bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation on Adiabatic Shearing Behavior of Vanadium Alloy V-5Cr-5Ti Hat-Shaped Specimen
Authors: Yan Yi Xia , Huang Xi Cheng , Hu Wen Jun
Published: June 2010

In this work, LS-DYNA program was adopted to simulate the loading process of Vanadium Alloy specimen conducted on the Split Hopkinson Pressure Bar (SHPB) in two dimensions. Based on the Johnson-Cook material constitutive relation and criterion of Johnson-Cook failure, the initiation, propagation process of an adiabatic shear band (ASB) and the corresponding distribution of temperature field in the vanadium alloy V-5Cr-5Ti hat-shaped specimen are analyzed. The field of stress, strain and temperature in the tip of an ASB, and the spread speed, the width as well as the type of the ASB are all studied. It is shown that the formation of the ASB is related to the loading velocity and the size of the hat-shaped specimen. And formation of mircocracks and their interlinkage are primary shearing failure mechanism of hat-shaped specimen.
Advances on Modelling of the Tool/Workpiece Interface during High Shear Processing
Authors: Krzyzanowski Michal , Rainforth W. Mark
Published: June 2010

Understanding and prediction of physical phenomena in different scales at the same time that are taking place at the tool/workpiece interface during high shear processing is done in different ways combining the latest finite element (FE) and discrete element (DE) analysis technology. The high shear processing is observed during hot rolling of aluminium, when it produces a highly deformed subsurface layer; and also during friction stir welding (FSW), when it results in significant heat generation and flow. The FE analysis is used for macro-scale simulation while the DE method is applied to simulate meso-scale phenomena taking place in the thin, sometimes a few micron thicknesses, surface layer. Different FE models and numerical techniques combined with DE based transient dynamics approaches are discussed in this work.
Modeling Corrosion of a Metal under an Aerosol Droplet
Authors: Venkatraman Murali Sankar , Cole Ivan S. , Gunasegaram Dayalan R. , Emmanuel Bosco
Published: June 2010

On a metal surface covered with a moisture layer of variable thickness and shape, the dissolved oxygen may induce a spatial separation of the anodic and cathodic reactions on space-time scales characteristic of the roughness, droplet size and the local kinetics of the system. This leads to a spatio-temporal variations in species concentrations, current and potential over the metal surface and thus atmospheric corrosion. Here a fully three-dimensional transient model is developed that addresses the corrosion of a metal under an aerosol droplet. The effects of various parameters, such as exchange current densities, initial concentrations, shape and size of the droplet, and diffusivity of oxygen on ionic, potential and current distributions are investigated.
Theoretical Study of Growth Mechanism of Goethite in the Presence of Surfactants
Authors: Yue Jeffrey , Jiang Xu Chuan , Yu Ai Bing
Published: June 2010

Goethite (α-FeOOH) nanorods could be prepared by a surfactant directed approach in aqueous solution at ambient conditions. In this approach, it is observed that the surfactants (e.g, cetyltrimethylammonium bromide (CTAB) and tetraethylamine chloride (TEAC)) play a key role in the growth of goethite nanorods under the reported conditions. The molecular dynamics (MD) method is used to understand the underlying principle governing particle formation and growth through the analysis of the interaction energies between the crystal surfaces and the surfactant molecules. The findings will be useful for understanding the growth mechanism of anisotropic particles and their surface coatings with heterogeneous materials for desired functional properties.
First-Principles Calculation of Water Molecules with Adsorbed Ions on the Fe(001) Surface
Authors: Nunomura Norio , Sunada Satoshi
Published: June 2010

The behavior of water molecules with sulfate on the Fe(001) surface has been investigated using a first-principles method based on density-functional theory (DFT) with numerical atomic orbitals as basis functions for the description of valence electrons and nonlocal pseudopotentials for the atomic core. We present results for the adsorption structure and the bonding nature as caused by the adsorption-induced variations in the electron density and the projected density of states. We have found that the structure of absorbed sulfate depends on the coverage of water molecule on the surface. Analysis of electrostatic potential at an aqueous metal interface provides an appropriate framework to understand complicated potential structures. The mechanism of proton transfer through dissociative adsorption and hydrogen bonding of water molecules has been obtained from calculated results.
Mechanical Properties and Size Effects of ZnO Nanowires Studied by First-Principles Calculation
Authors: Gao Zhan Jun , Gu You Song , Zhang Yue
Published: June 2010

First-principles density functional calculations were performed to investigate mechanical properties of ZnO nanowires and the size effects. Structural optimizations were performed first, and a series of strains were applied to the nanowires in the axial direction. The ground state energies were calculated and the elastic moduli of ZnO nanowires were obtained from the energy versus strain curves. It is found that the elastic moduli of the ZnO nanowires with three different diameters (1.2, 1.5 and 1.8nm) are 136.3, 138.7 and 138.0 GPa, respectively, and that of bulk ZnO along [0001] direction is 140.1 GPa. The elastic modulus of ZnO nanowire is slightly lower than that of the bulk and it decreases as the diameter decreases. Comparisons to experimental results and theoretical predications are made.
First-Principles Study of Formation and Properties of Fcc-NdOx in Nd-Fe-B Sintered Magnets
Authors: Chen Ying , Hirosawa Satoshi , Iwata Shuichi
Published: June 2010

The NdOx phase formed at the Nd/Nd-Fe-B interface in Nd-sputtered Nd-Fe-B sintered magnets is paid rather attention recently due to its important role in coercivity generation of surface Nd-Fe-B grains. Its crystal structures have been reported to vary with the change of the oxygen concentration, and the disorder fcc phase derived from Nd2O3-C-type structure to be the main form of existence. To understand the formation mechanism of this fcc-NdOx interfacial phase, the stability of all oxygen concentration range of Nd-O system has been investigated from the first principles. Based on LSDA+U calculations for selected ordered phases at various oxygen concentration in Nd-O, the Cluster Expansion Method (CEM) is applied to evaluate the formation energy, density of states and other properties of disorder phase.
Simulation of Dislocation Accumulation in ULSI Cells of Reduced Gate Length
Authors: Sato Michihiro , Ohashi Tetsuya , Aikawa Keisuke , Maruizumi Takuya , Kitagawa Isao
Published: June 2010

We numerically evaluate the accumulation of dislocations in periodic structure of the shallow trench isolation (STI) type ULSI cells which has generally been adopted as the latest semiconductor device structure. STI type ULSI cells with gate length less than 62 nm and various trench depths are employed and subjected to a temperature drop from the initial value of 1000 °C. Dislocation accumulation is evaluated by a technique of crystal plasticity analysis. Relations between the geometry of the STI type ULSI cells and dislocation accumulation are discussed.
Microstructure of a Paint Primer - a Data-Constrained Modeling Analysis
Authors: Yang Sam , Gao Da Chao , Muster Tim , Tulloh Andrew , Furman Scott , Mayo Sheridan , Trinchi Adrian
Published: June 2010

Metallic aerospace components are commonly painted with a primer to improve their corrosion resistance. The primer contains a polymer matrix with embedded corrosion inhibitor and filler particles. Its performance is determined by the microscopic distributions of the particles. Various techniques have been used to quantify such distributions, including X-ray micro-computed tomography (CT). However, its success is sometimes limited by factors such as different particles having similar X-ray CT absorption properties and their size being smaller than the resolution of micro-CT. In this paper, we have performed two X-ray CT measurements on a paint primer sample consisting of SrCrO4 corrosion inhibitor particles and UV-absorbing TiO2 filler particles. Fe and Ti targets were used as X-ray sources with different spectral distributions. The measured CT data sets were used as constraints for a data-constrained microstructure modeling (DCM) prediction of the sample’s microscopic structures. DCM model predictions were compared with experimental elemental surface maps and showed reasonable degree of agreement, suggesting X-ray micro-CT combined with DCM modeling would be a powerful technique for detailing the dynamics of chromate-inhibited primers and other multiphase systems where the components are sensitive to incident X-ray energy.
Continuous Casting of Advanced Steels of Near-Peritectic Composition
Authors: Dippenaar Rian J.
Published: June 2010

The automotive industry is increasingly utilizing advanced high-strength steels, primarily to reduce the mass of motor vehicles. However, many of these steels fall within the peritectic composition range, which are notoriously difficult to cast by continuous casting techniques. Against this background, a brief review is given of our current understanding of the peritectic reaction as such and the subsequent peritectic phase transformations.
Crater Eruption Induced by High Current Pulsed Electron Beam (HCPEB) Treatment
Authors: Grosdidier Thierry , Zhang Xiang Dong , Wu Jiang , Allain-Bonasso Nathalie , Zhang Ke Min , Zou Jian Xin , Qin Ying , Li Xiao Na , Hao Sheng Zhi , Dong Chuang
Published: June 2010

High current pulsed electron beam (HCPEB) is a fairly new technique for improving surface properties such as corrosion and wear resistances. One of the negative effects induced by HCPEB is the potential formation of craters on the surface of the HCPEB treated materials. These changes can impair the corrosion-resistance by promoting pitting. The mechanisms of nucleation and growth are detailed and the effect of the number of pulses on crater formation is discussed.
Electrodeposition of ZnTe Compound Semiconductors from Aqueous Solution
Authors: Ohgai Takeshi , Ikeda Takashi , Kawanaka Yasuyuki , Takao Keizo , Kagawa Akio
Published: June 2010

ZnTe compound semiconductors were synthesized in acidic aqueous solution using a pulsed current electrodeposition technique. The optimum condition to obtain ZnTe deposits was determined by the cathodic polarization curves measured at a wide potential range. During the co-deposition of Zn and Te, under potential deposition (UPD) of Zn was observed. Increasing the solution temperature up to 353 K, UPD of Zn was promoted by the formation of Zn(OH)2. Crystal phase, structure and chemical composition of electrodeposited ZnTe was controlled by the solution composition and electrolysis condition. The band gap energy of ZnTe films annealed at 573 K was close to 2.26 eV.
Deposition of GaN Films on Freestanding CVD Thick Diamond Films
Authors: Zhang Dong , Bai Yi Zhen , Qin Fu Wen , Bian Ji Ming
Published: June 2010

High quality GaN films are deposited on freestanding thick diamond films by electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD). The characteristics of GaN films were investigated by x-ray diffraction analysis (XRD), reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM). The high quality GaN films with small surface roughness of 8.3 nm and high c-orientation are successfully achieved at the optimized nitriding time with the diamond substrate. These properties of GaN films with small surface smoothness and high c-orientation are well used as piezoelectric films for surface acoustic wave (SAW) devices.
The Preparation for Cu(Sn) Films of Barrierless Interconnection
Authors: Xu Li Yan , Li Xiao Na , Chu Jinn P. , Dong Chuang
Published: June 2010

In this study, Cu films doped with different Sn concentrations from 0.6-1.4 at.% were prepared by magnetron co-sputtering. The electrical resistivities and microstructures of Cu (Sn) films after annealings were investigated. The results showed that a sharp increase of the resistivity of Cu (1.4 at.% Sn) and Cu (1.1 at.% Sn) films were found after annealing above at 500°C. The existence of 0.6 at.% Sn in the Cu film is in solid solution state. A minimum electrical resistivity value of ~3.2μΩ•cm was obtained after annealing at 600°C for 1h . Even after a annealing at 700°C, the Cu/Si interface of Cu (0.6 at.% Sn) film still remained sharp without any Cu-Si and Cu-Sn compounds. The results confirmed that the lower resistivity and higher stability of Cu films can be achieved by strictly control of the doping concentrations and the existing state (solid solution without compounds and precipitates) of Sn element.
Structural Stabilities in GaAs Nanocrystals Grown on Si (111) Surface
Authors: Yasuda Hidehiro , Matsumoto Kimihisa , Furukawa Tatsuya , Imamura Masaki , Nitta Noriko , Mori Hirotaro
Published: June 2010

Structural stabilities in GaAs nanocrystals grown on the Si (111) substrate have been studied by transmission electron microscopy in order to see the structure and growth mechanism. The GaAs nanocrystals grown epitaxially on the Si (111) surface kept at 573 K have thin shapes consisting of a flat surface which is parallel to the Si (111) surface. The crystalline structure of the initial growth layer, below approximately 5 nm in thickness is zincblend, but with increasing thickness the structure changes to the wurtzite structure by formation of orderly-arranged stacking faults. The small difference in the driving force between wurtzite and the zincblende structure could lead to a situation where the kinetic rate of nucleus formation is higher for the wurtzite structure than for the zincblende structure. It would highly increase the probability that the wurtzite structure is formed as a non-equilibrium state.
The Optimization of SMR-Based Filter by Thermal Annealing Treatment
Authors: Wei Ching Liang , Chen Ying Chung , Cheng Chien Chuan , Kao Kuo Sheng , Chung Chung Jen , Chang Wei Tsai
Published: June 2010

In this study, an SMR-based filter was fabricated by dc/rf magnetron sputtering and photolithography, and a thermal annealing treatment was adopted to improve the frequency response. The SMR-based filter is composed of a ZnO piezoelectric thin film onto SiO2/W Bragg reflector. ZnO thin films were prepared by two-step sputtering with various deposition temperatures to obtain good piezoelectric properties. ZnO layers deposited at the temperature of 200 °C exhibit a highly c-axis preferred orientation, good crystalline characteristics and low surface roughness.
The filter is thermal treated by a rapid thermal annealing (RTA) technique. The thermal annealing treatment has improved the film properties of ZnO layers, resulting in a higher c-axis preferred orientation and a lower surface roughness of ZnO films than those of as-deposited ZnO films. The atomic ratio of Zn to O in ZnO film approaches one at the annealing temperature of 400 °C, which results in a comparatively oxidized stoichiometric ZnO film. Finally, the frequency response of the annealed filter is improved, and a lower insertion loss is obtained.
Thermal Barrier Systems and Multi-Layered Coatings Fabricated by Spark Plasma Sintering for the Protection of Ni-Base Superalloys
Authors: Monceau Daniel , Oquab Djar , Estournès Claude , Boidot Mathieu , Selezneff Serge , Ratel-Ramond Nicolas
Published: June 2010

Aeronautic gas turbine blades, vanes and combustion chambers are protected against high temperature oxidation and corrosion by single or multilayered coatings. These include environmental coatings, generally based on Pt-modified Ni aluminides or MCrAlY overlays (where M = Ni and/or Co), thermal barrier coating (TBC) systems including a ceramic thermally insulating layer, and abradable seals. The present work shows the ability of the Spark Plasma Sintering technique to rapidly develop new coatings compositions and microstructures. This technique allows combining powders and metallic foils on a superalloy substrate in order to obtain multilayered coatings in a single short production step. Fabrication of MCrAlY overlays with local Pt and/or Al enrichments is shown, as well as fabrication of coatings made of -PtAl2, -PtAl, α-AlNiPt2, martensitic and (Ni,Pt)Al or Pt-rich ’ phases, including their doping with reactive elements. The fabrication of a complete TBC system with a porous and adherent Yttria Stabilized Zirconia (YSZ) layer on a bond-coating is also demonstrated, as well as the fabrication of a CoNiCrAlY-based cermet coating for abradable seal application. Difficulties of fabrication are reviewed, such as Y segregation, risks of carburization, local over-heating, or difficulty to coat complex shaped parts. Solutions are given to overcome these difficulties.
Electrochemical Characteristics of Sintered Duplex Ferritic-Austenitic Stainless Steels Produced by Powder Metallurgy Process
Authors: Sunada Satoshi , Arai Keisuke , Mori Katsuhiko , Miyahara Masahisa , Majima Kazuhiko
Published: June 2010

The sintered stainless steel produced by the powder metallurgy process (P/M) has attracted a growing interest because it has the advantage of better formability to fabricate complex shape products without machining and welding. The four sintered stainless steel samples; i.e., the mono-phase SUS304L SS P/M sample (hereafter denoted as 304L), the mono-phase SUS316L SS P/M sample (hereafter denoted as 316L), the duplex-phase SUS316L and SUS434L SS P/M sample (hereafter denoted as 316L+434L), and the duplex-phase SUS316L and SUS434L SS P/M sample with copper (hereafter denoted as 316L+434L+Cu) were used in this experiment, and their corrosion behavior was investigated through the electrochemical procedure. It was confirmed from the potentiodynamic polarization test that their corrosion behavior was clearly classified into two groups. The one is for the mono-phase stainless steel group and the other is for the duplex-phase stainless steel group. Both corrosion current density (Icorr) and passivation current density (Ip) for the latter group were smaller than those for the former group, and especially the duplex-phase 316L + 434L SS sample with copper (316L+434L+Cu) showed the lowest value. This implies that the duplex-phase 316L + 434L SS sample with copper (316L+434L+Cu) has the highest corrosion resistance.
Characterization Performance of Laser Melted Commercial Tool Steels
Authors: Bonek Mirosław , Dobrzański Leszek Adam
Published: June 2010

The purpose of this research paper is focused on the X40CrMoV5-1 hot work tool steel surface layers improvement properties using high power diode laser. In the effect of laser alloying with powders of carbides occurs size reduction of microstructure, as well as dispersion hardening through fused in but partially dissolved carbides and consolidation through enrichment of surface layer in alloying additions coming from dissolving carbides. Introduced particles of carbides and in part remain undissolved, creating conglomerates being a result of fusion of undissolved powder grains into molten metal base. In effect of convection movements of material in the liquid state, conglomerates of carbides arrange themselves in the characteristic of swirl. Laser alloying of surface layer of investigated steel without introducing alloying additions into liquid molten metal pool, in the whole range of used laser power, causes size reduction of dendritic microstructure with the direction of crystallization consistent with the direction of heat carrying away from the zone of impact of laser beam. Remelting of the steel without introducing into liquid molten pool the alloying additions in the form of carbide powders, causes slight increase of properties of surface layer of investigated steel in comparison to its analogical properties obtained through conventional heat treatment, depending on the laser beam power implemented for remelting. The outcome of the research is an investigation showing the structural mechanisms accompanying laser alloying.
Fundamental Property of Metals – Grain Boundaries Phase Transition as a Basis of Nanostructured Layers, Materials and Composites Production
Authors: Minaev Y.A.
Published: June 2010

The obtained generalized equation for description of a fundamental property of solid crystalline materials i.e. first-order phase transition of the grain boundaries with formation of two-dimensional liquid has been used for calculating of transition temperature of any metals, which value lies in range 0.55 – 086 of melting point. Based on these conclusions to develop strategies for effective forming of coatings by synthesis of nitrides and carbonitrides on surface layers of hard metals and chromium steels have been made. It was shown the hardening of thin surface layer (0.1-0.5mm) due enriched of a nitrides in steels and carbonitrides with diamond like structure and strengthening the following layer by recristallization of W carbides in WC-Co and WC-TiC-Co hard metal. These result to increase of alloys hardness, ductility, and resistance to wear and decrease of sensibility to fragile rupture. Industrial tests have been made.
Effect of Copper Sulfide on the Fatigue Properties of Bake Hardening Steels
Authors: Choi Il Dong , Kang Sung Gyu , Jang Ji Hyun , Lee Sung Bok , Hong Moon Hi
Published: June 2010

Bake hardening steels have to resist strain aging to prevent the yield strength increment and stretcher strain during press process and to enhance the bake hardenability during baking process after painting. The bake hardening steels need to control the solute carbon and the solute nitrogen to improve the bake hardenability. Ti and/or Nb alloying for nitride and carbide precipitation and low carbon content below 0.003% are used to solve strain aging and formability problem for automotive materials. However, in the present study, the effect of micro-precipitation of copper sulfide on the bake hardenability and fatigue properties of extremely low carbon steel has been investigated. The bake hardenability of Cu-alloyed bake hardening (Cu-BH) steel was slightly higher (5MPa) than that of Nb-alloyed bake hardening (Nb-BH) steel, but the fatigue limit of Cu-BH steel was far higher (45MPa) than that of Nb-BH steel. All samples showed the ductile fracture behavior and some samples revealed distinct fatigue stages, such as crack initiation, stable crack growth and unstable crack growth.
Determination of Mechanical Properties of TiN Coating Using a Notched Cylindrical Stainless Steel Substrate
Authors: Elambasseril Joe , Ibrahim Raafat N. , Das Raj
Published: June 2010

Comprehensive studies of the fracture morphology and the sequence of fracture patterns during tensile loading are important to understand the performance of ceramic coatings during operation. The ceramic coatings are applied to relatively rough surfaces with edges and corners. When the substrate is not perfectly smooth and flat, large stress concentrations are generated in the coated system. The stress concentrations due to the shape of the substrate also affect the initiation and propagation of cracks in the coatings. The mechanical integrity of TiN coating is studied using a new test specimen, known as the Cylindrically-Notched-Tensile (CNT) specimen that can mimic real life situations. The coated specimens under tensile loading are then examined using a scanning electron microscope to study the response of the coatings to the applied loads. The interfacial shear strength of the coatings is determined using the Agrawal-Raj model. Multiple cracks are observed in the coating and the fracture morphology was found to depend on the stress concentration at notch corners.
Liquid Phase Separation Behaviors in Cu-Fe Alloy Coatings Synthesized by Laser Cladding
Authors: Lu Yun , He Yi Zhu
Published: June 2010

A Fep/Cu composite coating was developed based on laser cladding process in immiscible liquid system. The microstructure of the coatings is characterized by a homogeneous distribution of Fe-rich spherical particles dispersed in the Cu-rich matrix. The size of the Fe-rich spheres decreases and their number density increases with the decrease of the heating input. The micro-hardness and wear resistance results show that the micro-hardness of the composite coating (spherical particle (380 ~ 450 HV0.2) and the Cu-rich matrix about 200 HV0.2) is far better than that of the copper (70 HV0.2), the wear resistance of the composite coating is almost twice of the copper. Such Fep/Cu structure composite coating have a good combination of high strength and corrosion resistance (Fe-rich phase) and high electric and thermal conductivities (Cu-rich phase) with many potential advanced applications in electronic devices.
Composition Design and Laser Cladding of Cu-Zr-Al Alloy Coating on the Magnesium Alloy
Authors: Wang Cun Shan , Li Ting , Yao Biao , Wang Rui , Wang Qing
Published: June 2010

The cluster line criterion was used for optimized design of a Cu-Zr-Al alloy used as coating on the AZ91HP magnesium alloy by laser cladding. Results show that the coating mainly consists of an amorphous, Cu8Zr3, and Cu10Zr7 phases, of which the relative content of amorphous phase is estimated to be 61 %. The formation of the amorphous and intermetallics composite structure results in high hardness, good wear resistance and corrosion resistance. The interface between the clad layer and the substrate has good metallurgical bond.
Effect of Titania Nanoparticles on Micro-Arc Anodizing of AM60B Magnesium Alloy
Authors: da Forno Anna , Ke Liu , Bestetti Massimiliano
Published: June 2010

Oxide films have been produced on the AM60B magnesium alloy using micro-arc oxidation process in an environmentally friendly alkaline solution with and without addition of titania nanoparticles. The surface morphology and cross-section of anodized samples were analyzed by Scanning Electron Microscopy (SEM) coupled with EDS and the phase composition was investigated by X-ray Diffraction (XRD). Hardness tests were performed by means of a micro-hardness tester and the corrosion resistance was evaluated in 3.5% NaCl solution using potentiodynamic polarization tests. Addition of titania nanoparticles doesn’t affect corrosion resistance significantly, but the oxide films produced in titania-containing solution are denser, thicker and have more uniform morphology. In the oxides produced at 130V-140V in presence of titania (4g dm-3) a spinel (MgAl2O4) was observed. Spinel phase increases the hardness up to 550 HV (10mN, 10 s). The addition of titania nanoparticles in the solution could be an interesting way to synthesize hard coatings on magnesium alloy AM60B by micro-arc oxidation in a short process time (10 minutes).
Production of Stainless Cast Iron Base Deposits with Dispersed Titanium Carbide Particles by Plasma Spraying
Authors: Hoshiyama Yasuhiro , Miyazaki Tsutomu , Miyake Hidekazu
Published: June 2010

Fe-C-Ti-Cr-Ni alloy powder in diameter of 32-53 μm made by argon atomization is low-pressure plasma sprayed to produce stainless cast iron base deposits with finely dispersed titanium carbide particles. The as-sprayed deposit formed on a water-cooled substrate consists of γFe, αFe, TiC and Cr3C2. Heat treatment of the as-sprayed deposit above 873 K results in the formation of Cr7C3. The fine precipitates of approximately 0.2 μm in the as-sprayed deposit formed on a water-cooled substrate are carbide. The as-sprayed deposit produced on a non-cooled substrate and deposits which are obtained by heat treatment of the as-sprayed deposit are composed of γFe, αFe, TiC, Cr3C2 and Cr7C3. As heat treatment temperature increases, carbide precipitates coarsen. The hardness of deposit decreases with increasing heat treatment temperature. The wear resistance of as-sprayed deposit formed on a non-cooled substrate was higher than that of the deposit heat-treated at 1273 K. The as-sprayed deposit and deposit heat-treated at 1273 K have higher wear resistance than a commercial stainless steel.
Stress Dependence of Microstructural Evolution in Heat Resistant Steels
Authors: Murata Yoshinori , Saoto Yoshihiro , Tsukada Yuhki , Koyama Toshiyuki , Morinaga Masahiko , Sasaki Yasutoshi , Hasegawa Yasushi
Published: June 2010

The state of the microstructure of ferritic heat resistant steels during creep was evaluate by the system free energy, which composes mainly chemical free energy, surface energy and elastic strain energy, and its stress dependence was expressed quantitatively by using a relaxation time. The steels used in this study were P91 (9Cr-1Mo-C-N-V-Nb) steel and P92 (9Cr-Mo-W-C-N-V-Nb-B) steel. The obtained results are as follows: (1) the relaxation time of elastic strain energy was expressed as a function of stress and temperature, (2) surface energy of P92 scarcely decreased during creep due to the formation of the Laves phase, and (3) the relaxation time of the chemical free energy in P92 was larger than that in P91.
Preparation and Property of a Fe-Doped DLC Multilayer by Ion Sources
Authors: Ren N. , Ma Z.J. , Zhao D.C. , Xiao G.J. , Wu S.H.
Published: June 2010

A novel technique has been successfully developed to grow Fe ion doped diamond-like corbon (DLC) multilayer, with the modified linear ion sources(LIS), on Si(100)substrates. The Fe ions, generated in the specially designed ion source and accompanying the argon ions were implanted into one DLC layer previously grown by pulsed arc ion plating during argon ions sputtering and etching. The Fe-DLC multilayer can be grown by alternating growth of DLC layer and Fe ion implantation. The mechanical properties of Fe-DLC films were characterized. The results show that the Fe ion implanted multilayer significantly improves its mechanical properties. As compared with the conventional DLC films. Its stress drops to 3.9 GPa from 4.5 GPa, its friction coefficient is down to 0.1 from 0.14, and its hardness remains unchanged.
Electrodeposition of CuSn Alloy from Noncyanide Sulfosuccinate Bath
Authors: Nakamura Toshihiro , Nagayama Tomio , Yamamoto Takayo , Mizutani Yasushi , Nawafune Hidemi
Published: June 2010

Recently the regulation of nickel usage because of allergy issues has been strengthened in Europe and other countries. The Cu-Sn alloy (40-55 mass%Sn) is called “speculum alloy” or “white bronze” and has a silvery-white appearance. We developed a noncyanide Cu-Sn alloy plating bath consisting of sulfosuccinic acid, L-methionine and polyoxyethylene-α-naphthol, from which silvery-white Cu-Sn alloy (40-55mass%Sn) were obtained. It is anticipated that the Cu-Sn alloy films will be used as an alternative to nickel undercoating for decorative gold or chromium electroplating.
Effect of Pre-Oxidation Treatment on the Thermal Shock Resistance of Thermal Barrier Coatings in a Combustion Gas Environment
Authors: Mei Hui , Cheng Lai Fei , Liu Ya Nan , Zhang Li Tong
Published: June 2010

Thermal barrier coatings (TBCs) were deposited by an Air Plasma Spraying (APS) technique. The TBC coating comprised of 92 wt.% ZrO2 and 8 wt.% Y2O3 (YSZ), CoNiCrAlY bond coat, and MarM247 nickel base super alloy. After APS of YSZ two batches of TBC specimens were tested, one batch of which was pre-oxidised in air for 10h at 1080 oC. Both types of the specimens were directly pushed into a combustion gas at 1150 oC for 25 min and then out to the natural air for quenching. The combustion gas was produced by burning jet fuel with high speed air in a high temperature wind tunnel, which simulates the real service conditions in an aeroengine. Results show that TBCs prepared by the APS had good thermal shock resistance in the combustion gas. The pre-oxidation treatment of the TBC had a significant effect on its thermal shock life. The as-oxidised TBCs always had worse thermal shock resistance than the as-sprayed ones after thermal shock cycles.
Investigation on Interfacial Bonding Strength of Anisotropic Conducive Adhesive with a New Cohesive Zone Model
Authors: Zhang Jun , Lin Yong Cheng , Wei Xin Li , Huang Liu Gang
Published: June 2010

A modified cohesive zone interface model with a damage factor was proposed to describe the effects of the thermal cycle and humidity aging on the strengths of adhesive joints. The damage factor can not only change the cohesive zone bonding strength but also affect the energies of separation. The modified cohesive zone interfacial model, as a user subroutine, is developed and implemented in ABAQUS to simulate the 90° peeling process of the specimens, which were bonded by anisotropic conducive adhesive film (ACF) and subjected to the cycle and humidity aging tests. The numerical simulated results well agree with experimental results, which confirmed the validity of the new model.
Development of Laser Surface Treatment with Excellent Corrosion Resistance and Conductivity Performance on Magnesium Alloy Products
Authors: Hino Makoto , Mitooka Yutaka , Murakami Koji , Nishimoto Katsuji , Kanadani Teruto
Published: June 2010

Effects of the laser processing on corrosion resistance and conductivity for the magnesium alloy products anodized from the phosphate electrolytic solution were examined. The area where anodized coating was removed under the appropriate laser processing condition showed the excellent corrosion performance as well as good conductivity. This improvement of the conductivity is attributable to the removal of the anodized coatings whose conductivity is not good, and excellent corrosion resistance is based on the sacrifice corrosion protection by anodizing from the phosphate electrolytic solution.
Relaxor Ferroelectricity and Electrostrictive Behavior of KNN-ST Ceramics
Authors: Fan Hui Qing , Li Zhuo , Ren Peng Rong , Jiao Gang Cheng
Published: June 2010

The new electrostrictive ceramics have been produced from the (1-x) K0.5Na0.5NbO3-xSrTiO3 (KNN-ST, x=0.1-0.25) system by using conventional mixed-oxide methods. Sintering temperatures rise with increasing SrTiO3 content (x=0.1-0.25) and are in a very narrow range. The x-ray diffraction patterns indicate that with the increasing of SrTiO3 up to 0.25, KNN-ST ceramics with a single perovskite structure exhibit a transition from orthorhombic to cubic and no other impure phase appeared. The dielectric and relaxor ferroelectric properties of KNN-ST ceramics are investigated with the different SrTiO3 content. Also, the strain of these ceramics induced by applied electric fields have been studied. The electrostrictive response is similarly as in the classical PMN (lead magnesium niobate), but lower (order of the 10-5) than PMN (order of the 10-3). Furthermore, this system shows translucent, high dielectric constant, thus suggests possible applications in electric-optic devices, electromechanical transducer applications.
VSintering and Nonlinear Dielectric Properties of Ba0.6Sr0.4TiO3 Ceramics Prepared by Citrate Method
Authors: Zhang Xiao Fei , Xu Qing , Chen Wen , Liu Han Xing
Published: June 2010

Ba0.6Sr0.4TiO3 powder was synthesized by a citrate method. The powder with a pure pervoskite phase and superfine particle morphology was produced at low calcining temperature of 550°C by controlling heating rate during the calcination. Microstructure and nonlinear dielectric properties of the ceramic specimens were investigated with respect to sintering temperature. It was found that the superfine morphology of the powder effectively reduced the sintering temperature of the ceramic specimens. The ceramic specimen sintered at 1260 °C attained about 95% of the theoretical density. At room temperature, the ceramic specimen showed a dielectric constant of 3010 and a dielectric loss of 0.48% at 10 kHz together with a tunability of 32.4% at 10 kHz and 20 kV/cm.
Millimeter-Wave Reactive Sintering of Neodymium-Doped Yttrium Aluminum Garnett
Authors: Imam M. Ashraf , Fliflet Arne W. , Gold Steven H. , Bruce Ralph W. , Stephenson Chad , Feng C.R.
Published: June 2010

Millimeter-wave sintering of ceramic laser host materials has been under investigation for high-energy laser (HEL) applications. Advantages of polycrystalline, compared to single-crystal, laser host materials include lower processing temperature, higher gain from higher dopant concentration, cheaper fabrication, and larger devices. We are currently investigating the solid-state reactive sintering of neodymium-doped yttrium aluminum garnet (Nd:YAG) using a high power millimeter-wave beam as the heat source. The 83 GHz beam is generated in the Naval Research Laboratory (NRL) High Frequency Materials Processing Facility that is powered by a 15 kW, CW, 83 GHz GYCOM gyrotron. The starting powder is a mixture of commercially available alumina, yttria, and neodymia powders. Near transparency and over 99% theoretical density have been achieved with grain sizes of 5 to 10 µm. The fluorescence lifetime of the Nd+3 1.06 µm lasing transition was measured to be about 200 µs, in good agreement with other work. SEM studies of the sintered microstructure show residual porosity caused by trapped pores that must be eliminated to produce fully transparent material.
Solid-State Reaction Synthesis and Mechanism of Lithium Silicates
Authors: Tang Tao , Huang Huo Gen , Luo De Li
Published: June 2010

Lithium-based ceramics have been recognized as promising tritium breeding-materials for D-T fusion reactor blankets. Lithium silicates, Li4SiO4 and Li2SiO3, are recommended by many ITER research teams as the first selection for the solid tritium breeder. The solid-state reaction method is the most important way to synthesize lithium silicates. In present study, the processes of solid-sate reaction between amorphous silica and Li2CO3 powders was investigaed by TGA/DSC; the lithium silicate powders were synthesized at 700~900°C with different Li:Si molar ratio using solid-state reaction method. The optimized synthesis temperature and the solid-state reaction mechanism were derived on the base of experimental results.
Solid-State Synthesis and Properties of Y-Doped BaCeO3
Authors: Li Ying , Ding Yu Shi , Wang Chang Zhen
Published: June 2010

BaCe1-xYxO3-α (x = 0.1, 0.15) solid electrolytes were prepared via ball milling raw powders of BaCO3, CeO2 and Y2O3, and pressing the powder mixtures into tablets followed by calcining in air. X-ray diffraction analysis indicated that the BaCe0.9Y0.1O3-α and BaCe0.85Y0.15O3-α solid solutions were synthesized at 1250°C and 1400°C, respectively. The solid electrolyte disks were made by grinding the calcined tablets into fine powders, cold isostatic pressing into the shape and sintering at 1550°C in air. The electrochemical impedance spectroscopy measurements revealed that they show useful protonic conduction, up to 2.7×10-2 S/cm at 900°C.
Research and Production Practice of DR Material in Baosteel
Authors: Li Xiu Jun , Chen Yun Peng
Published: June 2010

In recent years, the double cold reduction material (DR material) was developed rapidly with the increase of industry market of computer, mobile telephone, household electrical appliances and pop canning and so on. The DR material has its characteristics such as very thin specification, strong intensity, high flatness and surface quality. In China, only Baosteel has ability to produce with the double cold reduction (DCR) technology. In this paper,based on the five years research and production Practice since 2004, the experimental study, production commissioning and product performance optimization methods in Baosteel have been discussed, such as the mode choice, roll gap lubrication system as well as the control method, the actual production operation and technology parameter set and so on ,so as to promote the development and progress of DR material production. It offers beneficial reference for the technologist on the spot.
Preparation and Luminescent Properties of Na5Eu(MoO4)4-x(PO4)x Red Phosphors for White Light-Emitting Diodes Application
Authors: Xi Cui Sheng , Shi Shi Kao , Gong Hui Li , Zhou Ji
Published: June 2010

(PO4)3- -doped red phosphors, Na5Eu(MoO4)4-x(PO4)x (x ≤ 0.10), were prepared by the conventional solid-state reaction method, and their luminescent properties were studied. Under the excitation of near-UV 395 nm, the phosphors show intense red emission. In particular, the relative emission intensity of Na5Eu(MoO4)3.96(PO4)0.04 sample reaches about 5.0 times in comparison with that of the commercial red phosphor Y2O2S:Eu3+. The phosphor could be suitable for the application of white light-emitting diodes.
Ferroelectric and Photocatalytical Properties of Ta-Based and Nb-Based Oxide Ceramics and Powders from Environmentally Friendly Water-Soluble Tantalum and Niobium Precursors
Authors: Li Ai Dong , Zhai Hai Fa , Kong Ji Zhou , Wu Di
Published: June 2010

Due to the great potentials of tantalite and niobate materials in ferroelectric and photocatalytic applications, development of proper tantalum or niobium precursors is urgently need. In this work, a simple novel route to synthesize environmentally friendly aqueous tantalum and niobium precursors has been developed using cheap and stable Nb2O5 or Ta2O5 as starting source. Using home-made Ta and Nb precursors, several photocatalytic nanopowders such as BiNbO4 and BiTaO4, and ferroelectric ceramics such as 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT), have been prepared by a modified PC method. These powders and ceramics from polymeric precursors have low crystalline temperature and transformation temperature with uniform grain distribution, compared to conventional solid phase reaction (SSR). Pure triclinic phase of BiNbO4 powders can be obtained at 700°C instead of 1020°C of SSR, with excellent photodegradation activity of methyl violet. PC-derived PMN-PT ceramics also exhibit better ferroelectric and piezoelectric properties. All these indicate that this is an attractive and flexible approach using environmentally friendly water-soluble tantalum and niobium precursors for fabrication of tantalate and nibonate functional materials.
Laser Forming of Ti-6Al-7Nb Alloy Powder Compacts for Medical Devices
Authors: Miura Hideshi , Okawachi Kenta , Kang Hyun Goo , Tsumori Fujio , Kurata Kosaku , Arimoto Nobuhiro
Published: June 2010

Titanium and its alloys have been widely used for medical and aerospace applications because of their excellent attributes of light metal, high strength, high corrosion resistance and high biocompatibility. Especially, Ti-6Al-7Nb alloy has been developed as a more suitable biomaterial to replace Ti-6Al-4V alloy, because vanadium is toxic element to the biological body. However, it is not easy to fabricate the complex shaped and precise parts by the conventional methods due to their poor castability and machinability. In this study, laser forming technique has been applied to solve the above problems. The precise structure was obtained by optimizing the laser forming parameters. Using this technique, a honeycomb structure was fabricated　effective to grow the neighboring tissue and also encourage osseointegration. Finally, mouse osteoblasts were cultured on the formed structures, resulted in the effectiveness of the honeycomb structure for biocompatibility.
Development of Polyimide/SMA Thin-Film Actuator
Authors: Ishida Akira , Sato Morio
Published: June 2010

Ti-Ni-Cu shape memory alloy (SMA) thin films were sputter-deposited on heated polyimide substrates. The (Ni,Cu) rich Ti-Ni-Cu films deposited at a substrate temperature of 543 K were found to possess a high martensitic transformation temperature above room temperature over a wide range of Cu content from 7 to 23 at%, which allows stable production of actuators that operate at room temperature. Additional deposition of a Cu film onto the Ti-Ni-Cu films facilitated the soldering of wires onto the actuators and also decreased the power consumption and response time of the actuator. The force of a polyimide/Ti-Ni-Cu SMA actuator could be increased merely by increasing the thickness of the polyimide film. An actuator composed of a 125 m thick polyimide film and an 8 m thick TiNiCu film was able to lift a 13.5 g weight. Furthermore, a Ti-Ni-Cu film could be pattern etched on a polyimide film to produce a circuit. The results indicate that a polyimide/SMA film actuator is a promising simple actuator that can be produced by simply cutting out an appropriately shaped piece with scissors or by punching and then connecting the two edges to a battery by soldering.
The High Temperature Connecting Strength and Thermal Stability of Ti44Ni47Nb9 SMA Pipe Coupling
Authors: Jin Wei
Published: June 2010

The creeping properties of Ti44Ni47Nb9 shape memory alloy (SMA) were studied at 300°C. The connecting strength, deformation and thermal stability of the connected units were investigated under constant load and high temperature, and the units were composed of SMA pipe couplings and 16×1.5mm 1Cr18Ni9Ti tubes. The results indicated that (1) Ti44Ni47Nb9 alloys had excellent creeping properties at 400MPa stress and 300°C; (2) the connected units had good connected properties and thermal stabilities at 8445N axial tensile load and 400°C; (3) the essence of high temperature relaxation of the connected units was that the strength of SMA pipe couplings and connected tubes reduced with increasing temperature, and the pipe couplings had relative displacement to the connected tubes under axial tensile load.
Hysteretic Behavior of Concrete Cylinders Confined by Active Confining SMA Wire Jackets
Authors: Choi Eun Soo , Lee Hack Soo , Park Joo Nam , Cho Bak Soon
Published: June 2010

Shape memory alloy (SMA) wire jackets are distinct from conventional jackets for concrete members since they can provide active confinement easily. The applications of SMAs in civil engineering are on the increase since SMAs show unique properties of shape memory effect and superelastic behavior. Especially, the seismic application of SMAs for confining concrete becomes a hot issues in recent. Thus, this study conducts cyclic compressive tests of concrete cylinders jacketed by shape memory alloy (SMA) wires which can provide active confinement due to shape memory effect. Monotonic compressive tests provide only the peak strength and the ultimate strain for confined concrete. However, confined concrete is exposed to the repeating of loading and unloading during an earthquake. Also, this study performs the same tests for concrete cylinders jacketed by steel jackets which provide only passive confinement and the results are compared to those of SMA wire jackets. This study provides the basic information of concrete behavior confined by active or passive external jackets.
Phase Stability and Mechanical Properties of Ti-Cr Based Alloys with Low Young’s Modulus
Authors: Murayama Yonosuke , Sasaki Shuichi , Kimura Hisamichi , Chiba Akihiko
Published: June 2010

This work investigates the mechanical properties of Ti-Cr system alloys and focuses on the microstructure, the Young’s modulus, the deformation mechanism and the deformation behaviour observed in various alloy compositions. The addition of Al to the Ti-Cr system alloys greatly decreases the Young’s modulus. Addition of Al, Sn and Zr to various Ti-Cr alloys suppresses the athermal ω phase that forms during quenching from β field. A Ti-Cr system alloy with low Young’s modulus was obtained in suitable compositional combination of Cr, Zr and Sn or Al. The alloys with the composition where the quenched microstructure transits from martensite to meta-stable β phase show low Young’s modulus. In addition, the alloys show two-step yielding due to stress-induced transformation.
Phase Constituents of Ti-Cr-Au and Ti-Cr-Au-Zr Alloy Systems
Authors: Shinohara Yuri , Ishigaki Takuya , Inamura Tomonari , Kanetaka Hiroyasu , Miyazaki Shuichi , Hosoda Hideki
Published: June 2010

The phase constituents of the Ti-Cr-Au ternary and Ti-Cr-Au-Zr quaternary systems were investigated using X-ray diffraction analysis and optical microscopy. The composition ranges were 3~10mol%Cr and 0~8mol%Au for the ternary system, and 0~42mol%Zr were added to Ti-5mol%Cr-4mol%Au. It was found that the β phase was stabilized by the addition of Cr and Zr, and that A15-type Ti3Au was formed when the Au content was 6mol% or higher. Besides, C14 Laves phase similar to Zr33Ti40Au27 was recognized in Ti-5mol%Cr-4mol%Au-42mol%Zr.