bluuebunny/crossref_metadata_2025 huggingface dataset:
Insulation and Magnetic Properties of Iron Powder Coated by Wet Chemical Method
Authors: Cha Hyun Rok , Son Hyeon Taek , Yun Cheol Ho , Cho Jae Ik , Oh Ik Hyun , Lee Jae Seol , Kang Chang Seog , Kim Hyoung Mo
Published: March 2009

Magnetic core components are often made from laminated sheet steel, but they are difficult
to manufacture in near net shape, resulting in large core losses at higher frequencies. In this study, the
pure iron powder was treated with aqueous phosphoric acid to produce phosphate insulating layer on
the surface. After drying the powder, it was mixed with 0.5wt% Zn stearate and compacted in a mold
with a diameter of 20mm at 800MPa. The powder compacts were then heat treated at 500°C for 1
hour. The results showed that insulated iron powder was obtained with uniform phosphate layer by
chemical reaction. With increased amount of phosphate layer, the core loss and density of compacts
were decreased. It was also found that the addition of ethyl alcohol during insulating reaction
resulted in improved core loss value.
Synthesis of Cu-Coated Ni-Based Amorphous Composite Powders by Gas Atomization and Spray Drying Process
Authors: Kim Byoung Kee , Kim Yong Jin , Kim Jin Chun
Published: March 2009

Ni59Zr20Ti16Si2Sn3 bulk metallic glass (BMG) powders were produced by a gas
atomization process, and ductile Cu powders were coated on the Ni-based BMG powders using a
spray drying process in order to increase the ductility. Characteristics of the as-prepared powders
with the atomization and spray drying process conditions were investigated. The atomization was
conducted at 1450oC under the vacuum of 10-2 torr and the powders were mixed with water-soluble
Cu nitrate. The mixture was sprayed at the temperature of 130oC to prepared initial powder. After
reduction treatment, sub-micron size Cu powders were successfully coated on the surface of the
atomized Ni BMG powders.
Effect of Working Temperature on Microstructure and Mechanical Properties of Ultrafine Grained Al and Al-5vol.%SiCp Composite Processed by Accumulative Roll-Bonding
Authors: Lee Seong Hee , Chang Si Young , Oh Sung Tag
Published: March 2009

The effect of working temperature on microstructure and mechanical properties of
ultrafine grained monolithic Al and Al-5vol.%SiCp composite processed by accumulative roll
bonding (ARB) was studied. The ARB was performed up to eight cycles (an equivalent strain of
~6.4) without lubricant. The working temperature was varied from ambient temperature to 200
C. The samples processed at temperatures below 100C exhibited an ultrafine grained structure
over almost all regions. However, the samples processed at 200C showed an inhomogeneous
structure in which a few coarse grains due to an occurrence of conventional recrystallization is
partially seen. The tensile strength of both the monolithic Al and the composite decreased with
increasing the ARB working temperature. The variation of microstructure and mechanical
properties of the composite with the working temperature was compared to that of the
monolithic aluminum.
Powder Metallurgy of Nanostructured High Strength Materials
Authors: Eckert Jürgen , Scudino S. , Yu P. , Duhamel C.
Published: March 2009

Nanostructured or partially amorphous Al- and Zr-based alloys are attractive candidates for advanced high-strength lightweight materials. The strength of such materials is often 2 – 3 times higher than the strength of commercial crystalline alloys. Further property improvements are achievable by designing multi-phase composite materials with optimized length scale and intrinsic properties of the constituent phases. Such alloys can be prepared by quenching from the melt or by powder metallurgy using mechanical attrition techniques. This paper focuses on mechanically attrited powders containing amorphous or nano-(quasi)crystalline phases and on their consolidation into bulk specimens. Selected examples of mechanical deformation behavior are presented, revealing that the properties can be tuned within a wide range of strength and ductility as a function of size and volume fraction of the different phases.
Fabrication of Bi-2212/SrSO4 Composite Superconductors by Melting Powder Mixtures
Authors: Kim Kyu Tae , Jang Seok Hern , Lim Jun Hyung , Park Eui Cheol , Joo Jin Ho , Lee Hoo Jeong , Hong Gye Won , Kim Chan Joong , Kim Hye Rim , Hyun Ok Bae
Published: March 2009

We fabricated Bi-2212/SrSO4 composite superconductors by the melt casting process and
evaluated the effects of the powder mixing method and melting temperature on their microstructure
and superconducting properties. In the melt casting process, the Bi-2212 powders were mixed with
SrSO4 by hand-mixing (HM) and planetary ball milling (PBM) and then the powder mixtures were
melted at 1100°C~1200°C, solidified, and annealed.
We found that the powder mixture prepared by PBM was finer and more homogeneously mixed
than that prepared by HM, resulting in more homogeneous microstructure and smaller SrSO4 and
second phases after annealing. The critical current (Ic) also varied significantly with the powder
mixing method and the melting temperature. The Ic of the annealed rod prepared by PBM was 193
A at 77 K when melted at 1100°C, which is higher than that of the annealed rod prepared by HM
(132 A). This enhancement in the Ic value for the former is considered to be due to its more uniform
microstructure.
Characteristics of (Fe, M)S2 (M=Co, Ni, Mo) Composite Powders Fabricated by MCP
Authors: Jung Woo Hyun , Park Dong Kyu , Jung Kwang Chul , Suck Se Hoon , Ahn In Sup , Kim Ki Won
Published: March 2009

As the electrodes of secondary battery are made with sulfide composite powders,
excellent electrode system of environmental non-toxicity and with high specific energy density and
low material cost can be obtained. In this study, the (Fe, M)S2 composite powders was synthesized
by mechanochemical processes (MCP) in order to improve of the cycle life in bettery. The
formation of pyrite phase appreared at the case which adds nickel, but it was not observed in the
case where the transition metal was does not add but the transition metal such as cobalt,
molybdenum was added in stead. From charge-discharge test results, the initial discharge capasity
of (Fe, Ni)S2 electrode was 845 mAh/g. The initial discharge capasity of (Fe, Co)S2 electrode was
500mAh/g, but it showed a better cycle perfoemance than the case where the diffrent transition
metal was added.
Effect of Ag on the Thermoelectric Properties of Ag2Se Alloy Prepared by Mechanical Alloying Process
Authors: Min Wang Kee , Hwang H.D. , Lee C.H. , Park Ik Min , Park Yong Ho
Published: March 2009

The thermoelectric properties of Ag2Se and excess Ag alloys synthesized by mechanical
alloying process were studied. The absolute S value slightly decreased with the Ag content.
Contrary to that, the electrical conductivity (σ) increased with the Ag content. This was due to the
increased carrier concentration supplied by the excess Ag clusters. Below 280K, the σ value of the
excess Ag alloys is almost constant regardless of temperature, which means that the Ag excess
alloys is highly degenerated. At higher temperatures above 290 K, the intrinsic conduction behavior
for all materials is observed and the band gap energy for Ag2Se calculated from the slope of curve
in this higher temperature range is about 220 meV. The figure of merit value (Z) was increased by
the excess Ag, from 0.28/K (Ag2Se) to 0.91/K (Ag2.05Se0.95).
Fabrication of Continuously Porous t-ZrO2 Bodies Using Carbon Powder and Evaluate Their Biocompatibility
Authors: Gain Asit Kumar , Song Ho Yeon , Lee Byong Taek
Published: March 2009

The continuously porous t-ZrO2 bodies were fabricated by the extrusion process. The
average pore size of the 2nd passed samples was about 260μm in diameter. The maximum bending
strength value was about 177MPa. For the evaluation of their biocompatibility, human osteoblast
like MG-63 cells and osteoclast like Raw 264.7 cells were cultured on the top surface of the porous
t-ZrO2 bodies. The osteoblast cells were grown with spindle shape, condensed circular growth and
three-dimensional network type. In contrast, the osteoclast cells appeared with pebble stone
structure.
Segregation-Free Premixes for Increased Productivity and Improved Performance
Authors: Poszmik George , Narasimhan Kalathur S.
Published: March 2009

Powder mixes used in the P/M industry contain ingredients of substantially different
particle sizes and specific gravities that have a strong tendency to segregate during handling.
Reducing or eliminating this segregation is essential for the part producer to achieve consistent
precision and optimum performance. Treating the premixes with polymer binders helped to resolve
this problem. Binder/lubricant systems have been developed that provide improved flow rates
combined with increased green densities and green strengths. A review of these developments will
be presented and their impact on overall productivity and performance will be outlined.
Experimental Investigation and Modeling of the Specific Enthalpy Distribution in a Spray Cone
Authors: Ellendt N. , Uhlenwinkel Volker
Published: March 2009

In Spray Forming, specific enthalpy is a key parameter in the deposition process as it influences the thermal condition of the impinging droplets as well as that of the deposit surface. An empirical model for the distribution of specific enthalpy in the spray cone was developed as an easy to handle alternative to numerical models with which the descriptive partial differential equations are solved numerically. The model results were compared with the experimental data to validate its applicability.
Present Status and Future Prospects of Cold Spraying
Authors: Gaertner Frank , Schmidt Tobias , Kreye Heinrich
Published: March 2009

Cold spraying is a fairly new coating technique, which within the last decade attracted
serious attention of research groups and spray companies. As compared to thermal spraying, the low
process temperatures in cold spraying result in unique coating properties, which promise new applications.
Since particles impact with high kinetic energy in the solid state, new concepts to describe
coating formation are requested to enable the full potential of this new technology. The present contribution
gives a brief review of current models concerning bonding, supplying a description of the
most influential spray parameters and consequences for new developments. With respect to spray
forming by cold cold spraying, microstructures and thick, further machineable structures are presented.
Study on Metal/Diamond Binary Composite Coatings by Cold Spray
Authors: Kim Hyung Jun , Jung D.H. , Jang J.H. , Lee Chang Hee
Published: March 2009

Metal/diamond binary composite coatings on Al substrate without grit blasting were deposited by cold spray process with in-situ powder preheating. Microstructural characterization of the as-sprayed coatings with different diamond size, strength and with/without Ti coating on diamond was carried out by OM and SEM. The assessment of basic properties such as tensile bond strength and hardness of the coatings, and the deposition efficiency was also carried out. Particular attention on the composite coatings was on the diamond fracture phenomenon during the cold spray deposition and the interface bonding between the diamond and the Fe-based metal matrix.
Characteristics of Laser Aided Direct Metal Powder Deposition Process for Nickel-Based Superalloy
Authors: Zhang Kai , Liu Wei Jun , Shang Xiao Feng
Published: March 2009

Laser additive direct deposition of metals is a new rapid manufacturing technology, which combines with computer aided design, laser cladding and rapid prototyping. The advanced technology can build fully-dense metal components directly from CAD files without a mould or tool. With this technology, a promising rapid manufacturing system called “Laser Metal Deposition Shaping (LMDS)” is being constructed and developed. Through the LMDS technology, fully-dense and near-net shaped metallic parts can be directly obtained through melting coaxially fed powder with a laser. In addition, the microstructure and mechanical properties of the as-formed samples were tested and analyzed synthetically. The results showed significant processing flexibility with the LMDS system over conventional processing capabilities was recognized, with potentially lower production cost, higher quality components, and shorter lead time.
Fabrication of Porous Structure of BCP Sintered Bodies Using Microwave Assisted Synthesized HAp Nano Powder
Authors: Youn Min Ho , Paul Rajat Kanti , Song Ho Yeon , Lee Byong Taek
Published: March 2009

Using microwave synthesized HAp nano powder and polymethyl methacrylate (PMMA) as a pore-forming agent, the porous biphasic calcium phosphate (BCP) ceramics were fabricated depending on the sintering temperature. The synthesized HAp powders was about 70-90 nm in diameter. In the porous sintered bodies, the pores having 150-180 μm were homogeneously dispersed in the BCP matrix. Some amounts of pores interconnected due the necking of PMMA powders which will increase the osteoconductivity and ingrowth of bone-tissues while using as a bone substrate. As the sintering temperature increased, the relative density increased and showed the maximum value of 79.6%. From the SBF experiment, the maximum resorption of Ca2+ ion was observed in the sample sintered at 1000°C.
Analysis of Particle Rearrangement during Sintering by Micro Focus Computed Tomography (µCT)
Authors: Nöthe Michael , Schulze Matthias , Grupp Rainer , Kieback Bernd , Haibel A. , Banhart John
Published: March 2009

The decrease of the distance between particle centers due to the growth of the sinter necks can be explained by the well known two-particle model. Unfortunately this model fails to provide a comprehensive description of the processes for 3D specimens. Furthermore, there is a significant discrepancy between the calculated and the measured shrinkage because particle rearrangements are not considered. Only the recently developed analysis of the particle movements inside of 3D specimens using micro focus computed tomography (μCT), combined with photogrammetric image analysis, can deliver the necessary experimental data to improve existing sintering theories. In this work, μCT analysis was applied to spherical copper powders. Based on photogrammetric image analysis, it is possible to determine the positions of all particle centers for tracking the particles over the entire sintering process and to follow the formation and breaking of the particle bonds. In this paper, we present an in-depth analysis of the obtained data. In the future, high resolution synchrotron radiation tomography will be utilized to obtain in-situ data and images of higher resolution.
Assessment of the Corrosion Behavior of a Sintered Al-Cu-Mg Alloy in Aeronautical Environments as a Function of the Heat Treatment
Authors: Sánchez-Majado S. , Torralba José M. , Jiménez-Morales Antonia
Published: March 2009

In the present work it has been studied the corrosion performance of a powder
metallurgical aluminum alloy in aeronautical environments as a function of heat treatment. For this
purpose an Al-Cu-Mg prealloyed powder was uniaxially pressed at 600 MPa followed by sintering
at 590°C in nitrogen for 60 minutes. Subsequently sintered samples were heat treated to the T4 and
T6 state. Corrosion behaviour was assessed by means of potentiodynamic polarization (PPT) in
Dilute Harrison solution (DHS), which is considered to closely emulate the atmospheric
environment for aircraft. PPT results for the equivalent wrought counterpart, AA2024 in its typical
heat treatment for aeronautical applications T3, are also presented for comparison. The
microstructure of each sample has been examined by Scanning Electron Microscopy (SEM) and
Energy-Dispersive analysis of X-ray (EDX).
Similar corrosion performance was observed for both the as sintered sample and its equivalent
wrought counterpart, while corrosion resistance of the PM materials was improved by the heat
treatment, especially in the T4 state.
Grain Growth Kinetics of Cobalt-Doped SnO2 by Varying Nb2O5 Content
Authors: Chang Dong Gyu , Lee Joon Hyung , Kim Jeong Joo
Published: March 2009

SnO2 ceramics were co-doped with the aliovalent ions of CoO and Nb2O5 and the grain growth behavior of the SnO2 was investigated. When only CoO was doped, the grain growth exponent of SnO2 was 3. As the amount of Nb2O5 increased, the exponent changed from 3 to 2 when 0.505 mol% of Nb2O5 was added. The further addition of Nb2O5 changed the exponent from 2 to 3. When Nb2O5 content was 0.505 mol%, of which the grain growth exponent was 2, it is believed that an iso-electric point is formed without grain boundary segregation, since the respective space charges, generated by Nb5+ and Co3+ might compensate each other.
Microstructure and Tensile Properties of Tungsten Heavy Alloys
Authors: Islam Syed Humail , Qu Xuan Hui , Akhtar Farid , Feng Pei Zhong , He Xin Bo
Published: March 2009

Mechanical properties of tungsten heavy alloys are dependent on many factors including
the purity of the raw materials, their tungsten content, manufacturing parameters and the
microstructure of the final compact. The main object of this research was to examine the effect of
sintering conditions (temperature and time) on the microstructure of tungsten heavy alloys and how
the resulting modification of the microstructure can be used to optimize their mechanical properties.
Alloys composed of 88%, 93% and 95% wt. of tungsten with the balance of Ni: Fe in the ratio of
7:3 were consolidated into green compacts. Samples of each of the three resulting alloys were
sintered at different temperatures (1350°C,1450°C and 1500 0C) for different sintering holding
times (3 and 30 minutes) in hydrogen atmosphere. Standard metallographic procedures were used to
obtain SEM micrographs. The mechanical properties of tungsten heavy alloys were found to be
dependent on the microstructural parameters such as W particle size, solid volume fraction,
connectivity and w-w contiguity. It was shown that the mechanical properties of the alloys, and
especially their ductility, are harmed when tungsten grains are contiguous.
Hardenability of Low Alloy Sintered Mn Steels
Authors: Zendron Marianna , Molinari Alberto , Girardini Luca
Published: March 2009

Manganese is an alloying element that improves the strength of ferrite and the
hardenability of steels. It could be a valid substitute for expensive and toxic elements (as Mo and
Ni) in sintered steels, increasing mechanical properties.
The hardenability of four low alloy Mn steels was studied to establish the influence of manganese
on the heat treatments. The effect of Mn on steel hardenability is well established. The multiplying
hardenability factors in the range 0.05-1% Mn are known, and so the hardenability of the alloy to be
investigated can be predicted. The Grossmann approach was adopted, which uses cylinders with
different diameters to induce different gradients of cooling rate in the cross section. Quenching
experiments were carried out in the vacuum furnace, recording the actual cooling rate (on the
external surface and in the central axis). The maximum cooling rate attainable is 10 K/s. Hardness,
microhardness and microstructure profiles were determined, and correlated to cooling rate for the
different alloying elements and C contents.
The correlation of microstructure and microhardness to the actual cooling rate makes the results
independent on the process parameters and applicable to each industrial condition, once the actual
cooling rate in the parts is known.
Study for the Development of Fe-NbC Composites by Advanced PM Techniques
Authors: Gordo Elena , Gómez B. , González Roberto , Ruiz-Navas E.M.
Published: March 2009

The development of Fe-based metal matrix composites (MMCs) with high content of
hard phase has been approached by combining the use of advanced powder metallurgy techniques
like high-energy milling (HEM), cold isostatic pressing (CIP) and vacuum sintering. The most
innovative is the use of HEM for the obtaining of a composite powder avoiding the formation of
clusters in the microstructure of the sintered material, and the study of hardenability of sintered
materials. A 30 % vol. of NbC particles was mixed with Fe powder by HEM in a planetary mill
under Ar atmosphere to prevent oxidation. The optimal milling time was determined by sampling
every two hours until 10 hours of milling, characterising the powder by the observation of
morphology and microstructure by scanning electron microscopy (SEM), and controlling the carbon
content by a LECO analyser. Composite powders were compacted by CIP and then sintered in
vacuum at temperatures between 1300 °C and 1375 °C, during 30 min and 60 min. The variation of
density, hardness and carbon content with sintering temperature and time, besides the
microstructural changes observed, permits to find the optimal conditions of processing. Afterwards,
a heat treatment study was performed to study the hardenability of the cermet.
Effect of Repeated Quenching Heat Treatment on Microstructure and Dry Sliding Wear Behavior of Low Carbon PM Steel
Authors: Güral Ahmet , Tekeli Süleyman , Özyürek Dursun , Gürü Metin
Published: March 2009

The effect of repeated quenching heat treatment on microstructure and dry sliding wear behavior of low carbon PM steel was investigated. For this purpose, atomized iron powder was mixed with 0.3 % graphite and 1 % Ni powders. The mixed powders were cold pressed and sintered at 1200°C for 30 min under pure Ar gas atmosphere. Some of the sintered specimens were intercritically annealed at 760°C and quenched in water (single quenching). The other sintered specimens were first fully austenized at 890°C and water quenched. These specimens were then intercritically annealed at 760°C and re-quenched in water. The martensite volume fraction in the double quenched specimens was higher than that of the single quenched specimen. Wear tests were carried out on the single and double quenched specimens under dry sliding wear condition using a pin-on-disk type machine at constant load and speed. The experimental results showed that the wear coefficient effectively decreased in the double quenched specimen.
Sintered Structural Cu-Ni-Mo-C Low Alloyed Steels with Small Niobium Additions
Authors: Orban Magdalena , Orban Radu L.
Published: March 2009

This paper investigates the possibilities of niobium using for the mechanical properties of
the common low alloyed Cu-Ni-Mo-C structural sintered steels enhancing by a similar technique
with that used in the classical HSLA steels obtaining. For this purpose, both thermodynamic and
experimental investigations were carried out, their results showing that the added Nb to these steels
form at sintering in a nitrogen containing atmosphere, rather then the other alloying elements,
carbides, nitrides, carbonitrides. They are solved in austenite and precipitate at the sintered steels
cooling / artificial aging, forming precipitates of an expected strengthening effect. The results for
0.2 ÷ 1.0 % fine Nb powder and 0.3 % graphite additions to Distaloy AB powder cold compacted
and sintered in dissociated ammonia proved that such a strengthening effect, which leads to higher
mechanical properties of the processed steels than of the Cu-Ni-Mo-C ones, can be achieved.
The Sintering Behaviour of Fe-Mn-C Powder System, Correlation between Thermodynamics and Sintering Process, Mn Distribution and Microstructure
Authors: Hryha Eduard , Dudrová Eva
Published: March 2009

To study of the sintering behaviour of the Fe-0.8Mn-0.5C powder system the cylindrical
specimens with a density of ~7.0 g/cc were sintered in container at the temperature of 11200C for 30
min in a gas mixture of 7%H2/93%N2 with the inlet dew point of -600C. The composition (CO/CO2-
content) and the dew point of the flowing and “container micro-climate” atmospheres during the
whole sintering cycle were monitored. It was shown, that carbothermical reduction and formation
esp. CO/CO2 occurs in two different temperature ranges. Three peaks of dew point profile also can
be distinguished during sintering cycle. Following sintering the changes of ferromanganese
particles, Mn-content distribution and microstructures around the Mn-source were micro-analytical
evaluated at cross-section of specimens using the SEM with EDX microanalyses. The results
showed that manganese travels through porous iron matrix up to ~60 μm. The type of local
microstructure constituents is determined by the local Mn- and C contents.
Microstructure and Properties of Zn61Al34M5 Alloy Produced by Rapid Solidification and Warm-Compacting Sintering Process
Authors: Lou Hai Yi , Lu Wei , Yang Lei , Yan Biao
Published: March 2009

Microstructure and mechanical properties of a newly developed Zn61Al34M5 (M=Cu, Si,
RE, et al.) alloy obtained by warm-compacting sintering technique were studied using optical
microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy
(EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) associated with
measurements of mechanical properties. The results showed that the new alloy consisted of α-phase
and η-phase and have good plasticity; its hardness increased by 10%~20% and density decreased by
about 16% as compared with those of the traditional cast Zn-Al alloys.
Large Scale Production of Nanoparticles by Laser Pyrolysis
Authors: Reau Adrien , Guizard Benoit , Mengeot Cyrille , Boulanger Loic , Ténégal François
Published: March 2009

Laser pyrolysis is a very suitable gas-phase process for the synthesis of a wide range of
nanoparticles at laboratory scale. The principle of the method is based on the decomposition of
gaseous or liquid reactants by a high power CO2 laser followed by a quenching effect. The literature
reports the possibility to produce carbides, nitrides, oxides, metals and composites nanoparticles by
this process. This paper reports a study of the effect of the laser intensity (using an innovative
optical system) and of the gas flow rates on the characteristics (size and structure) of silicon carbide
(SiC) nanoparticles produced at pilot scale (up to 1.13 kg/h) by using a mixture of silane (SiH4) and
acetylene (C2H2). It has been shown that the decrease of the gas flow rate favors the increase of the
mean grain size of the particles and that the increase of the laser intensity seems to provoke an
increase of the mean crystal size and/or crystal number.
Investigation of Microstructure Inhomogeneity in SiCp-Reinforced Aluminum Matrix Composites
Authors: Gácsi Zoltán , Gür C. Hakan , Makszimus Andrea , Pieczonka Tadeusz
Published: March 2009

The type, volume fraction, size, shape and arrangement of embedded particles influence
the mechanical properties of the particle reinforced metal matrix composites. This presents the
investigation of the SiC particle and porosity distributions in various aluminum matrix composites
produced by cold- and hot-pressing. The microstructures were characterized by optical microscopy
and stereological parameters. SiC and porosity volume fractions, and the anisotropy distribution
function were measured to establish the influence of the consolidation method. The results showed
that SiC particles are arranged in a different way during the cold- and hot pressing. The amount of
porosity in the hot pressed specimens is always lower than that in the cold pressed ones; however,
cold pressed and sintered samples have few large pores whereas more fine pores develop in the hot
pressed ones. In the cold pressed specimens, heating rate for sintering influences the final density,
the amount of porosity increases parallel to the increase in the relative particle size; and coating of
SiC particles with Cu lowers the porosity while Ni-coating does not result in such an effect.
High Performance Self-Reinforced Polypropylene Composites
Authors: Bárány Tamás , Izer András , Czigány Tibor
Published: March 2009

Highly oriented polypropylene fiber reinforced random PP copolymer composites were
produced by film-stacking method. The reinforcing fibers were carded and needle punched and the
film-stacked packages were compression molded at different processing temperatures
(T=150…170°C) and holding times (t=90…600 s). For characterization of the consolidation of the
composite sheets interlaminar strength was determined and further the polished sections were
studied by light microscopy. Static tensile and dynamic impact (instrumented falling weight impact
- IFWI) tests were performed on the specimens cut from the sheets. It was established that the best
properties can be achieved when the processing conditions are 165°C and 90s. Increasing
temperature and improving consolidation reduced perforation impact energy owning to better
fiber/matrix adhesion and the smaller extent of delamination between the film-stacked layers.
Production and Examination of Double Composites
Authors: Kientzl Imre , Dobránszky János
Published: March 2009

Nowadays, metal matrix composites have many new areas of application owing
to their excellent properties - for example their great tensile strength and high Young’s
modulus with its relatively low weight.
The aim of this work is to an examination of ceramic fibre-reinforced aluminium matrix
composite wires made via continuous process. Furthermore, the research will outline the
double composite products that are composite wire-reinforced metal matrix composites.
Double composites are examined by tensile tests, bending tests and pressing tests. A
lot of research has been done on the thermal aging of composite wires and on measuring
the impact energy of thermal-aged specimens.
The mechanical test shows us that structures reinforced with the composite wires have
a notably higher load-carrying capacity than does a structure reinforced directly with fibres
or a structure without any reinforcement.
Determining the Anisotropy Coefficients of an Ultra Fine Grained Al6082 Alloy Subjected to ECAP
Authors: Krállics György , Fodor Arpad
Published: March 2009

Bulk Al6082 alloy is subjected to ECAP using route Bc. This paper focuses on the
determination of the anisotropy coefficients and equivalent stress-equivalent strain curve using
continuum mechanics equations. Assuming the material to be rigid-plastic, the parameters of the
constitutive equation are determined with the aid of measuring the deformation and the uniaxial
yield stress during upsetting tests in three perpendicular directions.
Changes of Subsurface Structure of Materials Developed during Sliding Friction
Authors: Bollók P. , Kozma M.
Published: March 2009

It is well known that during sliding friction the properties of rubbing surfaces are changed owing to transformations caused by applied loads, friction and wear processes. In the last years many research works were devoted to reveal the properties of the surfaces transformed during the friction and wear at the Budapest University of Technology and Economics in the Department of Machine Design. During these investigations the conditions of developing beneficial transformed surface layers and their operating boundaries were determined by experiments on metal sliding pairs in laboratory. The conditions of evolving large-scale adhesion junctions, scuffing and seizure were investigated on heavy-loaded surfaces at slow sliding velocity. During the experiments hard steel balls slid on dry or lubricated metal disks. Coefficient of friction and wear tracks were measured and structures and damages of sliding surfaces were evaluated using profilometry, SEM and normal microscope photographs, and micro-hardness measurement.
Comparison of Different Theoretical Models to Experimental Data on Viscosity of Binary Liquid Alloys
Authors: Budai I. , Benkő Mária Z. , Kaptay György
Published: March 2009

Six different theoretical equations are compared in the present paper with experimental
data, measured for 28 binary liquid metallic systems. General conclusions are drawn on the ability
of the different theoretical models to describe the concentration and temperature dependence of the
viscosity of liquid alloys. A new equation is derived, being able to predict the viscosity in multicomponents
alloy even if the viscosities of the pure components are not known.
Study of the Tempcore Process for the Production of High Resistance Reinforcing Rods
Authors: Niño O. , Martínez D. , Lizcano C. , Guerrero-Mata Martha Patrizia , Colás Rafael
Published: March 2009

The process known as Tempcore is used to produce high resistance rods by the formation of a surface layer of quenched and tempered martensite that surrounds a core made of ferrite and pearlite. Such a mixed structure is result of processing hot rolled rods through waters headers that reduce the temperature at the surface below that for the transformation into martensite. This structure is tempered by the heat flowing from the core of the rod, which transforms into ferrite and pearlite while the rod is in the cooling beds. Such processing produces a significant increase in yield and ultimate tensile strength, while maintaining adequate ductility. The economic advantages of this process are huge in comparison with those that require alloying elements or further metal working to improve mechanical properties. A series of experimental trials were carried out in a pilot plant in which parameters such as reheating temperature, water flow and processing time were varied to study their effect on the mechanical properties of carbon steel rods and on the structures formed in the bars. The study is being complemented by the thermal modelling by the finite element method.
Aperiodic Deformation Occurring as a Result of Thermoplastic Instability of Metals
Authors: Pálmai Zoltán
Published: March 2009

The author developed a three-dimensional model for the description of fast plastic deformation of metals in the case of cutting. Shear strain occurring as a result of shear stress has a reverse effect on stress, while the temperature of the material is increasing. These counteracting effects may lead to thermomechanic instability, which may result in aperiodic chaotic conditions besides periodic fluctuation due to the non-linear nature of the process. Apart from bifurcation and multi-cycle periodic deformation, the model also describes aperiodic chaotic deformation, which is proven by experimental results.
3D Characterization of Continuously Cast Slabs
Authors: Réger Mihály , Verő Balázs , Szélig Árpád
Published: March 2009

This paper deals with the characterization of solidification, cooling and expected
properties of continuously cast slabs. Semi-empirical models based on theoretical consideration and
on the results of heat transfer model are used for characterization of the following: surface and inner
temperature distribution of the cast semis, liquid sump depth and shape, liquid motion intensity
resulting in centerline segregation, parameters of the primary dendritic structure (primary and
secondary dendritic spacings, columnar to equiaxed transition position, CET). This method
provides an opportunity to make a realistic comparison between the solidification and final
properties of semis with different chemical compositions as a function of applied casting
technologies. The final goal of this research activity in the future is to define a comprehensive
quality function for optimizing continuous casting technology.
Numerical Analysis of Sliding Friction Behaviour of Rubber
Authors: Soós Eniko , Goda Tibor
Published: March 2009

A study has been made of asperity interaction of unlubricated steel/rubber sliding pair.
The aim is to study the effect of the internal friction (hysteresis) of rubber on the friction force. In
the two-dimensional finite element analysis, asperities are modeled by cylinders and both the
interfacial adhesion and the friction at steel-rubber interface are neglected. Rate-dependent material
behavior of rubber is described, as a first approximation, by a three-parameter Zener-model. It is
found that the viscoelastic properties of rubber have a strong influence on the hysteresis component
of friction. Distribution of energy loss generated over a cycle of contact in the rubber asperity is
also studied. It is concluded that the energy dissipation is most intensive at a certain depth below the
rubber surface.
The Experiences of Activated Tungsten Inert Gas (ATIG) Welding Applied on 1.4301 Type Stainless Steel Plates
Authors: Sándor Tamás , Dobránszky János
Published: March 2009

The TIG welding has a high disadvantage against the substantially high productivity
welding procedures. This is why there were continuously going on several trials to improve
the productivity of the TIG welding. The Activated Tungsten Inert Gas welding (ATIG welding)
is one of these trials. Application experiments of ATIG welding on austenitic stainless
steel plates will be presented. The main problems which appear when using the ATIG welding
are the choosing of tungsten electrode, the suggested fitting of parts for the joining, portioning
of the activating flux and the sensitivity for the measure of flux. They are extremely
important to apply the ATIG welding and the results will be presented by this work. In the
second half of this paper the comparison of the productivity differences between TIG and
ATIG welding; mechanical properties, microstructure and corrosion resistance of welded
joints will continue. Finally the evaluating the results and trying to classify the ATIG welding
amongst the modern and most productive welding procedures is detailed. Furthermore advises
for using the ATIG welding for suitable applications are represented.
The Role of Niobium in Lightweight Vehicle Construction
Authors: Mohrbacher Hardy , Klinkenberg Christian
Published: March 2009

Modern vehicle bodies make intensive use of high strength steel grades to improve the weight and the mechanical performance simultaneously. A broad range of medium and extra high strength steel grades is available. These steel grades have different characteristics concerning strength, formability and weldability. For many steel grades microalloying by niobium is the key to achieve their characteristic property profile. In HSLA steels niobium enhances the strength primarily by grain refinement. In interstitial free high strength steels niobium serves as a stabilizing element and also assists in obtaining the bake hardening effect. Some modern multiphase steels rely on niobium to achieve additional strength via grain refinement and precipitation hardening. Microstructural control provides a way to further optimize properties relevant to automotive processing such as cutting, forming and welding. The relevance of niobium microalloying in that respect will be outlined.
Actual Feed Rate per Tooth at Micro Milling
Authors: Takács Márton , Verő Balázs
Published: March 2009

Miniature structures can be produced economically by micro end milling as single parts or parts in small and medium lot sizes. The micro end milling process has to be analyzed particularly for the purpose of applying a well controlled and repeatable process. There are many specific characteristics in the micrometric scale of dimensions, whose role is negligible at the conventional processing technologies. One of these special features of micro end milling is the observation that the set value of the feed rate per tooth generally differs from the thickness of the actual removed material layer. Feed rate per tooth is practically defined as the distance, which is run by the edge lengthwise of the groove during one revolution of the tool. Accordingly the feed rate per tooth corresponds to the thickness of the material layer removed by one edge of the tool. This correspondence exists at conventional manufacturing methods but not at micro end milling. This fact is attended by more special features of the micro end milling process, which are multiple cutting, different machining conditions of the edges and tool deflection. This paper introduces the results of improvement of my earlier research on this field [1]. An enhanced flowchart was constructed, which provides the calculation of the thickness of the actual removed material layer at micro end milling under all possible circumstances.
Self-Lubrication and Wear Behavior of TiC/a-C:H Nanocomposite Coatings
Authors: Pei Yu Tao , Huizenga P. , Galvan Damiano , de Hosson Jeff T.M.
Published: March 2009

Advanced TiC/a-C:H nanocomposite coatings have been produced via reactive deposition
in a closed-field unbalanced magnetron sputtering system. In this paper, we report on the
tribological behavior of TiC/a-C:H nanocomposite coatings in which ultra-low friction is tailored
with superior wear resistance, being two properties often difficult to achieve simultaneously. In-situ
monitoring the wear depth at nanometer scale reveals that the self-lubricating effects are induced by
the formation of transfer films on the surface of ball counterpart. In addition, the CoF of TiC/a-C:H
nanocomposite coatings decreases with decreasing relative humidity. This phenomenon can be
interpreted in terms of water molecule interactions with the wear track. The influence of the volume
fraction and grain size of TiC nanocrystallites on the coating properties has been examined. A
superior wear resistance at a level of 10-17 m³/(N m lap) has been achieved under the condition of
super-low friction and high toughness, both of which require fine TiC nano-particles (e.g. 2 nm) and
a wide matrix separation that must be comparable to the dimensions of the nano-particles.
Evaluation with Surface Analysis Equipment, of Casting Defects in Cast Iron Articles (review)
Authors: Kambayashi H. , Kurokawa Y. , Ota H. , Hoshiyama Yasuhiro , Miyake Hidekazu
Published: March 2009

Authors have reported theses concerning the cast defect for publication in journal of Japanese Foundry
Engineering Society and AFS Transactions. This is a review of these reports. There are various factors in
the casting defect that occurs in the article of casting metal, and specific of the generation factor is difficult.
Moreover, it is necessary to decrease the casting defect to reduce the cost of goods manufactured and
energy of production. It is effective to the evaluation and the classification method of the casting defect to
employ Scanning Electron Microscopy with Energy Dispersion Spectrometer (SEM-EDS) and Electron
Probe Micro-Analysis (EPMA). Casting defects chose the one that the incidence was high and specific of
the generation factor is difficult, and the pinhole defect and inclusion defects were classified according to
the generation factor, and penetration defect showed the relation of physical factor, chemical factor, and
those interactions, and examined whether specific of the factor was possible by the surface analysis
equipment about other defects (Blow hole, Shrinkage, Orange peel, Cold shut, Cracks and Veining).
Microstructural Evolution of Durable Thermal Barrier Coatings with Hf and/or Y Modified CMSX-4TM Superalloy Substrates
Authors: Liu J. , Sohn Yong Ho , Murphy K.S.
Published: March 2009

Thermal cyclic lifetime and microstructural degradation of thermal barrier
coatings (TBCs) with (Ni,Pt)Al bond coat and Hf- and/or Y-modified CSMX-4
superalloy substrates were examined. Thermal cyclic lifetime of TBCs was measured
using a furnace thermal cycle test that consisted of 10-minute heat-up, 50-minute dwell at
1135°C, and 10-minute forced-air-quench. TBC lifetime was observed to improve from
600 cycles to over 3200 cycles with appropriate Hf- and/or Y-alloying of CMSX-4
superalloys. This significant improvement in TBC lifetime is the highest reported lifetime
in literature with similar testing parameters. Cross-sectional microstructure of TBC
specimens were examined by scanning electron microscopy (SEM) after the spallation
failure. While undulation of TGO/bond coat interface (e.g., rumpling and racheting) was
observed to be main damage mechanisms for TBCs on baseline CMSX-4, the same
interface remained relatively flat for durable TBCs on Hf- and/or Y-modified CSMX-4.
The parabolic growth constant of the TGO scale was slightly lower for TBCs with Hfand/
or Y-modified CSMX-4.
Mechanical and Electrochemical Properties of Plasma Electrolytic Oxide Coatings on Magnesium Alloys
Authors: Chang Si Young , Kim Ye Lim , Song Byung Heum , Lee Jae Ho
Published: March 2009

Ceramic coatings were synthesized on pure magnesium, binary Mg-Al and Mg-Zn alloys
by plasma electrolytic oxidation (PEO) technique, and their mechanical and electrochemical
properties were investigated. The coatings showed porous microstructure and some volcano top-like
pores on the surface. The coatings on Mg-Al alloys consisted of MgO, MgAl2O4 and Al2O3. In the
coatings on Mg-Zn alloys, MgO and ZnO were detected. The hardness and wear resistance showed
slight dependence on Al content but no tendency to increase with increasing Zn content. The coated
Mg alloys with Al, Zn showed better corrosion resistance in 3.5%NaCl solution but poor corrosion
resistance in methyl alcohol, compared to the coated pure Mg.
Surface Modification Technique Using Interfacial Reaction between Ti-Al Alloy and Steel
Authors: Morizono Yasuhiro , Nishida Minoru , Kodama Yoshikazu , Yamamuro Takateru , Ohno Yasuhide
Published: March 2009

Diffusion bonding of Ti and Ti-Al (Ti-10, 20 and 40 mol%Al) alloys to high carbon steel
was carried out at 1073 and 1273 K for 3.6 ks in a vacuum. It has been found that the joint with Ti-20
mol%Al alloy is separated in the vicinity of the interface promptly after the bonding treatment at 1273
K. Such a phenomenon could not be observed in other Ti-Al alloy/steel joints, and the Ti-20 mol%Al
alloy/steel joint bonded at 1073 K showed a high strength of about 170 MPa. Therefore, this
phenomenon depends on the bonding temperature and the composition of the Ti-Al alloys. From the
observation results of the interface, it is thought that the diffusion of constituent elements across the
interface is part of the reason for the separation phenomenon. The separated surface of the Ti-20
mol%Al alloy side showed diffraction peaks of TiC phase by XRD. Its Vickers hardness was about
1200 and approximately 4 times higher than that before the bonding treatment. It is expected that the
separation phenomenon at the Ti-20 mol%Al alloy/steel interface serves surface modification of
titanium materials, which show poor wear resistance.
Improvement in Wear Resistance of Nano WC-Co Coatings Fabricated by Detonation Gun Spraying
Authors: Park S.Y. , Kim Moon Chul , Park Chan Gyung
Published: March 2009

Nano structured WC-Co coatings with carbide size of 100−200nm were fabricated by
detonation gun spraying. The fabricated nano coatings showed improved hardness and wear
resistance compared to micron WC-Co coatings. Considerable phase decomposition of WC to W2C
and amorphous phase in nano coatings was detected, which is known to degrade wear resistance of
coatings. In order to improve the wear resistance of the coatings by recovering of dissociated
carbide phases, post heat treatment was conducted in Ar environment at temperature range of
400−900°C. Harness, fracture toughness and wear resistance of nano coatings were significantly
improved by post heat treatment. The improved properties were elucidated and discussed in terms
of microstructure and phase compositions.