According to optical micrographs and Differential Scanning Calorimetry (DSC) measurements, it seems that the recrystallisation temperature remains always very high (above 1400°C) even though cold work level increases (up to 66% of thickness reduction). However, the hardness values begin to decrease for heat treatment temperatures above 1200°C for hot worked conditions and below 1000°C for cold worked conditions, respectively.
Special Ceramic Material Based On Basaltic-Andesite for Extreme Environments
Authors: Albert Etele , Muntean Marcela , Ianculescu A. , Miculescu Florin , Albert B.
Published: March 2009

A special ceramic material with specific performances for some extreme environments can be elaborated using basaltic-andesite as raw material. The volcanic rocks presents specific compositions, a complex structure and properties, so some of them, such as basaltic-andesite, may have multiple utilization. The elaborated basaltic-andesite compound ceramic material, in mixture with porcelain-clay and alumina was characterized with SEM (scanning electron microscopy), EDS (energy dispersive spectroscopy), X-ray diffraction and thermo-gravimetric analysis. Many of the properties of this sort of ceramic material surpass the electric insulator porcelain type KER 110 ceramic, and in some approximate the high alumina-content ceramic materials.
Enhancement of Reliability of Machines and Materials by Friction Plating
Authors: Belevskiy L. , Popov Vladimir A. , Tulupov S.A. , Smirnov Oleg M.
Published: March 2009

A process of friction plating was developed for modification of the surface of metal items by strain hardening combined with application of protective coatings aimed to improve corrosion resistance, hardness, wear resistance and other functional properties. Friction plating is performed by means of a metal wire brush rotating at high speed. Coating material in the form of a rod or strip is pressed with a certain force to the rotary wire brush. In the contact zone, coating material is heated up to a high temperature. Particles of coating material are picked up by the ends of brush wires and transferred onto the treated surface. At the same time, the surface of the product is conditioned and heated. Investigations of friction plating have shown that plastic deformation of the surface layer combined with application of coating material particles ensures their strong adhesion to the substrate.
Chemical Vapor Crystallization of Hard Nanocomposite Tungsten Carbide Layers for Extreme Applications
Authors: Goncharov V.L. , Lakhotkin Y.V. , Kuzmin V.P. , Alimov Vladimir K. , Roth J.
Published: March 2009

The physico-chemical fundamentals (thermodynamics, kinetics) of tungsten carbides crystallization process are presented. Chemically vapor deposited coatings composed of tungsten carbides, metallic tungsten matrix with nanoparticles of tungsten carbides are synthesized from gaseous mixture of tungsten hexafluoride, hydrogen and propane at temperatures ranging from 623 to 923 K and can be used as materials for extreme environments. The physical and mechanical characteristics of these CVD coatings are discussed.
Micro-Raman Study on Structure Evolution of Graphite Exposed to Intense Thermal Shock Load
Authors: Hirai Takeshi , Compan Jeremie , Niwase Keisuke
Published: March 2009

A small area of a fine grain graphite block was exposed to intense thermal shock load at 9.6 GW/m2 and investigated by micro-Raman spectroscopy. Raman spectra of the loaded area show a reduction of the intensity ratio of D and G peaks in comparison with the one of unloaded graphite, indicating the ordering of graphitic structure even for as short as 5 ms. Raman spectra of the surrounding area, on the other hand, exhibited broad features of amorphous carbon, indicating a carbon deposits from the loaded area. The broad spectra showed a strong positional dependence, reflecting the temperature gradient of the block induced by the shock load. Fitting analysis of the Raman spectra clearly shows two linear relationships between the G-peak width (FWHMG) and the peak intensity ratio (ID / IG), corresponding to two steps of ordering process of the amorphous carbon deposits.
Examinations on the Oxidation Resistance of Innovative Carbon Based Materials
Authors: Hinssen Hans Klemens , Moormann Rainer , Schlögl Bärbel , Centeno A.
Published: March 2009

An overview on parameters influencing the oxidation behaviour of carbon based materials in oxidizing gases is presented in order to support the development of advanced carbon containing materials with high oxidation resistance. Facilities for testing the oxidation behaviour, as operated in FZJ, are explained. Results of exemplary oxidation tests in air at 700°C on diverse new developed materials are presented: Ti and Zr dopings and coatings were found less efficient, whereas Si coatings/dopings significantly reduce oxidation rates. Low oxidation rates of 3D-CFCs without doping/coating, which were manufactured under temperature treatment of > 2200°C and used high purity starting materials, point out the relevance of the latter parameters. Future work on oxidation resistance of carbon based materials is shortly discussed.
High-Power Fibre Lasers – Application Potentials for Welding of Steel and Aluminium Sheet Material
Authors: Thomy Claus , Seefeld Thomas , Vollertsen Frank
Published: March 2009

Latest developments in laser physics have enabled the production of high-power fibre lasers with beam powers up to 10 kW at excellent beam quality. Adding to these properties their high energetic efficiency, their considerable estimated lifetime and their compact size, they might well be considered to be a viable alternative to both conventional lamp- or diode-pumped Nd:YAGas well as to CO2-Lasers. However, due to the novelty of the system, very few experiences on their usability for materials processing and in special for welding of steel and aluminium sheet material
are existing. To help this situation, a 7 kW high-power fibre laser system was tested at the Bremer Institut fuer angewandte Strahltechnik, and its potentials for welding steel and aluminium sheets have been assessed. By these results, of which a selection is presented here, it could indeed be demonstrated that it is possible to remarkably enhance process limitations considering welding speed and sheet thickness previously regarded to be inevitable when welding with solid-state lasers.
Consequently, in July 2004 the first high-power fibre laser with a beam power exceeding 10 kW at a BPP of less than 12.5 mm*mmrad was tested in cooperation with SLV M-V Rostock. This laser source is currently used for developing mainly welding, but also cutting and cladding applications for a variety of industries. Within these studies, it was e. g. demonstrated that it is possible to achieve a penetration of 10 mm in EN-AW 6082 at a welding speed of 3 m/min.
Optical Measuring Technologies in Sheet Metal Processing
Authors: Galanulis Konstantin
Published: March 2009

During recent years, optical measuring technologies in sheet metal forming and tooling have been used more and more in the industry. Main applications are the digitizing of metal sheet parts and tools, forming analysis of metal sheets as well as the determination of material properties. Good interfaces to conventional CAD/CAM and numerical simulation systems made such optical measuring systems a part of complex process chains. These process chains mainly focus on optimizing the development of products and production processes and on improving the product
quality. Using optical systems considerably decreases the development time for products and production while improving the quality.
Use of Shell Elements for the FEM-Simulation of the Welding Process of Sheet Metal Parts
Authors: Zaeh Michael F. , Papadakis L. , Roeren Sven , Hornfeck T.
Published: March 2009

During the joining process of complex body components in the automobile industry,
dimensional accuracy is essential. In order to predict the behavior and to improve the geometrical quality of joined sheet metal parts during the welding and cooling process, a simulation method by means of finite elements is applied. This should be done in the early stage of the product’s life cycle to reduce process adjustments, which are time and money consuming. In recent years the simulation of welding was basically feasible by models consisting of volume elements. This way the metallurgical phase transformation, which is responsible for the behavior of the treated parts during the cooling process, can be established for a specific material. The use of volumes has a negative influence on the calculation time and it is not applicable for sheet metals. Especially, if effects from previous forming processes are to be considered. Additionally, the application of shells can meet the requirements of an analysis of the effects of welding when the metallurgical material properties are taken into account. In this paper an example of a sheet metal (DC04, former St 14) will be examined with the aid of a finite element analysis. Firstly, a transient temperature field is calculated in a thermal simulation by applying a certain method. In this calculation only the thermal properties of the material are used. Secondly, the transient temperature field is used as the initial load for the
thermo-mechanical analysis. The distortion and the residual stresses of the work piece can be calculated using thermo-mechanical properties and material phase transformations.
A New Approach for Optimization of Sheet Metal Components
Authors: Albers A. , Weiler H. , Emmrich D. , Lauber B.
Published: March 2009

Beads are a widespread technology for reinforcing sheet metal structures, because they can be applied without any additional manufacturing effort and without significant weight increase. The two main applications of bead technology are to increase the stiffness for static loading conditions and to reduce the noise and vibrations for dynamic loadings. However, it is difficult to design the bead patterns of sheet metal structures due to the direction-controlled reinforcement effect of the beads. A wrong bead pattern layout can even weaken the properties of the structure. In the past, the designs were predominantly determined empirically or by the use of so called bead catalogues. Recently, different optimization approaches for bead patterns were developed, which are based upon classical mathematical programming optimization algorithms together with automatically generated shape basis vectors. However, these approaches usually provide only vague suggestions
for the designs. One of the most severe difficulty with these approaches is to transfer the optimized results into manufacturable designs. Furthermore, another severe difficulty is that the optimization problem is non-convex, which frequently leads the mathematical programming algorithms into a local optima and thus to sub-optimal solutions. The investigations in this article show an optimization method, which within a few iterations leads to bead structures with excellent reinforcement effects using optimality criteria based approach. Generally, the results can be transferred without large effort into a final design. The new optimization method calculates the distribution of the bending stress tensor and the principal bending stresses based upon the results of a finite element analysis. The bead orientations
are calculated by the trajectories of the principal bending stress with the largest magnitude. The beads are projected on to the mesh of the component using geometric form functions of the desired bead cross section. A local bead ratio of 50% (defined as average area of the beads in relation to total area of the sheet) is used by the algorithm to determine the maximum moment of inertia. The proposed algorithm is numerical implemented in the optimization system TOSCA and
available for being applied with the following finite element solvers: ABAQUS, ANSYS, I-DEAS, NX Nastran, MSC.Nastran, MSC.Marc and PERMAS. The optimization algorithm is successfully applied to static and dynamic real world problems like car body parts, oil pans and exhaust mufflers. In the present work several academic and industrial examples are presented.
The Integration of CAPP and Production Planning for Bent Sheet Metal Parts
Authors: Cattrysse Dirk , Collin P. , Duflou Joost R. , Nguyen T.H.M. , Van Oudheusden Dirk
Published: March 2009

Both the topics of Computer Aided Process Planning and Production Planning in the
context of sheet metal air bending have been presented as standalone topics previously. This paper will focus on the interaction between both modules. Choices made by the CAPP-module seem to influence the possible gains that can be obtained in production planning and vice versa. The used procedures for both the CAPP module, including process planning and tool selection for air bending, and the Production Planning module, modelling the production planning as a Travelling Purchaser Problem, are described. The different areas of interaction between both
modules are also specified. Results demonstrate that the interaction between both modules has a significant impact and should be taken into account in an integrated process and production planning system.
Rapid Tooling by Laminated Object Manufacturing of Metal Foil
Authors: Prechtl M. , Otto Andrea , Geiger Manfred
Published: March 2009

The technology of Laminated Object Manufacturing (LOM) is not very new. For
hundreds of years wooden parts are built by stacking layers together. Nowadays also paper, plastic, ceramic composite and metal sheets are treated in layers.
For the manufacture of prototypes and especially technical tools, e. g. moulds for gravity casting, die casting or injection molding, out of metallic foil however the low self stiffness of this material is a great challenge. In this case it is useful to produce the parts in a two step process. The first subprocess is the stacking of the layers, which can be realised by laser beam spot welding to determine the position of the layer in combination with generating the defined contour by a laser beam cutting
process. This procedure is done in a fully automated machine where the CAD-file of the desired part and the building parameters like the laser parameters and the cutting velocity are needed as input. However the stability of the produced green part is insufficient for most kind of application. Hence, a second sub-process to enhance the mechanical properties of the part is necessary. This can for example be realised by high temperature soldering or by diffusion welding in a furnace with inert gas or vacuum. During these kinds of joining processes the green part is homogeneously pressed with the help of a powder bed and at the same time it is tempered for a defined term. In this paper the principle of sheet metal LOM is described as well as the process chain of Laminated Object Manufacturing of metal foil. For each sub-process of metal foil LOM the results of the experimental work for qualifying and optimizing the sub-process are shown. Finally some examples of possible applications especially in the field of Rapid Tooling and Rapid Manufacturing
are discussed.
Closed-Loop-Control of the Material Flow in the Deep Drawing Process
Authors: Behrens Bernd-Arno , Yun J.W. , Milch M.
Published: March 2009

In this paper, a concept of a closed-loop-control system for the material flow in deep
drawing processes based on a fuzzy-controller is presented. The deep drawing process is influenced by different variables as batch dependent material values, machine parameters as well as variations in the forming tools. Process stability can be improved by continuous process monitoring and process control. The control loop for controlling the material flow consists of an optical sensor, a deep drawing tool with an elastic blank holder, a fuzzy controller and a deep drawing press with a
multi point drawing cushion. The controlled variable (material flow) was measured contact-free and on-line by means of an optical sensor developed at the IFUM. As control variable the different lokal blank holder forces were chosen in order to influence the material flow in different areas. In order to combine the controlled variable (material flow) and the control variable (lokal blank holder force) a fuzzy logic controller was designed. The performance of the material flow control was investigated by generating disturbances (e.g. a high blank holder force at the beginning) in the deep drawing process. This procedure shows that the fuzzy-controlled material flow can be compensated for the disturbances by means of changing the blank holder force.
3D Ultrasonic Imaging for Sheet Metal Hydroforming
Authors: Meier Horst , Ermert H. , Knoll P. , Keitmann-Curdes Oliver
Published: March 2009

With fluid forming processes getting more and more common in industrial application a
lot of research is carried out to analyze the forming behavior of sheet metal within these processes. In order to gather experimental information about the forming behavior of the workpiece, an imaging system is presented, that will allow determining the actual shape within the forming process. The system has to be functional in liquid media as well as in a high pressure environment. Therefore an ultrasonic based system has been chosen, consisting of a small number of transducers which are alternately used as transmitter and receiver. It is possible to cover 100 by 100 mm² with only 10 by 10 transducers by the use of special algorithms. The reconstruction of the echographic images from the recorded data is done by a SAFTalgorithm (synthetic aperture focusing technique) followed by an analysis with special contourdetection algorithms, which are able to scan the image for contour data. It can be shown that the accuracy of the reconstruction is quite good in the 2.5-dimensional domain, if appropriate contour models for the description are used. Because of the small number of transducers and the specular reflection of the signals, the quality of the image can be improved significantly by the extension of the SAFT algorithm with an angle-weighted factor. The three dimensional reconstruction is also possible and will be demonstrated for simple geometries. The
ability for sampling more complex geometries and enhancing the accuracy will be achieved by the integration of three dimensional contour models and three dimensional angle-weighting.
The Design of an Incremental Sheet Forming Machine
Authors: Allwood J.M. , Houghton N.E. , Jackson K.P.
Published: March 2009

A new incremental sheet forming machine has been built in Cambridge and was
commissioned in October 2004. The basis for the machine design is described, including estimates of tool forces, the need for access to the reverse side of the workpiece, and the need to cope with high horizontal loads at the tool tip. The tool-mounting has been designed to rotate freely but passively, and to allow for simple exchange of tool tips. The workpiece is mounted on a set of load cells providing a six degree of freedom constraint without moment loading of the cells. The initial operation of the machine is briefly described.
Sheet Thinning Prediction in Single Point Incremental Forming
Authors: Ambrogio Giuseppina , Filice Luigino , Gagliardi Francesco , Micari Fabrizio
Published: March 2009

Incremental forming processes are characterized by a well known and particular feature: any deformation across the sheet plane determines sheet thinning, since the blank is fully clamped by means of a proper equipment. As a consequence, the availability of effective and reliable CAE tools capable to supply an accurate prediction of sheet thinning as a function of process parameters, represents a strong requirement for a wider practical application of incremental forming. The already available theoretical models (i.e. the sine law) do not provide, on the other hand, satisfactory results. Therefore in the paper a couple of numerical analysis strategies was applied to simulate simple incremental forming processes, as well as a proper experimental equipment was developed to verify the accuracy of the numerical predictions.
Studies for the Development of a Simulation Basis for Numerically Controlled Driving of Sheet Metal
Authors: Hoffmann Hartmut , Hautmann R. , Petry R.
Published: March 2009

The manufacturing technique of driving is one of the oldest procedures for sheet metal forming and has been used in the ancient world for the production of copper pots and vases. This technique is still utilized for niche applications but today has lost its importance. The process of driving is almost completely carried out manually and thus is only appropriate for very small quantities or in case of failure of other production processes. Since individualization of products is strongly gaining in significance, forming processes have to be found, which are independent from expensive tools and equipment. Using driving as the process of choice to form sheet metal, the grade of automation of the forming process has to be increased. Numerically controlled driving, i.e. automated positioning and handling of the work piece during the production process, will need a conclusive simulation base. This paper provides results of the analysis of sheet steel angles formed by the driving sub groups of shrinking and stretching.
Friction Stir Welding of Light Weight Sandwich Materials
Authors: Dörfler S. , Otto Andrea
Published: March 2009

Ever since its invention, friction stir welding has been of great interest for the joining of light weight materials. Due to joining in the solid state, friction stir welding inheres characteristic advantages that are unmatched by conventional fusion welding techniques. At the Chair of Manufacturing Technology friction stir welding is employed to develop a process chain for the production of highly load adapted car body components out of aluminum sheet metal and aluminum foam sandwich (AFS) by tailored blanking. In contrast to friction stir welding other materials, special measures have to be taken, since AFS comprises a layered material structure out of two solid aluminum sheet metal cover layers and a powder metallurgically produced core layer. After welding, the tailored blank is subjected to forming, foaming and a final laser cutting process. High temperature capability of the weld seam must be assured, hence foaming of the powder metallurgic core layer requires temperatures of up to 95% of core layer-solidus temperature. Therefore not only mechanical properties are revealed, but also temperature capability is assessed by differential scanning calorimetry (DSC). Additionally the weld seams are tested during foaming by the use of special specimen geometry. Due to the high deformation and temperature while welding and foaming, the metallurgical structure at the weld seam undergoes some modifications, which are subject to metallographic
analysis and hardness testing. As an outlook, new material developments towards 6000 aluminum alloys as cover sheet materials will be discussed with regard to the process chain.
The Significance of Experiment in the Finite Element Analysis of a Pulley Forming Process
Authors: Liu Xiao Hang , Daniels Mike , Shirvani Bez
Published: March 2009

For reasons of cost and weight, light gauge sheet is used wherever possible for metal fabrications. In sheet metal forming the process is to gather the metal into defined areas. The pulley forming process is no exception and is achieved by superimposing axial loads on top of radial loads using a pressure-controlled tailstock. Whilst the headstock-mounted tooling is fixed, that part held on the tailstock can be powered axially under controlled pressure. This pressure is governed by the width of the workpiece which changes during the forming process.
Experiments have been designed to provide an understanding of the pulley forming process and to verify numerical models. The latter has been taken the form of finite element simulations to enable prediction of metal flow, tool forces and potential sources of defects and failures. There are three objectives for conducting the experiments which have been investigated in this paper:
1. providing data to define the movements of the forming tools for the finite element model, including displacements and velocities,
2. understanding the effects of the pulley forming operation on the flow of material, and
3. validating the finite element model.
Modelling and Analysis of Integrated Hotforming and Quenching Processes
Authors: Lorenz D. , Roll Karl
Published: March 2009

In the automotive industry a general tendency to choose steels with enhanced strength for structural parts can be observed. This trend results from the increased lightweight design efforts to satisfy the fleet consumption restrictions. Hot forming and quenching of boron steel offers the possibility to improve the component strength and reduce the weight of structural parts. The main influences on the process are described and a method to model and simulate this process using the
finite element method using LS-DYNA is presented. Experimental investigations of the contact heat transfer have been carried out to enhance the simulation accuracy. A prototyping tool of a structural part is used to examine the process under production conditions. Temperatures of the tool and the part are measured during the process. These temperatures are compared with the simulation results in order to reevaluate the results of the process simulation.
Optical and Electrical Properties of SnS: Ag Films as Solar Cell Absorbers
Authors: Lu Pe Min , Jia Hong Jie , Cheng Shu Ying
Published: March 2009

SnS and Ag films were deposited on glass substrates by vacuum thermal evaporation successively, then they were annealed in N2 ambience at a temperature of 300 oC for 2h. By controlling the Ag evaporation voltage to roughly alter content of Ag in SnS films, different Ag-doped SnS films were obtained. The microstructures, composition and properties of the films were characterized with X-ray diffraction ( XRD ), atomic force microscopy(AFM) and some other methods. With the increase of Ag evaporation voltage (VAg), there exist new phases of Ag8SnS6 and Ag2S, whose intensity of diffraction peaks increases with the increasing Ag-dopant, and the average roughness of the films varies from 18.7nm to 23.6nm, and grain size increases from 192nm to 348nm. With the increase of VAg, the evaluated direct band gap Eg of the films decreases from 2.28eV(undoped) to 2.05eV (VAg=70V), the carrier concentration value and Hall mobility of the films diminishes from 2.048×1014cm-3 and 25.96 cm2.v-2.s-1 to 1.035×1016 cm-3 and 5.66 cm2.v-2.s-1, respectively; while the resistivity of the films decreases sharply from 1174Ω.cm(undoped ) to 107Ω.cm (VAg=70V ). All the films are of p-type conductivity. The above results show that the semiconducting properties of the SnS films have been improved by silver-doping.
Study of Control System for a Micro Programmable Blazed Grating
Authors: Yan Bin , Yuan Wei Zheng , Yu Yi Ting , Wang Lan Lan , Qiao Da Yong , Li Tai Ping
Published: March 2009

Based on a new micro programmable grating with changeable blazed angle, the control system was recently designed and developed, enabling the normal operation for the fabricated grating. The basic requirements for the control system are high reliability, efficiency and miniaturization. This paper presents the specific design objectives for the control system according to the grating’s operation characteristics. The whole control system contains three key modules—generator & communication module, high-voltage amplifier module and computer software module. Generator & communication module includes a high-performance microcontroller (C8051F020), a D/a converter (AD7305) and universal serial bus (USB) interface. As for the considered performances, PA69 is complete capable of magnifying the driving voltage signals to drive the grating in high-voltage amplifier module. After the development of the control system, an experiment was performed for investigating the dynamic frequency response of the grating. In conclusion, it has the advantages of wide output of voltage, high frequency response, driving ability in wide capacitive load range and real-time control properties. Hence, it is appropriate for controlling MEMS programmable grating in complicated and dynamic conditions.
Effect of the Thickness Uniformity in Micro-Electroforming Process by Dividing Conductive Zone on Cathode
Authors: Du Li Qun , Yu Li Chuan , Song Lei , Liu Chong
Published: March 2009

In this paper, an effective method is presented to improve thickness uniformity in nickel electroforming process. In most electroforming processes, thickness ratio of edge to center is 2.5~4 and the shape of the electroforming zone is naturally a concave. Dividing conductive zone of electroforming structure to redistribute current density was applied to improve electroforming uniformity. Theoretical analysis and experimental results verify that a proper dividing method can improve the electroforming uniformity effectively. In the experiment, the thickness ratio of edge to center decreases from 2.91 to 1.88.
Investigation on Fine Polishing Technique of Silicon Wafer
Authors: Gong Quan Cheng , Zhu Jian , Jia Shi Xing , Wu Jing
Published: March 2009

This paper presents a kind of fine polishing technique that adopts three-step polishing procedure and keeping-wafer-wet method. In order to remove the damaged layer created by lapping process or improve surface condition of silicon wafer, polishing process is needed. In this paper, techniques of improving the surface roughness of silicon are studied, three different polishing processes are presented, and optimum condition has been attained. Experiments of Si-Si bonding are also performed, and results show that after polishing ends, keeping surface of wafer wet is necessary to avoid slurry agglomerating.
Scanning Ion Conductance Microscopy and its Applications in Nanobiology and Nanomedicine
Authors: Liu Li Ping , Wang Yun Dou , Zhang Yan Jun
Published: March 2009

In cell biology and medicine study, continuous high spatial resolution observations of living cells would greatly aid the elucidation of the relationship between structure and function of cells. The development of scanning probe microscopy (SPM) has opened up a new era of life science and has been used to develop a family of related methods that allow studying of cell structure and function on nanometer scale. Scanning ion conductance microscopy (SICM) is a new member of such SPM family and can be used to obtain high-resolution non-contact images of the surface of live cells under physiological conditions, and hence allows the relationship between cell microstructure and function to be probed. In this review, we concisely introduce the principles of SICM and its applications in nanobiology and nanomedicine.
Design and Simulation of a Z-Axis Dual Proof Mass Micromachined Gyroscope with Decoupled Oscillation Modes
Authors: Yan Xin , Ma Zhi Chun , Chen Xu Yuan
Published: March 2009

In this paper, a Z-axis micromachined gyroscope with a new decoupled design was presented. The gyroscope consists of dual proof mass, sense frame and drive frame structure. The sense frame is constrained in the sense direction and anchored on the substrate, which minimize the influence from the motion of the proof mass in the drive direction. The drive frame is also restricted to oscillate in the drive direction. ANSYS has been used to make modal analysis and harmonic analysis to determine the vibration characteristics of the decoupled gyroscope. We introduce the decoupling ratio (ηDtS) of drive mode to sense mode and the decoupling ratio (ηStD) of sense mode to drive mode to determine the decoupling design. The results show that the drive mode and the sense mode are well decoupled.
Fabrication of Micro Via-Hole by Wet Etching of Pyrex Glass
Authors: Jia Shi Xing , Zhang Long , Zhu Jian
Published: March 2009

A method of fabrication of micro via-hole by wet-etching of Pyrex glass is presented in the paper. The through holes with double funnel-shape have been fabricated attribute to isotropic etching. Furthermore, the funnel-shape holes are advantageous to the joint sealing and have been applied to fabricate microfluid chips. The results show that the proportioning of corrosion solution is HF:HCl:H2O=3:6:10, and the corrosion rate is about 0.67um/min, the diameter of the holes on the both-side of the wafer is only 750 um, the middle ones are 300um