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Missouri University of Science and Technology

Materials Science and Engineering Faculty Research & Creative Works

2002

Articles 1 - 12 of 12

Full-Text Articles in Engineering

Segmented Roll For Casting Metal Strip, James R. Sauer, Ronald J. O'Malley, Robert S. Williams Nov 2002

Segmented Roll For Casting Metal Strip, James R. Sauer, Ronald J. O'Malley, Robert S. Williams

Materials Science and Engineering Faculty Research & Creative Works

Casting molten metal using a segmented roll for casting continuous metal strip. A strip caster (10) for producing a continuous strip (18) includes a tundish for containing a melt and a pair of horizontally disposed water cooled composite casting rolls (84). The casting rolls are juxtaposed relative to one another for forming a pouring basin (16) for receiving molten metal. The composite rolls are formed from a plurality of annular segments (45). Each segment preferably includes at least a pair of coolant openings (34) and means for aligning the coolant openings, such as a pair of alignment openings (26). The …

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Magnetic Order In Yba₂Cu₃O₆₊ₓ Superconductors, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Jeffrey W. Lynn, Seunghun Lee, Fatih Dogan Oct 2002

Magnetic Order In Yba₂Cu₃O₆₊ₓ Superconductors, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Jeffrey W. Lynn, Seunghun Lee, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Polarized and unpolarized neutron diffraction has been used to search for magnetic order in YBa2Cu3O6+x superconductors. Most of the measurements were made on a high quality crystal of YBa2CU3O6.6. It is shown that this crystal has highly ordered ortho-II chain order, and a sharp superconducting transition. Inelastic scattering measurements display a very clean spin-gap and pseudogap with any intensity at 10 meV being 50 times smaller than the resonance intensity. The crystal shows a complicated magnetic order that appears to have three components. A magnetic phase is found at …

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Surface Switching Characteristics Of Variable Permittivity Dielectrics, Wayne Huebner, Eric J. Carleton Aug 2002

Surface Switching Characteristics Of Variable Permittivity Dielectrics, Wayne Huebner, Eric J. Carleton

Materials Science and Engineering Faculty Research & Creative Works

Flashover voltage, lifetimes, and switch performance of insulators utilizing square thin and thick film electrodes were examined to determine the viability of using thin electrodes for reliable surface discharge switching. Gold, silver, and platinum were sputtered (0.25 µm) and screen printed (15 µm) onto Al2O3, TiO2, and modified BaTiO3 (MBT), then tested in air at 105 Pa, under vacuum (10-3/ torr), and while immersed in an insulating fluid, SF-2 (manufactured by 3M). For the measured range of 0.5 to 3 mm in air, the flashover voltage for all three insulators …

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Observation Of Changes In The Atomic And Electronic Structure Of Single-Crystal Yba₂Cu₃O₆.₆ Accompanying Bromination, Lamine M. Dieng, Yasuhiro Inamura, Trevor A. Tyson, Mark C. Croft, Fatih Dogan, C. Y. Kim, Joseph C. Woicik, James M. Grow Jul 2002

Observation Of Changes In The Atomic And Electronic Structure Of Single-Crystal Yba₂Cu₃O₆.₆ Accompanying Bromination, Lamine M. Dieng, Yasuhiro Inamura, Trevor A. Tyson, Mark C. Croft, Fatih Dogan, C. Y. Kim, Joseph C. Woicik, James M. Grow

Materials Science and Engineering Faculty Research & Creative Works

To ascertain the role of bromination in the recovery of superconductivity in underdoped YBa2Cu3O6+y (YBCO), we have performed polarized multiple-edge x-ray-absorption fine structure (XAFS) measurements on normal (y~0.6) and brominated (Br/Cu~1/30, y~0.6) single crystals with superconducting transitions at 63 and 89 K, respectively. The brominated sample becomes strongly heterogeneous on an atomic length scale. Approximately one-third of YBCO is locally decomposed yet incorporated as a well-ordered "host" lattice as nanoscale regions. The decomposed phase consists of heavily distorted domains with an order not following that of the "host" lattice. Structurally, these domains are fragments of …

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Room-Temperature Homogeneous Nucleation Synthesis And Thermal Stability Of Nanometer Single Crystal Ceo₂, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson May 2002

Room-Temperature Homogeneous Nucleation Synthesis And Thermal Stability Of Nanometer Single Crystal Ceo₂, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

Nanometer (about 4~5nm) CeO2 single crystals were first synthesized by room-temperature homogeneous nucleation; the size was determined by electron microscopy and specific surfaced area of the particles. Modeling revealed that the surface energy of as-synthesized nanometer single crystals was in the range of 2.8-3.7J/m2. Crystal growth mechanisms change over the temperature regimes, from boundary diffusion over low-temperature regime (Eα=0.16eV) to bulk diffusion (Eα=0.50eV) over high-temperature region.

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Biodegradable Glass Compositions And Methods For Radiation Therapy, D. E. Day, James E. White Apr 2002

Biodegradable Glass Compositions And Methods For Radiation Therapy, D. E. Day, James E. White

Materials Science and Engineering Faculty Research & Creative Works

A nonradioactive glass in particulate form adapted for radiation therapy in a mammal comprise a biodegradable rare earth-lithium borate glass material of a specified composition which, upon being subjected to an effective amount of neutron irradiation, will produce a beta or gamma emitting radioisotope, the radioisotope being distributed throughout the glass material, the glass upon being introduced into a body fluid for radiation therapy being adapted to react therewith causing the radioisotope to form an insoluble compound on the surface of the glass material which is retained in the glass material and thereby prevented from escaping from the treatment site. …

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Method For Preparing Porous Shells Or Gels From Glass Particles, D. E. Day, Samuel D. Conzone Mar 2002

Method For Preparing Porous Shells Or Gels From Glass Particles, D. E. Day, Samuel D. Conzone

Materials Science and Engineering Faculty Research & Creative Works

A method is provided for preparing shells, concentric shells or porous, homogenous gels from alkali borate glass particles at low temperatures (i.e. room temperature or less than above 100° C.). The alkali borate glass particles contain one or more cations such as aluminum which react with an aqueous solution containing an anion such as hydroxide to form an aqueous insoluble material having a solubility limit of less than about 0.01 wt. percent. TTie resulting shells or gels may be used in many different applications such as a filler in resins, as filters, precursors for nano-sized powders, as thin surface films …

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Charge And Spin Structure In Yba₂Cu₃O₆.₃₅, Herbert A. Mook, Pengcheng Dai, Fatih Dogan Mar 2002

Charge And Spin Structure In Yba₂Cu₃O₆.₃₅, Herbert A. Mook, Pengcheng Dai, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Neutron scattering has been used to measure the charge and spin structure in the highly underdoped superconductor YBa2Cu3O6.35. Incommensurate static charge ordering is found that remains at high temperatures. The magnetic pattern is complex with a resonance and incommensurate structure observed at low temperatures. The results clarify the role of striped phases in YBa2Cu3O6 + x superconductors.

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Corrosion Resistant Nickel-Based Alloy, Joseph William Newkirk, Sanhong Zhang Jan 2002

Corrosion Resistant Nickel-Based Alloy, Joseph William Newkirk, Sanhong Zhang

Materials Science and Engineering Faculty Research & Creative Works

A nickel based, high silicon alloy exhibits very high corrosion resistance in high temperature sulfuric acid environments. The alloy may be cast and is sufficiently ductile to be fabricated and machined. The alloy is ductile and has sufficient resistance to mechanical and thermal shock to be reliable in service when used as rotating parts.

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Agglomerated Lubricant, Mary R. Reidmeyer Jan 2002

Agglomerated Lubricant, Mary R. Reidmeyer

Materials Science and Engineering Faculty Research & Creative Works

A lubricant for use in lubricating the shot sleeve of a machine for die casting molten metals is in the form of agglomerated particles. The particles have an inorganic high pressure lubricant agglomerated, with a binder material and with an organic material. The solid lubricant is resistant to dusting, caking and breakage, can be fed through an automatic dispensing machine, and combines inorganic and organic materials to achieve excellent lubrication properties. The product has low flash and low smoke release into the environment.

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Neodymium And Erbium Coordination Environments In Phosphate Glasses, Mevlüt Karabulut, G. K. Marasinghe, Ezzeldin Metwalli, Andrew K. Wittenauer, Richard K. Brow, C. H. Booth, D. K. Shuh Jan 2002

Neodymium And Erbium Coordination Environments In Phosphate Glasses, Mevlüt Karabulut, G. K. Marasinghe, Ezzeldin Metwalli, Andrew K. Wittenauer, Richard K. Brow, C. H. Booth, D. K. Shuh

Materials Science and Engineering Faculty Research & Creative Works

The local structures of Nd3+ and Er3+ ions in two series of rare-earth (RE) phosphate glasses with nominal compositions xR203-(1-x)P2O5, where R=Nd and Er and 0.05≤x≤0.28, have been characterized by LIII-edge extended x-ray-absorption fine-structure spectroscopy (EXAFS). The RE coordination number depends on the R2O3 content, decreasing from 9.0 (10) oxygen nearest neighbors in ultraphosphate compositions (x<0.15) to 6.4 (9) oxygen nearest neighbors for the metaphosphate (x∼0.25) compositions. The average Er-O bond distance decreases from 2.29 (1) to 2.23 (1) Å, and the average Nd-O bond distance decreases from 2.40 (1) to 2.37 (1) Å over the same compositional range. The changes in coordination environments are consistent with the conversion of isolated RE polyhedra to clustered RE polyhedra sharing common oxygens as the number of available terminal oxygens per RE ion decreases with increasing x.

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Reactive Hot Pressing Of Alumina-Molybdenum Disilicide Composites, William Fahrenholtz, Ronald E. Loehman, Kevin G. Ewsuk Jan 2002

Reactive Hot Pressing Of Alumina-Molybdenum Disilicide Composites, William Fahrenholtz, Ronald E. Loehman, Kevin G. Ewsuk

Materials Science and Engineering Faculty Research & Creative Works

Al2O3-MoSi2 Composites Were Prepared by Reactive Hot Pressing using Molybdenum, Aluminum, and Mullite Powders as Precursors. the Gibbs Free Energy Was Highly Negative for the Composite-Forming Reaction, Which Indicated that the Products Were Stable Relative to the Reactants. after the Reaction, the Composites Had High Relative Density, ∼96%. based on the Composite-Forming Reaction, the Composites Should Have Contained 18 Vol% MoSi2 in an Al2O3 Matrix. Scanning Electron Microscopy Revealed that the MoSi2 Inclusions Were Elongated, with an Average Thickness of ∼5 Μm and Inclusion Lengths that Ranged from 5 to 50 …

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