bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a New Method for Producing Plane Expanded Metal by Laser Cutting and Forming of Metal Plates under Uniaxial Tension
Authors: Merklein Marion , Junker Daniel , Schaub Adam , Kretschmer Anne , Lechner Michael
Published: March 2015

The on-going trend to lightweight construction leads to a special focus on plane lattice structures as an alternative for solid metal plates. They demonstrate similar mechanical properties while taking up only a fraction of the normal material input and are thus economically favourable. Additionally, they fulfil functional and design aspects and therefore are used by several industries like the automobile. Nevertheless, the two most common types of lattice structures – perforated metal plates and expended metal plates – are either waste intensive or uneven and hence require additional rolling of the metal plate.Therefore, within this contribution a new and innovative approach for the production of plane lattice structures will be presented. The manufacturing process thereby consists of two steps. At first, a specially designed pattern is cut into metal plates via a laser. Subsequently, the plates are formed under uniaxial tension to realize the lattice structures. Based on the cutting length, cutting space and the row space different blanks with tailored lattice structures can be produced. From the experimental results first guidelines for the design of suitable patterns are derived. The investigations will be performed with precipitation hardenable aluminium AA6014.
Simulative Winding of Roll Formed Profile in Carcass Production for Flexible Pipes
Authors: Nielsen Peter Søe , Ormstrup Casper Alexander , Hartz Benjamin Arnold Krekeler , Nielsen Morten Storgaard , Bay Niels
Published: March 2015

In carcass production for flexible pipe systems roll formed profiles are wound around a mandrel forming an interlocking, flexible structure able to withstand collapse from outside water pressure or mechanical crushing. Carcass is often produced in lengths of several kilometres, which implies numerous welds between coils of stainless steel, often duplex grades. The welds are a source of failure, since fracture from time to time occurs here in the winding stage. A simulative test in form of three-point-bending is developed, which shows promising results together with simplified air- and v-bent profiles allowing offline testing of welds for optimisation purposes. Comparative studies are shown possible but discrepancies in boundary conditions cause the maximum strains in the simulative test to differ from those in production. A study of weld failure is done applying the simulative test and tensile tests using GOM ARAMIS 4M system for strain measurements. The results show strain localization at the weld from onset of yielding caused by the soft, heat affected zone next to the weld seam resulting in a local thinning of the strip similar to what is observed in production.
Numerical Analysis and Experimental Validation of the Thermo-Mechanical Flow Behaviour of the Hot Stamping Steel MBW® 1500
Authors: Potdar Bhargav , Graff Stéphane , Kiefer Björn
Published: March 2015

In virtual design of the hot stamping process, a reliable description of the material flow behaviour is an important input to ensure accurate estimations of the parts feasibility. Currently, to characterise the hot stamping material’s flow behaviour at elevated temperatures, tensile and upsetting tests are available. The measurement of the flow behaviour out of such tests, which is generally temperature and strain rate dependent, still remains a complex task. Therefore traditional methods to measure flow curves out of such measurements are not necessarily precise enough. In this contribution the authors focus on non-isothermal conductive tensile tests of the manganese-boron steel MBW® 1500 in order to understand its flow behaviour at elevated temperature. Numerical calculations using Finite Element Method (FEM) of the tests itself with correct boundary conditions as well as for all necessary phenomena are used to identify accurately the material’s flow curves by use of inverse optimisation. Finally, for validation purpose the identified flow curves out of the optimisation method were used to simulate the hot stamping of two different parts. Both geometries were chosen such that various strain paths are covered i.e. uniaxial tension to plane strain.
Design of Press Tools to Investigate the Hot Stamping Behaviour of Alternative Coatings for Press-Hardened Steel Parts
Authors: Close Damien , Feuser Peter , Lallement Régis
Published: March 2015

Due to oxidation and decarburization during heat treatment prior to hot stamping, various coating products have been developed in the last decades. Press-Hardened Steel (PHS) components for passenger cars are generally coated by aluminized or galvanized (GI) coatings. The aluminized coating presents a good formability at high temperature and permits forming and quenching components in the same press tools with a so called direct hot stamping method. Due to a strong cracking in the base material during direct hot stamping induced by liquid-metal embrittlement (LME), galvanized coated products must be pre-formed at low temperature and undergo heat treatment in separate press units. Moreover, the oxide scale formed on GI parts must be removed by abrasive blasting, whereas aluminized parts can be directly painted after hot forming. However, higher performance in corrosion resistance has been observed for galvanized parts, in particular in cosmetic and cut-edge corrosion. This increase is linked to the sacrificial effect or cathodic protection provided by the layer containing zinc. Daimler AG is investigating the possibility of improving performance of PHS body parts in terms of suitability for direct hot stamping and corrosion protection by developing new coating materials. In the following article, the main particularities and challenges involved in both current coating products will be introduced. The development of specific press tools for this study, as well as the corresponding simulation of hot forming will be presented. Finally, the hot forming behaviour and anticorrosive properties of both current products will be presented.
Improvement of the Ductility of Press-Hardened Plane Sheets through a Modified Heat Treatment
Authors: Konrad Tobias , Feuser Peter
Published: March 2015

Tailored press-hardening processes are used to reduce both production costs and component weight. The aim of these development methods is to generate regions zones in the component with both high and low tensile strengths. The B-pillar, for instance, needs high tensile strength in the region of the roof frame to prevent deformation. However, the connection to the body should have lower tensile strength to absorb the energy of a crash.Regarding the production process for tailored welded blanks, the tailored press-hardening processes for monolithic sheets need no joining operation. As an addition to recent publications, this paper presents a modified tailored press-hardening process, with a modified time-temperature process. Starting from the required tailored material properties of the part, with a sheet thickness of 1.5 mm, research has been done on the process window and process design.This contribution concentrates on modifications to the time-temperature profile. After heating the hot-dip galvanized, heat-treatable 22MnB5 steel above its austenitic temperature, the aim is to adjust the material’s mechanical properties within the cooling process.Based on the continuous TTT diagram, the cooling rate has an impact on the material’s mechanical material properties. Different proportions of constituents such as Bainite, Ferrite or Perlite are created by varying the cooling rate. Furthermore, during an intermediate stage in the cooling-down period, the holding temperature has an even stronger effect on the material’s microstructural composition and the corresponding mechanical properties. The rate of the transformation process changes, depending on the intermediate temperature. The third parameter investigated is the holding time at this intermediate temperature. As the holding time is increased a transformation, progressing from austenite to other constituents, can be observed.The results of this parametric study could be transferred to a prototype environment.
Flexible Rolling of Process Adapted Semi-Finished Parts and its Application in a Sheet-Bulk Metal Forming Process
Authors: Hildenbrand Philipp , Schneider Thomas , Merklein Marion
Published: March 2015

By applying bulk forming processes on sheet metals, thin-walled functional components with locally restricted wall thickness variations can be manufactured by forming operations. Using tailored blanks with a modified sheet thickness gradient instead of conventional blanks, an efficient controlling of the material flow can be achieved. One possible process to manufacture these semi-finished parts is a flexible rolling process. Based on an established process strategy new results for steels of differing strength and work-hardening behavior are presented in this paper. The influences of each material on the resulting process forces and blank properties regarding the same target geometry are discussed. The tailored blanks are hereby analyzed by their geometrical dimensions, like sheet thickness, and their mechanical properties, e.g. hardness distribution. Additionally, the possibilities of processing these tailored blanks in a deep-drawing and upsetting process are presented with a hereby focus on the residual formability of the tailored blanks.
Measuring Systems for Sheet-Bulk Metal Forming
Authors: Loderer Andreas , Timmermann Martin , Matthias Steffen , Kästner Markus , Schneider Thomas , Hausotte Tino , Reithmeier Eduard
Published: March 2015

In order to fulfil today’s demands on fast, efficient and sustainable production processes the sheet-bulk metal forming is being developed as a new forming technology within the scope of the SFB/Transregio 73. Characteristically for the sheet bulk metal forming is a three dimensional material flow, which allows for extensive freedom in the design process. To ensure maintaining all the advantages, provided by sheet-bulk metal forming, new inspection concepts for the produced parts as well as for the forming tools have to be developed. For a production-related inspection of produced parts a multi-sensor fringe projection system is under development, which will be employed to detect deviations of features’ form and size. With its sensors of varying measuring range and resolution a feature adapted inspection is possible. Additionally an optical fibre sensor is projected to detect small parts of interest in a very high resolution to enhance the possibilities of the multiscale multi-sensor system. A newly developed endoscopic fringe projection system is used to inspect parts that are out of reach for common optical measuring systems such as the forming tool of the process. This allows for a continuous measurement of tool features and thus the detection of slow growing wear. Challenging for measurement tasks in the sheet-bulk metal forming process are not only the complex geometries but also the harsh environmental conditions and especially for the parts’ inspection, the different surface parameters. In this article the surface parameters of the some sheet-bulk metal formed parts and forming tools will be explained, followed by a description of the different measuring systems. Finally an exemplary evaluation of the influence of the surface properties on an optical measuring system will be shown.
Optical 3D Metrology for Optimization of Sheet Metal Forming Processes
Authors: Galanulis Konstantin , Adolf Stephanie , Friebe Harald
Published: March 2015

3D optical metrology methods are increasingly used in the research of sheet metal materials and in sheet metal production processes. Optical measuring systems are implemented in different process stages, including design, sheet metal material research and component development, tool making and production as well as series accompanying quality control.Today’s development processes are initially driven from computational methods. Especially for the development of sheet metal components the numerical forming simulation is an important tool. However, performing a reliable forming simulation requires accurate input parameters like 3D geometry data for meshing, material parameters and boundary conditions which can be obtained with optical measuring systems. Further on the validation of these numerical simulations is supported with optical full-field sheet metal forming analysis.In the tool manufacturing phase 3D measurement data contributes in reducing the time frame for CNC machining processes, for the try-out phase, future tool reproduction as well as for repair and maintenance.With automated 3D measuring solutions series accompanying quality control is performed to determine tool wear and to shorten the response time if problems in the production occur.This paper is extending past work [1] and discusses today’s contribution of optical 3D measuring techniques in sheet metal component development and production, covering the areas of determining input parameters for sheet metal forming simulations and its validation, tool manufacturing, including the try-out, and production quality control using automated optical measurement machines.
Formability Characteristics of Hot Stamped Ti6Al4V Sheets Electro-Chemically Modified on Surface for Biomedical Applications
Authors: Valoppi Beatrice , Bruschi Stefania , Ghiotti Andrea
Published: March 2015

Over these last decades Ti6Al4V has been largely employed for biomedical applications because of its biocompatibility and high strength-to-weight ratio. According to several studies, the implantation success is strongly dependent on the characteristics of its surface, since the roughness and the chemical composition of the surface play an important role in the osseointegration of the implant and in its bioactivity, respectively.In this paper different thermo-electro-chemical treatments were applied to Ti6Al4V sheets to increase their roughness for biomedical applications. The Ti6Al4V sheets underwent three different treatments, namely acid etching, acid etching followed by anodization and etching in a hydrothermal reactor, and finally furnace annealing.After the etching and annealing treatments, the surface morphology of the samples were analysed through Scanning Electron Microscopy, while its chemical composition was identified through the Energy Dispersive Spectroscopy. The surface roughness and topography were evaluated by using a 3D profilometer. Furthermore, the bioactivity of the treated samples was evaluated by diving them in Simulated Body Fluid and then analysed through SEM and EDS analyses.Based on these results, the treatment assuring the best performance in terms of roughness and bioactivity was identified and then applied to tensile samples tested at 700°C and strain rates of 0.1 and 1s-1 to evaluate the impact of the surface treatment on the material formability and, therefore, to prove the feasibility of applying the hot stamping process to surface modified sheets.
Evaluation of Drawing Force and Thickness Distribution in the Deep-Drawing Process with Variable Blank-Holding
Authors: Lazarescu Lucian , Nicodim Ioan , Banabic Dorel
Published: March 2015

In the deep drawing process, the blank-holding force (BHF) is an important process parameter affecting the energy consumption and the successful production of parts. In the present work, both experiments and finite element simulations have been conducted to investigate the influence of constant and time variable BHF on drawing force (DF) and thickness distribution in the deep drawing process of cylindrical and square cups. A finite element model was developed in the AutoForm software and validated with experiments. The developed model has been used for the simulation of deep drawing process of AA6016-T4 aluminum alloy sheet. The experimental and numerical results show that, using a variable instead of a constant BHF, the DF can be decreased in the expense of wall thickening.
A New Approach to the Evaluation of Forming Limits in Sheet Metal Forming
Authors: Merklein Marion , Maier Andreas , Kinnstätter Daniel , Jaremenko Christian , Affronti Emanuela
Published: March 2015

The forming limit diagram (FLD) is at the moment the most important method for the prediction of failure within sheet metal forming operations. Key idea is the detection of the onset of necking in dependency of different sample geometry. Whereas the standardized evaluation methods provides very robust and reliable results for conventional materials like deep drawing steels, the determined forming limits for modern light materials are often too conservative due to the different failure behavior. Therefore, within this contribution a new and innovative approach for the identification of the onset of necking will be presented. By using a pattern recognition-based approach in combination with an optical strain measurement system the complete strain history during the test can be evaluated. The principal procedure as well as the first promising results are presented and discussed.
Flexible Manufacturing of Double-Curved Sheet Metal Panels for the Realization of Self-Supporting Freeform Structures
Authors: Bailly David , Bambach Markus , Hirt Gerhard , Pofahl Thorsten , Della Puppa Giovanni , Trautz Martin
Published: March 2015

Product development is complex due to the manifold requirements resulting from various perspectives, such as design, production, safety and sales. A concurrent engineering (CE) approach permits to respect all perspectives in the early development stage. However, in the architecture and construction sector for example, CE is particularly difficult to realize, because the central steering for this collaboration process is missing. Thus, the application of CE in the research sector can promote technical progress and cost reduction. In the specific field of freeform architecture, in most cases an individual shape of single components is unavoidable and the use of standard components impossible. Due to missing universal and mature construction concepts for freeform buildings, they are mostly realized with customized solutions often including material-consuming substructures, while the visible skin has only limited structural and functional properties.In this context the present paper proposes a novel universal panel system made of double-curved sheet metal layers enabling the assembly of self-supporting lightweight structures for the realization of freeform surfaces. The panel system has been developed in cooperation of architects, construction and production engineers, successfully applying an interdisciplinary CE approach. As a result, the concept allows for material and cost efficient solutions applicable for a wide range of freeform applications. The detailed development of the panel system is still in progress.Besides the general panel concept, the paper presents in particular the corresponding manufacturing chain and the tooling concept. Accounting for the varying part geometries in this application a flexible manufacturing chain based on the combination of stretch forming and incremental sheet forming has been developed. The entire production process is implemented in a single machine setup and successfully tested on a small-scale prototype.
Enhancement of Lemaitre Model to Predict Cracks at Low and Negative Triaxialities in Sheet Metal Forming
Authors: Isik Kerim , Doig Maria , Richter Helmut , Clausmeyer Till , Tekkaya A. Erman
Published: March 2015

Advanced high strength steels are still one of the best alternatives for light weight design in the automotive industry. Due to their good performances like high strength and high energy absorption, those steel grades are excellent for body in white components. Because of their restricted ductility, which sometimes leads to the formation of cracks without or low necking during forming operations, conventional forming limit diagrams may fall short. As a remedy, an enhanced variant of the Lemaitre continuum mechanical damage model (CDM) is presented in this work.Previous model extensions of the Lemaitre model improved the damage prediction for the shear and compression dominated stress states by introducing an additional weighting factor for the influence of compression on damage evolution, the so called crack closure parameter h. However, the possible range of the fracture behavior predicted by such models for low and negative stress triaxialities is limited. In this work, the Lemaitre CDM has been enhanced by considering the maximal shear stress to predict the fracture occurrence under shear. Previous models for the effect of void closure on damage evolution are reviewed and a novel model enhancement taking into account the maximal shear stresses is described. The determination of the damage model parameters is presented for a dual phase steel. For this particular material, the response of model enhancement on the failure prediction is discussed for a test part.
Creep Behaviour of AA6016 during Automotive Paint Drying Processes
Authors: Regensburger Jochen , Mendes de Lima Leticia , Albiez Christoph , Weigel Patricia , Drossel Welf Guntram
Published: March 2015

Modern car-bodies consist of different types of metals in order to gain the best crash performance at minimal weight. After the press and body shop, the bodies in white run through several paint drying processes, where also alloys of the 6xxx series become heat-treated. Consequently, the different thermal expansion behaviour of joined aluminium-steel components leads to high bending stress conditions within the car body structure while they heat up to 200 °C. In order to describe the process deformations numerical simulations were developed, where appropriate material models are necessary. Especially aluminium alloys with a melting point of about 600 °C can exhibit viscoplastic behaviour at 200 °C under stress. In this work, creep characteristics of the aluminium alloy AA6016 are investigated using a bending test. Based on these results an adequate model for finite element (FE-) simulations of creep strains is pointed out, which can be used for novel analyses of the whole car body in the automotive e-coat drying process.
Sheet Metal Laser Cutting Tool Path Generation: Dealing with Overlooked Problem Aspects
Authors: Dewil Reginald , Vansteenwegen Pieter , Cattrysse Dirk
Published: March 2015

This paper deals with non-trivial problem aspects of laser cutting tool path generation that, to the best of our knowledge, received relatively little attention in the scientific literature. It is shown that some aspects such as plate edge nesting, skeleton and remnant cutting, and clamp positioning can be modeled and solved with little additional effort using existing tool path algorithms. However, concepts such as collision avoidance, pre-cut optimization, and bridge utilization prove to be more challenging and will require more profound algorithmic adjustments if these have to be taken into account fully. An even harder problem aspect is generating tool paths that are thermally feasible. Since laser cutting introduces net heat into the metal sheet, the metal sheet tends to heat up as the cutting progresses. Quality deterioration can occur if the laser spends too much time cutting in the same region. It is shown how to model the easy problem extensions in order to handle them using existing problem approaches and solution approaches are suggested to tackle the harder concepts. In addition, a proof of concept is presented that shows that thermal feasible tool paths can be generated through a multi-start heuristic utilizing a thermal penalty function. A finite difference method iteratively (or concurrently dependent on the used heuristic) evaluates the thermal feasibility and updates the penalty function.
Structure and Electrochemical Properties of La1-xBaxCoO3 Powders as Negative Electrode Materials for Ni/MH Batteries
Authors: Liu Peng , Hu Jing Yun , Yao Qing Rong , Deng Jian Qiu , Wang Zhong Min , Zhou Huai Ying
Published: March 2015

The perovskite-type oxides have a newly application for alkaline batteries due to the excellent cyclic performance. In this work, La1-xBaxCoO3(x= 0.2, 0.4, 0.6) powders were prepared by a sol-gel method as negative electrode materials for Ni/MH batteries, and their phase structure and electrochemical properties were investigated in details. The effect of Ba substitution on electrochemical kinetic properties, including the exchange current densityI0and the hydrogen diffusion coefficientD, of La1-xBaxCoO3electrodes were also evaluated. X-ray diffraction analysis shows that La1-xBaxCoO3(x= 0.2, 0.4, 0.6) perovskite-type oxides consist of two phases, La0.5Ba0.5CoO3and BaCoO2.70. The discharge capacities of La1-xBaxCoO3negative electrodes tested at 40 mAg-1are 65.6, 76.6 and 88.3 mAhg-1whenx= 0.2, 0.4 and 0.6, respectively. Among the electrodes, La0.8Ba0.2CoO3electrode has the highest discharge capacity retention ratio of about 87% after 50 cycles at room temperature.
Controlled Growth of ZnO with Different Morphologies on Zn Foils by a Simple Aqueous Solution Method
Authors: Sun Qing Ling , Chang Yong Qin , Shao Chang Jing , Long Yi
Published: March 2015

Nanostructured ZnO with versatile morphologies has great potential applications in many fields. In this work, ZnO materials with different morphologies were deposited on Zn foils by a simple aqueous solution method, and the shape of ZnO can be controlled by the concentration of Cl ions in the solution. Rods, spheres and platelets were obtained respectively with the concentration of Cl ions increase. The competition between Cl ions and growth units in the solution results the formation of ZnO materials with different morphologies. At the same time, the preferential orientation of the crystal plane is also changed by the concentration of Cl ions. The different morphologies of ZnO grown form this kind of solution method was also explained.
Influence of Electron-Phonon Coupling Coefficient on Properties in Femtosecond Laser Ablation
Authors: Xiang Ran , Tan Xin Yu , Wei Hui Li
Published: March 2015

Thermodynamics effects generated by femtosecond laser ablation are very important. In this work, the numerical simulation of high-energy femtosecond laser ablation especially the electro-phonon coupling coefficient influence of high-energy femtosecond laser ablation on metal target was studied. A new two-temperature model (TTM) which considered the effects of electron density of states (DOS) on electron-phonon coupling coefficient was first established, then the temperature evolvement for electron and lattice in different electro-phonon coupling coefficient G, and the effect of G on electron temperature and lattice temperature and electron-phonon coupling time were emphatically analyzed. The results showed that the electron-phonon coupling coefficient strongly affected the surface electron temperature and coupling time in the femtosecond laser ablation. The smaller the electron-phonon coupling coefficient was, the more the energy transmission from electronic to ion subsystem. As a result, the smaller the value of electron-phonon coupling coefficient, a more rapid decline for the temperature of electronic sub-system achieved. This work will offer help for the future investigation of material fabrication by femtosecond laser ablation.
Effect of Particle Size of Natural Flake Graphite on the Size and Structure of Graphene Oxide Prepared by the Modified Hummers Method
Authors: Xian Hai Yang , Peng Tong Jiang , Sun Hong Juan
Published: March 2015

The effect of particle size of natural graphite on the size and structure of graphene oxide (GO) was investigated by using natural flake graphite (NFG) with different particle size. GO was prepared by modified Hummers method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, laser scattering particle size distribution analyzer and Atom force microscopy (AFM) were used to identify the characteristics of NFG and GO. The results provide evidence of how the graphite particle size affects the oxidation process and sheet size of the GO. Varies size monolayer GO sheets could be produced from the graphite with different particle size. The sheet size of GO is much smaller than that of the graphite, and the sheet size reduced multiple is proportional to the graphite particle size. The smaller particle size graphite is easily to be oxidized for a higher concentration GO suspension, and for more defect in the structure. Thus, this study leads to a better understanding of the preparation process of GO and provides a way to produce GO in different sheet size suitable for different applications.
Structural Features of Fibri-Form Silica from Short Chrysotile Fibers by Acid-Leaching
Authors: Song Peng Cheng , Peng Tong Jiang , Sun Hong Juan , Yu Yu Cao , Xian Hai Yang
Published: March 2015

The fibri-form silica was successfully synthesized from the short chrysotile fibers by inorganic acid-leaching. X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and N2adsorption isotherms were used to characterize the products. The results indicate that the fibri-form silica is a kind of noncrystalline material, and the content of SiO2in the fibri-form silica is 98.30%. From 50°C to 1200°C, the structure of fibri-form silica is stable. The average diameter of single fiber range from 20 nm to 50nm and the lengths are 50nm to 3μm. The surface area and pore volume of fibri-form silica are 369.22m2/g and 0.43cc/g, respectively. And the size of pore diameters are different, is one of mesopore materials presenting high quality filler and catalyzer carrier.
Seawater Corrosion Resistance of Low Heat Portland Cement Concrete
Authors: Wang Ning , Cheng Xiao Wei , Yang Yun Xia
Published: March 2015

With the analysis of the seawater corrosion effect on low-heat Portland cement concrete under wetting-drying test, the compressive strength and quality change of concrete test specimen were investigated for different test periods. According to the evaluation of seawater corrosion resistance, the low-heat Portland cement showed better corrosion resistance than that of ordinary Portland cement and moderate-heat Portland cement. Moreover, the corrosion mechanism was expounded through XRD and SEM analysis. It was found that lots of C2S in the low-heat Portland cement play an important role in corrosion resistance of cement concrete.
Stuy on Microwave-Assisted Grinding of Low-Grade Ludwigite
Authors: Liu Ya Jing , Jiang Tao , Deng Zhi , Xue Xiang Xin , Duan Pei Ning
Published: March 2015

The low-grade ludwigite is one of the complex and refractory ores. Based on the high energy consumption and inefficient in the grinding process and according to the microwave-assisted grinding principle, this paper studied the microwave absorption property of ludwigite and researched the effect of microwave heating on the grinding efficiency of it. The non-microwaved and microwaved samples were characterized with regard to the chemical components, mineral compositions, macroscopic structure and microstructure, grinding efficiency by methods of the chemical analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and grain size analysis, etc. The results indicated that ludwigite, with good microwave absorption property, was suitable for microwave processing. The grindability of microwaved ludwigite was related to the microwave power and microwave heating temperature. By the microwave heating temperature attained 500~650°C, many macro-cracks and micro-cracks were produced by thermal stress between different mineral interfaces, which resulted in the decrease of strength of ludwigite and easy levigation, but the mineral compositions had no obviously changed, which would not affect the subsequent magnetic separation. It was concluded that short, high-power treatments were most effective but over-exposure of the sample led to reductions in efficiency. Under the same conditions, the grinding efficiency of ludwigite was improved 24.54% higher than untreated ore, which significantly improved the grinding efficiency and reduced energy consumption.
Pitting Behavior of 304 Stainless Steel in Simulated Condensate in Refining High Sulfur and Salt Heavy Oil
Authors: Wang Xiao Hong , Guo Xiao Hua , Lin Yuan Hua , Li Ying Ying , Wang Shu Liang , Hu Hai Lun
Published: March 2015

The pitting behavior of 304 stainless steel in the simulated condensate with different salt content (4 mg/L, 8 mg/L, 16 mg/L, 32 mg/L, 64 mg/L) and sulfur content (1.2 g/L, 2.5 g/L, 5 g/L) was studied using potentiodynamic polarization curve and static immersion methods. The simulated condensate was simulating the condensed water in the unit of refining heavy oil with high salt and high sulfur. The results showed that with the increase in chloride ions concentration, the pitting potential of 304 stainless steel decreased and the pitting sensitivity increased. The pitting sensitivity of 304 stainless steel also increased with the increase in sulfide ions concentration. In several experimental mediums, when the concentration of chloride ions and sulfide ions were 64 mg/L, 5 g/L respectively, the number and the size of corrosion pits both were the largest, the pitting behavior was the most serious.
Formation and Mitigation of BaSO4 Scale in Oil Fields
Authors: Zhu Ming , Ren Cheng Qiang , Meng Yuan Yuan , Liu Li , Zheng Yun Ping
Published: March 2015

The deposition of BaSO4scale is always found in the oilfield. It is difficult to be removed. Therefore, it plays a negative role to the production. The effects of temperature and water chemistry on BaSO4scale have been investigated by using the conductivity method in this work. An environment-friendly copolymer was prepared to control the scaling of BaSO4. The copolymer was proved by static scale inhibition method, and weight-loss test that it has excellent scale inhibition performance and corrosion inhibition efficiency. Furthermore, FTIR spectra was used to prove that the scale inhibitor was polyepoxysuccinic acid (PESA).
Preparation and Characterization of Microporous Activated Carbon from Raw Anthracite
Authors: Wang Bo Tao
Published: March 2015

Activated carbon (AC) is a kind of artificial carbon materials with highly developed pore structure and high specific surface area. As sound adsorption materials, the AC shows excellent adsorption property, good chemical stability, high mechanical strength and easy-to-regeneration characteristics, which makes it a widely application in the fields of chemical industry, environmental protection, food and pharmaceutical industry, electrode materials, and so on [1-3].
Preparation of High Purity Spherical Silica Powder from Silica Fume
Authors: Sun Ning , Zhang Pei Cong , Qiu Ke Hui , Li Jun Feng , Liu Xiu Feng , Qiu Yu Chong , Yang Jin Chuan , Wang Xue , Xian Li Juan
Published: March 2015

High purity spherical silica powder was obtained using silica fume as the raw material in this study. The mixture acids of HF and HCl were used in the purification process to remove the impurities contained in the silica fume. The phase of the product was characterized by X-ray diffraction, indicating that the spherical silica powder was amorphous. The chemical composition of the product was investigated by X-ray fluorescence, showing the SiO2 content was 99.9096 wt%. It had been proved that the purification process could improve the dispersion of the product powder via the morphology comparison and the laser particle analyses. The experimental results showed that the parameters of the product spherical silica powder met all the standards of the electronic-grade packaging materials.
Efficient Visible-Light Photocatalysts from Sensitized TiO2 Nanospheres
Authors: Xu Xiao Yu , Wang Meng , Lin Lin , He Dan Nong
Published: March 2015

Sensitized TiO2 nanospheres with uniform diameter of ca. 100 nm were successfully synthesized by a hydrothermal method using urea as templates and subsequently employed as robust visible-light photocatalysts. The photocatalytic activities of the sensitized TiO2 nanospheres evaluated by photodegrading methyl orange (MO) were recorded, giving the best photocatalytic performance for the sample synthesized at 110°C for 36 h. The photocatalytic mechanisms of the sensitized TiO2 nanospheres were attributed to the reduction of bandgap energies and the sensitizing effect of melon. The resultant melon acted as a sensitizer to absorb visible light and induced electrons which participated in the photodegradation of MO molecules. The new concept was helpful to guide the synthesis of robust photocatalysts, dye-sensitized solar cells, or hybrid solar cells, and the results suggested that the sensitized TiO2 nanospheres were very promising for enhancing the visible-light photocatalytic activity of TiO2 photocatalysts.
Structural and Optical Properties of Cu2MnSnS4 Thin Film Fabricated by Sol-Gel Technique
Authors: Chen Lei Lei , Deng Hong Mei , Zhang Ke Zhi , Huang Ling , Liu Jian , Sun Lin , Yang Ping Xiong , Chu Jun Hao
Published: March 2015

Cu2MnSnS4 thin film was successfully prepared by a sol-gel technique on soda lime glass substrate from metal salts and thiourea. The structural and morphological properties of the fabricated film were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and atomic force microscopy. The combination of the X-ray diffraction results and Raman spectroscopy reveal that this obtained layer is composed by Cu2MnSnS4 phase and has a stannite structure with preferential orientation along the (112) direction. The scanning electron microscopy and atomic force microscopy results show that the synthesized thin film is smooth and compact without any visible cracks or pores. The band gap of the Cu2MnSnS4 thin film is about 1.29 eV determined by the UV-vis-NIR absorption spectra measurement, which indicates it has potential applications in solar cells.
Development of Chinese Exergy-Based Characterization Factors for Emissions in Life Cycle Impact Assessment
Authors: Zhang Yu Feng , Gong Xian Zheng , Wang Zhi Hong , Liu Yu
Published: March 2015

The development of eco-materials has become an important direction of materials science. Using appropriate methods to evaluate the environmental impacts caused by materials production is important for eco-materials research. For the purpose of obtaining more objective results to environment impacts, several exergy-based methods to indicate resource depletion have been established. However, no proper exergy-based evaluation methods for emissions in China have been reported. The objective of this study is to establish comprehensive exergy-based characterization model for life cycle assessment, and to apply this model to steel production.
Analysis of Cobalt Substance Flow through China in Year of 2012
Authors: Yan Kang , Guo Xue Yi , Tian Qing Hua , Li Dong
Published: March 2015

Substance flow analysis (SFA) of cobalt in China was carried out to analyze cobalt flows and stocks by using static SFA. Cobalt can be widely used in industry due to its high-melting point, high-strength, and well magnetism. In this static model, the relationship among inflows, outflows and stocks throughout the whole cobalt life-cycle in China were identified. According to the static model, the amount was calculated in the form of cobalt metal, in 2012, 29784t of cobalt was produced, and 30700t of cobalt was imported, 9400t exported and domestic consumption was 31700t, 9000t stocks of cobalt was consumed and 3000t old scrap was recycled in China. The ore index and recovery scrap resource of cobalt industry were 0.318 t/t and 0.136 t/t respectively.
Life Cycle Assessment of Metallic Copper Produced by the Pyrometallurgical Technology of China
Authors: Wang Hong Tao , Liu Yu , Gong Xian Zheng , Wang Zhi Hong , Gao Feng , Nie Zuo Ren
Published: March 2015

With the rapid development of industry in China, China has become the largest producer of refined copper as well as the largest consumer of copper in the world. In order to provide the support for decreasing the environmental impact of the copper pyrometallurgy of China, the life cycle assessment methodology was carried out in this study to identify and analyze the typical processes’ environmental load of refined copper production from ‘cradle-to-gate’ perspective. The results showed that the most serious environmental impact of copper pyrometallurgy was abiotic depletion potential and human toxicity. The abiotic depletion potential mainly comes from the copper ore mining, for this reason, increasing the use of renewable copper is an effective means to alleviate environmental load of our country copper pyrometallurgy industry. Meanwhile, reducing the direct and indirect discharge of poisonous and harmful elements (e.g. heavy metals) from the copper ore mining stage and the copper smelting process could decrease the human health damage efficiently.
Influence of Sputtering Power on the Structure, Optical and Electric Properties of Cu3N Films
Authors: Chen Li Na , Leng Jin Feng , Yang Zhong Xi , Meng Zhi Chao , Sun Bin
Published: March 2015

The Cu3N films were deposited successfully by reactive direct current magnetron sputtering, the films were comprehensively and systematically characterized by X-ray diffraction analyzer (XRD), UV-Visible spectrophotometer, four-probe resistance tester and other instruments. Results showed that under low deposition power (80W~100W), crystal orientation increased, which is attributed to higher energy under higher power. When sputtering power exceeded the value, excessive energy led to anti-sputtering hindering the process of further nucleation and growth of films. The transmittance of the films deposited under 100W reached the peak value of 78% on the scope of near-infrared light, and optical band gap (Eg) of 1.35ev. The resistivity of Cu3N films increased from 9.68×102Ω.cm to 2.12×103Ω.cm with increasing in sputtering power up to 100W.
Microstructure and Dielectric Properties of (Ba, Ta) Co-Doped Sr2Nb2O7 Ceramics
Authors: Chen Gang , Gong Chun Wei , Fu Chun Lin , Peng Xiao Dong , Cai Wei , Gao Rong Li , Deng Xiao Ling
Published: March 2015

(Sr1-xBax) 2(Nb0.9Ta0.1) 2O7 (SBNT) ceramics were prepared by solid state reaction. The crystal structure of SBNT ceramics, surface morphology and dielectric properties were studied using XRD, SEM and LCR instrument analyzer, respectively. The results show that the grain size decreases with increasing Ba concentration, and all samples show single phase, no second phase can been observed. Addition of Ba ion can improve the dielectric properties of SBN ceramics. The dielectric constant increases first, then decreases; the maximum value (εr=97) can be obtained at x=0.1, the dielectric constant changes slightly with increasing wide frequency.
Ferroelectric and Photovoltaic Properties of Mn-Doped Bismuth Ferrite Thin Films
Authors: Cai Wei , Fu Chun Lin , Gao Rong Li , Jiang Wei Hai , Deng Xiao Ling , Chen Gang
Published: March 2015

Bismuth ferrite is an important material in ferroelectric photovoltaic field, because of its narrow band gap and large polarization. Doping is a common method to further improve the photovoltaic properties of bismuth ferrite. Mn-doped bismuth ferrite thin films were prepared by sol-gel method. The effects of manganese on the crystal structure, ferroelectric and photovoltaic properties have been investigated. The result indicates that Mn-doped bismuth ferrite thin films are single phase and the lattice constant increases with the increase of manganese content. As manganese content increases, the remnant polarization and coercive electric field increase, while the short circuit photocurrent density and power conversion efficiency decrease. The open circuit photovoltage increases first and reaches the maximum and then decreases as manganese content increases. The results indicate that enhanced ferroelectricity caused by addition of manganese doesn’t make improvement on the photovoltaic characteristic.
Research on Surface Roughness of Acid Etched Silicon Wafers
Authors: You Bai Ling , Zhang Xue Nan , Luo Chong , Sun Xi Kai , Wu Kai Fang , Feng Shuo , Zhang Li Hua
Published: March 2015

With the development of power electronic devices, the market demand for acid etched wafers of monocrystalline silicon, which has good surface properties and minimum surface roughness, increases rapidly. But there has been rarely report about the impact of acid etching process on the wafer surface roughness. This paper studied the surface roughness of the wafer, which was etched by mixture of HNO3, HF and HAC. The results showed that the surface roughness became smaller with the increase of wafer remove amount, while the roughness became worse with the service life extension of the acid; however, fluid infusion discharge method could be adopted in the etching process so that the etching acid system could achieve a relatively balanced state and wafer roughness became stabilized. The process mechanism was studied and analyzed in this investigation.
Microstructure and Properties of A-Site Doping Bi4-xYxTi3O12 Ferrroelectric Thin Films
Authors: Liu Hong Cheng , Zhang Wei Jun , Zhang Xiao Chen , Yu Qian , Wang Jue
Published: March 2015

s. Yttium-substituted bismuth titanate (Bi4-xYxTi3O12, BYT) thin films were deposited on the (111)Pt/Ti/SiO2(100) substrates by a modified Sol-Gel process and studied in this work in terms ofY3+-modified microstructure and phase development as well as ferroelectric properties. With the aid of the fist-principle, the position of Y3+substitution for Bi3+on the microstructure of BYT was studied.The phase change in the formation of BYT crystalline and the effect of Y3+substitution for Bi3+on the microstructure of BYT was studiedbyXRD. The results showed that the optimal properties of the obtained BYT ferroelectric thin films werex:0.6. The ferroelectric properties of the films were also investigated. When the Y-substituted contentxwas equal to 0.6, the remnant polarization was the largest. The remnant polarization 2Prvalue was equal to 16.02μC/cm2and the coercive fieldEcvalue was 88 kV/cm.
Microstructure, Phase Transformation and Mechanical Property of Ni-Co-Mn-In Alloy Prepared by Spark Plasma Sintering
Authors: Tian Bing , Ren Dong Cai , Tong Yun Xiang , Chen Feng , Li Li , Zheng Yu Feng
Published: March 2015

The microstructure, phase transformation and mechanical property of Ni-Co-Mn-In alloy fabricated by powder metallurgical method were studied in the present investigation. The initial polycrystalline alloy was prepared by arc melting and then milled to fine particles, finally the powder particles were sintered by spark plasma sintering (SPS) method to make the bulk alloy with refined grains. The size of as-milled particles was much smaller than the grain size of the initial arc-melted alloy. The particles can be successfully densified to form a compact bulk by SPS. The initial arc-melted alloy presented a good martensitic transformation behavior, whereas the martensitic transformation of the as-sintered bulk alloy disappeared. The compressive strength and fracture strain of the as-sintered alloy greatly enhanced as compared to the initial arc-melted alloy due to the grain refinement and strengthening of grain boundaries.