bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanolayered CrN/TiAIN Coatings Synthesized by Ion Plating Technology for Tribological Application on Piston Rings
Authors: Cai Zhi Hai , Zhang Ping , Di Yue Lan
Published: March 2011

By using the ion plating technology,the multilayered CrN/TiAlN as well as monolayered CrN and TiAlN coatings were made on the suface of piston rings to improve its tribological properties and increase service life using Cr and Ti50Al50 alloy cathodes. EDS analysis showed that the main compositions of CrN/TiAlN coatings are Cr30.61%,Ti 20.42%,Al 13.88% and N 35.10%. The preferred orientation was changed from (111) in CrN and TiAlN monolayered coatings to (220) plane in the multilayered CrN/TiAlN coatings. The multilayered CrN/TiAlN coatings had smaller crystallite size than the monolayered CrN coatings. The multilayered TiAlN/CrN coating with rotational speed at 1.5 rpm exhibited the highest H3/E2 ratio value of 0.23 GPa, indicating the best resistance to plastic deformation, among the studied CrN, TiAlN and multilayered TiAlN/ CrN coatings. The CrAlTiN composite films performs better than binary CrN as well as the Cr plating in teams of hardness and wear resistance at high temperature.
Study on Microstructure and Mechanical Behavior of Magnetorheological Fluids with Mixed Particles
Authors: Li Hai Tao , Peng Xiang He
Published: March 2011

The microstructure and mechanical properties of magnetorheological (MR) fluids with mixed particles of different size are investigated. The interaction between particles of different radius is obtained and the model for motion of particles is proposed. Under an external magnetic field, the microstructure and yield shear stress of MR fluids with mixed particles of different sizes are simulated. It shows that particle size ratio in bidisperse suspensions can influence the performance of MR fluids.
Synthesis of Phosphazene Flame Retardant and its Application in Epoxy Molding Compound for Large-Scale Integrated Circuit Packaging
Authors: Yang Ming Shan , Liu Jian Wei , Li Lin Kai
Published: March 2011

The tri(o-phenylenediamine) cyclotriphosphazene (TPCTP) was synthesized using titrating technology of hexachlorocyclotriphosphazene solution and the synthesis parameters were investigated, and the structure of TPCTP was analyzed by FTIR in this paper. Using TPCTP synthesized in the work as flame retardant, the epoxy molding compound(EMC) for packaging of large-scale integrated circuits with halogen-free flame retardance was prepared. The results have shown that the flame retardance of EMC flame-retardanced by TPCTP was up to UL 94 V0 rating(1.6mm) and the oxygen index of the EMC was up to 34.5%, which indicates that TPCTP has much better flame retardance for EMC than traditional halogen flame-retardants. Meanwhile, TPCTP accelerated the curing reaction rate of EMC, which can be used for manufacturing the quick-curing EMCs or afterward-curing-free EMCs.
Cooperative Work & Cooperative Efficiency Evaluation of Automotive Industry Chain Based on Collaborative Commerce Platform
Authors: Wang Shu Ying , Yang Chao , Zheng Wei Na
Published: March 2011

A Cooperative Work mode was proposed based on an analysis on the collaborative characteristic of enterprises in automotive industry chain. And a description method of cooperative work model based on product order bills, maintenance bills and assembly order bills was constructed with the supporting of the collaborative commerce platform, the parts requirement info could be gained with the model. A cooperative efficiency evaluate model was constructed, on the base of history operation data, the value of deviation square was used to estimate the stability of the evaluation function in order to gain the weight of the factors, which provides a reference for the optimization of the industry chain.
Dynamics of a Higher Order Rational Difference Equation
Authors: Yang Yi , Lv Fei Bao
Published: March 2011

In this paper, we address the difference equation xn=pxn-s+xn-t/q+xn-t n=0,1,... with positive initial conditions where s, t are distinct nonnegative integers, p, q > 0. Our results not only include some previously known results, but apply to some difference equations that have not been investigated so far.
Attack and Improvement of the Secure Password Authentication Protocol in Wireless Networks
Authors: Lee Yung Cheng
Published: March 2011

Password authentication protocols are widely used mechanisms to authenticate identities in networks. In 2006, Yoon et al. proposed a secure password authentication protocol in wireless networks that fixed the drawback of Ma et al.’s protocol. In this article we show that the Yoon et al.’s protocol is still vulnerable to the off-line password guessing attack. We propose an improvement to solve the problem. The improvement protocol is secure while the computation cost is the same with Yoon et al.’s protocol.
Integrated Non Reciprocal Ring Resonators
Authors: Jalas Dirk , Petrov Alexander , Krause Michael , Hampe Jan , Eich Manfred
Published: March 2011

We present the theoretical concept of an optical isolator based on a resonance splitting in a silicon ring resonators covered by a magneto-optical polymer cladding. A polymer magneto optical cladding causing a 0.01 amplitude of the off-diagonal element of the dielectric tensor is assumed. Using a perturbation method it is shown that the resonance splitting of the clockwise and counter-clockwise modes increases for smaller ring radii. For the ring with a radius of approximately 1.5μm a 29GHz splitting is demonstrated. An optical isolator is proposed based on a critically coupled ring resonator.
Research on Rope-Less Hoist System Driven by PMLSM
Authors: Wang Xu Dong , Feng Hai Chao , Xu Bao Yu , Xu Xiao Zhuo
Published: March 2011

Rope-less hoist system driven by permanent magnet linear synchronous motor has the advantages of simple structure, small volume, high force, unlimited hoisting height and speed. So, it is attracting more attention, increasingly becoming a research hot and difficult in the vertical hoist field. In this paper, a design scheme of direct driving high-speed elevator is proposed according to the key technical problems of rope-less hoist system driven by PMLSM, and then a small-sized home elevator prototype is built. Experimental results show the safe and stable operation performance of the experimental device, which offers the reference for the further research and the development and application of PMLSM rope-less hoist system.
Research on Dependable Architecture of Saas Based Platform Supporting the Industry Chain Coordination
Authors: Liao Wei Zhi , Sun Lin Fu , Zhou Xiao Ming
Published: March 2011

The demand of dependability of SaaS(Software as a service) based platform supporting the industry chain coordination (in brief, PLATFORM) is analyzed, the characteristics of virtualization technique in the respect of enhancing the dependability of computing system are researched ,then the virtualization technique based dependable Architecture of PLATFORM is designed and the process of enhancing dependability of PLATFORM is discussed in the paper. The dependable Architecture of PLATFORM proposed in the paper can well satisfied dependable characteristic includes Reliability, availability, maintainability and security etc, and system crashes, system halt and data loss by reason of system fault , system error, system failure can be effectively prevented which can provide good support for SaaS based system applications.
Densification of TiCN Matrix Cermets by Microwave Sintering
Authors: Tang Si Wen , Zhang Hou An , Yan Jian Hui
Published: March 2011

TiCN matrix cermets were prepared by using traditional sintering and microwave sintering. The effect of sintering methods, sintering temperature and protective atmosphere to the densification process of as prepared material were discussed. The results show that microwave sintering can short the sintering time than the traditional sintering, but it need higher temperature to obtain approximate density. At 1500°C,holding 5min, vacuum microwave sintering can gain relative density of 99.5%. The relative density of TiCN matrix cermets under argon shield is lower than vacuum microwave sintering, and the microscopic particles is more small, but the uniformity of pore is reduced. Microwave sintering can greatly reduce energy consumption.
Analysis on the Failure Mechanism of Un-Connecting Rod Engine Gear Assembly
Authors: Huo Ping , Wang Jian Ping , Yu Jiang , Liu Rui Fang
Published: March 2011

With the respect of the phenomenon that gear teeth are broken in the gear-gear ring striking gear of un-connecting rod engine, this paper analyzes its movement rule, and applies the explicit integral finite element method to simulate its dynamics. It shows that the theory engagement of gear-gear ring conforms to the rule of epicyclic gear train, and the deviation of the phase angle caused by mismachining tolerance is the main reason why gear teeth are broken.
Modeling the Thermal Deformation of the Volume Bragg Grating in High-Power Beam Combining System
Authors: Gao Lan Lan
Published: March 2011

Volume bragg grating is the important element in spectral beam combining technique. However the thermal-induced distortion and temperature gradient make strong impact on the grating’s performance. In this paper, a model of five 3kW off resonator laser beams combining system is analyzed through Comsol. The z-displacement and temperature distributions with different boundary conditions have been shown. The results demonstrate that Comsol is a practical and useful tool to analyze the thermal problem in the gratings.
The Design of the Heterotypic Antenna Array of the Smart Antenna with the LMS Algorithm
Authors: Jin Jie , Kong Xi , Zhao Lan Lan
Published: March 2011

Using the Least Mean Square (LMS) algorithm, this paper simulates two smart antenna models under the same signal environment. By analyzing and comparing 8-antenna elements linear array and 2*4- antenna elements rectangular array, this paper proposes the way to design the heterotypic antenna model. This antenna array can help system to gain similar performance of signal to interference plus noise radio(SINR) with reduced size of the antenna. The paper realizes the simulation of two models with the LMS algorithm. The antenna pattern and the curve about convergence of error have been given. It also analyzes the influence of the step length factor on LMS algorithm performance, and finds out the reasonable step to ensure fast algorithm convergence and to suppress interference effectively.
Analysis on Spatial Pattern of Urban Heat Island and Impervious Surface Using Linear Spectral Mixture Analysis
Authors: Pan Jing Hu , Shi Pei Ji , Zheng Feng Juan
Published: March 2011

Based on Landsat ETM+ data within the metropolitan area of Lanzhou, China, green vegetation(GV) and impervious surface was extracted by a constrained linear spectral mixture analysis (LSMA),together with single window algorithm to invert land surface temperature ,and the correlation analysis was then conducted to examine the relationship between urban heat island (UHI) effect and impervious surface. Four types of end members with high albedo, GV, soil and low albedo are selected to model complicated urban land cover, estimation accuracy is assessed using Root-Mean-Square (RMS)error and color aerial images, with the help of Mantel and Partial Mantel. Spatial relationship of land surface temperatures (LST), impervious surface and GV were analyzed. Results indicate that impervious surface distribution and GV can be derived from Landsat TM/ETM+ images with satisfactory precision. Impervious surface and GV were positively correlated with UHI, while LST has space dependence, it has high space dependence, and was higher correlated with impervious surface than GV.
Mobile Wireless Sensor Networks K-Covering Algorithm
Authors: Zhou Xin Lian , Xiao Bin , Cheng Jing Liang
Published: March 2011

In mobile wireless sensor networks, sensor nodes may due to their own moves, energy loss, physical damage, errors and failures or other factors, will result the case of coverage holes, and then lead to inefficient network coverage. This paper designed a new algorithm based on clustering approach for mobile wireless sensor network, can monitor the network in real-time and repairing coverage holes quickly. Simulation results show that, the algorithm used in mobile wireless sensor network not only can achieve the desired uniformity of coverage, but also increase the coverage area, and better performance than the Virtual force algorithm(VFA) [1].
Dielectric and Hot/Wet Properties of Methyl-Silsesquioxane/Cyanate Ester Resin Hybrid Materials
Authors: Zhang Zeng Ping , Wen Yong , Du Hong Zhao , Pei Jian Zhong , Chen Shuan Fa
Published: March 2011

Methylsilsesquioxane (Me-SSQ) was incorporated into cyanate ester resin (CE) to obtain organic-inorganic hybrids with better dielectric properties in this study. First, methyltriethoxysilane was hydrolyzed and condensed to synthesize Me-SSQ. Then several Me-SSQ/CE hybrids containing different contents of Me-SSQ were prepared. The effect of Me-SSQ content on the dielectric and hot/wet properties of materials was investigated. Results showed that the Me-SSQ/CE hybrid containing 20wt% of Me-SSQ shows a dielectric constant of 2.78, which is much lower than the pure CE resin. At the same time, the dielectric loss of the Me-SSQ/CE hybrids was slightly increased (tanδ<0.006). It indicates that Me-SSQ/CE hybrid is a promising matrix materials for high-performance printed circuit board (PCB).
Preparation and Dielectric Properties of POSS-NH2/Cyanate Ester Resin Organic-Inorganic Hybrids
Authors: Zhang Zeng Ping , Pei Jian Zhong , Chen Shuan Fa , Du Hong Zhao , Wen Yong
Published: March 2011

In order to improve the dielectric and overal properties of cyanate ester (CE) resin, a functional POSS monomer(octa(aminopropyl)silsesquioxane, POSS-NH2), was employed to modify CE. A series of POSS-NH2/CE hybrids (CE, CE1, CE2, CE3 and CE4) containing different content of POSS have been prepared by melt casting and then curing. The curing reaction of the resin systems were monitored by FT-IR. Dielectric properties of the hybrids were investigated in detail. FT-IR results showed the almost disappearance of the –OCN for all resin systems, suggesting the complete curing of CE using the experimental curing technique. Dielectric investigation indicates that CE1 which contains 1 wt% of POSS has the best dielectric properties with not only lowest dielectric constant but also lowest dielectric loss.
Optimal Design of Tunable Optical Add-Drop Multiplexer in Silicon-on-Insulator
Authors: Xing Xiao Bo , Wang Ying Lian
Published: March 2011

A tunable optical add-drop multiplexer in silicon-on-insulator (SOI) is proposed by using thermo-optic effect. The device integrates a two-mode interference coupler with a set of tilted gratings, and its operation principle is based on multiple-mode interference principle and coupled-mode theory. The 3-dB bandwidth of add/drop wavelength is 0.5 nm in the reflection spectrum. Its central add/drop wavelength range is from 1550 to 1558.5 nm when the applied power is less than 14 W in the two-mode interference section, i.e. gratings section. The device is attractive in terms of tunable range of add/drop wavelength and design tolerance.
A Planar Lightwave Circuit Based on Optical Add-Drop Multiplexer with 16 Tunable Wavelength Channels
Authors: Xing Xiao Bo , Wang Ying Lian
Published: March 2011

An electrically controlled optical add-drop multiplexer (OADM) based on silicon on insulator is presented, which possesses 16 tunable add/drop wavelength channel of 100 GHz channel spacing. The OADM is integrated lateral p-i-n diodes with single-mode Mach-Zehnder interferometer filter, which transforms the change of refractive index induced by the plasma dispersion effect into a voltage controlled variation of add/drop wavelength. The 3dB bandwidth of add/drop wavelength is less than 0.8 nm when the etch depth, period, Bragg wavelength and length of Bragg grating are 500 nm, 223 nm, 1548.5 nm and 1000 mm, respectively. When the applied voltage is 1.059~1.2219V, the tunable add/drop wavelength of OADM is between 1547.7 and 1536.5nm. Also, the add/drop wavelength could be controlled precisely by changing the grating period, which can satisfy the requirement of other wavelength range.
Effect of Resistance Spot Welding Parameters on the Austenitic Stainless Steel 304 Grade by Using 23 Factorial Design
Authors: Peasura Prachya
Published: March 2011

This research was study the effect of resistance spot welding process on physical properties. The specimen was austenitic stainless steel sheet of 1 mm. The experiments with 23 factorial design. The factors used in this study are welding current at 8,000 and 12,000 Amp, welding time at 8 and 12 cycle and electrode force were set at 1.5 and 2.5 kN. The welded specimens were tested by tensile shear testing according to JIS Z 3136: 1999 and macro structure testing according to JIS Z 3139: 1978. The result showed that the welding current, welding time and electrode force had interaction on tensile shear and nugget size at 95% confidential (P value < 0.05). Factors affecting the tensile shear are the most welding current of 12,000 amp., welding time of 8 cycle and electrode force of 2.5 kN. were tensile shear of 9.83 kN. The nugget size was maximum at 7.15 mm. on welding current of 12,000 amp., welding time of 12 cycle and electrode force of 1.5 kN This research can bring information to the foundation in choosing the appropriate parameters to resistance spot welding process.
Micro-Thermoelectric-Generator Design and Analysis Based on Catalytic Combustion of Hydrogen
Authors: Wang Feng , Wang Guo Qiang , Zhou Jing , Zhou Xin Jing
Published: March 2011

The micro-thermoelectric-generator based on combustion of hydrogen and oxygen was designed. With the application of general finite reaction rate model in CFD software of FLUENT, the effect of inlet parameters on the highest temperature difference between the hot and cold plate of the generator was studied. Results show that, the temperature in the heating and cooling channel of the micro-thermoelectric-generator is uniform; With the increasing of inlet reactant temperature, the highest temperature difference increases, but the total efficiency of the generator decreases. Results can be used to the further design and optimization of micro-thermoelectric-generator based on hydrogen catalytic combustion.
Simulation of Methanol Steam Reforming Heated by Waste Heat for Hydrogen Production in a Microreactor
Authors: Wang Feng , Zhou Jing , Wang Guo Qiang , Zhou Xin Jing
Published: March 2011

In order to intensify the process of methanol steam reforming and improving the heating supply process by waste heat, the effect of evenly and interrupted distributed catalytic surface was studied on H2 content at reactor outlet. With the application of general finite reaction rate model in CFD software of FLUENT, we carried out 3-D simulation of this process. Results show that, outlet H2 content can be increased through interrupted distributed catalytic surface with the same catalyst loading. This result can be used to provide the basis for surface reaction design and optimization in microreactor.
Growth and Characterization of Self-Assembled Boron Carbon Nitride Needle-Like Nanostructures
Authors: Chen You Ming , Zhang Guang Ye , Yang Sheng Rong , Zhang Jun Yan
Published: March 2011

Large-scale highly aligned boron carbon nitride (BCN) needle-like nanostructures were synthesized directly on Si (100) substrates by the novel technique of magnetron sputtering of the boron and graphite targets in a N2+Ar gas mixture at the substrate temperature of 800 °C. XRD reveals that the nanostructures contain an inhomogeneous crystalline structure. The hybridized BCN phases with needle-like nanostructures should now be regarded as semiconductors may be used as electron emitters for field electron emission applications.
Design of Electronic Data Management System in Web-Based CAD Environment
Authors: Chen Hua Guang
Published: March 2011

Based on the enterprise demand for data management in the networked environment of the CAD, this paper designs a data management system, gives the systems structure, analyses the main problems in system development, introduces the main functional modules. The results show that the system can improve the design productivity of enterprises, and it also has good practical value and potential marketing value.
Research on Large Scale Data Set Processing Based on SVM
Authors: Chen Yue E , Ren Bai Li
Published: March 2011

SVM has got very good results in the area of solving the classification, regression and density estimation problem in machine learning, has been successfully applied to practical problems of text recognition, speech classification, but the training time is too long is a big drawback. A new reduction strategy is proposed for training support vector machines. This method is fast in convergence without learning machine’s generalization performance, the results of simulation experiments show the feasibility and effectiveness of that method through this method.
An Experimental and Analytical Vibration Study of a Thin Cylindrical Shell Treated with Constrained Layer Damping
Authors: Zhang Xiang , Zhu Shi Jian , Liu Gui Feng
Published: March 2011

This paper presents a experimental optimization method for a thin cylindrical shell with a partially passive constrained layer damping (PCLD) treatment. Vibration level difference theory is employed to evaluate damping effect of PCLD structures which the thicknesses of damping layer and constrained layer are different.
Chaotic Dynamics in Duffing System with Two External Forcings
Authors: Zhang Shu Guang , Zhu Zhi Yong , Guo Zhi
Published: March 2011

Duffing system with two external forcing terms is investigated in detail. The criterion of existence of chaos under the periodic perturbation is given by using Melnikov's method. Numerical simulations including heteroclinic and homoclinic bifurcation surfaces, bifurcation diagrams, maximum lyapunov exponents and Poincare map are given to illustrate the theoretical analysis.
Discussion on Construction of OCDMA PON Address Code-(F,K,2) Optical Orthogonal Codes
Authors: Li X.B. , Huang H.B. , Wang L.C.
Published: March 2011

Optical code division multiple access (OCDMA) passive optical network (PON) can find wide applications in the next optical access network. One of its key techniques of is construction of address code. Aiming at the facts that(F,K,1) optical orthogonal code (OOC) possesses good performance but capacity is small, and number of users in OCDMA PON is not very big thereafter OOC auto-correlation or cross-correlation may not be very strict,(F,K,2) OOC can be used as address codes for OCDMA PON. In this paper, the method of constructingOOC based on block design is discussed. The algorithm of construction (F,K,2) of OOC from block design is presented and simulated; several groups of(F,K,2) OOC are gained. The results show that the algorithm has good astringency and simplicity. It can construct(F,K,2) OOC effectively. It is feasible.
The Top-Stem-Cutter for the Top-Cutter Machine Design and Fem Analysis
Authors: Wang Chun Yao , Chen Fa , Lei Min , Jiang Yong Xin , Liu Yue
Published: March 2011

Designing a top-stem-cutter part for the top-cutter machine. Adams was used to analysis the moving simulation, with the help of it, the normal structure and dimension were inspected and verified. In this paper, the tract of the top-stem-cutter part analyzed by Adams was matched the result from the theoretical calculations; the model and structure also had been analyzed by Ansys, which provided a way to analysis and verify the machine, and analysis of the model can get the nature frequency of the top-stem-cutter part, and it had given us a way to lower frequency of machine; the structure analysis provided that the stress of the top-stem-cutter part should be lower than certain value.
Attached FBG Strain Sensor Based on Thermal Stress Mechanism
Authors: Li Jian Zhi , Du Yan Liang , Liu C.X.
Published: March 2011

Based on a novel thermal stress mechanism, a attached FBG strain sensor with temperature-compensated function was designed and manufactured. This sensor cannot only compensate temperature drift but enhance stain sensitivity. The results are as follows: this package was shown to have a near 2.0 pm/°C shift and a high strain sensitivity of 1.9pm/με in this proposed self-compensated package.
Segregation in Single-Crystal Nickel-Base Superalloys
Authors: Epishin A.I. , Svetlov I.L. , Petrushin N.V. , Loshchinin Yu.V. , Link T.
Published: March 2011

The effect and the ways of removal of the segregation of alloying elements within the dendrite cell in single-crystal nickel-base superalloys are discussed. The peculiar features of Re and Ru behavior are underlined.
Reactive Diffusion upon Planar Dissolving Copper in Solder Melts
Authors: Drápala Jaromír , Jopek Pavel , Petlák Daniel , Harcuba Petr , Kubíček Petr
Published: March 2011

Problems of reactive diffusion at a solid phase - melt contact were studied theoretically. The main intention was to calculate the time course of the solid phase dissolving in the case of planar dissolving. In our work we give heed especially to the dominating process, which is the solid metal A dissolving in solder melt B. During the dissolving, melt B saturates with metal A, and the process is influenced by convections which are characteristic for a given experimental configuration. A theoretical description of the kinetics of solid phase dissolving in the melt will be presented for the case of planar dissolving. The aim is to derive a relation for the interphase boundary movement (t) depending on time and a time course of growth of the element A concentration in the melt B. There are difficulties in accurate determination of the interphase boundary movement after heating of specimens for certain time intervals. It should be performed experimentally, since intermetallic phases are formed in original metal A both via diffusion and upon cooling and some phases segregate upon cooling of the solidifying melt. The main intention was to study experimentally the copper dissolving in melts of various solder alloys and the related reactive diffusion. We used pure Sn and Sn-Cu, Sn-Ag-Cu, Sn-Sb, Sn-Zn alloys as solder materials. Experiments aimed at the study of a Cu plate dissolving in the solder melt were carried out at various selected temperatures and times. The problems of reactive diffusion were studied both theoretically and experimentally and the problems that have to be solved preferably were emphasized. Concentration profiles of elements and thickness of layers of phases can be determined with SEM and X-ray microanalyses (WDX, EDX) of specimens after their diffusion heating.
The Effect of Plastic Deformation on Nitrogen Diffusion in α-Fe
Authors: Demchenko Lesya , Sidorenko Sergey I.
Published: March 2011

The surface diffusion layers formed in preliminary deformed (350 %) -Fe after nitriding at 853 K in ammonia medium were studied by means of metallography, electron microscopy, microhardness test and X-ray powder diffractometry. The preliminary plastic deformation (PPD) effects non-monotonously on the structure, microhardness and thickness of nitride - and -phases layers formed in -Fe. The narrow intervals of deformations of 3-8 % and 20-30 % were found in which the accelerated formation of nitride - and -phases occurs.
Redistribution of Alloy Elements during Nickel Silicide Formation: Benefit of Atom Probe Tomography
Authors: Perrin C. , Hoummada K. , Blum I. , Portavoce A. , Descoins M. , Mangelinck D.
Published: March 2011

The unique capabilities of atom probe tomography (APT) to characterize internal interfaces and layer chemistry with sub-nanometer scale resolution in three dimensions have been recently opened up to materials with poor electrical conductivity by the use of ultrafast laser pulses. The progress in sample preparation (focused ion beam) as well as in instrument performance enable now the analysis of relatively large volumes with typical diameters of 100 to 200 nm and depths of several hundred nm (this corresponds to an increase by several order of magnitude compared to the former instrument) of site specific samples. In this work, APT is used to study the effects of Pt on the formation and stability of Ni silicides. The precise location of this alloy element has been determined at the nanometer scale: In particular, APT allows us to quantify the amount of Pt in the grain boundaries (GB) of Ni2Si for about 100 different grain boundaries and thus to better characterize the GB diffusion and segregation.
Diffusion Phase Formation in the Cu-Sn Nanofilms System
Authors: Rennie Adrian R. , Sidorenko Sergey I. , Kotenko I.E. , Voloshko S.M. , Oleshkevych Anna I.
Published: March 2011

Processes involved in the structure and phase formation in the thin film systems Sn(4 nm)/Cu(14 nm) and Сu(14 nm)/Sn(8 nm) in the temperature range 130-500 оС were studied using “in situ” electron imaging and Transmission Electron Microscopy methods (TEM). Solubility of Sn α – solid solution Cu-Sn has been determined from the changes in the lattice parameter. This work was performed in the framework of the Swedish Institute supported cooperative research project “Thin metal films – the interplay of structure diffusion and boundaries” (SI dnr 00699/2009).
Thermally Activated Relaxation and Hysteretic Internal Friction in Ultrafine Grained Copper
Authors: Golovin Igor S. , Zadorozhnyy Vladislav Yu.
Published: March 2011

Temperature and amplitude dependent internal friction (TDIF and ADIF) in ultrafine-grained copper (99.95% Cu) specimens processed by equal channel angular extrusion by route BC in 1, 4, and 8 passes and then subjected to annealing is investigated by means of dynamical mechanical analyzer DMA Q800 in the temperature range from -100 to 550 °C, amplitude range from 10-6 to 10-3, and frequency range from 0.05 to 100 Hz. Two IF peaks were registered and explained by structural relaxation due to the recrystallisation process and by thermally activated grain boundary relaxation with broad distribution of relaxation times. Increase in amplitude dependent damping in ultrafine-grained copper is due to dislocation but not grain boundary contribution.
Role of Finite Vacancy Relaxation Rate at SHS Reactions in Nanosized Multilayers
Authors: Zaporozhets T.V. , Gusak Andriy
Published: March 2011

Rate of SHS (self-propagating high-tеmperature synthesis) reactions in solid nano-sized multilayers is controlled by the time and temperature dependent vacancy concentration. The increase of reaction temperature is typically faster than the rate of vacancy generation. Therefore, the finite relaxation rate of vacancies leads to drastic slowing down of SHS. On the other hand, as-prepared vacancy supersaturation due to fast deposition on the cold substrate may lead to a certain acceleration of SHS. Influence of (1) vacancy mean free path and (2) initial vacancy supersaturation on the SHS rate is investigated numerically. In wide region of parameters the front velocity appears to be inversely proportional to the square root of vacancy mean free path length.
Computer Simulation of Fe Diffusion in Liquid Al and along Al Grain Boundaries
Authors: Mendelev Mikhail , Rodin A.O. , Bokstein Boris S.
Published: March 2011

We performed molecular dynamics simulation of diffusion along symmetric <100> 5 and <111> 7 and one non-symmetric <100> 5 tilt grain boundaries in Al in the presence of Fe impurities. The simulation results are in reasonable agreement with available experimental data. The addition of Fe considerably decreases both Al and Fe diffusivities and increases the activation energy for diffusion. The simulation data indicate that the mechanism of diffusion is different in different grain boundaries. The diffusion along <100> 5 grain boundaries reminds that in liquid alloys.
Diffusion Controlled Grain Triple Junctions Wetting in Metals
Authors: Bokstein Boris S. , Gulevsky S.A. , Petelin A.L. , Rodin A.O.
Published: March 2011

The interaction between liquid and solid metals where the liquid-solid interface contains three grain boundary lines which meet in triple junction point is considered. The assumption that the liquid grooves may be formed not only along grain boundaries but along triple junctions is presented. The variation of Gibbs energy during the formation of triangle pyramidal groove along triple junction is determined. The dependence of Gibbs energy variation from groove dimensions shows that the wetting of triple junctions occurs by lower temperatures than the wetting of grain boundaries. This result allows to take into account the existence of grain size effect on the liquid phase penetration depth into the polycrystalline sample. The proposed mechanism of wetting in polycrystalline metal contains two stages: the outstrip melt penetration along triple junctions and the liquid grooving on grain boundaries forming the triple junctions. One of the processes – triple junction diffusion or liquid diffusion – may control the wetting in the polycrystalline sample.
Fabrication and Microstructure of Al-Based Hybrid Composite Reinforced by B4C and Ultra-Dispersed Tungsten
Authors: Gorshenkov Mikhail V. , Kaloshkin Sergey D. , Tcherdyntsev Victor V. , Danilov Vladimir D. , Gulbin Victor N.
Published: March 2011

Al-based hybrid composite reinforced by ultra-dispersed tungsten and B4C, was produced by mechanical alloying and hot extrusion. Structure of obtained composites was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The compressive and tensile properties of these materials were investigated. Tribological tests showed high antifriction properties and wear resistance of composite containing B4C and tungsten. The dilatometric measurements showed that thermal expansion coefficient remains approximately constant up to 500 °C.
Gallium Distribution in Gallium-Coated Aluminum for Brazing Application
Authors: Ferchaud E. , Christien Frédéric , Paillard Pascal , Barnier V. , Wolski Krzysztof , Mourton H. , Azaïs P. , Rossignol C.
Published: March 2011

This work deals with the study of a new aluminum brazing process, called Galluminium. This technique, consisting in using gallium as a solder, is advantageous since it enables to braze at ambient air without flux. Indeed if the gallium coating is done mechanically, it descales the alumina layer and acts as a barrier against further reoxidation. Nevertheless, liquid gallium causes a severe aluminum embrittlement since it penetrates into the aluminum grain boundaries. We will show in this paper that this phenomenon has only a little impact on the mechanical resistance of the brazed joints since the amount of deposited gallium is enough low to avoid a severe embrittlement and the heat treatment (from 200°C to 600°C during several minutes) during brazing process dissolves gallium in the bulk.
Thermodynamic and Kinetic Study of Leaching Magnesia from Natural Magnesites by Carbon Dioxide
Authors: Klochkovskii S. , Smirnov A. , Shabalina U.
Published: March 2011

The applicability of carbon dioxide pressure leaching for the extraction of high purity magnesia from natural magnesites has been investigated. Factors which have influence on the magnesia recovery such as time, temperature, pressure, particle size and calcination temperature have been studied. Optimum values were determined: calcination temperature was in the range 650 – 750 0C, time of the calcination was approximately 5 – 3 hours; carbon dioxide partial pressure leaching for the extraction of magnesia was about 3 bar; particle size was between 0,2 – 0,6 mm. A kinetic study of carbonation of MgO has been investigated at leaching temperature from 00C to 50 0C. Two processes were observed: the formation of a magnesium bicarbonate solution and the precipitation of magnesium carbonate. Our research has determined that the concentration of impurities in magnesium carbonate is virtually no different from their concentration in natural magnesites. Apparently, the formation of magnesium carbonate proceeds without destruction of structure. So the extraction of high purity magnesia from natural magnesites by carbon dioxide is only possible using magnesium bicarbonate. It is necessary to optimize the translation process of magnesium in solution and the technology of extraction of pure MgO from it to generate high purity magnesium on an industrial scale.
Numerical Simulation Support for Diffusion Coefficient Measurements in Polycrystalline Thin Films
Authors: Portavoce Alain , Blum Ivan , Chow Lee , Bernardini Jean , Mangelinck Dominique
Published: March 2011

The measurement of diffusion coefficients in today’s materials is complicated by the down scaling of the studied structures (nanometric effects in thin films, nano-crystalline layers, etc.) and by the complex production process conditions of industrial samples or structures (temperature variations, complex solute and point defect distributions, stress gradients, etc.). Often diffusion measurements have to be performed in samples for which initial experimental conditions do not offer the possibility of using conventional diffusion analytical solutions. Furthermore, phenomena involved with diffusion are sometimes so numerous and complex (stress, matrix composition inhomogeneities, time dependence of point defect generation sources, electrical effects, clustering effects, etc…) that the use of analytical solutions to solve the observed diffusion behavior is difficult. However, simulations can be of use in these cases. They are time consuming compared to the use of analytical solutions, but are more flexible regarding initial conditions and problem complexity. The use of simulations in order to model physical phenomena is quite common nowadays, and highly complex models have been developed. However, two types of simulations have to be considered: i) simulations aiming to understand and predict phenomena, and ii) simulations for measurement purposes, aiming to extract the (average) value of a physical parameter from experimental data. These two cases have different constrains. In the second case, that is the subject of this article, one of the most important stress is that the simulation has to precisely scale the experiment (sample size, experiment duration, etc.), sometimes preventing the measurement due to computational time consumption. Furthermore, the simpler the model (small number of parameters) used in the simulation, the more relevant the measurement (minimum error). In this paper, examples of recent works using two- and three-dimensional finite element simulations for diffusion coefficient measurements in thin polycrystalline films and nano-crystalline layers are presented. The possible use of simulations for diffusion coefficient measurements considering GB migration, GB segregation, or triple junctions is also discussed.
Cu GB Diffusion in Al. Effect of Alloying by Cu and Ce
Authors: Rodin Alexey , Dolgopolov Nikolai , Simanov Andrei , Zaytseva Alla
Published: March 2011

The diffusion of Cu in Al and Al based alloys was studied. It was shown the great scattering of triple product values, measured for different grain boundaries (GB) at the same samples. It was discussed in the terms of GB energy difference. It was also shown that GB triple product can be varied significantly by preliminary alloying of Al by 0.1% Cu. However, the alloying of Al by 0.5% Cu leads to disappearing of the effect of accelerated diffusion in GB in comparison with the bulk.
Comparison of Jump Frequencies of 111In/Cd Tracer Atoms in Sn3R and In3R Phases Having the L12 Structure (R = Rare-Earth)
Authors: Lockwood Harberts Megan , Norman Benjamin , Newhouse Randal L. , Collins Gary Scott
Published: March 2011

Measurements were made of jump frequencies of 111In/Cd tracer atoms on the Sn-sublattice in rare-earth tri-stannides having the L12 crystal structure via perturbed angular correlation spectroscopy (PAC). Phases studied were Sn3R (R= La, Ce, Pr, Nd, Sm and Gd). Earlier measurements on isostructural rare-earth tri-indides showed that the dominant diffusion mechanism changed along that series [4]. The dominant mechanism was determined by comparing jump frequencies measured at opposing phase boundary compositions (that is, more In-rich and more In-poor). Jump frequencies were observed to be greater at the In-rich boundary composition in light lanthanide indides and greater at the In-poor boundary composition in heavy-lanthanide indides. These observations were attributed to predominance of diffusion via rare-earth vacancies in the former case and indium vacancies in the latter. Contrary to results for the indides, jump frequencies found in the present work are greater for the Sn-poor boundary compositions of the stannides, signaling that diffusive jumps are controlled by Sn-vacancies. Possible origins of these differences in diffusion mechanisms are discussed.
Implanted Impurities in Wide Band Gap Semiconductors
Authors: Keßler P. , Lorenz K. , Vianden R.
Published: March 2011

Wide band gap semiconductors, mainly GaN, have experienced much attention due to their application in photonic devices and high-power or high-temperature electronic devices. Especially the synthesis of InxGa1-xN alloys has been studied extensively because of their use in LEDs and laser diodes. Here, In is added during the growth process and devices are already very successful on a commercial scale. Indium in nitride ternary and quaternary alloys plays a special role; however, the mechanisms leading to more efficient light emission in In-containing nitrides are still under debate. Therefore, the behaviour of In in GaN and AlN, the nitride semiconductor with the largest bandgap is an important field of study. In is also an important impurity in another wide band gap semiconductor – the II-VI compound ZnO where it acts as an n-type dopant. In this context the perturbed angular correlation technique using implantation of the probe 111In is a unique tool to study the immediate lattice environment of In in the wurtzite lattice of these wide band gap semiconductors. For the production of GaN and ZnO based electronic circuits one would normally apply the ion implantation technique, which is the most widely used method for selective area doping of semiconductors like Si and GaAs. However, this technique suffers from the fact that it invariably produces severe lattice damage in the implanted region, which in nitride semiconductors has been found to be very difficult to recover by annealing. The perturbed angular correlation technique is employed to monitor the damage recovery around implanted atoms and the properties of hitherto known impurity – defect complexes will be described and compared to proposed structure models.
Impurity Centers in Oxides Investigated by γ-γ Perturbed Angular Correlation Spectroscopy and Ab Initio Calculations
Authors: Pasquevich Alberto F. , Rentería Mario
Published: March 2011

In this chapter Perturbed Angular Correlation (PAC) experiments on binary oxides are described. These experiments provide local-scale fingerprints about the formation, identification, and lattice environment of defect complexes at the PAC probe site. The potential of the PAC observations in conjunction with ab initio calculations is shown. Measurements of the electric-field gradient at impurity sites using 111Cd and 181Ta probes are reviewed. Special attention is paid to oxides with the bixbyite structure. The case of In2O3 is particularly analyzed. Results obtained with HfO2, in form of coarse grain or nano particles, are described. The potential results that can be obtained from Density Functional Theory ab initio calculations in doped systems are shown describing the main results observed in many impurity-host systems.
Backward Drawing of Necks Using Incremental Approach
Authors: Petek Aleš , Kuzman Karl , Fijavž Renato
Published: March 2011

The paper presents a modern manufacturing concept called the “backward incremental hole-flanging process”. It enables drawing necks on the final products that can be very complex or even closed with minimal expense. Special attention is dedicated to researching the most influential process parameters affecting the neck height and the thinning of the neck using empirical modelling. Results show that forming tool diameter, and horizontal and vertical step sizes have the greatest influence on the forming results.
Numerical and Experimental Investigation of Process Parameters Effect of Low Carbon Steel Wire Produced with Roll Drawing Process
Authors: Lambiase Francesco , di Ilio Antoniomaria
Published: March 2011

The effect of roll drawing process parameters on geometrical characteristics of flat roll draw wires is analyzed. Low carbon steel wires AISI 1010 are used in the experimental tests to assess the final geometry, mainly characterized by the width of flat wires, varying among several experimental levels the main process parameters i.e., initial wire dimensions, height reduction and lubrication conditions. Design of experiment technique was used to define the experimental plan and statistical techniques, such as analysis of mean (ANOM) and variance (AVOVA), were used to evaluate the effective influence of previous cited process parameters on final geometry of wire. A finite element model is developed to investigate a further process parameter i.e. the working rolls dimensions. In order to validate the finite element model, a campaign of experimental tests was conducted and the geometrical predictions of FE model were compared with experimental mea-surements with particular attention to final wire width, width of contact area and wire elongation. A linear regression analysis was performed and an empirical formulation to forecast the lateral spread of wire according to the main process parameters was developed.
Measurement of Material Flow in Series Production
Authors: Neumann Anja , Hortig Dirk , Merklein Marion
Published: March 2011

This paper provides first results of a contact-free measurement system for monitoring the material flow in series production which has been under investigation for more than one year. An inductive proximity sensor with analog output was used to measure its own sheet metal coverage. Multiple sensors were integrated in the blank holder without affecting the deep drawing process. The robustness of the monitoring principle was assessed under series production conditions by using optical measurement equipment. This paper describes the basic information of the inductive measurement, the comparison of the inductive and optical measurement results and analyses correlations between the sensors.
Wrinkling Study in Tube Hydroforming Process
Authors: Khalili Khalil , Eftekhari Shahri S. Ehsan , Kahhal Parviz , Khalili M. Soheil
Published: March 2011

Tube Hydroforming Process (THF) is heavily affected by the pressure-displacement diagram, and adjustment of the raw tube. Three common defects of the process are bursting, buckling and wrinkling. In this work, the leading conditions to wrinkling defect have been studied. Proper criteria are required to predict wrinkling condition, and to quantify wrinkling when subjected to various pressure-displacement diagrams. A variety of criteria have been presented by researchers, most of which are suitable to a specific geometry. In current work, two criteria are considered namely, the strain difference and the radius velocity. At first an accurate FEM (Finite Element Model) model of the process have been established and validated. Then based on a number of experiments with different diagram, the process have been simulated and analyzed. According to experiments imbalances between pressure and displacement, improper sitting of tube in the die, poor vacation of the tube and the existence of external tiny particle inside the die, are the reason of wrinkling criterion in the tube. The Response Surface Method (RSM) has been used to model the responses from the finite element analysis. The behavior of the process has been predicted using this model.