bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Hybrid Sandwich Panel with Aluminum Foam Core and Carbon Fiber Reinforced Plastic Face Sheets under Three-Point Bending
Authors: Mohan K. , Yip Tick Hon , Sridhar Idapalapati , Seow H.P.
Published: March 2009

Aluminum foams are very popular material for structural applications because of its attractive combination of properties. Structural performance of those foams can be enhanced by bonding them between strong and stiff face sheets such as carbon fiber reinforced plastics (CFRP). The response of hybrid sandwich panels comprising aluminum foam core and CFRP face sheets were investigated under three-point bending and measured response is verified with finite element numerical simulations. Core indentation and core shear, failure modes are identified. Experimentally measured elastic stiffness and failure load of thee tested beams were found to be in good agreement with the numerical simulation and analytical predictions.
Mixed Phase Behavior in Hole-Doped Perovskite Materials
Authors: Nguyen X.P. , Le V.B.
Published: March 2009

MZFC, MFC magnetizations, χac susceptibility and resistance measurements have been carried out for various polycrystalline compounds of (AA’)(BB’)O3 perovskites with A = La, (Nd,Y); B = Mn,Co; A’ = Sr,Ca and B’= Fe, Ti. Analyses have been done to elucidate the metallic ferromagnetism (FM) established by Double Exchange interaction between B+3 ion and the B+4 ion that is induced by the substitution of A’ for A. It is shown that there is no ‘pure’ FM ordering existing in the compounds, in other words the materials consist of a FM and a non-FM phase. In case when the latter is an AFM phase, the coexistence and competition of the two phases result in spin-glass like appearances. Such phenomena have been observed in several compounds of both single- and/or mixed-element at B site. The studies on substitution of Mn for Co in La0.7Sr0.3Co1- yMnyO3 show no DE interaction between the two magnetic ions, which results in not only SG behavior at y = 0.1 concentration but a clear evidence on a phase separation in the high y region. An analysis of M(H,T) curves for this region suggests a structural scenario that the FM phase forms as islets (of volume fraction as small as 2.7 – 8.6%) embedded in isolating AFM matrix. For the case while B’= Ti the inhomogeneity evidence appears as an enhancement of the Low Field MagnetoResistance, which is commonly understood as an intergranular effect.
Effect of Hybrid Metallic and Ceramic Reinforcements on the Properties of Pure Magnesium
Authors: Ugandhar S. , Gupta Manoj , Sinha S.K.
Published: March 2009

In the present study, hybrid magnesium composites reinforced with SiC and Ti
particulates were successfully synthesized using an innovative disintegrated melt deposition technique followed by hot extrusion. Extruded samples were characterized for their microstructural, thermal and mechanical properties. Systematic investigations on the microstructure of the extruded
samples revealed retention and uniform distribution of SiC and Ti particulates, good matrixreinforcement interfacial integrity and limited porosity. Results of properties characterization revealed a decrease in the average coefficient of thermal expansion, and an increase in the hardness, dynamic modulus and 0.2% yield strength with an increase in amount of reinforcement. Ductility,
however, was adversely affected. An attempt is made to correlate the presence of hybrid (ceramic + metallic) reinforcements with the improved properties of composites synthesized.
Studies on Polyaniline: Polyethyleneterephthalate Films
Authors: Ahmed A.A. , Mohammad Faiz
Published: March 2009

The films of polyaniline:polyethyleneterephthalate films were prepared by polymerizing aniline soaked in polyethyleneterephthalate films of different thicknesses. The films were characterized by FTIR as well as for their electrical properties. The electrical properties of the films were observed to be of good quality as almost all the films showed a great increase in their electrical conductivity from insulator to semiconductor region after doping with hydrochloric acid. All the films in their doped state follow the Arrhenius equation for the temperature dependence of electrical conductivity from 35 to 115oC. The thermooxidative stability was studied by thermogravimetry and differential thermal analysis. The stability in terms of dc electrical conductivity retention was also studied under ambient conditions by two slightly different techniques viz. isothermal and cyclic techniques. The dc electrical conductivity of the films was found to be stable below 90oC for all the films under ambient conditions.
Electron Momentum Density of Hexagonal Magnesium Studied by Compton Scattering
Authors: Brancewicz Marek , Reniewicz Henryk , Andrejczuk Andrzej , Dobrzyński Ludwik , Żukowski Eugeniusz , Kaprzyk Stanisław
Published: March 2009

Directional Compton profiles of single crystal of hcp magnesium have been measured with scattering vectors along the [10 10], [1120] and [0001] directions in reciprocal space (special directions ΓΜ, ΓΚ, ΓΑ) using high-energy (662 keV) gamma radiation from a 137Cs isotope source. The experimental data were compared with corresponding theoretical Korringa-Kohn-Rostoker (KKR) calculations. The directional difference profiles, both experimental (of medium resolution) and theoretical ones, show very small anisotropy of the electron momentum density in magnesium, 2-3 times lower than in zinc and cadmium single crystals, significantly lower than observed in cubic metals. This small directional effect is in good agreement with Compton 60-keV energy experiments and positron annihilation data presented by other authors.
Modern Neutron Imaging: Radiography, Tomography, Dynamic and Phase Contrast Imaging with Neutrons
Authors: Schillinger Burkhard , Calzada Elbio , Lorenz Klaus
Published: March 2009

This paper gives a review about the current state of the art in neutron imaging like
neutron radiography, neutron tomography, stroboscopic imaging and phase contrast imaging. The
different techniques are described and compared to X-rays.
The Robust Control of Magnetic Bearings for Rotating Machinery
Authors: Gosiewski Zdzisław , Mystkowski Arkadiusz
Published: March 2009

The fast progress in the applications of active magnetic suspension systems needs to
apply the modern control theory. This paper deals with H∞ and H2 control of rigid rotor movement,
which is supported in magnetic bearings. The robust control of magnetic bearings is investigated
analytically. The nominal model of active magnetic suspension of rotor and the uncertainty model
were derived. The standard PID control and robust control are compared and performance of
nominal feedback configuration with weights is presented. We propose a robust control with a
multi-objective controller to achieve good robust stability when the model of a plant is uncertain.
The behavior of multiplicative uncertainty of magnetic suspension system is shown.
The aim of optimal robust control is to improve the magnetic suspension taking into account
the energy limitation (i.e., to avoid the saturation of actuators). The H2 performance and H∞
performance depend on a proper selection of weighting functions. So a very important step in the
controller design process is to choose the appropriate weight functions: We, Wu, Wd. The influence
of noise is limited by weight functions. We also put limits on input and output signals. The stability
of a system with disturbance interaction is discussed. The simulations of a well-posed and internally
stable magnetic system are presented. The success of the robust control is demonstrated through
results of numerical simulations.
A Computer Control System for the Hydraulic Stand MZPK 100 for Biaxial Fatigue Testing
Authors: Kasprzyczak L.M. , Słowik J.R. , Macha Ewald
Published: March 2009

This paper presents a two-channel digital control system for the hydraulic stand MZPK
100 designed for fatigue tests of cruciform specimens under biaxial tension-compression. In the
past, the fatigue test stand MZPK 100 was provided with unreliable analog control power cubicles.
Application of the computer with an analog and digital input-output signal path board,
Matlab/Simulink software and a new control box equipped with the necessary electronic subassemblies
(responsible for proper switching of the hydraulic supplier, command electrovalves,
conditioning of signals from sensors and so on) enables replacement of the old analog system by a
new two-channel digital control system. Nowadays, it is easy to modify the control system to
different requirements of material tests because the hardware (electronic) solutions have been
simplified, and the software has a friendly Simulink interface. Such an approach allows for the
implementation of different control algorithms, e.g. PID, adaptive, and fuzzy logic etc. Moreover,
this paper presents a description of how to keep the center of the specimen static under a controlled
force that is being applied by four independent actuators.
The Calculation of Dynamic Errors in Signal Transformation Circuits of Analog-to-Digital Converters for Mechatronic Systems
Authors: Marcinkevičius Albinas J. , Jasonis V.
Published: March 2009

Precision and wide-band analog-to-digital converters (ADC) are used for information
processing in mechatronic systems. The analog signal transformation circuits, such as sample, and
hold circuit (SHC) and an analog signal interpolation circuit (ASIC), are applied with the aim of
increasing the precision of converters. These circuits allow for reducing the quantity of comparators
in the converter and increase their dynamic stability. The models of SHC and ASIC as well as the
results of the calculation precision and dynamic parameters of such circuits are presented in this
paper. Equations for the calculation of the aperture error in the Gaussian and a sinusoidal input
signal were derived. The structural model, proposed for SHC, evaluates the nonlinearity of a
transfer characteristic, and the influence of noise in the signal and strobe channels. The results of
the theoretical research and analytical equations for the evaluation of the number of signal
interpolation block differential amplifiers, which depends on the analog signal’s maximal frequency
and the number of segments of the converter, are presented. The results of this work allow one to
estimate the main precision and dynamic parameters of ADC transformation circuits.
The Use of Mechatronics for the Improvement of Grinding Accuracy
Authors: Vekteris Vladas
Published: March 2009

Various aspects of the improvement of the functioning of grinding accuracy are
considered. Active methods of the control of grinding systems are proposed to ensure the quality
required for finishing. It is pointed out that the quality of finishing is closely connected with the
mutual position of the tool and the work piece in the grinding process. This position is appreciated
by permissible state areas of the axis of the tool and the work piece. Analytical expression of this
interaction is described by non-traditional mathematical model’s dependences. Mathematical
models presented evaluate eccentricity between the tool and the work piece or between other
elements of the system and enable one to better understand the appearance of the second and higher
harmonics on the work piece processed or on the tool. They allow one to simulate the finishing not
only of the cylindrical, but also of non-round profile work pieces, such as cams, eccentrics, etc. The
mathematical dependences worked out allow one to build various modifications of the grinding
systems and to evaluate the quality of their functioning. A circuit for the active control of the tool
position is proposed, with the goal of quality improvement of finishing. For this purpose the usage
of the adaptive spindle with tilting-pad journal bearings is suggested.
Self Configuration of a Novel Miniature Ultrasonic Linear Motor
Authors: Mracek Maik , Hemsel Tobias , Vasiljev Piotr , Wallaschek Jörg
Published: March 2009

Rotary ultrasonic motors have found broad industrial application in camera lens drives
and other systems. Linear ultrasonic motors in contrast have only found limited applications. The
main reason for the limited range of application of these very attractive devices seems to be their
small force and power range. Attempts to build linear ultrasonic motors for high forces and high
power applications have not been truly successful yet. To achieve drives, larger force and higher
power, and multiple miniaturized motors can be combined. This approach, however, is not as
simple as it appears at first glance. The electromechanical behavior of individual motors differs
slightly due to manufacturing and assembly tolerances. Individual motor characteristics are strongly
dependent on the driving parameters (frequency, voltage, temperature, pre-stress, etc.) and the
driven load and the collective behavior of the swarm of motors is not just the linear superposition of
the individual drive’s forces.
Vibroacoustic Properties of Materials Used in Constructions and Their Application in Lithuania
Authors: Gužas Danielius , Pelikša M.
Published: March 2009

At present, after the restoration of independence, intensive construction of modern
buildings for different purposes is being carried out within Lithuania. New effective materials and
forms are being applied to these constructions. Proper usage of these materials improves
vibroacoustic properties of buildings.
The article deals with the vibroacoustic properties of applied building constructions depending on
their forms and strengthening. Means to increase sound and vibration isolation without changing
vibroacoustic properties of used materials have been determined. Examples of practical application
of vibroacoustic properties of materials are given. The effectiveness of these materials has been
determined. Theoretical results of the effectiveness of vibroacoustic properties of building materials
coincide if the application of vibroacoustic properties in technologies of construction work is
proper.
Some Features of Rotor Dynamics inside Floating Sealing Ring
Authors: Banakh L.Y. , Nikiforov A.N. , Panovko G.Y.
Published: March 2009

Flow-coupled vibrations of system “rotor-ring” are researched. Absence effect of critical
rotor velocity and dynamic absorption of rotor vibration in the system “rotor-ring” is described.
These properties are caused by aero(hydro)dynamic forces in the clearance between rotor and ring.
Result of lowered vibration for high-speed rotor of turbo-pump containing floating sealing rings is
submitted.
The Sliding Pair's Reliability Calculation. General Approach
Authors: Zwierzycki Wiesław , Wojciechowicz Bolesław , Stachowiak Arkadiusz , Bieńczak Krzystof
Published: March 2009

This paper shows the possibilities of sliding pair’s calculation evaluation with the use of the generalized wear model where the wear rate v is a function of friction parameters p, v and complex constants K and x. It also estimates the inaccuracy (uncertainty) scale of methods making up the reliability prediction algorithm, especially in connection with the choice of: the method of transformation of random arguments distribution into the function distribution of the kinematic pairs stability, pseudorandom-number generators, contact stress characteristics.
Corrosive and Mechanical Wear in Sliding Pairs Calculation
Authors: Zwierzycki Wiesław , Stachowiak Arkadiusz
Published: March 2009

This paper analyses the state of knowledge on the range of analytic modeling of wear in
conditions of corrosive and mechanical interactions. So the achieved knowledge has allowed us to
formulate our own complex calculation algorithm. Based on that, the authors have elaborated a
computer program enabling a full simulation of corrosive and mechanical wear of rough surfaces in
pin – on – disc situation. The results of simulations and experimental tests are given in the paper.
Mechatronical System of Testing of Hydrodinamical Bearings
Authors: Jurevichius Mindaugas , Vekteris Vladas
Published: March 2009

This article presents a Mechatronic Hydrodynamic Bearings Testing System and
describes its main functions. The System’s structure, control and principles of data input/output
are given here. The System enables one to evaluate the quality of bearings by spectral analysis of
oscillations and orbits of the rotor pivot. Potentials of the System and realization of diagnostic
measurements by means of this System are described.
Investigation of Quality Change in Locomotive Lubricant
Authors: Bučinskas Vytautas , Subačius Rimantas , Mokšin V. , Vekteris Vladas
Published: March 2009

This paper describes experimental investigation of lubricant properties used in
locomotive engines. The workbench for experimental investigation is described, and experiment
technique is presented. Results and their interpretation show direction for further investigation.
Conclusions of results are made.
Optimization of Weighting and Labeling Process
Authors: Senkuvienė I. , Senkus V.
Published: March 2009

Target of the authors’ job was to optimize weighting and labeling process in mechanical
machining companies. Main direction was to increase efficiency and decrease the amount of
failures in the process. Efficiency in such field of industry is about 10 times lower than the
statistical EU number so it is vital to increase it.
Initial situation analysis indicated a low level of automation, computer systems are not connected to
a global system, and the process is not fully defined. This was found to be the main reasons for low
efficiency. High levels of failures are mainly caused by human mistakes.
To optimize the process it was decided to design an integrated computer system. In the frame of the
project an IT system called Kilo was designed, which communicates via ODCB with SQL server.
The duration of the project was 6 months. Weighting, counting and labeling processes were
automated by using a global PPS system data and a specially designed integrated electronic
weighting system.
During final steps of the project the performance of a new designed system was analyzed. The
results showed the following data: parts weighting and counting process time was decreased 50
percent, and labeling process time was decreased by 78 percent. Separate monitoring of failures
performed all 6 months showed impressive decrease of failures 90 percent and in the last month it
was not registered at all.
Device for an Active Dimension and Deflection Control of Shafts at Machining
Authors: Marcinkevičius Andrejus Henrikas
Published: March 2009

When using programmed machine tools many steps of a shaft are machined in one
operation. Many shafts are not rigid enough and for the purpose of achieving high accuracy and
productivity it is necessary to use an automatic follow rest and dimension control. The problem is
complicated by necessity of an automatic reset in an operation from one step of a shaft to the other.
The new scheme of a device is proposed in the paper that enables simultaneously to support the
shaft being machined and control its dimensions. The work principle of a device is that the shaft is
supported in a radial direction by a movable slider. Diameter of the shaft neck is measured by two
levers turning round their axes driven by the movable slider with patterns. The main idea is that at
motion of the slider equal to change of the shaft neck diameter measuring surfaces of levers are
constantly tangent to diametrical surface of the workpiece while the slider is supporting the
workpiece in radial direction, opposite to the cutting force. Dimension of a shaft neck is evaluated
as a sum of motion value of a slider and deviation from tangent of lever measuring surfaces.
Theoretical background of principle schemes and the work scheme of a device are presented in the
paper.
Research of the Durability of a Covering from Oxide Ceramics
Authors: Kuliavas Liudas Albinas , Mockaitis Jonas
Published: March 2009

A lifetime of details directly influences the lifetime of machines and equipment. Details
in most cases wear out, instead of collapsing. Raising their wear of resistance is a perspective
problem. The most economic way is drawing hardwearing coverings on a surface of details made of
carbon steel.
In our work coverings from oxide ceramics (Al2O3 and Al2O3+TiO2), put by the way of a gas-flame
spraying onto a surface of specimens made from carbon steels C20 and C45 were investigated.
Before a conversion coating specimens became hardened, a temper was made, the surface was
exposed to sandblasting, and the special sub layer for raising an adhesion of a covering with a basis
was put on. After drawing a ceramic covering, the micro hardness of a covering and a basis was
measured. Then the contact and abrasive wear resistance of surfaces on original installations was
tested. The agency on wear- resistance of an aspect oxide ceramic type of wear – contact and
abrasive, heating of the superficial layer arising because of a friction of two surfaces was
investigated.
At the end of the work, leading-outs are presented as a recommendation on the application of oxide
ceramics for raising of wear resistance of steel details.
Teaching of Materials and Welding Engineering to Today's Postgraduate Mechanical Engineers
Authors: Valiulis Algirdas Vaclovas
Published: March 2009

Rapid advances in technology have blurred traditional boundaries between engineering
disciplines and forced mechanical engineering graduate courses to embrace new subject areas.
These are not negative influences, but are simply a healthy response to rapidly advancing
technologies. A particular example is the combining in one study program, studies of different
engineering and structural materials (including composite materials, ceramics, polymers, etc.) and
methods and technologies of brazing, joining by welding, bonding by glue, etc of these materials.
Among all engineering programs, materials and mechanical engineering requires huge
laboratories and expensive facilities, as students need to develop practical experience. In order to
maintain an educational standard and quality, a university is forced to look for alternatives to handson
practical laboratories. One of the alternatives is to utilize a wide variety of computer-aided
learning packages and the simulation of physical-chemical processes in a welding pool and near to
its border. This paper sets forth a case for integrating aspects of materials and joining technologies
throughout a graduate curriculum.
A Pilot Program for Engineers: Sharpening English and Thinking Skills and the Application of Integrated Technical Information
Authors: Valentukeviciene M. , Baltrenaitė E. , Bizys Nin
Published: March 2009

The paper presents a pilot program that ran from February-April 2005 at Vilnius Gediminas
Technical University (VGTU) and was organized by The Environmental Engineering Faculty with the
British Embassy. The course could suit technical/mechanical specialists and be adapted to different
study areas. Seminars and workshops for 70 participants aimed at improving English, thinking skills
and the application and integration of knowledge. Technologists, engineers, project-designers,
lecturers and business people working in the environmental sector completed 20 tools for thinking,
based on Edward de Bono’s Cort Thinking Program. The concept was based on 12 year’s experience
with lecturers and post-graduate students at V.G.T.U. and evidence of the need for extended studies
and specific English, thinking skills and competencies as required by today’s employees in Lithuania
as an E.U. member.
Mechatronic Systems with Linear Induction Motors of Dampers
Authors: Poska A.J. , Smilgevičius A. , Rinkevičienė R.
Published: March 2009

The purpose of the paper is, from the view of system engineering, to investigate
mechatronic systems with uncontrolled or pulse controlled dampers that are equipped with a linear
induction motor (LIM), the secondary element of which appears as a moving element of a damper.
The main technological parameters determining the requirements for linear induction drives applied
in the automatic protection and technological process control systems were investigated. Methods to
investigate electromagnetic, electromechanical and thermal dynamic processes at pulse control of
large cross-area dampers were proposed, and application of results of the investigation was
considered.
Technological Trends of Nanoelectromechanical Systems
Authors: Navickas R.
Published: March 2009

The analysis of technological trends nanoelectromechanical systems and processes of self-formation micro- and nanostructures in manufacturing MEMS/NEMS have been made and the requirements have been formulated. The results of modeling geometry nanostructures and the implementation of self-formation processes for creating new technologies of manufacturing MEMS/NEMS have also been presented.
Mechanism of Grain Refinement in Aluminium in the Process of Hydrostatic Extrusion
Authors: Lewandowska Małgorzata
Published: March 2009

Technically pure aluminium was subjected to three passes by the process of hydrostatic extrusion (HE) to a true strain of 3.8. TEM observations of the microstructure revealed that the first pass of the process refined the grains to 0.6 μm, but the mean grain size remains unaffected by further strain. The microstructural evolution over the strain range from 1 to 4 proceeds through the recovery of grain interiors. Significant changes have been found in grain boundary characteristics. The fraction of high angle grain boundaries profoundly increases as the true strain increases. Various mechanisms for their formation and their relevance to HE are discussed
The Influence of Hydrostatic Extrusion on the Microstructure of 6082 Aluminium Alloy
Authors: Widlicki Pawel , Garbacz Halina , Lewandowska Małgorzata , Pachla Wacław , Kulczyk Mariusz , Kurzydlowski Krzysztof Jan
Published: March 2009

Hydrostatic extrusion can be viewed as one of the methods of Severe Plastic
Deformation, SPD, for the fabrication of ultra-fine grained alloys which causes a significant
increase in the mechanical properties such as tensile strength and hardness. In the present study the
microstructure of 6082 aluminium alloy after hydrostatic extrusion was investigated.
Hydroextrusion was performed in three steps with accumulated true strains of 1.34, 2.73 and 3.74
respectively. Microstructural observations were carried out using SEM, TEM and light microscopy.
Grain and inclusion sizes, shapes and distribution were investigated in the HE processed samples.
The study has shown that the hydrostatic extrusion process results in a profound refinement of both
the grain size and the inclusions in 6082 aluminium alloy.
Processing and Characterization of AlCu Aluminium Alloys by the ECAE Method
Authors: Lech-Grega Marzenia , Boczkal S. , Senderski J. , Płonka B.
Published: March 2009

Equal channel angular extrusion method (ECAE) was used to deform AlCu alloys in the
range of true strains ε = 1.15 – 2.3. Samples for investigation were produced from extruded bars,
conventionally manufactured and from a consolidated powder ingot. The influence of the strain on
the structure was studied by using light microscopy and TEM and on properties by hardness
measurement. Increased strain caused structural refinement of structure and increased hardness.
The structure revealed the presence of the mutually crossing microbands, visible against the
background of a high density of dislocations. After annealing, nearly equiaxed grains were formed.
The material prepared by powder consolidation possessed greater hardness. The results revealed
differences in structure and properties of nominally the same alloy, but processed differently, when
subjected to deformation by ECAE
Influence of Severe Plastic Deformation on the PLC Effect and Mechanical Properties in Al 5XXX Alloy
Authors: Zdunek Joanna , Widlicki Pawel , Garbacz Halina , Mizera Jaroslaw , Kurzydlowski Krzysztof Jan
Published: March 2009

In this work, Al-Mg-Mn-Si alloy (5483) in the as-received and severe plastically deformed states was used. Plastic deformation was carried out by hydrostatic extrusion, and three different true strain values were applied 1.4, 2.8 and 3.8. All specimens were subjected to tensile tests and microhardness measurements. The investigated material revealed an instability during plastic deformation in the form of serration on the stress-strain curves, the so called Portevin-Le Chatelier effect It was shown that grain size reduction effected the character of the instability.
Influence of High Pressure Hot Compaction on Microstructure of Al-Si-Ni-Mm Alloys
Authors: Cieślak Grzegorz , Latuch Jerzy , Kulik Tadeusz
Published: March 2009

Nanocrystalline Al-Si-Ni-Mm alloys have been intensively investigated in recent years.
Nanocrystalline Al - based alloys containing silicon (Si), rare earth metal (RE) and late transition
metal (Ni), have high tensile strength and good wear resistance. The aim of the work was to
manufacture bulk nanocrystalline Al-Si-Ni-Mm system alloys and determine the influence of hot
compaction at high pressure on the microstructure. The bulk nanostructured Al73Si19Ni7Mm1 and
Al72Si19Ni7Mm2 alloys were produced by high pressure hot compaction of ball milled
nanocrystalline ribbons.
Downscaling Equal Channel Angular Pressing
Authors: Zi Aikaterini , Estrin Yuri , Hellmig Ralph Jörg , Kazakevich M. , Rabkin Eugen
Published: March 2009

ECAP (equal channel angular pressing) is a well-known severe plastic deformation method used to produce ultra-fine grained materials. The dimensions of ECAP specimens are usually in the centimeter range. For producing high strength wires or fibres with diameter in the micrometer/millimeter range, downscaling of the ECAP process may be a viable option. To achieve this, several experiments were carried out. For downscaling to the micrometer range, porous steel discs can be used as processing tools. In this case, a solid state infiltration method as a variant of the forcefill process can be used. Extremely large strain is introduced due to the material flow through the tortuous channels inside a porous pre-form leading to grain refinement depending on processing conditions. To obtain specimens with a typical dimension in the millimeter range, the forcefill approach was altered by using die channels produced by conventional drilling. The tool geometry used is equivalent to conventional ECAP, but with a multi-channel die. Microstructure investigations demonstrating significant grain refinement confirm the viability of this approach.
Synthesis of Diamond Particles under Alkaline Hydrothermal Conditions
Authors: Yamasaki Nakamichi , Yokosawa Kazunori , Korablov Sergiy , Tohjt Kazuyuki
Published: March 2009

Very fine diamond powder (1-3 ~m) was readily sintered under hydrothermal conditions, with new bond formation occurring between the diamond particles in a l0M-NaOH solution at 573 K maintained at 1 GPa pressure, for 24 hours. This new bonding material can be formed by carbonization, from a chlorinated hydrocarbon such as dichloromethane and 1, 1,1–trichloroethane. The carbonized material forms a new bond between the hydrogenated diamond particles by the release of hydrogen chloride. Using Raman spectroscopy and hydrogenated cubic boron nitride substrates it was indisputably demonstrated that diamond was synthesized under these alkaline hydrothermal conditions. The surface morphology of the hydrothermal product on the cubic boron was similar to the new growth on the diamond substrates.
Nanotube and Nanorod Synthesis under High Frequency Electric Discharge Assisted Mechanical Milling
Authors: Calka Andrzej , Wexler David , Mosbah Ahmed Y.
Published: March 2009

Electric discharge assisted mechanical milling using a 50 Hz power supply has been used to produce a range of fine and nanostructural products, including nanocrystalline aglomerates and individual nano-particles and nano-fragments. Processing variables include; starting powder sample size; electric arc parameters such as arc length and arc voltage/current; mechanical milling parameters; gas atmosphere and ionized gas species present. We describe results of an experimental program underway to investigate phase transformations and/or particle fragmentation during discharge milling using a new pulsed power supply working at frequencies in the kHz range. The aims of this preliminary investigation were to determine processing parameters required for the synthesis of potentially useful high surface area particles, nanostructural powders and nanoparticles, and to compare products with those synthesised by Hz frequency discharge milling. Microstructural, morphological, and phase changes induced by kHz discharge milling were characterised by x-ray diffractommetry and transmission electron microscopy. Results were found to depend on the often competing processes of fragmentation into nano-particles, agglomeration of powder particles, particle melting and/or sintering, and chemical reaction induced by mechanoprocessing in the presence of a particular type of plasma. Discharge milling of graphite under Ar/4%H2 resulted in a range of products including; graphite nanostructures, carbon nanotubes and other exotic nanofragments. It was found that, compared with processing at 50 Hz, high frequency (kHz) electric discharge assisted mechanical milling of graphite resulted in higher yields of carbon nanotubes. hematite resulted in partial reduction to magnetite and FeO,and the formation of nanostructural oxide nanorods and nanorod clusters. Discharge milling of Co-WC resulted in products including; micron and submicron fracture products, nanostructural regions of Co and WC, and carbon rich nanorods and nanotubes.
Fabrication and Physical Properties of SiC-GaAs Nano-Composites
Authors: Kalisz Grzegorz , Grzanka Ewa , Wasik Dariusz , Swiderska-Sroda Anna , Gierlotka Stanislaw , Borysiuk Jolanta , Kaminska Maria , Twardowski Andrzej , Palosz Bogdan F.
Published: March 2009

Nano-composites consisting of a primary matrix phase of hard nanocrystalline SiC and a
secondary nanocrystalline GaAs semiconductor phase were obtained by high-pressure zone
infiltration. The synthesis occurs in three stages: (i) at room- temperature the SiC nanopowder is
compacted under high pressure to 8 GPa, (ii) the temperature is increased to 1240°C, above the
melting point of GaAs, and the pores were filled with liquid, (iii) on cooling GaAs nanocrystallites
grow in the pores. The synthesis was performed using a toroid-type high-pressure apparatus (IHPP
PAS, Warsaw) and a six anvil cubic press (MAX80 at HASYLAB, Hamburg). X-ray diffraction
studies were performed with a laboratory D5000 Siemens diffractometer. The phase compositionn,
grain size and macrostrains in the synthesized materials were examined. The microstructure of the
composites was characterized using a Scanning Electron Microscopy (SEM), and High Resolution
Transmission Electron Microscopy (TEM). Far-infrared reflectivity and Raman spectroscopy
measurements were used to trace built-in strains.
Nonlinear Elastic Properties of Bulk Metallic Glasses Zr52.5Ti5Cu17.9Ni14.6Al10 and Pd40Cu30Ni10P20
Authors: Kobelev N.P. , Kolyvanov E.L. , Khonik V.A.
Published: March 2009

The effect of uniaxial compression on the ultrasound velocities in bulk glassy
Zr52.5Ti5Cu17.9Ni14.6Al10 and Pd40Cu30Ni10P20 has been studied and the third-order elastic moduli of
these glasses have been determined.
Mechanical Spectroscopy, Internal Friction and Relaxation Phenomena in Solids – Suggested Reading
Authors: Magalas Leszek B. , Golovin S.A. , Darinskii B.M.
Published: March 2009

A list of monographs on internal friction, anelasticity, ultrasonic attenuation,
relaxation phenomena in solids, and mechanical spectroscopy published in Soviet Union,
Russia, and Ukraine is provided. A complete list of proceedings from international and
Russian conferences is also given. This work is a valuable supplement to the Mechanical
Spectroscopy - Suggested Reading Series.
Mechanical Relaxations and Transitions in Poly(Vinylidene Fluoride) PVDF
Authors: Gasmi A. , Gouasmia M. , Etienne S.
Published: March 2009

Dynamic mechanical spectroscopy and differential scanning calorimetry measurements carried out on PVDF films are reported. Several mechanical relaxations are observed around - 100° C, -40° C, and 17° C at 1 Hz, respectively. It is shown that thermomechanical treatments induce variation of material morphology as revealed by calorimetry and low-frequency mechanical spectroscopy. The effect of long-term ageing at room temperature is attributed to reversible melting and formation of small crystallites. The molecular rearrangements involved in ageing at room temperature are characterized by a slow dynamics.
Mechanical Spectroscopy of Oil Films Deposited on Metallic Substrate
Authors: Magalas Leszek B. , Etienne S.
Published: March 2009

The mechanical loss spectra obtained in metallic samples covered with various thin films of
arachis oils containing different sulphur concentrations, different consistency, and different oil
fractions are observed in the low-temperature range from 180 K to 300 K. The observed mechanical
loss spectra are identified as the surface induced mechanical loss phenomena. It is demonstrated that
mechanical loss spectra are induced by the presence of oil films on metallic substrates. It is shown that
the shape, the peak location, and the generation of the constituent low-temperature peaks can be
controlled by the state of the arachis oil films.
Structure and Conductivity of Nanostructured Sodium Nitrite
Authors: Golosovsky I. , Dvornikov V. , Hansen T. , Fokin A. , Koroleva E. , Korotkov L. , Naberezhnov A. , Tovar M.
Published: March 2009

Combined neutron diffraction, dielectric and conductivity measurements of NaNO2 embedded into porous glasses with average pore diameter 7 nm are performed in the ferroelectric and paraelectric phases. The temperature interval of existence of a volume premelted state in this confined material is determined. It is shown that the observed earlier giant growth of dielectric constant above TC can be attributed with an appearance of ionic conductivity due to jumping diffusion (or hopping) of constituent ions. These data are in a good agreement with experimental results of our earlier measurements of temperature evolution of structure of this nanocomposite material.
The Influence of Mechanical Deformation on the Optical Properties of Laminated As2S3, GeSe2 and As2Se3 Crystals
Authors: Babaev A.B. , Kamilov I.K. , Sultanov S.B. , Gabibov F.S. , Askhabov A.M.
Published: March 2009

Reversible photostructural conversions (darkening and bleaching) attended by a shift of transmittance edge and by the photoluminescence fatigue effect are revealed. Upon mechanical treatment of crystals the maximum of the luminescence excitation spectrum shifts toward higher energies. The low-energy edge of the luminescence spectrum flattens, and emission intensity increases. The experimental results are interpreted within a configuration model of two stable structural states of molecular groups.
Ultrasonic Investigation of the Ni40Ti50Cu10 Alloy
Authors: Straube U. , Mazzolai Giovanni , Biscarini A. , Coluzzi B. , Mazzolai Fabio M. , Beige Horst
Published: March 2009

The ultrasound pulse echo overlap method has been used to determine the elastic
stiffness coefficients and the corresponding ultrasonic attenuation for a single crystal of the
Ni40Ti50Cu10 alloy as a function of temperature. The elastic stiffness coefficients exhibit anomalies
near the martensitic phase transition. In the shear stiffness coefficient, corresponding to C44
propagation mode in austenite, a large jump occurs from 36 GPa, above the transition, down to
15 GPa, below the transition. This jump is accompanied by a strong increase in the ultrasonic
attenuation. The stiffness coefficients corresponding to C11 and C' = (C11 – C12)/2 modes in
austenite show an anomaly at the phase transition, however, these are small effects compared to the
one associated with C44 mode. The elastic behavior of this crystal has been characterised down to a
temperature of 100 K.
High-Temperature Mechanical Relaxations in Metals and Metallic Alloys
Authors: Rivière Andre
Published: March 2009

In spite of numerous works, the relaxation phenomena observed at high temperature (between room temperature and the melting temperature TM) are still under discussion. Because relaxation peaks were observed in single crystals, it is generally considered that the basis of the relaxation mechanism is linked to the dislocation network. The main difficulty for high temperature damping measurements is the great sensitivity of internal friction with several experimental parameters: the heating/cooling rate, maximal applied strain amplitude, sample purity, thermomechanical history of the sample, microstructure, etc. This sensitivity can explain the large scatter in experimental results published by various authors. Moreover, internal friction (IF) measurements performed during continuous heating or cooling and using an apparatus working at a quasi-static frequency, do not allow to completely describe the relaxation phenomena. On the contrary, isothermal mechanical spectroscopy (measurements of internal friction in a large frequency, temperature and maximal strain amplitude ranges) improves the experiments or evidences new relaxation effects. This is illustrated in this paper for various examples: slightly cold worked single crystals, polycrystals after a large cold work and recrystallization, non thermally activated peaks observed in metallic alloys, and relaxation peaks at very high temperature (above 0.9 TM).
Effects of Casting Variables on Soundness of A356 Alloy Products in Rheo-Diecasting
Authors: Kim J.M. , Sim J.G. , Moon J.Y. , Kim M.S. , Yoon K.M. , Ko Young Jin , Lim Jong Dae , Hong Chun Pyo
Published: March 2009

The effects of die temperature and plunger velocity on the soundness of semisolid cast products were
investigated in regards to the flow behavior of the slurry of A356 alloy in the H-NCM rheo-diecasting
process. The sound cast was obtained with the die-temperatures of above 220 . The sudden changes
of casting velocity resulted in irregular microstructures with micro-porosity and shrinkage defects due
to turbulent filling pattern. The high casting velocity at the end of filling has no effect on the
castability and the formation of casting defects in H-NCM(Hong-NanoCasting method). The Sr
modification provides much finer and spheriodized eutectic silicon particles.
Influence of Rapid Shear-Rate Changes on Microstructure Formation during Semi-Solid Processing
Authors: Lin Xin , Li Tao , Huang Wei Dong
Published: March 2009

The solidification behavior of the semi-solid slurry with rapid shear-rate changes was
investigated by using succinonitrile-5at.%water transparent alloy and Sn-15wt.%Pb alloy on a
self-made apparatus. The results showed that the rapid changes of shear-rate improved the nucleation
and promoted the globular growth of solidification microstructure in the stirred melt. The increase of
shear-rate was in favor of promoting the grain growth with globular shape to a certain extent,
however, when the shear-rate was beyond a critical value, the further increase of the shear-rate will
lead the disappearance of the globular crystals. Thus, the microstructure of semi-solid processing
could be refined by a controlled stirring process.
Heat Treatments Effect on A357 Components Produced by SSM
Authors: Forn Antonio , Baile Maite T. , Martín Enric , Goñi Javier , Sarriés I.
Published: March 2009

The present work studies the effect the solution heat treatment, during artificial ageing and
re-aging, has on the mechanical properties of an A357 aluminium alloy component formed by New
Rheocasting. The effect that the evolution of silicon, during the solution treatment at various times,
has on the mechanical properties was also examined. The mechanical properties were evaluated
performing tensile tests, fractographical analysis and hardness tests. The microstructural
characterization was made using optical and electronic microscopy.
Coarsening Kinetics and Coarsened Si Size Distribution of Spray-Formed High Loading Hypereutectic Al-Si Alloys in the Semisolid State
Authors: Chiang C.H. , Tsao Chi
Published: March 2009

The coarsening behavior of spray-formed A-35wt%Si and A-45wt%Si alloys in the
semisolid state were studied. The coarsening kinetic and Si size distributions after coarsening at
various temperatures and times in the semi-solid state were investigated. The coarsening exponents,
n, the rate constants, K, in the LSW theory, and the modified rate constants were determined from
previous works. The coarsening activation energies of the two spray-formed alloys were calculated
from the slopes of ln(KT) vs. 1/T plots. The Si size distribution functions after holding at various
temperatures and times in the semisolid state were determined for the two spray-formed alloys. The
effects of the stokes-motion in addition to pure diffusion mechanism on the variations of coarsened Si
size distribution were also investigated.
Interaction of Key Variables During Rheocasting: Importance of Microstructure, Fraction Solid and Flow Velocity
Authors: Jorstad John L.
Published: March 2009

The globular microstructure required for semi solid metal (SSM) processing was initially
developed by agitating melt to fragment dendrites during alpha-phase solidification. More recently, it
was learned that a suitable structure was also achievable through copious nucleation of fine grains at a
temperature close to the liquidus coupled with controlled cooling to prevent dendrite growth; a
technique that can be applied to liquid casting processes but that is especially useful for semi solid
Rheocasting (the slurry version of SSM). Rheocasting experiments were conducted to test the
interactions of microstructure developed by the copious nucleation route, fractions of solid up to 0.5
during casting and slurry flow velocities up to 5 meters per second. Their combined effects on casting
defects and tensile properties will be presented and discussed.
Microstructural Evolution of Semi-Solid AZ61 Magnesium Alloy during Reheating Process
Authors: Yan Hong , Zhang Fa Yun
Published: March 2009

The microstructural evolution of AZ61 semi-solid magnesium alloy during semi-solid
remelting process was studied in this paper. The semi-solid billet was fabricated by strain-induced
melt activation (SIMA) method. The results showed that the initial semi-solid grains melt mainly
through coalescence. With the prolongation of isothermal holding time, the grains grew up and
spheroidized, in which the mean diameter of grain and liquid volume fraction increased. In the
meantime, the higher the holding temperature, the faster the grain grew and spheroidized. The
suitable reheating temperature of AZ61 semi-solid magnesium alloy was 592. The samples were
susceptible to serious deformation beyond 597.
Microstructure and Damping Capacity of Semi-Solid AM50 Alloy
Authors: Jun Joong Hwan , Park Bong Koo , Kim Jeong Min , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Microstructures and damping properties of semi-solid AM50 (Mg-5%Al-0.3%Mn) alloy were
investigated and compared with those of die-cast AM50 alloy, based on experimental results of X-ray
diffractometry (XRD), optical microscopy (OM), hardness tests and damping tests in a flexural mode.
The semi-solid AM50 specimens show higher damping capacity than die-cast one in as-fabricated state,
and the higher the fraction of solid α-(Mg), the greater the damping capacity. The annealing at 200oC
deteriorates the damping properties of the semi-solid and die-cast specimens. This would be due to the
segregation of solute atoms on dislocation lines, which eventually leads to lower internal friction by the
restriction of dislocation movement. The peak damping values of the AM50 specimens are obtained after
annealing at 400oC. The disappearance of segregates acting as pinning points of dislocations is thought
to be responsible for the improvement in damping capacity. This result implies that the presence of solid
α-(Mg) phase and annealing treatment at high temperature are beneficial to damping property of AM50
alloy.