bluuebunny/crossref_metadata_2025 huggingface dataset:
INFLUENCE OF NANO-SIO2/POLYAMIDE COMPOSITES COATING ON THERMIC EFFECT AND OPTICAL PROPERTIES OF POLYETHYLENE FILM
Authors: CHEE CHING YERN , YAACOB ISKANDAR IDRIS
Published: April 2009

Polyethylene (PE) film was coated with nanosilica-polyamide layer using rod Mayer process. The nanosilica-polyamide system was prepared by dispersing nanosilica (nano- SiO 2) powder into solvent borne polyamide binder under vigorous stirring. Various compositions of nanosilica-polyamide slurry were prepared. The thickness of the layer was about four µm and eight µm for single and double layer coating respectively. A battery of characterization procedures were used to study the properties of the nanocomposite coating. The uniformity of silica dispersion was probed using elemental mapping procedure and scanning electron microscopy (SEM). With the introduction of nanosilica to polyamide binder, the visible light transmittance and ultra-violet (UV) radiation of nanosilica-polyamide system reduced with increasing nanosilica content and coating layer thickness. Infrared (IR) effectiveness (between 7 µm to 13 µm wavelengths) measurements by FTIR also showed that nanosilica-polyamide system coating on PE film surface greatly improved the thermic effect of PE film. The nanocomposite coating containing 14 wt% nanosilica and with eight µm coating thickness has improved the IR effectiveness of PE to 76%. Thermic effect of the nanocomposite increased with increasing nanosilica content and coating thickness.
EFFICIENT LOAD TRANSFER TO FUNCTIONALIZED CARBON NANOTUBES AS REINFORCEMENT IN POLYMER NANOCOMPOSITES
Authors: CHAKOLI ALI NABIPOUR , CAI WEI , JIEHE SUI , FENG JIANG TAO
Published: April 2009

Multiwalled carbon nanotubes (MWCNTs) grafted with poly(L-lactide-e-caprolactone) (PCLA) were synthesized by in situ ring opening polymerization and used as a reinforcement for neat PCLA. The analyzed data revealed that the applied tensile load on the composite was transferred to the functionalized MWCNTs, leading to a strain failure of the MWCNTs rather than an adhesive failure between the MWCNTs and the matrix. In comparison between the functionalized and pristine MWCNTs, as reinforcement materials for PCLA random copolymers (80% L-lactide (LA), 20% e-caprolactone (CL)) (PCLAR80), the functionalized MWCNTs are more effective reinforcement materials than pristine MWCNTs. In comparison with the neat PCLAR80, the increasing in tensile strength (28.03%) and elongation at failure (49.6%) when functionalized MWCNT loading reaches 1.0 wt%, indicate that an effective reinforcement of the MWCNT-OH-g-PCLA .
STUDY ON PREPARING Al2O3 PARTICLES REINFORCED ZL109 COMPOSITE BY IN SITU REACTION OF Fe2O3/Al SYSTEM
Authors: ZHANG JING , YU HUASHUN , ZHAO QI , WANG HAITAO , MIN GUANGHUI
Published: April 2009

Al 2 O 3 particles reinforced ZL109 composite was prepared by in situ reaction between Fe 2 O 3 and Al . The phases were identified by XRD and the microstructures were observed by SEM and TEM. The Al 2 O 3 particles in sub-micron size distribute uniformly in the matrix and Fe displaced from the in situ reaction forms net-like alloy phases with Cu , Ni , Al , Mn ect. The hardness and the tensile strength at room temperature of the composites have a small increase compared with the matrix. However, the tensile strength at 350°C can reach 92.18 MPa, which is 18.87 MPa higher than that of the matrix. The mechanism of the reaction in the Fe 2 O 3/ Al system was studied by DSC. The reaction between Fe 2 O 3 and Al involves two steps. The first step in which Fe 2 O 3 reacts with Al to form FeO and Al 2 O 3 takes place at the matrix alloy melting temperature. The second step in which FeO reacts with Al to form Fe and Al 2 O 3 takes place at a higher temperature.
HIGH TEMPERATURE TRIBOLOGICAL PROPERTIES OF SPARK-PLASMA-SINTERED Al2O3-SrSO4 SELF-LUBRICATING NANOCOMPOSITES INCORPORATED WITH AND WITHOUT Ag ADDITION
Authors: LI YU FENG , OUYANG JIA HU , ZHOU YU , WANG YA MING , MURAKAMI TAKASHI , SASAKI SHINYA
Published: April 2009

Spark plasma sintering (SPS) is employed to fabricate self-lubricating Al 2 O 3- SrSO 4 nanocomposites incorporated with and without Ag addition. The friction and wear properties have been evaluated using a high temperature friction and wear tester from room temperature to 600°C in dry sliding against alumina ball. X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) analyzer were used to investigate microstructure and self-lubrication mechanisms of nanocomposites after wear tests at different temperatures. Al 2 O 3- SrSO 4 nanocomposites with optimum compositional combinations exhibit low and stable friction coefficients of 0.22 and wear rates in the order of 10-5 mm3/Nm at high temperatures. At low temperature, the Ag additives in the composite form a discontinuous lubricating film to effectively reduce friction and wear. With increasing test temperature, plastic deformation of SrSO 4 during sliding plays an important role in formation of lubricating films on worn surfaces to reduce the friction and wear.
HOT DEFORMATION BEHAVIOR OF IN SITUTIB2 REINFORCED 6351 AL COMPOSITES DURING COMPRESSION AT ELEVATED TEMPERATURES
Authors: GUO SHENGLI , LI DEFU , CHEN DONG , WANG HAOWEI
Published: April 2009

The hot deformation behavior of in situ TiB 2 reinforced 6351 Al composites synthesized by mixed salt reaction method was investigated by compression tests in the temperature range of 300-550°C and strain rate range of 0.001-10 s-1. The microstructure evolution during compression was observed by employing transmission electron microscopy (TEM). The results show that, the flow stress decreases with decreasing strain rate and increasing temperature, and the activation energy is about 169.98 kJ/mol. Microstructure observation indicates that the complex dislocation structures were formed around the TiB 2 particulate at the lower temperature and the lower strain rate and their density is reducing with increasing temperature. Dynamic recovery and recrystalized structures were observed in the lower and higher deformation temperature, respectively. At the higher strain rate, the interface separation between TiB 2 particulate and Al matrix alloy and TiB 2 particulate cracking were found in this study. The main restoration mechanisms of TiB 2/6351 composites during hot deformation are dynamic recovery and dynamic recrystallization.
THERMAL EXPANSION OF ZrO2-ZrW2O8 COMPOSITES PREPARED USING CO-PRECIPITATION ROUTE
Authors: LIU HONGFEI , ZHANG ZHIPING , CHENG XIAONONG , YANG JUAN
Published: April 2009

In this work, a series of ZrO 2/ ZrW 2 O 8 ceramic composites with different amounts of ZrW 2 O 8 were successfully prepared by calcining the precursors synthesized using co-precipitation route at 1150°C for 3 h. The X-ray diffraction (XRD) data confirmed that the composites only consisted of α- ZrW 2 O 8 phase and m - ZrO 2 phase. The scanning electron microscopy (SEM) analysis of the synthesized ZrO 2/ ZrW 2 O 8 composites showed that the specimens had good mixed-uniformities. In addition, the thermal expansion coefficients of the composites decreased with increased amounts of negative thermal expansion ZrW 2 O 8, specimen with 26wt% ZrW 2 O 8 shows almost zero thermal expansion and its average thermal expansion coefficient is -0.5897×10-6K-1 in the temperature range from 30°C to 600°C.
INFLUENCE OF REINFORCEMENT SIZE ON MICROPLASTIC DEFORMATION BEHAVIOR OF SiCP/Al COMPOSITES
Authors: YAN YIWU , GENG LIN , LIU DAYONG
Published: April 2009

The microplastic deformation behavior of 20 vol.% SiCp / Al composites with various SiC particle sizes were investigated. The SiC particles are in four nominal sizes of 1, 5, 20 and 56 µm. The experimental results showed that the micro-yield strength is very sensitive to composite microstructure features. As the particle size increases, the micro-yield strength of composites decrease firstly, and then increase. The observed results were attributed to thermal residual stress and dislocation density due to the large difference in coefficient of thermal expansion between the matrix and reinforcement.
PREPARATION AND MICROSTRUCTURE OF MCNT/Cu NANOCOMPOSITE
Authors: GU WANLI , SHENG WENBIN
Published: April 2009

The fracture process and the structure changes of the multi-walled carbon nanotubes (MCNT) during the mechanical ball milling process were investigated and the samples of ball milled powder were observed by SEM. The results indicate that the MCNT turned into nano-whiskers or nano-particles during the ball milling process. The pre-milled MCNT could be distributed in Cu powders homogeneously. The bulk MCNT / Cu nanocomposite were fabricated by hot pressing the mixed MCNT / Cu powders at a temperature of 1073 K under a pressure of 20 MPa and the microstructure of the composites were investigated. It has been found that the multi-walled carbon nanotubes distributed in copper evenly.
FABRICATION AND HYDROGEN STORAGE PROPERTY OF Mg-3Ni-2MnO2-nCNTS NANOCOMPOSITES
Authors: SUN HONG-FEI , LIANG SHU-JIN , YU ZHENG-XING , FANG WEN-BIN
Published: April 2009

Mg -3 Ni -2 MnO 2 hydrogen storage nanocomposites added with different composition (1%~4%) carbon nanotubes (CNTs) were prepared by mechanical milling under the atmosphere of hydrogen. Different mechanical milling process parameter has been discussed in this paper. Study on hydrogen storage ability of Mg -3 Ni -2 MnO 2- nCNTs with different composition carbon nanotubes has been carried out. The result show that Mg -3 Ni -2 MnO 2- nCNTs excellent heat conductivity and good hydrogen storage (more than 6%vol) ability, the CNTs improve the mass transfer and heat transfer properties of the Mg -3 Ni -2 MnO 2, thus enhancing the kinetic property of hydrogen absorption and desorption of the hydrogen storage nanocomposites, and raising the hydrogen storage capacity. Due to the addition of the carbon nanotubes, the milling stress in the process of preparing the Mg -based namocomposites is reduced, the components can be closely bonded easily, and the additives can play better catalytic roles enhancing the kinetic property of hydrogen absorption and desorption of the hydrogen storage nanocomposites, and raising the hydrogen storage capacity. Due to the addition of the carbon nanotubes, the milling stress in the process of preparing the Mg -based namocomposites is reduced, the components can be closely bonded easily, and the additives can play better catalytic roles.
MECHANISM AND MICROSTRUCTURE TRANSFORMATION OF 3D-Si/LG5 COMPOSITES BY HIGH TEMPERATURE DIFFUSION TREATMENT
Authors: XIU ZIYANG , DENG ZONGQUAN , WANG XIAOFENG , WU GAOHUI
Published: April 2009

A dense and uniform Si p / LG 5 composite were fabricated by squeeze casting technology, and high temperature diffusion treatment was adapted to the composite. Microstructure observation indicated that Si transformed from irregular particles to 3D-structure. Fine dispersive precipitates Si were also observed on Si - Al interface and within Al matrix, smoothing and improving the interface. Based on the microstructure observation, three transformation stages were designated: melting, dissolution and precipitation, solidification. Thermodynamics and kinetics of the transformation can be explained by Gibbs-Thomson effect.
CHARACTERIZATION OF HYPEREUTECTIC Al-20wt%Si/TiCp METAL MATRIX COMPOSITE
Authors: CHOI JINMYUNG , PARK SEULKI , PARK BONGGYU , PARK IKMIN , PARK YONGHO , KIM YONGJIN
Published: April 2009

Hypereutectic Al - Si alloys are one of the most interesting material for high strength structural components because they have low coefficient of thermal expansion (CTE) as well as high wear resistance and mechanical properties. However, Al -based alloys have lower hardness and wear resistance than ferrous alloys and these disadvantages restrict the use of al -based alloy. They could be overcome by making composite reinforced with ceramic particles. TiC was good candidate for the reinforcement of the alloy. Al -20 wt % Si was fabricated by gas atomization and 1, 3 and 5 wt % TiC were mixed to these powders by turbular mixer for 10h with 45rpm. The mixture was hot-pressed at 550℃C for 1h under 60MPa pressure. Relative density of the sintered samples was about 98% of theoretical density. The effect of reinforcements on mechanical properties and wear resistance of composite was investgated. Strength, hardness and wear resistance of the sintered sample were improved by the grain refinement and dispersion strengthening.
A COMPUTATIONAL STUDY ON THE DEFORMATION OF NANOCRYSTALLINE NICKEL
Authors: ZHOU JIANQIU , LI SHUN , XU NAN
Published: April 2009

A phase mixture based finite element model was developed and the deformation of nanocrystalline nickel was studied in this paper. Monocrystalline grain interior phase and amorphous grain boundary phase were applied in the finite element model respectively. The digital topological model, which followed the Log-normal distribution, was generated by a systematic method. The experimental strain and strain rate hardening behaviors and severe nonlinearity phenomena of nanocrystalline nickel can be predicted very well by the numerical simulation. By presenting evolution process of Mises stress and equivalent plastic strain, we found shear localization phenomenon and much faster plastic deformation in grain boundary phase. These result in the relatively lower ductility of nanocrystalline nickel compared with that of coarse-grain counterparts.
GROWTH OF CARBON NANOTUBES ON IRON OXIDE NANOPARTICLES CATALYST DERIVED FROM IRON STORAGE PROTEIN-FERRITIN BY CVD METHOD
Authors: AN YULIANG , LIU YANQIU , YUAN XIA , TAN HAO
Published: April 2009

Here we used the iron oxide nanoparticles derived from ferritin as catalyst for the synthesis of carbon nanotubes (CNTs) by the chemical vapor deposition (CVD) of coal gas. It has been found that the structure and morphology of CNTs can be tailored, to some degree, by varying the experimental conditions such as catalyst loading and process parameters. In addition to straight CNTs, some Y-branched CNTs were also obtained, which might be due to the sulfur species in the coal gas.
THERMAL PROCESSING OF BUNDLED TUNGSTEN OXIDE NANOWIRES
Authors: SUN SHIBIN , ZHAO YIMIN , XIA YONGDE , ZOU ZENGDA , MIN GUANGHUI , ZHU YANQIU
Published: April 2009

Taking the wide band gap one-dimensional (1-D) tungsten oxide nanowires as an example, we here demonstrate systematically the physical characteristics of thermally processed nanowires at temperatures ranging from 400°C to 1000°C, for the first time. Accompanied by a significant drop of specific surface area from 151 m2/g for the as-prepared nanowires to 109 m2/g and 66 m2/g subject to annealing at 400°C and 450°C, dramatically morphology evolution and phase transformation have also been observed. The nanostructured bundles became straighter, larger in diameters and shorter in length, and eventually became irregular particles with size up to 5 µm. The Brunauer-Emmett-Tettler (BET) result suggests that 400°C can be considered as a top temperature limit in nanodevice design where high surface area is important, e.g. in gas sensors. A protocol for thermally processing of these bundled tungsten nanowires has been established.
LOW TEMPERATURE SYNTHESIS OF BaB6 NANOMETER POWDERS
Authors: ZHAO XIAOHUA , MIN GUANGHUI , ZHANG LIN , LIANG LIMEI , YU HUASHUN
Published: April 2009

The reaction synthesis of barium boride (BaB6) nanoparticles under low temperature was investigated in this study. X-ray diffraction (XRD) was used to investigate the phase and the structure of BaB 6. The characterization for microstructure was performed by Field Emission Scanning Electron Microscope (FESEM) with EDS, TEM, Fourier transform infrared (FTIR) spectroscopy and Raman scattering spectroscopy. It is concluded that BaB 6 nanoparticles can be successfully prepared under low temperature at 500°C. XRD pattern shows that the nanoparticles are consisted of predominantly (110)-oriented BaB 6 phase. The powders are polygonal-like shape with the average size of 200 nanometers. TEM identified that each nanoparticle shows perfect single crystal and cubic structure. The boron-to-barium atomic ratio of 5.24:1 was determined, less than the stoichiometric ratio of 6:1. BaB 6 nanoparticles can absorb infrared spectrum at 459, 690, 993, 1329, 1619, 2449 and 3423cm-1 in the test range of 400~4000cm-1, respectively. Three peaks at 677.1, 823.5 and 1116.4cm-1 can be observed clearly from the Raman spectra of BaB 6 nanoparticles at room temperature. The results showed that the electron dispersion of B 6 octahedron in BaB 6 is two-dimensional pancake-type without lattice distortion, which may account for the unique physical properties of BaB 6 nanoparticles.
IN VITRO AND IN VIVO BIOCOMPATIBILITY STUDIES OF ZNO NANOPARTICLES
Authors: ZHENG YUFENG , LI RANZHONG , WANG YUEDAN
Published: April 2009

The in vitro and in vivo biocompatibility of the ZnO nanoparticles were evaluated using cell model and animal model, by MTT assay, flow cell cytometry, pathological optical and electron microscopy examinations. Both the L929 cell and Hela cell proliferative activity were strongly inhibited by the presence of ZnO nanoparticles, no matter cultured with low dose and high dose suspension. AnnexinV-FITC/PI-FCM assay showed that the number of necrotic cell and apoptotic cell increased significantly. Feeding the ZnO nanoparticle suspension through digestive tract would lead to the damage to some primary organs (heart, lung, liver and kidney). Further investigation by TEM showed the expanded sarcoplasmic reticulum and organelle vacuolation features.
NUMERICAL SIMULATION OF BULK METAL FORMING BY MESHLESS METHOD
Authors: LIU HONGSHENG , XING ZHONGWEN
Published: April 2009

Conventional finite element (FE) analysis of bulk metal forming processes often breaks down due to severe mesh distortion. In recent years, meshless methods have been considerably developed for structural applications. The main feature of these methods is that the problem domain is represented by a set of nodes, and a finite element mesh is unnecessary. This new generation of computational methods can avoid time-consuming meshing and remeshing. A meshless method based on reproducing kernel particle method (RKPM) is applied to bulk metal forming analysis. The displacement shape functions are developed from a reproducing kernel (RK) approximation that satisfies consistency conditions. The shape function is modified to impose essential boundary conditions accurately and expediently. A material kernel function that deforms with the material is introduced to assure the stability of the RKPM shape function during large deformations. A program based on RKPM is developed to simulate two examples of bulk metal forming process such as ring compression and cold upsetting, and numerical results demonstrate the performance of the meshless method in bulk metal forming analysis.
MULTI-SCALE FINITE ELEMENT SIMULATION OF SEVERE PLASTIC DEFORMATION
Authors: KIM HYOUNG SEOP
Published: April 2009

The technique of severe plastic deformation (SPD) enables one to produce metals and alloys with an ultrafine grain size of about 100 nm and less. As the mechanical properties of such ultrafine grained materials are governed by the plastic deformation during the SPD process, the understanding of the stress and strain development in a workpiece is very important for optimizing the SPD process design and for microstructural control. The objectives of this work is to present a constitutive model based on the dislocation density and dislocation cell evolution for large plastic strains as applied to equal channel angular pressing (ECAP). This paper briefly introduces the constitutive model and presents the results obtained with this model for ECAP by the finite element method.
MODELING OF MECHANICAL BEHAVIOR AND DESIGN OF MICROSTRUCTURE ON PARTICULATE REINFORCED MATERIALS
Authors: ZONG B. Y. , WANG YAOMIAN , LI JIE , XU NA
Published: April 2009

An analytical model based on Eshelby equivalent inclusion approach and Mori-Tanaka mean field extension was established by introducing numerical matrix and composite secant/tangent moduli to simulate the stress-strain curve of particulate reinforced composite. The same modeling work was also carried out by FEM analysis based on the unit cell model using a commercial ANSYS code. The modeling results by both models on evolution of the load carried by the SiC particles during straining provide strong evidences to back up the strengthening mechanism of the load sharing. The modeling was also carried out to study the influence of different volume fractions and aspect ratios on elastic modulus and yield strength of the composites with different reinforcing particles to get a better understanding of strengthening mechanisms of the materials. A concept of microstructure design for particulate reinforced materials was argued based on new developments in understanding of the relationship between properties and microstructure. The optimal geometry of particulate reinforcement was discussed in respect to the best match up with matrix mechanical behavior.
STUDY ON THE INFLUENCE LAWS OF MECHANICAL PROPERTIES ON STIFFNESS OF AUTOMOTIVE BODY PANELS
Authors: ZHAO LIHONG , JIANG SHUYONG , REN ZHENG YI , YU HAIPING , YANG YUYING
Published: April 2009

The criterion and research technique of auto body panels stiffness are introduced in this work, and the finite element models (FEM) of cylindrical shallow shell that could represent auto body panels are established. Simulations of forming, springback and stiffness on cylindrical shallow shell are carried out. The simulations show great accuracy with the experimental results. Extensive simulated results of the influence laws of material mechanical properties on stiffness are achieved, such as yield strength, strain-hardening exponent, Young's modulus, anisotropy parameter and strength coefficient. With comparison of the weight coefficient of material mechanical properties on stiffness, it can be concluded that the Yong's modulus, strain-hardening exponent and yield strength are key influencing factors of stiffness. With the analysis of distribution of the strain after cylindrical shallow shell forming, plastic deformation during the forming process resulting in work-hardening of the material is one of the main reasons for increasing stiffness.
DEFORMATION MECHANISM OF BULK NANOCRYSTALLINE NI PREPARED BY PLASMA EVAPORATION METHOD
Authors: ZHOU JIANQIU , ZHU RONGTAO , ZHANG ZHENZHONG
Published: April 2009

Bulk nanocrystalline Ni samples were prepared by plasma evaporation method combined with hot pressure sintering. The compressive mechanical properties of the bulk samples were tested under quasi-static strain rates at room temperature and the evolution of microstructure of bulk sample before and after compression was studied. The experimental results indicated that the bulk samples show a good combination of strength and ductility and have obvious strain rate sensitivity. Both dislocation glide mediated and grain boundary mediated deformation mechanism were found to be main operating deformation mechanisms for the bulk samples based on the mechanical behaviors and grain refinement after compression.
MAGNETIC PROPERTIES, NANOSTRUCTURE AND ORDERING KINETICS OF FePtCu THIN FILMS
Authors: CHEN G. J. , SHIH Y. H. , JANG J. S. C. , JIAN S. R. , CHANG W. C. , HUANG J. C. A.
Published: April 2009

In this study, the ( FePt )100- x Cu x ( x =0, 4.6, 6.7, 8.8, 10.9) ( FePtCu ) alloy films were prepared by co-sputtering. The effects of Cu addition content and heat treatment on the nanostructure and magnetic properties of the polycrystalline ( FePt )100- x Cu x films are reported. The experimental results show that the ordering temperature of the ( FePt )100- x Cu x ( x =6.7) films reduced to 320°C, which is much lower than that of the FePt alloy. After heat treatment at 600°C for 1 hour, the ( FePt )100- x Cu x ( x =6.7) film shows a coercive force of 15 kOe and the magnetization of 576 emu/cc. The magnetic properties of the FePtCu films can be adjusted by varying the Cu content in the films. The enhancement of the magnetic properties of the FePtCu films mainly resulted from the formation of the order L 10 phase. DSC traces of as-deposited disorder films at different heating rates, to evaluate the crystallization of the order phase, showed that the addition of Cu atoms reduced the activation energy of ordering from 217 kJ/mol to 87 kJ/mol for the ( FePt )100- x Cu x films ( x = 0 and 6.7, respectively). The reduction of the ordering temperature and corresponding activation energy might due to the solid solution of the Cu atoms in the FePt films.
PHASE EVOLUTION AND MAGNETIC PROPERTIES OF TbCu7-TYPE (Sm, Pr)Co7-xHfxMy (x = 0-0.5; y = 0-0.14) RIBBONS
Authors: Chang H. W. , Huang S. T. , Chen I. W. , Chang C. W. , Chang W. C.
Published: April 2009

The effects of Hf substitution and C content on the magnetic properties, phase evolution, and microstructure of melt spun ( Sm , Pr ) Co 7- x Hf x C y ( x = 0-0.5; y = 0-0.14) ribbons have been studied. A proper Hf substitution is helpful not only in stabilizing 1:7 phase but also in enhancing its magnetic anisotropy field. As a result, magnetic properties of B r = 6.4 kG , i H c = 7.3 kOe and ( BH ) max = 8.7 MGOe for SmCo 6.9 Hf 0.1 ribbons are obtained. Besides, a small amount of C addition in the ribbons could slightly modify phase constitution and effectively refine their microstructure to strengthen the exchange coupling effect between magnetic grains. Furthermore, a slight Pr substitution for Sm may further increase the magnetization and the magnetic properties of the ribbons. The optimal magnetic properties of B r = 7.1 kG , i H c = 8.5 kOe and ( BH ) max = 11.2 MGOe could be achieved for the directly quenched Sm 0.8 Pr 0.2 Co 6.9 Hf 0.1 C 0.12 ribbons.
DESIGN OF ONE-DIMENSIONAL PHOTONIC QUASI-CRYSTAL ARRAYS FOR THE FLAT-BAND PASS FILTERS
Authors: YEO JONG-BIN , LEE HYUN-YONG , YUN SANG-DON , YANG HOE-YOUNG , KIM JIN-HEE
Published: April 2009

We designed the one-dimensional photonic quasi-crystals (1D PQCs) arrays for application to the flat-band (FB) pass filters using a transfer matrix method (TMM). In this work, the PQCs of the combinations of SiO 2- TiO 2 and SiO 2- ITO were designed with the centre wavelength of 1.550 µm at an incident angle of 8°. The width of flat-transmission bands increases with increasing the number of cavity. For a SiO 2/ TiO 2–based PQC with 3-cavity structure, the FB-width was evaluated to be about 0.7 nm and the insertion loss was approximately 0.3 dB. In addition, the band-center wavelength exhibited a blue shift with an increase of incident angle and their band widths are uniform for specific θ i -ranges. An application of this FB-pass filter to a wavelength division multiplexing (WDM) device was also proposed. We believe that the PQC-based devices could be comprehensively applied to the new conceptional optical passive and active devices.
PHOTOCATALYTIC DEGRADATION PROPERTY OF NANO-TiO2/DIATOMITE FOR RODAMINE B DYE WASTEWATER
Authors: LIU YUE , ZHENG SHUILIN , DU GAOXIANG , SHU FENG , CHEN JUNTAO
Published: April 2009

The Nano- TiO 2/Diatomite compound photocatalyst is used to degrade rhodamine B dye wastewater in photochemical reactor. The test result indicates that the rate of photodegradation of rhodamine B is influenced by reactive conditions. The best technical conditions are concentration of rhodamine B solution 10mg/L, ultraviolet light 300W, the compound photocatalyst amount used 1g/L, the pH 5.8, reaction time 20min. Under these conditions the rate of photodegradation of rhodamine B may reach as high as 97.80%. And the efficiency of photodegradation of catalyst only has a little changed in recycling.
A FINITE ELEMENT ANALYSIS OF EFFECTIVE THERMOELECTROELASTIC PROPERTIES OF COMPOSITES WITH A DOUBLY PERIODIC ARRAY OF PIEZOELECTRIC FIBERS
Authors: YAN PENG , JIANG CHIPING
Published: April 2009

This work deals with modeling of 1-3 thermoelectroelastic composites with a doubly periodic array of piezoelectric fibers under arbitrary combination of mechanical, electrical loads and a uniform temperature field. The finite element method (FEM) based on a unit cell model is extended to take into account the thermoelectroelastic effect. The FE predictions of effective properties for several typical periodic microstructures are presented, and their influences on effective properties are discussed. A comparison with the Mori-Tanaka method is made to estimate the application scope of micromechanics. The study is useful for the design and assessment of composites.
ELECTRONIC AND OPTICAL PROPERTIES OF MgV0.125Al1.875O4 BY FIRST PRINCIPLES
Authors: LI MEILING , SUN FENGJIU
Published: April 2009

The electronic and optical properties of MgV 0.125 Al 1.875 O 4 are investigated by use of the first principle. The calculated results indicate that the V -doped compound is semiconductor with a small gap 0.2102eV. It is concluded that the doping element V has specific rule in the MgAl 2 O 4 spinel, which leads it showing finite value DOS at the Fermi level and makes the total DOS gaps smaller than that of MgAl 2 O 4. In MgV 0.125 Al 1.875 O 4, the influencing factor on the optical process is that the 3d orbitals of V ion are highly localized and the part of 3d bands well incorporate into the conduction band, which very benefit to charge transfer transitions between O 2 p orbitals to the hybridized V 3 d orbitals near the conduction band. The absorption intensifies in the visible zone due to the V doping. The charge-transfer transitions around 282nm and 433nm between V and O are attributed to the optical excitation and deexcitation process, respectively, in agreement with experimental observations.
REVIEW OF RESEARCH WORK ON Ti-BASED COMPOSITE COATINGS
Authors: GABBITAS BRIAN , SALMAN ASMA , ZHANG DELIANG , CAO PENG
Published: April 2009

The service life of industrial components is limited predominantly by Chemical corrosion/mechanical wear. The project is concerned with the investigation of the capability of Ti ( Al , O )/ Al 2 O 3 coatings to improve the service life of tool steel (H13) used for dies in aluminium high pressure die casting.

This paper gives a general review on the research work conducted at the University of Waikato on producing and evaluating the titanium/alumina based composite coatings. The powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO 2 powders in two different molar ratios followed by a thermal reaction process. The feedstocks were then thermally sprayed using a high velocity air-fuel (HVAF) technique on H13 steel substrates to produce a Ti ( Al , O )/ Al 2 O 3 composite coatings. The performance of the coating was assessed in terms of thermal shock resistance and reaction kinetics with molten aluminium. The composite powders and coatings were characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD).
SURFACE MODIFICATION OF METALLIC MATERIALS BY HIGH CURRENT PULSED ELECTRON BEAM
Authors: HAO SHENGZHI , DONG CHUANG , LI MINCAI , ZHANG XIANGDONG , WU PINGSHENG
Published: April 2009

High current pulsed electron beam (HCPEB) has been developing as a useful tool for surface modification of materials. This paper presents our research work on surface modification of metallic materials, such as mold steel, stainless steel and magnesium alloy, with a HCPEB equipment of working parameters as electron energy 27keV, pulse duration ~1µs and energy density ~5J/cm2. Investigations performed have shown that the most pronounced changes of phase-structure state and properties occurring in the near-surface layer. The formation mechanism of surface craters and their evolution regularity are discussed based on the elucidation of non-equilibrium temperature filed and different kinds of stress formed during pulsed electron beam treatment. After the HCPEB treatments, samples show significant improvements in measurements of wear and corrosion resistance.
CHARACTERIZATION OF n AND p TYPE ZNO THIN FILMS DEPOSITED BY CATHODIC PULSED FILTERED VACUUM ARC SYSTEM
Authors: KAVAK H. , ERDOGAN N. H. , KARA K. , YANIS H. , BAZ Z. , ESEN R.
Published: April 2009

The transparent, conductive n and p -type semiconducting ZnO thin films were prepared by pulsed filtered cathodic vacuum arc deposition (PFCVAD) method. The structural, optical and electrical properties of n and p -type ZnO thin films are investigated after annealing at 450°C. 197 nm thick n -type ZnO thin film was deposited with oxygen pressure of 8.5 × 10-4 Torr . XRD pattern of annealed ZnO thin film exhibits hexagonal structure with (100), (101) and (110) orientations. The crystallite size of semiconductor ZnO thin film is 18 nm, interplanar distance 0.16 nm and lattice constant c is 0.52 nm for (110) orientation. The optical transmittance spectra of n and p -type ZnO films are over 90% in the visible wavelength region with optical energy gap 3.3 eV. p -type ZnO thin films are produced by oxidation of PFCVAD deposited zinc nitride. Zinc nitride is deposited with nitrogen pressure of 8.6 × 10-4 Torr and the thickness of this film is 179 nm. The oxidation of zinc nitride thin films at 450°C results in hexagonal structures p -type ZnO thin films. XRD pattern of this film has the same (100), (101) and (110) orientations with the same crystalline structures as the directly deposited ZnO thin film. Hall measurements indicated that ZnO films were p -type and the highest carrier concentration of 1.08 × 1018 cm -3 and mobility of 93.53 cm2/Vs were obtained.
EFFECT OF DEPOSITING TEMPERATURE ON THE INTERFACIAL ADHESION OF NANOCRYSTALLINE DIAMOND FILMS GROWN ON TITANIUM BY MICROWAVE PLASMA ASSISTED CVD PROCESS
Authors: ASKARI SYED JAWID , MERCHANT ALI IMRAN
Published: April 2009

In contrast to their exceptional mechanical properties, titanium and its alloys possess poor friction and wear characteristics. Nanocrystalline diamond (NCD) films appear to be a promising solution for their tribological problem due to their smooth surfaces and small grain size. However, the synthesis of a well adherent NCD film on titanium and its alloys is always complicated due to the different thermal expansion coefficients of the two materials, the complex nature of the interlayer formed during diamond deposition, and the difficulty in achieving very high nucleation density. In this work NCD thin films have been deposited on pure Ti substrates in a microwave plasma chemical vapor deposition (MWPCVD) reactor under fixed pressure and methane concentration in hydrogen but over a wide temperature range. The effects of depositing temperatures on the adhesion of films are evaluated using Rockwell indentation tests. It is found that by increasing the deposition temperature the films bonding deteriorates. The films synthesized are characterized by field emission scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and X-ray diffraction.
STRUCTURAL RESPONSE OF ALUMINIUM FOAM HYBRID SANDWICH PANELS UNDER THREE-POINT BENDING LOADING
Authors: KABIR KAVEH R. , VODENITCHAROVA TANIA , HOFFMAN MARK
Published: April 2009

The present study focuses on the structural response of sandwich panels consisting of a commercial closed-cell foam core and thin aluminium sheet skins under static three-point bending loading. Panels of different thicknesses and span lengths were tested, and the influence of the foam density, core thickness and skin type on the response was revealed. The failure modes in bending were greatly dependent on the span length but independent on the foam thickness. For short spans, the deformed shape at failure was asymmetric, as opposed to a symmetric mode for long spans. The density and thickness of the foam core, the presence of reinforcing face sheets and the beam span determined the failure load and bending strength of the sandwich panels.
THE SOFTENING BEHAVIOR OF HIGHER NIOUBIUM CONTENT X80 PIPELINE STEEL
Authors: MIAO CHENGLIANG , SHANG CHENGJIA
Published: April 2009

In this paper, the softening behavior of higher Nb content X80 pipeline steel was investigated by means of the stress relaxation curve. Deformed above 1050°C, the softening of the steel is fast and controlled by static recrystallization. Although the softening at 1000°C is slower obviously, it was also controlled by static recrystallization, no more than the grain growth rate was declined because of the drag effect of solute Nb . Moreover, the pinning effect of precipitation is more effective to retarding the softening at relatively lower temperature and that can be revealed by the softening curve too.
EFFECT OF STRAIN RATE ON THE HIGH-TEMPERATURE COMPRESSIVE DEFORMATION BEHAVIOR OF ULTRAFINE-GRAINED COPPER
Authors: LI XIAO-WU , JIANG QING-WEI , LIU YIN , WANG YAO
Published: April 2009

The high-temperature deformation and damage behavior of ultrafine-grained (UFG) Cu produced by equal channel angular pressing (ECAP) were investigated and compared at two strain rates of 10-2 s-1 and 10-3 s-1. It is found that the strain rate has an obvious effect on the deformation and damage behavior of UFG Cu , especially at the testing temperatures near and above recrystallization. In general, the lower the strain rate, more universally grain coarsening takes place, the lower the yield stress and steady flow stress are, and more aggravated the degree of deformation damage becomes.
DETERMINATION OF CRYSTAL STRUCTURE AND CRYSTALLOGRAPHIC CHARACTERISTICS IN Ni-Mn-Ga FERROMAGNETIC SHAPE MEMORY ALLOYS
Authors: CONG D. Y. , ZHANG Y. D. , ESLING C. , WANG Y. D. , ZHAO X. , ZUO L.
Published: April 2009

Ni - Mn - Ga ferromagnetic shape memory alloys (FSMAs) have received great attention during the past decade due to their giant magnetic shape memory effect and fast dynamic response. The crystal structure and crystallographic features of two Ni - Mn - Ga alloys were precisely determined in this study. Neutron diffraction measurements show that Ni 48 Mn 30 Ga 22 has a Heusler austenitic structure at room temperature; its crystal structure changes into a seven-layered martensitic structure when cooled to 243K. Ni 53 Mn 25 Ga 22 has an I4/mmm martensitic structure at room temperature. Electron backscattered diffraction (EBSD) analyses reveal that there are only two martensitic variants with a misorientation of ~82° around <110> axis in each initial austenite grain in Ni 53 Mn 25 Ga 22. The investigation on crystal structure and crystallographic features will shed light on the development of high-performance FSMAs with optimal properties.
FABRICATION OF BULK TITANIUM ALUMINIDES BY THERMAL SPRAY
Authors: CAO P. , GABBITAS B. , ZHANG D. L. , SALMAN A.
Published: April 2009

In this study we utilized two types of plasma spray processing, namely atmospheric plasma spraying (APS) and hypersonic plasma spraying (HPS) to produce structural bulk titanium aluminides. Microstructure characterisation of the deposits, their compositional changes and phase transformations were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. It was found that the TiAl alloyed powder particles experienced a significant phase change during both APS and HPS processes. During APS the TiAl alloyed powder particles also experienced a significant compositional change; having a considerable amount of titanium oxides. On the other hand, the compositional change during HPS was negligible. At the end of the paper, an attempt of using a low temperature spraying process, i.e. cold gas dynamic spray, was reported as an alternative coating method.
DEFORMATION BEHAVIORS OF THERMO-MECHANICALLY PROCESSED Zr-Nb-P ALLOYS
Authors: KO SAN , HONG SUN IG
Published: April 2009

Deformation behaviors of Zr -1.5 wt. % Nb alloys with no phosphorus addition and with various phosphorous contents (20 ppm, 160 ppm) were investigated in this study. The flow stress of Zr -1.5 Nb increased with the addition of 20~160 ppm phosphorous over a temperature range from room temperature to 450C. The dislocation density appeared to increase with increase of phosphorous content. The increase of strength with phosphorous addition may be linked to the increase of dislocation density. The increase of dislocation density with a higher phosphorous content can be associated with the increase of statistically stored dislocation due to a lower recovery rate. The activation volume decreased from 650~750 b 3 to 450`550 b3 with the addition of 160 ppm phosphorous at room temperature. The rate-controlling mechanism of the deformation of Zr - Nb - P alloy is thought to be the dislocation-solute interaction in which the segregation of alloying elements such as oxygen and phosphorous atoms affects the activation length of dislocations.
3D NUMERICAL AND EXPERIMENTAL STUDY ON FLOW CHARACTERISTICS OF MULTI-PASS ECAP WITH AA1050
Authors: JIN YOUNG GWAN , SON IL-HEON , IM YONG-TAEK
Published: April 2009

Experiments and numerical simulations were conducted to investigate flow behaviour of the specimen made of commercially pure aluminum alloy (AA1050) during multi-pass equal channel angular pressing (ECAP) for route A up to four passes. Influence of processing conditions on friction and flow behaviour was investigated by measuring load variations, microhardness distributions and microstructure changes depending on the number of passes. It was carefully simulated by employing the finite element technique by tracing the local deformation, determining the load requirement and comparing the local strain with microhardness distributions. Change of the grain size depending on the number of passes was monitored by transmission electron microscopy. The present work clearly showed flow characteristics of the deformed specimen at the central and surface regions due to the effect of the number of passes for the multi-pass ECAP.
LOW-FREQUENCY DAMPING BEHAVIOR OF PURE MG PROCESSED BY EQUAL CHANNEL ANGULAR PRESSING
Authors: FAN G. D. , ZHENG M. Y. , HU X. S. , CHANG H. , WU K.
Published: April 2009

Equal channel angular pressing (ECAP) was performed on the extruded pure magnesium at 250°C for 4 passes. After ECAP processing, the grain size was significantly refined. And the damping capacity was increased at low strain amplitudes, but decreased at high strain amplitudes. Three peaks were observed during the measurement of damping capacity at elevated temperatures. The mechanisms for damping capacity of pure Mg at ambient and elevated temperatures were discussed.
EFFECT OF ANNEALING ON CRYSTALLINE STATE AND MAGNETIC PROPERTIES OF (Tb0.28Dy0.72)Fe1.90 THIN FILMS
Authors: LI KUOSHE , LI HONGWEI , YAN HUI , YU DUNBO , WANG FENGYING , ZHANG GUOCHENG
Published: April 2009

Giant magnetostrictive ( Tb 0.28 Dy 0.72) Fe 1.90 thin films were deposited on Si (111) substrates at room temperature by pulsed laser deposition (PLD). The crystalline state and the magnetic properties of the samples were investigated in relation to the different annealing temperatures T a , which varied between 623K and 923K. X-ray diffraction results indicated the films are in amorphous state after annealing at T a = 623 K -823 K for 1h, and were partially crystallized at T a = 923 K for 1h. Meanwhile, the annealing treatment showed a great influence on the magnetic anisotropy. The orientation of the magnetic easy axis of the as-deposited films changed from perpendicular to parallel to the film plane after annealing treatment. The mechanism of the transformation of the magnetic easy axis was explained in terms of the tensile stress which is formed due to the difference in the thermal expansion coefficients of the thin film and substrate.
SURFACE PLASTIC DEFORMATION REGULARITY AND MICROSTRUCTURAL EVOLUTION IN THE COMPOUND ROLLING OF Q235 BILLET
Authors: REN TAO LIN , SHAN DE BIN , LU YAN
Published: April 2009

In order to meet the double demands on the high temperature creep and the fatigue property, compound rolling is put forward in this study. This technique obtains dual microstructures of billet, fine microstructure on the surface and original state microstructure in the center, through localizing the plastic deformation on the surface layer and leaving little plastic deformation in the center. Based on the local load theory, a set of equipment for the compound rolling has been produced. In order to study the deformation regularity of the compound rolling, Q235 billets have been used and the flow net method for strain measurement has been employed. The deformation regularity difference between the compound rolling and the flat rolling has been investigated. In addition, the microstructural evolution after the compound rolling on the surface and in the center of the Q235 billet has been observed. The results indicate that the compound rolling technique will localize the plastic deformation on the surface of the billet but leave little plastic deformation in the center.
EFFECT OF Ce ON GRAPHITE NODULE COUNT AND SIZE DISTRIBUTION IN DUCTILE IRON
Authors: DIAO XIAOGANG , NING ZHILIANG , CAO FUYANG , SUN JIANFEI
Published: April 2009

The graphite nodule density and size distribution are two very important parameters in the characterization of the microstructures of ductile iron. Various amount of cerium element ( Ce ) (from 0.005% to 0.020%) were added into ductile iron cast in sand moulds to investigate the effect of Ce concentration on graphite nodule count and size distribution. The addition of Ce has a significant effect on solidified microstructures of ductile iron. Increasing of Ce concentration from 0.005% to 0.014%, an obvious increase in nodule graphite amount is achieved and graphite size becomes finer. When the addition level of Ce reaches 0.018% or 0.020%, spheroidal graphite begins to coarsen, resulting in the decrease in graphite amount and formation of the some non-spherical graphite. An evident nucleus and faceted crystals inside a nodule are clearly distinguished and the thin flakes that constitute the nodule are observed from the SEM photograph. EDX-analysis of nucleus of the spheroidal graphite shows that it is composed of sulfur, cerium, magnesium and trace calcium. The 3-D nodule count of ductile iron is 11.7 × 103/ mm 3 with 0.005% Ce addition. The value is 45.8 × 103/ mm 3 with Ce addition up to 0.014% and the majority of diameter is less than 30 µm. However, with 0.018% Ce residual, the nodule count decreases to 29.0 × 103/ mm 3. The value is close to that of 0.018% Ce when Ce concentration is 0.020%, and the majority of diameter is less than 40 µm. The results indicate that the graphite nodule count reaches the maximum and mean diameter reaches the minimum with 0.014% Ce residual existing in ductile iron.
STICKY AND SLIPPY: TWO HYDROPHOBIC STATES TRANSITION OF ZnO HIERARCHICAL FILMS BY FLUOROALKYLSILANE MODIFICATION
Authors: LIU CHANGSONG , ZHANG QIANG , LI TAO , LI ZHIWEN
Published: April 2009

ZnO films with hierarchical structures were prepared in an aqueous solution of zinc nitrate, hexamethylenetetramine and hydrofluoric acid. They demonstrated superhydrophobicity and two superhydrophobic states conversion from sticky to slippy after they were modified by fluoroalkylsilane (FAS) self-assemble layers. Before FAS modification, ZnO hierarchical structures, having sphere-like microstructures with nano-petals, showed water contact angle of 151° and a sticky behavior: water droplets rest on such surface did not slide when the surface was tilted to any angle or even upside down, indicating a strong adhesion between water and the surface. However, after FAS modification, ZnO films showed an increase of water contact angle up to 164° and a large difference in dynamic wetting properties: water droplets moved spontaneously and hardly came to rest even on a horizontal surface. The transition from sticky ("Wenzel's state") to slippy ("Cassie's state") resulted from surface free energy change from high to low. The results also confirm that the low enough surface energy, cooperating with surface roughness, is crucial in making Cassie's state superhydrophobicity. The realization of conversion from sticky to slippy is of importance for further understanding wetting properties and applications of ZnO micronanostructures.