70 Matching Results

Search Results

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

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

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

Solid-particle erosion of an Al{sub 2}O{sub 3}-SiC-TiC composite

Description: An electrodischarge-machinable Al{sub 2}O{sub 3}-SiC-TiC composite developed by Industrial Ceramic Technology, Inc., has a high fracture toughness, 9.6{+-}0.6 MPm{sup 1/2}, as measured by indentation, and a Vickers hardness of 20.3{+-}0.6 GPa. The composite`s resistance to solid-particle erosion was measured for 143-{mu}m dia SiC particles impacting at 20-90{degree} angles and 50-100 m/s velocities. Erosion rate exhibited a maximum for normal incidence, and the erosion resistance was better tha… more
Date: November 1, 1996
Creator: Jiang, M.; Goretta, K.C.; Singh, D.; Routbort, J.L. & Schuldies, J.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Advanced sulfur control concepts

Description: Regenerable metal oxide sorbents, such as zinc titanate, are being developed to efficiently remove hydrogen sulfide (H{sub 2}S) from coal gas in advanced power systems. Dilute air regeneration of the sorbents produces a tailgas containing a few percent sulfur dioxide (SO{sub 2}). Catalytic reduction of the SO{sub 2} to elemental sulfur with a coal gas slipstream using the Direct Sulfur Recovery Process (DSRP) is a leading first-generation technology. Currently the DSRP is undergoing field testi… more
Date: November 1, 1995
Creator: Gangwal, Santosh K.; Turk, Brian S. & Gupta, Raghubir P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Compaction of spray-dried ceramic powders: An experimental study of the factors that control green density

Description: The pressure-compaction response of a spray-dried, 94% alumina powder containing several percent of a polymeric binder was investigated as a function of die diameter and compact aspect ratio. The results show that the die fill density decreases markedly with decreasing die diameter and aspect ratio, while the final green density (at 120 MPa) decreases only slightly under the same conditions. These results suggest that the ratio of the initial compact dimensions to the size of the granules may b… more
Date: November 1, 1995
Creator: Readey, M. J. & Mahoney, F. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Defining the glass composition limits for the CaO-Al2O3-SiO2 ternary system

Description: Vitrification is being investigated as an alternative wasteform for Department of Energy low-level mixed wastes. Since these wastes often contain significant amounts of calcium, the CaO-Al{sub 2}O{sub 3}-SiO{sub 2} ternary system may be used when trying to determine suitable glass compositions. The objective of this research was to determine a leach-resistant glass forming region in the CaO-Al{sub 2}O{sub 3}-SiO{sub 2} system. Several glasses were fabricated and characterized for chemical compo… more
Date: November 1, 1995
Creator: Cicero, C.A.; Andrews, M.K. & Bickford, D.F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Filter component assessment

Description: The objectives of this program are to provide a more ruggedized filter system that utilizes porous ceramic filters which have improved resistance to damage resulting from crack propagation, thermal fatigue and/or thermal excursions during plant or process transient conditions, and/or mechanical ash bridging events within the candle filter array. As part of the current Phase 1, Task 1, effort of this program, Westinghouse is evaluating the filtration characteristics, mechanical integrity, and co… more
Date: November 1, 1995
Creator: Alvin, M. A.; Lippert, T. E.; Diaz, E. S. & Smeltzer, E. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Lightweight ceramic filter components: Evaluation and application

Description: Ceramic candle filtration is an attractive technology for particulate removal at high temperatures. The primary objective of this SBIR research program is to increase the performance, durability, and corrosion resistance of lightweight filter candles and filter tubesheet components (Fibrosic{trademark}), fabricated from vacuum formed chopped ceramic fiber (VFCCF), for use in advanced coal utilization applications. Phase 1 results proved that significant gains in material strength and particle r… more
Date: November 1, 1995
Creator: Eggerstedt, P.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Separation of hydrogen using thin film palladium-ceramic composite membrane

Description: The primary objective of this study was to prepare and characterize a hydrogen permselective palladium-ceramic composite membrane for high temperature gas separations and catalytic membrane reactors. Electroless plating method was used as a potential route to deposit a thin palladium film on microporous ceramic substrate. The objectives of the work presented here were to characterize the new Pd-ceramic composite membrane by SEM and EDX analysis and to carry out fundamental permeability measurem… more
Date: November 1, 1995
Creator: Ilias, S.; King, F.G.; Su, N. & Udo-Aka, U.I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Shock compression of quartz and aluminum powder mixtures

Description: The authors report about the shock-compression response of highly porous (55% and 65% dense) mixtures of 4Al + 3SiO{sub 2} powders having shock-induced phase transitions and chemical reactions. Shock recovery experiments were performed using the CETR/Sawaoka plate-impact system (P = 40 to 100 GPa) and the Sandia Momma Bear A Comp B fixture (P = 22 to 45 GPa). The recovered compacts contained the high pressure stishovite phase, products of chemical reaction, as well as unreacted constituents. Th… more
Date: November 1, 1995
Creator: Joshi, V. S.; Thadhani, N. N.; Graham, R. A. & Holman, G. T., Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Compound semiconductor nanocrystals formed by sequential ion implantation

Description: Ion implantation and thermal processing have been used to synthesize compound semiconductor nanocrystals (SiGe, GaAs, and CdSe) in both SiO{sub 2} and (0001) Al{sub 2}O{sub 3}. Equal doses of each constituent are implanted sequentially at energies chosen to give an overlap of the profiles. Subsequent annealing results in precipitation and the formation of compound nanocrystals. In SiO{sub 2} substrates, nanocrystals are nearly spherical and randomly oriented. In Al{sub 2}O{sub 3}, nanocrystals … more
Date: November 1, 1994
Creator: White, C. W.; Budai, J. D. & Zhu, J. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Hot coal gas desulfurization with manganese based sorbents. Quarterly report, June--September 1994

Description: The focus of work being performed on hot coal gas desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) appears to be a strong contender to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zi… more
Date: November 1, 1994
Creator: Hepworth, M.T. & Slimane, R.B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Large-area triple-junction a-Si alloy production scaleup. Annual subcontract report, 17 March 1993--18 March 1994

Description: The objective of this subcontract over its three-year duration is to advance Solarex`s photovoltaic manufacturing technologies, reduce its a-Si:H module production costs, increase module performance and expand the Solarex commercial production capacity. Solarex shall meet these objectives by improving the deposition and quality of the transparent front contact, by optimizing the laser patterning process, scaling-up the semiconductor deposition process, improving the back contact deposition, sca… more
Date: November 1, 1994
Creator: Oswald, R. & Morris, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Lightweight alumina refractory aggregate. Phase 2, Pilot scale development

Description: Kilogram quantities of refractory aggregate were prepared from both a paste and a pelletized form of extruder feed material in both bench and pilot-scale equipment. The 99{sup +} % alumina aggregate exhibited a bulk density approaching 2.5 g/cm{sup 3} and a fired strength slightly lower than fused alumina. Based on initial evaluation by two refractory manufacturers in brick or castable applications, the new aggregate offered adequate strength with thermal conductivity reductions up to 34%, depe… more
Date: November 1, 1994
Creator: Swansiger, T.G. & Pearson, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

LuAlO{sub 3}: A high density, high speed scintillator for gamma detection

Description: We present measurements of the scintillation properties cerium doped lutetium aluminum perovskite, LuAlO{sub 3}:C, new dense ({rho}=8.34 g/cm{sup 3}) inorganic scintillator. This material has a 511 keV interaction length and photoelectric fraction 1.1 cm and 32% respectively, which are well suited to gamma ray detection. In powdered form with 0.5% cerium concentration, the scintillation light output is estimated to be 9,600 photons/MeV of deposited energy, the emission spectrum is a single peak… more
Date: November 1, 1994
Creator: Moses, W. W.; Derenzo, S. E.; Fyodorov, A.; Korzhik, M.; Gektin, A.; Minkov, B. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen