bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Technological Process of Cerium-Based Conversion Coating on Aluminum
Authors: Xu Ji Hui , Wang Xin , Wang Jing , Zheng Qiu Ju
Published: September 2009

The Cerium-based conversion coating is formed on the industrial aluminum(1060) by using chemical immersion. The microstructures of the conversion coating have been examined by scanning electron microscopy(SEM). The electrochemical measurement result shows that the corrosion resistance of aluminum is significantly improved after the conversion coating was formed. The result of X-ray photoelectron spectroscopy (XPS) shows that the cerium conversion coating mainly consisted of oxide of aluminum, CeO2 and TiO2. The formation mechanism of the Cerium-based conversion coating is investigated.
Synthesis of CdS Nanoparticle/Amphiphilic Block Copolymer Composite Films and its Characteristics of Microstructures and Optoelectronic Properties
Authors: Yu Yang Yen , Chien Wen Chen , Chou Yu Heng
Published: September 2009

In this study, block copolymers of PS-b-PMSMA with various molecular weight were synthesized by atom transfer radical polymerization (ATRP). GPC analysis showed that the molecular weight distribution of the prepared PS-b-PMSMA could be controlled to be lower than 1.3 for the case of molecular weight less than 30,000. The chemical structures of the amphiphilic block copolymers of PS-b-PMSMA were well identified by FTIR. SEM showed that the spherical micelles and compound micelles were produced in hybrid films. The EDX analysis indicated that the nano-sized CdS particles have been successfully prepared in the PS-b-PMSMA composite films. The diameter of CdS particles calculated from Brus formula was about 4-5 nm. PL analysis revealed that the λmax of emission of the prepared composite materials had a red-shift as the CdS particle size increased.
Effect of Annealing on Magnetic Properties and Domain Structures of FePt Thin Films by Rapid Thermal Annealing Technique
Authors: Chen Sheng Chi , Sun T.H. , Kuo Po Cheng
Published: September 2009

Single-layered FePt films of 30 nm thick were annealed at temperature between 300 and 800 °C for 1–180 sec by a rapid thermal annealing (RTA) with a high heating rate of 100 °C/sec. It is found that both the grain size and magnetic domain size of the FePt film increase with increasing annealing temperature and annealing time. The FePt films exhibited soft magnetic properties and without domain images were observed by magnetic force microscope (MFM) when the films were post-annealed at below 500 °C for 180 sec. The in-plane coercivity (Hc//) and perpendicular coercivity (Hc⊥) of FePt film increases significantly to 7.5 and 6.5 kOe respectively as annealing temperature increases to 600 °C. When the annealing temperature is increased to 700 °C, they are increased to 11.1 and 9.5 kOe, respectively, and the domain structure inclines to isolated domain. However, further increasing the annealing temperature to 800 °C, the Hc// and Hc⊥ values decrease to 9.8 and 8.9 kOe respectively due to largely increase the grain size of FePt and change the domain structure from isolation to continuity. On the other hand, in order to transform the FePt film from disordered γ phase to the ordered L10 phase, the annealing time of over 3 seconds is necessary when the film was post-annealed at 700 °C with a high heating rate of 100 °C/sec by RTA technique.
Influence of Substrate Temperature on the Characteristics of LaB6 Films
Authors: Xu Jing , Min Guang Hui , Zhao Xiao Hua , Yu Hua Shun
Published: September 2009

Lanthanum hexaboride (LaB6) films were deposited on SiO2 substrates in a vacuum chamber by d.c. magnetron sputtering from Lanthanum hexaboride pellet target. The fabricate temperature was adjusted from per 50°C. The influence of fabricate temperature on the characteristics of the films was studied. The surface morphology was studied by atom force microscope (AFM). The results of the AFM proved that the films were compact and even. Maximum roughness of the films is no more than 15.1 nm, and the average roughness is less than 3.1nm. The results of XRD showed that the structure of the films is crystal, except the film that fabricated at the temperature of 500°C. It is noticeable that the (100) crystal face is dominated in the film, and that is different from the bulk LaB6. The crystallization of the films changed obviously. Films that fabricated at 400°C crystallized better than others. The film thickness was measure using a Stylus Profiler. The results of the Stylus Profiler proved that the temperature showed little effect on the thickness of the films.
Coating Time Effect on Surface Structures of Silica-Encapsulated Gold Nanoparticles
Authors: Qu Qin , Liu Shan Tang
Published: September 2009

This paper reports the silica density, surface structures and optical properties of gold nanoparticles coated with different thickness of silica shells. The gold nanoparticles encapsulated with amorphous silica shells were prepared in a slight modification of Stǒber method. The silica-shell thickness could be varied from 20 to 50 nm by controlling the experimental conditions, such as reaction time. Transmission Electron Microscopy (TEM) and UV-Visible absorption spectroscopy were employed to characterize the size, shell density, surface structures and the optical properties of these silica-coated gold nanoparticles. The TEM images demonstrated that the density of the silica shell were depended on the reaction time, and the surface morphology was changed from porous structures in the initial coating to the final continuous and smooth silica surface. With the increasing of the reaction time, the silica-coated gold nanoparticles became more and more round and monodispersed. UV-Vis spectra showed that surface plasmon absorption peak had a red-shifted of 3~12 nm on increasing the thickness of silica shell from 20 to 50 nm. A possible mechanism of silica formation on gold nanoparticles was proposed on the basis of silica shell density and the shift of absorption peak of coated gold nanoparticles.
Effect of Gelatin on the Performance of Cerium-Based Conversion Coatings
Authors: Liu Hao Quan , Wang Xin , Xu Ji Hui , Liu Qiang , Gu Song Tao , Jiang Gui Jun , Zhou Meng
Published: September 2009

Cerium-based conversion coating process for corrosion protection is a potential replacement of chromates. However, there are still some defects such that the processing time is too long and the conversion coatings are not thick enough. The experiment proves that compared to non-added animal gelatin in corrosion-inhibiting cerium solution, the added one improves the deposition rate. After post-treatment process in phosphate, the surface morphology of the coatings is tested by scanning electron microsopy (SEM), the chemical composition of the protective films have been examined by energy-dispersive Spectrometer (EDS) and thickness of films is measured by coating thickness gauge.
Visible Light Activated Photocatalytic Degradation Effect of V-TiO2 on Azo Dye Wastewater
Authors: Cheng Ta Chih , Yao Kuo Shan , Hsieh Yung Hsu , Chang Ming Yi , Chang Chen Yu , Wang Guan Hao
Published: September 2009

In this study, the V-doped TiO2 was synthesized by sol-gel method and we evaluate the photocatalytic degrading efficiency of V-TiO2 complexes on azo dye wastewater under irradiation with visible light (λ= 419 nm). The results showed that the Anatase structure and nano size of V-TiO2 complexs were formed and they had better photo-response to visible light than pure TiO2. The efficiency of decoloriztion or destruction efficiency was less than 6 % using TiO2 alone but efficiency of 0.10VT-I was up to 90% after irradiated with visible light for 240 min. These evidences also reveal that the system of V-TiO2 complexes can directly utilize the sunlight and can be used to treat organic pollutants in the practical wastewate treatment factories.
Microstructure of the Passive Layer Formed on Different Austenitic Stainless Steels Implanted with Molybdenum
Authors: Abreu C.M. , Cristóbal M.J. , Figueroa Raul , Nóvoa Xosé R. , Pena G. , Pérez M.C.
Published: September 2009

Two austenitic stainless steels have been implanted at 150 keV with Mo at a fluence of 3.5x1015 ions/cm2. The effects of ion implantation in the chemical composition of the passive films was evaluated by x-ray photoelectron spectroscopy (XPS) and glancing angle x-ray diffraction (GAXRD) was used to determine the induced structural modifications. The results of the pitting corrosion studies carried out in neutral chloride medium as well as the morphology of the localized attack are discussed.
Implications of Diffusion on the Composition and Microstructures of Platinum Modified Aluminide Coatings on CMSX-4 Single Crystal Superalloy
Authors: Pedraza-Diaz Fernando
Published: September 2009

State-of-the-art aluminide coatings for high pressure aeroturbines rely on their chemical stability through the addition of platinum. In this work, the influence of diffusion on the composition and microstructure of Pt/Al coatings is investigated upon the different processing steps. Upon heat treatment of the electrodeposited Pt layers, the ready solubility of Pt in the ’-Ni3Al and its concentration gradient allow fast ingress of this element in the coating in spite of the higher diffusion coefficients of the substrate elements. The relatively high Pt contents at the surface thereafter promote Al ingress upon aluminisation by creating a greater concentration gradient between the coating atmosphere and the coating. This results in a -NiAl based coating grown by both Ni outward and Al inward diffusion. The diffusivity of Pt, Ni and Al being dependant on the stoichiometry of the -NiAl coating, different metal particles may precipitate mainly at the NiAl grain boundaries. In addition, the diffusion of the refractory elements towards the interdiffusion layer seems to be hurdled by increasing the Pt content. As a result of the countercurrent diffusion of species, different microstructures and compositions will appear across the coatings.
Photo-Induced Relaxation Self-Oscillations of Stripe Structures in FeBO3
Authors: Chzhan A. V. , Patrin G.S. , Isaeva I.N.
Published: September 2009

Photo-induced self-oscillations of stripe structures are studied in FeBO3 crystals at low temperatures. Experimental data show that the observed oscillations have a relaxational character. On the basis of the research carried out, a model for such oscillations is presented.
Theoretical Investigations of the Spin Hamiltonian Parameters and Defect Structure for Pt3+ in MgO
Authors: Hu Yue Xia , Wu Shao Yi , Wang Xue Feng , Li Li Li
Published: September 2009

The spin Hamiltonian parameters (anisotropic g-factors and the hyperfine structure constants) and defect structure for Pt3+ in MgO are theoretically investigated by using the perturbation formulas of these parameters for a 5d7 ion in a tetragonally elongated octahedron. This impurity center is attributed to substitutional Pt3+ on host Mg2+ sites, and the [PtO6]9 cluster suffers a relative elongation of 0.08Å along the C4 axis due to the Jahn-Teller effect. In the calculations, the contributions arising from the ligand orbital and spin-orbit coupling interactions and the Jahn-Teller elongation are taken into account using the cluster approach. The calculated spin Hamiltonian parameters based upon the above defect structure show good agreement with the observed values.
Chemical Precipitation Synthesis and Magnetic Properties of Hematite Nanorods
Authors: Li Qiao Ling , Wang Yong Fei , Zhang Cun Rui
Published: September 2009

One-dimensional (1D) hematite (α-Fe2O3) nanorods have been successfully prepared using a chemical precipitation method. The sample was characterized by using a variety of techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The results showed that the nanorods obtained were monocrystalline, with an average diameter of about 60nm and a length of up to 800nm. In the preparation of α-Fe2O3, the length of α-Fe2O3 seemed to increase with the addition of polyethylene glycol (PEG), and the diameter seemed to decrease with the addition of Zn2+. Nanorods of α-Fe2O3 with a smaller diameter and superior slenderness ratio were prepared by adding both PEG and Zn2+. A possible growth mechanism effect of PEG and Zn2+ upon the morphology of α-Fe2O3 was as follows: α-FeOOH grew in a one-dimensioned orientation upon the surface of a polyethylene glycol template. In the meantime, the Fe3+ position in the α-FeOOH crystal was substituted by Zn2+; resulting in point defects in α-FeOOH crystal due to the radius discrepancy between Zn2+ and Fe3+. The growth-step energy was then reduced as a result of the point defects in the α-FeOOH crystal. The results of magnetic measurements of the hematite nanorods revealed a weak ferromagnetic property which might be related to the shape anisotropy.
Solid State Preparation of TiO2 Nanoparticles in Optimal NaCl: TiOSO4 Weight Ratio and Milling Time
Authors: Salari Mary , Rezaee Masih , Marashi Pirooz
Published: September 2009

A solid-state reaction of TiOSO4.xH2SO4.yH2OTiO2 + (x+y)H2O + (x+1)SO3 was induced during milling to synthesis the titanium dioxide nanoparticles. Titanyl sulphate (TiOSO4.xH2O.yH2SO4) and NaCl powders were used as the reactant and diluent phases, respectively. Annealing the as-milled powder at 700°C along with diluent phase and the removal of the NaCl through washing resulted in fairly equiaxed anatase and rutile TiO2 nanoparticles with the mean size in the range of 15-55 nm. The effect of volume fraction of diluent phase (NaCl) and milling time on the particle size distribution, agglomeration and anatase to rutile phase transformation (AR) of TiO2 nanoparticles were investigated by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Investigations showed that increasing the NaCl: TiOSO4 weight ratio (NTR) leads to the formation of nanocrystalline anatase and rutile particles with more uniform size distribution, lower weight ratio of rutile phase and lower agglomeration of particles. Also, it was found that increasing the milling time can effectively decrease the nanocrystalline size of TiO2 down to 16nm and impede A  R transformation
Microstructure Evolution During Mechanical Alloying of Face Centered Cubic Ti3Si Nanoparticles
Authors: Wu Qiong , Li Chang Sheng , Tang Hua , Yu Xiao Hui , Cao Ke Sheng , Yang Jing Hai
Published: September 2009

Face centered cubic Ti3Si nanoparticles were synthesized by mechanical alloying process and the structural and compositional evolutions during the mechanical alloying process were investigated by X-ray diffraction and High Resolution Transmission Electron Microscopy. The results showed that the lattice parameter ratio c/a and the unit cell volume of Ti(Si) were found to decrease with increasing milling time, indicating that the shrinkage of Ti lattice was caused by diffusion of Si atoms into Ti. After milling 51h, amorphous compounds were obtained by alloying Ti and Si powders, and the following mechanical alloying process crystallized the amorphous alloy to crystalline Ti3Si nanoparticles. These nanoparticles were predominantly crystalline with traces of the remnant amorphous phase.
Nanoscaled C, Ni, Pt Thin Films
Authors: Wu Wan Yu , Hsu Chia Wei , Ting Jyh Ming
Published: September 2009

We have investigated the growth and characteristics of nanoscaled thin films of carbon, nickel, and platinum. The nanoscaled thin films were deposited on Si and quartz substrates with or without a surface layer of carbon, nickel, or platinum using a DC magnetron sputter deposition technique. The thicknesses, which were determined using ellipsometry, are all less than 10 nm. The film structures were examined using glazing angle incident x-ray diffractometry and Raman spectroscopy. The electrical and optical properties were determined using a four point probe technique and UV-VIS-IR spectrometry, respectively.
Fabrication of Copper-Alumina Nanocomposites by Mechanochemical Routes
Authors: Shehata F. , Abdelhameed M. , Fathy A. , Moustafa S.F.
Published: September 2009

Nanostructure composites of Copper-Alumina were successfully produced by new mechanochemical method using two different routes. First, route A was carried out by addition of coarse copper to aqueous solution of aluminum nitrate, and second, route B was also carried out by addition of coarse copper to aqueous solution of aluminum nitrate and ammonium hydroxide. In both routes, the mixtures were heated in air and milled mechanically to get the oxides powders of CuO and Al2O3. The CuO was reduced in preferential hydrogen atmosphere into fine copper. The composite powders have been cold pressed into briquettes and sintered in hydrogen atmosphere. The structure and characteristics of powders as well as sintered composites produced from both routes were examined by XRD, SEM, EDS, TEM and metallographic techniques. The results showed that, in both routes, nano-sized particles of alumina were formed and dispersed within the copper matrix. The structure revealed the formation of CuAlO2 spinel structure at copper alumina interface. Nanocomposites produced by route-B showed finer alumina particles of 30 nm compared to 50 nm produced by route-A resulting in improved properties in terms of relative density, macro and microhardness values.
Precursor to High Purity Carbon Nanotubes: A Step by Step Evaluation of Carbon Yield
Authors: Patil K.N. , Solanki Chetan S.
Published: September 2009

Yield of carbon nanotubes (CNTs) depends on numerous process parameters such as temperature of synthesis, type of catalyst, type of precursor, time of precursor flow and partial pressure of precursor gas as well as carrier gas, etc. Experiments were performed in order to find the optimum temperature of synthesis for varying time of precursor flow. The yield was evaluated in terms of mass of crystalline CNTs per gram of substrate and/or catalyst. The CNTs were grown on a calcium carbonate (CaCO3) substrate, with iron-cobalt (Fe-Co) as a catalyst, using acetylene (C2H2) as a precursor gas and argon (Ar) as a carrier gas. A three-stage purification process, incorporating two acid treatment steps and one annealing step, was used for purification which ensures high grade purity of CNTs. The highest yield of 21.4 g of CNTs per g of catalyst was achieved at 700oC for 60 min of synthesis. The CNTs were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman, Thermo-gravimetric analysis (TGA), and Gas chromatography (GC).
Mathematical Model of Homogenization Process of Alloying Elements in Binary Metal Nanosystems
Authors: Bulanov V.I. , Dmitriev A.N. , Krashaninin V.A. , Oglezneva Svetlana
Published: September 2009

The major problem of a powder material authority – the prediction of structural-phase composition in the production of new multicomponent materials by means of the mathematical description and making of the computer software for homogenization processes modeling in the binary metal-metal systems is solved. The objects of study are processes of nanopowders homogenization in solid-state metals nanosystems of the transition elements such as Fe-Mo, Fe-Cu, Fe-Ni, Fe-Cr. A complex theoretical and experimental study of homogeni¬zation processes in solid-state nanosystems is carried out. The analytical dependences of degree of homogenization on time and temperatures of the sintering process are established, the coefficients of mutual diffusion in systems are calculated, physical and chemical model of homogenization are offered, means of the computer nu¬merical analysis with visualization of the studied processes are created. The estimation of convergence of the numerical methods employed are carried out, the accuracy of calculations is determined, estimated calcula¬tions for considered systems are carried out. The obtained results will allow the reduction in the number of real experiments in the creation of new mate¬rials with required properties.
Hydrogen Diffusivity and Solubility in Pd Alloys Containing Nanometric Oxides
Authors: Azambuja Viviane M. , dos Santos Dílson S. , Fruchart Daniel
Published: September 2009

. The Pd0.97Zr0.03, Pd0.97Ce0.03 and Pd0.97Ce0.015 Zr0.015 alloys were produced and studied in the present paper with respect to the hydrogen diffusivity and solubility. These alloys in the conditions as melted and cold worked, heat treated and also internally oxidized were submitted to hydrogen permeation tests. It was observed that the hydrogen diffusivity is strongly affected by the internal oxidation due to nano-oxides formation in the samples. On the other hand, the hydrogen solubility increases with introduction of defects as dislocations and vacancies introduced by cold working as well as the precipitates due to the internal oxidation. The nature, size and distribution of the precipitates and their influence on the hydrogen permeation parameters are discussed in this work.
A History of the Fractography of Brittle Materials
Authors: Quinn George D.
Published: September 2009

The evolution of the science of fractography of brittle materials initially was driven by failure analysis problems. Early analyses focused on general patterns of fracture and how they correlated to the loading conditions. Many early documents are simply descriptive, but the curiosity of some key scientists and engineers was aroused. Scientific or engineering explanations for the observed patterns gradually were developed. Advances in microscopy and flaw based theories of strength and fracture mechanics led to dramatic advances in the state of the art of fractographic analysis of brittle materials. Introduction: This author was drawn backwards in time as he researched the current state of the art of fractographic analysis of brittle materials for his fractography guide book.[ ] Others have written about how the fractographic analysis of metals evolved (e.g., [ , , , ]), but there is no analogue for ceramics and glasses. The key scientists, engineers, and analysts who contributed to our field are shown in Fig. 1. Other work done by industry workers who were unable or loathe to publish is now lost, inaccessible, forgotten, or even discarded. It is the goal of this paper to review the key publications and mark the noteworthy advances in the field. Some deem fractography as the study of fracture surfaces, but this author takes a broader view. Fractography is the means and methods for characterizing fractured specimens or components and, for example, a simple examination of the fragments and how they fit together to study the overall breakage pattern is a genuine fractographic analysis.
The Effect of Neutron Irradiation on the Mechanical Properties of Advanced Silicon Nitride Nanocomposites
Authors: Koszor Orsolya , Horváth A. , Weber F. , Balázsi Katalin , Gillemot F. , Horvath M. , Fényi Balazs , Balázsi Csaba
Published: September 2009

There is a continuous need to develop structural and functional components to sustain fusion plasma under the very severe environment such as intense radiation or high temperature in fusion reactors. The reference Si3N4 and novel Si3N4 based nanocomposites with carbon nanotube, graphene or carbon black additions were irradiated in a controlled-temperature irradiation rig inside the Budapest Research Reaktor (BRR) at a temperature of 270 °C. In the irradiation channel of BRR the 1,5×1013 n/cm2 fluence can be reached in 700 hours. The effect of the neutron radiation on the mechanical properties of Si3N4 based nanocomposites with different carbon additives was investigated. In the case of 3-point bending test graphene and carbon nanotube added samples showed an increase in strength ~100-300 MPa after irradiation. 4-point bending strength measurements resulted in a significant increase of strength in the case of reference samples ~200-400 MPa and carbon nanotube added composites ~200-300 MPa after irradiation. Other samples showed no change in strength after irradiation.
Comparison of R-Curve Behavior of Si3N4 Measured by Indentation Method and Single-Edge V-Notched Beam Technique (SEVNB)
Authors: Špaková Jana , Dusza Ján
Published: September 2009

Study compare R-curve behaviour of silicon nitride obtained using Vickers indented beam specimens and single edge V-notched beam (SEVNB). R-curve measurement realized by Vickers indented beam was reported by Krause. Crack growth using single edge V-notched beam was observed in situ. The indentation experiments, in comparison with SEVNB method revealed higher R-curve values (KR=3.3 – 4.8 MPa.m1/2). The discrepancy in the R-curve results is attributed to inaccuracy related to the determination of indentation toughness. The indentation fracture toughness may include the aspects of crack opening behaviour, residual indentation stress intensity.
Influence of Microstructure on Mechanical Response of Silicon Nitride Ceramic Composites in Nano-, Micro- and Macro-Volume of Material
Authors: Shikimaka Olga , Grabco Daria , Balázsi Katalin , Danitsa Z. , Mirgorodscaia I. , Balázsi Csaba
Published: September 2009

The peculiarities of contact-induced deformation in nano-, micro- and macroscopic scale of silicon nitride ceramic composites have been studied by using quasistatic macro- and microindentation techniques, dynamic nanoindentation technique and microstructure investigations. The addition of multiwall carbon nanotubes (MWCNTs) to the ceramic matrix showed the modification of microstructure leading to the modification of mechanical behavior of material: increase of fracture toughness along with the decrease of hardness. The general tendency of hardness increase with decrease of deformation volume was observed for silicon nitride ceramics, as well as, a high fracture resistance in micro- and nano-deformed volumes of material.
Creep of FINEMET Alloy at Amorphous to Nanocrystalline Transition
Authors: Csach Kornel , Miškuf Jozef , Juríková Alena , Ocelík Václav
Published: September 2009

The application of FINEMET-type materials with specific magnetic properties prepared by the crystallization of amorphous alloys is often limited by their brittleness. The structure of these materials consists of nanosized Fe-based grains surrounded with amorphous phase. Then the final macroscopic mechanical properties are considerably influenced by the properties of this amorphous phase. Direct creep measurements during the crystallization of FINEMET alloys were performed and the creep properties of the residual amorphous phase formed during the nanocrystallization were described. It was shown that due to relatively high temperatures the residual amorphous phase undergoes intensive structural relaxation resulting in the obvious embrittlement of these materials.
Electrophoretic Deposition as Preparation Method for Intermediate Temperature SOFC Half Cells
Authors: Szepanski Christian , Grosse-Brauckmann Jana , Argirusis Christos
Published: September 2009

In this study we present the preparation of SOFC half cells by electrophoretic deposition. The cathode is deposited from a methyl ethyl ketone (MEK) suspension on dense apatite type lanthanum silicate (ATLS) pellets using a constant voltage. ATLS are a new class of electrolytes, which provides good oxygen permeability even at temperatures below 800°C. As cathode materials we used La2Ni0.8Cu0.2O4+δ (LNC) and La0.8Sr0.2Ni0.6Fe0.4O3 (LSNF). A conductive layer on the ATLS material was used to provide the necessary conductivity for electrophoretic deposition (EPD) process. For the preparation of suitable suspensions the charging behaviour and particle size of the different powders were investigated by means of zeta-potential and laser scattering measurements. When the electrophoretic mobility of the suspended particles was not sufficient iodine was added. Deposition kinetics were determined prior to preparation of the half cells. EPD parameters as well as sintering conditions were optimized in order to gain well adhering porous cathode layers.
Electrophoretic Deposition of YSZ Electrolyte on Porous NiO-YSZ Substrate for Solid Oxide Fuel Cells
Authors: Talebi Tahereh , Raissi Babak , Maghsoudipour Amir
Published: September 2009

: In this study a thin dense YSZ film has been fabricated from stable non-aqueous suspensions by Electrophoretic Deposition (EPD) method on a porous pre-sintered NiO-YSZ substrate. Thin film of YSZ and NiO-YSZ composite were used as electrolyte and anode, respectively, in SOFCs that should have certain characteristics. Process parameters like porosity, pre-sintering temperature, voltage and time of deposition have been considered and optimized for obtaining a controlled thickness. After depositing a conductive layer, EPD has been performed on NiO-YSZ composites. These layers were sintered and a crack-free dense thin film of 8 mol % YSZ was obtained on porous NiO-YSZ anode. The interface and adhesion between the two layers was investigated by Scanning Electron Microscope and microstructural observations.
Alumina and Zirconia Based Layered Composites: Part 2 Fracture Response
Authors: Chlup Zdeněk , Hadraba Hynek
Published: September 2009

Laminated materials are used for special applications where combination of properties of two components is needed. Ceramics is inherently brittle and above all superior properties (wear resistance, temperature durability, stiffness, low density and others) the brittleness is limiting factor for massive implementation in wide range applications. The laminated structure can be capable to overcome this handicap. Electrophoretic deposition (EPD) is the technique able to prepare ceramic laminated structures having strong interface between layers [1]. It is possible to prepare dense and crack free materials with tailored residual stresses controlled by layer thickness and deposition conditions by this technique. Crack propagation through layered composites based on Al2O3 and ZrO2 was studied. Cracks, produced by an indentation technique, propagated in direction to layer interfaces deflected towards the interface in the compressed layers and away from the interface in the layers containing tension stress [2,3]. Changes in the direction of crack propagation for the whole range of angles of incidence (0° - 90°) were described. The biggest change in the crack propagation was observed for the angle of incidence 45° for A/Z systems and was ca. 15°. The change in the crack propagation was independent on the level of residual stresses in the layers. Behaviour of indentation cracks observed in laminates under investigation was compared with the results obtained on standard SEVNB specimens having inclined the fracture plane with respect to the composite lamellar structure. This model condition helps to understand crack propagation in bulk material. All experimental work was supported by fractographical techniques enabling explanation of fracture micromechanism.
Infiltration of a 3-D Fabric for the Production of SiC/SiC Composites by Means of Electrophoretic Deposition
Authors: Novak Saša , König Katja , Ivekovič Aljaž , Boccaccini Aldo Roberto
Published: September 2009

Electrophoretic deposition (EPD) was used to infiltrate 2D and 3D SiC fabrics with SiC submicron particles with the aim to verify the potential of the technique for the fabrication of dense SiC/SiC composites. Bulk SiC deposits were first prepared from aqueous suspensions with different dispersants using cathodic and anodic deposition. The most suitable composition of the suspensions and the conditions for the infiltration were determined on the basis of the analysis of green parts formed. Using a specially designed EPD cell a relatively high packing density of SiC particles in infiltrated 2D and 3D SiC-fiber fabrics was achieved.
Pulsed-DC Electrophoretic Deposition (EPD) of Aqueous Alumina Suspension for Controlling Bubble Incorporation and Deposit Microstructure
Authors: Besra Laxmidhar , Uchikoshi Tetsuo , Suzuki Tohru , Sakka Yoshio
Published: September 2009

Electrophoretic deposition (EPD) from aqueous suspension generally forms deposit containing incorporated bubbles because of evolution of gases at electrodes due to electrolysis of water. We have demonstrated here that application of pulsed voltage /current instead of continuous DC enables controlling the amount of bubble incorporation and obtain bubble-free deposits during EPD of aqueous suspension. The yield and bubble incorporation decreased progressively with decrease in size of the applied pulse. A characteristic band of deposition window was found in the plot of voltage/current vs. pulse width within which smooth and bubble-free deposits are obtained. The window is wider at low applied voltages/currents than at higher voltages/currents implying that it is more easier to control the pulsed EPD at lower applied voltages and/currents. No deposition occurred below the window whereas deposits with incorporated bubbles formed above the window. Suppression of bubbles with decreasing pulse size was attributed to decrease in the amount of hydrogen evolved per pulse and verified by monitoring the gain in weight of palladium (Pd) electrode used as cathode during electrolysis of water.
Deposition of Sonochemically Derived Nano Particles
Authors: Grosse-Brauckmann Jana , Matic Sladjana , Schneider Oliver , Argirusis Christos
Published: September 2009

In this work we investigated the possibility to use electrophoretic deposition from organic solvents in order to deposit catalytically active surface-stabilized nanoparticles on a substrate. This permits to functionalize a surface by depositing a catalytic layer or simply offers a way to collect the synthesized nanoparticles e.g. for subsequent characterization. As an example, Co nanoparticles were prepared using a sonochemical method, and subsequently deposited on a substrate by electrophoretic deposition. We used ionic liquids (IL) in order to increase the ζ-potential of the nano particles.
Study of the Deposit Resistance during Electrophoretic Deposition
Authors: Stappers Linda , Zhang Li , Van der Biest Omer , Fransaer Jan
Published: September 2009

Deposition experiments in a Hull cell showed that high conductivity suspensions yield uniform deposits while low conductivity suspensions result in non-uniform deposits. This difference in deposition behavior is related to the resistance increase of the deposit during EPD. Impedance measurements during EPD showed that the ratio of the deposit resistance to the suspension resistance increases much more for high than for the low conductivity suspensions. They also showed that the total resistance of the EPD cell dropped almost to the suspension resistance after the electric field was turned off. This means that the deposit has no inherent resistance, but that its resistance during polarization is caused by the interaction of ions with the deposit and by the depletion of ions at the deposition electrode. The change in ion concentrations near the deposition electrode changes the acid/base properties of the particles in the deposit, as proven by adsorbed pH indicators on the particles. The change in acid/base behavior is quasi irreversible and results in a memory effect of the deposit resistance when the voltage is reapplied.
Recent Patenting Activity in Electrolytic Aluminium Production Technology
Authors: Patterson Edwin C. , Cross Robert N.
Published: August 2009

Companies and research organizations in the aluminium industry have a number of different strategies for protecting their new developments. Many research organizations have a patent focused strategy to facilitate commercialization of their new technologies. Conversely, primary aluminium producers tend to use patent protection more selectively, as they are able to use other Intellectual Property protection means such as trade secrets to protect their developments. This paper provides an overview of international patent publications from 1995 to 2008 in the field of electrolytic aluminium production and comments on perceived factors driving IP protection of these developments.
Meltless Ti – A New Light Metals Industry
Authors: Woodfield Andy , Ott Eric , Blank Jon , Peretti Mike , Linger David , Duke Larry
Published: August 2009

Recent advances in synthesis of titanium (Ti) alloy powders by direct reduction methods (meltless Ti) have led to new opportunities to produce Ti alloys with enhanced capabilities. The meltless Ti alloy powders can be consolidated into mill products, or used to manufacture near-net shape (NNS) components. A vision is outlined for creation of a new supply chain producing meltless Ti alloy powders, leading to the production and application of innovative turbine engine components. This paper highlights the benefits of meltless Ti alloys, details current assessment of meltless Ti alloy technology, and outlines some of the challenges to fully establish the new supply chain.
Numerical and Experimental Investigation of the Heat-Affected Zone in a Laser-Assisted Machining of Ti-6Al-4V Alloy Process
Authors: Yang Ji Hong Nancy , Brandt Milan , Sun Shou Jin
Published: August 2009

The aim of this work is to develop a 3-D transient finite element model for a moving Gaussian laser heat source to predict the depth of the heat-affected zone (HAZ) and temperature distribution in a Ti6Al4V alloy workpiece. It is found that the temperature profile and depth of HAZ are strongly dependent on the parameters of the laser beam. The thermal model simulations are compared with results produced by experimental work and these show close agreement.
Chemistry Control in Electron Beam Deposited Titanium Alloys
Authors: Brice Craig A. , Rosenberger Brian T. , Sankaran Sankara N. , Taminger Karen M. , Woods Bryan , Nasserrafi Rahbar
Published: August 2009

Direct manufacturing of metallic materials has gained widespread interest in the past decade. Of the methods that are currently under evaluation, wire-fed electron beam deposition holds the most promise for producing large-scale titanium parts for aerospace applications [1]. This method provides the cleanest processing environment as the deposition is performed under vacuum. While this environment is beneficial in preventing contamination of the deposit, there is the potential for preferential vaporization of high vapor pressure elements during the deposition process. This can lead to detrimental chemistry variations, which can have negative impacts on physical and mechanical properties.
Past experience has shown that deposition of the alloy Ti-6Al-4V using electron beam direct manufacturing can produce material with aluminum content below the specification minimum [2]. As aluminum has a high vapor pressure with respect to titanium and vanadium, it preferentially vaporizes from the molten pool. This aluminum loss scales with the size of the molten pool and thus the chemical content can vary throughout the build. Compensating for this loss is necessary in order to achieve nominal chemistry in the deposited material. This paper examines established processing conditions for direct manufacturing of titanium, quantitatively determines deposited alloy chemistry changes under various conditions, and suggests a feedstock composition that will result in deposited material with nominal Ti-6Al-4V chemistry.
The Effect of Aluminum Equivalent and Molybdenum Equivalent on the Mechanical Properties of High Strength and High Toughness Titanium Alloys
Authors: Yang Yu Lan , Wang Wei Qi , Li Feng Li , Li Wei Qing , Zhang Yong Qiang
Published: August 2009

The effect of Aluminum equivalent and Molybdenum equivalent on the strength and fracture toughness of titanium alloys was studied in this paper. The result shows that the tensile strength of the alloy increases with increasing of aluminum equivalent and molybdenum equivalent and the fracture toughness decreases gradually, the effect of aluminum equivalent is comparatively more conspicuous. A suitable value range of aluminum equivalent and molybdenum equivalent of high strength and high toughness titanium alloys are obtained from the analysis, based on this, a new type of high strength and high toughness titanium alloy BTi-6554 (Ti-4Al-5Mo-5V-6Cr) was developed, which has good combination of strength and fracture toughness and has the characteristics of high strength and high toughness.
Life Cycle Environmental Impact of Magnesium Instrument Panel
Authors: Koltun Paul , Tharumarajah Ambavalavanar
Published: August 2009

Light weighting of cars has the definite advantage of reducing fuel consumption and tail pipe emissions. In this respect, substitution of heavier steel components with magnesium ones can save on weight of the replaced component due to its weight advantage resulting in lowering green house gases (GHG). There are additional benefits when magnesium is applied to complex structures and assemblies such as an Instrument Panel (IP). The possibility of casting single piece magnesium cross-car beams of IP can reduce the number of components to be assembled as wells as ease the disassembly and recovery at the end of life. This study, considering these advantages of using magnesium for IPs, examines and compares the environmental life cycle impact of magnesium and traditional steel and plastic IPs. However, the results indicate that magnesium IPs can have higher GHG impact than equivalent IPs made from others. The technological avenues for reducing the impact of magnesium IPs are examined in an extended study, including impact of primary metal (assumed from China), improvements in casting manufacture and use of secondary metal. These improvements show substantial reduction of GHG in the manufacture of magnesium IPs and improvement in comparative GHG performance with other materials.
The Effect of Heat Treatment System on Mechanical Properties of Titanium Alloy BTi-6554
Authors: Wang Xiao Xiang , Wang Wei Qi , Li Wei Qing , Li Feng Li , Yang Yu Lan
Published: August 2009

The effects of solution and aging treatment on the mechanical properties of BTi-6554 alloy titanium were investigated. The results showed: As to βsolution and aging treatment, the increase of fracture toughness is quite conspicuous as the solution temperature was raised, but the change of strength and plasticity is not obvious; As to (α+β) solution and aging treatment, the decline of fracture toughness and plasticity is quite conspicuous as the solution temperature increased, but the strength increased. The strength of (α+β) solution and aging treatment is higher than that of βsolution and aging treatment, but the fracture toughness is relatively lower. As the aging temperature increased, the strength of the alloy gradually decreased, but the plasticity and fracture toughness gradually improved and the improvement of fracture toughness is quite conspicuous. A better combination of strength-toughness-ductibility could be obtained under the heat treatment as solution at 900~930 oC and aging treatment at 560~590 oC.
Thermodynamic Aspects of Tin Segregation during Solidification of Aluminium Alloys
Authors: Schmid-Fetzer Rainer
Published: August 2009

When trying to calculate the approximate constitution of as-cast tin containing aluminium alloys one has to cope with a combination of intricacies: (i) Scheil solidification simulation may reflect strong enrichment of alloying components, especially in multicomponent alloys, thus leaving the safe ground of the underlying thermodynamic database. (ii) Liquid demixing often intensifies by addition of many components to Al-Sn alloys, thus forming monotectic reactions, boosting the segregation and aggravating the first effect. (iii) Scheil simulation in multicomponent Al-x-y-z-Sn alloys not only combines the first two problems, moreover, the current versions of major thermodynamic software packages are not able to perform the Scheil simulation if liquid demixing and monotectic reactions occur. These intricacies are worked out and the development of a dedicated Al-Si-Cu-Mg-Sn thermodynamic database for large composition ranges is presented. Calculations are compared to experimental data of an Al-7.5Si-3.5Cu-0.3Mg-0.1Sn alloy and the need for specific follow-up work is identified.
Simulation of Deform Behavior of WE43 Magnesium Alloy Based on DEFORM-3D
Authors: Wang Qiang , Gao Jia Cheng , Niu Wen Juan
Published: August 2009

Compared with the actual operation, computational simulation will save the cost and provide more valuable references or guiding significance for the real production. Using professional forming software DEFORM-3D, the upsetting process of WE43 magnesium alloy was simulated. Based on the actual flow stress data, the simulation model of WE43 magnesium alloy was created in DEFORM-3D. Results show that the uniform distribution of the temperature of WE43 magnesium alloy during the forming process is beneficial to the structural homogeneity and contributes to excellent flowing property. There is the stress concentration in the edge and slide face of the billet. So during the process of compression, the fracture will appear earlier in the edge and slide face of the sample.
Computer Modelling of Grain Boundaries for Optimizing the Properties of Polycrystalline Metallic Materials
Authors: Kurzydlowski Krzysztof Jan
Published: August 2009

Grain boundaries significantly influence the properties of polycrystalline metallic materials, particularly with grain sizes in the nano-metre range. The effect of grain boundaries on plasticity, fracture and corrosion resistance is well documented experimentally. The aim of this paper is to show that recent progress in modelling of the role of grain boundaries in metallic materials offers new possibilities for optimizing their properties.
Greenhouse Gas Emissions Attributable to High Pressure Die Casting
Authors: Tharumarajah Ambavalavanar , Gunasegaram Dayalan R. , Koltun Paul
Published: August 2009

In spite of die castings being amongst the highest volume items manufactured by the metalworking industry, the influence of high pressure die casting (HPDC) process parameters on greenhouse gas (GHG) emissions remains largely unreported. In this article, the authors discuss the effect of some HPDC process parameters on GHG emissions using cradle-to-gate life cycle assessment (LCA) for both aluminium and magnesium alloys. Although the impacts reduced with increasing yields in both cases, it was determined that the GHG impact of magnesium alloy HPDC was more sensitive to HPDC yield irrespective of the ratio of primary/secondary alloys in the melt charge. The reasons for this include a greater dependence of magnesium alloy HPDC on high-emitting primary processing and the use of the highly potent GHG SF6 for melting. For magnesium alloy HPDC, a decrease in quality assurance (QA) rejects and cycle times also reduced GHG emissions, although their influences were found to be an order lower than that of yield.
Mechanical Characterisation of Material Properties Using Instrumented Indentation Experiments
Authors: Moy Charles , Bocciarelli Massimiliano , Ringer Simon P. , Ranzi Gianluca
Published: August 2009

The proposed work makes use of an inverse analysis approach to identify the mechanical properties of a material sample which can be described by means of the elastic modulus, yield stress and strain-hardening parameter. The particularity of the proposed work is the exploitation of the indentation curve as well as the imprint left by the indenter at the end of the test as input information to the inverse analysis. The numerical simulations required by the analysis are carried out by means of the finite element software Abaqus. This paper describes initial work carried out to validate the robustness of the inverse procedure for stainless steel samples using computer-generated data.