bluuebunny/crossref_metadata_2025 huggingface dataset:
TGO Growth Behavior with Thermal Fatigue and Its Effect on Fracture Behavior of Thermal Barrier Coatings
Authors: Kwon Jae Young , Jang Hyung Jun , Jung Yeon-Gil , Paik Ung Yu
Published: March 2009

Growth behavior of thermally grown oxide (TGO) layer with thermal fatigue condition in thermal barrier coatings (TBCs) was investigated, including its effect on fracture behavior of TBCs and bonding strength of top coat. The formation of TGO layer was influenced by both temperature and time exposed. However, the TGO thickness was independent on the bond coat thickness (80, 140,
and 280 µm) and the preparing method (APS and HVOF methods) of the bond coat. In Hertzian indentation tests for the TBCs before thermal fatigue, the TBCs with the bond coat prepared by APS showed fracture and/or delamination in regions of the top coat near to the interface, whereas the TBCs prepared by HVOF indicated cracks and fracture at the interface. After thermal fatigue, the
fracture path passed along the TGO layer without any cracks created from Hertzian indentation within the top coat in both cases. The bonding strength of the top coat measured by adhesion tests shows lower values for the TBCs with the HVOF bond coat than those with the APS bond coat before thermal fatigue. However, the values are similar to each other after thermal fatigue. This result is attributed to the fracture path of the TBCs, depending on the TGO formation.
Relationship between Microstructure and Tensile Strength in the Directionally Solidified (23-27) at. % Al-Ni Alloys
Authors: Lu Y. , Kim H.C. , Lee Je Hyun , Oh Myung Hoon , Wee Dang Moon , Hirano Toshiyuki
Published: March 2009

Directional or single crystal technique was applied to enhance the ductility, and two phases of γ (Ni) phase or β (NiAl) phase in γ‘(Ni3Al) matrix were also considered to increase the strength and ductility. In this study, directionally solidified rods were prepared at the solidification rate of 50µm/s in 23-27 at.% Al-Ni alloys, and tensile strengths of these rods were analyzed at room temperature. Directionally solidified samples showed the γ dendrite fibers formed in the Ni3Al matrix
in the hypo eutectic composition of 23 at.% Al, the γ‘ single phase in the eutectic composition of 24.5 at. % Al, and the β dendrite fibers in the γ‘ matrix in the hyper eutectic compositions of 25, 26, 27 at.% Al. The hypoeutectic alloy including γ dendrites with γ‘ matrix exhibited a large elongation of over 70% with ductile transgranular fracture at room temperature. With increasing Al contents, the γ
dendritic microstructure changed to the β dendrite in the γ‘ matrix, which resulted in decreasing the elongation by increasing the volume fraction of the brittle β dendrites in the ductile γ’ matrix.
Effect of Melt Depth and Nozzle Type on the Mixing Behavior in Bottom-Blown Steelmaking Ladle – A Water Model Approach
Authors: Cho Sung-Ho , Kim Chang Won , Han Jeong Whan , You Byung Don , Kim Dong Sik
Published: March 2009

It is generally well known that a steelmaking ladle operation plays an important role in
the production of clean steel. A turbulent mixing of melt with Ar gas bubbling from the ladle bottom can homogenize a melt temperature and can control precisely chemical compositions of steel. In order to figure out these phenomena, a quantitative analysis of fluid flow behavior of gas and melt during a ladle operation is required and special concerns should be focused on effects of operating parameters on the perfect mixing time of melt. In this study, as a basic approach, effects of operating parameters such as a melt depth (aspect ratio) and a nozzle type (one-hole or porous plug) on the mixing behavior in ladle operation are investigated. Water model experiments are carried out to simulate these melt behaviors in steelmaking ladle. As a result, it was found that there exist an optimized melt depth and a nozzle type at a given gas flow rate, which affect significantly on the mixing behavior of melt.
Effect of Frit Content in Ag Paste and Thickness of Transparent Dielectric on Yellowing Phenomenon
Authors: Jeon Jae Sam , Cha Myung-Ryoung , Kim Nam-Sok , Kim Hyung Sun
Published: March 2009

To determine the causes of the yellowing phenomenon on transparent dielectrics, we
investigated a bus electrode and transparent dielectric, varying the amounts of frit content in the Ag paste and experimenting with the thickness of the dielectric. It was found that increasing the frit content in the Ag paste coating caused the transparent dielectric to experience greater discoloration, so that it gradually turned a deep yellow, which suggests that oxygen in the air is a factor causing
discoloration of the transparent dielectric during firing.
Cell Sensing Margin of Lead-Free (Bi,La)4Ti3O12Thin Film Deposited on MTP Cell Structure in High Density FeRAM Device
Authors: Choi J.H. , Yoo H.S. , Cho K.W. , Kim N.K. , Oh S.H. , Choi E.S. , Yeom S.J. , Sun H.J. , Lee S.S. , Lee K.N. , Hong Suk Kyoung , Hong Tae Whan , Kim Il Ho , Ryu Sung Lim , Kweon Soon Young
Published: March 2009

A 16Mb 1-transistor /1-capacitor (1T1C) FeRAM device was fabricated with lead-free Bi3.25La0.75Ti3.0O12 (BLT) capacitors. The key integration processes contain a scalable MTP (Merged Top-electrode and Plate-line) cell structure and reliable BLT ferroelectric capacitors. Ferroelectric properties of BLT films were optimized on the newly developed MTP cell structure. BLT films were coated on Pt/IrOx/Ir bottom electrode using sol-gel solutions. The composition of the optimized BLT film was about Bi3.25La0.75Ti3.0O12. The switchable polarization obtained in a 100nm-thick BLT film was about 20 µC/cm2 at the 3 V applied voltage, and the optimized BLT film showed a few fatigue losses about 10% up to 1 × 1011 cycles. The imprint properties of the BLT film were also characterized at 25°C and 90°C operating temperature after 125°C data storage. The average cell signal sensing margin between data "1" and data "0" was measured to be about 900 mV, which is a
sufficiently large margin for device operation.
Interfacial Reaction and Joint Strength on Cu UBM with Pb-Free Flip Chip Solder Bumps
Authors: Kim Dae Gon , Ha Sang Su , Jung Seung Boo
Published: March 2009

The interfacial reaction and joint strength of the Pb-free flip chip solder joints were
investigated. Microstructural investigations were conducted using scanning electron microscopy (SEM), and phase analysis of the intermetallic compound (IMC) was carried out using energy dispersive spectrometer (EDS). Cu6Sn5 IMC layer was formed at the as-reflowed state, and Cu3Sn was additionally settled at the interface between the Cu6Sn5 and Cu under bump metallurgy (UBM).
Growth of the IMC layers followed the parabolic law, while the IMC layer growth was not highly affecting the mechanical properties of the solder joints. The shear force of the solder joints decreased because of the microstructural coarsening within the solder region.
TEM Observation of Interfacial Reaction Layers Formed Between Pb(Lead)-Free Sn-3.5Ag Solder and ENIG Plated Cu Substrate
Authors: Yoon Jeong Won , Jung Seung Boo
Published: March 2009

The interfacial reaction between eutectic Sn-3.5Ag solder and ENIG substrate during
reflow was investigated. During the reflow, the topmost Au layer dissolved into the molten solder, and the reaction layers of Ni3Sn4/Ni-Sn-P/Ni3P formed between Sn-Ag solder and Ni-P plating layer. After the reflow at 255 for 3 min, most of Ni3Sn4 intermetallic compound (IMC) spalled off the substrate. The formation of thick Ni3P and Ni-Sn-P layers was related to the direct reaction between
solder and Ni-Sn-P layer by the IMC spalling.
Reliability of Sn-Ag-Cu Flip Chip Package with Underfill under Thermal Shock
Authors: Noh Bo In , Jung Seung Boo
Published: March 2009

Thermal fatigue properties of solder joints encapsulated with underfill were studied
conducting thermal shock tests. Flip chip package with electroless nickel-immersion gold plated on FR-4 substrate and the Sn-3.0Ag-0.5Cu solder ball was used. The fatigue property of package with underfill was better than the package without it. The fatigue property of package with underfill which has a higher glass transition temperature (Tg) and lower coefficient of thermal expansion (CTE) was better than that of package with underfill with lower Tg and higher CTE.
Sliding Wear Behaviors of Steam Generator Tubes in Various Environments
Authors: Kim Gyung Guk , Noh Seung Dae , Park Gi Sung , Kim Seon Jin , Lee Deok Hyun , Hur Do Haeng , Choi Myung Sik , Han Jung Ho
Published: March 2009

Wear damage of steam generator tubes for nuclear power plants can cause the leakage of radioactive substances. Therefore, the evaluation of integrity and safety for tubes is very important from the viewpoint of nuclear ecocide. In the present study, to investigate the wear properties of Inconel 600 and 690 steam generator tube materials mated with 409 stainless steel commonly used
as support plate, sliding wear tests were performed with increasing sliding distance in air and in elevated temperature water environment, respectively. The wear volume of tube materials was less than those of supports under all conditions. There were no significant differences in the wear behavior for the Inconel 600 and 690 tubes, independently of the testing environment.
Development of Novel Wastewater Reclamation System Using Microfiltration with Advanced New Membrane Material and Electrodialysis
Authors: Kim Jong Oh , Jeong Jong Tae , Kim Seog Ku , Kim Ree Ho , Lee Yong Jae
Published: March 2009

The integrated system of microfiltration and electrodialysis was proposed for wastewater reclamation, and the treatment performances were experimentally investigated with a pilot-scale system. The filterability of membrane and the long-term operational performances of the system were focused with real municipal sewage. The suggested wastewater reclamation system shows stable water quality during operational period over 6 months. Therefore, it is believed to be a useful
system for reuse of wastewater and security of water resources.
Zeolite Synthesis from Coal Bottom Ash for Recycling as an Absorbent of Heavy Metals
Authors: Ahn Ji Whan , Han Gi Chun , You Kwang Suk , Um Nam Il , Cho Hee Chan
Published: March 2009

This study focused on the synthesis of zeolite from coal bottom ash and the CEC
assessment of synthesized products. To that end, zeolificaion tests were carried out at four temperature levels (80, 100, 120, 150oC) and five NaOH concentration levels (1, 2, 3, 4, 5M) by the alkali hydrothermal method. Consequently, NaP1, hydroxy-sodalite, and tobermorite were produced
from coal bottom ash. NaP1 with an excellent cation exchange capability had a high crystallinity at below 2M NaOH and 120 oC; and the maximum CEC value was 160meq/100g at 2M NaOH and 120 oC under the given conditions.
Effect of Hydrogen Content on Characteristics of Cu/C: H Films Coated on Polyethylene Terephthalate Substrate Prepared by ECR-MOCVD Coupled with a Periodic DC Bias
Authors: Lee Joong Kee , Jeon Bup Ju , Lee Sang Wha
Published: March 2009

Cu/C:H films were prepared on the PET (polyethylene terephthalate) substrate under room temperature by ECR (electron-cyclotron-resonance) chemical vapor deposition coupled with a (-)DC bias system. Hydrogen contents in the plasma strongly affected the crystallographic structures, sheet resistivity, and the composition of deposited films. Cu (111) peaks by XRD analysis were
clearly observed with the increase of hydrogen contents. The surface morphology also indicated that copper grains of very fine crystallites were incorporated in the metal-organic composite films by the introduction of hydrogen gas to the plasma. Cu/C:H composite films exhibited a good adhesion force due to the generation of sp3-CH2 bonding. These observations imply that hydrogen induced the
formation of stable volatile organic compounds and the reduction of copper, consequently leading to a significant alteration of the crystallographic structure and composition of deposited films. Finally, the EMI shielding efficiency was increased by the addition of hydrogen gas to the plasma, probably due to the increase of copper contents in the film.
Sputter-Deposited Cr as an Alternative to Electroplated Cr
Authors: Lee Chong Mu , Kim Kyung Ha , Lim Jong Min
Published: March 2009

Since the hexavalent chromium used in chromium electroplating was found to cause cancer in human body, alternative deposition techniques have been widely investigated. Sputter deposition of chromium (Cr) as a deposition technique for replacing electroplating was studied. Effects of RF-power, substrate temperature on the deposition rate, corrosion-resistance, hardness and adhesion strength were investigated. X-ray diffraction (XRD) analysis was performed to determine the structure and the compositions of the films. The hardnesses of the films were measured by using a nanoindenter. The microstructures of the films were observed using scanning electron microscopy. The deposition rate and hardness of the sputter-deposited Cr film tend to increase with the increasing RF-power and substrate temperature of the sputtering process. Both the hardness and adhesion strength of the sputter-deposited chromium film was found to be higher than those of the electroplated chromium film.
Removal of Bilirubin by Albumin-Fixed Polysulfone Membrane
Authors: Ge Dong Tao , Shi Wei , Ren Lei , Zhang Qi Qing
Published: March 2009

An asymmetric polysulfone membrane with reactive group of –OH was obtained by hydrolyzing the chloromethylated polysulfone membrane, and the albumin molecules were immobilized into the membrane with a crosslinking reagent of 1,4-butanediol diglycidyl ether. The albumin-fixed membrane was used to remove lipophilic toxins, bilirubin, from the bilirubin-albumin solution. The experiment results showed that the transfer rate of bilirubin was clearly enhanced after fixing albumin into the hydroxylated polysulfone membranes. The clearance of bilirubin was 49.3%. In addition, the effect of membrane thickness on the removal of bilirubin is discussed.
Effect of Physical and Chemical Change of Lignocellulosic Fiber on Heavy Metal Ion Removal
Authors: Lee Beom Goo , Lee Hyun Jong , Shin Dae Yong
Published: March 2009

Kenaf bast, coconut coir, and cotton, which are lignocellulosic fibers and environment
friendly natural materials, were tested for their ability to remove copper, nickel, and zinc ions from aqueous solutions according to their physical and chemical changes by solvent extraction. The order of the lignin and xylose content in unextracted fibers is coconut coir>kenaf bast>cotton. The fiber with the highest level of heavy metal removal, however, was kenaft bast. It showed that removal of heavy metals does not correlate with lignin and xylose content. Cotton, with about 1.1% lignin and
0.3% xylose, was very low in heavy metal ion sorption while other two fibers containing lignin and xylose did remove heavy metal ions. It indicates that lignin and xylose play a role in heavy metal ion sorption. Extraction with the various solvents removed different cell wall components and changed the cell wall structure, and thus did change the heavy metal ions removal capacity of lignocellulosic fibers.
Surface Characteristics of the Engineered Polymeric Media for Filtration and Adsorption in Urban Runoff
Authors: Kang Sung Won , Kim Seog Ku , Kim Young Im , Yun Sang Leen , Lee Tae Yoon
Published: March 2009

Urban runoff is one of the major sources that contaminates water supplies because it
contains toxic compounds such as heavy metals and PAHs (poly aromatic hydrocarbons) as well as suspended solids, organic compounds, and nutrients. The eingineered polymetric media in this research were developed as filtering media in the storm water treatment equipment. The media used in this study can remove contaminants in urban runoff via adsorption and filtration. The engineered media composed of polypropylene and anion surfactant were foamed to have buoyacy
and then shattered by mechanical device for efficient filtration. Surface characteristics of the engineered media were determined by using a scanning electron microscope and a microscope. Results indicated that surface area of the engineered media were increased from less than 0.05m2/g for the neither foamed nor shattered media to 7.82m2/g for the foamed and shattered media. Specific
gravity of the media that were foamed and shattered was 0.108~0.154 whereas the non-treated media had specific gravity of 0.914. Fractal dimension of media was measured for the irregularity of the media shape and the media that had high fractal dimension value was performed high filtration efficiency of suspended solids in runoff.
Investment Casting of Ti Alloys for Biomedical Application
Authors: Sung Si Young , Kim Young Jig
Published: March 2009

The aim of this study is to clarify the alpha-case formation mechanisms for the economic net-shape forming of Ti and Ti alloys. The α-case formation reaction between Ti and Al2O3 mold was examined in a plasma arc melting furnace. The reaction products were characterized by using an electron probe micro-analyzer and transmission electron microscopy. The α-case generation between
Ti and Al2O3 mold could not be explained by the conventional α-case formation mechanism, which is known to be formed by the interstitials, especially oxygen dissolved from mold materials. However, on the basis of our experimental results and thermodynamic consideration, it was confirmed that the α-case is formed not only by interstitial oxygen atoms but also by substitutional metal atoms
dissolved from mold materials. Based on the α-case formation mechanism, α-case free net-shape forming of Ti and Ti alloys could be possible for biomedical applications.
Synthesis and Properties of Bulk Amorphous/Nanocrystalline Aluminum Alloy Composites
Authors: Noh Si Joon , Jung Taek Kyun , Lee Dong  Suk , Kim Mok Soon , Yi Sung
Published: March 2009

The rod-shaped bulk composites consisting of Al-10Ni-6Ce and Al-4Fe-0.6Mo-1.1V-
0.3Zr alloy (mixing ratio; 0.7:0.3, 0.5:0.5 and 0.3:0.7) and corresponding monolithic alloys were produced to a full density via powder forging process. The process involved pre-compaction of rapidly solidified alloy powders and subsequent isothermal forging at 673K. The forged Al-10Ni- 6Ce alloy exhibited nano-scaled crystalline particles, such as fcc-Al, Al3Ni, Al4Ce and Al11Ce3 phase, coexisting with an amorphous phase. In the case of the forged Al-4Fe-0.6Mo-1.1V-0.3Zr
alloy, an equiaxed grain structure was observed to exist with uniformly distributed nano-scaled Al- Fe based intermetallics. The monolithic Al-10Ni-6Ce alloy had a considerably high maximum compressive strength (MCS) of 1.35 GPa without showing any compressive plastic strain (CPS). In contrast, the monolithic Al-4Fe-0.6Mo-1.1V-0.3Zr alloy possessed noticeably high CPS of 25% with the MCS of 0.71GPa. The composites acquired the CPS varying from 1 to 5.8 % and the MCS
from 1.26 to 0.74 GPa, with increment of the volume fraction of Al-4Fe-0.6Mo-1.1V-0.3Zr alloy from 0.3 to 0.7.
A Fast and Low Temperature Eco-Process for Alloy's Joining
Authors: Fu Zheng Yi , He D.H. , Zhang Jing Ying , Wang Wei Min , Wang Hang , Zhang Qing Jie
Published: March 2009

In this paper, we suggest PCH as a method of joining alloys. The temperature
distribution in the samples during the joining process was analyzied. From the temperature distribution profiles in PCH joining, it is concluded that PCH for the joining has two advantages: (1) There is a temperature distribution peak along the sample. The contacting surfaces which need high temperature happen to obtain the highest temperature; (2) The parts to be joined at relatively lower temperatures can avoid the damage of heat attack. The optimal joining conditions were discussed. The PCH and HP techniques were compared for the joining of alloys. It was found that the high tensile strength joined structure of alloys can be fabricated by PCH method at lower joining temperature, shorter holding time, and lower pressure, compared with that by HP method. The PCH process was considered to be an eco-friendly process compared with the traditional heat diffusion joining methods.
Design of Efficient TiO2/SiC Photocatalysts from TiC-SiC Nano Particles for Degradation of Organic Pollutants Diluted in Water
Authors: Yamashita Hiromi , Nishida Yoshikatsu , Chiyoda Osamu , Nose Hiroyuki , Narisawa Masaki , Ohmichi Tesutaro , Katayama Iwao
Published: March 2009

TiO2/SiC was prepared by oxidizing the TiC-SiC precursor obtained by carbothermic
reduction process of TiO2-SiO2 binary oxide. An XRD analysis indicated the formation of the mixture of anatase and rutile phases of TiO2 crystalline after the oxidation of TiC-SiC sample. TiO2/SiC photocatalyst exhibited a higher photocatalytic reactivity than TiO2-SiO2 binary oxide prepared by the conventional sol-gel method. These results indicate the advantages of SiC nano
powders as catalyst support of the TiO2 photocatalysts, and TiO2/SiC photocatalyst is effective for the degradation of organic compounds diluted in water.
Solvents Effects on Physicochemical Properties of Nano-Porous Silica Aerogels Prepared by Ambient Pressure Drying Method
Authors: Lee Seung Hun , Lee Eun A , Hwang Hae Jin , Moon Ji Woong , Han In Sub , Woo Sang Kuk
Published: March 2009

Hydrophobic silica aerogels were synthesized by an ambient pressure drying method from silicic acid with a different pH value, which was prepared from sodium silicate solution (water glass). In this study we chose various hydrocarbon class solvents such as pentane, hexane, heptane, and toluene, and performed surface modification in TMCS (trimethylchlorosilane)/solvent solutions in order to improve reproducibility in aerogel production. Densities of the aerogels were about 0.1 ~ 0.3
g/cm3 , and apparent porosities were 88 ~ 96 %, depending on the processing conditions. Specific surface area was approximately 730 ~ 950 m2/g, and average pore size around 10 nm.
Estimation of Environment-Friendly Permeable Pavement at Laboratory Test
Authors: Kim Ree Ho , Jeong Jinwoo , Lee Sang Ho , Gee Chae Sung
Published: March 2009

The creation of large impervious surface in urban and urbanizing areas commonly leads to multiple impacts on the stream systems including higher peak runoff, reduced infiltration, and increased pollutant loads to streams. Permeable pavements made up of a matrix of concrete blocks with voids offer one solution to the problem of increased stormwater runoff and decreased stream water quality. Experiment results indicate that lower pore size pavement showed a higher runoff reduction rate compared with other pavement. Also, water absorption capability of pavement will
drop the surface temperature of pavement. Compared to runoff, the turbidity and phosphorus concentration were lower than 27 [NTU] and 0.5 [mg/L], respectively. It appears that turbidity and hosphorus are concentrated in the pavement void.
Via/Hole Filling by Pulse-Reverse Copper Electroplating for 3D SiP
Authors: Chang Gun Ho , Chang Si Young , Lee Jae Ho
Published: March 2009

Copper via filling is an important factor in 3D stacking interconnection of SiP (system in package). As the packaging density is getting higher, the size of via is getting smaller. When DC electroplating is applied, a defect-free hole cannot be obtained in a small size hole. To prevent the defects in holes, pulse and pulse reverse current was applied in copper via filling. The size of 50, 70,
100 in diameter and 100 in height. The holes were prepared by DRIE method. TaN and Ta was sputtered for copper diffusion barrier. Via specimen were filled by DC, pulse and pulse-reverse current electroplating methods. The effects of additives and current types on copper deposits were investigated. Vertical and horizontal cross section of the via were observed by SEM to find the defects in via. When pulse-reverse electroplating method was used, defect free via were uccessfully obtained.
Effect of Compatibilizers on the Properties of Nano-Hydroxyapatite Reinforced Polyamide 66 and High Density Polyethylene Blends
Authors: Zuo Yi , Li Yu Bao , Zhang Xiang , Yang Wei Hu , Li Ji Dong , Mo Li Rong , Wang Hua Nan
Published: March 2009

The compatibility efficiency on different compatibilizer for nano-hydroxyapatite
(n-HA) reinforced polyamide 66 (PA66) and high density polyethylene (HDPE) blends at a composition of 40/42/18 as functionalized biomaterial was investigated by mechanical properties testing and scanning electron microscopy (SEM). The results showed that mechanical properties of compatibilized blends were much improved by the compatibilizers of maleic anhydride grafted
polyethylene (PE-g-MAH) and ethylene/methacrylic acid ionomer-sodium ion (ION) compared with the uncompatibilized blends. Blends had peak mechanical values of different compatibilizer. Both PE-g and ION formed adhesion during melt mixing and stabilized the morphology and significantly reduced the size of dispersed PE phase. PE-g gave the blends with PE spheres ranging from 1 to 4µm and ION with well-dispersed spheres with an average diameter of 1µm. The more
enlarged interphase of the blends containing ION reduced the lower interfacial energy to increase the miscibiliy of the blends. Consequently, ION had better contribution to rigidity properties than PE-g for n-HA/PA/PE blends.
Isothermal Oxidation Behavior of Ru Modified Aluminide Coating on a Fourth Generation Single Crystal Superalloy
Authors: Matsuoka Yuki , Chikugo Kazuyoshi , Suzuki Takakazu , Matsunaga Yasuo , Taniguchi Shigeji
Published: March 2009

Ru coating prior to aluminizing is one of the effective methods to reduce the harmful intermediate layer that forms under the coating (SRZ) on a 4th generation Ni-base SC superalloy. This study examined the short-term isothermal oxidation behavior of this Ru-modified coating at 1373 K in air. Surface observation by SEM showed that the scale becomes flat and uniform in comparison to simple aluminide coating. XRD and cross-sectional analysis results also showed that phase transformation from β-NiAl to γ’-Ni3Al seldom occurs in the Ru-modified coating layer leading to the prevention of local oxidation.
Observation of Lattice Defects and Nondestructive Evaluation of Fatigue Life in FeAl and Ni3Al Based Alloy by Means of Magnetic Measurement
Authors: Umakoshi Yukichi , Yasuda Hiroyuki Y.
Published: March 2009

A magnetic technique was applied to examine cyclic deformation behavior and
deformation damage in ordered FeAl and Ni3(Al,Ti) single crystals. The fatigue lifetime of FeAl was evaluated by an abrupt increase in spontaneous magnetization. The morphology of γ precipitates in Ni3(Al,Ti) during annealing and deformation was examined by changes in spontaneous magnetization and coercive force.
Change of Interlayer Exchange Coupling between the Adjacent Magnetic Transition Metal Layers across a Rare-Earth Metal Layer by Hydrogenation
Authors: Endo Yasushi , Sato Takanobu , Kaneko Tadashi , Kawamura Yoshio , Yamamoto Masahiko
Published: March 2009

We have studied the change of the interlayer exchange coupling between the adjacent magnetic transition metal (TM) layers across a rare-earth metal (REM) layer by hydrogenation in TM (10 nm)/REM (t nm)/TM (10 nm) trilayers composed of Fe and Co as the TM and Y as the REM. In the case of the Fe as TM, the magnetic properties are sensitive to hydrogenation. In particular, the interlayer exchange coupling changes remarkably by hydrogenation. On the other hand, in the case of the Co as TM, the magnetic properties do not change by hydrogenation, and the change of the coupling by hydrogenation cannot be confirmed. The difference of the change of the coupling by hydrogenation between TM=Fe and TM=Co should be attributed to the difference of the TM/Y interface state.
Martensitic Transformation of Ni-Mn-Ga Alloys under Magnetic Field and Hydrostatic Pressure
Authors: Kim Jae Hoon , Fukuda Takashi , Kakeshita Tomoyuki
Published: March 2009

The effects of magnetic field and hydrostatic pressure on martensitic transformation have been systematically investigated by using Ni2MnGa, Ni2.14Mn0.84Ga1.02, and Ni2.14Mn0.92Ga0.94, which exhibit P(parent phase)-I(intermediate phase)-10M, P-14M-2M, and P-2M transformation, respectively. The following results were obtained. (i) The P-I transformation temperature does not
change by magnetic field. (ii) The I-10M and the P-14M transformation temperatures decrease under applied magnetic field up to 0.8 MA/m and 0.4 MA/m, respectively, and then increase with increasing applied magnetic field higher than those fields. (iii) The 14M-2M transformation temperature increases under a magnetic field up to 0.4 MA/m and decreases under magnetic field up
to 0.8 MA/m and then increases again when the magnetic field becomes higher than 0.8 MA/m. (iv) The P-2M transformation temperature increases linearly with increasing applied magnetic field. (v) All transformation temperatures increase linearly with increasing hydrostatic pressure. The experimental results mentioned above (i)~(iv) under magnetic field can be well explained by using the Clausius-Clapeyron equation.
Strong Localization of Electromagnetic Wave in Ceramic/Epoxy Photonic Fractals with Menger-Sponge Structure
Authors: Kirihara Soshu , Takeda Mitsuo Wada , Sakoda Kazuaki , Honda Katsuya , Miyamoto Yoshinari
Published: March 2009

Menger-sponge is a three dimensional fractal structure with self-similar patterns. We
fabricated the Menger-sponge structure composed of epoxy with titania-based ceramic particles dispersion by using a stereolithography CAD/CAM system. It has a cubic body of 27 mm in edge size with square through holes of 1, 3 and 9 mm. The structure is characterized with a fractal dimension D = 2.73 and a fractal stage 3. The electromagnetic wave response of the Menger-sponge was measured
by using a network analyzer. Both reflection and transmission amplitudes of incident waves showed remarkable attenuations to -50 dB at 8 GHz simultaneously. The electric field intensity in the center holes in the Menger-sponge was measured by using a mono-pole antenna. The electromagnetic energy was localized in the central air cavity by forming the strong localization mode. The localized mode
frequency can be controlled by changing the structure size, number of stage, and the effective dielectric constant. We call such fractal structures as the photonic fractal.
Crystallographic Approach to Regenerated and Pathological Hard Tissues
Authors: Nakano Takayoshi , Ishimoto Takuya , Lee Jee Wook , Umakoshi Yukichi , Yamamoto Masaya , Tabata Yasuhiko , Kobayashi Akio , Iwaki Hiroyoshi , Takaoka Kunio , Kawai Mariko , Yamamoto Toshio
Published: March 2009

A dominant inorganic substance in hard tissue is known to be a biological apatite (BAp)^nano-crystal which basically crystallizes in an anisotropic hcp lattice, and the BAp c-axis is parallel to extended collagen fibrils. We applied the microbeam X-ray diffractometer system with an incident beam spot 100µm or 50µm in diameter to the original, regenerated and pathological hard tissues in order to analyze the preferential alignment of the BAp c-axis as a parameter of bone quality closely
relating to the mechanical function. We conclude that the BAp orientational distribution in the hard tissues is a new measure to evaluate stress distribution in vivo, nano-scale microstructure and the related mechanical function, healing process of the regenerated bone and progress of the bone diseases.
Fabrication of Porous Aluminium and Copper Media by Using Monotectic Solidification under a Magnetic Field
Authors: Yasuda Hideyuki , Ohnaka Itsuo , Dhindaw B.K. , Fujimoto Shinji , Takezawa N. , Tamayama T. , Tsuchiyama A. , Nakano T. , Uesugi Kentaro
Published: March 2009

Unidirectional solidification of Al-In, Cu-Pb and Cu-Pb-Al monotectic alloys was
performed under static magnetic fields up to 10T for formation of the regularly aligned-rod structure. mThe imposition of static magnetic fields exceeding 4T suppressed movement of the In liquid droplets at the Al solidifying front and enhanced the engulfment of the In droplets into the front. As a result,
the eutectic-like structure was obtained in the Al-10 and 15at%In hypermonotectic alloys. The micro X-ray tomography indicated that the continuous In rods with diameters of 10-20 µm were aligned parallel to each other. In the case of the Cu-Pb and the Cu-Pb-Al alloys, the imposition of static magnetic fields also enhanced the formation of the aligned Pb rods. The electrochemical etching by using a 10% HNO3 solution successfully removed the minor phase, and the porous aluminum and
copper with deep pores were fabricated.
Fabrication and Tensile Properties of Lotus-Type Porous Iron and SUS304L Stainless Steel
Authors: Hyun Soong Keun , Ikeda Teruyuki , Tane Masakazu , Nakajima Hideo
Published: March 2009

Lotus-type porous iron and stainless steel (SUS304L) whose long cylindrical pores are aligned in one direction were fabricated by unidirectional solidification in a pressurized hydrogen or nitrogen gas atmosphere. Pores are formed as a result of precipitation from the supersaturated gases when the liquid metal dissolved with gas atoms is solidified. The ultimate tensile and yield strengths of the porous iron produced in nitrogen atmosphere are about two times higher than in a hydrogen
atmosphere. Such superior strength is attributed to solid-solution hardening due to solute nitrogen atoms in iron matrix.
Analysis of Second Harmonic Pulse Distortion Induced by Repetitive Irradiation
Authors: Nomura Kazufumi , Ohmura Etsuji , Miyamoto Isamu
Published: March 2009

Shorter pulse duration and higher power lasers have accelerated the development of frequency conversion technique using nonlinear optical crystals for laser precision microfabrications. Previous theoretical studies concerning frequency conversion supposed one-pulse irradiation; accordingly, the influence of the temperature change of crystal induced by laser absorption was not considered, although practical frequency conversions are used with repetitive irradiation. Therefore, researches and developments of harmonic generation with repetitive irradiation have been approached experimentally or empirically. In this study, second harmonic generation considering laser absorption was analyzed theoretically. Output second harmonic pulse shape influenced by repetitive irradiation was evaluated, supposing that the intensity distribution of input pulse was temporal- and spatial-Gaussian. It was quantitatively revealed that a beam profile of output second harmonic pulse, especially generated by high input intensity, is distorted temporally and spatially even during extremely short time-ranges of one pulse. Our analysis suggests the possibility that this pulse distortion influences on processing accuracy.
Bonding of Various Metals Using Ag Metallo-Organic Nanoparticles-A Novel Bonding Process Using Ag Metallo-Organic Nanoparticles-
Authors: Ide E. , Angata S. , Hirose Akio , Kobayashi Kojiro F.
Published: March 2009

We propose a novel bonding process using Ag metallo-organic nanoparticles, of which the average particle size is around 11 nm. In this paper, Al, Ti, Ni, Cu, Ag and Au disc joints were made using the Ag metallo-organic nanoparticles in order to investigate the bondability of the various metals. These joints are evaluated based on measurement of the shear strength, and the observation of the fracture surfaces and the cross-sectional microstructures. The shear strength of
the various metal joints increased in the following order: Al, Ti, Ni, Cu, Ag and Au. This corresponds to the order of the standard-free energy value of the oxide formation for each metal. In particular, while the strengths of the Cu, Ag and Au joints, in which the oxides can be reduced by carbon, were the same level, those of the Al and Ti joints, of which the oxides were more stable than carbon oxides, were extremely low. This result suggests that the carbon atoms or organic elements
generated by the decomposition of the organic shell of the Ag metallo-organic nanoparticles may play a role in deoxidizing the oxide film on the metal surface. This can promote chemical bonding between the Ag nanoparticles and metals at low temperatures.
Fundamental Measurements of the Friction on an Atomically-Flat Terrace of Au(100) in Sulfuric Acid Solution under Potential Control Using Electrochemical Atomic Force Microscope
Authors: Hirai Nobumitsu , Tooyama Tatsuya , Tanaka Toshihiro
Published: March 2009

Potential dependence of the friction force between an atomically-flat terrace of Au(100) single crystal and a tip attached to a silicon nitride cantilever of electrochemical atomic force microscope (EC-AFM) have been investigated qualitatively in 0.05 M H2SO4 aqueous solution. It is found that the friction force gains when the potential increases in the potential range between −400
mV and 400 mV vs Hg/Hg2SO4 electrode.
Microstructural Evolution during Simple Heavy Warm Deformation of a Low-Carbon Steel
Authors: Narayana Murty S.V.S. , Torizuka Shiro , Nagai Kotobu
Published: March 2009

We examined the microstructure development in low carbon steel (0.15% C) during heavy warm deformation (HWD) using field emission scanning electron microscopy (FESEM) and electron back-scattering diffraction (EBSD). Plane strain compression tests have been conducted in the temperature
range of 773-923 K at strain rates of 0.01 s-1 and 1 s-1 with the specimens deformed to 25% of their original thickness. We summarize the strain rate and temperature into the Zener-Hollomon parameter and investigate its variation with plastic strain on the basis of the evolved microstructures and grain boundary character with a view to understanding the critical conditions for forming ultrafine grains and classifying them. Once established, these compressive strain-Z parameter plots simplify the selection of processing parameters (such as strain, strain rate, and temperature), towards achieving tailor-made microstructures in industrial components.
Effect of Hydrogen on the Fracture Behavior of High-Strength Cr-Mo Steel
Authors: Wang Mao Qiu , Akiyama Eiji , Tsuzaki Kaneaki
Published: March 2009

We examine the hydrogen embrittlement susceptibility of a high-strength AISI 4135 steel by means of a slow strain-rate test (SSRT) using notched round bar specimens. Hydrogen was introduced into the specimens by electrochemical charging and its content was measured by thermal desorption spectrometry (TDS). It was found that the maximum tensile stress decreased in a power
law manner with increasing diffusible hydrogen content. Finite element method (FEM) calculations demonstrated that the peak value of the maximum principal stress and the peak value of the locally accumulated hydrogen concentration at the maximum tensile stress were in good agreement with one power law relationship for the specimens with different stress concentration factors.
Microstructure and Mechanical Properties of the Stainless Steels Obtained by Sintering Mixtures of AISI 316L and Silicon Powders
Authors: Sikorski K. , Szymańska Agnieszka , Sekuła M. , Kowalczyk D. , Kazior Jan , Kurzydlowski Krzysztof Jan
Published: March 2009

The aim of the study was to obtain a ferritic-austenitic stainless steel through sintering of the mixture of austenitic steel AISI 316L powders with silicon in the amount ranging from 1 to 7%. The pressed mixtures were sintered at 1240oC for 60 minutes under hydrogen atmosphere. The results of the silicon admixture on the density, porosity, microstructure and mechanical properties of the sintered specimens are discussed.
Quantitative Description of the Structure and Substructure of Hot − Deformed Fe – Ni Austenitic Alloy
Authors: Ducki Kazimierz J. , Hetmańczyk Marek , Kuc Dariusz
Published: March 2009

The paper presents the results of research concerning the influence of hot deformation parameters on the structure and substructure as well as the plastic properties of a Fe–Ni austenitic alloy. The research was performed on a torsion plastometer in the range of temperatures of 900÷1150°C, at a strain rate 0.1 and 1.0 s-1. Plastic flow curves have been drawn up and the interrelations have been determined between the process parameters and the recrystallized grain size, inhomogeneity and shape. Functional relations between the Zener-Hollomon parameter and the mean grain size after dynamic recrystallization have been developed and the hot deformation activation energy has been estimated. The examination of substructure on TEM allowed the calculation of structural parameters: the average subgrain area and the mean dislocation density. A detailed investigation has shown that the substructure is inhomogeneous, consists of dense dislocation walls, subgrains and recrystallized regions.
Surface Treatment of Human Dentin by KrF Laser
Authors: Eugénio S. , Sivakumar M. , Vilar Rui
Published: March 2009

In the present work, dentin samples extracted from human molar teeth were treated with 248 nm wavelength pulsed laser radiation at fluences between 0.5 and 20 J/cm2. The surfaces were characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and x-photoelectron spectroscopy (XPS). Two distinct behaviours were observed in what concerns the evolution of surface morphology with fluence and number of pulses. In some samples the surface remained flat, independently of the fluence and covered by a layer of resolidified material and redeposited ablation particles, which
often occluded the dentinal structure. In other samples the surface topography depended on radiation fluence. For fluences below 1 J/cm2, intertubular dentin was preferentially removed, originating a columnar structure where columns were centred on the dentinal tubules and constituted by peritubular dentin. The height of the columns increased with the number of laser pulses. When fluence exceeded 1 J/cm2 the processed surface remained flat, covered with a fine resolidified layer. These distinct behaviours of dentin can be explained by differences in the
constitution of this composite biological material. Despite the topographic changes observed, the mineral phase of dentin (apatite) remained unaltered and collagen was removed only from the outermost superficial layers of the processed material. This fact is explained by the constitution and structure of dentin and by the physical properties and electronic structure of its main constituents. Taking into consideration the results obtained and the bond type and properties of the constituents
of dentin, it is suggested that the ablation of collagen occurs by a photochemical mechanism while the ablation of apatite is photothermal.
Molecular Dynamics Modelling of the Structure of Bioactive (CaO)0.3 (SiO2)0.7 Sol-Gel
Authors: Mead Robert N. , Mountjoy Gavin
Published: March 2009

Enhanced bioactivity has been observed for amorphous CaO-SiO2 sol-gels with 30mol% CaO, and several structural techniques have recently been used to investigate the structural basis for this bioactivity. The current work presents the first detailed atomic model of (CaO)0.3(SiO2)0.7 solgel after heat treatment at 600°C, produced using molecular dynamics. The model contains 1056
atoms in cubic box with length 24.1Å, and specifically incorporates hydroxyl groups which are characteristic of the sol-gel. The model is in good agreement with experimental X-ray and neutron diffraction results. Inspection of the model shows a network of SiO4 tetrahedra with an average connectivity of approximately 3. Ca have coordination of NCaO=5.3, in agreement with experimental results. On average, each Ca is surrounded by 4 other Ca, and visual inspection shows
several large clusters of Ca. These clusters should influence the dissolution of Ca, and hence the bioactivity of (CaO)0.3(SiO2)0.7 sol-gel.
Organically Modified Silica-Based Xerogels Derived from 3-Aminopropyltrimethoxysilane and 3-Isocyanatepropyltriethoxysilane through Carboxylic Acid Solvolysis
Authors: Fu Lianshe , Ferreira Rute A. Sá , Nobre Sonia S. , Carlos Luís D. , Rocha João
Published: March 2009

Organically-modified silica xerogels from 3-aminopropyltrimethoxysilane (APTES) and 3-isocyanatepropyltriethoxysilane (ICPTES) have been synthesized through carboxylic acid (formic acid, acetic acid and valeric acid) solvolysis. The resulting hybrid materials have been characterized by powder X-ray diffraction, mid-infrared spectroscopy, 29Si and 13C nuclear magnetic resonance, and photoluminescence spectroscopy. The results show that urea cross-links have been formed in
these hybrids. The luminescence features depend on the selected carboxylic acids. For example, comparatively to the hybrids derived from formic and acetic acid solvolysis, valeric acid shows a red-shift of the emission features.
Effect of the Matrix on the 1.5μm Photoluminescence of Er-Doped Silicon Quantum Dots
Authors: Cerqueira M.Fátima , Stepikhova Margarita , Losurdo Maria , Monteiro Teresa , Soares Manuel J. , Peres Marco , Neves Armando , Alves Eduardo
Published: March 2009

Erbium doped nanocrystalline silicon thin films were produced by reactive magnetron r.f. sputtering. Their structural and chemical properties were studied by micro-Raman, spectroscopic ellipsometry and Rutherford backscattering spectroscopy. Films with different crystalline fraction and crystallite size were deposited by changing the deposition parameters. The impact of the composition and structure of Erbium ions environment on the 1.5 µm photoluminescence is discussed.
Growth, Crystal Structure and Stability of Ag-Ni/Cu Films
Authors: Bdikin Igor K. , Strukova Galina K. , Strukov G.V. , Kedrov V.V. , Matveev D.V. , Zverkov S.A. , Kholkin Andréi L.
Published: March 2009

AgxNi1-x (x=0.0-1.0) films were grown on Cu substrates by electrodeposition method. The films were found to be a nanocrystalline mixture of pure silver and nickel. The grain sizes were determined by X-ray diffraction and electron microscopy techniques. The minimal value was 3.3 m for the alloy with 70 wt% concentration of Ni. The stability of the grown films upon heating in ir and in vacuum was examined. An increase in the grain size was found to begin at 150°C.
Laser Sintering of BaTiO3 Ceramics Obtained from Nanometric Powders
Authors: Silva Ronaldo Santos da , Hernandes Antonio Carlos
Published: March 2009

We have studied the synthesis and sintering of BaTiO3 (BTO) nanometric powders
produced by Pechini technique. A laser sintering procedure was applied to the BTO and its major
advantage was the quickness of the processing. We have used the radiation of a CO2 laser (CW –
100 W) as the heating source. A linear rate of irradiation was applied to avoid macroscopic defects.
The calcined powder at 800°C presented a single crystalline phase confirmed by the XRD and a
crystallite size of 20 nm. BTO ceramics sintered at Pmax = 7.0 W/mm2 for 10 min of irradiation
showed a high relative density (98 ± 1) % with an average grain size of 400 nm for a total time of
sintering of 40 minutes.
Electrical Resistance Sintering of M.A. Al-5AlN Powders
Authors: Martos Juan Manuel Montes , Cintas Físico Jesus , Cuevas Francicso Gomez , Rodríguez José A.
Published: March 2009

In this work, mechanically alloyed Al-5AlN powders have been sintered by the Electrical
Resistance Sintering (E.R.S.) technique. A die of alumina-base refractory concrete has been employed.
Several electric intensity currents and passage times through the compact have been tested
during the consolidation process. Compacts have been mechanically characterized by their hardness
distribution and by an indirect tensile test. The obtained results are compared with the corresponding
values of compacts prepared with the same powders by the conventional route of cold pressing
and furnace sintering. Finally, for all the electrically consolidated compacts, the final porosity, as
well as the average hardness and the strength in the indirect tensile test are empirically related to the
electric energy supplied during the process. This energy is a function of the electric intensity current
and passage time. The aforementioned empirical relationships are useful to select the best process
conditions.