bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal Distribution of Several Inorganic Microparticles in Mice
Authors: Abe Shigeaki , Koyama Chika , Akasaka T. , Uo Motohiro , Kuboki Yoshinori , Watari Fumio
Published: March 2009

Internal distributions of several inorganic microparticles administered into the tail vein of mice were determined using a Scanning X-ray analytical microscopy and energy-dispersed X-ray spectroscopy. After administration through the tail vein of mice, the particles circulated by blood flow then reach some organs and temporally remained. In this study, we determined that the distribution behaviors in body depend upon the chemical species and the size.
Macroporous Calcium Phosphate Bioceramics as Drug Release Agents: A Kinetics Study of Ampicillin Release
Authors: Albuquerque J.S.V. , Franca I.W.L. , Silva G.F. , Ferreira A.L.O. , Nogueira R.E.F.Q.
Published: March 2009

Semi-synthetic beta-lactam antibiotics are the most important class of antibacterial agents. Their use in veterinary and human medicine is in continuous expansion. Calcium phosphate bioceramics have been used in medicine and dentistry for nearly 30 years. Calcium phosphate ceramics (CPC) are nowadays being widely used as drug delivery systems because of their desirable properties such as biocompatibility, bioresorbability, controlled release etc. In recent years In this work, kinetic models to describe ampicillin adsorption from CPC were investigated. Calcium phosphate bioceramic are analogous to the mineral component of bones, its properties make it suitable for implant materials and delivery agents of drugs
Preparation of Synthetic HA Scaffold and the Effect of Heat Treatment on Bone Formation
Authors: Strnadova Marie , Protivinsky Jiri , Soukup Tomas , Strnad J.
Published: March 2009

The synthetic nanostructured HA powder was prepared by the reaction of calcium hydroxide Ca(OH)2 aqueous solution and phosphoric acid H3PO4. The powders were foamed using hydrogen peroxide and heat treated at temperatures ranging from 120 to 700°C. Bovine deproteinized bone BioOss was used as a reference material. Elemental analysis, X-ray diffraction, chemical analysis, differential thermal analysis, scanning electron microscopy, gas adsorption and mercury porosimetry were used to characterize the precipitates. In vitro cytotoxicity test and the preclinical evaluation of this material were performed. In vivo tests were carried out in the tibiae of beagle dogs. All animals were euthanized 3 and 6 months after implantation. The material degradation and new bone formation was observed. The process of precipitation and coagulation can be applied to obtain pure synthetic HA powder. Foaming with H2O2 represents a method suitable to produce HA material with higher surface area and porosity. The physico-chemical properties of HA granules and in vivo tests determined that synthetic scaffold is comparable with bovine bone material. No significant differences between synthetic HA150 scaffolds and bovine bone BioOss were observed in vivo. The heat treatment of HA results in slower resorption and remodeling.
Precipitating Rate of Ion in Cement-Based Materials
Authors: Long Guang Cheng , Xie You Jun , Yu Zhi Wu
Published: March 2009

The chloride ions and sulfate ions precipitating rates in surface layer of different mortars was experimentally measured. And the concept of precipitating rate of ions and corresponding equation in cementitious materials was proposed. Further, some factors affecting precipitating rate of ions were investigated. Results indicate that the precipitating rate of ions in surface layer of mortar can be expressed well by an exponential function of time variable. And the exponent in corresponding equation is about 0.42 in investigation scope, which cannot be influenced greatly by addition of mineral admixture or type of ions such as chloride ions or sulfate ions. However, the precipitating rate coefficient of ions changes remarkably with compositions of mortar or types of ions. Addition of mineral admixture can reduce the precipitating rate coefficient of ions.
Experiment and Analysis of Smart Concrete Beam Strengthened Using Shape Memory Alloy Wires
Authors: Kuang Ya Chuan , Ou Jin Ping
Published: March 2009

Shape memory alloy (SMA) has many potential applications as an actuator in smart material systems due to its abilities of shape memory, pseudo-elasticity, high damping and wear resistant. In this paper, a smart concrete beam has been developed by taking advantage of the shape memory effect of SMA and the characteristic of applying large forces on the resisting member in the transformation of SMA on heating. Deformation behavior and influence of factors on the deformation behavior of SAM smart concrete beam were investigated experimentally. Actuation mechanics of SMA was analyzed. Experimental results show that SMA wires significantly increase structural survivability and allow structural to recover from residual deformation by damaged earthquake and typhoon, and the crack almost closes completely after electrically heating the SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by heating. An increasing of the initial pre-strain of SMA wire can significantly improve the capacity of self-restoration of SMA concrete beams, but the steel main bars play a very negative role in reducing residual deformation.
Full-Scale Measurements of Typhoon Effects on a Super RC Tall Building Based on a Remote Monitoring System
Authors: Zhi Lun Hai , Li Q.S. , Li Z.N. , Wu J.R.
Published: March 2009

This paper presents the field measurement results of wind effects on the world’s tallest reinforced concrete building (CITIC Plaza, 391 m high) located in Guangzhou during the passage of typhoon Pabuk on August 10, 2007. The field data such as wind speed, wind direction and acceleration responses were simultaneously and continuously recorded from the tall building by a remote monitoring system. Detailed analysis of the field data was carried out to investigate the wind effects on the super tall building. The characteristics of the typhoon-generated wind including turbulence intensity, gust factor, turbulence integral length scale and power spectral density of fluctuating wind speed were analyzed. The dynamic characteristics of the buildings were determined from the field measurements and comparison with those calculated from the computational model of the building was made. The measured natural frequencies of the two fundamental sway modes of the building were found to be larger than those calculated. The damping ratios of the building were evaluated by random decrement technique, which demonstrated obvious amplitude-dependent characteristics and increased with increasing amplitude of the building during Typhoon Pabuk.
A Stiff Test Facility for Obtaining Controlled Shear Failure of Reinforced Concrete Beams
Authors: Lv Yan Mei , Yi Wei Jian
Published: March 2009

An energy absorbing stiff test facility has been developed for obtaining stable and controlled shear failure of reinforced concrete beams. Using two hydraulic jack and a cross steel beam to act as the stiffener and energy absorbing elements, test facility allows the monitoring of the complete curve of load versus mid-span deflection (including the post-peak region) of shear critical beams. To prove the feasibility of this test facility, the stiff test facility was measured when test facility were loaded up and down. Then, the shear failure experiments of 4 full size reinforced concrete beams were processed. The results indicate that the post-peak branch of the load versus mid-span deflection of the shear-critical reinforced concrete beams without web reinforcement was steeper than that of beams with web reinforcement and hence the stiff test facility was more stable for beams with web reinforcement.
Dispersion of Carbon Nanotubes in Polysilazanes for the Preparation of Reinforced Si-C-N Composites
Authors: Fernandez L. , Li Y. , Burghard M. , Burghard Z. , Gerstel P. , Bill Joachim , Aldinger Fritz
Published: March 2009

The present contribution reports two different approaches to achieve a good dispersion of single-walled carbon nanotubes (SWCNTs) in a precursor-derived Si-C-N matrix, which represents an important prerequisite for attaining a high-performance material. The first approach involves the use of SWCNTs covalently functionalized by disilazane groups, aiming at enhanced interfacial interaction between the nanotube surface and the matrix. Within the second approach, the effect of an electrical field applied in the cross-linking step during the nanocomposite synthesis was studied toward the task of dispersing and simultaneously aligning the SWCNTs in the Si-C-N matrix.
Influence of Lightweight Aggregate on Durability of High Performance Concrete
Authors: Zhang Bao Sheng , Kong Li Juan , Ge Yong
Published: March 2009

High performance concrete (HPC) with a water/cement ratio (w/c) of 0.32 and different lightweight aggregate (LWA) contents (0%, 25%, 50%, 75%, 100%) were prepared, and the influence of LWA on concrete frost-resistance and impermeability at different ages were studied, as well as the hydration degree, hydrated product, pattern and pore structure of the paste around aggregate. The results show that, by replacing normal weight aggregate (NWA) with 50% and 100% volume contents of pre-wetted LWA respectively, the chemical bound water of the cement paste surrounding aggregate are increased 12.1% and 22.7% as compared to concrete mixed without LWA. And at 28 days, lightweight aggregate concrete has the highest Ca(OH)2 content, whereas the 90-day Ca(OH)2 content of normal weight concrete is the highest. This proves that, with the increase of LWA content in concrete, both of the internal curing effect of pre-wetted LWA and secondary hydration effect of fly ash (FA) are strengthened, this can also be verified by the SEM study. Furthermore, the pore structure of the cement paste around aggregate can be improved consequently. The performance of frost-resistance of HPC can be improved by mixing LWA, the 90 day-frost-resistance of lightweight aggregate concrete is about 2.5 times of that of concrete mixed without LWA. The influence of LWA on the impermeability of HPC is different from normal concrete. When LWA content is more than 50%, the HPC impermeability decreased obviously, however at later age the difference between them becomes minor.
Effects of Limestone Powder in Manufactured Fine Aggregate on Early Hydration Process and Types of Cement Hydrates
Authors: Cai Ji Wei , Zhang Shao Bo , Zhou Ming Kai , Li Bei Xing
Published: March 2009

The crusher dust in Manufactured fine aggregate (MFA), e.g. limestone powder in calcareous MFA, constitutes micro gradation of the aggregate and suitable content of crusher dust in MFA can improve the properties of concretes. In this paper, early hydration processes of samples substituting limestone powder and fly ash for part of cement are analyzed, and effects of limestone powder on cement hydrates are studied through experiment of mortar prepared with MFA partially replaced by limestone powder and fly ash. The result reveals that both the dormant period and acceleration period of hydration ended earlier in the samples substituting limestone powder for part of cement, and amount of crystals of calcium hydroxide and hydrated calcium carboaluminate increases in hardened paste in the samples substituting limestone powder for part of MFA, i.e. calcareous dust (limestone powder) in MFA can stimulate and enhance hydration of cement.
Fabrication of Si Nitride Coating onto Metal Substrate by Reactive RF Plasma Spraying
Authors: Yamada Motohiro , Fukumoto Masahiro , Yasui Toshiaki
Published: March 2009

Si 3N 4 thick coating was fabricated by reactive RF plasma spraying, in which elemental Si reacted with surrounding nitrogen plasma. It was possible to fabricate the Si 3N 4 coating by reactive spraying on a graphite substrate. As for the substrate, however, graphite is difficult to apply to the practical structural parts because of its low mechanical strength. Thus, it was necessary to realize Si 3N 4 coating onto the metal substrate. In this research, Ti alloy, carbon steel and Ni alloy were used as the metal substrates. Ti alloy was difficult to apply to the formation of Si 3N 4 coating because the preferential reaction of Ti-N prevented the nitriding reaction of Si-N. On the carbon steel substrate, pure Si coating was fabricated. However, nitriding reaction was difficult to occur on this substrate
because the melting point of carbon steel was lower than the reaction temperature of Si-N. Ni alloy, one of the useful heat-resistant alloys, was also tried as the substrate. Finally, the feasibility of some kinds of interlayer between Si 3N 4 and steel substrate was clarified to improve the bonding property between Si 3N 4 and metal substrate.
Effect of Electric Current and Sliding Speed on Wear Rate of Metallized Carbon Strip Sliding against Copper Trolley
Authors: Kim H.J. , Lee J.K. , Jeong E.Y. , Bae Jung Chan , Huh Moo Young
Published: March 2009

Pure copper and copper alloy infiltrated carbon materials were newly developed for the application of the contact strip on the pantograph system of high-speed electric railway. After the compaction and following baking process at an elevated temperature, the shape and size of pores in carbon materials were controlled by the processes developed in this work. The infiltration of pure copper or copper silicon alloy was performed in a specially designed chamber equipped with an evacuation system by a diffusion pump and also a pressurizing system by a high pressure gas. In order to evaluate the performance of metallized carbon strip samples, the wear tests were performed in a wear testing machine which was designed for an actual operating condition for the high-speed electric railway. Wear properties of samples were discussed by tacking various wear testing data.
Texture and Microstructure of the Austenite in Multiphased Steel Sheets
Authors: Réglé Hélène , Maruyama Naoki , Yoshinaga Naoki
Published: March 2009

In this paper we present results obtained in collaboration between NSC and Arcelor on the austenite of a multiphased steel and on a 70%Ni-30Fe alloy. The work concerns the formation of the crystallographic textures during the recrystallisation of austenite, since these textures have a strong influence, after the phase transformation, on the forming properties of the sheets. The microstructure and the textures of the austenite and the FeNi alloy were measured with X-Ray diffraction techniques and with EBSD on a high resolution FEG-SEM.
Experimental Energetic Balance Associated to the Deformation of an Aluminum Multicrystal and Monocrystal Sheet
Authors: Louche Herve , Tabourot Laurent
Published: March 2009

This paper presents a method to estimate the stored energy during the tensile deformation of an aluminum multicrystal and polycrystal sheet sample. The method is based on thermo mechanical macroscopic fields analysis, like strains and temperature, obtained by a visible and an infrared cameras. Preliminary experimental results are presented. On an Al multicrystal sheet, heterogeneous thermo mechanical fields associated to the localized movement of dislocations at a
microscopic scale are presented. Furthermore, the energetic balance established during the tensile deformation of an Al polycristal show a decreasing ratio of stored energy on anelastic energy and a non constant fraction of total work converted into heat.
Application of the Repere Diffraction to Study Special Grain Boundaries in Recrystallized Metal
Authors: Slavov V.I. , Naumova O.M. , Kostylev S.N. , Puchkov A.V.
Published: March 2009

At present there is no understanding referring to the full picture of processes, that take place in the structure formation and improvement of required level of physical-mechanical properties for IF steel. That is why this paper is devoted to investigations of the texture and the quantity of the special grain boundaries to enable IF steel to high drawability.
The Formation of New Orientations during Recrystallization of Silver Single Crystals with {112}<111> Initial Orientation
Authors: Paul Henryk , Driver Julian H. , Maurice Claire , Piątkowski Andrzej
Published: March 2009

The recrystallization mechanisms in high purity Ag crystals with C{112}<111> initial orientation, deformed by channel-die compression, have been studied by local orientation measurements using TEM and SEM/EBSD. The microtexture analysis clearly indicates the importance of a simple relation of 25-40o (<111> or <112>) type, which is frequently observed during the early stages of recrystallization between isolated nuclei of uniform orientation and one of the as-deformed groups of components. As recrystallization proceeds, recrystallization twinning increases radically. In C-oriented silver single crystals this latter mechanism also plays a decisive role in the formation of the cube orientation.
Thermomechanical Behavior of Rapidly Solidified Fe-25Cr-20Ni
Authors: Draissia M. , Boukhris N. , Debili M.Y.
Published: March 2009

The thermomechanical treatment at 1050°C under a stress of about 30 MPa, of milled ribbons from Fe-25Cr-20Ni (0.060%Ni-0.1%Ti) refractory stainless steel, leads to a recrystallisation of the as-melt-spun structure which is intermediate between cellular and columnar dendritic. The mean grain size in the relatively high density zones (85%) may be considered as low and do not exceed 10µm. Other grains appear abnormally large and reach 30µm. The origin of these grains, must be researched in an exaggerate growth phenomenon under a local deformation near the critical work hardening.
Static Recrystallization of Ti-IF Steel after Warm Deformation
Authors: Ebrahimi R. , Oudin A. , Najafi-Zadeh A. , Barnett Matthew R. , Hodgson Peter D.
Published: March 2009

The present work examines the effect of strain and Zener Hollomon parameter, Z, on deformation and recrystallization of Ti-IF steel deformed in the warm temperature region. Torsion tests were performed at temperatures of 765oC and 850oC and strain rates of 0.003s-1 and 1s-1. For some conditions, an annealing treatment at the temperature of deformation was carried out using a fluidized bed furnace. Electron Back Scatter Diffraction (EBSD) maps were implemented to study the microstructure evolution. At a low value of Z abnormally large grains formed during annealing. At the higher values of Z, a more classical recrystallization reaction occurred during annealing. The latter is more desirable in most commercial applications.
Estimation of Stored Energy Distribution from EBSD Measurements
Authors: Gerber Ph. , Baudin Thierry , Jakani S. , Mathon Marie Helene , Bacroix Brigitte
Published: March 2009

Wire-drawn copper has been investigated with Electron Back Scattered Diffraction technique in a Scanning Electron Microscope after deformation by wire-drawing. In this paper, we show how to get qualitative informations about the deformation inhomogeneities related to the stored energy distribution, from the analysis of the quality index. Furthermore, the microstructural analysis in the wire diameter is completed using the quality index distribution approach. A relation between diameter of the wire and stored energy distribution is then qualitatively set. In order to validate the proposed method, the EBSD data are compared with the stored energy values obtained from neutron diffraction measurements.
Simulating the Topology of Recrystallization in Stabilized Ferritic Stainless Steels
Authors: Sinclair Chad W. , Weygand D. , Lépinoux J. , Bréchet Yves
Published: March 2009

The observation of inhomogeneous, ‘sluggish’ recrystallization in ferritic steels has been extensively documented and discussed, particularly with reference to low carbon steels. Stabilized ferritic stainless steels are also prone to this phenomenon and, in many cases, exhibit the effect more strongly than their carbon counterparts. The situation for stainless steels is exacerbated in part by the topology of the cold rolled microstructure, which is composed of highly elongated and layered grains. In this work an attempt has been made to probe the key features of this process by means of a two-dimensional vertex simulation. Key microstructural characteristics such as subgrain and grain size, topology, misorientation and energy are varied in these simulations in an attempt to elucidate the mechanisms responsible for the final recrystallization. These simulations are compared and contrasted with experimental observations from the recrystallization of an AISI409 stainless steel.
Development of New Multi-Dimension Squeezed Penetration Piling Machine
Authors: Huang S.Q. , Han Y.M. , Wang Yu Dong
Published: March 2009

The features of a newly developed multi-dimension squeezed penetration piling machine are presented in this paper. The simulation model is built and the squeezing mechanism is tested under simulation environment. With the simulation method key design parameters are predicted at the early design stage; the development cycle can be shortened; and the product quality can be improved.
Application of Hybrid Fuzzy PID Control to Auxiliary Workpiece Table
Authors: Zhang Da Wei , Tian Yan Ling , Yan Bing
Published: March 2009

In order to eliminate the non-linearity of a grinding auxiliary workpiece table, a hybrid
fuzzy PID controller has been developed. The two-dimensional fuzzy control with self-tuning factor is utilized to improve the performance. The Max-Min inference mechanism and COG defuzzification method are used to obtain the crisp output of the fuzzy controller. To eliminate the oscillation at balance position, the conventional PID controller is used in the small range of the error and the switch between two controllers can automatically realize according the preset value. Simulation and
experimental testing have been carried out to validate the performance of the hybrid fuzzy PID controller.
Discontinuous Creep Behaviour of 15Mo3 Type Steel
Authors: Szabó Péter János
Published: March 2009

15Mo3 type steel samples were subjected to creep loading at 550°C in order to
investigate the development of microstructure as well as the effect of the carbides. It was found that after reaching the secondary creep region, the slope of the creep curve decreased, the creep rate reached a minimum value and remained unchanged as the effect of strainhardening is counterbalanced by an annealing influence. After a short plateau, the slope increased. In order to explain this type of behaviour and to suggest a damage mechanism, TEM and EBSD investigations were performed. At the beginning of the process, subgrain formation started which was retarded by the carbides. At elevated temperature, however, the average distance between carbides increased, and the pinned dislocations were able to bypass them, the internal strain inside the grains (after reaching a maximum value after about 481 hours) decreased, and the creep process accelerated.
Application of WFS for Simultaneous Work Function and Secondary Electron Emission Measurement on Ba Covered Tungsten
Authors: Vida György , Beck Ildikó , Josepovits V. Katalin , Győr Miklós
Published: March 2009

In the present paper the secondary emission and work function of W covered with different thickness Ba layers are compared. The secondary emission and work function were measured by Work Function Spectroscopy (WFS). It is clearly pointed out that the thin Ba coating causes the the enhancement of electron induced secondary electron emission. In high pressure discharge lamps high secondary emission and high thermionic current are required for reliable operating conditions,
i.e., for reaching the nominal burning voltage and current etc. The results prove that the Ba spreading on the W surface from an alkali earth tungstate material is advantageous for lowering the work function and, simultaneously, for increasing the secondary emission yield.
Dynamic Rheological Behaviors of the Bone Scaffold Reinforced by Chitin Fibres
Authors: Li X.M. , Feng Qing Ling
Published: March 2009

In this study, a novel bioabsorbable porous bone scaffold reinforced by chitin fibres was prepared, the porosity of which is about 90 % and the pore size is approximately 200µm. The Advanced Rheological Enlarged System (ARES) was used to study the dynamic rheological behaviors of the ropy materials which would be made into the reinforced scaffold. The increase of the fibres’ volume content (Cf) enhanced the complex modulus (G*) and complex viscosity (h*) of the materials, the reason of which is that the fibres formed networks in the materials. When Cf increased from 35 % to 45 %, the storage modulus (G’) and loss modulus (G’’) curve showed obvious yielding behavior, which indicates that G’ and G’’ of the materials are hardly variable in a wide range. When Cf was more than 35 %, the loss factor (tand) was obviously lower than 1 and the materials exhibited viscoelastic properties, which result in a disadvantage for materials’ processing.
Solid-State Synthesis of Magnesium Silicide via Repeated Plastic Working and Spark Plasma Sintering
Authors: Oginuma Hideki , Kondoh Katsuyoshi , Yamaguchi Takashi , Yuasa Eiji
Published: March 2009

In this study, the solid-state reaction to form Mg2Si bulky materials via spark plasma
sintering (SPS) process was discussed. Elemental powder mixture of Mg-33.33mol%Si was refined and consolidated as green compacts by repeated plastic working (RPW) SPS was performed to synthesize and sinter magnesium silicide at 1100K from the RPWed compact. The only peaks of Mg2Si, not Mg and Si, were detected by X-ray diffraction analysis. Mg2Si bulky intermetallic began to shrink above 800K during SPS process, and its densification significantly occurred. The density of SPSed Mg2Si bulk material is about 100% of the theoretically relative one.
Assessment of Surface Damage in Thermally Aged FSX414 Cobalt-Based Superalloy Using Ultrasonic Rayleigh Wave
Authors: Byeon Jai Won , Kim C.S. , Kim Y.H. , Kwun S.I. , Hong S.J.
Published: March 2009

An attempt was made to assess the surface damage in the isothermally degraded
FSX414 Co-based superalloy using ultrasonic Rayleigh surface wave. Microstructural analysis (amount of solute Cr near the surface) and measurement of ultrasonic velocity and attenuation were performed after isothermal degradation heat treatment at 1100°C for up to 4000 hours. Rayleigh wave velocity was observed to increase with aging time, which was attributed to the increased
depletion of Cr near the surface. Strong frequency dependence of Rayleigh wave velocity was found in the specimens with surface depletion layer. Attenuation coefficient of Rayleigh wave increased with increasing aging time. Therefore, both attenuation and velocity of ultrasonic Rayleigh wave are suggested as potential nondestructive evaluation parameters for the characterization of the thermally aged FSX414 superalloy.
Physico-Chemical Properties and Performance of Novel PEEK-WC Membranes Contacting Human Plasma and Proteins
Authors: De Bartolo L. , Gugliuzza A. , Morelli S. , Cirillo B. , Gordano A. , Drioli Enrico
Published: March 2009

The aim of this work was the exploration of a potential biocompatible membrane prepared from a modified polyetheretherketone (PEEK-WC). The physico-chemical properties of PEEK-WC were characterised by Differential Scanning Calorimetry and FT-Infrared Spectroscopy. The surface affinity of this membrane to human plasma and proteins such as albumin, fibrinogen and immunoglobulins G was evaluated and compared with that of commercial membranes. The wettability of all investigated membranes was established by water contact angle measurements. PEEK-WC membranes exhibited moderate wettability and low protein adsorption, differently from other commercial membranes such as cellulose acetate membrane. A preferential adsorption of hydrophilic proteins as albumin on the membrane surfaces was observed. Human plasma adsorption on membranes followed the same trend as individual protein solutions.
Formation of Zn-ZnO Polygon Prismatic Nanocrystals by Liquid Source via Thermal Vapor Transport
Authors: Liu Kun-Ho , Lin Chin-Ching , Chen San-Yuan
Published: March 2009

A novel hierarchical polygon prismatic nanostructure of wurtzite Zn has been grown on silicon by liquid-solution seed nucleation and vapor-gas growth method. The Zn(ClO4)2 colloidal sol with various concentrations was used as seeds to control the dimension of Zn crystals from the nanometer (30 nm) to micrometer scale (2 µm). Depending on heat-treatment temperature, different morphology was developed. In the temperature range of 200-300oC, a compact polygon prismatic Zn structure was formed. However, in a high temperature range of 300-400oC, polygon prismatic Zn with hollow structure was observed. After oxidation treatment, the ZnO surface layer can be developed on the Zn nanocrystals to form ZnO-Zn core-shell structure as evidenced from PL measurement. These formed ZnO-Zn nano- and micro-crystals can be further used as building blocks to assemble two- or three-dimensional photonic crystals. PACS codes: 81.10.Aj, 64.70.Fx, 64.72.-y
Novel Approach to Preparation of InP Layers for Radiation Detectors
Authors: Prochazková Olga , Zavadil J. , Zdanský K. , Grym J.
Published: March 2009

The preparation and characterization of thick InP layers by Liquid Phase Epitaxy with admixture of Ce, Tb, Dy and Yb in the growth melt is reported. Measurement of temperature dependent Hall affect, C-V characteristics and low-temperature photoluminescence show the change of n®p type conductivity and considerable improvement of structural and electro-optical parameters for all studied rare-earth elements. Mn was identified as dominant acceptor impurity in the case of Tb and Dy addition. In the case of Ce and Yb the dominant acceptor was identified as isoelectronic Ce or Yb on the In site subjected to a strong electron-lattice interaction. The reported high quality thick p-type InP layers could well be used for the preparation of radiation detector structures.
Influence of Irradiation on Excess Currents in SiC pn Structures
Authors: Strel'chuk Anatoly M. , Kozlovski Vitalii V. , Lebedev Alexander A. , Smirnova N.Yu.
Published: March 2009

Excess currents of the different nature in 6H-SiC pn structures of the different origin and parameters were investigated. The effect of the suppression of the forward and reverse excess currents were observed after 0.9 MeV electron (dose 5x1016 ÷ 1.6x1017 cm-2) and 8 MeV proton (dose 5x1015 cm-2) irradiation for structures with shunts which is probably due to the presence of relatively small
inhomogeneities. The shunts in another group of pn structures probably are more high capability and they are more stable against degradation during irradiation.
Field Effect Mobility in n-Channel Si Face 4H-SiC MOSFET with Gate Oxide Grown on Aluminium Ion-Implanted Material
Authors: Gudjónsson G. , Ólafsson H.Ö. , Allerstam Fredrik , Nilsson Per Åke , Sveinbjörnsson E.Ö. , Rödle T. , Jos R.
Published: March 2009

We report investigations of Si face 4H-SiC MOSFETs with aluminum ion
implanted gate channels. High quality SiO2/SiC interface is obtained both when the gate oxide is grown on p-type epitaxial material and when grown on ion implanted regions. A peak field effect mobility of 170 cm2/Vs is extracted from transistors with epitaxially grown channel region of doping 5x1015 cm-3. Transistors with implanted gate channels with aluminum concentration of 1x1017 cm-3 exhibit peak field effect mobility of 108 cm2/Vs, while the mobility is 62 cm2/Vs for aluminum concentration of 5x1017 cm-3. The mobility reduction with increasing acceptor density follows the same functional relationship as in n-channel Si MOSFETs.
Brazing Al2O3 to Kovar Alloy with Ni/Ti/Ni Interlayer and Dramatic Increasing of Joint Strength after Thermal Cycles
Authors: Qiao Guan Jun , Wang Hong Jie , Gao Ji Qiang , Jin Zhi Hao
Published: March 2009

High purity alumina ceramic and Kovar alloy were brazed by Nickel and Titanium foils
stacked as Ni/Ti/Ni layer structure. Airtight joints were achieved with shear strength more than 30MPa, after brazing at 995oC for 30min. A sandwich structure was observed in solder, which means an a-Ti solid solution belt at mid part and Ti2Ni intermetallics belts at both sides. The main reaction product at alumina/solder interface was Ni2Ti4O, a complex oxide with structure similar to Ti2Ni, which is the bonding agent and transition from the solder’s metallic crystal lattice to alumina
crystal lattice. To simulate the actual serving conditions, a thermal cyclic experiment was undertaken at the 200oC-600oC temperature range. The results showed that shear strength of joint increased dramatically after thermal cycles. This interesting phenomenon is attributed to the annealing effects of thermal cycles, which released residual stress in brazed joints remarkably.
Interaction between Ti-6%Al-4%V Alloys and Hardmetals Coated by Cathodic-Arc Technology
Authors: Moreno C.M. , Artola G. , Sanchez J.M.
Published: March 2009

At present, milling of titanium based alloys for aerospace applications is mainly carried out with un-coated WC-Co carbide tools. The present work evaluates the chemical interaction of the Ti-6%Al-4%V alloy with these WC-Co commercial hardmetals. Strong decarburation induced by carbon diffusion to the Ti based alloy is observed at temperatures ranging from 750-1000°C. This reaction is responsible for the high adhesion found at the alloy-carbide interface. Different cathodic arc coatings have proved efficient in inhibiting such reaction and the associated adhesion to the Ti-6%Al-4%V alloy. Delamination induced by reaction between the Ti6Al4V alloy and AlTiN and TiAlCN coatings increases with the hot pressing temperature, being more severe for the AlTiN material. A lower bound of 44 J/m2 has been obtained for the interfacial fracture energy of cathodic arc PVD TiAlCN coatings on hardmetal substrates, this value being significantly higher than those previously reported for TiAlN materials.
The Propagation Characteristic of Viscous-Plastic Wave in Functionally Graded Layer
Authors: Liu Li Sheng , Zhang Qing Jie , Zhai Peng Cheng , Zhu Chang Chu
Published: March 2009

In the paper, propagation of two-dimensional viscous-plastic waves in graded layer media is investigated by numerical method. Firstly, an infinite model is used to analysis wave’s propagation in FGMs, this model has a finite gradient layer and non-reflecting boundary condition is used to simplify the model to be finite. Then the characteristic of viscous-plastic wave’s propagation in graded media is investigated on the base of this model. The following contents is researched by this
model: (1) The refracted effect of functionally gradient layers on incident wave; (2) the effect of incident angle on the bottom layer’s stress ; (3) the effect of gradient layer’s thickness on the bottom layer’s stress. Finally, some interesting, reasonable and important results are obtained by our researching work.
Dynamic Voltage-Current Characteristics of Unipolar Pulse Glow Discharge
Authors: Popović I. , Rajović V. , Zlatanović M.
Published: March 2009

Introduction of pulse plasma power supply is one of the major contributions to plasma
surface engineering. The voltage and current waveforms of nitrogen and nitrogen/hydrogen glow discharges in the vacuum total pressure range from 0.1 to 15 mbar were recorded and analyzed concerning the shape, typical operating values and the influence of surface treatment process parameters. It was found that the waveform shape of the voltage and current contains information on pulse generator output parameters and vacuum system properties during normal glow, hollow cathode discharge and arcing. We have also performed the scoping of dynamic parameters and static characteristic, in order to obtain information for the generator and chamber modeling, to be used in a future plasma materials treatment processes control. The influence of process parameters such as total pressure, cathode temperature and biasing voltage on current-voltage characteristics was also considered.
Synthesis, Structure and Properties of Iron-Based Bulk Glass-Forming Metallic Alloys Prepared by Different Processing
Authors: Mitrović N. , Roth Stefan , Degmová J. , Stoica M. , Eckert Jürgen
Published: March 2009

This article deals with the materials science and engineering of glass-forming alloys in Fe-(Nb)-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Ga)-(P, C, B) and Fe-(Co, Ni)-(Cu)-(Zr, Nb)-B bulk metallic glasses (BMG) systems with high thermal stability of the undercooled melt against crystallization. Different liquid quenching techniques (melt-spinning or copper-mold casting) as well as hot pressing of the powder obtained by milling of the melt-spun ribbons were used to prepare samples in various shapes. Synthesis of the investigated BMG alloys is discussed according to Inoue’s empirical components rules for the achievement of the large glass forming ability (GFA). Thermal and microstructure characterization (performed by DSC, TMA, XRD and Mössbauer spectroscopy) was used to correlate GFA, microstructure and thermo/thermo-magnetic treatments with optimum soft magnetic properties.
Scaling of Network Segment Dimensions in Hyperelastic Composites
Authors: Plavšić M.B. , Pajić-Lijaković Iva , Lazić N.L.
Published: March 2009

The change in elastomer tensile moduli, as formulated in the Gaussian statistical theory of rubber elasticity, with deformation, is considered both experimentally and theoretically. Gum elastomers of different structures and corresponding materials filled with carbon black, as reinforcing filler, are investigated experimentally. For all materials considered, the same scaling pattern with negative and low slope for small deformations, and positive and higher slope for large deformations is obtained, indicating two distinct mechanisms of elastic response. Most pronounced is the similarity of small deformation responses for filled materials. Considering the modulus as an elastic energy density gradient dependent on structure changes with deformation, and interpreting the changes for small deformations in terms of conformational energy change, the fractal dimension of a new type is formulated. It describes the decrease in elastomer network connectivity with deformations, which is discussed in terms of conformon dynamics. Possibilities of application of Faynman's path integral method and statistical method of random walk to the lattice are considered for the conformon, as well.
Residual Stress Analysis of Microwave Plasma CVD Diamond Films
Authors: Chen Leng , Mao Wei Min , Lu Fan Xiu , Yang Ping
Published: March 2009

The residual stress and crystallographic texture of diamond films were investigated in the present work. The diamond films were synthesized on (100) silicon wafer by Microwave Plasma Chemical Vapor deposition (MPCVD). Then the residual stresses of the films were measured by X-ray diffractometer equipped with the two-dimensional detector. The residual stresses can be classified into two categories, i.e., the intrinsic stresses and the thermal stresses. It was shown that the thermal stresses were compressive in the temperature range studied and the intrinsic stresses were tensile. The crystallographic textures of the films were measured by X-ray diffractometer with the method of pole figure and orientation distribution function (ODF). The experimental results suggest that the crystallographic textures of the films depend upon the deposition temperature and methane flow rates, and the components and intensity of crystallographic textures have effect on the residual stresses in diamond films to a certain extent.
The Texture Effect on Diffusion Barrier Property on TiN Films between Copper and Si Wafer
Authors: Sung Dong Young , Kim In Soo , Lee Min Gu , Park No Jin , Yang Bee Lyong , Yang Jun Mo , Ko Jung Kyu
Published: March 2009

TiN thin films are widely used as a coating material due to their good mechanical and
conductivity properties, high thermal properties, strong erosion and corrosion resistance. Also TiN has been used in Si devices as a diffusion barrier material for Al and Cu-based metallization. The uniform and dense structure of thin films is influenced by the texture of films. It was good to have uniform and dense structure and bad to have an open columnar structure in TiN thin films. Therefore, the property of diffusion barrier of the TiN films in semiconductor also is related to the texture and microstructure of TiN coated layer. In this study, the relationship between the texture and microstructure and the best diffusion barrier propertiy of TiN coated films (by PVD and MOCVD) on semiconductor devices (Cu/TiN/SiO2/Si layer) were investigated under different processing conditions and textures. The property of diffusion barrier for Cu of physical vapor deposited TiN thin films is better than that of metal organic chemical vapor deposited TiN thin films. Also the property of diffusion barrier for Cu of (111) textured TiN thin films is better than that of (200) textured TiN thin films.
Grain Boundary Nature and Localized Corrosion in 304 Austenitic Stainless Steel
Authors: Samajdar I. , Ahmedavadi P. , Wasnik D.N. , Kain Vivekanand , Verlinden Bert , Dey P.K.
Published: March 2009

The present study had one broad objective – to systematically characterize effects of overall grain boundary nature on localized corrosion, intergranular corrosion (IGC) and stress corrosion cracking (IGSCC), of type 304 (UNS S 30400) austenitic stainless steel. Various combinations of cold rolling and solution annealing, were applied to alter relative the relative concentrations of ‘special’ or low CSL boundaries and to relate them with the local corrosion resistance, IGC and IGSCC, after respective sensitization treatments. It has been shown that both extreme high and low concentration of random (or high energy) boundaries can provide an effective means of control for localized corrosion, degree of sensitization (DOS), IGC and IGSCC, - the improvement in localized corrosion resistance at extreme grain boundary randomization being more effective.
Texture Segregation and Texture Change in the Biaxial Stretching of AA6016
Authors: Bate Pete S. , Moore M. , Court S.A.
Published: March 2009

Sheets of the Al-Mg-Si alloy AA6016 have been prepared with different microstructures by rolling and annealing, followed by heat treatment to the T4 condition. These have been biaxially stretched using the Marciniak driving blank method, and their limit strains measured. Such biaxial stretching limits are very sensitive to inhomogeneity with length scales greater than about half the sheet thickness, and significant factors in that inhomogeneity are the materials grain size and the spatial segregation of texture. In this material, it appears that colonies of cube textured grains have an effect on the limit strains. However, there is significant change of texture during stretching and this texture evolution also needs to be considered. Finite element modelling has been used to evaluate the effects of grain size, clustering of the initial texture and texture evolution on the biaxial stretching limits.
Phase Transformation Textures in Ti-6Al-4V Alloy
Authors: Vogel Sven C. , Bhattacharyya D. , Viswanathan G.B. , Williams D.J. , Fraser H.L.
Published: March 2009

Titanium alloys are widely used in various industrial, domestic, and medical applications such as turbine blades, bicycle frames, knee implants, etc. The two-phase titanium alloy Ti-6Al-4V (wt. percent) is considered to be a workhorse alloy for many applications in these diverse fields. Despite the large body of work on this alloy, the question of the transformation mechanism from the hcp a to the bcc b phase, occurring on heating to temperatures above the a/b transus at ~980°C, is
still unresolved. Due to experimental difficulties, it has not yet been clearly determined whether the increase in b volume fraction occurs by fresh nucleation of b crystals within a phase grains or the growth of preexisting b grains. Since the Burgers orientation relationship holds only if the b grains are nucleated within the a grains, the outcome of this question greatly affects texture-modeling efforts for this system. The Burgers orientation relationship predicts that the {0001} crystal direction in a grain of the a phase becomes a {110} crystal direction in a grain of the b phase after the transformation. In this work we present experimental results from in-situ texture measurements performed on the HIPPO neutron diffractometer at LANSCE. Using the combination of time-offlight neutrons and full-pattern Rietveld analysis allowed us to determine the orientation distribution functions of both phases at room temperature, 800°C, 1020°C and again at room temperature. We found strong indications that the b phase indeed grows from grains preexisting at room temperature. Upon re-transformation from b to a we found that the Burgers relationship is followed.
Dynamic Recrystallization of Torsion Deformed NiAl
Authors: Klöden Burghardt , Skrotzki Werner , Oertel C.G. , Rybacki E.
Published: March 2009

Polycrystalline samples of NiAl have been deformed in torsion in the temperature range 800K – 1300K. Deformation is accompanied by dynamic recrystallization, which with increasing temperature changes from continuous to discontinuous mode. Emphasis was put on the occurrence of continuous dynamic recrystallization, which will be discussed with respect to texture and microstructure.
The Role of Microstructural Aspects on the Performance of Coarse-Grained Superplastic Al Alloys
Authors: Chezan A.R. , de Hosson Jeff T.M.
Published: March 2009

Deformed under optimum conditions of temperature and strain rate, coarse-grained
aluminum alloys show elongation to failure in excess of 300%. The strain rate sensitivity index and the activation energy point to solute drag creep as the principal mechanism, a mechanism that has virtually no grain size dependence. The present study summarizes microstructural effects that are grain size dependent and which can influence the values of the maximum tensile elongation that can be obtained in coarse-grained aluminum alloys. Such effects like inhomogeneous refinement of the
microstructure accompanied by the increase of the ratio of low/high angle grain boundaries and that of the texture contributes to flow stress instabilities leading to necking and premature failure.
Sintering Behavior of NbC-Reinforced Steel
Authors: Paulo Domingos S. , Martinelli Antonio Eduardo , Alves Jr. Clodomiro , Echude-Silva Jorge H. , Távora Michelle P. , Nascimento Rubens Maribondo
Published: March 2009

Powdered steel reinforced by NbC dispersed particles was sintered both in resistive furnace at 1180°C or in plasma reactor at 850°C (reference temperature) using heating rates that ranged from 10 to 100°C/min. Fe3P was used as liquid phase sintering additive. The microstructure of the resulting materials was visualized by scanning electronic microscopy. Distinctive microstructural features were observed as a function of the heating source and heating rate. Plasma sintering at rates ~ 30°C/min revealed different microstructural features comparing edge and sample bulk. Homogeneous mixtures of Fe and NbC could be sintered in resistive furnace and plasma reactor using relatively low heating rates. Plasma sintering at 800°C for 1 h (heating rate of 10°C/min) resulted in relative densities of ~ 91% of the theoretical density of the composite. Sintering in resistive furnace for 1150°C resulted in relative densities ~ 94%.
Influence of Mg on the Structural and Optical Properties of LiNbO3 Thin Films Grown by Polymeric Precursor Method
Authors: Simões A.Z. , Bouquet V. , Moura F. , Ries A. , Zaghete M.A. , Varela José Arana
Published: March 2009

A polymeric precursor solution was used to deposit pure and Mg doped LiNbO3 thin films on sapphire substrates by spin-coating. The effects of magnesium addition on crystallinity, morphology and optical properties of the annealed films were investigated. X-ray diffraction patterns indicate the oriented growth of the films. Phi-scan diffraction evidenced the epitaxial growth with two in-plane variants. AFM studies show that the films are very homogeneous, dense and present smooth surfaces. The refractive index and optical losses obtained by the prism coupling method were influenced by the magnesium addition.