bluuebunny/crossref_metadata_2025 huggingface dataset:
A Precision Tension Control System Based on PIC
Authors: Ren Sheng Le , Wang Yong Zhang , Lu Hua , Su Guo Sen
Published: March 2009

As an important factor in composite fiber winding, fiber winding tension influences the
product quality directly, and therefore tension control is a key technique in fiber winding techniques.
This paper introduces a closed loop tension control system with the PIC single chip computer as the
kernel, a function module with TLC5615 D/A converter as the output, AC servomotors as the
actuator, and a radius-following arm to measure the real time radius of the scroll. The mechanism of
the tension control system is analyzed and the mathematical model is set up. Then the paper expatiates
the design of main control circuit, the voltage transformation circuit and the analogy filter circuit. In
addition, the paper presents digital filter and control algorithm of the PIC software. The system is
proved to have high control precision and rapid time response through performance experiments of
the tension control system in different working states, which well meets the anticipated design
requirements.
Making Alumina Microcomponents From Al Powder
Authors: Kim J.S. , Jiang Kyle , Falticeanu C. Lucien , Davies G.J. , Chang I.T.H.
Published: March 2009

Alumina microcomponents have distinguishing advantages over Si counterparts. However, the shrinkage of alumina, as high as 20%, makes it difficult to produce precision components that require a high tolerance. A new fabrication process is presented to greatly reduce the shrinkage. The process consists of forming an Al powdered component through sintering and transforming the Al powdered component into an alumina part. In this way, the shrinkage occurring in sintering the Al powder component will be compensated by the expansion occurred when Al transforms into alumina. The process involves producing micro-moulds, preparing metallic paste, filling the micro-moulds with the metallic paste, demoulding, sintering the green Al patterns and finally oxidising the sintered Al-based components to achieve alumina components. The process was proven successful. Characterization of the sintered alumina microcomponents has been undertaken, including SEM image analysis, density and scale measurements.
Polymer Derived Ceramic Seals for Application in SOFC
Authors: Hong Sung Jin , Kim Deug Joong
Published: March 2009

Polymer derived ceramic composites have been developed for SOFC seals. The formation and properties of the ceramic composite derived from a mixture with polysiloxane and filler were investigated. In the presence of filler materials such as ZrO2 and AlCo, the thermal properties of the ceramic composite could be controlled. The mixtures with polymethylsiloxane and fillers were prepared and their conversions to ceramic composites by annealing in N2 atmosphere were studied. The microcrystalline composites with filler embedded in a silicon-boron-oxycarbide glass matrix were formed. The thermal expansion behaviors were measured and discussed.
Synthesis and Characterization of Delafossite CuLaO2 for Thermoelectric Application
Authors: Takahashi Yuhsuke , Matsushita Hiroaki , Katsui Akinori
Published: March 2009

The preparation of single-phase CuLaO2 with delafossite-type structure by means of the
solid-state reaction method was investigated using X-ray diffraction. The results showed that
notwhistanding the fact that there was a trace of metallic copper, nearly single-phase CuLaO2 was
obtained by using La(OH)3 as a lanthanum source and by firing the mixed powder with
nonstoichiometric composition ratio of La(OH)3:Cu2O =1:1.425 in a vacuum at 1273 K for 10 h.
The measurement of electrical conductivity and Seebeck coefficient showed that CuLaO2 thus
obtained was a p-type semiconductor and had a Seebeck coefficient of approximately 70 /V/K.
The Revolution of Diamond Synthesis Technology
Authors: Sung James C. , Hu Shao Chung , Lin I Chiao , Tsai Chia Cheng
Published: March 2009

Diamond grits synthesized under ultrahigh pressure have been commercially
manufactured since 1957. Most of the diamond grits are for sawing rocks (granite, marble) and
concrete. In 2004, more than 4 billion carats (800 tons) of diamond saw grits were produced
worldwide. About 3/4 of total production was made in China, but the Chinese diamond grits tend
to be smaller in size (<40 mesh) and with inferior quality, so their total value accounts for only 1/4
of the world sales (about $600 millions).
The ultrahigh pressure process for synthesizing diamond grits is due to make a quantum leap:
the raw materials will incorporate diamond seeds with a predetermined pattern. The result is
doubling the diamond yield with a narrower size distribution. Moreover, the shape of diamond
crystals can be precisely tuned. For example, diamond octahedra or diamond cubes, that are not
available today, can be mass-produced. The new technology is now being implemented
worldwide so the future diamond grits will have improved quality at reduced prices.
Effect of Adding a Type of Binder Phase on The Microstructure, Properties and Heat Treatment of Steel Bonded TiC Cermets
Authors: Farid Akthar , Guo Shi Ju , Shah Jawad Ali , Feng Pei Zhong
Published: March 2009

Particulate TiC reinforced 465 maraging stainless steel matrix Cermets were processed by conventional P/M. The binder phase was added in the form of elemental powders and master alloy powders. The microstructures, binder phase variation with TiC content and mechanical properties were evaluated. The addition of a type of binder phase largely effects the microstructure and mechanical properties. When a master alloy binder phase was used the microstructure showed interphase debondings, microcracks and large growths of TiC particles. Where as, elemental powders in the composition of binder phases showed defect free microstructure of steel bonded cermets. The binder phase variation from starting composition was observed with increase in wt% TiC content and this variation was higher when the master alloy powders were used as a binder. After heat treatment and aging, an increase in hardness was observed. The increase in hardness was attributed to the aging reaction in maraging stainless steel. The response to heat treatment was decreased with an increase in TiC content due to the shift of binder phase from the starting composition.
Preparation and Characterization of Stable Dispersions of Ni Nanoparticles
Authors: Lee Eun Hee , Lee Min Ku , Rhee Chang Kyu
Published: March 2009

Colloid stability of the suspensions of Ni nanoparticles has been investigated with adding
polymeric dispersant in various organic media. We characterized the dispersion stability of Ni
nanoparticles by means of visual inspection, transmission profiles measured by Turbiscan, the
particle size distribution, and the zeta potential. 0.01 wt% of Ni nanoparticles were found to be
optimally dispersed in ethanol among various organic media employed in this study with adding the
dispersant (0.6 wt%-2 wt%). As the concentration of the dispersant increased, the particle size
decreased in size from 300 nm to 200 nm due to less coalescence. The zeta potential values of the
Ni nanoparticles in suspensions with the dispersant were greater than -40mV. Such stable Ni
nanoparticle suspensions are attributed to the electrosteric effect of the polymeric dispersant.
Effect of TiC Content on Oxidation Behavior of Sintered WC-TiC-TaC Alloys
Authors: Tanaka Hiroki , Mouri Shigeki , Nakahara Kenji , Sano Hideaki , Zheng Guo Bin , Uchiyama Yasuo
Published: March 2009

The effect of TiC content on oxidation behavior of the sintered WC-TiC-TaC alloys with
2 mass% TaC and different TiC amount of 3-45 mass% was investigated through oxidation tests in
air at 973K in order to clarify their oxidation mechanism at high temperature. Based on the results
of mass change, SEM observation, elemental map analysis and composition analysis of the samples
before and after the oxidation test, it was revealed that with increasing TiC content in the alloys,
mass changes from oxidation and thickness of the oxidation scale decreased. Thus, it is considered
that the main component of the scales changed from WO3 to TiO2 gradually with increasing TiC
content in the alloys, and oxygen diffusing through the oxidation scale to the alloys was inhibited
more and more.
Mechanical Properties of Refractory Metals at Extremely High Temperatures
Authors: Fischer Bernd , Beschliesser Manuel , Hoffmann Andreas , Vorberg Stefan
Published: March 2009

Driven by the unavailibility of commercial test equipment for tensile and creep testing at temperatures up to 3000°C a measuring system has been developed and constructed at the University of Applied Sciences, Jena. These temperatures are reached with precision by heating samples directly by electric current. Contact-less strain measurements are carried out with image processing software utilizing a CCD camera system. This paper covers results of creep tests which have been conducted on TZM sheet material (thickness 2 mm) in the temperature range between 1200°C and 1600°C. It is the aim of this work to show the influence of heat-treatment conditions on creep performance in the investigated temperature range.
Improved Magnetic Properties of Silicon-Iron Alloy Powder Core
Authors: Lee Tae Kyung , Kim Gu Hyun , Choi Gwang Bo , Jeong In Bum , Kim Kwang Youn , Jang Pyung Woo
Published: March 2009

Eventhough Fe-6.5 wt.% Si alloy shows excellent magnetic properties, magnetic
components made of the alloy with the composition are not totally commercialized because of its
extremely low ductility. In order to overcome this demerit of alloy, 6.7 wt.% Si alloy powders were
produced by gas atomization and then post-processed to form magnetic cores. By doing so, the total
core loss could be minimized by reducing both hysteresis and eddy current loss, which were
attributed to both grain size adjustment and particle size control. From our experiments, we were
able to achive a core loss of 390 mW/cm3 at an induction of 0.1 T and 50 kHz through proper
processes and a permeability μeff of 68 at low frequency was kept up to 700 kHz. These properties
are compatable with the properties of well-known soft magnetic materials such as Fe-Si-Al and Ni-
Fe alloys. From the above results, it can be concluded that Fe-Si alloy powders with high Si content
have very high potential for the commercialization and application of the core.
Improvement of Super Low Core-Loss Soft Magnetic Materials
Authors: Maeda Toru , Sato Atsushi , Mochida Yasushi , Toyoda Haruhisa , Mimura Koji , Nishioka Takao
Published: March 2009

In the previous work, we reported a P/M soft magnetic material with super low core loss
value of W10/1k = 68 W/kg which is lower than that of 0.35mm-thick flat rolled soft magnetic
laminated steel sheets. But this material lack of strength characteristics due to spherical particles
produced by a gas-atomizing method. That is, the value of transverse rupture strength (TRS) was
only 20MPa when a non-hygroscopicity resin was used as binder.
In order to achieve both low core loss and high strength, the iron powder (shape, surface
morphology) and binder strength was improved, and we were able to obtain a material with TRS of
80 MPa and core loss (W10/1k) of 108 W/kg of. Furthermore, by using this binder system, we were
able to obtain a TRS of over 50MPa for the material with spherical particles (W10/1k = 81 W/kg).
Magnetic Properties of Amorphous FeSiB and Nanocrystalline Fe73Si16B7Nb3Cu1 Soft Magnetic Sheets
Authors: Cho H.J. , Cho E.K. , Song Y.S. , Kwon S.K. , Sohn K.Y. , Park Won Wook
Published: March 2009

The magnetic inductance of nanocrystalline Fe73Si16B7Nb3Cu1 and an amorphous
FeSiB sheet has been investigated to identify the radiofrequency identification (RFID)
performance. Planar flow cast amorphous ribbons were pulverized and classified using a stack of
sieve. The powder was mixed with binder and solvent and tape-casted to form 0.6-0.8 mm thick
films. The inductance of the sheet was measured to investigate the RFID characteristics of the
nanocrystalline and the amorphous materials. Results showed that the atmosphere for annealing
significantly influenced on the inductance of the material. The surface oxidation of the particles
was the main reason for the reduced inductance. The maximum inductance of Fe73Si16B7Nb3Cu1
alloy was about 88μH at 17.4 MHz, which was about 65% greater compared to the amorphous
FeSiB alloy. The higher inductance in the nanocrystalline alloy indicates that it may be used as a
potential replacement of current RFID materials.
Preparation and Sintering of Nano-Sized W-Ni-Fe Powder by Sol-Spray-Drying Process
Authors: Fan Jing Lian , Liu Tao , Ma Yun Zhu , Cheng Hui Chao
Published: March 2009

In this paper, less than 50nm nano-sized W-Ni-Fe composite powder was prepared by Sol-Spray-Drying Process. The preparing processes such as sol formation condition, reduction process of the procusor were studied in detail. The powder characteristics and sintering behavior of the powders were also studied. The powder is nearly spherical and it has good sinterability. In comparison with traditional micron mixed powder consisting of same composition, the melting temperature of the second phase lowered about 70°C, and the sintering temperature for nearly full densification was about 1390°C, which lowered more than 100°C.The effects of rare earth on sintering of the alloy were discussed.
Development of Conductive and Anticorrosive Paint Dispersed with Carbon Particles for Metal Separators of PEFC
Authors: Okahara Masahiro , Ishijima Zenzo , Shirahige Minoru
Published: March 2009

A resin paint dispersed with carbon particles was developed for the purpose of good
conductivity and corrosion resistance for metal separators used in Polymer Electrolyte Fuel Cells
(PEFC). The use of metal separators, especially Ti separators is a technology which has received
much attention for its practical application as it allows for much greater compact stacking, since it is
superior in both productivity and strength, in comparison with that of carbon molding separators.
However, if pure Ti separators are used in a severe reaction of electricity generation, there is a
deterioration in conductivity, because of the formation of a passive film, which subsequently causes
electricity generation difficulties after a few hours of use. Through examining the type of resin used
for the purpose of controlling the passive state, the grain size of the conductive filler (graphite (Gr)
+ carbon black (CB)) and the composition combination for the purpose of secure conductivity, it
was found that the combination of a scaly graphite-furnaced black mixed powder with a median
particle diameter of 4μm and VDF-10%HFP copolymer resin was optimal.
As a result of performing a single cell electricity generation evaluation of the Ti separator, which
had the above mentioned coating material, the life of 22,000 or more hours was confirmed and an
electricity generation evaluation is now being undertaken.
The Development of Mono-Sized Micro Silicon Particles for Spherical Solar Cells by Pulsated Orifice Ejection Method
Authors: Dong Wei , Masuda Satoshi , Takagi Kenta , Kawasaki Akira
Published: March 2009

Mono-sized silicon particles were effectively fabricated by a novel way named pulsated orifice ejection method (POEM). The particles are with very narrow particles size distribution and very small standard deviation of mean particle size. There are two different types spherical silicon particles were found. One consists of many grains mainly in random boundaries. The other consists of two or three grains with only twin orientation relationships, even single crystal in cross-section was also found within this type spherical silicon particles.
Hard, Wear Resistant Metal Surfaces for Industrial Applications through Laser Powder Deposition
Authors: Sears James , Costello Aaron
Published: March 2009

Most materials produced today are monolithic structures that are heat treated to perform a
particular function. Laser Powder Deposition (LPD) is a technology capable of modifying a
metallic structure by adding the appropriate material to perform a desired function (e.g., wear and
corrosion resistance). LPD offers a unique fabrication technique that allows the use of soft (tough)
materials as base structures. Through LPD a hard material can be applied to the base material with
little thermal input (minimal dilution and heat-affected-zone {HAZ}), thus providing the function of
a heat treatment or other surface modifications (e.g., carburizing, nitriding, thermal spray and
electroplating). Several materials (e.g., Stellite 6 &21, 316 SS, 420 SS, M4, Rex 20, Rex 121, 10V,
AeroMet 100, CCW+, IN 625 and IN 718) have been deposited on to carbon steel (4140, 4340,
1566, 1018) substrates to provide various functions for a number of industrial applications. These
surface modifications have been evaluated through standard wear testing (ASTM G-65), surface
hardness (Rc), micro-hardness (vickers), and optical microscopy. The results from these
evaluations will be presented along with several industrial application case studies.
Mg-Y-Cu Bulk Metallic Glass Obtained by Mechanical Alloying and Powder Consolidation
Authors: Lee Pee Yew , Hsu Chih Feng , Wang C.C.
Published: March 2009

Mg55Y15Cu30 metallic glass powders were prepared by the mechanical alloying of
pure Mg, Y, and Cu after 10 h of milling. The thermal stability of these Mg55Y15Cu30
amorphous powders was investigated using the differential scanning calorimeter (DSC).
Tg ,Tx , and Δ Tx are 442 K, 478 K, and 36 K, respectively. The as-milled Mg55Y15Cu30
powders were then consolidated by vacuum hot pressing into disk compacts with a diameter
and thickness of 10 mm and 1 mm, respectively. This yielded bulk Mg55Y15Cu30 metallic
glass with nanocrystalline precipitates homogeneously embedded in a highly dense glassy
matrix. The pressure applied during consolidation can enhance thermal stability and
prolong the existence of amorphous phase within Mg55Y15Cu30 powders.
Nanocrystalline and Ultrafine Grained Materials by Mechanical Alloying
Authors: Wang Erde , Hu Lian Xi
Published: March 2009

Recent research at Harbin Institute of Technology on the synthesis of nanocrystalline and untrafine grained materials by mechanical alloying is reviewed. Examples of the materials include aluminum alloy, copper alloy, Ti/Al composite, magnesium-based hydrogen storage material, and Nd2Fe14B/α-Fe magnetic nanocomposite. Details of the processes of mechanical alloying and consolidation of the mechanically alloyed nanocrystalline powder materials are presented. The microstructure characteristics and properties of the synthesized materials are addressed.
Synthesis of Titanium Carbide by Heat Treatment of TiH2 and Carbon Black Powders
Authors: Ahn In Sup , Bae Sung Yeal , Cho Ho Jung , Kim Chul Jin , Park Dong Kyu
Published: March 2009

TiC cermet is widely used for working dies with a high hardness and tool materials. In
this research, we attempted to produce submicron sized TiC powders from the ball milled TiH2 and
carbon black mixture by thermal treatment. The titanium hydride and carbon composite powders
were milled under argon atmosphere for 7 hours at various ball to powder ratios. At the initial stage,
an increase in particle size was observed, and graphite phase disappered. The TiC phase of 300nm
mean particle size was obtained by milling for 5 hours. As a result, its morphologies were
excessively agglomerated. At the heat treating temperature of 500°C, TiH2 phase transformed to Ti
completely and the complete TiC of lattice parameter 0.431 nm was formed when the temperature
reached 1000°C. Metal matrix composites(MMCs) based on the Fe-TiC system can be synthesized
by spark plasma sintering. Specimen formed sintering Fe-TiC powders display a microstructure of
uniformly dispersed TiC grain in a continuous metal matrix.
High Velocity Compaction : Overview of Materials, Applications and Potential
Authors: Dore Florence , Lazzarotto Ludovic , Bourdin Stephane
Published: March 2009

Since 2000, CETIM has been equipped with a High Velocity Press that can deliver up to
5 shots per second with each blow accurately set up (up to 20000J) thanks to the impact velocity
regulation (up to 11m.s-1). Through different projects, CETIM and its scientific and industrial
partners have evaluated the potential of this new technology in terms of materials and component
shape. Various kinds of powder materials were studied: metals, ceramics and polymers. The HVC
process was used with success to manufacture gears, large parts and multilevel components. More
than, the green machining process that enables shapes to be produced that would otherwise be
impossible to compact is improved by the high density of HVC parts and it is also an opportunity to
produce components with very hard sintered materials.
Warm Compaction: FEM Analysis of Stress and Deformation States of Compacting Dies with Rectangular Profile of Various Aspect Ratio
Authors: Armentani Enrico , Bocchini G.F. , Cricrì G. , Esposito Renato
Published: March 2009

The deformation under radial pressure of rectangular dies for metal powder compaction
has been investigated by FEM. The explored variables have been: aspect ratio of die profile, ratio
between diagonal of the profile and die height, insert and ring thickness, radius at die corners,
interference, different insert materials, i. e. conventional HSS, HSS from powders, cemented
carbide (10% Co). The analyses has ascertained the unwanted appearance of tensile normal stress
on brittle materials, also “at rest”, and even some dramatic changes of stress patterns as the die
height increases with respect to the rectangular profile dimensions. Different materials behave
differently, mainly due to difference of thermal expansion coefficients. Profile changes occur when
the dies are heated up to the temperature required for warm compaction. The deformation patterns
depend on compaction temperature and on thermal expansion coefficients.
Dry Coated Particle for Plasma Spraying
Authors: Briones-Rodríguez C. , Mayagoitia Vicente , Cuenca-Alvarez Ricardo
Published: March 2009

The performance of an in-house designed mechanofusion process and the preparation of
composite powders for plasma spraying are investigated in a variety of powdered mixtures
including metal/oxide, carbide/oxide, carbide/metal and metal/oxide/carbide. Scanning electron
microscopy shows that dry particle coating depends on the thermo-mechanical and chemical
properties of the powdered system. In the metal/oxide, carbide/oxide and metal/oxide/carbide
powder mixtures, fine ceramic particles coat the surface of the metallic or ceramic coarser particles
with no need of binders or solvents. However with the carbide/metal powdered system, an intimate
mixture of components is achieved with an incipient dry particle coating. A nearly rounded shape of
the final composite particles is induced by the mechanical energy input with no formation of new
phases as confirmed by XRD analysis. It is suggested that the coating mechanism is governed by
agglomeration and rolling phenomena. Finally these types of powders feature characteristics to be
plasma sprayed in air.
Porosity in Spray-Formed Materials
Authors: Uhlenwinkel Volker , Ellendt N.
Published: March 2009

Porosity in spray-formed materials is an important issue, but the formation of porosity is
not completely understood. Many experimental results and some theoretical models have been
presented in the past. Nevertheless, the prediction of porosity in a deposit is still not possible today.
The paper will give some examples picked from literature, which show some general correlations
between process parameters and porosity. These correlations can be helpful to form a basic
understanding of the process. Finally it is necessary to know more about the conditions of the
droplets and the deposit at the point of impingement. These impacting conditions have to be
correlated to the porosity to improve the understanding of the process and to make a prediction
possible. Determining the impact conditions is a challenge because usually they are not constant
with time and some values are difficult to measure.
Our experiments show a strong correlation between the surface temperature of the deposit and the
porosity. For IN718 and U720 as-sprayed porosities below 1 vol.% were achieved if the deposit
surface temperature is app. 1250 °C. The average impact angle weighted by the local particle mass
flux is also an important parameter. The probability of low as-sprayed porosity is high if the
average weighted impact angle is below 25° but decreases dramatically for higher impact angles.
High Efficient Metal Powder Production by Gas Atomisation Process
Authors: Ünal Rahmi , Aydın Mehmet
Published: March 2009

The most important parameter for production of fine powders efficiently is the velocity
of the atomizing gas. This can be achieved by increasing the pressure, but this way will not be
economic. For that reason, to achieve supersonic velocities different nozzle designs are used in
close coupled configuration for an efficient atomization. In this study, a new laval type nozzle was
designed and manufactured. Using this nozzle tin powder was produced in close coupled system by
using nitrogen gas at different operating conditions. The results showed that the increasing the gas
pressure up to 1.47 MPa reduced the mean powder size down to 11.39 microns with a gas/melt
mass flow rate ratio of 2.0. Powders are spherical in shape and have smooth surfaces.
High Oxygen Sensitivity of Nanocrystalline Ceria Prepared by Thermochemical Process
Authors: Lee D.W. , Yu Ji Hun , Lim T.S. , Jang Tae Suk
Published: March 2009

Nanostructured CeO2 powder was synthesized by a thermochemical process and its applicability as an oxygen gas sensor was investigated. An amorphous precursor was prepared by spray drying a cerium-nitrate solution and then heat-treated in air to induce evaporation of volatile components from the precursor powder, which then forms nanostructured ceria. The powder produced possessed a loose agglomerated structure with extremely fine CeO2 particles about 15 nm in size, resulting in a very high specific surface area (110 m2/g). The average grain size of a specimen sintered from the ceria powder at 1000 oC was about 40 nm, and its oxygen sensitivity n (logσ log(PO2 /Po)-n) was about 1/4 at 600 oC. The response time t90, time for responding to a change of oxygen partial pressure, of the specimens sintered at 800 ~ 1100 oC was very short, i.e., 3 ~ 5 seconds: The signal output was almost identical and uniformly repeated in a stable manner.
Strain Hardening Behaviour of PM Alloys with Heterogeneous Microstructure
Authors: Straffelini Giovanni
Published: March 2009

Tensile stress-strain and dynamic acoustic resonance tests were performed on Fe-C-Ni-
Cu-Mo high-strength steels, characterized by a heterogeneous matrix microstructure and the
prevalence of open porosity. All materials display the first yielding phenomenon and, successively,
a continuous yielding behavior. This flow behavior can be described by the Ludwigson equation
and developes through three stages: the onset of localized plastic deformation at the pore edges; the
evolution of plastic deformation at the pore necks (where the austenitic Ni-rich phase is
predominant); the spreading of plastic deformation in the interior of the matrix. The analytical
modeling of the strain hardening behavior made it possible to obtain the boundaries between the
different deformation stages.
Effect of Porosity Content on the Weldability of Powder Metal Parts Produced by Friction Stir Welding
Authors: Kurt Adem , Uygur Ilyas , Ates Hakan
Published: March 2009

Friction stir welding technique (FSW) has many advantages in terms of tool design,
rotational speed and traveling speed, and can be adjusted in a precise manner. It enables heat input
into the system to be controlled. In this study, Aluminum powders were compacted at 350,400 and
450 MPa pressure and sintered at 450 oC temperature for 30 minutes in Ar atmosphere. Sintered
powder metal parts were joined to each other by FSW at the speed of 1800 rpm and traveling
welding speed 200 mm/min under a constant friction force. The results show that the amount of
porosity affects the weldability of powder metallurgy (P/M) parts. Furthermore, the porosity and
microstructural evolution of the Aluminum also affected the hardness values of the tested materials.
Interactions in Titanium Matrix Composites Reinforced by Titanium Compounds by Conventional PM Route
Authors: Romero F. , Amigó Vicente , Salvador M.D. , Vicente A.
Published: March 2009

Titanium metal matrix composites were produced. The powder metallurgy route applied
was a conventional route consisting of blending titanium matrix powder with different percentages
of various titanium compounds, as reinforcement particles, followed by cold compaction in a
uniaxial press with a floating matrix and a sintering process in a vacuum furnace. This work studied
the different interactions between the titanium matrix and the various titanium compounds added.
To evaluate these interactions microscopic techniques are used principally, optical and electronic
microscopy, with EDX techniques. By microstructural analysis the reactivity between
reinforcement and matrix particles was investigated, and any new phases that formed during the
sintering process were evaluated. In addition, microhardness test were conducted to study the
mechanical properties associated with the new phases, and to evaluate the relative strength or
weakness of the interfacial zones.
Microstructures and Mechanical Properties of Consolidated Mg-Zn-Y Alloy
Authors: Lee J.K. , Kim Taek Soo , Jeong Ha Guk , Bae Jung Chan
Published: March 2009

The microstructure and mechanical properties of the Mg97Zn1Y2 alloy prepared by spark
plasma sintering of gas atomized powders have been investigated. After consolidation, precipitates
were observed to form in the α-Mg solid solution matrix of the Mg97Zn1Y2 alloy. These precipitates
consisted of Mg12YZn and Mg24Y5 phases. The density of the consolidated bulk Mg-Zn-Y alloy was
1.86 g/cm3. The ultimate tensile strength and elongation were dependent on the consolidation
temperature, which were in the ranges of 280 to 293 MPa and 8.5 to 20.8 %, respectively.
The Influence of Heat Treatment on Corrosion Resistance of PM Composite Materials Based on EN AW-AlCu4Mg1(A) Aluminium Alloy Reinforced with the Ti(C,N) Particles
Authors: Dobrzański Leszek Adam , Włodarczyk-Fligier Anna , Adamiak Marcin
Published: March 2009

Investigation results of the heat treatment effect on the corrosion resistance of the EN AW-AlCu4Mg1 (A) aluminium alloy base composite materials reinforced with the Ti(C,N) particles with varying volume fractions are presented. Examinations were made of the EN AW-Al Cu4Mg1(A) aluminum alloy, and also of the composite materials with the matrix from this aluminium alloy. It was found out, basing on own research, that corrosion wear after the corrosion tests of the composite materials with the addition of 5% of the Ti(C,N) particles is smaller compared to the pure aluminium alloy. Precipitation hardening causes improvement of the corrosion resistance of the investigated composite materials and - like in the state before the heat treatment, materials with 5% portion of the Ti(C,N) reinforcement ratio are characteristic of more advantageous features compared to the material without the reinforcement.
Fabrication of Carbon Nanotube Reinforced Aluminum Composite by Powder Extrusion Process
Authors: Yuuki Junichi , Kwon Hansang , Kawasaki Akira , Magario Akira , Noguchi Toru , Beppu Junichi , Seki Masayuki
Published: March 2009

This paper describes a fabrication process of Al/CNT composites and investigated their
mechanical properties. CNT is a very useful reinforcement for composites since it has a very high
strength and very high Young’s modulus. However, it is very difficult to distribute CNT in a metal
matrix. Natural rubber was used as an elastomer and mixed with Al powder and CNT precursors to
improve the distribution of the CNT in Al matrix. The resulting powder mixture was filled into Al
alloy billets and encapsulated in vacuum atmosphere. The billets were then extruded with different
extrusion ratios of 5, 10 and 20 at 673K. The composites were observed under optical microscope
and FE-SEM, and the mechanical properties were evaluated by Vickers hardness and tensile tests.
We succeeded in obtaining fully densified and finely extruded rod of Al/CNT composites of well
distributed CNT by hot extrusion process. Observation of post extrusion micro structures revealed
that CNT were not damaged by the hot extrusion process and their Vickers hardness and tensile
strengths obtained were about twice compared to pure Al.
Formation and Structure of Alkyl-Phosphonic Acid Layers on Passive Iron
Authors: Paszternák A. , Felhősi Ilona , Keresztes Z. , Kálmán Erika
Published: March 2009

Phosphonate layer formation on passive iron surface has been investigated by electrochemical and atomic force microscopy techniques. It was found that phosphonate groups bond more strongly to oxide surface, while metallic iron surface is disadvantageous for phosphonate layer formation in aqueous solutions. The rate of anodic dissolution is continually decreasing due to the time-dependent formation of protective phosphonate layer. The kinetics of phosphonate layer formation on passive iron is determined by the potential applied for preceding passive film formation. The size and shape of iron oxide grains depends slightly on the potential of passivation. Changes in morphology due to the phosphonate layer formation have been recorded by AFM.
Fluid Mechanical Model for Formation of Mineral Wool Fibers Applied in Polymer Composites
Authors: Vad János , Morlin Bálint
Published: March 2009

A fluid mechanical model was elaborated for the formation of mineral wool in the Junkers production technology. The model is based on an analytical approach. The future aim of the model is to establish guidelines for the following improvement in mineral wool quality: reduction of the diameter of mineral wool fibers, improvement of the homogeneity of fiber diameter distribution, and reduction of gravel size. The mineral wool is considered herein as reinforcing material for polymer composites, and such modifications result in the quality improvement of the composites. The quality improvement can be carried out by modifications of the technological settings. The parameters of the model were approximated on the basis of electron-microscopic measurements on a mineral wool reference specimen.
Examination of the Orientation Relationships between the Main Phases of Duplex Stainless Steel by EBSD
Authors: Berecz Tibor , Szabó Péter János
Published: March 2009

Duplex stainless steels are a famous group of the stainless steels. Duplex stainless steels
consist of mainly austenitic and ferritic phases, which is resulted by high content of different
alloying elements and low content of carbon. These alloying elements can effect a number of
precipitations at high temperatures. The most important phase of these precipitation is the σ-phase,
what cause rigidity and reduced resistance aganist the corrosion. Several orientation relationships
have been determined between the austenitic, ferritic and σ-phase in duplex stainless steels. In this
paper we tried to verify them by EBSD (electron backscatter diffraction).
Hydrogen in the Plastic Deformed Steel
Authors: Fábián Enikö Réka , Dévényi László
Published: March 2009

The solubility of hydrogen in iron and steels are affected by temperature and crystal structure. At lower temperatures (below about 400°C), the excess hydrogen, beyond that which is soluble (and therefore dissolved) interstitially, is retained in the steel in other sites commonly referred to as ”traps”. At room temperature, the dissolved hydrogen may be only a small fraction of the total hydrogen content. The movement of hydrogen in steel occurs by the migration of atoms through the lattice. The hydrogen diffusion takes place with interstitial mechanism. Trapping enhances the solubility of hydrogen but decreases the diffusivity. In practice hydrogen transmissibility is characterized by TH value. We have studied the effect of the cold rolling on the TH value for Al-killed low carbon enamelling-grade steel sheets. The microstructures of the samples were formed from ferrite, carbides and some non-metallic inclusions. Reducing the thickness of the steel sheets by cold rolling in carbides appears ruptures, microcavities, and the dislocation density increases in ferrite grains. Cold work increases the hydrogen permeation time. The average of TH values after hot rolling was 0.6; after about 72 % thickness reductions by cold rolling the average TH values was 101.4.
Micro Structural Aspects of Unstable Crack Propagation in Ferritic Steels
Authors: Trampus Péter
Published: March 2009

Fracture of ferritic reactor pressure vessel steels is determined by temperature and
specimen size. In low temperature fracture occurs by cleavage, with elevation of temperature
and decrease of specimen size the ratio of ductile tearing prior to cleavage increases and, in
the end, fracture will have a ductile character. There is a temperature interval where both
fracture mechanisms are present. Hypothesis of the traditional (global) assessment method has
been that the shift of the fracture toughness reference curves due to neutron irradiation is
equal with the shift of the ductile-to-brittle transition temperature measured by the Charpy
impact test. Local assessment approaches based on the „weakest link” statistical theory
recommend the direct measurement of fracture mechanics parameters to structural integrity
evaluation. The paper describes the main features of both global and local approaches,
analyzing the micro structural aspects of the most known micromechanical models of local
approach and drawing conclusions concerning their applicability.
A Novel Approach of Quenchant Evaluation by Applying Quality Functions
Authors: Felde Imre , Czinege Imre , Smoljan B. , Colás Rafael
Published: March 2009

A novel numerical approach for testing and evaluation of quenching media and
quenching systems is outlined. The technique proposed is based on determination of heat transfer
coefficient from temperature signals recorded and applying it as input for simulation of quenching
process. The evaluation method is based on the calculated microstructural and mechanical
properties of cylindrical samples.
High Elasticity Strain Gauge Made from Conductive Silicone Rubber
Authors: Valenta László , Huba Antal , Muka István
Published: March 2009

The paper summarises the results of our investigations on the conductive silicone rubber as strain sensor. The dynamic behaviour of silicone rubber shows strong nonlinearity and because of the relaxation and creep the sensor can not be used for static measure. The greatest advantage of this material lies in its high elasticity. The commercial strain metallic or semiconductor gauges work in the range of 10-7<ε<10-3 . With the new silicone rubber sensor one can achieve elongations typically in the range of 10-2<ε<102 so this sensor offers new possibilities for the measure and control of high elasticity structures. The fatigue tests show that dynamic behaviour of the sensor silicone is stable.
Compelling Global Issues in Science and Technology and the Role of Materials Science
Authors: Wadsworth Jeffrey , Cobian M.
Published: March 2009

As we enter the 21st century, we confront three global challenges that can be resolved only
with forefront science and technology: growing demands for energy, the adverse effects of climate
change, and emerging threats to national and global security. Materials science is critical to the fields
of research, development, and application that are essential to meeting these challenges. The
increasing globalization of scientific research and technology development presents its own
challenges at the national level, but also opens the way to new opportunities for fruitful collaboration
in materials science.
Titanium Carbide Particulate Reinforced Titanium Based Composite by In Situ Process
Authors: Kim Myoung Gyun , Kim Young Jig
Published: March 2009

Titanium carbide particle reinforced titanium composites were prepared by in-situ
synthesis reaction between titanium and carbon liquid alloys. The phases constitute and
microstructures of titanium composite have been investigated by OM, XRD, SEM, EPMA and TEM.
Although it was possible to synthesize titanium carbide particle reinforced titanium composites, the
morphology of in-situ titanium carbide grows into typically dendritic shape due to the compositional
supercooling theory. The observation of TEM also show that interfaces between the reinforcements
and the titanium matrix alloy are very clean.
Particle Size Effects on Complex Permeability and Electromagnetic Wave Absorption Properties of Amorphous Alloy-Epoxy Composites
Authors: Lim Kyoung Mook , Kim Moon Chul , Park Chan Gyung , Hong Y.M.
Published: March 2009

The electromagnetic wave absorption properties of amorphous alloy-epoxy composites
have been investigated utilizing various amorphous alloy particle sizes in quasi-microwave
frequency. The composite fabricated with small sized particle (< 26 μm) only revealed good
absorption properties above 20dB with a thin thickness less than 6 mm. As particle size decreased,
absorber had thinner matching thickness mainly due to increasing matching frequency. Such a
variation of matching frequency was resulted from resonance frequency variation. The magnetic
relaxation of the composites with small particle (< 38 μm) was contributed to magnetic resonance
induced by demagnetization field. The eddy current also affected on the magnetic relaxation of the
composites with large particle (> 38 μm) due to their large conductivity.
Effects of Fillers on Electrical Properties of PTFE Composites for Circuit Breaker
Authors: Park Hoy Yul , Kang Dong Pil , Ahn Myeong Sang , Lee Hee Woong , Yoon Seog Young , Park Seong Soo
Published: March 2009

This paper presents the effects of fillers on electrical properties of PTFE composites for
nozzle of circuit breaker. PTFE has been used widely as a material for circuit breaker nozzle. Adding
some filler into PTFE material is expected to be efficient for improving the endurance against arc
radiation. In this experiment, effects of fillers on electrical properties such as dielectric constant,
dissipation factor, electrical resistivity, dielectric strength and corona resistance of PTFE composites
were investigated.
Enhancement of TBC (Thermal Barrier Coatings) Characteristics by Gas Tunnel Type Plasma Spraying
Authors: Kobayashi Akira
Published: March 2009

Zirconia (ZrO2) coating formed by plasma spray method is widely used industrially as a
thermal barrier coating (TBC). Presently, there are some problems such as spallation and cracks
inside the coating. As one solution given by the development of new spaying processing, the gas
tunnel type plasma spraying is one of excellent method to enhance the TBC performances. The
zirconia-alumina (ZrO2-Al2O3) composite coating formed by this method has a high hardness layer
at the surface side of the coating, which shows the graded functionality of hardness, and is superior
as a TBC. In this paper, the performance of such high hardness ZrO2-Al2O3 composite coating was
investigated and the merit as TBC was clarified. The Vickers hardness of the high hardness layer
near the coating surface increased by the thermal process of high energy plasma, which
corresponded to the result that the coating became denser. Also, the effect of alumina mixing was
discussed about the microstructure of this composite coating. The combination of high hardness of
Al2O3 with the low thermal conductivity of ZrO2 resulted to the development of high performance
TBC. The transverse thermal conductivity of such ZrO2-Al2O3 composite coatings was proved to
be much smaller than that in the longitudinal direction.
Laser Shock Processing as a Method for the Improvement of Metallic Materials Surface Properties: A Discussion on the Influence of Combined Mechanical and Thermal Effects
Authors: Ocaña José Luis , Morales Furió Miguel , Molpeceres C. , Porro J.A. , García-Beltrán A.
Published: March 2009

Laser shock processing (LSP) has been presented as an effective technology for improving
surface mechanical and corrosion properties of metals, and is being developed as a practical
process amenable to production engineering. The main acknowledged advantages of the laser
shock processing technique consist on its capability of inducing a relatively deep compression
residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour,
explicitly, the life improvement of the treated specimens against wear, crack growth and stress
corrosion cracking. In the present paper, practical results at laboratory scale on the application
of Laser Shock Processing are presented showing the obtained tensile residual stresses
relaxation along with corresponding preliminary results about the resulting mechanical
properties improvement induced by the treatment. Additionally, the influence of different
irradiation parameters will be presented along with a physical interpretation of the mechanical
effects induced in the materials by the characteristic fast laser-plasma interaction regime
occurring in the process and model based assessments on the real possibilities of the
technique as a substitutive of traditional techniques as, for example, shot peening. From a
specific point of view, a critical analysis of the relative influences of coupled thermal and
mechanical stress and deformation effects during LSP is presented.
Surface Modification of Steel Using Liquid Jet Peening (Fatigue Performance)
Authors: Gnanamoorthy R. , Sahaya Grinspan A.
Published: March 2009

Oil jet peening is a surface modification process developed for the introduction of
compressive residual stresses. In this process, a high-pressure oil jet impinges on the surface to be
peened. Specimens made of AISI 1040 steel were peened at oil pressure of 50 MPa. Residual
stresses induced on the oil jet peened specimen was in the order of -200 MPa. Standoff distance
influenced the residual stress induced and also the erosion and surface roughness. Fully reversed
cantilever bending tests conducted on the peened and unpeened conditions revealed the improved
performance of the oil jet peened specimens.
Formation and Characteristic of Room Temperature Electrolytic Sulfidized Coating on Hard Steel Substrate
Authors: Jiang Jing Hua , Jiang Jian Qing , Ma Aibin , Lin Ping Hua
Published: March 2009

An electrolytic sulfurization at room temperature has been introduced in the present work,
which process parameters are optimized to the quenched Cr12 substrate. Morphology and
microstructure of the sulfide layers are investigated deeply, and their formation mechanism is discussed
in detailed. According to optimum parameter of sulfurizing process ( assistant current density of
1.8A/dm2, the saturated rare-earth-halide solution containing 300g Na2S2O3, 60g KHSO3 and 1000ml
H2O, 298K/20~40min), the ferrous sulfide coating was easily obtained on the quenched Cr12 substrate
with a uniform thickness of above 10μm, no matter about the treated parts with the complex
geometrical shapes. The tribological experiment results of a block-on-ring tribometer indicate that the
sulfide coatings on hard substrate have a very low friction coefficient and could obviously reduce the
wear extent of its counterpart. Compared with the traditional low-temperature process, this sulfurizing
technology has such virtues as simple process, heatless, low cost, little deformation, without pollution
question, etc., which could be employed for industrial solid lubricant due to the good friction-reducing
characteristic of lamellar-structure FeS phase.