bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Optical Characterization of M-α-Sialon (M=Ca, Ba, Sr) Doped by Europium
Authors: Michalik Daniel , Pawlik Tomasz , Sopicka-Lizer Malgorzata , Lisiecki Radosław
Published: October 2014

Oxynitrides compounds are interesting for white LED industry because more covalent matrix's bonds in comparison to oxides enable to obtain higher color temperature of wLED. The Sialon's luminescence material doped by rare earth ions with high mechanical and chemical resistance and a broad emission band may become an alternative for garnet phosphors. The goal of the study was to investigate influence of divalent stabilizing cations on luminescence properties of M-α-Sialon doped with Eu2+ in order to estimate its potential for YAG:Ce replacement in WLEDs. The compound of general formula EuxM1-xSi9,6Al2,4O0,8N15,2, where M=Ca, Ba, Sr, was prepared by the solid state reaction method from the mixture of the relevant oxides, nitrides and carbonates. Synthesis was carried out at the temperature of 1650°C for 4 h in a reduction atmosphere (N2+CO). The structure and morphology of obtained powders were analyzed by XRD and SEM/EDS methods, respectively. Optical properties were investigated by excitation, emission and reflection spectra and compared to photoluminescence properties of standard YAG:Ce. The obtained specimens show the significant effect of synthesis parameters on the phase composition and intensity of emission of M-α-Sialon:Eu2+ powder.
Influence of m and n Parameters of Ca-α-Sialon: Eu Solid Solution on Phosphor’s Optical Properties
Authors: Pawlik Tomasz , Michalik Daniel , Sopicka-Lizer Malgorzata , Serkowski Stanisław
Published: October 2014

Ca-α-sialon doped by Eu2+ is a promising material for white LED phosphors due to the strong UV absorption and a yellow broad band emission of activator. The general formula of α sialon enables changing matrix composition by altering m (Al-N) and n (Al-O) parameters of cross-substitution. Changes of the neighboring Eu ligands in the host crystal lattice would trigger important modification of the photoluminescence properties because of different crystal field splitting and the energy of the d orbital. The aim of this study was to correlate the matrix solid solution parameters with photoluminescence spectra features. The specimens of Ca-α-sialon:Eu2+ with m, n parameters in the range of 0.5-2.5 and 0.25-1.25 respectively, were prepared by the solid state reaction method in the reducing atmosphere of a graphite furnace. The phase composition of the obtained specimens was characterized by XRD, microstructure and morphology by the SEM/EDS techniques. The photoluminescence spectra (excitation, emission) were also recorded. Results show that m/n parameters have a significant influence on the final optical properties.
Femtosecond Laser Processing of Glass Materials for Assembly-Free Fabrication of Photonic Microsensors
Authors: Yuan Lei , Lan Xin Wei , Huang Jie , Xiao Hai
Published: October 2014

Research and development in photonic micro/nanodevices and structures have experienced a significant growth in recent years, fueled by their broad applications as sensors for in situ measurement of a wide variety of physical, chemical and biological quantities. Recent advancement in ultrafast and ultra-intense pulsed laser technology has opened a new window of opportunity for one-step fabrication of micro-and even nanoscale 3D structures in various solid materials. When used for fabrication, fs lasers have many unique advantages such as negligible cracks, minimal heat-affected-zone, low recast, and high precision. These advantages enable the unique opportunity to fabricate integrated sensors with unprecedented performance, enhanced functionalities and improved robustness. This paper summarizes our recent research progresses in the understanding, design, fabrication, characterization of various photonic sensors for energy, defense, environmental, biomedical and industry applications. Femtosecond laser processing/ablation of various glass materials (fused silica, doped silica, sapphire, etc.) is discussed towards the goal of one-step fabrication of novel photonic sensors and new enabling photonic devices. A number of new photonic devices and sensors are also presented.
Electromechanical Properties and Microstructure of Undoped K0.5Na0.5NbO3 Ceramics and KNbO3-NaNbO3 Crystals
Authors: Bah Micka , Giovannelli Fabien , Schoenstein Frédéric , Feuillard Guy , Le Clezio Emmanuel , Monot-Laffez Isabelle
Published: October 2014

K0.5Na0.5NbO3 (KNN) was manufactured by spark plasma sintering (SPS), which is a fast sintering method allowing to control the grain growth. Different samples of KNN are sintered with SPS at 920°C under 50 MPa for 5 minutes. High densities over than 97% are achieved. In order to make domain engineering, KNN crystals are grown by floating zone method. Stable molten zone is reached when oxygen or nitrogen gas flux is used, leading up to 50 mm length of crystals. High electromechanical coupling factor kt about 46 %, kp around 45 % and ε33S/ε0 of 253 are achieved for KNN ceramics poled at optimum electric field about 3 kV / mm. KNN crystal boule exhibits kt about 40 % against 34 % for KNN ceramic, both poled at 1 kV / mm. These results are promising to replace PZT for transducers applications.
How Can Be Realized High Piezoelectricity from Measuring Acoustic Wave Velocities ?
Authors: Ogawa Toshio
Published: October 2014

Material research and development on piezoelectric ceramics, especially lead-free ceramics, was proposed from a viewpoint of relationships between piezoelectricity and elastic constants such as Young’s modulus and Poisson’s ratio. We developed a method to be convenient to measure acoustic wave velocities by an ultrasonic thickness gauge with high-frequency. From the change in longitudinal and transvers wave velocities before and after DC poling, it was found that the ceramic bulk density was important to improve the piezoelectricity in lead-free ceramics. As a result, the candidates of lead-free ceramic compositions with higher piezoelectricity were proposed. Furthermore, the ratio of transvers wave velocity to longitudinal wave velocity was clarified to estimate compositions with higher piezoelectricity. The measurement of sound velocities was an effective method for researching and developing piezoelectric materials, and it was possible to design the material compositions of lead-free piezoelectric ceramics as well as lead-containing ceramics by the novel measuring method.
Effect of Isovalent B-Site Doping on Structural and Electrical Properties of Bismuth-Sodium-Titanate
Authors: Reichmann Klaus , Naderer Michael , Albering Jörg , Mautner Franz Andreas
Published: October 2014

Samples exhibiting substitution of Titanium in Bismuth-Sodium-Titanate (BNT) by isovalent Zirconium, Tin and Germanium (Bi0.5Na0.5Ti(1-x)DxO3 with D = Zr, Ge and Sn and x = 0.0025; 0.0050; 0.01; 0.02; 0.04; 0.08) were investigated with respect to microstructure, relative permittivity, loss factor and polarization. The substituents differ in mass, ionic radius and d-electron configuration. The shift of transitions observed in plots of permittivity and loss factor vs. temperature indicate the influence of the ionic radius. The occurrence of a pinched hysteresis loop at ambient temperature in the Sn-doped samples and the absence of any pinching in the hysteresis loops of Zr-and Ge-doped samples give rise to the assumption that this feature of polarization is connected to the ionic radius combined with the d10 electron configuration of Sn4+.
Effectiveness of Magnetic Sheets in Suppressing Magnetic Leakage in Automobile Wireless Energy Transfer Systems
Authors: Takeo Takashi , Kawaguchi Masato , Ishihara Taichi , Matsuzaki Toru
Published: October 2014

Recently, wireless energy transfer techniques are being developed for hybrid (HEV) or electric (EV) vehicles. However, without taking any measures, magnetic field strength around energy transfer systems that employ solenoid type antennas is known to exceed regulated values in most countries. In this study, the application of magnetic sheets, which are widely used as EMC components, is proposed to suppress the magnetic field leakage from an automobile energy transfer system and the ability of magnetic leakage suppression with the magnetic sheet has been evaluated by means of electromagnetic simulation. Through these investigations, desirable system arrangements are discussed. As a result, if combined with a metal plate, non-conductive magnetic materials having large permeability has been found to be preferable.
Modelling of the Oxygen Transport through MIEC Membrane in Transient Stage
Authors: Gazeau Camille , Blond Eric , Reichmann Mickaël , Geffroy Pierre Marie , Chartier Thierry , Richet Nicolas
Published: October 2014

The transient stage is critical due to the stress induced by the chemical and thermal strain. In order to predict this strain, the oxygen activity field through the membrane needs to be known. Usually, the membrane is divided into three zones: the bulk where diffusion takes place and the two surfaces where exchanges between atmosphere and membrane take place. Oxygen bulk diffusion is well described by the Wagner theory. A consensus has not yet emerged regarding the surface exchange models proposed in the literature. Moreover, these models describe the permanent state, and cannot be extended to the transient stage. A new macroscopic surface exchange model which allows computing transient stage is proposed. This model assumed that the oxygen flux is governed by the association/dissociation of adsorbed oxygen and by the high energetic cost of oxygen reduction/oxidation. Then, the balance of transient specie only present on the surface is introduced to account for these two phenomena. The oxygen activity fields predicted by the proposed model are in agreement with the measures of chemical potential drop between the membrane and the atmosphere in permanent state. Transient stage measured during isothermal expansion test is partially reproduced.
Self-Propagation Low Temperature Flameless Combustion Synthesis of Ni and Al Nanoparticles: Time-Resolved XRD Study
Authors: Mikhailov Yu.M. , Aleshin V.V. , Kolesnikova A.M. , Kovalev D.Yu. , Ponomarev V.I.
Published: October 2014

The combustion of cellulose nitrate (NC) in ballasted mixtures containing an organic binder and nickel hydroxycarbonate (NiOHCO3) or silver carbonate (Ag2CO3) as precursors has been found to produce Ni or Ag nanoparticles. Formation of Ni and Ag nanoparticles in the wave of flameless combustion of NC was monitored by the time-resolved X-Ray diffraction (TRXRD) method. During the formation of the Ag nanoparticles, the diffraction patterns exhibited only signals from decreasing amounts of the precursor and newly simultaneously formed 20-30 nm silver particles. It has been detected that in the systems with NiOHCO3 the formation of the Ni 5-10 nm crystals proceeded via some 2-3 seconds diffraction-silent intermediate state of the whole system.
Amorphous Alumina Coatings on Glass Bottles Using Direct Liquid Injection MOCVD for Packaging Applications
Authors: Etchepare P.L. , Vergnes H. , Samélor D. , Sadowski D. , Brasme C. , Caussat B. , Vahlas C.
Published: October 2014

In the field of packaging, coatings are commonly applied on containers to avoid interactions between them and their content. For glass bottles, application of a thin film prevents interactions with the phase in contact and consequently the alteration of surface properties of the latter. In this article, we propose an innovative way to apply amorphous alumina coatings on glass bottles by metalorganic chemical vapor deposition from aluminum tri-isopropoxide. A numerical model, using the Computational Fluid Dynamics code FLUENT, has been developed to calculate local profiles of gas flow, temperature, concentration and deposition rates into the reactor. The sub-micrometric alumina films have been deposited at reduced pressure between 480°C and 670°C. Uniform thickness profiles have been determined on cross sections over the length of the bottle and have been successfully simulated. Strongly improved hydrolytic resistance with regard to the uncoated bottles reveals the excellent performance of the films.
Comparison of the Ablation Mechanism of C/C-SiC Composite under Atmospheric and Low Pressure
Authors: Silva Roberson J. , Maciel Homero S. , Essiptchouk Alexei M. , Petraconi Gilberto
Published: October 2014

Comparisons of heating tests at atmospheric pressure and low pressure by using a thermal plasma torch were performed. A constant heat flux on the sample surface was applied in the study of the oxidation mechanism of C/C-SiC composite, used in thermal protection systems. The SEM and EDS analysis show an intensive glassification at the surface, which are strongly depend on the oxygen partial pressure and the sample surface temperature. For vacuum conditions, at maximum surface temperature of 1450 °C and the oxygen partial pressure of about 66 Pa, a uniform passivation layer of SiO2 is formed. At atmospheric pressure, under an oxygen partial pressure of 2.1×104 Pa, the maximum surface temperature is 400 °C higher than obtained in vacuum, reaching levels of 1850°C. Under these conditions, the protective oxide layer is partially volatilized with time, increasing the specific mass loss rate by a sublimation of the composite, directly exposed to the plasma jet. This effect is alike to what occurs in the process of transition from passive to active oxidation of SiC.
Oxide Films Formed on FeCrAl Steel Foil Coated with Pt and Al Films
Authors: Reszka Kazimierz , Zurek Zbigniew , Szczypinski M. , Jaron Artur
Published: October 2014

The investigations were aimed to characterize the oxide films (Al2O3) in terms of the crystal structure development and their impact on increase in mechanical distribution of Pt in volume of the film, as a system predisposed to carry out catalytic processes. The morphology and phase composition of oxide films formed on the surface of FeCrAl steel foil coated with Al and Pt films and Al/Pt composition films after oxidation at high temperature were investigated. All samples with films were oxidized in an atmosphere containing 67% O2/Ar at 850 ° C in a period of 24 h. As a result of the oxidation processes there were formed θ-Al2O3 oxides of whisker structure of a considerable size, while whiskers of θ-Al2O3 oxides formed on the samples coated with Pt films were smaller but with higher density. There was also α-Al2O3 phase in the form of solids in the immediate vicinity of the steel substrate.
Study on the Synthesis of Batches of the System Y-Ba-Cu-O Using Sol-Gel Method
Authors: Pashev Plamen , Raykova Rositsa , Hristov Yancho , Bogdanov Bogdan
Published: October 2014

The study presented deal with preparation of batches of the system Y-Ba-Cu-O using sol-gel method and citric acid as precursor. Batches with particle size of 100 nm containing each of the phases Y123 and Y211 were prepared. The stoichiometric amounts of Y, Ba and Cu oxides were dissolved in 65% HNO3 until clear blue solution was observed under heating to 80 ̊С. The nitrate solutions obtained were neutralized to pH = 6 with 25% solution of NH3 (p.a.), then С6Н8О7 was added as the gels obtained were thermally treated. The transformation processes taking place under change of temperature were studied by IR, XRD, DTA and SEM.
Consolidated Nanocomposite Materials with the Defined Properties
Authors: Semchenko G.D. , Gevorkyan E.S.
Published: October 2014

Application of modern ways of ceramic materials’ consolidation and association of synthesis methods of organic and inorganic chemistry, sol-gel method and mechanochemistry, allowing to control processes of synthesis of the defined phases at molecular level, gives the chance to create highly effective composite materials. It is known that properties of composites on the basis of refractory compounds become dimensionally dependent at reduction of the particles’ size to several interatomic distances in one, two or three dimensions . Obtaining of durable nanostructural ceramics on the basis of ZrO2 with substantial increase of mechanical properties can be realized by creation of material with fine homogeneous structure, on the basis of powders of nonoxygen compounds when strength properties and crack resistance increase at creation of –intra and –inter nanostructures. In work results of creation of the consolidated nanomaterials and composite ceramics with usage of the peculiarities set forth above for synthesis of precursors of powders and the defined phases that self-reinforce ceramic matrixes have been presented.
Compositional Designs for High Performance Antifingerprint Coated Concealed Cistern Control Panels
Authors: Tunali Ayşe , Tamsu Selli Neslihan
Published: October 2014

Concealed cistern control panels are the systems allowing the water inside the built-in reservoir to flow into the toilet bowl when it is necessary. In order to provide the water inside the reservoir to flush into the toilet bowl after the toilet is used, it is necessary to apply force on the control panels. Therefore, the panel surface is pressed with fingers. Especially in public places such as shopping malls, schools, hospitals; the sweat, oil and cosmetics passing through the fingers in a very short time leave spots on the panel surfaces. In order to clean the spots, it is needed to use cleaning materials with chemical content. This situation leads extra cost and as well as time consuming process. For this reason antifingerprint coated panels are required. In this study, antifingerprint coating systems were developed and to improve the coating performance such as mechanical and chemical resistance, different polyurethane composition ratios were studied and effectiveness of the coating systems were investigated by using characterization methods (SEM, EDX, FTIR).
Modeling the Properties of Cellular Ceramics: From Foams to Lattices and Back to Foams
Authors: Ortona Alberto , Rezaei Ehsan
Published: October 2014

Cellular ceramics are attracting material solutions for high temperature applications because of their outstanding properties. SiC cellular ceramics in particular withstand harsh environments at high temperatures for long operating times and are particularly resistant to thermal shock. Ceramic foams though, being random fragile structures, comprise properties which are rather scattered and difficult to engineer. This presentation shows how finite element analysis is used to study the effect of morphological features on ceramic foams in respect of their mechanical properties. Mean morphological parameters, obtained by X-ray computed tomography (XCT) on a commercially available SiSiC foam produced by the replica method, were used to generate a set of lattices in which one parameter was varied at a time. Starting from this approach, further work was then dedicated to optimize their properties. Polymeric lattices and foams, in which some characteristics were digitally modified learning from the optimization work were, produced by 3D printing and ceramized via the replica method. Both foams and lattices were then mechanically tested. Results show that some features such as strut shape and cell stretching affect the mechanical behavior of ceramic foams.
Porous Silicas for Enhanced Drug Release
Authors: Crean Abina M. , Ahern Robert J. , Dontireddy Rakesh , Faisil Walid , Hanrahan John P. , Griffin Brendan T. , Ryan Katie B.
Published: October 2014

Low drug water-solubility is a major challenge to overcome in the development of tablet or capsule dosage forms for a large number of promising drug candidates. Strategies to improve drug solubility and dissolution involve chemical, physical and formulation approaches. An emerging formulation approach to increase drug dissolution and solubility involves the creation of solid dispersions of drug molecules on to a high surface area inorganic carrier, such as porous silica. The combined benefits of a hydrophilic inorganic substrate, increased drug surface area and a high-energy drug form facilitate rapid drug dissolution into aqueous based media and can create supersaturated drug solutions. The work presented provides a brief overview of the silica grades investigated, processes employed to load drugs onto the silica substrates, provide some examples of the ability of silica to enhance drug dissolution and highlight some of the challenges in the development of these novel drug delivery systems.
Lightweight Bi-Layered Ceramic Tiles for Novel Applications
Authors: Novais Rui M. , Seabra Maria P. , Labrincha João A.
Published: October 2014

The excellent properties of porcelain stoneware tiles make them ideal materials for floor covering. However, their high density limits their use in novel applications, where low weight and low thermal conductivity are required. In this work, the production of lightweight bi-layered ceramics, with suitable mechanical resistance and low thermal conductivity in comparison with commercial tiles, is reported. The weight and thermal conductivity reduction was achieved by means of porogen incorporation. The possibility of using polypropylene (PP) as a pore forming agent was evaluated. PP completely burns out at relatively low temperatures with no emission of hazardous gases, and does not induce defects in the ceramic pieces. Results demonstrate that porosity (pore volume, number and area) can be easily controlled by adjusting the porogen amount (5-15 wt.%). The reduction in weight (7.5%) and thermal conductivity (up to five times) in comparison to commercial stoneware tiles might extend their use to novel applications.
Effect of Alternative Materials Added to the Plaster Composition
Authors: Seyhan Nurcan , Tayçu Aslı , Gula Mehmet , Eker Arzu , Kayaci Kagan , Kara Alpagut
Published: October 2014

In this study, the effect of alternative additives on the properties spred diameter, setting time, bending strength and water absorption of sanitaryware plaster moulds was investigated. The plaster was partially replaced by the alternative additives such as perlite, diatomite and glass beads. Microstructural features of the resultant compositions were determined by scanning electron microscope (SEM). Finally, represantative moulds were produced and their performance was investigated under industrial conditions. It was observed that perlite and diatomite addition deteriorated the strength of plaster moulds and there was no noticeable effect of these additives on casting performance of the plaster moulds. Morever, the presence of glass beads in plaster decreased weight of the moulds without deterioration of moulds service life.
New Ceramic Pigments for the Coloration of Ceramic Glazes
Authors: Llusar Mario , Gargori Carina , Cerro Sara , Badenes Jose Antonio , Monrós Guillermo
Published: October 2014

In this communication we provide some examples of hot research topics in the field of ceramic pigments. The more classical approach of finding new host lattices or chromophores is first illustrated with recent examples of new formulations for yellow-orange, reddish-brown and blue ceramic pigments based on pseudobrookites and related titanates. Then we highlight the advantages of using non-conventional preparation routes, which can provide different pigmenting alternatives for the emerging ink-jet printing technology, such as the development of nanoor sub-micron pigments and “ceramic inks”, or the use of appropriate precursors for in situ-generating pigments.
Study of the Variables that Lead to Hue Variations on Tiles Decoration Based on Silicon Cylinder Technique Laser Engraving Method
Authors: Ferraço Fabio , Boschi Anselmo Ortega
Published: October 2014

In the process of ceramic tiles production, the hue variation is one of the oldest and common problems whose appearance persists within the production and between two different productions of the same product; therefore it’s a problem to be solved still. Identify the origin the hue variation and minimize its occurrence it’s a constant challenge in the ceramic tile production, and the target is always to increase the quality end decrease the batches with different tones. Although the hue variation can have it’s origin within which one of the whole steps of the process, this work is focused on the decoration process using one of the most widespread technics of such step, the laser engraving silicon cylinders. This work accosts the influence of the speed of the ceramic line production and its effects on the hue variation. The studied characteristics were the shape and volume of the ink dot transferred by the cylinder to the tile surface, measured by optical microscopy and the result tone of the decoration, measured by spectrophotometry.
The Effect of Lithium Alumina Silicate Phases on Elastic Modulus of Porcelain Tiles
Authors: Aydin Tuna , Kara Alpagut
Published: October 2014

Spodumene, which is a lithium alumina silicate, has been used as a raw material in the production of thermal shock resistant whitewares and sanitarywares. The presence of spodumene results in enhancement of mullitization and imparts better physical and mechanical properties to ceramics. In this study, the influence of Lithium alumina silicate phases on the mechanical properties of standard porcelain stoneware body was investigated. Especially solid-solid reactions were observed between spodumene and quartz or spodumene and clay. These solid-solid reactions bring about a newly formed lithium alumina silicate (LAS) phases. Spodumene allows the development of a low viscosity liquid phase and results in a decrease in closed porosity, also with increase in bulk density, bending strength and elastic modulus.
Effect of the Reactivity of the Alkaline Solution and the Metakaolin on the Geopolymer Formation
Authors: Gharzouni Ameni , Joussein Emmanuel , Baklouti Samir , Rossignol Sylvie
Published: October 2014

The choice of precursors is a key parameter in the geopolymerization mechanism since it governs the kinetic of the reaction as well as the working properties of the final materials. This study focuses on the effect of the alkaline solution reactivity and metakaolin properties on the geopolymer formation. For this purpose, several geopolymer samples were synthesized from two alkaline solutions and three metakaolins. The structural evolution of formed geopolymers was investigated using FTIR spectroscopy and the following of the pH value during the formation. The measurement of mechanical strength was tested by compression. The results allow to evidence that for a less reactive alkaline solution, the reactivity of metakaolin governs the geopolymerization reaction. However, the alkaline solution is the steering reaction when it is highly reactive. Therefore, the extent of depolymerization of the alkaline solution and the reactivity of the metakaolin seem to control the rate of polycondensation and the mechanical properties of the geopolymer materials.
Ceramic Waste as New Precursors for Geopolymerization
Authors: Bignozzi Maria Chiara , Fusco Omar , Fregni Alberto , Guardigli Luca , Gulli Ricccardo
Published: October 2014

Geopolymers, and more in general alkali activated materials (AAM), are a new class of materials obtained by alumino-silicates precursors activated by means of alkaline solutions. Indeed, the term geopolymers is usually strictly referred to pure alumino-silicates such as metakaolin as starting material, whereas when the precursors also contain calcium oxide the resulting products are usually defined AAM. Geopolymerization technology can be more easily considered a sustainable process when industrial waste is used as precursors and the consolidation process occurs at room temperature. With these premises, alkali activation may be a very promising technology for the ceramic sector as well as construction industry. In this work, waste coming from bricks production has been used to obtain, at room temperature, geopolymers with different porosity tuning the sodium silicate content in the feed. Microstructure analysis carried out by means of mercury intrusion porosimeter and scanning electron microscopy is reported and discussed.
Mechanisms of SiC Refractory High Temperature Corrosion by Molten Salts (Na,K,Ca,Cl,S) in Waste to Energy Facilities
Authors: Poirier Jacques , Prigent Pascal , Bouchetou Marie Laure , de Bilbao Emmanuel , Blond Eric , Brossard Jean Michel
Published: October 2014

Damage of SiC oxide bonded refractories in waste-to-energy facilities (WtE) has been characterized. Different phenomena were observed: wear by slag phases, volume expansion of tiles and fracture in different locations. These results are in agreement with laboratory experiments. The role of gas composition and tiles temperature profile on deposit composition, on condensation of gaseous alkali chloride and on formation of liquid phase inside the porosity of the refractories has been emphasized. Gaseous alkali species are involved, not only in the formation of liquid phases, but also as a precursor of cristoballite formation around the SiC grains as well as in the rich alumina-silica matrix. On the hot face of the refractories, oxo-reduction reactions produce the formation of wollastonite. Post-mortem analysis after several thousand hours of operation point to three main corrosion mechanisms:
Numerical Analysis on the Refractory Wear of the Blast Furnace Main Trough
Authors: Chang Ca Min , Lin Yon Sen , Pan Chien Nan , Cheng Wen Tung
Published: October 2014

This study aims to numerically analyze the refractory wear of the blast furnace main trough. The three dimensional transient Navier-Stocks equation associated with the volume of fluid (VOF) was developed to describe the flow fields of air, molten iron and slag in the main trough of the blast furnace during tapping process; and then solved by the finite volume method (FVM) subject to the pressure implicit with split operator (PSIO). Based on the Newton’s law of viscosity, the computed shear stress profile in the impingement region consists with the erosion rate of main trough from the no. 4 blast furnace at China Steel Corporation (CSC BF4). The influence of the tapping angle and the ratio of iron to slag in tapping stream on the wall shear stress of main trough was also examined for the suggestion to minimize the refractory wear of blast furnace main trough in this work.
The Influence of Short Fibres and Foaming Agents on the Physical and Thermal Behaviour of Geopolymer Composites
Authors: Masi Giulia , Rickard William D.A. , Bignozzi Maria Chiara , van Riessen A.
Published: October 2014

Foaming methods to reduce the density of geopolymers were investigated as low density geopolymers are increasingly being reported in the literature to be effective in improving the insulating properties. However, there is no consistency in foaming methods and as such this study was performed to compare different foaming agents in order to better understand their effect on the properties of geopolymers. In particular, a surfactant and hydrogen peroxide were used individually and in combination to ensure a homogeneous pore distribution in the slurry. Physical and microstructural properties of the hardened low density geopolymers are presented and discussed. The behaviour under fire conditions of fibre reinforced and foamed geopolymer samples will also be presented in order to appreciate the suitability of geopolymer composite in high temperature applications.
Application of Fly Ash-Based Geopolymer for Structural Member and Repair Materials
Authors: Yodsudjai Wanchai
Published: October 2014

The applications of using fly ash-based geopolymer as a structural member and a repair materials in reinforced concrete structure was conducted. The optimum mix proportion of fly ash-based geopolymer concrete using for structural beam and fly ash-based geopolymer mortar using for repair material were developed. The flexural behavior of fly ash-based geopolymer reinforced concrete and the durability aspect namely the corrosion of steel reinforcement were investigated using the electrical acceleration. For the repair purpose, the fundamental properties; that is, compressive strength, flexural strength, bonding strength between fly ash-based geopolymer mortar and mortar substrate, setting time and chloride penetration were investigated. Also, the durability of conventional reinforced concrete beam repaired by the fly ash-based geopolymer mortar comparing with the comercial repair mortar was investigated. The behavior of the fly ash-based geopolymer reinforced concrete beam was similar to that of the conventional reinforced concrete beam; however, the corrosion of the steel reinforcement of the fly ash-based geopolymer reinforced concrete beam was higher than that of the conventional reinforced concrete beam. The fundamental properties of the fly ash-based geopolymer mortar were not different from that of the commercial repair materials; however, the durability of the reinforced concrete beam repaired by the fly ash-based geopolymer mortars performed a little lower than that of repaired with the commercial repair motar and also the control reinforced concrete with no repair. As a result, even there will be still a need of improvement there was a good tendency for using the fly ash-based geopolymer as the structural member and the repair materials.
Durability of Fly Ash Geopolymer Mortars in Corrosive Environments, Compared to that of Cement Mortars
Authors: Asprogerakas A. , Koutelia Aristea , Kakali Glykeria , Tsivilis Sotirios
Published: October 2014

In the present paper the durability of fly ash geopolymer mortars compared to that of cement mortars is investigated. Geopolymers can improve the ecological image of building materials, especially when their production is based on industrial by-products such as fly ash. Three series of fly ash based geopolymer mortars were prepared using calcareous sand to fly ash ratio (S/FA) varying from 0.5 to 2. In addition, cement mortar specimens were prepared using cement CEM I 42.5 N and CEM II 32.5 N. Durability of geopolymer and cement mortars was evaluated by means of compressive strength development, acid resistance, chloride diffusion and sulfate resistance. It was found that fly ash can be effectively used to produce geopolymer mortars with calcareous sand. Geopolymers exhibit competitive compressive strength compared to that of cement mortars. Geopolymer mortars develop their maximum compressive strength a few days after their casting. Geopolymer and cement mortars exhibit satisfactory resistance to sulphate attack. Cement mortars, generally, show better behaviour (compared to geopolymers) in chloride diffusion. Finally, geopolymers indicate improved performance against acid attack, compared to that of cement mortars.
Antibacterial and Self-Cleaning Coatings for Silicate Ceramics: A Review
Authors: Sciancalepore Corrado , Manfredini Tiziano , Bondioli Federica
Published: October 2014

The development of advanced materials is increasingly leading to integration of functions into materials and components. This drive in technological innovation is strongly felt in many traditional fields, like textiles or ceramics. Over the last twenty years, the so-called "traditional" ceramics industry for tile production has undergone a profound technological reorganization, both in production technologies and automation of the different production phases, but new products and possible new applications are still needed, thereby opening up new markets. In this paper a critical review of the industrial and scientific effort to obtain antibacterial and self-cleaning coating for ceramic tiles is reported. The main patents and scientific papers in the field are reported as well as some final results obtained by the authors on the evaluation of the durability of photocatalytic coating deposited on industrial ceramic tiles.
Activated Carbon Fibre Monoliths for Hydrogen Storage
Authors: Kunowsky Mirko , Marco-Lozar Juan Pablo , Linares-Solano Ángel
Published: October 2014

Porous adsorbents are currently investigated for hydrogen storage application. From a practical point of view, in addition to high porosity developments, high material densities are required, in order to confine as much material as possible in a tank device. In this study, we use different measured sample densities (tap, packing, compacted and monolith) for analyzing the hydrogen adsorption behavior of activated carbon fibres (ACFs) and activated carbon nanofibres (ACNFs) which were prepared by KOH and CO2 activations, respectively. Hydrogen adsorption isotherms are measured for all of the adsorbents at room temperature and under high pressures (up to 20 MPa). The obtained results confirm that (i) gravimetric H2 adsorption is directly related to the porosity of the adsorbent, (ii) volumetric H2 adsorption depends on the adsorbent porosity and importantly also on the material density, (iii) the density of the adsorbent can be improved by packing the original adsorbents under mechanical pressure or synthesizing monoliths from them, (iv) both ways (packing under pressure or preparing monoliths) considerably improve the storage capacity of the starting adsorbents, and (v) the preparation of monoliths, in addition to avoid engineering constrains of packing under mechanical pressure, has the advantage of providing high mechanical resistance and easy handling of the adsorbent.
Atomistic Models of Long-Term Hydrogen Diffusion in Metals
Authors: Ariza M.P. , Wang K.G. , Ortiz M.
Published: October 2014

The effective and efficient storage of hydrogen is one of the key challenges in developing a hydrogen economy. Recently, intensive research has been focused on developing and optimizing metal-based nanomaterials for high-speed, high-capacity, reversible hydrogen storage applications. Notably, the absorption and desorption of hydrogen in nanomaterials is characterized by an atomic, deformation-diffusion coupled process with a time scale of the order of seconds to hours--far beyond the time windows of existing simulation technologies such as Molecular Dynamics (MD) and Monte Carlo (MC) methods. In this work, we present a novel deformation-diffusion coupled computational framework, which allows the long-term simulation of such slow processes and at the same time maintains a strictly atomistic description of the material. Specifically, we first propose a theory of non-equilibrium statistical thermodynamics for multi-species particulate solids based on Jayne's maximum entropy principle and the meanfield approximation approach. This non-equilibrium statistical thermodynamics model is then coupled with novel discrete kinetics laws, which governs the diffusion of mass--and possibly also conduction of heat--at atomic scale. Finally, this thermo-chemo-mechanical coupled system is solved numerically using a staggered procedure. The salient features of this computational framework are demonstrated in the simulation of a specific hydrogen diffusion problem using palladium nanofilms, which comes with a simulation time of one second. More generally, the proposed computational framework can be considered as an ideal tool for the study of many deformation-diffusion coupled phenomena in hydrogen-storage-related applications including, but not limited to, hydrogen embrittlement, grain boundary diffusion, and various cyclic behaviors.
Study of New Active Materials for Rechargeable Sodium-Ion Batteries
Authors: Nakanishi Shinji , Nose Masafumi , Nakayama Hideki , Iba Hideki
Published: October 2014

Na4Co3(PO4)2P2O7is the unique crystal structure with multiple sodium-ion pathways in the structure. The electrochemical properties of Na4Co3(PO4)2P2O7as a positive electrode for sodium-ion batteries were investigated. Na4Co3(PO4)2P2O7had the multi redox couples in the highest potential region between 4.1 V and 4.7 V among ever reported sodium active materials and could deliver the reversible capacity of ca. 95 mAhg-1, corresponding to ca. 2.2 Na+. Na4Co3(PO4)2P2O7also exhibited the high rate capabilities and had a small polarization in the charge - discharge profile even at the high current densities, resulting in high energy efficiency of the battery. These performances indicate Na4Co3(PO4)2P2O7can be one of the good candidates for a positive electrode material of sodium-ion batteries.
Hydrothermal Synthesis of Corn Cob-Like LiFePO4/C as High Performance Cathode Material for Lithium Ion Batteries
Authors: Lin Mei , Wu Xiao , Chen Bo Lei , Yuan Ji Kang
Published: October 2014

Corn cob-like LiFePO4 (LFP) cathode material was simply synthesized through hydrothermal method using block copolymer (PEG-PPG-PEG) as the surfactant. The influence of pH value and reaction time on the morphology of LFP has been briefly investigated. The presence of copolymer plays an important role in the construction of the hierarchically microstructures. By adjusting the pH value and reaction time, platelet-like, hexagram-like, porous spindle-like and corn cob-like LFP microstructures were obtained. To gain the cell performance of the synthesized LFP, galvanostatic charging-discharging measurement on the as-prepared samples were performed. The porous spindle-like LFP/C shows unexpected electrochemical performance since the spindle-like LFP have large structure which prevents access for the liquid electrolyte. Corn cob-like LFP/C exhibits the best electrochemical performance, discharge specific capacities of 120 mAh g-1 after 100 cycles with capacity retention ratios of 80% at 0.1 C. This work also provides the possibility for further investigation into the shape-dependent electrochemical performance of other materials by optimizing the experimental parameters during hydrothermal synthesis.
Development of Plasmonic Photocatalysts for Environmental Application
Authors: Kowalska Ewa , Wei Zhi Shun , Karabiyik Baris , Janczarek Marcin , Endo Maya , Wang Kun Lei , Rokicka Paulina , Markowska-Szczupak Agata , Ohtani Bunsho
Published: October 2014

Regarding catalytic and plasmonic properties of gold nanoparticles (NPs), the novel area of research on photocatalytic gold properties has been recently started. In contrast with catalytically active gold NPs, where nanosized gold is recommended, our results showed that polydispersity of deposited gold NPs on semiconducting support was beneficial for photocatalytic activity under visible light irradiation. It is thought that wide size/shape distribution of gold NPs, and thus the ability of absorption of light in a wide wavelengths range is responsible for the high level of photoactivity. Though desirable absorption properties of plasmonic photocatalysts can be easily obtained by preparation of nanoparticles of different sizes and shapes, their photocatalytic activities under visible light irradiation are still low and should be enanced. The improvement of photocatalytic activities under visible light irradiation was achieved by enlargement of interfacial contact between titania and NPs of noble metals, extension of photoabsorption ranges (by preparation of NPs of various sizes and shapes or composed of two kinds of noble metals), and by deposition of noble metals NPs on faceted titania, i.e., octahedral (OAPs) and decahedral (DAPs). Plasmonic photocatalysts composed of titania and NPs of silver, gold or copper showed also high antiseptic properties under visible light irradiation, due to possible synergism of antiseptic properties of noble metals and photodisinfection properties of photocatalyst, since reactive oxygen species or photogenerated holes are formed on the surface of irradiated semiconductor.
Highly Efficient Plasmonic Palladium-Titanium Dioxide Co-Catalyst in the Photodegradation of Rhodamine B Dye
Authors: Lacerda Armando Marsden , Larrosa Igor , Dunn Steve
Published: October 2014

A co-catalyst was synthesized by photochemically depositing Pd nanoparticles onto TiO2 nanopowder support in a one-pot synthesis procedure. The Pd nanoparticles exhibited localised surface plasmon resonance observed using UV-VIS which increased the absorption cross-section of the co-catalyst system into the visible as well as UV regions of the spectrum. This was found to have a significant contribution to the photocatalytic activity of the catalyst in dye degradation experiments. The size, morphology and distribution of the Pd nanoparticles were determined by TEM, while the chemical state and amount of Pd deposited were analysed via XPS and ICP respectively.
CuZnSnSe Nanotubes and Nanowires by Template Electrosynthesis
Authors: Battaglia Mirko , Sunseri Carmelo , Piazza Salvatore , Inguanta Rosalinda
Published: October 2014

In this work we present some results of an extensive investigation aimed to find suitable conditions to grow CuZnSnSe (CZTSe) nanostructures through single-step electrodeposition into the channels of polycarbonate membranes. After the optimization of several electrodeposition parameters, we have found that pulsed current deposition, between 0 and -1 mA cm-2, is the best way to obtain CZTSe nanostructures mechanically attached to the support. An interesting result concerns the effect of supporting electrolyte in the deposition bath. In fact, changing its concentration it is possible to vary morphology of nanostructures from nanotubes to nanowires. In both case uniform arrays of ordered nanostructures were obtained on a Ni current collector that are very stable also after thermal treatment at 550°C.
Electrical and Electrochemical Properties of La2–xCaxNiO4+δ and La2–xCaxNiO4+δ–Ce0.8Sm0.2O1.9 Cathode Materials for Intermediate Temperature SOFCs
Authors: Pikalova Elena Yurievna , Kolchugin Alexander Anatolievich , Bogdanovich Nina Mihailovna , Bronin Dimitry Igorevich
Published: October 2014

The present work focuses on the electrical properties of La2–xCaxNiO4+δ (x=0–0.4) and the electrochemical performance of the cathodes based on these materials with a LаNi0.6Fe0.4O3-δ current collector in contact with a Ce0.8Sm0.2O1.9 electrolyte. The effect of the sintering temperature on the polarization resistance of La1.7Ca0.3NiO4+δ–Ce0.8Sm0.2O1.9 composites of different content has been studied by an impedance spectroscopy method. The composite electrode 50 wt.% La1.7Ca0.3NiO4+δ – 50 wt.% Ce0.8Sm0.2O1.9 sintered at the temperature below 1300°C has showed the lowest polarization resistance value equal to 0.27 Ωcm2 and in case of PrOx infiltration 0.033 Ωcm2 at 800°C in air.
Tunable Performance of P-Type Cu2O/SnO Bilayer Thin Film Transistors
Authors: Al-Jawhari H.A. , Caraveo-Frescas J.A. , Hedhili M.N.
Published: October 2014

Novel tunable p-type thin film transistors (TFTs) were developed by adopting Cu2O/SnO bilayer channel scheme. Using Cu2O film produced at a relative oxygen partial pressure Opp of 10% - as an upper layer - and 3% Opp SnO films - as lower layers - we built a matrix of bottom gate Cu2O/SnO bilayer TFTs with different thicknesses. We found that the thickness of the Cu2O layer plays a major role in the oxidization process exerted onto the SnO layer underneath. The thicker the Cu2O layer the more the underlying SnO layer is oxidized, and hence, the more the transistor mobility is enhanced at a certain temperature. Both the device performance and the required annealing temperature could then be tuned by controlling the thickness of each layer of the Cu2O/SnO bilayer TFT.
Electrocatalysts Based on Iron Phthalocyanine and Polyindole Supported on Carbon Nanotubes for Oxygen Reduction in DMFCs
Authors: Nguyen M.T. , Iannaci A. , Mecheri B. , Luisetto I. , d’Epifanio A. , Licoccia S.
Published: October 2014

Novel electrocatalysts from iron phthalocyanine (FePc) and polyindole (PID) supported on carbon nanotubes (CNTs) have been synthesized for oxygen reduction reaction (ORR) in Direct Methanol Fuel Cell (DMFC). Two synthetic strategies have been proposed: i) preparation of PID on CNTs (PID/CNTs) through indole polymerization followed by the mechanical mixing of PID/CNTs with FePc (FePc_PID/CNTs); and ii) dispersion of polymerized PID, FePc, and CNTs in methanol and subsequent drying (FePc/PID/CNTs). The morphology of prepared catalysts was examined by SEM, and the electrochemical activity towards ORR was evaluated by cyclic voltammetry. FePc/PID/CNTs catalysts were found to have higher activity than that of FePc_PID/CNTs, due to a better dispersion of PID and FePc on carbon support, as demonstrated by SEM. Furthermore, in comparison with platinum on carbon black the prepared PID-based catalysts exhibited a stable ORR potential in both H2SO4 and H2SO4 + CH3OH solution. These new iron-based catalysts are thus promising to substitute platinum/carbon black at the cathode side of DMFC.