bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoluminescence of Laser-Synthesized Anatase Titanium Dioxide Nanopowders
Authors: Šćepanović M. , Dohčević-Mitrović Z. , Hinić I. , Grujić-Brojčin M. , Stanišić G. , Popović Zoran V.
Published: March 2009

Titanium dioxide (TiO2) nanopowders were prepared by laser-induced pyrolysis. Raman scattering showed that prepared TiO2 nanocrystals have anatase TiO2 structure. Specific surface area of the powders varies from 84 to 110 m2/g, while the grain size of nanoparticles is between 30 and 70 nm, depending on preparation conditions. We measured photoluminescence (PL) spectra of TiO2 nanocrystals. Under laser irradiation with photon energy between 2.41 and 2.71 eV the TiO2 nanocrystals displayed strong visible light emission, even at excitation power as low as 0.05 W/cm2. The line shape and position of this broad luminescence band vary with excitation energy. As PL spectra of anatase TiO2 can be attributed to three kinds of physical origins (self-trapped excitons, surface states and oxygen vacancies) in this paper we try to resolve which of them are dominant for different TiO2 nanopowders of different grain size.
Extraction of the Parameters from I-V Data for Nonideal Photodetectors: A Comparative Study
Authors: Vasić A. , Osmokrović P. , Lončar B. , Stanković S.
Published: March 2009

Parameters that characterize semiconductor devices are often determined with difficulty, and their values very frequently depend on the method used for measurements and analysis. The extraction of diode parameters from the obtained I-V measurements could be complicated by their dependence on the voltage and the presence of series resistance. Therefore, an interpretation of the experimental I-V data must be very carefully made. In this paper, some methods for obtaining diode
parameters such as saturation current, ideality factor and series resistance are presented. An evaluation of these methods based on their application for the extraction of the relevant parameters of photodiodes is also performed. Some of the methods that produce reliable and reproducible results are evaluated based on the experimentally obtained results, and in the view of the complexity of the used methods and their limitations.
Testing Polycrystal Plasticity Models on Observed Lattice Rotations and Dislocation Structures
Authors: Winther Grethe
Published: March 2009

This paper combines experimental evidence at the mesoscopic and microscopic levels of the physical slip underlying plastic deformation in an aluminium polycrystal in the evaluation of crystal plasticity models. At the mesoscopic level, lattice rotations of individual bulk grains during deformation have been measured using high-energy synchrotron radation (3DXRD). At the microscopic level, deformation induced dislocation structures have been investigated by transmission electron microscopy. The performance of two different versions of the Taylor model taking different approaches to the ambiguity problem is evaluated.
Quantitative Texture Analysis with the HIPPO TOF Diffractometer
Authors: Pehl J. , Matthies Siegfried , Wenk H.R. , Lutterotti Luca , Vogel Sven C.
Published: March 2009

One of the design goals of the neutron time-of-flight (TOF) diffractometer HIPPO (HIgh Pressure - Preferred Orientation) at LANSCE (Los Alamos Neutron Science Center) was efficient quantitative texture analysis. In this paper, the effects of the HIPPO detector geometry and layout on texture analysis, particularly the shape and dimensions of the detector panels, are investigated. An aluminum sample with a strong and asymmetric texture was used to determine the methodological limitations of various methods of quantitative texture analysis. Several algorithms for extracting the orientation distribution function (ODF) from the TOF-spectra are compared: discrete orientations at arbitrary positions, harmonic method in Rietveld codes (MAUD and GSAS) and discrete methods in MAUD. All methods provide a similar representation of the main texture component, but discrete methods have a fundamental advantage over harmonic methods in characterizing regions of the ODF with low orientation densities. For HIPPO data of the present sample, harmonic expansions beyond lmax= 12 introduce subsidiary maxima and minima, which are consistently identified as artifacts. The results of our analysis establishes HIPPO as an efficient instrument to quantitatively determine preferred orientations in relatively short measuring times, if the texture features are not exceedingly sharp (full-width at half-maximum (FWHM) in the ODF > 20-30°).
Transformation Textures in Steels
Authors: Hutchinson W. Bevis , Ryde Lena , Bate Pete S.
Published: March 2009

The mechanisms by which textures can be inherited in transformed phases are discussed in the light of different transformation mechanisms. Possible origins of variant selection in the different cases are reviewed and classified. Evidence is presented for a hitherto unsuspected source of variant selection that arises from the stresses which are generated during transformation due to the presence of micro-segregation. Some model predictions show the potential effect of this phenomenon on textures in bainite or martensite.
Texture Evolution during Grain Growth under the Influence of Mechanical Stresses
Authors: Winning Myrjam
Published: March 2009

In order to study the influence of mechanical stress fields on the kinetics and texture evolution of grain growth, experiments were performed on high purity aluminium. Samples were annealed under the influence of different mechanical stresses. The temporal evolutions of grain sizes and of macrotexture were analysed in ependence on the applied stress. The results show that mechanical stresses can change the kinetics of grain growth and slow down the increase in the grain size. Also effects on the texture evolution were observed and shall be discussed.
The Orientations of Nuclei at Triple Junctions in Deformed Columnar Grain Ni
Authors: Wu Gui Lin , Godfrey Andrew , Juul Jensen Dorte , Liu Qing
Published: March 2009

Ni with columnar grain was cold rolled and then recrystallized. The orientations at triple junctions before and after annealing were characterised using the EBSD technique, and recrystallization nuclei at triple junctions were identified. A comparison was made between the orientations of the nuclei and the orientations of the grains in the same area before annealing. Both nuclei with orientations within the orientation spread of the deformed grains as well as away from that were found.
Texture Determination of Thin Cu-Wires by Synchrotron Radiation
Authors: Brokmeier Heinz Günter , Weiss Brigitte , Yi Sang Bong , Yi Wenhai Ye , Liss Klaus Dieter , Lippmann Thomas
Published: March 2009

A new method to investigate thin wires has been tested, which is based on a special sample holder and on a high energy X-rays. Due to the high penetration power of high energy Xrays quantitative texture data will be obtained without any additional corrections such as constant volume correction and absorption correction. The measurements have been carried out at the high energy beam line BW5 at HASYLAB – DESY (Hamburg). In order to overcome grain statistics problems on the investigated Cu-wire of 122µm thickness a special scanning routine together with the sample preparation allows to average over a wire length between 1mm and up to 240 mm.
Measurement of High-Resolution Recrystallization Textures in Nickel Sheets Using High-Energy Synchrotron Radiation
Authors: Klein Helmut , Preusser Andrea , Raue Lars , Bunge Hans Joachim
Published: March 2009

The new developed “sweeping detector” techniques using high energy synchrotron radiation allow to measure textures and microstructures of materials and their change during heat treatment with high location and orientation resolution.
Here we show these new methods applied to cold rolled and subsequently annealed nickel samples. The grain-resolved measurements show, impressively, many details of the recrystallization process which can otherwise not be seen. The results of these measurements can be the base for omprehensive recrystallization theories.
Effect of Hot Working on the Microstructure and Thermoelectric Characteristics of (Bi, Pb)-(Sr, Y)-Co-O Oxide
Authors: Fukutomi Hiroshi , Iguchi Eisuke , Ogawa Nobuyuki
Published: March 2009

Thermoelectric oxides consisting of Bi, Pb, Sr, Y and Co are produced by usual sintering method. Uniaxial compression deformation is performed on the oxides under various deformation conditions. Melting temperature is determined by thermal analysis and deformation is conducted close to the melting point. After deformation, density, microstructure, texture and thermoelectric characteristics are experimentally examined. It is found that the oxides plastically deforms at high temperatures, resulting in an increase in density as well as the development of textures. The sharpness of the texture varies depending on deformation temperature, strain rate and the amount of strain. Microstructure observation by SEM elucidates that plastic deformation proceeds without generating severe cracks and all the grains are heavily deformed. Simple examination on the crystal structure suggests that perfect dislocation having small Burgers vector can move on {001} which coincides with the texture results.
The Role of Special Boundaries during Solidification and Microstructure Evolution in Lead Free Solder Joints
Authors: Telang Adwait U. , Bieler Thomas R.
Published: March 2009

Solder joints based on Sn-Ag used in electronic systems fail due to thermomechanical fatigue (TMF) damage that develops during service. Grain boundary sliding and/or shear band formation are observed during TMF. Orientation Imaging Microscopy (OIM) was used to study the damage that develops and relate it to slip systems and the grain boundary character that is prevalent in tin. A number of special boundaries form preferentially during solidification, and those with misorientations about a [110] axis, including low angle boundaries, are more likely to slide with thermal cycling. Special boundaries aligned to have large resolved shear stress exhibit large scale sliding, and others with normal stress components exhibit fracture. Damage accumulation depends on the deformation mode, temperature, and initial crystal orientations present in the joint.
Simulation of Texture Development of Plane Carbon Steel in Multipass Rolling Using Analytical Flow Function
Authors: Beausir Benoît , Tóth László S. , Bouaziz Olivier
Published: March 2009

Using a simple analytical flow function, an analysis of the deformation field in symmetrical rolling has been carried out. The so-obtained varying velocity gradient is incorporated into the Taylor polycrystal plasticity model to simulate the development of the deformation texture. The initial discontinuity in the deformation field of the entering material element on the flow lines is also taken into account. Multiple passes of the material is simulated. A strong texture gradient is obtained in good agreement with experiments carried out for rolling of plane carbon steel. It is shown that the shear component of the texture is strongly related to the nature of multiple passes of the rolling operation.
Synchrotron Radiation Investigation of Twinning in Extruded Magnesium Alloy AZ3l
Authors: Davies Chris H.J. , Yi Sang Bong , Bohlen Jan , Kainer Karl Ulrich , Brokmeier Heinz Günter
Published: March 2009

The crystallographic response to deformation – texture evolution, internal elastic strain, and twin evolution – was measured for three load/orientation variants for AZ31 magnesium alloy extrudate tested in-situ in a synchrotron beamline. Specimens were loaded in tension parallel to the extrudate transverse direction, in compression along the same axis, and in compression parallel to the extrudate normal direction. The crystallographic responses are correlated with the mechanical behaviour of the extrudate.
Unbiased Evaluation of Chord Length Distributions from Orientation Maps
Authors: Pantleon Wolfgang
Published: March 2009

Grain structures in crystalline material are commonly identied by orientation inhomogeneities in orientation maps. A statistical approach is introduced to extract quantitative information on the chord length distribution of grains from orientation data gathered by electron back-scattering diffraction.
Investigation of Measured Pole Figures Errors
Authors: Nikolayev D.I. , Lychagina T.A. , Nikishin A.V. , Yudin V.V.
Published: March 2009

The objective of the present work is to study of errors on measured pole figures of
hexagonal materials. We used neutron time-of-flight (TOF) technique for texture measurements and obtained spectra for estimating of error values of measured pole figures. Peak profile analysis of an each individual spectrum allows gain pole figure value itself and the corresponding error at each pole figure point as well. Such results could be obtained for measurements on stationary source of radiation with the usage of a position sensitive detector.
Effect of the Rolling Draughts on the Evolution of Textures and Microstructures in 17.5 Cr-1.1 Mo Ferritic Stainless Steel Sheet
Authors: Park Soo Ho , Kang Hyung Gu , Lee Yong Deuk , Lee Jae Chul , Huh Moo Young
Published: March 2009

In order to investigate the effect of the reduction degree per rolling pass on the evolution of recrystallization textures and microstructures, the hot band of 17.5 Cr-1.1 Mo ferritic stainless steel sheets were cold rolled with lubrication according to two processing routes, by which different reduction degrees per pass were introduced. Rolling with a large number of passes led to the formation of fairly homogeneous rolling textures at all through-thickness positions. In contrast, cold rolling with large draughts resulted in pronounced texture gradients along the thickness direction. After recrystallization annealing, the texture maximum was obtained at {334}<483> in all samples regardless of the rolling routes and thickness layers. During subsequent annealing, recrystallization was observed to be faster in those grains with {111} orientations, while it was retarded in grains having orientations close to {001}<110>.
The Effect of Initial Orientation and Rolling Schedule on Texture Development in Duplex Steel
Authors: Ryś Janusz , Ratuszek Wiktoria , Witkowska Małgorzata
Published: March 2009

A development of deformation textures was examined in ferritic-austenitic duplex type steel subjected to cold-rolling within the range up to 90% of reduction by applying different rolling schedules. The investigations included X-ray phase analysis, texture measurements and microstructure observations by means of light microscopy. The experimental results indicate at the occurrence of strong initial textures in both component phases after preliminary thermo-mechanical treatment. Formation of the ferrite-austenite banded structure in the course of rolling along with the stability of major texture components, related by Bain orientation relationship, exert considerable effect on the development of the ferrite and austenite rolling textures.
Analysis of Texture Formation and Microstructure Characteristics of Cold Rolled IF Steel Sheets
Authors: Cai Y.X. , Liu Y.D. , Wang Yi Nong , Wang Gang , Wang Yan Dong , Wang Fu Hui , Zuo Liang
Published: March 2009

The aim of this work is to investigate the relationship between the deformation microstructure and texture in cold rolled Interstitial Free (IF) steel sheets. In the present research, the cold rolled IF steel sheets with 10%-50% reductions are used to observe the characteristic microstructure and individual orientations by transmission electron microscopy (TEM) and SAED patterns. The experimental results on inter-granular strain homogeneity and dislocation wall formation are given in details in this paper. The results are explained by the analysis of crystallographic gliding and are helpful to improve the prediction of cold rolling textures.
Development of Cold Rolling and Intercritical Annealing Texture in Two TRIP-Aided Steels
Authors: Emadodin E. , Akbarzadeh A.
Published: March 2009

High strength TRIP-aided steel sheets with high formability and better ductility are
of industrial interest. Texture control and retained austenite characterization are considered as the main factors with respect to the formability and ductility. In this work, the effect of cold rolling and intercritical annealing on texture development has
been investigated for two TRIP-aided steel sheets, which are different in Si and Al content. Experiments show that the cold rolling extends the a and g–fibers on these grades of steel. Intercretically annealing decreases the intensity of a–fiber and leads to sharpness of g–fiber, especially for Al steel.
Bulk Texture and Structure Changes in Tubes of Zr Alloys due to the Long-Range Effect of Ion-Plasma Surface Treatment
Authors: Perlovich Yuriy , Grekhov M. , Isaenkova Margarita , Fesenko Vladimir , Kalin B. , Yakushin V.
Published: March 2009

Irradiation of metal materials with low-energy ions is accompanied by the long-range
effect, consisting in distinct texture and structure changes at the depth, exceeding, at least, by 104 times the thickness of the layer of ion retardation. In order to ascertain mechanisms of this effect, a layer-by-layer X-ray study was carried out as applied to ion-plasma treated cladding tubes of Zr- 1%Nb alloy for nuclear reactors. Impacts of pulse treatments with helium plasma by two different regimes and the ion energy of ~ 1 keV were compared. It was found, that only by minimal surface melting the ion-plasma treatment causes unpredictable bulk texture changes, consisting in arising of the axial texture component. The melted surface layer suppresses shock waves, associated with braking of ions and supposedly responsible for stimulation of dislocation processes at long distances from the surface.
Textures and Local Textures in Severely Cold-Rolled and Annealed Ultra-Fine-Grained FeCo Alloy
Authors: Deng J.N. , Bouzy Emmanuel , Fundenberger Jean-Jacques , Peng Ru Lin , He Chang Shu , Zhang D.Z. , Wang Yan Dong
Published: March 2009

We find that a severely rolled FeCo alloy has anomalous enhancement of the rotated-cube {100}<011> texture component and a decrease of the {111} components after annealing, which is contrast to the recrystallization behaviors reported in traditional BCC metals and alloys. The local texture measurements show that two kinds of grains with obviously different orientations, i.e. {100} and {111}, are heterogeneously distributed in the deformed specimen and the migration of high-angle grain boundaries is observed after annealing in the disordering temperature region.
Formation of Inhomogeneous Texture and Structure in Metal Materials under Equal-Channel Angular Pressing
Authors: Isaenkova Margarita , Perlovich Yuriy , Fesenko Vladimir , Grekhov M. , Alexandrov Igor V. , Beyerlein Irene J.
Published: March 2009

Texture analysis and the new X-ray method of Generalized Pole Figures (GPF) were used by the study of texture and substructure inhomogeneity of Ti rods, submitted to Equal-Channel Angular Pressing (ECAP) at 400oC. Local texture features testify about gradual rotation of loading axes by ~15o when crossing the rod’s section. As a result of second pass (route C), the specific ECAP texture weakens and the textureless component intensifies. Observed substructure changes are connected with development of dynamic recovery and dynamic recrystallization.
Textural and Microstructural Inhomogeneities in Drawn and Annealed OFHC Copper Wire
Authors: Waryoba Daudi R. , Kalu Peter N.
Published: March 2009

This work presents the results of a study on textural and microstructural inhomogeneities that develop during annealing of heavily drawn Oxygen free high conducting (OFHC) copper wire. The wire was drawn at room temperature to a true strain of 2.31 and isothermally annealed at 750°C for annealing times ranging from 10s to 1hr. The inhomogeneity of microstructure across the wire was clearly visible as three distinct concentric regions, which were classified as: the inner core, the mid section, and the outer surface. Two texture transitions were observed. At shorter annealing time, recrystallization which originated from the mid section, resulted into a strong<100>+weak<111> duplex fiber texture. However, prolonged annealing gave rise to abnormal grain-growth that proceed from the mid section to the outer surfaces with a dominant <111> fiber component at the mid and inner region, and mixed components of <111>, <100>, and <112> at the outer surfaces.
Local Texture Evolution by Rate-Independent Polycrystal Model Allowing for Coordination of Interacting Crystals
Authors: Zisman A.A. , Zolotorevsky Nikolay Y. , Ermakova N.Yu.
Published: March 2009

A rate-independent polycrystal model, allowing for the shape and spatial coordination of neighboring constitutive crystals and for the plastic strain distribution among them, has been used to simulate the local texture evolution in an Al polycrystal under compression. The simulation results compare favourably to relevant experimental data and show the reorientation path of each crystal to strongly depend on orientations of its immediate neighbors.
An Intermediate Viscoplastic Model for Deformation Texture Evolution in Polycrystals
Authors: M'Guil S. , Ahzi Saïd
Published: March 2009

The aim of this work is to discuss a new non linear intermediate model for large
viscoplastic deformations that could predict the texture transition and stress-strain behavior in a range that spans from the upper bound (Taylor) to the lower bound (Sachs or static) estimates. In this model, we introduced a single parameter, f , as a weight function to formulate the proposed intermediate approach which combines the Taylor and Sachs estimates. This formulation leads to an interaction law by the minimization of a tensorial function which depends on the parameter f . For the applications, we focus on the uniaxial tension test. The results for texture evolution in an FCC polycrystal show that a transition between the copper type and brass type textures can be obtained by the proposed non-linear intermediate model.
Study of the Diamond 5%wt- Cobalt Sintering under the HPHT Lowest Limit
Authors: Lima F.T.C. , Bobrovinitchii Guerold Sergueevitch , Filgueira Marcello
Published: March 2009

Diamond composites consist in the diamond powder mixed with a binder phase, which sintering is carried out by means of the High Pressure-High Temperature (HPHT) techniques. These composites are widely used in the cutters of drillers for the oil industry, and as inserts for machining. In this work was used a mix of diamond + 5% weight cobalt. Sintering was accomplished under the HPHT Lowest Limit conditions: P=7GPa and T=15000C for times of t=10-30-60 seconds, aiming at the densification study under these conditions. Results are shown as a function of the sintered micro-structure evolution, cobalt influence on densification, graphitization, and hardness of the sintered parts.
Deposition of Sn-Al Onto Aluminum Powder in Its Self-Convective Motion by DC Sputtering
Authors: Sonoda Tsutomu , Watazu Akira , Kato Kazumi , Asahina Tadashi
Published: March 2009

The deposition of Sn-5wt.%Al alloy onto pure aluminum powder in its self-convective motion by magnetron DC sputtering was examined in order to prepare Al-Sn composite particles, aiming not only at the development of highly uniform sintered binary compact materials but also at the improvement of the bonding between the aluminum particles after sintering at low temperature such as 250°C. The self-convection phenomenon of the aluminum powder in the vacuum chamber occurred when a perpendicular vibration was applied to the powder. The sputter-deposition of the Sn-Al alloy was carried out during the self-convection of the aluminum powder. Under SEM and according to EPMA analysis, as well as according to thermal analysis with DSC, it was confirmed that the obtained particles were coated with the Sn-Al deposits. Therefore it was found that Sn-Al composite powder could be produced by this processing, and thereby not only the development of highly uniform sintered binary compact materials but also the improvement of the bonding between the aluminum particles after sintering at low temperature were expected.
Humidity Sensitive Characteristics of ZnO-TiO2-Ta2O5 Ceramic
Authors: Mineiro Sergio Luiz , Nono Maria do Carmo de Andrade , Kuranaga Carlos , Silva M.D.
Published: March 2009

The humidity sensing behavior of a ceramic oxide based on the ZnO-TiO2-Ta2O5 system was analyzed. Samples were uniaxially pressed and sintered at temperature range from 1000 to 1200oC. Electrical impedance and capacitance measurements were realized in different values of relative humidity (from 11 to 100%). The microstructures of the sintered samples were characterized by X-ray diffractions and SEM observations. Mercury porosimetry analyses were carried out to determine the open porosity and the surface area was measured by using the BET nitrogen method. The obtained results were correlated and discussed.
Using Experiments Design to Model Linear Firing Shrinkage of Triaxial Ceramic Bodies
Authors: Correia Sivaldo Leite , Curto K.A.S. , Hotza Dachamir , Segadães Ana M.
Published: March 2009

In the development and manufacture stages of floor and wall ceramic tiles, firing shrinkage is basically determined by the combination of raw materials and frequently used as quality control parameters. This configures the ideal scenario to apply the techniques of experiments design, often used in various other areas, to model those properties of such ceramics bodies. In this work, ten formulations of three different raw materials, namely a clay mixture, potash feldspar and quartz (triaxial compositions) were selected and processed under conditions similar to those used in the ceramics industry. With the experimental results, a regression model was calculated, relating linear shrinkage with composition. After statistical analysis and verification experiments, the significance and validity of the model was confirmed. The regression model can then be used to select the best combination of those three raw materials to produce a ceramic body with specified properties.
Replacing Coal by Tire Powder in Ceramic Industry
Authors: Mothé Cheila G. , Mothé Filho Heitor F.
Published: March 2009

Nowadays preserving nature, recycling or reusing materials are good policies. Around ten million tires are put out by year in Brazil, and it is not known for how long they will remain in environment till their complete degradation. This research used tires to replace coal in ceramic processing. In this way it helps to protect environment, to reduce the consumption of mineral deposits and to save money. Results show that tire powder can replace coal to obtain ceramic material, using one percent of tire. Experiments were carried out using TA instruments SDT 2960, in air or nitrogen atmospheres, at heating rate of 10°C/min., flow 120ml/min. TG/DTA curves of tire and coal have exothermic events at close temperatures between 450-600°C. At range of temperatures clay have endothermic events.
Anelastic Spectroscopy in TiO2
Authors: Grandini Carlos Roberto , Oliveira R.L.N. , Mota Rogério Pinto , Santos F.P. , de Campos Élson
Published: March 2009

Titanium dioxide (rutile) has a lot of interesting and useful features and hence is widely utilized for application. It has been used as white pigment, photocatalyst, biocompatible material and semiconductor material used in solar battery. In semiconducting TiO2 oxygen vacancies are said to play an important role in the electrical conduction. Measurements of the elastic energy loss and modulus (anelastic spectroscopy) as a function of temperature can distinguish among the different atomic jumps, which occur in the various phases or at different local ordering. In this paper, it is reported anelastic relaxation measurements in TiO2 samples using a torsion pendulum operating in frequencies around 40Hz, in the temperature range between -173 oC to 330 oC with heating rate of 1 oC/min. The results shown a reduction in the elasticity modulus with the increase in the corn starch content used for this consolidation.
Effect of the Calcination Time of Fish Bones in the Synthesis of Hydroxyapatite
Authors: Lima W.M. , Weinand W.R. , dos Santos O.A.A. , Paesano A. , Ortega F.H.M.
Published: March 2009

In this work, a combination of methods for HAp synthesis is investigated. Fish bones were calcined at 900oC between 4h and 12h, followed by milling in a high-energy ball mill, by 2h and 4h at 300rpm. The obtained material was characterized by using techniques such as laser granulometry, X-ray diffraction, scanning electron microscopy (SEM) and atomic absorption spectroscopy. The performed analysis permitted us to obtain the Ca/P ratio, the morphology and the phase structure of hydroxyapatite particles powder.
Obtaining of the Ceramics Pigments (Fe, Zn)Cr2O4 Using Waste of Electroplating as Raw Material
Authors: Milanez K.W. , Kuhnen N.C. , Riella Humberto Gracher , Kniess C.T.
Published: March 2009

The solid material from electroplating wastewater treatment was used as raw material in synthesis of ceramic pigments, once the formation of ZnCr2O4 and FeCr2O4 crystalline phases can be considered as a process of heavy metals inertization, such as chromium, zinc and iron. To reach the purpose of this paper, the techniques of elementary chemical analysis (Atomic Absorption Spectroscopy and X-Ray Fluorescence, thermal analysis (DTA/TGA) and X-Ray Diffraction were applied in samples of waste with the aim of physical and chemical characterization. After the characterization of residue were incorporate metallic oxides for correction of composition and obtaining of inorganic pigment. Pigment formation was followed through X-ray diffraction, where the formation of spinel phases containing the metals Fe, Cr and Zn were observed. The pigment was characterized through scanning electron microscopy, differential thermal analysis and thermogravimetry. The 8 hours cycle calcinated pigments formed crystalline spinel phases, where we can say that the present metals in the sludge became inert. It was possible to incorporate up to 20% of the galvanic waste in the production of Fe, Cr and Zn based inorganic pigments.
Particle Size Distribution Analysis of an Alumina Powder: Influence of Some Dispersants, pH and Supersonic Vibration
Authors: Papini C.J. , Yoshito Walter Kenji , Gouvêa Douglas , Neto Ricardo Mendes Leal
Published: March 2009

It is well known that colloidal powder particles (between 1 mm and 0.001 mm) tend to agglomerate due to electrostatic forces. Then assuring an optimal dispersion condition is essential for good particle-size analysis results, since aggregates or weak agglomerates can be measured as single particles. In this paper the particle size distribution of an alumina powder A1000SG (ALCOA) was measured using distinct dispersion procedures. Distilled water was used as dispersant liquid in the pure state and with additives (citric acid and Duramax D-3005). Dispersion by supersonic vibration was also investigated, but only the application time was varied. Particle size analysis was accomplished by laser scattering technique and the dispersion condition was evaluated through zeta potential. The results showed that the Duramax’s electrosteric impediment is more efficient than citric acid’s electrostatic force, thereby providing better dispersion. Although useful, the supersonic vibration was not good enough to assure an optimal dispersion, at least for the material tested here.
Corrosion and Cytotoxicity Evaluation of AISI 316L Stainless Steel Produced by Powder Injection Molding (PIM) Technology
Authors: Costa Isolda , Rogero Sizue Ota , Correa Olandir Vercino , Kunioshi Clarice Terui , Saiki Mitiko
Published: March 2009

This study investigates the in vitro corrosion and cytotoxicity response of AISI 316L stainless steel produced by powder injection molding (PIM) technology in a solution that simulates physiological fluids (MEM) by electrochemical techniques and neutral red uptake cytotoxicity assay. The results were compared with those of AISI 316L produced by conventional metallurgy. Both steels showed high corrosion resistance and no toxic effect in the cytotoxicity test. The corrosion products were analyzed by instrumental neutron activation analysis (INAA). The surfaces of the alloys were evaluated before and after corrosion test by scanning electron microscopy and a passive behaviour was indicated supporting the results from other techniques.
Centrifugal Atomization of Metals: Thermodynamics of the Process
Authors: Bobrovinitchii Guerold Sergueevitch , Filgueira Marcello
Published: March 2009

A complete description of the parts of a centrifugal atomizer, with geometries and dimensions are shown. Tests of atomization were carried out by using pure tin metal in air atmosphere. Mathematical simulation of the thermodynamics of the process was successful to describe the centrifugal atomization, showing a maximum experimental correspondence mismatch of 14%.
A New Model for Interpass Softening Based on the Strain Hardening Rate Prior to Unloading
Authors: Jonas John J. , Poliak Evgueni I.
Published: March 2009

It is shown that the kinetics of softening between mill passes can be modeled more
simply when the normalized strain (reduction) per pass is employed rather than the conventional strain. This method requires a second important input, namely the strain hardening rate at the end of preloading. Using this approach, the number of input parameters and experiments required for their determination are drastically reduced. The use of the Law of Mixtures to describe the behaviors of the recrystallized and unrecrystallized volume fractions is then illustrated. Finally, the approach required for quantifying the precipitation kinetics (in microalloyed steels) is described.
Application of Deformation to Improve Hot Ductility in the Peritectic Steel
Authors: Rezaeian Ahmad , Zarandi Faramarz , Bai D.Q. , Yue Steve
Published: March 2009

The hot strip rolling of advanced microalloyed high strength steels still represents a new task to many mills due to the lack of data on the hot deformation resistance. With the aid of processing data from the Ispat-Inland hot strip mill, the “measured mean flow stresses” are calculated from the mill force using the Sims analysis and taking into account roll flattening, slip ratio and the redundant strain. A modification of the Misaka mean flow stress equation is proposed for C – Mn – Si – Al steels microalloyed with up to 0.02 % Nb. The effects of alloying and microalloying are then estimated. A new fitting parameter shows excellent agreement with the mean flow stress data from industrial processing of advanced high strength microalloyed steels. However, during the second half of the rolling schedule (lower temperature region), indications of austeniteto- ferrite transformation were found.
Vanadium Microalloyed Steel for Thin Slab Casting and Direct Rolling
Authors: Li Yu , Baker T.N.
Published: March 2009

Vanadium microalloyed steels with high yield strength (»600MPa), good toughness and ductility have been successfully produced in commercial thin slab casting plants employing direct rolling after casting. Because of the high solubility of VN and VC, most of the vanadium is likely to remain in solution during casting, equalisation and rolling. While some vanadium is precipitated in austenite as cuboids and pins the grain boundaries, a major fraction is available for dispersion strengthening of ferrite. Despite a coarse as-cast grain size, significant grain refinement can be achieved by repeated recrystallisation during hot rolling. Consequently, a fine and uniform ferrite grain structure is produced in the final strip. Increasing the V and N levels increases dispersion strengthening which occurs together with a finer ferrite grain size. The addition of titanium to a vanadium containing steel, decreases the yield strength due to the formation of V-Ti(N) particles in austenite during both casting and equalisation. These large particles reduced the amount of V and N available for subsequent precipitation of fine (~5nm) V rich dispersion strengthening particles in ferrite.
Optimization of Rolling Conditions in Nb Microalloyed Steel Processed by Thin Slab Casting and Direct Rolling Route: Processing Maps
Authors: Uranga P. , Fernández-Calvo Ana Isabel , López Beatriz , Rodriguez-Ibabe J.M.
Published: March 2009

The microstructural evolution during the hot rolling of coarse grain sized austenite has been modeled taking into consideration all the microstructural mechanisms (dynamic, static and metadynamic recrystallization, strain induced precipitation) that could take place during the industrial TSDR production of a Nb microalloyed steel. Based on the results obtained from the model, processing maps have been drawn for a 0.035%Nb microalloyed steel. Optimum processing conditions to exploit all the benefits of Nb microalloying have been defined considering a final gauge thickness range between 1.5 and 12.65 mm.
Development of CSP® Processed High Strength Pipe Steels
Authors: Reip C.-P. , Hennig W. , Kempken J. , Hagmann R.
Published: March 2009

The CSP thin-slab technology (Compact Strip Production) provides a highly developed technical process for hot strip grades at low production costs. CSP combines the process stages of casting and rolling, which are discontinuous in the conventional process. This allows advantages to be achieved in terms of investments, energy consumption and operating costs. This paper describes the development work in progress, using the example of API steel grades. Key aspects of hot strip production such as alloying strategy, casting conditions, pass schedule
design and the course of cooling are discussed and the resulting range of material properties is outlined. It can be demonstrated that CSP-produced hot strips feature very good toughness at low temperatures and may even allow applications which call for sour gas resistance.
Processing and Stability of Ultrafine Grained Structures in Some Microalloy Steels
Authors: Pan L.X. , Karjalainen L. Pentti , Somani Mahesh C.
Published: March 2009

The dynamic strain-induced transformation (DSIT) of ferrite from austenite in intense deformation at temperatures close to Ar3 were applied to one C-Mn steel and several Nb and Nb-Ti microalloy steels to obtain an ultrafine ferrite grain size. As another route the static recrystallisation of severely cold-rolled martensite (SRM) was utilized. It was found that in the DSIT route a fine prior austenite grain size was crucial to form ferrite with the grain size of 1-3 µm with a considerable fraction of a secondary phase, carbide aggregate/pearlite or martensite. Grain sizes
achieved were somewhat finer in steels with a higher microalloying content. In the SRM route, the ferrite grain size of 1-1.5 µm was obtained by using the cold rolling of 80-90% reduction. Thermal stability of the ultrafine-grained structures, especially those from the DSIT route, was found to be excellent. In electron or laser beam welding of 1-2.5 mm sheets neither any coarse-grained zone existed in the heat-affected zone, nor did form any softened zone.
Thermomechanically Hot Rolled High and Ultra High Strength Steel Grades - Processing, Properties and Application
Authors: Klein M. , Spindler H. , Luger A. , Rauch R. , Stiaszny P. , Eigelsberger M.
Published: March 2009

In all application fields for hot rolled strip products for direct processing, e.g.
construction and engineering but also crane and truck industry, there is a strong customers demand for grades with increased strength levels and well balanced formability. At voestalpine Stahl GmbH these requirements were met with the development of the high strength microalloyed steel grade ALFORM700M and the ultra high strength steel grade ALFORM900M with a minimum yield strength (YS) of 700 MPa and 900 MPa, respectively. In the present paper investigations on the steel grades ALFORM700M and ALFORM900M are introduced. To explain the evolution of the obtained complex microstructures consisting of bainitic ferrite, bainite and martensite alloy design and industrial production process is discussed on
the base of dilatometric experiments and TEM investigations. The formation of precipitates is studied by using a numerical model, chemical methods and mechanical testing after heat treatment. Mechanical and mechanic-technological properties of the two steel grades are compared. Furthermore, some processing aspects as weldability an bending behaviour are highlighted. Finally, some typical applications for this high and ultra high strength steel grades are presented.
Vanadium Carbide Dissolution during Austenitisation of a Model Microalloyed FeCV Steel
Authors: Acevedo Reyes Daniel , Perez Michel , Pecoraro Stéphane , Vincent Alain , Epicier Thierry , Dierickx Pierre
Published: March 2009

High performance commercial micro alloyed steels contain elements such as vanadium, which leads to a fine dispersion of vanadium carbide precipitates. The precipitation state, in terms of volume fraction and size distribution, plays a significant role in final mechanical properties of the material. Different austenitisation heat treatments were performed on a model ternary alloy FeCV. Precipitation states were characterised combining different experimental techniques. TEM was used to identify the chemical composition of observed precipitates. ICP mass spectroscopy was performed to measure the volume fraction of precipitates. The size distribution was studied by SEM. Results are characteristic of a coarsening regime.
Activity Measurement of Liquid Sn-Ag-Bi Alloys by Fused Salt EMF Method
Authors: Katayama Iwao , Tanaka Toshihiro , Akai Shin-ichi , Yamazaki Kisao , Iida Takamichi
Published: March 2009

Activity of tin in liquid Sn-Ag-Bi alloys was derived by EMF measurement of galvanic cell with fused salts electrolyte in the temperature range of 700 to 900K in the whole composition range. Activity of tin at 900K shows very small positive deviation from Raoult’s low for Sn-Bi alloys. Activity of ternary alloys was measured along three pseudo binary systems of Sn-(Ag,Bi) (where xAg/xBi =1/3,1/1 and 3/1). Its concentration dependence is very complex. From the iso-activity curves in the ternary system excess free energy of mixing is derived using Darken’s method for Gibbs-Duhem equation
Transmission Electron Microscopy Observations on Cu-Ti Alloy Systems
Authors: Nishio Rimi , Konno Toyohiko J. , Semboshi Satoshi
Published: March 2009

Phase separation behaviors of a quenched Cu-3.0at%Ti alloy, as well as crystallographic structures of Cu-20.7at%Ti alloy have been studied using transmission electron microscopy. The furnacecooled Cu-20.7at%Ti alloy are composed of a-Cu4Ti (Ni4Mo-type) and b-Cu4Ti (Au4Zr-type) with the orientation relationship of (011)a//(110)b, [100]a//[001]b. As-quenched Cu-3.0at%Ti alloy showed a modulated structure with the modulation length of about 4 nm. When aged at 723K for 8 hr, the a-Cu4Ti phase emerges within the modulated or tweed-like microstructure. Prolonged aging results in the growth of the a-Cu4Ti particles and the loss of coherency. It is likely that asquenched Cu-3.0at%Ti alloy decomposes spinodally at 723K, followed by polymorphous ordering; though the present study did not exclude, as an alternative path, a decomposition mechanism based on the catastrophic nucleation.
Microstructure and High Temperature Deformation of Grain Refined Al Alloy Foil Fabricated by RF Magnetron Sputtering
Authors: Shibayanagi Toshiya , Watanabe D. , Maeda Masakatsu , Takayama Yoshimasa , Naka Masaaki
Published: March 2009

The present paper describes microstructure and mechanical properties of a grain refined Al alloy foils fabricated by RF magnetron sputtering method utilizing a commercial 7475Al alloy as a sputtering target. Microstructure of deposited foils was evaluated by means of SEM, TEM, SEM-EPMA and X-ray diffraction methods. Mechanical properties were analyzed by the Vickers hardness test and by tensile test at various temperatures. Columnar grains having a mixed grain size ranging from some hundreds microns to 1 micron on the planar section was obtained, and the foils were super-saturated solid solution with FCC structure. The foils contained less Mg content than the sputtering target. Superplastic deformation was observed for the foils at elevated temperature and the maximum elongation of 370% was obtained when deformed at 863K with the initial strain rate of 1.4 x 10-1s-1.
Manipulation Mechanisms for Micro-Assembly Technology
Authors: Takahashi Kunio
Published: March 2009

Author has been working about mechanisms of some manipulation methods for micro-assembly, i.e., a mechanical method, an electro-adhesive method, and a capillary method. For the purpose of optimization and breakthrough of the micro-assembly technology, theoretical understanding of adhesion phenomenon is essential, because the adhesional force is proportional to the size of objects meanwhile gravitational force is proportional to the third power of it. Consequently the adhesion phenomenon is no more negligible for the smaller objects usually less than 1 mm, e.g., micro-objects. Author will introduce our analyses about the manipulation mechanisms and related basic approaches to the adhesion phenomena including an adhesion force measurement in Auger electron spectroscope, an elastic continuum approximation approach using contact mechanics, a quantum mechanics approach for surface energy, a molecular mechanics approach for surface and interfacial energies. Also it will be expressed that our data base project for the surface and interfacial energies is based on these basic approaches for the purpose of optimization and/or breakthrough of the micro-assembly technology.
The Void Growth Simulations in the Hyper-Elastic Material with Multiple Seeds
Authors: Tsuji Tomoaki
Published: March 2009

The behaviors of a material are nonlinear in the large deformed region. The hyper elastic models can describe such non linear materials. If the hyper elastic material is applied to the hydrostatic tensile load, the void begins to grow when the load exceed the critical value. It is important to study the coalescence of the void growth in order to consider the destruction of the material. In this paper, the void growth simulations in the hyper-elastic material with multiple seeds are studied. The unit rectangular cell with small voids is subjected to the hydrostatic tensile load. This problem can be analyzed by FEM. However, the simulation with the larger number of the voids is not possible. Thus, the CA (Cellular Automaton) is used to describe the behaviors of the void coalescence and the possibility of CA is discussed.
Analysis of Laser Fusion Zone of Lotus-Type Porous Metals by 3-Dimensional FEM
Authors: Tsumura Takuya , Murakami Taichi , Hyun Soong Keun , Nakajima Hideo , Nakata Kazuhiro
Published: March 2009

Effects of pore directions on the profile of fusion zone for lotus-type porous magnesium by laser welding has been investigated by comparing the experimental observations and the results of numerical simulation. The three-dimensional finite element calculations were performed, which takes into account equivalent thermal properties and anisotropy of thermal conductivity. There is the pore anisotropy in the profile of fusion zone by laser beam irradiation and the good weldability was obtained when the growth direction of the original pore equaled to the direction of the laser beam irradiation. A good agreement was obtained between the calculated profile of the weld fusion zone and the experimental results.
Molecular Orbital Study on Adsorption Process of Silica Cluster on Polyimide Surface
Authors: Fujinami Akinori , Ogata Shigenobu , Shibutani Yoji , Yamamoto Kenichi
Published: March 2009

Process of a silica cluster on a polyimide surface was simulated by atomistic calculations combining the semi-empirical molecular orbital method and algorithms that can find the optimal path of a chemical bonding process. Specifically, we estimated the activation and sorption energies in the process. From the simulations, we found that chemical bonding occurs between a silica cluster and the polyimide substrate surface. In the adsorption processes, those reactions between the silica cluster and the polyimide surface which involve Si-O bonding between the cluster and the polyimide are the most probable.