bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Stitching Density of Nonwoven Fiber Mat towards Mechanical Properties of Kenaf Reinforced Epoxy Composites Produced by Resin Transfer Moulding (RTM)
Authors: Salim Muhamad Saifuddin , Mohd Ishak Zainal Arifin , Abdul Hamid Suhail
Published: February 2011

This study will focus on the usage of kenaf as a natural fibre in producing a composite materials consists of epoxy resin by resin transfer moulding (RTM). The variation amount of fiber loading and nonwoven fibre mat condition seems can give significant changes in properties of polymer composite in terms of mechanical aspects. Optimization of stitching density of nonwoven kenaf fibre mat manages to increase the mechanical behaviour. At higher degree of fibre loading, these enhancement properties are more apparent. Depending upon the direction of stitching process in producing nonwoven kenaf fiber mat, the composite obtained exhibit anisotropy behaviour in which the mechanical properties are vary upon the stitching direction of nonwoven mat.
Nanocomposite PVD Coatings Applied to Cold Plastic Forming Tools
Authors: Borowski Jacek , Rybak Tomasz , Ignatiev Mikhail , Wiśniewska-Weinert Hanna , Dobrovnik Igor , Leshchynsky Volf
Published: February 2011

Cold forging tools most often fail as a result of wearing down surface layer which works with forming part. Deposition of a hard coating on the working surface is widely applied to increase tool durability. In this respect technologies of production of top layers with the use of nanocomposite materials provide great opportunities of modification of tribological properties. This paper presents results of metallographic, SEM and HRTEM analysis of PVD nanocomposite coatings [1] (nACVIc, TiCN-CBC and TiCN-NP-MOVIC). The tribological tests with ball on disc (T10) tester and industrial tests of forging tool durability were made. The multilayer nACVIc coating is composed of thin layers with the thickness of approximately 2nm as structured alternately by Al and Ti,N,Si atoms, that is different from TiCN-CBC coating with column structure. A modification of the structure results in change of tribological behavior. The nACVIc nanocomposite coating is characterized by significantly less value of the friction coefficient (0.2) as compared to TiCN-CBC coating (0.7) under the same test conditions.
Iron Phases in Model Al-Mg-Si-Cu Alloys
Authors: Lech-Grega Marzena , Boczkal Sonia
Published: February 2011

Iron phases present in alloys from the 6xxx series affect the workability behaviour of these alloys. Iron in these alloys occurs in the form of intermetallic phases and AlFe, α-AlFeSi, β- AlFeSi eutectics. The homogenisation treatment is carried out to induce the transformation of  phase into phase The aim of the studies was EDX and EBSD analysis by scanning microscopy of iron phases present in model alloys based on 6061 system, characterised by the silicon-iron ratio Si/Fe=0,5 and 1, examined in as-cast condition and after homogenisation, followed by a comparison of the detected phases with phases present in industrial ingots. In 6061 alloy, copper in the amount of 0,4wt.% occurred in the solid solution of aluminium. The EDX analysis proved that copper atoms were embedded also in iron precipitates, and scarce phases of an AlxCuy type were being formed. Different content of magnesium in the examined alloys (0,8 and 1,2wt.%) affected not only the quantitative content of Mg2Si phases, but also the presence of AlFe phases in alloy with small content of Si (0,4wt.%) and high content of Mg (1,2wt.%).
Incremental Equal Channel Angular Pressing for Grain Refinement
Authors: Rosochowski Andrzej , Olejnik Lech
Published: February 2011

Creating a small amount of ultrafine grained metals by severe plastic deformation, for example using equal channel angular pressing, is possible in many research laboratories. However, industrial production of these materials is lagging behind because of the lack of industrially viable severe plastic deformation processes. One attempt to change this situation is based on the concept of incremental equal channel angular pressing developed by the University of Strathclyde and Warsaw University of Technology. The paper describes the path the researchers took to develop the process starting from finite element simulation, through tool design and process implementation, to material characterisation. Examples of various process configurations, which enable obtaining UFG bars, plates and sheets are given and possible future developments discussed.
Mechanical Properties of Cast Shape Memory Alloy for Brain Spatula
Authors: Tobushi Hisaaki , Kitamura K. , Yoshimi Yukiharu , Miyamoto K. , Mitsui K.
Published: February 2011

In order to develop a brain spatula or a brain retractor made of a shape memory alloy (SMA), the bending characteristics of the brain spatula of TiNi SMA made by the precision casting were discussed based on the tensile deformation properties of the existing copper and the TiNi rolled-SMA. The fatigue properties of both materials were also investigated by the plane-bending fatigue test. The results obtained can be summarized as follows. (1) The modulus of elasticity and the yield stress for the cast and rolled SMAs are lower than those for the copper. Therefore, the conventional rolled-SMA spatula and the new cast-SMA spatula can be bent easily compared to the existing copper-brain spatula. (2) With respect to the alternating- and pulsating-plane bending fatigue, the fatigue life of both the copper and the SMAs in the region of low-cycle fatigue is expressed by a power function of the maximum bending strain. The fatigue life of the conventional rolled SMA and the new cast SMA is longer than that of the existing copper. The fatigue life of the new cast and rolled SMAs in the pulsating-plane bending is longer than that in the alternating-plane bending. (3) The fatigue life of the rolled-SMA and the cast SMA for alternating- and pulsating-plane bendings can be expressed by the unified relationship with a power function of the dissipated work.
Processing of Materials by Electric Discharge Assisted Mechanical Milling
Authors: Calka Andrzej , Wexler David
Published: February 2011

Advanced materials manufacturing methods require clean, non-polluting, high speed and precise processes, and should result in highly reliable final products. However, traditionally, many functional materials are synthesized by slow reaction techniques that are both energy and time consuming. In such cases there is strong demand for more appropriate materials processing methods that could offer increased rapid reaction rates and energy efficiencies, and be environmentally safe. Electric discharge assisted mechanical milling (EDAMM) is a new and exciting materials processing technique which combines the attributes of conventional mechanical and mechanochemical milling with the several additional processing effects which can be generated by the simultaneous application of electric discharges. It is shown that EDAMM can be applied to synthesize a range of functional materials in a matter of minutes, rather than the hours or days required using traditional techniques. This presentation provides an overview of recent developments in the EDAMM method and its application to rapid materials processing, and the synthesis of certain functional materials. In this report, we demonstrate the versatility of EDAMM by; (i) synthesis of hard materials, (ii) synthesis of functional oxides used in electronic, magnetic and optical applications, (iii) rapid reduction reactions including extraction of metals from oxides and sulfides and (iv) synthesis of fine metallic and nonmetallic powders and (v) formation of nano- fragments, including carbon nanoribbons and iron oxide nanorods.
Structure Refinement Induced by Deformation Twinning in 77K Tensile Cu-8%at.Al Single Crystals
Authors: Perek-Nowak Małgorzata , Szczerba Marek S.
Published: February 2011

In the paper the concept of structure refinement due to mechanical twinning is discussed. It is postulated that the process of structure refinement may occur when dominant crystal shear proceeds across twin-matrix interface (Mode 2). Contrary, if the crystal shear proceeds parallel to the interface (Mode 1) no condition for structure refinement is satisfied. The conditions of the structure refinement and no structure refinement are shown taking example of tensile Cu-8%at. Al single crystals of two orientations [1 4 5] and [1 1 2] tested in liquid nitrogen. The tensile characteristics are therefore divided into stages associated with the Mode 1 and Mode 2, which correspond to the fact whether refinement of single crystal structure is present or not, as it is proved by the EBSD analysis. The performed analysis showed that structure refinement consists of formation of regions of new orientations, where the most common feature is the II order twinning (the case [1 4 5]) supported by other regions of specific orientations necessary to accommodate mainly the transfer of crystal twin shear across the twin-matrix interface. Moreover, if the II order twinning plays the dominating function (the case [1 1 2]) higher order twins are to bring into operation to assure further ductility of a deformed sample.
Thermo-Chemical Process of Aluminizing of the Nickel-Base Superalloy
Authors: Poręba Marek , Ziaja Waldemar , Sieniawski Jan
Published: February 2011

The thermo-chemical treatment routes for Renè77 superalloy were developed comprising low activity and high activity aluminizing by CVD method. The influence of the treatment on the oxidation resistance in air and creep resistance of the alloy was examined. The cyclic oxidation tests at 1100°C for 500 cycles were carried out. Creep tests were performed at 982°C at the stress level of 124 and 151.7MPa. The chemical and phase composition of the surface layer was analyzed after aluminizing. It was found that aluminide coating enhanced oxidation resistance of the Renè77 superalloy without deterioration of its mechanical properties.
Thermal Stability of Microstructure of Aluminide Layer Deposited by CVD Method on CMSX 4 Nickel Base Superalloy
Authors: Yavorska M. , Sieniawski Jan
Published: February 2011

In the paper the aluminide layer was deposited by CVD method on the CMSX 4 single crystal nickel base alloy. The aluminizing process was carried out at the 1050 °C during 8 h. The chemical vapor deposition process was performed by means of AlCl3 aluminum chloride. The effects of aluminizing were verified in microscopic examination (microstructure and depth layer) and chemical composition on the surface and cross-section of aluminide layer. The oxidation resistance in the air atmosphere at the 1100 °C during 1000 h was a criterion of efficiency of CVD process. The hardness distribution on the cross-section aluminide layer before and after oxidation test was investigated. The parabolic mass change was observed during oxidation. Under oxidation test during 120 h on the grain size of NiAl phase was observed the phase transformation β NiAl →Ni3Al. The increase of oxidation time causes decreasing of substrate hardness and stabilization of Topologically Closed Packed phases.
Variation Mechanism of Aspiration Pressure at the Tip of Metal Delivery Tube in Supersonic Atomization
Authors: Zhao Xin Ming , Xu Jun , Zhu Xue Xin , Zhang Shao Ming
Published: February 2011

The aspiration pressure variation at the tip of metal delivery tube in the supersonic atomization nozzle during gas-only atomization performance had been investigated in this work. The results reveal that the aspiration pressure is subambient at all operating pressures. A general trend is that with increasing atomization gas pressure, the value of aspiration pressure decreases at P0 between 0.5 and 1.5MPa, then increases as P0 ranges from 1.5~3.5MPa, finally decreases again at higher gas pressure (P0>~3.5MPa). When P0>2.0MPa, as the included angle α augments, the aspiration pressure ΔP increases. Meanwhile, the change range of aspiration pressure ΔP significantly enlarges when the jet included angle α raises from16 to 28º. The lager is the apex angle β of metal delivery tube, the greater is the aspiration pressure ΔP. And as the protrusion length of melt delivery tube h increases, the aspiration pressure ΔP decreases gradually.
Synthesis and Characterization of Sr3MgSi2O8:Eu2+, Dy3+ Phosphor Prepared by a Chemical Solution Method
Authors: Pan Wen , Wang Ning Hui , Li Guo Feng , Ning Gui Ling
Published: February 2011

A novel synthesis route for the production of Sr3MgSi2O8:Eu2+,Dy3+ sub-micron quasisphere phosphor powder is reported. Both the host and activator cations were co-precipitated in water-ethanol mixed solutions and precipitation was performed with analytical grade ammonium citratetribasic. As the dispersion media, optimum concentration for PEG in the precursor solution is determined to be 0.08 g/mL. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and fluorescence spectrophotometer were employed to characterize the phosphor. The effect of the calcining temperature on the crystalline particle and luminescence properties of Sr3MgSi2O8:Eu2+,Dy3+ is systematically discussed. Sr3MgSi2O8:Eu2+,Dy3+ single phased quasi-sphere phosphor was achieved by calcining the asprecipitated precursor at 1100°C. Sr2SiO4 was identified as the intermediate phase during the calcination process. Despite the small particle size, the emission intensities were higher by the present method. However, the afterglow characteristic was not better than that prepared by solidstate reaction in the comparable condition.
Preparation of Al-Sc Alloy by LiF-ScF3-ScCl3 Molten Salt Electrolysis
Authors: Guo Rui , Zhai Xiu Jing , Zhang Ting An
Published: February 2011

The paper studied the preparation of Al-Sc alloy by molten salt electrolysis. LiF-ScF3-ScCl3 as the electrolyte, Sc2O3 as raw material, liquid Al as cathode and graphite as anode. The process condition of preparating Al-Sc alloy includes the influence of current density, electrolysis time, temperature of electrolysis, Back EMF, content of Sc in alloy and current efficiency.The content of Sc in alloy prepared by this method has reached to the maximum of 3.437%. The components of alloys showed by SEM were uniform, it is applicable for commercial purposes. Preparation of Al-Sc alloys with scandium oxide as raw materials, it not only reduce environment pollution, but also decease the cost of production. It is reported in many documents, preparing aluminum base alloy by the method of molten salt electrolysis[1-3], people could make many alloys such as Al-Ce、Al-La、Al-RE、Al-Ti、Al-Si-Ti in the aluminum cell, also the method to prepare some rare earth alloys such as Al-Sr、Nd-Fe、La-Ni was reported[4,5]. Use the method of electrolysis to produce some aluminum base alloy with high-melting-point , difficult to restore , high-priced element is a good method because it is technological process is brief, economy is rational, the technology is feasible, this viewpoint is broadly approved in the world[6]. It isn’t necessary to use high-priced Sc as raw material in preparing Al-Sc alloy with molten salt electrolysis, it could control the Sc amounts in the alloy through the different current efficiency and electrolysis time, production in this method could be continuous or semi-continuous, so it is easy to be automatic controlled. A new molten salt system is used in this paper, we use molten salt electrolysis to produce Al-Sc alloy, take scandium oxide as raw material, through the study of the effect of the current intensity，electrolysis time and the electrolysis temperature , Back EMF and cell voltage, the final production Al-Sc alloy contains Sc 2~6%.
Effect of Heating Treatment on the Resistivity of Polycrystalline Silicon
Authors: Zhang Lei , Li Jia Yan , Wang Hao Yang , Xu Fu Min , Tan Yi
Published: February 2011

Effect of heat treatment in atmosphere on the resistivity of polycrystalline silicon has been investigated in this paper. After heat treatment at 1050oC for 10h, there is no obvious change of the resistivity in the N-type region of polycrystalline silicon, which could be contributed to the complicated influence factors, such as more impurities content and defects. On the other hand, an obvious increase of the resistivity was observed in the P-type region which could be contributed the redistribution of Al and B in the Si-SiO2 interface. The resistivity of the P-type region increased from less than 1Ω·cm to several hundreds Ω·cm.
Three Layers Weaved once Structure Design and Performance Testing for Fabric Keyboard Switch
Authors: Zhang Mei Ling , Wang Rui , Wang Zhan Gang
Published: February 2011

Flexible fabric keyboard is a field of smart textile. It can overcome traditional horniness keyboard can’t be foldable and washing. In this laboratory study there is Three Layers Weaved Once structure designed which consists of three kinds of orifice dimension, for example 4 wefts, 8 wefts and 12 wefts. At the same time three kinds of conductive filaments number combined are planed for each orifice dimension. There are 1, 4 and 8 roots of filaments combined together so that contact areas of the conductive material are changed. Then the immediate regain, connection pressure and connection ratio are tested and analyzed for every kind of fabric keyboard switch. It is concluded that 4 wefts orifice dimension and 4 roots of filaments combined is a better project. These findings may assist in recommendations regarding the further development of flexible fabric keyboard. The fabric keyboard switch forms the foundation for many smart textile applications.
Effects of Curing Method on the Gas Separation Performance of Phenolic Resin/Poly(vinyl Alcohol)-Based Carbon Membrane Materials
Authors: Zhang Bing , Wu Yong Hong , Wang Tong Hua , Qiu Jie Shan , Xu Tie Jun , Sun Xiu Hua
Published: February 2011

A novel cheap blended precursor phenolic resin/poly(vinyl alcohol) (PR/PVA) was developed to prepare carbon membranes. The effect of two curing methods (i.e., crosslinker and preoxidation) on the gas separation performance of their derived carbon membranes was investigated. Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to analyze the thermal stability of precursor and the changes in functional groups on membrane surface. The gas permeation of carbon membranes was tested for H2 and N2. The results show that PR, PR/PVA, and two PR/PVA cured samples have three thermal degradation stages. The thermal stability for original PR/PVA membrane is significantly improved via the method of preoxidation or crosslinker. Similar crosslinking structure is formed by the two curing methods. However, carbon membranes from crosslinker method present two-fold higher in hydrogen permeability and four-fold higher in selectivity than that from preoxidation method.
Internal Stress and Grain Size Effect on the Phase Stabilization of ZrO2 Deposited by MOCVD
Authors: Chen Zhe , Wang Bin , Prud’homme Nathalie , Ma Sheng Li , Ji Vincent , Ribot Patrick
Published: February 2011

Zirconia (ZrO2) films were deposited by metal-organic chemical vapor deposition (MOCVD) on {1 0 0} Si single crystal using Zr(thd)4 precursors. The thickness of obtained films is typically of 3.5 μm. The samples have been characterized by Field-Emission-Gun Scanning Electron Microscopy (FEG-SEM) for morphologic and microstructure study, and by X-ray Diffraction (XRD) for crystalline structure. The microstructure analysis showed that unexpected stable single tetragonal phase preferentially grew in low temperature area. According to the literature, the tetragonal phase stabilization is related to the crystalline size and the internal compressive stress. To analyze the effect of grain size and internal stress on the phase transformation, the thermal annealing were carried out in different temperatures and internal stress was measured by XRD method.
A Method for Ultrasonic Characterization of Density, Thickness and Velocity of Homogeneous Coating
Authors: Zhao Y. , Ma Zhen Yue , Lin Li , Li X.M. , Lei M.K.
Published: February 2011

This paper provides a nondestructive method for determination of the density, thickness and velocity of homogeneous coating from an inversion of experimental ultrasonic reflection coefficient amplitude spectrum (URCAS). The detailed analyses of the inverse algorithm and sensitivity of URCAS to the density, thickness and velocity are presented, and the sensitivity is identified as a basis for selecting the experimental data used in inversion. An example of the method and experimental measurement for comparison was given for an epoxy coating with the thickness of 0.277 mm. The relative errors between the inversion and reference value of the density, thickness and velocity were found to be 0.5 %, 3.97 %, and 0.97 %, respectively.
Correlating Ultrasonic Velocity and Porosity Using FDTD Method Based on Random Pores Model
Authors: Zhao Y. , Ma Zhen Yue , Lin Li , Li X.M. , Lei M.K.
Published: February 2011

Ultrasonic testing porosity of TBC (thermal barrier coating) has been investigated by numerical simulation based on the implementation of FDTD (Finite Difference Time Domain) method for the RPM (random pores model). Numerical simulations of measuring ultrasonic longitudinal and transverse velocities were carried out for the plasma sprayed ZrO2 coatings with porosities ranging from 0.5 % to 4 %. The results show both longitudinal and transverse velocity decrease with the increase of porosity, which is similar to the experimental results in the reference (J. Thermal Spray Technol 12 (2003) 530-535). The investigation proves that the combination of the RPM and FDTD method is available for simulating ultrasonic testing of TBC porosity.
Silicon Carbide Base Ceramic Fiber Synthesis from Polycarbosilane-Modified Polymethylsilane Blend Polymers by Melt Spinning
Authors: Xing Xin , Liu Lin , Cao Feng , Li Xiao Dong , Chu Zeng Yong , Cheng Hai Feng
Published: February 2011

A melt-spinnable precursor for SiC based fibers was prepared from blend polymers of polycarbosilane (PCS) and modified polymethylsilane (M-PMS). The blend polymers cured at 320°C are different from M-PMS and PCS. The ceramic yield of these blend polymers is about 83%. The C/Si ratio of M-PMS/PCS derived ceramics (pyrolyzed at 1250°C) is linear to the content of MPMS in M-PMS/PCS. After melt spinning, thermal oxidation curing, and pyrolysis, Si-C-O fibers were obtained. The diameter and the tensile strength of the resulted fibers are 16.5μm and 1.62GPa, respectively.
Si 2p Core Level Shifts of the Epitaxial SiON Layer on a SiC(0001), Studied by Photoemissin Spectroscopy
Authors: Shirasawa T. , Tanaka S. , Muro T. , Tamenori Y. , Harada Y. , Tokushima T. , Kinoshita T. , Shin S. , Takahashi T. , Tochihara H.
Published: February 2011

The epitaxial silicon oxynitride (SiON) layer grown on a 6H-SiC(0001) surface is studied with core level photoemission spectroscopy. Si 2p spectra show three spectral components other than the bulk one. Chemical shifts and emission angle dependence of these components are well explained within a framework of a determined structure model of the SiON layer.
Effects of LiF on Sintering Temperature and Microwave Dielectric Properties of (Ca0.3La0.4/3)(Li0.25Nd0.25)TiO3 Ceramics Doped by ZnO-B2O3- SiO2 Glass
Authors: Gu Yong Jun , Huang Jin Liang , Han Xiang Ju , Li Qian , Wang Xiao , Xu Hui
Published: February 2011

The sintering behaviors and microwave dielectric properties of the (Ca0.3La0.4/3)(Li0.25Nd0.25)TiO3 (abbreviated CLLNT) ceramics doped by small amounts of ZnOB2O3- SiO2 glass and LiF were investigated in this paper. The combination adding of ZnO-B2O3- SiO2 glass and LiF improved the densifications of the CLLNT ceramics and the sintering temperature of the CLLNT ceramics were efficiently lowered from 1400°C to 1000°C. Especially, the 4.0wt% ZnO-B2O3-SiO2 glass and 1.0wt% LiF doped CLLNT ceramic sintered at 1000°C for 3h has optimum microwave dielectric properties of Kr=97, Q×f=1286GHz, and TCF=43 ppm/°C, which enable it a suitable candidate for LTCC applications.
Synthesis and Characterizations of Nanoparticle Sulfur Using Eggshell Membrane as Template
Authors: Cheng Xian Zhong , Cheng Kuang , Liu Jin , Sun Xue Fang
Published: February 2011

Nanoparticles of sulfur with an average diameter of 5-35 nm were successfully prepared using eggshell membrane (ESM) as template in the the presence of surfactant Tween-80. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). The sizes of the nanoparticles sulfur were estimated by Debye-Scherrer formula according to XRD spectrum. Based on the detailed investigation, a possible synthesis mechanism is discussed here.
Urea Effect on Strong Electrorheological Response of Novel Core-Shell Nanoparticles
Authors: Tan Suo Kui , Song Xiao Ping , Guo Hong Yan , Ji Song , Zhao Hong
Published: February 2011

Electrorheological (ER) fluids are regarded as smart materials with potential for application in various industries because of the controllable viscosity, the reversibly and fast response. In this paper, core-shell structured Ni/Ti/Urea nanoparticles, as an ER material, were prepared by a sol-gel method. TEM, XRD and FT-IR spectra demonstrated that the Ni nanoparticles have been homogeneously coated with a 2 nm thick layer of TiO2 containing polar groups. The polar groups were caused by the introduction of urea. The ER effect of the fluids of Ni/Ti/Urea particles in silicone oil was investigated under a DC electric field. It is found that the ER fluids of the urea-doped Ni/TiO2/Urea particles have a high ER activity, which is 10 times that of the particles containing no urea. The polar groups in the particles are the intrinsic reasons for the enhancement of electrorheological effect.
Poly(styrene-Divinylbenzene) Microspheres Prepared by Seed Swelling Polymerization in the Presence of Tung Oil Methyl Esters
Authors: Jin Fu Qiang , Li Yan , Hu Su Qin , Jiang Bo , Zhang Xiao Dong
Published: February 2011

Poly(styrene-divinylbenzene) microspheres were prepared by seed swelling polymerization in the presence of tung oil methyl esters. First, the core monodisperse polystyrene microspheres were prepared by a dispersion polymerization method. Using polystyrene microspheres as seed, tung oil methyl esters as a functional monomer, divinylbenzene as crosslinker, poly(styrene-divinylbenzene) microspheres were prepared by seed swelling polymerization. Then they were characterized by using FT-IR spectroscopy, TG/DSC and optical microscopy. Results showed that the tung oil methyl esters did participate in the copolymerization of styrene and divinylbenzene.
Composites of Poly(lactic Acid) with Rice Straw Fibers Modified by Poly(butyl Acrylate)
Authors: Qin Li Jun , Qiu Jian Hui , Liu Ming Zhu , Ding Sheng Long , Shao Liang , Zhang Guo Hong , Zhao Yang
Published: February 2011

The modified rice straw fibers (MRSF) were prepared by suspension polymerization technique of butyl acrylate (BA) monomer and rice straw fibers (RSF) in water solution. FTIR test indicated that PBA was coated and absorbed on RSF.The biodegradable composites were prepared with the MRSF and poly(lactic acid) (PLA) by HAAKE rheometer. Mechanical properties showed that the tensile strength of PLA/MRSF composites were (W (%) =7.98%) increased by 6 MPa compared with blank sample. The possible reason was that the good interfacial adhesion between PLA and MRSF, which was demonstrated by SEM.
Investigation on Perforation Mechanism of Medium Density Polyethylene
Authors: Hosseinabadi F. , Zebarjad Seyed Mojtaba , Mazinani Mohammad
Published: February 2011

In this article, the perforation mechanism(s) of polyethylene was investigated through experiments. Several polyethylene (PE) film samples were fabricated by compression molding technique. In order to examine the perforation mechanism of PE, perforation tests were conducted according to ASTM F 1306 Standard procedure. The damage and plastic zone areas around the perforated area in PE test samples under cross polarized light condition were studied using the optical microscope. The plastic zone area was measured using an image analysis technique. For further clarification of the perforation mechanism of medium density PE (MDPE) films, the micrographs obtained form scanning electron microscope were examined. SEM observation of the test specimens showed shear bands formed in the plastic zone around the perforated area. The shear bands were observed to be on 45° angle with respect to the direction of applied force.
Effect of SiC on the Oxidation Resistance Performance of C/ZrC Composite Prepared by Polymer Infiltration and Pyrolysis Process
Authors: Zhao Dan , Zhang Chang Rui , Hu Hai Feng , Zhang Yu Di , Wang Qi Kun , He Xin Bo
Published: February 2011

Stitched carbon fiber cloth reinforced zirconium carbide composite (C/ZrC) was prepared by polymer infiltration and pyrolysis (PIP) process. C/ZrC-SiC composite was obtained by further introduction of SiC with PIP process in order to improve anti-oxidation property. The results show that 1.9vol% SiC addition improves the mechanical and anti-oxidation properties of C/ZrC composite. The flexural strength of C/ZrC is 247.9MPa, while that of C/ZrC-SiC is 273.1MPa. After oxidation in a muffle furnace at 1200°C for 30 minutes, the mass loss rate was reduced from 30.6% (C/ZrC) to 20.1% (C/ZrC-SiC), and the flexural strength and elastic modulus of C/ZrC were 56.7MPa and 5.7GPa, respectively, while those of C/ZrC-SiC were 122.9MPa and 17.2GPa, respectively.
Progress of Laminated Materials and Clad Steels Production
Authors: Li Long , Yin Fu Xing , Nagai Kotobu
Published: February 2011

Laminated materials and clad metals have received much attention in the industrial production due to the superior mechanical properties different from those in any of the constituent materials. Clad metal is a composite metal plate generally made by bonding a metal such as stainless steel plate to another metal such as carbon steel or low alloy steel plate. Clad metal not only has sufficient strength required of structural materials but provides other functions including resistance to heat and corrosion. As a result, the application of clad metals can significantly save precious alloying elements and reduce the cost. Therefore, clad metals have become an increasingly interesting topic in a variety of industrial fields. In this paper, fabrication technique and evaluation on mechanical properties of laminated metals have been briefly overviewed. In addition, the applications of laminated materials including clad metals are reviewed and the prospect of clad metals in the future is also described.
Investigation on Shock Response of Magnesium Alloy Honeycomb Sandwich Panels under Low Velocity Impact Loading
Authors: Zhao Hong Yang , Ju Dong Ying , Ito Yasumi , Nemoto Tetsuya , Takahashi Yoshie
Published: February 2011

This paper describes the results of an experimental investigation on the drop off impact test on a range of sandwich panels. The magnesium alloy sandwich panels were fabricated with rolled sheets at different thickness by pressing and bonding method. Out-plane compression test was employed to obtain its basic deformation-force behavior. The impact experiments were carried out in which a steel cylinder was dropped off at various height levels, ranging from 0.5m to 1.5 cm to impact the panel. A high speed camera was employed to take pictures at 20 thousand frames per second and the low-velocity impact response on the sandwich panels is recorded with a dynamic force senor under the panel simultaneously. The shock response with time and the impact absorption energy were analyzed and compared. The results of this study proved that the magnesium alloy honeycomb sandwich panels have good impact energy absorption performance.
Effect of High Volumes of Fly Ash on Flowability and Drying Shrinkage of Engineered Cementitious Composites
Authors: Zhu Yu , Yang Ying Zi , Yao Yan
Published: February 2011

In order to investigate flowability and drying shrinkage of ECC, mini-slump flow deformation test and drying shrinkage are employed to analyse the influence of fly ash on the flowability and shrinkage of ECC. The water-binder ratio is kept at 0.25. The replacement ratio of cement by fly ash is 50%, 60%, 70% and 80%, respectively. The experimental results show that fluidity of fresh cment paste increases obviously as the fly ash becomes larger. The drying shrinkage of ECC specimens is greatly reduced as the content of fly ash increases from 50% to 80%. The measured drying shrinkage strian of ECC specimens with 80% fly ash at 28 days is less than 1000×10-6. 25% reduction of drying shrinkage of ECC is found when the fly ash content increases from 50% to 80%.
An Experimental Research on Electrochemical Impedance Spectra of New High-Specific Energy EDLC
Authors: Liang Zi Lei , Cheng Chong Kuan , Liu Ji Bo , Mi Guo Min
Published: February 2011

The real times Electrochemical Impedance Spectroscopy (EIS) analysis which corresponds to the charge and discharge process was reported in order to evaluate the relationships between impedance and potential for new high specific energy electrochemical double-layer capacitors (EDLC). Also the Niquist plots were presented and the impedance of the EDLC was discussed in terms of complex capacitance. It was found that the high frequency impedance changed with its potential in charging or discharging process, the medium frequency impedance Rct belonged to the resistance of ions diffusion into micro pore or the inner of electrode material decreased with increasing charge voltage and had a certain capacitance of about 1F.
Effects of Aluminum Content on Plastic Formability of Wrought Mg Alloy Sheet Produced by Twin-Roll Casting Process
Authors: Watari Hisaki , Nishio Yoshimasa , Suzuki Mayumi , Haga Toshio , Davey Keith , Koga Nobuhio
Published: February 2011

A total weight reduction approach has been key issue for car manufacturers to cope with more and more stringent requirements for fuel economy. This paper describes the twin-roll casting technology of magnesium alloys that contain relatively high weight ratios of aluminum, such as AZ91,AZ101 and AZ111. The magnesium alloy sheets were cast by a horizontal twin roll caster to manufacture relatively high-strength Mg alloys with high aluminum content. The influences of such process parameters as casting temperature and roll speed were ascertained. The microstructures of cast magnesium alloy sheets were observed to investigate the effects of roll-casting conditions on crystal growth in the cast products. It was found that Mg alloys with high aluminum content can be fabricated at a roll speed of 15 m/min with a horizontal-roll caster. The grain size of the manufactured wrought magnesium alloy sheet was about 10 μm due to rapid solidification in the proposed process.
The Preparation of Cr12MoV/40Cr Dual-Metal Composite Die Steel by Vacuum Diffusion Welding
Authors: Pan Jin Zhi , Ren Rui Ming , Qi Zheng Feng
Published: February 2011

The composite die steel was prepared by vacuum diffusion welding with the cold work die steel Cr12MoV and the alloy steel 40Cr. The composition, microstructure and property changes of the welded joints were studied experimentally, and the relationship between the microstructure and the property after the final heat treatment was analyzed. Based on the experiment results, the suitable welding and heat treatment process were approached. The results show that the good metallurgical bonding is obtained via welding at 1100oC for 30 minutes with a pressure of 20 MP and not more than 0.01 Pa in vacuum. A number of voids are found in the tensile fracture surfaces when the welding temperature is below 1100oC. The grains of 40Cr steel grow obviously when the welding temperature is higher than 1100oC. After quenching at 1050oC and tempering at 200oC, the better mechanical properties are obtained in Cr12MoV because fine carbides distribute evenly. At the same time, the mechanical properties of 40Cr do not decrease dramatically because even though high temperature quenching brings coarse grain size, the amount of lamellar martensite, which is hard and brittle, decreases a lot and the amount of lath matensite increases. After quenching and tempering treatment, the bending strength of the composite die steel reaches 73% of that of Cr12MoV when treated by conventional processing. In the course of welding, carbon migrates from 40Cr to Cr12MoV, which results in a decrease in hardness at the interface of 40Cr.
Microstructure, Texture and Residual Stresses Induced by Surface Thermo-Mechanical Treatments
Authors: Grosdidier Thierry , Bolle Bernard , Puerta Velásquez J.D. , Zou J.X. , Fundenberger Jean-Jacques , Allain-Bonasso Nathalie , Chevrier P. , Tidu Albert
Published: February 2011

This paper reviews some recent results concerning surface integrity of materials processed with two important developing techniques: high speed machining (HSM) – here applied to the difficult case of Ti alloys – and low energy high current pulsed electron beam (LEHCPEB) surface treatment of steels. The effect of the processing parameters on the development of microstructure, texture and residual stresses is detailed for modifications occurring both at the surfaces and sub-surfaces.
Alloy Development and Process Optimization for a New High Strength and High Toughness Titanium Alloys Ti-63
Authors: Liu Yu Qin , Shen Jian Yun , Yue Qiang , Chu Mao You , Wang Xi Zhe , Wang Ding Chun
Published: February 2011

A new high strength and high toughness Ti-alloy, Ti-63, was designed via the CALPHAD approach using a thermodynamic database including elements Ti-Al-Cr-Mo-O-Si-Sn- V-Zr. Good combinations of strength, ductility and fracture toughness, with the values of tensile strength Rm > 1200 MPa, elongation A > 10%, reduction of area Z > 20% and fracture toughness KIC ≈ 80 MPa·m1/2, were achieved for the Ti-63 alloy after optimized heat treatment process.
Simulation of Discrete Dislocation Statics and Dynamics of Magnesium Foam
Authors: Diop Mouhamadou , Hao Hai , Dong Han Wei , Zhang Xing Guo
Published: February 2011

The simulation of magnesium plasticity at the microscopic and mesoscopic scale using space and time-discretized statics and dynamics dislocation was carried out. The complexity of discrete dislocation models dues to the fact that the mechanical interaction of ensembles of such defects is with an elastic nature, and therefore involves long-range interactions. The motion of dislocations or dislocation segments in their respective glide planes are usually described by assuming simple phenomenological viscous flows laws. The formulation of the dislocation dynamics is obtained by the Newton’s Second Law of motion for each dislocation or dislocation segment. The evolution of the dislocation position is obtained by simple difference algorithms.
Comparison between Roll Diffusion Bonding and Hot Isostatic Pressing Production Processes of Ti6Al4V-SiCf Metal Matrix Composites
Authors: Testani Claudio , Ferraro F. , Deodati Paolo , Donnini Riccardo , Montanari Roberto , Kaciulis Saulius , Mezzi Alessio
Published: February 2011

Titanium-metal-matrix composites (Ti-MMC) are materials with very large specific resistance and potential operative temperature up to 800° C. At present these composites are produced by Hot Isostatic Pressing (HIP), a reliable but expensive manufacturing method. To cut production costs, Centro Sviluppo Materiali SpA (CSM) has developed and patented an experimental plant for co-rolling at high temperature sheets of titanium alloy and silicon carbide monofilaments fabrics. The experimental Roll Diffusion Bonding (RDB) pilot plant permits a reduction of process costs of about 40% with respect to the HIP process. This work reports the results of microstructural and mechanical examinations carried out on composites realized by RDB and HIP. The comparison shows that the fibre-matrix interface is stable in both the composites while the mechanical properties of RDB composite are better due to its smaller grain size and high dislocation density.
VMAT2-Deficient Mice Display Nigral and Extranigral Pathology and Motor and Nonmotor Symptoms of Parkinson's Disease
Authors: Taylor Tonya N. , Caudle W. Michael , Miller Gary W.
Published: February 2011

Dopamine is transported into synaptic vesicles by the vesicular monoamine transporter (VMAT2; SLC18A2). Disruption of dopamine storage has been hypothesized to damage the dopamine neurons that are lost in Parkinson's disease. By disrupting vesicular storage of dopamine and other monoamines, we have created a progressive mouse model of PD that exhibits catecholamine neuron loss in the substantia nigra pars compacta and locus coeruleus and motor and nonmotor symptoms. With a 95% reduction in VMAT2 expression, VMAT2-deficient animals have decreased motor function, progressive deficits in olfactory discrimination, shorter latency to behavioral signs of sleep, delayed gastric emptying, anxiety-like behaviors at younger ages, and a progressive depressive-like phenotype. Pathologically, the VMAT2-deficient mice display progressive neurodegeneration in the substantia nigra (SNpc), locus coeruleus (LC), and dorsal raphe (DR) coupled withα-synuclein accumulation. Taken together, these studies demonstrate that reduced vesicular storage of monoamines and the resulting disruption of the cytosolic environment may play a role in the pathogenesis of parkinsonian symptoms and neurodegeneration. The multisystem nature of the VMAT2-deficient mice may be useful in developing therapeutic strategies that go beyond the dopamine system.
Rapidly Evolving Coronary Aneurysm in a Patient with Rheumatoid Arthritis
Authors: Pappy Reji , Wayangankar Siddharth , Kalapura Thomachan , Abu-Fadel Mazen S.
Published: February 2011

Coronary artery aneurysm (CAA) formation in the setting of an acute inflammatory state due to connective tissue disease is rare. We report a case of rapid progression from an ectatic to an aneursymatic left circumflex coronary artery leading to an acute coronary event in a patient with rheumatoid arthritis (RA). We report the accelerated growth of the aneurysm as it was temporally related to the lapse in treatment and the management strategies involved with this entity.
Eco‐evolutionary differences in light utilization traits and distributions of freshwater phytoplankton
Authors: Schwaderer Anne S. , Yoshiyama Kohei , de Tezanos Pinto Paula , Swenson Nathan G. , Klausmeier Christopher A. , Litchman Elena
Published: February 2011

We compiled light utilization traits for 56 species of freshwater phytoplankton to analyze group differences, trait trade‐offs, and allometric scaling relationships. We also used these traits to explain differences in major group distributions along the light availability gradient in 527 lakes in the continental United States. Major taxonomic groups differed significantly in their light utilization traits. Cyanobacteria had the highest initial slope of the growth‐irradiance curve (ɑ) and low irradiance at the onset of photoinhibition, indicating adaptation to low light environments. Green algae had the highest maximal growth rates and low ɑ, indicating adaptation to higher light environments. Groups capable of mixotrophy had traits indicative of poor light competitive abilities and high light requirements. Key light utilization traits scaled allometrically with cell size and exhibited trade‐offs leading to contrasting ecological strategies; ɑ and cell size were conserved at the highest taxonomic level (domain), indicating a fundamental trait divergence between prokaryotic and eukaryotic phytoplankton. In line with these trait differences, major groups showed different responses to light availability in natural conditions. The relative abundances of low light–adapted groups declined with increasing light availability and vice versa. The genera mean values of the initial slopes of the growth‐irradiance curves were significantly negatively correlated with the slopes of the relationships between the genus's relative abundance and light availability characterized by Secchi depth in 527 lakes. This indicates that light utilization traits can be used to explain phytoplankton distributions in nature.
Short‐term hypoxia alters the balance of the nitrogen cycle in coastal sediments
Authors: Neubacher Elke C. , Parker Ruth E. , Trimmer Mark
Published: February 2011

We measured denitrification, anaerobic ammonium oxidation (anammox), oxygen uptake, nutrient exchange, and pore‐water profiles of oxygen in intact sediments at three sites in the southern North Sea, which we experimentally exposed to different oxygen saturations (ambient and ∼ 33% of air‐saturation for oxygen [i.e., our hypoxic treatment]) over 14 months. Denitrification ranged from 1 μmol N m−2 h−1 to 21 μmol N m−2 h−1, anammox 0.2 μmol N m−2 h−1 to 5.7 μmol N m−2 h−1, and oxygen uptake 47 μmol O2 m−2 h−1 to 631 μmol O2 m−2 h−1. The seasonal patterns under ambient oxygen were correlated with those in the hypoxic treatment; though, on the whole, the magnitude of flux was different. On average, under hypoxia, both the penetration and consumption of oxygen decreased by ∼ 50%, denitrification increased by 32%, and anammox remained constant. Anammox accounted for between 10% and 20% of the total N2 production, which agrees with expectations for waters of these depths (30–80 m). Under ambient oxygen the sediments were strong sources of nitrate to the overlying water, 12 μmol NO−3 m−2 h−1 on average, but under hypoxia total N mineralization decreased by 46% and nitrate exchanged ceased. Short‐term hypoxia alters the balance between available N returned to the overlying water, primarily as NO−3, and that removed from the ecosystem as N2 gas.
Influence of iron on fatty acid and sterol composition of marine phytoplankton and copepod consumers
Authors: Chen Xi , Wakeham Stuart G. , Fisher Nicholas S.
Published: February 2011

We conducted laboratory experiments to determine the influence of iron on the fatty acid (FA) and sterol composition of the diatom Thalassiosira oceanica, the cryptophyte Rhodomonas salina, the prymnesiophyte Isochrysis galbana, and the copepod Acartia tonsa that fed on these algae. Algal cells were cultured with no added Fe or with Fe added at 100 nmol L−1. Fe‐deficient culture medium resulted in lower growth rates, cell volumes, and photosynthetic efficiencies for all algal species. The total mass of FA per cell was 2.2–3.1 times as high in Fe‐replete cells as in Fe‐deficient cells; on a carbon–normalized basis, the FA concentrations of Fe‐replete algal cells were 1.4–1.5 times as high. Differences were noted between Fe treatments for specific saturated, monounsaturated, and polyunsaturated FAs within each algal species. Total C‐normalized 20:5ω3 + 22:6ω3 concentrations declined 18%, 25%, and 35% in Fe‐deficient T. oceanica, R. salina, and I. galbana, respectively. Across all species, another consistent difference in FA composition between Fe treatments was for 18:4ω3, which had a C‐normalized concentration that was ∼ twofold higher in Fe‐replete algae. No consistent pattern for all algal species was evident for Fe effects on algal sterol concentration and composition, and in response to Fe limitation sterols were conserved more than C and FAs in these cells. Copepods feeding on Fe‐replete and Fe‐deficient algae displayed smaller differences in FA and sterol concentrations than in their algal diets. Differences in lipid concentration and composition between Fe‐replete and Fe‐deficient algae may partly explain the lower egg production rate of copepods fed Fe‐deficient algae.