bluuebunny/crossref_metadata_2025 huggingface dataset:
Deposition Characteristics of Direct-Write Suspended Micro/Nano-Structures
Authors: Zheng Gao Feng , Wang Ling Yun , Wang Hong Lian , Sun Dao Heng , Li Wen Wang , Lin Li Wei
Published: March 2009

Direct-Write (DW) technology based on Near-Field Electrospinning (NFES) was introduced to fabricate suspended micro/nano-structure on pattern substrate, and the deposition behaviors of DWed structure under different collector motion speed (CMS) were discussed to improve control of DW technology based on NFES. Deposit point of DWed structure on the substrate can be controlled accurately under the observation of microscope, and position error of micro/nano-structure is less than 5µm. When CMS is compatible with the electrospinning speed, straight line micro/nano-structure can be direct-written across micro-trenches with width of 5~40µm or to bridge two micro-pillars with diameter of 10µm. Due to the water evaporation and surface tension force, DWed structures suspended in the air would shrink smaller compared with that deposited on the top surface of pattern. The shrink ratio of micro-structure is higher than nano-structure and the shrink ratio decreases with the solution concentration increases. When the CMS is lower than electrospinning speed, the electrostatic force and elastic force would play a more prominent role on the deposition behavior of DWed structure. The electrical field strength on the top surface of pattern is higher than the space between two patterns, DWed thin film would deposit along the trip pattern and nanofiber would prefer to aggregate on the top surface of pattern under electrostatic force. When solution concentration is lower than 18%, nanofiber aggregate on the pattern would coagulate to form polymer bundle.
A High-Efficiency Energy Storage Scheme of Solar Micro-Power Systems
Authors: He Yong Tai , Liu Li Hui , Li Yan Qiu , Wang Lei
Published: March 2009

In self-power sensor nodes, the capability of energy harvesting and storing of the solar micro-power system determines their lifetime and adaptability to the environment. As a load of solar cells, energy storage devices directly influence the output conversion efficiency of solar cells and output power of solar micro-power system. In this paper, the advantages and disadvantages of NiCD batteries, NiMH batteries, Polymer Lithium-ion batteries and Super-capacitors are analyzed based on features of the solar micro-power system. A hybrid storage system combined with Polymer Lithium-ion batteries and the super-capacitors is designed. Experimental results show that the power density of hybrid storage system is larger than that of Polymer Lithium-ion batteries. The capability of pulsing load is improved over 60%, and the energy storage loss is reduced.
Gauge Factor and Nonlinearity of P-Type Polysilicon Nanofilms
Authors: Liu Xiao Wei , Lu Xue Bin , Chuai Rong Yan , Shi Chang Zhi , Huo Ming Xue , Chen Wei Ping
Published: March 2009

The gauge factor and nonlinearity of 80nm polysilicon nanofilms with different doping concentration were tested. The experimental results show that, from 8.1×1018cm-3 to 2.0×1020cm-3, the gauge factors first increase then decrease, which like the common polysilicon films (thickness is larger than 100nm). From 2.0×1020cm-3 to 7.1×1020cm-3, the gauge factors do not change with doping concentration almost, which can be explained by tunneling piezoresistive theory. When doping concentration is low than 4.1×1019cm-3, the nonlinearities are big, and the nonlinearities become small when doping concentration is high than 4.1×1019cm-3. The nonlinearity is related to the occupied condition of trapping states in grain boundary. The longitudinal gauge factor and nonlinearity are smaller than transverse ones. Take the gauge factor and nonlinearity both into consideration, the optimal doping concentration should be 4.1×1019cm-3. The conclusions are very useful for design and fabrication of polysilicon nanofilms piezoresistive sensor.
Analysis of Tunneling Piezoresistive Effect of P-Type Polysilicon Nanofilms
Authors: Lu Xue Bin , Liu Xiao Wei , Chuai Rong Yan , Shi Chang Zhi , Huo Ming Xue , Chen Wei Ping
Published: March 2009

The polysilicon nanofilms have significant piezoresistive characteristics. In this paper, an analysis of tunneling piezoresistive effect of p-type polysilicon nanofilms is presented based on the experimental data. The analysis results show that the tunneling piezoresistive effect is much remarkable than piezoresistive effect of neutral region, and the former is about 1.3 to 1.5 times of the latter. The higher is doping concentration, the more remarkable tunneling piezoresistive effect is. This advantage can be utilized to improve the temperature characteristics of polysilicon piezoresistive sensor.
The Potential Use of Periwinkle Shell as Coarse Aggregate for Concrete
Authors: Osarenmwinda J.O. , Awaro A.O.
Published: March 2009

The potential of periwinkle shell as coarse aggregate for concrete was studied in this paper. The properties of concrete made with periwinkle shell as coarse aggregate were examined. Test conducted on the concrete was compressive strength test. Prescribed mix designs of 1:1:2, 1:2:3, 1:4:6, 1:2:4 and 1:3:5 were used to produce concrete cubes used for testing. The different constituents that make up the periwinkle concrete are presented in ratio form as cement: sharp Sand: Periwinkle shell. Batching was done by volume and the corresponding weight recorded. The cubes were made and tested at hydration periods of 7, 14, 21 and 28 days to determine the compressive strength of the periwinkle shell concrete. The results show that periwinkle shell has a bulk density of 517kg/m3 and specific gravity of 2.05. The results also shows that design mix of 1:1:2, 1:2:3 and 1:2:4 with compressive strength of 25.67 N/mm2, 19.50N/mm2 and 19.83N/mm2 at 28 days hydration period respectively met the ASTM-77 recommended minimum strength of 17N/mm2 for structural light weight concrete while mix design of 1:4:6, and 1:3:5 with compressive strength of 14.00N/mm2 and 16.50N/mm2 respectively did not met the standard.
Toxicity Assessment of some Crude Oil Contaminated Soils in the Niger Delta
Authors: Aisien F.A. , Chiadikobi J.C. , Aisien E.T.
Published: March 2009

This paper considered the toxicity assessment of some crude oil contaminated soils in Niger Delta areas. The soil samples were collected from different horizontal distances, vertical depths and contaminated soil of different ages. The heavy metals in the contaminated soils were digested and extracted using di-acid digested and DTPA extraction methods respectively. The physiochemical parameters (moisture content, pH, N, P and heavy metals (Ni, Pb and Cd) were analysed with APHA method. The heavy metals concentration was determined using atomic absorption spectrophotometer (AAS). The results show that the metals concentration decreased with the age of the contaminated soil and with increased vertical depths. However, the metals concentrations were almost constant at different horizontal distances. Similar trend was observed for the moisture content, pH, N, P and K.
Micromechanical Model for Simulating Hydraulic Fractures of Rock
Authors: Yang Tian Hong , Tham Leslie George , Wang S.Y. , Zhu Wan Cheng , Li Lian Chong , Tang Chun An
Published: March 2009

A numerical model is developed to study hydraulic fracturing in permeable and heterogeneous rocks, coupling with the flow and failure process. The effects of flow and in-situ stress ratio on fracture, material homogeneity and breakdown pressure are specifically studied.
Surface Electrode Problems in Piezoelectric Materials
Authors: Zhou Kun Li , Zhou Zhi Dong , Kuang Zhen Bang
Published: March 2009

In this paper, the surface electrode problems in a piezoelectric half-plane with surface electrode are presented. By the analytical continuation method these problems can be reduced to Reimann-Hilbert problems and the closed-form expressions of the mechanical and electric fields are obtained. This research is useful for the piezoelectric apparatuses.
Charged Defect Formation Energies in TiO2 Using the Supercell Approximation
Authors: He Jun , Finnis Mike W. , Dickey Elizabeth C. , Sinnott Susan B.
Published: March 2009

TiO2 has been intensively studied as a wide band-gap transition metal oxide partially due
to the multi-valence nature of its cation. Here, density-functional theory calculations within the
supercell approximation are carried out to determine the preferred charge state of point defects in
rutile TiO2. The first component of this work is to investigate the dependence of the defect
formation energies on supercell size and the electrostatic Makov-Payne correction. The results show
that the Makov-Payne correction improves the convergence of defect formation energies as a
function of supercell size for positively charged titanium interstitials and negatively charged
titanium vacancies. However, in the case of positively charged oxygen vacancies, applying the
Makov-Payne correction gives the wrong sign for the defect formation energy correction. This is
attributed to the shallow nature of the transition levels for this defect in TiO2. Finally, we combine
the calculated defect formation energies with thermodynamic data to evaluate the influence of
temperature on the relative stabilities of point defects. The results indicate that when the Makov-
Payne correction is applied, a stable charge transition occurs for titanium interstitials. In addition, as
the temperature increases, the dominant point defect in TiO2 changes from oxygen vacancies to
titanium interstitials.
Self-Propagating High-Temperature Synthesis of Dense TiC-TiB2-MeO Ceramics
Authors: Shcherbakov Vladimir A. , Phitev Anton V. , Sachkova N.V. , Deorsola Fabio A. , Vallauri Dario , DeBenedetti Bruno
Published: March 2009

The aim of this work is the preparation and study of the mechanisms of structure
formation of dense ceramics based on the TiC–TiB2–MeO system obtained by pressure–assisted
Self-propagating High-temperature Synthesis. SHS systems were selected on the basis of
thermodynamic analysis as suitable to realise regimes of synthesis with formation of liquid phase
allowing a full densification. It was observed that at the adiabatic temperature the liquid phase
formed in the SHS products consists of either melted oxides or eutectic TiC–TiB2. The results of
microstructural observations and mechanical characterization confirm that the metal oxides
effectively promote the densification of the final products and the grain refinement of the SHSproduced
ceramic materials.
Synthesis Mechanisms of the Combustion Synthesis of IntermetCers Composites
Authors: Curfs C. , Terry A.E. , Vaughan G.B.M. , Kisi Erich H. , Rodríguez Miguel A. , Kvick Å.
Published: March 2009

Combustion synthesis techniques have been applied to an equiatomic mixture of
Aluminium, Nickel, Titanium and Carbon powders in order to obtain NiAl/TiC composites. Both
combustion modes have been used: the Self-propagating High-temperature mode (SHS), in which
the reaction propagates through the sample under the form of a heat wave and the Thermal
Explosion mode (TES), in which the reaction occurs simultaneously in the complete sample. The
reactions have been followed in-situ by time-resolved diffraction, using synchrotron X-rays for the
SHS mode and neutrons for the TES mode. Scanning Electron Micrographs and X-ray diffraction
patterns of the final product have shown that the same final products were obtained when the
mixture was synthesised under both combustion modes: a composite made of small and round TiC
particles (~1 micron) embedded into a matrix of larger NiAl grains (5 microns). However, the
Time-Resolved Diffraction studies have shown that, even with the same final products, the two
combustion modes follow two completely different routes. Thus, for the SHS mode, the reaction is
triggered by the formation of Nickel Aluminide and 3 intermediate phases are observed, and for the
TES mode, the self-sustained reaction starts with the formation of Titanium Carbide and no
intermediate phases have been seen.
Structure and Phase Formation in SHS_FGM
Authors: Rogachev A.S.
Published: March 2009

Self-propagating high-temperature synthesis (SHS), also known as combustion
synthesis, is one of the most prospective methods for production functionally graded materials
(FGM). The advantages of SHS include short time of reaction and product formation, which
allow retaining pre-determined concentration gradient in the synthesized material. In the
present work, the following challenges remaining in the field of FGM production by SHS are
discussed. First, main features of combustion of multilayer samples are considered from the
viewpoint of mutual influence of the combustible and inert layers. Second, evolution of the
concentration gradients (profiles) during the combustion is outlined and different methods for
controlling this process, such as mechanical pre-activation of the reactants are examined.
Third, processes of the product phase and microstructure formation in multilayer SHSmaterials
are described. The problem of creating very thin gradient samples and coatings by
SHS is also discussed. The consideration includes data of high-speed video recording, timeresolved
X-ray diffraction, SEM, EPMA and other experimental techniques.
The Analysis of Stress Concentration in Piezoelectric Ceramic Multilayer Actuators
Authors: Wang Hai Tao
Published: March 2009

This paper concerns the determination of stress concentration in piezoelectric ceramic
multilayer actuators when they are subjected to electrical loads. A full numerical procedure is
developed here to evaluate the strength of the stress concentration at the tip of electrodes. The whole
procedure consists of two steps: (1) a 1D finite element formulation is proposed to determine the
eigensolution of the singular electromechanical field; (2) a hybrid-Trefftz element is constructed to
determine the strength of the singular electromechanical field. The independently assumed stress and
electrical displacement fields are extracted from the eigensolution obtained from previous 1D finite
element formulation. Then, the proposed procedure is used to study stress concentration in
piezoelectric ceramic multilayer actuators.
On Thermal Conductivity of Porcelain Glaze with a Few Added Components
Authors: Jiang Hong Zhou , Tang Ying , Li Juan Juan , Zhou Jian , Liu Gui Zhen
Published: March 2009

The effects of a few added components, i.e. SnO2, Cr2O3 and Fe2O3, in porcelain glaze on
thermal conductivity of porcelain glaze are studied in this paper. The thermal conductivities of
several porcelain glaze samples with different contents of SnO2, Cr2O3 and Fe2O3 were measured
with a special measuring apparatus at room temperature. The theoretical explanation for these
measurement results is also sought according to the theory on heat transfer in solid materials,
briefly.
Thermally Sprayed Coating Composites for Film Heating Devices
Authors: Killinger Andreas , Gadow Rainer
Published: March 2009

Direct heated systems in white goods for medium temperature applications (approx. 250°
-350° C) can be applied onto glass, glass ceramic and metal substrates by means of thermal spray
techniques. Essentially, such a system requires at least two functional layers to work properly: (1)
The metal coating that works as the heating element and (2) an insulator coating that electrically
separates the substrate from the film heater. Therefore, the heating device combines three materials
(substrate, insulator and film heater) with rather different thermophysical properties. An optimized
spray deposition process with proper guidance of the heat flow is required to produce coatings that
can operate under cyclic thermal load conditions.
The paper discusses the influence of thermal spray process parameters as well as the applied spray
powders on the electrical properties of the achieved layer structures of the respective insulator and
film heater coatings.
Synthesis and Electrophoretic Deposition of Mullite Precursor Sols for the Oxidation Protection of Carbon Fibre Reinforced Composites
Authors: Moritz Kirsten , Herbig R. , Damjanović Tanja , Argirusis Christos , Borchardt Günter
Published: March 2009

The preparation of mullite coatings for the oxidation protection of carbon fibre reinforced
composites using a combination of sol-gel synthesis and electrophoretic deposition (EPD) has been
investigated.
Mullite precursor sols were synthesised by controlled hydrolysis and condensation reactions of the
metal alkoxides TEOS (tetraethoxysilane) and Al(OBus)3 (aluminiumtri-sec-butylate).
The structure and properties of the mullite precursor were strongly influenced by the synthesis
parameters, especially by the water to TEOS ratio (rw/Si) and the pH value of the water. A variety of
synthesis conditions was tested for optimising the mullite precursor sols regarding their suitability
for the electrophoretic deposition. The electrokinetic behaviour of the sols and the charging of the
sol particles which is necessary for a successful EPD were investigated by measurements of the
Electrokinetic Sonic Amplitude (ESA signal).
29Si CP/MAS NMR measurements were used to get information about the coordination of the
silicon and the homogeneity of the Al/Si distribution in the precursors. Heat-treated samples were
characterised by X-ray diffraction for investigating the mullite formation.
Coatings prepared by EPD and sintering at 1300 °C in Ar enabled an effective oxidation protection
in the temperature range 1200 °C ≤ T ≤ 1550 °C.
FeTiO3/Fe2O3 Multilayered Films for New Magnetic Semiconductors above Room Temperature
Authors: Fujii Tatsuo , Takada Yusuke , Takada Jun
Published: March 2009

Well-crystallized Fe1.18Ti0.82O3 and Fe1.18Ti0.82O3/Fe2O3 bilayered films were successfully
prepared by using reactive helicon plasma sputtering technique. The solid solution films, Fe2−xTixO3,
between hematite (α-Fe2O3) and ilmenite (FeTiO3) with various Ti concentrations, x, were epitaxially
formed on the α-Al2O3(0001) single-crystalline substrates. The magnetic and electric properties of
the solid solution films were systematically changed with increasing the Ti concentration. The film
with the intermediate composition of Fe1.18Ti0.82O3 had the largest saturation magnetization at low
temperature. However, the TC of solid solution films was linearly decreased with increasing the Ti
concentration. The Fe1.18Ti0.82O3 film without Fe2O3 layers showed lower TC of about 200 K, while the
TC of the Fe1.18Ti0.82O3/Fe2O3 bilayered film increased to about 220 K. The strong magnetic coupling
between layers seemed to increase the TC of the attached Fe1.18Ti0.82O3 layer. The sharp interface
between Fe1.18Ti0.82O3 and α-Fe2O3 layers was confirmed by the XPS depth profiling.
Microstructures and Interfaces in Melt-Growth Al2O3-Ln2O3 Based Eutectic Composites
Authors: Mazerolles Léo , Piquet N. , Trichet M.F. , Parlier Michel
Published: March 2009

Directionally solidified oxide eutectic ceramics were prepared from Al2O3, Ln2O3 and ZrO2 based
binary or ternary systems. Their microstructures consist of continuous networks of single-crystal
Al2O3 and oxide compounds (LnAlO3, Ln3Al5O12) which interpenetrate without grain boundaries.
The outstanding stability of these microstructures gives rise to a high strength and creep resistance
at high temperature. Influence of growth conditions on the morphology of the as-obtained
microstructures was studied. Preferred growth directions, orientation relationships between phases
and single-crystal homogeneity of specimen were revealed. Low residual stresses were measured in
the binary eutectics and fracture toughness at room temperature was improved by the addition of
zirconia at a eutectic composition in ternary systems.
Ceramic Composites for Automotive Friction Devices
Authors: Licciulli Antonio , Chiechi Antonio , Diso Daniela , Maffezzoli Alfonso
Published: March 2009

Advanced braking devices can represent a promising application for ceramic matrix
composites (CMC) with functional and structural properties. If the actual advanced braking
materials could be at least partially replaced by CMCs, it might become the first consumer market
for these materials. CMC containing three main phases, silicon carbide, graphite and carbon fibers
were prepared. A systematic analysis of the processing-structure-properties relationship of the
composite is carried out. In particular, silicon carbide provides the necessary hardness, whereas
graphite is used for its lubricating properties, and carbon fibers are used as reinforcement. The
samples, prepared using a reactive bonding technique, exhibited adequate mechanical properties,
high resistance to thermal shocks and good stability after many thermal cycles. Morphological and
structural investigations have been performed to optimize the content of each component.
Preliminary tribological investigations are presented.
Polyethylene-Clay Nanocomposites Using Ionomeric Compatibilizer
Authors: Sánchez-Valdés Saul , López-Quintanilla M.L.
Published: March 2009

Nanocomposites made of linear low-density polyethylene (LLDPE) and two different
types of clays were obtained and studied by using zinc neutralized carboxylate ionomer as a
compatibilizer. Two different clays, natural montmorillonite (Closite Na+) and a chemically
modified clay Closite 20A has been used. Nanocomposites were prepared by melt blending in a
twin-screw extruder using two mixing methods: two-step mixing and one-step mixing. The relative
influence of each compatibilizer was observed from structural analysis by WAXD, and mechanical
properties. Experimental results confirms that the film samples with ionomer showed good
mechanical performance and that the two step mixing conditions resulted in a better dispersion and
intercalation for the nanofillers than one step mixing.
Effects of Magnetic Powder Loading on Mechanical Properties and Magnetic Properties of Natural Rubber
Authors: Woramongconchai Somsak , Lohitvisat Chatchawan , Wichainchai Aree
Published: March 2009

The effect of magnetic powders and powders loading on magnetic properties and
mechanical properties of magnetic rubbers were studied. The natural rubber with magnetic powders,
Barium ferrite, Neodymium iron boron, were used as starting materials to prepare magnetic rubbers.
Barium ferrite (BaO.6F2O3) powders had been sintered at 1285 oC for 30 hours to improve its
crystal structure. The physical properties of magnetic rubbers, residual flux density (Br), coercive
force (Hc), maximum energy product (BHmax), hardness and density, had a trend to increase as
enhancing magnetic powders loading. However, some properties such as, intrinsic coercive force
(Hci), tensile strength and elongation at break, had a trend to decrease when the magnetic powder
loading was increased. Magnetic properties of the anisotropic type, sintered powders, were higher
than isotropic type, non-sintered powders, except the Hci because anisotropic magnetic rubber
indicated crystal orientation in the same direction.
Attainment and Characterization of the Thermosetting Polymer Loaded with Barite to be Used in the Manufacture of Isolating Plates to Bar the X-Ray Radiation
Authors: Figueiredo de Miranda Leila , Munhoz Jr. Antônio Hortêncio , Masson Terezinha Jocelen , Naime Virgínia Carolina , Camargo Costa Gustavo
Published: March 2009

The properties of composites based on thermosetting polyester and barite for use in the radiological protection area have been investigated with the objective to study the effect of different variables in the attainment of composites. To verify the efficiency of the composites produced in relation to radiological protection, lead was adopted as reference. A factorial experimental design was carried out and the studied variables were: type of polyester resin (orthophthalic or isophthalic), coupling agent (titanate or organosilane) and the ratio of resin to accelerator, catalyst and barite. The variables analyzed were: efficiency for barring the X-radiation, apparent density and mechanical properties. The effect, obtained from the experimental design, due to ratio of resin to barite in the apparent density was 0.036. The average apparent density of the samples produced with barite/resin value equal 2.0 (weight ratio) was 2.16g/cm3, while the average density of the samples produced with the weight ratio of barite/resin equal 3.0 was 2.2g/cm3. It was observed same trend for the density to mechanical properties. It was observed that the samples attenuated X-ray radiation adequately up to 116 kV.
Structure and Properties of Heterophase Nanostructured Ceramics
Authors: Ordanyan S. , Rumyantsev V. , Osmakov Andrey
Published: March 2009

The paper is dedicated to the study of the interdependence of structure and properties
of sintered heterophase ceramic composition based on ultra-fine (nanosized) powders. The
compositions based on brittle oxygen-free high-strength compounds under certain conditions are
able to demonstrate micro-plasticity. Microstructure of such materials typically features
homogeneous fine grains with certain critical maximum grain size. The substantial contribution
of interphase boundaries and their dislocation structure to the non-trivial mechanical properties is
discussed. Special features of interphase boundaries are demonstrated to contribute to the change
in rupture resistance of the heterophase ceramics.
Correlations between strength and elastic properties and results of tribological tests using «pin
and disk» arrangement were studied.
Increased fracture resistance, wear resistance, and micro-plasticity of heterophase ceramics is
found to be due to the modification microstructure size parameters and distinctive features of
interphase boundaries.
The generally formulated purpose of the present study is a search for the solution to the problem
of production of the advanced structural ceramic materials based upon oxygen-free refractory
compounds with improved physical and mechanical properties.
New Generation of CBN Grinding Wheels Bonded with Glass-Ceramic
Authors: Herman Daniela
Published: March 2009

The paper presents results of investigations on the application of glass-ceramic to
bonding the CBN grains into abrasive composite. The application of the glass with specific
chemical composition makes it possible to generate the designed crystalline phase in it. A type of
crystalline phase has a significant influence on the elastic modulus E.
Residual Stresses in Ceramic Metal Assembly after Brazing Process
Authors: Cazajus V. , Lorrain B. , Welemane H. , Karama Moussa
Published: March 2009

The framework of this study is the thermo-mechanical analysis of the brazing
process of ceramic metal assemblies. The thermal expansion gradient between ceramic and
metallic materials leads to the development of residual stresses during the cooling phase of
the brazing process which induce consequently an important reduction of the strength of these
composite structures. In the present work, numerical simulations are performed in order first
to predict the residual stresses distribution after the brazing process and in a second step, to
study their influence on the tensile strength of metallized ceramic seals. Results obtained are
compared with experimental tests.
Metallization of AlN for Electronics
Authors: Yokoyama Hiroki
Published: March 2009

Aluminum nitride (AlN) is widely used in the field of electronics because it has high
thermal conductivity, good electric and mechanical properties. On the other hand it has a shortcoming
of being difficult to wet metals. Therefore, various contrivances are needed to form a metal film with
high adhesion strength on AlN surface. In this paper we will review the vacuum technology that has
been used up to now, and mention the middle thickness film printing method that will be a key
technology from now on. Adhesion mechanism in the interface between AlN and metal film will be
also reported.
Grain Boundary Diffusion in Cation-Doped Superplastic 3Y-TZP
Authors: Boniecki Marek , Jakieła Rafał , Librant Zdzislaw , Wesolowski Wladyslaw , Dabrowska Danuta , Karas Agata
Published: March 2009

The superplastic flow in tetragonal zirconia polycrystals stabilised 3mol% Y2O3 (3YTZP)
is strongly affected by the dopant cations, which segregate at the grain boundary. It is
proposed that this flow is controlled by grain boundary diffusion of Zr4+ ions and therefore the
dopant cations should change the grain boundary diffusion. In order to prove this thesis the
measurements of grain boundary diffusion coefficients were made using Hf4+ ions as tracer.
Zirconia samples were doped with 1mol% of Al2O3, SiO2, MgO, MgAl2O4, GeO2 and TiO2. The
tracer was deposited on the surface of the zirconia specimens by placing several drops of hafnium
nitrate and then drying at 373 K. In this way, thin films of HfO 2 were obtained. The samples were
heated in the range 1553 – 1773 K for 1 to 24 h. The concentration versus depth profiles were
measured using secondary ion mass spectrometry (SIMS). Calculated hence grain boundary
diffusion coefficients were several times bigger for doped samples than for pure 3Y-TZP samples.
Annealing Effects on Toughened Intra-Type Nanocomposites
Authors: Awaji Hideo , Choi Seong Min
Published: March 2009

Intra-type nanocomposites, in which nanosized second-phase particles are embedded
within matrix grains, generate dislocations around the dispersed nanoparticles. The intra-type
nanostructure induces a thermal expansion mismatch between the matrix and the dispersed particles,
which will yield nanoscale stress distribution around the particles and generate lattice defects, such
as dislocations. The dislocations of ceramics can be generated at elevated temperatures, become
sessile dislocations at room temperature, and serve as nanocrack nuclei in highly stresses fields, e.g.
at a main crack tip. The frontal process zone size ahead of a crack tip is expanded due to creation of
nanocracks and hence the fracture toughness is improved. Annealing after sintered nanocomposites
is important in controlling the dislocation activities. Appropriate annealing will disperse
dislocations into the matrix grains. However, dislocations are sensitive to temperature, and higher
temperature or longer annealing time result in dislocation disappearance and cause the reduction of
the strength and fracture toughness of nanocomposites. In this study, commercially available
γ-alumina agglomerated powder with high porosity was used to create the intra-type nanostructure.
Nickel nitrate solution was infiltrated into nanopores of the γ-alumina agglomerates in vacuum. The
alumina/nickel composite powder following reduction in hydrogen atmosphere was sintered using a
pulse electric current sintering method. The volume fraction of nickel was about 3 vol %. After
appropriate annealing, the highest fracture toughness was obtained to be 7.6 MPam1/2, which is two
times higher than that of monolithic alumina.
Processing and Sintering of Alumina-YAG Nanocomposites
Authors: Palmero Paola , Montanaro Laura
Published: March 2009

The elaboration of 50 vol.% Al2O3/YAG (Y3Al5O12) nanocomposites was pursued by comparing
two processing routes. In one case, a composite powder was firstly synthesized via reverse-strike
co-precipitation and then submitted to an optimized thermal and extensive milling pre-treatment
prior to sinter. In the second case, a pure-alumina precursor was prepared via reverse-strike
precipitation and then doped with an yttrium salt solution; such doping procedure was performed on
alumina samples submitted to several thermal and/or mechanical pre-treatments carried out to yield
more or less relevant α-phase amounts. The optimization of the thermal/mechanical pre-treatment
of the former powder led to a very homogeneous, dense and fine microstructure, made of α-alumina
and YAG grains of about 300 nm in size. On the contrary, sintered bodies characterised by a larger
mean grain size and a lower homogeneity in microstructure were obtained by using the second
starting powder, even if, also in this case, a suitable control of the powder processing can allow a
promising improvement of the microstructural features.
Computational Phase Studies of Oxide Ceramics
Authors: Zinkevich Matvei
Published: March 2009

This paper shows how phase equilibria and thermodynamic properties of various
multicomponent oxide systems can be represented with the use of model equations for the Gibbs
energies of all phases as functions of temperature and composition. Starting from the stoichiometric
phases and random solutions, the complexity of the models increases tremendously when ordering
tendencies or certain defects in the lattice of ionic crystals, such as vacancies and/or variable
oxidation states have to be taken into account.
Sintering of Dense Silicon Nitride Ceramics at Low Temperature
Authors: Bressiani José Carlos , Genova Luis Antonio
Published: March 2009

Densification curves of silicon nitride specimens with varying composition were
determined with the aid of a dilatometer and these curves are presented in this paper. A novel
procedure has been used to determine the densification curves as well as the temperature at which
the rate of densification was highest. From these data, sintering profiles have been proposed to
produce silicon nitride based ceramics with high apparent density (above 96% of theoretical
density) at temperatures as low as 1520º C, with incipient grain growth. This procedure also enabled
efficient separation of the densification and grain growth phenomena and it can be used in other
two-step sintering studies.
Corrosion Behaviour of Structural Ceramics in Supercritical Water
Authors: Nagae Masahiro , Yoshio Tetsuo , Oda Kohei
Published: March 2009

The corrosion behavior of Si3N4, SiC, mullite, alumina and sapphire was investigated in
supercritical water at 450 °C and 45MPa for 2 to 50h. Corrosion resistance for the ceramics was as
follows in the order; Si3N4 < SiC < mullite < alumina < sapphire. Pitting corrosion with formation of
amorphous layer and intergranular corrosion due to dissolution of additives were observed in
PLS-Si3N4 and PLS-SiC, respectively. The corrosion behavior of mullite was characterized by
dissolution of SiO2 and formation of boehmite residue layer. High purity alumina ceramics showed
the highest corrosion resistance in the ceramics. Intergranular corrosion proceeded in the alumina
ceramics and its corrosion rate was strongly dependent on the impurity content.
Thermo-Structural Analysis of Ceramic Vanes for Gas Turbines
Authors: Fersini Maurizio , Bianco R. , De Lorenzis L. , Licciulli Antonio , Pasquero G. , Zanon G.
Published: March 2009

Advanced structural ceramics such as Hot Pressed Silicon Nitride (HPSN) and Reaction
Bonded Silicon Carbide (RBSC), thanks to their low density (3.1 ÷ 3.4 gr/cm3) and to their thermostructural
properties, are interesting candidates for aerospace applications. This research investigates
the feasibility of employing such monolithic advanced ceramics for the production of turbine vanes
for aerospace applications, by means of a finite element analysis. A parametric study is performed
to analyse the influence of the coefficient of thermal expansion, the specific heat, the thermal
conductivity, and the Weibull modulus on structural stability, heat transfer properties and thermomechanical
stresses under take-off and flying conditions. A nodal point that is evidenced is the high
intensity of thermal stresses on the vane, both on steady state and in transient conditions. In order to
reduce such stresses various simulations have been carried out varying geometrical parameters such
as the wall thickness. Several open questions are evidenced and guidelines are drawn for the design
and production of ceramic vanes for gas turbines.
Advanced Machining Technology for Gas Turbine and Heat Engine Components
Authors: Pujari Vimal K. , Vartabedian Ara , Collins William T.
Published: March 2009

Cost effective ceramic manufacturing with green and dense machining perspectives has been
described. An advanced CNC green machining based complex shape forming technology
developed at Saint-Gobain is described which has been shown to be robust and capable of rapid
prototyping. Utilizing a systems approach involving green blank properties, type of cutting tools
and machining parameters the procedure has been optimized. Integral Bladed Rotors (IBR) for
microturbine applications have been fabricated with dimensional controls within 0.15% and
successfully spin tested at 143330 rpm without failure. Following this approach, a cost effective
machining and prototype fabrication procedure is under development for IBR and Vane rings
for various civilian and military applications.
Fabrication, Wear and Performance of Ceramic Cutting Tools
Authors: Vleugels Jef
Published: March 2009

The ceramic cutting tool requirements for metal machining are reviewed, taking into
account the trends in industry towards dry high-speed cutting and the need for tools with complex
geometry. The emphasis will be on bulk materials rather than on coatings and most attention will be
devoted to machining of iron-based alloys (steels). In the development of new tool materials,
special attention should be given to the chemical matching of tool and workpiece material at
elevated temperatures. The chemical compatibility of the tool-workpiece combination can be
investigated by means of static interaction couples at elevated temperatures, which have been
exposed for times long enough to be able to characterise the interaction layer. Complementary to
the experimental investigation, the chemical compatibility of tool and workpiece materials can be
predicted from thermodynamic equilibrium solubility calculations of tool materials in a selected
workpiece material. Taking into account the mechanical properties needed, new ZrO2-based
composites were defined based on the thermodynamically estimated chemical stability. The
selection, development and proof testing of the new ZrO2-based composites is highlighted and their
wear behaviour and performance in high speed dry turning of construction steel is compared with
that of state-of-the-art cutting tool materials.
Corrosion Behaviour of Vitrified Heavy Metals from Industrial Waste
Authors: de Mello-Castanho Sonia Regina Homem , da Silva Antônio Carlos , Acchar Wilson , Segadães Ana M.
Published: March 2009

The vitrification process is an attractive route for the inertization treatment of hazardous
industrial wastes. The corrosion resistance of this kind of materials is one of the most important
requirements to ensure the long term retention of the toxic metals. In this work, silicate glasses with
various waste concentrations were obtained using a galvanic sludge from metallurgical activities
and glass forming rejects from ceramic activities. Glasses with several galvanic waste
concentrations were obtained. The corrosion behaviour of the vitrified materials under various pH
media was evaluated. The FTIR technique was used to investigate the glass structural
modifications. Glasses containing 40 wt.% galvanic waste additions show higher resistance to
corrosion media than those without waste additions.
Gas Sensing Properties of TiO2 and SnO2 Nanopowders Obtained through Gel Combustion
Authors: Deorsola Fabio A. , Mossino P. , Amato Ignazio , DeBenedetti Bruno , Bonavita A. , Micali G. , Neri G.
Published: March 2009

Nanostructured semiconductor metal oxides have played a central role in the gas sensing
research field, because of their high sensitivity, selectivity and low response time. Among all the
processes, developed for the synthesis of nanostructured metal oxides, gel combustion seems to be
the most promising route due to low-cost precursors and simplicity of the process. It combines
chemical gelation and combustion, involving the formation of a gel from an acqueous solution and
an exothermic redox reaction, yielding to very porous and softly agglomerated nanopowders.
In this work, nanostructured tin oxide, SnO2, and titanium oxide, TiO2, have been synthesized
through gel combustion. Powders showed nanometric particle size and high specific surface area.
The so-obtained TiO2 and SnO2 nanopowders have been used as sensitive element of resistive λ
sensor and ethanol sensor respectively, realized depositing films of nanopowders dispersed in water
onto alumina substrates provided with Pt contacts and heater. TiO2-based sensors showed at high
temperature good response, fast response time, linearity in a wide range of O2 concentration and
long-term stability. SnO2-based sensors have shown high sensitivity to low concentrations of
ethanol at moderate temperature.
Solid Oxide Fuel Cells: Status, Challenges and Opportunities
Authors: Singhal Subhash C.
Published: March 2009

A solid oxide fuel cell (SOFC) electrochemically converts chemical energy of a fuel into
electricity at temperatures from about 650 to 1000oC. SOFCs offer certain advantages over lower
temperature fuel cells, notably ability to use CO as a fuel rather than being poisoned by it, and high
grade exhaust heat for combined heat and power, or combined cycle gas turbine applications. This
paper reviews the operating principle, materials for different cell and stack components, cell
designs, and applications of SOFCs. Among different designs of solid oxide fuel cells (SOFCs), the
electrical resistance of tubular SOFCs is high, and areal power density (W/cm2) and volumetric
power density (W/cm3) low. Planar SOFCs, in contrast, are capable of achieving very high power
densities.
Hydrothermal Synthesis of Advanced Ceramic Powders
Authors: Suchanek Wojciech L. , Riman Richard E.
Published: March 2009

This paper briefly reviews hydrothermal synthesis of ceramic powders and shows how
understanding the underlying physico-chemical processes occurring in the aqueous solution can be
used for engineering hydrothermal crystallization processes. Our overview covers the current status
of hydrothermal technology for inorganic powders with respect to types of materials prepared, ability
to control the process, and use in commercial manufacturing. General discussion is supported with
specific examples derived from our own research (hydroxyapatite, PZT, -Al2O3, ZnO, carbon
nanotubes). Hydrothermal crystallization processes afford excellent control of morphology (e.g.,
spherical, cubic, fibrous, and plate-like) size (from a couple of nanometers to tens of microns), and
degree of agglomeration. These characteristics can be controlled in wide ranges using
thermodynamic variables, such as reaction temperature, types and concentrations of the reactants, in
addition to non-thermodynamic (kinetic) variables, such as stirring speed. Moreover, the chemical
composition of the powders can be easily controlled from the perspective of stoichiometry and
formation of solid solutions. Finally, hydrothermal technology affords the ability to achieve cost
effective scale-up and commercial production.
Electrochemical Active Parts at Electrode/Electrolyte Interfaces for Solid Oxide Fuel Cells (SOFCs) by Isotope Labeling-SIMS Analysis
Authors: Horita Teruhisa , Kishimoto Haruo , Yamaji Katsuhiko , Sakai Natsuko , Xiong Yue Ping , Brito Manuel E. , Yokokawa Harumi
Published: March 2009

The electrochemical reaction of solid oxide fuel cells (SOFCs) was reviewed in terms of mass and
charge transports of reaction species around the electrode/electrolyte interfaces. Oxygen reduction
and fuel oxidation were analyzed by isotope labeling and secondary ion mass spectrometry as well as
conventional electrochemical method. The SIMS images after 18O2 (stable isotope oxygen) labeling
suggested that the O2/cathode/electrolyte interfaces were the most active parts for oxygen reduction
and incorporation. The widths of active parts of oxygen reduction were about several 100 to some
1000 nm different depending on the cathode materials and reaction mechanism. The isotope
labeling-SIMS technique was also applied to visualize the active parts for CH4 decomposition and
carbon deposition around the anode metal/electrolyte oxide interfaces. The active parts for carbon
deposition were only on the Ni surface on YSZ electrolyte. The effect of substrate oxide on the
carbon deposition was also examined at the mesh-shaped metal/oxide interfaces.
Fabrication of Components for Solid Oxide Fuel Cells by Tape Casting and Magnetic Pulsed Compaction
Authors: Spirin A. , Ivanov Victor , Lipilin Alexandr , Paranin S. , Khrustov Vladimir , Nikonov Alexey , Rempel Al. , Ivin S.
Published: March 2009

Fabrication of dense YSZ electrolytes and porous LSM cathodes in the shape of tubes
using a radial magnetic pulsed compaction of multilayered tubular blanks of powder tapes has been
investigated. The tapes were prepared with butyral resin binder. The multilayered blanks were
compacted magnetically. Magnetic pressures of 0.2-0.3 GPa in amplitude, sintering temperatures as
low as 1100-1300 °C (in air) with holding time of 20-540 min have been used. Cathode tubes of
0.2-1.0 mm thick exhibited the reproducible open porosity up to 45 %. YSZ electrolyte tubes with
the wall of 100-450 microns thick had near full relative density, 0.97-0.99, and were characterized
with grains of 200-500 nm in size on the average depending on the sintering temperature. The
electrochemical cells built up of as-prepared tubular electrolytes and traditional research electrodes
were tested under the air-hydrogen fuel cell conditions. The specific output power, 0.6 W cm-2, was
realized at temperature of 885 °C.
Pseudocapacitive Manganese Oxide Prepared by a Spray Pyrolysis/Electrostatic Deposition Technique
Authors: Yi Chen Chin , Lin Chung Kwei , Lyu Y.R. , Lin H.H. , Tuan Wei Hsing
Published: March 2009

Manganese oxide powders were prepared by spray pyrolysis from manganese acetate
solution with various pyrolysis temperatures and directly collected via high-voltage electrostatic
deposition technique (ESD). The as-prepared powders were coated onto graphite substrates by
electrophoretic deposition technique (EPD). The as-prepared powders and/or coatings were
examined by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), cyclic
voltammetry (CV), and etc. XRD data determined the phase of the as-prepared powders as
nanocrystalline Mn3O4 phase, manganese hydroxide and residual acetate. In addition, the
electrochemical characteristics of the resulting powder mixtures were examined by cyclic
voltammetry and charge/discharge cycling in electrolyte for redox supercapacitor applications.
Advanced Radiation-Resistant Ceramic Composites
Authors: Katoh Yutai , Snead L.L. , Nozawa Takashi , Morley N.B. , Windes William E.
Published: March 2009

Ceramic matrix composites (CMC’s), particularly silicon carbide (SiC) fiber-reinforced
SiC-matrix (SiC/SiC) composites, have been studied for advanced nuclear energy applications for
more than a decade. The perceived potentials for advanced SiC/SiC composites include the ability
to operate at temperature regimes much higher than heat-resistant alloys, the inherent low inducedactivation
nuclear properties, and the tolerance against neutron irradiation at high temperatures.
This paper reviews the recent research and development of the advanced radiation-resistant SiC/SiC
composites for nuclear applications. Additionally, remaining general and specific technical issues
for SiC/SiC composites for nuclear applications are discussed.
A First Principles Study of Palladium Impurities in Silicon Carbide
Authors: Roma Guido
Published: March 2009

The main task of the silicon carbide layer in Triso-coated fuel particles for gas-cooled
high temperature fission reactors is to retain fission products. It has been observed that some fission
products, and in particular Pd, attack the SiC layer and are supposed to be responsible for corrosion
of the material, which could facilitate fission products release.
We used first principles calculations based on Density Functional Theory (DFT) in order to
investigate the energetic, structural, and kinetic properties of Pd impurities inside SiC; we obtained
solution and migration energies in pure SiC and discuss the thermodynamics of a few reactions that
could possibly occur for Pd impurities in silicon carbide.