bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo Modelling of Recrystallization Process in Cold Rolled IF-Ti Steel
Authors: Samet-Meziou Amel , Gerber Ph. , Tarasiuk Jacek , Baudin Thierry , Penelle Richard
Published: March 2009

Recently, some authors have used the Monte Carlo modelling using complete set of experimental data to get a better correlation between experimental observations and calculations concerning recrystallization process [1, 2]. Simulations using Monte Carlo technique have been performed these last years for IF-Ti steels in order to predict the microstructure and the texture evolution after high reduction amounts by cold rolling [3, 4]. On the contrary, in the present work, this evolution is simulated in an IF-Ti steel cold rolled after low deformation amount (reduction amount R = 40 %). Microstructure is characterized by Electron Back-Scattered Diffraction and introduced in the model. The quality index of the Kikuchi patterns (EBSD data) is used to qualitatively evaluate the stored energy for each grain. Different hypothesis of nucleation mechanisms have been introduced into the model. It has been shown that the better recrystallization texture correlation between experiment and simulation is obtained by taking into account the nucleation in the low stored energy sites and highly misorientation regions. Finally a simulation issue was compared with EBSD and TEM experimental results: microstructure, recrystallization kinetics and Avrami coefficients values.
Grain Boundaries with High Misorientation and Low Mobility
Authors: Ryde Lena , Hutchinson W. Bevis , Kumano Tomoji
Published: March 2009

Island grains have been studied in iron samples that had been treated by critical-strainannealing and in commercial silicon iron alloy sheets after incomplete secondary recrystallisation. Such islands remain behind because their boundaries have such a low mobility that the grains cannot shrink away in the time available during annealing. Misorientations of these islands in relation to the grains surrounding them were measured using EBSD. Similar results were observed
in both materials. A small number of low angle boundaries were found and also many twin boundaries. The most remarkable observation, however, was the presence of many general high angle boundaries that did not correspond to any evident coincidence relation.
Segregation of Calcium to Magnesium Oxide Grain Boundaries
Authors: Papillon F. , Wynblatt P. , Rohrer Gregory S.
Published: March 2009

Grain boundary (GB) segregation has been measured in Ca-doped MgO by examining intergranular fracture surfaces with Auger electron spectroscopy. The measurements reveal several interesting features. The composition of any given GB on the fracture surface is almost uniform, except for small variations due to deviations from planarity. There is a strong anisotropy of GB composition, which can amount to as much as a factor of six between low and high segregation GB's. Finally, although the compositions of opposite sides of a GB fracture are uniform, there are sometimes significant differences between the two sides, in agreement with a recently formulated model of GB composition as a function of GB character.
Study of the Texture Formation during Strain Induced Boundary Migration in Electrical Steel Sheets
Authors: Murakami Kenichi , Tarasiuk Jacek , Réglé H. , Bacroix Brigitte
Published: March 2009

Texture formation through strain induced boundary migration (SIBM) was investigated. Temper rolling reduction before final annealing for SIBM was varied between 0 and 26% and grain sizes and textures were measured using EBSD. In the specimen which was temper rolled to 5%, in which grain growth by SIBM occurred most efficiently, a strong Goss component (which was a minor component after rolling), developed during annealing. From the EBSD image quality analysis, it was found that stored energy increased significantly in the Goss component with strain (from 5 to 9 %), whereas it was always relatively small in the D-Cube component ({001}<110>), compared to Goss and g-fibre components. Based on these results, a mechanism of grain growth by SIBM was suggested. Texture evolution during annealing could thus be explained by the hypothesis, speculated from the analysis of orientation stability, that D-Cube grains are associated with more homogeneous dislocations distributions than Goss grains, in which the co-existence of high and low dislocation density zones could favour grain growth by SIBM.
Kinetics of Austenite Grain Growth during a Continuous Heating of a Niobium Microalloyed Steel
Authors: San Martín David , Caballero Francisca García , Capdevila Carlos , Carcía de Andrés C.
Published: March 2009

Grain growth is a thermally activated process in which the average grain size increases as temperature and time increases. The driving force for grain growth results from the decrease in the free energy associated with the reduction in total grain boundary energy. There are several known factors that influence the migration of grain boundaries such as second phase particles precipitated in the matrix and the solute elements segregated at grain boundaries. The austenite grain boundaries are revealed using the thermal etching method. Carbon extraction replicas were prepared to determine the composition and size of precipitates present in the matrix. In this work, the evolution of the average prior austenite grain size (PAGS) of a low carbon steel microalloyed with niobium is studied as a function of temperature and heating rate. Austenite grains show a two-stage growth. It has been found that as heating rate increases, the grain coarsening temperature (TGC) increases and the grain size at that temperature decreases. TGC temperature lies around 40-60°C below the temperature for complete dissolution of carbonitrides (TDISS).
The Experiment Research of Diamond Wire-Saw in Quarrying Granite with High Efficiency
Authors: Zhang Jin Sheng , Huang B. , Wang Zhenya , Wang X.L. , Liu Zeng Wen
Published: March 2009

The diamond wire-saw is a kind of stone machining equipment with flexible cutters. It is widely used in quarrying granite, machining of quarry stones and various special-shaped stones. Experiment has been carried out on the parametric relations among wear form, cutting liner speed and tightening force of diamond wire according to the experimental result of diamond wire-saw in quarrying Shidao Red granite with high efficiency. The suitable working parameters of diamond wire-saw in granite cutting are discussed in the paper, the purpose of which is to improve productivity and quality, and to reduce the cost of the diamond wire-saw as well as to make good
use of advantages of diamond wire-saws. Practice proves that diamond wire-saw is an ideal equipment with high economy index in quarrying granite.
Cutting Force Model for Contour Surface Machining of Gear Indexing Cam with Flat End Milling
Authors: Guo P.Q. , Huang Chuan Zhen , Zhao Ping
Published: March 2009

This paper presents a model to predict the cutting forces for flat end milling as machining gear indexing cam. Rotation feeding makes axial depth of cut and uncut chip thickness change during cutting process. The development of the model is based on the analysis of cutting edge expression. According to the existing the relationship of the local cutting force and chip load and assuming the cutter to be divided into a number of differential elements in the axial direction of the cutter, the model is derived by summarising the cutting forces produced by each differential cutter disc engaged in the cut. The equation for calculating uncut chip thickness of differential disc is educed. In order to avoid the complex computing for axial depth of cut of the entire edge, a unit square window function and its criterion are introduced to estimate whether a segment of edge is in engaging range.
Local Region Mahalanobis Distance Feature and Its Application in Monitoring Wearing and Breakage States of Cutting Tools
Authors: Ji Shi Ming , Zhang Li , Wan Y.H. , Zhang X. , Yuan Ju Long , Zhang L.B.
Published: March 2009

The Mahalanobis distance feature proposed by P.C .Mahalanobis, an indian statistician. In this paper, we propose a new concept, Local Region Mahalanobis Distance feature –LRMD feature, we shall discuss the structure form, the obtaining methods of LRMD feature from an image and the relations between the LRMD feature and wearing and breakage states of cutting tools. The new research results indicate that the method of automatic on-line cutting tool condition monitoring based on LRMD feature can has better inspect result than the method of Mahalanobis Distance feature.
Growth of Nanocrystalline Diamond Films on Co-Cemented Tungsten Carbide Substrates by Hot Filament CVD
Authors: Sun Fang Hong , Zhang Zhi Ming , Shen H.S. , Chen Ming
Published: March 2009

Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using CH4/H2/Ar gas mixture by hot filament chemical vapor deposition (HFCVD) technique. The evidence of nanocrystallinity, smoothness and purity was obtained by characterizing the sample with scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM) and selected-area electron diffraction (SAED). A new process was used to deposit composite diamond films by a two-step chemical vapor deposition procedure including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond. The results show that the film consists of nanocrystalline diamond grains with sizes range from 20 to 80 nm. The Raman spectroscopy, XRD pattern, HR-TEM image and SAED pattern of the films indicate the presence of nanocrystalline diamond. Surface roughness is measured as Ra<100nm by AFM.
Smooth nanocrystalline diamond layers can be deposited on conventional microcrystalline diamond layers using a two-step chemical vapor deposition by regulating the deposition parameters. These composite diamond films with the multiplayer (nanocrystalline/microcrystalline) structure have low surface roughness and high adhesive strength on WC-Co substrates. The diamond-coated tools and drawing dies with these composite coatings display excellent performances in the practical application.
Mechanism of Electrode Material Removal in Short Pulse Time Electric Discharge Machining
Authors: Wang Zhen Long , Cui Jing Zhi , Liu X.F. , Zhao Wan Sheng
Published: March 2009

In electric discharge manufacturing, especially to the complex part finishing machining, electrode wear effects the electrode’s life-span and the work pieces precision in both dimension and geometry. Although it is more difficult to explain the exact mechanism of metal erosion in sparking, the basic phenomenon that the work materials near the channels melted, vaporized, and then flushed off in the dielectric liquid has suggested that the mechanism of electrode wear is based on a thermal
conduction process governed by heat generating from arc channels and dissipating into the tool and the work. On the basis of a review of the other researchers’ work and analysis to the thermal conduction phenomenon, this paper presents an electrode wear model based on heat conduction. Finite element is employed to solve the heat conduction model of wear, and in addition, a theoretic planar sunken function at electrode surface impacted by plasma flow is established. Some
experiments and simulations are made to verify the hypothetic model, and the conclusions that the simulation result of erosion figure and erosion trend of the material are correspond to the hypothetic model are confirmed.
Numerical Simulation of Sheet Deforming Caused by Laser Shocking
Authors: Zhou Jian Zhong , Zhang Yong Kang , Zuo Dun Wen , Yang Chao Jun , Cai Lan
Published: March 2009

Laser shock forming (LSF) is a new technique realized by applying a compressive shock wave generated by laser shocking on the surface of sheet metal. It is a mechanical, not a thermal process. After briefly reviewing the mechanism of LSF, instead of previously reported experimental research, a numerical simulation method of sheet deforming caused by laser shock waves is presented. The process of laser-shock plastic deforming of sheet metal is simulated with ABAQUS software, the simulation results are compared and agree well with the experiments on the condition of single laser shocking. It is shown that numerical simulation is available for optimizing laser parameters and predicting the sheet deformation contour of laser shock forming process.
Intercalation of Lithium Into Graphite as the First Step to Produce Carbon Nano-Tubes in an Electrochemical Way
Authors: Sytchev J. , Borisenko N. , Kaptay György
Published: March 2009

The mechanism of lithium electrochemical reduction from its molten chloride at two
different electrodes – glassy carbon and graphite – has been investigated by the cyclic voltammetry method in terms of so-called ‘thermodynamic’ or ‘material balance’ reversibility. It has been shown that the adsorption of lithium on glassy carbon and graphite plays an important role in the overall process of reduction, especially at polarization rates below 1 V/s. Lithium intercalation, probably due to small lithium atomic radius, practically does not have influence on the reversibility at these polarization rates. The process of lithium deposition on the electrodes used may be complicated by the dissolution of lithium in the melt in the whole range of polarization rates applied.
Reactor Pressure Vessel Integrity in Light of the Evolution of Materials Science and Engineering
Authors: Trampus Péter
Published: March 2009

Structural integrity of the reactor pressure vessel of pressurized water reactors is
one of the key safety issues in nuclear power operation. Integrity may be jeopardized during operational transients. The problem is compounded by radiation damage of the vessel structural materials. Structural integrity assessment as an interdisciplinary field is primarily based on materials science and fracture mechanics. The paper gives an overview on the service induced damage processes and associated changes of mechanical properties, the prediction of degradation and the assessment of the entire component against brittle fracture
with a special focus on how the evolution of materials science and engineering has
contributed to reactor vessel structural integrity assessment.
Basalt Fiber Reinforced Hybrid Polymer Composites
Authors: Czigány Tibor
Published: March 2009

Short fiber (basalt, carbon, ceramic, and glass) reinforced polypropylene hybrid
composites were investigated to determine their mechanical properties in case of different reinforcing fiber types. The composites were reinforced with fibers and were produced by hot pressing after hot mixing techniques. Composite properties such as flexural strength, stiffness, static and dynamic fracture toughness were measured. It was realized that the main damage modes of the composites are fiber pullout and debonding. It was also found that basalt fibers are the most sensitive to the lack of the treatment with additives. These results were supported by scanning
electron micrographs taken of the fracture surfaces.
Annealing Textures of Thin Films and Copper Interconnects
Authors: Lee Dong Nyung
Published: March 2009

Vapor-, electro-, and electroless-deposits have usually strong fiber textures. When
annealed, the deposits undergo recrystallization or abnormal grain growth to reduce their energy stored during deposition. The driving force for recrystallization is mainly caused by dislocations, whereas that for abnormal grain growth is due to the grain boundary, surface, interface, and strain energies. During recrystallization and abnormal grain growth, the texture change can take place. The recrystallization and abnormal grain growth textures are in general of fiber type. However, copper
interconnects are subjected to non-planar stress state due to geometric constraints during room temperature and/or elevated temperature annealing. The annealing textures of the thin films and copper interconnects are discussed in terms of the minimization of the surface, interface, and strain energies, the grain boundary energy and mobility, and the strain-energy-release maximization.
Studies on Nanostructured Polyurethane/Clay Interpenetrating Polymer Networks
Authors: Zhou Ninglin , Xia Xiao Xian , Li Li , Wei Shao Hua , Shen Jian
Published: March 2009

A novel exfoliated polyurethane (PU)/clay Interpenetrating Polymer Networks (IPNs) nanocomposite has been synthesized with polyurethane and organoclay. MTPAC is used as swelling agent to treat Na-montmorillonite for forming organoclay. The results indicate that there is very good compatibility between organoclay and PU. Nanoscale silicate dispersion was analyzed by XRD. The mechanical properties of the nanocomposites have been measured by tensile testing machine. The nanocomposites show obviously improved physical and mechanical properties when compared with the pure polymer. Additionally, PU /MTPAC- clay shows lower water absorption properties than pure PU do. In addition, the reinforcing and intercalating mechanism of silicate layers in polyurethane matrix are discussed.
Encapsulation of Nanometer CaCO3 by Polymer Network
Authors: Liu Wen Fang , Guo Zhao Xia , Yu Jian
Published: March 2009

Stearic acid coated nanometer CaCO3 was encapsulated by polystyrene (PS) network via emulsion polymerization, where a polyfunctional monomer trimethyol propane trimethacrylate (TMPTMA) or divinyl benzene (DVB) was used as crosslinker. The feed modes of monomer and initiator are investigated. Batch mode is shown to be more convenient than semi-continuous mode in view of network perfection. With the amount of crosslinkers increased from 1 wt% to 7 wt%, the
percentage of unextractable PS is high (not lower than 95%) for all samples in the system of TMPTMA, while this value decreases sharply from 74% to 3% in the system of DVB. The yield in the system of DVB is higher than that of TMPTMA. With increased amount of CaCO3, encapsulation ratio can be varied from 5.2 to 2.6, while the yield and unextractable PS decrease. FT-IR spectra of the products after extraction indicate tight encapsulation between PS and CaCO3, and TEM photographs of composite particles give direct evidence of encapsulation.
On-Line Wear Monitoring of Polymer Matrix Composites
Authors: Quintelier Jan , de Baets Patrick , Degrieck Joris , Ledda Alessandro , Philips W. , Sol Hugo , Van Hemelrijck Danny
Published: March 2009

The Laboratory Soete developed a new test setup, based on the well-known pin-on-disc test rig. Instead of the standard composite specimen and steel disc, a rotating composite disc and a steel pin is presently used to have a visible wear track. Other measurement techniques (Acoustic Emission, vibrations, temperature) can be used on the test rig. Continuous monitoring of the wear track combined with standard wear and friction measurements, give results of the current state of the wear track. Fourier frequency analysis (FFT) of these signals gives an indication of the change in condition and contact geometry of the resulting pin-disc combination. A high-speed camera will be used to acquire digital images of the worn composite surface. These online measurements yield to the gradual evolution in damage of the composite specimens.
Research on Electromechanical Properties of Cymbal Piezocomposite Transducer
Authors: Li Deng Hua , Li Ke , Cheng Yang
Published: March 2009

The electromechanical properties of cymbal piezocomposite transducer were investigated in this paper. Piezoelectric ceramic PZT—5A was used as piezoelectric phase of transducer, and brass foil was used as end cap electrode of cymbal piezocomposite transducer. Several types of this transducer were fabricated. The displacements of this transducer as functions of the applied force and the applied electric field were investigated. It was calculated and analyzed for the energy
transmission coefficient and electromechanical coupling coefficient of this transducer which optimum values were obtained.
Distribution of Mo at Grain Boundary of 1300MPa CrMo Steel
Authors: Yang W.G. , Zhang L.N. , Zhang X. , Hui W.J.
Published: March 2009

TEM, EDS and STEM were used to investigate distribution of Mo element in new CrMo steel ADF1 which is applied to 1300MPa high strength bolts with superior delayed fracture resistance. Research results reveal that Mo easily concentrates at grain boundaries. According to refined EDS point and mapping analysis, the region of Mo segregation at grain boundary is about several nanometers wide, and distribution of Mo along the grain boundary is not uniform. The average content of Mo at grain boundary is about double of that in grain area. Concentration of Mo
can increase the bonding force of grain boundary, and this is of advantage to the improvement of strength and delayed fracture resistance of the new CrMo steel.
Fracture Behavior and Its Shear Lag – Monte Carlo Simulation of SiC/SiC Composite Exposed in Air at High Temperatures
Authors: Morishita Kohei , Tanaka H. , Kimura Shigeru , Okuda Hiroshi , Ochiai Shojiro , Tanaka Masashi , Hojo M. , Nakayama H. , Sato M.
Published: March 2009

It has been reported that SiC/SiC composite has high strength and toughness, but is
degraded when exposed in air at high temperatures due to the propagation of the crack made by the premature fracture of the SiO2 layer. The present work aimed to describe such a behavior with a computer simulation. For this aim, the shear lag - Monte Carlo simulation method was applied. The variation of strength of the composite as a function of thickness of the SiO2 layer and change of fracture morphology with progressing oxidation could be reproduced satisfactorily by this method.
Dynamic Visualization of Crack Tip Stress Field and Propagation Using the Mechano-Luminescence in SrAl2O4: (Eu,Dy,Nd)
Authors: Kim Ji Sik , Kwon Yong Nam , Sohn Kee Sun
Published: March 2009

The present investigation aimed at visualizing the propagating crack in a
mechano-luminescence (ML) material, which enabled us to measure instantaneous R-curves and observe directly the bridging (shielding) stress in the fast-propagating crack system. The well-known ML compound, SrAl2O4:Eu,Dy,Nd, was adopted as a testing material. The crack initiation and growth from the mechanically machined sharp notch tip in the disc shaped compact tension (CT) specimen at a relatively fast loading rate were found to be associated with the extent of light emission around the crack. The in-situ measurement of crack length and applied load for 0.3 sec yielded an instantaneous R-curve at the conventional crack propagation speed.
Synthesis and Photoluminescence of Eu3+ Doped Sr2CeO4 via Carbonate Precursor
Authors: Shi Shi Kao , Li Jun Min , Zhou Ji
Published: March 2009

Carbonate precursor of Eu3+ doped Sr2CeO4 is obtained from a mixed solution of strontium, cerium and europium nitrate using ammonium carbonate as precipitant. Calcining the carbonate precursor at different temperatures, the Eu3+ doped Sr2CeO4 phosphor is synthesized. The phase purity of the material is closely related with the calcination temperature, and the phosphor with high purity can be achieved after the precursor annealed at 1200°C. The photoluminescence performance for Eu3+ doped Sr2CeO4 depends on the concentration of Eu3+. The excitation and emission reveal efficient energy transfer from Ce4+ to Eu3+, making the emission light from blue-white to red-white, further to red as the Eu3+ concentration gradually changes from low concentration (1 mol%) to high
concentration (10 mol%).
Preparation, Phase Transformation and Dielectric Properties of Aluminum Phosphate Compounds
Authors: Wang Xin Peng , Tian Shi
Published: March 2009

Reaction between nanometer γ-Al2O3 and H3PO4 to form AlPO4 by hydro-thermal
method was studied. The microstructure of the reaction product was examined by SEM (scanning electronic microscope). The phase transformation of AlPO4 was investigated by DSC (differential scanning calorimeter) and XRD (X-ray Diffraction). The relative dielectric constant and dielectric dissipation factor of different kinds of aluminum phosphates were measured. Results of the study led to the optimal parameter of the reaction and showed that aluminum phosphate is a good matrix to make functional ceramic-matrix composites.
Study on the Cracking of SiO2-TiO2 Films Prepared by Sol-Gel Method
Authors: Zhou Feng , Liang Kai Ming , Shao Hua
Published: March 2009

In this paper, the cracking behavior of sol-gel-derived SiO2-TiO2 films on glass-ceramics substrates is characterized by means of DTA, XRD and SEM. The SiO2-TiO2 films are deposited by sol-gel dip coating with tetrabutyl orthotitanate (Ti(OBu)4) and tetraethyl orthosilicate (TEOS) as raw precursors. The result shows that the cracking of the films is mainly related to the surface cleanliness of the substrate, the thermal expansion coefficients of the film and the substrate, the
viscosity of the mixed sol, and the unbalanced stress produced during drying and heating process. The films without cracks were obtained by modifying the composition of sol and controlling the relative humidity and the heating rate of heat treatment.
Dislocation-Precipitate Interaction and Its Effect on Thermostability of Bainite in a Nb-Bearing Steel
Authors: Yang Shan Wu , Wu Hui Bin , Yuan S.Q. , Shang Cheng Jia , Wang Xue Min , He Xin Lai
Published: March 2009

After bainitic transformation, the dislocations formed in deformed austenite remained to be pinned by the precipitates so that thermostability of the bainitic ferrite was improved. Coarsening of the precipitates accompanied by their distribution density change occurred during reheating. After long reheating, further precipitates nucleated in bainite. Dislocations inside laths getting rid of pinning of precipitates and their polygonization play the precursor to the evolution of microstructures, in which lath boundaries disappeared gradually.
Ti3AlC2 — A Soft Ceramic Exhibiting Low Friction Coefficient
Authors: Zhai Hong Xiang , Huang Zhen Ying , Zhou Yang , Zhang Zhi Li , Li Shi Bo , Wang Yi Fan
Published: March 2009

The friction behavior of a high-purity bulk titanium aluminum carbide (Ti3AlC2) material dryly sliding against low carbon steel was investigated. Tests were performed using a block-on-disk type high-speed friction tester under sliding speed of 20 m/s and 60 m/s, several normal pressures from 0.1 to 0.8 MPa. The results showed that the friction coefficient is as low as about 0.18 for sliding speed of 20 m/s and only 0.1 for 60 m/s, and that almost not changes with the normal pressure. The reason could be related with the presence of a surface layer on the friction surface. The layer was analyzed to consist of Ti, Al and Fe oxides, which played a lubricate part inducing the friction coefficient decrease on the friction surface.
Self-Lubricant Effect of Tri-Oxidizing Layer in Surface of Bulk Ti3SiC2 Materials
Authors: Zhang Zhi Li , Zhai Hong Xiang , Huang Zhen Ying , Zhou Yang , Li Shi Bo
Published: March 2009

In this paper, tribological tests for Ti3SiC2 sliding against low carbon steel were made on a block-on-disc type friction tester, with the normal pressures from 0.1 to 0.8 MPa and the sliding speed of 30 to 50 m/s. The surface state was observed and analyzed by SEM and XRD. A definite tribo-glazing layer was found over the worn surface of the Ti3SiC2 block, which seems to be primary reason for Ti3SiC2 to have comparatively lower friction coefficient and wear rate, because the tribo-glazing layer would be fusible under high frictional temperature. The tribo-glazing layer was the results of tribo-chemical oxidation reaction and the cause forming it could be the high frictional temperature and the mechanical catabolism in the surface of Ti3SiC2 during sliding friction. Due to the tribo-oxidation reaction is un-reversible and self-adaptive, the tribo-glazing layer in area and thickness are function of normal pressures and sliding speed.
Effect of Different Abrasive Particle Hardness on the Erosion Resistant Performance of α-Al2O3 Ceramics
Authors: Bao Chong Gao , Pan Wei , Miao He Zhuo
Published: March 2009

The erosion resistance of α-Al2O3 ceramics in flowing suspensions of solid particles was investigated with a rotary disk erosion wear tester. The effect of different abrasive particle hardness on its erosion resistance was studied and the microcosmic failure mechanism of its surface was analyzed. The results show that the erosion resistance of α-Al2O3 is more and more excellent than that of the metal Cr15Mo3 with the hardness enhancement of the abrasive particles. When SiO2,
Al2O3, SiC is in turn selected as the abrasive, the erosion resistance of α-Al2O3 ceramics is 4.06, 5.20, 5.77 times than that of Cr15Mo3 respectively due to the different hardness of such abrasives. Due to erosion, Cr15Mo3 is worn out most in the whole, the erosion holes are very clear and its failure pattern is in “W” shape. The wear of α-Al2O3 mainly occurs in the binding phase of the crystal boundary for its grain is fine and dense enough. So although the crystal grains are exposed at
last, no breaks and cracks can be found on the erosion surface. Its failure pattern is in “U” shape.
Joining of Cf/SiC Ceramic Matrix Composite Using SiC-Si3N4 Preceramic Polymer
Authors: Liu Hong Li , Li Shu Jie , Chen Zhi Jun
Published: March 2009

Carbon fibre reinforced SiC (Cf /SiC) as a promising high temperature structural material possesses broad prospects for aeronautical and astronautical applications. Joining technique is very important from both technical and economical points of view. Joining of Cf/SiC to itself has been realized by reaction joining process using a preceramic polymer, polysilazane, as joining material (welding compound). The weld strength of joints is strongly affected by joining temperature and number of times of reinforcement, which comprises infiltration and pyrolysis of polysilazane.
Samples were joined at temperatures ranging from 1100oC -1400oC. The maximum weld strength of joints is obtained at 1250oC. The reinforcement can remarkably increase the weld strength of joints. After three times of reinforcement the shearing strength of joints reaches 27.78MPa. Microstructural study and phase analysis reveal that the joining material has transformed into an amorphous ceramic interlayer composed of Si, C and N at 1100~1250oC, which is uniform and densified. The thickness of the interlayer is 2-3µm. The contact at the interfaces is good without
obvious cracks and pores. The amorphous ceramic interlayer transforms into crystal SiC and Si3N4 at 1400oC.
Study on Phase Transformation and Microstructure Development of Yb α-SiAlON Ceramics Prepared by Pressureless Sintering
Authors: Liu G.H. , Chen Ke Xin , Zhou He Ping , Ferreira José Maria F.
Published: March 2009

In this paper, single-phase Yb α-SiAlON ceramics were prepared by pressureless sintering and the densification, phase transformation as well as microstructure development were studied. It was demonstrated that the phase transformation could be completed at 1700 °C and elevated temperature was beneficial to grain growth. Additionally, effect of the addition of seed crystals prepared by combustion synthesis was discussed. From the experimental results, it was found that the
added seed crystals facilitated the phase transformation and improved the microstructure development, resulting in the formation of elongated grains.
Processing and Microstructure of an All-Oxide Ceramic Composite
Authors: Chen Z.C. , Kulkarni R. , Chawla Krish K. , Koopman M. , Ikeda Kazutaka
Published: March 2009

An all-oxide composite consisting of alumina fiber, alumina matrix, and barium zirconate interphase has been investigated. The barium zirconate interphase was applied on alumina fibers through coating via a sol-gel route. The incorporation of the coatings did not significantly influence the densification behavior of the composite under hot-pressing conditions. During the processing of the composite, the barium zirconate reacted in situ with alumina fiber and alumina matrix to form
Ba-β-alumina platelets with an elongated morphology, which is propitious for crack deflection and thus toughness enhancement. The results reveal that it is possible to reduce fiber strength degradation by controlling the coating and densification processes.
Material Processing and Testing of Plasma-Interactive Components for Fusion Energy Systems
Authors: Smid Ivi
Published: March 2009

In a global effort, the key players have combined their R&D forces to work jointly on the next generation thermonuclear fusion device. The development of structural, heat-sink and armor materials for plasma interactive components is focusing on neutron irradiation damage, and its impact on property retention and component integrity. Consequently, the processing of materials, realistic component testing methods as well as modeling are being optimized to suit the newest design concept(s). Nondestructive inspection of components is now available at an accuracy needed to ensure long service in a harsh, nuclear environment. The most promising materials and best established manufacturing processes are described; the proposed qualification techniques for fusion in-vessel and heat removal systems are reviewed.
Development of Tungsten Coatings for Application in Fusion Experiments
Authors: Maier Hans
Published: March 2009

In the development of nuclear fusion into a future peaceful energy source, the scheme of magnetically confined fusion plasmas has experienced substantial progress in the last decades. Some of the main remaining materials issues are the high heat loads and the erosion of plasmafacing components by erosion from particle impact. Since component lifetime considerations and the negative influence of impurities on the plasma lead to opposite conclusions about the materials choice, an experimental investigation of the applicability of tungsten as plasma-facing material is currently performed at the tokamak fusion experiment ASDEX Upgrade in Garching, Germany. For this purpose an industrial scale method to coat graphite tiles with tungsten thin films was required. Therefore a comparative study of the heat load behaviour of coatings deposited with various PVD techniques was performed. Tungsten coatings on graphites and fiber reinforced carbons were investigated with respect to their properties relevant for fusion research including electron-beam loading with heat loads exceeding 20MW/m2.
Effects of Pb on SCC of Alloy 600 and Alloy 690 in Prototypical Steam Generator Chemistries
Authors: Lumsden Jesse , McIlree Allan , Eaker Richard , Thompson Rocky , Slosnerick Steve
Published: March 2009

Intergranular attack/stress corrosion cracking of Alloy 600 continues to be an issue
in the tube/tube support plate crevices and top of tubesheet locations of recirculating steam generators and in the upper bundle of free span superheated regions of once through steam generators (OTSG). Recent examinations of degraded pulled tubes from several plants suggest possible lead involvement in the degradation. Laboratory investigations have been performed to determine the factors influencing lead cracking in Alloy 600 and Alloy 690 steam generator tubes. The test environment is believed to be prototypical, with the addition of lead oxide, of a concentrated liquid phase existing in the pores of thin deposits on upper bundle tubes of an OTSG. Highly strained reverse U-bend specimens were tested at controlled electrochemical potentials. Maximum susceptibility was at open circuit potential, unlike cracking of Alloy 600 in caustic and acid sulfate environments where maximum susceptibility occurs when specimens are polarized above the open circuit potential. Transgranular, intergranular and mixed mode cracking was
observed and in all Alloy 600 conditions tested (mill annealed, sensitized, thermally treated) while thermally treated Alloy 690 has so far resisted cracking. A film rupture/anodic dissolution model with displacement plating of Pb preceding passive film formation is consistent with the experimental observations
Creep Resistance of Zr-Sn-Nb-Fe-Cr Alloy
Authors: Li Zhongkui , Wang Wen Sheng , Zhang J.J. , Zhou Lian
Published: March 2009

The creep resistance of one kind of Zirconium based alloy with Niobium, Iron,
Chromium , Tin alloying elements was investigated, the creep curve ( e-t) was obtained in stress levels of 117MPa 、137MPa、157MPa respectively by holding 200 hours at 400°C. The results show that the creep resistance of this alloy is much better than that of Zircaloy-4. The microstructure of post- creep test was observed by TEM, which shows that the dislocation morphology is changed from dislocation lines to dislocation cells with strain increasing , and some precipitates grow larger. It is concluded that the creep is controlled by dislocation climb-glide diffusion mechanism.
Features of Swelling in Modified Austenitic Steels
Authors: Voyevodin V. , Bryk V. , Borodin O. , Neklyudov I.M. , Akasaka N. , Onose S.
Published: March 2009

Results of analysis of swelling behaviour of alloying austenitic steels are described from the point of view of the cooperative interaction of defect structure, solid solution decay and precipitates evolution.
The Microstructure of Pure Copper after Stepwise Change of Irradiation Temperature
Authors: Sumino Y. , Watanabe H. , Yoshida Naoaki
Published: March 2009

In order to investigate the effect of stepwise change of irradiation temperature on pure copper, heavy ion irradiations under constant temperature and varying temperature conditions were performed. Specimens were irradiated up to 10dpa. In the temperature region of 473K ~ 673K, one-step temperature variation and periodic temperature variations were performed during irradiation. The resulting microstructures were compared with those induced by the irradiation at the constant temperature of 673K.
Dynamic Recrystallization of Ferrite in a Low Carbon Nb-Microalloyed Steel
Authors: Li Long Fei , Yang Wang Yue , Sun Zu Qing
Published: March 2009

The hot deformation behavior of a low carbon Nb-microalloyed steel is investigated by hot compression test in the ferrite phase region compared with a low carbon steel with similar compositions, and the effect of Nb on dynamic recrystallization of ferrite is analyzed. Results indicate that during hot deformation in the ferrite phase region, the effect of Nb solely depends on the size of NbC precipitates. Tiny particles which average size is about 7.5nm have a retarding effect on dynamic recrystallization process of ferrite, on the contrary, coarser particles which average size is about 30.6nm have a promoting effect and are of benefit to the refinement of recrystallized grains.
Ternary Ceramics Ti3SiC2: Combustion Synthesis and the Reaction Mechanism
Authors: Huang Tsung Yen , Chen Chien Chong
Published: March 2009

In this study, Ti3SiC2 was successfully synthesized by the combustion of green samples with a composition formula: (3-x)Ti/Si/(2-x)C/xTiC, where x ranged from 1.0 to 1.8. First, the Ti3SiC2 yield monotonically increased with x, but the maximal yield was less than 50%. The most important factor to increase the Ti3SiC2 yield was found to be the post-combustion heating. The yield dramatically increased to about 90% when a 150-second post-combustion heating time was provided. Furthermore, the yield was proportional to the post-heating time, and linearly increased with the amount of applied post-combustion heating energy. Next, excess Si in the starting reactant powders can further increase the extent of Ti3SiC2. When the mole of Si increased from 1.0 to 1.1, the resulted yield was more than 99%. For the study of reaction mechanism, analyses of sequential layers of quenched samples resulted in the following proposed mechanism. First, TiC, TiSi2, Ti5Si3 were formed from the reactions of Ti, Si and C powders. Next, the eutectic liquids (Ti-Ti5Si3 and Si-TiSi2) covered the TiC particles at the elevated temperature. In the final stage, product Ti3SiC2 was resulted from heating the eutectics and TiC. It is noted that the last two steps required large energy, indicating the post-combustion heating was crucial to produce high-purity Ti3SiC2 product.
Prediction of Flow Stress and Microstructural Evolution during Hot Forging of Three Microalloyed Medium Carbon Steels
Authors: Yoo Yeon Chul , Kim S.I. , Byon Sang Min , Lee Young Seog
Published: March 2009

A constitutive relation is proposed in this study by introducing a function prescrbing the volume fraction of dynamically recrystallized grains into the Voce’s equation to predict the stress-strain relations for three microalloyed medium carbon steels. We performed hot torsion test in temperature range of 900-1100 and strain rate range of 0.05-5.0s-1 to obtain the flow stress-strain curves. The calculated flow stresses are in good agreement with the measured ones. We have then applied the equations in FE analysis to predict the distribution of dynamic recrystallization volume fraction and flow stress for hot forging.
Magnetic Properties and Magnetostriction of ZnxNi1-x MnSb Alloys
Authors: Ren S.K. , Ji G.B. , Huang Song Ling , Cao Q.Q. , Zhang Feng Ming , Du You Wei
Published: March 2009

We have investigated the magnetic properties and magnetostriction of ZnxNi1-xMnSb compounds prepared by solid state reaction method. It is found that for x less than 0.6 the magnetization of ZnxNi1-xMnSb almost remains unchanged. However, when x is larger than 0.6 the magnetization starts to drop linearly. Experimental result indicates that at low Zn concentrations, x < 0.7, the Curie temperature (TC) decreases with increasing Zn concentration x. However, when x > 0.7, the Curie temperature increases distinctly with increasing x. The Zn concentrartion dependence of magnetostrictive ceofficient is also studied. The experimental curve shows that when x < 0.6 the value of magnetostriction coefficient for ZnxNi1-xMnSb decreases linearly with the increasing Zn
concentration x. However, when x is above 0.6, the magnetostrictive ceofficient raises distinctly. By analyzing the XRD pattern, the structures of the materials are examined and the relationship between the properties and the structures are discussed. A structural phase transition is observed. It has been indicated that the structure plays an important role in the magnetic and magnetostrictive properties of the system.
Strain Change and Creep Behavior of STACIR/AW Power Line with Heat Exposure
Authors: Kim Byung Geol , Park Su Dong , Kim Shang Shu , Lee Hee Woong
Published: March 2009

As a way to expand electric capacity in power line with hovering of electric power demand, STACIR/AW (super thermal-resistant Al alloy conductors Al-clad Invar-reinforced) overhead conductor which cans double ampacity has been developed. The STACIR/AW power line is mechanically composite stranded wire composed of INVAR/AW stranded wire as core for sag control and heat-resistant aluminum alloy for delivering doubled electric current. Recently, in order to ensure stable line operation and to predict its span of life, the changes of thermal properties for STACIR/AW have been investigated. In the present work, the changes of strain with temperature and the creep behavior as important factors in sag control will be presented. The transition temperature of STACIR/AW 410sqmm was estimated approximately 130°C and the creep rates were decreased with temperatures.
The Structural and Photoluminescence Character of InAs Quantum Dots Grown on a Combined InAlAs and GaAs Strained Buffer Layer
Authors: Shi G.X. , Xu Bo , Jin P. , Ye X.L. , Cui C.X. , Zhang C.L. , Wu J. , Wang Z.G.
Published: March 2009

The structural and photoluminescence (PL) properties of the InAs quantum dots (QDs) grown on a combined InAlAs and GaAs strained buffer layer have been investigated by AFM and PL measurements. The dependence of the critical thickness for the transition from 2D to 3D on the thickness of GaAs layer is demonstrated directly by RHEED. The effects of the introduced-InAlAs layer on the density and the aspect ratio of QDs have been discussed.
The Texture and Property of Diffusion Barrier of TiN Thin Films
Authors: Sung Dong Young , Kim In Soo , Lee Min Gu , Yang Bee Lyong , Yang Jun Mo , Ko Jung Kyu
Published: March 2009

The uniform and dense structure of thin films is influenced by the texture of films. It was good to have uniform and dense structure and bad to have an open columnar structure in TiN thin films. Therefore, the property of diffusion barrier of the TiN films in semiconductor also is related to the texture and microstructure of TiN coated layers. In this study, the relationships between the textures and microstructures and the properties of TiN films on semiconductor were investigated under different processing methods (PVD and MOCVD). The property of diffusion barrier of RF
sputtered (PVD) TiN is better than that of metal organic chemical vapor deposited (MOCVD) TiN thin films. Also the property of diffusion barrier of PVD (111) textured TiN is better than that of PVD (100) textured TiN thin films on oxidized Si wafer.
Changes of Fatigue Property with Heat Exposure in INVAR/AW Wire
Authors: Kim Shang Shu , Park Su Dong , Kim Byung Geol , Lee Hee Woong , Sin Goo Yong , Lee Dong Il , Min Byung Uk
Published: March 2009

Fatigue properties of INVAR/AW wires have been investigated under the heat exposure in order to ensure stable operation and to estimate life span of their power line. In the case of heat exposure for 1000hr, fatigue life and limit increased. For further heat exposure, fatigue limit decreased due to the decrease in yield strength. The variation fatigue of strand wire was strongly dependent on its amplitude. Also, cracks in wires of 7 strands were caused by stress concentration at the outer surface and fretting between each wire during vibration.
Carbon Nanotube Field Emitters for Display Applications Using Screen Printing
Authors: Jung Hyuck , Lee Duck-Jin , Chun Hyun-Tae , Koh Nam-Je , Cho Young Rae , Lee Dong-Gu
Published: March 2009

In this study, a 10"-sized panel with novel tetrode structure was tried to prevent broadening of electrons emitted from CNTs. The structure of the novel tetrode is composed of CNT emitters on a cathode electrode, a gate electrode, an extracting electrode coated on the top of a hopping electron spacer (HES), and an anode. HES contains funnel-shaped holes whose inner surfaces are coated with MgO. Electrons extracted through the gate are collected inside the funnel-shaped holes and hop along the hole surface to the top extracting electrode. The effects of HES on emission characteristics of field emission display (FED) were investigated. An active ozone treatment for the complete removal of residues of organic binders in the emitter devices was applied to the FED panel as a post-treatment
The Effect of Si on the Toughness of High Strength Mn-Si-Cr Series Bainitic Steels
Authors: Tan Zhun Li , Bai Bing Zhe , Fang Hong Sheng , Yang Fu Bao
Published: March 2009

The relationship between the toughness and silicon content of high strength Mn-Si-Cr series bainitic steels has been investigated. The results show that with increasing in silicon content, the onset temperature of the steel’s tempered martensite embrittlement (TME) rises; moreover, the minimum value of tested toughness decreases and the tempering temperature corresponding to the minimum value of toughness increases. This phenomenon results from the effect of silicon on the stability of filmy carbon-enriched retained austenite in carbide-free bainite/martensite (CFB/M) microstructure.
Study on Manufacture of 2:17 Sm-Co Magnets by Powder Injection Molding
Authors: Yin Hai Qing , Jia Cheng Chang , Qu Xuan Hui
Published: March 2009

Manufacture of 2:17 Sm-Co magnets by powder injection molding was investigated. The binder of thermoplastic polymer was selected as the wax-based system including paraffin wax, stearic acid and high density polyethylene. Before mixing with paraffin wax and high density polyethylene, the powder of 5-8 µm was coated by stearic acid. The molding compacts were obtained under 200°C without deficits. Solvent debinding and thermal debinding were combined to remove the binder. The basic magnetic characteristics of the specimen were of the same level as those by powder metallurgy technique, which indicated that to fabricate 2:17 Sm-Co magnets by powder injection molding was feasible.