bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Residual Carbon on the Microstructure Evolution during the Sintering of M2 HSS Parts Shaping by Metal Injection Moulding Process
Authors: Herranz Gemma , Levenfeld B. , Várez A.
Published: March 2009

In this present investigation, Metal Injection Moulding (MIM) of M2 High Speed Steel (HSS) parts using a wax-High Density Polyethylene (HDPE) binder is shown. This work is focused on the examination of the sintering densification and microstructure evolution of the parts. The injection molding process of the feedstock has been optimized to obtain high quality green parts. The elimination of organic binder was carried out by thermal debinding under inert atmosphere. In order to keep carbon in the sample that could improve the sintering process, incomplete debinding was performed between 450 and 600 °C. The specimens were sintered at temperatures between 1210 and 1280oC in high vacuum atmosphere, obtaining the 98% of the theoretical density. A homogeneous distribution of fine M6C carbides was obtained as well as V-rich carbides (MX) during sintering which reinforced the HSS and hence increasing the mechanical properties of the parts. In the samples with higher residual carbon content, the sintering window was extended up to 20 degrees and the optimum temperature was lower.
Alumina-Titania Spot Spraying Bead Formation and Characteristics in Atmospheric Plasma Spraying
Authors: Joo Hye Sook , Choi Han Shin , Jo Hyung Ho , Cho Hoon , Kim June Seob , Lee Chang Hee
Published: March 2009

Fine and coarse alumina-titania composite particles were overlaid by allowing the
particles to be deposited for a short time without moving a plasmatron [spot spraying bead]. Both
the deposition efficiency and maximum deposition rate were measured at the different plasma gas
composition. Considering the normalized maximum deposition rate [(maximum deposition
rate)x(deposition efficiency)-1], effects of particle size and plasma gas composition on the particle
segregation within a cross-section of mass flux could be estimated. Also, particle melting state
according to the position within a mass flux at the moment of impact could be also estimated
through the investigations of microstructure and phase composition of the spot spraying bead.
Fabrication of Nano-Sized Titanate Powders by an Ethylene Glycol Solution Route
Authors: Lee Sang Jin , Lee Man Jong , Yoon Young Soo
Published: March 2009

Several titanate powders (Al2TiO5, SrTiO3, etc.) were synthesized by an ethylene glycol solution route. Titanium isopropoxide and nitrate salts were dissolved in stoichiometric proportions in liquid-type ethylene glycol without any precipitation. The parent precursor sols were dried to porous gels, and then the gels were calcined and crystallized. All synthesized titanate powders had stable crystallization behavior at low temperature and high specific surface area after a simple ball-milling process. A three-component PZT (Pb(Zr0.52·Ti0.48)O3) powder was also synthesized successfully by the ethylene glycol method. In this study, the characteristics of the multi-component titanate powders by the ethylene glycol method are examined.
Densification Behavior and Microstructural Development of Nano-Agglomerate Powder during Sintering
Authors: Kang Yun Sung , Cha B.H. , Kang H.G. , Lee Jai Sung
Published: March 2009

Densification behavior of nano-agglomerate powder during pressureless sintering of Fe-Ni nanopowder was investigated in terms of diffusion kinetics and microstructural development. To understand the role of agglomerate boundary for sintering process, densification kinetics of Fe-Ni nano-agglomerate powder with different agglomerate size was investigated. It was found that activation energy for densification process was lower in the small-sized agglomerate powder. The increase in the volume fraction of inter-agglomerate boundary acting as high diffusion path might be responsible for the enhanced diffusion process.
Microstructure Characteristics and Electrical Properties of Sintered (Bi,La)4Ti3O12 Ferroelectric Ceramics
Authors: Yoo H.S. , Son Y.H. , Hong Tae Whan , Ur Soon Chul , Ryu Sung Lim , Kweon Soon Young
Published: March 2009

1mm-thick BLT ceramics were sintered in accordance with a bulk ceramic fabrication
process. All XRD peaks detected in the sintered ceramics were indexed as the Bi-layered perovskite
structure without secondary phases. Density was increased with increasing the sintering temperature
up to 1050°C and the maximum value was about 98% of the theoretical density. The remanent
polarization (2Pr) value of BLT ceramic sintered at 1050°C was approximately 6.5 μC/cm2 at the
applied voltage of 4.5kV. The calculated electromechanical couping factor (kt) of it was about 5%
and the mechanical quality factor (Qm) was about 2200. From these results, a BLT ceramic target
for plused laser deposition (PLD) system was successfully fabricated.
Multi-Scale Virtual Reality of Sintering
Authors: Olevsky Eugene
Published: March 2009

The directions of further developments in the modeling of sintering are pointed out, including multi-scale modeling of sintering, on-line sintering damage criteria, particle agglomeration, sintering with phase transformations. A true multi-scale approach is applied for the development of a new meso-macro methodology for modeling of sintering. The developed macroscopic level computational framework envelopes the mesoscopic simulators. No closed forms of constitutive relationships are assumed for the parameters of the material. When a time-step of the calculations is finished for one macroscopic element, the mesostructures of the next element are restored from the initial state according to the history of loading. The model framework is able to predict the final dimensions of the sintered specimen on a global scale and identify the granular structure in any localized area for prediction of the material properties.
An Investigation on Elongation-Porosity Relation in Sintered 17-4 PH Stainless Steel
Authors: Sung Hwan Jin , Ha Tae Kwon , Ahn Sang Ho , Chang Young Won
Published: March 2009

In the present study, powder injection molding (PIM) process, in which the porosity of
sintered parts can be easily controlled, has been employed to produce specimens with the various
porosities from the initial stage of sintering and to the stage of nearly full density. A series of tensile
tests has been conducted on these specimens at room temperature to elucidate the effect of a wide
range of porosity. The material used in this study was 17-4 PH stainless steel, which is the
precipitation hardenable stainless steel containing 4% of Cu and well known to show high strength
and the high corrosion resistance at the same time. The 17-4 PH stainless steel powders used in this
study were produced by the high-pressure water atomization method. Based on the results of tensile
tests on the specimens with the various porosity, a new approach to predict the elongation of sintered
materials has been carried out and a new framework combining neck growth model and ideal pore
model has been established.
Modification of Low Alloyed Steels by Manganese Additions
Authors: Sicre-Artalejo J. , Campos Mónica , Marcu Teodora , Torralba José M.
Published: March 2009

The efforts to increase the potential PM market [makes necessary to accept new
challenges to develop new products. To address this question, we can consider modifying the pores
system or the material composition and at same time, the cost of the alloying elements and the
compromise between strength, tolerances and cost. The present study examines the sintering
behavior and effect of manganese addition, both mechanically-blended and mechanically alloyed,
on Cr-Mo low alloyed steels to enhance the mechanical properties. Mn sublimation during sintering
results in some specific phenomena to occur which facilitate the sintering of alloying elements with
high oxygen affinity. To benefit from the Mn sublimation effects, small Mn particles must be
homogenously added in order to increase the specific surface available to sublimate. First, the
milling time is optimized to attain a master alloy with 50% of Mn that is diluted in Fe-1.5Cr-0.2Mo
water atomized prealloyed powder by normal mixing. These mixtures were pressed to a green
density of 7.1 g/cm3 and sintered at 1120 °C in 90N2-10H2 atmosphere. The resulting mechanical
properties and the microstructures are discussed considering the high energy stored in the master
alloy which favors the mass transport mechanism during sintering.
Nominally Equivalent Powders for P/M Steels: Analysis of Response to Sintering and Differences at Various C Content
Authors: Bocchini G.F. , Ienco M.G. , Pinasco M.R. , Stagno E. , Baggioli Andrea , Gerosa Riccardo , Rivolta Barbara
Published: March 2009

Globalization enables P/M part makers to choose powders from different sources. Raw
materials produced by a given process and having equal chemical composition are supposed to be
equivalent. The differences in sintering behavior, in industrial equipment, have been investigated on
P/M steels obtained from four diffusion-bonded powders (Fe + Ni + Cu + Mo) on atomized iron
base, at the same alloy contents. Two levels of carbon and two sintering conditions have been
investigated. Dimensional changes, C content, hardness, microhardness pattern, universal hardness,
fractal analysis, pore features, microstructure features, and rupture strength have been compared, to
characterize different raw materials. An index of homogeneity of microstructures, based on a
specific statistical approach, does not agree completely with observed microstructures and pore
feature. The results show that the claimed equivalence is not confirmed by experimental data.
Analyses of microhardness and microstructure distributions seem powerful tools to rate the real
equivalence of so claimed powders. P/M part makers may use the proposed approach to assess
detectable differences on performances among powders that are declared as “true” substitute, so
confirming or contradicting any even not negligible cost difference. The comparison methods here
described and applied can also help powder producers to improve the suitability of their products to
sintering processes.
Stress Corrosion Cracking of Alloys 600, 690, and 800 in a Tetrathionate Solution at 340°C
Authors: Lee Eun Hee , Kim Kyung Mo
Published: March 2009

The stress corrosion cracking (SCC) susceptibility of Alloy 600 MA, Alloy 600 TT, Alloy
800, and Alloy 690 TT were investigated in a deaerated 0.01 M solution of sodium tetrathionate
using reverse u-bend test samples at 340 °C. The results showed that SCC occurred in all alloys,
excluding Alloy 690 TT. The SCC susceptibility of the alloys increased in the following order:
Alloy 690 TT, Alloy 800, Alloy 600 TT, and Alloy 600 MA. The SCC susceptibility decreased with
an increase in the chromium content of the alloys. The results of the deposits and spectra taken from
an energy dispersive X-ray system confirmed the existence of a reduced sulfur causing SCC.
The Effect of Chemical Composition of Sintering Atmosphere on the Structure and Mechanical Properties of PM Manganese Steels with Chromium and Molybdenum Additions
Authors: Sulowski Maciej , Cias Andrzej , Stoytchev Marin , Andreev Tchavdar
Published: March 2009

The effect of chemical composition of the sintering atmosphere on the density, microstructure
and mechanical properties of Fe-3%Mn-(Cr)-(Mo)-0.3%C is described. Pre-alloyed Astaloy
CrM and CrL, ferromanganese and graphite powders were the starting powders. Following the
pressing in rigid dies, compacts (green density approx. 6.8-7.1 g/cm3) were sintered at 1120 and
1250°C in atmospheres with different H2 and N2 content. The dew point of the sintering atmospheres
was below -60°C. Subsequently samples were furnace cooled to room temperature.
Tensile and transverse rupture strengths, elongation, R0.2 yield offset, impact toughness and apparent
surface hardness were examined. Following the mechanical tests, to investigate microstructure
optical microscopy was employed.
As the results show, sintering in nitrogen-rich atmospheres allow to achieve comparable properties
of the specimens with those of the specimens sintered in hydrogen-rich atmosphere. It means
that it is possible to produce sintered Fe-Mn-Cr-Mo-C PM steels in safe and cheaper nitrogen-rich
atmosphere.
A Study of Debinding Behavior and Microstructural Development of Sintered Al-Cu-Sn Alloy
Authors: Kim J.S. , Chang I.T.H. , Falticeanu C. Lucien , Davies G.J. , Jiang Kyle
Published: March 2009

A new approach is explored to achieve sintered aluminium alloy from metallic powder mixtures without compression or adding Mg. In this approach, mixtures of micron-sized aluminium powder (average size of 2.5 μm) and nano-sized alloying elemental powder of Cu and Sn (less than of 70nm), at appropriate proportions to compositions of Al-6wt%Cu, Al-6wt%Cu-3wt%Sn with and without adhesive binder were prepared by magnetic stirring. Then, the powder mixture was poured into a crucible and heat treated at a temperature of 600°C for 11 hours in inert atmosphere of N2 or Ar. In this paper, we investigate the debinding behavior of loosely packed Al-based powder mixture and the microstructural development and mechanical property sintered parts using a combination of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffractrometry (XRD) and hardness test.
Examination of Calcium-Phosphates Prepared from Eggshell
Authors: Balázsi Csaba , Kövér Zsuzsanna , Horváth Enikõ , Németh Csaba , Kasztovszky Zsolt , Kurunczi Sándor , Wéber Ferenc
Published: March 2009

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Supercapacitor Electrodes Made from Mixture of Amorphous Carbon Nano-Particles and Carbon Black
Authors: Tóth Sara , Füle M. , Veres M. , Pócsik I. , Koós Margit
Published: March 2009

Electrodes for electric double layer supercapacitors (EDLS) usually made of a mixture of
carbon black and binder material. However the binding mixture causes loss in the capacitance
because after the polymerization it obstructs the pores of the carbon black, thus decreasing the
active surface of the capacitor. The capacitance of the electrode can be increased by use of additive
materials, which improve the electrochemical performance of the active material. The effect of
amorphous carbon nano-particles, added to the carbon black on the performance of the
supercapacitor electrodes was studied earlier. It was found that maximal value was obtained for the
composition of 30 wt.% of amorphous carbon nano-particles and 70 wt.% of carbon black [1]. In
this work test-piece supercapacitors (TPS) fabricated with non-aqueous Li-based electrolyte were
studied to analyze the influence of the size of the TPS to the specific capacitance.
These systems were examined by impedance, charge-discharge measurements and cyclic
voltammetry. The working potential window of the capacitor was found to be the 0-1 V region.
Increasing the area of the electrode by using Al foils of larger size resulted in proportional increase
of the capacitance.
Temperature Dependence of Barkhausen Noise Parameters in Carbon Steel
Authors: Harasztosi L. , Daróczi Lajos , Szabó I.A. , Balogh Z. , Beke Dezső L.
Published: March 2009

Temperature dependence of different parameters (the position of the inflexion point and the saturation value on the root main square, RMS, values versus exciting field curves) of the Barkhausen noise is measured in structural steel (S 235 JRG1). It is shown that while the position of the inflexion point remained constant, the RMS value at the inflexion point and saturation value increased with the increasing temperature, T. Most interestingly the field required for saturation decreased with decreasing temperature and had a breakpoint at about 200K. Breakpoints at the same temperature on the critical exponents versus temperature functions (i.e. on the β(T) and α(T) curves, where β and α are the exponents of the probability distributions of peak heights and durations, respectively) were also observed. This temperature can be identified as the ductile-brittle transition temperature.
The Effect of the Compression on the Mechanical Properties of Wood Material
Authors: Kuzsella László , Szabó Imre
Published: March 2009

The wood is one of the most favourable structural material. It appears on all fields of the
ordinary life. It is difficult to say an application where the wood is not used due to its cheap price,
availability and just simply the beauty.
Beside of the wide range of process technologies a new process appeared. This process changes the
properties of the material and brings many new applications to this traditional material. This process
is the compression of the structural wood material.
This publication deals with the effect of the compression on the mechanical properties of two
hardwoods (beech: fagus sylvatica, oak: quercus) by the help of the three-point bending test and the
Charpy impact test.
Mechanical Testing of Tendon
Authors: Molnár László , Solti Enikő , Bojtos Attila , Huba Antal
Published: March 2009

This paper presents an overview about results of mechanical testing of human tendon. We
are dealing with the main function of tendon and touching on typical insurance of tendon and
reconstruction of them. Since the material characteristic of tendon and dynamic models of them are
not known there was made a lot of uniaxial tension test and based on measuring results built up a
linear lumped model for dynamic simulation using the synthesis method. As results we can already
provide quantitative data about mechanical bearing capacity of tendon beside known qualitative
categories. Paper shows a well working fixing technology for tendons during tension test.
Prediction of Fullerene Stability Using Topological Descriptors
Authors: Réti Tamás , Bitay Enikő
Published: March 2009

In recent years, several attempts have been made to characterize the geometric structure
of fullerenes by means of topological shape factors in order to predict their physical properties and
stability. In this paper, we present a simple method to estimate the stability of fullerenes on the
basis of quantitative topological criteria. This approach is based on the concept of the generalized
combinatorial curvatures defined on the set of simple graphs embedded on a closed surface without
boundary (sphere, torus, projective plane, Klein bottle). It is shown that starting with the computed
generalized combinatorial curvatures several novel topological indices can be generated. From
computations performed on a set of C40 and C60 fullerenes, we concluded that the four topological
shape factors tested (Λ(-1), (-1), Λ(1) and (1)) could be successfully used to preselect the most
stable fullerene isomers.
Wear Analysis of Functionally Gradient Composite Materials by FE Modelling of Microhardness Measurements and Wear Tests
Authors: Felhös David , Váradi Karoly , Friedrich Klaus
Published: March 2009

Rollers of three different material structures were examined: rollers consisting of pure EP
resin; homogeneous EP/SiC composite rollers containing 5 vol.% SiC; and EP/SiC composite
rollers with functionally gradient (FG) material structure. Wear tests were performed on the rollers.
The wear tests showed that rollers of gradient structure are the most wear-resistant of all.
Microhardness measurements were performed on the materials of the three different rollers. SEM
images were made of the surface of wear traces. In order to get to know better the effect of SiC
reinforcement particles on the wear mechanism, microhardness measurements were simulated by
3D FE micro-models. The SEM images and the FE models were used to explain the excellent wear
behavior of the tread of rollers with gradient material distribution.
Simulation of 3-Dimensional Cell Population Growth Processes in Polyhedral Cellular Systems
Authors: Réti Tamás , Zsoldos Ibolya
Published: March 2009

In order to simulate the polyhedral grain nucleation in alloys, 3-D cell population growth
processes are studied in space-filling periodic cellular systems. We discussed two different methods
by which space-filling polyhedral cellular systems can be constructed by topological
transformations performed on “stable” 3-D cellular systems. It has been demonstrated that an
infinite sequence of stable periodic space-filling polyhedral systems can be generated by means of a
simple recursion procedure based on a vertex based tetrahedron insertion. On the basis of computed
results it is conjectured that in a 3-D periodic, topologically stable cellular system the minimum
value of the average face number 〈f〉 of polyhedral cells is larger than eight (i.e. 〈f〉 > 8). The
outlined algorithms (which are based on cell decomposition and/or cell nucleation) provide a new
perspective to simulate grain population growth processes in materials with polyhedral
microstructure.
Evaluation of Steel Hardenability by JM®-Test
Authors: Smoljan B. , Iljkic Dario , Tomasic N. , Felde Imre , Totten G.E. , Réti Tamás
Published: March 2009

The modified Jominy-test was designed for prediction of hardenability of high-hardenability
tool steels and possibility of application of modified Jominy-test in computer simulation of quenching
of high-hardenability tool steels has been investigated. Because of high hardenability there are limits in
application of original Jominy-specimen in simulation of quenching of steels. The performance of
investigated modified Jominy-test in simulation of quenching of high-hardenability tool steels was
estimated by comparison of cooling curves of modified Jominy-specimen (JM®-specimen) and
cylindrical specimen. The influence of dimension of JM®-specimen on cooling curves has been
investigated. The time of cooling, t8/5 relevant for results of quenching was predicted. Modified
Jominy-test can be applied in simulation of quenching of steel with higher hardenability rather than
original Jominy-test.
The State of Differently Heat-Treated 12% Ni Maraging Steel after Laser Remelting
Authors: Grum Janez , Slabe Janez Marko
Published: March 2009

The paper describes the results obtained in an investigation of laser remelting of
specimens made of 12% Ni maraging steel suitable for the manufacture of highly thermomechanically
loaded machine parts or tool parts. The aim of the investigation was to establish the
state of differently heat treated maraging steel after a laser repair processes including melting of the
material. An analysis of the specimens with an optical microscope after laser remelting showed,
regardless of the initial condition, a cellular-dendritic microstructure in the remelted track. In the
heat-affected zone surrounding the laser-remelted track the microstructure varied considerably also
regardless of the initial condition. A microstructure analysis supported by microhardness
measurements made it possible to define several microstructural zones or sub-zones in the heataffected
zone. The measurement of residual stresses using the relaxation hole-drilling method close
to the laser-remelted track was used to study the influence of the initial material state on the residual
stresses after laser remelting.
Microstructure and Abrasive Wear Studies of Laser Clad Al-Si/SiC Composite Coatings
Authors: Anandkumar R. , Colaço Rogerio , Ocelík Václav , de Hosson Jeff T.M. , Vilar Rui
Published: March 2009

Surface coatings of Al-Si/SiC metal-matrix composites were deposited on Al-7 wt. % Si
alloy substrates by laser cladding. The microstructure of the coatings was characterized by optical
microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The microstructure
of the coating material is profoundly influenced by the processing parameters used, in particular by
the particle injection velocity and by the specific energy. When the injection velocity is low or
specific energy is high excessive dissolution of SiC in the melt pool occurs. The microstructure of
the coatings presents partially dissolved SiC particles, and considerable proportions of Al4SiC4
plates and faceted Si equiaxed crystals dispersed in a α-Al+Si eutectic matrix. On the contrary for
high injection velocity or low specific energy dissolution of SiC is very limited and the
microstructure of the coatings consists essentially of undissolved SiC particles in a matrix
consisting of primary α-Al dendrites and α-Al+Si eutectic. Abrasive wear tests were performed on
the coatings using a ball cratering device and a 35 wt. % suspension of 4.25 μm average diameter
SiC particles in water as abrasive. Coatings prepared with a high specific energy present an average
hardness of 248 HV and an average abrasive wear rate of 17.4x10-5 mm3/m. Coatings deposited
with a low specific energy exhibit an average hardness of 117 HV and an average abrasive wear
rate of 4.3 x10-5 mm3/m.
Grain Refinement of Metal Surface Using Hot Shot Peening
Authors: Harada Yasunori , Fukaura Kenzo , Tsuchida Noriyuki
Published: March 2009

In this study, the grain refinement near the surface of metal workpiece using hot shot
peening was investigated to improve the surface properties of the workpiece. In this process, the
grains were refined due to plastic deformation generated by the collision of a lot of shots under hot
working conditions. A model experiment using two shots was carried out to examine the effects of
the amount of deformation, the processing temperature and the time interval of the collision on grain
size. In the experiment, the workpieces were stainless steel SUS304 and commercially pure copper.
It was found that the global surface layer successfully attained to the fine grains by means of hot shot
peening.
Adhesion Study of Cold-Sprayed CoNiCrAlY-Mo Coating of Inconel 625 Using the Laser Shock Adhesion Test (LASAT)
Authors: Ichikawa Y. , Ogawa Kazuhiro , Nivard M. , Berthe L. , Boustie M. , Ducos M. , Barradas Sophie , Jeandin Michel
Published: March 2009

MCrAlY-typed coatings are conventional for applications to land-based turbines against hightemperature
oxidation and corrosion. However, improvements are still currently expected from
innovations in the coating process and/or in the selection of the starting materials. Both types of
innovations were studied in the present work. The former consisted in cold spray as a substitute
for plasma spray which is conventionally used as the coating process. The latter consisted in
developing mechanically-alloyed powders to be suitable for the targeted application especially.
In this study, coating-substrate adhesion was considered as the justice of the peace to assess
improvements from these innovations. This was determined using the LAser Shock Adhesion
Test, namely LASAT, which was recently developed as innovative adhesion testing of thermal
spray coatings.
Among the main results, mechanical alloying was shown to be satisfactory to result in an
homogeneous powder from the mixing of CoNiCrAlY with Mo. This powder could be coldsprayed,
all the more easily because of a fine grain size. Results were compared with those
obtained from conventional commercial pre-alloyed powders. As a general result, it was shown
that cold spray could lead to highly-dense and high-adhesion MCrAlY-typed coatings onto
Inconel 625 even though the process is usually claimed to be convenient for high-ductility
materials such as copper. Incidentally, LASAT was confirmed to be a flexible and powerful
testing tool to study adhesion; which resulted in the ranking of the various types of coatings
involved in the work. Results are discussed in the light of an experimental simulation of the
impinging of cold-sprayed particles using so-called “laser flier impact experiments”. In this
development of this simulation approach to cold spray, the flier was made of a 50μm-thick disc
machined from HIP’ed CoNiCrAlY.
Fabrication Routes of Microsized Electrochemical Biosensors Based on Single-Walled Carbon Nanotubes
Authors: Valentini Federica , Orlanducci Silvia , Terranova M.L. , Palleschi Giuseppe
Published: March 2009

In this work two different synthesis processes for Single-Wall Carbon Nanotubes
deposition (such as the Hot Filament-Chemical Vapor Deposition, HF-CVD, and the electrophoretic
deposition, EPD) on microwire surfaces, were described. Then, the morphological and structural
characterization of SWNT-modified microwires were performed by Scanning Electron Microscopy
(FE-SEM) and Raman Spectroscopy, respectively. Finally, the nanostrcutured microelectrodes were
electrochemically characterized using NADH, NAD+, epinephrine, and ascorbic acid (AA), useful
biological molecules to develop electrochemical sensors and biosensors.
Modelling of Nitrogen Deposition Pressure Effect on Grain Size Development and Mechanical Properties of Nanocrystalline Ternary Nitride Coatings
Authors: Wuhrer Richard , Yeung Wing Yiu
Published: March 2009

Development of complex ternary nitride coatings has attracted significant industrial interest
in recent years. In deposition of complex ternary nitride coatings, the nitrogen deposition pressure
plays an important role in structural evolution of the coatings leading to development of different
mechanical properties. This paper summaries some successful analyses by the authors on the
relationships amongst the deposition rate, grain size and hardness of the coatings against the nitrogen
deposition pressure. It has been established that as the nitrogen pressure decreases, the deposition rate
of the coatings increases and the grain size decreases. Hardness of the coatings increases due to the
development of a refined and densified coating structure. Taking into account of the reaction kinetics
at the targets, the interactions of the sputtered atoms occurred in their transfer to the substrate, the
reaction kinetics at the substrate, the target material characteristics and the geometric arrangement of
the sputter magnetron configuration, modelling to the relationships of deposition rate with nitrogen
deposition pressure, grain size with deposition rate and hardness with grain size have been
successfully established in this study. A limiting grain size of the coatings has also been identified in
the grain refinement process.
Characteristics of Gallium Oxide Nanowires Synthesized by the Metalorganic Chemical Vapor Deposition
Authors: Kim Hyoun Woo , Shim S.H.
Published: March 2009

We have synthesized the high-density Ga2O3 nanowires on gold (Au)-coated silicon
substrates using metalorganic chemical vapor deposition. The nanowires exhibited one-dimensional
structures having circular cross sections with diameters in the range of 30-200 nm. The energy
dispersive x-ray spectroscopy revealed that the nanowires contained elements of Ga and O, without
Au-related impurities. X-ray diffraction analysis and high-resolution transmission electron
microscopy showed that the Ga2O3 nanowires were crystalline.
Prediction of Softening of High Speed Steel with Surface Nitriding for Hot Forging
Authors: Minami Akihiro , Marumo Yasuo , Saiki Hiroyuki
Published: March 2009

A model hot forging test was carried out using tools of matrix high-speed steel. Dynamic
thermal loads were applied to tools subjected to ion nitriding on the surface layer of the tool, and the
conditions of deterioration and thermal softening were examined by measuring Vickers hardness in
the vicinity of the tool surface after the thermal load test. In addition, static tempering softening tests
were carried out, and thermal softening equations are obtained using tempering parameter on the basis
of the obtained master tempering curves. When the thermal load was applied under the same
conditions to nitrided and heat-treated tools, the degree of surface deterioration and thermal softening
was small for nitrided tools. Equations of softening for two cases, i.e., specimen subjected only to
heat treatment and specimen subjected to both heat treatment and nitriding, were expressed using
tempering parameter.
Strength and Fracture of Aluminium Alloys
Authors: Kobayashi Toshiro , Toda Hiroyuki
Published: March 2009

Synchrotron X-ray microtomography has been utilized for the 3D characterisation of
microstructure of aluminium foams. A combination of phase contrast imaging technique and several
application techniques, such as local area tomography, microstructural gauging and in-situ
observation, has enabled the assessment of microstructural effects on compressive deformation
behaviours. It has been clarified that ductile buckling of a cell wall occurs regardless of any of the
above microstructural factors in the case of a pure aluminium foam, while rather brittle fracture of a
cell wall is induced by the existence of coarse micro-pores independently of the intermetallic particles
and the grain boundary in the case of Al-Zn-Mg alloy foams. When cooling rate during foaming is
high, however, lower energy absorption might be attributable to the significant amount of residual
foaming agent particle and its inhomogeneous distribution. These tendencies are also confirmed by
3D strain mapping by tracking internal microstructural features.
Solid - Phase Synthesis of Carbon Nanoparticles and their Application to Direct Methanol Fuel Cell
Authors: Shen Jing Mei , Lv Gui Qin , Zhang Ning , Zhang Shusheng , Kang Xiao Hong , Zhu Hong
Published: March 2009

Carbon nanoparticles were prepared by simple method. TEM image shows that the particle
size is several nanometers. Furthermore, the specific surface area of the material is reached for 425.8
m2/g. It is much larger than that of carbonVulcan-XC72, which they is widely used as catalyst supports
for DMFC electrodes. Carbon nanoparticles is a kind of promising material used for catalyst support in
DMFC.
Processing and Properties of Advanced Solid Oxide Fuel Cells
Authors: Stöver Detlev , Buchkremer Hans Peter , Mai Andreas , Menzler Norbert H. , Zahid Mohsine
Published: March 2009

Up to now, Solid Oxide Fuel Cell (SOFC) materials and processing does not meet the cost goals for
commercialization. This resulted in a worldwide increase in R&D activities dealing with advanced
materials and effective manufacturing methods.
The present paper describes efforts to process novel SOFC materials as well as optimization of well
known ones. The R&D trends are explained for key components such as anode, electrolyte, cathode,
contact- and protective layers.
Typical SOFC manufacturing methods include tape casting, extrusion, calendaring and axial
pressing. Each of these techniques has advantages and limitations. Examples for the highly efficient
use of these methods are given for electrolyte supported cells as well as anode and cathode supported
designs. An evaluation in reference to automation, process complexity and costs is given under the
present limiting factors. Exemplary the processing by tape casting and the micro structural fine
tuning of an advanced anode-supported system is discussed in detail. To produce the layered
components of an SOFC, techniques like screen printing, wet powder spraying, PVD and CVD are
under development. While the layer properties are excellent, PVD and CVD are nowadays too
expensive in some cases, due to the low deposition rates. If thin layers are required, these techniques
become interesting under cost considerations. The effectiveness of a PVD interlayer between
electrolyte and high power density cathodes is shown in comparison to a sintered layer.
In thin electrolyte concepts, the cathode becomes the power limiting component at operating
temperatures below around 750°C. Thus new cathode materials and adjusted processing parameters
are under development. The possibilities to manufacture advanced cathode layers by screen printing,
wet powder spraying and other wet chemical methods are discussed. As an example screen printing
of LSCF is described which results in a high power density cathode layer for low temperature SOFC
operation. Finally, future needs to achieve the technical and economic goals are summarized.
First-Principle Molecular-Dynamics Study of Hydrogen and Aluminium Nanowires in Carbon Nanotubes
Authors: Doi Kentaro , Nakano Hiroshi , Ohta Hirokazu , Tachibana Akitomo
Published: March 2009

In this study, we investigated the effect of aluminum species on hydrogen adsorption on
carbon nanotube (CNT). This hydrogen absorption mechanism has been clarified by potential energy
analysis and molecular-dynamics simulations. There were potential barriers in both reactions,
absorption and dissociation of hydrogen on the surface of CNT. These activation energies were,
however, certainly decreased by aluminum species. Furthermore, chemical and physical properties of
the electronic structures were analyzed by kinetic energy density, tension density, and stress tensor
density.
Mechanical Strength and Interface Adhesion of a Solid Oxide Fuel Cell with Doped Ceria Electrolyte
Authors: Xie Yong Song , Zhang Xin Ge , Robertson Mark , Maric Radenka , Ghosh Dave
Published: March 2009

An SOFC must have sufficient mechanical strength and interface adhesion to ensure it
can be handled without breakage during fabrication and assembly, and has desired performance and
reliability. Methods for measuring mechanical properties and interface adhesion of an SOFC have
been developed and measurements made on a cermet-supported SOFC with a SDC electrolyte. The
SOFC evaluated had a porous NiO-YSZ substrate, a porous NiO-SDC anode and a dense SDC
electrolyte fabricated using tape-casting, screen-printing and co-firing techniques. The flexural
strength and interface adhesion of the substrate, the anode and the electrolyte, along with their
Young’s modulus, hardness and residual stress, were quantitatively measured. The results of the
measurements indicate that the NiO-YSZ supported, SDC electrolyte SOFC has adequate
mechanical strength and sufficient interface adhesion.
Design of Micro-Structure at Atom Level in Dy Doped CeO2 Solid Electrolytes for Fuel Cell Applications
Authors: Mori Toshiyuki , Drennan John , Ou Ding Rong , Ye Fei
Published: March 2009

Rare earth doped ceria compounds are fluorite related oxides which show oxide ionic
conductivity higher than yttria stabilized zirconia in oxidizing atmosphere. As a consequence of this,
considerable interest has been shown in application of these materials for ‘low (below 500°C)’
temperature operation of solid oxide fuel cells (SOFCs). In this study, the nano-sized powders of
DyxCe1-xO2-x/2 (x=0.15 and 0.2) were prepared using ammonium carbonate co-precipitation method.
To design the nano-structure in aforementioned materials, the round shape particles were prepared
in nano-scale. The combined process of Spark Plasma Sintering (SPS) and Conventional Sintering
(CS) was examined for fabrication of nano-structured doped CeO2 solid electrolytes. The
nano-structural features in the (SPS+CS) specimen and CS specimen were observed using
transmission electron microscopy (TEM). This micro-analysis suggested that the micro-domain
with distorted pyrochlore structure exists in the grain of these materials. The conducting properties
in the specimens were strongly influenced by the micro-domain size. It is found that the present
combined process minimized the micro-domain size and maximized the conductivity in the
specimens. Also nano-structured Dy doped CeO2 sintered bodies in the present study had wide ionic
domain and high transport number of oxygen. This suggests that fabricated sintered bodies are
suitable for the solid electrolyte in low temperature operated SOFCs. It is concluded that a control
of micro-domain size is a key for development of high quality doped CeO2 electrolytes for fuel cell
application. It is expected that advanced solid electrolytes for clean energy production will be
produced by a design of nano-structure in rare earth doped CeO2 solid electrolyte.
Processing and Mechanical Properties of RuAl-Based Alloys
Authors: Reynolds T.D. , Acosta M. , Johnson David R.
Published: March 2009

Alloys of Ru-Al-Cr with compositions between Ru-10Al-35Cr and Ru-3Al-39Cr (at.%)
were directionally solidified and heat treated to produce single phase hcp-Ru(Cr,Al) and two phase
B2-hcp microstructures. The room temperature fracture toughness, tensile behavior, and cyclic
oxidation behavior at 1100°C were investigated and compared to previous results measured from
RuAl and Ru-Al-Mo alloys. For microstructures consisting of a Ru(Cr,Al) matrix with fine RuAl
precipitate, a good room temperature fracture toughness, tensile ductility, and oxidation resistance
at 1100°C were measured.
Cold-Working and Annealing of L10-Ordering Iron-Palladium Base Intermetallics
Authors: Wiezorek Jörg M.K.
Published: March 2009

Alloys based on FePd in the vicinity of the equiatomic composition are good model
systems to study the microstructrual and phase transformation behavior of the class of
technologically interesting ferromagnetic L10-intermetallics that includes also FePt and CoPt. Here,
thermo-mechanical processing, involving cold-work and annealing at temperatures below the
ordering temperature was used to control microstructures and to improve properties of FePd. L10-
ordered FePd with ultra-fine grain sizes and up to about 8-fold increased coercivity compared with
conventionally processed material has been obtained. Relationships between processing condition,
microstructure (scale, morphology and texture) and the magnetic properties are discussed.
Microstructures and Mechanical Properties of Directionally Solidified Intermetallic Composites
Authors: Bei H. , George E.P.
Published: March 2009

This paper reviews two kinds of well-aligned fibrous microstructures produced by directional
solidification of NiAl-Mo and Fe-Fe2Ta eutectics. In both these composites, fiber size and spacing
decrese inversely as the square root of the growth rate. Tensile tests as a function of temperature
showed that the NiAl-Mo composite has a higher yield strength and lower ductile-to-brittle
transition temperature than the NiAl matrix. For the Fe-Fe2Ta composite, yield strengths in excess
of 700 MPa were obtained at temperatures to 600°C, with elongations to fracture of ~3% which
remained roughly constant at temperatures to 950°C.
A Study of Recrystallization and Phase Transitions in Intermetallic Titanium Aluminides by In Situ High-Energy X-Ray Diffraction
Authors: Liss Klaus Dieter , Bartels A. , Clemens Helmut , Bystrzanowski S. , Stark A. , Buslaps Thomas , Schimansky Frank Peter , Gerling Rainer , Schreyer Andreas
Published: March 2009

High-energy synchrotron X-ray diffraction is a novel and powerful tool for bulk studies of
materials. In this study, it is applied for the investigation of an intermetallic γ-TiAl based alloy. Not
only the diffraction angles, but also the morphology of reflections on the Debye-Scherrer rings are
evaluated in order to approach lattice parameters and grain sizes as well as crystallographic
relationships. An in-situ heating cycle from room temperature to 1362 °C has been conducted starting
from massively transformed γ-TiAl which exhibits high internal stresses. With increasing temperature
the occurrence of strain relaxation, chemical and phase separation, domain orientations, phase
transitions, recrystallization processes, and subsequent grain growth can be observed. The data
obtained by high-energy synchrotron X-ray diffraction, extremely rich in information, are interpreted
step by step.
Influence of Mechanical Surface Treatments on the Fatigue Performance of the Gamma TiAl Alloy Ti-45Al-9Nb-0.2C
Authors: Lindemann Janny , Kutzsche Anja , Oehring Michael , Appel Fritz
Published: March 2009

The effect of shot peening and roller burnishing on the fatigue performance of the γ(TiAl)
alloy Ti-45Al-9Nb-0.2C was investigated over a wide range of processing intensities. At optimized
conditions shot peening and roller burnishing can markedly improve the fatigue strength at ambient
temperatures. For temperatures above 650 °C, the residual compressive stresses induced by shot
peening and roller burnishing quickly relax. This indicates that, at elevated temperatures, surface
roughness and dislocation strengthening become more important for the fatigue performance of
mechanically surface-treated components. Roller burnishing leads to much lower surface roughness
than shot peening, resulting in more effective improvement of high temperature fatigue performance.
However, surface strengthening by shot peening can also be beneficial for the fatigue performance at
elevated temperatures, when the surface roughness is reduced by subsequent polishing.
Microstructure and Hardness of Scandium Trialuminide with Ternary Rare-Earth Additions
Authors: Harada Yoshihisa , Dunand David
Published: March 2009

The microstructure of ternary Al3(Sc1-yREy) intermetallic compounds (where RE is one of
the rare-earth elements La, Ce, Nd, Sm, Eu, Yb or Lu), was investigated as a function of RE
concentration for 0<y≤0.75. Alloys with La, Ce, Nd, Sm or Eu additions consist of a L12 phase
containing a dendritic second phase with D019 (La, Ce, Nd, Sm) or C11b (Eu) structure. Alloys with
Yb or Lu additions show a single L12 phase. The RE solubility limits at 1373 K in the
L12-Al3(Sc1-yREy) phase are very low for La, Nd, Ce and Eu (0.08-0.41 at.% or y=0.0032-0.0164),
low for Sm (3.22 at.% or y=0.1288) and complete for Yb and Lu. The lattice parameter of the L12
solid-solution increases linearly with RE concentration and the magnitude of this effect is correlated
with the atomic size mismatch between Sc and the RE elements. The Vickers micro-hardness of the
L12 solid-solution increases linearly with increasing RE concentration.
Deformation and Fracture Analysis of a Duplex γ-TiAl Alloy during Low Cycle Fatigue
Authors: Cui Wen Fang , Liu Chun Ming , Bauer V. , Christ Hans-Jürgen
Published: March 2009

Isothermal low cycle fatigue (LCF) behaviours of a third generation titanium
aluminide based γ-TiAl alloy with duplex microstructure were investigated under the various
test conditions, including temperature (550°C-750°C), total strain amplitude (0.3%-0.6%) and
environment (air and vacuum), in order to clarify the fatigue life, deformation characters and
fracture process of the alloy during LCF. The plastic strain accumulation has a great
contribution to LCF damage. With increasing total strain range, LCF life decreases distinctly.
Under the small total strain amplitude (≤0.4%), the increase of test temperature enforces
microstructure resistance to LCF fracture. However, the increase of test temperature together
with large total strain amplitude (>0.5%) accelerates the microstructural degradation, which
behaves the dissolution of α2 lamellae and recrystallization of γ phase, resulting in great LCF
damage. Moreover, environment brittlement during high temperature exposure to air
influences the initiation process of fatigue cracks. The fracture mechanisms at various test
conditions were analyzed.
Investigation and Application of Excellent Performance Mg Rare Earth Alloys as a Structural Material
Authors: Wang Li Min , Peng Qiu Ming , Yang Jie , Fang Da Qing , Wu Yao Ming , Liu Hai Feng , Meng Jian , Zhang Hong Jie
Published: March 2009

Magnesium (Mg) alloys are becoming one of the key engineering materials for aerospace
and automotive industries because of their low density, high specific strength, excellent
machinability and good diecastability, etc. In the meantime, conventional Mg alloys are limited for
their low strength and creep resistance. Therefore, special attention is given on its applications at
high temperature such as the transmission case and the engine block, In the near decades, much
effort have been devoted to improving the properties such as strength, ductility, creep resistance of
Mg alloys by adding rare earth (RE) elements, and it has been certified that the addition of RE do
improve the performances of the Mg alloys. In this paper, we will review the progresses in the
investigations of the Mg-RE alloys as a structural material, and also propose its application prospect
in future.