bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosorption of Heavy Metals by Pseudomonas aeruginosa Isolated from a Petroleum Contaminated Site
Authors: Pérez R. Maria , Abalos A. , Gómez José Manuel , Cantero Domingo
Published: March 2009

The study describes the sorption of Cr, Cu, Mn and Zn by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum and heavy metals. The concentrations studied (mgL-1) were Cr-50, Cu-49, Mn-60 and Zn-70. The solution pH and ionic strength were very important factors in the metal biosorption performance and the biosorption capacity of Pseudomonas aeruginosa AT18 for Cr3+ Cu2+, Mn2+ and Zn2+. In aqueous solution the biosorption increased with increasing pH in the range 5.46-7.72. The results obtained in the experimental assays show that Pseudomonas aeruginosa AT18 has the capacity for biosorption of the metallic ions Cr3+, Cu2+ and Zn2+ in solutions, although its capacity for the sorption of manganese is low (22.39 mg Mn2+/g of biomass) in comparison to the Cr3+, Cu2+ and Zn2+ ions, as shown by the individual analyses. However, 20% of the manganese was removed from an initial concentration of 49.0 mgL- 1, with a Qm value similar to that obtained in solutions containing mixtures of Cr3+ Cu2+, Mn2+ and Zn2+. The chromium level sorbed by Pseudomonas aeruginosa AT18 biomass was higher than that for Cu, Mn and Zn, with 100% removal in the pH range 7.00-7.72 and a Qm of 121.90-200.00 mg of Cr3+/g of biomass. The remove of Cr, Cu and Zn are a result also of precipitation processes.
Biorecovery of Platinum Group Metals from Secondary Sources
Authors: Murray Angela J. , Mikheenko I.P. , Goralska Elzbieta , Rowson N.A. , Macaskie Lynne E.
Published: March 2009

Since 1998 demand for the platinum group metals (PGM) has exceeded supply resulting in large price increases. Undersupply, combined with rising costs prompts environmentally friendly recycling technologies. Leachates containing PGM were produced from secondary waste sources using microwave leaching technology with the aim of recovering precious metals using bacterial biomass. Previous studies showed that metallised biomass exhibits catalytic activity; hence metal is not only recovered but can be converted into a valuable product. Cells of Escherichia coli MC4100 that had been pre-metallised with Pt were more effective at reducing PGM from the leachates. The solid recovered from the leachate onto the bacteria was characterised using X-ray Powder Diffraction (XRD) and Energy Dispersive X-ray Microanalysis (EDX). Metallised biomass was tested for catalytic activity (reduction of Cr(VI) to Cr(III)) to compare the ‘quality’ of polymetallic bacterial-based catalysts versus counterparts made from single and mixed metal model solutions.
Bioleaching of a Zinc Sulfide Ore by Thermophilic Consortia Isolated from Copahue Volcano
Authors: Giaveno Alejandra , Donati Edgardo R.
Published: March 2009

Bioleaching of a sulfide ore was investigated using a consortium of thermophilic bacteria
and archaea. The consortium was obtained through successive enrichment procedures (using M88
with tetrathionate) after isolating from two different places into the geothermal area (Baño 9 and
Las Maquinitas) of the Copahue volcano (in the north of Neuquén province in Argentina).
Bioleaching experiments were carried out in 250-ml shake flasks with 100 ml of media and 1 g of
the sulfide ore. Flasks were incubated at 150 rpm and 70 oC. The major constituents of the ore (La
Resbalosa, Argentina) were sphalerite, pyrite, chalcopyrite and galena. The sample used throughout
bioleaching experiments contained 22.5 % Zn. Two different media (0K and M88) were evaluated
with and without the addition of elemental sulfur. Genetic diversity analysis of the microbial
community was performed by PCR amplification of bacterial 16S rDNA fragments and analyzed by
DGGE (denaturing gradient gel electrophoresis). The 16S rDNA was amplified by using eubacteria
and archaea primers. Metal concentration, Eh and pH were periodically analyzed. Solid residues
were filtered, washed, dried and finally analyzed by XRD and XRF. After 45 days, more than 50 %
of zinc and about 100 % of the copper were solubilized. Galena and jarosite were detected in the
solid residues. The data indicated that the dominant acidophiles were bacteria or archaea according
to the media. M88 media allowed an important decrease of pH and higher zinc extractions while the
presence of sulfur did not show significant influence on the zinc recovery.
Influence of Chelators on Iron Solubilization from Quartz and Feldspars by Bioleaching
Authors: Štyriaková Iveta
Published: March 2009

Ultra-fine iron particles are difficult to treat by conventional mineral processing methods. Thus bioleaching is an attractive alternative for effective removal of iron minerals. The removal of oxidic Fe-phases from industrial silicates via bioleaching needs to be optimized with regard to the rate of iron reduction and dissolution. A new role for chelators as the low addition of AQDS or NTA during bacterial quality improvement of non-metallics, resulted in stimulating of Fe dissolution under non-controlled anaerobic conditions. AQDS stimulated bacterial iron reduction and Fe2+ concentration in solution was higher than Fe3+. However, NTA non-stimulated iron reduction, but increased bacterial iron dissolution in form of Fe3+. Changes in iron removal from samples were used to assess the chelator effectiveness of the heterotrophic bioleaching process. Chelators might be added to iron-contaminated non-metallics during bioleaching processes for stimulation of rate of iron removal.
Creation of Tailored High-Strength, Hybrid Sandwich Structures
Authors: Palkowski Heinz , Lange Günther
Published: March 2009

The subproject A3 deals with the production and manufacturing and the subsequent
treatment of partially strengthened, three layered, symmetrical Sandwich Structures. With this type
of strengthening, complex material properties can be developed, e.g. high strength with high
stiffness, good thermal joining properties at the place of strengthening, as well as an improved
strength and strength absorbing ability. The forming behaviour is still widely unknown.
Local Strain Hardening of Sheet and Solid Forming Components during Formation of Martensite in Metastable Austenitic Steels
Authors: Behrens Bernd-Arno , Hübner Sven , Sunderkötter C. , Knigge Julian , Weilandt Katrin , Voges-Schwieger Kathrin
Published: March 2009

The industrial application of stainless steels is of high importance because of their high
corrosion resistance and forming behaviour. The evolution of martensite during the deep drawing
processes leads to an increasing strain hardening of the material. In the collaborative research centre
675 “Erzeugung hochfester metallischer Strukturen und Verbindungen durch gezieltes Einstellen
lokaler Eigenschaften” (Creation of high strength metallic structures and joints by setting up scaled
local material properties), metal forming processes is being researched. Emphasis on this part of the
project is the stress-induced formation of martensite in sheet metal and bulk metal components in
metastable austenitic steel. The aim of the investigations is to develop partial structure fields of
martensite in sheet metal components in order to construct a lightweight structure. Therefore,
components are divided into stretched and non-stretched parts. This leads to a defined buckling of
components, for example in case of a crash. Furthermore, the effect of the transformation induced
formation of martensite in metastable austenitic steel should be utilised on bulk metal forming
components. Thereby special load adapted components with locally optimized properties are
producible, like austenitic ductile regions and martensitic high-strength areas.
Material Aligned Process Control for the Welding Technology of Locally Hardened Materials
Authors: Wesling Volker , Rekersdrees T.
Published: March 2009

The subproject B5 examines the welding technological processing of locally hardened
materials to produce structures and knots by means of high-freqency welding (HFW). The aim of
B5 is a defined intervention in process and plant technology to control current voltage, temperature
and compressive stress distribution of the entire weld seam. Particularly the effects on locally
hardened areas have to be measured and optimized. Also the process specific advantages of HFW
(e.g. plastic deformations and the application of an in situ heat treatment) have to be examined and
optimized to improve structural strength.
Aspects Concerning Rheological Properties of the CIM’s Binder Systems
Authors: Matrici Lidia , Domşa Şerban , Brânduşan Liviu
Published: March 2009

Ceramic Injection Molding (CIM) can provide design engineers with economic solution
to otherwise apparently insoluble part production problems. CIM combine attributes of plastic
injection molding with the higher properties of ceramics.
The aim of the paper is examine the rheology of binder systems with independent parameters (shear
rate, temperature, and binder content). The study also establish that the feedstocks used for CIM it
must be assured an extremely low viscosity at the injection temperature. The experimental results
show that an increasing of the wax contain with 5% leads to a more pronounced decrease of the
shear stress than the increasing with 10 oC of the temperature. In all situations the temperature’s
increasing determines a decrease of the feedstock’s viscosity and shear stress.
Effect of Small Iron, Chromium and Boron Additions as Alloying Elements on Microstructure and Mechanical Properties of Ni3Al
Authors: Orban Radu L. , Lucaci Mariana
Published: March 2009

This paper investigates the effect of Fe, Cr and B additions, in small proportions, as
alloying elements in Ni3Al with the purpose to reduce its intrinsic fragility and extrinsic
embrittlement and to enhance, in the same time, its mechanical properties. It represents a
development of some previous research works of the authors, proving that Ni3Al-Fe-Cr-B alloys
obtained by reactive synthesis (SHS) starting from Mechanically Alloyed powder mixtures have
superior both room temperature tensile strength and ductility, and compression ones at temperatures
up to 800 °C, than pure Ni3Al. These create premises for their using as superalloys substitutes.
Experimental Study Regarding Compressing Process with Assisted Friction Force
Authors: Sas-Boca Monica
Published: March 2009

Friction between powder and tools plays a major role during cold compaction of PM
components with results on the inhomogeneous densification. The present work deals with a new
method of compaction for PM components by using the friction force between die and compacts as
an active pressing force in order to reduce the density gradient. The proposal technique consists in
moving the container of the die, during pressing stage to the punch direction with a well determined
speed. As a result, the friction force acts in the same sense as the pressing load with better
distribution of powder flow during compaction. The experimental results of compaction parameters
versus density have proved the decreasing of the density gradient by increasing die/punch speed
rate. A sharp density gradient on the specimen height moving container contrarily to the punch.
Contributions to Processing of Self-Lubricated, Nanocomposite Wear Resistant Coatings by Reactive UM Magnetron Co-Sputtering
Authors: Strnad G. , Biro D. , Vida-Simiti I.
Published: March 2009

Recently a great deal of attention has been devoted to sputtering technology for nanostructured
coatings. Wear resistant nanocomposite coatings are very promising materials, which can
be easily scaled up for industrial production. Therefore, reactive magnetron sputtering of alloy
targets or co-sputtering of elemental metal targets are now intensively investigated. Present paper
presents some results of our research work for optimization of tribological properties by definition
of selected parameters for reactive sputtering process conditions of self-lubricated carbon doped
TiAlN coating. Tailored nanocomposite thin films of multicomponent and multiphase materials
have been performed by DC reactive UM magnetron co-sputtering of TiAl and TiC target materials
in Ar–N2 respectively C2H2 and CH4 as carbon precursor gases.
Tubular Composite Material for Hardfacing Layers with Protection Appliance against Abrasive Wears
Authors: Motoiu P. , Popescu Gabriela , Binchiciu Horia , Dumitrescu D. , Ivanescu S. , Fratila C. , Stoiciu F.
Published: March 2009

Thermal spraying technologies are an effective way to ensure surface protection against
destructive effects of wear, corrosion and oxidizing phenomena which can be applied in majority
industrial sectors for improving properties of new parts or for reconditioning worn out parts
technology. The powders used in this study are mainly used in the repair of cast iron parts (e.g.
engine blocks) and in build - up of press tools for car bodies, threads, turbine-guided vanes, rotating
valves and shafts in eccentric presses. Three types of tubular composites based on WC powders
were studied which demonstrated that this technology improved their properties.
Factors that Influence the Adherence of Biovitroceramic Coatings on Titanium
Authors: Britchi Iulia Mirela , Olteanu Mircea , Ene Niculae
Published: March 2009

In order to manufacture ceramic coatings on metallic substrates with medical
applicability, a compromise has to be made between adherence, mechanical resistance and
bioactivity. Biovitroceramic layers to satisfy all these requirements are extremely difficulty to
develop. The goal of this contribution is to employ a simple technique like enamelling for making
biocompatible and bioactive coatings with improved mechanical properties and very good
adherence onto metallic substrates made of titanium samples. One important factor for a good
adherence is the value of the thermal expansion coefficient of the ceramic coating to be closed to
that of the metallic substrate. Once this achieved by establishing an adequate ceramic composition,
there remain other factors that contribute to a good adherence such as metallic surface pretreatment.
The surface was processed by Al2O3 powder (125 'm) blasting, degreased with acetone
in an ultrasonic device and immersion in phosphoric acid. The (Na2O-K2O-Li2O-CaO-MgO-SiO2-
B2O3-TiO2-P2O5) biovitroceramic coating – titanium interface was examined by means of optical
microscopy and electronic microscopy. The coating adherence to the metallic substrate was
evaluated qualitatively by Vickers microhardness tests at the interface.
Finite Element Analysis of Thermal Stresses in Circumferential Cast Clasps of Removable Partial Dentures
Authors: Sandu Liliana , Faur Nicolae , Bortun Cristina , Porojan Sorin
Published: March 2009

Several studies evaluated the removable partial dentures by the finite element analysis,
but none of them evaluated thermal stresses. The purpose of the study was to explore the influence
of thermal oral changes induced by hot/cold liquids and food on the circumferential cast clasps of
removable partial dentures. A 3-dimensional finite element method was used to explore the
temperature distribution, thermal stress and the influence of thermal changes on stresses and
displacements of circumferential clasps during functions. Thermal variations induce stresses in
dental clasps, high temperatures having a more aggressive effect than lower one. Cold liquids and
food induce high stresses in the retentive clasp arms while hot ones in the occlusal rests of the
clasps and for the back action clasp also in the minor connector. The study suggests the importance
of consFigureidering thermal variations for stress analyses of the cast clasps.
XRD Investigation of Impact Pattern on Ball Bearing Steel Samples
Authors: Andrei Gabriel , Gheorghies Constatin , Andrei Laurenţia , Birsan Iulian Gabriel
Published: March 2009

The main purpose of this work is to reveal the structural changes occured after the impact
test on ball bearing steel samples, relative to their ferrite-pearlite phase. The XRD analysis has been
used to investigate the level of first and second order internal stresses, the dimensions of mosaic
blocks as well as the dislocation density in crystal lattice. The influence of the impact velocity,
material hardness and surface roughness on fine structural parameters, mentioned above, is also
analysed. On the basis of structural changes it is possible to control the material response during the
impact loading.
NiAl Oxidation and Corrosion Resistant Coatings Obtained by Thermal Spraying
Authors: Orban Radu L. , Lucaci Mariana , Rosso Mario , Grande Marco Actis
Published: March 2009

There are investigated the possibilities to avoid or at least to reduce the Al2O3 scales
formation on NiAl powder particles at its plasma spray deposition on steel substrates. The optimum
processing parameters and the necessity to surround the plasma jet by an inert gas have been
established. In appropriate processing conditions, the obtained coating layer is formed by flattened
particles, welded together and to the substrate, proving their melting during spraying. It is dense and
adherent, consisting of NiAl with only small Al2O3 inclusions, proving the NiAl stability preserving
without decomposition or a notable oxidation, as premises of its desired functionality achievement.
High Potency Late Inoculation of Grey Cast Iron
Authors: Chisamera Mihai , Riposan Iulian , Stan Stelian , Albu C.B. , Brezeanu C. , Naro Rod
Published: March 2009

Inoculation comparisons were made between Calcium-bearing FeSi75 and a new
complex alloy tablet (CAT) inoculant to compare their effects on late inoculation. Thermal analysis
was used to study the solidification behavior and how FeSi75 and the CAT inoculants affect
graphite nucleation. Quick-cup addition rates for FeSi75 ranged from 0.1% to 0.3% while the CAT,
was added in much smaller amounts, 0.01 to 0.03%. Thermal analysis of the base low sulphur iron
(0.02 %S) was characterized by excessive eutectic undercooling. It was found that an addition of
0.03% of the CAT had inoculation efficiency comparable to 0.2% to 0.3% Ca-FeSi75 in reducing
the level of undercooling, recalescence and the maximum recalescence rate. A greater negative peak
of the first derivative at the end of solidification process, that would minimize micro-shrinkage
tendencies, was also obtained.
A Vision of Wire Rod Rolling Technology for the Twenty First Century
Authors: Lundberg Sven Erik
Published: March 2009

During the last 60 years, tremendous developments have been in wire rod rolling. Finish
rolling speeds in the order of 100 – 140 m/s are common and on line wire rod cooling practices, has
made it possible to treat the wire rod directly in line in the mill instead of separate off line
operations. New procedures for roll setting have been developed to cut the downtime in the mill, by
presetting the stands in separate workshops an supply the entire rolling line with fast changing
equipment. Much of the efforts have been directed to improve the productivity and the wire rod
quality, but also to improve the working environment. In the 21:st century, the main challenge will
be the global energy saving and environment protection, which in turn will require new trends in
wire rod rolling and wire rod rolling research. The in line treatment will be applied for more steel
grades, but the important savings must be solved at the interface between the
steelmaking/continuous casting and the wire rod rolling. Hot charging as well as warm rolling will
be employed in order to save energy. Their knowledge of the rolling processes will be improved by
means of new methods for plastic analysis. New processes must be introduced, where the
requirements from the rolling mills will direct the development. These are including casting of
smaller billet sections, in order to minimize the mechanical work, and thus the consumption of
electrical energy for conversion of the billets to wire rod. By the development of these technologies
not only energy will be saved. Better wire rod surfaces can be obtained and the investment cost for
new rolling mills will decrease. However the development of new knowledge and new processes
requires funding on a level that is hard to expect, especially from the funding system which exists at
present.
Fabrication of Metal Powders Having Spherical Shape Particles (an Overview)
Authors: Spârchez Zeno
Published: March 2009

On the basis of a graphical classification devised by the author, the paper presents a brief
analysis of the principal methods and procedures used for elaborating powders having spherical
particles. The than discussion is focused on emphasizing and classifying the influence factors
related to the material, processing method and equipment, which enables the obtaining of spherical
particles. In the case of those methods which lead to both spherical and non-spherical particles,
additional operations are needed the separation of the non-spherical particles, possibly followed by
their conversion to spherical particles in a thermal field.
A New Method of Reducing Shock between Press Head and Press Disk in High Speed Lapping
Authors: Yang J.D. , Tian C.L. , Yang H.Y. , Hao Z.Q. , Zhu Z.H.
Published: March 2009

Considering the shock between the press head and press disk in high speed lapping is more
serious, this paper proposes a new method to reduce this shock. By this method a hole is machined for
air passing on the press head axis. The topper of the hole is connecting with a pressure air resource.
Thus an air cushion between the press head bottom and press disk on the workpiece is produced. With
the distance between them reducing gradually, the damping of air cushion on the press head increases
gradually. This makes speed of the press head approaching the workpiece decrease gradually and until
reach zero. The pressure of the press head acts on the press disk increases gradually from zero to
working pressure, which can reduce the shock between the press head and workpiece effectively,
prevent weak workpiece from destroying in lapping and improve machining accuracy and quality.
This method possess the advantages of easy to carry out, simple to operate and convenient to apply.
Precision Grinding of High Chromium Steels Using Metal Bonded CBN Wheel
Authors: Hasuda Y. , Kato T. , Meguriya R. , Suzuki Y. , Kinebuchi S. , Furusawa T. , Ohashi T.
Published: March 2009

In this study, the influences of carbides and alloy additives on ground surface
characteristics of several high Chromium (Cr) steels and abrasive grains of working surface were
discussed. In the grinding using metal bonded CBN wheel, almost constant values in ground
surface roughness and high grinding ratio were shown. 5% Cr steel with Vanadium, 8% Cr steel
and 10% Cr steel showed a rougher surface than Cr steels with 3%, 4% and 5% due to the carbide
inclusion. The grinding ratio of 5%Cr steel could be raised considerably by adding sulfur to it.
Study on the Behavior of the Cast-Iron Bonded Grinding Wheel to Machining Properties of Hard and Brittle Materials
Authors: Ma S.L. , Li Wei , Zhu Cong Rong , Zhang J. , Ye H.C.
Published: March 2009

Tungsten carbide which is a hard and brittle material was ground by cast-iron bonded diamond wheel with ELID (Electrolytic In-Process Dressing) technique, for the purpose of getting high efficiency, super-precision machining. Three kinds of cast-iron bonded diamond wheels with different grain size were adopted to get different grinding efficiency and surface quality of workpieces. The grinding properties of cast-iron bonded grinding wheels with different grain size and the ground surface quality of tungsten carbide are discussed in this paper. The experiment results indicate that, under the same feeding amount, the grinding efficiency of the wheel with bigger grain size is higher, and it could make the dimension accuracy of the workpiece controllable, but the wheel with smaller grain size could get better ground surface quality. The two grinding phases are decided by the ratio between the size of abrasive grain and the thickness of the oxide layer on the grinding wheel.
Prediction of Surface Roughness Using Regression and ANN Models in High-Speed Finish Milling Operation
Authors: Pan Yong Zhi , Ai Xing , Zhao Jun , Li G.Y.
Published: March 2009

In this paper, multi-linear regression and artificial neural network (ANN) models have been
developed to predict surface roughness in high-speed milling of 7050-T7451 aluminum alloy. Surface
roughness is taken as the response variable, while cutting speed, feed per tooth, radial depth of cut and
slenderness ratio are taken as independent input parameters. An orthogonal experiment design is
developed to conduct experiments. The measured values of surface roughness are used to find the
regression coefficients and train the neural network for prediction of surface roughness. Predicted
values of surface roughness by both models are compared with the measured values.
Investigation on the Machining of Thick Diamond Films by EDM Together with Mechanical Polishing
Authors: Chen Rong Fa , Zuo Dun Wen , Sun Yu Li , Lu Wen Zhuang , Li D.S. , Wang M.
Published: March 2009

Although research on various diamond polishing techniques has been carried for years, some issues still need to be examined in order to facilitate application on large areas in a cost-efficient manner. A compositive technique for machining efficiently thick diamond films prepared by DC plasma arc jet is reported in the present paper. A two-stage polishing was applied on thick polycrystalline diamond films, by employing first electro-discharge machining (EDM) for rough polishing and subsequently mechanical polishing for finishing operations. Experimental results obtained clearly indicate the applicability of the proposed two-stage technique for fabricating transparent diamond films that can be used for the production of X-ray windows. Appropriate etching with EDM is an effective pretreatment method for enhancing the efficiency of rough polishing process in mechanical polishing of thick diamond film. The machined surfaces of diamond films are studied by Scanning Electron Microscope (SEM) and Raman Scattering Spectroscopy (Raman).
Precision Grinding and Slicing of Glass-Like-Carbon
Authors: Hasuda Y. , Suzuki Y. , Kato T. , Meguriya R. , Furusawa T. , Ohashi T.
Published: March 2009

High density and isotropic poreless structure of Glass-like-carbon makes it practically
used for fuel cells of space-shuttles and hard disk substrate etc. Glass-like-carbon is one of the new
materials which attract attention, but it is so hard and brittle that precise machining of this material
is difficult. Surface grinding and slicing were performed to collect the fundamental data of precise
machining. The main results obtained in this study are as follows. (1) The transition from brittle
mode to ductile mode in surface grinding occurs at a grain mesh size between #5000 and #3000.
(2) The maximum grain depth of cut ‘dg’ necessary for ductile mode grinding is 0.021-0.006 mm or
less. (3) When it is being sliced, the kerf width of the #1000 grinding wheel becomes wider than
that of the #2000 grinding wheel because of the fact that the material removal capability of the
#1000 grinding wheel is bigger than that of the #2000 grinding wheel. (4) It is extremely effective
to use the fine grinding wheel, since the Young's modulus of glass-like-carbon is considerably low
and eventually causes compression transformation,.
Finite Element Modeling of Burr Formation in Metal Cutting with a Backup Material
Authors: Deng Wen Jun , Xia Wei , Lu Long Sheng , Tang Yong
Published: March 2009

2D finite element model with the same material for backup to minimize the burr size was developed to investigate mechanism of burr formation and burr minimization. The flowstress of the workpiece and backup material are taken as a function of strain, strain-rate and temperature. Temperature-dependent material properties are also considered. The Cockroft-Latham damage criterion has been adopted to simulate ductile fracture. The crack initiation and propagation is simulated by deleting the mesh element. The result shows putting a backup material behind the edge of the workpiece is an effective way to minimize the burr size. The effects of cutting condition, temperature and different backup material properties on the burr formation and burr size can be investigated using the developed finite element model. This model could be useful in the search for optimal tool geometry and cutting condition for burr minimization and for the modeling of a burr formation mechanism.
The Standardization for the Edge Quality of the Precise Machining Products
Authors: Kato Y. , Ohmri K. , Hatano E. , Takazawa K.
Published: March 2009

BEST-JAPAN has being proceeded the standardization of the Edge Quality. Already, we
announced this one at international conference on “Precision Surface Finishing and Deburring” at
San Francisco and St. Petersburg. This paper describes the discussion of the Edge Quality and
Indication & Evaluation Methods of The Edge Quality.
Experimental Study on Surface Finishing Performances in Quick-Point Grinding
Authors: Xiu Shi Chao , Li Chang He , Cai Guang Qi
Published: March 2009

There are lower grinding force and temperature in quick-point grinding process because
of the higher grinding speed and the less depth of cut, especially the point contact between the
grinding wheel and the workpiece due to the point grinding angles. Thus it can achieve better
surface finishing process in grinding cylindrical surface. Since the point grinding model is different
from the conventional cylindrical grinding in theory, the surface roughness is in relation to the
point-grinding angles greatly besides the grain granularity, depth of cut, grinding speed and axial
feeding rate like the conventional cylindrical grinding process. Based on the theoretical studies on
the surface roughness in the process, the surface finishing experiments and measures at the various
grinding parameters were performed. The experimental results show that the process parameters,
such as point-grinding angles, depth of cut, grinding speed and axial feeding rate, must be
controlled reasonably for the higher surface finishing demand in quick-point grinding process.
Long Term Degradation Behavior of Impact Properties of Hydraulic Forged Superalloy 718 during Exposure at High Temperature
Authors: Song Young Seok , Lee M.R. , Kim Jeong Tae
Published: March 2009

To check long term degradation behavior of hydraulic forged superalloy 718 during
exposure at high temperature, an Alloy 718 ingot with a diameter of 400mm was manufactured by
the vacuum melting process, VIM followed by VAR. The ingot was broken down for uniform
microstructure and mechanical properties by a controlled cogging process using a hydraulic press.
To investigate long term degradation behavior of impact properties and hardness, the specimens
were exposed to 600oC, 650oC and 700oC for holding times up to 12,112 hours. Impact energy
absorption tests were performed at room temperature. The fractured area and the microstructure of
the impact specimens were observed by OEM and SEM and Brinell hardness tests were also
performed. The changes of impact energy and hardness are remarkably different for each
temperature condition. The results suggest that the impact properties and hardness of Ni based
superalloy 718 is strongly related to temperature and time during high temperature exposure.
High-Resolution Dynamic Analysis of the Phase Transformation in Ge2Sb2Te5 Alloy
Authors: Song Se Ahn , Zhang Wei , Jeong Hong Sik , Kim Jin Gyu , Kim Youn Joong
Published: March 2009

Phase transformation and crystal growth behavior of Ge2Sb2Te5 were investigated
systematically by means of in situ heating (from room temperature to 500 oC) of amorphous
Ge2Sb2Te5 alloy in a high voltage electron microscope with real-time monitoring. Large-scale
crystallization occurred to amorphous Ge2Sb2Te5 around 200 oC. Large crystal growth developed on
heating from 200 oC to 400 oC, and single crystalline grains grew up to 150 nm. Eventually the onset
of partial melting of thin Ge2Sb2Te5 foil was at 500 oC and liquid Ge2Sb2Te5 was observed for the first
time by high-resolution transmission electron microscopy. Hexagonal Ge2Sb2Te5 phase remains after
a subsequent cooling.
Development of a Fretting Wear Evaluation Method in the Nuclear Fuel Fretting by Using a Wear Scar Shape
Authors: Lee Young Ho , Kim Hyung Kyu
Published: March 2009

In order to evaluate the effects of a variation of a supporting springs' shape on the wear
behavior of a nuclear fuel rod, sliding wear tests have been performed in room temperature air and
water. The objective of the tests is to quantitatively evaluate the relationship between a worn area and
a wear volume, and the formation behavior of a worn area with a variation of the slip amplitudes,
applied normal loads and supporting spring shapes. The results indicated that the variation behavior
of the volume and the wear scar size was influenced by the contact shape between the springs and the
fuel rods. Also, it was found to be possible to evaluate a critical ratio (Tc) for each spring shape and
test condition when the T was defined as the ratio of an applied normal load (Ln) to a wear scar size
(At). Below this Tc, the wear volume was rapidly increased and the Tc was determined by a variation
of the At under the same applied normal load condition. This result enables us to evaluate a wear
resistant spring shape by using an analysis of a wear scar after wear tests have been completed. Based
on the above results, the relationship between At and a worn area (Aw), a wear mechanism and an
evaluation method for a wear resistance were discussed.
Mechanical Properties of Railway Wheel for Standard Reinforcement
Authors: Kwon Seok Jin , Lee Dong Hyung , Seo Jung Won , Hur Hyun Mu
Published: March 2009

For the high quality of wheel, the railway wheel has standardized such as UIC, KS, and
JIS code but the chemical composition, the mechanical property and the hardness is merely requested.
Although the standard of railway wheel has sustained, the damages of railway wheel have been
occurred in service running. Because of wheel damage with spalling, shelling and thermal crack, the
maintenance cost for the railway wheel has increased. In order to reduce wheel damage, it is necessary
to reinforce the standard of railway wheel. In present study, the fracture mechanics characteristics of
railway wheel such as threshold stress intensive factor, fracture toughness and impact energy
depended on temperature have tested. The result shows that the standard of railway wheel has to
supplement fracture toughness and impact energy depended on low temperature in order to reduce the
wheel damage.
Transmission Electron Microscopy (TEM) Observations of Phase-Separations of Gamma-Prime Precipitates in Ni-Al-Fe and Ni-Si-Fe Ternary Alloys
Authors: Senga M. , Kumagai H. , Moritani Tomokazu , Doi Minoru
Published: March 2009

In Ni-13.0at%Si-3.1at%Fe alloy, when γ/γ’ two-phase microstructure formed at 1123 K is
isothermally heated at 923 K which is lower than the temperature where the initial γ/γ’ microstructure
forms, the phase-separation of γ/γ’ precipitate phase occurs and γ particles newly appear in each
cuboidal γ’ precipitate. While in Ni-10.2at%Al-10.8at%Fe alloy, when γ/γ’ two-phase microstructure
formed at 1023 K is isothermally heated at 1123 K which is higher than the temperature where the
initial γ/γ’ microstructure forms, the phase-separation of γ’ precipitate phase takes place and γ
particles newly appear in each cuboidal γ’ precipitate. Such appearance of new γ particles in γ’
precipitates can be explained by the difference in the volume fraction of γ phase that should exist in
the γ/γ’ two-phase system depending on the heating temperature.
First Principles Calculations of Thermodynamic Quantities and Phase Diagrams of High Temperature BCC Ta-W and Mo-Ta Alloys
Authors: Masuda-Jindo Kinichi , Van Hung Vu , Turchi P.E.A.
Published: March 2009

The thermodynamic properties of high temperature metals and alloys are studied using
the statistical moment method, going beyond the quasi-harmonic approximations. Including the
power moments of the atomic displacements up to the fourth order, the Helmholtz free energies and
the related thermodynamic quantities are derived explicitly in closed analytic forms. The
configurational entropy term is taken into account by using the tetrahedron cluster approximation of
the cluster variation method (CVM). The energetics of the binary (Ta-W and Mo-Ta) alloys are
treated within the framework of the first-principles TB-LMTO (tight-binding linear muffin tin
orbital) method coupled to CPA (coherent potential approximation) and GPM (generalized
perturbation method). The equilibrium phase diagrams are calculated for the refractory Ta-W and
Mo-Ta bcc alloys.
Fabrication of Carbon Nanotubes Reinforced Polyethylene Fibers by Melt Spinning: Process Optimization and Mechanical Strength Characterization
Authors: Sulong Abu Bakar , Park Joo Hyuk
Published: March 2009

Optimization process for fabrication of Carbon nanotubes (CNTs) reinforced
Polyethylene (PE) fibers by melt spinning has been studied. Three main melt spinning process
parameters (spinning temperature, spinning distance, and spinning revolution) are evaluated by the
Taguchi’s method to decrease the diameter of fibers. Decreasing diameter of fibers is greater
influenced by spinning revolution and distance than spinning temperature. Moreover, fibers in
diameter 22 μm (average) are successfully fabricated. Mechanical properties are measured by
tensile test machine based on ASTM D3822 for single fibers which were fabricated at optimized
melt spinning process parameters. Pure PE polymer fibers and chemically surface modified CNTs
reinforced fibers also fabricated for comparison purpose. The interfacial bonding of CNTs with PE
matrix is investigated through fracture surfaces image analysis by Scanning Electron Microscopy
(SEM).
Numerical Simulations for Uniaxial Ratcheting of SiCP/6061Al Composites Concerning Particulate Arrangement
Authors: Guo Su Juan , Kang Guo Zheng , Dong Cheng
Published: March 2009

Based on three dimensional cubic unit cell models containing several particulates with
certain particulate arrangements, the monotonic tensile and uniaxial ratcheting behaviors of
particulate reinforced metal matrix composites (i.e., T6-treated SiCP/6061Al composites) were
numerically simulated by using elastic-plastic finite element code ABAQUS with help of newly
developed user material subroutine (UMAT). In the simulations, the effects of different particulate
arrangements inside the unit cell models on the monotonic tensile and ratcheting behaviors of the
composites were discussed. It is shown that the effect of particulate arrangement on the ratcheting
of the composite depends on the arranged modes and the number of particulates contained in the
model, and the interaction between particulates can be represented reasonably by the cubic unit cell
model with a suitable distribution of multi-particulates.
Warm Forging Characteristics of AZ31 Alloy
Authors: Kwon Yong Nam , Lee Young Seon , Lee Jung Hwan
Published: March 2009

Industrial application of magnesium alloys has increased significantly recently. However,
wrought magnesium alloys still have a lot of technical challenges to be solved for more applications.
First of all, low formability of wrought alloys should be improved by optimizing the processing
variables. In the present study, the effect of process variables such as forging temperature and
forging speed were investigated to forgeability of magnesium alloy. To understand the effect of
process variables more specifically, both numerical and experimental works have been carried out
on the model which contains upsetting geometry. Forgeability of AZ31 alloy was found to depend
more on the forging speed rather than temperature. Forged sample showed a significant activity of
twinning, which was found to be closely related with flow uniformity.
Low-Pressure Preheating Combustion Synthesis of Silicon Nitride
Authors: Zhang Ke , Bai Ling , Shen Wei Ping , Ge Chang Chun
Published: March 2009

Silicon nitride was prepared by means of low-pressure preheating combustion synthesis in
this paper. When N2 pressure is less than or equal to 2MPa, the lowest preheating temperature is about
653K, reactant could make silicon nitride by combustion synthesis. The additive of ammonium
fluoride and ammonium chloride, as the reactive diluent, and Si react and make some useful
intermediate products to α -Si3N4 after thermal decomposition. The reactive diluent content must be
appropriate. At the same time, with the improvement of Si3N4, as the inert diluent, content in reactant,
the adiabatic flame temperature of system would reduce, and combustion reaction rate of Si also
drops, so it is propitious to make high level of α -Si3N4.
Improved Density Distribution in Powder Metallurgy Parts with Filtering Methods
Authors: Kim Man Sig
Published: March 2009

Powder Metallurgy (P/M) is mainly composed of four steps: powder feeding, compaction, ejection,
and sintering. A feedshoe moves forward and backward over the die cavity to fill it with metal
powders. Possible problem in this stage is the uneven supply of powder on the horizontal direction.
It can cause tool breakage due to uneven density distribution. Unevenly-distributed powder also
causes internal cracks during compaction or warpage during sintering. Another problem during
powder feeding is the inclusion of air with powder. This changes the overall density of the part.
Powder feeding mechanism is very important, because it is the first step in the process. If there is
imperfection during powder feeding, the final part ends up with a bad part no matter how perfect the
rest of the processes are. This paper describes the development of an advanced powder feeding
mechanism, which allows well-distributed amount of powder to be delivered to the die cavity.
The Improvement of Permeability and Strength in Soft Magnetic Composites Motor Core Using Spark Plasma Sintering Process
Authors: Cha Hyun Rok , Yun Cheol Ho , Son Hyeon Taek , Cho Jae Ik
Published: March 2009

The practical uses of soft magnetic composite(SMC) for an electrical motor is presented in
this paper. SMC allows obtaining improved stator and core shapes as well as totally new design
concepts such as claw pole motor. However, a major disadvantage of soft magnetic composites was
their weak strength. In this study, spark plasma sintering (SPS) was utilized to improve the strength
of SMC. Advantages of the SPS process over other conventional sintering process are the faster
heating and cooling rates ensured and higher pressure applied during the sintering procedure. This
allows obtaining high strength products in short periods of time to meet with industrial application
without insulation destruction. This paper introduces the development of high strength soft magnetic
composite motor core and examples of practical application for industries. The result showed that the
SPS process increased the fracture strength, about 1.3 to 1.7 times, of SMC compare to the
conventional compaction. Also we derive method to reduce the iron loss in the SPS sintering process
using control forming temperature. As the forming temperature decreased from 500°C to 300°C,
reduction of iron-loss was obtained from 192W/kg to 21W/kg by using SPS sintering process.
Moreover, with increased the SPS sintering process pressure value from 250MPa to 800MPa which is
the conventional compaction condition and decreased forming temperature to 200°C, iron-loss was
measured. The results showed that iron-loss was obtained 11.42W/kg and it was similar value of
conventional compaction results.
Effect of Residual Stress on P Doped Nano-Crystalline Silicon Deposited by HWCVD Films
Authors: Swain Bibhu P.
Published: March 2009

p doped nano-crystal l ine si l icon (nc-Si) were deposi ted by hot wire chemical
vapour deposi t ion (HWCVD) using SiH4 , H2 and B2H6 precursors. nc-Si was
characterized by XRD, Raman and residual st ress. Residual stress of nc-Si were
measure by Sin2ψ vs d method. As deposi ted fi lms show tensi le st ress and
decreases from 2500 MPa to 250 MPa wi th increase of B2H6 f low rate f rom 0.01 to
5 %. Crystal l ine f ract ion of p doped nc-Si decreases f rom 35 to 57% as wi th
increase of B2H6 concent rat ion
Development of Environmental Cell for Gas Reaction of Nano-Size Particles
Authors: Okudera Koya , Hamada Koichi , Suda Takanori , Hashimoto Naoyuki , Ohnuki Somei
Published: March 2009

“Environmental cell” microscopy was applied for surveying gas reaction of hydrides in
magnesium base alloys, which are candidates for hydrogen storage materials in advanced hydrogen
energy systems. In order to clarify the mechanism of hydrogenation process, in-situ experiment has
been carried out by using a 200 kV transmission electron microscope (TEM) equipped with a newly
developed environmental cell, which is capable to 0.1 MPa in the temperature range between R.T. and
200°C. When hydrogen gas reacted with magnesium powders, straightening of surface steps (60~70
nm in height) was observed, indicating that volume expansion occurred. In addition, the formation of
MgH2 was indicated in selected-area-diffraction patterns (SADP). The precise study on this in-situ
experiment, as well as its improvement, will be continued, with using transparent films.
Numerical Simulation of Unidirectional Solidification Process of Turbine Blade Castings
Authors: Yu Jing , Xu Qing Yan , Liu Bai Cheng , Li Jia Rong , Yuan Hai Long
Published: March 2009

A mathematical model for three-dimensional simulation of unidirectional solidification
process and microstructure evolution of Ni-based superalloy investment castings was developed
based on CA-FD method. The modified ray tracing method was used to solve the complicated heat
radiation transfer among the multiple blades and outer space during withdrawal process. Various
withdrawal rates were used. During one process high withdrawal rate was used first before the
platform approached the baffle. Then the low withdrawal rate was used to reduce the temperature
difference of the platform in horizontal section and avoid the defects formed in the corner of the
platform. The experimental cooling curves of different positions in the blades and microstructure
were compared with the simulation results. Both the results showed that the various withdrawal rates
process was effective to reduce the temperature difference of the platform and avoid the formation of
stray grains. This process could be helpful to increase the productivity.
Effect of Orifice Shape in Contour Crafting with Ceramic Material: A Simulation for Extrusion and Deposition Mechanism
Authors: Kwon Hong Kyu , Kim Kwang Soo
Published: March 2009

This paper presents our experimentation and
modeling efforts to study the pattern of material flow in the
extrusion and deposition stages of the Contour Crafting (CC)
process. Specifically, we performed a preliminary finite
element analysis (FEA) of extrusion and deposition
mechanisms with clay as the fabrication material. Using the
FEA simulations, we derived certain basic understandings of
the effect of extrusion orifice geometry on the performance of
CC. We found that a square orifice is most aptly suited, both in terms of delivering the optimal
fusion between layers as well as creating the desired external surface profile. Our experiments
validate these results.