bluuebunny/crossref_metadata_2025 huggingface dataset:
Saccharides Derivatives in Shaping of Ceramic Powders – New Monomers and Dispersants
Authors: Bednarek Paulina , Szafran Mikolaj , Mizerski Tadeusz
Published: October 2010

Saccharides, particularly monosaccharides, as well as their derivatives, were found to be
a group of effectively working processing agents in case of alumina which has been used as a solid
phase of highly loaded suspensions. The synthesis of new low-toxic monomers obtained from
saccharides is reported and their application in gelcasting process is presented. The synthesized
monomer named 3-O-acrylic-D-glucose is an interesting alternative for the commercially available
acrylic monomers. The present paper describes the properties of ceramic slurries obtained from two
alumina powders of different grain size (47nm and 0.70mm) with the use of the new monomer
3-O-acrylic-D-glucose. The rheological measurements showed that new monomer can be applied
not only as monomer able to polymerize in situ but also as dispersing agent for nanoalumina
powders.
Production of Nanopowders with the Help of Fiber Laser
Authors: Ivanov Maxim , Kotov Yuriy , Samatov Oleg , Timoshenkova Olga , Demina Tatiana
Published: October 2010

Development of an efficient technology to produce nanopowders for nanostructured materials with improved mechanical, novel electromagnetic and optical properties is still of current importance. Nanoparticles can be made by means of laser-assisted material evaporation and subsequent vapor condensation. The method provides high-purity weakly agglomerated nanopowders with narrow grain size distribution, and can be applied to various materials. However, up to these days this technique has not found wide recognition because of a low output rate and high energy consumption. This report deals with the production technology and characteristics of nanopowders produced with the help of Yb-doped fiber laser. Data for the nanopowders characteristics, as well as output rate and energy consumption are discussed in this paper. The evaporation of materials with the help of the fiber laser was proved to be an efficient method for commercial production of the fine nanopowders.
Microstructural Tailoring of YAG and YAG-Containing Nanoceramics through Advanced Synthesis Routes
Authors: Palmero Paola
Published: October 2010

Wet-chemical syntheses have been applied to the production of ceramic powders, with the aim of tailoring compositional and micro/nanostructural features, as an imperative requirement toward the elaboration of ceramic components with improved functional or even structural properties. Three syntheses are here presented and discussed, respectively concerning a purephased, nanostructured YAG powder, a biphasic Al2O3-YAG composite and three-phased Al2O3- YAG-ZrO2 material. In particular, this paper is aimed to illustrate the path followed from the set-up of the easier synthesis of the mono-phased system to the definition of the advanced procedures for the production of more and more complex compositions.
Lightweight Hybrid Foam with Dimensional Stability
Authors: Chen Ming Yung , Chen Cheng Gang
Published: October 2010

Availability of advanced materials has opened up opportunities in meeting several
functional requirements through hybridization. Hybrids consisting of ceramics, metals and high
performance polymers could benefit many aircraft and space satellite applications. They could
meet requirements of low weight, high environmental stability, and high thermal or dimensional
stability. In this study, hybrid materials consisting of high performance polymer, porous
ceramics (glass microballoons) and other constituents such as Zircornium Tungstate (with
negative coefficient of thermal expansion (CTE)) and nanoclay were studied. Specimens were
successfully produced with a range of density from 0.4 to 1.1 g/cm3 depending on the degree of
fill in the syntactic foams. CTE tailoring was achieved to greatly reduce the residual stress
arising from processing and CTE mismatch of dissimilar materials. The evaluations of
dimensional stability were examined from thermomechanical analysis. The synergistic effects of
resin, ceramic constituents and pores on the hybrid properties will be presented.
Heterogeneous Sol-Gel Systems – Derived Ceramics
Authors: Shilova Olga A.
Published: October 2010

Heterogeneous sol-gel systems (suspensions), synthesized by mixing sols and fillers of various dispersity (oxides, minerals, etc.), are successfully used to prepare glass-ceramic coatings. Sol composition (precursor, catalyst, solvent, dopants), filler dispersity and a homogenization mode for obtained suspensions essentially influence the properties of coatings formed. Here ways of the control of properties of heterogeneous sol-gel systems (by using various dopants, additives of organic low- and high-molecular compounds, as well as ultrasound) to reach set electro-physical and mechanical characteristics of coatings are considered in details. A number of examples of applications of glass-ceramic and hybrid coatings as well as ‘skin’ - layers are resulted.
New Methodology in Modeling Ceramics
Authors: Algatti Mauricio A. , Ferreira de Lucena Emerson , de Campos Élson , Mota Rogério Pinto , Santana Jerusa Góes Aragão
Published: October 2010

The improvement of ceramic synthesis and processing methodology based on digital image processing and analysis of ceramic samples is in its initial stage. The main reason is that the models are based on poorly obtained data from sample’s digital image processing. The lack of a solid statistical analysis and digital-imaging setup standardization make the method less useful that it should be if set in a sound basis. Therefore the importance of setting a new methodology in digital image processing for data acquisition on ceramic morphology analysis is essential for setting new models for customized ceramic synthesis and processing. The present paper shows results based on Scanning Electron Microscopy (SEM) from Al2O3 ceramics obtained by starch consolidation method. Observation of different sample’s regions allowed a more accurate description of ceramic morphology. Plots of resistance to flexion versus porosity and its correlation with the grain size and shape allowed one to choose the best model for representing ceramic’s morphology. Correlation of starch percentage with sample’s porosity and mechanical resistance allowed the best experimental conditions for customized ceramic’s performance.
Fabrication of Porous Silicon Nitride by Sacrificing Template Method
Authors: Mesquita Rodrigo Mende , Bressiani Ana Helena Almeida
Published: October 2010

High performance porous structural ceramics have been widely studied. Silicon nitride is an interesting material for this application because bodies with high mechanical strength, achieved as a result of “in situ” anisotropic grain grown, can be obtained. In this study, Si3N4 bodies with different porosity related aspects (percentage, morphology, etc.) are made using the sacrificing template method, by changing the percentage (vol%) and the drying method of the mixture as well as the sintering time. The porosity, apparent density (Archimedes method), microstructure (SEM) and the mechanical strength (in compression) of these bodies were determined. It was thus possible to relate the type and amount of starch with the porosity and mechanical properties of the bodies.
Use of Electrothermal Explosion and Electro-Thermal Analyser (ETA-100) for the Study the Kinetics of Fast High-Temperature Reactions in SHS-Ceramic Systems
Authors: Shteinberg A.S. , Berlin A.A.
Published: October 2010

Due to the lack of specialty kinetic methods and instruments, the kinetics of fast hightemperature
reactions SHS-ceramic systems has not been adequately studied. Recently, we have
developed a number of methods of so-called non-isothermal kinetics (NIK) and designed
instruments allowing one to obtain information about reactions of ceramic systems in a wide
range of practically important temperatures and rates. The use of one of the NIK-methods
(called electrothermal analysis based on the phenomena of electro thermal explosion) allows
one to study kinetics of SHS of some ceramic materials characterized by the total reaction time
~ 10 μs. In ETE, both samples pressed from reagents powders or cylindrical samples made from
tightly rolled foils were studied. The joule heating was accompanied by high-speed scanning of
the non-stationary temperature field on its surface. Description and technical characteristics of
the specialty device electrothermoanalyzer ETA-100 manufactured by ALOFT are given.
Kinetic parameters of fast EM reactions for the temperatures up to 3600 K can be measured by
ETE method using ETA-100. New kinetic data for fast high-temperature gasless SHS yielding
individual and composite materials (including refractory carbides and borides of transition
metals, silicon and boron carbides, some refractory oxides and hard alloys) are presented. At
high-speed impact of the samples, the reaction rate constants were found to exceed the
combustion rate constants (measured by ETA-100) by many orders of magnitude. It was
concluded that the kinetic mechanisms of the corresponding fast reactions in the static
conditions and under the impact are dramatically different. It was shown that SHS in ETE mode
has a significant potential as a modern practical method to be used for welding of refractory and
dissimilar materials, production of coarse superabrasives, etc.
Past and Current Accomplishments in Production of Ceramic Powders and Structures by Self-Propagating High-Temperature Synthesis Method
Authors: Puszynski Jan A. , Degraw Alan
Published: October 2010

A comprehensive review of both past and current world-wide accomplishments in the area of combustion synthesis, with special emphasis on the production of oxide and nonoxide ceramic powders, is presented. This review focuses on scale-up and production initiatives undertaken by international companies and institutions. A significant part of this review is dedicated to manufacturing of dense and porous structures involving combination of self-propagating high-temperature technique with other processing methods. Finally, new initiatives and challenges associated with this novel synthesis technique are discussed.
Synthesis of Alumina and Aluminum Nitride Layers on a Graphitic Substrate via a Sol-Gel Route
Authors: Fontaine Florian , Pailler René , Guette Alain
Published: October 2010

In this study, our objective is to deposit an alumina or an aluminum nitride layer on a turbostratic carbon substrate. The coatings are synthesized via a sol-gel route followed by a heat treatment in order to obtain -alumina or hexagonal aluminum nitride by carbothermal nitridation of alumina. The synthesis of such layers on carbon substrates is not reported in literature.
Several slurries were elaborated using various solvents and catalysts, and aluminum-tri-sec-butoxide as an aluminum precursor. The coating is obtained by dropping the substrate in the sol. After drying and pyrolysis, the amorphous alumina layer obtained has a thickness ranging from 500 nm to 1 µm. The material is finally heat treated. Several treatment conditions were evaluated.
A thermodynamic study of the Al-C-O-N system will be drawn, and the composition of the synthesized sol-gel and heat treatment parameters will be detailed. Then, the layer’s morphology and structure will be characterized thanks to Scanning Electron Microscopy and X-Ray Diffraction analyses. The impact of heat treatment parameters will be discussed and experimental results will be compared to the theoretical thermodynamic results.
Porous SHS-Ceramics
Authors: Maksimov Yu.M. , Kirdyashkin A.I. , Baev Vladimir K. , Gushin Aleksandr N.
Published: October 2010

In the work, interrelations between morphology of porous metalloceramics and thermal modes of SHS wave have been revealed on the basis of complex investigations including high-speed microvideo filming and dynamic pyrometry of processes, the physical and chemical analysis of products by the example of various intermetallic and hybrid (Ni, Co, Сr-Al, Ti-B-Cu, Ti-Si), metallothermic (FeTiO3-Al, Si, C; FeO-Al2O3-MgO-Al, etc.) systems.
SHS Refractory Materials “Furnon” and their Practical Implementations in Kazakhstan and Russia
Authors: Mansurov Zulkhair A.
Published: October 2010

The work deals with the review, analysis, systematization and classification SHS- refractories of a «Furnon» class are. The chronology of researches, introduction into industry are given, economic feasibility of their application in industries are shown. Comparative characteristics and distinctions of SHS- refractories with classical refractory are given. Current status, prospects and possible fields of using refractories produced by SHS method are considered.
Comparison of Microwave and Conventional Sintering of LHA Ceramics and Functionally Graded Alumina-LHA Ceramics
Authors: Negahdari Zahra , Willert-Porada Monika
Published: October 2010

The low thermal conductivity of Lanthanum hexaaluminate, abbreviated as LHA,
combined with high structural reliability of alumina matrix ceramics attracted our attention to
develop a new functionally graded layered LHA-Al2O3-composite, with a LHA and a porosity
gradient along the thickness of a bulk oxide ceramic. LHA is formed by in–situ reaction during
sintering of the alumina/LHA composite. The high sintering temperature required for completion of
LHA formation in LHA-rich layers causes grain growth and a degradation of mechanical strength in
alumina-rich layers. Therefore, microwave hybrid heating was investigated as a method to enhance
the reaction rate without excessive grain growth. Comparison of conventionally and microwave
assisted sintered homogenous composite ceramics with 20–80 volume percent LHA showed that
utilization of microwave heating could enhance the solid–state reaction and densification in samples
containing more than 20 volume percent LHA. Enhanced microwave absorption in LHA rich layers
assisted the sintering of a functionally graded composite at lower temperatures, enabling LHA
formation without any abnormal grain growth in alumina rich layers.
Effects of Strain-Graded Plastic Deformation on Mechanical Properties of Metals
Authors: Matsuura Kiyotaka , Ohno Munekazu
Published: October 2010

In a flow forming process of automobile wheels of Al-based alloys, plastic deformation of the rim part is performed by rollers from the periphery side, while the inner periphery is fixed on a steel mandrel and is slightly deformed. Therefore, the rim part has a strain-graded microstructure in the thickness direction. In this study, the effects of the strain-graded plastic deformation on mechanical properties of an Al-Si cast alloy have been investigated. The strain-graded plastic deformation in this study was done by hot rolling of an Al alloy plate together with a steel plate. The two plates were joined at one end in the longitudinal direction and were rolled from the joined edge at 330 oC using a roller with a roll diameter of 200 mm and a rotation speed of 66 per minute. The chemical composition of the alloy was Al-7mass%Si-0.3mass%Mg-0.3mass%Fe. The rolled Al alloy plate had a strain-graded microstructure in the thickness direction; the strain was the highest at the roller side surface and the lowest at the steel plate side surface. The rolling also brought about a Si particle size graded microstructure. The eutectic Si rods were broken by the rolling deformation and the Si particle size was the smallest at the roller side surface and the largest at the steel plate side surface. On the other hand, a normal rolling deformation of the Al alloy plate without the steel plate was also performed for comparison. The rolled sample having the strain-graded and Si particle size graded microstructure exhibited much　more excellent bending strength and ductility compared with the normally rolled sample.
Defect Crystal Structure of Low Temperature Modifications of Li2MO3 (M=Ti, Sn) and Related Hydroxides
Authors: Tarakina Nadezda V. , Denisova Tatiana A. , Baklanova Yana V. , Maksimova Lidia G. , Zubkov Vladimir G. , Neder Reinhard B.
Published: October 2010

Crystal structures of Li2MO3 (M=Sn, Ti) and TiO(OH)2 have been studied in detail and
refined using X-ray powder diffraction data. All compounds posses a high concentration of defects
in the structure. The crystal structures of the Li2MO3 salts obtained at 700°C reveal stacking faults
of LiM2 metal layers, which leads to the appearance of short-range order in three possible space
groups: C2/c, C2/m, P3112. The possibility to stabilize this imperfect state increases the mobility of
the Li+ ions in the Li2TiO3 structure and allows the complete exchange of lithium by hydrogen in
acid water solutions with formation of TiO(OH)2. The crystal structure of TiO(OH)2 belongs to the
layered double hydroxide structure type with the 3R1 sequence of oxygen layers and can be
described as a stacking of charge-neutral metal oxyhydroxide slabs [(OH)2OTi2O(OH)2].
Co-Doping Effect of Metal Ion on the Visible Light Responsive Photocatalytic Properties of Nitrogen Doped Titanium Dioxide
Authors: Zhang Pei Lin , Yin Shu , Sato Tsugio
Published: October 2010

Different valences of metal ions such as Fe3+ and Nb5+ were co-doped with nitrogen ion
into titanium dioxide by hydrothermal method using metal chlorides and hexamethylenetetramine
as the sources of metal ions and nitrogen ion, respectively. The co-doping of low-content metal ion
showed no noticeable influence on the crystalline phases and specific surface area (S.S.A.) of the
samples. Doping with Fe ion could significantly enhance the absorption in visible light region, but
doping with Nb ion showed almost no effect. The photocatalytic activities of the samples were
determined for the oxidative destruction of NO gas under various wavelengths. Co-doping with Nb
ion improved the deNOx ability, but co-doping with Fe ion depressed it, indicating that co-doping
with higher valence metal ion was effective in reducing the vacancy in the lattice which acts as the
recombination center of the photo-induced electrons and holes, and achieving higher photocatalytic
activity.
Layered Alumina Ceramics with Porosity Steps
Authors: Gregorová Eva , Pabst Willi , Chmelíčková Michaela
Published: October 2010

This work deals with the preparation and characterization of macroporous alumina
ceramics and permeable laminates with a stepwise (layerwise) porosity gradient in the range of
approx. 20–50 %. Layered structures are made by sequential casting and draining of ceramic
suspensions containing corn starch (median size approx. 14 micrometers), using both traditional slip
casting (TSC) and starch consolidation casting (SCC). In both techniques starch acts as a poreformer,
which is eliminated during firing. The influence of the alumina concentration and starch
content in the suspension on the porosity, pore size and pore connectivity in the individual layers is
studied. It is shown that differential shrinkage of the layers in the case of SCC, caused by the
different starch content, may be avoided by controlling the alumina content. The distribution of pore
throat diameters (cell window sizes) is determined by mercury porosimetry, whereas the
distribution of pore cavity diameters (cell sizes) is measured by microscopic image analysis.
Effect of the Hydrothermal Heat Treatment Conditions of Titanium Substrates on the Bio-Mimetically Grown “Bone-Like” Apatite Coatings
Authors: Teker Dilek , Sağ Can Poyraz , Dinçer Mehmet , Alkoy Sedat , Öztürk Koray
Published: October 2010

Hydrothermal surface modifications of the titanium specimens were performed (i) at 200
°C under 1.5 MPa pressure, and (ii) at 230 °C under 2.5 MPa pressure. To see the effect of an ion
implantation, two different aqueous hydrothermal environments were selected: (i) de-ionized water
and (ii) calcium containing de-ionized water. Hydrothermally treated titanium surfaces were
analyzed by X-ray photoelectron spectroscopy (XPS) and found to become rich with Ca when Cacontaining
hydrothermal environment was used. The surface-modified titanium specimens were
then kept immersed in 1.5X simulated body fluid (SBF) for 1, 2, 3 and 4 weeks. The biomimetically
formed coatings were characterized using scanning electron microscopy (SEM) and Xray
diffractometer (XRD). Crack formations and, consequently, severe peelings were observed after
drying for all the coatings on the substrates that were treated hydrothermally using only de-ionized
water. The Ca implanted titanium surfaces, on the contrary, were able to develop crack-free and
quite cohesive coatings. Up to two weeks of immersion and after drying, no-cracks were observed
in the coatings when the substrates were treated at higher temperature and under higher pressure
(230 °C and 2.5 MPa for the present investigation).
Lithium Disilicate Glass-Ceramic Obtained from Rice Husk-Based Silica
Authors: Santos Felipe Antunes , dos Santos Claudinei , Rodrigues Júnior Durval , Lazar Dolores Ribeiro Ricci , Faviero de Castro Dayane , Pinatti Daltro Garcia , Conte Rosa Ana
Published: October 2010

In this work lithium disilicate glass-ceramic and glasses based on the Li2O-SiO2 system
have been investigated by replacing the high-purity SiO2 starting powder by silica obtained from
rice husk. Glasses were developed at the stoichiometric composition of 66%.molSiO2:33%.molLiO2
using SiO2 obtained by thermochemical treatment of rice husk. The influence of rice husk-SiO2 on
phase formation, microstructure, hardness and fracture toughness was determined and discussed.
Investigations were carried out by means of differential thermal analysis, X-ray fluorescence, X-ray
diffractometry and scanning electron microscopy. Amorphous and transparent glasses were
obtained after melting. The glasses presented Tg near to 480 0C, crystallization peak at 660 0C in
both glasses from different silica sources and Li2Si2O5 as the crystalline phase after heat treatment.
The hardness (HV300gF) presented average values near to 430 HV for both high-purity and rice husk
silica powders. Fracture toughness measurements present results near to 1.7 MP am1/2 for both
compositions.
Crystal Growth of Calcite Nano-Plate by Alternate Soaking Method, Using CDS Crystals
Authors: Hayashi Koya , Tomohara M. , Fujino K. , Sakane Genta , Katayama Y.
Published: October 2010

Hetero-epitaxial growth of calcite crystals on calcium dodecyl sulfate (Ca(DS)2 = CDS) single crystals was studied by alternate soaking method.
The calcite (006) oriented single crystals grow on the (001) surface of the CDS.
The hetero-epitaxial growth mechanism is discussed by the lattice matching of the a-c planes of calcite and CDS according to the structure data of the CDS single crystal.
Microwave Assisted Solvothermal Synthesis and Visible Light Photocatalytic Properties of Nb and N Co-Doped SrTiO3 Nanoparticles
Authors: Sulaeman Uyi , Yin Shu , Sato Tsugio
Published: October 2010

Niobium and nitrogen co-doped SrTiO3 possessing excellent visible light responsive photocatalytic activity was successfully synthesized by microwave-assisted solvothermal reaction using SrCl2.6H2O, Ti(OC3H7)4, NbCl5 and hexamethylenetetramine in KOH aqueous solution. The photocatalytic activity was determined by DeNOx ability using LED lamps with the wavelengths of 627 nm (red), 530 nm (green), 445 nm (blue) and 390 nm (UV). The photocatalytic activity of SrTiO3 for DeNOx ability in visible light region could be improved by co-doping Nb5+ and N3-. The excellent visible light photocatalytic activity of this substance may be due to the generation of a new band gap that enables to absorb visible light and decrease in the lattice defects which acts as a recombination center of photoinduced electrons and holes.
Production and Characterization of Boron Carbide – Titanium Diboride Ceramics by Spark Plasma Sintering Method
Authors: Uygun Berkay , Göller G. , Onüralp Yücel , Şahin Filiz Çinar
Published: October 2010

This study was carried out to produce and characterize B4C - TiB2 ceramics by spark plasma sintering. Initial B4C and TiB2 powders were mixed in ethanol solution with YSZ balls for 1 hour. Sintering was performed with 5, 10, 15 and 20 volume % TiB2 containing mixtures respectively in disc-shaped graphite dies. The applied pressure was 40 MPa at 1760 °C for 5 minute sintering duration. The improvement of low sinterability and low strength of B4C was investigated as well as strength of flexibility, hardness and fracture toughness. The obtained products were characterized by X-ray diffraction and SEM imaging. The hardness values were measured under 1000 g load and the density values were measured with Archimedes' principle. The 3-point bending tests and modulus of elasticity measurements were also conducted.
The Effects of Codoping Y2O3 on MgO Doped Spark Plasma Sintered Al2O3
Authors: Apak Burcu , Göller G. , Onüralp Yücel , Şahin Filiz Çinar
Published: October 2010

Nanocrystalline alumina (Al2O3) powders were sintered by Spark Plasma Sintering (SPS)
method in a vacuum atmosphere to obtain highly dense and fine grained final ceramic products. In
the first section of experiments, 0.4 % wt MgO doped and 0.4 wt % Y2O3 doped Al2O3 were
sintered at high temperatures and under high pressure with a SPS system. Later sintering procedures
were carried out with codoping Y2O3 with the cathodic ratio of 0.4 wt % in order to investigate
dopant effects on spark plasma sintered alumina. The microstructures of all samples were observed
using scanning electron microscope and the properties such as density, hardness and fracture
toughness were examined.
Microwave Absorbency Change of Zirconia Powder and Fiber during Vacuum Heating
Authors: Sano Saburo , Kawakami Shoji , Takao Yasumasa , Takayama Sadatsugu , Sato Motoyasu
Published: October 2010

Stabilized zirconia shows rather high microwave absorbency at room temperature, and the
absorbency become higher with increasing temperature. In this study, stabilized zirconia powder,
partially stabilized zirconia powder and zirconia fiber were subjected for microwave absorption
measurements at elevated temperature. Microwave absorption measurements were done by using a
system consists of a microwave vector network analyzer, a circular wave-guide fixture and a vacuum
furnace. Microwave absorbency was evaluated by the reflection power change from the sample in the
circular wave-guide fixture under vacuum heating. Microwave absorbency of stabilized zirconia
powder, partially stabilized zirconia powder and zirconia fiber gradually increased with the increase
of temperature. We supposed that the increase of microwave absorbency is related to the ionic
(oxygen) conduction behavior of stabilized zirconia. Stoichiometric composition ZrO2 powder was
also subjected for a measurement to consider the relation between microwave absorbency and ion
conduction of zirconia. As the result, stoichiometric composition ZrO2 powder was not absorbed
microwave power even when the powder was heated up to 900oC because it isn’t an oxygen ion
conductor.
Hybrid Foams, Colloids and Beyond: Advanced Ceramics through Integrative Chemistry
Authors: Brun Nicolas , Ungureanu Simona , Carn Florent , Julián-López Béatriz , Backov Rénal
Published: October 2010

Today chemistry of materials and as such the ceramic field of research are addressed through more and more complex synthetic methodologies in order to optimize final material performances. The notion of complexity in chemical science is illustrated inhere through the concept of integrative chemistry. Particularly the integration between bi-liquid foams, sol-gel process, organo-silane functionnalization, lanthanides complexation and Pd heterogeneous nucleation is proposed as a non-exhaustive synthetic tool box to reach specific advanced ceramics. The first section is dealing with the synthesis of the first series of Si(HIPE) macrocellular foams where the oil volume fraction of the starting emulsion allows a nice tuning of the foams macroporosity. The second section is dealing with Europium complexation of diketone and malonamide hybrid Organo-Si(HIPE) leading to the Eu3+@Organo-Si(HIPE) luminescent foams, while the third part is dedicated to Pd heterogeneous nucleation within host hybrid foams. This last series of macrocellular ceramics are labeled Pd@Organo-Si(HIPE) which demonstrates good turn over number (TON) and turn over frequencies (TOF) when acting as supported catalysts for the Mizoroki-Heck coupling reactions. In the above mentioned foams the HIPE acronym is for High Internal Phase Emulsion.
The Quality of Brazed Ceramic and Cemented Carbide Joints - A Mechanical and Metallurgical Assessment
Authors: Tillmann Wolfgang , Wojarski Lukas , Lehmert Benjamin
Published: October 2010

The availability of adequate joining technologies is of major importance in order to exploit the full potential of ceramic materials. The same is true for joints between cemented carbides and their counterparts. Such joints are not easy to manufacture due to wetting and bonding problems as well as induced thermal stresses. Currently, active brazing is a potential approach for fabricating such joints. The filler alloy contains reactive agents such as Titanium or Hafnium etc. that interact by forming wettable reaction layers on the ceramic surface. It is self-evident that they function very well on cemented carbides as well.
The paper describes potential wetting and bonding reactions from a metallurgical point of view. Ceramics, superabrasive and cemented carbides are investigated with respect to interfacial reactions. The quality of the reaction products is of crucial importance regarding the mechanical performance of the joints, as their immanent brittleness can lead to a significant weakening.
Apart from metallurgical assessments, mechanical tests are conducted in order to deliver data for their integration in hybrid structures. FE methods can be applied to assess the stress situation in the final joint. Thus it is possible to adjust the design accordingly.
Temperature Modeling for Friction Welding Process between Ceramic and Metal
Authors: Seli Hazman , Izani Md. Ismail Ahmad , Rachman Endri , Ahmad Zainal Arifin
Published: October 2010

Numerical model of friction welding between ceramic and metal rods are established to predict
temperature rises during the initial phase of the process. In this study alumina(ceramic) and mild
steel(metal) rods are used and joined with aluminium sacrificial interlayer. The workpieces are
welded together by holding alumina still, while rotating the steel attached with aluminium piece
under influence of an axial load which creates frictional heat in the interfaces. The transient
thermal response in welding is hard to model analytically. Generally, heat is dissipated over
time scales of less than two seconds. For the thermal model, an explicit one dimensional (1-D)
finite difference (FD) method is utilized to approximate the heating and cooling temperature
distribution of the joined dissimilar rods. The preliminary predictions are compared to actual
thermocouple data from welds conducted under identical conditions and are shown to be in fair
agreement. Even though the FD method proposed in this study cannot replace a more accurate
numerical analysis, it does provide guidance in weld parameter development and allows better
understanding of the friction welding process.
Study of Corrosion Behavior of Conventional and Nanostructured WC-Co HVOF Sprayed Coats
Authors: Khameneh Asl Shahin , Saghi Beyragh Mohammad Reza , Kakroudi Mahdi Ghassemi
Published: October 2010

Interest in nanomaterials has increased in recent years. This is due to the potential of size reduction to nanometric scale to provide properties of materials such as hardness, toughness, wear, and corrosion resistance. The current study is focused on WC-Co cermet coats, materials that are extensively used in applications requiring wear resistance. In this work, WC-17Co powder was thermally sprayed onto mild steel using High Velocity Oxy Fuel (HVOF) spray technique. The nanostructured specimen was produced from sprayed sample by heat-treating at 1100°C in a vacuum chamber. Their structures were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Polarization and electrochemical impedance spectroscopy (EIS) tests were performed on the both types of coated samples in 3.5% NaCl solution. The amorphous phase in WC-17Co coating was transformed to crystalline phases by heat treatment at high temperatures. The heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. Generation of these phases produced the nanostructured coating with better mechanical properties. Comparative electro chemical test results showed that, the heat treatment could improve corrosion resistance of the nanostructured WC-17Co coat than the as sprayed coats.
Preparation, Characterization and Applications of Glass-Ceramic-to-Metal Seals
Authors: Donald Ian W. , Metcalfe B.L. , Gerrard L.A. , Fernie J.A.
Published: October 2010

It is recognized that many factors need to be taken into consideration in the successful design and manufacture of high quality glass-ceramic-to-metal seals, particularly if an adequate component lifetime is to be achieved. During their preparation, undesirable reactions may occur between diffusing metal species and glass constituents, and these can lead to the formation of highly localized internal stresses, the presence of which can initiate failure of a seal either during manufacture or, more seriously, whilst in service due to the influence of static fatigue. In the case of high temperature systems, reactions under hostile operating conditions also need to be taken into consideration. A thorough understanding of the relevant glass-ceramic/metal interactions is therefore required in order that steps can be taken to avoid or at least minimize reactions within the interfacial region that may lead to localized modifications of the glass-ceramic microstructure. In this contribution, factors influencing the lifetime behaviour of glass-ceramic/metal systems are reviewed and discussed, with particular reference given to SOFC sealants and also to advanced electrical components developed at AWE including seals to stainless steels and Ni-based superalloys. Fundamental studies on bonding to pure Fe, Ni and Cr are also included.
Near-Net-Shape Thermoplastic Forming of Alumina-Silicon Carbide Nanocomposites
Authors: Kern Frank , Gadow Rainer
Published: October 2010

Alumina-SiC nanocomposites have attracted the interest of material scientists due to their excellent mechanical and thermomechanical properties. Compared to alumina they offer higher strength, toughness and reliability. The high creep resistence of alumina-SiC makes it attractive for high temperature structural applications.
Commercial applications however require performing and reliable manufacturing technologies. Ceramic injection molding (CIM) was chosen for the production of small and complex shaped components with narrow dimensional tolerances used in engineering applications. For axially symmetric, elongated component geometries such as tubes or rods, thermoplastic extrusion is a more appropriate forming technology. In this study the complete process cycle of thermoplastic extrusion and injection molding was evaluated with the aim to evaluate their suitability for industrial production of alumina-SiC nanocomposites. Compounding of the feedstocks, forming by CIM and extrusion and the subsequent thermal treatment – debinding and pressureless sintering were investigated. Intermediate and final products were characterized with respect microstructure and mechanical.
Microstructural Evolution during High-Temperature Oxidation of Ti2AlN Ceramics
Authors: Cui Bai , Sa Rafael , Jayaseelan Daniel Doni , Inam Fawad , Reece Michael J. , Lee William Edward
Published: October 2010

Microstructural evolution of Ti2AlN ceramics during high-temperature oxidation in air has been revealed by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEGSEM), and energy-dispersive spectroscopy (EDS). After oxidation below 1200 °C, layered microstructures formed on Ti2AlN surfaces containing anatase, rutile, and α-Al2O3. Above 1200 °C, more complex layered microstructures formed containing Al2TiO5, rutile, α-Al2O3, and continuous void layers. With increasing temperature, anatase gradually transformed to rutile, and TiO2 reacted with α-Al2O3 to form Al2TiO5. Based on these microstructural observations, an oxidation mechanism for Ti2AlN ceramics is proposed.
Production and Characterization of Alumina-Diamond Composites and Nanocomposites
Authors: Agnolon Pallone Elíria Maria de Jesus , Trombini Vania , Silva Kátia L. , Bernardi Luis O. , Yokoyama Makoto , Tomasi Roberto
Published: October 2010

One of the most recent alternatives in the development of materials with high mechanical
properties and wear resistance is the addition of nanometric and/or micrometric particles of a
secondary phase into ceramic matrices. Nanostructured materials can be defined as systems that
have at least one microstructural characteristic of nanometric dimensions (less than 100nm). In this
work, alumina-diamond nanocomposites were produced using nanometric diamond powder
obtained by high energy milling in a SPEX mixer mill for 6h. The crystallite size was 30nm. After
deagglomeration, the diamond powder was added to the alumina matrix in a ratio of 5wt%. The
samples were isostatically pressed and high-vacuum sintered. The resulting nanocomposites and
composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy
(SEM), and by microhardness, diametral compression and wear resistance tests. The results
confirmed the promising wear characteristics of the alumina-diamond nanocomposite.
High Activity Photocatalyst Powder Formed by Three Ceramic Oxides
Authors: Perazolli L. , Pegler G.F. , Silva M.R.A. , Ingino R.A.F. , Varela J.A.
Published: October 2010

A Photocatalyst ceramic powder that presented high photoactivity based on TiO2
modified with 25% molar of SnO2 and up to 5% molar of Ag2O was obtained in the present work.
The aforementioned ceramic powder was obtained using all commercial oxides as well as the
oxides mixture technique. The powders were ground in high energy mill for one hour with
subsequent thermal treatment at 400°C for four hours. They were, furthermore, characterized using
surface area of around 6m2/g, where the X-Ray diffraction results provided evidence for the
presence of anatase and rutile phases, known to be typical characteristics of both the TiO2 and SnO2
used. During the thermal treatment, Ag2O was reduced to metallic silver. The photodegradation
rehearsals were carried out using a 0.01 mmol/L Rhodamine B solution in a 100mg/L photocatalyst
suspension in a 500ml beaker, which was irradiated with 4W germicide Ultraviolet light of 254nm.
In addition, samples were removed after duration of about 10 minutes to an hour, where they were
analyzed thoroughly in UV-vis spectrophotometer. The analysis of the results indicated that for the
compositions up to 2.5% molar of Ag2O, the photoactivity was found to be greater than that of
Degussa P25 photocatalyst powder, and as such it was then used as a reference. Taking into account
90% degradation of Rhodamine B, a duration period of 11 minutes was obtained for the developed
photocatalyst powder compared to the 38 minutes observed for the Degussa P25. FEG-SEM
micrographies enabled the verification of the morphology as well as the interaction of the oxide
particles with the metallic silver, which led us to propose a model for the increase in photoactivity
observed in the photocatalyst powder under investigation.
Influence of Residual Thermal Stresses on the Properties of the NiAl Matrix Composites Reinforced with Ceramic Particles
Authors: Kaliński Dariusz , Chmielewski Marcin , Pietrzak Katarzyna
Published: October 2010

One of the most important problems in both the fabrication and exploitation of ceramicmetal
composites are residual thermal stresses. The paper presents the results of a numerical
analysis (by the Finite Elements Method) of the stress state induced in the NiAl matrix composites
reinforced with spherical particles of a ceramic phase (Al2O3, ZrO2, TiC), including examinations of
the dependence of this stress state on the volumetric fraction of the ceramics (20 to 40vol.%). The
stress state prevailing in this composite appeared to be complex. In all the samples, the stresses
active in the ceramic regions were compressive whereas those active in the metal matrix were
tensile in the circumferential direction and compressive in the radial direction. An increase of the
ceramic volumetric fraction resulted in an increase of the tensile stresses in the NiAl matrix and a
decrease of the compressive stresses in the ceramic particles.
These theoretical results were verified experimentally by examining the properties of the
NiAl-Al2O3, NiAl-ZrO2 and NiAl-TiC (20 and 30 vol.% fraction of the ceramics) composites
produced by hot-pressing. The microstructure, density, and bending strength of these composites
were examined, and the results are discussed in the paper.
Effect of an Oxides Composite Support of Ce(Sm)O3-La(Sr)CrO3 on Pd-Ni Alloy for Decomposition Activity of CH4
Authors: Yamanaka Ichiro , Nabae Yuta , Ito Takeo
Published: October 2010

A Pd-Ni/La(Sr)CrO3-Ce(Sm)O2 composite anode showed good performance for solid oxide fuel cell reactions with dry CH4. Compositions of Pd and Ni in the Pd-Ni/La(Sr)CrO3-Ce(Sm)O2 composite anode affected the electrochemical oxidation catalysis of dry CH4. The Pd and Ni ratios from 50:50 to 75:25 were suitable for the oxidation. The Pd-Ni/La(Sr)CrO3-Ce(Sm)O2 composite anode showed the high tolerance to the carbon deposition under closed and open circuit conditions. A Pd-Ni/Ce(Sm)O2 catalyst showed very low catalytic activity for decomposition of dry CH4. A Pd-Ni/SiO2 catalyst showed very high catalytic activity for the decomposition of dry CH4 and a large amount of deposited carbon formed. The Pd-Ni particles on SiO2 were quite multifaceted from TEM-EDS observation. On the other hand, the Pd-Ni particles on Ce(Sm)O2 support had a spherical shape and doping of Ce and Sm was confirmed. This nature should inhibit the formation of particular plane that is essential for the carbon fiber formation. The detail function of Ce(Sm)O2 and La(Sr)CrO3 supports was discussed.
Soot and Ash Layer Characteristics in Ceramic Diesel Particulate Filters
Authors: Dimopoulos Eggenschwiler Panayotis , Liati Anthi
Published: October 2010

Detailed investigation of the morphology, internal structure and oxidative reactivity of
PM (ash and soot) trapped in a loaded, uncoated, ca. 30cm long DPF made of SiC, used on a small
truck engine operating on a test bench for ca. 250 hours without fuel borne additive revealed the
following: ash PM accumulates at the outflow part of the DPF after repeated regenerations, filling
up ca. 15% of the effective filter volume. The ash shows a tendency to accumulate more at central
over periphery segments, probably following the corresponding differences in the flow rate pattern
of the exhaust stream. The amount of ash diminishes significantly towards inflow and becomes
minor at ca. 10cm from filter inlet.
Soot occurs as aggregates forming a coherent ‘cake’ deposited only in inflow channels. Outlet
channels are completely devoid of any deposited material. HRTEM studies show that soot forms
aggregates consisting of individual, nearly spherical particles with an average size of 24nm in
diameter. The internal particle structure consists of an outer part with nearly concentric alternating
lamellae and an amorphous core. Raman spectra of the soot reveal a certain degree of crystallinity
and are in line with spectra reported for carbon blacks produced at high temperatures exhibiting low
surface area but high degree of ordered structure.
Thermo-Chemo-Mechanical Modelling of Mixed Conductors in Transient Stages
Authors: Valentin Olivier , Blond Eric , Richet Nicolas
Published: October 2010

This study deals with the modelling of the mechanical behaviour accounting for the expansion induced by the oxygen diffusion in MIECs membrane during semi-permeation transient stage. A dedicated model of chemical expansion and its numerical implementation is used to study the relationship between the mechanical stress and the oxygen flux. The impact of the ratio between oxygen bulk diffusion and surface exchange kinetics on mechanical stress in transient stage is discussed. At last, the need of a compromise between the oxygen flux performance and the mechanical reliability is underlined.
Synthesis and Characterization of the LiMnP1–xVxO4–δ Solid Solutions
Authors: Kellerman Dina G. , Mukhina Natalya , Gorshkov Vadim , Tsarev Boris , Zhuravlev Nikolai , Zabolotskaya Elena V.
Published: October 2010

Compounds with the olivine-type structures are considered as perspective materials for
lithium-ion power sources for both industrial and transport applications. Lithium iron phosphate is
most highly developed from this family, but LiMnPO4 is supposed as much promising, due to its
higher EMF vs. lithium. One of the main lacks of this class of materials is the low electronic
conductivity. The traditional ways of conductivity increase by partial replacement of Mn with other
transition metal for LiMnPO4 do not result to essential success. Our approach consisting in the
influence onto anion sublattice results to better effect. Such solid solutions should be suitable for
oxygen nonstoichiometry creation in virtue of ability of vanadium ion for oxidation degree
downturn. Using magnetic methods, we succeeded to show that the required solid solutions are
really formed. The optimal synthesis conditions of LiMnP1-xVxO4-δ solid solutions were determined.
It was shown, that the doping of LiMnPO4 by vanadium jointly with oxygen nonstoichiometry
brings to substantial enhance of electronic conductivity in this material. Observed peculiarities of
the magnetic properties indicate the restructuring in the local environment in anion sublattice.
Structural Ceramics Based on Nanosized Si3N4 Powders
Authors: Rumyantsev V. , Osmakov Andrey , Korableva N. , Belykh N. , Stafeckis L. , Ordanyan S.S.
Published: October 2010

Ceramics based on nanosized plasma chemistry Si3N4 powder compositions s (30-100
nm) is processed by activated pressureless sintering, hot pressing and hot isostatic pressing.
Microstructure characterization of the obtained materials by means o light and scanning microscopy
revealed no correlation between microstructure and the bulk consolidation method . Average grain
size in all cases was 200-500 nm.
Comparative characterization of the physical and mechanical behavior of the analyzed samples
showed the following results: relative density - over 99 %, flexural strength – over 700 MPa,
Vickers hardness - 16-17GPa, fracture toughness – 6.5-7.4 MPa·m1/2. The activated pressureless
sintered samples demonstrated physical and mechanical behavior comparable to the samples
consolidated by other methods.
Activated pressureless sintering of nanosized plasma chemistry Si3N4 powders led to considerable
economic advantages in processing Si3N4 spherical rotation bodies for hybrid roller bearings and
cutting tools.
Silicon nitride (Si3N4)-based structural ceramics is widely studied and used for over half a century
due to its unique properties: low density, combined with high strength and wear-resistance, high
decomposition temperature, high oxidation resistance, low friction coefficient and high resistance to
chemical corrosion[1].