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Articles 541 - 570 of 1347

Full-Text Articles in Materials Science and Engineering

Freeze Casting Of Bioactive Glass And Ceramic Scaffolds For Bone Tissue Engineering, Qiang Fu Jan 2009

Freeze Casting Of Bioactive Glass And Ceramic Scaffolds For Bone Tissue Engineering, Qiang Fu

Doctoral Dissertations

"The main objectives of this dissertation were to explore the production of bioactive ceramic and glass scaffolds with oriented pore architectures by unidirectional freezing of suspensions, and to characterize the mechanical and biological performance of the scaffolds. Freezing of aqueous suspensions of hydroxyapatite (HA) or bioactive 13-93 glass particles resulted in the formation of scaffolds with a lamellar-type microstructure (pore width = 5-30 µm). The addition of polar organic solvents (such as 60 wt% dioxane) to the aqueous suspensions markedly changed the morphology and size of the oriented pores, giving scaffolds with a columnar-type microstructure and larger pre width (90-110 …

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Yttria Stabilized Zirconia As A Candidate For High Energy Density Capacitor, Oratai Jongprateep, Vladimir Petrovsky, Fatih Dogan Dec 2008

Yttria Stabilized Zirconia As A Candidate For High Energy Density Capacitor, Oratai Jongprateep, Vladimir Petrovsky, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

As one of the main components in power converters, dielectric capacitors can play crucial roles in facilitating power conversion in various applications, such as hybrid-electric and fuel cell vehicles. Capacitor reliability is a key challenge for development of high-performance capacitors. In this study, yttrium stabilized zirconia (YSZ) with various yttria concentrations were fabricated and tested for dielectric properties, such as breakdown strength and dielectric loss factors. The results indicated that the breakdown strength as high as 2 MV/cm could be achieved in YSZ samples with 10 mol% yttria. In addition, the dielectric loss factors of the samples were lower than …

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N,N’-Bis(3,5-Di-T-Butylsalicylideneimine) Propanediamine And Its Some Tetradentate Schiff Base Complexes Synthesis, Characterization And Thermal Study, Fatih Dogan, M. Ulusoy, O. F. Ozturk, I. Kaya, B. Salih Nov 2008

N,N’-Bis(3,5-Di-T-Butylsalicylideneimine) Propanediamine And Its Some Tetradentate Schiff Base Complexes Synthesis, Characterization And Thermal Study, Fatih Dogan, M. Ulusoy, O. F. Ozturk, I. Kaya, B. Salih

Materials Science and Engineering Faculty Research & Creative Works

Several mononuclear Co (II), Ni (II), Cu (II) and Fe (II) complexes of tetradentate salpren-type diamine, obtained from 3,5-di-tert–butyl-2-hydroxybenzaldehyde and 1,3-diaminopropane have been prepared and characterized by analytical, spectroscopic (FTIR, UV-Vis) techniques, magnetic susceptibility measurements and thermogravimetric analyses (TG). The thermodynamic and thermal properties of complexes have been investigated. For further characterization direct insertion probe-mass spectrometry (DIP-MS) was used and the fragmentation pattern and also stability of the ions were evaluated. The characterization of the end products of the decomposition was achieved by X-ray diffraction. The thermal stabilities of metal complexes of N,N’-bis(3,5-di-t-butylsalicylideneimine) propane diamine ligand (L) were found as …

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Freeform Fabrication Of Zirconium Diboride Parts Using Selective Laser Sintering, Ming-Chuan Leu, Erik B. Adamek, Tieshu Huang, Greg Hilmas, Fatih Dogan Aug 2008

Freeform Fabrication Of Zirconium Diboride Parts Using Selective Laser Sintering, Ming-Chuan Leu, Erik B. Adamek, Tieshu Huang, Greg Hilmas, Fatih Dogan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using the Selective Laser Sintering (SLS) process, both flexural test bars and 3D fuel injector components have been fabricated with zirconium diboride (ZrB2) powder. Stearic acid was selected as the binder. Values of SLS process parameters were chosen such that the green parts could be built with sharp geometrical features and that the sintered parts could have good mechanical properties. After binder burnout and sintering, the SLS fabricated ZrB2 test bars achieved 80% theoretical density, and the average flexural strength of the sintered samples was 195 MPa. These values demonstrate the feasibility of the SLS process for …

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Nanoparticulate Composites Of Melt Textured Yba2cu3o7−X Superconductors, Oratai Jongprateep, Fatih Dogan Aug 2008

Nanoparticulate Composites Of Melt Textured Yba2cu3o7−X Superconductors, Oratai Jongprateep, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

It has been shown that Nd1+xBa2−xCu3O7−x could exhibit a pronounced Jc(H) peak effect, which results in an enhancement of the critical current density under the medium range magnetic field. Additions of small quantities of Nd2O3 into Pt-doped YBa2Cu3O7−x (Y123) resulted in the formation of nanosized (30–60 nm) secondary phases which are expected to have a significant effect on superconducting properties of melt textured Y123 single crystals. By considering of solidification kinetics, effect of neodymium oxide and platinum addition on processing parameters of melt textured Y123 superconductors are …

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The Effect Of Vibratory Milling On The Powder Properties Of Zinc Oxide Varistors, Maura Kelleher, M.S.J. Hashmi May 2008

The Effect Of Vibratory Milling On The Powder Properties Of Zinc Oxide Varistors, Maura Kelleher, M.S.J. Hashmi

Articles

The formation of powders from multi-elemental oxides for the subsequent formation of a green and sintered compact body is a major processing operation in the manufacture of ZnO varistors. The physical and chemical properties of the metal oxides are crucial not only for the formation of a varistor component with optimum microstructure and thus electrical characteristics but also for avoiding the introduction of flaws and reduced yield during subsequent manufacturing stages. The effect of vibratory milling using cylindrical zirconia media on the physical and chemical properties of the mixed multi-elemental oxide additives of a commercial ZnO varistor formulation was studied. …

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Analysis Of Multi-Layered Materials Under High Velocity Impact Using Cth, Jason K. Lee Mar 2008

Analysis Of Multi-Layered Materials Under High Velocity Impact Using Cth, Jason K. Lee

Theses and Dissertations

Multi-layer armor containing ceramic and metallic layers has become more common in the past two decades. Typically, ceramics have high compressive strength which combined with their low density make them highly desirable for armor applications. This research effort numerically simulates high velocity impact of cylindrical projectiles on multi-layer metallic and ceramic targets of finite thickness. The impact of the projectile occurs normal to the surface of the target. The projectiles used are made of either S7 tool steel or tungsten. The targets consist of either rolled homogeneous armor, 4340 steel and boron carbide ceramic or rolled homogeneous armor and boron …

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Effects Of Environment On Creep Behavior Of Nextel 720/Alumina-Mullite Ceramic Composite At 1200°C, Christopher L. Genelin Mar 2008

Effects Of Environment On Creep Behavior Of Nextel 720/Alumina-Mullite Ceramic Composite At 1200°C, Christopher L. Genelin

Theses and Dissertations

The creep behavior of an oxide-oxide ceramic matrix composite (CMC) was investigated at 1200°C in laboratory air, in steam and in argon. The composite consisted of a porous alumina-mullite matrix reinforced with laminated, woven mullite/alumina (Nextel/720) fibers. The composite had no fiber coating and relied on its porous alumina/mullite matrix for flaw tolerance. Tensile stress-strain behavior was investigated and the tensile properties were measured at 1200°C in laboratory air. Tensile creep behavior of the CMC was examined for creep stress levels of 73, 91, 114 and 136 MPa. Creep run-out, set to 100 h, was achieved for stress levels ≤ …

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Composition Dependence Of The In-Plane Cu-O Bond-Stretching Lo Phonon Mode In Yba2cu3o6+X, F. Stercel, T. Egami, Herbert A. Mook, M. Yethiraj, J.-H. Chung, M. Arai, C. Frost, Fatih Dogan Jan 2008

Composition Dependence Of The In-Plane Cu-O Bond-Stretching Lo Phonon Mode In Yba2cu3o6+X, F. Stercel, T. Egami, Herbert A. Mook, M. Yethiraj, J.-H. Chung, M. Arai, C. Frost, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

An inelastic pulsed neutron scattering study was performed on the dependence of the dispersion and spectral intensity of the in-plane Cu-O bond-stretching LO phonon mode on doped charge density. The measurements were made in the time-of-flight mode with the multiangle position sensitive spectrometer of the ISIS facility on single crystals of YBa2Cu3O6+x x=0.15, 0.35, 0.6, 0.7, and 0.95. The focus of the study is the in-plane Cu-O bond-stretching LO phonon mode, which is known for strong electron-phonon coupling and unusual dependence on composition and temperature. It is shown that the dispersions for the samples with x=0.35, 0.6, and 0.7 are …

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Densification, Microstructure, And Mechanical Properties Of Zirconium Diboride Based Ultra-High Temperature Ceramics, Sumin Zhu Jan 2008

Densification, Microstructure, And Mechanical Properties Of Zirconium Diboride Based Ultra-High Temperature Ceramics, Sumin Zhu

Doctoral Dissertations

"The first part of this dissertation was aimed at studying the densification of ZrB₂ ceramics by pressureless sintering techniques. Various processes have been applied to coat ZrB₂ powders with polymer precursors, which were used to produce C after charring. After sintering at 1900⁰C, relative density increased of ~70% for uncoated ZrB₂ to >99% for ZrB₂ coated with at least 1.0 wt% C. Thermodynamic analysis suggested that C reacted with and removed oxide impurities (ZrO₂ and B₂O₃) that were present on the ZrB₂ particle surfaces, which promoted densification by minimizing grain coarsening"--Abstract, page iv.

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Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski Jan 2008

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert fuels containing ZrO2 and MgO as the inert matrix. Ceramics with this inert matrix, Ce, U and eventually Pu will be synthesized and examined. While the Advanced Fuel Cycle Initiative focus is on inert fuels with Pu as the fissile component, this task will perform initial laboratory experiments with Ce and U. The initial work with Ce will be performed early in the project with results used as a basis for U studies. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf. …

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Thickness Effects On The Ac And Dc Electrical Behavior Of Rf-Sputtered Batio3 Nano-Capacitors With Pt And Ni Electrodes, James N. Reck, Matthew O'Keefe, Fatih Dogan Jan 2008

Thickness Effects On The Ac And Dc Electrical Behavior Of Rf-Sputtered Batio3 Nano-Capacitors With Pt And Ni Electrodes, James N. Reck, Matthew O'Keefe, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Nanoscale BaTiO3 capacitors were deposited on Si wafers at dielectric thicknesses of approximately 25, 50, 100, and 200 nm using RF-magnetron sputtering with either 25 nm thick Ni or Pt electrodes. Multiple DC and AC tests were conducted on these devices to determine the effects of BaTiO3 thickness on the measured dielectric behaviors. All films were observed to have non-linear responses for resistance, permittivity, and loss with respect to dielectric thickness. The permittivity was found to follow a standard dead layer model behavior with measured values ranging from approximately 350 to 1700 for Ni electrodes and approximately 100 …

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Composition Dependence Of The In-Plane Cu-O Bond-Stretching Lo Phonon Mode In Y⁢Ba2⁢Cu3⁢O6+X, Ferenc Stercel, Takeshi Egami, Herbert A. Mook, Mohana Yethiraj, J-H Chung, M. Arai, C. Frost, Fatih Dogan Jan 2008

Composition Dependence Of The In-Plane Cu-O Bond-Stretching Lo Phonon Mode In Y⁢Ba2⁢Cu3⁢O6+X, Ferenc Stercel, Takeshi Egami, Herbert A. Mook, Mohana Yethiraj, J-H Chung, M. Arai, C. Frost, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

An inelastic pulsed neutron scattering study was performed on the dependence of the dispersion and spectral intensity of the in-plane Cu-O bond-stretching LO phonon mode on doped charge density. The measurements were made in the time-of-flight mode with the multiangle position sensitive spectrometer of the ISIS facility on single crystals of Y⁢Ba2⁢Cu3⁢O6+x (x=0.15, 0.35, 0.6, 0.7, and 0.95). The focus of the study is the in-plane Cu-O bond-stretching LO phonon mode, which is known for strong electron-phonon coupling and unusual dependence on composition and temperature. It is shown that the dispersions for the samples with …

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Using Science, Engineering, And Education To Address Water Supply Challenges In The Highlands Of Guatemala, Andrew Curtis Elmore, William Fahrenholtz Dec 2007

Using Science, Engineering, And Education To Address Water Supply Challenges In The Highlands Of Guatemala, Andrew Curtis Elmore, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

The Guatemalan Highlands is a Popular Destination for Non-Government Organizations Interested in Performing Relief Projects. U.S.-Based Organizations Such as Rotary International, Engineers Without Borders, and Various Religious Organizations Travel to Guatemala to Conduct Humanitarian Activities Which May Be Effective for the Short Term, But It is Not Clear that the Efforts Have a Systematic Impact. Students and Faculty at the University of Missouri-Rolla Have Systematically Studied Water Supply Issues Including Undergraduate and Graduate Research Projects and Undergraduate Engineering Courses Such as International Capstone Design. Materials Engineers Have Been Involved in the Study of Ceramic-Based Water Treatment Devices. These Microfilters Have …

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Enhanced Shrinkage Of Lanthanum Strontium Manganite (La0.90sr0.10mno3+Δ) Resulting From Thermal And Oxygen Partial Pressure Cycling, Benjamin P. Mccarthy, Larry R. Pederson, Harlan U. Anderson, Xiao Dong Zhou, Prabhakar Singh, Gregory W. Coffey, Edwin C. Thomsen Oct 2007

Enhanced Shrinkage Of Lanthanum Strontium Manganite (La0.90sr0.10mno3+Δ) Resulting From Thermal And Oxygen Partial Pressure Cycling, Benjamin P. Mccarthy, Larry R. Pederson, Harlan U. Anderson, Xiao Dong Zhou, Prabhakar Singh, Gregory W. Coffey, Edwin C. Thomsen

Materials Science and Engineering Faculty Research & Creative Works

Exposure of (La0.90Sr0.10)0.98MnO3+δ (LSM-10) to repeated oxygen partial pressure cycles (air/10 ppm O2) resulted in enhanced densification rates, similar to behavior shown previously due to thermal cycling. Shrinkage rates in the temperature range 700°-1000°C were orders of magnitude higher than Makipirtti-Meng model estimations based on stepwise isothermal dilatometry results at a high temperature. a maximum in enhanced shrinkage due to oxygen partial pressure cycling occurred at 900°C. Shrinkage was the greatest when LSM-10 bars that were first equilibrated in air were exposed to gas flows of lower oxygen fugacity than in …

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Transportation Fuel Research And Development: Statistically Validated Codes And Standards, Fatih Dogan Aug 2007

Transportation Fuel Research And Development: Statistically Validated Codes And Standards, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The recent establishment of the National University Transportation Center at MST under the "Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users," expands the research and education activities to include alternative transportation fuels and other issues that are at the forefront of society and the national agenda. UMR in partnership with MTI will establish a rural hydrogen transportation test bed for developing, demonstrating, evaluating, and promoting hydrogen-based technologies in a real-world environment. The State of Missouri is ideally suited to develop and demonstrate the proper operation of hydrogen highways in a rural setting, which represents over 25 percent …

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Aqueous-Based Extrusion Fabrication Of Ceramics On Demand, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas, Michael W. Hayes Aug 2007

Aqueous-Based Extrusion Fabrication Of Ceramics On Demand, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas, Michael W. Hayes

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests were conducted to determine the optimal deposition parameters for starting and stopping of the extrudate on demand. The collected test data is used to create a process model that describes the relationship between ram velocity and material extrusion rate. …

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Effects Of Surface-Deposited Nanocrystalline Chromite Thin Films On The Performance Of A Ferritic Interconnect Alloy, I. Belogolovsky, X. D. Zhou, H. Kurokawa, P. Y. Hou, S. Visco, H. U. Anderson Aug 2007

Effects Of Surface-Deposited Nanocrystalline Chromite Thin Films On The Performance Of A Ferritic Interconnect Alloy, I. Belogolovsky, X. D. Zhou, H. Kurokawa, P. Y. Hou, S. Visco, H. U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

LaCrO3 -Based nanocrystalline thin films, substituted with Sr and Zn and coated onto a Fe-26 atom % Cr Ebrite alloy were evaluated at 750-900°C as potential enhancers of oxide properties in ferritic alloy interconnects of a solid oxide fuel cell. It was found that at 750°C the coatings provided (i) lower oxidation rates, (ii) increased electrical conductivity, (iii) protection during 24 h cycling and at least 2375 h of isothermal oxidation, and (iv) a fine-grained and uniform oxide microstructure. Although after oxidation at 850°C the grains grew substantially and the scale seemed to be overgrowing the film, conductivity and …

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Development Of Single Chamber Solid Oxide Fuel Cells With Porous Samaria Doped Ceria Electrolytes, Nathaniel Goss Jan 2007

Development Of Single Chamber Solid Oxide Fuel Cells With Porous Samaria Doped Ceria Electrolytes, Nathaniel Goss

Opportunities for Undergraduate Research Experience Program (OURE)

Single chamber solid oxide fuel cells generate electricity using hydrogen and hydrocarbon fuel mixed with oxygen at intermediate temperatures (400-800°C) without using seals to separate the gases. A single-chamber solid oxide fuel cell was fabricated with a porous samaria doped ceria (SOC) electrolyte, nickel oxide anode, and a lanthanum strontium cobalt iron oxide (LSCF) cathode. Instead of separately sintering the different components at different temperatures, the electrolyte and electrodes were co-sintered at 1100°C. The porous SOC electrolyte approached 84% theoretical density when sintered at 1100° C. The fuel cell had a maximum open circuit voltage of .65 V at 550°C. …

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A Simple Sol-Gel Processing For The Development Of High-Temperature Stable Photoactive Anatase Titania, Suresh Pillai, Declan Mccormack, John Colreavy Jan 2007

A Simple Sol-Gel Processing For The Development Of High-Temperature Stable Photoactive Anatase Titania, Suresh Pillai, Declan Mccormack, John Colreavy

Articles

No abstract provided.

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Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski Jan 2007

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert fuels containing ZrO2 and MgO as the inert matrix. Ceramics with this inert matrix, Ce, U and eventually Pu will be synthesized and examined. While the Advanced Fuel Cycle Initiative focus is on inert fuels with Pu as the fissile component, this task will perform initial laboratory experiments with Ce and U. The initial work with Ce will be performed early in the project with results used as a basis for U studies. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf. …

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Properties Of Alkaline-Resistant Calcium-Iron-Phosphate Glasses, Jiawanjun Shi Jan 2007

Properties Of Alkaline-Resistant Calcium-Iron-Phosphate Glasses, Jiawanjun Shi

Masters Theses

"The physical properties and alkaline corrosion resistant properties of calcium-iron-phosphate glasses were studied. The addition of Fe₂O₃ decreases the thermal expansion coefficient and increases the glass fiber's Young's modulus in comparison with the addition of CaO. Bulk glass dissolution behavior in alkaline Lawrence solution was studied by weight loss experiments, Raman spectroscopy, and analytical scanning electron microscopy. The corrosion of glass powder in NaOH solution was studied by X-ray diffraction, infrared spectroscopy and high pressure liquid chromatography. The results show that the dissolution rate decreases when the phosphate chain length decreases. Calcium oxide can improve the glass durability in high …

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Growth Of Mc3t3-El Pre-Osteoblasts On Borate Containing Glasses & Growth Of Osteoblastic Cells On 13-93 Glass Scaffolds, Agatha Dwilewicz Jan 2007

Growth Of Mc3t3-El Pre-Osteoblasts On Borate Containing Glasses & Growth Of Osteoblastic Cells On 13-93 Glass Scaffolds, Agatha Dwilewicz

Opportunities for Undergraduate Research Experience Program (OURE)

Three borate-based glasses, compositions designated 1B, 2B, and 3B, with B203 levels of 15, 31, and 46 mole percent (Table 1), respectively, were tested for their effects on the growth of MC3T3-El mouse pre-osteoblastic cells under physiological fluid conditions. Silicate type 45S5 glass was used as a control for comparison. Independently, the biocompatibility of recently developed silicate-based porous 13-93 bioactive glass scaffolds was tested; Saos-2 human osteosarcoma cell line was used. Tests performed for the two studies included: contact assays of cell growth at the glass interface, chemical analysis of borate released into the culture medium, quantitative …

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Enhancement Of Crystal Growth And Superconducting Properties Of Melt-Textured Yba2cu3o7−X Through Addition Of Baceo3 And Basno3, Oratai Jongprateep, Fatih Dogan Sep 2006

Enhancement Of Crystal Growth And Superconducting Properties Of Melt-Textured Yba2cu3o7−X Through Addition Of Baceo3 And Basno3, Oratai Jongprateep, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The effects of additions of BaSnO3 in combination with BaCeO3 on the microstructure, crystal growth and superconducting properties of melt-textured YBa2Cu3O7−x (Y123) have been investigated. It has been reported that the addition of BaCeO3 to Y123 results in an increase in the critical current density. However, higher cerium concentrations affect the solidification process and inhibit the growth of melt-textured Y123 single crystals. BaSnO3 has been shown to restore the properties of Y123 with BaCeO3 additives. Increasing the amount of added BaSnO3 leads to refinement of Y211 particles, enhancement of …

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Effects Of Environment On Creep Behavior Of Two Oxide-Oxide Ceramic Matrix Composites At 1200°C, Pavlos Koutsoukos Sep 2006

Effects Of Environment On Creep Behavior Of Two Oxide-Oxide Ceramic Matrix Composites At 1200°C, Pavlos Koutsoukos

Theses and Dissertations

Previous studies by the advisor and graduate students examined creep behavior of the Nextel720/Alumina CMC in air and in 100% steam environments at 1200 and 1330°C. Results showed that while this oxide/oxide system exhibits an exceptionally high fatigue limit at 1200°C it also experiences substantial strain accumulation under sustained loading conditions. Furthermore, these earlier investigations revealed a significant degrading effect of 100% steam environment on material performance under both static and cyclic loadings. The present effort will investigate creep rupture behavior of Nextel720/Alumina composite in the inert gas environment. In addition, creep rupture behavior of Nextel720/Aluminosilicate CMC will be investigated …

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Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas Aug 2006

Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-based components in an environmentally friendly fashion. The method is based on the extrusion of ceramic slurries using water as the binding media. Aluminum oxide (Al2O3) is currently being used as the part material and solids loading as high as 60 vol. % has been achieved. This paper describes a novel manufacturing machine that has been developed for the extrusion of high solids loading ceramic slurries. A critical component of the machine is the deposition system, which consists of a syringe, a plunger, …

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Freeze-Spray Processing Of Layered Ceramic Composites, Qiang Fu, Oratai Jongprateep, Ashlee Abbott, Fatih Dogan Aug 2006

Freeze-Spray Processing Of Layered Ceramic Composites, Qiang Fu, Oratai Jongprateep, Ashlee Abbott, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Thermal gradients and associated stresses are critical in designing with ceramic composites having low thermal conductivity. In order to reduce the stresses from thermal gradients, compositional gradients are employed in designing of composite structures. This study addresses development of freeze-spray process to fabricate layered ceramic structures with controlled layer thickness and microstructural development. The composites were processed by spraying of ceramic slurries with low binder content and relatively high solids loadings (up to 40 vol%) on a cooled substrate. The frozen parts were freeze-dried and sintered at elevated temperatures. The relationship between microstructural development and thermal expansion behavior of Al …

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Effects Of Frequency And Environment On Fatigue Behavior Of An Oxide-Oxide Ceramic Matrix Composite At 1200°C, Griffin Hetrick Jun 2006

Effects Of Frequency And Environment On Fatigue Behavior Of An Oxide-Oxide Ceramic Matrix Composite At 1200°C, Griffin Hetrick

Theses and Dissertations

Advances in aeronautical engineering in the 21st century depend upon materials that can perform well in extreme environments such as high temperatures and oxidizing conditions. Nextel™720/Alumina (N720/A) is an oxide/oxide ceramic matrix composite with a porous alumina matrix that has been identified as a candidate material for such applications. This research investigated the effects of frequency on fatigue response of N720/A at 1200°C in both air and steam environment. Prior investigation of this material by Eber [8] in 2005 studied fatigue behavior at 1200°C in air and in steam environments at the frequency of 1.0 Hz. The current research focused …

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Effect Of Environment On Creep Behavior Of An Oxide/Oxide Cfcc With ±45° Fiber Orientation, Gregory T. Siegert Jun 2006

Effect Of Environment On Creep Behavior Of An Oxide/Oxide Cfcc With ±45° Fiber Orientation, Gregory T. Siegert

Theses and Dissertations

Aerospace applications require materials capable of maintaining superior mechanical properties while operating at high temperatures and oxidizing environments. Nextel™ 720/A (N720/A), an oxide/oxide ceramic matrix composite (CMC) with a porous alumina matrix was developed specifically to provide improved long-term properties and performance at 1200°C. This research evaluated the creep behavior of N720/A with a ±45° fiber orientation at 1200°C in: laboratory air, steam, and argon environments. Creep-rupture tests at the creep stress levels of: 45, 40, 35, and 15 MPa were conducted in each environment.
The ultimate tensile strength of N720/A with ±45° fiber orientation was 55 MPa, the elastic …

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2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla Apr 2006

2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla

Undergraduate Research Conference at Missouri S&T

No abstract provided.

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