bluuebunny/crossref_metadata_2025 huggingface dataset:
Wear Behavior of WC-Co Carbides with Addition of Cr3C2 and Ni
Authors: Carrino Luigi , Durante Massimo , Formisano Antonio , Langella Antonio , Minutolo Fabrizio Memola Capece , Caraviello Antonio
Published: May 2014

Cemented carbides present some characteristics that ensure high performances for cutting and wear-resistant tools. The aim of the work is to evaluate the influence of Chromium Carbide and Nickel on the properties (wear and friction) of a cemented carbide constituted by a hard phase of tungsten carbide and a binder phase of cobalt. Different tests were carried out by varying the percentage of Cr3C2 and, for one only case, also Nickel was added. The tests were carried out by a pin-on-disk apparatus and diamond abrasive sheet. The experimental campaign provided tests for different values of load and relative velocity. Friction coefficient was directly evaluated by the apparatus and data on the wear were obtained by measuring the loss of weight of the samples (parallelepipeds with hemispherical head). The tests allowed to determine the percentage of Cr3C2 that ensure an improvement of the aforementioned properties and to highlight the irrelevance of Nickel.
Re-Meshing in Finite Element Simulations of Hot Working Including a Microstructural Evolution Model
Authors: Bambach Markus
Published: May 2014

Material models that couple the evolution of flow stress to the evolution of the microstructure are important for the simulation of hot working processes in which the microstructure undergoes large changes. Among the microstructural evolution mechanisms in hot working, dynamic recrystallization (DRX) plays a central role as it occurs during deformation. When the workpiece deforms, the element shape may deteriorate, which makes re-meshing necessary. At the same time, certain regions of the finite element mesh undergo DRX and a sharp interface between recrystallized and non-recrystallized portions of the workpiece develops. Elements of the old mesh that are cut by the interface contain nodes with a non-zero recrystallized volume fraction and nodes where the recrystallized volume fraction is zero. During re-meshing, when the microstructural data is transferred to the new mesh, nodes or integration points that are actually in region of the workpiece that is not yet recrystallized may be assigned a non-zero recrystallized volume fraction. As a consequence, the interface moves, which is unwanted and may produce large errors when re-meshing is frequently done. In this paper, the problem of the propagation of the DRX interface during re-meshing is treated. It is shown that the propagation occurs with standard data mapping algorithms and produces a large error at the interface. A re-meshing scheme is proposed that uses a smooth mesh-free interpolating function based on radial basis functions to interpolate the recrystallized volume fraction. The interface is the zero level set of this interpolant. Performing the mapping as a least squares fit of the interpolant allows for a substantial reduction of the mapping error and suppresses the propagation of the DRX front.
Evaluation of Tribological Properties of AlMg4.5Mn0.7 in Massive Microforming Using the Barrel Compression Test
Authors: Schubert Andreas , Jahn Stephan F. , Müller Benedikt
Published: May 2014

Tribology is one of the major issues in forming processes. It is influenced by many factors such as workpiece and tool material, lubrication, process parameters, geometric scale etc. Especially in microforming processes, friction plays an important role due to an increased surface to volume ratio and the domination of open over closed lubricant pockets. A simple and sensitive method to quantify the friction factor under realistic conditions of massive forming is the barrel compression test. The friction factor is calculated out of the friction-dependent barreling of cylinder samples while being compressed between two parallel tool surfaces.In these investigations, the barrel compression test was applied to determine the friction factor between cylindrically shaped samples made of the aluminium alloy AlMg4.5Mn0.7 (EN AW 5083) and polished surfaces made of the tool steel 1.3343. The specimen diameter was varied between 0,5 mm and 10 mm. The focus of investigations was the size-dependence of the friction factor under the variation of the parameters such as forming degree, lubrication conditions, and die velocity. In addition to the calculation of the friction factor, surfaces were evaluated by microscopy and roughness measurements.
A Vertical Type Tandem Twin Roll Caster for Clad Strip Equipped with a Scraper
Authors: Haga Toshio , Tsuge Hiroshi , Ishihara Takuya , Kumai Shinji , Watari Hisaki
Published: May 2014

A vertical type tandem twin roll caster equipped with a scraper for the clad strip was invented. This roll caster could cast three layers clad strip which base strip had lower melting point than that of the overlay strips. The base strip was cast by an upper twin roll caster and the overlay strips were cast by a lower twin roll caster. The scrapers were attached to the lower twin roll caster, and were innovated to cast this type of three layers of clad strip. Solidification layers those became the overlay strips were pulled from between the scraper and the roll. The melt of the alloy which was as same as the base strip was poured between the scraper and the base strip. This melt connect the overlay strip and the base strip. The base strip was not re-melted. The scraper enabled that the solidification layer of the overlay strip contact to the melt of the base strip without mixing of the melt of the base and overlay strip. In this way, the sound three layers clad strip which base strip had lower melting point than that of the overlay strip could be cast by the vertical type tandem twin roll caster equipped with a scraper.
A Non-Conventional Technique for Evaluating Welded Joints Based on the Electrical Conductivity
Authors: Santos Telmo G. , Sorger Gonçalo , Vilaça Pedro , Miranda R.M.
Published: May 2014

Recent studies showed that electrical conductivity is a valuable technique to identify the different zones of solid-state welded joints with a good correlation with the microstructure and hardness. This is a relevant result since this technique is expedite and, in some cases, non destructive. The concept was applied to other welding processes as the ones involving fusion and to a wide range of materials. For this, a comprehensive study was performed using friction stir welding, tungsten inert gas (TIG) and gas metal arc (MAG) welding processes in either bead on plate or butt joints in: carbon steel, magnesium and titanium. Eddy current non-destructive testing (NDT) was used to measure the electrical conductivity at different depths in transverse sections of the processed materials. The obtained profiles were compared to the hardness profiles in the same sections. As a result, a good correlation was observed in most materials welded by solid state and by fusion processes. The variation of the electrical conductivity closely follows the one detected in the hardness. Another interesting conclusion is that, even for fusion welding of carbon steels, the technique has potential to complement the hardness measurements and microstructural observations, allowing to identify the distinct zones of welds in materials commonly used in industry.
Resource-Efficient Machining of Hard Metals
Authors: Kroening Oliver , Herzig Mathias , Schulze Hans Peter , Hackert-Oschätzchen Matthias , Kühn Ralf , Zeidler Henning , Schubert Andreas
Published: May 2014

The main requirements of carbide metal working are higher precision and high quality surface which can be fulfilled by electrical discharge machining. This procedure is accompanied with formation of heat affected zones (white layers) during the discharge process negatively. Therefore, the essential post-processing reduces the efficiency of this process and shows the importance of process energy sources (PES) with ultra short discharge in favor of a clearly differentiated cutting volume. By means of simulations of crater geometry and channel expansion the influence of discharge rise time is defined as determining factor for the cut volume and formation of white layers. The technological section presents two different approaches of realizing ultra-short pulses.
Investigation of the Hot Deformation Behavior of an Al-Mg-Sc-Zr Alloy under Plane Strain Condition
Authors: Taendl Johannes , Dikovits Martina , Poletti Cecilia
Published: May 2014

This study investigates the hot deformation behavior of a new Al-Mg-Sc-Zr alloy under plane strain conditions. Flow curves corrected for deformation heating were calculated for strain rates between 0.01 and 10s-1 in a temperature range of 200 to 400°C. To evaluate the deformation behavior, strain rate sensitivity as well as flow localization parameter maps were calculated for strains of 0.2, 0.4, and 0.6. In addition, microstructural investigations and hardness measurements were performed for selected samples. It was shown that the flow stress decreased with deacreasing strain rate and increasing temperature. The best formability was observed for high strain rates and low temperatures as well as for low strain rates and high temperatures. In these cases no flow instabilities were observed.
Structural Optimization and Additive Manufacturing
Authors: Ibabe Julen , Jokinen Antero , Larkiola Jari , Arruabarrena Gurutze
Published: May 2014

Additive Manufacturing technology offers almost unlimited capacity when manufacturing parts with complex geometries which could be impossible to get with conventional manufacturing processes. This paper is based on the study of a particular real part which has been redesigned and manufactured using an AM process. The challenge consists of redesigning the geometry of an originally aluminium made part, in order to get a new stainless steel made model with same mechanical properties but with less weight. The new design is the result of a structural optimization process based on Finite Element simulations which is carried out bearing in mind the facilities that an AM process offers.
Effect of the Interdiffusion at the Polymer/Polymer Interface on the Flexural Properties of Over-Moulded Short Glass Fibre/Glass Fabric Reinforced PA6 Composites
Authors: Lafranche Eric , Renault Thierry , Krawczak Patricia
Published: May 2014

The injection over-moulding of 30wt% short glass fibre reinforced PA6 (SGF from Solvay Engineering Plastics) onto consolidated unbalanced (87/13) 70wt% glass fabric reinforced PA6 (Continuous Fibre Reinforced Thermoplastic (CFRT) from Solvay Engineering Plastics) was investigated with the objective to optimise the flexural and interlaminar shearing of the complex. Among the processing parameters, the temperature of the fabric before injection and the over-moulded melt temperature associated to the mould temperature (cooling rate of the complex) were revealed as the main parameters directing the mechanical properties of the complex. Moreover, the flexural modulus and the apparent interlaminar shear strength fall down critically in the main direction (chain direction of the fabric) under a CFRT temperature of 150°C. The effect of the SGF/CFRT interface was quantified in term of quadratic distance of diffusion through the interface. First, the 1D cooling of the complex was simulated according to the heat transfer module of COMSOL Multiphysics® in order to determinate the variation of the temperature field during the cooling stage of process. The calculations were achieved with an initial CFRT temperature of 23, 100, 150 and 200°C, the mould and SGF melt temperatures were kept constant. The diffusion theory has then been applied to calculate the variation of the auto-diffusion coefficient through the thickness during the complex cooling, the diffusion is supposed occurring only at a temperature above the PA6 crystallisation temperature (185°C). The calculation of the quadratic distance of diffusion through the thickness confirmed the mechanical results. Under a CFRT temperature of 150°C, the ability to the molecular diffusion at the interface becomes non-existent. The melt temperature of the SGF PA6 has to be sufficient to melt the CFRT PA6 interface, the time of diffusion directed by both the CFRT and mould temperatures (cooling rate) has to be long enough to allow the molecular diffusion from the material to the other.
Study on Instability and Forming Limit of Sheet Metal under Stretch-Bending
Authors: Hou Bo , Perdahcioglu Emin Semih , van den Boogaard A.H. , Kitting Daniela
Published: May 2014

Under stretch-bending conditions, a significant tensile stress gradient through sheet thickness is induced, especially for a small punch radius. The traditional instability theories were developed assuming a uniform tensile stress / strain distribution through thickness; hence, may lead to unreliable prediction of stretch-bending formability. In this study, the instability behavior of sheet metal under stretch-bending is analyzed via FE-simulation of an Angular Stretch-Bend Test (ASBT). In order to reflect the influence of bending, contact normal stress etc., solid elements are used in the simulation. Three deformation stages are identified: (a). stable deformation; (b). strain localization through sheet thickness; (c). localized necking. Based on the instability characteristics, a localized necking criterion is proposed for predicting forming limits of sheet metal under stretch-bending. By combining the proposed criterion and solid element simulation, good agreement between numerical and experimental results is indicated. This work provides a new approach for predicting stretch-bend formability with sufficient accuracy and convenience.
Electromagnetic Sheet Metal Feeder
Authors: Teichrib Sergej , Krimm Richard , Behrens Bernd-Arno
Published: May 2014

For a continuous feeding of sheet metals in forming press lines mechanical roll and gripper feeders are used. Typical resulting problems are the damage of the sheet surface due to the mechanical contact. The present contribution deals with the investigations of an electromagnetic material feeder for electric conductive sheet metals. The concept is based on the principle of an asynchronous linear motor. Here the sheet metal acts directly as the secondary part. The new approach was first analysed and designed by means of finite element simulation. With experimental measurements the simulations could be validated using a demonstrator of the electromagnetic feeder. The results indicate that the feeding forces of partially 1000 N can be doubled in comparison to conventional mechanical roll feeders.
High Precision Algorithms for 3D Objects Shadow Inspection in Partially Coherent Light
Authors: Chuguy Yuri V. , Senchenko Elena S.
Published: May 2014

As applied to the dimensional inspection the peculiarities of 3D objects image formation with clear shadow projection under their illumination by quasi-monochromatic partially coherent light based on the constructive theory of 3D objects formation using a model of equivalent diaphragms are studied. Two threshold algorithms for determining the position of 3D objects geometric boundaries under their inspection by optical shadow method according to their thickness as well as the light source angular size and the projection system aperture diaphragm are developed. These algorithms are based on the application of true (calculated) threshold or standard one using the corrective component to threshold. It has been shown theoretically and experimentally that their use can significantly improve the measurement accuracy of extended objects. The obtained results under the development of measuring systems for industrial inspection of ceramic details allowed us to reduce the measurement error.
Evaluation of the Transient Temperature Distribution of End-Face Sliding Friction Pair Using Infrared Thermometry
Authors: Wei Wei , Yu Jian Wei , You Tao , Yu Xiao Fen , Wang Yong Hong
Published: May 2014

A real-time temperature measurement system was designed for end-face sliding friction pairs with an infrared (IR) probe and IR thermography installed on it. The approximate temperature of contact surface was measured by the probe while non-contact surface’s temperature distribution was determined with the IR thermography. Two experiments with constant load but varied rotational speeds were carried out, and a preliminary study was made to analyze the variation of temperature in the friction process. Furthermore, the probe data was used as thermal load to calculate the temperature field by the FEM model and the result was verified using IR images. The experimental results showed that the infrared measurement system can detect and record the interface-temperature variation accurately. The probe data showed a good dynamic performance with the variation of friction coefficient. In addition, the calculated temperature field showed good accordance with the IR thermography data.
Research and Development of a Yield Strength 400 MPa Class Structural Steel Plate with Enhanced Weldability
Authors: Zhang Yu , Li Xiao Bao , Pan Xin
Published: May 2014

A 400 MPa yield strength structural steel plate with enhanced weldability was produced by using advanced steel making technology and thermo-mechanical controlled processing technique. A microstructure consisting of acicular ferrite (3~8 μm) and polygonal ferrite was observed in the rolled plate, which exhibits a yield strength ≥ 420 MPa, tensile strength ≥ 560 MPa, elongation ≥ 26 % and charpy impact toughness ≥ 300 J at-40 °C. Three-wire flux copper backing submerged arc welding with heat input of 230 kJ/cm was applied to butt weld the 36 mm thick plate, and defect-free joint with satisfactory mechanical properties were produced. The coarse grain heat affected zone (CGHAZ) contains mostly intra-granular nucleated ferrite plus a few grain boundary ferrite and ferrite side plate, and shows charpy impact toughness ≥ 90 J at-40 °C. The enhancement impact toughness of CGHAZ resultant from high heat input welding is due to improvement of intra-granular ferrite formation induced by Ca and Ti containing oxides and sulphides.
Degradation of Spark Plasma Sintered (0, 5, 10 and 15 mol%) CeO2 + YSZ Composites in Supercritical Water
Authors: Siebert-Timmer Audrey , Bichler Lukas
Published: May 2014

Cubic Yttria-stabilized zirconia (c-YSZ) is a candidate material for high temperature applications due to its chemical inertness, high thermal stability and low thermal conductivity. In addition, due to c-YSZ’s high radiation stability, there is a new interest in this ceramic for thermal insulating cladding material in Supercrticial Water Nuclear Reactors (SCWR). However, due to the aggressive environment of supercritical water, the degradation behaviour of the ceramic must be well understood prior to its industrial application. In this research, moderately dense 8 mol% Yttria stabilized zirconia (YSZ) as well as YSZ composites containing 5, 10 and 15 mol% CeO2 were fabricated via Spark Plasma Sintering (SPS) and subjected to static corrosion testing in supercritical water (SCW) at 400°C and 31MPa. Weight loss and crystal lattice changes associated with SCW exposure were studied.
Nickel-Chromium Alloys: Engineered Microstructure via Spark Plasma Sintering
Authors: Pasebani Somayeh , Dutt Aniket K. , Charit Indrajit , Mishra Rajiv S.
Published: May 2014

There is a need to enhance or develop high temperature capabilities of structural materials for advanced coal‐fired power plants. These materials require a combination of high temperature strength, creep resistance and corrosion resistance in the oxygen‐rich and hydrogen‐rich high pressure environments. In this study, atomized Ni‐20Cr (wt.%) powder was mechanically milled with Y2O3 nanopowder (30‐40 nm powder size) to produce an alloy with a chemical composition of Ni‐20Cr‐1.2Y2O3 (wt.%) alloy using high energy ball milling. To minimize agglomeration during milling, 1 wt.% stearic acid was added to the powder mixture prior to milling. Microstructural characteristics of the powder were primarily characterized by the X‐ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystallite size and lattice strain were measured by XRD whereas powder morphology (powder size, shape) was studied by SEM. A milling time of 2 h was found to be optimal for the purpose that yttria particles are not dissolved yet uniformly distributed. Subsequently, the milled powder was consolidated into bulk specimens (12.5 mm in diameter) via spark plasma sintering (SPS) at 1100 °C for 30 minutes. Following SPS, the density and hardness of the specimens were measured. Microstructural characterization of the SPSed specimens was performed using SEM and TEM. The microstructural characteristics were correlated with the measured mechanical properties.
Metals for High Temperature Applications under Extreme Conditions – Development and Testing
Authors: Merker Jürgen , Koch M.
Published: May 2014

A lot of technical processes require metallic materials which are able to withstand very high temperatures under extreme conditions. Examples are applications in glass industry, space technology and crystal growing. Application temperatures are in the range from 1100°C to 2300°C. Besides the extremely high temperature the materials are often influenced simultaneously by high mechanical loading and chemical attack. Due to their outstanding chemical stability, corrosion resistance and high mechanical strength the platinum group metals, in particular platinum, rhodium and iridium, are therefore ideal materials for high temperature use under extreme conditions. These metals are widely used in spite of their high prices. High temperature applications require high melting point metals, commonly strengthened by solid solution or oxide dispersion hardening. This paper reports e. g. on the development of oxide dispersion hardened platinum and platinum alloys manufactured by fusion technique. Furthermore the paper presents a comprehensive review of studies on platinum materials which facilitate the design of equipment used for high temperature applications under extreme conditions. Stress-rupture strength and creep behavior have been investigated in a temperature range between 1200°C and 2300°C. The results of the investigations can supply a basis to optimize materials selection for high temperature applications under extreme conditions.
High Thermal Conductivity Aluminum Powder Metallurgy Materials
Authors: Donaldson I.W.
Published: May 2014

High thermal conductivity aluminum has special advantages for electronic packaging and thermal management applications because of the combination of excellent thermal conductivity and relatively low density. Recent development of new press-and-sinter aluminum materials with low levels of alloying that sinters to a high density yielding a high thermal conductivity approaching the theoretical value for pure aluminum. The sintered materials possess thermal conductivity (TC) exceeding 200 w/m-oK (typically 215 – 230 w/m-oK), which makes it unique, since cast and wrought aluminum materials typically fall below 175 w/m-oK. This allows the benefits of powdered metal for low cost manufacturing at high volumes of parts to be realized. This unique combination of low cost and high TC makes these materials an attractive alternative to higher TC materials such as copper. In addition, a metal matrix composites (MMCs) press and sinter approach to tailoring the coefficient of thermal expansion (CTE) can also be used.
Anti-Adhesive Finishing of Temporary Implant Surfaces by a Plasma-Fluorocarbon-Polymer
Authors: Finke Birgit , Testrich Holger , Rebl Henrike , Nebe Barbara , Bader Rainer , Walschus Uwe , Schlosser Michael , Weltmann Klaus Dieter , Meichsner Jürgen
Published: May 2014

Titanium implant surfaces should ideally be designed to support the subsequent clinical application. Therefore temporarily used implants have to fulfill both the mechanical stabilization of the bone stock and furthermore in trauma surgery the disintegration into the bone because the implant should be removed after fracture healing. The anti-adhesive plasma-fluorocarbon-polymer (PFP) films were synthesized using two different low-pressure plasma sources, the 2.45 GHz microwave (mw) and the 13.56 MHz capacitively coupled radio-frequency (rf) discharge in a mixture of the precursor octafluoropropane (C3F8) and hydrogen (H2). The film properties were characterized using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, water contact angle measurements, and abrasive strength tests. Cell adhesion and spreading of human osteoblasts were clearly reduced on these PFP surfaces. First in vivo data on the biocompatibility of the PFP films deposited in the rf-discharge demonstrate that the local inflammatory tissue response for PFP coating was comparable to controls, while a PFP coating deposited in mw plasma induced stronger tissue reactions.
Effect of Hydrolysis on Mechanical Behavior of Bioabsorbable Composites
Authors: Kobayashi Satoshi , Yamaji Shusaku
Published: May 2014

In this study, effect of hydrolysis in simulated body environment on mechanical behavior oftricalcium phosphate (TCP)/Poly(L-lactic acid) (PLLA) composites were analytically characterized.In order to predict stress-strain behavior after hydrolysis, damage micromechanical analysis proposedby the authors were utilized. In this model, nonlinear behavior in stress strain relationship weresimulated considering interfacial debonding between TCP particle and PLLA matrix. For the purposeof deciding the interfacial strength, such as critical energy release rate, curve fitting was conducted onthe result of the composites with 15wt% TCP content. Theoretical results on 5wt% and 10wt%composites using the interfacial strength obtained were in good agreement with experimental results.This result indicated that interfacial strength was independent from TCP fraction.
Osteoconductivity of Hydrothermal-Treated Valve Metals
Authors: Kuroda Kensuke , Zuldesmi Mansjur , Okido Masazumi
Published: May 2014

Anti-corroded valve metals, such as Ti, Nb, Ta, and Zr have been used as metallic biomaterials. However, as untreated surfaces, they do not have high osteoconductivity, and surface coatings with bioactive substances are needed for the implantation into the bone. Surface property, especially hydrophilicity, is considered to have a strong influence on the biological reactions. However, the influence of a hydrophilic surface on osteoconductivity is not completely clear. In this study, we produced super-hydrophilic surface on valve metals (Ti, Nb, Ta and Zr) using a hydrothermal treatment at 180 °C for 180 min. in the distilled water, and then the treated samples were stored in 5PBS(-). This maintained water contact angle less than 10 (deg.) in an apparent. The osteoconducivity of super-hydrophilic treated metals was evaluated with in vivo tests. The hard tissue formation on the samples increased with decreasing the water contact angle. That is to say that super-hydrophilic valve metals without coating of bioactive substances had high osteoconductivity, and the surface properties strongly affected on the osteoconductivity.
Relationship between Heterogeneous Microstructure and Fatigue Strength of Ti-Nb-Ta-Zr Alloy for Biomedical Materials Subjected to Aging Treatments
Authors: Narita Kengo , Niinomi Mitsuo , Nakai Masaaki
Published: May 2014

β-type titanium alloys such as a Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) are potential candidates for next-generation metallic biomaterials. However, the mechanical strength of β-type titanium alloys with a single β phase is not enough to be approved as materials for fabricating medical implant devices that are subjected to heavy loads, such as a spinal fixation device. Therefore, β-type titanium alloys are often subjected to aging treatments in order to improve their mechanical strength through precipitation hardening. However, β-type titanium alloys exhibit a heterogeneous microstructure because of microscale elemental segregation. In this study, the heterogeneous microstructure caused by the microsegregation of secondary phases was characterized by field emission scanning electron microscopy (FESEM) in TNTZ subjected to aging treatments. Furthermore, the influence of the heterogeneous distribution of secondary phases in TNTZ on mechanical properties was revealed by comparing its properties to the homogeneously structured TNTZ subjected to long-term homogenization.
Osteoconductivity of Superhydrophilic Anodized TiO2 Films Using Hydrothermal Treatment
Authors: Okido Masazumi , Kuroda Kensuke
Published: May 2014

In this study, we conferred superhydrophilic properties on anodized TiO2 coatings using a hydrothermal treatment, and developed a method to maintain this surface until implantation. The osteoconductivity of these coatings was evaluated with in vivo tests. A hydrothermal treatment made the surface of as-anodized samples more hydrophilic, up to a water contact angle of 13 deg. Storage in PBS(-) led to a reduction in the water contact angle, because of the adsorption of the inorganic ions in the solution, and the sample retained its high hydrophilicity for a long time. As the water contact angle decreased, the hard tissue formation ratio increased continuously up to 58 %, which was about four times higher than the hard tissue formation ratio on as-polished Ti.
Bioengineering Application in Kinesitherapy of Children with Lower Limbs Dysfunction
Authors: Chuchnowska Iwona , Sękala Agnieszka , Wolany Weronika
Published: May 2014

The work presents an innovative, interactive device used to support the rehabilitation process in small children with lower limbs dysfunction. The presented equipment combines movement therapy with simultaneous psychological stimulation of the child. EEG sensor measures the activity of the child’s brain waves and at the same time functions as the controller of the rehabilitation process. Application of the discussed equipment in the process of rehabilitation of children supports their optimal development within individual limits.
Carbides and their Role in Advanced Mechanical Properties of L605 Alloy: Implications for Medical Devices
Authors: Sun Fan , Mantovani Diego , Prima Frédéric
Published: May 2014

L605 (ASTM F90), a cobalt-chromium-tungsten alloy with excellent mechanical properties and high radiopacity, has been widely accepted as a suitable alloy for stent applications. The presence of carbides in this alloy, primary carbides and secondary carbides, leads to difficulties in controlling mechanical performances and therefore in optimizing stent size and performances. This work is thus to investigate the carbides and their role in advanced mechanical properties of L605 alloy for stent fabrication. Herein, the nature, nucleation, distribution and dissolution of the carbides were investigated in a series of recrystallized L605 tubes from hard-drawn (HD) state. The mechanical properties corresponding to each carbide state were examined by tensile tests and microhardness measurements. The results indicate important relationships among carbide precipitation, grain size and mechanical behaviors, as a function of annealing temperature and duration. The intergranular secondary carbides, induced at the onset of the recrystallization of L605 matrix, were preferentially precipitated at grain boundaries. The nucleation of such particulate phase leads to a pinning effect on grain coarsening, resulting in a strengthening effect of the material. However, the further growth of the secondary carbides brings about considerable reduction of ductility, which is inacceptable for stent application. Therefore, an optimization protocol on carbides controlling was developed to maintain the strengthening effect without losing ductility and small grain size.
Deformation Microstructure and Mechanisms in a Metastable β Titanium Alloy Exhibiting TWIP and TRIP Effects
Authors: Sun Fan , Zhang Jing Yong , Marteleur Matthieu , Gloriant T. , Vermaut Philippe , Castany Philippe , Curfs Caroline , Jacques Pascal J. , Prima Frédéric
Published: May 2014

Titanium alloys typically exhibit a limited ductility (typically 20%) and little strain-hardening. An alloy design with new concept was conducted aiming at improving both ductility and strain hardening while keeping the mechanical resistance at an excellent level. An experimental validation was illustrated with the Ti-12(wt.%)Mo alloy, exhibiting true stress - true strain values at necking, of about 1000MPa and 0.38, respectively, with a large strain hardening rate close to the theoretical limit. In order to clarify the origin of this outstanding combination of mechanical properties, detailed microstructural investigation and phase evolution analysis were conducted by means of in-situ synchrotron XRD, in-situ light microscopy, EBSD mapping and TEM microstructural analysis. In the deformed material, combined Twinning Induced Plasticity (TWIP) and Transformation Induced Plasticity (TRIP) effects are observed. Primary strain/stress induced phase transformations (β->ω and β->α’’) and primary mechanical twinning ({332}<113> and {112}<111>) are simultaneously activated in the β matrix. Secondary martensitic phase transformation and secondary mechanical twinning are then triggered in the twinned β zones. The {332}<113> twinning and the subsequent secondary mechanisms are shown to be dominant at the early stage deformation process. The evolution of the deformation microstructure results in a high strain hardening rate (~2GPa) bringing both a high tensile strength and a large uniform elongation.
Electronic Properties of Cubic Boron Nitride with Impurity Atoms and Vacancy
Authors: Li Yu Bo , Cheng Tian Yuan , Yang Hang Sheng
Published: May 2014

Cubic boron nitride (cBN) has significant technological potential for use in high-temperature high-power electronic applications. And S and Zn were reported to be potential n-and p-type dopants. In this study, influences of vacancies, S and Zn impurity atoms on the electronic properties of cBN were investigated by first-principle approaches. The computation results are in good agreement with our experimental approach.
Friction and Wear Properties of the Siliconized, Chromized and Borochromized Steel Substrates
Authors: Murakami Takashi , Hibi Yuko , Mano Hiroki , Matsuzaki Kunio , Inui Haruyuki
Published: May 2014

In this study, the friction and wear properties of the siliconized, chromized and borochromized SS 400 steel/Si3N4 tribopairs were investigated in ethyl alcohol at 298 K. The surface of the siliconized plate specimens mainly consisted of Fe3Si, while the surfaces of the chromized and borochromized steel plate specimens were mainly composed of Fe-Cr alloy and Cr2B phases, respectively. The borochromized specimens exhibited the highest microvickers hardness of all the plate specimens. Also, it was found that both the chromized and borochromized steel specimens exhibited friction coefficients as low as 0.2 in ethyl alcohol, and that the friction coefficients of the siliconized steel specimens were slightly lower than those of the non-coated steel specimens.
Sandwich Lightweight Design in Automotive Usage
Authors: Brückmann Simon M. , Friedrich Horst E. , Kopp Gundolf , Kriescher Michael
Published: May 2014

State of the Art
Aluminum Di-Borides for Engineered Surfaces for Low Friction Applications
Authors: Sudeep Ingole , Rajeshwari Paluri
Published: May 2014

Careful consideration of friction and wear could save the U.S. economy as much as $120 billion per year. Friction, wear, and lubrication have direct influence on the performance, reliability, and service life of a device that contains moving components. These components are found in applications of energy conversion, power generation, energy harvesting in the broader fields such as agriculture, transportation, and bioengineering etc. The useful life of these systems and their energy efficiency can further be improved by improving the surface performances of sliding systems.
Ceramics matrix multifunctional composite due to their unique properties are one of the alternatives for these applications. We report development of alumina based ceramic matrix composites (CMCs) with in-situ functional phases. The overview of properties will be provided. The mechanism for low friction will be discussed. In this investigation, the reinforcement (boron) addition showed strong influence on the in-situ phase formation and surface performance. The phase characterization confirmed formation of AlB2, B2O3, and Al18B4O33. The sintering temperature showed influence on the stability of these phases. The mixed mode failure was evident from the wear tests. It was found that the coefficient of friction was reduced up to 30% when compared to parent alumina. These newly designed multifunctional composites potential candidate materials that improve the energy efficiency and sustainability.
Dry Sliding Wear Behaviour of Magnesium Alloy Based Hybrid Composites in Transverse Direction
Authors: Mondal A.K. , Kumar S.
Published: May 2014

Wear behaviour of AE42 Mg alloy-based composites reinforced with Saffil short fibres (SSF) and SiC particles (SiCp) in various combinations has been investigated in transverse direction, i.e., the plane containing random fibre-orientation was parallel to the steel counter-face. Wear tests are conducted on a pin-on-disc set-up under dry sliding condition having a constant sliding velocity of 0.837 m/s for a constant sliding distance of 2.5 km in the load range of 10-40 N. It is observed that the hybrid composites reinforced with both SSF and SiCp exhibit better wear resistance than the composite reinforced with SSF alone, because SiCp are harder than SSF and remain intact retaining their load bearing capacity even at the highest load employed in the present investigation. The dominant wear mechanism is observed to be abrasion for all the composites. It is accompanied by fracture and pull-out of SSF from the worn surfaces. Wear behaviour of the composites in transverse direction is also compared with wear behaviour in longitudinal direction, i.e., the plane containing random fibre-orientation was perpendicular to the steel counter-face, reported earlier by the same authors. It is observed that the wear resistance of the composites in transverse direction is lower than that in longitudinal direction due to the lower load bearing capacity, the extensive fracture and pull-out of SSF from the worn surfaces.
Effect of Dispersibility of TiB2 Particles on Electrical Conductivity in TiB2/Al Composites
Authors: Sasaki Gen , Ishikawa Kota , Choi Yong Bum , Sugio Kenjiro , Mastugi Kazuhiro
Published: May 2014

20vol% TiB2 particle Al composites were fabricated by spark plasma sintering after blending TiB2 and Al particles. The dispersibility of TiB2 particles in composites was controlled by the blending method before sintering. Then the effect of the dispersibility on the electrical conductivity was estimated. As increasing the dispersibility, the electrical conductivity of the composites decreased. The dispersibility of TiB2 particles in composites was estimated by two-dimensional local number (LN2D), quantitatively. The theoretical value of electrical conductivity considering LN2D was estimated by the simulation of finite volume method and the Laplace equation of electric potential distribution. The tendency of low electrical conductivity of the composite with uniform distribution of TiB2 particles was confirmed by this simulation, but the experimental degradation of electrical conductivity for uniform distribution for clustering distribution was higher than that of theoretical value. The electrical conductivity of Al seems to be affected by the plastic deformation. There are the deformation regions around the interface between TiB2 particle and Al because of the difference of thermal expansion. Therefore, the quantity of the deformation region is increasing for increasing the dispersibility, and then the electrical conductivity of the composites decrease.
Performance of an Anode-Supported Honeycomb Solid Oxide Fuel Cell
Authors: Nakajima Hironori
Published: May 2014

An anode-supported honeycomb solid oxide fuel cell can work with high power density and improve thermo-mechanical durability at high temperatures. We have thus fabricated the honeycomb cell with an electrolyte layer of 8YSZ on an anode honeycomb substrate of Ni/8YSZ. The cathode layer is LSM-YSZ composite. Current-voltage and current-power density characteristics of the cells having different anode and cathode flow channel configurations are measured under different hydrogen flow rates. We also evaluate the hydrogen mole fraction distributions in the honeycomb cell using finite element method, and discuss appropriate anode and cathode flow channel configurations. The present study is a starting point of developing an anode-supported honeycomb cell for cell stacks assembled with multiple and large scale honeycomb cells which can achieve high efficiency flow channel and current collecting configurations, and enhanced thermo-mechanical durability.
Enhanced Performance of Ag-Doped Oxygen Electrode Based Solid Oxide Electrolyser Cell under High Temperature Electrolysis of Steam
Authors: Hu Su , Li Qing Shan , Zheng Yi Feng , Wei Shi Hao , Xu Cheng
Published: May 2014

Solid oxide electrolyser (SOE) has been receiving increasing attention due to its potential applications in large-scale hydrogen production and carbon dioxide recycling for fuels. Improving the performance of SOE cell through oxygen electrode development has been of main interest because the major polarization loss of the SOE cell is at the oxygen electrode during high temperature electrolysis (HTE). In the present study, Ag was doped into (La0.75Sr0.25)0.95MnO3+δ(LSM) based oxygen electrode of Ni/YSZ cathode-supported SOE cell through a solid state method enhanced by ball milling. Short stacks were manufactured using doped and undoped cells and tested under HTE of steam at 800°C up to 150h for in situ comparative study of doping effect. The cells with doped oxygen electrodes showed less polarization loss, lower resistance and improved performance by comparison with the undoped cell. Post-mortem examination revealed Ag migrated from the current collecting layer to the electrolyte/anode interface, which may promote the cell performance.
Friction Stir Welding of Al Alloys: Analysis through a Multi-Objective Optimization Tool
Authors: Cavaliere P.
Published: May 2014

Friction Stir Welding is a well known solid state joining technology. Many processing conditions and materials properties affect the microstructural evolution and mechanical behavior of the produced joints. The main parameters involved in the welding process have been studied and the results presented in the present paper. The fatigue life and crack behavior of several aluminum alloys FSW joints have been presented. The analysis was conducted through a multi-objective optimization tool capable of correlating all the material properties and processing parameters to the final mechanical performances of the welds.
Evaluation of FSW on High Yield Strength Steels for Shipbuilding
Authors: Rückert Guillaume , Chargy Myriam , Cortial François , Jorez François
Published: May 2014

FSW process has been evaluated on three shipbuilding steels (DH36, S690QL and 80HLES steels) by fully penetrated butt welds on 8mm thick plates. Non destructive tests were carried out to highlight the presence of intrinsic defects known for the welding process (eg kissing bond). The validated inspection methodology (volume and surface testing) confirm the integrity of welds and the absence of geometrical defects for examinations and mechanical tests as part of a qualification procedure.
Behavior of Decomposed Ammonia Borane at High Pressure up to ~10 GPa
Authors: Sun Yong Zhou , Chen Jiu Hua , Drozd Vadym , Najiba Shah
Published: May 2014

We conducted in situ Raman spectroscopy study on ammonia borane loaded in diamond anvil cell (DAC). The ammonia borane was decomposed at around 140 degree Celsius under the pressure ~0.7 GPa. Raman spectra show the hydrogen was desorbed within 1 hour at 140 degree Celsius. The hydrogen was sealed in the DAC well and cooled down near to room temperature. Applying higher pressure up to ~10 GPa indicates interactions between the products and loss of dihydrogen bonding. No rehydrogenation was detected in the pressure range investigated.Keywords: Ammonia borane; Diamond anvil cell; High pressure; Phase transition
Effect of Long-Term Creep on Microstructure of a 9% Cr Heat Resistant Steel
Authors: Dudko Valeriy , Fedoseeva Alexandra , Kozlov Pavel , Skorobogatykh Vladimir , Schenkova Izabella , Kaibyshev Rustam
Published: May 2014

The effect of long-term creep at 600°C under 137 MPa on the microstructure of a P92-type steel was investigated. The microstructure after tempering consisted of laths with an average thickness of 400 nm. Dispersion of secondary phases consists of M23C6 carbides with an average size of 85 nm located mainly on lath, block and prior austenite boundaries and MX carbonitrides with average size of 31 nm homogeniously distributed throughout. Creep with duration of 40738 hours led to coarsening of M23C6 carbides up to 182 nm. Precipitation of Laves phase with an average size of 290 nm took place in both grip and gauge portions of ruptured specimen. Vanadium-rich MX particles were replaced by particles of Z-phase with sizes of 97 and 48 nm after long-term creep and aging, respectively. The average misorientation of the lath boundaries was approximately 2° and scarcely varied during creep, while the mean lath thickness increased to 890 nm in gauge section of ruptured specimen and remained essentially unchanged in the grip section. Dislocation density decreased slightly under long-range aging and creep.
Production of SiC Materials by Reactive Infiltration
Authors: Caccia Mario , Narciso Javier
Published: May 2014

The use of oak sawdust as carbon precursor for SiC manufacture via reactive infiltration was studied. The effect of oak sawdust pressing parameters, temperature and pressure, on the final SiC's properties was studied. Final product's quality was evaluated through density measurement, and microstructure and pore size distribution variations were characterized with optical microscopy and mercury porosimetry. Pressed oak sawdust preforms were carbonized to obtain a carbon porous preform which was then infiltrated with melted silicon. Successful infiltration of preforms pressed at room temperatures were performed, to obtain a porous SiC. Hot pressed preforms were not satisfactory infiltrated due to a narrowing of their pores caused by SiC formation's expansiveness.
Effect of B2O3 Fluxing on Glass-Forming Ability and Soft Magnetic Properties of Fe(-Co)-B-Si-Nb Bulk Metallic Glasses
Authors: Bitoh Teruo
Published: May 2014

The effect of B2O3 fluxing on the glass-forming ability (GFA), the structure and the soft magnetic properties of Fe (-Co)-B-Si-Nb bulk metallic glasses (BMGs) has been investigated. The large Fe-Co-B-Si-Nb BMG specimens with diameters up to 7.7 mm, which is approximately 1.5 times as large as that of the maximum diameter of the copper mold cast one (= 5 mm), were prepared by the fluxing and water quenching. Thus the GFA of the Fe-Co-B-Si-Nb BMG are improved by the fluxing. It was confirmed that the soft magnetic properties of the Fe-Co-B-Si-Nb BMG are also improved by the fluxing. On the other hand, it was found for the Co-free Fe-B-Si-Nb BMG that the B2O3 fluxing promotes the precipitation of the α-Fe (-Si) and Fe2B phases in the central region of the specimens; i.e., the GFA of the Fe-B-Si-Nb BMG is decreased by the fluxing. The Fe-B-Si-Nb BMG specimens show a flat hysteresis loop, indicating a good linear relationship between the magnetic induction and the applied magnetic field. These results of the Fe-B-Si-Nb BMG show that it is possible to develop a new soft magnetic material that exhibits constant permeability, which is necessary for producing inductors and choke coils.