bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction between the Ceramic CaZrO3 and the Melt of Titanium Alloys
Authors: Li Chong He , Gao Yong Hui , Lu Xiong Gang , Ding Wei Zhong , Ren Zhong Ming , Deng Kang
Published: October 2010

The CaZrO3 complex oxide ceramic was synthesized in the development
of the potential refractory for melting of titanium alloy, the crucible ( 40XH40mm)
was prepared by the solid sintering of mixture of powder (CaO:ZrO2 =1:1) with a
small amount of TiO2 as additive at 1750°C. The melting of TiNi and Ti6Al4V was
carried out in the inducting furnace under vacuum or/and Ar atmosphere. The
interfacial reaction between the melts of alloys and CaZrO3 refractory was
investigated by scanning electron microscope (SEM) with energy dispersive X-ray
spectroscopy (EDS). It is found that, the thickness of interfacial reaction layer
between the ceramic CaZrO3 and the melt of titanium alloys (TiNi and Ti6Al4V) is
approximately 30-300 μm, there are few elements such as Ca, Zr, Ti, and Ni diffused
through the interfacial reaction layer. These results may provide the basement to
designing a novel refractory for melting of titanium alloys.
The Latest Trends in Refractories Technology for Iron and Steel Production at Nippon Steel Corporation
Authors: Matsui Taijiro
Published: October 2010

In this report, the trends in refractories technologies for iron and steel production at Nippon Steel Corporation in the last few decades are outlined. Amid dramatic changes in crude steel production accompanying increased ratios in higher quality of steel and sophisticated refining methods, in in our refractory ceramics R&D Div., actual machines have been realized by practicing developed outcomes with technologies for every production process relating to: refractory material quality, furnace building or execution, reparation, diagnosis, demolition, and recycling. Thus, continuing reduction in the unit consumption of refractories has been steadily performed. Additionally, technical issues are reduced to further enhance and maintain our international competitiveness in refractories technologies.
Characterisation of the Fracture Path in ‘Flexible’ Refractories
Authors: Harmuth Harald
Published: October 2010

The denomination ‘flexible’ is chosen in the professional jargon of refractories technology for materials able to bear relatively high strains without or with acceptable loss of strength. In many cases this term is equivalent to relatively low brittleness. Characterisation of brittleness based on fracture mechanical investigations may use figures of merit like brittleness numbers, a so called characteristic length or the R’’’’ parameter according to Hasselman. In many cases these figures show that brittleness reduction of refractories is achieved by decrease of strength with at the same time more or less unaffected specific fracture energy. Microscopic investigations of fracture paths aim to exhibit which peculiarities of crack microstructure enable this change of mechanical properties. A microscopical technique developed for this purpose separately evaluates the relative crack lengths along the grain/matrix interface, within the matrix and within the grain. Results obtained for several types of refractories show brittleness decrease is associated by an increase of the relative crack length along the grain/matrix interface and a decrease of transgranular fracture. Prefabricated microcracks and a relatively low grain/matrix bond strength may support this type of crack propagation.
Thermomechanical Characterization of Monolithic Refractory Castables
Authors: Cutard Thierry , Donval Nicolas , Mazzoni Aurélien , Michel Claire , Nazaret Fabien
Published: October 2010

This paper deals with the characterization of the thermomechanical behavior of monolithic refractory castables in a wide temperature range, up to 1200°C. Different test types are considered: tensile tests, compression tests, bending tests and tests on more complex shapes and geometries. A particular attention is paid to the detailed characterization and interpretation of the non-linear behaviors of these materials. Monotonic, cyclic and creep tests are considered. In some cases, digital image correlation (DIC) methods can be coupled to mechanical tests to obtain strain fields. Such results are particularly interesting to observe and to understand damage processes.
As damage is a major characteristic of the monolithic castable behaviors, links are established between the thermomechanical behavior and damage mechanisms. Two main scales are taken into account for damage characterization: the macroscopic and the microscopic ones. Main mechanisms that are considered deal with microcracking, macrocracking, debonding and cavitation. Two types of materials are considered: non-reinforced and fiber reinforced refractory castables.
Mechanical Behaviour of MgO-CaZrO3-Based Refractories for Cement Kilns
Authors: Baudín Carmen , Pena Pilar , Obregón Álvaro , Rodríguez-Galicia Jose Luis
Published: October 2010

The mechanical behaviour of ceramic refractories formulated in the MgO-CaO-SiO2-
ZrO2 system is analysed in terms of the room temperature Young´s modulus, the modulus of
rupture and the work of fracture at 25 and 1100°C. The materials have been designed taking into
account the phase equilibrium relationships to obtain MgO-CaZrO3-Ca2SiO4-Ca3Mg(SiO4)2 or
MgO-CaZrO3-Ca3Mg(SiO4)2-c-ZrO2 as final crystalline phases. Different relationships between the
proportion and sizes of the fines and the aggregates have been explored. The microstructure of the
materials has been characterised in terms of density, crystalline phases and phase distribution and
morphology. A combination of X-Ray diffraction (XRD) analyses and Reflected Light Optical
Microscopy (RLOM) has been used. The relationships between the obtained phases and
microstructures and the grain size distributions of the used raw materials have been established. The
relationships between the mineralogical composition and the obtained microstructure and the
mechanical behaviour are discussed.
Novel Refractory Development for Synthetic Rutile Manufacture via the Becher Process
Authors: Stone Nigel A. , Wright Wayne , O'Byrne Marty , Bow Stuart
Published: October 2010

Australia is fortunate in that it has ~80,760 kt (Ti equivalent) representing 15% of the
world’s titanium resources in the form of ilmenite, rutile, anatase and leucoxene. Although of late
the annual quantity of mined material has reduced due to the global financial situation, the average
amount of material mined was of the order of 700 kt (Ti eq). To date the most common process
used for beneficiating the ilmenite in Australia has been the Becher process to produce synthetic
rutile of the order of 92-96% TiO2. Due to the nature of the mineralogy of the deposits, a very
small amount of naturally occurring radioactive materials (mainly thorium) is present which for
some applications is considered unacceptable. Consequently a number of years ago the Synthetic
Rutile Enhancement Process (SREP) was developed which removes the thorium contamination
through the use of a boron containing mineral additive [1,2,3], which complexes the radioactive
material during the reduction process. Unfortunately the consequences of this reaction is the build
up of a flux-like material on the walls of the rotary kilns leading to significantly reduced throughput
and even significant refractory loss. The aim of this paper is therefore to describe the development
of a novel refractory castable system utilising the in-situ formation of aluminium titanate which in
combination with matrix chemistry control and thermo-mechanical property design, greatly
inhibited the adhesion of process flux on the refractory walls. The development strategy and
subsequent history from simulated laboratory testing and early small scale trials up to the
performance of the novel refractory in a fully lined kiln operating over a number of years will be
highlighted.
Effect of Surface-Modified Si-Al-C® Fibre Addition on the Mechanical Properties of Silicon Carbide Composite
Authors: Moriyasu H. , Kita J. , Suemasu H. , Davies Ian J. , Koda S. , Itatani K.
Published: October 2010

The effect of surface modified Si-Al-C® fibre with carbon interface (SA/C fibre) addition
on the densification of silicon carbide (SiC) composite was examined. An acid treatment (H2SO4
and HNO3) was carried out at 50°C for 3 h in order to add COO- group to the surface of SA/C fibre
and to enhance the dispersibility of SA/C fibre in the SiC powder due to the mixing operation in the
polar solvent. Commercially available ultrafine SiC powder (specific surface area: 47.5 m2∙g-1) was
mixed with acid-treated SA/C fibre and sintering aid (4.8 mass% Al4C3 and 1.2 mass% B4C) in the
presence of acetone. The relative density of the SiC composite with non-acid-treated SA/C fibre
addition hot-pressed at 1800°C for 1 h in Ar atmosphere under a pressure of 62 MPa was 98.4%,
whereas that of the SiC composite with acid-treated SA/C fibre addition increased to 98.7%.
Furthermore, the fracture toughness increased from 5.6 MPa∙m1/2 to 7.0 MPa∙m1/2 for the
acid-treated SA/C fibre addition.
XPS Study of In Situ One-Step Amination of Nanocrystalline Diamond Films
Authors: Torrengo S. , Miotello Antonio , Speranza G. , Minati L. , Bernagozzi I. , Ferrari M. , Chiasera A. , Dipalo M. , Kohn Erhard
Published: October 2010

In the present work two different in situ amination of hydrogenated nano-crystalline
diamond surfaces were studied. The effects of an UV irradiation in pure ammonia gas were
compared to those produced in a mixture of pure ammonia gas with a small amount of pure oxygen.
In situ XPS analysis was used to study the evolution of surface terminations from “C-H” to “CNH2”.
As we will show in this work, the grafting of NH2 functional groups to the diamond surface
is mediated by oxygen indicating that oxygen plays a crucial role in the process of amination.
Simulation of Complex Dielectric Materials
Authors: Quandt Alexander , Leymann Heinrich Alexander Magnus
Published: October 2010

Photonic crystals are not only responsible for the beautiful colors of opal gems, butterflies
and peacocks. They are also of great technological interest as the key elements of a large variety of
modern photonic devices [1]. We present a domestic simulation package, which has been developed
for the optimum design of such devices. It basically consists of a number of MATLAB routines,
which should allow for a convenient determination of photonic band structures and related
properties. We briefly mention some of the main numerical challenges involved in the development
of the most effective code. Then we discuss the main features of photonic band structures obtained
for complex dielectric materials, and finally describe some useful numerical features, that will be
implemented in future versions of our program package.
Rare – Earth – Doped Silicate Glass – Ceramic Thin Films for Integrated Optical Devices
Authors: Berneschi Simone , Alombert-Goget Guillaume , Armellini Cristina , Bhaktha B.N.S. , Brenci Massimo , Chiappini Andrea , Chiasera A. , Ferrari Maurizio , Guddala Sriram , Moser Enrico , Nunzi Conti Gualtiero , Pelli Stefano , Righini G.C. , Turrell Sylvia
Published: October 2010

The possibility to confine the light in optical planar structures represented the milestone
for the development of integrated optical devices in different application areas, such as
communications and sensing. In particular, rare-earth (RE) doped planar waveguides demonstrated
to be an interesting solution in the realization of integrated optical lasers and amplifiers suitable for
the generation/regeneration of the signal in metropolitan and local area networks. Nowadays,
although these devices are commercially available, the major contribution of the research consists in
discovering and developing better combinations of materials and fabrication processes, in order to
reduce the costs and increase the performance of the aforesaid devices. In this context glass-ceramic
waveguides, activated by RE ions, seem to fully respond to these requests. The aim of this paper is
to offer a comprehensive review on the main results obtained in our Labs in the field of glassceramics.
Fabrication and characterization of different silicate glass-ceramic thin films, doped with
different percentages of RE ions, will be presented and discussed. The interesting results obtained
make these systems quite promising for development of high performance integrated optical
amplifiers and lasers.
The Ballistic Impact Characteristics of Woven Fabrics Impregnated with a Colloidal Suspension and Flattened Rolls
Authors: Kim Chun Gon , Kim Il Jin , Lim Gun , Yoon Byung Il
Published: October 2010

This research investigated the ballistic impact characteristics of KM2 Kevlar fabrics and
Dyneema UD for personnel body armour using two stage gas gun. The neat KM2 Kevlar fabrics
were compared with those impregnated with shear thickening fluid(STF) which showed to absorb
much energy up to a velocity of 300m/s. Also studied are the effects of projectile shapes on the
energy absorbing in fabrics. We observed that the fiber pull out distance without breaking is
important for ballistic energy absorption. We devised an efficient ballistic energy absorbing
mechanism at high velocity range by adopting flattened roll design of Dyneema UD. The suggested
hybrid design composed of flattened roll and KM2 fabric impregnated with STF with stitching had
advantage of 15~20% areal density reduction compared with neat KM2 fabric design.
Thermally Controlled Crystallization of Electrospun TiO2 Nanofibers
Authors: Park Hyoung Jun , Sigmund Wolfgang M.
Published: October 2010

The anatase phase of TiO2 has been of great interest due to its photocatalytic activity. For
enhanced photocatalytic activity, the polymorphic structure of anatase phase and the rutile phase
was pursued to form the semiconductor-semiconductor junction, which could even further enhance
photocatalytic activity. TiO2 nanofibers with large specific surface area were fabricated via
electrospinning from ethanol-based sol while the phase development was controlled by heat
treatment. TiO2 fibers were characterized by x-ray diffraction (XRD) and transmission electron
microscopy (TEM) for the crystalline phase and its microstructure, respectively. Among different
heat treatment temperatures tested, 700°C was found to have the smallest grains while having both
semiconductor, i.e. rutile and anatase available. TiO2 calcined at 800°C also achieved the
polymorphic structure of anatase and rutile phases, however showed significant grain growth.
Ceramic Membranes in Carbon Dioxide Capture: Applications and Potentialities
Authors: Drioli Enrico , Brunetti Adele , Barbieri Giuseppe
Published: October 2010

Today, CO2 capture from e.g. flue gas has becoming an emerging opportunity for membrane gas separation. The flue gas coming out from power plants contains about 10-15% CO2, which should be separated before its sequestration. The most used membranes for this application are polymeric but they cannot be used at a high temperature. The flue gas exits at ca. 200°C, depending on the specific locations in the plant and, thus, it is highly desirable to separate it at high temperature.
An alternative class to polymeric membranes is represented by the ceramic one which comprises zeolites, carbons, silica, perovskites membranes, that exhibit high fluxes and thermal resistance. However, a great challenge is to fabricate them as thin layers, avoiding formation of cracks that compromise the separation. Today, new solutions are in progress for the production of ceramic membrane able to overcome these limitations. For example, hybrid membranes able to combine the properties of different materials are proposed. Moreover, new works are done on mixed-matrix membranes, comprising of a molecular sieve guest phase dispersed in a polymer host matrix [3] which combines the advantage offered by the two materials. This work proposes an overview on the main applications of ceramic membranes in CO2 capture processes.
Hydrogen Desorption Reactions of the Na-Mg-B-H System
Authors: Pottmaier Daphiny , Garroni Sebastiano , Barò Maria Dolors , Baricco Marcello
Published: October 2010

Hydrogen storage in the solid state has shown increasing research and development, and recently an approach in mixing two hydride systems together by ball milling (reactive hydride composites) has been investigated in more detail, e.g. NaBH4 plus MgH2. Thermodynamic destabilization may occur by new compounds formation during dehydrogenation, e.g. MgB2. A study of the the role of O2/H2O contamination for the reaction 2NaBH4 + MgH2 ↔ 2NaH + MgB2 + 4H2 was conducted using in-situ X-ray powder diffraction. Desorption reaction is observed to begin by a competition of MgH2 and NaBH4 decomposition due to higher reactivity promoted by ball milling processing summed to O2/H2O contamination. Oxidation of NaBH4 into NaBO2 is observed to happen in higher degree than MgH2/Mg into MgO for the Na-Mg-B-H system.
Innovative Systems for Hydrogen Storage
Authors: Guardamagna Cristina , Cavallari Andrea , Malvaldi Veronica , Soricetti Silvia , Pontarollo Alberto , Molinas Bernardo , Andreasi Diego , Lo Russo Sergio , Capurso Giovanni , Magistri Loredana , Monteverde Michela , Nava Riccardo , Mazzanti Viviana
Published: October 2010

One of the main challenges in the perspective of a hydrogen economy is the
development of a storage system both safe and with high weight capacity. Among the most
promising systems are the storage in metals and chemical hydrides and the high pressure storage
in tanks made of composite materials. Both these technologies allow volumetric densities equal
or higher than that of liquid hydrogen.
The present work deals with the results obtained in a Italian national project, whose objectives
have been the development of innovative technologies in specific applications: large scale energy
storage, stationary applications in distributed generation, and automotive (with a particular
attention to the fluvial and the sea transportation in protected areas).
The theoretical, modellistic and experimental activities have been oriented to the development of
innovative high capacity metal hydrides, the study of a regeneration method for chemical
hydrides, the integration of intermediate pressure electrolyzers with advanced compressors and,
finally, the development of thermomechanical models for executive design of storage systems. A
number of prototypes has been realised and installed in a test facility in the Fusina (Venezia)
power plant. The activity has been completed with an executive feasibility evaluation, in the
perspective of industrial applications.
Alloy Design and Processing Challenges for Advanced Power Systems: An Alloy Producer’s Perspective
Authors: Maurer Gernant E. , Patel Ashish D.
Published: October 2010

The alloys required for fossil fuel power systems are transitioning from stainless steels that operate below 600oC to nickel-based alloys that can operate up to 760oC in advanced ultra-super critical steam turbines. This transition brings with it major metallurgical as well as economic challenges related to alloy design, melt processing, and fabrication of these large size components. The alloys, in general, must maintain creep resistance over 100,000 hours of service life while at the same time maintaining resistance to severe steam oxidation and general oxidation. A need exists for nickel-based alloys that are not only highly alloyed, but are also impervious to phase instabilities during initial processing and service. The potential exists for severe segregation when casting large ingots. This possibility must be dealt with during thermo-mechanical processing to obtain the wrought structures that can be inspected to design defect levels. This paper will detail these challenges as they have been addressed in smaller aerospace turbines and discuss strategies to overcome these problems. New computational modeling tools will play a critical role in engineering solutions for alloy design, solidification, forging, and heat treatment. Since any solution also needs to be economically viable, the paper also discusses processing cost issues in terms of the process yields and operational strategies. The use of powder metallurgy will also be reviewed as a cost effective alternative to alloys that have traditionally been cast-wrought processed.
Improving the Oxidation Resistance of Fe-Cr-Mn Interconnector of Solid Oxide Electrolyte Fuel Cell with the Addition of Trace Elements
Authors: Wang W.S. , Lian Shuang Shii , Chen C. , Tsai K.C. , Shong W.J. , Lee R.Y.
Published: October 2010

Fe-Cr-Mn alloy is a common material used for the metallic interconnector of solid oxide electrolyte fuel cells (SOFC). However, its high temperature oxidation resistance needs to be strengthened to improve the performance of SOFC. In this study, the effect of trace additions of Ti, Mo, Co and La on the high-temperature behavior of Fe-Cr-Mn alloy was investigated. The composition of Fe-22Cr-2Mn-X (X = Ti, Mo, Co, La) alloys was designed to maintain a bcc structure with the aid of the thermal-calc software. These alloys tended to form Cr-rich oxide in the inner layer and Mn-rich oxide in the outer layer of the specimens after oxidative tests at 850°C, thus reducing the likelihood of chromium oxide evaporation. The experimental results indicated that the addition of Co and La produced better oxidation resistance at high temperatures than Ti and Mo. In addition, the influence of trace elements on electrical resistance of the interconnector material was examined as well.
High Temperature - FTIR Characterization of Gadolinia Doped Ceria
Authors: Arabaci Aliye , Solak Nuri
Published: October 2010

Doped ceria-based (DC) materials have recently been considered as the most promising solid electrolytes for intermediate temperature solid oxide fuel cell (IT-SOFC) applications. Doped ceria is usually prepared via thermal decomposition of its water soluble salts, especially, acetates and nitrates. The properties of the obtained final product directly influenced by the starting material and the decomposition products. Therefore, it is crucial to understand the decomposition steps and intermediate products. Number of experimental work have been reported using various in-situ and ex-situ techniques such as thermogravimetry with mass spectrometry (TG/DTA-MS), X-ray diffraction with differential scanning calorimeter (XRD-DSC). However, the available literature data is limited and not reasonably in agreement with each other. High Temperature FT-IR spectroscopy, TG/DTA-MS, XRD, techniques were used and results are compared with literature. A good agreement between the thermal analyses and HT-FTIR results were obtained. Possible decomposition mechanism is discussed.
Fine Controlled Metallodendrimers for Advanced Nano-Catalysts
Authors: Yamamoto Kimihisa
Published: October 2010

Dendrimers are highly branched organic macromolecules with successive layers or “generations” of branch units surrounding a central core. We show that tinchlorides complexes to the imines groups of a spherical polyphenylazomethine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. By further extending this strategy, it should be possible to control the number and location of metalchlorides incorporated into dendrimers for advanced nano-materials, such as nano-catalysts.
Status and Challenges of Molten Carbonate Fuel Cells
Authors: McPhail Stephen J.
Published: October 2010

By analogy with the development of nuclear power and photovoltaics, the position of MCFC technology is evaluated in the context of today’s energy supply. A brief review is presented of the technical status of MCFC materials and challenges left open. At system level, a number of more or less niche applications prove to be promising for approaching early markets and an update is given of some important figures on construction and deployment of MCFC systems worldwide.
Study of Carbon Nanotubes for Lithium-Ion Batteries Application
Authors: Varzi Alberto , Täubert Corina , Wohlfahrt-Mehrens Margret , Kreis Martin , Schütz Walter
Published: October 2010

The potential use of multi-walled carbon nanotubes (MWCNTs) produced by chemical vapour deposition (CVD) as a conductive agent for electrodes in Li-ion batteries has been investigated. LiNi0.33Co0.33Mn0.33O2 (NCM) has been chosen as active material for positive electrodes, and a nano-sized TiO2-rutile for the negative electrodes. The electrochemical performances of the electrodes were studied by galvanostatic techniques and especially the influence of the nanotubes on the rate capability and cycling stability has been evaluated. The addition of MWCNTs significantly enhanced the rate performances of both positive and negative electrodes and improved the capacity retention upon cycling. The obtained results demonstrated that the addition of MWCNTs in low amounts to the electrode composition enables an increase in both energy and power density of a Li-ion battery.
Sago Gel Polymer Electrolyte for Zinc-Air Battery
Authors: Masri M.N. , Nazeri M.F.M. , Mohamad A.A.
Published: October 2010

A sago-based gel polymer electrolyte (GPE) was prepared by mixing native
sago with potassium hydroxide (KOH) aqueous in order to investigate the applicability of
GPE to zinc-air (Zn-air) battery. The viscosity and conductivity of the sago GPE were
evaluated using varying sago amounts and KOH concentrations. The viscosity of the sago
GPE was kept as a reserve in the region of ~ 0.2 Pa s as the KOH concentration was
increased from 2 to 8 M. Sago GPE was found to have an excellent ionic conductivity of
(4.45  0.1) x 10-1 S cm-1 with 6 M KOH. GPE was also employed in an experimental Znair
battery using porous Zn electrode as the anode. The battery shows outstanding
discharge capacity and practical capacity obtained of 505 mA h g-1.
Ionic Liquid Binary Mixtures for Low Temperature Applications
Authors: Appetecchi Giovanni Battista , Montanino Maria , Carewska Maria , Alessandrini Fabrizio , Passerini Stefano
Published: October 2010

The thermal and transport properties of PYR1(2O1)TFSI-PYR13FSI ionic liquid binary mixtures as electrolytes for low temperature electrochemical devices are reported in the present paper. The DSC measurements are in good agreement with the conductivity results. It is shown that the incorporation of even small mole fractions (x  0.3) of PYR1(2O1)TFSI into PYR13FSI strongly hinders the ability of the samples to crystallize. This results in a very large conductivity enhancement for the PYR1(2O1)TFSI-PYR13FSI binary mixtures, particularly at low temperatures, that were seen to approach conduction values of 10-4 Scm-1 and 10-3 Scm-1 at -40°C and -20°C, respectively. Such an interesting behavior makes PYR1(2O1)TFSI-PYR13FSI binary mixtures particularly appealing for low temperature applications.
A Molecular Dynamics Study on Pressure Dependence of Ag Diffusion in Ag3SI
Authors: Yarimitsu Masakazu , Aniya Masaru
Published: October 2010

The pressure dependence of the diffusion coefficient in the superionic α- and β-phases of Ag3SI has been studied by using the method of molecular dynamics. It is shown that in the high temperature α-phase, the Ag diffusion coefficient decreases with pressure. On the hand, in the intermediate temperature β-phase, the Ag diffusion coefficient exhibits a maximum at around 2.8 GPa. The structural origin of this behavior is discussed through the pressure dependence of the pair distribution functions.
Hydrogen Uptake and Hydrogen Profiles in Chromia Scales Formed on Ni25Cr(Mn) in Low pO2 Test Gases at 1000°C
Authors: Hänsel Michael , Garcia-Fresnillo Laura , Tobing Stefanus Luman , Breuer Uwe , Shemet Vladimir
Published: October 2010

Two chromia forming materials have been exposed to different test gases at low pO2. All used test gases contained hydrogen species in the form of molecular hydrogen and water vapour. To insure the validity of the measured H-profiles H2 was replaced by with D2 and H2O by D2O. The Deuterium profiles in the oxides formed were established using SIMS and GDOES techniques. The profiles were quantified and correlated with the growth rate and the microstructures of the chromia scales formed on in low pO2 test gases. The presence of H2/H2O in the low pO2 test gas alters the properties of thermally growing chromia scales.
Influence of the Microstructure on the U1-yAmyO2-x (y= 0.1; 0.15) Pellet Macroscopic Swelling
Authors: Prieur Damien , Jankowiak Aurélien , Leorier Caroline , Herlet Nathalie , Donnet Louis , Dehaudt Philippe , Lechelle Jacques , Laval Jean Paul , Blanchart Philippe
Published: October 2010

This work is devoted to the study of the geometrical stability in time of UyAm1-yO2-x pellet due to self-irradiation at room temperature. Dense and tailored porosity U1-yAmyO2-x (y=0.10; 0.15) compounds were fabricated by a powder metallurgy process. Up to 3.4.1017 α particles/g, an increase in the diameter of 0.9% was observed for the dense compounds while for the tailored porosity material a diameter increase of 0.4% was observed. Swelling laws have been established from the experimental data.
Advantages Hot Isostatically Pressed Ceramic and Glass-Ceramic Waste Forms Bring to the Immobilization of Challenging Intermediate- and High-Level Nuclear Wastes
Authors: Vance Eric R. , Moricca S. , Begg Bruce D. , Stewart M.W.A. , Zhang Y. , Carter M.L.
Published: October 2010

Hot isostatic pressing (HIP) is a technology with wide applicability in consolidating calcined intermediate-level and high-level nuclear waste, especially with wastes that are not able to be readily processed by vitrification at reasonable waste loadings. The essential process steps during the HIP cycle will be outlined. We have demonstrated the effective consolidation via HIP technology of a wide variety of tailored glass-ceramic and ceramic waste forms, notably simulated ICPP waste calcines, I sorbed upon zeolite beads, Pu-bearing wastes, inactive Cs/Sr/Rb/Ba mixtures, simulated waste pyroprocessing salts from spent nuclear fuel recycling, Tc, U-rich isotope production waste, and simulated K-basin (Hanford, WA, USA) and Magnox sludges (UK). Can-ceramic interactions have been carefully studied. The principal advantages of the HIP technology include: negligible offgas during the high temperature consolidation step, relatively small footprint, and high waste loadings. As a batch process, the wasteform chemistry can be readily adjusted on a given process line, to deliver wastes into different end states (e.g. direct HIP versus chemically tailored). This flexibility allows the treatment of multiple waste streams on the one process line.
Multiscale Modelling of the Influence of Damage on the Thermal Properties of Ceramic Matrix Composites
Authors: El Yagoubi Jalal , Lamon Jacques , Batsale Jean Christophe
Published: October 2010

Ceramic matrix composites (CMC) are very attractive materials for structural applications at high temperatures. Not only must CMC be damage tolerant, but they must also allow thermal management. For this purpose heat transfers must be controlled even in the presence of damage. Damage consists in multiple cracks that form in the matrix and ultimately in the fibers, when the stresses exceed the proportional limit. Therefore the thermal conductivity dependence on applied load is a factor of primary importance for the design of CMC components. This original approach combines a model of matrix cracking with a model of heat transfer through an elementary cracked volume element containing matrix crack and an interfacial crack. It was applied to 1D composites subject to tensile ant thermal loading parallel to fiber direction in a previous paper. The present paper compares predictions to experimental results.
Adhesion and Barrier Properties Analysis of Silica-Like Thin Layer on Polyethylene Naphthalate Substrates for Thin Film Solar Cells
Authors: Addonizio Maria Luisa , Fusco Luigi
Published: October 2010

In this investigation the surface properties optimisation of a flexible PEN foil to use as substrate for thin film silicon solar cells is presented. The polymer surface, usually hydrophobic and inactive to chemical reactions, can give poor adhesion for films deposited on it. Furthermore, gas desorption from the polymer sometimes causes serious problems to the quality of the devices. To overcome these problems a thin film of silica-like functional material has been developed on polymer foil. Silica-like films were produced by sol-gel process starting from an organic silanes compound (APTMS) as precursor and the solution was deposited by spin-coating. Amorphous silica-like films were obtained with a hydrophilic surface. They were smooth, dense, homogeneous, transparent and exhibited an excellent adhesion to the polymer substrate due to the chemical bond between amine groups of the APTMS with carbonyl bonds in PEN. Physical properties such as elastic modulus and hardness and the UV irradiation effect on structure and surface hydrophilicity of the silica-like coatings have been analysed. A water contact angle of 34° was obtained after UV irradiation. Nanoindentation analysis showed that the silica-like coating have an hardness and an elastic modulus up to 2.0 GPa and 13.2 GPa respectively much higher than that of pure PEN. Oxygen permeability measured on silica-like coated PEN gave a value of 5.7 x 10-9 cc m/m2 s atm showing larger barrier properties respect to pure PEN. Strong adhesion, improved mechanical properties and barrier effect of our silica-like coating make the modified PEN substrate suitable to be used in thin film solar cell technology.
Quantum Size Effects in a Si:H Films Prepared by PECVD with Different Hydrogen-Diluted Silane
Authors: Prušaková Lucie , Vavruňková V. , Netrvalová M. , Müllerová J. , Šutta P.
Published: October 2010

Quantum size effect (QSE) comprises a novel phenomenon where structural, mechanical, thermal, electronic and optical properties of solids are affected by the reduction in particle size. Size-dependent properties in semiconductors and dielectrics come into play especially by making one (thin films) or more (quantum wires and dots) dimensions of a sample very small, particularly going from micro to nano-dimensions. One or more dimensional QSE is accompanied with an increase of the light absorption and the blue-shift of the optical band-gap due to a creation or reduction of the crystallite sizes having different dielectric constants (relative permitivity). Understanding the nature of the size-induced properties is of fundamental importance for advanced technological applications. The size-dependent band-gap makes a material attractive for optical absorption-based applications. In this work, a-Si:H films different in thickness were prepared by PECVD technology using different hydrogen-diluted silane. One-dimensional QSE (when film thickness decreased) and three-dimensional QSE (when due to a high hydrogen-silane dilution the nano-crystalline structure of the films appeared) were observed.
Intermediate Band Solar Cells
Authors: Martí Antonio , Luque Antonio
Published: October 2010

Intermediate band (IB) solar cells aim to exploit in solar cells the energy of below bandgap energy photons. They are based in a material that, in addition to the conventional conduction and valence bands, has an electronic band (named intermediate band) located inside the bandgap and separated from the conduction and valence band by a null density of states. The theoretical limiting efficiency of these cells (63.2 % at maximum concentration) is equivalent to a triple junction solar cell but requiring a single material instead. Several approaches are being followed worldwide to take to practice this concept that can be divided into two categories: quantum dots and bulk materials. This paper reviews the main experimental results obtained under both approaches.
The Influence of the Fullerene on the Optical Constants of the Photoactive Blend Film of a Polymer Solar Cell
Authors: Morvillo Pasquale , Bobeico Eugenia , Esposito Salvatore
Published: October 2010

The short circuit current density (Jsc) of polymer solar cells is strictly related to the absorption of the blend film. Recently it has been shown that the use of [70]PCBM as electron acceptor can improve the current output of such devices because C70 derivatives have a stronger and broader absorption compared to C60 ones. The aim of this work is to study the influence of the fullerene on the optical behaviour of the photoactive blend film of a polymer solar cell. We have determined the optical constants of a P3HT:[70]PCBM blend film and studied their variation as a function of the annealing temperature. Afterward, we simulated the optical absorption of the active layer inside the device structure and calculated the maximum achievable Jsc with the aim to correlate the variation of the optical constants to the device output current. We compared this value with that one obtained using a P3HT:[60]PCBM blend.
Improved Concentration Capabilities of Flat-Plate Fresnel Lenses
Authors: Shvarts Maxim Z. , Soluyanov Andrey A.
Published: October 2010

This paper presents an experience in designing, manufacturing and testing the Fresnel lenses (FLs) for sunlight concentration in photovoltaic modules with multi-junction solar cells (SCs). A power ray tracing model is used for calculating and optimizing refractive profile parameters and obtaining optical-power characteristics (OPCs) of Fresnel lenses. In searching the optimum combination of the lens aperture, its focal distance and profile configuration, the optimization criterion was the maximum of the average sunlight concentration at high optical efficiency in the focal spot of minimum size. Analysis of characteristics of circular Fresnel lenses with conical (the facet generating lines are straight ones) and curvilinear (the facet generating lines are curved ones) refracting surfaces has been carried out. The effect material parameters on the lens optical efficiency were studied. Molds for Fresnel lens formation and experimental specimens were fabricated and a control of their profile parameters has been done. A degree of the effect of the light flux characteristics and Fresnel lens geometrical imperfections on validity of the experimental data interpretation has been examined. The correction procedure have been applied in the calculation model to establish the lens optical efficiency values at standard irradiance conditions.
Optical Methods for Indoor Characterization of Small-Size Solar Concentrators Prototypes
Authors: Parretta Antonio , Antonini Andrea , Butturi Maria Angela , Milan Emiliano , Di Benedetto Pierangelo , Uderzo Davide , Zurru Paolo
Published: October 2010

The light collection properties of different types of solar concentrators have been investigated by applying conventional and innovative methods of characterization [1, 2]. Four types of optical methods were applied: i) a “direct” method using a laser beam as light source; ii) a “direct” method using a parallel beam simulating the direct component of solar light; iii) a “direct” integral method using a lambertian light source simulating the diffuse component of solar light; iv) an “inverse” method using a lambertian light source applied at the receiver side, thereby reversing the light path. The optical properties derived by applying the above three methods were: i) the local optical collection efficiency, resolved on the entrance point and direction of incidence ii) the overall optical collection efficiency under collimated light, resolved on direction of incidence; iii) the spatial and angular distribution of flux on the receiver.
Assessment of a Phase Change Material (PCM) System for Moderating Temperature Rise of Solar Cells under Concentrated Sunlight
Authors: Casenove Eric , Pujol Loic , Vossier Alexis , Perona Arnaud , Goetz Vincent , Dollet Alain
Published: October 2010

Experiments and simulations were carried out to assess a passive device for cooling photovoltaic cells under concentrated sunlight. The cooling device was made of a Graphite- Phase Change Material (PCM) composite inserted in an aluminum enclosure. The PCM considered in this work was selected among several commercially available materials. Experimental plots of material temperature versus time were recorded for various incident solar powers and compared to 3D-thermal simulation predictions. Theoretical cell temperature profiles obtained using the PCM-based device were compared to those obtained without PCM, that is, using bulk (PCM-free) aluminum heat sink. The interest of using PCM cooling systems in CPV applications was finally discussed.
Effect of Cobalt-Substitution on the Structure and Thermoelectric Properties of Chimney-Ladder Solid Solution (Mn1-xCox)Siγ (γ~ 1.7)
Authors: Miyazaki Yuzuru , Saito Yoshitsugu , Hayashi Kei , Yubuta Kunio , Kajitani Tsuyoshi
Published: October 2010

A partially cobalt-substituted solid solution of Nowotny chimney-ladder phase,
(Mn1-xCox)Si, has been prepared using a tetra-arc-type furnace and a subsequent annealing process.
The compounds consist of two tetragonal subsystems of [Mn1-xCox] and [Si], with an irrational
c-axis ratio = cMn/cSi ~ 1.7. The crystal structure and thermoelectric properties of (Mn1-xCox)Si
solid solution were compared with those of the Fe-substituted solid solution, (Mn1-xFex)Si. In the
case of Co-series, extra valence electrons are introduced relative to Fe-series, since the valence
electron count is 3d74s2 for Co but 3d64s2 for Fe, respectively. It was naturally expected that the Feand
Co-substituted MnSi becomes n-type conductor from the p-type one at x > 0.23(5) and x >
0.06(1), respectively. Experimentally, the Fe-substituted samples become n-type at x > 0.28 but it
is not the case for the Co-substituted ones. It is thus evident that there is an unknown factor which
controls the thermoelectric properties of Co-substituted samples.
Improvement of Radiation Resistance of Multijunction GaInP/Ga(In)As/Ge Solar Cells with Application of Bragg Reflectors
Authors: Lantratov Vladimir M. , Emelyanov Viktor M. , Kalyuzhnyy Nikolay A. , Mintairov Sergey A. , Shvarts Maxim Z.
Published: October 2010

Feasibility to increase the radiation resistance of multijunction solar cells in using Bragg reflectors has been shown. Two designs of Bragg reflectors for multijunction solar cells, which allow ensuring in the Ga(In)As subcell base an effective collection of minority charge carriers at the decrease of their diffusion length caused by radiation treatment, have been investigated. Influence of subcells’ thicknesses of n-p GaInP/Ga(In)As/Ge solar cell under 1 MeV electron irradiation with fluences up to 3•1015 cm–2 on short circuit current was considered. Optimal thicknesses of GaInP and GaInAs subcells with Bragg reflectors, depending on the rated operation period on the geostationary orbit, were estimated. It has been shown that such an optimization allows to achieve efficiency at long operation of solar cells on the orbit noticeably higher than that of non-optimized cells.
On-Sun Performance of FLATCON® CPV Systems
Authors: Gombert Andreas , Heile Inka , Wüllner Johannes , Gerstmaier Tobias , van Riesen Sascha , Gerster Eckart , Röttger Michael
Published: October 2010

Concentrating photovoltaic (CPV) systems based on III-V semiconductors entered the photovoltaic market recently. Concentrix Solar deploys the FLATCON® CPV module technology originally developed at the Fraunhofer Institute for Solar Energy Systems ISE. This paper gives a short introduction in design considerations of FLATCON CPV module and provides detailed field data of the system technology over up to two years are presented as well as field experiences with the operation of the systems. FLATCON modules are based on III-V triple junction cells, a Fresnel lens array, and a glass cover and bottom plate. In 2008, Concentrix installed a single tracker system and two power plants in Spain. A system solar-to-grid AC energy efficiency of 21% over the whole period of two years with maximum system AC power efficiency values of 23% for a single tracker system are shown. Similar systems installed in 2009 and equipped with the current FLATCON module CX-75 achieved system AC power efficiencies of 25%. The effects of spectral variations of the solar irradiation on power plant performance are discussed.
Thermoelectric Properties of the Heavy Element Doped Heusler Fe2VAl Alloy Prepared by Powder Metallurgy Technique
Authors: Mikami Masashi , Kobayashi Keizo , Tanaka Suguru
Published: October 2010

Sb-doped Heusler Fe2VAl alloy was synthesized to evaluate the effect of heavy element doping on thermoelectric properties of the Heusler alloy. For the sample preparation, a pulse-current sintering technique with fine powder prepared by mechanical alloying was used. By using the powder metallurgy technique, a heavy element with a low melting point can be stably doped, compared to the melting process. Thermal conductivity was effectively-reduced by a small amount of the substitution because of the large atomic mass of Sb compared to the constituent elements of Fe2VAl alloy. Conduction type was controlled by adjusting the valence electron density. For the p-type conduction, Ti substitution for the V site was examined and large positive Seebeck coefficient was obtained while maintaining the low thermal conductivity.
The Evaluation of TiTe2 as a Diffusion Barrier in the Formation of Low Thermal Conductivity Nanolaminates with Bi2Te3 and Sb2Te3
Authors: Mortensen Clay , Zschack Paul , Johnson David C.
Published: October 2010

The evolution of designed [(Ti-Te)]x[(Sb-Te)]y, [(Bi-Te)]x[(Sb-Te)]y, [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]y and [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors were followed as a function of annealing temperature and time using both low and high angle x-ray diffraction techniques to probe the self assembly into nanolaminate materials. The [(Bi-Te)]x[(Sb-Te)]y precursors were found to interdiffuse at low temperatures to form a (BixSb1-x)2Te3 alloy. The [(Ti-Te)]x[(Bi-Te)]y and [(Ti-Te)]x[(Sb-Te)]y precursors formed ordered nanolaminates [{(TiTe2)}1.35]x[Bi2Te3]y and [{(TiTe2)}1.35]x[Sb2Te3]y respectively. The [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]x precursors formed [{(TiTe2)}1.35]w[(Bi0.5Sb0.5)2Te3]2x nanolaminates on annealing, as the bismuth and antimony layers interdiffused. Over the range of TiTe2 thicknesses used in [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors, Bi and Sb were found to interdiffuse through the 2-4 nm thick Ti-Te layers, resulting in the formation of (BixSb1-x)2Te3 alloy layers as part of the final nanolaminated products. When the Bi-Te and Sb-Te thicknesses were equal in the amorphous precursors, symmetric [{(TiTe2)}1.35]m[(Bi0.5Sb0.5)2Te3]n nanolamiantes were formed. When the thicknesses of Bi-Te and Sb-Te layers were not equal in the amorphous precursor, asymmetric [(TiTe2)1.35]m[(BixSb1-x)2Te3]n[(TiTe2)1.35]m[(BixSb1-x)2Te3]p nanolaminates were formed. These results imply that to form (A)w(B)x(C)y nanolaminates using designed layered precursors all three components must be immiscible. To form (A)x(B)y(A)x(C)z nanolaminates, the components must be immiscible or the precursor to the A component and the A component itself must be an effective interdiffusion barrier preventing B and C from mixing.