bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Surface Modifications on Friction, Using High-Feed Milling and Wear Resistant PVD-Coating for Sheet-Metal Forming Tools
Authors: Biermann Dirk , Freiburg Dennis , Hense Rouven , Tillmann Wolfgang , Stangier Dominic
Published: March 2015

Increasing technological requirements, as well as the demand for an efficient production demands high performance materials and enhanced manufacturing processes. The development of a new manufacturing process, sheet-bulk metal forming (SBMF), is one approach to produce lightweight forming parts with an increased number of functional properties while, at the same time, combining the advantages of sheet and bulk metal forming. For SBMF processes, the specific adjustment of the friction between tool and workpiece for a specifically designed material flow, which is called tailored friction, is of great importance. The reduction of friction is essential in order to ensure a homogeneous forming zone. However, a higher friction can be used to control the material flow to increase the local thickness of the work piece for additional functional integration. This paper shows the development of surface structures for SBMF tools by means of high-feed milling. Process parameters like the tilt angle or the feed are varied to influence the surface parameters of the structures, which results in different tribological properties of the forming tool. The structured surfaces are subsequently coated with a wear resistant CrAlN coating, processed by a magnetron-sputtering process (PVD) to enhance the lifetime and performance of the forming tool. Finally, a ring compressing test is used to investigate the tribological behavior of the coated structures.
Analysis of Tensile Test of Titanium EBW Sheet
Authors: Adamus Janina , Motyka Maciej
Published: March 2015

The continuous pursuit of vehicle weight reduction forces the industry to look for alternative materials to steel. Light alloys such as aluminium or titanium are materials that provide a decrease in weight using conventional technologies. Additional weight reduction results from using tailor-welded blanks (TWB). While the joining and forming steel or even aluminium TWBs is quite well known and described in the technical literature, joining and forming titanium TWBs still poses a significant problem. In the paper, experimental tests carried out with welded samples manufactured from commercially pure titanium Gr 2 and titanium alloy Gr 5 sheets are presented. The samples were joined by electron beam welding. Mechanical testing and optical microscopy were used to characterise the welds and the base metal of the samples. The samples were subjected to uniaxial tension up to final failure. The 3‑D Digital Image Correlation system ARAMIS was used for monitoring the whole deformation process. This makes it possible for real-time observation of sample deformation. The test results and the numerical analysis of the tensile tests are compared. The numerical simulations were carried out with the ADINA System based on the Finite Element Method (FEM). The mechanical analysis leads to calculation of the strain state after sample deformation in uniaxial tension (mechanical model).
Cold Formability of Automotive Sheet Metals: Anisotropy, Localization, Damage and Ductile Fracture
Authors: Lian Jun He , Ahn Deok Chan , Chae Dong Chul , Münstermann Sebastian , Bleck Wolfgang
Published: March 2015

Experimental and numerical investigations on the characterization and prediction of cold formability of two different types of automotive steel sheets, a ferritic stainless steel sheet (AISI 439) and a dual-phase steel sheet (DP600) are performed in this study. Due to the different microstructure configurations, these two steels show significant differences in plasticity behavior as well as failure mechanisms. The ferritic stainless steel shows strong anisotropic plastic deformation in terms of both yielding and hardening, whereas the dual-phase steel behaves quite isotropic resulting from the mixture of two phases. However, unlike the localization dominant failure mechanism of the ferritic stainless steel, the incompatible deformation due to the distinctions of the mechanical properties of two phases naturally results in early damage and extensive damage development prior to localization, or ductile fracture without localization. In this study, all these features are taken into account for an accurate prediction of formability. A general modelling framework with specifications for these separate features is formulated and applied to the two steels.
Validation of Kinematic Hardening Parameters from Different Stress States and Levels of Plastic Strain with the Use of the Cyclic Bending Test
Authors: Rosenschon Martin , Suttner Sebastian , Merklein Marion
Published: March 2015

The recent development of new lightweight sheet metal materials, like advanced high-strength steels or aluminium alloys, in combination with an increasing component complexity provides new challenges to the numerical material modelling in the FEM based process design. An auspicious approach to improve the quality of the numerical results – most notably in springback analysis – is the modelling of the so called Bauschinger effect achieved through implementation of kinematic hardening models. Within this paper the influence of the stress state and the level of pre-strain on the numerical simulation result of the advanced high strength steel DP-K45/78+Z will be analysed. For this purpose, a parameter identification of the kinematic hardening law according to Chaboche and Rousselier is performed at different pre-strains on the basis of experimental data from tension-compression tests as well as cyclic shear tests. Finally, the identified parameters are validated in a comparison between numerical and experimental results of a cyclic bending test.
Analysis and Optimization for the Production Process of an Automotive Alternator Using FEM and Experiments
Authors: D'Annibale Antonello , di Ilio Antoniomaria , Trozzi M. , Bonaventura L.
Published: March 2015

This paper presents the analysis and the optimization of the process parameters for an innovative and more efficient production system for claw pole alternators intended for automotive application. The authors, after a preliminary study about forces, material properties and geometrical specifics to achieve, set out a first set of parameters to realize an 8-pole rotor. After that, it was possible to layout each step of the forging process in a FE model and observe the geometrical properties of the final rotor. Once reached a good comprehension of the whole process by preliminary studies, experiments were conducted with the effective material currently employed to build the claw pole and other information were collected to refine the finite element model. By comparing the results between the FEM and experiments, it was possible to build a realistic model, which allowed adjusting the process in short time in order to make the final product meet all the required geometrical specifics and pass the electrical tests.
Experimental and Numerical Investigation on a Pressure Dependent Friction Model
Authors: Zöller Fabian , Sturm Vera , Merklein Marion
Published: March 2015

The objective of this paper is the investigation of the implemented pressure dependent friction model in the FE simulation program AutoForm. Since the values for the required parameters of this approach are not defined in the actual FE simulation program, this paper contributes to a first definition of these parameters. Therefore, experimental investigations with the cup drawing tests are carried out. With the support of the experimental results regarding the maximum stamping force, the model is calibrated and subsequently validated by the comparison of the sheet thicknesses of the experimental and numerical investigations. The results of this validation reveal a good accordance of simulation and reality in nearly all areas. However there are also areas in which the prediction accuracy decreases in comparison to the basic simulation. Therefore, additional investigations have to be carried out which concentrate on the modification of this pressure dependent approach towards a better universal prediction accuracy of the simulation.
Numerical Prediction of Failure within Small Curvature Bending of Advanced High Strength Steels
Authors: Tsoupis Ioannis , Merklein Marion
Published: March 2015

Within this paper a numerical study of the Continuum Damage Mechanics based damage model Lemaitre in commercial software LS-DYNA is performed in order to correctly predict failure in terms of crack occurrence within small curvature bending of AHSS steels. A strain based calibration method is used for the effective adaption of the Lemaitre model to the bending operation, which is based on the comparison and adaption of the numerically calculated and the experimentally measured deformation field on the outer surface of the bent specimen. Within this method the material dependent damage parameter S is systematically varied in the simulation in order to represent maximum major strain. The new method is proved by numerical simulation of experiments provoking crack initiation using smaller bending radii. It can be shown that failure in terms of crack initiation can be correctly predicted by the model with the damage parameters, which were determined by the method of strain based calibration and an additional optimisation of the parameter Dc. Thus, within this study a user friendly and effective way for the application of Lemaitre damage model to small curvature bending processes of AHSS steels is developed.
A Modified Shell Element Model Combined with Yld91 Yield Function in Simulating Aluminum Alloy Applied Hydroforming
Authors: Zhang Fei Fei , Chen Jun , Chen Jie Shi , Zhu Xin Hai , Yuan Shi Jian
Published: March 2015

Hydroforming has been used widely across many industrial fields. Large applied pressure during hydroforming makes it necessary to consider the influence of normal stress in the thickness direction, while in FE simulation, the use of traditional shell element based upon plane-stress assumption is not appropriate in such cases. Here, the traditional shell element is modified by changing the constitutive relation which took into account the normal stress in the thickness direction, and the modified shell element formula is combined with Yld91 yield function to simulate the forming process of Aluminium alloy. Then the element formulation and material model is implemented into the FE code Ls-Dyna by means of USER interface. Two examples are carried out and good correlations are obtained when compared to the traditional shell element and solid element.
Development of a Testing Method for the Identification of Friction Coefficients for Numerical Modeling of the Shear-Clinching Process
Authors: Müller Martin , Vierzigmann Ulrich , Hörhold Réjane , Meschut Gerson , Merklein Marion
Published: March 2015

Global competition as well as social and scientific megatrends strongly influence the modern car manufacturing industry. One of the most important approaches is the implementation of lightweight constructions. Therefore, the usage of high performance materials with tailored properties gains importance. For safety-relevant components such as automotive passenger cells it is necessary to minimize deformation to reduce the risk of injury for the vehicle occupants during a car accident. Thus, hot stamped high-strength steels have been established. High-strength and low formability of this kind of materials represent new challenges for joining technologies. One possibility to join high-strength steels is the newly developed shear-clinching technology. Due to the use of a combined cutting and joining process, the connection of dissimilar materials with high difference in strength and formability can be achieved. Further research to ensure process reliability and to improve the strength of the joint is required. One possible approach for this is the numerical investigation of the material flow during the joining process. Therefore, the definition of process parameters for the finite element model is necessary. A big impact on the quality of the results has the accuracy of the used friction values. As established testing methods are not suitable for modeling the rather complex tribological system between the joining partners of the shear-clinching process, an innovative testing method is needed. Studies in the field of sheet-bulk metal forming already demonstrated the applicability of the ring compression test for sheet metals. This paper presents a concept for the adaption of the ring compression test to the specific needs of the investigated shear-clinching process. The numerical identification of the friction coefficients is validated by experimental data and first results are qualified by experimental and simulative shear-clinching joints.
On the Solid Bonding Phenomena in Linear Friction Welding and Accumulative Roll Bonding Processes: Numerical Simulation Insights
Authors: Campanella Davide , Buffa Gianluca , Fratini Livan , Merklein Marion
Published: March 2015

Solid Bonding based welding processes allow to obtain defect free joints with low residual stress and low distortion. However, the engineering and optimization of solid bonding processes is difficult and requires a large number of time and cost consuming test trials. In this way, proper numerical models are essential tools permitting effective process design. The aim of this research was the comparison of the material process conditions during two different manufacturing processes taking advantage of the same metallurgical phenomenon, namely solid bonding. Linear Friction Welding, used to weld non-axisymmetric components and Accumulative Roll Bonding, used to increase the mechanical properties of sheet metals, were considered. Numerical models were set up, validated and used to design the process by studying the complex material behavior during the solid bonding of different aluminum alloys. An implicit approach was used for the Linear Friction Welding and Accumulative Roll Bonding processes, leading to the understanding of the main process variables influence on the field variables distribution and the occurrence of actual bonding.
Selection, Modeling and Prediction of Life of Stripper of Compound Die
Authors: Kashid Sachin , Kumar Shailendra , Hussein Hussein Mohamed
Published: March 2015

Compound dies are widely used for production of pierced blanks with high accuracy. Stripper is one of the major components of a compound die. In this paper, research work involved in the selection, modeling and prediction of life of stripper of compound die is presented. Knowledge based system (KBS) approach is used for selection of size of stripper. The knowledge base is constructed through coding of production rules of IF-THEN variety in AutoLISP language. Further, a CAD system is developed for automatic modeling of stripper of compound die. This CAD system works in conjunction with the KBS developed for selection of stripper. An artificial neural network (ANN) model is developed for prediction of life of stripper. Various factors affecting life of stripper are investigated through FEM analysis and the critical simulation values are determined. The proposed ANN model is trained by using FEM simulation results. The proposed work is tested successfully on different sheet metal parts taken from stamping industries. A sample run is also demonstrated in this paper.
Finite Element Analysis on Plastic Deformation Behaviors of Ti-3Al-2.5V Tubes under Axial Compression
Authors: Huang Tao , Zhan Mei , Tan Jin Qiang , Guo Jing , Yang He
Published: March 2015

With the requirement of aviation and aerospace fields for high-strength Ti-3Al-2.5V titanium alloy bent tubes with high-performance, it is great significance to research the plastic deformation of Ti-3Al-2.5V tubes under compression to obtain desired flow stress curves. A finite element (FE) model of axial compression of Ti-3Al-2.5V tubes was established in this study. Using this model, deformation behaviors of Φ12 mm × t0.9 mm Ti-3Al-2.5V tubes with different ratios of thickness to height (t/h) compressed under different frictions were analyzed. It is shown that the non-uniform deformation degree of the tubes increases with the decrease of t/h and the increase of friction coefficient. This means that a large t/h value and small friction can help to attain a uniaxial compression condition to obtain desired flow stress curves. Such compression conditions for the Φ12 mm × t0.9 mm Ti-3Al-2.5V tube is that, t/h is not less than 0.6 and the friction coefficient is not greater than 0.05
Numerical Study on the Comparison of Deformation Characteristics during the Fine Blanking Process of Spur Gears and Helical Gear
Authors: Xia Wen Ting , Mao Hua Jie , Hua Lin , Liu Yan Xiong
Published: March 2015

As important transmission components, helical gears have been widely applied to mechanical and automotive fields. The traditional manufacturing process for helical gears is machining, which is time-consuming and result in the high cost of gears. In order to improve the production efficiency and product quality of helical gears, a novel forming process principle for the fine blanking of helical gears was developed. In this study, reliable three-dimensional (3D) rigid-plastic finite element (FE) models of single tooth and complete gears were set up and investigated using the software Deform-3D, the deformation characteristics of fine blanking of spur gears and helical gears were compared. Based on the valid numerical models, variation tendency of different field variables such as damage material flow velocity, and mean stress were obtained, as well as the feature of the tooth section, which provides a better understanding of the deformation mechanism of rotational fine blanking process.
Internal Flow-Turning - An Innovative Technology for the Manufacture of Tailored Tubes
Authors: Homberg Werner , Rostek Tim , Wiens Eugen
Published: March 2015

In order to optimise the material utilisation and improve the lightweight design of automotive parts tailored hollow profiles are needed, especially as semi-finished parts for hydroforming. Internal Flow-Turning is an innovative incremental forming technology which enables the manufacture of tubes featuring a varying wall thickness and a constant outer diameter. These characteristics facilitate the material feed at hydroforming processes significantly. In addition, the spinning-related forming technology improves the mechanical material properties, shape and dimensional accuracy, and the surface quality of parts produced.
Laser Forming of Steel Dome-Shaped Parts Using a Flower Pattern
Authors: Loh-Mousavi Mohsen , Rostami Mehrdad , Farzin Mahmoud
Published: March 2015

In recent years, laser forming of round plates into bowl or dome shapes by use of circular, radial and circular-radial patterns have been investigated. Usually formed circular plates using circular or linear patterns are distorted as asymmetric saddle shapes. In this study, a new flower pattern has been proposed to form round plates by laser. To make this pattern, the laser beam scans several petal paths on a circular blank. Laser forming of round plates by the proposed pattern have been studied by three dimensional finite element method. The results have been compared for the flower pattern and other conventional circular and radial pattern. In addition experiments have been conducted to verify the numerical results. The results show that the deformed parts by the petal path are more symmetrical in comparison with circular and radial patterns. It was found that in laser forming of dome-shaped parts, scanning by petal paths prevent distortion and increase the geometrical symmetry of deformed parts by laser. It was shown that laser radiation on petal paths improves the deformation process of laser forming of circular steel sheets.
Fluoride Adsorption Properties of CeO2 Powders and Al Foam Loaded CeO2
Authors: Chen Jian Qing , Yang Dong Hui , Wei Yong , Jiang Jing Hua , Ma Ai Bin , Song Dan
Published: March 2015

Cerium oxide powder and aluminum foam loaded cerium oxide were prepared by hydrothermal method using cerium nitrate hexahydrate and dimethyl oxalate (DMO) as raw material. Cerium oxide precursors and cerium oxide particles were characterized by field emission scanning electron microscopy (FESEM). Aluminum foam loaded cerium oxide was characterized by environment scanning electron microscopy (ESEM). On the basis of calculation and fitting of the experimental data, effect of the particle size on the adsorption rate, desorption rate and concentration of surface active sites of the powder and composite absorbents were studied. Results show that the removal of fluoride ions can be realized by exchange adsorption of oxhydryl on the cerium oxide particles surface and the fluoride ions in the solution.
Enhanced Photocatalytic Properties of Ag-Modified Mg-Doped ZnO Nanocrystals Hybridized with Reduced Graphene Oxide Sheets
Authors: Wang Lin Qin , Wu Yan , Yang Xiang
Published: March 2015

Heterojunction semiconductor composites could enhance the photoelectric conversion efficiency of photocatalysts. We successfully in-situ synthesized the hybrids of Mg-doped ZnO and reduced graphene oxide (MZO/RGO) by one-pot wet chemical method. Ag nanocrystals are loaded onto the MZO/RGO composites by photochemical reduction method. Crystallization of MZO/RGO-Ag upon thermal decomposition of the stearate precursors was investigated by X-ray diffraction technique. XRD studies point toward the particles size with 15-20 nm, which was confirmed by scanning electron microscope and energy dispersive X-ray spectroscopy, and also indicates that Ag nanoparticles were deposited on the surface of nanocomposites. The photocatalytic performance of ZnO nanomaterial was significantly improved by Mg-doping, RGO sheets corporation and Ag hybridization. It was found that the RGO sheets take the role of improving the charge separation during the photocatalytic activity, and the presence of Ag nanocrystals enhances the quick discharge of photoinduced electrons under the UV light. Therefore, the MZO/RGO-Ag nanohybrids are excellent candidates for the applications of environmental issues.
Preparation and Photocatalytic Property of Dendritic TiO2/VOx Nanofibers
Authors: Teng Le Tian , Zhao Kang , Tang Yu Fei , Chen Xi
Published: March 2015

TiO2/VOxnanofibers were synthesized via electrospinning and dipping technologies. They increased the photocatalytic property by reducing the recombination rate of electrons and holes at the surface of TiO2. The composition, structure and morphology were characterized. The effect of annealing temperature to the dendritic structure and their photocatalytic property were demonstrated. The results showed dendritic TiO2/VOxnanofiers were obtained via dipping in vanadium sol, which was annealed at 550°C in 90% Ar/10% H2atmosphere. The average diameter of the samples was 354±42nm. Both the size and the number of dendritic structure were increased as the annealing temperature was rising. The degradation rate of methyl orange (5mg/L) by as-prepared TiO2/VOxnanofibers was 76.4% after exposure under UV light for 120min, which was 25.7% higher than which annealed in air atmosphere.
Effect of Sputtering Power on Photocatalytic Activity of Thin TiO2 Films
Authors: Luo Zhi Hong , Leng Jin Feng , He Wen Shuang , Hu De Jiang
Published: March 2015

TiO2 thin films with outstanding photocatalysis can potentially be used for photocatalysis device in the field of environmental protection. TiO2 thin film (99.99%) was fabricated successfully by power metallurgy. The effect of sputtering power on TiO2 thin films by radio frequency magnetron sputtering was investigated. The results show that the higher sputtering power is beneficial for the growth of Rutile structure with superior photocatalysis. With the increasing of sputtering power, the rate of methyl orange degradation increases under UV light irradiation. The degradation rate of TiO2 thin film under sputtering power 75W and 165W is 40% and 80% respectively. This is attributed to the increase of the rutile phase with many defects and dislocation network under higher sputtering power.
Preparation of Al2O3 from the Nepheline Ore of Nanjiang County, Sichuan Province of China
Authors: Qiu Yu Chong , Qiu Ke Hui , Li Jun Han , Zhang Pei Cong
Published: March 2015

Crystalline alumina samples with Al2O3 content of 95.23 wt.% were prepared directly from the nepheline ore in Nanjiang county, Sichuan province of China. Four steps were involved in the experiment of alumina preparation, including calcination, dissolution, carbonation and re-calcination. Lime was used in the calcination process with the nepheline concentrates powders to generate soluble aluminates and insoluble silicates. NaOH solution was used as the mother solution in the dissolution process. CO2 was introduced into the solution to precipitate the Al (OH)3 precursor, which was then fired to obtain crystalline alumina. Among the crystalline alumina obtained three phases of crystals existed which were detected by XRD and SEM, including δ-Al2O3 as the major phase, while θ-Al2O3 and κ-Al2O3 as the minor phases. Various crystal phases of alumina could be ascribed to the purity and crystal structure of precursor, as well as the re-calcination temperature and time.
Biomass Reduction Roasting-Magnetic Separation of Low Grade Goethite
Authors: Wang Qiu Yue , Wu Yan , Li Yong Huo , Yang Xiang
Published: March 2015

The average grade of iron ores in China is around 32%, about 10% lower than the world’s average level. In order to alleviate the demand of iron ore for steelmaking industries, it is urgent to develop a highly efficient, energy-saving, low-carbon and environment-friendly technology. The goethite ore from Northern Hainan Island was studied via reduction magnetization by pine, rice chaff, and corn straw biomass fuels. The magnetic properties and magnetic separation were discussed by optimizing the parameters of roasting temperature, roasting time, and the ratio of biomass fuels. The results show that we could obtain concentrated iron ore grade of pine roasting and magnetic separation grade of iron concentrate 61.64% with the recovery of 79.75% via pine fuel roasting, 61.75% with the recovery 80.16% via rice chaff, and 61.47% with the recovery of 81.28% via corn straw roasting. Thereby, we could deduce that biomass fuels for reduction roasting of low goethite ore is promising to substitute the traditional coal and coke fossil fuels.
Synthesis and Properties of the Poly(methyl methacrylate-acrylamide)
Authors: Wu Yuan Peng , Zhu Chun Yang , Lin Yuan Hua , Yan Zhu , Yang Hao , Zhou Chang Liang , Singh Ambrish
Published: March 2015

The hole in the shale formation is in nanometer or micrometer scale, so the conventional plugging materials which are in the scale of millimeter cannot be used during the drilling of the shale formation. An effective way to solve this problem is to develop new plugging materials, which are in the nanometer or micrometer scale. In this article, the micron copolymer particles were prepared by the soap-free emulsion polymerization of the monomers methyl methacrylate (MMA) and acrylamide (AM). The structure of the copolymer particles was characterized by the Fourier transform infrared spectroscope (FT-IR). The particle size was determined by dynamic light scattering (DLS). In addition, the salt tolerance, temperature resistance and compatible property of the particles with the additives of drilling fluids were studied in detail.
Effect of Heat Treatment on Corrosion Resistance of 0Cr18Ni9Ti Stainless Steels
Authors: Li Hua Wei , Guan Deng Gao , Xu Guan Li , Sun Yao , Tang Feng , Chen Ting , Yan Han , Xu You , Sun Chuan Min
Published: March 2015

0Cr18Ni9Ti stainless steels are used extremely broad, but the corrosion phenomena of 0Cr18Ni9Ti stainless steels will happen in its using because of various reasons. 0Cr18Ni9Ti stainless steels were taken with different process of heat treatment in order to change its corrosion resistance in this paper. The corrosion resistance performance of the samples was discussed by metallographic picture observation, weight-loss method and organizational analysis. The better heat treatment process was chosen, according to the contrast experiment method. The results indicate that the sample has the best corrosion resistance after 1040°C×1.5h solid solution and stabilization treatment of 890°C×2h. This study has certain positive meaning to improve the 0Cr18Ni9Ti stainless steel corrosion resistance.
Preparation and Characterization of Microporous Activated Carbon from Raw Petroleum Cokes
Authors: Wang Bo Tao
Published: March 2015

Adopting the chemical activation method, the high specific surface area activated carbon (AC) was prepared by the solid mixing method using Daqing petroleum cokes as raw materials and KOH as activator. The influence of the ratio of KOH to carbon, activation temperature and activation time on the iodine and methylene blue adsorption properties of the AC were studied. The micro-graphitic structure of the AC was studied by X-ray diffraction (XRD). The BET specific surface area, BJH pore size distribution and pore volume of the AC were determined by N2 adsorption (at 77K). The experimental results show that the high specific surface area AC can be prepared with the ratio of KOH to carbon of 4, activation temperature of 800°C and activation time of 1h. The specific surface area was as high as 2142 m2/g with the iodine adsorption value of 288mg/g and methylene blue adsorption value of 1266mg/g. The XRD and BJH results also show that amorphous carbon was the dominating form, and the pore size distribution represents micropore structure.
Recent Advances in Graphene Preparation Methods
Authors: Zhou Chao , Chen Si Hao , Lou Jian Zhong , Chen Zhi Chang , Xu Gang , Yang Chun Yu
Published: March 2015

Graphene, a single layer of sp2-bonded carbon atoms arranged in a honeycomb lattice, has attracted a plethora of attention because of its remarkable physical, mechanical, electronic and optical properties. This paper reviews recent advances in the preparation methods of graphene. Recently, graphene materials research has reached an unprecedented event, and the graphene preparation method also is endless. A lot of papers have been reported, but not an exhaustive list of various preparation methods and its principles. In this article, based on the previous preparations of graphene, comprehensive fabrication methods were summarized, and then, put forward a new vision and perspectives.
Application of Ultrafine Weighting Materials in High-Density Oil-Based Drilling Fluid Technology
Authors: Ye Yan , An Wen Hua , Yin Da , Zhang Qing Wen , Li Lei , Ren Ling Ling
Published: March 2015

High-density oil-based drilling fluid already was considered as one of the most effective technologies during the HTHP Ultra-deep well drilling process. The weighting materials sag such as barite sag, however, always occurred because of the density contrast between the base oil and the weighting material, and hence sag can result in excessive torque, lost circulation and many other problems. This study applied three kinds of ultra-fine powder (particle size≤4μm), which are new weighting materials, to replace the common API barite (particle size10~70μm). The different kinds of high-density oil-based drilling fluids, which weighted with micronized barite, micronized ilmenite, manganese tetraoxide and API barite, were prepared and evaluated separately in lab. The performance data showed that compared with conventional weighting materials, the application of ultrafine powder technology could greatly optimize the rheology of high-density oil-based drilling fluids (ρ ≥ 2.3 g/cm3), reduce the amount of emulsifiers about 50% and dramatically enhance the dynamic suspension-stability of the system, Furthermore, OBM drilling fluids weighted with ultrafine weighting materials almost presented lower viscosity, shear force and sedimentation rate, which will meet more severe requirements of ultra-deep complex well drilling.
Preparation and Optical Property of ZnS:Mn/XO2 (X=Ti, Si) Nanoparticles with Core/Shell Structure
Authors: Wang Yu Long , Zhang Wen Tao , Long Jian Ping , Zhang Pei Cong
Published: March 2015

In this paper, Mn2+ doped ZnS (ZnS:Mn) nanoparticles were prepared by co-precipitation method. And then different thickness of TiO2 and SiO2 inorganic shell were coated on prepared ZnS:Mn through the hydrolysis reaction of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS). ZnS:Mn crystal and core/shell structure were described by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical property of all ZnS:Mn/XO2 (X=Ti, Si) nanoparticles were investigated by photoluminescence (PL) spectrometer. The effect of Mn2+ concentration and XO2 (X=Ti, Si) shell thickness on luminescence intensity of ZnS:Mn/XO2 was studied. The results showed that with TiO2 and SiO2 shell thickening, Mn2+ emission of ZnS:Mn/XO2 samples increased first and then decreased. When the thickness of inorganic shell (molar ratio of shell and core amount) reached to 0.5 (TiO2) and 1.0 (SiO2), the optimal luminescence intensity was obtained. The emission of ZnS:Mn/TiO2 and ZnS:Mn/SiO2 was 2.0 and 1.5 times more in intensity than that of uncoated ZnS: Mn, respectively.
Combustion Synthesis and Luminescence Properties of Li2Ca1-x-ySiO4: xEu3+, ySm3+ Phosphors
Authors: Zhao Ce , Qiu Ke Hui , He Xia , Yan Guo Yin , Chen Si Zhu
Published: March 2015

A series of red-emitting phosphors, Eu3+-doped and Eu3+ with Sm3+ co-doped Li2CaSiO4, were prepared by the combustion method. The phase composition was investigated by XRD, and photoluminescent properties were characterized by fluorescent spectrophotometer. The results show that the diffraction peaks of samples all match well with that of Li2CaSiO4 [JCPDS NO. 27-0290]. The excitation spectra consists of the broadband and the sharp lines, which are assigned to the charge transfer band (CTB) of Eu3+→O2– and the typical intra-4f transitions of the Eu3+ ions, respectively. The emission spectrum covers the characteristic f-f transitions of Eu3+, namely, 5D0→7F1 (596 nm), 5D0→7F2 (620 nm), 5D0→7F3 (657 nm) and 5D0→7F4 (705 nm). The concentration quenching occurs when Eu3+ mol fraction equals to 9%. When Eu3+and Sm3+ were co-doped, the luminous intensity of the emission spectrum was superior to the Eu3+ mono-doped, which explains the Sm3+ has a sensitization effect for Eu3+.
Corrosion Behavior of P-Coated Biomedical Pure Magnesium
Authors: Zhou Shi Jie , Li Jun Feng , Long Jian Ping , Du Han Qiu
Published: March 2015

Magnesium and its alloys are potential materials in biodegradable hard tissue implants. However, the fast degradation rates in a physiological environment constitute the main limitation for biomedical application. In this work, the NH4H2PO4- KMnO4chemical conversion treatment on the surface was used. The morphology and structure of the coating was observed and analyzed by SEM. The electrochemical behavior in Hanks' simulated body fluid of the coated magnesium was systematically investigated. Our results disclose that the corrosion resistance of the P-coated magnesium is significantly improved.
Analysis on the Global Warming Potential of Cement Concrete Pavement in China
Authors: Zhao Li Li , Wang Zhi Hong , Liu Yu , Gong Xian Zheng , Gao Feng , Cui Jia Ping , Jiang Quan , Ma Li Ping
Published: March 2015

The global warming of cement concrete pavement from raw material extraction to road construction was analyzed by the method of life cycle assessment. The characterization results showed that the procedure of producing material is the most important stage to emit greenhouse gas and it accounts for 98.5% of the global warming potential that caused by the material production and construction stage. For the materials used in different structure layers, surface layer is the biggest impact of greenhouse and accounts for 68.9% of the total impact caused by material used in constructing pavement. Therefore in the future, by using recycled materials or more environmental materials will be a good way to reduce environment impact.
Life Cycle Assessment of Cement Clinker Production Using Coal Gangue as Alternative Raw Material and Fuel
Authors: Cui Jia Ping , Liu Yu , Wang Zhi Hong , Gong Xian Zheng , Gao Feng , Zhao Li Li , Hao Li Wei
Published: March 2015

Life cycle assessment (LCA) was carried out to quantify and analyze the environmental impact and benefit caused by the utilization of coal gangue as alternative raw material and fuel in cement clinker production. The optimal dosage of coal gangue was determined by comparing among different mixing amount scenarios and Portland cement clinker (clinker without adding any waste) considering the phases of coal gangue disposal, transportation, and raw meal grinding and clinker calcination. The results showed that: 1) After adding coal gangue to the raw meal, almost all the considered environmental impacts of cement clinker including human toxicity potential, photochemical smog potential, especially abiotic depletion potential decreased significantly. However, global warming potential and acidification potential increased slightly in comparison with Portland cement clinker. 2) Compared with the Portland cement clinker, the single environmental indicator reduced after adding coal gangue and the indicator decreased gradually with the dosage increasing.
Research on Life Cycle Energy Consumption and Environmental Emissions of Light-Duty Battery Electric Vehicles
Authors: Shen Wan Xia , Zhang Bo , Zhang Yu Feng , Wang Xue Chao , Lu Qiang , Wang Cheng
Published: March 2015

Based on producing and manufacturing process of key components, a light-duty battery electric passenger vehicle was selected as a research object, and the energy consumption and environmental emissions from raw materials production, electric vehicle manufacture and operation process in depth were analyzed. The results showed that, the energy consumption for the whole life cycle of EV was 438GJ. The production and operation process of EV accounted for 18.5% and 81.5%, respectively. The GHGs (including CO2, CH4and N2O) emission was 39.3tCO2-eq. The production and operation processed of EV account for 17% and 83%, respectively. Five kinds of other gases emissions from the production and operation process of EV were as follows: 305kg SOx, 206kg NOx, 133kg PM, 69.3kg CO, and 14.6kg NMVOCs. The production and manufacture of key parts and components account for the largest share of the total energy consumption and environmental emissions. Battery system is in the next place, while motor system is least.
Preparation of Fly Ash/CeO2 Composite and its Adsorption Kinetics for Congo Red Dye from Aqueous Solution
Authors: Li Bei Gang , Ding Lei
Published: March 2015

Fly ash/CeO2 composite (FA/CeO2) was prepared by acid modification and precipitation method using a low-cost waste fly ash (FA) as a raw material and characterized by X-ray diffraction (XRD) and the BET surface analysis. The adsorption of FA and FA/CeO2 for Congo Red (CR) from simulated dye wastewater was studied. The different regeneration methods for the CR-saturated FA/CeO2 were investigated. The results show that the adsorption capacity and removal rate of CR on FA/CeO2 can respectively reach 175.35mg/g and 97.42%, 4.5 times higher than those on FA. The adsorption process of FA/CeO2 for CR at different temperatures (25°C~55°C) can well be described by the pseudo-second-order adsorption model and is mainly controlled by intraparticle diffusion. The adsorption rate decreased slightly with increasing temperature, and the obtained adsorption apparent activation energy is 15.08kJ/mol. This indicates that CR is easily adsorbed on FA/CeO2, and the adsorption of the process is mainly physical adsorption with exothermic nature. The room temperature is favorable to the adsorption and actual operation. NaOH solution of 0.01 mol/L can make CR-saturated FA/CeO2 regenerated three times, and corresponding removal rate for CR can reach 97.82%, 80.21% and 66.04%, respectively. As a new kind of low-cost and high-efficient adsorbent, FA/CeO2 composite has the potential value in the application of wastewater treatment.
Lithiation/ Delithiation Process of Silicon-Carbon Composites Prepared by Mechanical Alloying
Authors: Ang Ya Feng , Ren Xin Yi , Dou Zhen Bo , Jiang Xun Yong
Published: March 2015

In this study, graphite doped silicon was prepared by mechanical alloying (MA). MA is an effective method to manufacture silicon-carbon composite. The results show that the capacity retention ability of the graphite doped silicon by MA anode is better than silicon. The fellow result shows that LiaCb appears at the middle of lithiation process and disappear with the production of LixSiy, LixSiy produce and disappears at the end of lithiation process and beginning of delithiation process respectively. The SEI film enhanced with the increasing amount of lithium and silicon-carbon composite material was severely decomposed with the cycles increase.
Energy Saving Property of Heat-Reflective Coatings on Temporary Buildings
Authors: Lv Qiu Rui , Mao Qian Jin , Wang Ya Li , Wang Zi Ming , Cui Su Ping
Published: March 2015

The energy saving of temporary buildings used heat-reflective coatings in cold region has been paid growing attention. Surface temperature and energy consumption were calculated by the temporary office building and factory building in Beijing. The buildings are color steel plate structure in this paper. The roofs and exterior walls of buildings were painted with heat-reflective coatings. The general solar reflectivity of roofs and exterior walls were about 26% and 22%; after the application of heat-reflective coatings the reflectivity increased to about 84% and 72%. Results demonstrated that the roofs have the best cooling effect, with the average surface cooling reaching 23.32°C in summer. The estimated energy savings of roof was about 9.95Wh/m2 per day and the energy consumption reducing rate was up to 67.7% in summer. Considering the energy consumption increased in winter, heat-reflective coatings were only strongly advised to paint on roofs in cold region.
Evaluation and Selection Research on External Wall Insulation Materials Based on Green Building Energy Conservation
Authors: Ma Li Ping , Wang Ying , Jiang Quan , Zhao Chun Zhi , Zhao Ping
Published: March 2015

Mateial selection technology for green building is an important support of green building development. Aiming at the realization of green building energy conservation, the green building material selection evaluation model was proposed integrating double elements - energy contained in a unit product of building material and energy saveing brought to the building operation in the service process of building material. Taking three categories of thermal insulation materials - polyphenyl board, rock wool board and polyurethane rigid foam board as examples, the relative relationship was calculated and analyzed between energy contained in a unit product of three categories of thermal insulation materials and energy saving in building operation brought by them respectively, and finally a conclusion draws from that: based on building energy conservation, polyphenyl board is a suitable product to realize green building material selection.
SiC/Cu Composite Prepared by Spontaneous Infiltration of Copper Alloy into Porous SiC Ceramic
Authors: Zhang Kuo , Shi Zhong Qi , Liu Gui Wu , Qiao Guan Jun
Published: March 2015

A porous SiC ceramic reinforced copper-matrix composite was fabricated by spontaneous infiltration of molten Cu-24at%Si alloy into the reinforcement. The influence of process parameters on the infiltration behavior and microstructure of the as-prepared SiC/Cu composite investigations showed that infiltration temperature had an important influence on the infiltration behavior, and higher infiltration temperature which decreased the viscosity of molten Cu-24Si was beneficial to the penetration. Besides, the degree of infiltration increased with the increase of dwelling time at 1600°C. SiC particles were bonded together by sintering additives to form the porous reinforcement, which can be maintained after spontaneous infiltration. The interfacial bond between SiC and Cu-24Si alloy was tight, and no obvious interfacial reaction layer was observed in the as-prepared composite.
Preparation of Silicon Carbide Reticulated Porous Ceramics by Organic Foam Impregnation
Authors: Zhang Xiang Zhao , Wang Ren Juan , Liu Gui Wu , Shao Hai Cheng , Zhang Kuo , Shi Zhong Qi , Qiao Guan Jun
Published: March 2015

Silicon carbide (SiC) reticulated porous ceramics were prepared by organic foam impregnation, using polyurethane sponges as template and deionized water or alcohol as slurry solvent. The sintering behavior, microstructures and apparent density of struct of the SiC reticulated porous ceramics fabricated using the aqueous slurry under different sintering aids and sintering process and the alcohol slurry were investigated comparatively. The experimental results showed that both the microstructures and apparent density of the samples fabricated by Y2O3+AlN as sintering aid were better than those Al2O3 as sintering aid while the aqueous slurry, and the samples fabricated by two-step process (firstly heated to 700 oC in air furnace, and then sintered at 1800 oC in Ar atmosphere) while Y2O3+AlN as sintering aid obtained the optimal properties. In particular, the samples fabricated by the alcohol slurry and reaction sintering process were provided better properties than the aqueous slurry.
Influence of Fineness on Activity Index of Blast Furnace Slag with Different SiO2/Al2O3
Authors: Cui Su Ping , Liu Ling Ling , Wang Ya Li , Wang Hui , Dong Shi Jie
Published: March 2015

Granulated blast furnace slag (GBFS) is a by-product of ironmaking and widely used in the cement and concrete. GBFS samples with different ratio of SiO2/Al2O3 were prepared under the laboratory conditions and ground by the agate ball mill at different times. Then they were characterized by laser particle size analysis (LPSA), scanning electron microscopy (SEM), Bertrand surface method and mechanical testing. It was found that the activity index of GBFS clearly increased with the decrease of the GBFS particle size. In the case of the average particle size about 32μm, the activity indices were irregular with the increase of SiO2/Al2O3 ratio, whereas for the average particle size about 11μm, the activity indices decreased with the increase of SiO2/Al2O3 ratio.
Utilization of Serpentine Resources in China
Authors: Dong Fa Qin , Zhou Qing , Peng Tong Jiang
Published: March 2015

As a new type of non-metallic mineral resource, serpentine has attracted more and more attentions. Serpentine mineral resources are abundant in China, with more than 5 billion tons reserves proved. However, most of them have not been used adequately except for some special serpentine, such as serpentine jade and chrysotile. The overview for status quo of serpentine utilization consists of the distribution, chemical compositions, crystal structure of serpentine, mature but not economic applications and some development of high-value utilization research. It is expected to provide some references for deeper research and promoting its applications.