bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape Memory Effect and Superelasticity of an Equiatomic Ti-Ni Alloy with Surface Sulfide Layers
Authors: Nam Tae Hyun , Hur Shin Goo , Lee Jae Hwa , Cho Gyu Bong
Published: March 2009

Shape memory characteristics and superelasticity of an equiatomic Ti-Ni alloy with
surface sulfide layers were investigated by means of thermal cycling tests under constant load, tensile tests, and scanning electron microscopy. Martensitic transformation start temperature (Ms) increased by sulfidation, which is ascribed to a compressive stress imposed by surface sulfide layers. Surface sulfide layers were found to make transformation elongation be small when their thickness
was less than 5 ㎛. This is ascribed to the fact that the surface sulfide layers were not detached from substrates and constrained martensitic transformation. When thickness of the surface sulfide layers was 35 ㎛, transformation elongation was not affected by them because they were detached during transformation. Superelastic recovery decreased by the sulfide layers when their thickness was about 5 ㎛, while it did not change when the thickness was about 35 ㎛.
Electrochemical and Structural Properties of Si/Ni/Cu Electrode Films Fabricated with Different Methods
Authors: Cho Gyu Bong , Lee Bong Ki , Sin Won Chul , Nam Tae Hyun
Published: March 2009

Si film electrodes for Li micro-film batteries were fabricated on a Cu substrate and a Ni/Cu film. In the structural properties, Si film had an amorphous structure, while the crystallinity of Ni buffer film was improved after annealing. FE-SEM observation demonstrated differences in surface morphologies of Si films fabricated with different methods. In the electrochemical properties, the Ni-inserted film showed the largest initial charge and discharge capacity, and the cell with annealed
Si/Ni/Cu film showed good cycleability. It is believed that the insertion of Ni film as a buffer film improved the charge and discharge capacity owing to the enhancement of adhesion between Si film and Cu substrate.
The Cavitation Behavior of Fe-Cr-C-Si-Ni Alloys
Authors: Kim Ji Hui , Na Kwang Su , Kim Seon Jin
Published: March 2009

The cavitation erosion behavior of Fe-Cr-C-Si-xNi (x = 1, 2 and 3 wt.%) alloys were investigated for 50 hours using a 20 kHz vibratory cavitation erosion test equipment. 1 wt.% Ni added Fe-based hardfacing alloy showed excellent cavitation erosion resistance, comparable to the stellite 6. Above 1 wt.% Ni, however, the erosion resistance deteriorated quickly. It is conjectured that Ni addition above 1 wt.%, which has been shown to increase the stacking fault energy (SFE),
resulted in reduction of the work hardening rate during the erosion test. Therefore, the enhanced cavitation erosion resistance of the 1 wt.% Ni alloy over the 2 and 3 wt.% Ni alloys could be explained in terms of the SFE, Ms temperature and work hardening.
Fabrication and Magnetic Properties of Mullite Based Nanocomposites with Embedded FeCr Alloy Nanoparticles
Authors: Wang Hao , Wang Wei Min , Fu Zheng Yi , Sekino Tohru , Niihara Koichi
Published: March 2009

Mullite-based nanocomposites with embedded FeCr alloy nanoparticles were synthesized by reduction of sol-gel prepared Al5.4(Fe0.8Cr0.2)0.6Si2O13 solid solution in hydrogen. The feature of the formation of FeCr alloy is characterized by XRD analysis. Structural characterization revealed that the intragranular FeCr alloy nanoparticles along with inter-granular iron grains were obtained
in as reduced sample. After acid washing, the intergranular metal grains were eliminated. The static magnetic properties of nanocomposite powders were studied using Magnetic Property Measurement System. It is found that part of the intra-granular metal nanoparticles have superparamagnetic behavior at room temperature.
Fabrication of Nickel-Silver Rods and Plate through a Small Cross Section Continuous Casting Process
Authors: Cho Hoon , Choi Han Shin , Jo Hyung Ho
Published: March 2009

The environmentally friendly manufacturing process, continuous casting process with small cross sections, is the near net-shaped manufacturing technology used to fabricate copper alloy wires and plates with the required final tolerance and sound quality. Furthermore, the process consumes less energy and discharges less environmental loads because the process can eliminate the
need for hot extrusion, hot rolling and heat treatment for production copper alloy wires and plate. In the present study, the effects of a continuous casting speed on the mechanical properties and the microstructure of the nickel-silver (Cu-Ni-Zn) alloy were studied and energy requirements, atmospheric CO2 emission and yield for the production of the Cu-Ni-Zn alloy was investigated quantitatively with respect to continuous casting with small cross sections and conventional material
processing including casting, extrusion and heat treatment. The yield for production of Cu-Ni-Zn alloy can be improved above 30% with the application of continuous casting with small cross sections when the productivity is similar. Twice the amount of energy required and CO2 were consumed and emitted in the conventional manufacturing process when the yield of the processes was considered.
Combinational Effects of Ni Precursors on Ni/YSZ Cermet Anode
Authors: Han Kyoung Ran , Jeong Youn Ji , Kim Chang Sam , Lee Hai Won
Published: March 2009

NiO/YSZ composite powder with 70 wt% of NiO was prepared by surface modification of ~30 nm YSZ with Ni precursors. As Ni precursors, acidic nickel nitrate and basic nickel carbonate were employed. By varying the ratio of Ni precursors, substantially different particle sizes were obtained. Their Ni/YSZ cermets also showed substantially different microstructures and porosities.
Effects of combination of Ni precursors on Ni/YSZ cermets were studied by using XRD, zetapotential, and SEM.
Development of 2-Cavity Die Casting Process for AM50 Mg Steering Column Lock Housing Module
Authors: Kim Shae K.
Published: March 2009

It is obvious that automotive industry worldwide is predicting significant growth in the use of magnesium alloys for weight reduction to decrease fuel consumption and emission. About a half decade ago, the price of magnesium alloys was more than twice that of aluminum alloys on a weight basis. Currently, magnesium alloys cost about one and a half times that of aluminum alloys on a weight basis, and thus the price of magnesium alloys is the same as or lower than that of aluminum
alloys on a per volume basis. However, in considering the performance of magnesium components (not their specific mechanical properties) and recycling aspect of magnesium alloys, it is required to realize niche applications of magnesium alloys, which meet the cost requirement on performance basis and/or offer more than weight reduction. There are many other factors that make magnesium a
good choice: component consolidation, improved safety for driver and passengers, and improved noise vibration and harshness (NVH), to name a few. As one of these efforts to adopt magnesium alloys in automotive component, this paper describes the research strategy of cold chamber type 2-cavity die casting of AM50 magnesium alloy for developing the steering column lock housing
module with emphasis on cost driving factors and necessities for cost reduction, explaining why AM50 magnesium alloy is chosen with design and die casting process optimization.
Synthesis Nanosized MgAl2O4 Spinel Powder with Excellent Sinterability
Authors: Lee Peng Yuan , Suematsu Hisayuki , Yatsui K. , Niihara Koichi
Published: March 2009

Nanosized MgAl2O4 powder was prepared following a polymerized complex oxide
method. Size of the synthesized powders was 7 to 45 nm depending on the calcination temperature. Powder synthesized at lower temperature showed excellence sinterability. The relative density of the sintering body using the powder synthesized at 700°C reached up to 99.8 % at 1550°C for 3 h in air without any sintering additive.
Photocatalytic Oxidation and Decomposition of Acetic Acid over TiO2, TS-1 and Ti-MCM-41 Catalysts
Authors: Park Ji Hwan , Kim Sung Gab , Park Seong Soo , Hong Seong Soo , Lee Gun Dae
Published: March 2009

Transient reaction of adsorbed monolayer of acetic acid was used to compare the
photocatalytic properties of TiO2 (Degussa P-25), titanium silicalite (TS-1) and Ti-MCM-41. TS-1 and Ti-MCM-41 catalysts with Si/Ti ratio of 50 were prepared by in-situ crystallization. The catalysts were characterized using XRD and UV-DRS. During photocatalytic oxidation (PCO), CO2 and HCHO were formed on P-25 TiO2, whereas CO2 and CH4 formed on TS-1 and Ti-MCM-41.
Acetic acid decomposed photocatalytically on P-25 TiO2 to form CO2, CH4 and C2H6. On the contrary, CO2 and CH4 were formed on TS-1 and Ti-MCM-41 during photocatalytic decomposition (PCD). The rates of product formation during PCD were lower than PCO. The TS-1 and Ti- MCM-41 catalysts were less active per gram of catalyst. However, the TS-1 and Ti-MCM-41 catalysts had much higher adsorption capacities for organics. Therefore, it seems that the TS-1
and Ti-MCM-41 catalysts have some advantages in applications to PCO of organic comtaminants under conditions where the organic concentrations vary widely.
High Temperature Deformation Behavior of Pre-Sintered Al-10Si-5Fe Based Alloy
Authors: Lee Dong  Suk , Jung Taek Kyun , Shim Gyu-Sam , Kim Mok Soon , Kim Won Yong , Yamagata Hiroshi
Published: March 2009

The mechanical properties of pre-sintered Al-10Si-5Fe-1Cu-0.5Mg-1Zr (wt%) alloy were investigated in the temperature range from 673K to 813K and at initial strain rates from 10-4 to 100 s-1. In the high temperature range of 793K and 813K, the strain rate sensitivity index was close to that for superplasticity (0.3). Stress exponent was estimated to be 2 and 5 in the temperature range
from 793K to 813K and from 673K to 773K, respectively. The activation energies for the plastic flow were calculated to 77kJ/mol for the n=2 region and 127kJ/mol for the n=5 region. These values were close to that for grain boundary diffusion and self-diffusion in pure aluminum, respectively. We found that a dynamic recrystallization (DRX) and grain boundary sliding (GBS) occur depending on the test temperature and stain rate. A filament-like phase containing Cu and Mg
was observed in the cracked surface of the specimen deformed at 793K and 813K.
Microstructures and Tensile Properties of Fe-40Al Intermetallic with High Boron Content
Authors: Lee Jin Hwan , Byeon Jai Won , Kwun S.I. , Hong S.J. , Huh J.G. , Hyun C.Y.
Published: March 2009

The effects of B addition up to 0.4 wt% (i.e., 1.61 at%) to Fe-40Al alloy on
microstructures and tensile properties were investigated. The vacancy-annealed specimens following casting and extrusion were examined by optical and scanning electron microscopy and thermal neutron-induced microradiography. The addition of a large amount of B resulted in grain refinement and changed the fracture mode from intergranular to transgranular to increase the tensile elongation. Especially, the alloy containing 0.3wt% B exhibited the elongation of 16.4% under the strain rate of 1x100s-1 at room temperature. The increase in elongation with increasing strain rate
was discussed in terms of suppression of hydrogen embrittlement.
Fluidity of A356 Alloy during In-Ladle DTC Rheocasting
Authors: Lee Jin Kyu , Jo Hyung Ho , Yoon Young Ok , Ha Seong-Ho , Kim Shae K.
Published: March 2009

There are two primary semisolid processing (S2P) routes, thixocasting and rheocasting. Especially, the rheocasting process has become a new focus in the field of semisolid process because of its many advantages such as increased shot size flexibility, no special SSM billet, inhouse recycling of scrap and smaller investment, compared with the thixoforming process. In-Ladle
direct thermal control (DTC) rheocasting was developed, based on the fact that there is slurry and mush transition in molten metal, which is controlled by solid shape and relative interfacial energy. Fluidity is investigated by applying pressure casting for optimizing conditions of in-ladle DTC rheocasting of A356 Al alloy based on research results of simulation and actual microstructure control.
The Transfection Efficacy of Chitosan-DNA Nanoparticles on MGC803, SMMC-7721, MG63 Cells
Authors: Chen Song , Zhang Bin , Ren Lei , Sun Li-Ping , Zhang Qi Qing
Published: March 2009

Chitosan-DNA nanoparticles were synthesized from the complexation of chitosan
solution and the plasmid pCD-GFP encoding green fluorescent protein through a coacervation process. The nanoparticles formed were of diameter inferior to 100 nm. The transfection efficacy of chitosan-DNA nanoparticles in MGC803 cells was higher than in SMMC-7721 cells, whereas the plasmid GFP was not expressed in MG63 cells.
Characteristic Evaluation of Extrusion Parameters on Direct Extrusion Process of 3003 Al Alloy Used for Automotive Condenser Tubing
Authors: Jo Hyung Ho , Hwang Duck Young , Cho Hoon
Published: March 2009

Environmental regulations in the refrigeration technology make the harmful
refrigerants such as CFCs (chlorofluorocarbons) and HCFCs (hydro-chlorofluorocarbons) replaced by eco-refrigerants such as CO2 , and the substitution of CO2 increases the pressure of multi-void condenser tube. As a result, the stiffness of the conventional 1000 series Al alloys can be open to
question. The present study is mainly aimed at developing a direct extrusion process and neocondenser tube material for the application of eco-friendly refrigerants with higher working pressure than the conventional CFC and HCFCs refrigerants. The mechanical properties and burst strength for condenser tube were greatly affected by the large grains formed by brazing condition. As a result of the burst testing, 3003 Al alloy proved to be more suitable than 1100 Al alloy for the
application of condenser tube to eco-friendly refrigerant usage because 3003 Al alloy can be durable in the heat exchanger required high pressure of working. Furthermore, optimum dies design has to be introduced for control metal flow and metal welding during direct extrusion process.
Vacuum Diffusion Brazing of Al5052 Alloys Using Ag-28Cu Insert Metal
Authors: Lee Young Sup , Seo Kyoung Won , Lee C.H. , Lim Cheol Ho , Lee C.H.
Published: March 2009

In this study, we examined brazeability of Al5052 alloys using a Ag-28Cu insert metal in vacuum condition. A high frequency induction-heating vacuum hot press was used for the brazing. Under a static pressure of 0.5 MPa and a vacuum of 5×10-5 Torr, the temperature of hot press was raised up to brazing temperature (480-590°C) at a speed of 10°C/min and held at the brazing
temperature for various times. Interface behaviors of the brazed joints were observed after brazing at 480-590°C by optical microscopy and Electron Probe Micro Analyzer (EPMA). Also, bonding strength of the brazed joints was examined. During vacuum brazing of Al5052 alloys with Ag-28Cu
insert metal, eutectic melts were formed by eutectic reaction between Al5052 and Ag-28Cu insert metal at about 490°C. It was found that reaction layers of two phases are formed at the interface between Al5052 and Ag-28Cu insert. EPMA analysis revealed that two phases in the reaction layers consist of Ag-rich phase and Cu-rich phase. The bonding strength of the joints increased with brazing
temperature and time. The highest bonding strength was 141 MPa at 580°C, 10min.
Recrystallization Behaviors and High Temperature Tensile Properties of Mg-Al-Sn-(Zn) Wrought Alloys
Authors: Kim Jeong Min , Lee Jae Min , Jun Joong Hwan , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Al or Zn content of AZ31 alloy was reduced and small amounts of Sn were added to
improve the formability of alloys. And the recystallization behaviors and mechanical properties of Sn added alloys were investigated. In all the investigated alloys, of which Al content was less than 3%, virtually no Mg17Al12 phase was found. Nor any Sn-containing phase was observed in either AZ21 or AM30 base alloys up to 0.75%Sn. The elongation of alloys at both room temperature and 300oC was significantly improved by the Sn additions possibly owing to increased uniformity of
grain size (size difference between fine and coarse grains). Hindered recrystallization and reduced growth rate of recrystallized grains by the Sn additions are postulated to be the main reason for the enhanced grain size uniformity.
Dispersion Stability of TiO2 Powder Synthesized by Homogeneous Precipitation Process at Low Temperatures
Authors: Woo S.H. , Kim Wheung Whoe , Rhee Chang Kyu
Published: March 2009

Crystalline TiO2 particles with a diameter of 300nm were obtained from aqueous
TiOCl2 solution with 0.67M Ti4+ concentration, diluted by TiCl4 solution using the homogeneous spontaneous precipitation process. Dispersion stability of rutile TiO2 powder with acicular typed primary particles has been investigated in both aqueous and organic media. In this paper, we focus on the TiO2 suspension stability in aqueous and organic media using a recently developed optical analyzer(Turbiscan) and Zeta potential analyzer. The surface potentials of TiO2 particles were greatly modified by dispersion medium and valance of the ionic species, which governs the colloidal behavior of TiO2 particles virtually.
Sub-100nm Hybrid Stamp Fabrication by Hot Embossing
Authors: Hong Sung Hoon , Yang Ki Yeon , Lee Heon
Published: March 2009

The fabrication of nano-structured materials using nanoimprint lithography has become more prevalent in recent years, due to its cost effectiveness and readiness. However, One of the biggest drawback of this technique is the fabrication of the imprinting stamp, which is expensive and difficult to fabricate. This paper describes a method of replication original Si or quartz made imprinting template into a polymer stamp which has many advantages, such as the simplicity and low cost of the fabrication process and the flexibility of the resulting stamp. Using the hot
embossing method, PVC based imprint stamp with sub 100nm patterns can be fabricated. Due to its high UV transmittance, reasonable mechanical hardness and low surface energy, PVC based nanosized template can be used as a stamp for UV-NIL and sub 100nm patterns were successfully transferred by the UV-NIL process with PVC based imprint stamp.
Growth of CNTs on 304 Stainless Steel Using Sparked Iron as a Catalyst
Authors: Thongtem Somchai , Singjai Pisith , Thongtem Titipun , Daothong Suphaporn
Published: March 2009

Carbon nanotubes (CNTs) were grown on 304 stainless steel using iron as a catalyst. By using the applied voltages of 4-6 kV, iron wire with 0.5 mm in diameter was sparked for 1, 2, 10 and 100 times to form catalytic dots on the steel substrate. CNTs were subsequently grown in a gas mixture of 10 ml/s Ar and 0.1 ml/s C2H2 at a temperature range 700 - 900 K for 300 s (5 min). The dots and CNTs were characterised using AFM, SEM and TEM to determine their characteristics.
Abnormal Grain Growth Mechanism in Alumina
Authors: Bang Hee Gon , Song Jun Ho , Park Sang Yeup
Published: March 2009

During the sintering process, the onset of abnormal grain growth is depend on
various factors. The abnormal grain growth behavior, however, was focused only the growth stage compared to nucleation stage. Because most of abnormal grain growth occurred to a rapid mode, the observation of abnormal grain growth was impossible. In this study, we intend to in-situ observe the nucleation stage of abnormal grain using porous alumina. As a result, the liquid phase due to unintended impurities plays a main role for the formation of abnormal nuclei by the rearrangement of small grains due to the capillary force.
Titanium Oxide-Based Photocatalysts: -From Fundamentals to Practical Applications-
Authors: Tsujimaru Koichiro , Anpo Masakazu
Published: March 2009

Advanced ion-beam techniques such as metal ion-implantation and RF magnetron
sputtering deposition were successfully applied in the development of titanium oxide photocatalysts capable of absorbing and working under both UV and visible light irradiation. This advanced physical method was found to be one of the most promising approaches to preparation of highly functional second-generation titanium oxide-based photocatalytic materials, TiO2 nano-powders, highly dispersed titanium oxide species within zeolite frameworks, and TiO2 thin film systems with efficient solar beam utilization of up to 20-30 %.
Effect of Thermo-Mechanical Variables on the Dynamic Ferrite Transformation Induced by Hot Deformation in 0.22C-Mn Steel
Authors: An Jae-Young , Kwon Young Jae , Kim S.I. , Lee Duk Lak , Lee Chong Mu , Hwang Sun Keun , Yoo Yeon Chul
Published: March 2009

Hot torsion of a C (0.22 wt%)-Mn steel was used to investigate the influence of thermomechanical arameters on the strain induced dynamic transformation (SIDT) of ferrite. The pecimens were strained as a function of strain rate (0.05/sec - 5/sec) and strain (- 5.0) at right bove Ar3 temperature. The critical strain to initiate dynamically transformed ferrite nuclei during
deformation increased as increasing the strain rate. On the other hand the completion of SIDT was hifted to larger strain by decreasing strain rate. This is due to the fact that the dynamic ransformation of ferrite was processed in the interior of austenite grain as well as at grain boundary y large stored energy and many nucleation sites for high strain rate. The dynamic transformed
micro-structure of ferrite was developed to higher angle and the grain size could be refined to ~3 ㎛ at strain of 3.0 and 5/sec.
Formation of Ultra Fine Ferrite and Determination of Critical Strain in the Strain Induced Dynamic Transformation for 0.22C-Mn Steel
Authors: Lee Sang Min , Kwon Young Jae , Lee Duk Lak , Cho Sang Hyun , Hwang Sun Keun , Yoo Yeon Chul
Published: March 2009

The low carbon steel of 0.22wt% carbon was tested to estimate the dynamic phase
transformation behavior from austenite to ferrite. The samples were deformed at just above Ar3 temperature by hot torsion at condition of strain rate (0.5/sec) and strain (5.0). The flow curve obtained at just above Ar3 significantly differed from others due to dynamic transformation. Based on the analysis of flow stress curve and observation of micro-structure evolution, the initiation and finish points of strain induced dynamic transformation (SIDT) could be determined. An inflection
point observed at early deformation range (0.2–0.3) from the work-hardening rate and stress plot meant that new ferrite grains were nucleated in austenite matrix and these nuclei could be also confirmed by optical microscope. Subsequently in strain range of 0.7-1.0, the flow stress had the maximum value and new fine ferrite grains were dynamically generated inside untransformed austenite grains as well as prior austenite grains. The dynamic phase transformation induced by deformation made eventually fine ferrite grains under 3 ㎛ and decreased stress level with a fixed
gradient.
Prediction of Flow Curves and Micro-Structural Evolution in Strain Induced Dynamic Transformation of Low Carbon Steel
Authors: An Jae-Young , Kwon Young Jae , Kim S.I. , Lee Duk Lak , Yoo Yeon Chul
Published: March 2009

The relationships between flow stress curve and microstructure evolution in strain
induced dynamic phase transformation (SIDT) of low carbon steel (0.22wt.%) were quantitatively investigated. The deformation was carried out at just above Ar3 temperature (710°C) as a function of strain rate (0.01-5/sec). The softening process of SIDT was well agreed with calculated result derived from Avrami’s and constitutive equation at higher strain rate than 0.5/sec. However, the
calculated results differed from the experimental curve at strain rate of less than 0.2/sec. This is due to fact that the dynamic transformation from austenite to ferrite can not be completed owing to less stored energy during hot deformation.
Textures and Mechanical Properties of Melt-Extruded Al-Cu Alloys
Authors: Lee B.S. , Joo Dae Heon , Ryou M. , Kim Myung Ho
Published: March 2009

The influence of heat treatment on mechanical properties and textures of a meltextruded Al-4.5wt.%Cu alloy bar was studied. And its characteristics are compared with those of a hot-extruded Al-Cu alloy bar. The results show that the mechanical properties of the melt-extruded Al-Cu alloy bar were slightly higher than those of the hot-extruded bar, and the difference in their mechanical properties was narrowed after the T6 treatment. The recrystallization texture was found
in the melt-extruded Al-Cu alloy bar, and the fiber texture of the hot-extruded Al-Cu alloy bar was found different from that of the melt-extruded Al-Cu alloy bar.
Effect of Electromagnetic Stirring on Orientation Distribution Function of Primary Solid Phase of Al-Cu Alloy
Authors: Lee Dock Young , Han Jun Hyun , Kang Suk Won , Mun Jung-Hwa , Kim Ki Bae
Published: March 2009

In this study, the orientation distribution function (ODF), which can be calculated from the pole figure data, was examined and tried in order to characterize the bulky morphology of primary solid phase of semi-solid slurry instead of erroneous 2D observation for the characterization of microstructure. Al-15wt%Cu alloys were electromagnetically stirred during the continuous cooling in the specially designed electromagnetic (EM) stirrer, which generates a rotating magnetic field, and
the samples were prepared by interrupt-quenching semi-solid slurry at a solid-liquid region. Owing to EM stirring the temperature distribution of melt inside a crucible became uniformed compared with the case of unstirred melt and the normal dendritic structure was transformed to one consisting of the spherical and rosette shaped primary solid phase due to the fragmentation of the dendrites. Also by
the effect of EM stirring the <110>//ND texture were still strongly developed, but the advancement of the orientations to lead <110>//ND texture became weaker, and the orientations to lead <100>//ND and <111>//ND texture were more strongly advanced in comparison with the unstirred case. Therefore the advancement of the texture became weak and so the tendency to random orientation was appeared due to the EM stirring. Therefore it was thought that the extent of random orientation could be valued for the characterization of bulky morphology of primary solid phase of semi-solid slurry.
Photocatalytic Properties of Mesoporous TiO2 Films Derived from Evaporation-Induced Self-Assembly Method
Authors: Pan Jia Hong , Chai Seung Yong , Lee Wan In
Published: March 2009

Hexagonal and cubic mesoporous TiO2 films were prepared by using triblock copolymer-templated sol-gel method via evaporation-induced self-assembly (EISA) process. The mesophase of TiO2 film was controlled by spin-speed during the spin-coating process. The hexagonal mesoporous structure
was formed at a high spin-speed around 2000 rpm, whereas the cubic mesostructure was formed at a low spin-speed around 600 rpm. XRD and TEM results indicate that those mesostructures are highly organized with a pore diameter of 7 nm. The prepared cubic and hexagonal mesoporous films were tested as photocatalysts for the decomposition of 2-propanol in gas phase. Both films
presented considerably higher photocatalytic activity than a nonporous TiO2 films prepared by a typical sol-gel process without addition of triblock copolymer. Notably, we found that the cubic mesoporous films showed a relatively higher photocatalytic activity than the hexagonal mesostructured film. We believe this is due to the orientation of pore channels open on the surface of mesoporous films.
Recycling of Waste Coal Fly Ash: Synthesis of Zeolite-Like Minerals from Residue Yielded by Extraction of Aluminum Ions
Authors: Ryu M.S. , Sin H.G. , Park S.H. , Yoon Seog Young , Stevens Ron , Park Hong Chae
Published: March 2009

The conversion of residue, by extraction processing of aluminum ions from coal fly ash to zeolitic materials by hydrothermal treatment in the presence of NaOH solution, was investigated and the resulting material characterized.
Luminescence Porous Ceramics Using Recycling Glass
Authors: Matsushita Junichi , Yasumatsu S. , Hosaka N. , Okawa K. , Fujita T. , Li Jian Bao , Lin Hong , Shim Kwang Bo
Published: March 2009

The fabrication and fluorescence properties of luminescence porous ceramics were
investigated by using recycling glass addition of oxide phosphor to determine the suitability of this material for the application of recycling glass. The aim of this study was to give the fluorescence performance to the porous ceramics using recycling glass with phosphor material. The samples showed a good "Eco" luminescence porous ceramics of about 60 to 70 % porosity using recycling
glass.
Effect of Pair-Mineralizer on the Reaction of Alite and Calcium Langbeinite Formation
Authors: Kwon Woo Teck , Kim Young Phil , Kim Y. , Kim Soo Ryong , Bae Seong Youl
Published: March 2009

This paper investigates the effect of the pair-minerializer (CaSO4,-CaF2) on the reaction of alite, belite and calcium langbeinite formation with different alkali and sulfate contents. A set of clinker samples was prepared by adding laboratory grade reagents of (NH4)2SO4, CaF2 and K2CO3 to the cement raw mixes. The mineralogical composition of clinker was analyzed by X-ray powder diffraction, and the quantity of minerals was evaluated by using TOPAS software. As the
experimental results, the total amount of calcium silicate minerals was rapidly increased with the addition of F and SO3 components simultaneously as pair-mineralizer with K2O more than the value which mineralizer was added separately. Also, in the case of adding K2O only to the raw mixes, the amount of alite is decreased after clinkering. However, if alkali (K2O) and pair-minerializer
(CaSO4,-CaF2) were added simultaneously, the quantity of alite and calcium langbeinite mineral increased because of the formation of stable clinker minerals by the reaction of alkali (K2O) and sulfate.
Low Temperature Synthesis of Porous Cordierite from Fly Ash
Authors: Kim Sung Jin , Bang Hee Gon , Park Sang Yeup
Published: March 2009

Cordierite is known as three different crystalline forms, such as metastable form (µ-
cordierite), high temperature form (α–cordierite; indialite), and low temperature form (β-cordierite). In general, cordierite has a phase transition behavior from metastable form to high temperature form. In this study, we focused to synthesize the porous cordierite at low temperature using reaction method without metastable form. When we used a pure starting powders (Al2O3, MgO, and SiO2),
metastable cordierite and Mg spinel phase was obtained during the heat treatment. However, fly ash based mixture used as a starting powder, we obtained a porous α–cordierite at low synthesis temperature through transition from sapphirine/spinel and mullite/spinel
A Study of Ga2O3 Nanomaterials Synthesized by the Thermal Evaporation of GaN Powders
Authors: Kim Hyoun Woo , Myung Ju Hyun , Shim S.H.
Published: March 2009

We have synthesized gallium oxide (Ga2O3) nanomaterials at two different growth
temperatures on iridium (Ir)-coated substrates by thermal evaporation of GaN powders. The products consist mainly of nanobelts, with some additional nanosheets. The nanobelts were of a single-crystalline monoclinic Ga2O3 structure. The broad emission photoluminescence band of 900°C-products had a different peak position from that of the 970°C-products.
Characteristics of SnO2 One-Dimensional Nanomaterials Synthesized on TiN-Coated Substrates by the Evaporation of Sn Powders
Authors: Kim Hyoun Woo , Shim S.H. , Myung Ju Hyun
Published: March 2009

One-dimensional structures of tin oxide (SnO2) on TiN-coated substrates were obtained by simple heating of Sn powders. X-ray diffraction, high-resolution transmission electron microscopy, and the selected area electron diffraction showed that 1D structures are composed of SnO2 with rutile structure. The photoluminescence of the structures in the visible region suggests possible applications in nanoscaled optoelectronic devices.
Effects of Anodizing Time on Anodizing of Mg-Al Alloy in Alkaline Solution
Authors: Kim Seong Jong , Kim Jeong Il
Published: March 2009

This paper investigated the effects of anodizing time on the formation of anodic oxide
films on a Mg-Al alloy in alkaline solution. The thickness of the anodic oxide film was increased by increasing the time required to generate the active dissolution reaction. When anodizing at various anodizing time, the potential after passivity increased with time, which implies growth in film thickness. When the anodizing time was varied, the quantity of oxygen increased with time in the white areas (the film), i.e., more film was observed in the SEM and EDX analyses.
A Study for Microwave Enhanced Synthesis of NIR Absorbing Materials
Authors: Im Ji Un , Yu Chan Yong , Yoo Jeong Yi , Son Se Mo , Lee Gun Dae , Park Seong Soo
Published: March 2009

Symmetrically and unsymmerically substituted bis-dithiobenzil nickel complexes
containing four substituted and unsubstituted methoxy groups were synthesized from a benzoin compound using phosphorous pentasulfide under the conventional thermal and microwave processing. The efficiency of microwave synthesis over the conventional thermal synthesis was illustrated by the yield of bisdithiobenzil nickel complex dyes. The samples were characterized by the means of elemental analyzer, 1HNMR, IR spectroscopy, Uv-vis spectroscopy and DSC.
Characterization of Ni Nanopowders Produced by Electrical Explosion of Wire Technique
Authors: Kim Hwan Tae , Seo Won Sik , Kwon Dae Hwan , Choi Pyuck Pa , Kim Ji Soon , Kwon Young Soon
Published: March 2009

Nanosize nickel powders were successfully produced by electrical explosion of wire
(EEW). In EEW, the nickel wire was discharged in a chamber filled with nitrogen or argon gas, and the produced powders were subsequently stabilized by air-passivation at room temperature for 2 h. X-ray diffraction only showed the nickel phase of FCC crystal structure, whereas TEM and XPS analyses showed the formation of a very thin oxide layer of NiO on the surface of particles.
Particles were spherical in shape, and the mean particle size calculated by specific surface area was about 100 nm. The particle size decreased with increasing charging voltage and with increasing ambient gas pressure. Argon gas was more effective in producing finer particles than nitrogen gas.
Nano Scale Material Property Measurement of MEMS Material Using Piezo Actuated Material Testing Machine
Authors: Lee Hye Jin , Lee Nak Kyu , Lee Hyoung Wook , Park Hoon Jae , Choi Tae Hoon
Published: March 2009

Many micro technology researches have been concentrated in the field of materials and a process field. But the properties of micro materials should be understood to give still more advanced results. Among the various material properties, mechanical material properties such as tensile strength, elastic modulus, etc., is the basic property. To measure mechanical properties in micro or nano scale, actuating must be very precise. Piezo is a famous actuator, frequently used to measure very precise mechanical properties in micro research field. But piezo has a nonlinearity
called hysteresis. Not precision result is caused because of this hysteresis property in piezo actuator. Therefore feedback control method is used in many researches to prevent this hysteresis of piezo actuator. Feedback control method produces a good result in processing view, but causes a loss in a resolution view. In this paper, hysteresis is compensated by using an open loop control method. To apply the open loop control method to piezo actuated nano scale material testing machine,
hysteresis property is modeled in a mathematical function, and a compensated control input is constructed using inverse function of original data. The reliability of this control method can be confirmed by testing nickel, aluminum, and copper micro thin foil that is used in MEMS material broadly. If these MEMS material properties are used in a MEMS research field, more economical and high performance MEMS materials can be obtained.
Fabrication and Microstructure of ZnO-SiO2 Nanoparticles by a Reverse Micelle and Sol-Gel Processing
Authors: Kim Rak Hee , Kim Jae Won , Park K.S. , Bae Dong Sik
Published: March 2009

ZnO-SiO2 nanoparticles were synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles was controlled by manipulating the relative rates of the hydrolysis and condensation reaction of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average size of synthesized ZnO-SiO2 nanoparticles was in the range of 20-40 nm. The effects of synthesis parameters such as the molar ratio of water to precursor and the molar ratio of water to surfactant are discussed.
Controlled Release of Active Substance from Biodegradable Copolymer Matrix
Authors: So Hyung Suk , Shin Hyun Chul , Kim Beom Suk , Yoo Yeong Seok
Published: March 2009

The purpose of this study is to develop a new system to control effective discharge of active substances such as agricultural chemicals. To synthesize a naturally dissolvable polymer; ε-caprolactone and diglycolide were copolymerized with ethylene glycol as an initiator to produce macrodiol. As macrodiol has hydroxyl groups in both ends, they are modified with methacryloyl chloride for photochemical networking. After standard macromonomer produced by this procedure
was physically mixed with methylene blue, it was networked with ultra-violet rays to be filmed. This film is naturally dissolvable and hydrolytic. As a result of hydrolytic test with a crosslinked structure of 10 % methylene blue, it decreased by 9 % for seven weeks in 37 °C phosphate buffer solution (pH = 7). Thus, we verified that active substance can be discharged from a crosslinked structure for a long time at a constant rate under room temperature.
Tribological Analysis of Al2O3/TiO2/ZrO2 Nanocomposites as an Alternative for THR Materials
Authors: Visbal Santiago , Lee Soo Wohn , Morillo C. , Carrillo Daniel G. , Lira-Olivares Joaquín
Published: March 2009

This work studied the microstructure and tribological behavior of Al2O3/TiO2/ZrO2
nanocomposites to be used in hip joint replacements. To increase the fracture toughness of alumina and enhance the tribological properties, nanometer sized particles of TiO2 and ZrO2 were added. The specimens contained 10 mol% of TiO2, different percentages of ZrO2 (0, 2.5, 5, 7.5, 15 and 20 mol %), and alumina as a remainder. Disks were hot pressed at 1500 °C and 25 MPa, in an Argon atmosphere for 1 hour. Given the fact that the sample containing 7.5 mol% of ZrO2 showed the
lowest wear volume, it was hot pressed again at 1500, 1400, 1300 and 1200 °C to assess the best temperature condition for sintering. For a composition of 7.5 mol% of ZrO2 the lowest coefficient of friction (0.1-0.3) and the lowest wear volume (0.0046 mm3) were achieved. A direct relation between mechanical and tribological properties was not found. However, these nanocomposites
may be considered as a candidate for a new generation of hip joint replacement material.
The Characteristic of the La3Ga5SiO14 Single Crystal Grown by Vertical Bridgman Method in Ar Atmosphere
Authors: Bamba Noriko , Kato Kentaro , Taishi Toshinori , Hayashi Takayuki , Hoshikawa Keigo , Fukami Tatsuo
Published: March 2009

Langasite (La3Ga5SiO14: denoted by LGS) single crystal is one of the lead free
piezoelectric materials with high piezoelectricity that is maintained up to its melting point (1470°C). Although LGS single crystals have usually been grown by Czochralski (CZ) method in oxygen contained atmosphere to prevent evaporation of Ga, they were grown by the vertical Bridgman (VB) method in Ar atmosphere without oxygen, and their properties were evaluated in this work. Transparent and colorless LGS single crystals were successfully obtained without Ga evaporation by the VB method in Ar atmosphere, and their resistivity at room temperature was much higher than that grown by conventional CZ method. Piezoelectric constant d11 of the crystal grown by the VB method was 6 x 10-12 C/N, which was close to that of the crystal grown by CZ method. The colorless transparent LGS single crystal turned to orange and its resistivity decreased
by annealing in air. Since an orange-colored transparent LGS single crystal has been grown by conventional CZ method, this indicates that color change and the resistivity decrease of LGS crystal is caused by extra interstitial oxygen atoms in the crystal.
Surface Modification of Glass Plate to Enhance Thickness of Silica Aerogel
Authors: Heo Deog Do , Jun B.S. , Oh Young Joo
Published: March 2009

Surface modification process was employed to enhance the thickness of film and avoid crack propagation during ambient drying for the smart glazing. To eliminate the hydrocarbon on the surface of glass, UV was irradiated on the glass slide under oxygen atmosphere. The wetting angle was reduced to the optimal condition for dip-coating when UV irradiation with oxygen time was kept for 10minutes. The thickness of the surface modification samples have almost double value compared to the sample of non-surface treatment. The thickness of the film after heat treatment of
the substrate was highly increased.
Synthesis of AlON Refractory Raw Materials from Aluminum Dross Using Thermite Reaction Process
Authors: Joo H. , Yun J. , Hwang K. , Jun B.S.
Published: March 2009

Aluminum dross is presented as a potential material to form AlON using thermite
reaction. The commercial MgAl powder, active carbon, and titania were prepared to make a chemical furnace (self-propagation combustion). The preheating temperature of 300 is enough to intitate ignition of the mixture as fuel and oxidizer. The addition of Y2O3 (1wt. %) is effective to enhance solid solution products between Al2O3 and AlN in the Aluminum dross. The level of contamination like an alkali metal oxide in the Aluminum dross was reduced highly by the heat from chemical furnace.
Biomimic Tubulose Scaffolds with Multilayer Prepared by Electrospinning for Tissue Engineering
Authors: Qi Hong Xu , Kong Deling , Hu Ping , Zhang Jun , Lin Wei Jie , Song Fei
Published: March 2009

Electrospinning represents an attractive approach for polymer processing. In the present study, gelatin and poly (propylene carbonate)(PPC) were electrospun successfully and collected on a rotating mandrel to form tubulose scaffolds. Furthermore, to mimic the real structure of animal blood vessels, the polymers were employed in a single tube as distinct layers by the technique of alternate
electrospinning. Scanning electronic microscopy (SEM) was used to analyze the morphology and diameter of the fibers, and the porosity of the scaffold. The tubes were seeded with rat bone marrow derived mesenchymal stem cells (BMSCs) and cultured for 2 weeks to evaluate their biocompatibility. The growth and distribution of the cells were observed directly under the fluorescent microscope. The interaction between cells and scaffold was analyzed by SEM and H&E
staining. After two weeks culture, the fibers were almost embedded by growing BMSCs. H&E staining and green fluorescent image showed that BMSCs uniformly grew inside the scaffolds. The results showed that electrospun tubes with uniform pores and fibers of smaller diameter were appropriate for BMSCs attachment and proliferation. These primary data indicated that scaffolds fabricated by ectrospinning are structurally biocompatible. The PPC scaffolds may be useful in vascular tissue engineering if they were further modified chemically or with appropriate therapeutic molecules.
Study on Improving Stainless Steel Antibacterial Capability
Authors: Yang Wei Hu , Li Yu Bao , Wu Lan , Yang Ai Ping , Li Ji Dong , Li H.
Published: March 2009

A new method was studied for improving stainless steel antibacterial capability. The
Na2FeO4 coating was prepared on steel surface throughout NaOH treatment, then steel samples were immersed into the solution coantaining Ag+, Zn2+ and TiO2. The antibacterial-ions were fixated firmly on the stainless steel with chemical bond. Scanning electronic microscopy(SEM), X-ray(XRD) and atomic absoption spectroscopy(AAS) were employed to analyze the materials, and the results showed that the antibacterial membrane included silver citrate and silver peroxide. Quinn test was also carried out, in which Staphylococus and E.coli. the results showed that the steel has a bacteriostasis rate of 99.48% to Staphylococus, and 99.09% to E.coli.
Fabrication of Porous Clay Materials with Aligned Pore Structures by Freeze-Drying
Authors: Hwang Hae Jin , Kim Do Yeon , Moon Ji Woong
Published: March 2009

Porous clay materials with columnar type pore channels were fabricated from water-based clay slurry and a specially designed mold by using a freeze casting technique. Ice was stimulated to grow vertical direction, and aligned macro pores were formed to the same direction. The phase separation between the ice and clay particles might be responsible for the formation of the columnar type pores. It appears that it is possible to control the size and morphology of pores by modifying a
freezing mold, refrigerant temperature, and the weight fraction of clay in slurry.
Kinetics of the SiC Formation from Carbon Thin Film and SiO Gas
Authors: Sano Hideaki , Karasuyama Hajime , Zheng Guo Bin , Uchiyama Yasuo
Published: March 2009

A thin film including β-silicon carbide was synthesized by a reaction of silicon monoxide gas and carbon source derived from polyimide film (PIF) at 1400°, 1500°, 1600°, 1700° and 1800°C. Formation mechanism of the SiC film was investigated thermodynamically and kinetically through the relationships among the conversion ratio of SiC, synthesis temperature and time. The formation
processes were simulated based on the calculation of differential equations concerning thermodynamic and kinetic constants of 7 chemical equations. The sample obtained had a film shape similar to that of the carbon source film. The results of the time dependence curves of the conversion ratio of SiC calculated from 7 chemical equations, 14 rate constants, 2 diffusion constants, 10 chemical species and 10 differential equations are in good agreement with the experimental results of
the SiC conversion ratio as a function of synthesis time. The calculation results of solving each constant suggest that the formation processes of SiC are "rate-controlled reaction at the interface" at the initial stage of the reaction, and then they gradually change to "diffusion-controlling reaction in the reacted region". In the long term synthesis, we recognized that the waste SiO with non-stoichiometric oxygen can also be used as a silicon source.
Modification of Natural Zeolite Powder and Its Application to Interior Non-Woven Textile for Indoor Air Quality Control
Authors: Lim Hyung Mi , Jung Ji Sook , Kim Dae Sung , Lee Dong Jin , Lee Seung Ho , Kim Woo Nyon
Published: March 2009

The application of VOC-free materials for building interior is the first step to reduce the contamination level, however, it is practically unavoidable to find a way to eliminate existing pollutants from furniture, adhesives, etc. As a positive way of controlling the air indooors, the air conditioner may be applied with high functional filter, which uses electricity for compulsory air circulation. As an alternative, we modified natural zeolite powder by ion exchange and also by addition of TiO2 photo-catalyst for multifunctional powder to contribute to controlling the indoor air
quality. The modified zeolites were applied on the interior non-woven polypropylene sheet to reduce indoor air pollutants not only by adsorption mechanism but also by decomposition mechanism. We studied deodorization of the multi-functional powders and also their coating on non-woven textiles by a Gastec method.
Electrical and Luminescent Properties of Size Controlled ZnO Nanorods
Authors: Park Jae Young , Oh Chang Won , Kim Ju Jin , Kim Sang Sub
Published: March 2009

Well-aligned ZnO nanorods were synthesized using metalorganic chemical vapor
deposition. Their size was controlled by adjusting the O/Zn precursor ratio. The electrical transport and optical properties of the size-controlled nanorods were investigated. The elelctron concentration and electron mobility in the nanorods are not sensitive to the change of the precursor ratio. In addition, the photoluminescent property is nearly the same regardless of their different sizes. These results
suggest that altering the precursor ratio is a way of fabricating size-controlled ZnO nanorods with quite consistent electrical and optical properties.