bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion Behavior of Chromium Cast Iron and Steel in Hot Concentrated Alkaline
Authors: Tu Xiaohui , Liu Jun Quan , Li Wei , Su Jun Yi
Published: March 2009

Abstract. Hot concentrated alkaline corrosion and wearing corrosion environment exists in alumina metallurgical industry. Iron and steel materials with outstanding alkaline corrosion resistance are strongly demanded for their
fabrication equipments. In this paper, corrosion resistance in static hot concentrated alkaline solution of several kinds of martensite chromium cast iron and steel was studied through polarization curves, potential-time curves, weight loss in
the corrosion, and corrosive morphology analysis. Experimental results indicated that corrosion processes can be divided into three stages: dissolving of passivating films, exposed surface corrosion, and corrosion beneath the corroded product. Protection effect of the passivating films was transitory, and the corrosion rate during the exposed surface corrosion reached the maximum. Corrosion of the testing materials was composed of active dissolving corrosion of the
metal matrix and caustic embrittlement cracking of the matrix, as well as grain boundary corrosion for the cast iron. Dissolving corrosion of the metal matrix was the main cause that induced the weight loss, while severe caustic
embrittlement cracking of the metal matrix was disadvantageous. With an increase of the chromium content in the cast iron or steel, active dissolving corrosion of the metal matrix increased. However, the tendency of caustic embrittlement cracking decreased.
Improvement of the Core Loss of SiFe by Optimizing the Operation Conditions of the Laser Scribing
Authors: Ahn Seung Joon , Park Chul Geun , Lim J.S. , Baik K.H. , Kim Dae Wook , Kim Ho Seob , Ahn Seung Joon
Published: March 2009

The magnetic domain refinement was carried out by laser pulse scribing in order to reduce the core loss of SiFe. The laser pulses were generated by a Q-switched Nd:YAG laser, and the optical frequencies of the laser pulses were altered by using the SHG and the THG. The core losses were measured and analyzed to find optimal parameters of the laser treatment. The laser beam was focused
with a spot size of 0.2 mm, and pulse energy of 10~30 mJ and the lines were scribed with a period of ~5 mm. The core loss was improved up to 19 % with the THG of Q-switched Nd:YAG laser in 3% SiFe.
Characteristics of Thin Film of Nano-Hybrid Synthesized from Acrylic Resin and Colloidal Silca-Silane Sol
Authors: Kang Dong Pil , Park Hoy Yul , Kang Young Taec , Na Moon Kyong , Lee Hee Woong
Published: March 2009

Organic-inorganic hybrid blends were prepared in variation with the ratio of sol solution to urethaneacrylic resin. Such sol solutions were synthesized from colloidal silica (CS)/ methyltrimethoxysilane(MTMS)/vinyltrimethoxysilane(VTMS) by sol-gel reaction through two step reactions. Thin films of organic-inorganic hybrid blends were prepared using spin coater on the glass and aluminum sheets. In order to understand surface properties of thin films, contact angle and
roughness were measured. Surface contact angle and roughness of thin films increased as the amount of sol solution increased. Thermal dissociation temperature of thin films was observed using TGA. Thin films were stable until 270 oC. Thermal dissociation temperature of thin films improved with increasing sol solution. In order to observe insulation property of thin films, electrical resistance measurements were performed. Surface and volume resistance of thin films increased as the amount of sol solution increased.
Effects of Processing Parameters on the Mechanical Properties of SiCp/AC8A Composites by Pressureless Metal Infiltration Process
Authors: Kim Jae Dong , Kim Hyung Jin , Koh Sung Wi
Published: March 2009

The effects of additional Mg content and the size of the reinforcement phase on the
mechanical properties of 20 vol.% SiCp/AC8A composites fabricated by pressureless metal infiltration process were investigated. The hardness of SiCp/AC8A composites increased gradually with an increase in the additive Mg content, while the bending strength of SiCp/AC8A composites increased with an increase in additive Mg content up to 5%. However, this decreased when the level
of additive Mg content was greater than 5%. The increase in hardness by additive Mg content is due to the formation of hard reaction products such as Mg2Si and AlN during the process, whereas the decrease in bending strength when Mg content was above 5% is due to the formation of coarse precipitates by excessive Mg reaction and an increase in the porosity level. The hardness and
strength of the composites increased with a decrease in the size of SiC particles. It was found that the composites with smaller particles enhanced the interfacial bonding more than those with bigger particles from fractography of the composites.
Wear Characteristics of Particulate Reinforced Metal Matrix Composites Fabricated by a Pressureless Metal Infiltration Process
Authors: Kim Jae Dong , Kim Hyung Jin , Koh Sung Wi
Published: March 2009

The effect of size and volume fraction of ceramic particles with sliding speed on the
wear properties were investigated for metal matrix composites fabricated by a pressureless metal infiltration process. The particulate metal matrix composites exhibited about 5.5 - 6 times greater wear resistance compared with AC8A alloys at high sliding speed, and by increasing the particle size and decreasing the volume fraction the wear resistance improved. The wear resistance of the
metal matrix composites and AC8A alloy represented different aspects: the wear loss of the AC8A alloy increased with sliding speed linearly, whereas, the metal matrix composites displayed more wear loss than the AC8A alloy in the slow-speed region. However, a transition point of wear loss was found in the middle-speed region, which shows the minimum wear loss. Furthermore, wear loss
in the high-speed region exhibited almost the same value as the slow-speed region. In terms of wear mechanism, the metal matrix composites showed abrasive wear at a slow to high sliding speed generally. However, the AC8A alloy showed abrasive wear at low sliding speed and adhesive and melt wear at a high sliding speed.
Development of Cube-Textured Ni and Ni-W Alloy Tapes by Focused Infrared Heating
Authors: Chung Jun Ki , Bae Sung Yeal , Lee Sung Gap , Park Chan , Yoo Sang Im , Kim Cheol Jin
Published: March 2009

We fabricated bi-axially textured pure Ni and Ni–5at.%W (Ni-5W) alloy tapes for the application of rechargeable battery cathode and coated superconductor, where the controlled microstructure of the substrate plays a critical role. The sintered Ni or Ni-W rods were cold-rolled into the thin tapes of 80 ~ 100 µm thickness, and the tapes were heat-treated for texture development with a line focused infrared heater. The temperature was maintained at 800 ~ 1050 °C, using a 1kW double ended linear halogen lamp in 96%Ar-4%H2 atmosphere. The (2 0 0) texture of
Ni tape was successfully formed through optimization of the recrystallization infrared heating condition for the cold rolled Ni tapes. The full width half maximum of the Ni tapes was less than 10o, and the grain size was 20 ~ 40 µm. Focused IR-heating resulted in a better texture development and smaller grain size compared to the conventional resistive heating because of the steep temperature gradient.
Reciprocating Sliding Wear Behavior of Inconel 600 Mated with SUS 304 Stainless Steel at Elevated Temperatures
Authors: Lee Kwon Yeong , Hwang Chang Seon , Kim Seon Jin , Kim Gyung Guk , Kim Ji Hui , Yoon Chong Seung
Published: March 2009

The sliding wear behavior of a steam generator in a nuclear power plant (Inconel 600) was investigated at 225, 250 and 300°C. Effects of wear parameters such as sliding distance and contact stress were examined with SUS 304 (austenitic). In the prediction of the wear volume by Archard wear equation, the standard error range was calculated to be ±0.53×10-9 m3 and the reliability to be 71.9 % for the combination of Inconel 600 and SUS 304. The error range was considered to be relatively broad because the wear coefficient in Archard equation was assumed to
be constant. However, the wear volume turned out to increase parabolically with the sliding distance owing to the combination of strain hardening of the wear surface and the oxidative wear. Based on the experimental results, the wear coefficient was modified as a function of the rotating sliding distance. The calculation with the modified wear equation showed that, although the error range was not significantly narrowed, the reliability increased from 71.9 to 78.1 %.
Net-Shape Forming of TiAl Automotive Parts for Fuel Efficiency
Authors: Sung Si Young , Kim Young Jig
Published: March 2009

Alpha-case formations between investment molds and TiAl alloys were investigated for economic TiAl alloys net-shape forming. The α-case reactions between mold and TiAl alloys were characterized by using optical microscopy and a hardness tester. In the case of TiAl alloys, there were no α-case formation reactions. The α-case was formed not only by interstitial oxygen elements but also by substitutional metallic elements dissolved from mold materials. There were neither interstitial
nor substitutional α-case formations since TiAl alloys have both negligible solubility of oxygen and low activity in molten states. The results of the investment casting of TiAl alloys confirmed that the casting route in our study can be an effective approach for the economic net-shape forming of TiAl alloys automotive parts.
Mechanical Behavior of TiB2 Nanoparticles Reinforced Cu Matrix Composites Synthesized by In-Situ Processing
Authors: Kwon Dae Hwan , Huynh Khoa Xuan , Nguyen Thuy Dang , Choi Pyuck Pa , Chang Myung-Gyu , Yum Young Jin , Kim Ji Soon , Kwon Young Soon
Published: March 2009

Cu-TiB2 nanocomposite powders were in situ synthesized by combining high-energy ball milling of Cu-Ti-B elemental powder mixtures as precursors and subsequent self-propagating high temperature synthesis (SHS). Cu-40wt.% TiB2 was produced after SHS reaction and then diluted by copper to obtain desired homogeneous composites with 2.5, 5 and 10wt.%TiB2. Spark plasma
sintering (SPS) was used to inhibit grain growth and thereby obtain fully Cu-TiB2 sintered bodies with nanocomposite structure. After SHS reaction, only Cu and TiB2 phases were detected in the SHS-product. Spheroidal TiB2
particles smaller than 250nm were formed in the copper matrix after SHS-reaction. Mechanical and electrical properties were investigated after SPS at 650°C for 30min under 50MPa. The electrical conductivity decreased from 75 to 54% IACS with increasing of TiB2 contents from 2.5 to 10wt.%. However, hardness increased from 56 to 97HRB. In addition, the tensile strength increased with increasing the TiB2 content.
Thermal and Phase Evolutions of As-Milled Powders Fabricated by Mechanical Alloying in the TiH2-C System
Authors: Bae Sung Yeal , Ahn In Sup , Sung Tek Kyung , Park Dong Kyu
Published: March 2009

Nano-TiC powders were fabricated for mechanical alloying (MA) by shaker mill using the TiH2 powders mixed carbon powder. For mechanical alloying, titanium hydride was easily breaking alloy and easily decomposed titanium particles and hydrogen gas. The decomposition titanium powders in TiH2 powders were very fine particle size and unstable phase. And it easily reacted to carbon ;(TiH2 + C TiC + H2). The effects of mechanical allyoing, morphology, phase and particle size were evaluated with X-ray diffraction (XRD), field emission scanning electron
microscopy (FESEM), TG/DTA and particle size analyzer. As-milled powders for 10 hours were successfully synthesized powders of TiC phase, mean particle 300nm size. And as-milled powder for 1 hour was included unstable phase, was annealed for 1 hour at 400°C-1300°C in 1x10-3torr vacuum atmosphere. Unstable phase was changed to recrystallize phase by heat treatment. After heat treatment for 1hour using as-milled powders, it was included many types of titanium oxide at
temperature below 1000°C, was formed single phase of TiC at temperature over 1000°C.
Thermal Conductivity of Hot-Pressed BN Ceramics
Authors: Lee Sang Kee , Nakamura Kazuo , Kume Shoichi , Watari Koji
Published: March 2009

Hexagonal boron nitride ceramics with sintering additives were synthesized by uniaxial hot-pressing. Hot pressing was carried out at 1800oC for 2 h under the uniaxial pressure of 30 MPa under a nitrogen atmosphere. Thermal conductivity perpendicular and parallel to the direction of the hot-pressing axis was measured by the laser-flush method.
Analysis of Deformation Characteristics in Wave-Typed Heat Sink Composed of Fin and Base
Authors: Yu Byung Geel , Kim Ye Lim , Chang Si Young
Published: March 2009

Deformation characteristics of a newly developed wave-typed heat sink during
mechanical assembly of fin-base were analyzed by using the Ansys program. The original points a and b marked in the fin and base moved to the opposite y direction with increasing pressure, while their movements to x direction were relatively small. It was evident that at least 207㎫ must be applied to well bond the fin with the base. Under a constant pressure, the smaller the pressured area was, the better the bonding between fin and base was, despite a small uniform deformation in the base
area as the pressured area increased.
Characterization of Fe-Mo Alloyed Nanoparticles Synthesized by Chemical Vapor Condensation Process
Authors: Ha Jong Keun , Cho Kwon Koo
Published: March 2009

Iron(Fe)-molybdenum(Mo) alloyed nanopaticles and nanowires were produced by the chemical vapor condensation(CVC) process using the pyrolysis of iron pentacarbonyl(Fe(CO)5) and molybdenum hexacarbonyl(Mo(CO)6). The influence of CVC parameter on the formation of nanoparticle, nanowire and size control was studied. The size of Fe-Mo alloyed nanoparticles can be controlled by quantity of gas flow. Also, Fe-Mo alloyed nanowires were produced by control of the
work chamber pressure. Obtained nanoparticles and nanowires were investigated by field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction.
Effect of Slag Layer on Flow Patterns in a Gas Stirred Ladle
Authors: Cho Sung-Ho , Hong Sung Hwan , Han Jeong Whan , You Byung Don
Published: March 2009

Flow patterns and mixing behaviors in a gas stirred steelmaking ladle with a slag layer were discussed using a water model experiment as well as a numerical simulation. While the water model experiment was performed to investigate the effect of slag on the mixing behavior in ladle, the numerical simulation was carried out to figure out the flow pattern in ladle with a slag layer. Slag viscosity and its thickness in ladle were considered as major variables. It was found that a slag layer made a great change in the flow pattern in ladle, which, in turn, affected on the mixing
behavior in ladle. A flow pattern without a slag layer showed that rising bubbles eventually made a recirculation loop at the central area of the ladle and this flow pattern was regarded as a favorable flow pattern for the better mixing behavior. However, a flow pattern with a slag layer showed distorted and localized recirculating loop near side wall below slag layer. This eventually gave a
longer mixing time in ladle with a slag layer. Moreover, as the gas flow rate increases, slag existing on top of the ladle was found to be entrained into the melt. Slag viscosity and its thickness were found to be major variables affecting the behavior of slag entrainment. Lower the slag viscosity and thicker the slag layer, much more slag on top of the melt was entrained into the melt.
The Effect of Cold Equal Channel Angular Process on Texture of Magnesium Alloy (AZ31)
Authors: Lim Hee Taek , Kang Jung Hoon , Han Jeong Whan , Hwang Sun Keun , Kim Won Yong
Published: March 2009

In the present study, we have attempted to refine a microstructure of conventional AZ31 magnesium alloy using a new combination process including hot extrusion followed by a cold equal channel angular pressing (ECAP). ECAP die was specially designed with an inner die corner angle of 135 degree, the fillet angle of 45 degree and dimensional thermo-coupled elastro-plastic material
model in order to understand the change of stress and strain of the deformed material after a cold ECAP. ECAP for the AZ31 alloy, which was extruded in the extrusion ratio 20 to 1 and heat-treated at 623K, was successfully carried out at room temperature. The uniform shear band obtained from experiment was well matched with the zone of effective strain more than 0.533 estimated from
calculation. On the basis of the results, it is suggested that the room temperature ECAP makes microstructure to be refined and the basal plane to be rotated slightly from extrusion direction to axis direction. Compressive yield strength of AZ31 alloy can be enhanced up to twice in applying ECAP process. Hall-Petch relations do not fit to the experimental data This can be ascribed to the texture effect. Room temperature ECAP process is very promising in improving mechanical properties of
AZ31 alloy in terms of grain refinement and texture control.
Kinetic Analysis of the Decomposition of Calcium Carbonate Using Danyang Limestone
Authors: Cho Sang Hwan , Joo Sung Min , Cho Jin Sang , Yu Young Hwan , Ahn Ji Whan , Han Choon , Kim Hwan
Published: March 2009

Non-isothermal behaviors of calcium carbonate using Danyang limestone were
investigated. It was attempted to provide non-isothermal data with a precision sufficient for the determination of reliable decomposition behaviors and for the estimation of accurate kinetic parameter. The decomposition temperature of calcium carbonate on the onset, peak and final point were measured. Reaction rate was decreased and maximum reaction temperature was increased
with increasing heating rate. Activation energy of Danyang limestone was 45.14㎉/㏖ and 50.80㎉/ ㏖ by Kissinger method and Freeman method, respectively.
Hydrogen Absorption Kinetics of Ti-Nb-Cr Alloys
Authors: Shin Kyung , Seok Song , Kweon Soon Young , Kim Il Ho , Lee Young Geun , Hong Tae Whan
Published: March 2009

The Ti-Cr systems are known to consist of BCC solid solution, C36, C14, C15 Laves phase at high temperature. Among others, BCC solid solution phase has been reported to have a high hydrogen storage capacity. However, activation, wide range of hysteresis at hydrogenation/dehydrogenation, and degradation of hydrogen capacity due to hydriding/dehydriding cycles have to be improved for its application. In this study, for improving such a problem, we added on Nb. To obtain a target materials, Ti-1Nb-10Cr, Ti-3Nb-10Cr and Ti-5Nb-10Cr specimens were
prepared by planetary ball mill. The milling process was carried out under nitrogen atmosphere. Specimens synthesized were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermo gravimetric analysis/differential scanning calorimetry(TG/DSC). In order to examine hydrogen absorption
kinetics, Sievert's type automatic pressure-composition- isotherm (PCI) was performed at 293, 323 , 373 and 423K under 1, 5MPa hydrogen atmosphere.
Correlation of Superhydrophilicity and Photocatalytic Activity in the TiO2-Based Porous Thin Films
Authors: Chai Seung Yong , Park Jin Koo , Kim Ho Kun , Lee Wan In
Published: March 2009

Transparent TiO2, WO3-TiO2, and MoO3-TiO2 films were prepared by spin-coating each colloidal suspension. The monolayer coverage of WO3 on the surface of TiO2 greatly increased the photocatalytic activity in the decomposition of gaseous 2-propanol, whereas the addition of MoO3 considerably decreased the photocatalytic reaction of TiO2. For the estimation of superhydrophilicity, the change of contact angles between the water drop and the film surface was measured as a function of UV-irradiation time. The measured contact angle of WO3-TiO2 film was considerably lower than that of TiO2 before the UV-irradiation, and it decreased to the minimum
value about 4 times faster than that of pure TiO2 films with the irradiation of UV light. On the other hand, MoO3-TiO2 films showed a low contact angle at initial point, but their contact angle was very slowly decreased under the UV light. The initial low contact angles suggest the high hydrophilic character of WO3-TiO2 and MoO3-TiO2 films with high Lewis surface acidities. The observed trend suggests that the superhydrophilicity is closely related to the photocatalytic activity.
Quantitative Analysis of Micro-Macro Domain Transition of PNN-PT-PZ(x) System at Higher PZ Content
Authors: Yoon Man Soon , Ur Soon Chul
Published: March 2009

Since the discovery of relaxor behavior in Pb(Mg 1/3 Nb 2/3 )O3 (referred to as PMN), the studies of relaxor ferroelectrics with Pb(B'1/3B"2/3)O3 type perovskites have intensified because of their excellent dielectric and electromechanical properties. The present study is mainly focused on
the quantitative analysis of micro-macro domain transition, using dielectric spectroscopy, hot-stage TEM. The deviation from Curie-Weiss behavior was investigated over a broad range of temperature. As the relative contents of PbZrO3 increased, the Curie-Weiss temperature decreased, while the Curie-Weiss constant increased. However, the Lorentz polarization factor (γ) decreased with
increasing PbZrO3 content, indicating an enhanced relaxor behavior in the PNN-PT-PZ(x) system at higher PZ content. A microscopic examination demonstrates that the relaxor-normal ferroelectric transition corresponds to a micro-macro domain switching. The long-range ferroelectric domains below the transition temperature were characterized by twin-like 90o macro domains with tetragonal
symmetry and by the subdomains, which presumably relieves the internal electrostrictive strains associated with the polarization nonuniformity caused by the polar nanodomains.
Thermal Properties of Bi2O3-B2O3-ZnO Glass System
Authors: Kim Yu Jin , Hwang Seong Jin , Kim Hyung Sun
Published: March 2009

Oxide glasses having lower glass transition temperature are widely used in electric
devices. The oxide glasses usually contain lead oxide. Recently, lead oxide glasses have been replaced with lead-free oxide glasses because of the environmental pollution. We investigated the thermal properties and the glass formation region in the Bi2O3-B2O3-ZnO ternary system. The results showed that the ratio of Tg/Tl of the bismate glasses is around 0.55, which is lower than the value of ratio 0.67, the two-third rule (Tg/ Tl=2/3)
Formation of Layer on Bismate Frit Surface during Wet Milling
Authors: Cha Myung-Lyoung , Hwang Seong Jin , Kim Hyung Sun
Published: March 2009

We investigated the mechanism of chemical reaction between Bi2O3 glass and water solution during milling. As a result, the frit condition affected discoloration with crystallization. After milling, there was a deposited layer on the frit surface. The layer was composed of leached ions, contaminates of metal oxides, and hydroxides. Bismate glass frit is reacted to the milling solution so that the frit surface is formed with a gel layer. In milling, contaminates contained in milling solution is contributed to the formation of deposed layer on frit surface.
Evaluation of Pelletized Adsorbent Made for Removing VOCs by MSWI Fly Ash ( Ⅱ )
Authors: Shim Young Sook , Yoo Yeong Seok , Rhee Seung Whee , Lee Woo Keun
Published: March 2009

The objective of this study is to prepare a pelletized adsorbent to remove volatile
organic compounds (VOC) from the municipal solid waste incinerator (MSWI) fly ash in Korea. The fly ash sample was sieved to particle size of 75-150㎛, and then a hydrothermal processing was carried out. The pelletized adsorbent was prepared from hydrothermal treated fly ash by mixing it with coal tar pitch and K2CO3 as a carbon source and activating agent, and activating them. The
optimum condition to derive maximum iodine adsorptivity and BET surface area was the mixing ratio of hydrothermal treated fly ash, coal tar pitch and K2CO3 of 40/40/20 wt.% at the activation temperature of 800°C. Under this condition, the iodine adsorptivity and BET surface area for prepared adsorbent were 455 mg/g and 325 m2/g, respectively.
Application of Media Manufactural by Waste Plastic to Stormwater Treatment in Urban Drainage System
Authors: Kim Seog Ku , Yun Sang Leen , Kim Young Im , Kang Sung Won , Lee Yong Jae
Published: March 2009

While more attention has been paid in recent years to urban point source pollution control, no considerable measures have been taken to control urban non-point source pollution. Contaminants from non-point sources deposited on urban impermeable surfaces such as road and highway are easily released to the public waters by rainfall, leading to the deterioration in water quality in urban area.
Experiments were performed using a reactor and real rainwater runoff obtained from road surfaces at various pollutant loading and rainfall intensity to determine the criteria for the first flush rainwater and to evaluate the applicability of the reactor for treating road runoff. The results at different rainfall intensities show that the medium PPB is superior to the other media for water permeability. PPB was not blocked at 10 mm/hr rainfall, and its permeability was stable. On the other hand, PVS and PPF resulted in a substantial overflow ratio even at 1 mm/hr rainfall intensity. Comparison of treatment efficiencies for suspended solids showed that all media showed similar removal efficiency ranging from 91% to 95%. However, PPB seems to be better
than the other media considering its higher water permeability. PPB and PPF, both hydrophobic, yielded over 76% of heavy metal removal. But the hydrophilic media PVS showed much smaller removal efficiency ranging from 26% to 47%. The treatment efficiencies over PAHs (Poly Aromatic Hydrocarbons) showed the similar removal efficiency ranging from 66% to 97% for all three media. In this study a reactor using filter media was investigated to reduce the level of contamination in urban road runoff.
Influence of Deposition Parameters on Adhesion/Cohesion of Plasma Sprayed TiO2 Coatings
Authors: Chen Huang , Lee Soo Wohn , Hur Bo Young
Published: March 2009

Adhesion/cohesion is one of the most important properties for coatings. It is related with their durability and functionality of coatings. In this study, a series of TiO2 coatings were prepared by atmosphere plasma spraying under different deposition parameters. Their adhesion or cohesion was evaluated as a function of coating thickness as well as deposition parameters using the scratch
test. In addition, the influence of deposition parameters on coating porosity, surface roughness, and microhardness is discussed. The results indicate that the deposition parameters investigated have a remarkable influence on coating porosity and microhardness as well as adhesion or cohesion, but no obvious influence was observed for surface roughness.
Effect of Slag Compositions on the Extraction of Metallic Components from the Used PCB
Authors: Jang Sung Hwan , Han Jeong Whan , Jeong Jin Ki , Lee Jae Chun
Published: March 2009

From materials view point, a PCB (Printed Circuit Board) is a simple mixture of various metals, plastics and oxides. Thus, it can be regarded as urbanized resources or ores. The existence of valuable metallic components in used PCB, then, becomes a major driving force for the recycling In this study, the effect of slag compositions on the extraction of valuable metallic components from
the used PCB is investigated. Especially, a melting temperature of slag and slag viscosity are discussed as major operating parameters. PCB contains nearly 30wt% of SiO2 and 20wt% of Al2O3 as major oxides, and by just adding other flux components to used PCB, 20wt%Al2O3-Xwt%SiO2 - Ywt%CaO-10wt%MgO slag system with low melting point and low slag viscosity can be made to extract metallic components from used PCB by gravity separation. The slag basicity was changed
under fixed compositions of Al2O3 and MgO. It was found that a proper melting temperature and slag basicity to make a homogeneous liquid slag and to extract metallic components from used PCB were 1573 K, and 0.75, respectively.
Microstructural Transformations of an Amorphous Fe90 Zr10 Alloy Induced by High-Energy Ball-Milling
Authors: Choi Pyuck Pa , Kwon Young Soon , Kim Ji Soon , Kwon Dae Hwan
Published: March 2009

Mechanically induced crystallization of an amorphous Fe90Zr10 alloy was studied by
means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Under high-energy ball-milling in an AGO-2 mill, melt-spun Fe90Zr10 ribbons undergo crystallization into BCC α- Fe(Zr). Zr atoms are found to be solved in the Fe(Zr) grains up to a maximum supersaturation of about 3.5 at.% Zr, where it can be presumed that the remaining Zr atoms are segregated in the grainboundaries.
The decomposition degree of the amorphous phase increases with increasing milling
time and intensity. It is proposed that the observed crystallization is deformation-induced and rather not attribute to local temperature rises during ball-collisions.
Effect of Indium on the Microstructures and Mechanical Properties of Dental Gold Alloys
Authors: Jung H.Y. , Lee S.H. , Doh Jung Mann , Yoon Jin Kook , Lim H.N.
Published: March 2009

The effect of indium on the microstructures and mechanical properties of a Au-Pt-Cu
alloy was investigated. The Au-Pt-Cu-xIn alloys heat-treated at 550°C for 30 min revealed a maximum hardness value of 207 HV, irrespective of the heat temperature and In contents. Also, the hardness of the Au-Pt-Cu-xIn alloys (x = 0.5, 1.0, 1.5, 2.0) aged at 550 °C rapidly increased with increasing aging time, and it reached an almost constant value after 30 min. The hardness of the Au- Pt-Cu-xIn alloys aged at 550°C for 30 min increased with increasing In content until 1.5wt%, but it
slightly decreased with more increasing In content. Also, a variation of the tensile strength of the alloys with In contents showed a similar trend of hardness change with In contents. Analysis of EDS and TEM revealed that the microstructure of Au-Pt-Cu-xIn alloys is composed of solid solution with fcc structure and intermetallic InPt3 precipitate with L12 structure. Based on this investigation, it can be concluded that an increase in hardness of Au-Pt-Cu-xIn alloys is ascribed to a complex effect of the precipitation hardening of InPt3 and the grain size refinement.
An Amperometric Biosensor Using Prussian Blue Modified Electrode
Authors: Yi In-Je , Kim Ju-Ho , Kang C.J. , Park Jae Hyun , Kim Yong Sang
Published: March 2009

The performances of an electrochemical detector (ECD) using Prussian blue (PB) modified indium tin oxide (ITO) electrode were investigated. PB is one of the well-known catalytic materials. PB offers electrocatalytic reaction between electrode and analytes (dopamine and catechol). We optimized the PB film thickness that would catalyze redox reaction efficiently using surface
topography from atomic force microscopy (AFM). Capillary electrophoresis (CE) and amperometric method were used to separate and detect the testing analytes. The results showed that the PB film could serve as an excellent mediator, which catalyzes electron transfer. We measured electropherograms for the testing analytes consisting of catechol and dopamine with their concentrations of 100 µM and 10 µM, respectively.
Preparation of Silver Metallic Sponge from Macroporous Carbon Template
Authors: Yan Jia , Wang An Jie , Kim Dong Pyo
Published: March 2009

Silver-containing porous frameworks have been extensively used in catalysis,
electrochemistry, for heat dissipation and biofiltration. In this study, porous silver sponge was prepared by using a sacrificial macroporous carbon template. Aqueous AgNO3 was infiltrated into the carbon template and reduced to Ag by borohydride reduction reaction, followed by burning of the sacrificial template in air at 500~650°C. The products were characterized by SEM, XRD, and N2 adsorption-desorption isotherms. The Ag sponge exhibited a BET surface area of 12 m2/g.
Influence of Doping on the Antibacterial Effect of TiO2 Nanoparticles
Authors: Liu Guo Mei , Wang Kai , Zhou Zuo Wan
Published: March 2009

TiO2 nanoparticles doped with V, Mn or Zn, respectively, were synthesized from pure TiO2 and dopants calcinating at definite temperature. The physical properties of prepared TiO2 nanoparticles were characterized by TEM, XRD and UV-vis spectrum. The TEM images showed that the diameters of the particles were 20~50 nm. There was no peak of doping elements in the XRD spectrum of nano-sized TiO2 doped, but the peak of a little amount of rutile was observed, which
demonstrated that V, Mn and Zn might locate in the TiO2 octahedral lattice, or might be highly dispersed within crystalline of TiO2. In the meanwhile, doping of the TiO2 decreased the temperature for TiO2 transforming from anatase into rutile, and promoted the transforming. It was found that a little amount of V5+ may take the place of Ti4+ in the lattice of TiO2. The red-shift was clearly observed in the UV-vis spectrum of TiO2 nanopowders doped with V. As a result, the band gap was
changed and the TiO2 nanopowders doped with V enable to absorb visible light. The red-shift could be assigned to the charge transfer transition between the 3d orbital of V5+ and the TiO2 conduction or valance band. The red-shift was not observed in the UV-vis spectrum of TiO2 nanopowders doped with Mn and with Zn, the shape of which was similar to that of pure TiO2. The results of the minimum inhibition concentration (MIC) for Escherichia coli and Staphylococcus aureus showed that
vanadium ions doping intensely improved the antibacterial efficiency of nanocrystallites. This was attributed to the change of surface properties of metal ions doped semiconductor, such as O vacancies, Ti interstitial ions and vanadium ions which took the place of titanium.
Foaming Characteristics of Al-Mg Alloy Foam
Authors: Kim Sang Youl , Um Yong Su , Hur Bo Young
Published: March 2009

Al-Mg alloy foam used in this study was prepared, and Al-Mg alloy was melted by using a high-frequency induction furnace. Thickening and foaming agent were added to the molten Al-Mg alloy at a specific temperature, which was stirred. For uniform distribution of thickening and foaming agent, the impeller was rotated with high-speed about 400-1000rpm. When left in a furnace for a specific period after uniform dispersion of the foaming agent, gas was generated from the foaming
agent and the cell size and distribution inside. We determined the structure of Al-Mg alloy foam using CT(Computed Tomography). The structure of Al-Mg alloy foam has homogeneous cell size at the bottom, larger cell size in the middle, and oalescence cell in the top part. To prevent this phenomenon, the viscosity and surface tension of the melt of Al-Mg alloy were controlled.
Photo- and Electroluminescence of Hydrogenated Nanocrystalline Si Prepared by Plasma Enhanced Chemical Vapor Deposition Techniques
Authors: Shim Jae Hyun , Cho Nam Hee
Published: March 2009

We studied photoluminescence (PL) and electroluminescence (EL) properties of hydrogenated nanocystalline silicon (nc-Si:H) thin films prepared by applying the plasma enhanced chemical vapor deposition (PECVD) techniques. . A prototype of ITO/nc-Si:H/P-type Si wafer/Al EL devices was illustrated with its fundamental electrical and optical features. The nc-Si:H films exhibited PL spectra in a wavelength range of 350 ~ 700 nm with the maximum intensity at ~ 530 nm,
which is attributed to quantum confinement effects (QCE) owing to the presence of nanocrystalline Si. The EL device produced EL spectra with their maximum intensity at ~ 525 nm which are similar to the PL spectra. The light emission is attributed to radiative recombination related to nanocrystalline Si contained in the hydrogenated amorphous Si (a-Si:H).
Inhibition Mechanism of Magnesium Ion on Carbonation Reaction with Ca(OH)2 and CO2
Authors: Kim Jeong Hwan , Ahn Ji Whan , Ko Sang Jin , Park Woon Kyoung , Han Choon
Published: March 2009

The objective of this study is to synthesize the single phase aragonite precipitated
calcium carbonate by the carbonation process in the Ca(OH)2-MgCl2-CO2 system. Many researchers reported the influence of Mg2+ ion on the synthetic properties. The inhibition of calcite nucleation and crystal growth, distortion of calcite lattice, and change of surface electrification were investigated. Variety of particle size and aspect ratio were observed according to changes in the
concentration of Ca(OH)2 slurry, temperature, and CO2 gas flow rate. The nucleation rate increased when decreasing the temperature and increasing the CO2 gas flow rate. Particle size and aspect ratio increased at high temperature, low CO2 gas flow rate, and high concentration of Ca(OH)2 slurry, however small-sized aragonite was obtained at low temperature.
Growth of ZnO Thin Films by Metalorganic Chemical Vapor Deposition Using Isopropyl Alcohol for Oxygen Precursor
Authors: Park Jae Young , Hong Yong Sung , Kim Sang Sub
Published: March 2009

ZnO thin films were synthesized by metalorganic chemical vapor deposition on Al2O3
(0001) substrates particularly using isopropyl alcohol for oxygen precursor. Change in microstructure was investigated depending on the growth temperature and the O/Zn precursor ratio. Under an optimized condition, ZnO thin films having a very smooth surface and dense cross-sectional microstructure were obtained while possessing epitaxial crystalline alignment. However, the photoluminescent spectrum lacks the band-edge emission.
Acetate and Chloride Effects on Hydrogen Production across Crevices
Authors: Sundararajan T. , Akiyama Eiji , Tsuzaki Kaneaki
Published: March 2009

Crevice corrosion experiments on pure iron were carried out in a 0.5 M acetate buffer with varied chloride concentrations. Changes in resultant currents and morphology due to crevice attack were explained by IR potential drop mechanisms. The specimens experienced potential drop inside the crevice, which resulted in the formation of passive, active, and hydrogen evolution regions. The passive region did not exist in the electrolyte containing 0.05 M and 0.5 M chloride. Hydrogen evolution, which occurred inside the crevice was measured on rear side of the specimen
using hydrogen permeation test. The results suggest that the hydrogen produced inside the crevice is measurable using a permeation test. The entry of diffusible hydrogen showed a significant increase with the addition of chloride into the acetate buffer.
Structure and Properties of the Wear Resistant Coatings Obtained in the PVD and CVD Processes on Tool Ceramics
Authors: Dobrzański Leszek Adam , Pakuła Daniel
Published: March 2009

The paper presents investigation results of structure and functional properties of the hard wear resistant coatings obtained in the PVD and CVD processes on the Si3N4 nitride tool ceramics. Examinations of coatings structures were made using the transmission (TEM) and scanning (SEM) electron microscopes, microhardness tests, coating adhesion to the substrate with the „scratch test”,
and the coatings abrasive resistance „pin-on-disc” test. Machining tests results and roughness tests results for the machined grey cast iron surface are also presented. The research carried out proved that depositing the hard, anti wear, multilayer coatings based on the Al2O3 and TiN layers onto the
Si3N4 nitride tool ceramics with the PVD method results in obtaining better functional properties like extension of the cutting tool life, than in case of the uncoated nitride ceramics or coated with the PVD coatings and some CVD ones.
Mechanical Properties of Ultra-Fine Grained Al-Li Alloys
Authors: Adamczyk-Cieślak Bogusława , Lewandowska Małgorzata , Mizera Jaroslaw , Kurzydlowski Krzysztof Jan
Published: March 2009

The results obtained in the present study reveal the effect of equal channel angular
extrusion (ECAE) on the grain size and mechanical properties of Al-Li alloys. During 8 passes of ECAE process, coarse grain microstructure in the initial state transforms into ultrafine grained. The
final grain size depends on both total strain applied and Li content in the alloy. Due to the grain refinement the microhardness and yield stress increase by 100%. During compression deformation, the coarse grain alloys exhibit continuous hardening, whereas in the ultrafine-grained alloys, a stagnation of work hardening at the beginning of compression deformation is observed. This behaviour is related to the dynamic recovery of the severely deformed microstructure.
Technological Surface Layer Selection for Small Module Pitches of Gear Wheels Working under Cyclic Contact Loads
Authors: Gawroński Z. , Sawicki J.
Published: March 2009

Selection of proper technological surface layer well resistant to cyclic external loads
superposed onto residual stresses is presented in this paper, with a gear wheel taken as an example. The computer simulations of external loads were carried out by means of the FEM method (Finite Element Method) with the use of the ANSYS package. Residual stresses were measured by means of the Waisman-Philips and modified X-ray sin2Ψ method. The results of the stress superposition were verified experimental by with use of a circulating power stand. The applied low pressure
nitiriding method NITROVAC demonstrated a high ability to increase the durability and reliability of the discussed toothed wheel in comparison with the convencional treatment applied so far.
Growth Structures and Phase Formation in Industrially Room-Temperature Pulsed Laser Deposited FCC Ti-Based Nitride Coatings
Authors: Lackner Juergen
Published: March 2009

The current work focuses on the materials science aspects of the growth phenomena of titanium-based coatings TiN, (Ti,Al)N and (Ti,Al)(C,N) with face-centered cubic lattice structure, deposited by the industrially-styled Pulsed Laser Deposition (PLD) technique at room temperature. hese coating materials are widely spread in mechanical, tribological and decorative applications due to their exceptional physical and chemical properties. Recently, the trend of using temperaturesensitive materials like polymers and tool steels of the highest hardness demands new lowtemperature coating techniques for protective surface finishing as well as for functionalization of the surfaces. These titanium-based compounds can fulfill a wide range of these demands, but up to now there is a lack of industrially designed vacuum coating techniques operating at temperatures lower than 50 °C necessary for these materials. The PLD process is known as one of the most promising candidates for such coating demands. But up to now PLD is only a well-established laboratory coating technology and has not become a standard industrial coating technique despite its outstanding process features. The missing of PLD coating systems, which fulfill the requirements for industrial applications like high-rate deposition and adequate sizes of deposition chambers, is considered as one of the main obstacles for a breakthrough of the PLD technique. To overcome this problem an industrially designed PLD coating system has been developed and built at the Laser Center Leoben of JOANNEUM Research Forschungsgesellschaft mbH.
Influence of Substrate Temperature in Plasma Assisted Pulsed Laser Deposition of Hydroxyapatite Thin Films
Authors: Solla Eugenio Luís , Borrajo Jacinto P. , González Pio , Serra Julia , Chiussi Stefano , León Betty , Pérez Amor Mariano
Published: March 2009

The bioactive properties of hydroxyapatite (HA) are well known in the implant industry and coatings of HA have been used to enhance the adhesion of living tissue to metal prostheses. Pulsed laser deposition (PLD) in a water vapour atmosphere is an appropriate method for the production of crystalline HA coatings. In this work the effect of RF plasma on thin films of HA grown by PLD at different substrate temperatures has been studied. The physicochemical properties
of the films were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), showing that the incorporation of RF discharge in the deposition chamber can lead to changes in the crystallinity and deposition rate of the films but substrate temperature still plays the most important role.
New LDPE Copolymeric Films with Enhanced Hydrophilic Properties Prepared by Gamma Irradiation
Authors: Ferreira Luís M. , Falcão António N. , Gil M. Helena
Published: March 2009

Graft copolymerization induced by gamma radiation has being used as a tool to modify the surface properties of a range of polymeric substrates. This work describes the use of this technique for the grafting of 2-hydroxyethyl methacrylate (HEMA) branches onto low-density polyethylene (LDPE) surface, in order to improve its hydrophilic properties. Sample preparation protocols were selected from previous work in order to obtain films with high grafting yields. The obtained PE-g-HEMA films were characterized by thermal analysis techniques (DSC and TGA), and by Fourier transform infrared spectroscopy (FTIR). The results obtained show that, upon irradiation, there is some loss of cristalinity of the copolymer
backbone, but also that the samples keep a good thermal stability. The water uptake of the samples was evaluated. Hydration levels up to near 95 % with a ydration/dehydration average ratio of 1:5 were obtained.
Influence of Sterilization with γ-Irradiation in the Degradation of Plasma Sprayed Hydroxyapatite Coatings
Authors: Costa Tânia , Serro Ana Paula , Pires Eduardo , Colaço Rogerio
Published: March 2009

The influence of sterilization with γ-irradiation in the properties of plasma sprayed
hydroxyapatite (HAp) coatings used for medical implants is investigated in this work. HAp coatings were applied on titanium alloy substrates by plasma spraying and then submitted to 1 and 10 cycles of sterilization with γ-irradiation. As-applied HAp coatings were used as control samples. Afterwards, the modifications on the samples, induced by the irradiation process, were evaluated by X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Water contact angle measurements
as well as adhesion tests were also carried out in order to evaluate the influence of the irradiation process on the wettability and mechanical behaviour of the HAp coatings. No microstructural modifications were detected by X-ray diffraction after sterilization. However, the results show that sterilization with γ-irradiation originates modifications of the surface of HAp, as detected by a change of color of the coatings and by the XPS analysis. Nevertheless, these modifications do not result in significant changes in the wettability and mechanical behaviour of the HAp coatings.
Isothermal Crystallisation of a Glass from the 3CaO.P2O5–SiO2–MgO–K2O System Studied by Impedance Spectroscopy
Authors: Queiroz Carlos M. , Fernandes Maria Helena F.V. , Frade Jorge R.
Published: March 2009

Impedance spectroscopy was used to measure the changes of electrical properties during the isothermal crystallisation of the phosphate phase in bulk samples of a glass with nominal molar composition (3CaO.P2O5)20(SiO2)35(MgO)38.354(K2O)6.646, developed for biomedical applications. Crystallization studies were performed in isothermal conditions at 800°C and 860°C, and were monitored by impedance spectroscopy. XRD shows that a stable orthophosphate phase,
Ca9MgK(PO4)7 crystallizes at about 860°C, after formation of earlier phosphate precursors formed at lower temperatures, namely oxyapatite (Ca5(PO4)3O) and tricalcium phosphate (Ca3(PO4)2). The conductivity of bulk glass samples decreases at 800°C, as the phosphate precursors phases
crystallize. The opposite trend is observed on crystallizing the orthophosphate phase, at 860°C.