bluuebunny/crossref_metadata_2025 huggingface dataset:
Production and Characterization of Polyhydroxyalkanoates (PHAs) from Inexpensive Substrates by Alcaligenes Latus
Authors: Thammawong C. , Thongkhong K. , Iamtassana K. , Sharp Alice , Opaprakasit Pakorn
Published: March 2009

Polyhydroxyalkanoate (PHA) is biodegradable polyester, which can be synthesized by many microorganisms through catabolic pathway, without producing any toxic byproduct. Owing to it special and versatile properties, this polymer has attracted much attention as a possible replacement for traditional plastics in the future. Feasibility of PHA production from inexpensive substrates was investigated by using Alcaligenes latus, gram negative bacteria, which can be grown in various types of wastewater. Four substrates were employed, i.e., wastewater from palm oil industry (oil-lean palm oil and oil-rich palm oil), wastewater from soymilk industry, and a control synthetic wastewater. The results show that PHA copolymer, poly(hydroxybutyrate-co-hydroxyvalerate) P(HB-co-HV), is produced from the metabolic pathways of A. latus. Soxhlet extractor was then employed in extraction process of the PHA copolymer. The resulting copolymer was characterized by Fourier Transform Infrared (FTIR) spectroscopy, and Nuclear Magnetic Resonance (NMR) Spectroscopy.
Microstructure and Interfaces of Thin Film Capacitors on Base Metal Foils
Authors: Dechakupt Tanawadee , Yang G. , Reaney Ian M. , Randall Clive A. , Trolier-McKinstry S.
Published: March 2009

The microstructure and interface quality of chemical solution deposited barium titanate thin films on Ni foil were studied. Cross-sectional transmission electron microscopy shows that a ~200 nm thick barium titanate film annealed in a controlled oxygen partial pressure consists of equiaxed grains with grain size range of 24-75 nm (~ 42 nm average). NiO was detected after re-oxidation by X-ray diffraction, but not by transmission electron microscopy, suggesting that the oxide is not a continuous barrier layer, but is spatially distributed in the films. Oxygen non-stoichiometry and the existence of C in barium titanate films were observed by electron energy loss spectrometry. In addition, it was found that there is a 5-8 nm thick Ni-Ba alloy developed at the interface between the barium titanate film and Ni foil.
Effects of Manganese Addition on Phase Formation, Microstructure and Electrical Properties of Barium Titanate Ceramics
Authors: Tangsritrakul Jirapa , Unruan Muangjai , Ketsuwan Piyachon , Yimnirun Rattikorn
Published: March 2009

In this study, the influence of Mn addition on phase formation, microstructure and electrical properties of Ba(Ti1-xMnx)O3 where x = 0.01 to 0.2 was investigated. The XRD patterns showed that the crystal structure of Ba(Ti1-xMnx)O3 at room temperature changed from tetragonal to hexagonal as Mn concentration increased, which also caused the room temperature dielectric constant decrease from 1143 to 47. The microstructure of Ba(Ti1-xMnx)O3 ceramics at low concentration revealed a bimodal microstructure. As the x value increased, the well grown grains decreased with the extent of fine-grained increased. Ferroelectric hysteresis (P-E) loop was not clearly observed as Mn concentration increased because of the formation of paraelectric hexagonal phase
Preparation of Nano- MgO and Investigation of its Infrared Absorption Properties
Authors: Zhu Yi Min , Han Yue Xin , Wang Xiao Yu , Wang Xu
Published: March 2009

A precipitation-pyrolysis process was developed for the synthesis of MgO nano-particles with diameter of 20~100 nm by using organic reagent, glycol, n-butanol and N,N-Dimethylacetamide, as shape and size controller. XRD and TEM were used to study on composition, morphology and size of the as prepared MgO nanoparticles. The results indicate that organic crystal controller is one of the key factors affecting the sizes and shapes of the nano MgO particles. When using glycol as a crystal controller, the dispersion of nano MgO particles is better and olive-shaped particles with sizes of 20~40 nm are prepared. When nano MgO particles are synthesized by MgCl2 and Mg(NO3)2, their particle sizes are smaller and their particles with olive shape. During chemical reaction process, Mg(OH)2 particles are already formed to be nano scale. Calcination process at the temperature of 650°C can change the crystal shape slightly. FTIR results show that nano MgO particles have abnormal infrared absorption behaviors compared with that of micron scale.
Production Status of Nano-Sized Powder Materials in China
Authors: Lü Xing Dong , Liu Xiao Hua , Gai Guo Sheng
Published: March 2009

The current situation of nano-sized powder materials in China was introduced especially the status of commercial production and the progress of manufacture process and technology. The current production process and reaction conditions for some nano-sized powders were also introduced, and the existent problems were discussed. The future development of nano-sized powder materials in China was prospected.
A Super Highly Sensitive Glucose Biosensor Based on Ag/PPy Nanoparticle-Ethyl Cellulose Hybrid Materials
Authors: Ren Xiang Zhong , Zhang Pei Xin , Liu Jian Hong , Zhang Qian Ling
Published: March 2009

Ag/polypyrrole(PPy) composite nanoparticles within 100 to 150nm diameter were successfully synthesized. Fourier transform infrared spectroscopy(FTIR) and X-ray diffraction patterns(XRD) data suggested that the nanoparticles were composed of Ag and PPy. An amperometric glucose biosensor was fabricated by adsorbing of glucose oxidase(GOx) to an Ag/PPy nanoparticle-ethyl cellulose composite material modified platinum electrode. The biosensor exhibited a super highly sensitive response to the analyte with a detection limit of 1.0×10-7mol/L. Moreover, the biosensor showed quick current response. The effects of some factors, such as working voltage, pH value , mensuration temperature and mass ratio of Ag/PPy nanoparticles to ethyl cellulose, were also studied.
Study on Size Distribution of Oolitic Hematite
Authors: Zhao Li Bing
Published: March 2009

the processing of oolitic hematite is considered to be one of difficult problems in mineral processing due to finely disseminated and complex structure of ore. The ore property, size distribution, mineralogy and mineral processing technology of refractory oolitic hematite in Longyan Iron Mine of Xuan Steel in Hebei, China is studied in the paper.. The result shows that grade of iron concentrates of 61.34 % and the recovery of 53.07 % are obtained by four stages of grinding, four times of gravity, tertiary HMS and single stages of rougher and scavenger reverse flotation in sequence.
Surface Coating of TiO2 Powder
Authors: Zhang Pei Xin , Zhang Dong Yun , Qiu Qi , Jing Li , Ren Xiang Zhong
Published: March 2009

SiO2 nano-scale films were coated on the surface of TiO2 powder by liquid phase deposition. The morphology and the composition of coated TiO2 were studied by transmission electron microscopy (TEM), X-ray photoelectronic spectrscopy (XPS), and X-ray fluorescence (XRF). The study showed that a continuous SiO2 nano-scale film was coated on the TiO2 particles, and the element Si was bonded to the surface of TiO2 in the form of the Ti-O-Si bond. The most suitable conditions for coating are: 0.5 mol•L-1 of C ; pH value of 9.5; 200 g•L-1 of C , reaction time of 5 h at 85 °C.
Effect of Heat Treatment on Properties of Mineral Attapulgite
Authors: Tang Qing Guo , Liang Jin Sheng , Meng Jun Ping , Wang Fei , Li Li Wei , Li Yang Xian
Published: March 2009

Mineral attapulgite powders were heat treated at different temperature from 100°C to 800°C. The effect of heat treatment on properties of attapulgite were studied by particle size distribution, surface free energy, and water vapor adsorption performance. The results show that the medium particle size and surface free energy of attapulgite increase and hygroscopic capacity promptly reduce with the increase of heat temperature .The medium particle size of the raw palygorskite is 3.09 μm, and it becomes 14.12 μm after heat treatment at 800 °C. The surface free energy, polarity component and dispersion component of the natural attapulgite are 45.16mN•m-1, 13.92mN•m-1, 31.24mN•m-1, respectively, and they become 116.22 mN•m-1，116.22 mN•m-1，0.0 mN•m-1 after heat treatment at 800°C. Moreover, the hygroscopic capacity of attapulgite in 24h decreases from 17.1 % to 5.6% after heat treatment at 800°C.
Facile Controlled Synthesis of Mg(OH)2 Nanoparticles with Novel Shapes
Authors: Wang Jing Hui , Li Xin , Ye Jun Wei , Lin Yuan , Ning Gui Ling
Published: March 2009

In this paper, magnesium hydroxide (Mg(OH)2) nanoparticles with tunable morphologies have been selectively synthesized via a facile template-free solvothermal route. The as-synthesized samples were characterized by instrumental analyses such as transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). It was found that the morphology and size of the final products strongly depended on the reaction temperature and duration time. By manipulating the temperature and time in the solvothermal treatment, fiber-like, sphere-like and garland-like magnesium hydroxide nanoparticles were obtained. The described method without any catalysts or templates for preparing magnesium hydroxide nanoparticles is promising for industrial production in competition with other approaches.
One High Efficiency Production Line of Clinker and Slag Grinding Separately by Roller Mill in Cement Industry
Authors: Liu Ning Chang , Li Zhao Feng
Published: March 2009

In cement industry, many grinding up systems are on operating now. The tradition process of tube mill grinding system is high energy consumption, so it’s low efficiency, especially in the final cement grinding process. The value and advantage of slag is recognized more and more, but it’s difficult to be grinded up. Furthermore, the disadvantage and shortages to grind up clinker compounded with slag to produce cement are obvious and adopted. The best process is to grind up slag, clinker separately. Then, these two kinds of powder are compounded by a mixer. Hereby, it introduces a design of the process to grind up clinker, slag by one roller mill.
Effect of Fibre Anisotropy on Composite Thermal Conductivity
Authors: Lloyd J.C. , Clegg W.J.
Published: March 2009

This paper examines the effect of anisotropy on the effective composite thermal conductivity, Kc, of metal matrix composites containing carbon-based inclusions. Added effects of thermal interface conductance, hbd, and size have also been considered. It has been found that at high hbd values, the effective thermal conductivity of the composite is limited by inclusion anisotropy. At lower hbd values and smaller inclusion sizes, this effect is greatly diminished due to the more dominant effect of limited heat flow across the interface.
Preparation of Functionally Graded W/Cu Interlayers and Brazing to CuCrZr and CFC for Actively Cooled Flat Tile Divertor Mock-Ups
Authors: Edtmaier C. , Hula R.C. , Pintsuk Gerald , Guarnone Paola
Published: March 2009

The designed plasma facing materials for the divertor-components in ITER are up to now carbon (graphite or CFC) and tungsten. The heat flux loading can result in temperatures of up to 550°C at the interface between the plasma facing material and the CuCrZr heat sink, an operation temperature which is too high for CuCrZr. Additionally the temperature gradient and the mismatch in thermal expansion (CTE) of both parts of the divertor result in high stresses at the interface. A tungsten-copper composite material with a gradation from pure copper on the one side to pure tungsten on the opposite side is supposed to support the stress reduction. The tungsten contributes to the strength of the composite, whereas the copper provides the required thermal conductivity (TC) of at least 200 W/mK. The graded W/Cu layers were produced by the “chemical mixing” method and subsequent liquid phase sintering. Here the use of sub-µm W-particle sizes offers an opportunity to gain well dispersed W-particles with high Cu-containing composites resulting in lower CTE values and higher thermal conductivities compared to coarser W-powders. Brazing of the functionally graded W/Cu interlayers to CuCrZr and CFC materials resulted in adjoined mock-ups.
Stress State, Texture, Phase and Morphology Analysis of Thin Graded W/Cu Coatings on Tungsten and their Thermal Behaviour in Fusion Application
Authors: Herrmann Aurelia , Balden Martin , Rasiński M. , Bolt Harald
Published: March 2009

Thin graded W/Cu coatings plus subsequent heat treatment at 800°C are used to improve the interfacial adhesion between W and Cu. Specimen with ~500 nm thick graded W/Cu coatings were characterized and analyzed after thermal treatment at 550°C, 650°C and 800°C. At 800°C a significant change in the nanostructure is observed. The better adhesion is caused by W/W grain boundary diffusion processes and Oswald ripening of the nanometre-sized grains leading to their interconnection between each other and the W substrate. The phase and texture analysis of graded W/Cu indicates grain growth and diffusion processes of pure W and Cu. The stress analysis shows that the changes in the nanostructure of the W/Cu coatings correlates to the stress relieve of W at temperature starting from 650°C. After cooling of the coating to RT the residue intrinsic tensile stress is caused by thermal mismatches of the substrate and the 100% W layer of the coating.
Characterization of MeV Ion-Irradiated SiCf/SiC Composites Prepared with Different Methods
Authors: Park Ji Yeon , Kang Seok Min , Kim Weon Ju , Kohyama Akira
Published: March 2009

To estimate the ion-irradiation effect on various types of SiCf/SiC composites, a silicon self-ion irradiation was performed at temperatures of 600 °C and 1200 °C and at doses of 5 dpa and 20 dpa, respectively. These SiCf/SiC composites were prepared by different processes such as CVI (chemical vapor infiltration), WA-CVI (SiC whisker assisted CVI) and hot-pressing (HP) method. Hardness was measured by a nano-indentation tester and microstructural changes were observed by TEM with SAD(selected area diffraction) technique for the specimens prepared by FIB (Focused Ion Beam) milling. The damage dose was calculated by the SRIM2003 code and then compared with microstructureal observation.
Numerical Simulation and Experimental Analysis of Laser Surface Remelting of AISI 420 Stainless Steel Samples
Authors: Cheung Noé , Larosa M.A. , Osório Wislei R.R. , Lerardi Maria Clara F. , Garcia Amauri
Published: March 2009

The aim of this work is to develop a heat transfer mathematical model based on the finite difference method in order to simulate temperature fields in the laser surface remelting process. Convective heat transfer in the remelted pool is taken into account by using the effective thermal conductivity approach. Experiments of laser surface remelting of AISI 420 stainless steel samples were carried out in the present investigation, and numerical simulations were applied for the laser machine operating parameters. The work also encompasses the analysis of microstructural and microhardness variations throughout the resulting treated and unmolten zones.
Residual Stress Measurements in Mo/CuCrZr Tiles Using Neutron Diffraction
Authors: Mergia K. , Grattarola Marco , Messoloras S. , Gualco Carlo , Hofmann Michael
Published: March 2009

In plasma facing components (PFC) for nuclear fusion reactors tungsten or carbon based tiles need to be cooled through a heat sink. The joint between the PFC and the heat sink can be realized using a brazing process through the employment of compliant layer of either a low yield material, like copper, or a high yield material, like molybdenum. Experimental verification of the induced stresses during the brazing process is of vital importance. Strains and residual stresses have been measured in Mo/CuCrZr brazed tiles using neutron diffraction. The strains and stresses were measured in Mo tile along the weld direction and at different distances from it. The experimental results are compared with Finite Element Simulations.
Thermo-Mechanical Behaviour of HfO2 Coatings for Aerospace Applications
Authors: Mergia K. , Liedtke Volker , Speliotis T. , Apostolopoulos G. , Messoloras S.
Published: March 2009

The use of ceramic composite materials in aerospace applications requires the development of oxidization protection coatings which can withstand very high temperatures. HfO2 is a promising material as a high temperature oxidization protective layer. HfO2 coatings have been deposited by radiation frequency magnetron sputtering all over the surface of SiC substrates and were tested under re-entry conditions. Also their oxidization resistance in air in the temperature range 1100 to 1450°C has been examined. The coatings were found to be stable and well-adhering to the substrate even after 100 re-entry cycles. No oxidization of the underlying SiC structure is observed. Re-entry and oxidization tests result in the formation of HfSiO4 at the HfO2/SiC interface, which further promotes their oxidization resistance.
Joining of Steel-Aluminium Hybrid Structures with Electron Beam on Atmosphere
Authors: Bach Friedrich Wilhelm , Beniyash A. , Lau K. , Versemann R.
Published: March 2009

Against the background of the required weight reduction in transportation through
lightweight construction, the application of hybrid structures, where dissimilar materials are joined together, has a high technical and economical potential. In the field of sheet machining, combinations of steel and aluminium are especially interesting. In comparison to conventional steels, the application of aluminium alloys as supporting materials makes a distinct weight reduction possible. On the other hand, steels have advantages in the fields forming and welding. The application of modern high-strength steels with reduced sheet thicknesses allows weight reduction,
too. But joining of material combinations of steel and aluminium is problematic. On the one hand brittle intermetallic compounds are formed between steel and aluminium. On the other hand the aluminium melt has a bad wetting behaviour. Different physical properties of both materials have to be considered, too. To achieve sufficient mechanical properties of such joinings it is necessary to limit growth of intermetallic compounds between steel and aluminium. This can be actualized by an exact energy
supply. With the electron beam on atmosphere a precise and easily controllable energy supply is possible. The publication demonstrates successful investigations, which were performed with the 175 kVNVEBW (Non Vacuum Electron Beam Welding) installation at Institut of Materials Science, University of Hanover. With NVEB joining hybrid structures between zinc coated steels and 5.xxx and 6.xxx aluminium alloys were produced. In a welding-brazing process (the steel remained in the solid phase whereas the aluminium was molten) combinations with acceptable mechanical properties could be joined. By use of optimized joining parameters as well as a surface activating flux, both, a good wetting and a thin intermetallic compound < 10 µm were attained. Another possible strategy is a pure brazing process, for which an example is also given in the paper. The paper shows metallurgical and mechanical investigations, among other things results of element
distribution analysis and tensile tests.
Investigations on Seam Quality in Laser Beam Welding of Contaminated, Zinc Coated Sheets
Authors: Blankl A. , Geiger Manfred
Published: March 2009

The customers’ demand for high quality and low cost products with rising functionality forces the enterprises to cost savings. In production these cost savings can be accomplished by simplification or omission of handling operations in the process chain. In laser beam welding of stamped sheet metals a previous cleaning of the sheets is usually necessary to guarantee a sufficient seam quality at a lap joint. Due to the recent trend towards low use of lubricants in forming operations the question arises, whether this process could be avoided in order to lower the production costs. The disadvantage of this measure would be a degradation of the seam quality. This reduction shows up in a falling strength of the weld due to inclusions and pore formation. This paper deals with the impact of different types of contaminations on the quality of laser welding. Therefore several liquid (oils) and solid (metallic and non-metallic) contaminants are examined. Zinc coated sheets are investigated too, because a zinc contamination arises with these sheets in the welding operation. The zinc coating evaporates because of the high temperature and this leads to a high porosity in the welding seam. In both cases also the height of the gap between the two sheets is varied in order to investigate its influence on the weld. To reduce the effort of the investigations, but not the accuracy of the results, the laboratory trials were supported by the methods of design of experiments. After the welding operation, the quality of the welding seam is
evaluated by means of its mechanical properties and tightness. The results of the investigations are discussed and the developed solution strategies are presented.
Distortion Minimization in Remote Welding of Steel
Authors: Thomy Claus , Schilf M. , Seefeld Thomas , Sepold G. , Vollertsen Frank
Published: March 2009

In conventional robot-guided laser beam welding of sheet metal, e.g. for automotive
applications, one of the key aspects determining the welding sequence is the positioning distance between the welds. Generally, it is intended to minimize this positioning length, due to the pure positioning velocity significantly influence the cycle time. However, to minimize cycle time by minimizing positioning distances might result in a welding sequence less than optimal in view of distortion. In view of this conflict, remote welding may be a potential solution. It has been demonstrated that, by moving the laser spot over the work piece by the help of a fast beam deflection unit, it is possible to reduce the relative proportion of positioning time to less than 10% of the cycle time. In special, the importance of positioning distance is drastically reduced, thus allowing to base the selection of the welding sequence on technological aspects such as distortion rather than on economic necessities. However, basic studies on distortion and distortion minimization exploiting the specific advantages of remote welding are still lacking. Thus, various investigations on this topic have been conducted at the BIAS Bremer Institut für angewandte
Strahltechnik by the help of a Trumpf CO2-Laser remote welding system. The results presented here are focussed on the effects of heat input and welding sequence on distortion during stitch welding of one- and two dimensional steel sheet structures.
System for Design and Computation of Lightweight Structures Made of Bent Profiles
Authors: Chatti Sami , Dirksen Uwe , Schikorra Marco , Kleiner Matthias
Published: March 2009

The process chain for the production of lightweight profile structures consists of the
design and computation phases, the manufacturing of straight profiles, the manufacturing and further processing of bent profiles, and the joining of single profiles to lightweight structures. A sophisticated lightweight construction design of profile structures is characterised by the use of the correct material at the correct place with the correct dimensions. To design in this way means to purposefully find the technically and economically best solution. This requires a holistic technological approach covering the whole system “design-material-manufacturing”. Furthermore, appropriate experiences in design and the use of calculation software for the determination of several mechanical component properties as well as the simulation of manufacturing processes are necessary. A satisfactory component optimisation and a manufacturing specific design of the components presupposes, however, the integration of design, computation, and manufacturing knowledge into a single system using modern CA technologies to realise simultaneous engineering.
Intelligent Manufacturing by Enhanced Product Models
Authors: Bley H. , Zenner C. , Bossmann M.
Published: March 2009

As the quality of manufactured products as well as the quality of the used manufacturing processes has become more and more important for a company in order to stay competitive in the last decades, an integrated quality management leading towards intelligent manufacturing represents a key factor today. Therefore, new methods are required for considering quality information in all phases of the product life cycle. Feature technology and especially the use of so-called measurement and quality features represent an approach towards integrated quality management and the achievement of process-oriented and global quality control loops. Furthermore, feature technology in general also represents a high potential just within the area of sheet metal forming where it can be used to provide additional information for designing manufacturing processes and constructing tools and devices in manufacturing systems.
Determination of Friction Coefficients for the FE-Analysis of Sheet Forming of Tailored Welded Blanks
Authors: Tolazzi Massimo , Merklein Marion
Published: March 2009

The finite element analysis of sheet forming processes needs precise and reproducible data of the tribological conditions, which influence the material flow during the process. In this work the friction coefficient and its dependency on the hardness and surface topography of the blank are investigated. The selected materials are four steels with different surface qualities and coatings, FeP04, ZStE340, DP450 and TRIP800, which are joined by laser welding. Moreover, each material both with and without weld seam, was tested at three different values of normal contact pressure in a strip drawing test. The topography of both the base material and the weld line was obtained by measuring the surface roughness and implementing the data in a surface analysis software. Micro-hardness profiles along the tailored welded blanks were also determined. The strip drawing test was used to measure the friction coefficient between sheet metal and tool both in the case of
tailored welded blanks and base material. The comparison between the results obtained for base materials and tailored welded blanks shows that the presence of the weld seam causes a clear increase of the friction between blank and tool.
The Development of Cold Forging Progressive Die Technology for the Case of Slim Type Spindle Motor
Authors: Tai C.W. , Tsai H.-C. , Tsai Sheng Chi
Published: March 2009

To promote the competitiveness of 3C industries in Taiwan, the cold forging progressive die technology is still being developed. The technology can rapidly and steadily produce high quality and complex shape products. Moreover, it can reduce manufacturing costs and time, too. The design for the cold forging progressive die process for the slim type spindle motor case consists of three main stages. First, we arrange a reasonable and appropriate process planing for the case. Second, we use computer software to simulate the main forming processes. Third, we perform a
simple forming test to check up the results of the simulation. According to the test results, the main forming of the slim type spindle motor case is similar to the results of the simulation. Consequently, we demonstrate that the one-piece slim type spindle motor case can be manufactured with a progressive die. The forming processes include piercing, coining, upsetting, ironing, sizing, and blanking. The results from computer simulation and forming test result indicate that a reasonable effective
manufacturing process for the one-piece slim type spindle motor case is possible. The final conclusions will be introduced in the article. In addition, we also discuss the possible problem involving the production of the slim type spindle motor case.
Non-Traditional Forming Limit Diagrams for Incremental Forming
Authors: Jeswiet J. , Young David J. , Ham M.
Published: March 2009

Although not standard, Forming Limit Diagrams, FLD’s, are used throughout the
automotive industry as a preliminary tool to determine if a sheet metal forming process is capable of forming a good part. FLD’s show a limited range of strains on the diagram; typically the range is 0 to 1 on the major strain axis. A new rapid prototyping process called Single Pont Incremental Forming, SPIF, experiences strains over 3. As FLD’s do not typically cover that level of strain, a new method for developing FLD’s is needed. Such a method is proposed in this paper. Research has been conducted with five different shapes, formed using Single Point Incremental Forming. The part shapes utilized contain the most common combinations of angles and curves observed in formed sheet metal products. The strains encountered in forming each of these parts are measured and the strain data is then plotted on the same FLD. These new FLD’s can then be utilized as a predictive tool for engineers to determine if their design can be produced using the SPIF process.
Laserforming of 3D Features
Authors: Duflou Joost R. , Callebaut B. , Kruth Jean Pierre
Published: March 2009

The aim of the research presented in this paper is to investigate the feasibility of
generating 3D features in sheet metal blanks using laser forming techniques. Aiming for systematic process planning and a good process control capability, only the temperature gradient mechanism is considered for this purpose. The research has been performed on a 6 kW CO2 laser CNC platform. In a first part, bending along curved lines and bending close to edges are investigated. In a second part, these findings are applied for the creation of a louver. A dimensional measurement system is used for analyzing the geometric dimensional characteristics of the formed shapes. It is found that louvers can be made as a local 3D feature in a sheet metal blank. Based on these initial results, it can be concluded that form features, which are traditionally generated by means of form tools on a punching machine, can to some extend also be obtained by means of industrial lasers, widening the application range of these machine tools.
Forces in Single Point and Two Point Incremental Forming
Authors: Jeswiet J. , Duflou Joost R. , Szekeres Alexander
Published: March 2009

Forces have been measured in Two Point Incremental Forming and Single Point
Incremental Forming of Sheet Metal. It is necessary to know the magnitude of these forces when trying to determine if the equipment available is capable of Forming Sheet Metal by either one of the two foregoing processes. The magnitude of forces is also needed when developing appropriate models for the Incremental Sheet Forming. The forces measured in forming cones and truncated pyramids from AA 3003-0 are described.
Further Experimental Investigations and FEM Model Development in Sheet Incremental Forming
Authors: Giardini Claudio , Ceretti Elisabetta , Aldo Attanasio
Published: March 2009

Sheet Incremental Forming (SIF) is a modern technique that deforms the sheet on a positive or negative die using a simple punch mounted on a general purpose CNC machine. Several working parameters (tool path, spiral width and tool depth) have been studied in previous papers [1, 2] analyzing their influence on a simple part when working AISI 304 or Cu DHP sheets. The main problem was to study the process feasibility, that is, the possibility of correctly deforming the pieces without breaking them. The research reported here has been focused mainly on other two important variables, studying their influence on the final part quality: the punch diameter and its velocity when deforming the sheet. Surface roughness and minimum thickness of the deformed sheet have been chosen as parameters for analyzing and evaluating the process efficiency. In FEM analysis, a simulation model was developed and implemented considering Cu DHP sheet. The comparison with
experimental results was used to validate the simulation model and to identify the most suitable simulation parameter values (friction coefficient between various elements and blank holder force). The developed and validated model can be used for studying the process optimization. The results obtained in this paper can also be used as guidelines for the correct design of Sheet Incremental Forming process.
Tribological Investigations on Coated Steel Sheets Using the Dry Film Lubricant Drylube E1
Authors: Tolazzi Massimo , Meiler M. , Merklein Marion
Published: March 2009

Tribological aspects strongly influence the deep drawing behaviour of sheet metal, being responsible for both the punch force and the material draw-in from the flange. Recent developments in lubrication technology have shown that dry film lubricants can be a good alternative to conventional fluid lubricants in case of aluminium sheets. Their main advantages are the homogeneous distribution on the blank surface, the good adhesion to the surface and the possibility of applying it already in the rolling mill. In order to introduce this technology in series production also for steel sheets more knowledge concerning the influence of the lubricant amount on the
drawing forces is needed. A further important aspect to be considered is the surface quality of the steel grades and its interactions with the dry lubricant. In this paper four steel grades with different mechanical and/or surface properties are considered. After a microscopical and topographical investigation of the surface the materials were tested in a cup drawing test after applying two different amounts of the dry film lubricant Drylube E1. Further process parameters which were varied are the blank holder force FN and the drawing ration b. In this way, information about the
influence of the lubricant amount on both the drawing force and on the maximum blank holder force FZ could be obtained for three different values of b. The experimental results have shown how a strong decrease of the lubricant amount (from 1.0 down to 0.5 g/m2) causes, at a given drawing ratio, only a small increase in the maximum drawing force as well as a small increase in the maximum blank holder force.
Buckling Texturing Technology for Increase in Stability of Thin Sheet Metal Structures – Simulation and Application
Authors: Behrens A.W. , Ellert J.
Published: March 2009

Embossing is a well known method to improve the transverse rigidity of thin sheet metal plates. This paper deals with a special embossing method where bulges get embossed into the surface of a cranked workpiece by hydrostatic pressure. The base for describing the production process is the elementary bulge structuring process at which a bionic bulge pattern gets embossed into the surface of a cylindrical shell. This structure enables highest amount of stiffness. By FEMsimulations the main process parameters and the optimal dimensions of the bulges are ascertained. The identified bulge geometry is the base for the design of the structuring tool. In industrial applications the structuring process will be a rolling process with an elastomere coated pressure roll, followed by a rebending operation. The simulation of this complex process demands an analogous model based on a half shell, which is virtually straightened. Then the bending resistance of a so achieved bulge structured plate is calculated under a three-point-bending load. Using the same computing procedure a realistic automotive body part is investigated. The whole process combines CAD & FEM techniques in a new and efficient way.
Metal Flow and Die Filling in Coining of Micro Structures with and without Flash
Authors: Thome M. , Hirt Gerhard , Rattay B.
Published: March 2009

The continuing miniaturization of production systems and products poses a challenge for metal forming technologies to produce precise small scale products with microscopic geometric details. Thin metal plates with channel structures are considered to be typical examples for microfluidic applications [1,2]. In this study the coining process of sheet metal to produce channel and rib structures is examined in terms of geometrical die parameters and tool design. For this reason extensive experimental series and numerical simulations have been realized and evaluated.
Experimental and Numerical Investigation of the Formability of Laser Welded Patchwork Blanks
Authors: Lamprecht K. , Geiger Manfred
Published: March 2009

Within the past decades tailored welded blanks have become a key product for the
construction of lightweight automotive bodies. Following the principle of applying material only where it is really needed results in an improved stiffness and crash worthiness of the body-in-white, while at the same time weight and production costs may be reduced. An alternative to the concept of tailored blanks is the so-called patchwork blank technique. The principle of patchwork blanks is to add a flat piece of sheet metal onto the main blank in the areas where reinforcements are required.
The assembly can be done by adhesive bonding, resistance spot welding or laser welding prior to forming. The major benefits of this technique in comparison to tailored blanks are the abolition of cutting operations and a high flexibility regarding the shape and position of the reinforcement. Even if there is a big application potential for patchwork blanks in automobile production, practical realisation of this innovative technique is hindered due to a lack of knowledge regarding the
formability of patchwork blanks. In this study the formability of laser welded patchwork blanks is investigated by means of experimental trials and finite element analysis. In order to simulate accurately the forming processes of patchwork blanks using finite element analysis, knowledge about the characteristics of the weld metal, including the weld bead and the heat affected zone, is essential. Microhardness
measurements have been applied to analyse the heat affected zone and to determine its lateral dimensions. The constitutive behaviour of the weld metal has been investigated by uniaxial tensile tests with a special sample geometry. The results obtained from these experimental investigations have been used to define different modelling techniques for the finite element analysis of patchwork blank forming processes. It can be shown that the consideration of the modified material properties along the weld seam leads to an improvement of the accuracy of the numerical calculation.
Analyses of the Forming Limit Diagram in Digital Environment
Authors: Pepelnjak Tomaz , Petek Aleš , Kuzman Karl
Published: March 2009

The determination of the forming limit diagrams (FLDs) for sheet metal can be
influenced by testing parameters and a chosen testing procedure. Many different tests have been applied and recent work has resulted in some guidelines to decrease the influence of the testing method and the expertise of an individual laboratory. In the last years some methods have been developed which tend to be independent from the individual expertise, but comprehensive experimental work is still indispensable to obtain the material’s necking and failure limit. The experimental work could be omitted by prediction of the FLD with numerical simulations. The paper presents a methodology to determine the whole area of the FLD for sheet metal in a
digital environment. The material thinning has been analysed with the finite element simulation using the ABAQUS program. The Marciniak testing procedure has been chosen to determine the FLD. The thickness strain as a function of time as well as first and second time derivation of the thickness strain have been analysed for the critical specimen areas where the onset and propagation of necking occur.
Finite Element Analysis of Plate Bending Problems Using Transition Plate Elements
Authors: Kanber B. , Bozkurt O.Y.
Published: March 2009

In this work, four different transition plate elements are derived and used for the finite
element analysing of plate bending problems. The Mindlin plate theory is used in the element formulations. So the transverse shear is also included in the solutions. The coefficients of trial functions are selected from the Pascal triangle using a practical rule. An existing finite element program is improved by adding new type transition plate elements. All Fortran IV codes are changed to Fortran 95 codes in the existing program. To verify the developed elements, a cantilever plate and plate bending problems are solved. Their results are compared with ANSYS results.
Poly(4-vinylpyridine) Coated CdTe Core/Shell Quantum Dots
Authors: Dai Zhao , Li Ping , Zhang Ji Mei , Xu Shi Chao , Guo Ning , Zheng Guo , Sun Bo
Published: March 2009

A kind of novel quantum dots (QDs) with poly(4-vinylpyridine) (PVPy) as shell and CdTe QDs as core was presented in this work. This core/shell ODs can conjugate DNA easily because the surface pyridyl exist on QDs, and which has potential application in DNA biosensors field. CdTe QDs were prepared in aqueous solution with 3-mercaptopropionic acid (MPA) as stabilizer. It was found that the fluorescent intensity of QDs was depended the reflux time. Following the increase of reflux time, the fluorescent intensity of QDs reached the maximum at 10 h with about 10 nm in diameters. And the fluorescent intensity of QDs was also increased. When the reflux time was 10 h, the diameter of QDs would increase to about 10 nm. After adjusted the pH of QDs solution system to 7.0, the MPA stabled QDs were purified by ultracentrifugation and freeze-drying respectively. The polymerization was performed in water when 4-vinylpyridine (VPy) used as monomer, N,N’-methylene-bisacrylamide (MBAAm) as crosslinker, potassium persulphate (PPS) as initiator and MPA stabled QDs as seeds. The surface carboxyl of MPA on QDs could promote the form of PVPy coated CdTe QDs. It was shown that the fluorescent intension of core/shell QDs was decreased following the polymerization and the diameter of QDs could increase to 20-30 nm.
Synthesis and Characterization of CdTe/PAA/P-4-VP Quantum Dots
Authors: Jiang Yu Hua , Zhang Ji Mei , Dai Zhao , Xu Shi Chao , Yin Yong , Zheng Guo , Sun Bo
Published: March 2009

In this article, a novel kind of nanomaterials called CdTe/PAA/P-4-VP quantum dots (QDs) was studied. CdTe quantum dots were synthesized by mixing CdCl2 solution containing Mercaptopropionic Acid (MPA) stabilizer at pH 9.1 with NaHTe aqueous solution and refluxing 1 h at 96 °C. Then, CdTe solution obtained was adjusted to pH 7.5 by poly(acrylic acid) (PAA) which could provide many carboxyl groups to CdTe QDs. PAA-modified CdTe (CdTe/PAA)solution was transparent during 2 months and the fluorescence of CdTe/PAA was higher than that of CdTe at the same pH, which indicated that PAA increased the stability and fluorescence intension of CdTe QDs. Then poly(4-vinylpyridine)-coated CdTe/PAA QDs (CdTe/PAA/P-4-VP QDs) were prepared after 4-VP was polymerized on the surface of CdTe/PAA nanoparticles by using N, N'-Methylenebisacrylamide as crosslinker and potassium persulfate as initiator. The parallel experiment in which PAA was replaced by HCl was also arranged and CdTe/P-4-VP QDs was gained. Fluorescence emission spectrum (FE), transmission electron microscope (TEM), and infrared spectrum (IR) were used to characterize CdTe/PAA/P-4-VP and CdTe/P-4-VP QDs. The FE spectrum of CdTe/PAA/P-4-VP QDs had an obviously red shift compared with that of CdTe QDs while the red shift in FE spectrum of CdTe/P-4-VP QDs was not obvious, which indicated that PAA played an important role in the synthesis of P-4-VP-coated CdTe QDs. The fluorescence of CdTe/PAA/P-4-VP QDs was one times higher than that of CdTe QDs, which suggested the advantage of CdTe/PAA/P-4-VP QDs in fluorescence application. TEM photos showed that the average size of CdTe/PAA/P-4-VP QDs was 13.3nm. The IR spectrum of CdTe/PAA/P-4-VP QDs showed that characteristic absorption peak of carboxyl groups from PAA or/and MPA was wide and other absorption peaks of CdTe/PAA/P-4-VP QDs were the same with that of 4-VP which confirmed that P-4-VP coated CdTe QDs.
Preparation Process of Metal Matrix Micro/Nano-Powders Reinforced by Nanometer Particles
Authors: Wang Hong Yu , Zuo Dun Wen , Yu Shou Xin , Zhang Dan
Published: March 2009

The compound of micron powders and nanometer powders is a magnificent step in the application and development of metal matrix composite reinforced by nanometer particles. By taking nano-Al2O3 powders and Ni-based micron powders as the research object, the preparation process of metal matrix micro/nano-powders reinforced by nanometer particles with high energy ball-milling is discussed from three aspects: the additive process of nanometer powders, the additive content of nanometer powders, and the required ball-milling time in the paper. The results show that the additive process of nanometer powders which uses directly the dispersed uniformly nanometer suspensions as grinding medium can effectively decrease and avoid nanometer powders’ agglomeration of composite powders. Nanometer particles are well distributed in the composite powders. The optimum additive content of nanometer powders is consistent with the theoretical model of mixture ratio, which is determined by the ratio of the average diameter of micron powders and nanometer powders and their density of corresponding solid materials. Meanwhile, the required ball-milling time for preparation of better uniformity composite powders is no more than 0.5hr. This implies that the preparation process has a high productivity. Moreover, the preparation process is verified through other nanometer powders including nano-SiC powders and nano-CeO2 powders.
WO3 Nanostructures Synthesized by a Sonochemical Strategy
Authors: Sun Shi Bin , Zou Zeng Da , Min Guang Hui
Published: March 2009

A simple sonochemical synthesis of tungsten trioxide hydrate with various morphologies has been developed by using tungsten hexachloride (WCl6) as precursor and water, ethanol and their mixture as solvent, followed by annealing in a tube furnace. The resulting products were structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM) and differential thermal analysis (DTA). Results show that nanowhiskers emanating from the core of nanoparticles have been obtained with ethanol as solvent, and that nanoplates and nanosheets were formed when water and/or mixed ethanol and water was used as the solvent, respectively. The continuous changing supersaturation of tungsten trioxide may account for the formation of nanowhiskers. The formation of nanoplates or nanosheets may be associated with the selective adsorption of solvent molecules on the WO3 crystals. Due to a combination of the loss of chemical bonded water and crystal growth, the as-synthesized tungsten trioxide hydrate underwent apparent morphological evolution during thermal processing.
Study of Microfluidic Chip with In Situ Prepared Chitosan Membrane Immobilized with Glucose Oxidase
Authors: Cao Qiang , Xu Yi , Song De Fu , Han Wei Wei , Dong Xi Zhe
Published: March 2009

A microfluidic chip with in-situ prepared chitosan membrane immobilized with Glucose Oxidase was developed as glucose oxidase reactor to detect human serum. The chitosan was prepared in-situ in the micro-channel as the immobilization material.Then,GOD was immobilized in the chitosan membrane, in which factors, such as the glutaraldehyde concentration, time of crosslinking and immobilization, buffer pH, were optimized with orthogonal experiments. The concentration of glutaraldehyde was finally chosen as 0.15%, time of crosslinking as 60 min, immobilization time as 15 h, and buffer PH as 8.0. The immobilization efficiency could reach up to 5U•cm2. The homemade microchip could be applied for rapid determination of glucose in serum, combining with the Luminol-K3Fe(SCN)3 Chemiluminescence reaction system. Under optimized conditions of sample velocity of 500uL•min-1, the concentration of K3Fe(SCN)3 of 1×10-2mol•L-1 and the concentration of luminol of 5×10-4 mol•L-1, the detection limit could achieved 1ug•mL-1.