bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Temperature Failure of Fe76Ni2Si9B13 Compacted from Amorphous Glass Powder
Authors: Miškuf Jozef , Csach Kornel , Juríková Alena , Tabachnikova Elena D. , Bengus Vladimir Z. , Podolskiy Aleksey V. , Nesterenko Vladimir
Published: September 2009

The fracture surface morphology of Fe76Ni2Si9B13 bulk amorphous alloys failed in compression at temperatures from 4.2 to 300 K was investigated. The samples were prepared by the explosive compaction technique from amorphous powder. It has been found that fracture stress decreases with temperature from 300 to 4.2 K. In this temperature range, the brittle failure prevails. The failure propagates across particles and along particle boundaries too. The fracture micromorphology is riverlike pattern with fine dimples.
Fracture Toughness of Si3N4 Based Ceramics with Rare-Earth Oxide Sintering Additives
Authors: Tatarko Peter , Lojanová Štefánia , Dusza Ján , Šajgalík Pavol
Published: September 2009

Fracture toughness of hot-pressed silicon nitride and Si3N4+SiC nanocomposites prepared with different rare-earth oxides (La2O3, Sm2O3, Y2O3, Yb2O3, Lu2O3) sintering additives have been investigated by Chevron Notched Beam, Indentation Strength and Indentation Fracture techniques. The fracture toughness values of composites were lower due to the finer microstructures and the lack of toughening mechanisms. In the Si3N4 with higher aspect ratio (Lu or Yb additives) crack deflection occurred more frequently compared to the Si3N4 doped with La or Y, which was responsible for the higher fracture toughness.
Wear of TiCN Coated Sintered Fe-1.5Cr-0.2Mo-0.7C Steels
Authors: Bidulský Róbert , Actis Grande Marco
Published: September 2009

The wear behaviour on prealloyed sintered steel parts TiCN PVD coating was analysed. Cylindrical specimens ( 40x30 mm3) were compacted to the green density of ~7.0 g.cm-3. The specimens were sintered in pusher furnace at the temperature of 1180°C for 40 minutes in an atmosphere of 25H2+75N2. Part of sintered specimens was then coated by Physical Vapour Deposition. Wear tests were carried out by means of a pin-on-disk tribometer. The results of profilograms (the values of surface roughness) and the wear curves (mass loss versus sliding distance) showed positive effect of coating on the wear resistance of the tested specimens.
Quantitative Description of Overlaps on Sialon Ceramics Fractures by the Multifractal Method
Authors: Stach Sebastian , Roskosz Stanisław , Cybo Jerzy , Cwajna Jan
Published: September 2009

A quantitative description of overlaps on fractures in sialon ceramics, is presented in the paper. A conventional analysis, aiming at the determination of the percentage share of overlaps on the basis of quantitative fractography, was preceded by stereometric/fractal analyses. They enabled the selection of representative sections of samples and then, the production of transverse microsections in those places for an analysis of the fractures’ profiles using the light microscopy method and fractographic image analysis. Based on the compared results from both methods, a successful verification was made of the research methodology developed earlier for sintered carbides and proven for a chromium-molybdenum steel.
Failure Analysis on a Flowmeter
Authors: Kuebler Jakob
Published: September 2009

A measuring cone made of borosilicate glass mounted in a flowmeter failed after a life¬time of only a few months. Therefore, a failure analysis was conducted which revealed that the reason for failure was a too high flow rate. The high flow rate made the float touch the upper float stop. When contacting the stop, the float started to rotate in an unstable manner and as a result was hitting and grinding along the inner cone wall which resulted in cracks, micro-chipped surface areas and grinding marks. One of the longitudinal cracks then grew subcritically till final failure occurred.
Fractography of Dental Restorations
Authors: Scherrer Susanne S. , Quinn Janet B. , Quinn George D.
Published: September 2009

The dental community is using a variety of ceramic restorative materials such as porcelains (leucite or alumina based), glass-ceramics (leucite, mica, lithium disilicates), alumina-glass infiltrated, and CAD-CAM ceramics including pure alumina and zirconia (3Y-TZP) core materials. Polycrystalline ceramics such as alumina and zirconia serve as substructure materials (i.e., framework or core) upon which glassy ceramics are veneered for an improved appearance. Under masticatory loads, sudden fracture of the full-thickness restoration or of the veneering ceramic (chips) may occur.
Stereomicroscope and scanning electron microscope analyses were used to perform qualitative (descriptive) fractography on clinically failed dental ceramic restorations. The most common features visible on the fracture surfaces of the glassy veneering ceramic of recovered broken parts were hackle, wake hackle, twist hackle, arrest lines, and compression curls. The observed features are indicators of the local direction of crack propagation and were used to trace the crack’s progression back to its initial starting zone (the origin).
This paper presents the applicability of fractographic failure analyses for understanding fracture processes in brittle dental restorative materials and it draws conclusions as to possible design or processing inadequacies in failed restorations.
Fracture of Layered Ceramics
Authors: Bermejo Raúl , Ceseracciu Luca , Llanes Luis , Anglada Marc
Published: September 2009

Layered ceramics are foreseen as possible substitutes for monolithic ceramics due to their attractive mechanical properties in terms of strength reliability and toughness. The different loading conditions to which ceramic materials may be subjected in service encourage the design of tailored layered structures as function of their application. The use of residual stresses generated during cooling due to the different thermal strain of adjacent layers has been the keystone for the improvement of the fracture response of many layered ceramic systems, e.g. alumina-zirconia, alumina-mullite, silicon nitride-titanium nitride, etc. In this work, the fracture features of layered ceramics are addressed analysing two multilayered structures, based on the alumina-zirconia system, designed with tailored compressive residual stresses either in the external or internal layers. Contact strength and indentation strength tests have been performed to investigate the response of both designs to crack propagation. The experimental findings show a different response in terms of strength and crack growth resistance of both designs. While layered structures with compressive stresses at the surface provide a better response against contact damage compared to monoliths, a flaw tolerant design in terms of strength and an improved toughness through energy release mechanisms is achieved with internal compressive stresses. The use of layered architectures for automotive or biomedical applications as substitutes for alumina-based ceramics should be regarded in the near future, where reliable ceramic designs are needed.
Electrophoretic Deposition of Lead-Zirconate-Titanate Perovskite Thick Films with Low Sintering Temperature
Authors: Kuscer Danjela , Kosec Marija
Published: September 2009

We have studied the processing of lead-zirconate-titanate PbZr0.53Ti0.47O3 (denoted PZT) based thick films using an electrophoretic deposition (EPD) process in order to obtain the active film with desired thickness and porosity at low the sintering temperature. The colloidal suspensions were prepared by mixing the ceramic powder in ethanol with the controlled addition of a polyelectrolyte salt and an organic base. In order to optimise the deposition process, the stability of the PZT and Pb5Ge3O11 (denoted PGO) particles in ethanol-based suspensions was studied. The electrophoretic deposition of PZT-PGO was performed from a mixture of optimal PZT and PGO suspensions in an appropriate molar ratio. PZT and PGO acting as a sintering aid were deposited on an Al2O3/Au substrate at a constant applied current and sintered at 850 oC. The thickness of the deposit was controlled by the deposition time and the applied current. PZT-PGO thick films deposited at 1.2 mA for 60 seconds and sintered at 850oC for 8 hours exhibited a room-temperature dielectric permittivity of 1050, dielectric losses of 0.038, a remanent polarisation Pr of 29 C/cm2, a coercive field Ec of 21 kV/cm and a d33 of 97pC/N.
Preparation of NASICON-Based Ceramic Thick-Film with Electrophoretic Deposition for Solid-State Photoluminescence Device
Authors: Shimizu Youichi , Takase Satoko , Ida Kensaku , Imamura Masataka , Koguma Ikuhiro
Published: September 2009

Electrophoretic deposition method was applied to prepare some solid-electrolyte thick-films of Na1+xZr2SixP3-xO12 (x = 2, 3; NASICON) and Na5DySi4O12 (NDSO) on Au-coated alumina substrates. With the ethanol-based medium, the deposition process was investigated under constant voltage mode. The concentration of the suspension and applied voltage were optimized with respect to the rate of deposition and quality of the deposit. The NASICON (Na3Zr2Si2PO12) -based solid-state ionic conductor thick-film as a host ceramic with a guest Cu+ ion has been produced as a noble phosphor thick-film by using an electrochemical ion doping method. The photoluminescence (PL) device of the NASICON:Cu+ film showed good photo-luminescent peaks near 450-500nm depending on the host materials.
Electrophoretic Deposition of Star Polymer-Europium Chalcogenide Nanocomposite Films
Authors: Somarajan Suseela , Hasan Saad A. , Harrison Melissa A. , Mahajan Sameer V. , Adkins Chinessa T. , Harth Eva , Dickerson James H.
Published: September 2009

The electrophoretic deposition of polystyrene/divinylbenzene (PS/DVB) star polymer-europium sulphide (EuS) nanocomposite films from a colloidal suspension is reported. Liquid suspension, containing both the PS/DVB star polymer and EuS nanocrystals were prepared by separately injecting dichloromethane (DCM) based solutions of EuS nanocrystals and of the star polymers, respectively, into a stratified liquid combination of hexane and DCM. Scanning electron microscopy illustrates images of the dependence of surface morphology on nanocrystal concentration of the PS/DVB-EuS star polymer film. These polymer-encased nanocrystal films may be a more practical option for the fabrication of magneto-optical thin film devices, such as optical switches, optical isolators, and optical memories.
Electrophoretic Deposition/Infiltration of Natural Zeolite Particles on/into Various Substrates
Authors: Hayashi Shigeo , Onoe Junpei , Ebina Kazuyoshi , Kodama Nobuhiro
Published: September 2009

Electrophoretic deposition (EPD) and infiltration (EPI) behavior of a natural zeolite (clinoptilolite, produced in Akita prefecture, Japan) particles on/into a steel and a porous glass substrates were investigated for the purpose of the environmental purification. The obtained deposit of the zeolite prepared by the EPD was less durable against peeling off compared with the EPI process, but it was improved by use of silica sol particles as a binder. Ion uptake efficiency of the EPD sample was superior to that of the EPI sample, that will be caused by the shape factor of the zeolite particle deposit.
Preparation of Thin Proton Conducting Membranes by Means of EPD
Authors: Argirusis Christos , Grosse-Brauckmann Jana , Sourkouni Georgia , Taillades Gilles , Roziere Jaques
Published: September 2009

The present study uses electrophoretic deposition of yttrium doped barium cerate to prepare SOFC half cells on nickel/barium cerate (Ni/BaCe) and nickel / yttria stabilized zirconia (Ni/YSZ) substrates. Therefore we investigated charging and agglomeration behaviour of nanosized barium cerate powder in different solvents by means of a micro electrophoresis experiment and dynamic light scattering. Stable suspensions of barium cerate were prepared and deposition kinetics was examined prior to the preparation of thin membranes on the two cermets. Tests with different solvents and additive combinations showed that methyl-ethyl-keton (MEK) with addition of polyacrylic acid (PAA) is the best combination for the use of the suspension for electrophoretic deposition. Electrophoretic deposition in this case is a simple and low cost method to produce homogenous and dense layers in the scale of microns.
Photocatalytic Destruction of 1,4-Dioxane in Aqueous System by Surface-Roughened TiO2 Coating on Stainless Mesh
Authors: Yanagida Sayaka , Nakajima Akira , Kameshima Yoshikazu , Okada Kiyoshi
Published: September 2009

This study investigated the effect of surface roughness on a coating of TiO2 submicron powders that had been applied on a stainless steel mesh using electrophoretic deposition (EPD). Roughness was provided to the surface of EPD coating using UV pre-illumination to the suspension prepared by isopropyl alcohol and commercial TiO2 powder. The Ra value was increased around 20% by this treatment. The rough coating provided a higher photocatalytic decomposition rate of 1,4-dioxane in water than a smooth coating obtained from the suspension without UV pre-illumination. That increase is attributable to the increase of the reaction field on the coating surface.
Formation of Crystalline-Oriented Titania Thin Films on ITO Glass Electrodes by EPD in a Strong Magnetic Field
Authors: Kawakita Mamiko , Uchikoshi Tetsuo , Besra Laxmidhar , Suzuki Tohru , Kawakita Jin , Sakka Yoshio
Published: September 2009

Crystal-oriented and crack-free thin TiO2 films with a good interfacial adhesion on indium-tin oxide (ITO) glass substrates for photoelectrodes were fabricated by the electrophoretic deposition (EPD) method in a 12 T strong magnetic field. A binder-free suspension for the EPD was prepared by dispersing TiO2 in the mixture of 2-propanol and 2,4-pentanedione. The electrophoretic mobility and the sedimentation rate were measured at various ratios of the mixed solution. The optimized state of the suspension exhibiting the highest surface charge potential and producing deposits with the highest green density was obtained at the 50:50 mixing ratio. The TiO2 films were characterized by XRD and SEM analyses. The photo-current measurement was also conducted to investigate the relation between the photo-anode characteristics of a dye-sensitized solar cell and the plane orientation of the TiO2 films
Intermediate Scale Production of Ceramics and Ceramic Coatings by EPD
Authors: Blackburn John
Published: September 2009

The potential for the commercial use of EPD as a manufacturing technique has been established. Rigs and equipment have been designed and constructed for the EPD of ceramic components to a range of geometries including tubes and plates. Components have been produced with uniform thickness up to 3mm, or with varying thickness. Systems have also been operated to produce ceramic coatings on metal substrates including flat foils, tubes, rods and complex shapes. Coatings of ZrO2, cerium gadolinium oxide (CGO), cermet mixtures, (La0.8Sr0.2)0.98Mn oxide (LSM), TiO2 and Al2O3 have all been successfully produced and such layers can be achieved with a deposition time of <2 minutes. Multiplying the number of EPD cells which can be operated simultaneously enables the average deposit time to be reduced to a level where commercial production becomes feasible. Thicker crack-free layers of the above materials up to 150micron have been produced for applications where a robust porous structure is required. XRD, SEM and EDX results have shown that the EPD methods developed for use in these systems are capable of producing layers from binary or ternary mixtures of suspension without segregation within the formed layers.
Developing an Electrophoretically Depositable Self-Lubricating Nanocomposite Paint Process for a Short Recoil Semi-Automatic Handgun Application
Authors: Hope Peter
Published: September 2009

Semi-automatic handguns characterised by the classic Colt 1911 model rely on a reciprocating slide mechanism for loading and ejecting. The moving surfaces require a tight fit to maintain firing accuracy while having ease of movement to avoid misloading or jamming. The electrophoretic painting method is ideal for coating complex geometries where engineering tolerances need to be maintained. The anodically depositable paint system developed for this application incorporates nanosilica for reinforcement of the resin binder and a blend of polytetrafluoroethylene, boron nitride and molybdenum disulphide to provide a self-lubricating anti-corrosive coating. Colourants have been added to provide various appearance attributes. The formulating procedures for producing this type of complex electrophoretic paint are described. This includes considerations of manufacture, shelf life, shipping, application by the customer, and compliance with health and environmental regulations as well as meeting the extreme performance requirements of the end use.
Influence of Water on the Preparation of Thick Mesoporous Silica Coatings by the Electrophoretic Deposition Method
Authors: Negishi Hideyuki , Endo Akira , Miyamoto Ai , Sakaki Keiji , Ohmori Takao
Published: September 2009

Ordered mesoporous silica (MPS) is expected to be used as an adsorbent for energy-efficient desiccant cooling systems. For practical use, it is important to be able to fabricate thick MPS coatings on metal supports. As we reported previously, MPS coatings on metal substrates can be formed using the electrophoretic deposition (EPD) method. Since MPS adsorbs a certain amount of water depending on the relative humidity, the amount of water adsorbed in MPS influences electrification, dispersion stability, and EPD behavior. In this study, we investigated the influence of water on the formation of thick MPS coatings by using an acetone bath. MPS powder was placed in a humidity-controlled vessel prior to EPD to adsorb water. The deposited amount tended to increase when dry MPS powder was used and when the water content of the acetone was reduced. In addition, the deposited amount was constant for 24 hours or more when the MPS powder was immersed in acetone containing 0.15 vol% of water. We found that dried MPS powder and acetone containing less than 0.45 vol% water were suitable for the stable preparation of thick MPS coatings. Consequently, 100 m-thick MPS coatings were successfully fabricated with the EPD method using dried MPS powder and an acetone bath containing 0.15 vol% water
Processing and Characterization of Biocompatible Titania Coatings by Electrophoretic Deposition
Authors: Santillán M. J. , Quaranta Nancy E. , Membrives F. , Roether Judith A. , Boccaccini Aldo Roberto
Published: September 2009

The electrophoretic deposition (EPD) technique was developed for depositing TiO2 films on stainless steel (SS) and titanium substrates. Titania coatings were obtained in conditions of optimal solution stability using acetylacetone suspensions of TiO2 nanoparticles and I2 at pH≈ 5. Deposition tests were carried out at 10V for varying times. The deposit thickness was seen to increase with EPD time, revealing that the deposits grew quickly for times <120 s, reaching a saturation value at longer times. The substrates were treated by physical and chemical methods before EPD in order to improve the adhesion of the films. The EPD coatings were sintered at 700, 800 and 900 °C under controlled argon atmosphere or in vacuum to study the influence of sintering atmosphere on crystalline phase transformation. The TiO2 coatings were characterized by XRD using Rietveld analysis. The results showed that TiO2 films on Ti substrates (chemically leached before deposition) had better adherence, homogeneity and density than those on SS. The coatings sintered al 700°C in vacuum resulted in a major proportion of anatasa phase. The porosity of the titania coatings sintered at 700°C (2 hr) in vacuum was calculated to be 19% .
Electrophoretic Deposition of Smectite Particles onto Cupper Plate
Authors: Watanabe Hideo , Matsushima Hideki , Fuji Masayoshi , Takahashi Minoru
Published: September 2009

Layered clay has been of great interest because of their nano-sized layer structure and hence intercalation and ion-exchange capacity to be used as a host material of composite with polymers and/or metals. In this study, smectite as a silicate-layered clay was easily exfoliated and dispersed into purified water, and was deposited onto a cupper plate for which dc voltage ranging from + 1.0 V to + 6.0 V was applied with respect to a counter platinum plate electrode. The cupper plate was pre-treated by chemical and chemical mechanical polishing (CP and CMP) prior to the electrophoretic deposition (EPD). The surface roughness of the substrate as well as the smectite film formed was characterized by an atomic force microscope (AFM). The thickness of smectite layer was estimated using an X-ray fluorescence (XRF) analysis as well as a scanning electron microscope (SEM) observation. The layer thickness can be described as a function of operational parameters such as applied voltage and operating time. Smooth smectite film with thickness ranging from 100 nm to 10 μm has been successfully fabricated onto the CMP cupper plate by the EPD method in this study.
Fly Ash Cenospheres Coatings by EPD-Microwave Sintering Process for SiC Corrosion Resistance
Authors: Chávez-Valdez Alejandra , Vargas-Gutiérrez Gregorio , Almanza-Robles J.M. , Arizmendi-Morquecho Ana
Published: September 2009

Fly ash cenospheres coatings are a promising material in improving the oxidation and corrosion resistance of SiC. In this work, fly ash cenospheres coatings were deposited on SiC substrates by electrophoretic deposition process at 500 V during 30 seconds, 1, 2 and 3 minutes. These coatings were characterized by SEM to observe the surface morphology. The coatings were sintered at 1000, 1100 and 1200°C during 3 hours by microwave heating. After sintering, the coatings were characterized by XRD. Cross sections of the substrate/coating samples were analyzed by SEM/EDS. The coatings with the best deposition and sintering conditions were evaluated by oxidation and hot corrosion resistance tests. The oxidation test was performed in air at temperatures from 1000 to 1300°C during 100 hours. In addition, fly ash cenospheres coatings on SiC and uncoated SiC substrates were subjected to a hot corrosion test at 1000°C during 100 hours in Na2SO4. The coatings showed good adhesion after sintering; the main phases of the coating were mullite and SiO2. The uncoated substrates were found to gain weight due to the formation of SiO2 at the surface. In contrast, SiC samples coated with fly ash cenospheres showed no weight gain and exhibited no signs of cracking or spallation following the oxidation tests. After the high temperature corrosion test in Na2SO4, the uncoated SiC showed signs of oxidation and corrosion while the coated remained unreacted in the presence of molten Na2SO4, indicating that the electrophoretic deposition fly ash cenospheres acted as a hot corrosion barrier for SiC substrates.
Alumina and Zirconia Based Composites: Part 1 Preparation
Authors: Hadraba Hynek , Maca Karel , Chlup Zdeněk
Published: September 2009

Electrophoretic deposition of Al2O3 and ZrO2 powders from isopropanol suspension in the presence of monochloroacetic acid under constant-current conditions was studied. The similar charge and electrophoretic mobility of Al2O3 and ZrO2 in the suspensions was found. Adjusting to properly controlled kinetics of deposition deposits were prepared of pre-defined thicknesses. In view of the negative charge of Al2O3 and ZrO2 particles in the isopropanol suspensions used, the prepared layers were deposited on the anode and thus they were not affected by possible solvent electrolysis, which contributed to their defect-free and low-porosity structure.
Galvanostatic Electrophoretic Deposition of Yttriumsilicate on C/C-Si-SiC Composites
Authors: Grosse-Brauckmann Jana , Damjanović Tanja , Argirusis Christos
Published: September 2009

The use of carbon fibre reinforced carbon composites in oxidizing atmospheres is limited to temperatures below 400 °C. To benefit from their excellent mechanical strength that is still preserved at high temperatures, suitable oxidation protection coating systems have to be developed. Composites which are capillary infiltrated with Si and coated with SiC via chemical vapour deposition show significantly enhanced oxidation resistance. For the increase of service temperature above 1300 °C, high temperature stable materials with low oxygen diffusivities such as yttrium silicates have to complement the SiC coating. The electrophoretic deposition performed under constant current conditions leads to relatively high green densities and therefore good sinterability of the applied coatings. In this work we present the preparation of suspensions, their characterization regarding particle size and electrophoretic mobility for yttrium silicate powder prepared by the solid state method. Depending on particle charge and conductivity of the investigated suspensions iodine is employed to increase particle charge. The use of current densities between 0.5-5mA/cm² leads to smooth and homogeneous layers. Layers sintered as low as 1400 °C for 2h already show promising protection of the C/C-Si-SiC substrate during thermogravimetric analysis.
Electrophoretic MEA Fabrication for High Performance DMFC
Authors: Munakata Hirokazu , Omori Suguru , Kanamura Kiyoshi
Published: September 2009

Anode for direct methanol fuel cell (DMFC) was fabricated on Nafion 117 membrane by electrophoretic deposition (EPD) method. An ethanol suspension containing Pt-Ru/C and Nafion ionomer was utilized, in which Pt-Ru/C and Nafion ionomer formed composite particles. The prepared electrode was tightly attached to the membrane without mechanical pressing and heat treatment. The electrode composition, i.e., the ratio between Pt-Ru/C and ionomer in the electrode, was controllable by Nafion content in the suspension, and strongly influenced on the DMFC performance. Accordingly, the anode with ionomer fraction of 26% exhibited the highest performance, which was more than twice as high as the performance attained in a standard electrode fabrication (hot press method).
Preparation and Electrophoretic Deposition of an Yttrium Silicate Precursor Sol
Authors: Grosse-Brauckmann Jana , Borchardt Günter , Argirusis Christos
Published: September 2009

. In the present work we used the sol-gel process to prepare Y2SiO5 precursor sols suitable for electrophoretic deposition (EPD). The sol synthesis was performed through the controlled hydrolysis of alkoxide solutions of tetraethoxysilane and yttriumoxoisopropoxide. During sol development emphasis was put on characterization of particles size and zeta potential of the formed aggregates. We succeeded in synthesizing a clear sol containing polymeric aggregates with acceptable particle charge. The electrophoretic deposition on glassy carbon or C/C-SiC slabs led to homogenous layers. At low sol concentrations micro cracks in the deposited layers were observed whereas higher concentrations led to thin and dense layers. During constant current EPD a constant voltage was recorded indicating that the deposited layer does not lead to an increase in resistivity in this kind of EPD system.
Controlling of Surface Parameters of Particles Used for Electrocodeposition
Authors: Bellmann Cornelia , Caspari Anja , Grundke Karina
Published: September 2009

It is well known that colloid-chemical aspects, such as agglomeration processes, wetting and adsorption phenomena, have a decisive influence on the separation behaviour and coating quality of a composite plating. The following processing steps for electrocodeposition have to be considered: preparation of a stable dispersion of the particles in the electrolytic bath, transportation of the particles to the metal surface, adhesion of the particles onto the surface, incorporation of the particles in the metal matrix. Celis [1,2] and Hyashi [3] could show that ion adsorption onto the particle surface is very important for electrophoretic mobility and layer quality. On the other site, Fransaer and others [2,4] showed that surface free energy plays an important role for incorporation of particles in a metal matrix. They could demonstrate that hydrophilic particles do not make contact with the electrode, probably due to repulsive hydration forces. Hydrophobic particles make contact with the electrode, due to an attractive hydrophobic force. Hence it is important to have a method for estimating the hydrophilic/ hydrophobic surface properties of such particles to select a suitable surface modification strategy. A direct way to measure the surface free energy of solid particles is not available so far. Therefore, it is generally accepted to use the phenomenon of capillary penetration of liquids into porous media to determine the wetting properties of particles by measuring the penetration velocity of well-defined liquids in a powder packing. The kinetics of penetration correlates mainly to the geometric structure of the powder packing and the wettability of the particles. By using the equation-of-state approach for solid-liquid interfacial tensions the solid surface free energy of the particles can be determined [5]. In this paper, we show the usefulness of capillary penetration experiments and discuss some parameters that should be considered for the interpretation of the data. Ion adsorption processes, on the other hand, can be described by electrokinetic measurements [6,7].
Aging Behavior of Yttria Stabilized Zirconia (YSZ) in Non Aqueous Suspensions for Electrophoretic Deposition Application
Authors: Borojeni Iman Azarian , Raissi Babak , Maghsoudipour Amir , Kazemzad Mahmood , Marzbanrad Ehsan
Published: September 2009

In this research aging behaviors of yttria stabilized zirconia (YSZ) in non aqueous suspensions, namely ethanol, isopropanol, n-propanol, acetylacetone and the mixture of ethanol-acetylacetone were investigated. For this purpose, electrical conductivity, electrophoretic mobility and suspension stability during aging time (6 to 7 days) were evaluated. Except for the ethanol-acetyl acetone mixture, each suspension contained 0 to 0.8 g/L iodine. It was revealed that, the alcoholic suspensions indicated lower conductivity in comparison with acetylacetone suspensions. However, acetylacetone suspension showed lower conductivity variation with time. Although iodine could improve the electrophoretic mobility of ethanol and acetylacetone suspensions, it had little effect on electrophoretic mobility of isopropanol and n-propanol suspensions. Also, it was indicated that iodine as a dispersant was not helpful for alcoholic suspensions stability. It was concluded that the mixture of acetylacetone-ethanol suspension was the best candidate in this study for electrophoretic deposition of YSZ, owing to its little behavior variation with the aging time, low conductivity and high electrophoretic mobility. High quality crack-free layers were electrophoretically deposited from this suspension on the substrate by applying 50 V/cm electrical field.
Surface Modification of SiC Powder for Use in Electrophoretic Deposition
Authors: Sakakibara Saki , Suzuki Tohru , Matsuda Atsunori , Uchikoshi Tetsuo
Published: September 2009

The surface modification of SiC powder with an alumina precursor was achieved by a sol-gel method to apply the electrophoretic deposition (EPD) technique to the shaping of the SiC powder. The isoelectric point of the surface-modified SiC powder with sol-gel-derived alumina precursor was shifted to around pH 9, which is close to that of alumina. The alumina-coated SiC deposited on a cathodic substrate by EPD. The green compact of surface-modified SiC powder was sintered by hot pressing in an argon atmosphere at 2000oC.
Fast Deposition of Surface Structures by Two-Step EPD
Authors: Nold Alexander , Zeiner Johannes , Clasen Rolf
Published: September 2009

In this paper, the feasibility of obtaining well-defined compact EPD deposits in a short time was studied. EPD from organic and aqueous suspensions were tested. The formation of bubbles coming from solvent electrolysis damages the deposits. 4 different EPD geometric configurations were developed and tested with different experimental conditions. One of them, consisting of both electrodes tilted 30° helped to avoid bubbles getting trapped in the deposit. Our preliminary results showed that there is a very strong influence of the voltage applied, and the separation distance between the electrodes, over the width and height of the structures deposited. Working with aqueous suspensions is more suitable than with organic solvents from the environmental point of view. More work needs to be done in this direction to improve the quality of the deposits and to fine-tune the experimental conditions.
Near Net Shaping with Bimodal Powders on Shaped Membranes via EPD
Authors: Clasen Rolf , Oetzel Christian
Published: September 2009

The electrophoretic deposition (EPD) is a very promising process for shaping compacts, especially for nanopowders. Up till now EPD is not used on a large-scale production of ceramic products. Additionally, the higher cost of nanopowders was also a barrier for the development of new products. As the deposition rate at EPD is independent of particle size, it is an ideal process for shaping compacts of powder mixtures with nanopowders. Silica and zirconia powders were used as model systems to demonstrate the advantages of EPD. Applications might be the preparation of high-purity silica glass for processing of semiconductors and zirconia ceramics for near net-shaped dental crowns. In both cases the optimum green density was achieved for approx. 10 % addition of nanopowders to a coarser matrix powder. The compacts were homogenous. Alternatively, compacts of different powders can be prepared in a two-step process. Examples are shown for the electrophoretic impregnation (EPI) and a reactive forming of nanoparticles inside the pore volume of a compact consisting of coarser particles.
Probability of Fault Location in a Beam Structure Using the Spectral Element Method and the Spatial Wavelet Analysis
Authors: Gherlone Marco , Ruotolo Romualdo , Surace Cecilia
Published: September 2009

The aim of the work is to develop a procedure allowing the test engineer to determine the probability of finding a crack in a beam structure. The procedure is based on the use of wavelet analysis and the simulation is performed by taking advantage of spectral elements to represent accurately the dynamic behaviour of beam structures in the high frequency range. In this context, numerical analyses are performed with the final scope of simulating a real testing environment: measurement error is considered and spectral elements are used so as to avoid influencing the capacity of the procedure with regard to solving the inverse problem. In this article the relation between the excitation frequency and the probability of locating the fault is shown. In particular, it is demonstrated by simulation that the probability of correctly determining the fault location increases with the excitation frequency.
Identification of Crack Parameters in a Cantilever Beam under Uncertain End Conditions
Authors: Wang Zhi Hua , Jing Lin , Zhang Wei Wei , Ma Hong Wei
Published: September 2009

The local effect of “softening” at the crack location can be simulated by an equivalent spring connecting the two segments of the beam. As modelling the crack, the non-perfectly rigid clamp is also simulated as a torsional spring of unknown stiffness. Combined with the Bernoulli-Euler theories of beam, the present model is applied to derive the characteristic equation of the cantilever beam under uncertain end conditions related to the crack parameters, namely, the location and the depth of the crack. Based on this characteristic equation, an accurate crack identification method is developed to identify the location and the depth of the crack by minimizing the difference between the analytical and experimental frequency values. The proposed approach is verified by two cantilever beam experiments under ideal boundary conditions and uncertain end conditions. It is found that the location and the depth of the crack can be worked out when at least three natural frequencies are known. For crack identification of the cantilever beam under uncertain end conditions, the identified crack location of the proposed approach is more accurate than the Narkis’ method. Furthermore, the crack depth can also be obtained by the present method.
Investigation Frequency Resolution Effect on Hilbert Spectrum for Instantaneous Vibration Impact Signal Analysis
Authors: Li Hong Kun , Zhang Zhi Xin
Published: September 2009

Instantaneous impact signal analysis investigation and feature extraction have been broadly investigated by many researchers. How to determine an effective time-frequency distribution analysis method is urgent needed. In this paper, Hilbert spectrum frequency resolution is investigated to show signal typical features according to performance estimation model. Different frequency units for a Hilbert spectrum expression will be investigated on the effect of feature analysis in detail. An estimation model will be constructed to determine the best frequency resolution for signal analysis. By using this estimation, frequency resolution can be determined. This model can improve the performance of Hilbert spectrum to show signal features and accuracy for signal analysis and pattern recognition. To testify the effectiveness of this estimation model, numerical simulation will be used as an example to analyze the accuracy of this model. At the same time, different bearing working condition’s pattern recognition based on Hilbert spectrum will be used to testify the effectiveness of this model.
Acoustic Emission in Structural Health Monitoring
Authors: Holford Karen M.
Published: September 2009

Structural Health Monitoring (SHM) is of paramount importance in an increasing number of applications, not only to ensure safety and reliability, but also to reduce NDT costs and to ensure timely maintenance of critical components. This paper overviews the modern applications of acoustic emission (AE), which has become established as a very powerful technique for monitoring damage in a variety of structures, and the new approaches that have enabled the successful application of the technique, leading to automated crack detection. Examples are drawn from a variety of industries to provide an insight into the current role of AE in structural health monitoring.
Application of Hilbert-Huang Transform Method on Fault Diagnosis for Wind Turbine Rotor
Authors: Huang Qian , Jiang Dong Xiang , Hong Liang You
Published: September 2009

Many signals of wind turbine faults are non-stationary and have highly complex
time-frequency characteristics. Traditional time-frequency analysis method, such as Windowed
Fourier Transform method, has no noticeable effect in handing non-stationary signals. Hilbert-Huang
Transform (HHT) is a new signal processing method for analyzing the non-stationary mechanical
signals. Based on Empirical Mode Decomposition (EMD), the Intrinsic Mode Function (IMF) in
HHT can reflect the intrinsic physical characteristics of original data. Moreover, it is a good way to
identify the faults involving a breakdown change. First, the principles and advantages of the HHT are
presented in detail in this paper. Then, three typical faults of wind turbine rotor, such as rotor
imbalance, aerodynamic asymmetry due to blade surface roughness and yaw misalignment are
discussed by the HHT. Last, reasonable conclusions are drawn by the comparison between this
method and the Wavelet Transform (WT) method with the help of simulation fault signals. The
results show the effectiveness of HHT method for diagnosing those faults of wind turbine rotor.
The Response Characteristics of Various Impact Patterns on the Smart Bumper of Automotives
Authors: Hong Yong , Wang Gao Ping , Go Yeon Gon , Hong Dong Pyo , Chung Tae Jin
Published: September 2009

In this paper, a pendulum system is constructed to perform the fundamental research which is concentrated on the various frequency patterns of impact-object simulation tests. We confirmed the application possibility for the method of discriminable pattern recognition whether impact-object is human-like or not via frequency analysis using smart sensors. Therefore a specific experimental data are compared and analyzed with the obtained database within a short time period. The impact analysis system, which is based on the above processing, can be developed and then used to recognize the impact information measured by smart sensors.
Implementation of Reliability-Based Criteria for Structural Integrity Assessment of Existing Structures
Authors: Diamantidis Dimitris
Published: September 2009

This contribution discusses the implementation of reliability-based criteria including target safety level, residual life time, economical constraints and inspected present condition of the structure in order to assess its structural integrity. Thereby global failure is emphasized and aspects such as structural robustness and progressive collapse are implemented. Recent requirements in standards are reviewed and practical recommendations are provided. Case studies regarding re-qualification of existing structures are briefly presented, especially with respect to the aforementioned aspects. The summarized studies deal with a) reanalysis of deteriorated platforms in the North Sea and in West Africa subjected to extreme environmental actions and b) reevaluation of subway structures in Central Europe after damage due to flooding. Conclusions and suggestions for the reassessment of existing structures are finally given.
Enhanced Assessment of the Remaining Service Life of a Steel Railway Bridge
Authors: Leander John , Andersson Andreas , Karoumi Raid
Published: September 2009

During annual inspections of one of Sweden’s most important railway bridges, the Söderström Bridge in central Stockholm, cracks in the web of the main steel beams have been discovered. Extensive theoretical work has been undertaken to assess the remaining service life of the bridge. Furthermore, the bridge has recently been instrumented to enhance the theoretical predictions by monitoring the real railway traffic as well as the response of the bridge. This article describes the monitoring program and the analysis methods used. Some interesting results regarding the remaining fatigue life are presented.
Numerical and Experimental Investigation of the Sensing Area of Piezoelectric Elements for Damage Detection with the E/M Impedance Method
Authors: Xing Ke Jia , Schulte Rolf T. , Fritzen Claus Peter
Published: September 2009

During this decade, piezoelectric elements are explored and applied successfully in SHM, which has positioned them as an enabling technology for damage assessment. When permanently bonded to the structure, they provide the bi-directional energy conversion, which is used in impedance-based SHM. In this method, the variations of the structure’s impedance are monitored by piezoelectric elements. However, before experiments are performed, it is important to position correctly the piezoelectric elements on the structure. Therefore, the capability of piezoelectric actuators is explored under the aspect of sensor position.
This work presents the investigation of sensing ability of surface-bonded piezoelectric element using numerical simulation and experiment. The results of numerical and experimental investigation are shown in this paper, which illuminates the model in the aluminium plate could be used to predict the state of it. In the experimental investigation, it also shows the factors which influence strongly the capability of sensor detection.
Dealing with high frequency excitation, calculation requires a very dense finite element mesh, hence, the spectral element method (SEM) is chosen as model-based method, which is much more efficient than classical FEM. The structure, self-sensing elements as well as damage are modelled, from which the spectra of E/M impedance is computed. It gives the theoretical basis for the experiment design. The numerical results are verified and validated by experimental investigation. With such a numerical tool, the efficiency of the E/M impedance method can be clearly improved with respect to the determination of suitable piezoelectric element locations.
A Review on Advances of Damage Identification Methods Based on Vibration
Authors: Yan Jun Xia , Liu Chu Sheng , Liu Tong Zeng , Zhao La La
Published: September 2009

Damage identification methods based on Vibration are summarized in the paper. Their specialities are compared. Some problems of damage identification technology based on vibration and the past, current applications of the technology to mechanical engineering are introduced. The critical issues for further research in this field are also pointed out.
Development of Many-Angular Pin Type Load Cell for a Overload Limiter of a Movable Crane
Authors: Han Dong Seop , Ha Jung Min , Han Geun Jo
Published: September 2009

An overload limiter is used to prevent its overturning accident during an operating of a movable crane. Recently the indirectly measuring method, which measures hoisting load and overturning moment of overload limiter, demands instead of the existing method, which measures only hoisting load. The indirectly measuring method is how to conduct the hoisting load and overturning moment as measuring the load of hydraulic cylinder for a luffing driving of boom. So we need to develop the many-angular pin type load cell with the measuring angle of ±10 degree instead of the existing load cell with the measuring angle of ±2 degree. In this study we conducted the finite element analysis in order to evaluate the effect of the aspect ratio of measuring cross section on the measuring limit of the load cell to develop the many-angular pin type load cell. For this investigation, the aspect ratio of measuring cross section and load applying angle were adopted as design parameters and the stresses of measuring part were evaluated for each parameter.
Spur Gear Crack Propagation Assessment Using Model-Based Analysis and Simulation
Authors: Tian Zhi Gang , Zuo Ming J.
Published: September 2009

Model-based gear dynamic analysis and simulation has been a promising way for
developing e®ective gearbox vibration monitoring approaches. In this paper, based on the dynamic model of a one-stage gearbox with spur gears and one tooth crack, we investigate
statistical indicators and the discrete wavelet transform (DWT) technique to identify e®ective
and sensitive health indicators for re°ecting the crack propagation level. Our results suggest
that the root mean square (RMS) indicator is a good statistical indicator to re°ect the crack
propagation in the early stage; DWT can improve the sensitivity of the RMS indicator and the
RMS indicator becomes more sensitive with the increase of the DWT level.
Influence of Fatigue Loading on the Engineering Critical Assessment of Steel Catenary Risers in Sour Deepwater Oil and Gas Developments
Authors: Holtam Colum M. , Baxter David P. , Thomson Rachel C. , Ashcroft Ian A.
Published: September 2009

Steel catenary risers (SCR) are used in deepwater oil and gas developments to transfer produced fluids from the seabed to surface facilities. SCRs can be subject to fatigue loading from a variety of sources including wave and tidal motion, vortex induced vibration (VIV) and operating loads. When the produced fluids are sour (ie contain water and H2S) higher fatigue crack growth rates (FCGR) are expected, and this can have a significant effect on defect tolerance.

The aim of this paper is to provide guidance on the current best practice methods for performing engineering critical assessments (ECA) on internal surface breaking defects in SCRs operating in a sour environment and subject to VIV fatigue loads. Example ECA calculations are presented for circumferential girth weld flaws, based on the failure assessment diagram (FAD) approach within the framework of BS 7910 [1]. The influence of certain key input variables is demonstrated, including the FCGR, determined from recent sour test data generated as part of this research.