101 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Aluminium Oxides"  
Results: 1 - 24 next
open access

Dual and Triple Ion-Beam Irradiations of Fe, Fe(Cr) and Fe(Cr)-ODS Final Report: IAEA SMoRE CRP

Description: Structures of nanoparticles in Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y2O3 (K3) and Fe-20Cr-4.5Al-0.34Ti-0.5Y2O3 (MA956) oxide dispersion strengthened (ODS) ferritic steels produced by mechanical alloying (MA) and followed by hot extrusion have been studied using high-resolution transmission electron microscopy (HRTEM) techniques to gain insight about the formation mechanism of nanoparticles in MA/ODS steels. The observations of Y-Al-O complex-oxide nanoparticles in both ODS steels imply that decomposition… more
Date: November 20, 2011
Creator: Fluss, M. J.; Hsiung, L. L. & Marian, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

REFINEMENT OF THE NEPHELINE DISCRIMINATOR: RESULTS OF A PHASE II STUDY

Description: Twenty five glass compositions were selected for a Phase II study to assess the potential for reducing the conservatism in the nepheline discriminator. The glass compositions were restricted to regions that fell within the validation ranges of the DWPF PCCS models. In addition, the liquidus temperature model was used to restrict the glass compositions so that they could all be melted at the same temperature. The nepheline discriminator was used to force the glass compositions into regions where… more
Date: November 21, 2008
Creator: Fox, K & Tommy Edwards, T
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Solid State, Surface and Catalytic Studies of Oxides

Description: This project investigates the catalytic properties of oxides for the selective oxidative dehydrogenation of light alkanes and for hydrocarbon reduction of NO{sub x}. Various vanadium oxide based catalysts were investigated to elucidate the relationship between the chemical and structural properties of the catalysts and their selectivity for the formation of alkenes. It was found that vanadium oxide units that are less reducible give higher selectivities. For hydrocarbon reduction of NO{sub x}, … more
Date: November 23, 2004
Creator: Kung, H. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

IMPERMEABLE THIN Al2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

Description: In order to improve the hot corrosion resistance of conventional YSZ TBC system, the Al{sub 2}O{sub 3} overlay coating has been successfully produced on the surface of YSZ by the Sol-gel route. The YSZ substrates were coated with boehmite sol by dip coating process, dried to form a gel film and calcined at 1200 C to form {alpha}-Al{sub 2}O{sub 3} overlay. The microstructures of TBC and Al{sub 2}O{sub 3} overlay were examined by scanning electron microscopy (SEM). The results showed that micro-p… more
Date: November 30, 2002
Creator: Mao, Scott X.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The spectral emittance and stability of coatings and textured surfaces for thermophotovoltaic (TPV) radiator applications

Description: Coatings or surface modifications are needed to improve the surface emissivity of materials under consideration for TPV radiator applications to a value of 0.8 or higher. Vacuum plasma spray coatings (ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, Fe{sub 2}TiO{sub 5}, ZrTiO{sub 4}, ZrO{sub 2} + 8% Y{sub 2}O{sub 3} + 2% HfO{sub 2}, and Al{sub 2}O{sub 3} + TiO{sub 2}) and a chemical vapor deposited coating of rhenium whiskers were used to increase the surface emissivity of refractory me… more
Date: November 1, 2000
Creator: Cockeram, B.V. & Hollenbeck, J.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Modifier coordination and phosphate glass networks

Description: The addition of up to approximately 16 mole% Cs{sub 2}O to vitreous P{sub 2}O{sub 5} reduces the glass transition temperature (T{sub g}) by 150 K, whereas further additions up to 50 mole% produce little additional change in T{sub g}. {sup 31}P magic angle spinning nuclear magnetic resonance spectra indicate that the phosphate network is progressively dipolymerized over the entire range of compositions. The property trend is explained by a transition in the Cs{sup +} coordination environment, fr… more
Date: November 30, 1999
Creator: Brow, R.; Click, C. A. & Alam, T. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The Formation of High-Coercivity, Oriented, Nanophase Cobalt Precipitates in Al

Description: Ion-implantation and thermal-processing methods have been used to form nanophase magnetic precipitates of metallic cobalt that are embedded in the near-surface region of single crystals of Al{sub 2}O{sub 3}. The Co precipitates are isolated, single-crystal particles that are crystallographically oriented with respect to the host Al{sub 2}O{sub 3} lattice. Embedded nanophase Co precipitates were formed by the implantation of Co+ at an energy of 140 keV and a dose of 8 x l0{sup 16} ions/cm{sup 2}… more
Date: November 29, 1999
Creator: Honda, S.; Modine, F. A.; Haynes, T. E.; Meldrum, A.; Budai, J. D.; SOng, K. J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Growth and oxidation of thin film Al{sub 2}Cu

Description: Al{sub 2}Cu thin films ({approximately}382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a {approximately}3 nm Al{sub 2}O{sub 3} passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p{sub 3/2} peak and a 1.6 eV shift of the valence band relative to metallic Cu upon Al{sub 2}Cu formation. Scanning Electron Microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al{sub 2}Cu film is composed of 30--70 … more
Date: November 9, 1999
Creator: Son, K. A.; Missert, N. A.; Barbour, J. C.; Hren, J. J.; Copeland, R. G. & Minor, K. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Variations in the Nature of Metal Adsorption on Ultrathin Al(2)O(3) Films

Description: First-principles density-functional calculations are used to study metal adsorption (Li, K, Y, Nb, Ru, Pd, Pt, Cu, Ag, Au, and Al at 1/3-4 monolayer coverages) atop 5 ~ A1203 films on Al(Ill). The oxide-metal bond is ionic at Iow coverages but, with interesting exceptions, caused by polari@i ,~-cE!vED at high coverages where the overlayer is metallic. Binding trends are explained in terms of s'imp e concepts. Increasing overlayer thickness can cause the adsorbate-oxide interface structure to th… more
Date: November 24, 1998
Creator: Bogicevic, Alexander & Jennison, Dwight R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A dynamic inert metal anode.

Description: A new concept for a stable anode for aluminum electrowinning is described. The anode consists of a cup-shaped metal alloy container filled with a molten salt that contains dissolved aluminum. The metal alloy can be any of a number of alloys, but it must contain aluminum as a secondary alloying metal. A possible alloy composition is copper with 5 to 15 weight percent aluminum. In the presence of oxygen, aluminum on the metal anode's exterior surface forms a continuous alumina film that is thick … more
Date: November 9, 1998
Creator: Hryn, J. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Technical Status Report on the Effect of Phosphate and Aluminum on the Development of Amorphous Phase Separation in Sodium

Description: The objective of the Tank Focus Area ''Optimize Waste Loading'' task is to enhance the definition of the acceptable processing window for high-level waste vitrification plants. One possible manner in which the acceptable processing window may be enhanced is by reducing the uncertainty of various compositional/property models through a specifically defined experimental plan. A reduction in model uncertainty can reduce limitations on current acceptance constraints and may allow for a larger proce… more
Date: November 3, 1998
Creator: Cozzi, A.D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

In situ X-Ray Absorption Spectro-Electrochemical Study of Amorphous Tin-Based Composite Oxide Material

Description: We have measured the XAFS spectra of a sample of tin-based composite oxide (TCO) material with a nominal composition of Sn{sub 1.0}B{sub 0.56}P{sub 0.40}Al{sub 0.42}O{sub 3.47} during the discharge and charge cycles in an ''in situ'' configuration. Our results confirm the amorphous nature of TCO and show that Sn in TCO is coordinated with 3 oxygen atoms at a distance of 2.12 {angstrom}. Upon discharging, initially, Li interacts with the electrochemically active Sn-O center forming metallic Sn i… more
Date: November 1, 1998
Creator: Mansour, A. N.; Mukerjee, S.; Yang, X. Q. & McBreen, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Pit Initiation in AIO{sub X}/AI Thin Films

Description: The electrochemical responses of AlO{sub x}/Al thin films have been investigated as a function of film growth conditions which produce films with different grain orientation, size and morphology. Films with smooth, 150 nm diameter, randomly oriented grains show a higher pitting potential and lower passive current than those films with large grain-boundary grooving from a mixture of smooth micron-sized, (200)-oriented grains and 300--500 nm diameter, (220)-oriented grains. These results suggest … more
Date: November 1, 1998
Creator: Son, K. A.; Barbour, J. C.; Missert, N.; Wall, F. D.; Copeland, R. G.; Martinez, M. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Atomic resolution Z-contrast imaging of ultradispersed catalysts

Description: Using Z-contrast imaging in a 300 kV scanning transmission electron microscope, direct images of single metal atoms on a support material in industrial catalyst systems are formed. The simultaneously collected conventional bright-field images reveal orientational information about the support, which allows possible configurations of Pt atoms on a {gamma}-Al{sub 2}O{sub 3} support surface to be deduced. Image intensities also allow the three-dimensional configuration of a raft of Rh atoms on a {… more
Date: November 1, 1997
Creator: Nellist, P.D. & Pennycook, S.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Cl{sup {minus}} adsorption on an Al{sub 2}O{sub 3} surface in an electrolyte

Description: Adsorption of ions on mineral surfaces is important to a number of technologies, including soil-surface geochemical cycling, corrosion, waste isolation and environmental restoration. The initiation of pitting of aluminum in water vapor and chlorine environments has been associated with the adsorption of chloride ions on the surface of oxidized aluminum. The authors present a method for calculating the minimum energy configurations of atomic and molecular species adsorbing on defected solid surf… more
Date: November 1, 1997
Creator: Wilson, W. D. & Schaldach, C. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fabrication and evaluation of uniform and gradient density epoxies

Description: Filled epoxy materials which vary in density in a designed manner have been fabricated and their mechanical properties evaluated. Density variations were produced by incorporating different volume fractions of either glass microballoons (GMB) or alumina. Several different sample types were evaluated including uniform density (0.8 g/cm{sup 3} < {rho} < 2.0 g/cm{sup 3}) samples and gradient density samples (GMB only, 0.8 g/cm{sup 3} < {rho} < 1.2 g/cm{sup 3}). The uniform density specimens were e… more
Date: November 1, 1997
Creator: Domeier, L. A.; Skala, D. M. & Goods, S. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Neutron-scattering studies of nitride, oxide, and phosphate ceramics and their relationship with molecular-dynamics simulations of high-temperature properties

Description: Currently, the strength and reliability of nitride and carbide ceramics are not sufficient to meet the demands of high-tech applications such as heat engines. A large R and D effort is needed to advance the field of ceramic science and engineering. The strength of ceramics depends on both the nature of atomic bonding such as covalency versus ionicity and the microstructure such as flaws and stress within the materials. The length scale of these influential factors ranges from 0.1 to 5,000 nm, t… more
Date: November 1, 1997
Creator: Loong, C.K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Process development for electron beam joining of ceramic and glass components

Description: The purpose of this project is to develop and extend the electron beam joining process to applications related to Mo/Al{sub 2}O{sub 3} cermets for neutron tube fabrication, glass seals for flat panel displays, and ceramics for structural applications. The key issue is the identification of the allowable operating ranges that produce thermal conditions favorable to robust joining and sealing. High strength, hermetic braze joints between ceramic components have been produced using high energy ele… more
Date: November 1, 1997
Creator: Turman, B. N.; Glass, S. Jill; Yang, Pin; Gerstle, Frank P.; Halbleib, John A.; Voth, Thomas E. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Recent Developments in Freeform Fabrication of Dense Ceramics From Slurry Deposition

Description: A freeform fabrication technique for dense ceramics and composites has been developed. The technique requires less than 2 volume percent of organic additives and relies on the principle of layerwise deposition of highly loaded colloidal slurries. Components can be manufactured into complex geometries with thick solid sections as well as with thin-walled sections with high aspect ratios. Process feasibility and quality is dependent on the processing parameters of solids loading, slurry rheology,… more
Date: November 1, 1997
Creator: Cesarano, J., III; Baer, T. A. & Calvert, P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Energetic-particle synthesis of nanocomposite Al alloys

Description: Ion implantation of O into Al and growth of Al(O) layers using electro-cyclotron resonance plasma and pulsed laser depositions produce composite alloys with a high density of nanometer-size oxide precipitates in an Al matrix. The precipitates impart high strength to the alloy and reduced adhesion during sliding contact, while electrical conductivity and ductility are retained. Implantation of N into Al produces similar microstructures and mechanical properties. The athermal energies of deposite… more
Date: November 26, 1996
Creator: Follstaedt, D. M.; Knapp, J. A.; Barbour, J. C.; Myers, S. M. & Dugger, M. T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Advanced materials for aerospace and biomedical applications: New glasses for hermetic titanium seals

Description: Titanium and titanium alloys have an outstanding strength-to-weight ratio and corrosion resistance and so are materials of choice for a variety of aerospace and biomedical applications. Such applications are limited by the lack of a viable hermetic glass sealing technology. Conventional silicate sealing glasses are readily reduced by titanium to form interfacial silicides that are incompatible with a robust glass/metal seal. Borate-based glasses undergo a similar thermochemistry and are reduced… more
Date: November 1, 1996
Creator: Brow, R.K.; Tallant, D.R. & Crowder, S. V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Ceramic-Metal Composite Formation by Reactive Metal Penetration

Description: Ceramic-metal composites can be made to near-net-shape by reactive penetration of dense ceramic preforms by molten metals. Reactive metal penetration is driven by a strongly negative Gibbs energy for reaction. For Al, the general form of the reaction is (x+2) Al + (3/y) MO[sub y] yields Al[sub 2]O[sub 3] + M[sub 3/y]Al[sub x], where MO[sub y] is an oxide that is wet by molten Al. In low PO[sub 2] atmospheres and at temperatures above about 900 degrees C, molten Al reduces mullite to produce Al[… more
Date: November 1, 1996
Creator: Loehman, Ronald E.; Ewsuk, Kevin G.; Fahrenholtz, William G. & Lakshman, Bala B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The effect of silica-containing binders on the titanium/face coat reaction

Description: The interactions of CP-Ti and Ti-6Al-4V with investment molds containing alumina/silica and yttria/silica face coat systems were studied. Containerless melting in a vacuum was employed and small test samples were made by drop casting into the molds. The effects of the face coat material and mold preheat temperatures on the thickness of the alpha case on the castings were evaluated with microhardness and microprobe measurements. It was found that the thickness of the alpha case was the same, whe… more
Date: November 1996
Creator: Frueh, C.; Poirier, D. R. & Maguire, M. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Microstructural and mechanical characterization of alumina scales thermally developed on iron aluminide alloys

Description: To understand the underlying phenomena when characterizing material performance, we must know the chemistry and physics of the early stages of oxidation, chemistry, and bonding at the substrate/oxide interface, effect of segregants on the strength of bonding, transport processes through the scale formed during corrosion, mechanisms of residual stress generation and relief, and fracture behavior at the oxide/substrate interface. Specific objectives of the program described here are to (a) system… more
Date: November 1996
Creator: Natesan, K.; Renusch, D.; Veal, B. W. & Grimsditch, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen