bluuebunny/crossref_metadata_2025 huggingface dataset:
High Temperature Mechanical Properties of Ni-Al-Cr Based Alloys with Refractory Alloying Elements
Authors: Kim Won Yong , Kim Han Sol , Yeo In Dong , Kim Mok Soon
Published: March 2009

We report on advanced Ni3Al based high temperature structural alloys with refractory alloying elements such as Zr and Mo to be apllied in the fields of die-casting and high temperature press forming as die materials. The duplex microstructure consisting of L12 structured Ni3Al phase and Ni5Zr intermetallic dispersoids was observed to display the microstructural feature for the present
alloys investigated. Depending on alloying elements, the volume fraction of 2nd phase was measured to be different, indicating a difference in solid solubility of alloying elements in the matrix γ’ phase. Lattice parameter of matrix phase increased with increasing content of alloying elements. In the
higher temperature region more than 973K, the present alloys appeared to show their higher strength compared to those obtained in conventional superalloys. On the basis of experimental results obtained, it is suggested that refractory alloying elements have an effective role to improve the high temperature strength in terms of enhanced thermal stability and solid solution hardening.
High Temperature Oxidation of TiAl(La)N Coating Deposited on a Steel Substrate by Arc-Ion Plating
Authors: Shapovalov Y.A. , Lee Dong Bok
Published: March 2009

The high temperature oxidation behavior of the TiAl(La)N coating, which was deposited on a steel substrate by the arc-ion plating method, was investigated at 700, 800 and 900oC in atmospheric air. The oxidation kinetics of the coating were mainly governed by the inward diffusion of oxygen and outward transport of nitrogen. The oxide scale was porous, nonadherent, and prone to cracking, indicating the oxidation resistance above 700oC is poor.
High Temperature Oxidation of WC-ZrN Superhard Nanocomposite Film
Authors: Lee Dong Bok , Shapovalov Y.A.
Published: March 2009

The high-temperature oxidation behavior of WC-ZrN superhard nanocomposite film was studied in air between 500 and 700oC. The WC-ZrN film displayed poor high-temperature oxidation resistance, because of the formation of the nonprotective W-oxide scale and the less-protective, nonstoichiometric ZrO2-x oxide scale. The scale was prone to cracking and spallation. During oxidation, C and N escaped from the film into the air, while oxygen from the air diffused into the film.
Effect of MgF2 Additive on the Mechanical Properties in Hydroxyapatite / Zirconia Composites
Authors: Kim Sung Hwan , Lee Hyun Chan , Bang Hee Gon , Park Sang Yeup
Published: March 2009

In this study, the effect of MgF2 additive on the mechanical properties of hydroxyapatite (HAp)/zirconia composites was investigated. As a fluoride additive, MgF2 was added to HAp/zirconia composites for the suppression of phase decomposition from HAp to tricalcium phosphate (TCP). Due to the dissolution of MgF2 at the phase decomposition temperature of HAp, the phase decomposition of non-stoichiometric HAp was suppressed. When MgF2 (5, 10 vol%) was
added to HAp/zirconia composites, the decomposition of HAp was completely suppressed below 1400oC due to the ion substitution F- of for OH- in the HAp crystal structure. The flexural strength and Vickers hardness of composites was revealed more higher values compared with the MgF2-free composites.
The XPS and GDS Study of SrBi2Ta2O9/ZrO2/Si (MFIS) Structure According to Heat Treatment Effects of ZrO2 Buffer Layer
Authors: Park Chul Ho , Son Young Gook
Published: March 2009

ZrO2 buffer layer and SrBi2Ta2O9 (SBT) thin films were deposited on the P-type Si(111) substrates by the R.F. magnetron-sputtering method. We studied the effect of the post-annealing of the ZrO2 buffer layer on the MFIS structure. We could conclude that the elements of Zr, Sr, Bi, and Ta etc. were diffused by the post-annealing, and according to the process with and without the post-annealing of the ZrO2 layer, the diffusion amount of Sr, Bi, Ta elements shows slight difference
through the glow discharge spectrometer (GDS) analysis. From the results of the XPS analysis, we can confirm that a small amount of SiO2 and metallic Zr exist at the interface, and ZrO2 exists as the amorphous state with the weak binding energy before the post-annealing process. Contrarily, after the post-annealing of the ZrO2/Si structure, SiO2 and metallic Zr are observed at the wide range, but the
bonding state of ZrO2 is strengthened.
Effects of Void Formation within the Pb-Free BGA Solder Balls on the Mechanical Joint Strength
Authors: Kim Jong Woong , Jung Seung Boo
Published: March 2009

The effects of void formation on the joint strength and failure mode of the solder joints
were examined. A computational modeling technique, i.e., finite element modeling, was employed to investigate the effects. The effects of location, size and number of void were also investigated and compared with the case that has no void in the solder ball. When there was 1 or more voids in the solder ball, the joint strength decreased regardless of the location, size, and number of voids.
Especially, the shear force of the joints decreased about 50% when 3 voids were formed in the solder ball. From the stress analyses, the possibility of preliminary brittle interfacial failure should be lower when voids were formed in the solder ball.
Fabrication of Lead Free Micro Solder Powder by Melts Dispersion Technique
Authors: Youn Jeong Il , Ha Won , Kim Young Jig
Published: March 2009

A new process, melts dispersion technique, was developed to fabricate the solder powder in oil surroundings by forming molten metal’s droplets. The main parameters of the technique on shape and size of powders were investigated in the present paper. It is shown that a cooling rate of the melts and viscosity of oil for isolation of droplets affect the shape and the size. The cooling rate is a
very important parameter, and there is a critical cooling rate at given conditions. Although the melts were dispersed perfectly in oil, fine droplets were merged and coalesced during solidification without rapid cooling. The shape of powder has an influence mainly on oil viscosity and was altered into a sphere from an irregular shape with increasing oil viscosity.
Formation Characterization of Ultra-Fine Cu Powder from Cu(OH)2 Slurry by Wet Reduction Method
Authors: Ahn Jong Gwan , Kim Dong Jin , Hoang Hai , Lee Jae Ryeong , Chung Hun Saeng
Published: March 2009

Ultra-fine copper powders with an average size of 150 nm were synthesized from
Cu(OH)2 .H2O slurry with hydrazine monohydrate as a reduction agent by using the wet reduction method. Parameters such as temperature, reduction agent feeding rate, stirring rate, stirring speed, Cu(OH)2 concentration, and surfactants were investigated. It was found that the feeding rate of hydrazine monohydrate and the use of surfactants mainly affect the morphology and size of the copper powders along with their dispersion. XRD, PSA, and SEM were used to characterize the
prepared particles.
Environmentally Friendly Polyurea Microcapsules of Pesticides by PVA Mediated Interfacial Polymerization
Authors: Paik Seung Uk
Published: March 2009

Microcapsules containing agrochemical pesticides used to control insects have attracted considerable interest for the last three decades in the search for reducing intrinsic toxicities, overconsumption, and ecological problems that have been caused generally by conventional pesticides. Biodegradable polyurea microcapsules containing pesticides such as ethyl parathion, benlate, and daconyl were prepared by the interfacial polymerization of polyisocyanate monomers with polyamines. In the process of microencapsulation with various emulsifying agents under the condition of high to medium concentration, polysulfonated emulsifiers such as lignosulfonate and styrenesulfonate sometimes failed to produce microcapsules because of random solidification of the aqueous mass leaving a serious problem of reproducibility. A protective colloid, polyvinylalcohol (PVA), was examined to prepare the stable high-concentrated emulsion under various conditions.
Capsule slurry with 33% active ingredient was successfully obtained by the use of ca. 1% PVA as a protective colloid. In the case of the capsule with 42% active ingredient, the wall-forming reaction produced microcapsules, which turned out to be considerably coagulated or sometimes resulted in the failure of producing microcapsules. However, it was found that the mixed emulsifier of 10% of
PVA and 90% of poly (sodium4-styrenesulfonate (PSS) produced stable emulsion and successfully led to microcapsules in high concentration under various conditions without any problems of reproducibility. The particle size distribution of the microcapsules was not much influenced by surfactants, and the size and distribution of the obtained microcapsules were directly affected by the agitation speed of emulsion.
Photocatalytic Characterization of Plasma Sprayed TiO2 Coating in Environmental Engineering Application
Authors: Kim Tae Ho , Lee Soo Wohn , Chen Huang , Cho Hae Yong
Published: March 2009

The commercial nano-sized TiO2 powder (P25) was immobilized on foamed waste-glass substrates by using the plasma spraying technology. The immobilized TiO2 coatings were applied to treat both the green tide and the red tide under illumination of an UV light. Their photocatalytic characterizations were evaluated as functions of the number of residual algae, transmission as well as pH value with illumination time. It was found that the plasma sprayed nano-TiO2 coatings on
foamed waste-glass show a higher photocatalytic activity, which was effective to treat the green tide and the red tide.
Mechanical Properties of Copper Hollow Sphere Manufactured by Sintering Process
Authors: Koo Ja Myeong , Jung Seung Boo
Published: March 2009

The polystyrene spheres coated with a slurry, consisting of copper (I) oxide powder, water and PA (poly acrilamide), were reduced to form copper (Cu) hollow spheres at sintering temperatures ranging from 650 to 950 °C under a hydrogen atmosphere. The microstructural evolutions and mechanical properties of the Cu hollow spheres were investigated with the sintering temperature. The increase in the sintering temperature led to the increase in the density and grain
size of the spheres. The amount of the residual copper oxide in the samples decreased with increasing sintering temperature. The electrical conductivity, hardness, and compression strength of the hollow spheres increased with increasing sintering temperature.
Microstructure Characterization on TiO2 Based Anodes
Authors: Yi Zeng , Chen Kang Ning , Wu Wei , Gao Jian Hua
Published: March 2009

Titanium based anodes are widely used in chlori-alkali industry. Two kinds of titanium based anodes were characterized by using XRD and SEM. The test results of their electrocatalytic properties showed that the nanosize crystals have great effect on the anode’s polarization behaviors and accelerated stability life. The anode with higher content of Ta possessed a smaller crystal size and better electrocatalys
Rheological Characteristics of Mg-Al Alloys with Ceramic Particles for Meta Foam
Authors: Park Soo Han , Song Kwang-Ho , Um Yong Su , Hur Bo Young
Published: March 2009

Foamed metal is a kind of porous material with pores in the metal matrix. One of the
possible process routes is to blow gas bubbles into liquid metals. However, many metallic foams produced by this foaming method have coarse and irregular cell structures. The industrial aim is to fabricate foams with more uniform structure and cell size. It is important to understand the mechanisms and factors controlling. The rheological characteristics are the most important factors in the metal foam manufacturing. Thus this study investigated the bubble behavior of the molten metal
and its two most important two parameters: surface tension and liquid viscosity. The surface tension (by the ring method) and the viscosity (by the rotation method) of Mg-Al alloy (AZ91, AM60) have been measured under pure Ar and SF6 + CO2 atmosphere. The results show that the surface tension and the viscosity of these alloys decrease with increasing temperature. The addition of Ca and SiC to
Mg alloys decreases the surface tension and increases the viscosity. This anomalous behavior is related with the preferential adsorption of high activity elements on the surface.
Synthesis and Magnetic Properties of Fe/SiO2 Nanocomposite Powders by the Chemical Vapor Condensation Process
Authors: Kim Jin Chun , Lee Jae Wook , Park Byung Yeon , Choi Chul Jin
Published: March 2009

Fe/SiO2 nanocomposite powders were synthesized by the chemical vapor
condensation(CVC) process. Phase and microstructures of the as-prepared powders were investigated with CVC experimental parameters by XRD, TEM and VSM. The analysis of XRD patterns revealed that the Fe/SiO2 powders could be produced above 700. With increasing reaction temperature, the XRD peaks became clearer. The size of powders was about 50nm at 1100oC. The Fe/SiO2 powders showed an intricate long-stand structure attributed to their magnetic characteristics. TEM results revealed that the Fe powders were covered by SiO2 layer fully or partially depending on the experimental condition. The saturation magnetization and the coercive force of the as-sytheised powders were investigated with the decomposition temperature.
Synthesis of Polymeric Precursor for Oxidation-Resistant SiCBN Ceramic Microstructure via Soft Lithography
Authors: Nghiem Quoc Dat , Pham Anh Tuan , Kim Dong Pyo
Published: March 2009

Microelectromechanical systems (MEMS) including microchemical devices have been widely concerned, in particular, when made of an extremely stable ceramic material for their use at harsh conditions. SiCBN preceramic polymer was derived from borazine (B3N3H6) modified allylhydridopolycarbosilane (AHPCS) via hydroboration of allyl groups with B-H groups at 0oC for 24 h by following the standard Schenk technique. The extent of polymer-to-ceramic conversion with
an ultimate ceramic yield of 92 wt% was investigated by simultaneous TGA, 1H, 13C-NMR, IR, and XRD measurements. The polymer-derived SiCBN ceramic remained as an amorphous solid up to 1400oC. The ceramic product obtained after pyrolysis at 1000-1400oC exhibited excellent oxidation resistance in air. In addition, ceramic microstructures were fabricated by employing soft lithographic technique.
Influence of the Cup's Edge Geometry on the Transferred Stresses to the Ball/Cup Interface in all Ceramic THR
Authors: Carrillo Daniel G. , Lee Soo Wohn , Lira-Olivares Joaquín
Published: March 2009

Alumina ceramics as well as zirconia ceramics have been used to manufacture hip
replacement components since the 1990’s. These materials have been used for the ceramic balls and cups in the replacements for the following reasons: in the case of alumina for its excellent wear behavior; and in the case of zirconia, for its good wear behavior but with greater fracture toughness than alumina. Nevertheless, since ceramics are brittle, the design of the components must consider
ways to avoid detrimental stress concentrations. In this study the stress concentration on the rim of the ceramic cup is inspected by means of a two-dimensional axis symmetric finite element model. This model simulates contact between the components to obtain the stresses that are transferred
from the ball to the cup. Different geometries of the cup’s edge are simulated to evaluate the incidence of the geometry over the stress pattern. Although this model concentrates on the contact between the ball and the cup, the loading is made from the stem to the ball, which means that the load is transferred from the stem to the ball and then to the cup. This approach may offer a more realistic output. The data from this study may be useful for hip replacement designers as well as for surgeons because it shows a direct relationship between the stress patterns and the geometrical parameters of the design.
Densification Mechanism of Fine Ni-20Cr Powder during Pulsed Electric Current Sintering
Authors: Nanko Makoto , Sato Manabu , Matsumaru Koji , Ishizaki Kozo
Published: March 2009

Microstructure observation and kinetic analysis were conducted on fine Ni-20Cr powder (spherical shape and 5 m in average particle diameter) to understand the sintering mechanism of fine metallic powder during pulsed electric current sintering (PECS). Insulation of the sample during PECS was carried out to investigate the influences of pulsed electric current passing through the
sample. Temperature at the sample/die interface was measured as sample temperature. Pulsed electric current did not influence densification. The microstructure observation revealed that the necks between particles had very small curvature radius, which means the neck formation by compressive deformation of particles owing to creep. As results of the kinetic analysis of the densification, the creep rate of fine Ni-20Cr powder was two digits larger than the extrapolated values
of the steady-state creep on PECS of coarse Ni-20Cr powder and creep tests reported previously. The larger creep rate of fine Ni-20Cr powder during PECS may be influenced by not only smaller grain size of powder particles but also contribution of the initial creep, which was faster than the steady-state creep.
Radio Frequency Interference Characteristics of Plate-Like Soft Magnetic Powders-Polymer Composites
Authors: Kim Sang Woo , Yoon Y.W. , Kim G.Y. , Lee Kyung Sub
Published: March 2009

Radio frequency interference characteristics of plate-like Fe-Si-Al alloy
powders-polymer composites were investigated for effective noise suppression. Broadband reflection loss characteristics were exhibited in the composites below a critical compaction pressure of 1.56 x 108 N/m2, while narrowband characteristics were shown in the composites above the critical pressure. Although the composites at 2.34 x 108 N/m2 had the highest complex permeability and complex permittivity, the loss properties did not show the broadband characteristics. The peculiar broadband characteristics were obtained in the composites with wideband dependency of the imaginary part of permittivity and permeability. These findings led us to conclude that the broadband electromagnetic interference characteristics of the composites are caused by the coupling effects of magnetic and dielectric resonance in the radio frequency range.
High Grade Purification of Sericite by Hydrocyclone and Magnetic Separation
Authors: Kim Kyung Nam , Shin Dae Yong , Park Hyun
Published: March 2009

Sericite has the intermediate nature of the muscovite and illite, which has been used as the additive of the cosmetics, the ceramic industry, welding rods, and other various pigments and the paint. In this study, the characteristics of sericite were examined using XRD(X-ray diffractometer), XRF(X-ray fluorescence spectrometer), TG-DTA(Thermal Analyzer), SEM(Scanning Electron
Microscope) and PSA(Particle Size Analyzer). The raw ore is composed of 60.90wt% SiO2, 7.88wt% K2O, 0.36wt% TiO2, 24.80wt% Al2O3, 1.64wt% Fe2O3, 2.39wt% CaO, and 0.83wt% MgO. After sericite was purified, the content of SiO2 decreased from 60.9wt% to 51.4wt%, and in the crystal phase the intensity of quartz decreased significantly. For the high grade purification of sericite, the
removal of iron and separation of quartz for the raw ore (sericite), the hydrocyclone were used with the magnetic separator. The content of iron was reduced from 1.64wt% to 0.91wt%.
Fabrication and Properties of High Strength Al-8Fe-2Mo-2V-1Zr Alloy Produced by Melt Spinning Techniques
Authors: Jung Taek Kyun , Lee Dong  Suk , Kim Mok Soon , Kim Won Yong
Published: March 2009

High strength Al-8Fe-2Mo-2V-1Zr (wt.%) alloys fabricated by a melt spinning and a hot extrusion process were produced to correlate the microstructure and mechanical property. Melt spun ribbon prepared by single roll melt spinner showed a cellular structure with an average size of 10nm and Al-Fe based intermetallic dispersoid of less than 10nm in particle size. The melt spun ribbon obtained was then pulverized to make a powder shape followed by hot extrusion at 648K, 673K,
723K and 773K in extrusion ratio of 5 to 1, respectively. Equiaxed grain structure containing Al-Fe based intermetallic phase was observed in all extruded specimens. According to increasing extrusion temperature, the grain size increased and particle size of intermetallic dispersoid. The lattice parameter increased from 0.4051nm to 0.4059 nm with increasing extrusion temperature from 648K to 773K, those values were larger than that obtained in pure Al (0.4049nm). Yield strength of the
specimen extruded at 648K measured to 956MPa at room temperature, 501MPa at 573K and 83MPa at 773K, respectively. With increasing extrusion temperature yield strength decreased significantly at room temperature and even in the intermediate temperature range, while no noticeable difference in yield strength was observed at 773K.
Low Elastic Modulus β Ti-Nb-Si Alloys for Biomedical Applications
Authors: Kim Won Yong , Kim Han Sol , Yeo In Dong
Published: March 2009

We report on advanced β-titanium alloys having excellent biocompatibility without
containing V or Al that has been known as a toxic element for human body, and on a low elastic modulus to be used in the fields of artificial joint and dental implant in the replacement of natural human bone. Martensite structure with α’ (hcp) or α”(orthorhombic) was observed in Ti-xNb-1.5at.%Si, where x=10-20at.%. The crystal structure of martensite formed from water quenching process was largely dependent upon Nb content but does not on Si content. On the basis of experimental results obtained, it is suggested that Si has an effective role to suppress the precipitation of ω phase leading to reduction in elastic modulus in the metastable β phase region. Metastable β phase region was superior to reduce the elastic modulus than stable β phase region in the present alloy system. The minimum value of elastic modulus was measured to 48GPa.
Thermopneumatic-Actuated Polydimethylsiloxane (PDMS) Microfluidic System
Authors: Yoo Jong Chul , Kang C.J. , Jeon D. , Kim Yong Sang
Published: March 2009

We propose a new PDMS microfluidic system including microvalves and a micropump
that are easily integrated on the same substrate with the same process steps. The pumping rate of the fabricated microfluidic system was measured under various frequency and duty-ratio of applied power. The maximum pumping rate of about 26 nl/min is measured under the duty ratio of 1 % at 2 Hz of the applied pulse voltage. The dynamic response of the microvalve in the microfluidic system is measured under the on/off alternation with the applied power of 100 mW.
Raman Spectroscopic Investigation of Nitrogen-Doped Titanium Dioxide Nanoparticles
Authors: Shen Yan Fang , Xiong Tian Ying , Li Tie Fan , Yang Ke
Published: March 2009

Nitrogen-doped titania nanoparticles were co-prepared by sol-gel and
mechanical-alloying method. Raman spectroscopy was used to investigate the microstructure information of the nitrogen-doped titania nanoparticles. Besides, XPS, ESR and UV-vis absorption spectra were also analyzed as supplementary means. At first blue then red shift of 142 cm-1 peak was observed as the annealing temperatures increased. The possible reasons for the shift were discussed.
Development of Fiber Filter Media to Control Heavy Metals and Nutrients in Urban Stormwater Runoff
Authors: Kim Ree Ho , Lee Sang Ho , Jeong Jinwoo , Gee Chae Sung
Published: March 2009

The pollutants in urban stormwater runoff, which lead to non-point source contamination of water environment around cities, are of great concern. Lignocellulose fiber filters have potential to treat urban stormwater runoff because they are cheap and environmentally friendly, and can effectively remove particulate pollutants. However, the fiber filters alone cannot sufficiently remove soluble pollutants including heavy metals, nitrogen compounds, and phosphate. In this study,
techniques for chemical modification of lignocellulose fiber filter were implemented to enhance the treatment efficiency of soluble pollutants in urban stormwater runoff. Using these chemically modified fiber filters together with polymer filter media, a new treatment device was examined to control the pollutants in first flush of stormwater. The results indicated that the filters incorporated into the treatment unit allow the control of urban stormwater runoff with minimal cost and high efficiency.
Effect of Surface Morphology on Apatite Formation
Authors: Zhao Ying , Xiong Tian Ying , Liu Yu Liang , Li Tie Fan , Wang Long Bao
Published: March 2009

The bioactivity of Ti6Al4V induced by SSPB (supersonic particles bombarding) and alkali treatment was investigated in this work. More coarse surfaces were formed by SSPB and alkali treatment, which led to better bioactivity than that by only alkali treatment. Apatite began to appear on the surface of specimen only after 1 day of immersion in 1.5 SBF. As time passed, they gradually covered the whole surfaces. After 7 days of soaking in vitro, apatite formed and covered
all the surfaces of the titanium alloys, and they packed very densely and uniformly. EDS and XRD results proved all the new-formed phases were composed of a carbonate containing hydroxyapatite with small crystallites and defective structure. As a result, SSPB treatment might be an effective way to enhance the bioactivity of titanium alloys for implantation.
Thoughts on the Occasion of the Second Transformation in Materials Science
Authors: Meshii M.
Published: March 2009

The discipline of Materials Science is, we believe, in the midst of the second
transformation. The research and education of most of the Materials Science and Engineering departments in the United States have traditionally emphasized hard materials. The recent surge in research of soft materials and our perceptions that the Materials Science Methodology (both experimental and numerical) holds the advantage in the research of the soft materials prompt us to expand the area of soft materials at the expense of hard materials. Clearly the struggle between the
two types of materials will continue for some time to come. The current struggle in weighting will be described in an historical fashion comparing it to the struggle in the first transformation that took place in the 1950's and 1960's.
Variant Selection of Plate Martensite in Fe-28.5at.%Ni Alloy
Authors: Kitahara Hiromoto , Ueda Masato , Tsuji Nobuhiro , Minamino Yoritoshi
Published: March 2009

Variant selection rule of plate martensite in a coarse-grained Fe-28.5at.%Ni alloy was
investigated. Crystallographic analysis of martensite plates was carried out by electron back scattering diffraction (EBSD) analysis in a scanning electron microscope with a field emission type gun (FE-SEM). Certain variant selections were recognized for martensite plates in the Fe-28.5at.%Ni alloy. Equivalent strain, which was calculated from the shape strain of each variant, was used to evaluate the accommodation of the shear strain induced by martensite transformation. Variant selection was ruled not only by the shear strain accommodation but also by the ngle between habit planes of adjacent martensite plates.
Internal Stress Field in Ultrafine Grained Aluminium Fabricated by Accumulative Roll-Bonding
Authors: Ueji Rintaro , Taniguchi J. , Sumida N. , Tanaka Katsushi , Tsuji Nobuhiro
Published: March 2009

Internal stress field in a severely deformed aluminium with ultrafine grained
microstructure has been studied by convergent-beam electron diffraction (CBED) technique in transmission electron microscopy (TEM). A commercial purity aluminium (99.1%Al) sheet was highly strained by the accumulative roll-bonding (ARB) process to evolve an ultrafine grained structure. Higher-order Laue zone (HOLZ) lines in the incidence disk of the ] 12 1 [ zone axis have been observed at various positions within an identical ultrafine grain. The key finding is that the
HOLZ line pattern taken from the vicinity (~50nm) of the grain boundary (lamellar boundary) looses ) 1 1 0 ( mirror symmetry, whereas the pattern from the grain centre has the symmetry. The former and the latter represent the existence of a large non-hydrostatic stress field and a small internal stress field, respectively. The magnitude of the internal stress becomes larger with approaching to a grain
boundary.
Pseudoelasticity in Fe3Al Single Crystals under Cyclic Loading
Authors: Yasuda Hiroyuki Y. , Yamaoka Keisuke , Umakoshi Yukichi
Published: March 2009

D03-ordered Fe3Al single crystals containing 23, 25 and 28at.%Al were cyclically
deformed at [ 49 1 ] loading axis in tension-compression mode. Giant pseudoelasticity took place in Fe-23 and 25at.%Al single crystals at an early stage of cyclic deformation, while a slight strain recovery was observed in Fe-28at.%Al. In Fe-23 and 25at.%Al single crystals, superpartial dislocations with Burgers vector of 1/4[111] moved individually dragging the nearest neighbour anti-phase boundary (NNAPB). The NNAPB pulled back the superpartials during unloading,
resulting in giant pseudoelasticity and low residual dislocation density. In contrast, a couplet of the superpartials was observed to bow out leaving two superpartials in Fe-28at.%Al. This means that the dislocation couplet dragged the next-nearest neighbour anti-phase boundary (NNNAPB). The surface tension of NNNAPB is lower than that of NNAPB resulting in a slight strain recovery in Fe-28at%Al.
As cyclic deformation proceeded, residual dislocation density increased with an increase in the number of cycles even in Fe-23 and 25at.%Al. In particular, persistent slip bands (PSB) were formed in Fe-23at.%Al single crystals, though PSB is seldom observed in fatigued intermetallic compounds.
To-and-fro motion of superpartials during loading and unloading was suppressed by dislocation bundles, resulting in a reduced shape recovery. However, large strain recovery occurred in Fe-25at.%Al single crystals at a strain amplitude of 1.0% even at 20cycles. It was also noted that Fe-23 and 25at.%Al demonstrated tension-compression asymmetry even at [ 49 1 ] orientation; the yield stress in compression was higher than that in tension. This implies that the core structure of
<111> screw dislocation played an important role in the deformation behaviour of Fe3Al single crystals.
Crystal Orientation in High Magnetic Field
Authors: Wu Cun You , Li Shu Qin , Murakami Yuichiro , Sassa Kensuke , Asai Shigeo
Published: March 2009

A new technology relating to crystal orientation and structure alignment has emerged by the development of superconducting technologies. Now, a high magnetic field covering a rather large space is available even in small-scale laboratories. Under this circumstance it has been found that the crystal orientation in materials can be controlled by imposition of the high magnetic field. This principle due to a magnetization force can be applied not only to magnetic materials but also to
non-magnetic materials with asymmetric unit cells. In this paper, three novel processes for the crystal orientation of ceramics and metals are described.
Fabrication and Properties of Porous Materials with Directional Elongated Pores
Authors: Nakajima Hideo , Hyun Soong Keun , Tane Masakazu , Nakahata T.
Published: March 2009

Lotus-type porous materials whose long cylindrical pores are aligned in one direction were fabricated by unidirectional solidification from the melt dissolving gas. The pores were evolved by supersaturation of gas atoms when the liquid was solidified. Although such porous metals with high thermal conductivity were produced by casting process, the process could not produce porous metals with low thermal conductivity, which possess uniform pore size and porosity. In order to obtain
uniform pore size and porosity in metals with low thermal conductivity, we invented a new “continuous zone melting technique”. Using this technique various metals, alloys, intermetallic compounds and semiconductors were fabricated. Mechanical properties of tensile strength on lotus-type porous metals are described; lotus-type porous iron fabricated using a pressurized nitrogen gas instead of hydrogen exhibits superior strength. The lotus materials can be applied to various functional materials. Some examples are also shown in this paper.
Extended Effective-Mean-Field Analysis for Electrical Conductivity of Lotus-Type Porous Nickel
Authors: Tane Masakazu , Hyun Soong Keun , Nakajima Hideo
Published: March 2009

We studied the effective electrical conductivity of lotus-type porous nickel with cylindrical elongated pores by applying the extended effective-mean-field (extended EMF) theory that is based on Hatta-Taya’s theory and Bruggeman’s effective-medium approximation. We modeled lotus-type
porous nickel as the composite materials with ellipsoidal void inclusion, and examined the effect of shape and orientation of the pores and applied-electric-field direction on the effective electrical conductivity. The extended EMF theory revealed that well-known Archie’s power law is quite useful for expressing the porosity dependence of the electrical conductivity of lotus-type porous metals even
though the deviation of porous morphology exists.
Enhancement of Reaction of Zinc on Superficially Nanocrystallized IF Steel by Near Surface-Severe Plasitc Deformation
Authors: Minamino Yoritoshi , Tsuji Nobuhiro , Koizumi Yuichiro , Nakamizo Y. , Sato M. , Shibayanagi Toshiya , Naka Masaaki
Published: March 2009

The reaction between the zinc plate (ZP) and the IF steel with near surface ultra fine grains (NSUFG) structure with grain size of about 89 nm was studied in temperature range of 473K to 623K in order to elucidate the temperature dependence of the reactions and its mechanism, by comparison with the reactions of ZP to coarse grains (CG) sheet, superficial cold rolled CG sheet (CG+R) and
superficial cold rolled NSUFG sheet (NSUFG+R). It was found that this NSUFG structure considerably affected reactions between IF steel and ZP. There was almost no effect of superficial cold rolling on their reactions, but the NSUFG structure dramatically enhanced the reactions. The incubation times for appearance of the reaction layer and its layer width of ZP /(NSUFG or NSUFG+R) reactions are shorter and thicker than those of the ZP/(CG or CG+R) ones. The activation
energy for reaction was 107kJ/mol, which indicates that the volume diffusion in zinc side and the grain boundary diffusion in the iron side play an important role in the reaction. The layer growth up to the layer thickness less than about 10µm was controlled mainly by the interface reaction and it over about 10µm mainly by the diffusion mass transfer.
Effective Heat Transfer Analysis by Mesh Superposition Method
Authors: Kubo Futoshi , Zako Masaru , Kurashiki Tetsusei
Published: March 2009

In recent years, it has been proposed that multi-scale numerical analyses can be applied to structural design to reduce experimental efforts. Although many multi-scale analyses have been mainly applied to mechanical dynamics, they do not approach the subject from a thermal perspective, which is a very important phenomenon for structural design. With this consideration, in this paper we
dealt with the formulation and programming of the unsteady-state heat transfer problem by a mesh superposition method, which is spotlighted in the stress analysis field. The numerical results of the proposed method have good agreement with the conventional finite element method. It has also been verified that the developed program has good accuracy and that the proposed method is useful in the
design of engineering products.
Bi Effect on the Microstructure and Dielectric Properties of SrTiO3 Thin Films
Authors: Okhay Olena , Bergano Vitor M.X. , Wu Ai Ying , Vilarinho Paula M.
Published: March 2009

Crystalline (Sr1-1.5xBix)TiO3 (SBiT) thin films (0.002 ≤ x ≤ 0.5) were prepared by sol-gel on Pt/TiO2/SiO2/Si substrates. Cubic monophasic SBiT films were obtained for samples with x ≤ 0.167. For films with x ≥ 0.267 a second phase identified as Bi4Ti3O12 was observed. The lattice parameter of SBiT films increases with increasing Bi content, similar to the variation observed in SBiT ceramics. No obviously variation of the grain size with the Bi content was observed. The
dielectric constant ε´ at room temperature increases with increasing of Bi concentrations up to x ≤ 0.1. The loss tangent of Bi doped SrTiO3 films is approximately 0.05 and lower than undoped ST films at 10kHz. The higher values of ε´ of Bi doped ST films with x=0.1 and x=0.167 in comparison with undoped films may suppose the appearance of a dielectric anomaly at low temperatures, which will be dependent on the Bi content.
Electrical Properties of Fluorine Doped Diamond Like Carbon
Authors: Trippe Simone C. , Madaleno Joana Catarina , Pereira Luiz
Published: March 2009

In this work fluorinated Diamond Like Carbon (DLC) films have been grown with
different CF4 concentrations and have been studied by electrical DC measurements in a temperature range from 30 to 300 K. It was found that the samples grown with lower CF4 concentration show a small rectification, with a potential barrier lower than 0.3 V. The bulk conduction shows a trapcontrolled Space Charge Limited Current (SCLC), with characteristic trap energy between 0.08 and 0.13 eV, confirmed by the differential conductivity analysis. The activation energy (ranging from 50 to 140 meV) is also dependent on the sample fluorine concentration, decreasing with the fluorine concentration increase.
Aluminothermic Reduction of Niobium Pentoxide in a Hydrogen Plasma Furnace
Authors: Mendes Marcio W.D. , Santos António Carlos P. , Medeiros Francisca de Fatima P. , Alves Jr. Clodomiro , Silva A.G.P. , Gomes Uilame Umbelino
Published: March 2009

The aluminothermic reduction is a highly exothermal reaction between a metal oxide and aluminium. Conventionally this reaction is ignited by an electric resistance and the reaction products after cooling are in the form of a rigid block of mixed metal and aluminium oxide. In this work a new process of aluminothermic reduction is presented, in which the reaction is ignited by a hydrogen plasma. The niobium oxide and aluminium powders are high energy milled for six hours to form particles constituted of oxide and aluminum. Stoichiometric, substoichiometric and
superstoichiometric mixtures were prepared. The mixture was placed in a stainless steel tube (the hollow cathode) inside the reactor chamber. The chamber was firstly evacuated. Then hydrogen at low pressure was introduced. In the following an electric discharge between the cathode and the anode localized just above the cathode ignites the plasma. The plasma heats the particles on the surface of the powder layer and starts the reaction that proceeds in each particle since the reactants are intimately mixed. The heat generated by the reaction propagates deeper in the layer until the whole mixture reacts. Substoichiometric mixtures can be used because hydrogen takes part of the reduction. The Nb2O5 – Al starting powder mixture and the products of the reaction are characterized by laser grain size measurement and X-Ray diffraction (XRD). The products are in
form of powder or agglomerates of particles. Phases of reaction products was determined by XRD analysis and the particle size trough SEM.
Design and Development of Magnetic Sensors Based on Giant Magnetoresistance (GMR) Materials
Authors: Djamal Mitra , Darsikin  , Saragi Togar , Barmawi M.
Published: March 2009

This paper describes magnetic sensors that have been developed in the last three years. GMR thin film materials have been successfully developed using unpinned CoFe/Cu/CoFe sandwiches on Si(100) substrate using a home built dc-opposed-target magnetron sputtering (OTMS). The magnetization of the sandwich is measured using hysteresis loop instrument, the Vibrating Sample Magnetometer (VSM). It was found that the phase of GMR was formed, with the MR ratio 15.76%.
Detailed Structural Characterisation of Phosphor YAG:Ce3+ Particles Obtained via Spray Pyrolysis
Authors: Mančić Lydia , del Rosario G. , Marinković Z. , Milošević O.
Published: March 2009

The yttrium-aluminium garnet phase (YAG) represents a suitable host material for solidstate lasers and is widely used for various display applications being doped with rare-earth ions. Introduction of Ce3+ ion as a luminescence centre transforms it from insulating to effective phosphor material capable of emitting radiation in the visible spectrum. In this work Ce3+ doped YAG powder was obtained via aerosol route using nitrate precursor solution. Well-crystallized targeted phase was obtained after additional thermal treatment. A combination of different analysis techniques (differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy with determination of image metrology, energy dispersive spectroscopy, transmission electron microscopy) is used to obtain detailed information about the structural and morphological powder properties. The effects of both processing parameters and post annealing treatment conditions are discussed from the viewpoint of establishing the best relationship between them and produced YAG:Ce3+ crystal structure.
Improved Materials for Environmental Application: Surfactant-Modified Zeolites
Authors: Jovanović V. , Dondur V. , Damjanović Lj. , Zakrzewska J. , Tomašević-Čanović M.
Published: March 2009

The surface properties of zeolites A, X, Y and natural zeolite clinoptilolite (CLI)
functionalized by cationic surfactants were investigated. The quaternary ammonium type
surfactants, such as hexadecyltrimethylammonium (HDTMA) chloride,
stearildimethylbenzylammonium (SDMBA) chloride and distearildimethylammonium (DSDMA)
chloride, replaced inorganic cations like Na+ and Ca2+ on the external surface of zeolites. The
adsorption capacities of all organic cations followed the order of
CLI>CaY>CaX>CaA>NaY>NaX>NaA and increased with the increase of Si/Al molar ratio in
zeolite structure. This modification resulted in an alteration in the surface property of zeolites - it
changed from hydrophilic to hydrophobic. The adsorption of selected pesticides with different
hydrophobicity on surfactant-modified zeolites was studied. It is shown that surfactant-modified
zeolites can be used for removal of pesticides from the environment. The increase in hydrophobicity
of pesticides resulted in an increase in pesticide adsorption on SDMBA and DSDMA modified
zeolites.
Electrocatalytic Activity of Nano-Sized Ebonex/Pt for Underpotential Deposition of Hydrogen
Authors: Vračar Lj.M. , Krstajić N. , Elezović N.
Published: March 2009

The underpotential deposition of hydrogen was studied in 0.5 mol dm-3 HClO4 solution
on an electrode based on Ebonex-supported platinum electrocatalyst spread on rotation Au disk
electrode (Ebonex/Pt). Pt catalyst was prepared by the impregnation method from 2-propanol
solution of Pt(NH3)2(NO2)2 and Ebonex powder. Ebonex support (nonstoichiometric mixture of
titanium oxides) was characterized by: X-ray diffraction (XRD), energy dispersive X-ray
spectroscopy (EDX) and BET techniques. The synthesized catalyst was analyzed by TEM
technique. Voltammetric profiles at the Ebonex/Pt catalyst surface in 0.5 mol dm-3 HClO4 aqueous
solution obtained at different temperatures with the evaluation of the temperature effect on the
reversible adsorption of the Hupd state are presented and the thermodynamic state functions for H
adatom adsorption process are calculated. The chemisorptive energy strength of the Ebonex/Pt-H
state is estimated in order to establish the relationship between the surface structure and the
electrocatalytic activity of Ebonex/Pt electrode and compare it to the one for smooth polycrystalline
Pt.
Nanoindentation of In Situ Polymers in Hydroxyapatite/Poly-L-Lactide Biocomposites
Authors: Balać I. , Tang Chak Yin , Tsui Chi Pong , Chen Da Zhu , Uskoković P.S. , Ignjatović N. , Uskokovic Dragan P.
Published: March 2009

In order to obtain more accurate properties after compaction of hydroxyapatite
(HAp)/poly-L-lactide (PLLA) composite, high-resolution measurement of mechanical properties
method is proposed to determine the properties of each phase separately, leading to information that
are valuable for the development of new materials as well as for predictive modeling purposes. The
PLLA polymer processing conditions used in hot pressing of the composite strongly influence final
mechanical properties of the material in the solid state. Since the aim was to measure PLLA
material properties, acceptable findings could only be made using unconstrained, cured in situ
nanoindentation tests. A finite element analysis of the in situ indentation experiment was performed
to determine required size of plain polymer area, needed for indentation test, which would minimize
the particle influence on the matrix elastic behavior.
High-Temperature Fatigue of Deep Rolled Aluminium Alloy AA6110-T6
Authors: Juijerm P. , Altenberger I. , Scholtes Berthold
Published: March 2009

The precipitation-hardened aluminium wrought alloy AA6110-T6 (Al-Mg-Si-Cu) was mechanically surface treated (deep rolled) at room temperature. The cyclic deformation behavior and s/n-curves of deep rolled AA6110-T6 have been investigated by stress-controlled fatigue tests at room and elevated temperatures up to 250°C and compared to the polished condition as a reference. The effect of deep rolling on fatigue lifetime under high-loading and/or elevatedtemperature conditions will be discussed. The stability of near-surface residual stresses as well as work-hardening states (FWHM-values) was investigated by X-ray diffraction methods. Residual stress- and FWHM-depth-profiles before and after fatigue tests at elevated temperature are presented. It was found that the investigated AA6110-T6 aluminium alloy shows cyclic softening during stress controlled fatigue tests at room and elevated temperatures. Below a certain stress amplitude at a given temperature, deep rolling can enhance the fatigue lifetime of AA6110-T6 as compared to the untreated state through cyclically stable near-surface work hardening as indicated by stable FWHM values. From the s/n data of deep rolled and polished AA6110-T6, an effective boundary line for the deep rolling treatment in a stress amplitude-temperature diagram can be established.
Novel Technique for Joining of Thick Section Difficult-to-Weld Aluminium Alloys
Authors: Ilyushenko R. , Nesterenkov V.
Published: March 2009

One of the “show stoppers” in fusion welding of highly alloyed aerospace aluminium alloys is their
susceptibility for liquation cracking in the weld heat-affected zone. Liquation cracking is a
microscopic intergranular discontinuity, which occurs under the effect of welding thermal cycle
and in the presence of stresses involved with the welding process. These intergranular
discontinuities are often observed in welding of thick plates and extrusions, which usually have
relatively coarse elongated grains, that are generally oriented parallel to each other.
Friction Stir Welding (FSW) is a low temperature non- fusion process, which produces very fine
equiaxed grain structure in the weld nugget for majority of Al-alloys. It was found that bead-onplate
FS welds performed on alloy, which in fusion welding is susceptible to liquation cracking,
were crack free. It was therefore proposed to use FSW for grain refining of the parent material by
putting a number of overlapping FS welds onto the edges of both parent plates prior to joining by
fusion welding. Experimentation has shown that there was no liquation cracking after the final weld
was performed. This novel welding method has been successfully proven for Electron Beam
Welding (EBW) of various Al-alloys including joining of dissimilar materials. The details of
experiments as well as welded coupons test results are presented.