bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Sawdust Briquette: An Alternative Source of Fuel
Authors: Osarenmwinda J.O. , Imoebe S.
Published: March 2009

The production of an improved sawdust briquette, as an alternate source of fuel has been achieved. In addition to sawdust other constituents of the briquette were silica (sharp sand), starch and kerosene. The density, ash content, calorific values and moisture content of briquette were determined. The composition of starch and kerosene was constant throughout the experiment. It was observed that as silica percentage was increased, there was an increase in the briquette calorific value until maximum value of 20%. The sample which gave the best calorific value was with percentage compositions of 60% sawdust, 20% silica (sharp sand), 5% kerosene and 15% starch with a calorific value of 12.68mJ/kg .The produced briquette had a higher calorific value than wood and other agro waste it was compared with.
Bio-Treatment of Brewery Effluent Using Enzymes
Authors: Aisien F.A. , Oyakhilomen G.A. , Aisien E.T.
Published: March 2009

The feasibility of treating brewery effluent using bio-catalysts (enzymes) was investigated. Carbohydrase, lipase, protease and a mixture enzyme made of carbohydrate and lipase were used. Brewery wastewater samples were collected and analyzed for 96 hrs, at intervals of 12 hrs. The physiochemical properties: biological oxygen demand BOD, chemical oxygen demand COD, total suspended solid (TSS), total dissolved solid TDS, pH, phosphorus (PO4), ammonium nitrogen (NH4-N), total hydrocarbon (THC) were determined using APHA standard method of analysis. The concentrations of the physiochemical properties of the brewery effluent decreased with increasing biodegradation time, for the various enzymes used. However, the different enzymes gave different percentage reductions of each of the physiochemical properties. The order of percentage reduction for the enzyme systems is mixed enzyme > carbohydrase > lipase > protease > control. Hence, the mixed enzyme gave the best results of 90%, 90%, 50%, 100%, 91.6% and 100% reductions for COD, BOD, TSS, NH4-N, PO4 and THC, respectively after 96 hrs. of biotreatment. However, the control gave the least percentage reductions of 6.9%, 5.3%, 16.4%, 7.1%, 5.8% and 50.0% for COD, BOD5, TSS, PO4, NH4-N, and THC respectively.
Drinking Water Quality Monitoring in Ado-Ekiti and Environs
Authors: Folorunso O.P. , Omotoso T.
Published: March 2009

The water cycle is an obvious mode of transmission of enteric diseases. Bacteriologically polluted water is potentially dangerous to health because of possible outbreak of typhoid, dysentery and cholera epidemics. In this paper major sources of drinking water in Ado Ekiti and its environs were examined for physical, chemical and biological qualities. These consists of wells in Adebayo, Ajilosun, Odo-Ado and other suburbs; most popular sachet waters (pure water) produce in Ado- Ekiti and the Pipe-borne water from the state water cooperation (Ureje treatment plants). The results were analyzed using t-distribution method of data analysis and World Health Organization (WHO) Standard was applied. The wells were found to be a little more acidic. All the samples showed high calcium content and some gave total hardness value above WHO standard. 70% of the samples, failed bacteriological test. Samples examined give a wider coverage of drinking water sources in Ado-Ekiti, Ekiti State.
Differential Evolution Based Optimal Tuning of Load Frequency Controller
Authors: Inyanda A.K. , Bakare G.A. , Kunduli M.
Published: March 2009

Load Frequency Controllers (LFC) are required to maintain constant power and frequency in inter-connected power generating systems. Differential Evolution (DE) based optimal tuning of load frequency controller of two area inter-connected power system is presented in this paper. The proposed method optimizes the parameter of Integral controller by selecting the optimal gain which drives the change in frequency in the two areas and change in tie-line power flow to zero within the shortest time span. Simulation results on two networks revealed that the proposed controller dampened the frequency oscillations and restores the system frequency and tie-line power to set value after a step load disturbance.
Performance of Binary Phase Shift Keying (BPSK) and Quartenary Phase Shift Keying (QPSK) Signalling Schemes in Fast and Frequency Non-Selective Rayleigh Fading Channel with a Decision Feedback Equalizer (DFE) at the Receiver
Authors: Raji T.I. , Adeyemo Z.K.
Published: March 2009

In this paper, we study the performance of Binary phase shift keying (BPSK) and Quartenary phase shift keying (QPSK) modulation signalling over fast and frequency non-selective Rayleigh fading channel with mobile digital communication and usually a decision feedback equalizer (DFE) at the receiver. Mobile communication is generally a complex process in which the input modulated signals propagate to the receiver over many different paths resulting in what is known as multipath propagation. Its main effects are delay spread and Doppler spread. These effects result in the channel being classified as fast and frequency non selective. Performances in terms of Bit Error Rate (BER) with respect to the Signal-to-Noise Ratio (SNR) at different selected velocities of 10, 40, 70 and 100km/hr are investigated with Adaptive Equalizer. Simulation results are obtained using MATLAB 7.0 programming language. The results indicate that at all the velocities considered; there is an excessive degradation in the BER performance due to fading with both the BPSK and QPSK modulation schemes. However, the BER improves for BPSK modulation signalling scheme when a decision feedback equalizer is used at the receiver
Effects of Gun Tube Profile and Sabot on Stresses and Velocity of Long Rod Penetrator
Authors: Kim J.B.
Published: March 2009

The paper describes the combined influences of the forward sabot diameter, sabot modulus, and L/D on the stress of the projectile rod traveling in the gun tube. Three types of gun tube profile were simulated. The first profile is perfectly straight. The second profile is monotonously curved tube only by gravity loads (Type A). The third is a changeful curved tube by gravity loads with imagined as-manufactures (Type B).
Three-dimensional dynamic finite element analysis method was used for the sabot/rod system transiting in a gun tube. Numerical simulation results showed that the maximum von Mises stress due to in-bore behavior of the sabot/rod system could be decreased by changing the forward sabot diameter in a type B tube. The effect of tube centerline profile on the stress of the rod was analyzed for the conditions mentioned above. The von Mises stress of the rod in the changeful curved tube is as much as 10% higher than that in the straight or monotonously curved tube.
Simulation of Multiple Hydraulic Fracturing in Non-Uniform Pore Pressure Field
Authors: Li Lian Chong , Tang Chun An , Tham Leslie George , Yang Tian Hong , Wang Shao Hong
Published: March 2009

A series of numerical simulations of hydraulic fracturing were performed to study the initiation, propagation and breakdown of fluid driven fractures. The simulations are conducted with a flow-coupled Rock Failure Process Analysis code (RFPA2D). Both heterogeneity and permeability of the rocks are taken into account in the studies. The simulated results reflect macroscopic failure evolution process induced by microscopic fracture subjected to porosity pressure, which are well agreeable to the character of multiple hydraulic fracturing experiments. Based on the modeling results, it is pointed out that fracture is influenced not only by pore pressure magnitude on a local scale around the fracture tip but also by the orientation and the distribution of pore pressure gradients on a global scale. The fracture initiation, the orientation of crack path, the breakdown pressure and the stress field evolution around the fracture tip are influenced considerably by the orientation of the pore pressure. The research provides valuable guidance to the designers of hydraulic fracturing engineering.
A Piezoelectric Screw Dislocation Interacting with a Dielectric Crack in a Hexagonal Piezoelectric Material
Authors: Liu Jin Xi , Liu X.L.
Published: March 2009

This paper is concerned with the interaction of a piezoelectric screw dislocation with a semi-infinite dielectric crack in a piezoelectric medium with hexagonal symmetry. The solution of the considered problem is obtained from the dislocation solution of a piezoelectric half-plane adjoining a gas medium of dielectric constant ε0 by using the conformal mapping method. The intensity factors of stress, electric displacement and electric field and the image force on the dislocation are given explicitly. The effect of electric boundary conditions on the dislocation-crack interaction is analyzed and discussed in detail. The results show that ε0 only influences the electric displacement and electric field intensity factors and the image force produced by the electric potential jump.
Self-Propagating High-Temperature Synthesis of Carbide- and Boride-Aluminides
Authors: Matsuura Kiyotaka , Hikichi Yusuke , Obara Yuki
Published: March 2009

TiC- and TiB2-FeAl composites have been produced using the Self-propagating
High-temperature Synthesis (SHS) method under Pseudo Hot Isostatic Pressing (PHIP). When
mixtures of the elemental powders were heated to a temperature near the melting point of Al under
a PHIP of 150 MPa, the powder mixtures exothermically reacted and produced TiC particle
dispersed and TiBB2 particle dispersed FeAl-matrix composites. As the volume factions of TiC and
TiB2 particles increased from 0.3 to 0.8, the average particle size increased from approximately 1
to 10 μm and the average Vickers hardness increased from approximately 600 to 1600 in both the
TiC-FeAl and TiB2-FeAl systems. The application of the PHIP remarkably reduced the porosity of
the SHS products. Preheating of the elemental powder mixtures at 773 K for 30 minutes also
reduced the porosity. Moreover, the preheating reduced the particle size in the SHS products. It
was suggested that degassing of the powder surfaces and mutual diffusion between the different
powders should have occurred during the preheating, which led to reduction in pore formation and
reduction in heat generation at the SHS reactions, respectively.
SHS Oxide Catalysts: Synthesis, Properties and Applications
Authors: Xanthopoulou Galina , Vekinis George
Published: March 2009

Over the last 30 years, the SHS method has been used to produce a range of very active catalysts
with a range of compositions (borides, carbides, nitrides, oxides, intermetallides, metals on carriers)
for various chemical processes. Physico-chemical properties of each composition were regulated by
control of the SHS process parameters. Such SHS catalysts have been examined over a range of
compositions and reaction temperatures and the processing conditions were optimised for each
particular process, which included: oxidation of CO, H2, soot, hydrocarbons, organic acids,
aldehides, alcoholes, deep methane oxidation, dehydrogenation, pyrolysis of diesel, naphta and
petrol, oxidative dehydrodimerization of methane, hydrogenation, isomerization, cracking,
production of synthesis gas, synthesis ammonia and other processes. The activity of many of the
materials developed is substantially better than many of commercial catalyst systems and SHS
catalysts used in industry. We herein present a review of some of the most important SHS oxide
catalytic systems produced worldwide with particular emphasis on the optimization of properties
via control of SHS processing and discuss important industrial and environmental applications.
Laminated and Functionally Graded Ceramics by Electrophoretic Deposition
Authors: Van der Biest Omer , Vandeperre L. , Put Stijn , Anné Guy , Vleugels Jef
Published: March 2009

Electrophoresis is the effect that when an electric field is applied to a suspension of a
powder in a liquid, the powder particles move under influence of this field. Frequently the powder
particles also deposit at one of the electrodes. The form of the electrode determines the form of the
deposit, hence shaping is possible. The current insights into the science and technology of
electrophoretic deposition (EPD) will be summarized. EPD is well suited for shaping layered
microstructures (laminates), by simply changing repeatedly between two or more suspensions
during deposition. Tubular laminates consisting of silicon carbide layers and crack deflecting
graphite interlayers have been produced. These tubes demonstrate an enhanced fracture energy and
a gradual mode of failure. Another area of advanced ceramics where the use of EPD makes sense
are functionally graded materials (FGM) in which one tries to combine in one component high
hardness and high toughness. EPD allows the formation of FGM by depositing from a powder
suspension to which a second suspension is continuously added during the process. An example
will be shown of a graded WC-Co hardmetal.
FGM's for Biomedical Applications
Authors: Watari Fumio , Liao Susan , Yokoyama Atsuro , Omori Mamoru , Ohata Noboru
Published: March 2009

Functionally graded materials (FGM) were fabricated for bio-medical applications,
(1) implants, (2) dental core and post, (3) guided tissue regeneration (GTR) membranes.
(1) FGM implants of Ti/HAP and TiN/HAP with the concentration changing gradually in the
longitudinal direction of cylinder were fabricated to optimize both mechanical properties and
biocompatibility in each region. Concentration gradient was formed by packing of dry powders into
mold. Spark plasma sintering was effective for sintering of non-uniform composition in FGM. Brinel
hardness decreased gradually from Ti part to HAP part, which contributes to stress relaxation in the
implanted region of bone. In vivo tests showed that osteogenesis and maturation is more advanced in
the HAP rich region.
(2) FGM dental core and post made of composite resin was fabricated by laser lithography, one
of the photo-curing type CAD/CAM systems. The elastic modulus changed gradually from 10.6GPa
in core part to 2.9GPa at the apex of post by decreasing the filler content of ceramic powders from
64% to 0% in polymer matrix. Stress analysis using finite element method showed the stress
relaxation by further 30 % in FGM, compared with the uniform composite resin.
(3) Biodegradable GTR membrane composed of nano HAP/collagen reinforced with PLGA was
prepared. The membrane has the three layer structure with the thickness of about 100μm for each
where the composition of HAP/collagen is increased from pure PLGA. The graded membrane
structure could give the different functions of the high degradation speed and Ca ion release to
enhance osteoconductivity for bone remodeling in the high HAP/collagen side and the relatively low
degradability to prevent the ingrowth of fibroblasts in the pure PLGA side.
Atmospheric Pressure Plasma-Enhanced CVD for Surface Modification: Principles and Applications
Authors: Hitchman Michael L. , Alexandrov Sergei E.
Published: March 2009

This review gives an overview of the characteristics of various non-thermal, nonequilibrium
plasmas and outlines results of AP-PECVD with dielectric barrier discharges.
Improved Mechanical Properties by Nanoreinforced Ceramic Composite HVOF Coatings
Authors: Turunen Erja , Varis Tommi , Keskinen Jari , Fält Teppo , Hannula Simo Pekka
Published: March 2009

Special nanoreinforced ceramic composite coatings were produced. Dense nanostructured
alumina and chromia coatings alloyed with various nanofraction elements such as Ni, NiO, ZrO2 and
SiC were manufactured by HV2000
HVOF spraying. As a result coatings with nearly 100%
improvements relative fracture toughness, were produced.
Structure and Properties of α+β Titanium Alloy - TixAly Intermetallic Phases Laminate Composite
Authors: Wierzchon T. , Ossowski M.
Published: March 2009

The rapid progress in engineering enhances the demands set on materials requiring better
mechanical properties, resistance to frictional wear, resistance to corrosion and erosion etc. These
demands can be satisfied by e.g. applying various surface engineering techniques which permit
modifying the microstructure, phase and chemical composition of the surface layers of the treated
parts. By subjecting a laminate composite: α+β titanium alloy - TixAly intermetallic phases
produced by diffusion bonding of titanium alloy and aluminum with the hybrid surface treatment
that consists of magnetron sputtering and glow discharge assisted oxidizing or by the glow
discharge nitriding process we can produce a composite built of several zones arranged in the
following sequence: Al2O3/ TixAly intermetallic phases/titanium alloy/TiAl3/ titanium alloy/ TixAly
intermetallic phases/ Al2O3 or TiN+αTi(N)/ titanium alloy/ TiAl3/ titanium alloy/αTi(N) +TiN.
The paper presents the structure, phase composition and properties such as the resistance to
frictional wear and to corrosion of a new constructional material - a laminate composite Ti –Al with
diffusion surface layers, which widen significantly the application range of titanium alloys.
Surface Micromachining of Polyureasilazane Based Ceramic-MEMS Using SU-8 Micromolds
Authors: Fakhfouri Vahid , Jiguet Sébastien , Brugger Juergen
Published: March 2009

We describe a novel surface micromachining process for the fabrication of ceramic-type MEMS devices, such as free-standing cantilevers, that is based on the use of high-aspect ratio micromolds of SU8 and aluminum as sacrificial layer. 250μm-high and 100-1000μm-wide molds were used to confine a liquid precursor of SiC/Si3N4 based ceramics on the sacrificial layer that enables the detachment of the green body before the pyrolysis step at 1000°C. The final ceramic cantilever has dimensions ranging from 100-500μm x 1-2mm x 50μm and a smooth surface. Details of the processing, structural and material characterization such as Dynamic Rheological and Thermogravimetric Analysis under UV will be presented and compared to those found in the literature.
Microstructural Aspects of Ceramic-Metal Composites Performance in Erosive Media
Authors: Hussainova Irina , Antonov Maksim , Volobueva Olga
Published: March 2009

Solid particle erosion tests were conducted on WC-, TiC-, and Cr3C2 - based ceramicmetal
composites (cermets) to study their performance in erosive media. The overall objectives of
this study are: (i) to improve our current understanding with regards to the influence of intrinsic
properties on wear behavior of cermets, (ii) to estimate an influence of metallurgical features during
cermets fabrication on resistance to fracture; (iii) to consider micromechanical aspects of cermets
durability; and (iiii) to offer the criteria of material reliability in different erosive conditions. For
this reasons, microstructure of multiphase materials, fracture mechanisms, ability of energy
dissipation and thermo-mechanical parameters and erosion resistance were analyzed.
Magneto-Photonic and Magnonic Crystals Based on Ferrite Films - New Types of Magnetic Functional Materials
Authors: Nikitov S.A. , Filimonov Yu A. , Tailhades Ph.
Published: March 2009

A new type of photonic crystals entitled “magnonic crystals (MC)” that exhibit forbidden
gaps in the microwave spectrum of magnetostatic spin waves (MSW) are reported. The topography
of the MCs that consist of two-dimensional (2-D) etched holes periodic structure in yttrium iron
garnet films was studied by atomic force and magnetic force magnetometry. The propagation
characteristics of spin waves in such 2-D MCs was measured and analyzed.
Tailoring the Properties of Ceramic-Based Composites Using Co-Extrusion Processing
Authors: Hilmas Greg , Watts Jeremy
Published: March 2009

Co-extrusion processing is a powder-based forming method that uses the
simultaneous ram extrusion of two or more materials to form multi-phase systems
with functionally designed architectures. A functionally designed material has
functional properties that are specifically tailored for an application by changing the
macrostructure (100’s of microns) with little or no change in overall composition.
Thus, co-extrusion can be used to improve the functional properties of composite
materials, with or without a concurrent boost of its intrinsic properties. An example
of a functionally designed material with a coaxially co-extruded architecture, known
in the ceramic field as a “fibrous monolith”, has elongated cells of a major (70-90
vol.%) phase surrounded by cell boundaries of a minor (10-30 vol.%) phase. A
variety of strong-phase/weaker-phase combinations have been demonstrated,
including Si3N4/BN, SiC/graphite, SiC/BN. Several wear resistant-phase/ductilephase
combinations have also been studied, including Diamond(Co)/WC(Co) for use
in the petroleum drilling industry. The presentation will cover co-extrusion
processing as a technology, applications that are being considered or are in production
for most of the latter materials combinations, and a discussion of the functional
properties that can be achieved using co-extrusion as a means to create functionally
designed materials.
Ceramic Matrix Composite with Increased Thermal Conductivity
Authors: Ichard J.C. , Pailler R. , Lamon Jacques
Published: March 2009

The purpose of the study was to increase the thermal conductivity of multilayered and
self-sealing ceramic matrix composites via the silicon melt infiltration process.
The first step of the process consisted in filling porosity using various organic xerogels by the
sol-gel route. Carbon xerogels obtained by subsequent pyrolysis may reduce and homogenize the
porous network within the composite. Cracking of the xerogels due to volumic shrinkage
occurring during air drying may be decreased by controlling the initial parameters as concerns
the gel solution and/or by operating a second impregnation/pyrolysis step.
Filling of such composites by liquid silicon revealed that a specific route and particular
conditions are necessary to eliminate porosity by controlling gas production species from pore
surface at high temperature. This may be achieved through a directional flow and using highly
viscous silicon (thanks to a localized wick), and by keeping the sides of the materials permeable
to gas.
This led to composite materials with a thermal conductivity which was four times as high as that
of those materials densified via CVI. An increase in mechanical properties was also observed.
Fatigue and Creep Behaviour of a SiCf/SiC Composite for Nuclear Fusion Reactor Applications
Authors: Trentini E. , Riccardi B. , Labanti M.
Published: March 2009

This study presents the results of mechanical tests of commercial 2D SiCf/SiC ceramic
matrix composite for fusion reactors applications.
The creep behaviour was investigated by means of flexural constant load stress-rupture tests, in
controlled atmosphere at 600 and 1000°C. The creep strain and time to failure vary with applied load
according to a power law. Cyclical tests at room temperature and at high temperature showed that
the material has a good fatigue behaviour at room temperature, as no evident fatigue damage was
detected after 80.000 cycles at a peak load up to 98 % of MOR. Conversely at high temperature
(1000°C) the specimens showed a progressive compliance increase and limited cycles to failure even
at peak load as low as 40 % of MOR. Creep phenomena seem to influence the fatigue behaviour.
Creep strain analysis, crack growth and fracture surface observations allowed to investigate the
mechanisms that affect the crack propagation, the fracture process and the rupture life under cyclic
loading and under constant stress loading at different temperatures.
Ceramic Composites and Thermal Protection Systems for Reusable Re-Entry Vehicles
Authors: Valente Teodoro , Bartuli Cecilia , Pulci Giovanni
Published: March 2009

Next generation of reusable launch vehicles and new hypersonic space vehicle concepts are currently under development, moving from traditional aerodynamic configuration towards slender profiles. Main expected benefits are reduction of drag, enhancement in lift-to-drag ratio and reduction of interferences with radio frequency transmissions during the re-entry. Flexibility in designing sharp profiles is strictly conditioned to the availability of suitable materials and processing technologies, required to fabricate components and surfaces able to withstand higher heat fluxes induced by the new profiles. Advances in the field of CMC's for high temperature structures and TPS are the basis for innovative approaches to the design of future RLV's. Beside baseline solutions, already available and well characterized, as for C/SiC CMC's, ultra high temperature ceramics seem to offer the right chance to fabricate hot structures having the required heat-resistant and load carrying capabilities. This paper deals with technologies based on the use of diboride based CMC's which can be considered promising candidate materials for the fabrication of hot structures of slender bodies, such as nose cap and wing leading edges. Recent experimental results will be presented and discussed.
Diffusion of Metallic Species and their Influence on Interfacial Reactions in Glass-Ceramic-to-Metal Seals
Authors: Donald Ian W. , Metcalfe Brian L. , Gerrard Lee A. , Fong Shirley K.
Published: March 2009

This is a preliminary investigation aimed at assessing the influence of
individual metallic elements on the sealing characteristics of glass-ceramic-to-metal
seals in order to aid in the analysis of interfacial reactions in more complex practical
alloy systems. In the present study, a lithium zinc silicate (LZS) glass nucleated with
P2O5 has been sealed to high purity Fe, Ni and Cr metals and the resultant diffusion into
the glass of each metal monitored as a function of sealing temperature and time. The
initial data obtained are compared with similar data noted for multi-component alloys.
Transient-Liquid-Phase and Liquid-Film-Assisted Joining of Ceramics
Authors: Hong S.M. , Akashi T. , McKeown J.T. , Sugar J.D. , Bartlow C.C. , Glaeser Andreas M.
Published: March 2009

Transient-liquid-phase (TLP) joining and liquid-film-assisted joining (LFAJ) exploit thin
metallic films that melt at relatively low temperatures as part of a multilayer, multimaterial
interlayer to enable joining at reduced temperatures. These methods are attractive for assemblies
that include temperature-sensitive components, however, unlike conventional low-temperature
joining methods, they also offer the potential for service at temperatures approaching or even
exceeding the original joining temperature. In successful TLP joining and LFAJ, the wetting
behavior of the liquid plays a critical role. In TLP joining, the liquid ultimately disappears during
joining due to interdiffusion and chemical homogenization. In contrast, in LFAJ the liquid persists
at the joining temperature, provides a high-diffusivity transport path that accelerates joint
formation, and ultimately undergoes a morphological transition that disrupts the initially continuous
film. The resulting isolated liquid droplets solidify on cooling. Current studies of these joining
methods are described, and promising future directions are indicated.
Effect of Dense Layer Formation on Dissolution Rate of MgO-C Refractory in Molten Slag
Authors: Sunayama Hiroyuki , Kawahara Masayasu
Published: March 2009

The corrosion test for magnesia-carbon refractory, MgO-C, with dense layer has been
carried out by a rotating cylinder method at 1673 K. The specimen, which was a cylinder of 25
mm diameter and 25mm height, was rotated in molten slag at 50 rpm. The chemical composition
of slag was CaO-SiO2-FeO-MgO-CaF2. The corrosion rate was determined by the variation of
radius of the cylindrical specimen against corrosion time. The decrease of radius was obtained by
a calculation of dissolved MgO into the slag. In addition, the diameter of the specimen was
measured with a slide calipers after the corrosion test. The cylindrical specimen was heated to
form a dense layer before the corrosion test. The corrosion rate of the MgO-C refractory with
dense layer was slower than that of the MgO-C refractory without dense layer. The oxidized layer,
where the dense layer formed, dissolved at much the same rate as the MgO brick. The dense layer
probably obstructed contact between slag and carbon in the matrix, and then oxidation of C by
slag did not take place. Formation of the dense layer was effective to inhibit corrosion of MgO-C
refractory by molten slag.
Application of Fractal Geometry to Fracture Forensics, Research and Production
Authors: Mecholsky Jr. J.J.
Published: March 2009

The fracture surface records past events that occur during the fracture process by
leaving characteristic markings. The application of fractal geometry aids in the interpretation and
understanding of these events. Quantitative fractographic analysis of brittle fracture surfaces
shows that these characteristic markings are self-similar and scale invariant, thus implying that
fractal analysis is a reasonable approach to analyzing these surfaces. The fractal dimensional
increment, D*, is directly proportional to the fracture energy, γ, during fracture for many brittle
materials, i.e., γ = ½ E a0 D* where E is the elastic modulus and a0 is a structural parameter. Also,
D* is equal to the crack-size-to-mirror-radius ratio. Using this information can aid in identifying
toughening mechanisms in new materials, distinguishing poorly fabricated from well prepared
material and identifying stress at fracture for field failures. Examples of the application of fractal
analysis in research, fracture forensics and solving production problems are discussed.
Electro-Stimulated Piezo-Spectroscopy for Measuring Nano-Scale Residual Stress Fields in Ceramics
Authors: Pezzotti Giuseppe , Leto Andrea , Yamada Kiyotaka , Porporati Alessandro Alan
Published: March 2009

Electro-stimulated piezo-spectroscopy (PS) can be quantitatively used for obtaining
information about applied and residual stress fields piled up in ceramic materials and devices. PS
experiments can be conducted in a field-emission-gun scanning electron microscope (FEG-SEM)
equipped with a high spectral resolution cathodoluminescence (CL) spectrometer. Micromechanical
information can be thus added to the microscopic crystallographic and chemical information already
available in conventional SEM devices. Independent of the physical mechanisms behind CL
emission, the spectral position of selected bands in ceramics is shown to possess high stress
sensitivity. In addition, given the high scanning flexibility and spatial resolution of the electron
beam, residual stress assessments can be performed on relatively large areas with significantly
improved spatial resolution as compared with the more popular photo-stimulated PS approach (i.e.,
using a laser beam as the excitation source). In this paper, we first quantitatively characterize the
stress dependence of the spectroscopic bands observed in ruby. Then, based on this knowledge, an
application is shown of bi-dimensional residual stress mapping around an indentation print.
Strengthening of ZrO2 Ceramics due to Nano-Crystallization
Authors: Morita Koji , Hiraga Keijiro , Kim Byung Nam , Yoshida Hidehiro
Published: March 2009

The fracture strength σf of ZrO2-based ceramics tends to increase with decreasing grain
size d. As compared with the data for submicrometer-grain-sized material with d ≈ 350 nm,
nano-crystallization of ZrO2 ceramics less than d ≈ 90 nm can improve σf by a factor of 2.0-2.5. The
maximum strength reaches σf ≈ 2500 MPa, which is classed as the highest σf of oxide ceramic
materials. The high σf can be associated with an increase in the critical t →m transformation stress and
a decrease in the flaw size due to nano-crystallization.
Sintering of Silicon Carbide Ceramics with Additives Based on the (Y2O3-Al2O3-SiO2) System
Authors: Marchi J. , Bressiani José Carlos , Bressiani Ana Helena A.
Published: March 2009

The sintering behavior of silicon carbide using alumina, silica and yttria as additives was
investigated. Powders containing 90 vol. % SiC and 10 vol. % additives (keeping 1Y2O3:1Al2O3
molar ratio) were sintered at 1950°C/1h, in a dilatometer or a graphite resistance furnace. Thermal
treatments were also done from 1500°C/1h up to 1800°C/1h, in order to evaluate the formation of
transient crystalline secondary phases. The sintered samples were characterized through XRD, SEM
and TEM analysis. The results showed that sintering behaviour is clearly related to the additive
composition investigated, as demonstrated by linear shrinkages and linear shrinkages rate curves.
Temperatures of particle rearrangment, solution-reprecipitation of SiC grains, as well as secondary
crystalline phase(s) formation and dissolution could be revealed after dilatometric analysis. These
temperatures are in good agreement with XRD results. Microstructural observations through SEM
and TEM analysis are also related to the sintering behaviour.
Restructuring of Nuclear Oxide Fuel under High Burnup Irradiation
Authors: Kinoshita Motoyasu
Published: March 2009

The ceramics fuel of UO2, irradiated in power reactors, has restructuring at high burnup,
around 70MWd/kgU, which is near in the scope of future fuel utilization with improving economy.
The original grains are divided into sub-grains of 100 nm scale and segregation of fission gas (Xe, Kr)
grows bubbles resulting in volumetric swelling of the fuel. This restructuring was investigated in the
field of nuclear engineering of power reactor fuel industry. This presentation briefly provides
observations of this restructuring and some of engineering consequences. In a mechanism study a
new approach, combing accelerator irradiation and computational science has been started and some
of initial results are presented.
Preparation and Characterization of Copper-Doped Tin Oxide Nanopowder via Hydrothermal Route
Authors: Zhou Dong Xiang , Liu Huan , Gong Shu Ping
Published: March 2009

Copper-doped tin oxide nanopowder has been synthesized via the hydrothermal route, in
which pure metallic Sn, diluted nitric acid solution and Cu(NO3)2 are used as the starting materials.
The hydrothermal treatment at about 200°C for 10 h results in rutile crystalline SnO2 particles with a
narrow size distribution typically in the range of 3~6 nm. The average crystallite size of 5 wt%
CuO-doped SnO2 particles remains smaller than 12.5 nm even after annealing at 800°C. The
evaluation of the sensitive properties of the synthesized powder with various amount of CuO doping
is conducted on the thick-film samples fabricated by screen-printing method. The high sensitivity
toward H2S as shown by the sensor test results show the possibility of using this material for gas
sensor fabrication.
Application of Protonic Conduction in Perovskite-Type Oxides: Mixed Proton-Electron-Conducting Membrane for Hydrogen Separation
Authors: Matsumoto Hiroshige
Published: March 2009

Hydrogen separation is one of the key techniques for the forthcoming hydrogen economy.
This paper describes a possible electrochemical method and materials for hydrogen separation: mixed
proton-electron-conducting membrane that can permeate hydrogen selectively from
hydrogen-containing gases, such as reformed gases of hydrocarbons. Proton-conducting
perovskite-type solid electrolytes are first introduced as the base material of the mixed conductor.
Some transition metal-doped perovskites are shown to have a mixed conductivity of protonic and
electronic charge carriers, revealed by electrochemical and X-ray-spectroscopic measurements.
Catalytic and Electrical Properties of Electrochemical NOx Reduction System
Authors: Yamaguchi Toshiaki , Kato Yuko , Kikuta Koichi , Suzuki Toshio , Fujishiro Yoshinobu , Awano Masanobu , Hirano Shin Ichi
Published: March 2009

The catalytic and electrical properties of an electrochemical NOx reduction system were
investigated. A power above 3.5W/cm2 reduced more than 60% of NOx to N2 over the
(La,Sr)CoO3-α/Ce0.9Gd0.1O1.95/Pt laminated system in a temperature range of 450°C to 650°C. O2-
transportation removed the oxygen around the cathode layer through the Ce0.9Gd0.1O1.95 electrolyte
layer, then NO was able to decompose to N2 at the cathode. This ceria-based system exhibited
stable NOx reduction with respect to electrical power, regardless of operating temperature.
Development of Waste-Containing Malayaite Ceramic Pigments
Authors: Costa G. , Ribeiro M.J. , Trindade Tito , Labrincha Joao A.
Published: March 2009

The preparation of ceramic pigments using industrial waste, a galvanizing sludge from
the Cr/Ni plating process, as primary source is here reported. The ceramic pigments were prepared
using the common solid state reaction process, investigating the optimal formulation, milling and
firing conditions. The main focus will be given on the synthesis of chrome-tin red malayaite
Ca(Cr,Sn)SiO5 pigment that was fully characterised and then tested in a standard ceramic glaze.
Typical working conditions and colour development will be also reported.
Rheological and Thermomechanical Behaviour of Steel Fiber Reinforced Carbon Containing Castables
Authors: Rigaud Michel , Balamurugan Kumarasamy , Sankaranarayanane Kannabiran
Published: March 2009

Rheological test results on alumina-magnesia castables, containing extruded flake
graphite pellets, as well as steel fibers are considered at first. After being fired at different
temperatures, thermomechanical properties of such castables containing either carbon steel or
stainless steel fibers have been determined, at room temperature, as well as at temperatures up to
1100°C. Those results indicate that the use of fibers improves the performances of carbon
containing castables at intermediate temperatures (800 º - 1100 °C), increasing the work of fracture
by 50% at 1100 °C and by 10 fold at room temperature.
Modelling High Temperature Refractory Structures for the Glass Furnace
Authors: George Simon D. , Cronje Marius , Farn S.M.
Published: March 2009

The importance of modelling as a tool in the design of both refractory structures and
materials is considered. Both bulk refractory structures as well as refractory microstructure are
considered. Whilst computational models are emphasised, contrasts and synergy between physical
and computational modelling are drawn. It is shown that the range of structures, materials and
environments that can be considered as part of a design process is vastly increased by the use of
models.
Fabrication and Testing of Corrugated 3D SiSiC Ceramics for Porous Burner Applications
Authors: Schmidt Jens , Scheiffele Matthias , Mach Alexander , von Issendorff Franz
Published: March 2009

Non-oxide SiC ceramics can withstand high temperatures ~1400 °C in severe
combustion environments. Therefore such ceramics are interesting candidates for advanced
combustion technologies, e.g. sophisticated porous burners. For the fabrication of porous SiSiC
ceramics the DLR developed a new technology based on carbon sheets and lamellae. These basic
materials can be combined to lightweight 3D C/C stacks. Through the variation of the amplitude
and number of lamellae per inch, the open porosity and orientation of the pore channels could be
tailored in a wide range. By using the pyrolysis followed by the liquid silicon-melt infiltration
process the carbon stack could be directly converted into SiC in one shot. The residual open
porosity can easily be filled with pure silicon to obtain 3D SiSiC structures with adequate
mechanical strength and sufficient damage tolerance. Best results from durability tests were
obtained with structures which are composed of oriented pore channels. Suitable structures should
have angles (α) of about α = ± 60° or less. The results from burner rig tests at LSTM with improved
components have been very promising, since a lifetime up to 500 hours and 2000 start-ups could be
obtained with α = ± 50° as well as with α = ± 60° sample. So far, no significant oxidation or
degradation could be observed after 1939 h/10800 start-ups with α = ± 45° sample. These proof
tests are ongoing and show that these novel cardboard like structures have a high potential for
industrial applications.
Silica Additions and the Performance of PTC Thermistors
Authors: Leach Colin , Zubair M. , Freer Robert
Published: March 2009

A series of PTC thermistors, based on BaTiO3, doped with Ca, Mn and Y, were prepared with
additions of SiO2 at levels of 0, 1, 2 and 3 at. %. The effect of the SiO2 additions and cooling rate
on microstructural development and bulk performance were characterised using a combination of
SEM, EBSD, and R-T experiments. It was found that the addition of SiO2 increased grain size
marginally, and decreased sample density by reducing the amount of grain-grain contact. The
addition of SiO2 also modified the distribution of grain boundary types by systematically decreasing
the proportion of low-Σ grain boundaries within the microstructure. Electrical behaviour was
modified by adding SiO2 or increasing the sample cooling rates; in both cases there was an increase
in ρ25 and a decrease in ρmax, with ρmax also being displaced to higher temperatures.
Lead Doping of Wet-Chem. PZT 95/5 for Enhanced Electrical Performance in Ferroelectric Power Supply Applications
Authors: Charles Stephen D.G. , Evans James D.S. , Bennett David H.
Published: March 2009

Wet chemistry produced niobium modified PZT 95/5 was synthesised and processed
for use in a ferroelectric power supply. The electrical performance of ferroelectric
power supply components can be characterised by the remnant polarisation for the
material, which is found to follow closely with density. The effects of doping the wet
chemistry derived oxide powder with additional PbO via a traditional mixed oxide
route were assessed as a function of density and remnant polarisation. The results
have shown a gradual improvement followed by a sharp deterioration in density and
electrical properties as PbO additions increase and exceed a certain level. As a result
of lead volatilisation during subsequent processing steps, the actual lead content for
the optimum PbO dopant level was in the region of theoretical stoichiometry, which
in part concludes the findings of this study. Further conclusions are made in reference
to the effect of excessive PbO on the material’s processing characteristics.
Synthesis, Characterization and Sintering Behavior of Nanocrystalline Cordierite Ceramics
Authors: Laokul Paveena , Maensiri S.
Published: March 2009

Nanocrystalline cordierite powders were prepared by the polymerized complex method.
The synthesized precursor was calcined in air at 600-1200 oC for 1h, and the calcined powders were
fully characterized by TG/DTA, BET, XRD, SEM, and TEM. The XRD and selected-area electron
diffraction (SAED) analysis confirmed the development of the phase composition of cordierite
powders showing amorphous phase after calcination at temperature below 800oC, mixed phases of
spinel and μ-cordierite phase after calcination at 800oC and 900oC, and mixed phases of spinel, μ-
cordierite and α-cordierite phases after calcination at above 900oC. The BET specific surface areas
of the calcined powders varied from 3 to 107 m2/g, depending on calcination temperature. The
highest specific surface area of 107 m2/g was found in the powders calcined at 800oC. The average
particle sizes evaluated by BET were less than 60 nm, depending on calcination temperature. The
powders calcined at 800oC and 1000oC were uniaxially pressed and pressureless-sintered in air at
1250-1350oC for 2h. Densities of the sintered samples evaluated by Archimedes’s method were 87-
91 % of theoretical value. The crystal structure of all the sintered samples, determined by XRD, was
mainly α-cordierite, having a small amount of spinel as second phase.
Electromechanical Properties of Ferroelectric Thin Films for Piezoelectric MEMS Applications
Authors: Maiwa Hiroshi
Published: March 2009

Piezoelectric microelectromechanical systems (MEMS) employing ferrroelectric thin
films have been extensively studied. In this paper, materials issues of the piezoeletric films are
presented. Temperature dependence of the electrical and electromechanical properties of
Pb(ZrxTi1-x)O3 (PZT, x= 0.3, 0.52, and 0.7) thin films were measured using scanning probe
microscopy in the temperature range from -100°C to 150°C. The field-induced displacement
increased with increase of the temperature; however, their temperature dependence was relatively
small, compared with that reported on bulk PZT ceramics. Thus far, the use of PZT film has been
most widely studied for MEMS applications. However, the lead toxicity associated with PZT and
other lead oxide-based ferroelectrics is problematic. Therefore, properties of the lead-free thin film
piezoelectrics are also described in this paper. As candidate for the lead-free piezoelectrics,
Bi4-xNdxTi3O12 (BNT) and Ba(Zr0.2Ti0.8)O3 (BZT) thin films are chosen. BNT and BZT films
prepared by chemical solution deposition exhibit field-induced strain corresponding to 38 pm/V and
35 pm/V, respectively.
Time-Dependent Nonlinear Ferroelastic Behaviour of Soft Lead Zirconate Titanate Piezoceramics
Authors: Zhou Da Yu , Kamlah Marc , Gan Yi Xiang , Laskewitz Bernd
Published: March 2009

Motivated by predicting the performance and reliability of piezoelectric devices,
considerable research efforts have been made in recent years to mathematically describe the largesignal
nonlinear behaviour of ferroelectric piezoceramics. The success of such modelling approach
depends strongly on our knowledge of the loading history dependence of the material properties. In
this experimental work, the nonlinear ferroelastic behaviour was investigated in detail for a
commercially available soft lead zirconate titanate (PZT) material under low-frequency
compressive stress loading. It was found that the strain response was significantly loading rate
dependent. The evolution of the elastic moduli was determined using fast small-stress partial
unloading method, which was specially designed to minimize the time-dependent effect as much as
possible. The results were used to separate the reversible elastic deformation from the irreversible
plastic strain due to domain switching.
Characterization of the Aurivillius Type PbBi4Ti4O15 Piezoelectric Ceramic Doped with Eu3+
Authors: Pablos L. , Villafuerte-Castrejón Maria Elena , Ibarra-Palos A. , Ocotlán-Flores J. , Sato R. , Saniger José M.
Published: March 2009

PbBi4Ti4O15 belongs to the bismuth oxide layers family discovered by
Aurivillius more than 50 years ago. In the last few years, there has been considerable
interest in layered oxides exhibiting ferroelectric, piezoelectric and other related
properties due to their wide range of application in technical devices. In the present
work the PbBi4Ti4O15 solid solution formed with Eu3+ was synthesized by
coprecipitation method and solubility limit was found. All compounds were
characterized by scanning electron microscopy, density measurements and X-ray
diffraction. The variation of lattice parameter with the Eu3+ concentration was obtained.
Raman spectroscopy was carried out in order to determine the Eu3+ site in the lattice.
Thermal analysis (thermogravimetry and differencial scanning calorimetry) results are
also presented.
DSC Kinetic Studies on Glass Ceramic System Crystallizing Indialite (Mg2Al4Si5O18)
Authors: Baldi Giovanni , Dami Valentina , Faso V.
Published: March 2009

A formulation belonging to the CaO-MgO-SiO2-Al2O3 system was characterized in order to
found a monophase system based on indialite (Mg2Al4Si5O18), known for its good mechanical
characteristics. The classical kinetic studies performed in the muffle kiln show an initial surface
crystallization followed from immediate bulk crystallization. The kinetic results obtained via
differential scanning calorimetry (DSC) were treated with isothermal method, Kissinger, Ozawa
and Matusita and Sakka approaches and compared. These results partially explain the
macroscopic behavior, because the studies performed on sample of different grain size show a
typical trend for a surface crystallization, while the value of Avrami parameter calculated from
the kinetics is 2.3, demonstrating a bi-dimensional crystallization. The value of crystallization
energy EC calculated with the isothermal method is 517.8 kJmol-1 and the comparison with nonisothermal
studies suggests bulk crystallization to occur with an increasing number of nuclei and
a two-dimensional growth of crystals.