bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave-Assisted Synthesis of Hexagonal Barium Ferrite Powders with Nano-Particle
Authors: Dong Li Min , Han Zhi Dong , Wu Ze , Zhang Xian You
Published: March 2009

A novel ceramic synthesis technique, microwave-assisted process was investigated for the production of Barium Hexagonal ferrite (BaFe12O19) powders with improved physical properties. Compared to conventional syntheticroute, the new method significantly shortened synthetic steps and reaction time. This technique involves the reaction of stoichiometric amount of metal nitrates and appropriate dosage of citric acid at microwave oven and the whole process took only 15 min. The powders of BaFe12O19 were further investigated by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The results showed that the formation temperature of M-type Ba hexaferrite is significant low, compared to conventional furnace heating. The X-ray diffraction analysis demonstrates that the phase purity of the microwave-processed samples were determined and compared with a conventionally processed material. SEM observations indicate that the size of the synthesized BaFe12O19 powders is small and uniform distribution. Thus, microwave irradiation is proved to be a novel, extremely facile, timesaving and energy-efficient route to the synthesis of BaFe12O19 powders.
Effects of Rare Earth Oxides on the Microstructure and the Mechanical Properties of High-Purity Alumina Ceramics Sintered at Low Temperature
Authors: Sun Feng , Tian Ting Yan , Zhang Wei Ru , Chen Bo
Published: March 2009

High-purity alumina ceramics were prepared by sintering at low temperature, using rare earth
oxide Y2O3 and Tm2O3 as sintering aids. Adding the mixture of Y2O3 and Tm2O3 in the alumina powders
can effectively improve the sintering ability and mechanical properties. The mixture, Y2O3+Tm2O3, can
restrain the grains growth, fine the grain size, make the grain uniform and finally help to form compact
structure. The transgranular fracture was the main fracture mode. It was found the relative density of
alumina ceramics with 0.3wt% Y2O3 and Tm2O3, sintered at 1620°C for 3hrs, can be over 99.2% and the
strength, toughness and microhardness reach 533.1MPa, 4.9MPa⋅m1/2 and 17.2GPa, respectively.
Hydrothermal Synthesis of Nanosized Mullite Powders
Authors: Jia Xiao Lin , Li Su Ping , Zhang Hai Jun , Zhu Jiang Tao , Hu He Long
Published: March 2009

Nanosized mullite powders were prepared by hydrothermal method with bauxite as precursor.
The effects of mineralizer, hydrothermal temperature, hydrothermal time, dispersant on the phase, crystal
size and secondary granularity of the powders were discussed. The properties of the prepared powders
were characterized by XRD, SEM, and ZETASIZER. The results show that the spherical nanosized
mullite powders with crystal size of 28nm are prepared under the conditions of 0.92 mol·L-1 concentration
of NaOH, less than 85% filling ratio, 110°C for 6 h with bauxite calcined at 1040°C as starting material.
Preparation of SiBCN Microtubes from Melt-Spinnable Polymers
Authors: Gottardo Laura , Bernard Samuel , Berthet Marie Paule , Miele Philippe
Published: March 2009

SiBCN microtubes were prepared for the first time by spinning a low molecular weight preceramic polymers of boron-modified polyvinylsilazanes into green fibers ~30 m in diameter which were subsequently thermolyzed under a nitrogen atmosphere. Hollow SiBCN ceramic fibers black colored, of flexible form, ~20 m in diameter and 0.8GPa in tensile strength were produced.
Surface Roughness in High Feed Turning with Wiper Insert
Authors: Liu Zhan Qiang , Zhang Peng , Guo Peng , Ai Xing
Published: March 2009

Surface roughness in a turning operation is affected by a great number of factors. Two of
the most important factors are feed rate and the size of the corner radius. Surface roughness can be
roughly determined to increase with the square of the feed rate and decrease with increased size of the
corner radius. However, wiper insert geometries changed this relationship with the capability to
generate good surface roughness at relatively higher feeds by transferring small part of the round
insert edges into the straight cutting edges of the pointed insert. The principle of how wiper inserts
behave different from conventional inserts as to the effects on the surface roughness is explored in
this paper. Experimental study of the surface roughness produced in the turning of hardened mild
steels using coated carbide tools with both conventional and wiper inserts is conducted. The test
results prove the effectiveness of the wiper inserts in providing excellent surface roughness. The
results also suggest that the use of the wiper insert is an effective way that significantly increases
cutting efficiency without changing the machined surface roughness in high feed turning operations.
Research on Dynamic Cutting Performance of High Speed Face Milling Cutter
Authors: Zheng Min Li , Jiang Bin , Liu Jia , He Chong Yu
Published: March 2009

According to the characteristics of high speed face milling process, the models of
dynamic cutting forces and frequency spectrum were established. By means of frequency spectrum
analysis for dynamic cutting forces of high speed face milling cutter, the law of influence of cutter’s
structure and parameters on dynamic cutting performance of cutter was acquired, high speed face
milling cutter for machining aluminum alloy was developed, and evaluation for dynamic cutting
performance of cutter was processed based on experiment. The results indicate that more teeth of
cutter and greater cutting contact angle can make the energy more dispersible, higher cutting speed
and greater rake of cutter can depress dynamic cutting forces, and improve effectively dynamic
cutting performance of cutter. High speed face milling cutter with five teeth takes on better dynamic
high speed cutting performance for machining aluminum alloy, as cutting contact angle exceeds
ninety degrees but it is less than one hundred eighty degrees, and cutting speed exceeds 2260m/min.
Experimental Study on the Flexural Fatigue Damage Evolution of Layered Fiber Reinforced Concrete
Authors: Wang Ji , Zhang Ming Zhong , Fan Xiao Chun
Published: March 2009

In order to study the damage evolution law for layered fiber reinforced concrete
subjected to flexural fatigue, the flexural fatigue tests were carried out on both layered steel fiber
reinforced concrete(LSFRC) and layered hybrid fiber reinforced concrete(LHFRC) beams of which
the type of steel fiber was uniform on the same concrete mix. At the same time the flexural fatigue
tests with original concrete(OC) were carried out. Based on the experiments, both flexural fatigue
life and damage characteristic of LSFRC LHFRC and OC were compared and analyzed. The results
indicated that the fatigue life of LHFRC was a little larger than that of LSFRC under the stress level,
which was more than an order of magnitude of OC. And the fatigue distortion of LSFRC, LHFRC
and OC were similar. They all followed three-phase law. However, the proportion of every phase
was different, which proved that layered steel fibers and polypropylene fibers could effectively
restrain the degradation of concrete.
Crystal Growth and Ferroelectric Properties in Bi0.5Na0.5TiO3–BaTiO3 Crystals
Authors: Teranishi Shunsuke , Noguchi Yuji , Miyayama Masaru
Published: March 2009

0.999Bi0.5Na0.5TiO3-0.001BaTiO3 (BNT-0.1%BT) single crystals with a maximum size of 1×1×1
mm3 were successfully grown by a flux method using BNT-6%BT powder and Bi2O3 as a flux. The
crystals showed a remanent polarization of 33 μC/cm2 and coercive electric field of 40 kV/cm along
[100]Cubic. Electric-field induced strain measurements along [100]Cubic revealed an effective
piezoelectric strain constant d33
* of 80 pm/V.
Preparation of Ru Nano-Particles Dispersed on a Highly-Porous Material
Authors: Aramaki Kiyoshi , Kawaguchi Susumu , Saito Morihiro , Kuwano Jun , Saito Yasukazu
Published: March 2009

Metallic ruthenium nano-particles supported on carbon were prepared from Ru3(CO)12 and highly-porous activated carbon by adsorption of the complex under boiling conditions in an acetone or cyclohexane solution, followed by H2 reduction at 200oC. Occupation of micropores with the precursor all through the carbon surface would diminish the BET surface area and the pore volume, whereas partial restoration of them by heating the material in H2 flow would be caused by complex decomposition and coagulative growth of Ru nano-particles (3.01 nm in average from TEM observation), which were surely lager in size than the pore diameter (2.15 nm determined by adsorption-isotherm measurements). Ru nano-particles were well dispersed on carbon.
Preparation of High Lithium Ion Conductive Glass-Ceramics Solid Electrolytes in the LiTi2(PO4)3 System by the Mechanochemical Method and their Application as Coating Materials of LiCoO2
Authors: Morimoto Hideyuki , Someno Yuya , Arai Yasuhito , Tobishima Shinichi
Published: March 2009

Amorphous fine powder in the Li2O-Al2O3-TiO2-P2O5 (LATP) system were prepared directly from a
mixture of Li2O, Al2O3, TiO2, and P2O5 as starting materials using a mechanical milling technique at
room temperature. LATP glass-ceramics were obtained by heat treatment of the mechanochemically
prepared amorphous powder over the crystallization temperature. X-ray diffraction peaks due to
LiTi2(PO4)3 and AlPO4 crystals for LATP glass-ceramics were observed. Thus, high lithium ion
conducting LATP glass-ceramics solid electrolytes were prepared successfully from the
mechanochemically prepared amorphous powder. The LATP glass-ceramic fine particles were
investigated as coating materials of LiCoO2 cathode in lithium ion batteries. The LATP
glass-ceramics coated LiCoO2 electrode materials exhibited a good charge-discharge performance for
charging up to a high voltage (4.5 V vs. Li/Li+).
Analysis on the Fracture Failure of Brazed Diamonds in Wire Sawing
Authors: Huang Guo Qin , Huang Hui , Xu Xi Peng
Published: March 2009

An investigation was undertaken to elucidate the mechanisms for the fracture failure of
brazed diamonds in wire sawing. Diamonds were brazed by high-frequency induction in vacuum.
The changes of compressive strength and the appearances of the diamonds at different brazing
temperatures were obtained. The morphologies of the diamonds after sawing were also observed.
Together with the stress analysis of a brazed grit, it is found that the fracture failure of brazed grit is
the result of the brittle fracture happening on the root section of the grit, the interface between the
grit and the brazing alloy. The degradation of mechanical properties of grits in brazing is a key
factor to the reduction of their resistance to fracture. Lower machining forces as well as grit
exposure are in favor of preventing grits from fracture.
The Effect of Bone Regeneration According to Maintenance Period of the PTFE Membrane in Rabbit Calvarial Defects
Authors: Jang Han Wook , Kim Hyung Seok , Jung Min Gu , Kim Hyun Sung , Kim Byung Ock , Jang Hyun Sun
Published: March 2009

The purpose of this study is to figure out the effect of maintaining period of PTFE membrane used in GBR with autogeonous bone, heterogeneous bone and synthetic bone on bone formation on rabbits' cranial defect. Eight adult New Zealand white rabbits were used in this study. Four defects were surgically made in their calvaria. Using a trephine bur, 4 'through and through' defects were created and classified into 4 groups, which were consisted of control (no graft), experimental group 1 (autogeonous bone) and experimental group 2 (deproteinized bovine bone: OCS-B®; NIBEC, Korea), experimental group 3 (synthetic bone: MBCP; Biomatlante, France). The defects were covered with PTFE membrane (Cytoplast®, Innova, Canada). Membranes were removed after 1, 2, 4 and 8 weeks post-GBR in each 2 rabbits. And then, all rabbits were sacrificed; specimens were taken and observed histologically..: After removing the membranes after 1 week of the experiment, bone formation was not evident in a control group but the area was replaced with only loose fibrous connective tissue. In group 1(autogeonous bone), thin bone formation and infiltration of connective tissue on the superficial layer were observed. Initial bone formation and infiltration of fibrous connective tissue were evident in group 2(deprotenized bovine bone) and 3(synthetic bone). When the membranes were removed after 2 weeks of the experiment, bridge shaped bone formation was shown in control group but mostly connective tissue took place. More increased bone thickness was evident in group 1 and increased bone formation than first week was shown in group 2 and 3. When the membranes were removed after 4 weeks of the experiment, 2/3 of normal bone thickness was formed in control group still with infiltration of connective tissue. In group 1, regular bone formation with normal bone thickness was shown and in group 2 and 3, similar bone thickness to the normal was evident. After the removal of the membranes in 8 weeks, bone thickness formed in control group was more increased than 4th week, but could not reach normal bone thickness. In group 1, normal bone thickness was formed and similar bone thickness to that of the normal was observed in group 2 and 3. Within the limited study, when performing the GBR procedure, at least 4-week period of the membrane retention is required, and more retention time of the xenograft or synthetic bone is needed than that of autogenous bone for better bone regeneration.
Investigation on Screwy Microstructure of Solid-Trough Shell
Authors: Chen Bin , Sun Shi Tao , Peng Xiang He , Fan Jing Hong
Published: March 2009

Scanning electron microscope (SEM) observation shows that Solid-trough shell is a kind of bioceramic composite consisting of laminated aragonite and organic materials. The aragonite layers are parallel with the surface of the shell and consist of numerous thin and long aragonite fibers. The aragonite fibers in an arbitrary aragonite layers possess different directions and compose a kind of screwy microstructure. The maximum pullout force of the screwy microstructure was investigated and compared with that of parallel microstructure based on their representative models. It shows that the maximum pullout force of the screwy microstructure is markedly larger than that of the parallel microstructure, which was experimentally validated.
Fire Resistance of Bar-Reinforced Concrete Filled Steel Columns
Authors: Xu Lei , Liu Yu Bin
Published: March 2009

In this paper a numerical model for fire resistance analysis of bar-reinforced concrete filled steel columns with square and circular cross-sections have been put forward. The model has been validated by testing results. There is a good agreement. Used of the theoretical model, the relations between the fire resistance and various parameters have been analyzed. On the basis of that, formulas for the calculation of the fire resistance of bar-reinforced concrete filled square and circular steel columns under ISO-834 Standard Fire Curves are developed respectively. The calculated results have a good agreement with those of mechanic model and test.
Tribological Characteristics of Carbon Nano-Fiber Dispersed Silicon Nitride Based Composites in High-Temperature Fuel
Authors: Wada Masashi , Kashiwagi Kazumi , Kitaoka Satoshi , Fuwa Yoshio
Published: March 2009

The effect of carbon nano-fiber (CNF) dispersion on the tribological behavior of Si3N4 based composites against bearing steel were investigated in kerosene. The friction coefficients were not affected by the CNF addition. On the other hand, the wear rates of Si3N4/CNF composites showed a minimum value on 3 mass% CNF additions. The primary wear mechanism of Si3N4 is considered to be controlled by oxidation wear of Si3N4 due to a trace amount of water as impurity in the kerosene.
A Quantitative Basis for Rocking Curve Measurement of Highly Oriented Polycrystalline Thin Films
Authors: Toraya H. , Hibino H. , Ida Takashi
Published: March 2009

A quantitative basis for rocking curve measurements of preferentially oriented
polycrystalline thin films is presented. The Gaussian function is used for modeling the preferred orientation of crystallites around the plane normal of the specimen surface. A theoretical rocking curve is fitted to the observed curve by the least-squares method, and the degree of preferred orientation, given in volume fraction, can be derived from a refined preferred orientation parameter of
the distribution function even when the preferred orientation is very small. Uses of diffractometers equipped with parallel-beam optics and the integrated intensity rather than peak intensity are important for reliable rocking curve measurement.
Completion of Crystal Structure with Polyhedral Coordination: A New Procedure
Authors: Altomare Angela , Cuocci Corrado , Giacovazzo Carmelo , Grazia Anna , Moliterni Anna Grazia Giuseppina , Rizzi Rosanna
Published: March 2009

The ab-initio crystal structure solution via powder diffraction data is often uncomplete. A recent procedure POLPO [1] aims at completing a partial structure model provided by Direct Methods by exploiting the prior information on the polyhedral coordination of the located atoms (tetrahedral or octahedral) and their connectivity has been developed. The POLPO procedure requires that all the cations are correctly labelled and rightly located. This condition does not always occur, particularly when the data quality is poor. A new method is described which is able to locate missing cations and surrounding anions when the cation coordination is tetrahedral or octahedral.
Features of Crystal Structure and Ferroelectric Phase Transitions of KTiOPO4 Doped with Nb and Sb
Authors: Ivanov S.A. , Stefanovich Sergei Yu. , Eriksson S.-G. , Voronkova V.I. , Losevskaya T.Yu. , Yanovskii V.K. , Tellgren Roland , Rundlöf Håkan
Published: March 2009

The evolution of the crystal structures as a function of temperature of the new solid-
solution KTiOPO4 (KTP) isomorphs, namely K1-xNbxTi1-xOPO4 and K1-xSbxTi1-xOPO4 have been studied by neutron powder diffraction below and above the ferroelectric phase transition temperatures. On the basis of the experimental data obtained the cation distribution, among the sublattices of this structure, and the distortion of the framework at the phase transition, have been discussed. The possible correlation between the non-linear optical properties and the dominant structural features tailored by compositional variation has also been studied.
Phase Transformations in Li-Mn-O Spinels Synthesized by Sol-Gel Method
Authors: Lisovytskiy D. , Kaszkur Z. , Baumer V. N. , Pielaszek J. , Marzec J. , Molenda J. , Dygas J. , Kopeć Monika , Krok F.
Published: March 2009

Abstract. Lithium-manganese spinels obtained by sol-gel method were studied by XRD, impedance spectroscopy, electric conductivity and thermogravimetric analysis (TGA). Heating of low-temperature spinels up to 630° C leads to the formation of spinels with lattice constants close to stoichiometric high-temperature spinels, which exhibit no phase transition around room temperature and have good electric conductivity.
The Effect of Varying Ca-Content on the Structure of High-Tc Superconductor (CaxLa1-x)(Ba1.75-xLa0.25+x)Cu3O7-δ (x = 0.5, 0.6, and 0.8) Studied by Neutron Powder Diffraction
Authors: Sato Yasushi , Valkeapää M. , Petrykin Valery , Osada Minoru , Eriksson S.-G. , Kakihana Masato , Rundlöf Håkan
Published: March 2009

We have performed neutron powder diffraction (NPD) experiments on
polycrystalline powders with nominal compositions (Ca0.5La0.5)(Ba1.25La0.75)Cu3O7- δ ,
(Ca0.6La0.4)(Ba1.15La0.85)Cu3O7-δ and (Ca0.8La0.2)(Ba0.95La1.05)Cu3O7-δ . The diffraction patterns, analysed by the Rietveld method, show that all samples consist mainly of a tetragonal Y-123 type phase. Unit cell parameters a and c shorten as the calcium content increases: a = 3.8660(2), 3.8634(3), and 3.8624(5) Å; c = 11.6325(11), 11.6143(14), and 11.5822(20) Å for x-values 0.5, 0.6, and 0.8, respectively. For the x = 0.6 and 0.8 samples the Rietveld refinement of calcium occupancies and EDX analysis suggest that the actual composition is closer to x ≈ 0.5. However, since the lattice parameters do change, it is also suggested that at these higher doping levels calcium does enter the Y-
site to a larger extent than for the x = 0.5 composition. This is also in accordance with previously reported values for the Tc, which decreases slighty as x changes from 0.5 to 0.6 and has a pronounced change from 80 K to 73 K for x = 0.6 and 0.8, respectively.
The Evolution of the Antiferromagnetic Structure of the Terbium Titanium Oxysulfide Tb2Ti2S2O5 between 5K and 1.4K
Authors: Lafond A. , Leynaud O. , André G. , Bourée F. , Caldès M. , Meerschaut A.
Published: March 2009

The Tb2Ti2S2O5 compound belongs to the lanthanide titanium oxysulfides family Ln2Ti2S2O5. The 3D-structure can be schematically described as a 2D-stacking of [Tb2S2] layers alternating with [Ti2O5] ones. The magnetic structure of this compound was determined from neutron diffraction experiments on a powder sample in the 1.4 K - 15 K temperature range. An incommensurate antiferromagnetic long-range order (LRO) occurs at temperatures ranging from 4.1 K to 2.9 K, which turns to a commensurate state below 2.4 K. The evolution of the propagation vector from ki, ⃗ (kx,0,0), kx ≈ 0.46 to kc, ⃗(1/2,0,1/2) is quite unusual. The origin of this unusual
change in direction of the propagation vector is not yet explained. On the other hand, a quite large part of the total magnetic moment is involved in a short range ordering (SRO). The refinement procedure taking into account the different coexisting magnetic phases leads to a smooth variation of the total magnetic moment versus temperature.
Aluminum Alloy Strips Casting Using an Unequal Diameter Twin Roll Caster
Authors: Nakamura Ryoji , Takahashi Kenta , Ikawa Masahiko
Published: March 2009

An unequal diameter twin roll caster was devised in order to increase productivity of the strip. This caster could cast the strip thicker than 6mm at the speed of 5m/min. The feature of this caster is that the lower roll was four times larger than the upper roll. The solidification length of the strip could be set longer easily than the conventional twin roll caster for aluminum alloy. Lowsolidification rate semisolid casting and low superheat casting were adopted. These were effective to increase the casting speed without decreasing the thickness of the strip. In the present study, the unequal diameter twin roll caster was designed and assembled. The test castings were operated and the characteristics of this caster were shown.
Grain Boundary Area, Grain Boundary Curvature and Particle Pinning in an Al-1mass%Mn Alloy Containing Al6Mn Precipitates
Authors: Rios Paulo Rangel , Fonseca G.S.
Published: March 2009

The usual expression to calculate the limiting grain radius due to particle pinning is
RL=ar/f, where r is the particle radius, f is the volume fraction of the particles, RL is the limiting grain radius and a is a constant equal to 1/6 according to Rios[Acta Metall. Vol. 35 (1987) p. 2805]. This form is not convenient for comparison with experimental measurements. In this work two alternative expressions are proposed: 1)SVL=3SVP where SV is the grain boundary area per unit of volume and SVP is the interface area per unit of volume and 2)H=SVP where H is the total grain boundary curvature. These expressions are compared with experimental measurements carried out in a high purity Al-1mass%Mn alloy containing Al6Mn precipitates annealed for 3600 s at temperatures ranging from 500 to 620 oC. Good agreement is obtained between theory and experiment. The relative merits and shortcomings of each expression are discussed in detail from a fundamental and experimental point of view. It is concluded that the first expression is probably the
best choice for practical purposes.
Modeling and Analyzing on Nonuniformity of Material Removal in Chemical Mechanical Polishing of Silicon Wafer
Authors: Su Jian Xiu , Guo Dong Ming , Kang Ren Ke , Jin Zhu Ji , Li X.J. , Tian Y.B.
Published: March 2009

Chemical mechanical polishing (CMP) has already become a mainstream technology in global planarization of wafer, but the mechanism of nonuniform material removal has not been revealed. In this paper, the calculation of particle movement tracks on wafer surface was conducted by the motion relationship between the wafer and the polishing pad on a large-sized single head CMP machine. Based on the distribution of particle tracks on wafer surface, the model for the within-wafer-nonuniformity (WIWNU) of material removal was put forward. By the calculation
and analysis, the relationship between the motion variables of the CMP machine and the WIWNU of material removal on wafer surface had been derived. This model can be used not only for predicting the WIWNU, but also for providing theoretical guide to the design of CMP equipment, selecting the motion variables of CMP and further understanding the material removal mechanism in wafer CMP.
Border Surface Changes on the Edge of the Castings with Nodular Graphite
Authors: Szocs Katalin , Vaida Maria
Published: March 2009

The paper presents the study of the microstructure and ultrasound measurments by
proeminent part of the nodular iron castings. The experiment has been made in the Havy Machine Factory in Clausenburg. The crossing speed of the ultasound increases near the edge of the castings. Analising the nodular iron microstructure by smoler castings, there occurs no graphite change. By bigger mouldings the shape of the graphite can change to a vermicular graphite near the edges. The thickness of the transformed stratum is of 0,1-0,3 mm. In the nodular graphite iron are acting the forces in the frontier-surface. After casting the evaporation of the magnezium increases near the edge of the castings. The changes of forces on frontier surface can be caused by the changes of the innere tension, and also by the
interacting of moulding materials. Opinions regarding these two effects are contardictory in the technical literature. Our experiments have been made in the Heavy Machine Combinat (C.U.G) in Kolozsvar, on nodular iron containing different ferrit-pearlite proportions. The weight of castings varried between 0,5 kg and 8000 kg. The metalic melt necessary to nodulisation was produced inductive furnaces of 6,3 and 12 tons. Before treatment by magnezium alloy, the chemical composition of the iron melt varried between the following parameters, according to the different types of irons: 3,7-3.9% C, 0,2-1,4% Si, 0,1-1,0% Mn, max. 0,025% S, max. 0,05% P, 0,1-1,4% Cr,%, 0,05-0,3% Mo, 0,2-0,8% Cu, 0,2-2,0% Ni. The globularisation has been made in the Tundich-pot. The work-temperature was between 1450 and 1600 C. We used 1,8 – 2,2% FeSiMg and 0,4-1,6% FeSi for the nodulisation. Our target was the examination of the surface strata on the castings, using for mould mixtures with different chemical effect.
Investigation of Notch Sensitivity and Blade Breakage of Bandsaw Blade Steels
Authors: Dobránszky János , Magasdi Attila , Ginsztler János
Published: March 2009

Bandsaw blades are one of the most commonly used tools of the wood cutting industry. Their base materials are mostly unalloyed or poorly Cr-alloyed tool steels. After the review of the bandsaw blade’s cyclic load characteristics, we present the typical failures, which can be, originate in it’s cracking. With the use of these information an overall systematization has been set up by the bandsaw blade cracking types and its root causes. The main place of the failure is the weld and the
heat-affected zone’s area where the welding can failure or the lack of toughness can produce cracking. An other zone, where cracking may appear is the bandsaw blade’s tooth gullet because it raises the stress intensity factor. Special material testing methods have been made to investigate the tooth gullet’s notch sensitivity from the test results that a comparison of several bandsaw blade base material,
are reviewed. With the use of the results a notch sensitivity rating system has been worked out, which can be used to rate different bandsaw blade base material’s notch sensitivity.
Effects of Al on Cycling Stability of a New Rare-Earth Mg-Based Hydrogen Storage Alloy
Authors: Liu Y.F. , Pan H.G. , Li Rui , Lei Y.Q.
Published: March 2009

In order to improve the cycling stability of a new rare-earth Mg-based hydrogen
storage alloys, La0.7Mg0.3Ni2.65-xMn0.1Co0.75Alx (x=0.0-0.4) alloys were prepared to investigate the structure and electrochemical properties of these alloys. XRD and Rietveld analyses reveal that the alloys consist of a (La,Mg)Ni3 phase with rhombohedral PuNi3-type structure and a LaNi5 phase with hexagonal CaCu5-type structure. Electrochemical studies on these alloys indicate that their maximum discharge capacities were decreased from 400.7 mAh/g (x=0.0) to 335.6 mAh/g (x=0.4). However, the cycling stability of the alloy electrodes was significantly
improved after Ni was partially replaced by Al. After 100 charge/discharge cycles, the discharge capacity retention was increased from 32.0% (x=0.0) to 73.8 % (x=0.3), which can be attributed to the formation of a dense oxide film on the alloy surface. Moreover, the high rate dischargeability measurements indicate that the electrochemical kinetic properties were deteriorated with increasing Al content owing to the presence of a dense oxide film of Al.
Characteristics of Ni-Based Bi-Layer Contacts on GaN
Authors: Zainuriah Hassan , Yam F.K. , Yap Z.J. , Aziz Azlan Abdul , Ibrahim Kamarulazizi
Published: March 2009

GaN-based materials have been the subject of intensive research recently for blue and ultraviolet light emission and high temperature/high power electronic devices. Ohmic contacts with low contact resistance are essential in improving the electrical and optical performances of the devices. A wide variety of contact metallizations have been reported for p-GaN, including the standard Ni/Au as well as Ni. Different surface pretreatments have been investigated to lower the contact resistivity. To employ metal layers as a reliable ohmic contact on GaN, it is essential to understand the thermal stability of metal-GaN contact in addition to developing low resistance
ohmic system. In this paper, we report on the characteristics of Ni/Ag bi-layer contacts on p-type GaN. The structural and electrical stability of the contacts at various annealing temperatures (480°C – 780°C)were investigated. Changes in the surface morphology of the contacts on annealing were examined using scanning electron microscopy (SEM). Specific contact resistivity and barrier height,
determined using transmission line method (TLM) and current-voltage (I-V) measurements were calculated.
Surface Morphology Characteristics and Improvements on Corrosion Resistance in Anodized Mg-Al Alloys as a Result of Sealing Treatments
Authors: Kim Seong Jong , Kim Jeong Il , Okido Masazumi
Published: March 2009

The effects of sealing solutions on the corrosion resistance of anodized Mg-Al
alloys were investigated. As the proportion of Mg(OH)2 increases with the increase in the NaOH concentration, the corrosion potential improves. The sealing effects were further improved by increasing the temperature of distilled water, the pH of solutions, and the proportion of Mg(OH)2 present in the anodic film.
Biodegradable Porous Nano-Hydroxyapatite/Alginate Scaffold
Authors: Xu Feng Lan , Li Yu Bao , Han Jimei , Lv Guo Yu
Published: March 2009

Porous scaffold containing biodegradable Ca-crosslinked alginate(ALG) and
nano-hydroxyapatite(n-HA) is synthesized by the freeze-extraction and freeze-gelation methods. The prepared scaffolds were tested by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared absorption spectra (IR), raman spectra, X-ray diffraction (XRD) and burning test. Chemical binding between inorganic n-HA and Ca-crosslinked alginate was investigated. It indicated that n-HA was interacted with Ca-crosslinked alginate. The results of SEM showed that the scaffolds exhibited open-cellular pore structures. The content of n-HA affected the porosity and pore size of the composite. The composite can be a promising scaffold material for tissue engineering.
Effect of Plasma Spraying Gas on Microstructure and Properties of 95vol.%Al2O3–5vol.%SiC Nanocomposite Coatings
Authors: Tram Pham Huyen , Min Joon Won , Chen Huang , Lee Soo Wohn
Published: March 2009

Based on the strong inhibition of SiC particles on the grain growth of the Αl2O3 matrix, a mixture powder of α-Al2O3 and SiC was used as feedstock to deposit the nanocomposite coatings by plasma spraying. To determine the effect of plasma spraying gas on microstructure and mechanical properties of Al2O3–SiC nanocomposite coatings, primary Ar gas and secondary H2 gas were chosen, which have an effect on temperature and velocity of the flyingpowders at the time of
impacting on substrate. The X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to characterize the microstructures of these coatings. Surface roughness was measured also.
Mechanical Properties of Al2O3-TiO2-SiC Nanocomposites for the Femoral Head of Hip Joint Replacement
Authors: Visbal Santiago , Lira-Olivares Joaquín , Sekino Tohru , Niihara Koichi , Moon Byung Kyu , Lee Soo Wohn
Published: March 2009

Microstructure and mechanical properties of Al2O3-TiO2-SiC nanocomposites were
studied. To improve the mechanical and tribological properties of alumina, nano-sized TiO2 and SiC powders were dispersed. Spark Plasma Sintering (SPS) technique, at 1400°C, 50 MPa for 5 minutes, was applied for the densification of Al2O3-TiO2-SiC nanocomposites. Characterization of Al2O3- TiO2-SiC nanocomposites was carried out using Scanning Electron Microscopy (SEM),
Transmission Electron Microscope (TEM), X-ray diffractometer and EDX. Fracture toughness and Vickers hardness were estimated by indentation technique. These experimental results on mechanical properties of Al2O3-TiO2-SiC nanocomposites indicated that they can be a potential material with high hardness and high fracture toughness to be used as femoral head in total hip joint
replacement.
Study of Corrosion Resistance of Anodized Ti6Al4V in SBF
Authors: Zhao Ying , Xiong Tian Ying , Jin Hua-Zi , Wang Li Bin , Li Tie Fan
Published: March 2009

A layer of amorphous thick anodic oxide film was formed on Ti6Al4V substrate after
anodization, and its thickness achieved 30-40µm. After immersion in SBF, anodized sample and substrate indicated different corrosion resistance. According to icorr, Rp and Ecorr, the concerned experimental results of potentiodynamic polarization curves, the anodic oxide film provided effective corrosion protection, which could be attributed to its relatively uniform, smooth, compact and intact microstructure. And the results of total immersion test also proved the protective role of the anodic film.
Effect of Sintering Atmospheres on the Microstructure Evolution of Alumina/Alumina:SiC Whisker Laminate Composites
Authors: Park Sang Yeup , Bang Hee Gon
Published: March 2009

Alumina/Alumina: SiC laminate composites were fabricated by the pressureless sintering method. Although the laminate defect, such as channel crack, was observed under the sintering of oxidation atmosphere, laminate defects were eliminated by the sintering of non-oxidation atmospheres. Among various atmospheres, the vacuum atmosphere was effective in the elimination of laminate defects and also for homogeneous microstructure.
Effect of Skin Pass Mill Elongation on Characteristics of Surface Friction and Formability
Authors: Hur Bo Young , Cho Sang Hun , Kim Sang Youl
Published: March 2009

Coated sheet steels have been increasingly used in automotive industry for improving corrosion resistance. When GA outer plates processed the interfacing of the coating film and the metal matrix causes surface irregularities in the surface state of the sheet metal. Consequently, research to determine each phase composite’s friction coefficient is on-going. Investigating the effects that cause surface roughness, change and mechanical properties of outer automobile plates
through temper rolling skin pass mill elongation is essential. Researching surface roughness in relation to surface friction properties requires the determination of a surface friction coefficient. This research demonstrates that there is a complex effect between the lubricant membrane and surface roughness when processing GA plates. Consequently, the strength of the lubricant membrane strongly influences the friction coefficient
Sensitivity and Thermal Property of Polyaniline Sensor
Authors: Kim Jung Suk , Cho Jae Hyun , Yu Jun Boo , Sohn Sung-Ok , Huh Jeung Soo
Published: March 2009

The polyaniline (PAn) polymer was synthesized by a chemical method using aniline (AN) as monomer, ammonium persulfate (APS) as initiator, and dodecylbenzene sulfonic acid (DBSA) as dopant at 0ı. Conducting polymer films were prepared on the alumina substrate with an interdigitated electrode by using the dip coating method. These films were soaked in methanol solvent for 1h at room temperature to remove excessive DBSA and then were heated at 70ı for 4h
in N2. The detecting materials having a liquid phase at one atmospheric were precisely controlled by the system having a mass flow controller (MFC), temperature controller and measuring chamber. The sensitivity was estimated by heating from 70ı. The sensitivity observed in PAn sensor was lower than PAn-DBSA sensor at 1000 ppm methanol vapors under N2. because the additional
thermal doping effect was resulted from increasing molecular motion in polymer chain to 70ı but DBSA used as dopant was decomposed by heating over 120ı. It caused the melting point of DBSA to be lower than 120ı. So the thermal properties of PAn and PAn-DBSA were investigated by DSC (differential scanning calorimetry). The DSC was scanned with a heating rate of 10ı/min. The PAn
sample did not show the melting peak but PAn-DBSA sample showed the melting peak at 190ı. From this result, the new crystalline-region was evaluated in PAn-DBSA and increased of crystallinity of PAn polymer. And FE-SEM studies showed that the presence of the dopant strongly influenced the morphology of the polymer.
Dual Ion Beam Sputtering for Chromium Nitride as an Alternative to Electroplated Hexavalent Chromium
Authors: Shin Kyoung Chul , Lim Jong Min , Lee Chong Mu
Published: March 2009

The hexavalent chromium used in chromium plating is so toxic that it is very hazardous to human body and even carcinogenic. Therefore, it is indispensable to develop an alternative deposition technique. To explore the feasibility of sputtering as an alternative technique for chromium plating, we investigated the dependences of the deposition rate, the phases, the hardness, the surface roughness and the corrosion-resistance of CrNx deposited on the high speed steel substrate by using a dual ion beam sputtering system on the rf-powers. The deposition rate of CrNx
depends more strongly upon the rf-power for argon ion beam than that of the nitrogen ion beam. The hardness of the CrNx film can be maximized by optimizing the rf-power, so that the volume percent of the Cr2N phase in the film is highest. Amorphous films are obtained when the rf-power for nitrogen ion beam is much higher than that for argon ion beam. The CrNx film deposited by using the sputtering technique under the optimal condition provides corrosion-resistance comparable to that of the electroplated chromium.
Effect of RO Components on Some Properties of Pb Free Glass Frit for PDP
Authors: Hwang Jong Hee , Lim Tae Yeoung , Kim Chang Yeoul , Han S.M. , Park Jin Sook , Masaki T.
Published: March 2009

The effect of RO components variation on some properties was studied in Pb free glass frit for PDP (Plasma Display Panel). One of the main components, BaO, was replaced progressively at fixed concentration of alkaline earth oxides. We studied the transparency, thermal expansion, softening point, and the high temperature microscopic behaviors of glass frits and TG(thermal gravimetry) of
raw material. The compositional dependence of those properties was discussed from the view points of compositional diversity and production process of Pb free glass frit.
Characteristic of Titania Photocatalyst Fine Particles Added Zirconia
Authors: Watanabe Eiji , Takagi Makoto , Fukaya Mitsuharu , Taoda Hiroshi
Published: March 2009

Recently, the titania photocatalyst has been widely used in the environmental fields.
However, because the past titania photocatalyst used only the range of ultraviolet rays, the usage has been limited. We attempted to develop a new type of titania photocatalyst that activates to respond not only in the ultraviolet rays region but also in the visible radiation region. The titania photocatalyst fine particles that zirconium oxide was uniformly added in the titania fine particles,
and introduced simultaneously nitrogen into the crystal lattice in addition were synthesized. It was showed the high photo-absorption ability of the titania photocatalyst added the zirconium compared with not done by the absorption spectrum. Furthermore, it was found that the titania fine particles that introduced nitrogen colored to yellow, had also the high photo-absorption ability in the visible
range of 600nm to 400nm in addition to the range of ultraviolet rays. It was thought that this depended on the reason based on the difference of the amount of the nitrogen introduction in the titania that originated in the zirconium. Moreover, it was compared the stability maintenance for the titania introduced nitrogen with it not done by the bleaching test of heating. As a result, the stability of the titania added the zirconium was higher than not added.
Fabrication of Tubular Mullite-Alumina Porous Ceramics by Polymer-Aided Extrusion
Authors: Hua Yao Ai , Yang Ke , Wang Ruo Ding
Published: March 2009

Mullite-alumina porous ceramics were fabricated by polymer-aided extrusion through
using natural kaolin and alumina as starting materials. The physical and chemical properties of porous ceramics were investigated. The results showed that the approach of using kaolin as starting material offers many benefits such as low cost, big processing capacities, low mullitization temperature and unique microstructure. The porous ceramics with high strength, high porosity, narrow pore size distribution, high permeability and good thermal-shock behavior was obtained by
modifying preparation conditions.
Effect of Ti Addition on the Fracture Toughness of Al-Ti-B Alloys Synthesized by High-Energy Ball Milling and Spark Plasma Sintering
Authors: Kim Ji Hui , Lee Kwon Yeong , Kim Gyung Guk , Kim Seon Jin
Published: March 2009

Al alloys containing boron or its compound are attractive for neutron shielding materials since boron exhibits high thermal neutron absorbing capability. However, poor fracture toughness and low ductility of boron compounds restrict their usage as structural materials. By adding Ti as a third element, it is expected to improve the toughness of Al-B alloys. The present study investigates the effect of the Ti addition on fracture toughness of the (Al+Xat%Ti)2at%B (X = 0.5, 1, 1.5 at%) alloy
fabricated by high energy ball milling and spark plasma sintering (SPS). The SPS method was used to consolidate (Al+Xat%Ti)2at%B (X = 0.5, 1, 1.5 at%) alloy with the pressure of 50 MPa. Charpy impact tests showed that the fracture toughness of the 1 at%Ti added-alloy was 4 MPam1/2 , and that it was three times higher than that of Al-B alloys. Further reduction of the Ti addition down to 0.5
at% at 1.9 MPam1/2 or up to 1.5 at% at 2 MPam1/2 slightly decreased the fracture toughness. The microstructures of the present specimens were investigated by FE-SEM and TEM to describe the relationship with fracture toughness.
Synthesis and Characterization of Nanosized ITO Powders by Glycothermal Processing
Authors: Bae Dong Sik , Kim Hye Kyoung , Kim Rak Hee , Kim Jae Won , Lee Je Hyun , Park Sang Whan , Han Kyong Sop
Published: March 2009

Nanosized ITO(indium tin oxide) powders were prepared in ethylene glycol
solution under mild temperature and pressure conditions by precipitation from metal
nitrates with aqueous potassium hydroxide. The average size and distribution of the
synthesized ITO powders were about 20 ㎚ and broad, respectively. The phase of
synthesized particles was crystalline reacted at 230 0C for 6 h.. The optical properties of the synthesized ITO powders were transparent.
Synthesis of Cordierite Using High Energy Ball Milling
Authors: Kim Sung Jin , Bang Hee Gon , Park Sang Yeup
Published: March 2009

Cordierite was synthesized by the reaction sintering using a high-energy ball
milling process. After a high-energy ball milling for 32hr, the reaction temperature of
cordierite was reduced to 1350oC from the conventional synthesis temperature of
1460oC. High-energy ball milling process was effective for the formation of amorphous silica layer to provide a low reaction temperature of cordierite.
Micromechanical Mean-Field Analysis for Stress-Strain Curve of Lotus-Type Porous Iron
Authors: Tane Masakazu , Hyun Soong Keun , Ichitsubo T. , Nakajima Hideo
Published: March 2009

We studied the plastic behavior of lotus-type porous iron with unidirectional long
cylindrical pores. Lotus-type porous iron with different porosities was fabricated by the continuous zone melting method in a pressurized hydrogen and helium atmosphere. To calculate the stress-strain curves for lotus iron, we applied a modified Qiu-Weng’s micromechanical mean-field theory that has recently been proposed by the present authors [J. Mater. Res., in press], and compared the results with those of compression tests. We experimentally found that the
deformation resistance and work hardening rate depend on the sample porosity and loading direction. They decrease with an increase in porosity, and their values in the loading along the direction perpendicular to the longitudinal axis of pores are smaller than those in the parallel-direction loading. Our micromechanical calculations reproduce well the stress-strain curves experimentally obtained and express the experimental trends successfully.
Characteristics of SnOx-Coated Lithium Manganese Oxide Thin Film for MEMS Power System
Authors: Lee Jae Ho , Kim Young Jae , Moon Hee Soo , Park Jong Wan
Published: March 2009

We prepared spinel-phase LiMn2O4 layer by using rf magnetron sputtering system. LiMn2O4 films were deposited at room temperature and then annealed at 750°C for crystallization to spinel type. In order to reduce the interface reaction such as Mn dissolution phenomenon during operation, we introduced SnOx (coating-layer) thin film. The SnOx films were deposited on LiMn2O4 films by rf magnetron sputtering system. A SnOx-coated LiMn2O4 film was more stable during the chargingdischarging reaction and maintained good cycle behavior at high temperature conditions of 55°C.
Hydrogenation Properties of Mg-TiNi Hydrogen Storage Composites Materials
Authors: Hong Tae Whan
Published: March 2009

Magnesium and Magnesium alloys have been studied as one of the good lightweight
hydrogen storage materials, but the materials have strong difficulties in the fabrication process of mass production until now. The Rotation-Cylinder Method (RCM) has been developed to fabricate magnesium-based composites with moderate rotation under normal atmosphere. Inthis study, the Mg-TiNi hydrogen storage composites materials were manufactured by RCM and evaluated their hydrogenation properties by a Sieverts-type automatic pressure-composition-isotherm (PCI) apparatus at 523, 573 and 623K. The hydrogenation properties of Mg-TiNi composites depended on the behavior of TiNi reinforcements. The formation of Mg hydride, MgH2, on 4h milling samples of Mg-10mass% TiNi intermetallics hinted to the catalytic behavior of TiNi reinforcements. In addition,
the dehydriding profile at 573K revealed the two steps of plateau pressure, which were affected by the existence of multi hydride phases.