bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the Duration of Potentiostatic Anodizing on the Corrosion Resistance and Surface Morphology of Films Formed on Mg-Al Alloys
Authors: Kim Seong Jong , Jang Seok Ki , Kim Jeong Il
Published: March 2009

The effects of the duration of potentiostatic anodizing on the corrosion
resistance and surface morphology of anodic oxide films formed on Mg-Al alloy
(AZ91) in 1 M NaOH were investigated. With the formation of an anodic film, the
current density decreased gradually, started to stabilize at 300 s, and was relatively
constant at 600 s. These results may be related to the increased time for catalysis of the active dissolution reaction, which not only enlarges the area covered by the anodic film, but also produces a more coherent, thicker film. The reference corrosion potentials of the anodic oxide film for AZ91 shifted in the noble direction with time. In general, the corrosion resistance characteristics were improved with anodizing time.
Effect of Hydrogen Peroxide on the Photocatalytic Decomposition of 4-Nitrophenol over TiO2/Cr-Ti- MCM-41 Catalysts in Visible Light
Authors: Lee Gun Dae , Do Y.J. , Park Seong Soo , Hong Seong Soo
Published: March 2009

Cr, Ti-substituted TiO2-loaded MCM-41 (TiO2/Cr-Ti-MCM-41) catalysts were prepared, and their photocatalytic activities for decomposition of 4-nitrophenol (4-NP) in visible light were studied. The effect of H2O2 on the photocatalytic decomposition of 4-NP was investigated. Tisubstituted MCM-41 exhibited an absorption in UV range, and the incorporation of both Ti and Cr in the MCM-41 framework created visible light absorption. The visible light absorption capability
of TiO2/Cr-Ti-MCM-41 increased with increasing TiO2 loading. The photocatalytic activity of Cr- Ti-MCM-41 for degradation of 4-NP in visible light increased with increasing TiO2 loading up to 33 wt%. The addition of H2O2 enhanced the photocatalytic activity of 33 wt% TiO2/Cr-Ti-MCM-41 for decomposition of 4-NP in visible light. H2O2 was found to promote the adsorption of 4-NP on the
Cr-Ti-MCM-41 surface, leading to increased reaction rate. In addition, H2O2 may act as an electron acceptor during photocatalytic reaction, thereby lowering the electron-hole recombination and increasing the efficiency of hole utilization.
Self-Lubricating Composite Coating on Air Foil Bearing Shaft by Hollow Cathode Plasma Jet
Authors: Yang Min Kyu , Yang Hyu Seung , Park Jong Ku , Ryu Keun , Lee Yong Bok , Lee Jeon Kook
Published: March 2009

The self-lubricating composite films were deposited on Inconel 718 by Hollow Cathode Plasma Jet (HCPJ). These composite materials consist of chrome nickel alloy matrix and Ag, BaF2/CaF2 solid lubricants. The Cr2O3-NiCr-Ag composite thin film was crystallized and had the main peaks of Cr2O3 (012) and Ag (111). The deposition rate of 200 nm /min by HCPJ was much
faster than the ordinary R.F planar magnetron sputtering. The surface roughness of coated shaft was 30 nm.
Tribological Behaviors of Al2O3/SiC Nanocomposites during Dry Sliding
Authors: Kim Seung Ho , Sekino Tohru , Niihara Koichi
Published: March 2009

Tribological behaviors of Al2O3/SiC nanocomposites were found to be related to the
amount of nanosized SiC and initial Hertzian contact stress. As the applied load increased, the wear volumes of Al2O3/SiC nanocomposites slightly increased, but that of monolithic Al2O3 increased rapidly above 50 N. Tribological behavior of monolithic Al2O3 was transited from mild wear to severe wear.
In-Vitro Hertzian Fatigue Properties of Glass Infiltrated Ceramic Composites for Dental Crowns
Authors: Song Yo Seung , Park Il Seok , Jang Ju-Woong , Lee Deuk Yong , Lee Se Jong
Published: March 2009

Hertzian cyclic fatigue properties of the glass-infiltrated alumina and spinel were
evaluated using a WC sphere of radius of 3.18 mm in exact in vitro environment (artificial saliva) at contact loads from 200 N to 1000 N to investigate indentation damage and strength degradation. At 200 N, no strength degradation was observed up to 106 contact cycles. As the load increased from 200 N to 1000 N, the reduction in strength was found when the transition from ring to radial cracking
occurred. The degree of strength degradation after critical cycling was more pronounced probably owing to the chemical reaction of the artificial saliva with the glass phase along the radial cracks introduced during the large numbers of contact cycles.
Embrittlement Fracture in a 17-4 PH Stainless Steel after Aging at 400°C
Authors: You Wei , Lee Jung Hun , Shin Soo Keun , Choe Byung Hak , Paik Ung Yu , Lee Je Hyun
Published: March 2009

The embrittlement fracture mechanism caused by microstructural evolution of 17-4 PH stainless steel at long term aging was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The solution treated specimen consists largely of lath martensite with a small fraction of elongated δ-ferrite. The spherical particles existed a little in the martensite matrix, while no precipitates were present in the δ-ferrite at the solution treated specimen
as non-aging. The precipitation of Fe-Cu in the δ-ferrite causes the aged hardening after long term aging accormpanied by decreases in elongation and charpy V-notch energy absorption. The increased fraction of brittle fracture on the fractured surface by impact and tensile test reveals that the embrittlement of the 17-4 PH alloys during long term aging is mainly caused by the precipitation hardening in the δ-ferrite matrix.
The Effect of Pozzolanics on the Recycled Aggregates by Surface Treatment
Authors: Kim Jae Jun , Youn Sang Heum , Cho M.J. , Shin H.T. , Yoon Jeong Bae , Hwang Kyu Hong , Lee D.S.
Published: March 2009

To improve the mechanical properties of concretes containing recycled aggregates, pozzolanic materials such as Silica Fume and Meta Kaolin were used to decrease the porosity of the recycled aggregates. These pozzolanic aterials were adhered on the surface of recycled aggregates and closed the open pores so that the water absorption was decreased 1~2% as the amount of adsorption was increased. Compressive strength of cement mortars and concretes using surface treated recycled aggregates reached above 95% of the strength of its natural counterparts. Investigation of the microstructures using the scanning lectron micrographs showed the formation of dense interface after the adsorption treatment of pozzolanics to recycled aggregates.
Effect of Particle Size on the Extraction of Metallic Components from Oxidized PCB in High Frequency Induction Furnace
Authors: Lee Jae Chun , Jeong Jin Ki , Kwon Eui-Hyuk , Jang Sung Hwan , Han Jeong Whan
Published: March 2009

It is generally well known that PCB (Printed Circuit Board) is a complex mixture of various metals mixed with various types of plastics and ceramics. Accordingly, it is very important to extract metallic components from used PCB’s from the point of view of recycling the used resources as well as the environmental protection. In this study, a high temperature pyro-metallurgical process was investigated to extract valuable metallic components from the used PCB’s. For this purpose, used
PCB’s were shredded and oxidized to remove plastic materials, and then, a high frequency induction furnace was used to melt and separate metallic components in molten state from the remaining oxides. After the oxidation of the used PCB, 30.6wt% SiO2, 19.3wt% Al2O3 and 14wt% CaO were analyzed as major oxides, and thereafter, a typical composition of 32wt%SiO2-20wt%Al2O3-38wt%CaO
-10wt%MgO was chosen as a basic slag system for the separation of metallic components Moreover, in order to understand the size effect on the extraction of metallic components, oxidized PCB’s were further milled, and then, melted. As a result, it was found that the size of oxidized PCB’s was needed to be less 0.9mm to make a homogeneous liquid slag and to recycle metallic components over 95%.
Comparison of Transmittance of Pb-Free Transparent Dielectric Made by Screen Printer and Die Coater
Authors: Cha Myung-Lyoung , Jeon Jae Sam , Kim Hyung Sun
Published: March 2009

For the application of transparent dielectric layer of PDP (Plasma display panel), a Pb-free glass, ZnO-B2O3-SiO2 glass, was measured for thermal and optical properties after forming thick films. Glass frit of different size (d50=1.7, 4.3㎛) and different thickness film forming process (a die coater and a screen printer) were applied to a transparent dielectric. The coated layer was determined
for pore contents, size, and transmittance. As a result, the screen printing method produced non-uniform surface and increased pores with multilayer. The die coater method, however, produced more uniform surface and less pore content compared to the screen printing method. Thus it shows that the increase of pore size and contents has detrimental effects on the transmittance of thick films
made by a lead-free glass, ZnO-B2O3-SiO2 glass.
Alumina/Aluminum Composite Fabricated by Freeze and Dry Process with Water-Soluble Polymer Slurry
Authors: Nakata M. , Suganuma Katsuaki
Published: March 2009

To clarify the effects of parameters of porous ceramics form on the characteristics of composites fabricated by high-pressure infiltration, Alumina forms with different porosity (15~70vol %) and pore morphology were fabricated by Freeze and Dry Process and Partial Sintering Process. Alumina/aluminum composites were made by the squeeze casting. The composites contained the different volume fraction of aluminum depending on the initial porosity of the ceramics form. The coefficient of thermal expansion (CTE) and thermal conductivity of composites were measured. The results indicated clearly that variation of the structure of porous
ceramics form fairly affected CTE but the effects on thermal conductivity were small.
Microstructural Evolution of Electromagnetically Stirred Al Alloy during Isothermal Reheating in Solid-Liquid Region
Authors: Lee Dock Young , Kim Ki Bae , Kim Do Hyang
Published: March 2009

The effects of reheating in solid-liquid region on the microstructure of electromagnetically stirred Al alloy have been investigated. The billet of Al alloy was produced at a various casting speed from 200 to 500 mm/min in a continuous casting machine with an electromagnetic stirring device. The microstructure of the billet, which was isothermally reheated in a solid-liquid region during holding for from 0.5 to 15 min, was examined. The roundness and size of primary α phase of electromagnetic stirred Al alloy was measured according to the reheating time.
The roundness of primary α phase was obtained a minimum during holding for from 3 to 7 min at a holding temperature of 584°C and was deteriorated at a longer reheating time due to a dominant coalescence. Also the spheroidization of primary α phase during reheating in solid-liquid region was significantly dependent on initial microstructure of the billet.
Influences of Fiber Orientation on the Progressive Damage in Glass Reinforced Hybrid Composite
Authors: Kim Cheol Woong , Song Sam Hong , Oh Dong Joon
Published: March 2009

The anisotropy of hybrid composite such as Al/GFRP laminates made it possible to control the fiber orientation according to the loading patterns. Therefore, it is important to study the fatigue and delamination behaviors of Al/GFRP laminates by fiber orientation. Al/GFRP laminates of three different fiber orientations (0°, 45°, 90°) were chosen, and the progressive delamination behavior was examined through the fatigue tests. The effects of the fiber orientation on the crack length, the
fatigue life, the delamination, the crack growth rate (da/dN), and the stress intensity factor range ( ΔK) were investigated and discussed. The findings led to a conclusion that the effect of fiber orientation should not be ignored in analyzing the progressive damage of Al/GFRP laminates.
The Effect of Defect Locations on the Stress Distribution and Crack Initiation in Monolithic Aluminum vs. GLARE Hybrid Composite
Authors: Kim Cheol Woong , Song Sam Hong , Oh Dong Joon
Published: March 2009

This paper investigates the effect of the defect location on the stress concentration, the stress distribution, and the crack initiation behavior when the defects were made in the vicinity of the circular hole in the monolithic aluminum and the glass fiber reinforced laminates (GLARE). As the defect location in the vicinity of the circular hole was changed from ° = 90 4 q to ° = 0 1 q , the stress concentration was increased. Generally, the stress concentration of GLARE was about 15% greater
than that of the monolithic aluminum. When the defect was at ° = 30 2 q , Multi Site Damage (MSD) crack was found in the monolithic aluminum, but just the main cracks existed in GLARE. The delamination instead of MSD crack was made in GLARE, and it resulted in the prevention against the second crack initiation.
Processing and Microstructural Characteristics of Bi-Materials Composed of Al and Its Composite
Authors: Chang Si Young , Kim Jung-Gu , Kang Kae Myung
Published: March 2009

Both the Al-5wt%Mg powder mixture and Al-5wt%Mg/SiCp composite mixture were
separately ball-milled for 50h, followed by compaction under a pressure of 350MPa. To obtain the bi-materials, the compacted Al-5wt%Mg and Al-5wt%Mg/SiCp composites were bonded by sintering at 873K-1173K for 1-3h. At a relatively low temperature, 873K, the sound bi-materials could not be obtained. However, the bi-materials with the macroscopically bonded interface between Al-Mg and its composite were obtained at temperatures higher than 873K. The length of a well-bonded interface became longer with increasing temperature and time, indicating the improved contact in the bonded interface. The relative density in the bi-materials increased as the sintering temperature and time increased, and the bi-materials sintered at 1173K for 5h showed the highest density.
Effects of Si Content and Cold Rolling Condition on Brazeability of Al-Mn-Zn Alloy Core Brazing Sheet
Authors: Noh Si Joon , Kim Mok Soon , Jung D. , Han Jeong Whan , You Byung Don
Published: March 2009

Three layer clad brazing sheets composed of Al-7.5Si alloy (filler, thickness:10 ㎛
)/Al-1.2Mn-2Zn-(0.04-1.05)Si alloy (core, thickness:80 ㎛)/Al-7.5Si alloy (filler, thickness:10 ㎛), were produced by laboratory fabrication, through casting, hot rolling, cold rolling, intermediate annealing, and final cold rolling. The effects of Si content in the core(0.04-1.05wt.%) and reduction rate of the final cold rolling(10-45%) on microstructure and brazing behavior were investigated. The results revealed that the microstructure and brazeability of the brazing sheet are governed both by Si content in the core and by the reduction rate of the final cold rolling. The excellent brazeability was obtained when the core alloy has the Si content of/cold rolled to 0.04%/10-45%, 0.41%/20-45% and 0.64%/30-45%. In these cases, a coarse grain structure was developed in the core during the brazing process, which suppressed the penetration of melting filler into the core.
Sol-Gel Derived TiO2 Coating for Chemical Protection of Stainless Steel
Authors: Shin Dae Yong , Kim Kyung Nam , Han Sang Mok
Published: March 2009

Sol-gel coatings of TiO2 have been prepared from TiO2 sol and deposited by a dip-coating technique on 316L stainless steel sheets to study their electrochemical behavior in corrosive solutions. The influence of the coatings on the chemical corrosion of the substrate was evaluated by potentiodynamic polarization curves in different aqueous NaCl solution at 25°C. Comparative tests were performed on uncoated one. The thickness of the TiO2 coatings varied from 0.5~0.8 µm. The
values of the electrochemical parameters allow for an explanation of the role of the TiO2 films in the increased resistance of stainless steel against corrosion in moderately aggressive environments.
Influence of the Electromagnetic Stirring on Globularization of Primary Solid Phase in Solid-Liquid Region
Authors: Lee Dock Young , Kim Ki Bae , Kim Do Hyang
Published: March 2009

Forming of alloy and composite within a solid-liquid region, i.e. thixo-forming and
rheo-forming, has been recognized as a technology offering several potential advantages over casting and forging such as a low forming pressure, reduction of macrosegregation, and reduction of porosity. In this paper, a globularization for primary solid phase by a forced fluid flow in melt due to electromagnetic stirring during solidification and isothermal stirring at solid-liquid region, was
examined to produce Al alloy having a globular solid phase to get a thixotropic behavior. The electromagnetic stirrer was specially designed and manufactured to create all kind of fluid flow pattern such as a circumferential, vertical, helicoidally and contra-rotating flow pattern during the solidification of a melt. The size and roundness of primary solid phase of the quenched sample after isothermal stirring at solid-liquid region were measured with respect to a stirring time and frequency.
The globularization of solid phase was enhanced with incresing the stirring time and electromagnetic flux density, i.e. stirring strength.
Effect of PVP Addition on Microstructure of SrZrO3 Thin Films on Bi(2223) Tapes
Authors: Song Yo Seung , Lee Deuk Yong , Lee Se Jong , Kim Bae Yeon , Hong Shin Nam
Published: March 2009

SrZrO3 resistive oxides on Ag sheathed Bi(2223) tapes were prepared by the sol-gel and dip-coating method to investigate the effect of PVP content and thermal stage on microstructure of the films. Although film thickness rose with the addition of PVP, the amount of PVP was not effective to reduction in the crack density of the films. However, longer drying time at low temperature and shorter heat treatment time at 500oC were effective for controlling the microcracks of the SrZrO3
films, indicating that the microcracking of the films was governed primarily by the thermal stage.
Effects of MWNT and GNF on the Performance of Sulfur Electrode for Li/S Battery
Authors: Kim Jong-Hwa , Choi Young Jin , Jeong Sang Sik , Cho Kwon Koo , Kim Ki Won
Published: March 2009

We investigated the effects of multi-walled carbon nanotubes (MWNT) and graphitic nanofibers (GNF) on the performance of sulfur electrode for the lithium/sulfur battery. MWNT and GNF were manufactured by a thermal chemical vapor deposition (CVD) method, and then they were added as an additive in the sulfur electrode. The added sulfur electrodes were composed of
60wt% elemental sulfur (Aldrich), 20wt% acetylene black, 5wt% MWNT or GNF, and 15wt% poly ethylene oxide (PEO) dissolved in acetonitrile. No-added sulfur electrodes were prepared by mixing 60wt% elemental sulfur, 25wt% acetylene black, and 15wt% PEO. The addition of MWNT and GNF was found to give good electrochemical effects in sulfur electrode.
Orientation Distribution in Bi2Te3-Based Compound Prepared by Spark Plasma Sintering
Authors: Kim Ki Tae , Lim Cheol Ho , Kim Yong Hwan , Cho Dong Choul , Lee Young Sup , Lee C.H.
Published: March 2009

P-type Bi0.5Sb1.5Te3 compounds doped with 3wt.% Te were fabricated by spark plasma sintering after mixing large powders(PL) and small powders(PS). We could obtained the highest figure of merit(Zc) of 2.89×10-3/K in sintered compound mixed to PL:PS=80:20. This resulted from the increase of orientation by large powders(PS) and the reduce of pores by small powders. The figure
of merit(Zc) of the sintered compound using only small powders(PS) showed lower value of 2.67×10-3/K compared with that of sintered compound mixed to PL:PS=80:20 due to the increase of electrical resistivity.
Synthesis of Ni-YSZ Cermet for an Electrode of High Temperature Electrolysis by High Energy Ball Milling
Authors: Hong Hyun Seon , Chae Ui-Seok , Park Keun Man , Choo Soo-Tae
Published: March 2009

Ni/YSZ composites for a cathode that can be used in high temperature electrolysis were prepared by ball milling of Ni and YSZ powder. Ball milling was performed in a dry process and in ethanol. The microstructure and electrical conductivity of the composites were examined by XRD, SEM, TEM and a 4-point probe. XRD patterns for both the dry and wet ball-milled powders showed that the composites were composed of crystalline Ni and YSZ particles. The patterns did not change
with increases in the milling time up to 48 h. Dry-milling slightly increased the average particle size compared to starting Ni particles, but little change in theparticle size was observed with the increase in milling time. On the other hand, the wet-milling reduced the average size and the increasing milling time induced a further decrease in the particle size. After cold-pressing and annealing at 900 oC for 2 h, the dry-milled powder exhibited high stability against Ni sintering so that the particle size changed little, but the particle size increased in the wet-milled powder. The electrical conductivity increased after sintering at 900 oC. Particles from the dry and wet process became denser and contacted closer after sintering, providing better electron migration paths.
Application of Polymer Plating to Inhibit Corrosion of Magnesium Alloy
Authors: Kang Zhi Xin , Li Yuan Yuan , Mori Kunio
Published: March 2009

An organic compound of dihexyl-contained triazine dithiol was specially synthesized for surface modification of magnesium alloy AZ91 in order to improve its corrosion resistance. The nano-scale polymer film on the surface of AZ91 was created with the synthesized compound by means of electrochemical measuring system called as polymer plating in the electrolytic solution. The modified surface of AZ91 had the peculiar functional characteristic of water repellency to inhibit corrosion. Corrosion tests were carried out with methods of polarization curve and electrochemical impedance. The corrosion resistance was evaluated from corrosive current density
and reactive resistance. When concentration of the compound was set on 8 mol/m3, the good corrosion resistance was obtained for low corrosive current density and high reactive resistance in NaCl aqueous solution at 303K.
Two-Dimensional X-Ray Diffraction for Structure and Stress Analysis
Authors: He Bob B. , Xu Ke Wei , Wang Fei , Huang Ping
Published: March 2009

This paper introduces the recent progress in two-dimensional X-ray diffraction as well as its applications in microstructure and residual stress analysis. Based on the matrix transformation between diffraction space, detector space and sample space, the unit vector of the diffraction vector can be expressed in the sample space corresponding to all the geometric parameters and Bragg conditions. The same transformation matrix can be used for texture and stress analysis. The fundamental equations for both stress measurement and texture measurement are developed with the matrix transformation defined for the two-dimensional diffraction. Stress measurement using twodimensional detector is based on a direct relationship between the stress tensor and the diffraction cone distortion. The two-dimensional detector collects texture data and background values simultaneously for multiple poles and multiple directions.
Adaptation of the X-Ray Diffraction Technique to the Analysis of Residual Stress in Carbo-Nitrided Steel Layers
Authors: Sprauel Jean Michel , Michaud H.
Published: March 2009

X-ray diffraction is used to analyse the fatigue behaviour of carbo-nitrided steel layers. Measurements are therefore carried out on the two major phases of the material, i.e. the martensite (a') and the retained austenite (g). On such gear material, X-ray residual stress evaluations are particularly difficult for three reasons. First, the studied material is multiphase. For that reason, in each phase, the stress component in the direction normal to the surface is non negligible. Second, the diffraction peaks obtained on the martensite are broadened, due to the overlap of different reflections of the tetragonal structure. Third, the material contains also carbide and nitride clusters, which lead to incoherent and diffuse scattering of X-rays thus making quantitative phase determination difficult. In our paper the methods used to solve these problems are presented. The development of a new quantitative phase analysis method which accounts for the variation of diffuse scattering of X-rays is shown first. The second part deals with an iterative micromechanical model implemented for the evaluation of the carbon content and the residual stress components of each phase. These methods are used for analysing the evolution with cycling fatigue of all the parameters derived from our enhanced analysis (phase volume fraction, carbon content, stress components, peak width).
X-Ray Stress Measurement of Carbide in Tool Steel
Authors: Gotoh Masahide , Hirose Hajime , Sasaki Toshihiko
Published: March 2009

Thin films deposited by physical vapor deposition (PVD) were studied in terms of
residual stress by the authors. The final purpose of our study is to evaluate the stress state at the interface between a substrate and a thin film. In this study, JIS-SKH55 tool steel without thin-film deposition was used as the specimen. SKH55 is a dual-phase steel consisting of martensite a’Fe and alloyed carbide M6C2. The specimens were heated to 573K, 798K, 843K and 893K. Recently, the relationship between the misfit of plastic strain and stress obtained by X-ray stress measurement has been proposed by the authors using the Eshelby/Mori-Tanaka model (EMT model). The residual stress and the misfit of plastic strain were determined by X-ray stress measurement using the EMT model. Results showed that as annealing temperature increased, the compressive residual stress
remained nearly constant up to about 800K, and decreased above 800K in both phases. The misfit of plastic strain also remained nearly constant up to about 800K, and reached zero above 800K.
Residual Stress Mapping in Welds Using the Contour Method
Authors: Zhang Ying , Pratihar S. , Fitzpatrick Michael E. , Edwards Lyndon
Published: March 2009

The contour method, a newly-invented sectioning technique for residual stress
measurement, has the potential to measure the cross-sectional residual stress profile of a weld in a simple and time-efficient manner. In this paper we demonstrate the capability of the contour method to measure cross-sectional residual stress profiles, which are compared with neutron diffraction measurements and show excellent agreement. The results provide useful information for safetycritical
design of welded components and optimization of welding parameters, and also illustrate the potential of the contour technique as a powerful tool for residual stress evaluation.
Effect of Machining Conditions on Residual Stress Corrosion Cracking of 316L SS
Authors: Braham Chedly , Ben Rhouma A. , Lédion J. , Sidhom H.
Published: March 2009

Surface generation using conventional machining processes shows a residual stress distribution which mainly depends on the process parameters. This distribution affects the mechanical stability of the layers affected by the process. Particularly, when a specific level of the residual stresses is reached, a stress
corrosion cracking (SCC) of the 316L austenitic stainless steel occurs in the MgCl2 (40%) solution at 142°C. Results obtained in this investigation have shown that the non-cracking residual stress threshold value depends not only on the couple workspace material / environment, but on the surface generation process
also. Indeed while, a threshold SCC value of +380 MPa was measured in the case of surfaces generated using the turning process, a value of +280 MPa only was evaluated for the ground surfaces. This difference was discussed on the basis of the relation between the mechanism of crack initiation under SCC and the electrochemical reactivity of the generated surfaces using a specific process. Hence, one can conclude that the residual stress heterogeneity at the surface as well as in the under layer and the finished surface reactivity explain the morphology of the generated cracks by SCC and the sense of the non-cracking threshold must be revised.
Influence of Grinding Conditions on Residual Stress Profiles after Induction Surface Hardening
Authors: Grum Janez
Published: March 2009

Induction surface hardening creates very desirable residual stresses in the hardened surface layer. Residual stresses are always of a compressive nature and are usually present to the depth of the induction-hardened layer. By the appropriate selection of grinding wheel and grinding conditions and taking into account the physical and mechanical properties of the workpiece material very favourable compressive residual stresses in the hardened surface layer can be retained.
How is it possible to assure a desirable surface and surface layer quality after induction hardening and fine grinding Finding an answer to this question requires a very good knowledge of the process of grinding on the micro-level as well as knowledge of mechanical and heat effects acting on the layer of the workpiece including the type and condition of the grinding wheel. An allinclusive consideration of the numerous influences of the kind and condition of the tool on the changes on the surface and in the surface layer of the workpiece in the given machining conditions
is described by the term “surface integrity”.
Residual Stresses due to Deep-Drawing of Pre-Coated Aluminum-Alloy Sheets
Authors: Sudo Masatoshi , Iwase Tomohiko , Hattori Yoshiyuki , Nakajima Madoka
Published: March 2009

In this study, we examined how the press formability of A1 alloys sheets and the
generation of residual stresses was influenced by pre-coating resins, lubricants, die shoulder radius, the punch shoulder radius, and so on. The use of a pre-coated layer offers advantages by preventing direct contact between sheet metal and the face of the die, and also by enabling the use of volatile oil lubricants that keep the factory environment cleaner. The circumferential residual stress (σC ) of a cup becomes lower when the lubricant is less effective, and when the die shoulder radius is smaller.
Determination of the Residual Stresses in Composite Laminate Using the Compliance Method
Authors: Montay Guillaume , Sicot Olivier , Gong X.L. , Cherouat Abel , Lu Jian
Published: March 2009

Residual stresses play an important role on the mechanical behavior of composite laminate. The development of new methods to determine the residual stresses gradient within the laminates is necessary. This article presents the adaptation of the compliance method in the case of composite laminates carbon/epoxy [02/902]s. The incremental drilling of a constant width groove allows for each increment to measure the strains (using strain gages) and displacements (using an optical device) of particularly points of the structure surface. These experimental data are compared with results given by a finite elements simulation. This comparison allows to raise the residual stresses in the composite laminate.
Investigation of the Relationship between Annealing Temperature and Yield Strength in Cu Film by In Situ XRD Stress Analysis Method
Authors: Qin M. , Ji Vincent , Wu Y.N. , Ma S.Y. , Li J.B.
Published: March 2009

A new method is applied to investigate the relationship between the yield strength and
annealing temperature for a Cu film. By Ion Beam Assisted Magnetron Sputtering (IAMS), Cu film with 2.4 µm thickness was deposited on a strip of super high strength steel 37SiMnCrNiMoV, and the specimens were treated by vacuum-annealing at different temperature. The X-ray tensile test was used to measure the longitudinal and transverse stresses and applied strain for Cu film. Based on the experimental results, the equivalent stress s and the equivalent uniaxial strain t e can be obtained. According to the s- t e relation, the calculated proof stress is acquired. The results indicate that the proof stress of the film decreases with the increasing of annealing temperature. When annealing temperature rises from 150ı to 300ı, the decreasing amplitude of proof stress is the largest. The phenomenon can be explained by the recrystallization and microstructure evolution in Cu film during the annealing treatment.
Modelling of the Ultrasonic Shot Peening Process
Authors: Pilé C. , François Manuel , Retraint Delphine , Rouhaud Emmanuelle , Lu Jian
Published: March 2009

The aim of this work is to reach a better understanding of the ultrasonic shot-peening
process and, in particular, the evolution of the shot speed distribution. A simple 1D modelling of the interaction between the shots and the sonotrode is carried out. The impact is considered as inelastic with an energy absorption that depends on the speed of the shot. It is found that after about 10 interactions (» 1s) the speed distribution in the chamber follows a Maxwell-Boltzmann distribution, which is the
distribution found in a perfect gas at equilibrium. The influence of various process parameters such as the sonotrode amplitude, the vibration frequency on the average speed and on the Almen intensity is studied.
Determination of Residual Stresses after Tensile Tests and Deep Drawing of Unstable Austenitic Steel
Authors: Berrahmoune M. Reda , Berveiller Sophie , Inal Karim , Patoor Etienne , Simon Christian R. , Glez Jean-Christophe
Published: March 2009

The main objective of this work is to contribute to the study of the 301LN unstable
austenitic stainless steel by determining the distribution of residual stresses after deep drawing, taking into account the phase transformation. In the first part, kinetics of martensitic transformation are determined for uniaxial loading. Tensile tests are performed at different pre-strains at room temperature for two different strain rates. The austenite/martensite content is measured by X-ray diffraction and is coupled with the determination of residual stresses distribution. In addition, to establish a relation between the complex loading path effect and the residual stresses state, deep drawing are done for different drawing ratios for two different temperatures. Macroscopic tangential residual stresses are determined by the separation
technique. It appears that the residual stresses increase with increasing drawing ratios and the maximum value is located at middle height of the cup.
A Study on the Microstrains in the Textured YBa2Cu3O7-d Superconductor Films
Authors: Liu Dan Min , Liu Min , Xiao Wei Qiang , Xu Xue Dong , Liu Wei , Zhou Mei Ling
Published: March 2009

YBa2Cu3O7-δ(YBCO) films with highly biaxial textures were deposited on SrTiO3 single crystal, textured polycrystalline Ag and NiO/Ni substrates using pulsed laser deposition, metal-organic decomposition and ultrasonic spray pyrolysis method. The microstrains in different specimens with strong textures were measured using x-ray diffractometer and were compared each other.
Co-Precipitation Processing of Nanosized (Y,Gd)2O3: Eu Powder and Its Enhanced X-Ray Excited Luminescence
Authors: Shi Ying , Chen Ji Yang , Shi Jian Lin
Published: March 2009

Preparation of nanosized (Y,Gd)2O3:Eu powders by co-precipitation processing is reported. Phase transformation during calcination was studied by means of DTA-TG FT-IR, SEM and XRD in detail. It was found that the morphologies and X-ray excited luminescence of (Y,Gd)2O3:Eu powders were greatly influenced by the precipitants used. The (Y,Gd)2O3:Eu powder resulted from the complex precipitants of NH3•H2O and NH4HCO3 possessed best microstructural features with grain size of about 30nm and specific surface area of 38m2/g after being calcined at 8500C for 2hr, showing a much finer grain and less agglomeration than those from other two precipitation processing. It was demonstrated that nanosized (Y,Gd)2O3:Eu powder from complex precipitant exhibited much higher luminescence intensity at 611nm under excitation of X-ray (70Kev). which might be attributed to less degree of agglomeration among primary grains, decreasing the probability of non-radiation relaxation.
Ferroelectric Ceramics Related to BaTiO3 for Z5U Multilayer Capacitors
Authors: Taïbi-Benziada Laldja
Published: March 2009

Several pellets of general formula Ba1-xMx(Ti1-xLix)O3-3xF3x were prepared from BaTiO3, MF2 ( M = Ca, Sr, Ba or Pb ) and LiF powders then sintered by the conventional solid state route at 900 or 1000°C for 1, 2 or 4 hours. X-Ray powder diffraction patterns were collected at room temperature and SEM observations were carried out. Dielectric measurements were performed between 150 and 450K in the frequency range 50Hz - 40MHz. All the ceramics exhibit a very broad ferroelectric displacive phase transition in the temperature range 255K ≤ TC ≤ 328K.The ε' r - T curves and the values of tanδ are compatible with the Z5U class of capacitors. Furthermore, a Debye dielectric relaxation occurs in these oxifluorids in the frequency range 4MHz ≤fr ≤ 38.5MHz.
Power Evaluation of PbTe with Continuous Carrier Concentration Gradient
Authors: Imai Yoshio , Zhu P. , Isoda Yukihiro , Shinohara Yoshikazu
Published: March 2009

In this paper, we reported that lead telluride (PbTe) with continuous carrier
concentration gradient, in which PbI2, Al and Zr were doped, were successfully fabricated by the unidirectional solidification method. The carrier concentration was optimized by adjusting the relation between the dopants and the carrier concentration gradient. The carrier concentration for the ingots was estimated from the resistance results which were measured by the one-probe method. The result shows that the carrier concentration was large at the initiation side and small at termination side of the solidified ingots. The degree of the carrier concentration gradient can be controlled by the holding time at a liquid state and the cooling rate from the liquid state. The carrier concentration gradient can be largely affected by the
Al-dopant. The samples 0.07mol%PbI2-0.05mol%Zr-0.07mol%Al-PbTe, which were made from a liquid phase at 1200K held for 1h and cooled at 98K/h, showed a carrier concentration gradient ranging from 2×1024 to 1.5×1025 /m3. The effective maximum power for this continuous FGM is 20% larger than that of jointed FGM.
Testing and Characterization of Ceramic Thermal Barrier Coatings
Authors: Bartsch Marion , Baufeld Bernd , Dalkiliç Serdar , Mircea Iulian
Published: March 2009

This paper gives a short overview of tests applied for the investigation of long term
behaviour of thermal barrier coating systems. A variety of tests has been conducted on an exemplary material system with the coatings applied by electron beam physical vapour deposition. Damages and damage evolution in different tests are compared. Since the observed damage mechanisms are different, it is proposed to design laboratory tests as realistic as possible, especially if the test data are used for lifetime assessment. In order to get reasonable testing times, the damage accumulation has to be described as a function of loading history, long time before failure. For the case of final failure by spallation of the ceramic top coat, it is proposed to use the apparent interfacial fracture toughness as damage parameter. Several methods for measuring the apparent fracture toughness of brittle coatings are discussed with respect to their application to thermal barrier coating systems.
Three Dimensional Fracture Analysis of FGM Coatings
Authors: Inan Ozgur , Dag Serkan , Erdogan Fazil
Published: March 2009

In this study the three – dimensional surface cracking of a graded coating bonded to a homogeneous substrate is considered. The main objective is to model the subcritical crack growth process in the coated medium under a cyclic mechanical or thermal loading. Because of symmetry, along the crack front conditions of mode I fracture and plane strain deformations are assumed to be satisfied. Thus, at a given location on the crack front the crack propagation rate would be a function of the mode I stress intensity factor. A three – dimensional finite element technique for
nonhomogeneous elastic solids is used to solve the problem and the displacement correlation technique is used to calculate the stress intensity factor.
Using the Image Analysis Program for Prediction of Thermal Stability Behavior of Refractory Specimen
Authors: Volkov-Husović Tatjana , Jančić R.M. , Mitraković D.
Published: March 2009

Most important properties which are usually measured for refractories are work
temperature and thermal stability. Thermal stability of the alumina based samples was measured using a standard laboratory procedure, the water quench test ( JUS.B.D.8.319.). ImagePro Plus Program was used for image analysis of microphotographs of the samples before, during and after water quench test. Changes at the surface before, and after cycling were given. Mechanical
characteristics were considered such as compressive strength, and dynamic modulus of elasticity. It was measured by resonance frequency measurements, as well as ultrasonic velocity. In this work the correlation between microstructure, ulatrasonic velosity and strength on thermal stability of the sample were investigated. The obtained results were used for validation of the model to predict the thermal stability of the refractory specimen.
Porous Graded Materials by Stacked Metal Powder Hot-Press Moulding
Authors: Nishiyabu Kazuaki , Matsuzaki Satoru , Okubo Kenji , Ishida Masashi , Tanaka Shigeo
Published: March 2009

The production method for metal components with micro sized porous structure has been developed by applying “powder space holder method” to metal powder injection molding process. In this study, a co-sintering process was utilized to make a plate of sintered metal with micro porous graded structure. The green compact sheets with various contents of space hold particles were prepared by hot press molding for simplification. The five layers of metal with symmetric structure, which the skin layer was formed with high density metal and the core was formed with open or closed porous structure, or with inverse symmetry, was obtained by changing stacking sequence in co-sintering process. Mechanical properties of the materials with plain homogeneous porous structure and porous graded structure were compared. The usefulness of proposed method for producing the metal components with micro porous graded structure and the effective of graded structure to compensate the deficiencies on the mechanical property of porous metals was shown.
A New Functional Material; Photonic Fractal
Authors: Miyamoto Yoshinari , Kirihara Soshu , Takeda Mitsuo Wada , Honda Katsuya , Sakoda Kazuaki
Published: March 2009

An entirely new functional material named photonic fractal has been developed. It can strongly localize electromagnetic waves in a dielectric fractal cube called Menger sponge without reflection and transmission. The wavelength and frequency of the localized mode can be predicted using a simple equation associated with the fractal geometry and the spatially averaged dielectric constant of the Menger sponge structure. A wide variety of applications to communication, information, energy, sensing, medical care, and other fields are considered. Design and fabrication of Menger sponge fractals with epoxy resin and ceramics, their electromagnetic wave responses, integration of photonic fractals as well as potential applications are reported.
Characterization of Nanoporous Lanthanide-Doped Gadolinium Gallium Garnet Powders Obtained by Propellant Synthesis
Authors: Krsmanović R. , Polizzi Stefano , Canton P.
Published: March 2009

In the present work we study the nanocrystalline powders of lanthanide-doped
Gd3Ga5O12 (GGG, gadolinium gallium garnet) prepared using propellant synthesis. A series of GGG samples containing a number of different trivalent lanthanide ions (Tm, Er, Ho, Eu, Sm, Nd, and Pr) in different quantities (1%, 5%, 10%) were produced. Samples were characterized by X-ray diffraction (pre- and post calcination) for phase identification and line-broadening analysis, and by
electron microscopy (SEM and TEM) for morphological and nanostructural investigation. Thermal behavior of the powder was investigated by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The samples have a polycrystalline porous structure. Elemental microanalysis made by energy dispersive X-ray spectroscopy (EDX) detector attached to TEM and
XRD unit-cell determinations confirmed that the lanthanides ions entered the structure of GGG. Crystallites have a high degree of disorder.
Neutralization of Ion Beams for Reduction of Charging Damage in Plasma Etching
Authors: Nina Aleksandra , Radmilović-Radjenović M. , Petrović Z.Lj.
Published: March 2009

Neutral beams were proposed for plasma etching in order to reduce damage due to charging. We analyzed the efficiency of neutralization in a system proposed recently where a beam of ions was neutralized in the gas phase and in a set of narrow tubes. We studied surface neutralization as well as collisions of ions in the gas. In the case of collisions of ions with aperture walls, efficiency of neutralization was assumed to be 100%. We also investigated the influence of various parameters such as aperture length, tube diameter and initial ion energy on the efficiency of neutralization using a Monte Carlo code for ion motion simulation. In our calculations we used a well-established set of cross sections for argon.
Nickel/Silica Precursor from Sodium Silicate Solution - Synthesis and Characterization
Authors: Krstić J. , Vukelić N. , Nedić Zoran , Milutinović-Nikolić A. , Šućurović A. , Jovanović D.
Published: March 2009

The aim of this paper was the investigation of the influence of synthesis parameters, as well as the order of synthesis steps, in procedure of chemical precipitation, on the properties of synthesized nickel precursor. The starting materials were always the same aqueous solutions of Ni(NO3)2×6H2O and Mg(NO3)2×6H2O of constant molar ratio, 2% solution of SiO2 in the form of sodium silicate solution (module SiO2/Na2O = 3.0) and 10% solution of Na2CO3, while synthesis steps and addition modes were varied. Complete pH and temperature monitoring was performed during entire synthesis at 90°C. The formed precipitate aged 30 minutes at synthesis temperature. By changing the order and conditions of adding SiO2 and Na2CO3 solutions and keeping the treatment of precipitates the same (rinsing with hot distilled water followed by drying at 110°C for 24 hours) six different precursors were obtained. Samples characterizations were performed using different experimental techniques: XRD analysis, IR spectroscopy, reflection spectroscopy, TG analysis, N2 physisorption. The relation between synthesis procedure and precursor properties was established.
Dilatometer Investigations of Reactive Sintering of Zinc Titanate Ceramics
Authors: Obradović N. , Labus Nebojsa , Srećković Tatjana , Ristić Momcilo M.
Published: March 2009

Starting powder mixtures of ZnO and TiO2, at the molar ratio that is in accordance with the stoichiometry of zinc titanate Zn2TiO4, were mechanically activated using a planetary ball mill in different time intervals from 0 to 90 minutes. X-ray diffraction analysis, scanning electron microscopy and non-isothermal dilatometric measurements were performed in order to investigate zinc titanate formation. Processes occurring during mechanical activation led to the formation of a specific structure of obtained powders that promoted and accelerated solid-state reactions and densification during sintering. The main conclusion based on analysis is that mechanical activation enables better compaction of activated powders, i.e. possibility of achieving higher densities of green bodies without binders, but first of all that Zn2TiO4 ceramics can be obtained by mechanical activation after a certain time with appropriate thermal treatment, i.e. heating rate and sintering time, at temperatures lower than those when non-activated mixtures were used.