bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Photovoltaic Powered Forced Convection Solar Dryer
Authors: Adelaja A.O. , Ogunmola B.Y. , Akolade P.O.
Published: March 2009

This solar conversion system incorporates a suction fan powered by a solar PV module. Located at the outlet of the chamber is the d.c suction fan utilised to achieve forced air circulation without the use of external power supply like grid electricity, fossil fuel and battery. Simple thermal energy balance equations and heat transfer equations were employed in the design of the system. The operational efficiency of the collector is 83.2% and mass flow rate 1.58kg/min, the maximum temperature achieved in the chamber was 58oC. The system was used to dry vegetable, hydrophylum. The capital cost is less than $150.
Development of a New Product Using Two Distributed Teams
Authors: Mbohwa C.
Published: March 2009

Recent trends in globalization of business operations and education has increased the need for global teams. These teams face a variety of challenges. This paper discusses the experience of distributed teams made up of participants from the Tokyo Metropolitan Institute of Technology and Stanford University in carrying out a design and development assignment. Challenges faced included differences in culture, in time and experience and the use of distributed information to develop a new product. Better product development demanded at least one face-to-face meeting, setting milestone deadlines and heavy use of electronic media, especially telephone and video conferencing.
Maintenance Productivity Measurement: Case Study of a Manufacturing Company
Authors: Alli O.A. , Ogunwolu L. , Oke O.
Published: March 2009

This research involves measuring maintenance productivity and seeks to measure how maintenance of equipment affects the overall productivity of the company. The Stewart Utility Concept was used along with a scaling factor. Performance measures were identified and their values were obtained. Five productivity ratios were employed to obtain the overall maintenance productivity. Results from the graphs showed that Equipment Availability was 78.32%; Emergency Failure Intensity Ratio was 28.4%; Maintenance Cost Component was 32.39/btl; Cost of Maintenance hour was N125, 081/hr; Routine Service Worked was 92.03% and Cost of Reduction was 5.32hr/N. The overall maintenance productivity of the period under review was fairly good though there is room for improvement. Average overall maintenance productivity was found to be 63.2%. This is an indication that there were evaluations and review of maintenance productivity within the period.
Investigation of the Vibrational Mode of a Long Bone – The Ulna
Authors: Nworgu O.D. , Osahon O.D.
Published: March 2009

An excised and dried ulna was vibrated at its balance pnoint about 42% (0.1m) along the length from the olecranon process, using an electromagnetic vibrator. The vibration was carried out in the anterior-posterior plane. The bone response to the mechanical vibration was picked up at equal intervals (0.02m) along the length of the bone in the plane of the vibration, using an accelerometer attached to the bone. From the response curve of the bone, the resonant frequencies at the various pick- up positions were identified. Analysis of the data shows that when the responses were picked up using the accelerometer at 0.02m proximal, and 0.1m distal, to the point of vibration, the excised ulna vibrated in the fundamental mode like a fixed-fixed beam at resonant frequencies of 340 Hz and 355Hz respectively. For resonant frequencies greater than 650 Hz, the ulna vibrates like a fixed-free beam and at modes greater than the fundamental. It is suggested from this study that the vibration of the long bone in the fundamental mode lends itself to detailed analysis in the use of resonant frequency method in the assessment of the bone quality.
Development of a Model for Analysing Radial Flow of Slightly Compressible Fluids
Authors: Akpobi John A. , Akpobi E.D.
Published: March 2009

In this work, we develop a finite element-finite difference method to solve the differential equation governing the radial flow of slightly compressible fluids. The finite element method is used to carry out spatial approximations so as to study the variation of fluid properties at the various nodes to which effect we divided the entire radial domain of the fluid into a mesh of four radial 1-D quadratic elements which exposes nine nodes to intense study. Time approximation is done with the aid of the Crank-Nicolson finite difference scheme.
Finite Element Simulation of Performance Characteristics of Infinitely Wide Plane Pad Slider Bearing
Authors: Oladeinde M.H. , Akpobi John A.
Published: March 2009

The paper describes the results of a numerical study using Galerkin’s finite element method on an infinitely wide slider bearing. The analysis is based upon the generalized Reynolds equation with the assumption that the pressure gradient in the lubricating film is negligible in the axial direction. Detailed results for bearing characteristics including pressure, load capacity, frictional force, frictional coefficient as a function of film thickness ratio (aspect ratio), and velocity of slider show that these parameters have a strong influence on the bearing behavior. Specifically, it has been shown that friction coefficient and frictional force increases with lower aspect ratios. Also, higher load carrying and maximum pressure is obtained with increased speed of the slider Point wise comparison of the results obtained using the Finite Element Method and that obtained with second order Finite Difference marching Method using base parameters show that the latter simulation has a maximum point wise error of 0.46% in comparison to 0.32% for Finite Element simulation. It has been shown that the Finite Element Method produces more accurate results. The results are in tabular and graphical forms.
Development of Software Package in Designing Chain Drives as Engineering Transmission Element
Authors: Adeyeri M.K. , Adeyemi M.B.
Published: March 2009

The paper work is aimed at using Microsoft Visual Basic 6.0 to develop window based design software that combines flexibility with adequate users interface for the design of chain drives as an engineering transmission element. The chain drives considered are of two types; silent and roller. The calculations are programmed either through ‘known torque’ or ‘through guess pitch value’. The design software combines computational with sketch template in a single process to generate the required parameters of the chain drives. The package was tested with a number of case studies and the results obtained were quite satisfactory.
Design for Manufacture of a Miniature Batch Reactor
Authors: Igboanugo A.C. , Audu T.O.K.
Published: March 2009

The results of a study into the design for manufacture of a chemical batch reactor for the synthesis of alkyd resin destined for surface-coating production is presented. The procedures for determining the key geometrical parameters of the reactor are explained. This paper presents the application of fertile innovation to the design and development of chemical batch reactor that uses boiler steam in conjunction with heat from efficient wood stove to achieve constant supply of heat, sustained at about 2500C. The design concept is governed by an analytical model developed and which specifies the optimal reactor geometries that would afford efficient heat and mass transfer. Residence time for our reactor is five (5) hours as against eight (8) hours associated with laboratory scale reactors. The performance of the chemical batch reactor during a preliminary test-run was evaluated in terms of the well over 3000C processing temperature achieved and from the result rises hope eternal.
The Effect of Baffles in Shell and Tube Heat Exchangers
Authors: Akpabio E. , Oboh I.O. , Aluyor E.O.
Published: March 2009

Shell and tube heat exchangers in their various construction modifications are probably the most widespread and commonly used basic heat exchanger configuration in the process industries. There are many modifications of the basic configuration which can be used to solve special problems. Baffles serve two functions: Most importantly, they support the tubes in the proper position during assembly and operation and prevent vibration of the tubes caused by flow-induced eddies, and secondly, they guide the shell-side flow back and forth across the tube field, increasing the velocity and the heat transfer coefficient. The objective of this paper is to find the baffle spacing at fixed baffle cut that will give us the optimal values for the overall heat transfer coefficient. To do this Microsoft Excel 2003 package was employed. The results obtained from previous studies showed that to obtain optimal values for the overall heat transfer coefficient for the shell and tube heat exchangers a baffle cut of 20 to 25 percent of the diameter is common and the maximum spacing depends on how much support the tubes need. This was used to validate the results obtained from this study.
Performance Evaluation of Palm Waste Screw Press Briquette Moulding Machine
Authors: Ilechie C.O. , Aibangbee G.F. , Ogblechi S.R. , Amiolemhen P.E.
Published: March 2009

An alternative source of heat energy to firewood called, palm waste briquette, has been developed from oil palm fruit process wastes. These wastes (sludge, shell, fibre) are compounded in a volumetric ratio of 1:2:3 and moulded into briquettes. The performance evaluation of a low cost women friendly palm waste briquette moulding machine was carried out. The evaluation showed that the machine designed and fabricated using readily available low carbon steel (mild steel) and employing the vertical screw thread mechanism in its operation, produces three different sizes of briquette (industrial sizes, medium sizes and domestic sizes). It requires only two unskilled operators and has a daily throughput of about 1,300kg briquettes (i.e. 400 pieces-industrial size or 800 pieces-medium size or 1,600 pieces-domestic size) unlike a modified brick moulding machine which has a daily throughput of 120 pieces industrial size
Fuzzy Based Solid Waste Management Method
Authors: Ojo O.O. , Anyata B.U.
Published: March 2009

Fuzzy-based Solid Waste Management involves the application of fuzzy set theory to formulate a solid waste management algorithm by taking into account a large criterion set and an extensive number of alternatives for various levels of uncertainty in Solid Waste Management. Fuzzy method of solid waste management allows consideration of multicriteria to better manage the inherent uncertainties. The fuzzy-based approach involve determination of solid waste management alternatives, selection of basic criteria, assignment of linguistic variables, construction of membership functions, assignment of membership degree values to each criterion, determination of the best criteria combination for alternatives and the choice of the best alternative. The result shows that alternative 2 has highest degree of membership function to the decision function and therefore is the chosen option.
Sustaining the Rural Energy Demand through Biogas Technology
Authors: Aribisala J.O. , Omotoso T.
Published: March 2009

Energy supply and utilization is one of the economic indices of regional development and standard of living. Energy availability in the rural areas of Nigeria is fast becoming a great challenge with the high cost of cooking gas and kerosene and environmental problems associated with firewood. The paper demonstrated the use of a pilot model study (floating drum plant) of bio-decomposition of animal waste (cattle dung and fodder) in an anaerobic condition (single batch system) to generate methane for domestic cooking. This is a unique way of waste management with additional values of energy accessibility, reliability, quality, cost and benefits including environmental and social aspects. Method involved the pre-treatment of the substrate and its inoculation. Material compositions were batched by weight. Gas produced was monitored for 10 times at 3 days interval effective from the fifth day of retention. Efficiency increased to peak at the 11th day (32.8% of the total cumulative, TC) and reduced to 1.2% TC at the 22nd day.
Indoor Smoke Emissions from Direct-Fires in Urban Households in Benin City Area of Midwestern Nigeria
Authors: Umosekhaimhe G.O.
Published: March 2009

The levels of emissions of gaseous pollutants from indoor fires within the conventional apartment types in Benin City have been studied. In Nigeria indoor smokes from domestic activities and mosquito coils occur in a significant number of houses. This study was conducted using carbon monoxide as a tracer gas within smoke in households over Benin City. Measurements were conducted using the most common residential building-type (flats) in the region. Sampling was done at 0.1m AGL, 1.0m AGL, 2.0m AGL and ceiling height to ascertain vertical distribution. The study indicated that huge levels of CO ranging between 25 and 40 ppm were observed in the self-contained or bachelor’s flat with windows closed during the night for guard against mosquitoes and crawling insects, while similar apartments with windows opened during the night equipped with protective mosquito nets showed CO concentrations with levels of between 28 and 42 ppm. The results of both house-types were significant when compared with values of the World Health Organization (WHO) and Federal ministry of environment (FMENV) acceptable limits for indoor CO concentrations.
Application of Pareto Analysis to Faults Identification in Electrical Distribution Network: A Case Study of Ugbowo 11kV Feeder, Benin City, Nigeria
Authors: Ogujor E.A. , Ubeku E.U. , Aikhoje P.T.
Published: March 2009

Application of Pareto Analysis technique in major feeder pillar faults identification is presented in this paper. Power outage data due to feeder pillar faults were collected between January, 2005 and September, 2007 from Power Holding Company of Nigeria (PHCN), Ugbowo district office, Edo State, Nigeria for four feeder pillars. The data were processed and Pareto Analysis technique was applied to the field data. The results obtained shows that eliminating wrong fusing and overloading in Edaiken 2 and Holex feeder pillars will reduce faults by 77.42 and 79.53% respectively while eliminating wrong fusing, overloading and line-to-line faults in Uwasota 2 and Holy Rosary feeder pillars will reduce faults by 87.9 and 88.35% respectively.
Use of Hydraulic Network Model for Evaluating Fire Flow Capacity of a Water Distribution Network
Authors: Izinyon O.C. , Anyata B.U.
Published: March 2009

A WaterCAD hydraulic network model of the existing Ikpoba Hill Benin City water distribution system was constructed and calibrated for steady state simulation studies using the network’s physical, operational and calibration data. The model was then used for available fire flow analysis and system improvement design. Our study reveals that the existing network has available fire flow of O l/s and hence cannot provide needed flow for fire suppression. However, the proposed improved network with increased diameters of existing pipes and which also takes into account expected future growth has available fire flow of between 29.6l/s and 40l/s at the nodes in the network.On the basis of available fire flow at the nodes in the system, hydrant tagging, numbering and colour coding which can effectively increase the fire fighting ability of the fire department can be undertaken.
Design and Implementation of a GSM Activated Automobile Demobilizer with Identification Capability
Authors: Okundamiya M.S. , Emagbetere J.O. , Edeko F.O.
Published: March 2009

The incidence of car theft in Nigeria has grown to nearly epidemic proportion. On daily basis, the numbers of stolen cars reported over the media are on the increase. Alarms and other deterrents are not enough. There is actually little one can do to prevent a car from being stolen. However, with a Global System for Mobile communication (GSM) activated automobile demobilizer with identification capability one can virtually take control of the virtually impossible incidence and hence increase the possibility of car recovery. This paper is aimed at implementing a security device capable of safeguarding cars from theft as well as provides picture and audio information of the culprits in an attempt to steal the car. To realize this work, use was made of a GSM phone
Numerical Study on Cracking Process of Masonry Structure
Authors: Wang Shu Hong , Zhang Yong Bin , Tang Chun An , Li Lian Chong
Published: March 2009

Masonry structure is heterogeneous and has been widely used in building and construction engineering. The study on cracking pattern of masonry structure is significant to engineering design. Many previous investigations on the failure process of masonry structure are usually based on the homogenization technique by selecting a typical unit of masonry to serve as a representative volume. This kind of numerical analysis neglects the mesoscopic heterogeneous structure, which cannot capture the full cracking process of masonry structures. The cracking process of masonry structure is dominantly affected by its heterogeneous internal structures. In this paper, a mesoscopic mechanical model of masonry material is developed to simulate the behavior of masonry structure. Considering the heterogeneity of masonry material, based on the damage mechanics and elastic-brittle theory, the new developed Material Failure Process Analysis (MFPA2D) system was put forward to simulate the cracking process of masonry structure, which was considered as a two-phase composite of block and mortar phases. The crack propagation processes simulated with this model shows good agreement with those of experimental observations. The numerical results show that numerical analysis clearly reflect the modification, transference and their interaction of the stress field and damage evolution process which are difficult to achieve by physical experiments. It provides a new method to research the forecast theory of failure and seismicity of masonry. It has been found that the fracture of masonry observed at the macroscopic level is predominantly caused by tensile damage at the mesoscopic level.
Symplectic Solution for a Plane Couple Stress Problem
Authors: Zhong Wan Xie , Fang Gui-Xiang , Yao Wei-An
Published: March 2009

Based on the Pro-Hellinger-Reissner variational principle of plane couple stress problem, the dual PDEs are proposed corresponding to the force method extension. The duality solution methodology is thus extended to plane couple stress problem, and then the method of separation of variables and eigenfunction expansion in the symplectic space is used to find the analytical solutions. A long strip domain plate with both lateral edges free, fixed at one end and under simple tension at the far end, is solved analytically. The solution is composed of the inhomogeneous boundary condition solutions and the superposition of eigensolutions of homogeneous lateral boundary conditions. The method of separation of variables is used for the dual PDEs, from which the eigen-root transcendental equation is solved and the corresponding eigenvector functions are obtained. The boundary conditions at the fixed end are derived via the variational method. Numerical results show that due to the effect of couple stress, the stress distribution is no longer infinity as given by the classical theory of elasticity at the corner of fixed end.
Cyclic Stress-Strain Behavior and Thermomechanical Effect in Metal Matrix Composites
Authors: Kim Hong Gun
Published: March 2009

A micromechanical model based on continuum analysis has been investigated by using finite element analysis (FEA) in discontinuous metal matrix composites (DMMC). To assess the tensile and compressive constitutive responses, a cyclic stress-strain behavior has been performed. For analysis procedure, the elastoplastic FEA and the regularly aligned axisymmetric single fiber model have been implemented to evaluate the internal field quantities. Accordingly, the fiber and matrix internal stresses were investigated for the constrained representative volume element (RVE). Further, the local plasticity in the matrix were described during loading and unloading precesses, which can predict the damage mechanisms as well as strengthening mechanisms. On the other hand, a thermoelasto- plastic analysis has been performed using FEA for the application to the continuum behavior in a discontinuous metal matrix composite. The internal field quantities of composite as well as overall composite behavior and an experiment was demonstrated to compare with the numerical simulation. As the procedure, the reasonably optimized FE mesh generations, the appropriate imposition of boundary conditions, and the relevant postprocessing such as elasto-plastic thermo-mechanical analysis were taken into account. For micromechanical model, the temperature dependent material properties and precipitation hardening effects have been employed to investigate field quantities. It was found that the residual stresses are induced substantially by the temperature drop during heat treatment and that the FEA results give a good agreement with experimental data.
Fatigue Damage of Materials with Small Crack Calculated by the Ratio-Method under Cyclic Loading
Authors: Yu Yan Gui
Published: March 2009

This paper offers some new calculating equations on the small crack growth rate for describing the elastic-plastic behavior of materials under symmetric or un-symmetric cyclic loading. And it yet suggests the estimating formulas of the life relative to varied small crack size aoi at each loading history. The method is to adopt the ratio e p e e D D / by plastic strain range to elastic strain
range as a stress-strain parameter, using some staple material parameters as the material constants in damage calculating expression. And it gives out a new concept of the composite material constant, that it is functional relation with each staple material constants, average stress，average strain and critical loading time. The calculated results are accordant with the Landgraf’s equation, so could avoid unnecessary fatigue tests and will be of practical significance to stint times, manpower and capitals, the convenience for engineering applications.
Cross-Property Relations between Elastic and Thermal Properties of Porous Ceramics
Authors: Pabst W. , Gregorová Eva
Published: March 2009

The cross-property relations between the elastic moduli and the thermal conductivity of
porous ceramics are reviewed from the viewpoint of micromechanics (composite theory).
Consequences of the rigorous Milton-Torquato and Gibiansky-Torquato relations (in the form of
bounds, i.e. inequalities derived between bulk or shear moduli on the one hand and thermal
conductivity on the other) are compared to various approximate relations (equalities) recently
proposed between the tensile modulus (Young’s modulus) and thermal conductivity, among them
the two new cross-property relations proposed by the authors. The relations are critically discussed
and applied to the case of porous alumina, zirconia and alumina-zirconia composite ceramics.
Mapping of Elemental and Phase Composition in Air-Oxidized Ti3SiC2
Authors: Low It Meng
Published: March 2009

The oxidation behaviour of Ti3SiC2 in air is not well understood due to mixed results
reported in the literature. In this study, the surface composition depth-profiles of air-oxidized
Ti3SiC2 have been investigated by synchrotron radiation diffraction (SRD) and secondary ion mass
spectroscopy (SIMS) in the temperature range 500-1300°C. Anatase has been observed to form at
~600°C, rutile at ~750°C and tridymite at ~1100°C. Depth-profiling results by SIMS and SRD have
revealed a distinct gradation in element and phase composition respectively within the surface
oxide layers.
Application of X-Ray Microtomography to the Microstructural Characterization of Al-Based Functionally Graded Materials
Authors: Velhinho Alexandre , Braz Fernandes Francisco Manuel , Ferreira S.C. , Rocha L.A. , Vignoles Gerard , Cloetens P.
Published: March 2009

This paper provides a brief overview of the possibilities offered by X-ray computed
microtomography, and particularly synchrotron radiation X-ray microtomography, regarding metal
matrix composite characterization, emphasis being placed in the case of Al-based functionally
graded materials. Examples are provided concerning the characterization of the reinforcement
population, interfacial properties, in-situ transformation and damage evolution. The specific needs
of the technique and limitations to its widespread use are mentioned.
Sintering of EPD Ceramic Coatings by Electron Beam
Authors: De Riccardis Maria Federica , Carbone Daniela , Piscopiello Emanuela , Rizzo Antonella , Vittori Antisari Marco
Published: March 2009

In order to obtain wear resistant coating as well as thermal barrier on metallic substrates
by EPD, the conventional high temperature treatments are inapplicable; so we used an alternative
method to densify and make the electrophoretic deposit more adherent. In this work we described a
novel method to obtain EPD deposits with good density and adherence to stainless steel substrate.
At first, we achieved stabilized alumina and alumina-zirconia based suspensions; to improve the
adhesion of ceramic coating on metal, some stainless steel substrates were sandblasted, others were
coated with titanium bond layers. Then the substrates were coated by EPD; finally, we used the
electron beam to treat the ceramic coating-metallic substrate system on the surface; in this way we
obtained adherent and dense EPD coatings. In order to evaluate the quality and the microstructure
of the coating sintering, the samples were observed by scanning and transmission electron
microscopy; pull tests showed the adhesion of treated EPD coating was about one hundred times
higher than that of deposited EPD coating.
Coating of Austentic Stainless Steel with Ti/O Compositionally Gradient Film by Reactive DC Sputtering
Authors: Sonoda Tsutomu , Watazu Akira , Katou Kiyotaka , Asahina Tadashi
Published: March 2009

Coating of austentic stainless steel substrates with Ti/O compositionally gradient film was
examined using reactive DC sputtering technique, in order to improve not only the abrasion
resistance of the stainless steel but also the adhesion between the deposited film and the substrate
with preserving the high hardness of such a hard ceramic coating as titanium oxide coating. The
deposition of Ti/O compositional gradient films were realized by varying continuously the oxygen
content in Ar-O2 sputter-gas during the reactive sputtering. The obtained films were appeared to be
uniform and adhesive, while Ti-O compositional constant (i.e. non-gradient) films which were
deposited by reactive DC sputtering under the same sputtering conditions except for the Ar-O2 gas
mixing condition, i.e., with the oxygen content in the gas mixture constant, peeled off partly.
According to AES in-depth profiles, the oxygen (O) concentration in the obtained film gradually
decreased in depth direction from the surface toward the substrate, confirming that Ti/O
compositional films had formed on the stainless steel. On the basis of XRD, it was found that not only
hcp alpha-titanium and titanium oxide (anatase) but also some types of suboxides had formed in the
gradient films. Furthermore the gradient films approximately indicated Hv600 which was much
higher than that of the stainless steel substrate. Therefore the abrasion resistance of the stainless steel
and the adhesion at the interface were expected to be improved at the same time.
Bioactive Apatite-Mullite Glass-Ceramic Coatings on Titanium Substrates
Authors: Stanton Kenneth T. , Vanhumbeeck Jean François
Published: March 2009

Fluorapatite-mullite glass-ceramics have been shown to be bioactive in the
cerammed state and the present study examines how they may be deposited on
biomedical-grade titanium alloy substrates for orthopaedic applications. A simple
deposition route was used for initial application of the material in the glassy state and
it was then cerammed in-situ. This cheap and non-line-of-sight route produces well
adherent coatings by virtue of a reaction between the coating and substrate during the
ceramming step. Several characterization techniques including DSC and XRD have
been used to determine the crystallization behaviour of the glass-ceramic ex-situ and
electron microscopical techniques have been used to characterize glass-ceramic
microstructures and the nature of the coating-substrate interfacial region.
Assessment of the Adhesion of Ceramic Coatings
Authors: Chen Jinju , Bull S.J.
Published: March 2009

A number of methods have been proposed to assess the adhesion of ceramic coatings
including pull-off, shockwave, bending, scratch, and indentation tests. With the development of
new coatings, the need for reliable adhesion tests is paramount, but it is not always easy to select an
appropriate adhesion test, particularly for sub-micron coatings. Indentation tests are suitable in such
cases provided that the interfacial failure mode is understood and can be modelled. This paper
reviews the existing models and our newly developed models to extract quantitative adhesion data
in such cases.
Residual Stress Relaxation and Microstructure in ZnO Thin Films
Authors: Ozen Istem , Gülgün Mehmet Ali
Published: March 2009

Stability under normal environmental conditions over a long period of time is crucial for
sustainable thin-film device performance. Pure ZnO films with thicknesses in the 140 - 450 nm
range were deposited on amorphous glass microscope slides and (100)-oriented single crystal
silicon wafers by radio frequency magnetron sputtering. The depositions were performed at a
starting temperature of 200 oC. ZnO films had a columnar microstructure strongly textured along
the <0002> direction. XRD peak-shift analysis revealed that the films were under residual,
compressive, in-plane stress of -5.46 GPa for the glass substrate and -6.69 GPa for the Si substrate.
These residual stresses could be completely relaxed by thermal annealing in air.
When left under normal environmental condition over an extended period of time the films
failed under buckling leading to extensive cracking of the films. The XRD and SEM results
indicated different mechanisms of stress relaxation that were favored in the ZnO thin films
depending on the energy provided. Although thermal annealing eliminated residual stresses, serious
micro-structural damage upon annealing was observed. Thermal annealing also led to preferential
growth of some ZnO crystals in the films. This kind of behavior is believed to be indicative of
stress-induced directional diffusion of ZnO. It appears that for the extended stability of the films,
the stresses have to be eliminated during deposition.
Design and Development of Novel Coatings to Inhibit Degradation due to High Temperature Sulphidation
Authors: Du Hai Liang , Burnell-Gray Jim. S. , Datta Psantu K.
Published: March 2009

This paper discusses the design and development of sulphidation resistant coatings. The first
section discusses the rationale for designing and developing such coatings. The rationale for selecting
the coating systems has been derived from our work on the HT sulphidation behaviour of MCrAlYX
(M=Co, or Co-Fe and X=V, Nb, Mo and W) type of coating alloys. This work has allowed the
establishment of the mechanisms of sulphidation and led to the choice of the coating systems discussed
here. The second section describes the sulphidation performance of several selected coatings, single
and multilayer, deposited on Ti, TiAl and Ni-based alloys at 750-850oC in environments of low
oxygen and high sulphur potentials.
Optimization of UHV-CVD Thin Films for Gate Dielectric Applications
Authors: Rogers Bridget R. , Song Zhe , Geil Robert D. , Weller Robert A.
Published: March 2009

In-situ and ex-situ spectroscopic ellipsometry (SE), atomic force microscopy (AFM),
transmission electron microscopy (TEM), and time of flight medium energy backscattering (ToF
MEBS), are used to investigate the properties of 30 and 60 Å ZrO2 films deposited at different
temperatures on hydrogen terminated silicon (H-Si) and native silicon oxide surfaces. Results
show that the initial-stage deposition of ZrO2 on H-Si and native silicon oxide surfaces are
different. A 3-dimesional (3D) type nucleation process of ZrO2 on H-Si leads to high surface
roughness films, while layer-by-layer deposition on native silicon oxide surfaces leads to
smooth, uniform ZrO2 films. An interfacial layer, between the substrate and the metal oxide, is
formed through two independent mechanisms: reaction between the starting surfaces and ZTB or
its decomposition intermediates, and diffusion of reactive oxidants through the forming ZrO2
interfacial stack layer to react with the substrate.
A Study of the Platinum/Alumina Interface
Authors: Suppel Kate P. , Forrester Jenny S. , Suaning Gregg J. , Kisi Erich H.
Published: March 2009

Single crystal sapphire in one of four orientations (0001), (11 2 0), (1102) and (1010) was bonded
to polycrystalline platinum foil at 1330oC under light load 20 N (0.8 MPa) in argon. The different
orientations were used as a means to model individual grains within a polycrystal without the
uncertain influence of grain boundaries and glass-forming contamination (e.g. SiO2). Partial
bonding was observed in all cases. Optical microscopy, scanning electron microscopy (SEM) and
X-ray photoelectron spectroscopy (XPS) were used to study the nature of the bond which appears
to be physical rather than chemical, in agreement with previous work.
Evaluation of Mechanical Properties and Comprehensive Modeling of CMC with Stiff and Weak Matrices
Authors: Koch Dietmar , Tushtev Kamen , Horvath Jürgen , Knoche Ralf , Grathwohl Georg
Published: March 2009

The mechanical properties of ceramic matrix composites (CMC) depend on the
individual properties of fibers and matrix, the fiber-matrix interface, the microstructure and the
orientation of the fibers. The fiber-matrix interface of ceramics with stiff matrices (e.g. CVI-derived
SiC/SiC) must be weak enough to allow crack deflection and debonding in order to achieve
excellent strength and strain to failure (weak interface composites WIC). This micromechanical
behavior has been intensively investigated during the last 20 years. With the development of CMC
with weak matrices (weak matrix composites WMC) as e.g. oxide/oxide composites or polymer
derived CMC the mechanical response can not be explained anymore by these models as other
microstructural mechanisms occur. If the fibers are oriented in loading direction in a tensile test the
WMC behave almost linear elastic up to failure and show a high strength. Under shear mode or if
the fibers are oriented off axis a significant quasiplastic stress-strain behavior occurs with high
strain to failure and low strength. This complex mechanical behavior of WMC will be explained
using a finite element (FE) approach. The micromechanical as well as the FE models will be
validated and attributed to the different manufacturing routes.
Degradation of Conductivity and Microstructure under Thermal and Current Load in Ni-YSZ Cermets for SOFC Anodes
Authors: Thydén Karl , Barfod Rasmus , Liu Yi Lin
Published: March 2009

The degradation of electrical conductivity in porous nickel-yttria stabilized zirconia
composite cermets in a H2/H2O atmosphere under high temperature treatments has been
investigated. The parameters varied were: temperature, water partial pressure, and electrical current
load. The microstructure was analyzed before and after the treatment by optical microscopy and
field emission scanning electron microscopy (FE-SEM). From the optical images the particle size
and total amount of Ni, as area fraction, in the sample were measured. By the use of charge contrast
(CC) in the FE-SEM particle size and area fraction of percolated Ni was measured. Temperature
proved to have the largest effect on the degradation. Samples tested at 1000°C, in contrast to 750°C,
showed a severe decrease of conductivity and growth of Ni particles. Higher water partial pressure
accelerated Ni particle growth at both temperatures, but the loss of percolation and conductivity at
1000°C was less severe under high water partial pressure. A possible explanation for this behavior
is discussed.
Fatigue Behaviour of Structural Ceramic Composites
Authors: Fantozzi Gilbert , Reynaud Pascal , Rouby Dominique
Published: March 2009

Non-oxide composites are interesting materials for long term applications at high
temperature under oxidizing atmosphere. To improve their lifetime, self-healing [Si-B-C] matrix
has been developed recently. On this new generation of composite, fatigue has been studied at high
temperature (up to 1200°C) in air. For the SiCf/[Si-B-C] composite, lifetime at 600°C is higher than
1000 h for a tension/compression cyclic loading of -50/+170 MPa. Nevertheless, the mechanical
behaviour during the cyclic fatigue test is different at 600°C from that at 1200°C. Contrarily to
1200°C, at 600°C no specific evolution of the classical parameters used to characterize the
mechanical behaviour during fatigue allows us to estimate the approach to fracture,. This indicates
that the fatigue phenomena involved at 600°C are different from those involved at 1200°C. At
600°C, lifetime is mainly controlled by slow-crack-growth in the fibres in presence of air, and at
1200°C lifetime is controlled by fibre creep and oxidation.
Corrosion of Mullite in Contaminated Water Rich Gas Mixtures at High Temperatures: The Effect of Impurity Diffusion
Authors: Ruescher Claus H. , Eils Nadine , Horn Ingo , Schneider Hartmut , Shimada Shiro
Published: March 2009

Two series of mullite single crystal plates of thicknesses between 0.9 and 1.9 mm were
exposed up to 12 h to a slowly flowing water rich gas mixture (O2/H2O = 80/20; 100 ml/min) at
temperatures of 1670°C. The heat treated samples show up to about 50 μm into the mullite a partial
surface decomposition. Decomposition products are sodium containing silicon-rich aluminosilicate
glass and α-alumina within melt cavities. Concentration profiles through the plate cross sections
show the effect of inward and outward diffusion of OH forming species and Na and Mg impurity
enrichment on ppm level in the bulk.
Influence of Grain Size Distribution on Hardness and Fracture Toughness of Si3N4/SiC Nanocomposites
Authors: Hnatko Miroslav , Lojanová Štefánia , Pálková Helena , Lenčéš Zoltán , Šajgalík Pavol
Published: March 2009

Si3N4/SiC nanocomposite material with yttria as sintering additive was prepared by
hot pressing method. SiC nanoinclusions were produced by in situ reaction between SiO2
and C during the sintering process. The homogenous microstructure of hot pressed samples
contained fine Si3N4 grains with average diameter of 200 nm. The post-sintering treatment at
1750°C for 26 and 70 hours significantly changed the microstructure of Si3N4/SiC
composites. The difference between the average grain size of hot pressed sample and sample
treated for 70 hours is approx. 300 %. In sake of this fact the mechanical properties (KIC,
HV1) were not changed significantly. The largest differences between the mechanical
properties of hot pressed and annealed samples were only 8 %.
Nanoparticle Bonding Technology for Composite Materials
Authors: Naito Makio , Abe Hiroya , Sato Kazuyoshi
Published: March 2009

Nanoparticle bonding technology can present a promising method for nano/micro
structural controls of composite particles as well as composite materials. The
nanoparticle bonding can be well conducted by making use of the unique properties of
nanoparticle surface at lower temperature without any binder in dry phase. In this paper,
the concept of nanoparticle bonding technology is introduced. The examples of
nano/micro structural controls of particles including composite particles and the
composite materials are shown.
Development of CNT-Silicon Nitrides with Improved Mechanical and Electrical Properties
Authors: Balázsi Csaba , Wéber Ferenc , Arató Péter , Fényi Balazs , Hegman Norbert , Kónya Zoltán , Kiricsi Imre , Vértesy Zófia , Biró László Péter
Published: March 2009

This work is focusing on exploring preparing processes to tailor the microstructure of
carbon nanotube (CNT) reinforced silicon nitride-based ceramic composites. Samples with different
porosity’s and different amount (1, 3 or 5 wt%) of carbon nanotubes have been prepared by using
gas pressure sintering or hot isostatic pressing. In comparison, composites with 1wt%, 5wt% or
10wt% carbon black and graphite have been manufactured. We measured the room temperature
mechanical and electrical properties, examined the micro and nano structure by X-ray diffraction
and electron microscopy. It was found that it is possible to develop CNT-silicon nitride composite
for applications where a decent electric conductivity and good mechanical properties are required.
Hard and Tough Boron Suboxide Based Composites
Authors: Shabalala T.C. , McLachlan David S. , Sigalas I.J. , Herrmann Mathias
Published: March 2009

Boron Suboxide (B6O) powder was synthesized at temperatures of about
1400 oC from the reaction of boron and boric acid powders. The synthesized
B6O powders were hot pressed at 1900 oC and at pressures of 50 MPa.
Additionally to pure B6O materials, composites with Aluminum were
prepared. The microstructure and properties of the sintered compacts were
investigated. The addition of Aluminum in the composites results in the
formation of an additional Aluminum Borate phase. The composites showed
a similar hardness (~30GPa) as the pure B6O samples but an increased
fracture toughness (~3.5MPa.m1/2).
Ceramic Piston for Hydraulic Brakes: Design Study
Authors: Kosmač Tomaž , Dakskobler Aleš , Kermc Mihael , Stadler Zmago
Published: March 2009

A design study for ceramic pistons was undertaken in order to address the overheating
problems associated with the caliper during aggressive braking using modern C/C-SiC brake discs.
The reasoning behind the piston design and the choice of the shaping technology are explained.
Zirconia-toughened mullite (ZTM) ceramic was chosen for the pistons, because this material
exhibits a low thermal conductivity, sufficiently high mechanical strength and fracture toughness, as
well as very good thermal-shock resistance. The manufacturing technology of experimental ceramic
brake pistons involved compounding of the selected starting powders to form a high-solids-loadingcontaining
feedstock, tooling, shaping of green parts by low-pressure injection molding, extraction
of the organic binder, pressure-less sintering in air and final machining. Prototypes brake pistons
were fabricated and successfully tested as components of motorcycle brake systems in a test
laboratory and on a motorcycle racing track.
SAXS Characterization of Carbon Aerogels for Catalytic Supports
Authors: Ehrburger-Dolle Françoise , Berthon-Fabry Sandrine , Bley Françoise
Published: March 2009

Carbon aerogels are very promising substrates for electrocatalyst deposition involved in
fuel cells. Their advantage over high surface area carbon blacks currently used, is the porous
monolithic structure yielding large pore volumes with controlled pore sizes. By changing the
synthesis parameters, it is possible to adjust their multi-scale structure which is strongly related to
the electrochemical performances. The aim of the lecture is to give a survey of information about
the multi-scale structure that can be obtained by small and wide angle X-ray scattering (SAXS and
WAXS) techniques combined with contrast variation (CV). To this end, a series of SAXS
experiments on carbon aerogels are described and the analysis of the experimental data is
explained. Particular attention is paid to the determination of the specific surface area, SSAXS, and to
the reasons why WAXS curves combined to SAXS ones make this determination more pertinent.
The physical meaning of similarity or difference between SSAXS and surface area determined by gas
adsorption, SADS, is discussed and information obtained by using contrast variation (CV) is
described for two carbon aerogels prepared in different conditions.
Synthesis and Processing of Perovskite Oxides for Solid Oxide Fuel Cells Anode Fabrication
Authors: Montinaro Dario , Bertoldi Massimo , Sglavo Vincenzo M.
Published: March 2009

In the present work materials alternative to Ni/YSZ cermets anodes for Solid Oxide
Fuel Cells (SOFCs) have been studied in order to overcome the problems related to catalytic
deposition of carbon and the limited tolerance to sulphur. Anodes consisting of
(La0.75Sr0.25)(Cr0.5Mn0.5)O3-δ (LSCM25) have been investigated with regard to synthesis and
processing related problems. Single phase LSCM25 perovskites were synthesized by urea/nitrates
gel combustion method and the as prepared powders were used to produce green tapes by tape
casting processing. Thick LSCM25 substrates, suitable as anodes in anode supported SOFC
fabrication, were successfully obtained by sintering of green LSCM25 laminates.
Zirconia Inert Matrix for Plutonium Utilisation and Minor Actinides Disposition in Thermal Reactors
Authors: Degueldre Claude
Published: March 2009

The toxicity of the UO2 spent fuel is dominated by plutonium and minor actinides (MA): Np, Am and Cm, after
decay of the short live fission products. Zirconia ceramics containing Pu and MA in the form of an Inert Matrix Fuel (IMF)
could be used to burn these actinides in Light Water Reactors. Optimisation of the fuel designs dictated by properties such as
thermal, mechanical, chemical and physical must be performed with attention for their behaviour under irradiation. Zirconia
must be stabilised by yttria to form a solid solution such as AnzYyPuxZr1-yO2-y where minor actinide oxides are also soluble.
Burnable poison may be added if necessary such as Gd, Ho, Er, Eu or Np, Am them-self. These cubic solid solutions are
stable under heavy ion irradiation. The retention of fission products in zirconia, under similar thermodynamic conditions, is a
priori stronger, compared to UO2, the lattice parameter being larger for UO2 than for (Y,Zr)O2-x. (Er,Y,Pu,Zr)O2-x in which Pu
contains 5% Am was successfully irradiated in the Proteus reactor at PSI, in the HFR facility, Petten as well as in the Halden
Reactor. These irradiations make the Swiss scientists confident to irradiate such IMF in a commercial reactor that would
allow later a commercial deployment of such a fuel for Pu and MA utilisation in a last cycle. The fuel forms namely pellet of
solid solution, cercer or cermet fuel are discussed considering the once through strategy. For this strategy, low solubility of
the inert matrix is required for geological disposal. As spent fuels these IMF’s are demanding materials from the solubility
point of view, this parameter was studied in detail for a range of solutions corresponding to groundwater under near field
conditions. Under these conditions the IMF solubility is 106 times smaller than glass, which makes the zirconia material very
attractive for deep geological disposal. The desired objective would be to use IMF to produce energy in reactors, opting for
an economical and ecological solution.