bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallization of Gahnite in CMAS Glass Forming System - Mechanism and Process Kinetics
Authors: Herman Daniela , Okupski Tomasz , Walkowiak Wiesław
Published: October 2010

The crystallisation mechanism of glass-ceramic materials from a CMAS group Al0.37B0.34Fe0.01Mg0.02Zn0.29Ca0.05Si0.78O3 was tested under non-isothermal conditions by the DTA method. Glass-ceramic material of two-phase composition with precipitation of crystallites from islet silicates Zn2SiO4 and a crystalline phase from a spinel group, gahnite ZnAl2O4 was obtained in the system under investigation. Activation energy of a crystallization process Ea was determined and a crystal growth morphology parameter n was computed. It was revealed that in the test material from a CMAS group one could obtain the crystalline phase in the form of ghanite as a result of a controlled process of crystallization. The occurrence of a spinel phase caused the obtained glass-ceramic material had higher fracture toughness (KIC) than material from a CMAS group, containing pyroxene crystalline phases typical for this system.
Visible and Infra-Red Reflectance of Several Typical Japanese Glazes for Roof Tiles and Wall Tiles
Authors: Sugiyama Toyohiko , Kakiuchida Hiroshi , Ohashi Masayoshi
Published: October 2010

. Tile coating with a higher reflectance of sun light are effective in mitigating heat-island phenomenon. Covering the surface of the ground or the exterior of buildings with such high reflectance coatings has attracted attention because of its high cost effectiveness. Recently, companies producing Japanese roofing tiles or wall tiles have been trying to develop high reflectance glaze for their products. However, while we have enormous amounts of data on visible reflectance measured through the study of glaze coloration, there are comparatively less data pertaining to infrared reflectance on pottery glazes. Though optical properties of simple glass and ceramics have been extensively studied, pottery glazes are complex glass-crystalline micro-composites. The pottery glazes sometimes have heterogeneous structures caused by phase separation, crystallization in the base glass, oriented crystallization on the surface, and so on, which are considered to affect infrared reflection. In this paper, several kinds of typical Japanese glazes are characterized from the point of view of the visible and infra-red spectral reflectance, and the improvement of these characteristics is discussed.
Preparation and Stability of Alkali Activated Materials from Slag and Fly Ashes
Authors: Bilek Vlastimil
Published: October 2010

Alkali-activated concretes are relatively well-known composites. They show good mechanical properties, good resistance to the attack of a variety of chemical media and some other suitable properties. For their practical application various problems must be solved. In this paper some effects of the composition of the alkali activator and the composition of the binder on setting time, workability, efflorescence, leaching, strengths, shrinkage development, freezing and thawing resistance are studied with respect to a low price of the materials.
Use of Local Raw Materials for Construction Purposes
Authors: Rahier Hubert , Slatyi Faten , Aldabsheh Islam , Alshaaer Mazen , Khoury Hani , Esaifan Muayed , Wastiels Jan
Published: October 2010

A geopolymer produced from Jordanian kaolinite is described in this work. The aim is to produce low environmental impact materials from local raw materials. In this paper the emphasis is on the general characteristics of the material and on its durability. With the used kaolinite, specimens with compressive strength of 41 MPa under dry conditions and 23 MPa under immersed water conditions were obtained. The durability under environmental conditions was good.
Repairing of Damaged Stone in Monuments and Stone Buildings
Authors: Teixeira-Pinto Amândio
Published: October 2010

The main causes of rock degradation in stone buildings are discussed and the current methods of recovering damaged stones are summarized.
The Alkaline Activation seems to present a great potential to deal with particular cases of damaged stones resulting mainly from fracture incidents provoked by physical actions, where the global substitution of the stone itself is not considered.
A practical case of recovering granite on the windows frames of a beautiful chalet to be intended for the Municipal Archives at Vila Real is described, in what is considered to be the first experiment of this technique in recovering building stone.
Recycling of Industrial Wastewater by its Immobilization in Geopolymer Cement
Authors: Tavor Dorith , Meyohas Tal , Ronen Shlomi , Wolfson Adi
Published: October 2010

In this work, wastewater from Teva Pharmaceutical Industries Ltd., which comprises
several organic and inorganic compounds, was solidified in a geopolymer matrix. The addition of
wastewater to the polymerization mixture of fly ash based geopolymers yielded a high compressive
strength of 50-75 MPa that is similar to that of wastewater-free geopolymer. The leaching of organic
compounds from the matrix was examined and it was found to be negligible, about 0.2%wt, and
comparable to the amount that leached from a geopolymer matrix made without wastewater. The
results indicate that the immersion temperature and the time of immersion have negligible
influences on carbon leaching.
Geopolymer Binders in Composite Cements and Ceramic-Like Materials
Authors: Kaps Christian , Hohmann Marc
Published: October 2010

Two types of geopolymeric networks have been prepared and characterized: aluminosilicatic binders(1) generated of metaclays for composite cements and iron-phosphate binders(2) formed of iron oxyhydroxites for applications in strong acidic environments. The focus of the investigations was on the influence of the thermal(1) or the acidic(2) activation on the structure and properties of the materials. In both cases, the amount of present water plays an essential role.
Dissolution-Reorientation-Polycondensation Process of Metakaolin in Alkaline Solutions Related to Geopolymerization
Authors: Zhang Yun Sheng , Sun Wei , Li Zongjin
Published: October 2010

Geopolymer is a novel type of inorganic cementitious materials, which has become a hot
topic across the world. Geopolymerization process of metakaolin in alkaline solutions shows
important effects on final properties of hardened geopolymer. In this paper all the possible reaction
pathways involved in the dissolution-reorientation-polycondensation process of metakaolin in
alkaline solution were studied according to thermodynamic theory. The corresponding reaction
energy of every possible pathway was also calculated using computation chemistry methodsemi-
empirical AM1 calculation. The optimum reaction pathway was analysized based on the
energy-minimized principle. The calculation results showed that highly alkaline accelerated the
dissolution of 6-membered tetrahedron rings of SiO4 or AlO4 tetrahedron representing the
molecular structure of metakaolin during dissolution process. Si-Al hybrid reorientation should
theoretically be primary reorientation pathway during reorientation process. Framework clusters
should be primary polycondensation products during polycondensation process. The above studies
enhanced our understanding of formation mechanisms of metakaolin in alkaline solutions related to
geopolymerization.
Evaluation of the Stability of Waste-Based Geopolymeric Artificial Aggregates for Wastewater Treatment Processes under Different Curing Conditions
Authors: Silva Isabel Castanheira , Castro-Gomes João Paulo , Albuquerque António
Published: October 2010

Waste geopolymeric artificial aggregates (WGA) with different atomic ratios of mining
waste mud/Na2SiO (4 to 5) and Na2SiO/NaOH (1.25 to 5) were produced using curing temperatures
of 20°C and 130°C and its structural stability and pH variation after immersion in water was
observed during 3 months. Results showed that WGA with mud/Na2SiO and Na2SiO/NaOH of 5
and 4, respectively, cured at 20°C presented good stability in water and pH decreased from 10 to 7
in 24 days. Compressive strength was determined in additional samples cured at 20°C and 80°C in
dry conditions, for 13 curing ages and 15 water immersion periods (up to 14 weeks). Results of this
second stage showed that increasing temperature to 80°C accelerated compressive strength gain but
only during the first 3 weeks (up to 15.4 MPa). After 24 h in water compressive strength decreased
to half of the initial values determined in dry conditions in all samples and, therefore, the increase
of temperature did not bring benefits to WGA strength in water. Regardless the curing temperature
and the dry curing age comprehensive strength stabilizes between 1 MPa and 2 MPa after 4 weeks
immersion in water, which are values that makes WGA suitable to be used as bed material for
wastewater treatment processes.
Role of Alkaline Cations on Geomaterial Foams
Authors: Prud'Homme Elodie , Michaud Philippe , Joussein Emmanuel , Peyratout Claire , Smith Agnes , Rossignol Sylvie
Published: October 2010

The synthesis of geopolymers based on alkaline polysialate, was achieved at slightly elevated temperature, by alkaline activation of raw minerals and industrial waste. The materials were prepared from a solution containing dehydroxylated kaolinite and alkaline hydroxide pellets dissolved in potassium or sodium silicate. Then the mixture was transferred to a polyethylene mould sealed with a top and placed in an oven at 70°C during 24 hours. The addition of an industrial waste, silica fume, leads to the formation of an in-situ inorganic foam. Whatever the alkaline cation, foam formation occurs. The properties depend on the viscosity of silicate precursors due to the amount of water and to the size of alkaline.
The Federation for International Refractories Research and Education (FIRE): Progress and Outcome on Education, Research and Industrial Partnership
Authors: Rigaud Michel
Published: October 2010

FIRE has been incorporated as a non-profit organization in Canada, in May 2005. It is by now a network of professors, researchers and industrial partners, representing eight different universities spread in six different nations and eleven multinational companies, who have gathered, to undertake well-defined precompetitive research projects, and to train highly-qualified personnel for the industry. The evolution of the refractory education arena, in an economically globalized world, caught in a maelstrom of technical changes, is presented. The changes of paradigm from the “information age society” to the “crowdsourcing” in background, the FIRE realization are highlighted in such a context of “conceptual age society” are considered, with the concept of “coopetition”.
Organic Viscosity Modifiers for Controlling Rheology of Ceramic Slurries Used in the Investment Casting
Authors: Ferenc-Dominik Julia , Matysiak Hubert , Kurzydlowski Krzysztof Jan
Published: October 2010

The paper presents results of the study on the rheology modifiers of ceramic slurries
used in the investment casting. The ceramic slurries used in the study were based on aluminum
oxide powder in silica sol binder. Following modifiers were used as thickening agents: mpj, locust
bean and xanthan gums. The influence of the substances on the slurry viscosity were tested with a
silica sol binder before application to the ceramic slurries. The viscosity measurements were
carried out with the use of ARES and Brookfield rheometres. The results obtained demonstrate the
potential of employing the investigated substances as rheology modifiers for ceramic slurries used
in the investment casting.
Analysis and Interpretation of Microstructures after Liquid Oxide Corrosion
Authors: Poirier Jacques
Published: October 2010

Corrosion by liquid oxides is one of the most severe modes of degradations which limit the lifetime of the refractory linings. The study of the microstructures of corroded refractories provides essential information. However, the interpretation of the microscopic observations is difficult :
- The refractories are multi-component and heterogeneous ceramics,
- The microscopic observations are carried out at room temperature. They are not representative of the mineral and vitreous phases existing at high temperature,
- During cooling, new solid phases appear by crystallization of liquid oxides. The composition of the vitreous phases also evolves with the temperature.
Consequently, the information obtained is often limited.
In this paper , we will present a method to analyse and interpret the microstructures of refractories after use. The concept of local thermodynamic equilibrium and the use of the phase rule make it possible to interpret the microstructures of corroded refractories, to explain the observed mineral zonation and to quantify the composition of the liquid phase at high temperature from chemical profiles established by S.E.M.
Experimental data from corrosion of MgO-C, Al2O3-MgO and high alumina refractories will illustrate and validate this theoretical approach.
Calcium Zirconate as the Secondary Phase of Magnesia Refractories for Cement Rotary Kiln
Authors: Szczerba Jacek
Published: October 2010

The paper describes formation of the phases in magnesia-zirconia refractories due to reaction with the cement furnace charge in a form of pre-calcined meal or Portland clinker containing sulphur and chlorine in a different content at the temperature 1300°C and 1450°C. The studies were carried out by using the coating test. The microstructure changes of the contact zones between coating and the brick were studied by the scanning electron microscopy, SEM, coupled with EDS. The temperature dependence of reactivity the pre-calcined meal and Portland clinker in relation to the magnesia-zirconia bricks has been documented and discussed.
Simulation of Moulding of Refractory Bricks
Authors: Gruber Dietmar , Harmuth Harald
Published: October 2010

Simulations presented here aim to show reasons for undesirable product heterogeneity and possible defects. Potential negative influences are for example insufficient deaeration, friction between the bulk material and the mould, deformation of the mould and an inappropriate mould filling. In a first step data were collected from a production process. This includes the load and displacement during moulding and the mass of the mix filled into the mould. For the Finite Element modelling with ABAQUS the brick material was simulated with a Drucker-Prager model including a cap. The results show the influence of the friction between mix and mould on the densities and stresses in the pressed blank.
Impact of Free Fluor Fluxes on Nozzle Wear Mechanisms
Authors: Brandaleze Elena , Benavidez Edgardo , Peirani Valeria , Santini Leandro , Gorosurreta Carina
Published: October 2010

Fluoride emissions during continuous casting operations could cause health problems and equipment corrosion. For these reasons, nowadays free fluor mould fluxes are developed, using other oxides in order to substitute fluoride compounds. Although physical properties of the flux must be garantizied to prevent operation problems and product defects, it is relevant to analyse the effect of the new fluxes on the nozzle wear mechanisms. In this paper, the influence of B2O3 and Li2O on the wear of the nozzle materials is determined. A post mortem study on a nozzle used for steel billet casting that it was in contact with fluorides fluxes were carried out to identify the real wear mechanisms acting during operation. To determine and compare the effect of B2O3 and Li2O on the wear, static corrosion tests were developed on the same type of nozzle material. A similar corrosion mechanisms were identified in both cases: refractory melt infiltration and grain dissolution, but less penetration depth was observed for the flux containing B2O3 and Li2O. The results were correlated with some physical properties of the fluxes such as viscosity and surface tension.
Standard Testing of Refractories
Authors: Buttol Xavier , Erauw Jean Pierre
Published: October 2010

Refractories cover a wide range of products. With the aim to precisely describe the key product properties, end-users and refractory producers have progressively developed a common language: refractory standards. After a brief description of refractory standards history, and a synoptic overview of the present status, future prospects are illustrated by an example. The Belgian Ceramic Research Centre (BCRC) has recently launched a pre-normative research in the field of unshaped refractories. It focuses on robust methods to assess the workability and setting of hydraulically bonded unshaped products. Among the investigated methods, the so-called “exothermic profile” appears to have a high potential to become a standard for refractory producers or end-users.
Alumina-Mullite Refractories: Prototypal Components Production for Thermal Shock Tests
Authors: Brentari Alida , Labanti Martino , Mazzanti Francesca , Mingazzini Claudio , Sangiorgi Sergio , Villa Matteo , Martelli Stefano , Olevano Daniela
Published: October 2010

Alumina-mullite refractory tiles are used as liners in gas turbines for power production, for the thermal insulation of the combustion chambers. The typical microstructure is characterized by a coarse fraction, in order to increase porosity (and hence thermal insulation) and improve thermal shock resistance (by grain bridging mechanism). A mixture of alumina and ceramic wastes was optimized to manufacture prototypal components, by cold isostatic press (CIP). On sintering at 1600°C, a final composition of 40% mullite and 60% alumina was obtained.
For the production of refractory tiles with dimensions similar to the commercial ones, an appropriate mould was CAD-CAM designed and produced, using aluminium and silicone. 115 x 95 x 30 mm3 tiles were obtained and utilized for thermal shock tests. Samples were heated up to 1000°C and quenched to 20°C: this cycle was repeated 30 times before inspecting the macroscopic cracks. The results were compared with those obtained with a standard test for advanced technical ceramics based on MOR measurements. Two different pressing conditions were tested (60 and 150 MPa) in order to get data about a possible industrial production by uniaxial pressing.
Laboratory Study of Corrosion of an Alumina Refractory by Molten Potassium Salts
Authors: Li Na , Hupa Leena , Yrjas Patrik , Hupa Mikko
Published: October 2010

The increasing use of biomass and waste derived fuels in combustion challenges the
chemical durability of refractories. Durability of an alumina refractory was studied in a chemically
aggressive environment. A mixture of potassium chloride and carbonate (molar ratio 1:9) was
placed on the sample and heated at 700-1000°C in an electric laboratory furnace in air for one week.
Cross-sections of the samples were studied by SEM-EDXA to determine penetration of potassium
in the refractory. Potassium was found only in the silicate matrix phase of the alumina refractory.
Penetration of potassium decreased steeply from the surface to 1 mm, after which the decrease was
linear but varied with temperature. At 700 and 800°C the thickness of the matrix layer that had
reacted with potassium was 3 mm, while the layer was thinner at 900 and 1000°C. At the higher
temperatures a glassy layer consisting of K2O, Na2O, CaO and SiO2 formed on the refractory
surface. At 900°C the thickness of the surface layer was of 10μm, while a 200μm layer was
measured at 1000°C. The procedure used in this work can be used to develop a laboratory scale
method to be used to study corrosion of refractories in biomass combustion devices.
Carbon Containing Castables and More
Authors: Aneziris Christos G. , Dudczig Steffen
Published: October 2010

In terms of this work formulations of carbon bonded castables based on new binder approaches and nanoadditions
will be demonstrated. The new binder system allows the manufacturing of water based magnesia
carbon castables with the same properties and chemistry of pressed magnesia carbon bricks. This binder can be
also applied in oxide castables offering them high refractoriness and workability during processing. According to
the workability nano-additions improve significantly the spreading diameter of carbon castables and as a result
their flowability.
Microtexture Control of Alumina Using Anisotropic Alumina Particles
Authors: Hashimoto Shinobu , Yoshitaka Nishimura , Hirofumi Hirano , Sawao Honda , Iwamoto Yuji
Published: October 2010

A dense alumina body with anisotropic grains was fabricated from anisotropic particles
(platelets) after heating at 1650°C for 15 min under applying pressure of 60 MPa using a PECS
technique. When the alumina was cut on the vertical plane to the load direction while sintering, the
breakdown voltage was 15 KV/mm and thermal conductivity was 36 W/mK. On the other hand, a
porous alumina body was also synthesized from alumina platelets. The uniaxial pressure in
fabricating the green compact body had an influence on the relative density of the alumina body after
heating. The relative density and compressive strength of the compact that was uniaxially pressed at 1
MPa were 75 %, respectively. In addition, the relative density and compressive strength of compact
that was uniaxially pressed at 3 MPa were 64 %, respectively. The thermal conductivity of the porous
alumina with 64% in porosity was 0.8 W/Km.
Nanogaps for Sensing
Authors: Favier Frédéric
Published: October 2010

Modern resistive chemical sensors include discontinuous nano/mesostructures. Sensing performances are then governed by the chemical nature of the nanostructure gap as well as by the sensor design at the nanogap scale. Various top-down, bottom-up and hybrid fabrication routes of discontinuous/nanogaped metal nano and mesostructures have been developed. These structures are assembled/organized on insulating surfaces for integration of resistor based devices for the specific sensing of chemicals in gaseous as well as in liquid media. Hydrogen sensing based on discontinuous/gaped palladium nano/mesostructures is a chosen case-study for the evaluation of various nano/mesogap fabrication methods.
Development and Characterization of Transparent Glass Matrix Composites
Authors: Pang Bo , McPhail David S. , Jayaseelan Daniel Doni , Boccaccini Aldo Roberto
Published: October 2010

Glass matrix composites based on NextelTM fibre reinforced borosilicate glass were fabricated.
Unidirectional fibres were arranged in two directions with a periodic interspacing sandwiched
between two glass slides. XRD analysis and SEM observations proved that the selected
process parameters were effective in densifying the composites without significant
transparency losses. A geometry based equation was derived to evaluate the expected light
transmittance of the composites. ZrO2 coating on Nextel™ fibres, developed by a sol-gel
method, was investigated in order to provide a weak bonding at the fibre/matrix interface to
promote fibre pull-out during fracture. A developed hybrid sol-gel coating method was
employed to form a smooth and crack free coating surface on the Nextel™ fibre bundles. The
present composites show potential for applications in architecture and special machinery
requiring strong transparent windows.
Application of Fiber Produced by Plasma Spray Method in Cementitious Complex Binder
Authors: Kalpokaite-Dickuviene Regina , Brinkiene Kristina , Cesniene Jurate
Published: October 2010

The effect of microfiber produced from recycled waste catalyst on microstructure and mechanical strength of cementitious complex binder was analysed. Complex binder reinforced with 1%, 3% and 5% fibers were exposed to 600, 800 and 1000°C for 3h. The influence of annealing temperature on morphology of fiber reinforced complex binder was analyzed applying SEM, XRD techniques. Experimental results showed that reinforcement with 1% of fiber had advantage on mechanical strength of complex binder up to 800°C. Meanwhile addition of 5% of fiber resulted in lowest values of strength and reduced bulk density of complex binder in all firing temperature range.
Irradiation of a Nanocomposite of Pseudoboehmite-Nylon 6,12
Authors: Munhoz Jr. Antônio Hortêncio , Peres Renato Meneghetti , Silveira L.H. , Andrade e Silva Leonardo Gondim , de Miranda L.F.
Published: October 2010

Nanocomposites are nanometrical material particles embedded in a specific matrix. The degree of organization of the nanostructures and their properties depend on the nature of the organic and inorganic components of the structure that can generate synergic interactions. Polymeric nanocomposites are related to a class of hybrid materials where inorganic substances of nanometric dimensions are dispersed in a polymeric matrix. In the present work, nanocomposites of nylon 6,12 with different concentrations of pseudoboehmite obtained by sol-gel process were prepared with and without the presence of octadecylamine. After preparation, the samples were irradiated with a 200 kGy radiation dose in an electron accelerator. The pseudoboehmite nano particles were characterized by X-ray diffraction, scanning electron microscopy, differential thermal analysis and thermo gravimetric analysis. The nanocomposites were characterized by thermal and mechanical tests. The addition of pseudoboehmite promoted a reduction of the melting flow during the production of the composites evidencing the interaction of pseudoboehmite with the polymeric matrix, probably modifying its crystalline structure.
Synthesis of Carbon Nanotubes/Gold Nanoparticles Hybrids for Environmental Applications
Authors: Minati L. , Speranza G. , Bernagozzi I. , Torrengo S. , Toniutti L. , Rossi B. , Ferrari M. , Chiasera A.
Published: October 2010

Multi-walled carbon nanotubes were chemically cut by acid treatments and then deposited on 2-aminoethanethiol-modified gold substrate by the application of an external electric field. 2-aminoethanethiol-capped gold nanoparticles were then covalently bonded to the nanotubes to exploit their plasmon resonances. Reaction intermediates as well as the final products were analyzed by X-Ray Photoelectron Spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. The synergetic interaction between carbon nanotubes and gold nanoparticles leads to an efficient signal enhancement in Raman spectra. This is of particular interest for the detection of toxic molecules dangerous for the environment.
MoO3-x Nanowires as Inorganic Components of Liquid Crystalline Elastomer Composites
Authors: Domenici Valentina , Conradi Marjetka , Remškar Maja , Mrzel Aleš , Zalar Boštjan
Published: October 2010

MoO3-x nanowires belong to photocromic materials and are promising candidates for lithium intercalation, hydrogen sensing, and smart windows. We report on a successful preparation of liquid single crystal elastomers (LSCE) containing MoO3-x nanowires, mostly the conductive Mo5O14 phase. Preparation and basic chemical and physical properties of these materials are discussed in view of the potentiality of these composites as actuators. The particular combination of molybdenum based nanowires and LSCE enables functionalization of liquid single crystal elastomers preventing the pristine mechanical and optical properties of the host matrix.
Materials Performance in Advanced Steam Cycle and in Oxy-Fuel Combustion Systems
Authors: Natesan Ken , Zeng Zuo Tao
Published: October 2010

The U.S. Department of Energy (DOE) Office of Fossil Energy is intensely promoting research and development of materials for advanced steam cycle systems and for oxy-fuel combustion systems. At Argonne National Laboratory, we have conducted studies to evaluate the corrosion performance of candidate structural alloys in coal-ash and in steam environments, in support of advanced steam cycle systems. The laboratory tests simulate the combustion atmosphere of advanced steam-cycle systems and three deposit chemistries that included ash constituents, alkali sulfates, and NaCl. Corrosion rate data will be presented for several Fe- and Ni-base alloys along with the mechanistic understanding of the corrosion processes. In the study on materials for oxy-fuel applications, we have evaluated the corrosion performance of the materials in CO2, steam, and in steam-CO2 mixtures. Materials selected for the study include intermediate-chromium ferritic steels, Fe-Cr-Ni heat-resistant alloys, and nickel-based superalloys. Information will be presented for materials exposed at temperatures between 650 and 950°C for times up to 10,000 h. In the ongoing experiments, we have incorporated low levels of sulfur and chlorine compounds (in addition to CO2 and steam) in the exposure environment to establish the role of second/third reactant on the scaling, internal penetration, and long term performance of the structural alloys.
Selection of Ceramics and Composites as Materials for a Supercritical Water Gasification (SCWG) Reactor
Authors: Richard Thierry , Poirier Jacques
Published: October 2010

In the presence of supercritical water, organic materials are converted into energetic gas,
with high hydrogen content. In the present application, thermochemical conversion of humid wastes
from wine or sugar production is reached at temperatures and pressures up to 550°C and 250 bars.
Material is a key point for the development of SCWG process operating in such conditions. In
supercritical water the durability of metals and alloys is limited by corrosion, but ceramics and
ceramic composites are known to be stable under extreme conditions. For this reason, we have
proceeded to an examination of a selection of ceramic materials that could be used as an anticorrosive
wall of the gasification reactor. We show that, ultra-high temperature ceramics Si3N4, BN,
Al2O3 and SiC are strongly corroded by humid waste, but carbon-based materials are resistant in
both subcritical and supercritical conditions in the presence of pure or waste water. As a conclusion,
graphite may be a very good material for SCWG reactor.
High Temperature Water Electrolysis Using Metal Supported Solid Oxide Electrolyser Cells (SOEC)
Authors: Schiller Günter , Ansar Asif , Patz Olaf
Published: October 2010

Metal supported cells as developed at DLR for use as solid oxide fuel cells by applying plasma deposition technologies were investigated in operation of high temperature steam electrolysis. The cells consisted of a porous ferritic steel support, a diffusion barrier layer, a Ni/YSZ fuel electrode, a YSZ electrolyte and a LSCF oxygen electrode. During fuel cell and electrolysis operation the cells were electrochemically characterised by means of i-V characteristics and electrochemical impedance spectroscopy measurements including a long-term test over 2000 hours. The results of electrochemical performance and long-term durability tests of both single cells and single repeating units (cell including metallic interconnect) are reported. During electrolysis operation at an operating temperature of 850 °C a cell voltage of 1.28 V was achieved at a current density of -1.0 A cm-2; at 800 °C the cell voltage was 1.40 V at the same operating conditions. The impedance spectra revealed a significantly enhanced polarisation resistance during electrolysis operation compared to fuel cell operation which was mainly attributed to the hydrogen electrode. During a long-term test run of a single cell over 2000 hours a degradation rate of 3.2% per 1000 hours was observed for operation with steam content of 43% at 800 °C and a current density of -0.3 Acm-2. Testing of a single repeating unit proved that a good contacting of cell and metallic interconnect is of major importance to achieve good performance. A test run over nearly 1000 hours showed a remarkably low degradation rate.
Hydrogen Storage on Beryllium-Coated Toroidal Carbon Nanostructure C120 Modeled with Density Functional Theory
Authors: Castillo-Alvarado Fray de L. , Ortíz-López Jaime , Arellano J.S. , Cruz-Torres Armando
Published: October 2010

Ab initio density functional calculations were performed on a toroidal carbon C120 nanostructure with a single beryllium atom bonded to its outer surface. These calculations are based on DFT with the generalized gradient approximation PW91 (Perdew and Wang) as implemented in the Materials Studio v.4.3 code. The Dmol3 module was used to calculate, among others, total energy, charge density, HOMO-LUMO and Mulliken population analysis. On the basis of these results, the beryllium-coated toroidal carbon C120 nanostructure appears to be a good candidate for H2 storage with moderate adsorption energy.
Numerical Simulation of Hydrogen Dynamics at a Mg-MgH2 Interface
Authors: Giusepponi Simone , Celino Massimo
Published: October 2010

Hydrogen desorption from hydride matrix is still an open field of research. Extensive abinitio molecular dynamics simulations are performed to characterize the desorption process at the interface MgH2-Mg. The numerical model succesfully repoduces the experimental desorption temperature for the hydride with and without Fe catalyst. Formation energies and work of adhesion are computed and linked to the desorption mechanism. Moreover a detailed analysis of the structural data reveals the role played by the catalysts in the lowering the desorption temperature.
Thermodynamic Database for Hydrogen Storage Materials
Authors: Baricco Marcello , Palumbo Mauro , Pinatel Eugenio , Corno Marta , Ugliengo Piero
Published: October 2010

In order to be used for applications, the thermodynamic stability of a candidate hydrogen storage material should be suitable for hydrogen sorption at room conditions. By mixing different hydrides, it is possible to promote the hydrogenation/dehydrogenation processes. On the other hand, small changes in composition allow a tailoring of thermodynamic stability of hydrides. Knowledge of thermodynamic stability of hydrides is thus fundamental to study the hydrogenation/dehydrogenation processes and useful to rationalize synthesis reactions and to suggest possible alternative reaction routes. The purpose of this work is to develop a consistent thermodynamic database for hydrogen storage systems by the CALPHAD approach. Experimental data have been collected from the literature. When experimental measurements were scarce or completely lacking, estimations of the energy of formation of hydrides have been obtained by ab initio calculations performed with the CRYSTAL code. Several systems of interest for hydrogen storage have been investigated, including metallic hydrides (M-H) and complex hydrides. The effect on thermodynamic properties of fluorine-to-hydrogen substitution in some simple hydrides is also considered. Calculated and experimental thermodynamic properties of various hydrides have been compared and a satisfactory agreement has been achieved.
Fabrication of an Intermediate-Temperature Anode-Supported Planar SOFC Via Tape Casting and Lamination
Authors: An Chung Min , Sin Yong Wook , Yoon Jiun , Sammes Nigel
Published: October 2010

Many physical and chemical problems in solid oxide fuel cells (SOFC) are induced by the operating temperature of approximately 800 ~ 1000°C. The focus of the research in SOFC’s is, thus, on running the systems at the intermediate operating temperature range below 800 °C. A way to achieve this includes changing the electrolyte material in order to get a good ionic conductivity in the intermediate temperature range below 800 °C. In this work, gadolinium doped ceria is selected as the electrolyte, which was mixed with NiO for the anode material, and tape cast and laminated to produce a novel graded IT-SOFC . The cross-section of the SOFC cell was observed using Scanning Electron Microscope (SEM) showing a dense electrolyte layer. The operating temperature to test the cell was 500 and 550 °C. The electrochemical properties of the cell were measured using impedance spectroscopy. The ASR of unit cells was found to be between 2.67 and 4.62 Ω∙cm2. The electrochemical performance is discussed under the effect of porosity gradients at 500 and 550 °C.
Hybrid Membranes for Proton Exchange Fuel Cell
Authors: Valle Karine , Pereira Franck , Rambaud Frederic , Belleville Philippe , Laberty Christel , Sanchez Clément
Published: October 2010

Fuel cell technology has merged in recent years as a keystone for future energy supply. The proton exchange membrane fuel cell (PEMFC) is one of the most promising projects of this energy technology program; the PEMFC is made of a conducting polymer that usually operates at temperatures in the range 20-80°C. In order to reach high energy consumption application like transportation, the using temperatures need to be increased above 100°C.
Sol-gel organic/inorganic hybrids have been evaluated as materials for membranes to full file the high temperature using requirement. These new materials for membrane need to retain water content and therefore proton conductivity property with using temperature and time. The membranes also need to be chemical-resistant to strong acidic conditions and to keep their mechanical properties regarding stacking requirements. In order to! answer all these specifications, the proposed hybrid membranes are based on nanoporous inorganic phase embedded in an organic polymer in which chemical grafting and conductivity network microstructure are optimized to preserve both water-uptake and proton conductivity at higher temperatures. Such very promising results on these new hybrids are presented and discussed regarding electrochemical properties/microstructure
Investigation of a Passive DMFC Mini-Stack at Room Temperature
Authors: Arico’ Antonino Salvatore , Baglio Vincenzo , Stassi Alessandro , Antonucci Vincenzo
Published: October 2010

Direct Methanol Fuel Cells (DMFCs) are promising candidates for portable electric power sources because of their high energy density, lightweight, compactness, simplicity as well as easy and fast recharging. Recently, the attention has been focused on portable applications with passive-feed DMFCs. Under this configuration, DMFCs operate without any external device for feeding methanol and blowing air into the cells. An investigation of properties and operating parameters of a passive DMFC monopolar mini-stack, such as catalyst loading and methanol concentration, was carried out. From this analysis, it was derived that a proper Pt loading is necessary to achieve the best compromise between electrode thickness and number of catalytic sites for the anode and cathode reactions to occurs at suitable rates. Methanol concentrations ranging from 1 M up to 10 M (40 vol%) and an air-breathing operation mode were investigated. A maximum power of 225 mW was obtained at ambient conditions for a three-cell stack, with an active single cell area of 4 cm2 corresponding to a power density of about 20 mW cm-2.
Solutions for Material Corrosion Problems in MCFC
Authors: Frangini Stefano , Moreno Angelo , Zaza Fabio
Published: October 2010

It is widely recognized that metallic corrosion of the cathode current collector is a key technological problem that must be fully resolved before Molten Carbonate Fuel Cells can be commercialized on a more competitive basis. This paper presents a short overview on the corrosion mitigation strategies that appear more appropriate for MCFC current collectors. As alternative to the current use of the 300-series austenitic stainless steels, specialty high-Mn stainless steels, corrosion-resistant Ni-based alloys and sol-gel coatings of thin conductive spinel or perovskite ceramic layers are seen as the most promising corrosion solutions for the cathode-side environment. The use of basic additives into electrolyte for inhibiting molten carbonate corrosion is a further mitigation option yet with less practical perspectives due to the high constraints on the electrolyte properties. Recent and current studies conducted at ENEA on MCFC corrosion solutions are also mentioned.
Computational and Experimental Design of Novel High Temperature Alloys
Authors: Brammer Travis , Ray Pratik K. , Misra Sumohan , Ye Yi Ying , Akinc Mufit , Kramer Matthew J.
Published: October 2010

Discovery of new high temperature alloys is a multidimensional problem which encompasses the intrinsic thermodynamic stability and their thermo-chemical and thermo-mechanical response to the combustion environment. Even when considering only the transition metals in combination with stable oxide formers, the number of ternary combinations exceeds 104. Hence, the traditional Edisonian process is not a practical approach to develop new alloy systems. Using formation enthalpy as a guide to compound stability, we propose a hierarchical scheme for identifying potential alloy systems which involves sifting through large regions of phase space with increasingly more accurate analysis. The coarsest sieve is a semi-empirical method based on the Miedema model extended to ternary systems. The next stage is ab initio simulations for a more accurate assessment and the basis for selecting system to investigate experimentally. We describe the implementation of this approach through the discovering of ternary additions that improve the oxidation stability -NiAl alloy.
Nanostructured Anode Material for Li-Ion Batteries
Authors: Ferrara Germano , Arbizzani Catia , Damen Libero , Inguanta Rosalinda , Piazza Salvatore , Sunseri Carmelo , Mastragostino Marina
Published: October 2010

The present paper focuses on a nanostructured SnCo alloy electrochemically prepared by template method in view of its use as anode material alternative to graphite in lithium-ion batteries. The fabrication of SnCo nanowire arrays was carried out by potentiostatic co-deposition of the two metals by using nanostructured anodic alumina membranes as template. Electrochemical tests on lithiation-delithiation of these SnCo electrodes in conventional organic electrolyte (EC:DMC LiPF6) at 30°C showed that their specific capacity was stable for about the first 12 cycles at a value near to the theoretical one for Li22Sn5 and, hence, progressively decayed.
Printed Supercapacitor as Hybrid Device with an Enzymatic Power Source
Authors: Keskinen Jari , Sivonen Eino , Bergelin Mikael , Eriksson Jan Erik , Sjöberg-Eerola Pia , Valkiainen Matti , Smolander Maria , Vaari Anu , Uotila Johanna , Boer Harry , Tuurala Saara
Published: October 2010

Low cost printable power sources are needed e.g. in sensors and RFID applications. As manufacturing method printing techniques are preferred in order to keep the costs low. The materials should also be easily disposable. Enzymatic bio-fuel cells are an alternative for printable primary batteries. Since one drawback of bio-fuel cells is their low power, we have developed supercapacitors that can be combined with enzymatic bio-fuel cells to provide the power peaks necessary in the applications. The materials for the supercapacitors have been chosen to be compatible with the fuel cell and with printing methods, e.g. the activated carbon powder in the electrodes was bound with chitosan. As printing substrates we have used paperboards. The current collectors have been made of graphite and metal inks. Since the voltage requirement is limited to approximately 1 V, aqueous electrolytes have been used. Printed supercapacitors of various sizes have been prepared. The geometrical electrode areas have been between 0.5 and 2 cm2. The maximum feasible output current has been in the order of 50 mA corresponding to about 50 mW power. When the capacitor is used together with an enzymatic power source, the leakage current must be as low as possible. Typical leakage current values have been in the order of 10 µA.
Comparison of High Temperature Mechanical Behaviour and Microstructure of the New Gamma–TiAl8Ta with Gamma-TiAl8Nb Alloy
Authors: Angella Giuliano , Lupinc Valentino , Maldini Maurizio , Onofrio Giovanni
Published: October 2010

The high temperature creep and fatigue properties of two  -TiAl base intermetallic alloys, for gas turbine components, have been investigated within the Integrated European project IMPRESS. The alloys contain 8% at. of Ta or Nb, respectively. The microstructure of both alloys was cross convoluted lamellar rather than the well known conventional lamellar, typical of the usual -TiAl. The microstructure of the Ta containing alloy was homogeneous in all the analyzed batches whilst that of the Nb alloy appeared significantly spread out from specimen to specimen. The creep properties of the alloys were investigated in the temperature range 700-850°C with applied stresses in order to have times to rupture up to about 3,000 h. The creep behaviour presented no steady state regimes, but only minima of the creep rates between significant decelerating and accelerating regimes. The minimum creep rates of the Ta alloy resulted to be significantly slower than the Niobium alloy at the same creep conditions. In low cycle fatigue at 650 and 700°C the Ta  -TiAl showed longer lives than the Nb alloy, whilst the fatigue crack propagation rate in the same temperature range did not show any significant difference. Threshold values of stress intensity factor range were accurately measured at different R ratio. The microstructures of the two alloys were analysed by scanning microscopy in order to rationalise the different mechanical behaviour.
Self Diagnostic EB-PVD Thermal Barrier Coatings
Authors: Nicholls John R. , Wellman Richard G. , Steenbakker Remy , Feist Jörg
Published: October 2010

Thermal barrier coatings (TBCs) are an enabling materials technology to improve the efficiency and durability of gas turbines and thus through such efficiency improvements offer reduce fuel usage and an associated reduction in CO2 emission. This commercial drive is pushing both aero- and industrial turbines to be lifetime dependent on TBC performance – the TBC must be “prime reliant”.
However, the prediction of the durability of the TBC system has proved difficult, with lifetimes varying from sample to sample and component to component. One factor controlling this is the inability to measure accurately the bondcoat/ceramic interface temperature when buried under a TBC. In operating engines this is further exacerbated by the fact that such TBC systems operate in strong temperature gradients due to the need to cool aerofoil components.
This research examines the design and manufacture of self diagnostic thermal barrier coatings capable of accurately measuring the interface temperature under the TBC, whilst providing the requisite thermal protection. Data on the temperature sensing capability of various rare earth doped EB-PVD thermal barrier coatings will be reported. It will be shown that systems exist capable of measuring temperatures in excess of 1300oC. Details of the measurement method, the compositions and the thermal stability of such systems will be discussed in this paper. The ability to produce a sensing TBC capable of measuring interface temperature, surface temperature and heat flux will further be discussed permitting the design of thermal barrier protected components capable of in-situ performance monitoring.
Water Gas Shift Reaction in Pd-Based Membrane Reactors
Authors: Basile Angelo , Pinacci Pietro , Tosti Silvano , De Falco Marcello , Evangelisti Claudio , Longo Tiziana , Liguori Simona , Iulianelli Adolfo
Published: October 2010

Water-gas shift reaction is an important industrial reaction, used for producing synthesis gas and ammonia as well as pure hydrogen for supplying at PEM fuel cells. In this work, an overview on water gas shift reaction performed in Pd-based membrane reactors is shown, paying particular attention to the influence on the performances of some operating variables such as reaction temperature, reaction pressure, H2O/CO molar ratio and sweep gas.