The Effect of Heat Treatment on Residual Stress and Machining Distortions in Advanced Nickel Base Disk Alloys

NASA Technical Reports Server (NTRS)

Gayda, John

2001-01-01

This paper describes an extension of NASA's AST and IDPAT Programs which sought to predict the effect of stabilization heat treatments on residual stress and subsequent machining distortions in the advanced disk alloy, ME-209. Simple "pancake" forgings of ME-209 were produced and given four heat treats: 2075F(SUBSOLVUS)/OIL QUENCH/NO AGE; 2075F/OIL QUENCH/1400F@8HR;2075F/OIL QUENCH/1550F@3HR/l400F@8HR; and 2160F(SUPERSOLVUS)/OIL QUENCH/1550F@3HR/ 1400F@8HR. The forgings were then measured to obtain surface profiles in the heat treated condition. A simple machining plan consisting of face cuts from the top surface followed by measurements of the surface profile opposite the cut were made. This data provided warpage maps which were compared with analytical results. The analysis followed the IDPAT methodology and utilized a 2-D axisymmetric, viscoplastic FEA code. The analytical results accurately tracked the experimental data for each of the four heat treatments. The 1550F stabilization heat treatment was found to significantly reduce residual stresses and subsequent machining distortions for fine grain (subsolvus) ME209, while coarse grain (supersolvus) ME209 would require additional time or higher stabilization temperatures to attain the same degree of stress relief.

Welding and brazing of nickel and nickel-base alloys

NASA Technical Reports Server (NTRS)

Mortland, J. E.; Evans, R. M.; Monroe, R. E.

1972-01-01

The joining of four types of nickel-base materials is described: (1) high-nickel, nonheat-treatable alloys, (2) solid-solution-hardening nickel-base alloys, (3) precipitation-hardening nickel-base alloys, and (4) dispersion-hardening nickel-base alloys. The high-nickel and solid-solution-hardening alloys are widely used in chemical containers and piping. These materials have excellent resistance to corrosion and oxidation, and retain useful strength at elevated temperatures. The precipitation-hardening alloys have good properties at elevated temperature. They are important in many aerospace applications. Dispersion-hardening nickel also is used for elevated-temperature service.

Advanced nickel-hydrogen spacecraft battery development

NASA Technical Reports Server (NTRS)

Coates, Dwaine K.; Fox, Chris L.; Standlee, D. J.; Grindstaff, B. K.

1994-01-01

Eagle-Picher currently has several advanced nickel-hydrogen (NiH2) cell component and battery designs under development including common pressure vessel (CPV), single pressure vessel (SPV), and dependent pressure vessel (DPV) designs. A CPV NiH2 battery, utilizing low-cost 64 mm (2.5 in.) cell diameter technology, has been designed and built for multiple smallsat programs, including the TUBSAT B spacecraft which is currently scheduled (24 Nov. 93) for launch aboard a Russian Proton rocket. An advanced 90 mm (3.5 in.) NiH2 cell design is currently being manufactured for the Space Station Freedom program. Prototype 254 mm (10 in.) diameter SPV batteries are currently under construction and initial boilerplate testing has shown excellent results. NiH2 cycle life testing is being continued at Eagle-Picher and IPV cells have currently completed more than 89,000 accelerated LEO cycles at 15% DOD, 49,000 real-time LEO cycles at 30 percent DOD, 37,800 cycles under a real-time LEO profile, 30 eclipse seasons in accelerated GEO, and 6 eclipse seasons in real-time GEO testing at 75 percent DOD maximum. Nickel-metal hydride battery development is continuing for both aerospace and electric vehicle applications. Eagle-Picher has also developed an extensive range of battery evaluation, test, and analysis (BETA) measurement and control equipment and software, based on Hewlett-Packard computerized data acquisition/control hardware.

Nickel base alloy. [for gas turbine engine stator vanes

NASA Technical Reports Server (NTRS)

Freche, J. C.; Waters, W. J. (Inventor)

1977-01-01

A nickel base superalloy for use at temperatures of 2000 F (1095 C) to 2200 F (1205 C) was developed for use as stator vane material in advanced gas turbine engines. The alloy has a nominal composition in weight percent of 16 tungsten, 7 aluminum, 1 molybdenum, 2 columbium, 0.3 zirconium, 0.2 carbon and the balance nickel.

Characterization of the Temperature Capabilities of Advanced Disk Alloy ME3

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; OConnor, Kenneth

2002-01-01

The successful development of an advanced powder metallurgy disk alloy, ME3, was initiated in the NASA High Speed Research/Enabling Propulsion Materials (HSR/EPM) Compressor/Turbine Disk program in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. This alloy was designed using statistical screening and optimization of composition and processing variables to have extended durability at 1200 F in large disks. Disks of this alloy were produced at the conclusion of the program using a realistic scaled-up disk shape and processing to enable demonstration of these properties. The objective of the Ultra-Efficient Engine Technologies disk program was to assess the mechanical properties of these ME3 disks as functions of temperature in order to estimate the maximum temperature capabilities of this advanced alloy. These disks were sectioned, machined into specimens, and extensively tested. Additional sub-scale disks and blanks were processed and selectively tested to explore the effects of several processing variations on mechanical properties. Results indicate the baseline ME3 alloy and process can produce 1300 to 1350 F temperature capabilities, dependent on detailed disk and engine design property requirements.

Successful Surface Treatments for Reducing Instabilities in Advanced Nickel-base Superalloys for Turbine Blades

NASA Technical Reports Server (NTRS)

Locci, Ivan E.; MacKay, Rebecca A.; Garg, Anita; Ritzert, Frank J.

2004-01-01

An optimized carburization treatment has been developed to mitigate instabilities that form in the microstructures of advanced turbine airfoil materials. Current turbine airfoils consist of a single crystal superalloy base that provides the mechanical performance of the airfoil, a thermal barrier coating (TBC) that reduces the temperature of the base superalloy, and a bondcoat between the superalloy and the TBC, that improves the oxidation and corrosion resistance of the base superalloy and the spallation resistance of the TBC. Advanced nickel-base superalloys containing high levels of refractory metals have been observed to develop an instability called secondary reaction zone (SRZ), which can form beneath diffusion aluminide bondcoats. This instability between the superalloy and the bondcoat has the potential of reducing the mechanical properties of thin-wall turbine airfoils. Controlled gas carburization treatments combined with a prior stress relief heat treatment and adequate surface preparation have been utilized effectively to minimize the formation of SRZ. These additional processing steps are employed before the aluminide bondcoat is deposited and are believed to change the local chemistry and local stresses of the surface of the superalloy. This paper presents the detailed processing steps used to reduce SRZ between platinum aluminide bondcoats and advanced single crystal superalloys.

Dual-Alloy Disks are Formed by Powder Metallurgy

NASA Technical Reports Server (NTRS)

Harf, F. H.; Miner, R. V.; Kortovich, C. S.; Marder, J. M.

1982-01-01

High-performance disks have widely varying properties from hub to rim. Dual property disk is fabricated using two nickel-base alloys, AF-115 for rim and Rene 95 for hub. Dual-alloy fabrication may find applications in automobiles, earth-moving equipment, and energy conversion systems as well as aircraft powerplants. There is potential for such applications as shafts, gears, and blades.

Validation test of 125 Ah advanced design IPV nickel-hydrogen flight cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1993-01-01

An update of validation test results confirming the advanced design nickel-hydrogen cell is presented. An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term, Low-Earth-Orbit (LEO) spacecraft missions. The new features of this design, which are not incorporated in state-of-the-art design cells, are: (1) use of 26 percent rather than 31 percent potassium hydroxide (KOH) electrolyte; (2) use of a patented catalyzed wall wick; (3) use of serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management; and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion due to charge/discharge cycling. The significant improvements resulting from these innovations are extended cycle life; enhanced thermal, electrolyte, and oxygen management; and accommodation of nickel electrode expansion. Six 125 Ah flight cells based on this design were fabricated by Eagle-Picher. Three of the cells contain all of the advanced features (test cells) and three are the same as the test cells except they do not have catalyst on the wall wick (control cells). All six cells are in the process of being evaluated in a LEO cycle life test at the Naval Weapons Support Center, Crane, IN, under a NASA Lewis Research Center contract. The catalyzed wall wick cells have been cycled for over 19000 cycles with no cell failures in the continuing test. Two of the noncatalyzed wall wick cells failed (cycles 9588 and 13,900).

The Effect of Tungsten and Niobium on the Stress Relaxation Rates of Disk Alloy CH98

NASA Technical Reports Server (NTRS)

Gayda, John

2003-01-01

Gas turbine engines for future subsonic transports will probably have higher pressure ratios which will require nickel-base superalloy disks with 1300 to 1400 F temperature capability. Several advanced disk alloys are being developed to fill this need. One of these, CH98, is a promising candidate for gas turbine engines and is being studied in NASA s Advanced Subsonic Technology (AST) program. For large disks, residual stresses generated during quenching from solution heat treatment are often reduced by a stabilization heat treatment, in which the disk is heated to 1500 to 1600 F for several hours followed by a static air cool. The reduction in residual stress levels lessens distortion during machining of disks. However, previous work on CH98 has indicated that stabilization treatments decrease creep capability. Additions of the refractory elements tungsten and niobium improve tensile and creep properties after stabilization, while maintaining good crack growth resistance at elevated temperatures. As the additions of refractory elements increase creep capability, they might also effect stress relaxation rates and therefore the reduction in residual stress levels obtained for a given stabilization treatment. To answer this question, the stress relaxation rates of CH98 with and without tungsten and niobium additions are compared in this paper for temperatures and times generally employed in stabilization treatments on modern disk alloys.

Formation of Minor Phases in a Nickel-Based Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, T. P.; Garg, A.; Miller, D. R.; Sudbrack, C. K.; Hull, D. R.; Johnson, D.; Rogers, R. B.; Gayda, J.; Semiatin, S. L.

2012-01-01

The minor phases of powder metallurgy disk superalloy LSHR were studied. Samples were consistently heat treated at three different temperatures for long times to approximate equilibrium. Additional heat treatments were also performed for shorter times, to then assess non-equilibrium conditions. Minor phases including MC carbides, M23C6 carbides, M3B2 borides, and sigma were identified. Their transformation temperatures, lattice parameters, compositions, average sizes and total area fractions were determined, and compared to estimates of an existing phase prediction software package. Parameters measured at equilibrium sometimes agreed reasonably well with software model estimates, with potential for further improvements. Results for shorter times representing non-equilibrium indicated significant potential for further extension of the software to such conditions, which are more commonly observed during heat treatments and service at high temperatures for disk applications.

Creep deformation mechanism mapping in nickel base disk superalloys

DOE PAGES

Smith, Timothy M.; Unocic, Raymond R.; Deutchman, Hallee; ...

2016-05-10

We investigated the creep deformation mechanisms at intermediate temperature in ME3, a modern Ni-based disk superalloy, using diffraction contrast imaging. Both conventional transmission electron microscopy (TEM) and scanning TEM were utilised. Distinctly different deformation mechanisms become operative during creep at temperatures between 677-815 °C and at stresses ranging from 274 to 724 MPa. Both polycrystalline and single-crystal creep tests were conducted. The single-crystal tests provide new insight into grain orientation effects on creep response and deformation mechanisms. Creep at lower temperatures (≤760 °C) resulted in the thermally activated shearing modes such as microtwinning, stacking fault ribbons and isolated superlattice extrinsicmore » stacking faults. In contrast, these faulting modes occurred much less frequently during creep at 815 °C under lower applied stresses. Instead, the principal deformation mode was dislocation climb bypass. In addition to the difference in creep behaviour and creep deformation mechanisms as a function of stress and temperature, it was also observed that microstructural evolution occurs during creep at 760 °C and above, where the secondary coarsened and the tertiary precipitates dissolved. Based on this work, a creep deformation mechanism map is proposed, emphasising the influence of stress and temperature on the underlying creep mechanisms.« less

Advanced designs for IPV nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Smithrick, J. J.; Manzo, M. A.; Gonzalez-Sanabria, O. D.

1984-01-01

Advanced designs for individual pressure vessel nickel-hydrogen cells have been concieved which should improve the cycle life at deep depths-of-discharge. Features of the designs which are new and not incorporated in either of the contemporary cells (Air Force/Hughes, Comsat) are: (1) use of alternate methods of oxygen recombination, (2) use of serrated edge separators to facilitate movement of gas within the cell while still maintaining required physical contact with the wall wick, and (3) use of an expandable stack to accommodate some of the nickel electrode expansion. The designs also consider electrolyte volume requirements over the life of the cells, and are fully compatible with the Air Force/Hughes design.

Validation test of advanced technology for IPV nickel-hydrogen flight cells: Update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1992-01-01

Individual pressure vessel (IPV) nickel-hydrogen technology was advanced at NASA Lewis and under Lewis contracts with the intention of improving cycle life and performance. One advancement was to use 26 percent potassium hydroxide (KOH) electrolyte to improve cycle life. Another advancement was to modify the state-of-the-art cell design to eliminate identified failure modes. The modified design is referred to as the advanced design. A breakthrough in the low-earth-orbit (LEO) cycle life of IPV nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3,500 cycles for cells containing 31 percent KOH. The boiler plate test results are in the process of being validated using flight hardware and real time LEO testing at the Naval Weapons Support Center (NWSC), Crane, Indiana under a NASA Lewis Contract. An advanced 125 Ah IPV nickel-hydrogen cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term, LEO spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent KOH electrolyte; (2) use of a patented catalyzed wall wick; (3) use of serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management; and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion due to charge/discharge cycling. The significant improvements resulting from these innovations are: extended cycle life; enhanced thermal, electrolyte, and oxygen management; and accommodation of nickel electrode expansion. The advanced cell design is in the process of being validated using real time LEO cycle life testing of NWSC, Crane, Indiana. An update of validation test results confirming this technology is presented.

Thermal and Mechanical Property Characterization of the Advanced Disk Alloy LSHR

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, John; Telesman, Jack; Kantzos, Peter T.

2005-01-01

A low solvus, high refractory (LSHR) powder metallurgy disk alloy was recently designed using experimental screening and statistical modeling of composition and processing variables on sub-scale disks to have versatile processing-property capabilities for advanced disk applications. The objective of the present study was to produce a scaled-up disk and apply varied heat treat processes to enable full-scale demonstration of LSHR properties. Scaled-up disks were produced, heat treated, sectioned, and then machined into specimens for mechanical testing. Results indicate the LSHR alloy can be processed to produce fine and coarse grain microstructures with differing combinations of strength and time-dependent mechanical properties, for application at temperatures exceeding 1300 F.

Strengthening Precipitate Morphologies Fully Quantified in Advanced Disk Superalloys

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.

1998-01-01

Advanced aviation gas turbine engines will require disk superalloys that can operate at higher temperatures and stresses than current conditions. Such applications will be limited by the tensile, creep, and fatigue mechanical properties of these alloys. These mechanical properties vary with the size, shape, and quantity of the gamma precipitates that strengthen disk superalloys. It is therefore important to quantify these precipitate parameters and relate them to mechanical properties to improve disk superalloys. Favorable precipitate morphologies and practical processing approaches to achieve them can then be determined. A methodology has been developed at the NASA Lewis Research Center to allow the comprehensive quantification of the size, shape, and quantity of all types of gamma precipitates.

Advanced nickel base alloys for high strength, corrosion applications

DOEpatents

Flinn, John E.

1998-01-01

Improved nickel-base alloys of enhanced strength and corrosion resistance, produced by atomization of an alloy melt under an inert gas atmosphere and of composition 0-20Fe, 10-30Cr, 2-12Mo, 6 max. Nb, 0.05-3 V, 0.08 max. Mn, 0.5 max. Si, less than 0.01 each of Al and Ti, less than 0.05 each of P and S, 0.01-0.08C, less than 0.2N, 0.1 max. 0, bal. Ni.

Validation test of advanced technology for IPV nickel-hydrogen flight cells - Update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1992-01-01

Individual pressure vessel (IPV) nickel-hydrogen technology was advanced at NASA Lewis and under Lewis contracts with the intention of improving cycle life and performance. One advancement was to use 26 percent potassium hydroxide (KOH) electrolyte to improve cycle life. Another advancement was to modify the state-of-the-art cell design to eliminate identified failure modes. The modified design is referred to as the advanced design. A breakthrough in the LEO cycle life of IPV nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3,500 cycles for cells containing 31 percent KOH. The boiler plate test results are in the process of being validated using flight hardware and real time LEO testing. The primary function of the advanced cell is to store and deliver energy for long-term, LEO spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent KOH electrolyte; (2) use of a patented catalyzed wall wick; (3) use of serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management; and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion due to charge/discharge cycling. The significant improvements resulting from these innovations are: extended cycle life; enhanced thermal, electrolyte, and oxygen management; and accommodation of nickel electrode expansion.

Advanced nickel base alloys for high strength, corrosion applications

DOEpatents

Flinn, J.E.

1998-11-03

Improved nickel-base alloys of enhanced strength and corrosion resistance, produced by atomization of an alloy melt under an inert gas atmosphere and of composition 0--20Fe, 10--30Cr, 2--12Mo, 6 max. Nb, 0.05--3 V, 0.08 max. Mn, 0.5 max. Si, less than 0.01 each of Al and Ti, less than 0.05 each of P and S, 0.01--0.08C, less than 0.2N, 0.1 max. 0, bal. Ni. 3 figs.

Advances in lightweight nickel electrode technology

NASA Technical Reports Server (NTRS)

Coates, Dwaine; Paul, Gary; Daugherty, Paul

1989-01-01

Studies are currently underway to further the development of lightweight nickel electrode technology. Work is focused primarily on the space nickel-hydrogen system and nickel-iron system but is also applicable to the nickel-cadmium and nickel-zinc systems. The goal is to reduce electrode weight while maintaining or improving performance, thereby increasing electrode energy density. Two basic electrode structures are being investigated. The first is the traditional nickel sponge produced from sintered nickel-carbonyl powder. The second is a new material for this application which consists of a non-woven mat of nickel fiber. Electrodes are being manufactured, tested, and evaluated at the electrode and cell level.

Advances in lightweight nickel electrode technology

NASA Technical Reports Server (NTRS)

Coates, Dwaine; Paul, Gary; Wheeler, James R.; Daugherty, Paul

1989-01-01

Studies are currently underway to further the development of lightweight nickel electrode technology. Work is focused primarily on the space nickel-hydrogen system and nickel-iron system but is also applicable to the nickel-cadmium and nickel-zinc systems. The goal is to reduce electrode weight while maintaining or improving performance thereby increasing electrode energy density. Two basic electrode structures are being investigated. The first is the traditional nickel sponge produced from sintered nickel-carbonyl powder and the second is a new material for this application which consists of a non-woven mat of nickel fiber. Electrodes are being manufactured, tested and evaluated at the electrode and cell level.

Fatigue Failure Modes of the Grain Size Transition Zone in a Dual Microstructure Disk

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Kantzos, Pete T.; Palsa, Bonnie; Telesman, Jack; Gayda, John; Sudbrack, Chantal K.

2012-01-01

Mechanical property requirements vary with location in nickel-based superalloy disks. In order to maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored grain microstructures. In this study, fatigue failure modes of a grain size transition zone in a dual microstructure disk were evaluated. A specialized heat treatment method was applied to produce varying grain microstructure in the bore to rim portions of a powder metallurgy processed nickel-based superalloy disk. The transition in grain size was concentrated in a zone of the disk web, between the bore and rim. Specimens were extracted parallel and transversely across this transition zone, and multiple fatigue tests were performed at 427 C and 704 C. Grain size distributions were characterized in the specimens, and related to operative failure initiation modes. Mean fatigue life decreased with increasing maximum grain size, going out through the transition zone. The scatter in limited tests of replicates was comparable for failures of uniform gage specimens in all transition zone locations examined.

A nickel base alloy, NASA WAZ-16, with potential for gas turbine stator vane application

NASA Technical Reports Server (NTRS)

Waters, W. J.; Freche, J. C.

1974-01-01

A nickel-base superalloy based on the nickel-aluminum-tungsten system designated WAZ-16 was developed for high strength in the 1095 C (2000 F) to 1205 C (2200 F) range. Its tensile strength at the latter temperature is approximately 186 MN/m2 (27,000 psi). The combination of properties of the alloy suggest that it has potential as a stator vane material in advanced gas turbine engines.

High Temperature, Slow Strain Rate Forging of Advanced Disk Alloy ME3

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; OConnor, Kenneth

2001-01-01

The advanced disk alloy ME3 was designed in the HSR/EPM disk program to have extended durability at 1150 to 1250 F in large disks. This was achieved by designing a disk alloy and process producing balanced monotonic, cyclic, and time-dependent mechanical properties. combined with robust processing and manufacturing characteristics. The resulting baseline alloy, processing, and supersolvus heat treatment produces a uniform, relatively fine mean grain size of about ASTM 7, with as-large-as (ALA) grain size of about ASTM 3. There is a long term need for disks with higher rim temperature capabilities than 1250 F. This would allow higher compressor exit (T3) temperatures and allow the full utilization of advanced combustor and airfoil concepts under development. Several approaches are being studied that modify the processing and chemistry of ME3, to possibly improve high temperature properties. Promising approaches would be applied to subscale material, for screening the resulting mechanical properties at these high temperatures. n obvious path traditionally employed to improve the high temperature and time-dependent capabilities of disk alloys is to coarsen the grain size. A coarser grain size than ASTM 7 could potentially be achieved by varying the forging conditions and supersolvus heat treatment. The objective of this study was to perform forging and heat treatment experiments ("thermomechanical processing experiments") on small compression test specimens of the baseline ME3 composition, to identify a viable forging process allowing significantly coarser grain size targeted at ASTM 3-5, than that of the baseline, ASTM 7.

Plated nickel wire mesh makes superior catalyst bed

NASA Technical Reports Server (NTRS)

Sill, M.

1965-01-01

Porous nickel mesh screen catalyst bed produces gas evolution in hydrogen peroxide thrust chambers used for attitude control of space vehicles. The nickel wire mesh disks in the catalyst bed are plated in rugose form with a silver-gold coating.

NICKEL-BASE ALLOY

DOEpatents

Inouye, H.; Manly, W.D.; Roche, T.K.

1960-01-19

A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

Low Cost Heat Treatment Process for Production of Dual Microstructure Superalloy Disks

NASA Technical Reports Server (NTRS)

Gayda, John; Gabb, Tim; Kantzos, Pete; Furrer, David

2003-01-01

There are numerous incidents where operating conditions imposed on a component mandate different and distinct mechanical property requirements from location to location within the component. Examples include a crankshaft in an internal combustion engine, gears for an automotive transmission, and disks for a gas turbine engine. Gas turbine disks are often made from nickel-base superalloys, because these disks need to withstand the temperature and stresses involved in the gas turbine cycle. In the bore of the disk where the operating temperature is somewhat lower, the limiting material properties are often tensile and fatigue strength. In the rim of the disk, where the operating temperatures are higher than those of the bore, because of the proximity to the combustion gases, resistance to creep and crack growth are often the limiting properties.

Initial performance of advanced designs for IPV nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.

1986-01-01

Advanced designs for individual pressure vessel nickel-hydrogen cells have been conceived which should improve the cycle life at deep depths-of-discharge and improve thermal management. Features of the designs which are new and not incorporated in either of the contemporary cells (Air Force/Hughes, Comsat) are: (1) use of alternate methods of oxygen recombination, (2) use of serrated edge separators to facilitate movement of gas within the cell while still maintaining required physical contact with the wall wick, and (3) use of an expandable stack to accommodate some of the nickel electrode expansion. The designs also consider electrolyte volume requirements over the life of the cells, and are fully compatible with the Air Force/Hughes design.

Initial performance of advanced designs for IPV nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Smithrick, J. J.

1985-01-01

Advanced designs for individual pressure vessel nickel hydrogen cells were conceived which should improve the life cycle at deep depths of discharge and improve thermal management. Features of the designs which are new and not incorporated in either of the contemporary cells (Air Force/Hughes, Comsat) are: (1) the use of alternate methods of oxygen recombination, (2) use of serrated edge separators to facilitate movement of gas within the cell while still maintaining required physical contact with the wall wick, and (3) use of an expandable stack to accommodate some of the nickel electrode expansion. The designs also consider electrolyte volume requirements over the life of the cells, and are fully compatible with the Air Force/Hughes design.

Disk Alloy Development

NASA Technical Reports Server (NTRS)

Gabb, Tim; Gayda, John; Telesman, Jack

2001-01-01

The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA HSR/EPM disk program to have extended durability at 1150 to 1250 "Fin large disks. Scaled-up disks of this alloy were produced at the conclusion of this program to demonstrate these properties in realistic disk shapes. The objective of the UEET disk program was to assess the mechanical properties of these ME3 disks as functions of temperature, in order to estimate the maximum temperature capabilities of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor / Turbine Disk program were sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. Additional sub-scale disks and blanks were processed and tested to explore the effects of several processing variations on mechanical properties. Scaled-up disks of an advanced regional disk alloy, Alloy 10, were used to evaluate dual microstructure heat treatments. This allowed demonstration of an improved balance of properties in disks with higher strength and fatigue resistance in the bores and higher creep and dwell fatigue crack growth resistance in the rims. Results indicate the baseline ME3 alloy and process has 1300 to 1350 O F temperature capabilities, dependent on detailed disk and engine design property requirements. Chemistry and process enhancements show promise for further increasing temperature capabilities.

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen battery cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1990-01-01

An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed. The primary function of the advanced cell, is to store and deliver energy for long term, low earth-orbit (LEO) spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent potassium hydroxide (KOH) electrolyte, (2) use of a patented catalyzed wall wick, (3) use of serrated edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management, and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion. Six 125 Ah flight cells based on this design were fabricated by Eagle-Picher. Three of the cells contain all of the advanced features (test cells) and three are the same as the test cells except they don't have catalyst on the wall wick (control cells). All six cells are in the process of being evaluated in a LEO cycle life test. The cells have accumulated about 4700 LEO cycles (60 percent DOD 10 C). There have been no cell failures, the catalyzed wall wick cells however, are performing better.

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen battery cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1990-01-01

An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term, low earth-orbit (LEO) spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent potassium hydroxide (KOH) electrolyte, (2) use of a patented catalyzed wall wick, (3) use of serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management, and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion. Six 125-Ah flight cells based on this design were fabricated by Eagle-Picher. Three of the cells contain all of the advanced features (test cells) and three are the same as the test cells except they don't have catalyst on the wall wick (control cells). All six cells are in the process of being evaluated in a LEO cycle life test. The cells have accumulated about 4700 LEO cycles (60 percent DOD 10 C). There have been no cell failures; the catalyzed wall wick cells, however, are performing better.

Nickel-Based Superalloy Resists Embrittlement by Hydrogen

NASA Technical Reports Server (NTRS)

Lee, Jonathan; Chen, PoShou

2008-01-01

A nickel-based superalloy that resists embrittlement by hydrogen more strongly than does nickel alloy 718 has been developed. Nickel alloy 718 is the most widely used superalloy. It has excellent strength and resistance to corrosion as well as acceptably high ductility, and is recognized as the best alloy for many high-temperature applications. However, nickel alloy 718 is susceptible to embrittlement by hydrogen and to delayed failure and reduced tensile properties in gaseous hydrogen. The greater resistance of the present nickel-based superalloy to adverse effects of hydrogen makes this alloy a superior alternative to nickel alloy 718 for applications that involve production, transfer, and storage of hydrogen, thereby potentially contributing to the commercial viability of hydrogen as a clean-burning fuel. The table shows the composition of the present improved nickel-based superalloy in comparison with that of nickel alloy 718. This composition was chosen to obtain high resistance to embrittlement by hydrogen while maintaining high strength and exceptional resistance to oxidation and corrosion. The most novel property of this alloy is that it resists embrittlement by hydrogen while retaining tensile strength greater than 175 kpsi (greater than 1.2 GPa). This alloy exhibits a tensile elongation of more than 20 percent in hydrogen at a pressure of 5 kpsi (approximately equal to 34 MPa) without loss of ductility. This amount of elongation corresponds to 50 percent more ductility than that exhibited by nickel alloy 718 under the same test conditions.

Separating the Influence of Environment from Stress Relaxation Effects on Dwell Fatigue Crack Growth in a Nickel-Base Disk Alloy

NASA Technical Reports Server (NTRS)

Telesman, J.; Gabb, T. P.; Ghosn, L. J.

2016-01-01

Both environmental embrittlement and crack tip visco-plastic stress relaxation play a significant role in determining the dwell fatigue crack growth (DFCG) resistance of nickel-based disk superalloys. In the current study performed on the Low Solvus High Refractory (LSHR) disk alloy, the influence of these two mechanisms were separated so that the effects of each could be quantified and modeled. Seven different microstructural variations of LSHR were produced by controlling the cooling rate and the subsequent aging and thermal exposure heat treatments. Through cyclic fatigue crack growth testing performed both in air and vacuum, it was established that four out of the seven LSHR heat treatments evaluated, possessed similar intrinsic environmental resistance to cyclic crack growth. For these four heat treatments, it was further shown that the large differences in dwell crack growth behavior which still persisted, were related to their measured stress relaxation behavior. The apparent differences in their dwell crack growth resistance were attributed to the inability of the standard linear elastic fracture mechanics (LEFM) stress intensity parameter to account for visco-plastic behavior. Crack tip stress relaxation controls the magnitude of the remaining local tensile stresses which are directly related to the measured dwell crack growth rates. It was hypothesized that the environmentally weakened grain boundary crack tip regions fail during the dwells when their strength is exceeded by the remaining local crack tip tensile stresses. It was shown that the classical creep crack growth mechanisms such as grain boundary sliding did not contribute to crack growth, but the local visco-plastic behavior still plays a very significant role by determining the crack tip tensile stress field which controls the dwell crack growth behavior. To account for the influence of the visco-plastic behavior on the crack tip stress field, an empirical modification to the LEFM stress

Potassium Sodium Niobate-Based Lead-Free Piezoelectric Multilayer Ceramics Co-Fired with Nickel Electrodes.

PubMed

Kawada, Shinichiro; Hayashi, Hiroyuki; Ishii, Hideki; Kimura, Masahiko; Ando, Akira; Omiya, Suetake; Kubodera, Noriyuki

2015-11-03

Although lead-free piezoelectric ceramics have been extensively studied, many problems must still be overcome before they are suitable for practical use. One of the main problems is fabricating a multilayer structure, and one solution attracting growing interest is the use of lead-free multilayer piezoelectric ceramics. The paper reviews work that has been done by the authors on lead-free alkali niobate-based multilayer piezoelectric ceramics co-fired with nickel inner electrodes. Nickel inner electrodes have many advantages, such as high electromigration resistance, high interfacial strength with ceramics, and greater cost effectiveness than silver palladium inner electrodes. However, widely used lead zirconate titanate-based ceramics cannot be co-fired with nickel inner electrodes, and silver palladium inner electrodes are usually used for lead zirconate titanate-based piezoelectric ceramics. A possible alternative is lead-free ceramics co-fired with nickel inner electrodes. We have thus been developing lead-free alkali niobate-based multilayer ceramics co-fired with nickel inner electrodes. The normalized electric-field-induced thickness strain ( S max / E max ) of a representative alkali niobate-based multilayer ceramic structure with nickel inner electrodes was 360 pm/V, where S max denotes the maximum strain and E max denotes the maximum electric field. This value is about half that for the lead zirconate titanate-based ceramics that are widely used. However, a comparable value can be obtained by stacking more ceramic layers with smaller thicknesses. In the paper, the compositional design and process used to co-fire lead-free ceramics with nickel inner electrodes are introduced, and their piezoelectric properties and reliabilities are shown. Recent advances are introduced, and future development is discussed.

Potassium Sodium Niobate-Based Lead-Free Piezoelectric Multilayer Ceramics Co-Fired with Nickel Electrodes

PubMed Central

Kawada, Shinichiro; Hayashi, Hiroyuki; Ishii, Hideki; Kimura, Masahiko; Ando, Akira; Omiya, Suetake; Kubodera, Noriyuki

2015-01-01

Although lead-free piezoelectric ceramics have been extensively studied, many problems must still be overcome before they are suitable for practical use. One of the main problems is fabricating a multilayer structure, and one solution attracting growing interest is the use of lead-free multilayer piezoelectric ceramics. The paper reviews work that has been done by the authors on lead-free alkali niobate-based multilayer piezoelectric ceramics co-fired with nickel inner electrodes. Nickel inner electrodes have many advantages, such as high electromigration resistance, high interfacial strength with ceramics, and greater cost effectiveness than silver palladium inner electrodes. However, widely used lead zirconate titanate-based ceramics cannot be co-fired with nickel inner electrodes, and silver palladium inner electrodes are usually used for lead zirconate titanate-based piezoelectric ceramics. A possible alternative is lead-free ceramics co-fired with nickel inner electrodes. We have thus been developing lead-free alkali niobate-based multilayer ceramics co-fired with nickel inner electrodes. The normalized electric-field-induced thickness strain (Smax/Emax) of a representative alkali niobate-based multilayer ceramic structure with nickel inner electrodes was 360 pm/V, where Smax denotes the maximum strain and Emax denotes the maximum electric field. This value is about half that for the lead zirconate titanate-based ceramics that are widely used. However, a comparable value can be obtained by stacking more ceramic layers with smaller thicknesses. In the paper, the compositional design and process used to co-fire lead-free ceramics with nickel inner electrodes are introduced, and their piezoelectric properties and reliabilities are shown. Recent advances are introduced, and future development is discussed. PMID:28793646

Heat Treatment Devices and Method of Operation Thereof to Produce Dual Microstructure Superalloys Disks

NASA Technical Reports Server (NTRS)

Gayda, John (Inventor); Gabb, Timothy P. (Inventor); Kantzos, Peter T. (Inventor)

2003-01-01

A heat treatment assembly and heat treatment methods are disclosed for producing different microstructures in the bore and rim portions of nickel-based superalloy disks, particu- larly suited for gas turbine applications. The heat treatment assembly is capable of being removed from the furnace and disassembled to allow rapid fan or oil quenching of the disk. For solutioning heat treatments of the disk, temperatures higher than that of this solvus temperature of the disk are used to produce coarse grains in the rim of each disk so as to give maximum creep and dwell crack resistance at the rim service temperature. At the same time, solution temperature lower than the solvus temperature of the disk are provided to produce fine grain in the bore of the disk so as to give maximum strength and low cycle fatigue resistance.

Fabrication of Turbine Disk Materials by Additive Manufacturing

NASA Technical Reports Server (NTRS)

Sudbrack, Chantal; Bean, Quincy A.; Cooper, Ken; Carter, Robert; Semiatin, S. Lee; Gabb, Tim

2014-01-01

Precipitation-strengthened, nickel-based superalloys are widely used in the aerospace and energy industries due to their excellent environmental resistance and outstanding mechanical properties under extreme conditions. Powder-bed additive manufacturing (AM) technologies offer the potential to revolutionize the processing of superalloy turbine components by eliminating the need for extensive inventory or expensive legacy tooling. Like selective laser melting (SLM), electron beam melting (EBM) constructs three-dimensional dense components layer-by-layer by melting and solidification of atomized, pre-alloyed powder feedstock within 50-200 micron layers. While SLM has been more widely used for AM of nickel alloys like 718, EBM offers several distinct advantages, such as less retained residual stress, lower risk of contamination, and faster build rates with multiple-electron-beam configurations. These advantages are particularly attractive for turbine disks, for which excessive residual stress and contamination can shorten disk life during high-temperature operation. In this presentation, we will discuss the feasibility of fabricating disk superalloy components using EBM AM. Originally developed using powder metallurgy forging processing, disk superalloys contain a higher refractory content and precipitate volume fraction than alloy 718, thus making them more prone to thermal cracking during AM. This and other challenges to produce homogeneous builds with desired properties will be presented. In particular, the quality of lab-scale samples fabricated via a design of experiments, in which the beam current, build temperature, and beam velocity were varied, will be summarized. The relationship between processing parameters, microstructure, grain orientation, and mechanical response will be discussed.

Flight Weight Design Nickel-Hydrogen Cells Using Lightweight Nickel Fiber Electrodes

NASA Technical Reports Server (NTRS)

Britton, Doris L.; Willis, Bob; Pickett, David F.

2003-01-01

The goal of this program is to develop a lightweight nickel electrode for advanced aerospace nickel-hydrogen cells and batteries with improved specific energy and specific volume. The lightweight nickel electrode will improve the specific energy of a nickel-hydrogen cell by >50%. These near-term advanced batteries will reduce power system mass and volume, while decreasing the cost, thus increasing mission capabilities and enabling small spacecraft missions. This development also offers a cost savings over the traditional sinter development methods for fabrication. The technology has been transferred to Eagle-Picher, a major aerospace battery manufacturer, who has scaled up the process developed at NASA GRC and fabricated electrodes for incorporation into flight-weight nickel-hydrogen cells.

Deterministic multi-step rotation of magnetic single-domain state in Nickel nanodisks using multiferroic magnetoelastic coupling

NASA Astrophysics Data System (ADS)

Sohn, Hyunmin; Liang, Cheng-yen; Nowakowski, Mark E.; Hwang, Yongha; Han, Seungoh; Bokor, Jeffrey; Carman, Gregory P.; Candler, Robert N.

2017-10-01

We demonstrate deterministic multi-step rotation of a magnetic single-domain (SD) state in Nickel nanodisks using the multiferroic magnetoelastic effect. Ferromagnetic Nickel nanodisks are fabricated on a piezoelectric Lead Zirconate Titanate (PZT) substrate, surrounded by patterned electrodes. With the application of a voltage between opposing electrode pairs, we generate anisotropic in-plane strains that reshape the magnetic energy landscape of the Nickel disks, reorienting magnetization toward a new easy axis. By applying a series of voltages sequentially to adjacent electrode pairs, circulating in-plane anisotropic strains are applied to the Nickel disks, deterministically rotating a SD state in the Nickel disks by increments of 45°. The rotation of the SD state is numerically predicted by a fully-coupled micromagnetic/elastodynamic finite element analysis (FEA) model, and the predictions are experimentally verified with magnetic force microscopy (MFM). This experimental result will provide a new pathway to develop energy efficient magnetic manipulation techniques at the nanoscale.

Fatigue Resistance of the Grain Size Transition Zone in a Dual Microstructure Superalloy Disk

NASA Technical Reports Server (NTRS)

Gabb, T. P.; Kantzos, P. T.; Telesman, J.; Gayda, J.; Sudbrack, C. K.; Palsa, B. S.

2010-01-01

Mechanical property requirements vary with location in nickel-based superalloy disks. To maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored microstructures. In this study, a specialized heat treatment method was applied to produce varying grain microstructures from the bore to the rim portions of a powder metallurgy processed nickel-based superalloy disk. The bore of the contoured disk consisted of fine grains to maximize strength and fatigue resistance at lower temperatures. The rim microstructure of the disk consisted of coarse grains for maximum resistance to creep and dwell crack growth at high temperatures up to 704 C. However, the fatigue resistance of the grain size transition zone was unclear, and needed to be evaluated. This zone was located as a band in the disk web between the bore and rim. Specimens were extracted parallel and transverse to the transition zone, and multiple fatigue tests were performed at 427 and 704 C. Mean fatigue lives were lower at 427 C than for 704 C. Specimen failures often initiated at relatively large grains, which failed on crystallographic facets. Grain size distributions were characterized in the specimens, and related to the grains initiating failures as well as location within the transition zone. Fatigue life decreased with increasing maximum grain size. Correspondingly, mean fatigue resistance of the transition zone was slightly higher than that of the rim, but lower than that of the bore. The scatter in limited tests of replicates was comparable for all transition zone locations examined.

Extreme ultraviolet reflection efficiencies of diamond-turned aluminum, polished nickel, and evaporated gold surfaces. [for telescope mirrors

NASA Technical Reports Server (NTRS)

Malina, R. F.; Cash, W.

1978-01-01

Measured reflection efficiencies are presented for flat samples of diamond-turned aluminum, nickel, and evaporated gold surfaces fabricated by techniques suited for EUV telescopes. The aluminum samples were 6.2-cm-diameter disks of 6061-T6, the electroless nickel samples were formed by plating beryllium disks with 7.5-microns of Kanigen. Gold samples were produced by coating the aluminum and nickel samples with 5 strips of evaporated gold. Reflection efficiencies are given for grazing angles in the 5-75 degree range. The results indicate that for wavelengths over about 100 A, the gold-coated nickel samples yield highest efficiencies. For shorter wavelengths, the nickel samples yield better efficiencies. 500 A is found to be the optimal gold thickness.

Recent Advances in the Synthesis and Stabilization of Nickel and Nickel Oxide Nanoparticles: A Green Adeptness

PubMed Central

Rani, Aneela

2016-01-01

Green protocols for the synthesis of nanoparticles have been attracting a lot of attention because they are eco-friendly, rapid, and cost-effective. Nickel and nickel oxide nanoparticles have been synthesized by green routes and characterized for impact of green chemistry on the properties and biological effects of nanoparticles in the last five years. Green synthesis, properties, and applications of nickel and nickel oxide nanoparticles have been reported in the literature. This review summarizes the synthesis of nickel and nickel oxide nanoparticles using different biological systems. This review also provides comparative overview of influence of chemical synthesis and green synthesis on structural properties of nickel and nickel oxide nanoparticles and their biological behavior. It concludes that green methods for synthesis of nickel and nickel oxide nanoparticles are better than chemical synthetic methods. PMID:27413375

Nickel-based anodic electrocatalysts for fuel cells and water splitting

NASA Astrophysics Data System (ADS)

Chen, Dayi

Our world is facing an energy crisis, so people are trying to harvest and utilize energy more efficiently. One of the promising ways to harvest energy is via solar water splitting to convert solar energy to chemical energy stored in hydrogen. Another of the options to utilize energy more efficiently is to use fuel cells as power sources instead of combustion engines. Catalysts are needed to reduce the energy barriers of the reactions happening at the electrode surfaces of the water-splitting cells and fuel cells. Nickel-based catalysts happen to be important nonprecious electrocatalysts for both of the anodic reactions in alkaline media. In alcohol fuel cells, nickel-based catalysts catalyze alcohol oxidation. In water splitting cells, they catalyze water oxidation, i.e., oxygen evolution. The two reactions occur in a similar potential range when catalyzed by nickel-based catalysts. Higher output current density, lower oxidation potential, and complete substrate oxidation are preferred for the anode in the applications. In this dissertation, the catalytic properties of nickel-based electrocatalysts in alkaline medium for fuel oxidation and oxygen evolution are explored. By changing the nickel precursor solubility, nickel complex nanoparticles with tunable sizes on electrode surfaces were synthesized. Higher methanol oxidation current density is achieved with smaller nickel complex nanoparticles. DNA aggregates were used as a polymer scaffold to load nickel ion centers and thus can oxidize methanol completely at a potential about 0.1 V lower than simple nickel electrodes, and the methanol oxidation pathway is changed. Nickel-based catalysts also have electrocatalytic activity towards a wide range of substrates. Experiments show that methanol, ethanol, glycerol and glucose can be deeply oxidized and carbon-carbon bonds can be broken during the oxidation. However, when comparing methanol oxidation reaction to oxygen evolution reaction catalyzed by current nickel-based

High energy density micro-fiber based nickel electrode for aerospace batteries

NASA Technical Reports Server (NTRS)

Francisco, Jennifer; Chiappetti, Dennis; Coates, Dwaine

1996-01-01

The nickel electrode is the specific energy limiting component in battery systems such as nickel-hydrogen, nickel-metal hydride and nickel-zinc. Lightweight, high energy density nickel electrodes have been developed which deliver in excess of 180 mAh/g at the one-hour discharge rate. These electrodes are based on a highly porous, nickel micro-fiber (less than 10 micron diameter) substrate, electrochemically impregnated with nickel-hydroxide active material. Electrodes are being tested both as a flooded half-cell and in full nickel-hydrogen and nickel-metal hydride cells. The electrode technology developed is applicable to commercial nickel-based batteries for applications such as electric vehicles, cellular telephones and laptop computers and for low-cost, high energy density military and aerospace applications.

Retention of Compressive Residual Stresses Introduced by Shot Peening in a Powder Metal Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Danetti, Andrew; Draper, Susan L.; Locci, Ivan E.; Telesman, Jack

2016-01-01

The fatigue lives of disk superalloys can be increased by shot peening their surfaces, to induce compressive residual stresses near the surface that impede cracking there. As disk application temperatures increase for improved efficiency, the persistence of these beneficial stresses could be impaired, especially with continued fatigue cycling. The objective of this work was to study the retention of residual stresses introduced by shot peening, when subjected to fatigue and high temperatures. Fatigue specimens of powder metallurgy processed nickel-base disk superalloy ME3 were prepared with consistent processing and heat treatment. They were then shot peened using varied conditions. Strain-controlled fatigue cycles were run at room temperature and 704 C, to allow re-assessment of residual stresses.

Validation test of 125 Ah advanced design IPV nickel-hydrogen flight cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1993-01-01

An update of validation test results confirming the advanced design nickel-hydrogen cell is presented. An advanced 125 Ah individual pressure vessel Ni-H cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term LEO spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent KOH electrolyte; (2) use of a patented catalyzed wall wick; (3) use of serrated-edge separators to facilitate gaseous O and H flow within the cell, while maintaining physical contact with the wall wick for electrolyte management; and (4) use of a floating rather than a fixed stack to accommodate Ni electrode expansion due to charge/discharge cycling. The significant improvements resulting from these innovations are extended cycle life; enhanced thermal, electrolyte, and oxygen management; and accommodation of Ni electrode expansion. Six 125 Ah flight cells based on this design were fabricated; the catalyzed wall wick cells have been cycled for over 19,000 cycles with no cell failures in the continuing test. Two of the noncatalyzed wall wick cells failed (cycles 9588 and 13,900).

Development study of compositions for advanced wrought nickel-base superalloys

NASA Technical Reports Server (NTRS)

Kent, W. B.

1972-01-01

Using NASA IIb as a base composition, the effects of five key elements (carbon, tungsten, tantalum, aluminum, and hafnium) on resultant properties were investigated in an effort to optimize the composition and derive new wrought high temperature alloys with improved strength characteristics. A total of nineteen compositions were melted, extruded, and rolled to bar stock using thermomechanical processing. Both full and partial solution heat treatments were developed for the compositions. Tensile properties from room temperature to 1800 deg F, stress and creep rupture properties to 1800 deg F, and thermal stability characteristics were evaluated. NASA IIb-7 exhibited the best response to the partial solution heat treatment for optimum properties up to 1200 deg F. The alloy contained 0.13C, 9.0 Cr, 9.0 Co, 2.0 Mo, 7.5 W, 10.0 Ta, 3.5 Al, 0.75 Ti, 0.02 B, 0.10 Zr, 0.50 V, 1.0 Hf, and balance nickel.

Directionally solidified eutectic gamma plus beta nickel-base superalloys

NASA Technical Reports Server (NTRS)

Jackson, M. R. (Inventor)

1977-01-01

A directionally solidified multivariant eutectic gamma + beta nickel-base superalloy casting having improved high temperature strength and oxidation resistance properties is provided. This comprises a two phase eutectic structure containing, on a weight percent basis, 5.0-15.0 tungsten, 8.5-14.5 aluminum, 0.0-35.0 cobalt and the balance being nickel. Embedded within the gamma phase nickel-base matrix are aligned eutectic beta phase (primarily (NiCo)Al reinforcing lamellae.

Study of the properties and the choice of alloys for bladed disks (blisks) and a method for their joining

NASA Astrophysics Data System (ADS)

Povarova, K. B.; Valitov, V. A.; Obsepyan, S. V.; Drozdov, A. A.; Bazyleva, O. A.; Valitova, E. V.

2014-09-01

The choice of materials for the bladed disks (blisks) that are intended for next-generation aviation gas turbine engines is grounded. As blade materials, single crystals of light heterophase γ' + γ VKNA-type alloys based on the γ'(Ni3Al) intermetallic compound with an ordered structure are proposed. The choice of novel deformable EP975-type nickel superalloys, which are intended for operation at 800-850°C, as the disk material is grounded. It is shown that the most effective method for forming one-piece joints of an Ni3Al-based alloy and a high-alloy EP975-type nickel superalloy is the new process of solid-phase pressure welding under conditions of high-temperature superplasticity. Solid-phase joints are formed for heterophase Ni3Al-based alloy single crystals and deformable EK61 and EP975 nickel alloys. The gradient structures in the zone of the solid-phase joints that form under the conditions of low- and high-temperature superplasticity at homologous temperatures of ˜0.6 T m and 0.9 T m are studied. The character and direction of the diffusion processes at the joint of an intermetallic alloy single crystal and a deformable polycrystalline alloy are determined.

Advanced nickel-metal hydride cell development at Hughes: A joint work with US government

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, H.S.; Pickett, D.F.; Stockel, J.F.

1995-01-25

Hughes is currently engaged in the development of an advanced nickel-metal hydride (Ni/MHx) cell for spacecraft application with performance goals of 15 years of opertion in a geosynchronous earth orbit at 80% depth of discharge and over 30,000 cycles of life at 30% depth of discharge in a typical low earth orbit. We have developed the basic fabrication technique for a lightweight and potentially long life nickel electrode which is useable in space Ni/MHx cells. We have developed several attractive hydride alloys which are useable in hydride electrodes and basic fabrication techniques for lightweight, inexpensive, and potentially long life hydridemore » electrodes for a Ni/MHx cell. Utilizing Hughes extensive experiences in development of advanced Ni/Cd and Ni/H{sub 2} cells, we plan to develop a first generation space Ni/MHx cell design by 1995 and have the cell flight ready by 1997.« less

Advanced nickel-metal hydride cell development at Hughes: A joint work with US government

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, H.S.; Pickett, D.F.; Stockel, J.F.

1995-07-01

Hughes is currently engaged in the development of an advanced nickel-metal hydride (Ni/MHx) cell for spacecraft application with performance goals of 15 years of operation in a geosynchronous earth orbit at 805 depth of discharge and over 30,000 cycles of life at 30% depth of discharge in a typical low earth orbit. The authors have developed the basic fabrication technique for a lightweight and potentially long life nickel electrode which is usable in space Ni/MHx cells. The authors have developed several attractive hydride alloys which are usable in hydride electrodes and basic fabrication techniques for lightweight, inexpensive, and potentially longmore » life hydride electrodes for a Ni/MHx cell. Utilizing Hughes extensive experiences in development of advanced Ni/Cd and Ni/H{sub 2} cells, the authors plan to develop a first generation space Ni/MHx cell design by 1995 and have the cell flight ready by 1997.« less

Methodology Developed for Modeling the Fatigue Crack Growth Behavior of Single-Crystal, Nickel-Base Superalloys

NASA Technical Reports Server (NTRS)

1996-01-01

Because of their superior high-temperature properties, gas generator turbine airfoils made of single-crystal, nickel-base superalloys are fast becoming the standard equipment on today's advanced, high-performance aerospace engines. The increased temperature capabilities of these airfoils has allowed for a significant increase in the operating temperatures in turbine sections, resulting in superior propulsion performance and greater efficiencies. However, the previously developed methodologies for life-prediction models are based on experience with polycrystalline alloys and may not be applicable to single-crystal alloys under certain operating conditions. One of the main areas where behavior differences between single-crystal and polycrystalline alloys are readily apparent is subcritical fatigue crack growth (FCG). The NASA Lewis Research Center's work in this area enables accurate prediction of the subcritical fatigue crack growth behavior in single-crystal, nickel-based superalloys at elevated temperatures.

Intermetallic Nickel-Titanium Alloys for Oil-Lubricated Bearing Applications

NASA Technical Reports Server (NTRS)

DellaCorte, C.; Pepper, S. V.; Noebe, R.; Hull, D. R.; Glennon, G.

2009-01-01

An intermetallic nickel-titanium alloy, NITINOL 60 (60NiTi), containing 60 wt% nickel and 40 wt% titanium, is shown to be a promising candidate material for oil-lubricated rolling and sliding contact applications such as bearings and gears. NiTi alloys are well known and normally exploited for their shape memory behavior. When properly processed, however, NITINOL 60 exhibits excellent dimensional stability and useful structural properties. Processed via high temperature, high-pressure powder metallurgy techniques or other means, NITINOL 60 offers a broad combination of physical properties that make it unique among bearing materials. NITINOL 60 is hard, electrically conductive, highly corrosion resistant, less dense than steel, readily machined prior to final heat treatment, nongalling and nonmagnetic. No other bearing alloy, metallic or ceramic encompasses all of these attributes. Further, NITINOL 60 has shown remarkable tribological performance when compared to other aerospace bearing alloys under oil-lubricated conditions. Spiral orbit tribometer (SOT) tests were conducted in vacuum using NITINOL 60 balls loaded between rotating 440C stainless steel disks, lubricated with synthetic hydrocarbon oil. Under conditions considered representative of precision bearings, the performance (life and friction) equaled or exceeded that observed with silicon nitride or titanium carbide coated 440C bearing balls. Based upon this preliminary data, it appears that NITINOL 60, despite its high titanium content, is a promising candidate alloy for advanced mechanical systems requiring superior and intrinsic corrosion resistance, electrical conductivity and nonmagnetic behavior under lubricated contacting conditions.

High weldability nickel-base superalloy

DOEpatents

Gibson, Robert C.; Korenko, Michael K.

1980-01-01

This is a nickel-base superalloy with excellent weldability and high strength. Its composition consists essentially of, by weight percent, 10-20 iron, 57-63 nickel, 7-18 chromium, 4-6 molybdenum, 1-2 niobium, 0.2-0.8 silicon, 0.01-0.05 zirconium, 1.0-2.5 titanium, 1.0-2.5 aluminum, 0.02-0.06 carbon, and 0.002-0.015 boron. The weldability and strength of this alloy give it a variety of applications. The long-time structural stability of this alloy together with its low swelling under nuclear radiation conditions, make it especially suitable for use as a duct material and controlling element cladding for sodium-cooled nuclear reactors.

Advanced optical disk storage technology

NASA Technical Reports Server (NTRS)

Haritatos, Fred N.

1996-01-01

There is a growing need within the Air Force for more and better data storage solutions. Rome Laboratory, the Air Force's Center of Excellence for C3I technology, has sponsored the development of a number of operational prototypes to deal with this growing problem. This paper will briefly summarize the various prototype developments with examples of full mil-spec and best commercial practice. These prototypes have successfully operated under severe space, airborne and tactical field environments. From a technical perspective these prototypes have included rewritable optical media ranging from a 5.25-inch diameter format up to the 14-inch diameter disk format. Implementations include an airborne sensor recorder, a deployable optical jukebox and a parallel array of optical disk drives. They include stand-alone peripheral devices to centralized, hierarchical storage management systems for distributed data processing applications.

Major Effects of Nonmetallic Inclusions on the Fatigue Life of Disk Superalloy Demonstrated

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; Bonacuse, Peter J.; Barrie, Robert L.

2002-01-01

The fatigue properties of modern powder metallurgy disk alloys can vary because of the different steps of materials and component processing and machining. Among these variables, the effects of nonmetallic inclusions introduced during the powder atomization and handling processes have been shown to significantly degrade low-cycle fatigue life. The levels of inclusion contamination have, therefore, been reduced to less than 1 part per million in state-of-the-art nickel disk powder-processing facilities. Yet the large quantities of compressor and turbine disks weighing from 100 to over 1000 lb have enough total volume and surface area for these rare inclusions to still be present and limit fatigue life. The objective of this study was to investigate the effects on fatigue life of these inclusions, as part of the Crack Resistant Disk Materials task within the Ultra Safe Propulsion Project. Inclusions were carefully introduced at elevated levels in a nickel-base disk superalloy, U720, produced using powder metallurgy processing. Multiple strain-controlled fatigue tests were then performed on extracted test specimens at 650 C. Analyses were performed to compare the low-cycle fatigue lives and failure initiation sites as functions of inclusion content and fatigue conditions. Powder of the nickel-base superalloy U720 was atomized in argon at Special Metals Corporation, Inc., using production-scale high-cleanliness powder-processing facilities and handling practices. The powder was then passed through a 270-mesh screen. One portion of this powder was set aside for subsequent consolidation without introduced inclusions. Two other portions of this powder were seeded with alumina inclusions. Small, polycrystalline soft (Type 2) inclusions of about 50 mm diameter were carefully prepared and blended into one powder lot, and larger hard (Type 1) inclusions of about 150 mm mean diameter were introduced into the other seeded portion of powder. All three portions of powder were

Thermodynamic Considerations of Contamination by Alloying Elements of Remelted End-of-Life Nickel- and Cobalt-Based Superalloys

NASA Astrophysics Data System (ADS)

Lu, Xin; Matsubae, Kazuyo; Nakajima, Kenichi; Nakamura, Shinichiro; Nagasaka, Tetsuya

2016-06-01

Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies.

Nickel-based Enzyme Systems*

PubMed Central

Ragsdale, Stephen W.

2009-01-01

Of the eight known nickel enzymes, all but glyoxylase I catalyze the use and/or production of gases central to the global carbon, nitrogen, and oxygen cycles. Nickel appears to have been selected for its plasticity in coordination and redox chemistry and is able to cycle through three redox states (1+, 2+, 3+) and to catalyze reactions spanning ∼1.5 V. This minireview focuses on the catalytic mechanisms of nickel enzymes, with an emphasis on the role(s) of the metal center. The metal centers vary from mononuclear to complex metal clusters and catalyze simple hydrolytic to multistep redox reactions. PMID:19363030

The interaction of reaction-bonded silicon carbide and inconel 600 with a nickel-based brazing alloy

NASA Astrophysics Data System (ADS)

McDermid, J. R.; Pugh, M. D.; Drew, R. A. L.

1989-09-01

The objective of the present research was to join reaction-bonded silicon carbide (RBSC) to INCONEL 600 (a nickel-based superalloy) for use in advanced heat engine applications using either direct brazing or composite interlayer joining. Direct brazing experiments employed American Welding Society (AWS) BNi-5, a commercial nickel-based brazing alloy, as a filler material; composite interlayers consisted of intimate mixtures of α-SiC and BNi-5 powders. Both methods resulted in the liquid filler metal forming a Ni-Si liquid with the free Si in the RBSC, which, in turn, reacted vigorously with the SiC component of the RBSC to form low melting point constituents in both starting materials and Cr carbides at the metal-ceramic interface. Using solution thermodynamics, it was shown that a Ni-Si liquid of greater than 60 at. pct Ni will decompose a-SiC at the experimental brazing temperature of 1200 ‡C; these calculations are consistent with the experimentally observed composition profiles and reaction morphology within the ceramic. It was concluded that the joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is not feasible due to the inevitability of the filler metal reacting with the ceramic, degrading the high-temperature properties of the base materials.

Effects of cobalt in nickel-base superalloys

NASA Technical Reports Server (NTRS)

Tien, J. K.; Jarrett, R. N.

1983-01-01

The role of cobalt in a representative wrought nickel-base superalloy was determined. The results show cobalt affecting the solubility of elements in the gamma matrix, resulting in enhanced gamma' volume fraction, in the stabilization of MC-type carbides, and in the stabilization of sigma phase. In the particular alloy studied, these microstructural and microchemistry changes are insufficient in extent to impact on tensile strength, yield strength, and in the ductilities. Depending on the heat treatment, creep and stress rupture resistance can be cobalt sensitive. In the coarse grain, fully solutioned and aged condition, all of the alloy's 17% cobalt can be replaced by nickel without deleteriously affecting this resistance. In the fine grain, partially solutioned and aged condition, this resistance is deleteriously affected only when one-half or more of the initial cobalt content is removed. The structure and property results are discussed with respect to existing theories and with respect to other recent and earlier findings on the impact of cobalt, if any, on the performance of nickel-base superalloys.

Assessment of disk MHD generators for a base load powerplant

NASA Technical Reports Server (NTRS)

Chubb, D. L.; Retallick, F. D.; Lu, C. L.; Stella, M.; Teare, J. D.; Loubsky, W. J.; Louis, J. F.; Misra, B.

1981-01-01

Results from a study of the disk MHD generator are presented. Both open and closed cycle disk systems were investigated. Costing of the open cycle disk components (nozzle, channel, diffuser, radiant boiler, magnet and power management) was done. However, no detailed costing was done for the closed cycle systems. Preliminary plant design for the open cycle systems was also completed. Based on the system study results, an economic assessment of the open cycle systems is presented. Costs of the open cycle disk conponents are less than comparable linear generator components. Also, costs of electricity for the open cycle disk systems are competitive with comparable linear systems. Advantages of the disk design simplicity are considered. Improvements in the channel availability or a reduction in the channel lifetime requirement are possible as a result of the disk design.

Nickel speciation in several serpentine (ultramafic) topsoils via bulk synchrotron-based techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siebecker, Matthew G.; Chaney, Rufus L.; Sparks, Donald L.

2017-07-01

Serpentine soils have elevated concentrations of trace metals including nickel, cobalt, and chromium compared to non-serpentine soils. Identifying the nickel bearing minerals allows for prediction of potential mobility of nickel. Synchrotron-based techniques can identify the solid-phase chemical forms of nickel with minimal sample treatment. Element concentrations are known to vary among soil particle sizes in serpentine soils. Sonication is a useful method to physically disperse sand, silt and clay particles in soils. Synchrotron-based techniques and sonication were employed to identify nickel species in discrete particle size fractions in several serpentine (ultramafic) topsoils to better understand solid-phase nickel geochemistry. Nickel commonlymore » resided in primary serpentine parent material such as layered-phyllosilicate and chain-inosilicate minerals and was associated with iron oxides. In the clay fractions, nickel was associated with iron oxides and primary serpentine minerals, such as lizardite. Linear combination fitting (LCF) was used to characterize nickel species. Total metal concentration did not correlate with nickel speciation and is not an indicator of the major nickel species in the soil. Differences in soil texture were related to different nickel speciation for several particle size fractionated samples. A discussion on LCF illustrates the importance of choosing standards based not only on statistical methods such as Target Transformation but also on sample mineralogy and particle size. Results from the F-test (Hamilton test), which is an underutilized tool in the literature for LCF in soils, highlight its usefulness to determine the appropriate number of standards to for LCF. EXAFS shell fitting illustrates that destructive interference commonly found for light and heavy elements in layered double hydroxides and in phyllosilicates also can occur in inosilicate minerals, causing similar structural features and leading to false positive

Fretting Fatigue of Single Crystal/Polycrystalline Nickel Subjected to Blade/Disk Contact Loading

NASA Astrophysics Data System (ADS)

Matlik, J. F.; Murthy, H.; Farris, T. N.

2002-01-01

Fretting fatigue describes the formation and growth of cracks at the edge-of-contact of nominally clamped components subjected to cyclic loading. Components that are known to be subject to fretting fatigue include riveted lap joints and blade/disk contacts in launch vehicle turbomachinery. Recent efforts have shown that conventional mechanics tools, both fatigue and fracture based, can be used to model fretting fatigue experiments leading to successful life predictions. In particular, experiments involving contact load configurations similar to those that occur in the blade/disk connection of gas turbine engines have been performed extensively. Predictions of fretting fatigue life have been compared favorably to experimental observations [1]. Recent efforts are aimed at performing experiments at higher temperatures as shown in the photograph below along with a sample fracture surface. The talk will describe the status of these experiments as will as model developments relevant to the single crystal material properties.

Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Chen; Gupta, Vipul; Huang, Shenyan

The goal of this project is to model long-term creep performance for nickel-base superalloy weldments in high temperature power generation systems. The project uses physics-based modeling methodologies and algorithms for predicting alloy properties in heterogeneous material structures. The modeling methodology will be demonstrated on a gas turbine combustor liner weldment of Haynes 282 precipitate-strengthened nickel-base superalloy. The major developments are: (1) microstructure-property relationships under creep conditions and microstructure characterization (2) modeling inhomogeneous microstructure in superalloy weld (3) modeling mesoscale plastic deformation in superalloy weld and (4) a constitutive creep model that accounts for weld and base metal microstructure and theirmore » long term evolution. The developed modeling technology is aimed to provide a more efficient and accurate assessment of a material’s long-term performance compared with current testing and extrapolation methods. This modeling technology will also accelerate development and qualification of new materials in advanced power generation systems. This document is a final technical report for the project, covering efforts conducted from October 2014 to December 2016.« less

Bipolar Nickel-Metal Hydride Battery Being Developed

NASA Technical Reports Server (NTRS)

Manzo, Michelle A.

1998-01-01

The NASA Lewis Research Center has contracted with Electro Energy, Inc., to develop a bipolar nickel-metal hydride battery design for energy storage on low-Earth-orbit satellites. The objective of the bipolar nickel-metal hydride battery development program is to approach advanced battery development from a systems level while incorporating technology advances from the lightweight nickel electrode field, hydride development, and design developments from nickel-hydrogen systems. This will result in a low-volume, simplified, less-expensive battery system that is ideal for small spacecraft applications. The goals of the program are to develop a 1-kilowatt, 28-volt (V), bipolar nickel-metal hydride battery with a specific energy of 100 watt-hours per kilogram (W-hr/kg), an energy density of 250 W-hr/liter and a 5-year life in low Earth orbit at 40-percent depth-of-discharge.

Nickel-silver alloy electrocatalysts for hydrogen evolution and oxidation in an alkaline electrolyte.

PubMed

Tang, Maureen H; Hahn, Christopher; Klobuchar, Aidan J; Ng, Jia Wei Desmond; Wellendorff, Jess; Bligaard, Thomas; Jaramillo, Thomas F

2014-09-28

The development of improved catalysts for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in basic electrolytes remains a major technical obstacle to improved fuel cells, water electrolyzers, and other devices for electrochemical energy storage and conversion. Based on the free energy of adsorbed hydrogen intermediates, theory predicts that alloys of nickel and silver are active for these reactions. In this work, we synthesize binary nickel-silver bulk alloys across a range of compositions and show that nickel-silver alloys are indeed more active than pure nickel for hydrogen evolution and, possibly, hydrogen oxidation. To overcome the mutual insolubility of silver and nickel, we employ electron-beam physical vapor codeposition, a low-temperature synthetic route to metastable alloys. This method also produces flat and uniform films that facilitate the measurement of intrinsic catalytic activity with minimal variations in the surface area, ohmic contact, and pore transport. Rotating-disk-electrode measurements demonstrate that the hydrogen evolution activity per geometric area of the most active catalyst in this study, Ni0.75Ag0.25, is approximately twice that of pure nickel and has comparable stability and hydrogen oxidation activity. Our experimental results are supported by density functional theory calculations, which show that bulk alloying of Ni and Ag creates a variety of adsorption sites, some of which have near-optimal hydrogen binding energy.

Aerodynamic and torque characteristics of enclosed Co/counter rotating disks

NASA Astrophysics Data System (ADS)

Daniels, W. A.; Johnson, B. V.; Graber, D. J.

1989-06-01

Experiments were conducted to determine the aerodynamic and torque characteristics of adjacent rotating disks enclosed in a shroud, in order to obtain an extended data base for advanced turbine designs such as the counterrotating turbine. Torque measurements were obtained on both disks in the rotating frame of reference for corotating, counterrotating and one-rotating/one-static disk conditions. The disk models used in the experiments included disks with typical smooth turbine geometry, disks with bolts, disks with bolts and partial bolt covers, and flat disks. A windage diaphragm was installed at mid-cavity for some experiments. The experiments were conducted with various amounts of coolant throughflow injected into the disk cavity from the disk hub or from the disk OD with swirl. The experiments were conducted at disk tangential Reynolds number up to 1.6 x 10 to the 7th with air as the working fluid. The results of this investigation indicated that the static shroud contributes a significant amount to the total friction within the disk system; the torque on counterrotating disks is essentially independent of coolant flow total rate, flow direction, and tangential Reynolds number over the range of conditions tested; and a static windage diaphragm reduces disk friction in counterrotating disk systems.

Magneto-thermal Disk Winds from Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Bai, Xue-Ning; Ye, Jiani; Goodman, Jeremy; Yuan, Feng

2016-02-01

The global evolution and dispersal of protoplanetary disks (PPDs) are governed by disk angular-momentum transport and mass-loss processes. Recent numerical studies suggest that angular-momentum transport in the inner region of PPDs is largely driven by magnetized disk wind, yet the wind mass-loss rate remains unconstrained. On the other hand, disk mass loss has conventionally been attributed to photoevaporation, where external heating on the disk surface drives a thermal wind. We unify the two scenarios by developing a one-dimensional model of magnetized disk winds with a simple treatment of thermodynamics as a proxy for external heating. The wind properties largely depend on (1) the magnetic field strength at the wind base, characterized by the poloidal Alfvén speed vAp, (2) the sound speed cs near the wind base, and (3) how rapidly poloidal field lines diverge (achieve {R}-2 scaling). When {v}{Ap}\\gg {c}{{s}}, corotation is enforced near the wind base, resulting in centrifugal acceleration. Otherwise, the wind is accelerated mainly by the pressure of the toroidal magnetic field. In both cases, the dominant role played by magnetic forces likely yields wind outflow rates that exceed purely hydrodynamical mechanisms. For typical PPD accretion-rate and wind-launching conditions, we expect vAp to be comparable to cs at the wind base. The resulting wind is heavily loaded, with a total wind mass-loss rate likely reaching a considerable fraction of the wind-driven accretion rate. Implications for modeling global disk evolution and planet formation are also discussed.

Head-Disk Interface Technology: Challenges and Approaches

NASA Astrophysics Data System (ADS)

Liu, Bo

Magnetic hard disk drive (HDD) technology is believed to be one of the most successful examples of modern mechatronics systems. The mechanical beauty of magnetic HDD includes simple but super high accuracy positioning head, positioning technology, high speed and stability spindle motor technology, and head-disk interface technology which keeps the millimeter sized slider flying over a disk surface at nanometer level slider-disk spacing. This paper addresses the challenges and possible approaches on how to further reduce the slider disk spacing whilst retaining the stability and robustness level of head-disk systems for future advanced magnetic disk drives.

Gamma prime hardened nickel-iron based superalloy

DOEpatents

Korenko, Michael K.

1978-01-01

A low swelling, gamma prime hardened nickel-iron base superalloy useful for fast reactor duct and cladding applications is described having from about 7.0 to about 10.5 weight percent (wt%) chromium, from about 24 to about 35 wt% nickel, from about 1.7 to about 2.5 wt% titanium, from about 0.3 to about 1.0 wt% aluminum, from about 2.0 to about 3.3 wt% molybdenum, from about 0.05 to about 1.0 wt% silicon, from about 0.03 to about 0.06 wt% carbon, a maximum of about 2 wt% manganese, and the balance iron.

Nine percent nickel steel heavy forging weld repair study. [National Transonic Wind Tunnel fan components

NASA Technical Reports Server (NTRS)

Young, C. P., Jr.; Gerringer, A. H.; Brooks, T. G.; Berry, R. F., Jr.

1978-01-01

The feasibility of making weld repairs on heavy section 9% nickel steel forgings such as those being manufactured for the National Transonic Facility fan disk and fan drive shaft components was evaluated. Results indicate that 9% nickel steel in heavy forgings has very good weldability characteristics for the particular weld rod and weld procedures used. A comparison of data for known similar work is included.

Innovative technologies for powder metallurgy-based disk superalloys: Progress and proposal

NASA Astrophysics Data System (ADS)

Chong-Lin, Jia; Chang-Chun, Ge; Qing-Zhi, Yan

2016-02-01

Powder metallurgy (PM) superalloys are an important class of high temperature structural materials, key to the rotating components of aero engines. In the purview of the present challenges associated with PM superalloys, two novel approaches namely, powder preparation and the innovative spray-forming technique (for making turbine disk) are proposed and studied. Subsequently, advanced technologies like electrode-induction-melting gas atomization (EIGA), and spark-plasma discharge spheroidization (SPDS) are introduced, for ceramic-free superalloy powders. Presently, new processing routes are sought after for preparing finer and cleaner raw powders for disk superalloys. The progress of research in spray-formed PM superalloys is first summarized in detail. The spray-formed superalloy disks specifically exhibit excellent mechanical properties. This paper reviews the recent progress in innovative technologies for PM superalloys, with an emphasis on new ideas and approaches, central to the innovation driving techniques like powder processing and spray forming. Project supported by the National Natural Science Foundation of China (Grant Nos. 50974016 and 50071014).

Thermal and mechanical treatments for nickel and some nickel-base alloys: Effects on mechanical properties

NASA Technical Reports Server (NTRS)

Hall, A. M.; Beuhring, V. F.

1972-01-01

This report deals with heat treating and working nickel and nickel-base alloys, and with the effects of these operations on the mechanical properties of the materials. The subjects covered are annealing, solution treating, stress relieving, stress equalizing, age hardening, hot working, cold working, combinations of working and heat treating (often referred to as thermomechanical treating), and properties of the materials at various temperatures. The equipment and procedures used in working the materials are discussed, along with the common problems that may be encountered and the precautions and corrective measures that are available.

New Scattered Disk Object and Centaur Colors

NASA Astrophysics Data System (ADS)

Brucker, Melissa; Wilcox, P.; Stansberry, J.

2013-10-01

We report B, V, and R magnitudes for scattered disk objects and centaurs from observations taken in December 2011 and August 2013 using the Lowell Observatory Perkins Telescope with PRISM and observations taken in March 2012 at the Vatican Advanced Technology Telescope (VATT) on Mt. Graham, Arizona. Targeted scattered disk objects include 2002 CY224, 2003 UY117, 2006 QJ181, 2008 CT190, 2009 YG19, 2010 FD49, 2010 VZ98. Targeted centaurs include 2002 QX47, 2005 UJ438, 2006 UX184, and 2007 RH283. We will determine if the resultant centaur colors follow the bimodal distribution (B-R either red or gray) previously detected. We will also compare the resultant scattered disk object colors to those published for other scattered disk objects. This work is based on observations with the Perkins Telescope at Lowell Observatory, and with the VATT: The Alice P. Lennon Telescope and the Thomas J. Bannan Astrophysics Facility.

Advanced nickel-hydrogen cell configuration study

NASA Technical Reports Server (NTRS)

1983-01-01

Long-term trends in the evolution of space power technology point toward increased payload power demand which in turn translates into both higher battery system charge storage capability and higher operating voltages. State of the art nickel-hydrogen cells of the 50 to 60 Wh size, packaged in individual pressure vessels, are capable of meeting the required cycle life for a wide range of anticipated operating conditions; however, they provided several drawbacks to battery system integrated efforts. Because of size, high voltage/high power systems require integrating hundreds of cells into the operating system. Packaging related weight and volume inefficiencies degrade the energy density and specific energy of individual cells currently at 30 Wh/cudm and 40 Wh/kg respectively. In addition, the increased parts count and associated handling significantly affect the overall battery related costs. Spacecraft battery systems designers within industry and Government realize that to reduce weight, volume, and cost requires increases in the capacity of nickel-hydrogen cells.

Urinary nickel excretion in populations living in the proximity of two russian nickel refineries: a Norwegian-Russian population-based study.

PubMed Central

Smith-Sivertsen, T; Tchachtchine, V; Lund, E; Bykov, V; Thomassen, Y; Norseth, T

1998-01-01

The Russian nickel refineries located in the cities of Nikel and Zapolyarny close to the Norwegian border are responsible for extensive sulfur dioxide and nickel pollution, as well as severe ecological damage in both countries. The aim of our study was to investigate human nickel exposure in the populations living on both sides of the Norwegian-Russian border. The design was a cross-sectional population-based study of adults aged 18-69 years residing in Sor-Varanger municipality, Norway, and Nikel and Zapolyarny, Russia, during 1994 and 1995. Individual exposure to nickel was assessed by measurements of nickel in urine using electrothermal atomic absorption spectrometry. For controls, urine was collected from adults in the Russian cities of Apatity and Umba (Kola Peninsula) and the Norwegian city of Tromso, all of which are locations without nearby point sources of nickel. Altogether 2,233 urine specimens were analysed for nickel. People living in Nikel had the highest concentrations (median 3.4 microg/l), followed by Umba (median 2.7 microg/l), Zapolyarny (median 2.0 microg/l), Apatity (median 1.9 microg/l), Tromso (median 1.2 microg/l), and Sor-Varanger (median 0.6 microg/l). Regardless of geographical location, the Russian study groups all had a higher urinary-nickel average than those in Norway (p<0.001). With the exception of Nikel, neither the Russian nor the Norwegian urinary-nickel levels were associated with residence location near a Russian nickel refinery. We concluded that industrial nickel pollution alone could not explain the observed discrepancy between Norway and Russia; we also discuss other possible nickel exposure sources that may account for the high urinary levels found in Russia. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:9681979

Reliability model of disk arrays RAID-5 with data striping

NASA Astrophysics Data System (ADS)

Rahman, P. A.; D'K Novikova Freyre Shavier, G.

2018-03-01

Within the scope of the this scientific paper, the simplified reliability model of disk arrays RAID-5 (redundant arrays of inexpensive disks) and an advanced reliability model offered by the authors taking into the consideration nonzero time of the faulty disk replacement and different failure rates of disks in normal state of the disk array and in degraded and rebuild states are discussed. The formula obtained by the authors for calculation of the mean time to data loss (MTTDL) of the RAID-5 disk arrays on basis of the advanced model is also presented. Finally, the technique of estimation of the initial reliability parameters, which are used in the reliability model, and the calculation examples of the mean time to data loss of the RAID-5 disk arrays for the different number of disks are also given.

Precise tuning in platinum-nickel/nickel sulfide interface nanowires for synergistic hydrogen evolution catalysis

PubMed Central

Wang, Pengtang; Zhang, Xu; Zhang, Jin; Wan, Sheng; Guo, Shaojun; Lu, Gang; Yao, Jianlin; Huang, Xiaoqing

2017-01-01

Comprising abundant interfaces, multicomponent heterostructures can integrate distinct building blocks into single entities and yield exceptional functionalities enabled by the synergistic components. Here we report an efficient approach to construct one-dimensional metal/sulfide heterostructures by directly sulfuring highly composition-segregated platinum-nickel nanowires. The heterostructures possess a high density of interfaces between platinum-nickel and nickel sulfide components, which cooperate synergistically towards alkaline hydrogen evolution reaction. The platinum-nickel/nickel sulfide heterostructures can deliver a current density of 37.2 mA cm−2 at an overpotential of 70 mV, which is 9.7 times higher than that of commercial Pt/C. The heterostructures also offer enhanced stability revealed by long-term chronopotentiometry measurements. The present work highlights a potentially powerful interface-engineering strategy for designing multicomponent heterostructures with advanced performance in hydrogen evolution reaction and beyond. PMID:28239145

Detailed Microstructural Characterization of the Disk Alloy ME3

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Garg, Anita; Ellis, David L.; O'Connor, Kenneth M.

2004-01-01

The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA/General Electric/Pratt & Whitney HSR/EPM disk program to have extended durability for large disks at maximum temperatures of 600 to 700 C. Scaled-up disks of this alloy were then produced at the conclusion of that program to demonstrate these properties in realistic disk shapes. The objective of the present study was to assess the microstructural characteristics of these ME3 disks at two consistent locations, in order to enable estimation of the variations in microstructure across each disk and across several disks of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor/Turbine Disk program had been sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. For this study, microstructures of grip sections from tensile specimens in the bore and rim were evaluated from these disks. The major and minor phases were identified and quantified using transmission electron microscopy (TEM). Particular attention was directed to the .' precipitates, which along with grain size can predominantly control the mechanical properties of superalloy disks.

Advances in nickel hydrogen technology at Yardney Battery Division

NASA Technical Reports Server (NTRS)

Bentley, J. G.; Hall, A. M.

1987-01-01

The current major activites in nickel hydrogen technology being addressed at Yardney Battery Division are outlined. Five basic topics are covered: an update on life cycle testing of ManTech 50 AH NiH2 cells in the LEO regime; an overview of the Air Force/industry briefing; nickel electrode process upgrading; 4.5 inch cell development; and bipolar NiH2 battery development.

Nickel Ion Release from Three Types of Nickel-titanium-based Orthodontic Archwires in the As-received State and After Oral Simulation

PubMed Central

Ramazanzadeh, Barat Ali; Ahrari, Farzaneh; Sabzevari, Berahman; Habibi, Samaneh

2014-01-01

Background and aims. This study aimed to investigate release of nickel ion from three types of nickel-titanium-based wires in the as-received state and after immersion in a simulated oral environment. Materials and methods. Forty specimens from each of the single-strand NiTi (Rematitan "Lite"), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) were selected. Twenty specimens from each type were used in the as-received state and the others were kept in deflected state at 37ºC for 2 months followed by autoclave sterilization. The as-received and recycled wire specimens were immersed in glass bottles containing 1.8 mL of artificial saliva for 28 days and the amount of nickel ion released into the electrolyte was determined using atomic absorption spectrophotometry. Results. The single-strand NiTi released the highest quantity of nickel ion in the as-received state and the multi-strand NiTi showed the highest ion release after oral simulation. The quantity of nickelion released from Damon Copper NiTi was the lowest in both conditions. Oral simulation followed by sterilization did not have a significant influence on nickel ion release from multi-strand NiTi and Damon Copper NiTi wires, but single-strand NiTi released statistically lower quantities of nickel ion after oral simulation. Conclusion. The multi-strand nature of Supercable did not enhance the potential of corrosion after immersion in the simulated oral environment. In vitro use of nickel-titanium-based archwires followed by sterilization did not significantly increase the amount of nickel ion released from these wires. PMID:25093049

Nickel hydrogen common pressure vessel battery development

NASA Technical Reports Server (NTRS)

Jones, Kenneth R.; Zagrodnik, Jeffrey P.

1992-01-01

Our present design for a common pressure vessel (CPV) battery, a nickel hydrogen battery system to combine all of the cells into a common pressure vessel, uses an open disk which allows the cell to be set into a shallow cavity; subsequent cells are stacked on each other with the total number based on the battery voltage required. This approach not only eliminates the assembly error threat, but also more readily assures equal contact pressure to the heat fin between each cell, which further assures balanced heat transfer. These heat fin dishes with their appropriate cell stacks are held together with tie bars which in turn are connected to the pressure vessel weld rings at each end of the tube.

Modeling Dust Emission of HL Tau Disk Based on Planet-Disk Interactions

DOE PAGES

Jin, Sheng; Li, Shengtai; Isella, Andrea; ...

2016-02-09

In this paper, we use extensive global two-dimensional hydrodynamic disk gas+dust simulations with embedded planets, coupled with three-dimensional radiative transfer calculations, to model the dust ring and gap structures in the HL Tau protoplanetary disk observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). We include the self-gravity of disk gas and dust components and make reasonable choices of disk parameters, assuming an already settled dust distribution and no planet migration. We can obtain quite adequate fits to the observed dust emission using three planets with masses of 0.35, 0.17, and 0.26 M Jup at 13.1, 33.0, and 68.6 AU, respectively.more » Finally, implications for the planet formation as well as the limitations of this scenario are discussed.« less

DiskDetective.org: Finding Homes for Exoplanets Through Citizen Science

NASA Technical Reports Server (NTRS)

Kuchner, Marc J.

2016-01-01

The Disk Detective project is scouring the data archive from the WISE all-sky survey to find new debris disks and protoplanetary disks-the dusty dens where exoplanets form and dwell. Volunteers on this citizen science website have already performed 1.6 million classifications, searching a catalog 8x the size of any published WISE survey. We follow up candidates using ground based telescopes in California, Arizona, Chile, Hawaii, and Argentina. We ultimately expect to increase the pool of known debris disks by approx. 400 and triple the solid angle in clusters of young stars examined with WISE, providing a unique new catalog of isolated disk stars, key planet-search targets, and candidate advanced extraterrestrial civilizations. Come to this talk to hear the news about our latest dusty discoveries and the trials and the ecstasy of launching a new citizen science project. Please bring your laptop or smartphone if you like!

The Effect of Boron on the Low Cycle Fatigue Behavior of Disk Alloy KM4

NASA Technical Reports Server (NTRS)

Gabb, Timothy; Gayda, John; Sweeney, Joseph

2000-01-01

The durability of powder metallurgy nickel base superalloys employed as compressor and turbine disks is often limited by low cycle fatigue (LCF) crack initiation and crack growth from highly stressed surface locations (corners, holes, etc.). Crack growth induced by dwells at high stresses during aerospace engine operation can be particularly severe. Supersolvus solution heat treatments can be used to produce coarse grain sizes approaching ASTM 6 for improved resistance to dwell fatigue crack growth. However, the coarse grain sizes reduce yield strength, which can lower LCF initiation life. These high temperature heat treatments also can encourage pores to form. In the advanced General Electric disk superalloy KM4, such pores can initiate fatigue cracks that limit LCF initiation life. Hot isostatic pressing (HIP) during the supersolvus solution heat treatment has been shown to improve LCF initiation life in KM4, as the HIP pressure minimizes formation of the pores. Reduction of boron levels in KM4 has also been shown to increase LCF initiation life after a conventional supersolvus heat treatment, again possibly due to effects on the formation tendencies of these pores. However, the effects of reduced boron levels on microstructure, pore characteristics, and LCF failure modes in KM4 still need to be fully quantified. The objective of this study was to determine the effect of boron level on the microstructure, porosity, LCF behavior, and failure modes of supersolvus heat treated KM4.

Manufacture of astroloy turbine disk shapes by hot isostatic pressing, volume 1

NASA Technical Reports Server (NTRS)

Eng, R. D.; Evans, D. J.

1978-01-01

The Materials in Advanced Turbine Engines project was conducted to demonstrate container technology and establish manufacturing procedures for fabricating direct Hot Isostatic Pressing (HIP) of low carbon Astroloy to ultrasonic disk shapes. The HIP processing procedures including powder manufacture and handling, container design and fabrication, and HIP consolidation techniques were established by manufacturing five HIP disks. Based upon dimensional analysis of the first three disks, container technology was refined by modifying container tooling which resulted in closer conformity of the HIP surfaces to the sonic shape. The microstructure, chemistry and mechanical properties of two HIP low carbon Astroloy disks were characterized. One disk was subjected to a ground base experimental engine test, and the results of HIP low carbon Astroloy were analyzed and compared to conventionally forged Waspaloy. The mechanical properties of direct HIP low carbon Astroloy exceeded all property goals and the objectives of reduction in material input weight and reduction in cost were achieved.

Spin Testing of Superalloy Disks With Dual Grain Structure

NASA Technical Reports Server (NTRS)

Hefferman, Tab M.

2006-01-01

This 24-month program was a joint effort between Allison Advanced Development Company (AADC), General Electric Aircraft (GEAE), and NASA Glenn Research Center (GRC). AADC led the disk and spin hardware design and analysis utilizing existing Rolls-Royce turbine disk forging tooling. Testing focused on spin testing four disks: two supplied by GEAE and two by AADC. The two AADC disks were made of Alloy 10, and each was subjected to a different heat treat process: one producing dual microstructure with coarse grain size at the rim and fine grain size at the bore and the other produced single fine grain structure throughout. The purpose of the spin tests was to provide data for evaluation of the impact of dual grain structure on disk overspeed integrity (yielding) and rotor burst criteria. The program culminated with analysis and correlation of the data to current rotor overspeed criteria and advanced criteria required for dual structure disks.

Identifying Likely Disk-hosting M dwarfs with Disk Detective

NASA Astrophysics Data System (ADS)

Silverberg, Steven; Wisniewski, John; Kuchner, Marc J.; Disk Detective Collaboration

2018-01-01

M dwarfs are critical targets for exoplanet searches. Debris disks often provide key information as to the formation and evolution of planetary systems around higher-mass stars, alongside the planet themselves. However, less than 300 M dwarf debris disks are known, despite M dwarfs making up 70% of the local neighborhood. The Disk Detective citizen science project has identified over 6000 new potential disk host stars from the AllWISE catalog over the past three years. Here, we present preliminary results of our search for new disk-hosting M dwarfs in the survey. Based on near-infrared color cuts and fitting stellar models to photometry, we have identified over 500 potential new M dwarf disk hosts, nearly doubling the known number of such systems. In this talk, we present our methodology, and outline our ongoing work to confirm systems as M dwarf disks.

Static Chemistry in Disks or Clouds

NASA Astrophysics Data System (ADS)

Semenov, D.; Wiebe, D.

2006-11-01

This FORTRAN77 code can be used to model static, time-dependent chemistry in ISM and circumstellar disks. Current version is based on the OSU'06 gas-grain astrochemical network with all updates to the reaction rates, and includes surface chemistry from Hasegawa & Herbst (1993) and Hasegawa, Herbst, and Leung (1992). Surface chemistry can be modeled either with the standard rate equation approach or modified rate equation approach (useful in disks). Gas-grain interactions include sticking of neutral molecules to grains, dissociative recombination of ions on grains as well as thermal, UV, X-ray, and CRP-induced desorption of frozen species. An advanced X-ray chemistry and 3 grain sizes with power-law size distribution are also included. An deuterium extension to this chemical model is available.

Nickel extraction from nickel matte

NASA Astrophysics Data System (ADS)

Subagja, R.

2018-01-01

In present work, the results of research activities to make nickel metal from nickel matte are presented. The research activities were covering a) nickel matte characterization using Inductively Couple plasma (ICP), Electron Probe Micro Analyzer (EPMA) and X-Ray Diffraction (XRD), b) nickel matte dissolution process to dissolve nickel from nickel matte into the spent electrolyte solutions that contains hydrochloric acid, c) purification of nickel chloride leach solution by copper cementation process to remove copper using nickel matte, selective precipitation process to remove iron, solvent extraction using Tri normal octyl amine to separate cobalt from nickel chloride solutions and d) Nickel electro winning process to precipitate nickel into the cathode surface from purified nickel chloride solution by using direct current. The research activities created 99, 72 % pure nickel metal as the final product of the process.

A near-infrared imaging survey of interacting galaxies - The disk-disk merger candidates subset

NASA Technical Reports Server (NTRS)

Stanford, S. A.; Bushouse, H. A.

1991-01-01

Near-infrared imaging obtained for systems believed to be advanced disk-disk mergers are presented and discussed. These systems were chosen from a sample of approximately 170 objects from the Arp Atlas of Peculiar Galaxies which have been imaged in the JHK bands as part of an investigation into the stellar component of interacting galaxies. Of the eight remnants which show optical signs of a disk-disk merger, the near-infrared surface brightness profiles are well-fitted by an r exp 1/4 law over all measured radii in four systems, and out to radii of about 3 kpc in three systems. These K band profiles indicate that most of the remnants in the sample either have finished or are in the process of relaxing into a mass distribution like that of normal elliptical galaxies.

Synthesis of bacteria promoted reduced graphene oxide-nickel sulfide networks for advanced supercapacitors.

PubMed

Zhang, Haiming; Yu, Xinzhi; Guo, Di; Qu, Baihua; Zhang, Ming; Li, Qiuhong; Wang, Taihong

2013-08-14

Supercapacitors with potential high power are useful and have attracted much attention recently. Graphene-based composites have been demonstrated to be promising electrode materials for supercapacitors with enhanced properties. To improve the performance of graphene-based composites further and realize their synthesis with large scale, we report a green approach to synthesize bacteria-reduced graphene oxide-nickel sulfide (BGNS) networks. By using Bacillus subtilis as spacers, we deposited reduced graphene oxide/Ni3S2 nanoparticle composites with submillimeter pores directly onto substrate by a binder-free electrostatic spray approach to form BGNS networks. Their electrochemical capacitor performance was evaluated. Compared with stacked reduced graphene oxide-nickel sulfide (GNS) prepared without the aid of bacteria, BGNS with unique nm-μm structure exhibited a higher specific capacitance of about 1424 F g(-1) at a current density of 0.75 A g(-1). About 67.5% of the capacitance was retained as the current density increased from 0.75 to 15 A g(-1). At a current density of 75 A g(-1), a specific capacitance of 406 F g(-1) could still remain. The results indicate that the reduced graphene oxide-nickel sulfide network promoted by bacteria is a promising electrode material for supercapacitors.

The Effect of Stabilization Treatments on Disk Alloy CH98

NASA Technical Reports Server (NTRS)

Gayda, John; Gabb, Timothy P.; Ellis, David L.

2003-01-01

Gas turbine engines for future subsonic transports will probably have higher pressure ratios which will require nickelbase superalloy disks with 1300 to 1400 F temperature capability. Several advanced disk alloys are being developed to fill this need. One of these, CH98, is a promising candidate for gas turbine engines and is being studied in NASA s Advanced Subsonic Technology (AST) program. For large disks, residual stresses generated during quenching from solution heat treatments are often reduced by a stabilization heat treatment, in which the disk is heated to 1500 or 1600 F for several hours followed by a static air cool. The reduction in residual stress levels lessens distortion during machining of disks. However, previous work on CH98 has indicated that stabilization treatments can also decrease creep capability. In this study, a systematic variation of stabilization temperature and time was investigated to determine its effect on 1300 F tensile and, more importantly, creep behavior. Dwell crack growth rates were also measured for selected stabilization conditions. As these advanced disk alloys may be given a supersolvus solution or a subsolvus solution heat treatment for a given application, it was decided that both options would be studied.

Zodiac II: Debris Disk Science from a Balloon

NASA Technical Reports Server (NTRS)

Bryden, Geoffrey; Traub, Wesley; Roberts, Lewis C., Jr.; Bruno, Robin; Unwin, Stephen; Backovsky, Stan; Brugarolas, Paul; Chakrabarti, Supriya; Chen, Pin; Hillenbrand, Lynne;

Zodiac II: Debris Disk Science from a Balloon

NASA Technical Reports Server (NTRS)

Bryden, Geoffrey; Traub, Wesley; Roberts, Lewis C., Jr.; Bruno, Robin; Unwin, Stephen; Backovsky, Stan; Brugarolas, Paul; Chakrabarti, Supriya; Chen, Pin; Hillenbrand, Lynne;

Elevated Temperature Properties of Titanium Carbide Base Ceramals Containing Nickel or Iron

NASA Technical Reports Server (NTRS)

Cooper, A L; Colteryahn, L E

1951-01-01

Elevated-temperature properties of titanium carbide base ceramals containing nickel or iron were determined in oxidation, modulus of rupture, tensile strength, and thermal-shock resistance. These materials followed the general growth law and exhibited two stages in oxidation. The following tensile strengths were found at 2000 degrees F: 13.3 weight percent nickel, 16, 150 pounds per square inch; 11.8 weight percent iron, 12,500 pounds per square inch; unalloyed titanium carbide, 16,450 pounds per square inch. Nickel or iron additions to titanium carbide improved the thermal-shock resistance, nickel more. The path of fracture in tensile and thermal-shock specimens was found to progress approximately 50 percent intergranularly and 50 percent transgranularly.

Removing nickel from nickel-coated carbon fibers

NASA Astrophysics Data System (ADS)

Hardianto, A.; Hertleer, C.; De Mey, G.; Van Langenhove, L.

2017-10-01

Conductive fibers/yarns are one of the most important materials for smart textiles because of their electrically conductive functionality combined with flexibility and light weight. They can be applied in many fields such as the medical sector, electronics, sensors and even as thermoelectric generators. Temperature sensors, for example, can be made using the thermocouple or thermopile principle which usually uses two different metal wires that can produce a temperature-dependent voltage. However, if metal wires are inserted into a textile structure, they will decrease the flexibility properties of the textile product. Nickel-coated Carbon Fiber (NiCF), a conductive textile yarn, has a potential use as a textile-based thermopile if we can create an alternating region of carbon and nickel along the fiber which in turn it can be used for substituting the metallic thermopile. The idea was to remove nickel from NiCF in order to obtain a yarn that contains alternating zones of carbon and nickel. Due to no literature reporting on how to remove nickel from NiCF, in this paper we investigated some chemicals to remove nickel from NiCF.

Disk storage management for LHCb based on Data Popularity estimator

NASA Astrophysics Data System (ADS)

Hushchyn, Mikhail; Charpentier, Philippe; Ustyuzhanin, Andrey

2015-12-01

This paper presents an algorithm providing recommendations for optimizing the LHCb data storage. The LHCb data storage system is a hybrid system. All datasets are kept as archives on magnetic tapes. The most popular datasets are kept on disks. The algorithm takes the dataset usage history and metadata (size, type, configuration etc.) to generate a recommendation report. This article presents how we use machine learning algorithms to predict future data popularity. Using these predictions it is possible to estimate which datasets should be removed from disk. We use regression algorithms and time series analysis to find the optimal number of replicas for datasets that are kept on disk. Based on the data popularity and the number of replicas optimization, the algorithm minimizes a loss function to find the optimal data distribution. The loss function represents all requirements for data distribution in the data storage system. We demonstrate how our algorithm helps to save disk space and to reduce waiting times for jobs using this data.

An Optical Disk-Based Information Retrieval System.

ERIC Educational Resources Information Center

Bender, Avi

1988-01-01

Discusses a pilot project by the Nuclear Regulatory Commission to apply optical disk technology to the storage and retrieval of documents related to its high level waste management program. Components and features of the microcomputer-based system which provides full-text and image access to documents are described. A sample search is included.…

Vibration Based Crack Detection in a Rotating Disk. Part 2; Experimental Results

NASA Technical Reports Server (NTRS)

Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Martin, Richard E.; Haase, Wayne C.; Baaklini, George

2005-01-01

This paper describes the experimental results concerning the detection of a crack in a rotating disk. The goal was to utilize blade tip clearance and shaft vibration measurements to monitor changes in the system's center of mass and/or blade deformation behaviors. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk's geometry as well as a change in the system's center of mass occurs. Here, a notch was used to simulate an actual crack. The vibration based experimental results failed to identify the existence of a notch when utilizing the approach described above, even with a rather large, circumferential notch (l.2 in.) located approximately mid-span on the disk (disk radius = 4.63 in. with notch at r = 2.12 in.). This was somewhat expected, since the finite element based results in Part 1 of this study predicted changes in blade tip clearance as well as center of mass shifts due to a notch to be less than 0.001 in. Therefore, the small changes incurred by the notch could not be differentiated from the mechanical and electrical noise of the rotor system. Although the crack detection technique of interest failed to identify the existence ofthe notch, the vibration data produced and captured here will be utilized in upcoming studies that will focus on different data mining techniques concerning damage detection in a disk.

Advanced turbine study

NASA Technical Reports Server (NTRS)

Castro, J. H.

1985-01-01

The feasibility of an advanced convective cooling concept applied to rocket turbine airfoils which operate in a high pressure hydrogen and methane environment was investigated. The concept consists of a central structural member in which grooves are machined. The grooves are temporarily filled with a removable filler and the entire airfoil is covered with a layer of electroformed nickel, or nickel base alloy. After removal of the filler, the low thermal resistance of the nickel closure causes the wall temperature to be reduced by heat transfer to the coolant. The program is divided in the following tasks: (1) turbine performance appraisal; (2) coolant geometry evaluation; (3) test hardware design and analysis; and (4) test airfoil fabrication.

Near-Threshold Fatigue Crack Growth Behavior of Fine-Grain Nickel-Based Alloys

NASA Technical Reports Server (NTRS)

Newman, John A.; Piascik, Robert S.

2003-01-01

Constant-Kmax fatigue crack growth tests were performed on two finegrain nickel-base alloys Inconel 718 (DA) and Ren 95 to determine if these alloys exhibit near-threshold time-dependent crack growth behavior observed for fine-grain aluminum alloys in room-temperature laboratory air. Test results showed that increases in K(sub max) values resulted in increased crack growth rates, but no evidence of time-dependent crack growth was observed for either nickel-base alloy at room temperature.

Characteristics of the Plasma Source for Ground Ionosphere Simulation Surveyed by Disk-Type Langmuir Probe

NASA Astrophysics Data System (ADS)

Ryu, Kwangsun; Lee, Junchan; Kim, Songoo; Chung, Taejin; Shin, Goo-Hwan; Cha, Wonho; Min, Kyoungwook; Kim, Vitaly P.

2017-12-01

A space plasma facility has been operated with a back-diffusion-type plasma source installed in a mid-sized vacuum chamber with a diameter of 1.5 m located in Satellite Technology Research Center (SaTReC), Korea Advanced Institute of Science and Technology (KAIST). To generate plasma with a temperature and density similar to the ionospheric plasma, nickel wires coated with carbonate solution were used as filaments that emit thermal electrons, and the accelerated thermal electrons emitted from the heated wires collide with the neutral gas to form plasma inside the chamber. By using a disk-type Langmuir probe installed inside the vacuum chamber, the generation of plasma similar to the space environment was validated. The characteristics of the plasma according to the grid and plate anode voltages were investigated. The grid voltage of the plasma source is realized as a suitable parameter for manipulating the electron density, while the plate voltage is suitable for adjusting the electron temperature. A simple physical model based on the collision cross-section of electron impact on nitrogen molecule was established to explain the plasma generation mechanism.

Recrystallization characteristics of oxide dispersion strengthened nickel-base alloys

NASA Technical Reports Server (NTRS)

Hotzler, R. K.; Glasgow, T. K.

1980-01-01

Electron microscopy was employed to study the process of recrystallization in two oxide dispersion strengthened (ODS) mechanically alloyed nickel-base alloys, MA 754 and MA 6000E. MA 754 contained both fine, uniformly dispersed particles and coarser oxides aligned along the working direction. Hot rolled MA 754 had a grain size of 0.5 microns and high dislocation densities. After partial primary recrystallization, the fine grains transformed to large elongated grains via secondary (or abnormal) grain growth. Extruded and rolled MA 6000E contained equiaxed grains of 0.2 micron diameter. Primary recrystallization occurring during working eliminated virtually all dislocations. Conversion from fine to coarse grains was triggered by gamma prime dissolution; this was also a process of secondary or abnormal grain growth. Comparisons were made to conventional and oxide dispersion strengthened nickel-base alloys.

Evaluation of coatings for cobalt- and nickel-base superalloys, volume 2

NASA Technical Reports Server (NTRS)

Moore, V. S.; Brentnall, W. D.; Stetson, A. R.

1970-01-01

The final results of an oxidation-reduction rig evaluation of aluminide coatings are presented, as applied to 1N-100 and B1900 nickel-base and X-10 and WI-52 cobalt-base alloys. Burner rigs were used which operated on JP-5 fuel and air, producing a gas velocity of 0.85 (2000 to 2500 ft/sec) at the specimen's leading edge. One-hour heating cycles were used with three minutes of air blast cooling. Results of testing at temperatures ranging from T sub max of 1850 to 2050 F indicate that coated B1900 has the longest oxidation life at all temperatures, followed by IN-100X-40WI-52, based on a weight change criterion. Coatings on nickel-base alloys provided more than twice the life of coating on cobalt-base alloys at comparable temperatures. The coatings with higher aluminum content and comparable thickness had longer lives. Silicon appeared to be a beneficial additive in the nickel-base alloy coatings for long term, low temperature life, but not for short term, high temperature performance. Chromium was identified in all coatings. Extrapolating the life results obtained to 1600 F, all the selected coatings on the four alloys would be protective for at least 10,000 hours.

MEMS-based wide-bandwidth electromagnetic energy harvester with electroplated nickel structure

NASA Astrophysics Data System (ADS)

Sun, Shi; Dai, Xuhan; Sun, Yunna; Xiang, Xiaojian; Ding, Guifu; Zhao, Xiaolin

2017-11-01

A novel nickel-based nonlinear electromagnetic energy harvester has been designed, fabricated, and characterized in this work. Electroplated nickel is very suitable for a stretching-based mechanism to broaden the bandwidth due to its good process and mechanical properties. A strong hardening nonlinearity is induced due to the large deformation of the thin nickel based guided-beam structure. Combining the merits of both the mechanical properties and guided-beam structure, the energy harvester shows good bandwidth performance. It is found that increasing the thickness of the central platform could guarantee nonlinearity. Static and dynamic models of the energy harvester are simulated and validated. Test results show that the energy harvester has good repeatability without any destruction under a large deformation condition. At the acceleration of 0.5 g, comparative large bandwidths of 129 and 59 Hz are obtained for displacement and RMS output voltage, respectively. Power output of 3.4 µW and normalized power density of 125.92 µW cm-3 g-2 are achieved with the load resistance of 38 Ω.

The elemental move characteristic of nickel-based alloy in molten salt corrosion by using nuclear microprobe

NASA Astrophysics Data System (ADS)

Lei, Qiantao; Liu, Ke; Gao, Jie; Li, Xiaolin; Shen, Hao; Li, Yan

2017-08-01

Nickel-based alloys as candidate materials for Thorium Molten Salt Reactor (TMSR), need to be used under high temperature in molten salt environment. In order to ensure the safety of the reactor running, it is necessary to study the elemental move characteristic of nickel-based alloys in the high temperature molten salts. In this work, the scanning nuclear microprobe at Fudan University was applied to study the elemental move. The Nickel-based alloy samples were corroded by molten salt at different temperatures. The element concentrations in the Nickel-based alloys samples were determined by the scanning nuclear microprobe. Micro-PIXE results showed that the element concentrations changed from the interior to the exterior of the alloy samples after the corrosion.

Deep eutectic solvent approach towards nickel/nickel nitride nanocomposites

DOE PAGES

Gage, Samuel H.; Ruddy, Daniel A.; Pylypenko, Svitlana; ...

2016-12-15

Nickel nitride is an attractive material for a broad range of applications including catalysis. However preparations and especially those targeting nanoscale particles remain a major challenge. Herein, we report a wet-chemical approach to produce nickel/nickel nitride nanocomposites using deep eutectic solvents. A choline chloride/urea deep eutectic solvent was used as a reaction medium to form gels containing nickel acetate tetrahydrate. Heat treatment of the gel in inert atmosphere forms nanoparticles embedded within a nitrogen-doped carbon matrix. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to understand the decomposition profile of the precursors and to select pyrolysis temperatures locatedmore » in regions of thermal stability. X-ray diffraction (XRD) confirmed the presence of metallic nickel, whereas X-ray photoelectron spectroscopy (XPS) suggested the existence of a nickel nitride surface layer. According to transmission electron microscopy (TEM) analysis these mixed phase, possibly core-shell type nanoparticles, have very defined facets. Furthermore, these materials represent a unique opportunity to tune catalytic properties of nickel-based catalysts through control of their composition, surface structure, and morphology; in addition to employing potential benefits of a nitrogen-doped carbon support.« less

An optical disk archive for a data base management system

NASA Technical Reports Server (NTRS)

Thomas, Douglas T.

1985-01-01

An overview is given of a data base management system that can catalog and archive data at rates up to 50M bits/sec. Emphasis is on the laser disk system that is used for the archive. All key components in the system (3 Vax 11/780s, a SEL 32/2750, a high speed communication interface, and the optical disk) are interfaced to a 100M bits/sec 16-port fiber optic bus to achieve the high data rates. The basic data unit is an autonomous data packet. Each packet contains a primary and secondary header and can be up to a million bits in length. The data packets are recorded on the optical disk at the same time the packet headers are being used by the relational data base management software ORACLE to create a directory independent of the packet recording process. The user then interfaces to the VAX that contains the directory for a quick-look scan or retrieval of the packet(s). The total system functions are distributed between the VAX and the SEL. The optical disk unit records the data with an argon laser at 100M bits/sec from its buffer, which is interfaced to the fiber optic bus. The same laser is used in the read cycle by reducing the laser power. Additional information is given in the form of outlines, charts, and diagrams.

MEANS 2: Microstructure- and Micromechanism-Sensitive Property Models for Advanced Turbine Disk and Blade Systems

DTIC Science & Technology

2009-12-31

f„„„,„ -L...-J..— - —I 1 / f+_—=p / —j \\-\\- 4A 14 4A»4 / 4A C4 M / »4.4C A4, «i »A OWOLC $-ISF s - csr !•» ’ML...Materials Society) Publications. 23. S . Ma, L. Carroll and T.M. Pollock, "Development of y Phase Stacking Faults during High Temperature Creep of Ru...into the design of advanced disk and blade systems 6. AUTHOR( S ) Michael J Mills 5. FUNDING NUMBERS FA9550-05-1-0135 7. PERFORMING ORGANIZATION

Advanced nickel-hydrogen cell configuration study

NASA Technical Reports Server (NTRS)

Adler, E.; Perez, F.

1984-01-01

Three nickel hydrogen battery designs, individual pressure vessel (IPV), common pressure vessel (CPV), and a bipolar battery module were studied. Weight, system complexity and cost were compared for a satellite operating in a 6 hour, 5600 nautical mile orbit. The required energy storage is 52 kWh. A 25% improvement in specific energy is observed by employing a bipolar battery versus a battery comprised of hundreds of IPV's. Further weight benefits are realized by the development of light weight technologies in the bipolar design.

Practical and Secure Recovery of Disk Encryption Key Using Smart Cards

NASA Astrophysics Data System (ADS)

Omote, Kazumasa; Kato, Kazuhiko

In key-recovery methods using smart cards, a user can recover the disk encryption key in cooperation with the system administrator, even if the user has lost the smart card including the disk encryption key. However, the disk encryption key is known to the system administrator in advance in most key-recovery methods. Hence user's disk data may be read by the system administrator. Furthermore, if the disk encryption key is not known to the system administrator in advance, it is difficult to achieve a key authentication. In this paper, we propose a scheme which enables to recover the disk encryption key when the user's smart card is lost. In our scheme, the disk encryption key is not preserved anywhere and then the system administrator cannot know the key before key-recovery phase. Only someone who has a user's smart card and knows the user's password can decrypt that user's disk data. Furthermore, we measured the processing time required for user authentication in an experimental environment using a virtual machine monitor. As a result, we found that this processing time is short enough to be practical.

Microstructural study of the nickel-base alloy WAZ-20 using qualitative and quantitative electron optical techniques

NASA Technical Reports Server (NTRS)

Young, S. G.

1973-01-01

The NASA nickel-base alloy WAZ-20 was analyzed by advanced metallographic techniques to qualitatively and quantitatively characterize its phases and stability. The as-cast alloy contained primary gamma-prime, a coarse gamma-gamma prime eutectic, a gamma-fine gamma prime matrix, and MC carbides. A specimen aged at 870 C for 1000 hours contained these same constituents and a few widely scattered high W particles. No detrimental phases (such as sigma or mu) were observed. Scanning electron microscope, light metallography, and replica electron microscope methods are compared. The value of quantitative electron microprobe techniques such as spot and area analysis is demonstrated.

High gas velocity oxidation and hot corrosion testing of oxide dispersion-strengthened nickel-base alloys

NASA Technical Reports Server (NTRS)

Deadmore, D. L.; Lowell, C. E.

1975-01-01

Several oxide dispersion strengthened (ODS) nickel-base alloys were tested in high velocity gases for cyclic oxidation resistance at temperatures to 1200 C and times to 500 hours and for hot corrosion resistance at 900 C for 200 hours. Nickel-chromium-aluminum ODS alloys were found to have superior resistance to oxidation and hot corrosion when compared to bare and coated nickel-chromium ODS alloys. The best of the alloys tested had compositions of nickel - 15.5 to 16 weight percent chromium with aluminum weight percents between 4.5 and 5.0. All of the nickel-chromium-aluminum ODS materials experienced small weight losses (less than 16 mg/sq cm).

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen flight cells. An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

Validation testing of the NASA Lewis 125 Ah advanced design individual pressure vessel (IPV) nickel-hydrogen flight cells was conducted. Work consisted of characterization, storage, and cycle life testing. There was no capacity degradation after 52 days of storage with the cells in the discharged state, an open circuit, 0 C, and a hydrogen pressure of 14.5 psia. The catalyzed wall wick cells were cycled for over 11,000 cycles with no cell failures in the continuing test. One of the noncatalyzed wall wick cells failed.

Additive Manufacturing of Nickel-Base Superalloy IN100 Through Scanning Laser Epitaxy

NASA Astrophysics Data System (ADS)

Basak, Amrita; Das, Suman

2018-01-01

Scanning laser epitaxy (SLE) is a laser powder bed fusion (LPBF)-based additive manufacturing process that uses a high-power laser to consolidate metal powders facilitating the fabrication of three-dimensional objects. In the present study, SLE is used to produce samples of IN100, a high-γ' non-weldable nickel-base superalloy on similar chemistry substrates. A thorough analysis is performed using various advanced material characterization techniques such as high-resolution optical microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and Vickers microhardness measurements to characterize and compare the quality of the SLE-fabricated IN100 deposits with the investment cast IN100 substrates. The results show that the IN100 deposits have a finer γ/γ' microstructure, weaker elemental segregation, and higher microhardness compared with the substrate. Through this study, it is demonstrated that the SLE process has tremendous potential in the repair and manufacture of gas turbine hot-section components.

Redundant disk arrays: Reliable, parallel secondary storage. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Gibson, Garth Alan

1990-01-01

During the past decade, advances in processor and memory technology have given rise to increases in computational performance that far outstrip increases in the performance of secondary storage technology. Coupled with emerging small-disk technology, disk arrays provide the cost, volume, and capacity of current disk subsystems, by leveraging parallelism, many times their performance. Unfortunately, arrays of small disks may have much higher failure rates than the single large disks they replace. Redundant arrays of inexpensive disks (RAID) use simple redundancy schemes to provide high data reliability. The data encoding, performance, and reliability of redundant disk arrays are investigated. Organizing redundant data into a disk array is treated as a coding problem. Among alternatives examined, codes as simple as parity are shown to effectively correct single, self-identifying disk failures.

Design and implementation of reliability evaluation of SAS hard disk based on RAID card

NASA Astrophysics Data System (ADS)

Ren, Shaohua; Han, Sen

2015-10-01

Because of the huge advantage of RAID technology in storage, it has been widely used. However, the question associated with this technology is that the hard disk based on the RAID card can not be queried by Operating System. Therefore how to read the self-information and log data of hard disk has been a problem, while this data is necessary for reliability test of hard disk. In traditional way, this information can be read just suitable for SATA hard disk, but not for SAS hard disk. In this paper, we provide a method by using LSI RAID card's Application Program Interface, communicating with RAID card and analyzing the feedback data to solve the problem. Then we will get the necessary information to assess the SAS hard disk.

Fabrication technology of CNT-Nickel Oxide based planar pseudocapacitor for MEMS and NEMS

NASA Astrophysics Data System (ADS)

Lebedev, E. A.; Kitsyuk, E. P.; Gavrilin, I. M.; Gromov, D. G.; Gruzdev, N. E.; Gavrilov, S. A.; Dronov, A. A.; Pavlov, A. A.

2015-11-01

Fabrication technology of planar pseudocapacitor (PsC) based on carbon nanotube (CNT) forest, synthesized using plasma enhanced chemical vapor deposition (PECVD) method, covered with thin nickel oxide layer deposited by successive ionic layer adsorption and reaction (SILAR) method, is demonstrated. Dependences of deposited oxide layers thickness on device specific capacities is studied. It is shown that pseudocapacity of nickel oxide thin layer increases specific capacity of the CNT's based device up to 2.5 times.

Characterization of Carbon Nanotube Reinforced Nickel

NASA Technical Reports Server (NTRS)

Gill, Hansel; Hudson, Steve; Bhat, Biliyar; Munafo, Paul M. (Technical Monitor)

2002-01-01

Carbon nanotubes are cylindrical molecules composed of carbon atoms in a regular hexagonal arrangement. If nanotubes can be uniformly dispersed in a supporting matrix to form structural materials, the resulting structures could be significantly lighter and stronger than current aerospace materials. Work is currently being done to develop an electrolyte-based self-assembly process that produces a Carbon Nanotube/Nickel composite material with high specific strength. This process is expected to produce a lightweight metal matrix composite material, which maintains it's thermal and electrical conductivities, and is potentially suitable for applications such as advanced structures, space based optics, and cryogenic tanks.

A new solid-phase extraction disk based on a sheet of single-walled carbon nanotubes.

PubMed

Niu, Hong Yun; Cai, Ya Qi; Shi, Ya Li; Wei, Fu Sheng; Liu, Jie Min; Jiang, Gui Bin

2008-11-01

A new kind of solid-phase extraction disk based on a sheet of single-walled carbon nanotubes (SWCNTs) is developed in this study. The properties of such disks are tested, and different disks showed satisfactory reproducibility. One liter of aqueous solution can pass through the disk within 10-100 min while still allowing good recoveries. Two disks (DD-disk) can be stacked to enrich phthalate esters, bisphenol A (BPA), 4-n-nonylphenol (4-NP), 4-tert-octylphenol (4-OP) and chlorophenols from various volumes of solution. The results show that SWCNT disks have high extraction ability for all analytes. The SWCNT disk can extract polar chlorophenols more efficiently than a C(18) disk from water solution. Unlike the activated carbon disk, analytes adsorbed by the new disks can be eluted completely with 8-15 mL of methanol or acetonitrile. Finally, the DD-disk system is used to pretreat 1000-mL real-world water samples spiked with BPA, 4-OP and 4-NP. Detection limits of 7, 25, and 38 ng L(-1) for BPA, 4-OP, and 4-NP, respectively, were achieved under optimized conditions. The advantages of this new disk include its strong adsorption ability, its high flow rate and its easy preparation.

Spiral density waves in a young protoplanetary disk.

PubMed

Pérez, Laura M; Carpenter, John M; Andrews, Sean M; Ricci, Luca; Isella, Andrea; Linz, Hendrik; Sargent, Anneila I; Wilner, David J; Henning, Thomas; Deller, Adam T; Chandler, Claire J; Dullemond, Cornelis P; Lazio, Joseph; Menten, Karl M; Corder, Stuartt A; Storm, Shaye; Testi, Leonardo; Tazzari, Marco; Kwon, Woojin; Calvet, Nuria; Greaves, Jane S; Harris, Robert J; Mundy, Lee G

2016-09-30

Gravitational forces are expected to excite spiral density waves in protoplanetary disks, disks of gas and dust orbiting young stars. However, previous observations that showed spiral structure were not able to probe disk midplanes, where most of the mass is concentrated and where planet formation takes place. Using the Atacama Large Millimeter/submillimeter Array, we detected a pair of trailing symmetric spiral arms in the protoplanetary disk surrounding the young star Elias 2-27. The arms extend to the disk outer regions and can be traced down to the midplane. These millimeter-wave observations also reveal an emission gap closer to the star than the spiral arms. We argue that the observed spirals trace shocks of spiral density waves in the midplane of this young disk. Copyright © 2016, American Association for the Advancement of Science.

Advanced intermediate temperature sodium-nickel chloride batteries with ultra-high energy density

NASA Astrophysics Data System (ADS)

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y.; Meinhardt, Kerry D.; Chang, Hee Jung; Canfield, Nathan L.; Sprenkle, Vincent L.

2016-02-01

Sodium-metal halide batteries have been considered as one of the more attractive technologies for stationary electrical energy storage, however, they are not used for broader applications despite their relatively well-known redox system. One of the roadblocks hindering market penetration is the high-operating temperature. Here we demonstrate that planar sodium-nickel chloride batteries can be operated at an intermediate temperature of 190 °C with ultra-high energy density. A specific energy density of 350 Wh kg-1, higher than that of conventional tubular sodium-nickel chloride batteries (280 °C), is obtained for planar sodium-nickel chloride batteries operated at 190 °C over a long-term cell test (1,000 cycles), and it attributed to the slower particle growth of the cathode materials at the lower operating temperature. Results reported here demonstrate that planar sodium-nickel chloride batteries operated at an intermediate temperature could greatly benefit this traditional energy storage technology by improving battery energy density, cycle life and reducing material costs.

The strainrange partitioning behavior of an advanced gas turbine disk alloy, AF2-1DA

NASA Technical Reports Server (NTRS)

Halford, G. R.; Nachtigall, A. J.

1979-01-01

The low-cycle, creep-fatigue characteristics of the advanced gas turbine disk alloy, AF2-1DA have been determined at 1400 F and are presented in terms of the method of strainrange partitioning (SRP). The mean stresses which develop in the PC and CP type SRP cycles at the lowest inelastic strainrange were observed to influence the cyclic lives to a greater extent than the creep effects and hence interfered with a conventional interpretation of the results by SRP. A procedure is proposed for dealing with the mean stress effects on life which is compatible with SRP.

Disk-loss and disk-renewal phases in classical Be stars. II. Contrasting with stable and variable disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Draper, Zachary H.; Wisniewski, John P.; Bjorkman, Karen S.

2014-05-10

Recent observational and theoretical studies of classical Be stars have established the utility of polarization color diagrams (PCDs) in helping to constrain the time-dependent mass decretion rates of these systems. We expand on our pilot observational study of this phenomenon, and report the detailed analysis of a long-term (1989-2004) spectropolarimetric survey of nine additional classical Be stars, including systems exhibiting evidence of partial disk-loss/disk-growth episodes as well as systems exhibiting long-term stable disks. After carefully characterizing and removing the interstellar polarization along the line of sight to each of these targets, we analyze their intrinsic polarization behavior. We find thatmore » many steady-state Be disks pause at the top of the PCD, as predicted by theory. We also observe sharp declines in the Balmer jump polarization for later spectral type, near edge-on steady-state disks, again as recently predicted by theory, likely caused when the base density of the disk is very high, and the outer region of the edge-on disk starts to self absorb a significant number of Balmer jump photons. The intrinsic V-band polarization and polarization position angle of γ Cas exhibits variations that seem to phase with the orbital period of a known one-armed density structure in this disk, similar to the theoretical predictions of Halonen and Jones. We also observe stochastic jumps in the intrinsic polarization across the Balmer jump of several known Be+sdO systems, and speculate that the thermal inflation of part of the outer region of these disks could be responsible for producing this observational phenomenon. Finally, we estimate the base densities of this sample of stars to be between ≈8 × 10{sup –11} and ≈4 × 10{sup –12} g cm{sup –3} during quasi steady state periods given there maximum observed polarization.« less

Laser illuminator and optical system for disk patterning

DOEpatents

Hackel, Lloyd A.; Dane, C. Brent; Dixit, Shamasundar N.; Everett, Mathew; Honig, John

2000-01-01

Magnetic recording media are textured over areas designated for contact in order to minimize friction with data transducing heads. In fabricating a hard disk, an aluminum nickel-phosphorous substrate is polished to a specular finish. A mechanical means is then used to roughen an annular area intended to be the head contact band. An optical and mechanical system allows thousands of spots to be generated with each laser pulse, allowing the textured pattern to be rapidly generated with a low repetition rate laser and an uncomplicated mechanical system. The system uses a low power laser, a beam expander, a specially designed phase plate, a prism to deflect the beam, a lens to transmit the diffraction pattern to the far field, a mechanical means to rotate the pattern and a trigger system to fire the laser when sections of the pattern are precisely aligned. The system generates an annular segment of the desired pattern with which the total pattern is generated by rotating the optical system about its optic axis, sensing the rotational position and firing the laser as the annular segment rotates into the next appropriate position. This marking system can be integrated into a disk sputtering system for manufacturing magnetic disks, allowing for a very streamlined manufacturing process.

Protoplanetary Disks as (Possibly) Viscous Disks

NASA Astrophysics Data System (ADS)

Rafikov, Roman R.

2017-03-01

Protoplanetary disks are believed to evolve on megayear timescales in a diffusive (viscous) manner as a result of angular momentum transport driven by internal stresses. Here we use a sample of 26 protoplanetary disks resolved by ALMA with measured (dust-based) masses and stellar accretion rates to derive the dimensionless α-viscosity values for individual objects, with the goal of constraining the angular momentum transport mechanism. We find that the inferred values of α do not cluster around a single value, but instead have a broad distribution extending from 10-4 to 0.04. Moreover, they correlate with neither the global disk parameters (mass, size, surface density) nor the stellar characteristics (mass, luminosity, radius). However, we do find a strong linear correlation between α and the central mass accretion rate \\dot{M}. This correlation is unlikely to result from the direct physical effect of \\dot{M} on internal stress on global scales. Instead, we suggest that it is caused by the decoupling of stellar \\dot{M} from the global disk characteristics in one of the following ways: (1) The behavior (and range) of α is controlled by a yet-unidentified parameter (e.g., ionization fraction, magnetic field strength, or geometry), ultimately driving the variation of \\dot{M}. (2) The central \\dot{M} is decoupled from the global accretion rate as a result of an instability, or mass accumulation (or loss in a wind or planetary accretion) in the inner disk. (3) Perhaps the most intriguing possibility is that angular momentum in protoplanetary disks is transported nonviscously, e.g., via magnetohydrodynamic winds or spiral density waves.

Oxidation and the Effects of High Temperature Exposures on Notched Fatigue Life of an Advanced Powder Metallurgy Disk Superalloy

NASA Technical Reports Server (NTRS)

Sudbrack, Chantal K.; Draper, Susan L.; Gorman, Timothy T.; Telesman, Jack; Gab, Timothy P.; Hull, David R.

2012-01-01

Oxidation and the effects of high temperature exposures on notched fatigue life were considered for a powder metallurgy processed supersolvus heat-treated ME3 disk superalloy. The isothermal static oxidation response at 704 C, 760 C, and 815 C was consistent with other chromia forming nickel-based superalloys: a TiO2-Cr2O3 external oxide formed with a branched Al2O3 internal subscale that extended into a recrystallized - dissolution layer. These surface changes can potentially impact disk durability, making layer growth rates important. Growth of the external scales and dissolution layers followed a cubic rate law, while Al2O3 subscales followed a parabolic rate law. Cr- rich M23C6 carbides at the grain boundaries dissolved to help sustain Cr2O3 growth to depths about 12 times thicker than the scale. The effect of prior exposures was examined through notched low cycle fatigue tests performed to failure in air at 704 C. Prior exposures led to pronounced debits of up to 99 % in fatigue life, where fatigue life decreased inversely with exposure time. Exposures that produced roughly equivalent 1 m thick external scales at the various isotherms showed statistically equivalent fatigue lives, establishing that surface damage drives fatigue debit, not exposure temperature. Fractographic evaluation indicated the failure mode for the pre-exposed specimens involved surface crack initiations that shifted with exposure from predominately single intergranular initiations with transgranular propagation to multi-initiations from the cracked external oxide with intergranular propagation. Weakened grain boundaries at the surface resulting from the M23C6 carbide dissolution are partially responsible for the intergranular cracking. Removing the scale and subscale while leaving a layer where M23C6 carbides were dissolved did not lead to a significant fatigue life improvement, however, also removing the M23C6 carbide dissolution layer led to nearly full recovery of life, with a

Vibration-Based Data Used to Detect Cracks in Rotating Disks

NASA Technical Reports Server (NTRS)

Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Martin, Richard E.; Baaklini, George Y.

2004-01-01

Rotor health monitoring and online damage detection are increasingly gaining the interest of aircraft engine manufacturers. This is primarily due to the fact that there is a necessity for improved safety during operation as well as a need for lower maintenance costs. Applied techniques for the damage detection and health monitoring of rotors are essential for engine safety, reliability, and life prediction. Recently, the United States set the ambitious goal of reducing the fatal accident rate for commercial aviation by 80 percent within 10 years. In turn, NASA, in collaboration with the Federal Aviation Administration, other Federal agencies, universities, and the airline and aircraft industries, responded by developing the Aviation Safety Program. This program provides research and technology products needed to help the aerospace industry achieve their aviation safety goal. The Nondestructive Evaluation (NDE) Group of the Optical Instrumentation Technology Branch at the NASA Glenn Research Center is currently developing propulsion-system-specific technologies to detect damage prior to catastrophe under the propulsion health management task. Currently, the NDE group is assessing the feasibility of utilizing real-time vibration data to detect cracks in turbine disks. The data are obtained from radial blade-tip clearance and shaft-clearance measurements made using capacitive or eddy-current probes. The concept is based on the fact that disk cracks distort the strain field within the component. This, in turn, causes a small deformation in the disk's geometry as well as a possible change in the system's center of mass. The geometric change and the center of mass shift can be indirectly characterized by monitoring the amplitude and phase of the first harmonic (i.e., the 1 component) of the vibration data. Spin pit experiments and full-scale engine tests have been conducted while monitoring for crack growth with this detection methodology. Even so, published data are

Intermetallic nickel silicide nanocatalyst—A non-noble metal–based general hydrogenation catalyst

PubMed Central

Pohl, Marga-Martina; Agapova, Anastasiya

2018-01-01

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO2 as the silicon atom source. The process involves thermal reduction of Si–O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon–carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal–based catalysts. PMID:29888329

Intermetallic nickel silicide nanocatalyst-A non-noble metal-based general hydrogenation catalyst.

PubMed

Ryabchuk, Pavel; Agostini, Giovanni; Pohl, Marga-Martina; Lund, Henrik; Agapova, Anastasiya; Junge, Henrik; Junge, Kathrin; Beller, Matthias

2018-06-01

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO 2 as the silicon atom source. The process involves thermal reduction of Si-O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon-carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H 2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal-based catalysts.

Nickel-Hydrogen Batteries - An Overview

NASA Technical Reports Server (NTRS)

Smithrick, John J.; ODonnell, Patricia M.

1996-01-01

This article on nickel-hydrogen batteries is an overview of the various nickel-hydrogen battery design options, technical accomplishments, validation test results, and trends. There is more than one nickel-hydrogen battery design, each having its advantage for specific applications. The major battery designs are Individual Pressure Vessel (IPV), Common Pressure Vessel (CPV), bipolar, and low-pressure metal hydride. State-of-the-art nickel-hydrogen batteries are replacing nickel-cadmium batteries in almost all geosynchronous Earth orbit applications requiring power above 1 kW. However, for the more severe Low-Earth Orbit (LEO) applications (greater than 30,000 cycles), the current cycle life of 4000-10,000 cycles at 60 - 80 % DOD should be improved. A NASA Lewis Research Center innovative advanced design IPV nickel-hydrogen cell led to a breakthrough in cycle life enabling LEO applications at deep Depths of Discharge (DOD). A trend for some future satellites is to increase the power level to greater than 6 kW. Another trend is to decrease the power to less than 1 kW for small low-cost satellites. Hence, the challenge is to reduce battery mass, volume, and cost. A key is to develop a lightweight nickel electrode and alternate battery designs. A CPV nickel-hydrogen battery is emerging as a viable alternative to the IPV design. It has the advantage of reduced mass, volume, and manufacturing costs. A 10-A-h CPV battery has successfully provided power on the relatively short-lived Clementine spacecraft. A bipolar nickel -hydrogen battery design has been demonstrated (15,000 LEO cycles, 40 % DOD). The advantage is also a significant reduction in volume, a modest reduction in mass, and like most bipolar designs, features a high-pulse power capability. A low-pressure aerospace nickel-metal-hydride battery cell has been developed and is on the market. It is a prismatic design that has the advantage of a significant reduction in volume and a reduction in manufacturing cost.

Nickel hydrogen batteries: An overview

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Odonnell, Patricia M.

1994-01-01

This paper on nickel hydrogen batteries is an overview of the various nickel hydrogen battery design options, technical accomplishments, validation test results and trends. There is more than one nickel hydrogen battery design, each having its advantage for specific applications. The major battery designs are individual pressure vessel (IPV), common pressure vessel (CPV), bipolar and low pressure metal hydride. State-of-the-art (SOA) nickel hydrogen batteries are replacing nickel cadmium batteries in almost all geosynchronous orbit (GEO) applications requiring power above 1 kW. However, for the more severe low earth orbit (LEO) applications (greater than 30,000 cycles), the current cycle life of 4000 to 10,000 cycles at 60 percent DOD should be improved. A LeRC innovative advanced design IPV nickel hydrogen cell led to a breakthrough in cycle life enabling LEO applications at deep depths of discharge (DOD). A trend for some future satellites is to increase the power level to greater than 6 kW. Another trend is to decrease the power to less than 1 kW for small low cost satellites. Hence, the challenge is to reduce battery mass,volume, and cost. A key is to develop a light weight nickel electrode and alternate battery designs. A common pressure vessel (CPV) nickel hydrogen battery is emerging as a viable alternative to the IPV design. It has the advantage of reduced mass, volume and manufacturing costs. A 10 Ah CPV battery has successfully provided power on the relatively short lived Clementine Spacecraft. A bipolar nickel hydrogen battery design has been demonstrated (15,000 LEO cycles, 40 percent DOD). The advantage is also a significant reduction in volume, a modest reduction in mass, and like most bipolar designs, features a high pulse power capability. A low pressure aerospace nickel metal hydride battery cell has been developed and is on the market. It is a prismatic design which has the advantage of a significant reduction in volume and a reduction in

Advanced intermediate temperature sodium-nickel chloride batteries with ultra-high energy density.

PubMed

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y; Meinhardt, Kerry D; Chang, Hee Jung; Canfield, Nathan L; Sprenkle, Vincent L

2016-02-11

Sodium-metal halide batteries have been considered as one of the more attractive technologies for stationary electrical energy storage, however, they are not used for broader applications despite their relatively well-known redox system. One of the roadblocks hindering market penetration is the high-operating temperature. Here we demonstrate that planar sodium-nickel chloride batteries can be operated at an intermediate temperature of 190 °C with ultra-high energy density. A specific energy density of 350 Wh kg(-1), higher than that of conventional tubular sodium-nickel chloride batteries (280 °C), is obtained for planar sodium-nickel chloride batteries operated at 190 °C over a long-term cell test (1,000 cycles), and it attributed to the slower particle growth of the cathode materials at the lower operating temperature. Results reported here demonstrate that planar sodium-nickel chloride batteries operated at an intermediate temperature could greatly benefit this traditional energy storage technology by improving battery energy density, cycle life and reducing material costs.

Advanced intermediate temperature sodium–nickel chloride batteries with ultra-high energy density

PubMed Central

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y.; Meinhardt, Kerry D.; Chang, Hee Jung; Canfield, Nathan L.; Sprenkle, Vincent L.

2016-01-01

Sodium-metal halide batteries have been considered as one of the more attractive technologies for stationary electrical energy storage, however, they are not used for broader applications despite their relatively well-known redox system. One of the roadblocks hindering market penetration is the high-operating temperature. Here we demonstrate that planar sodium–nickel chloride batteries can be operated at an intermediate temperature of 190 °C with ultra-high energy density. A specific energy density of 350 Wh kg−1, higher than that of conventional tubular sodium–nickel chloride batteries (280 °C), is obtained for planar sodium–nickel chloride batteries operated at 190 °C over a long-term cell test (1,000 cycles), and it attributed to the slower particle growth of the cathode materials at the lower operating temperature. Results reported here demonstrate that planar sodium–nickel chloride batteries operated at an intermediate temperature could greatly benefit this traditional energy storage technology by improving battery energy density, cycle life and reducing material costs. PMID:26864635

The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

NASA Technical Reports Server (NTRS)

Harf, F. H.

1985-01-01

Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of gamma-prime particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the finest gamma-prime particles, and had the lowest gamma-gamma-prime lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650 gamma C, the rupture lives at 650 and 760 C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the gamma-prime particle size distribution and the gamma-gamma-prime mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

Phase Stability of a Powder Metallurgy Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, John; Kantzos, P.; Telesman, Jack; Gang, Anita

2006-01-01

Advanced powder metallurgy superalloy disks in aerospace turbine engines now entering service can be exposed to temperatures approaching 700 C, higher than those previously encountered. They also have higher levels of refractory elements, which can increase mechanical properties at these temperatures but can also encourage phase instabilities during service. Microstructural changes including precipitation of topological close pack phase precipitation and coarsening of existing gamma' precipitates can be slow at these temperatures, yet potentially significant for anticipated disk service times exceeding 1,000 h. The ability to quantify and predict such potential phase instabilities and degradation of capabilities is needed to insure structural integrity and air worthiness of propulsion systems over the full life cycle. A prototypical advanced disk superalloy was subjected to high temperature exposures, and then evaluated. Microstructural changes and corresponding changes in mechanical properties were quantified. The results will be compared to predictions of microstructure modeling software.

Towards a Global Evolutionary Model of Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Bai, Xue-Ning

2016-04-01

A global picture of the evolution of protoplanetary disks (PPDs) is key to understanding almost every aspect of planet formation, where standard α-disk models have been continually employed for their simplicity. In the meantime, disk mass loss has been conventionally attributed to photoevaporation, which controls disk dispersal. However, a paradigm shift toward accretion driven by magnetized disk winds has taken place in recent years, thanks to studies of non-ideal magnetohydrodynamic effects in PPDs. I present a framework of global PPD evolution aiming to incorporate these advances, highlighting the role of wind-driven accretion and wind mass loss. Disk evolution is found to be largely dominated by wind-driven processes, and viscous spreading is suppressed. The timescale of disk evolution is controlled primarily by the amount of external magnetic flux threading the disks, and how rapidly the disk loses the flux. Rapid disk dispersal can be achieved if the disk is able to hold most of its magnetic flux during the evolution. In addition, because wind launching requires a sufficient level of ionization at the disk surface (mainly via external far-UV (FUV) radiation), wind kinematics is also affected by the FUV penetration depth and disk geometry. For a typical disk lifetime of a few million years, the disk loses approximately the same amount of mass through the wind as through accretion onto the protostar, and most of the wind mass loss proceeds from the outer disk via a slow wind. Fractional wind mass loss increases with increasing disk lifetime. Significant wind mass loss likely substantially enhances the dust-to-gas mass ratio and promotes planet formation.

Improved turbine disk design to increase reliability of aircraft jet engines

NASA Technical Reports Server (NTRS)

Alver, A. S.; Wong, J. K.

1975-01-01

An analytical study was conducted on a bore entry cooled turbine disk for the first stage of the JT8D-17 high pressure turbine which had the potential to improve disk life over existing design. The disk analysis included the consideration of transient and steady state temperature, blade loading, creep, low cycle fatigue, fracture mechanics and manufacturing flaws. The improvement in life of the bore entry cooled turbine disk was determined by comparing it with the existing disk made of both conventional and advanced (Astroloy) disk materials. The improvement in crack initiation life of the Astroloy bore entry cooled disk is 87% and 67% over the existing disk made of Waspaloy and Astroloy, respectively. Improvement in crack propagation life is 124% over the Waspaloy and 465% over the Astroloy disks. The available kinetic energies of disk fragments calculated for the three disks indicate a lower fragment energy level for the bore entry cooled turbine disk.

Analysis of thermoelectric properties of high-temperature complex alloys of nickel-base, iron-base and cobalt-base groups

NASA Technical Reports Server (NTRS)

Holanda, R.

1984-01-01

The thermoelectric properties alloys of the nickel-base, iron-base, and cobalt-base groups containing from 1% to 25% 106 chromium were compared and correlated with the following material characteristics: atomic percent of the principle alloy constituent; ratio of concentration of two constituents; alloy physical property (electrical resistivity); alloy phase structure (percent precipitate or percent hardener content); alloy electronic structure (electron concentration). For solid-solution-type alloys the most consistent correlation was obtained with electron concentration, for precipitation-hardenable alloys of the nickel-base superalloy group, the thermoelectric potential correlated with hardener content in the alloy structure. For solid-solution-type alloys, no problems were found with thermoelectric stability to 1000; for precipitation-hardenable alloys, thermoelectric stability was dependent on phase stability. The effects of the compositional range of alloy constituents on temperature measurement uncertainty are discussed.

Region-based multi-step optic disk and cup segmentation from color fundus image

NASA Astrophysics Data System (ADS)

Xiao, Di; Lock, Jane; Manresa, Javier Moreno; Vignarajan, Janardhan; Tay-Kearney, Mei-Ling; Kanagasingam, Yogesan

2013-02-01

Retinal optic cup-disk-ratio (CDR) is a one of important indicators of glaucomatous neuropathy. In this paper, we propose a novel multi-step 4-quadrant thresholding method for optic disk segmentation and a multi-step temporal-nasal segmenting method for optic cup segmentation based on blood vessel inpainted HSL lightness images and green images. The performance of the proposed methods was evaluated on a group of color fundus images and compared with the manual outlining results from two experts. Dice scores of detected disk and cup regions between the auto and manual results were computed and compared. Vertical CDRs were also compared among the three results. The preliminary experiment has demonstrated the robustness of the method for automatic optic disk and cup segmentation and its potential value for clinical application.

Investigation of hydrogen evolution activity for the nickel, nickel-molybdenum nickel-graphite composite and nickel-reduced graphene oxide composite coatings

NASA Astrophysics Data System (ADS)

Jinlong, Lv; Tongxiang, Liang; Chen, Wang

2016-03-01

The nickel, nickel-molybdenum alloy, nickel-graphite and nickel-reduced graphene oxide composite coatings were obtained by the electrodeposition technique from a nickel sulfate bath. Nanocrystalline molybdenum, graphite and reduced graphene oxide in nickel coatings promoted hydrogen evolution reaction in 0.5 M H2SO4 solution at room temperature. However, the nickel-reduced graphene oxide composite coating exhibited the highest electrocatalytic activity for the hydrogen evolution reaction in 0.5 M H2SO4 solution at room temperature. A large number of gaps between 'cauliflower' like grains could decrease effective area for hydrogen evolution reaction in slight amorphous nickel-molybdenum alloy. The synergistic effect between nickel and reduced graphene oxide promoted hydrogen evolution, moreover, refined grain in nickel-reduced graphene oxide composite coating and large specific surface of reduced graphene oxide also facilitated hydrogen evolution reaction.

Method for improve x-ray diffraction determinations of residual stress in nickel-base alloys

DOEpatents

Berman, Robert M.; Cohen, Isadore

1990-01-01

A process for improving the technique of measuring residual stress by x-ray diffraction in pieces of nickel-base alloys which comprises covering part of a predetermined area of the surface of a nickel-base alloy with a dispersion, exposing the covered and uncovered portions of the surface of the alloy to x-rays by way of an x-ray diffractometry apparatus, making x-ray diffraction determinations of the exposed surface, and measuring the residual stress in the alloy based on these determinations. The dispersion is opaque to x-rays and serves a dual purpose since it masks off unsatisfactory signals such that only a small portion of the surface is measured, and it supplies an internal standard by providing diffractogram peaks comparable to the peaks of the nickel alloy so that the alloy peaks can be very accurately located regardless of any sources of error external to the sample.

Joining precipitation-hardened nickel-base alloys by friction welding

NASA Technical Reports Server (NTRS)

Moore, T. J.

1972-01-01

Solid state deformation welding process, friction welding, has been developed for joining precipitation hardened nickel-base alloys and other gamma prime-strengthened materials which heretofore have been virtually unweldable. Method requires rotation of one of the parts to be welded, but where applicable, it is an ideal process for high volume production jobs.

Additive Manufacturing of Nickel Superalloys: Opportunities for Innovation and Challenges Related to Qualification

NASA Astrophysics Data System (ADS)

Babu, S. S.; Raghavan, N.; Raplee, J.; Foster, S. J.; Frederick, C.; Haines, M.; Dinwiddie, R.; Kirka, M. K.; Plotkowski, A.; Lee, Y.; Dehoff, R. R.

2018-06-01

Innovative designs for turbines can be achieved by advances in nickel-based superalloys and manufacturing methods, including the adoption of additive manufacturing. In this regard, selective electron beam melting (SEBM) and selective laser melting (SLM) of nickel-based superalloys do provide distinct advantages. Furthermore, the direct energy deposition (DED) processes can be used for repair and reclamation of nickel alloy components. The current paper explores opportunities for innovation and qualification challenges with respect to deployment of AM as a disruptive manufacturing technology. In the first part of the paper, fundamental correlations of processing parameters to defect tendency and microstructure evolution will be explored using DED process. In the second part of the paper, opportunities for innovation in terms of site-specific control of microstructure during processing will be discussed. In the third part of the paper, challenges in qualification of AM parts for service will be discussed and potential methods to alleviate these issues through in situ process monitoring, and big data analytics are proposed.

Anisotropy of high temperature strength in precipitation-hardened nickel-base superalloy single crystals

NASA Technical Reports Server (NTRS)

Nakagawa, Y. G.; Terashima, H.; Yoshizawa, H.; Ohta, Y.; Murakami, K.

1986-01-01

The anisotropy of high temperature strength of nickel-base superalloy, Alloy 454, in service for advanced jet engine turbine blades and vanes, was investigated. Crystallographic orientation dependence of tensile yield strength, creep and creep rupture strength was found to be marked at about 760C. In comparison with other single crystal data, a larger allowance in high strength off-axial orientation from the 001 axis, and relatively poor strength at near the -111 axis were noted. From transmission electron microscopy the anisotropic characteristics of this alloy were explained in terms of available slip systems and stacking geometries of gamma-prime precipitate cuboids which are well hardened by a large tantalum content. 100 cube slip was considered to be primarily responsible for the poor strength of the -111 axis orientation replacing the conventional 111 plane slip systems.

GAPS IN PROTOPLANETARY DISKS AS SIGNATURES OF PLANETS. II. INCLINED DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang-Condell, Hannah; Turner, Neal J.

2013-07-20

We examine the observational appearance of partial gaps being opened by planets in protoplanetary disks, considering the effects of the inclination relative to the line of sight. We model the disks with static {alpha}-models with detailed radiative transfer, parameterizing the shape and size of the partially cleared gaps based on the results of hydrodynamic simulations. As in previous work, starlight falling across the gap leads to high surface brightness contrasts. The gap's trough is darkened by both shadowing and cooling, relative to the uninterrupted disk. The gap's outer wall is brightened by direct illumination and also by heating, which puffsmore » it up so that it intercepts more starlight. In this paper, we examine the effects of inclination on resolved images of disks with and without gaps at a wide range of wavelengths. The scattering surface's offset from the disk midplane creates a brightness asymmetry along the axis of inclination, making the disk's near side appear brighter than the far side in scattered light. Finite disk thickness also causes the projected distances of equidistant points on the disk surface to be smaller on the near side of the disk as compared to the far side. Consequently, the gap shoulder on the near side of the disk should appear brighter and closer to the star than on the far side. However, if the angular resolution of the observation is coarser than the width of the brightened gap shoulder, then the gap shoulder on the far side may appear brighter because of its larger apparent size. We present a formula to recover the scale height and inclination angle of an imaged disk using simple geometric arguments and measuring disk asymmetries. Resolved images of circumstellar disks have revealed clearings and gaps, such as the transitional disk in LkCa 15. Models created using our synthetic imaging attempting to match the morphology of observed scattered light images of LkCa 15 indicate that the H-band flux deficit in the inner

Comparative Performance Assessment of INTELSAT 5 Nickel Hydrogen and Nickel Cadmium Batteries

NASA Technical Reports Server (NTRS)

Cooper, D.; Ozkul, A.

1984-01-01

The first Nickel Hydrogen battery deployment onboard a commercial geosynchronous communications satellite was realized with the launch of the INTELSAT 5, Flight 6 spacecraft on 19 May 1983. The initial five spacecrafts in this series are equipped with Nickel Cadmium batteries. Based on the data available on both types of batteries, design and operational performance comparisons of INTELSAT 5 Nickel Cadmium batteries are presented. General characteristics of the INTELSAT 5 spacecraft as related to electrical-power-subsystem functions and battery operations are summarized.

Microstructural indicators of transition mechanisms in time-dependent fatigue crack growth in nickel base superalloys

NASA Astrophysics Data System (ADS)

Heeter, Ann E.

Gas turbine engines are an important part of power generation in modern society, especially in the field of aerospace. Aerospace engines are design to last approximately 30 years and the engine components must be designed to survive for the life of the engine or to be replaced at regular intervals to ensure consumer safety. Fatigue crack growth analysis is a vital component of design for an aerospace component. Crack growth modeling and design methods date back to an origin around 1950 with a high rate of accuracy. The new generation of aerospace engines is designed to be efficient as possible and require higher operating temperatures than ever seen before in previous generations. These higher temperatures place more stringent requirements on the material crack growth performance under creep and time dependent conditions. Typically the types of components which are subject to these requirements are rotating disk components which are made from advanced materials such as nickel base superalloys. Traditionally crack growth models have looked at high temperature crack growth purely as a function of temperature and assumed that all crack growth was either controlled by a cycle dependent or time dependent mechanism. This new analysis is trying to evaluate the transition between cycle-dependent and time-dependent mechanism and the microstructural markers that characterize this transitional behavior. The physical indications include both the fracture surface morphology as well as the shape of the crack front. The research will evaluate whether crack tunneling occurs and whether it consistently predicts a transition from cycle-dependent crack growth to time-dependent crack growth. The study is part of a larger research program trying to include the effects of geometry, mission profile and environmental effects, in addition to temperature effects, as a part of the overall crack growth system. The outcome will provide evidence for various transition types and correlate those

Smart nickel oxide materials for the applications of energy efficiency and storage

NASA Astrophysics Data System (ADS)

Lin, Feng

The present dissertation studies nickel oxide-based materials for the application of electrochromic windows and lithium-air batteries. The materials were fabricated via radio frequency magnetron sputtering and subsequently post-treated with thermal evaporation and ozone exposure. The strategies to improve electrochromic performance of nickel oxide materials were investigated including compositional control, morphology tuning, modification of electronic structure and interface engineering (i.e., Li2O 2, graphene). The electrochemical properties of the resulting materials were characterized in lithium ion electrolytes. Extremely high performing nickel oxide-based electrochromic materials were obtained in terms of optical modulation, switching kinetics, bleached-state transparency and durability, which promise the implementation of these materials for practical smart windows. With the aid of advanced synchrotron X-ray absorption spectroscopy, it is reported for the first time that the electrochromic effect in multicomponent nickel oxide-based materials arises from the reversible formation of hole states in the NiO6 cluster accompanying with the reversible formation of Li2O2. The reversible formation of Li2O 2 was successfully leveraged with the study of electro-catalysts and cathode materials for lithium-air batteries. The reversibility of Li 2O2 was thoroughly investigated using soft X-ray absorption spectroscopy and theoretical simulation, which substantiates the promise of using electrochromic films as electro-catalysts and/or cathode materials in lithium-air batteries.

Digitized molecular diagnostics: reading disk-based bioassays with standard computer drives.

PubMed

Li, Yunchao; Ou, Lily M L; Yu, Hua-Zhong

2008-11-01

We report herein a digital signal readout protocol for screening disk-based bioassays with standard optical drives of ordinary desktop/notebook computers. Three different types of biochemical recognition reactions (biotin-streptavidin binding, DNA hybridization, and protein-protein interaction) were performed directly on a compact disk in a line array format with the help of microfluidic channel plates. Being well-correlated with the optical darkness of the binding sites (after signal enhancement by gold nanoparticle-promoted autometallography), the reading error levels of prerecorded audio files can serve as a quantitative measure of biochemical interaction. This novel readout protocol is about 1 order of magnitude more sensitive than fluorescence labeling/scanning and has the capability of examining multiplex microassays on the same disk. Because no modification to either hardware or software is needed, it promises a platform technology for rapid, low-cost, and high-throughput point-of-care biomedical diagnostics.

Method for improving x-ray diffraction determinations of residual stress in nickel-base alloys

DOEpatents

Berman, R.M.; Cohen, I.

1988-04-26

A process for improving the technique of measuring residual stress by x-ray diffraction in pieces of nickel-base alloys is discussed. Part of a predetermined area of the surface of a nickel-base alloy is covered with a dispersion. This exposes the covered and uncovered portions of the surface of the alloy to x-rays by way of an x-ray diffractometry apparatus, making x-ray diffraction determinations of the exposed surface, and measuring the residual stress in the alloy based on these determinations. The dispersion is opaque to x-rays and serves a dual purpose, since it masks off unsatisfactory signals such that only a small portion of the surface is measured, and it supplies an internal standard by providing diffractogram peaks comparable to the peaks of the nickel alloy so that the alloy peaks can be very accurately located regardless of any sources of error external to the sample. 2 figs.

Deciphering Debris Disk Structure with the Submillimeter Array

NASA Astrophysics Data System (ADS)

MacGregor, Meredith Ann

2018-01-01

More than 20% of nearby main sequence stars are surrounded by dusty disks continually replenished via the collisional erosion of planetesimals, larger bodies similar to asteroids and comets in our own Solar System. The material in these ‘debris disks’ is directly linked to the larger bodies such as planets in the system. As a result, the locations, morphologies, and physical properties of dust in these disks provide important probes of the processes of planet formation and subsequent dynamical evolution. Observations at millimeter wavelengths are especially critical to our understanding of these systems, since they are dominated by larger grains that do not travel far from their origin and therefore reliably trace the underlying planetesimal distribution. The Submillimeter Array (SMA) plays a key role in advancing our understanding of debris disks by providing sensitivity at the short baselines required to determine the structure of wide-field disks, such as the HR 8799 debris disk. Many of these wide-field disks are among the closest systems to us, and will serve as cornerstone templates for the interpretation of more distant, less accessible systems.

Evaluation of the cyclic behavior of aircraft turbine disk alloys

NASA Technical Reports Server (NTRS)

Cowles, B. A.; Sims, D. L.; Warren, J. R.

1978-01-01

Five aircraft turbine disk alloys representing various strength and processing histories were evaluated at 650 C to determine if recent strength advances in powder metallurgy have resulted in corresponding increases in low cycle fatigue (LCF) capability. Controlled strain LCF tests and controlled load crack propagation tests were performed. Results were used for direct material comparisons and in the analysis of an advanced aircraft turbine disk, having a fixed design and operating cycle. Crack initiation lives were found to increase with increasing tensile yield strength, while resistance to fatigue crack propagation generally decreased with increasing strength.

Study of alumina-trichite reinforcement of a nickel-based matric by means of powder metallurgy

NASA Technical Reports Server (NTRS)

Walder, A.; Hivert, A.

1982-01-01

Research was conducted on reinforcing nickel based matrices with alumina trichites by using powder metallurgy. Alumina trichites previously coated with nickel are magnetically aligned. The felt obtained is then sintered under a light pressure at a temperature just below the melting point of nickel. The halogenated atmosphere technique makes it possible to incorporate a large number of additive elements such as chromium, titanium, zirconium, tantalum, niobium, aluminum, etc. It does not appear that going from laboratory scale to a semi-industrial scale in production would create any major problems.

Preparation and testing of nickel-based superalloy/sodium heat pipes

NASA Astrophysics Data System (ADS)

Lu, Qin; Han, Haitao; Hu, Longfei; Chen, Siyuan; Yu, Jijun; Ai, Bangcheng

2017-11-01

In this work, a kind of uni-piece nickel-based superalloy/sodium heat pipe is proposed. Five models of high temperature heat pipe were prepared using GH3044 and GH4099 nickel-based superalloys. And their startup performance and ablation resistance were investigated by quartz lamp calorifier radiation and wind tunnel tests, respectively. It is found that the amount of charging sodium affects the startup performance of heat pipes apparently. No startup phenomenon was found for insufficient sodium charged model. In contrast, the models charged with sufficient sodium startup successfully, displaying a uniform temperature distribution. During wind tunnel test, the corresponding models experienced a shorter startup time than that during quartz lamp heating. GH4099/sodium heat pipe shows excellent ablation resistance, being better than that of GH3044/sodium heat pipe. Therefore, it is proposed that this kind of heat pipe has a potential application in thermal protection system of hypersonic cruise vehicles.

Welding of nickel-base superalloys having a nil-ductility range

NASA Technical Reports Server (NTRS)

Smashey, Russell W. (Inventor); Kelly, Thomas J. (Inventor); Snyder, John H. (Inventor); Sheranko, Ronald L. (Inventor)

1999-01-01

An article made of a nickel-base superalloy having a nil-ductility range from the solidus temperature of the alloy to about 600.degree. F. below the solidus temperature is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, adjusting the temperature of the article to a welding temperature of from about 1800.degree. F. to about 2100.degree. F., welding a preselected area in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected area so as to locally melt the alloy in the preselected area, providing a filler metal having the same composition as the nickel-based superalloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.

Fuel Cell Performance Implications of Membrane Electrode Assembly Fabrication with Platinum-Nickel Nanowire Catalysts

DOE PAGES

Mauger, Scott A.; Neyerlin, K. C.; Alia, Shaun M.; ...

2018-03-13

Platinum-nickel nanowire (PtNiNW) catalysts have shown exceptionally high oxygen reduction mass activity in rotating disk electrode measurements. However, the ability to successfully incorporate PtNiNWs into high performance membrane electrode assemblies (MEAs) has been challenging due to their size, shape, density, dispersion characteristics, and corrosion-susceptible nickel core. We have investigated the impact of specific processing steps and electrode composition on observed fuel cell performance and electrochemical properties in order to optimize performance. We have found that nickel ion contamination is a major concern for PtNiNWs that can be addressed through ion exchange in fabricated/tested MEAs or by acid leaching of catalystmore » materials prior to MEA incorporation, with the latter being the more successful method. Additionally, decreased ionomer incorporation has led to the highest performance demonstrating 238 mA/mg Pt (0.9 V IR-free) for PtNiNWs (pre-leached to 80 wt% Pt) with 9 wt% ionomer incorporation.« less

Fuel Cell Performance Implications of Membrane Electrode Assembly Fabrication with Platinum-Nickel Nanowire Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mauger, Scott A.; Neyerlin, K. C.; Alia, Shaun M.

Platinum-nickel nanowire (PtNiNW) catalysts have shown exceptionally high oxygen reduction mass activity in rotating disk electrode measurements. However, the ability to successfully incorporate PtNiNWs into high performance membrane electrode assemblies (MEAs) has been challenging due to their size, shape, density, dispersion characteristics, and corrosion-susceptible nickel core. We have investigated the impact of specific processing steps and electrode composition on observed fuel cell performance and electrochemical properties in order to optimize performance. We have found that nickel ion contamination is a major concern for PtNiNWs that can be addressed through ion exchange in fabricated/tested MEAs or by acid leaching of catalystmore » materials prior to MEA incorporation, with the latter being the more successful method. Additionally, decreased ionomer incorporation has led to the highest performance demonstrating 238 mA/mg Pt (0.9 V IR-free) for PtNiNWs (pre-leached to 80 wt% Pt) with 9 wt% ionomer incorporation.« less

Welding Metallurgy of Nickel-Based Superalloys for Power Plant Construction

NASA Astrophysics Data System (ADS)

Tung, David C.

Increasing the steam temperature and pressure in coal-fired power plants is a perpetual goal driven by the pursuit of increasing thermal cycle efficiency and reducing fuel consumption and emissions. The next target steam operating conditions, which are 760°C (1400°F) and 35 MPa (5000 psi) are known as Advanced Ultra Supercritical (AUSC), and can reduce CO2 emissions up to 13% but this cannot be achieved with traditional power plant construction materials. The use of precipitation-strengthened Nickel-based alloys (superalloys) is required for components which will experience the highest operating temperatures. The leading candidate superalloys for power plant construction are alloys 740H, 282, and 617. Superalloys have excellent elevated temperature properties due to careful microstructural design which is achieved through very specific heat treatments, often requiring solution annealing or homogenization at temperatures of 1100 °C or higher. A series of postweld heat treatments was investigated and it was found that homogenization steps before aging had no noticeable effect on weld metal microhardness, however; there were clear improvements in weld metal homogeneity. The full abstract can be viewed in the document itself.

Quantitative Residual Strain Analyses on Strain Hardened Nickel Based Alloy

NASA Astrophysics Data System (ADS)

Yonezawa, Toshio; Maeguchi, Takaharu; Goto, Toru; Juan, Hou

Many papers have reported about the effects of strain hardening by cold rolling, grinding, welding, etc. on stress corrosion cracking susceptibility of nickel based alloys and austenitic stainless steels for LWR pipings and components. But, the residual strain value due to cold rolling, grinding, welding, etc. is not so quantitatively evaluated.

Rotationally-supported disks around Class I sources in Taurus: disk formation constraints

NASA Astrophysics Data System (ADS)

Harsono, D.; Jørgensen, J. K.; van Dishoeck, E. F.; Hogerheijde, M. R.; Bruderer, S.; Persson, M. V.; Mottram, J. C.

2014-02-01

Context. Disks are observed around pre-main sequence stars, but how and when they form is still heavily debated. While disks around young stellar objects have been identified through thermal dust emission, spatially and spectrally resolved molecular line observations are needed to determine their nature. Only a handful of embedded rotationally supported disks have been identified to date. Aims: We identify and characterize rotationally supported disks near the end of the main accretion phase of low-mass protostars by comparing their gas and dust structures. Methods: Subarcsecond observations of dust and gas toward four Class I low-mass young stellar objects in Taurus are presented at significantly higher sensitivity than previous studies. The 13CO and C18O J = 2-1 transitions at 220 GHz were observed with the Plateau de Bure Interferometer at a spatial resolution of ≤0.8″ (56 AU radius at 140 pc) and analyzed using uv-space position velocity diagrams to determine the nature of their observed velocity gradient. Results: Rotationally supported disks (RSDs) are detected around 3 of the 4 Class I sources studied. The derived masses identify them as Stage I objects; i.e., their stellar mass is higher than their envelope and disk masses. The outer radii of the Keplerian disks toward our sample of Class I sources are ≤100 AU. The lack of on-source C18O emission for TMR1 puts an upper limit of 50 AU on its size. Flattened structures at radii >100 AU around these sources are dominated by infalling motion (υ ∝ r-1). A large-scale envelope model is required to estimate the basic parameters of the flattened structure from spatially resolved continuum data. Similarities and differences between the gas and dust disk are discussed. Combined with literature data, the sizes of the RSDs around Class I objects are best described with evolutionary models with an initial rotation of Ω = 10-14 Hz and slow sound speeds. Based on the comparison of gas and dust disk masses

Cyclic Spin Testing of Superalloy Disks With a Dual Grain Microstructure

NASA Technical Reports Server (NTRS)

Gayda, John; Kantzos, Pete

2005-01-01

An aggressive cyclic spin test program was run to verify the reliability of superalloy disks with a dual grain structure, fine grain bore and coarse grain rim, utilizing a disk design with web holes bisecting the grain size transition zone. Results of these tests were compared with conventional disks with uniform grain structures. Analysis of the test results indicated the cyclic performance of disks with a dual grain structure could be estimated to a level of accuracy which does not appear to prohibit the use of this technology in advanced gas turbine engines, although further refinement of lifing methodology is clearly warranted.

The development of additive manufacturing technique for nickel-base alloys: A review

NASA Astrophysics Data System (ADS)

Zadi-Maad, Ahmad; Basuki, Arif

2018-04-01

Nickel-base alloys are an attractive alloy due to its excellent mechanical properties, a high resistance to creep deformation, corrosion, and oxidation. However, it is a hard task to control performance when casting or forging for this material. In recent years, additive manufacturing (AM) process has been implemented to replace the conventional directional solidification process for the production of nickel-base alloys. Due to its potentially lower cost and flexibility manufacturing process, AM is considered as a substitute technique for the existing. This paper provides a comprehensive review of the previous work related to the AM techniques for Ni-base alloys while highlighting current challenges and methods to solving them. The properties of conventionally manufactured Ni-base alloys are also compared with the AM fabricated alloys. The mechanical properties obtained from tension, hardness and fatigue test are included, along with discussions of the effect of post-treatment process. Recommendations for further work are also provided.

Stagger angle dependence of inertial and elastic coupling in bladed disks

NASA Technical Reports Server (NTRS)

Crawley, E. F.; Mokadam, D. R.

1984-01-01

Conditions which necessitate the inclusion of disk and shaft flexibility in the analysis of blade response in rotating blade-disk-shaft systems are derived in terms of nondimensional parameters. A simple semianalytical Rayleigh-Ritz model is derived in which the disk possesses all six rigid body degrees of freedom, which are elastically constrained by the shaft. Inertial coupling by the rigid body motion of the disk on a flexible shaft and out-of-plane elastic coupling due to disk flexure are included. Frequency ratios and mass ratios, which depend on the stagger angle, are determined for three typical rotors: a first stage high-pressure core compressor, a high bypass ratio fan, and an advanced turboprop. The stagger angle controls the degree of coupling in the blade-disk system. In the blade-disk-shaft system, the stagger angle determines whether blade-disk motion couples principally to the out-of-plane or in-plane motion of the disk on the shaft. The Ritz analysis shows excellent agreement with experimental results.

A biokinetic model for systemic nickel

DOE PAGES

Melo, Dunstana; Leggett, Richard Wayne

2017-01-01

The International Commission on Radiological Protection (ICRP) is updating its suite of reference biokinetic models for internally deposited radionuclides. This paper reviews data for nickel and proposes an updated biokinetic model for systemic (absorbed) nickel in adult humans for use in radiation protection. Compared with the ICRP s current model for nickel, the proposed model is based on a larger set of observations of the behavior of nickel in human subjects and laboratory animals and provides a more realistic description of the paths of movement of nickel in the body. For the two most important radioisotopes of nickel, 59Ni andmore » 63Ni, the proposed model yields substantially lower dose estimates per unit of activity reaching blood than the current ICRP model.« less

A biokinetic model for systemic nickel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melo, Dunstana; Leggett, Richard Wayne

The International Commission on Radiological Protection (ICRP) is updating its suite of reference biokinetic models for internally deposited radionuclides. This paper reviews data for nickel and proposes an updated biokinetic model for systemic (absorbed) nickel in adult humans for use in radiation protection. Compared with the ICRP s current model for nickel, the proposed model is based on a larger set of observations of the behavior of nickel in human subjects and laboratory animals and provides a more realistic description of the paths of movement of nickel in the body. For the two most important radioisotopes of nickel, 59Ni andmore » 63Ni, the proposed model yields substantially lower dose estimates per unit of activity reaching blood than the current ICRP model.« less

Burst Testing and Analysis of Superalloy Disks With a Dual Grain Microstructure

NASA Technical Reports Server (NTRS)

Gayda, John; Kantzos, Pete

2006-01-01

Elastic-plastic finite element analyses of room temperature burst tests on four superalloy disks were conducted and reported in this paper. Two alloys, Rene 104 (General Electric Aircraft Engines) and Alloy 10 (Honeywell Engines & Systems), were studied. For both alloys an advanced dual microstructure disk, fine grain bore and coarse grain rim, were analyzed and compared with conventional disks with uniform microstructures, coarse grain for Rene 104 and fine grain for Alloy 10. The analysis and experimental data were in good agreement up to burst. At burst, the analysis underestimated the speed and growth of the Rene 104 disks, but overestimated the speed and growth of the Alloy 10 disks. Fractography revealed that the Alloy 10 disks displayed significant surface microcracking and coalescence in comparison to Rene 104 disks. This phenomenon may help explain the differences between the Alloy 10 disks and the Rene 104 disks, as well as the observed deviations between analytical and experimental data at burst.

Hydrogen induced fracture characteristics of single crystal nickel-based superalloys

NASA Technical Reports Server (NTRS)

Chen, Po-Shou; Wilcox, Roy C.

1990-01-01

A stereoscopic method for use with x ray energy dispersive spectroscopy of rough surfaces was adapted and applied to the fracture surfaces single crystals of PWA 1480E to permit rapid orientation determinations of small cleavage planes. The method uses a mathematical treatment of stereo pair photomicrographs to measure the angle between the electron beam and the surface normal. One reference crystal orientation corresponding to the electron beam direction (crystal growth direction) is required to perform this trace analysis. The microstructure of PWA 1480E was characterized before fracture analysis was performed. The fracture behavior of single crystals of the PWA 1480E nickel-based superalloy was studied. The hydrogen-induced fracture behavior of single crystals of the PWA 1480E nickel-based superalloy was also studied. In order to understand the temperature dependence of hydrogen-induced embrittlement, notched single crystals with three different crystal growth orientations near zone axes (100), (110), and (111) were tensile tested at 871 C (1600 F) in both helium and hydrogen atmospheres at 34 MPa. Results and conclusions are given.

A review of nickel hydrogen battery technology

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Odonnell, Patricia M.

1995-01-01

This paper on nickel hydrogen batteries is an overview of the various nickel hydrogen battery design options, technical accomplishments, validation test results and trends. There is more than one nickel hydrogen battery design, each having its advantage for specific applications. The major battery designs are individual pressure vessel (IPV), common pressure vessel (CPV), bipolar and low pressure metal hydride. State-of-the-art (SOA) nickel hydrogen batteries are replacing nickel cadmium batteries in almost all geosynchronous orbit (GEO) applications requiring power above 1 kW. However, for the more severe low earth orbit (LEO) applications (greater than 30,000 cycles), the current cycle life of 4000 to 10,000 cycles at 60 percent DOD should be improved. A NASA Lewis Research Center innovative advanced design IPV nickel hydrogen cell led to a breakthrough in cycle life enabling LEO applications at deep depths of discharge (DOD). A trend for some future satellites is to increase the power level to greater than 6 kW. Another trend is to decrease the power to less than 1 kW for small low cost satellites. Hence, the challenge is to reduce battery mass, volume and cost. A key is to develop a light weight nickel electrode and alternate battery designs. A common pressure vessel (CPV) nickel hydrogen battery is emerging as a viable alternative to the IPV design. It has the advantage of reduced mass, volume and manufacturing costs. A 10 Ah CPV battery has successfully provided power on the relatively short lived Clementine Spacecraft. A bipolar nickel hydrogen battery design has been demonstrated (15,000 LEO cycles, 40 percent DOD). The advantage is also a significant reduction in volume, a modest reduction in mass, and like most bipolar designs, features a high pulse power capability. A low pressure aerospace nickel metal hydride battery cell has been developed and is on the market. It is a prismatic design which has the advantage of a significant reduction in volume and a

Extragalactic SETI: The Tully-Fisher Relation as a Probe of Dysonian Astroengineering in Disk Galaxies

NASA Astrophysics Data System (ADS)

Zackrisson, Erik; Calissendorff, Per; Asadi, Saghar; Nyholm, Anders

2015-09-01

If advanced extraterrestrial civilizations choose to construct vast numbers of Dyson spheres to harvest radiation energy, this could affect the characteristics of their host galaxies. Potential signatures of such astroengineering projects include reduced optical luminosity, boosted infrared luminosity, and morphological anomalies. Here, we apply a technique pioneered by Annis to search for Kardashev type III civilizations in disk galaxies, based on the predicted offset of these galaxies from the optical Tully-Fisher (TF) relation. By analyzing a sample of 1359 disk galaxies, we are able to set a conservative upper limit of ≲ 3% on the fraction of local disks subject to Dysonian astroengineering on galaxy-wide scales. However, the available data suggests that a small subset of disk galaxies actually may be underluminous with respect to the TF relation in the way expected for Kardashev type III objects. Based on the optical morphologies and infrared-to-optical luminosity ratios of such galaxies in our sample, we conclude that none of them stand out as strong Kardashev type III candidates and that their inferred properties likely have mundane explanations. This allows us to set a tentative upper limit at ≲ 0.3% on the fraction of Karashev type III disk galaxies in the local universe.

Adhesive bonding of super-elastic titanium-nickel alloy castings with a phosphate metal conditioner and an acrylic adhesive.

PubMed

Matsumura, H; Tanoue, N; Yanagida, H; Atsuta, M; Koike, M; Yoneyama, T

2003-06-01

The purpose of the current study was to evaluate the bonding characteristics of super-elastic titanium-nickel (Ti-Ni) alloy castings. Disk specimens were cast from a Ti-Ni alloy (Ti-50.85Ni mol%) using an arc centrifugal casting machine. High-purity titanium and nickel specimens were also prepared as experimental references. The specimens were air-abraded with alumina, and bonded with an adhesive resin (Super-Bond C & B). A metal conditioner containing a phosphate monomer (Cesead II Opaque Primer) was also used for priming the specimens. Post-thermocycling average bond strengths (MPa) of the primed groups were 41.5 for Ti-Ni, 30.4 for Ti and 19.5 for Ni, whereas those of the unprimed groups were 21.6 for Ti, 19.3 for Ti-Ni and 9.3 for Ni. Application of the phosphate conditioner elevated the bond strengths of all alloy/metals (P < 0.05). X-ray fluorescence analysis revealed that nickel was attached to the debonded resin surface of the resin-to-nickel bonded specimen, indicating that corrosion of high-purity nickel occurred at the resin-nickel interface. Durable bonding to super-elastic Ti-Ni alloy castings can be achieved with a combination of a phosphate metal conditioner and a tri-n-butylborane-initiated adhesive resin.

Essential elucidation for preparation of supported nickel phosphide upon nickel phosphate precursor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xuguang, E-mail: liuxuguang@qust.edu.cn; Xu, Lei; Zhang, Baoquan

2014-04-01

Preparation of supported nickel phosphide (Ni{sub 2}P) depends on nickel phosphate precursor, generally related to its chemical composition and supports. Study of this dependence is essential and meaningful for the preparation of supported Ni{sub 2}P with excellent catalytic activity. The chemical nature of nickel phosphate precursor is revealed by Raman and UV–vis spectra. It is found that initial P/Ni mole ratio ≥0.8 prohibits the Ni-O-Ni bridge bonding (i.e., nickel oxide). This chemical bonding will not result in Ni{sub 2}P structure, verified by XRD characterization results. The alumina (namely, γ-Al{sub 2}O{sub 3}, θ-Al{sub 2}O{sub 3}, or α-Al{sub 2}O{sub 3}) with distinctmore » physiochemical properties also results in diverse chemical nature of nickel phosphate, and then different nickel phosphides. The influence of alumina support on producing Ni{sub 2}P was explained by the theory of surface energy heterogeneity, calculated by the NLDFT method based on N{sub 2}-sorption isotherm. The uniform surface energy of α-Al{sub 2}O{sub 3} results only in the nickel phosphosate precursor and thus the Ni{sub 2}P phase. - Graphical abstract: Surface energy heterogeneity in alumina (namely α-Al{sub 2}O{sub 3}, θ-Al{sub 2}O{sub 3}, and γ-Al{sub 2}O{sub 3}) supported multi-oxidic precursors with different reducibilities and thus diverse nickel phosphides (i.e., Ni{sub 3}P, Ni{sub 12}P{sub 5}, Ni{sub 2}P). - Highlights: • Preparing pure Ni{sub 2}P. • Elucidating nickel phosphate precursor. • Associating with surface energy.« less

Etude des mecanismes de formation des microstructures lors du brasage isotherme de superalliages a base de nickel

NASA Astrophysics Data System (ADS)

Ruiz-Vargas, Jose

This thesis reports theoretical and experimental investigations carried out to understand the mechanisms of microstructure formation during isothermal brazing, produced by brazing Inconel 625 and MC2 nickel-based superalloys with filler metal BNi-2. Firstly, studies were made on pure Ni to interpret microstructure's formation with simplified alloy chemistry. Microstructure formation have been studied when varying time at constant temperature (isothermal kinetics), but also when varying temperature for constant hold time (isochronal kinetics). The chemical composition and crystallography of the present phases have been identified, with the following results : (i) the fraction of dissolved base metal has been found proportional to the initial thickness of the brazing alloy, so that the composition of the liquid remains homogeneous with a precise initial equilibrium composition during the whole brazing process, (ii) the melting of the joint occurs in two steps : at lower temperature, it involves only partially melting, and boron diffusion in pure Ni leads to the precipitation of fine Ni3B borides at the interface ; in a second stage, at higher temperature, melting is complete and thermodynamic equilibrium requires significant dissolution of nickel, which also involves the dissolution of part of borides already formed. Secondly, nickel plating technique was used on Inconel 625 nickel-based superalloy. A thin layer of Ni with varying thickness, has been electrodeposited to observe the gradual dissolution of Inconel and microstructural features formation due to the presence of superalloy alloying elements. It has been observed that the nickel coating does not prevent precipitation in the base metal as boron diffuse rapidly through the coating width. In the intermediate nickel plating width, fragile precipitates of nickel borides have been observed, because the contribution of Inconel alloying elements to the melt was very limited. In absence of nickel plating on the

Attack polish for nickel-base alloys and stainless steels

DOEpatents

Steeves, Arthur F.; Buono, Donald P.

1983-01-01

A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

Method of polishing nickel-base alloys and stainless steels

DOEpatents

Steeves, Arthur F.; Buono, Donald P.

1981-01-01

A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

Attack polish for nickel-base alloys and stainless steels

DOEpatents

Not Available

1980-05-28

A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels is described. The chemical attack polich comprises FeNO/sub 3/, concentrated CH/sub 3/COOH, concentrated H/sub 2/SO/sub 4/ and H/sub 2/O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

A MEMS disk resonator-based band pass filter electrical equivalent circuit simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundaram, G. M.; Angira, Mahesh; Gupta, Navneet

In this paper, coupled beam bandpass Disk filter is designed for 1 MHz bandwidth. Filter electrical equivalent circuit simulation is performed using circuit simulators. Important filter parameters such as insertion loss, shape factor and Q factor aresetimated using coventorware simulation. Disk resonator based radial contour mode filter provides 1.5 MHz bandwidth and unloaded quality factor of resonator and filter as 233480, 21797 respectively. From the simulation result it’s found that insertion loss minimum is 151.49 dB, insertion loss maximum is 213.94 dB, and 40 dB shape factor is 4.17.

Forging of Advanced Disk Alloy LSHR

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, John; Falsey, John

2005-01-01

The powder metallurgy disk alloy LSHR was designed with a relatively low gamma precipitate solvus temperature and high refractory element content to allow versatile heat treatment processing combined with high tensile, creep and fatigue properties. Grain size can be chiefly controlled through proper selection of solution heat treatment temperatures relative to the gamma precipitate solvus temperature. However, forging process conditions can also significantly influence solution heat treatment-grain size response. Therefore, it is necessary to understand the relationships between forging process conditions and the eventual grain size of solution heat treated material. A series of forging experiments were performed with subsequent subsolvus and supersolvus heat treatments, in search of suitable forging conditions for producing uniform fine grain and coarse grain microstructures. Subsolvus, supersolvus, and combined subsolvus plus supersolvus heat treatments were then applied. Forging and subsequent heat treatment conditions were identified allowing uniform fine and coarse grain microstructures.

Hierarchical Mesoporous Zinc-Nickel-Cobalt Ternary Oxide Nanowire Arrays on Nickel Foam as High-Performance Electrodes for Supercapacitors.

PubMed

Wu, Chun; Cai, Junjie; Zhang, Qiaobao; Zhou, Xiang; Zhu, Ying; Shen, Pei Kang; Zhang, Kaili

2015-12-09

Nickel foam supported hierarchical mesoporous Zn-Ni-Co ternary oxide (ZNCO) nanowire arrays are synthesized by a simple two-step approach including a hydrothermal method and subsequent calcination process and directly utilized for supercapacitive investigation for the first time. The nickel foam supported hierarchical mesoporous ZNCO nanowire arrays possess an ultrahigh specific capacitance value of 2481.8 F g(-1) at 1 A g(-1) and excellent rate capability of about 91.9% capacitance retention at 5 A g(-1). More importantly, an asymmetric supercapacitor with a high energy density (35.6 Wh kg(-1)) and remarkable cycle stability performance (94% capacitance retention over 3000 cycles) is assembled successfully by employing the ZNCO electrode as positive electrode and activated carbon as negative electrode. The remarkable electrochemical behaviors demonstrate that the nickel foam supported hierarchical mesoporous ZNCO nanowire array electrodes are highly desirable for application as advanced supercapacitor electrodes.

Fomalhaut's Debris Disk and Planet: Constraining the Mass of Formalhaut B from Disk Morphology

NASA Technical Reports Server (NTRS)

Chiang, E.; Kite, E.; Kalas, P.; Graham, J. R.; Clampin, M.

2008-01-01

Following the optical imaging of exoplanet candidate Fomalhaut b (Fom b), we present a numerical model of how Fomalhaut's debris disk is gravitationally shaped by a single interior planet. The model is simple, adaptable to other debris disks, and can be extended to accommodate multiple planets. If Fom b is the dominant perturber of the belt, then to produce the observed disk morphology it must have a mass M(sub pl) < 3M(sub J), an orbital semimajor axis a(sub pl) > 101.5AU, and an orbital eccentricity e(sub pl) = 0.11 - 0.13. These conclusions are independent of Fom b's photometry. To not disrupt the disk, a greater mass for Fom b demands a smaller orbit farther removed from the disk; thus, future astrometric measurement of Fom b's orbit, combined with our model of planet-disk interaction, can be used to determine the mass more precisely. The inner edge of the debris disk at a approximately equals 133AU lies at the periphery of Fom b's chaotic zone, and the mean disk eccentricity of e approximately equals 0.11 is secularly forced by the planet, supporting predictions made prior to the discovery of Fom b. However, previous mass constraints based on disk morphology rely on several oversimplifications. We explain why our constraint is more reliable. It is based on a global model of the disk that is not restricted to the planet's chaotic zone boundary. Moreover, we screen disk parent bodies for dynamical stability over the system age of approximately 100 Myr, and model them separately from their dust grain progeny; the latter's orbits are strongly affected by radiation pressure and their lifetimes are limited to approximately 0.1 Myr by destructive grain-grain collisions. The single planet model predicts that planet and disk orbits be apsidally aligned. Fomalhaut b's nominal space velocity does not bear this out, but the astrometric uncertainties are difficult to quantify. Even if the apsidal misalignment proves real, our calculated upper mass limit of 3 M(sub J) still

PCM-Based Durable Write Cache for Fast Disk I/O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Zhuo; Wang, Bin; Carpenter, Patrick

2012-01-01

Flash based solid-state devices (FSSDs) have been adopted within the memory hierarchy to improve the performance of hard disk drive (HDD) based storage system. However, with the fast development of storage-class memories, new storage technologies with better performance and higher write endurance than FSSDs are emerging, e.g., phase-change memory (PCM). Understanding how to leverage these state-of-the-art storage technologies for modern computing systems is important to solve challenging data intensive computing problems. In this paper, we propose to leverage PCM for a hybrid PCM-HDD storage architecture. We identify the limitations of traditional LRU caching algorithms for PCM-based caches, and develop amore » novel hash-based write caching scheme called HALO to improve random write performance of hard disks. To address the limited durability of PCM devices and solve the degraded spatial locality in traditional wear-leveling techniques, we further propose novel PCM management algorithms that provide effective wear-leveling while maximizing access parallelism. We have evaluated this PCM-based hybrid storage architecture using applications with a diverse set of I/O access patterns. Our experimental results demonstrate that the HALO caching scheme leads to an average reduction of 36.8% in execution time compared to the LRU caching scheme, and that the SFC wear leveling extends the lifetime of PCM by a factor of 21.6.« less

A highly efficient microfluidic nano biochip based on nanostructured nickel oxide.

PubMed

Ali, Md Azahar; Solanki, Pratima R; Patel, Manoj K; Dhayani, Hemant; Agrawal, Ved Varun; John, Renu; Malhotra, Bansi D

2013-04-07

We present results of the studies relating to fabrication of a microfluidic biosensor chip based on nickel oxide nanorods (NRs-NiO) that is capable of directly measuring the concentration of total cholesterol in human blood through electrochemical detection. Using this chip we demonstrate, with high reliability and in a time efficient manner, the detection of cholesterol present in buffer solutions at clinically relevant concentrations. The microfluidic channel has been fabricated onto a nickel oxide nanorod-based electrode co-immobilized with cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) that serves as the working electrode. Bare indium tin oxide served as the counter electrode. A Ag/AgCl wire introduced to the outlet of the microchannel acts as a reference electrode. The fabricated NiO nanorod-based electrode has been characterized using X-ray diffraction, Raman spectroscopy, HR-TEM, FT-IR, UV-visible spectroscopy and electrochemical techniques. The presented NRs-NiO based microfluidic sensor exhibits linearity in the range of 1.5-10.3 mM, a high sensitivity of 0.12 mA mM(-1) cm(-2) and a low value of 0.16 mM of the Michaelis-Menten constant (Km).

Minimizing the bimetallic bending for cryogenic metal optics based on electroless nickel

NASA Astrophysics Data System (ADS)

Kinast, Jan; Hilpert, Enrico; Lange, Nicolas; Gebhardt, Andreas; Rohloff, Ralf-Rainer; Risse, Stefan; Eberhardt, Ramona; Tünnermann, Andreas

2014-07-01

Ultra-precise metal optics are key components of sophisticated scientific instruments in astronomy and space applications. Especially for cryogenic applications, a detailed knowledge and the control of the coefficient of thermal expansion (CTE) of the used materials are essential. Reflective optical components in IR- and NIR-instruments primarily consist of the aluminum alloy Al6061. The achievable micro-roughness of diamond machined and directly polished Al6061 does not fulfill the requirements for applications in the visible spectral range. Electroless nickel enables the reduction of the mirror surface roughness to the sub-nm range by polishing. To minimize the associated disadvantageous bimetallic effect, a novel material combination for cryogenic mirrors based on electroless nickel and hypereutectic aluminum-silicon is investigated. An increasing silicon content of the aluminum material decreases the CTE in the temperature range to be considered. This paper shows the CTE for aluminum materials containing about 42 wt% silicon (AlSi42) and for electroless nickel with a phosphorous content ranging from 10.5 to 13 %. The CTE differ to about 0.5 × 10-6 K-1 in a temperature range from -185 °C (LN2) to 100 °C. Besides, the correlations between the chemical compositions of aluminum-silicon materials and electroless nickel are shown. A metrology setup for cryo-interferometry was developed to analyze the remaining and reversible shape deviation at cryogenic temperatures. Changes could be caused by different CTE, mounting forces and residual stress conditions. In the electroless nickel layer, the resulting shape deviation can be preshaped by deterministic correction processes such as magnetorheological finishing (MRF) at room temperature.

A Study on Advanced Lithium-Based Battery Cell Chemistries to Enhance Lunar Exploration Missions

NASA Technical Reports Server (NTRS)

Reid, Concha M.; Bennett, William R.

2010-01-01

NASAs Exploration Technology Development Program (ETDP) Energy Storage Project conducted an advanced lithium-based battery chemistry feasibility study to determine the best advanced chemistry to develop for the Altair Lunar Lander and the Extravehicular Activities (EVA) advanced Lunar surface spacesuit. These customers require safe, reliable batteries with extremely high specific energy as compared to state-of-the-art. The specific energy goals for the development project are 220 watt-hours per kilogram (Wh/kg) delivered at the battery-level at 0 degrees Celsius ( C) at a C/10 discharge rate. Continuous discharge rates between C/5 and C/2, operation between 0 and 30 C and 200 cycles are targeted. Electrode materials that were considered include layered metal oxides, spinel oxides, and olivine-type cathode materials, and lithium metal, lithium alloy, and silicon-based composite anode materials. Advanced cell chemistry options were evaluated with respect to multiple quantitative and qualitative attributes while considering their projected performance at the end of the available development timeframe. Following a rigorous ranking process, a chemistry that combines a lithiated nickel manganese cobalt oxide Li(LiNMC)O2 cathode with a silicon-based composite anode was selected as the technology that can potentially offer the best combination of safety, specific energy, energy density, and likelihood of success.

NGC 3516: Disk Diagnostics from a Windy BLSy1 in a High-State

NASA Astrophysics Data System (ADS)

Turner, Tracey

2006-09-01

Recent advances have shown X-ray flux to be simply correlated with reflection-signatures from the disk and with an associated wind in AGN. It appears two things are essential to observe the disk/wind: 1) catch the Seyfert in a high-state where disk/wind features show up strongly and 2) separate out reprocessing from distant gas to allow isolation of disk/wind features. NGC 3516 is currently in a very high state, which we predict will lead to observable features from the disk and its wind. UV data indicate NGC 3516 is very likely to have an observable disk wind due to a favorable orientation. We request 210 ks XMM exposure on NGC 3156 with supporting 200 ks Chandra time to test our prediction of flux-linked disk reflection and wind.

Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bajaj, R.; Mills, W.J.; Kammenzind, B.F.

1999-07-01

This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x10{sup 20} n/cm{sup 2} at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranularmore » failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed.« less

Vacuum Levels Needed to Simulate Internal Fatigue Crack Growth in Titanium Alloys and Nickel-base Superalloys: Thermodynamic Considerations

DTIC Science & Technology

2012-03-01

AFRL-RX-WP-TP-2012-0250 VACUUM LEVELS NEEDED TO SIMULATE INTERNAL FATIGUE CRACK GROWTH IN TITANIUM ALLOYS AND NICKEL - BASE SUPERALLOYS...TITANIUM ALLOYS AND NICKEL - BASE SUPERALLOYS: THERMODYNAMIC CONSIDERATIONS (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM...surface growth in Ti- alloys and Ni - base superalloys. Even with the highest vacuum level attained using “state-of-the-art” pumps, it is unclear if

Fast disk array for image storage

NASA Astrophysics Data System (ADS)

Feng, Dan; Zhu, Zhichun; Jin, Hai; Zhang, Jiangling

1997-01-01

A fast disk array is designed for the large continuous image storage. It includes a high speed data architecture and the technology of data striping and organization on the disk array. The high speed data path which is constructed by two dual port RAM and some control circuit is configured to transfer data between a host system and a plurality of disk drives. The bandwidth can be more than 100 MB/s if the data path based on PCI (peripheral component interconnect). The organization of data stored on the disk array is similar to RAID 4. Data are striped on a plurality of disk, and each striping unit is equal to a track. I/O instructions are performed in parallel on the disk drives. An independent disk is used to store the parity information in the fast disk array architecture. By placing the parity generation circuit directly on the SCSI (or SCSI 2) bus, the parity information can be generated on the fly. It will affect little on the data writing in parallel on the other disks. The fast disk array architecture designed in the paper can meet the demands of the image storage.

Ruthenium-based, inert oxide electrodes for impregnating active materials in nickel plaques

NASA Astrophysics Data System (ADS)

Manoharan, R.; Uma, M.

Titanium electrodes coated with mixed ruthenium-iridium-titanium oxides are tested as inert counter electrodes for impregnating active materials in porous nickel plaques. The latter are to be used as the positive electrodes in nickel/cadmium cells. Weight losses and variations in bath voltage have been monitored while using these electrodes in the impregnation bath. A 2.85 Ah nickel/cadmium cell has been constructed using nickel electrodes developed by employing the coated electrodes of this study. The performances of these coated electrodes are compared with those of platinum electrodes that are currently employed by nickel/cadmium battery manufacturers. The results are found to be satisfactory.

THE EVOLUTION OF INNER DISK GAS IN TRANSITION DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoadley, K.; France, K.; McJunkin, M.

2015-10-10

Investigating the molecular gas in the inner regions of protoplanetary disks (PPDs) provides insight into how the molecular disk environment changes during the transition from primordial to debris disk systems. We conduct a small survey of molecular hydrogen (H{sub 2}) fluorescent emission, using 14 well-studied Classical T Tauri stars at two distinct dust disk evolutionary stages, to explore how the structure of the inner molecular disk changes as the optically thick warm dust dissipates. We simulate the observed Hi-Lyman α-pumped H{sub 2} disk fluorescence by creating a 2D radiative transfer model that describes the radial distributions of H{sub 2} emissionmore » in the disk atmosphere and compare these to observations from the Hubble Space Telescope. We find the radial distributions that best describe the observed H{sub 2} FUV emission arising in primordial disk targets (full dust disk) are demonstrably different than those of transition disks (little-to-no warm dust observed). For each best-fit model, we estimate inner and outer disk emission boundaries (r{sub in} and r{sub out}), describing where the bulk of the observed H{sub 2} emission arises in each disk, and we examine correlations between these and several observational disk evolution indicators, such as n{sub 13–31}, r{sub in,} {sub CO}, and the mass accretion rate. We find strong, positive correlations between the H{sub 2} radial distributions and the slope of the dust spectral energy distribution, implying the behavior of the molecular disk atmosphere changes as the inner dust clears in evolving PPDs. Overall, we find that H{sub 2} inner radii are ∼4 times larger in transition systems, while the bulk of the H{sub 2} emission originates inside the dust gap radius for all transitional sources.« less

Accumulation of methylglyoxal increases the advanced glycation end-product levels in DRG and contributes to lumbar disk herniation-induced persistent pain.

PubMed

Liu, Cui-Cui; Zhang, Xin-Sheng; Ruan, Yu-Ting; Huang, Zhu-Xi; Zhang, Su-Bo; Liu, Meng; Luo, Hai-Jie; Wu, Shao-Ling; Ma, Chao

2017-08-01

Lumbar disk herniation (LDH) with discogenic low back pain and sciatica is a common and complicated musculoskeletal disorder. The underlying mechanisms are poorly understood, and there are no effective therapies for LDH-induced pain. In the present study, we found that the patients who suffered from LDH-induced pain had elevated plasma methylglyoxal (MG) levels. In rats, implantation of autologous nucleus pulposus (NP) to the left lumbar 5 spinal nerve root, which mimicked LDH, induced mechanical allodynia, increased MG level in plasma and dorsal root ganglion (DRG), and enhanced the excitability of small DRG neurons (<30 μm in diameter). Intrathecal injection of MG also induced mechanical allodynia, and its application to DRG neurons ex vivo increased the number of action potentials evoked by depolarizing current pulses. Furthermore, inhibition of MG accumulation by aminoguanidine attenuated the enhanced excitability of small DRG neurons and the mechanical allodynia induced by NP implantation. In addition, NP implantation increased levels of advanced glycation end products (AGEs) in DRG, and intrathecal injection of MG-derived AGEs induced the mechanical allodynia and DRG neuronal hyperactivity. Intrathecal injection of MG also significantly increased the expression of AGEs in DRG. Importantly, scavenging of MG by aminoguanidine also attenuated the increase in AGEs induced by NP implantation. These results suggested that LDH-induced MG accumulation contributed to persistent pain by increasing AGE levels. Thus generation of AGEs from MG may represent a target for treatment of LDH-induced pain. NEW & NOTEWORTHY Our study demonstrates that methylglyoxal accumulation via increasing advanced glycation end-product levels in dorsal root ganglion contributes to the persistent pain induced by lumbar disk herniation, which proposed potential targets for the treatment of lumbar disk herniation-induced persistent pain. Copyright © 2017 the American Physiological Society.

Rechargeable nickel-3D zinc batteries: An energy-dense, safer alternative to lithium-ion.

PubMed

Parker, Joseph F; Chervin, Christopher N; Pala, Irina R; Machler, Meinrad; Burz, Michael F; Long, Jeffrey W; Rolison, Debra R

2017-04-28

The next generation of high-performance batteries should include alternative chemistries that are inherently safer to operate than nonaqueous lithium-based batteries. Aqueous zinc-based batteries can answer that challenge because monolithic zinc sponge anodes can be cycled in nickel-zinc alkaline cells hundreds to thousands of times without undergoing passivation or macroscale dendrite formation. We demonstrate that the three-dimensional (3D) zinc form-factor elevates the performance of nickel-zinc alkaline cells in three fields of use: (i) >90% theoretical depth of discharge (DOD Zn ) in primary (single-use) cells, (ii) >100 high-rate cycles at 40% DOD Zn at lithium-ion-commensurate specific energy, and (iii) the tens of thousands of power-demanding duty cycles required for start-stop microhybrid vehicles. Copyright © 2017, American Association for the Advancement of Science.

Addition of silicon improves oxidation resistance of nickel based superalloys

NASA Technical Reports Server (NTRS)

Lowell, C. E.; Miner, R. V., Jr.

1974-01-01

Specific weight changes of nickel-base superalloy B-1900 and B-1900 + 1% Si specimens were tested at 1273 K. B-1900 was losing weight at an increasing rate due to spalling of oxide scale while B-1900 + 1% Si was still gaining weight at low, nearly constant rate. Similar comparison in weight change was observed for specimens tested at 1373 K.

NGC 3516: Disk Diagnostics from a Windy BLSy1 in a High-State

NASA Astrophysics Data System (ADS)

Turner, Tracey Jane

2005-10-01

Recent advances have shown X-ray flux to be simply correlated with reflection-signatures from the disk and an associated wind. It appears two things are essential to observe the disk/wind: 1) catch the Seyfert in a high-state where disk/wind features show up strongly and 2) separate out reprocessing from distant gas to allow isolation of disk/wind features. NGC 3516 provides the ideal source for further study in this regard. The source is currently in a very high state, which we predict will lead to observable features from the disk and its wind. We request 210 ks XMM exposure on NGC 3156 with supporting Chandra time to test our prediction of flux-linked disk reflection and wind.

Creep and stress rupture of a mechanically alloyed oxide dispersion and precipitation strengthened nickel-base superalloy

NASA Technical Reports Server (NTRS)

Howson, T. E.; Tien, J. K.; Mervyn, D. A.

1980-01-01

The creep and stress rupture behavior of a mechanically alloyed oxide dispersion strengthened (ODS) and gamma-prime precipitation strengthened nickel-base alloy (alloy MA 6000E) was studied at intermediate and elevated temperatures. At 760 C, MA 6000E exhibits the high creep strength characteristic of nickel-base superalloys and at 1093 C the creep strength is superior to other ODS nickel-base alloys. The stress dependence of the creep rate is very sharp at both test temperatures and the apparent creep activation energy measured around 760 C is high, much larger in magnitude than the self-diffusion energy. Stress rupture in this large grain size material is transgranular and crystallographic cracking is observed. The rupture ductility is dependent on creep strain rate, but usually is low. These and accompanying microstructural results are discussed with respect to other ODS alloys and superalloys and the creep behavior is rationalized by invoking a recently-developed resisting stress model of creep in materials strengthened by second phase particles.

Coevolution of Binaries and Circumbinary Gaseous Disks

NASA Astrophysics Data System (ADS)

Fleming, David; Quinn, Thomas R.

2018-04-01

The recent discoveries of circumbinary planets by Kepler raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disk, and how the disk and binary interact. The central binary excites resonances in the surrounding protoplanetary disk that drive evolution in both the binary orbital elements and in the disk. To probe how these interactions impact both binary eccentricity and disk structure evolution, we ran N-body smooth particle hydrodynamics (SPH) simulations of gaseous protoplanetary disks surrounding binaries based on Kepler 38 for 10^4 binary orbital periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disk via a parametric instability and excite disk eccentricity growth. Eccentric binaries strongly couple to the disk causing eccentricity growth for both the disk and binary. Disks around sufficiently eccentric binaries strongly couple to the disk and develop an m = 1 spiral wave launched from the 1:3 eccentric outer Lindblad resonance (EOLR). This wave corresponds to an alignment of gas particle longitude of periastrons. We find that in all simulations, the binary semi-major axis decays due to dissipation from the viscous disk.

Method for decontamination of nickel-fluoride-coated nickel containing actinide-metal fluorides

DOEpatents

Windt, N.F.; Williams, J.L.

In one aspect, the invention comprises contacting nickel-fluoride-coated nickel with gaseous ammonia at a temperature effecting nickel-catalyzed dissociation thereof and effecting hydrogen-reduction of the nickel fluoride. The resulting nickel is heated to form a melt and a slag and to effect transfer of actinide metals from the melt into the slag. The melt and slag are then separated. In another aspect, nickel contianing nickel oxide and actinide metals is contacted with ammonia at a temperature effecting nickel-catalyzed dissociation to effect conversion of the nickel oxide to the metal. The resulting nickel is then melted and separated as described. In another aspect nickel-fluoride-coated nickel containing actinide-metal fluorides is contacted with both steam and ammonia. The resulting nickel then is melted and separated as described. The invention is characterized by higher nickel recovery, efficient use of ammonia, a substantial decrease in slag formation and fuming, and a valuable increase in the service life of the furnace liners used for melting.

Method for decontamination of nickel-fluoride-coated nickel containing actinide-metal fluorides

DOEpatents

Windt, Norman F.; Williams, Joe L.

1983-01-01

The invention is a process for decontaminating particulate nickel contaminated with actinide-metal fluorides. In one aspect, the invention comprises contacting nickel-fluoride-coated nickel with gaseous ammonia at a temperature effecting nickel-catalyzed dissociation thereof and effecting hydrogen-reduction of the nickel fluoride. The resulting nickel is heated to form a melt and a slag and to effect transfer of actinide metals from the melt into the slag. The melt and slag are then separated. In another aspect, nickel containing nickel oxide and actinide metals is contacted with ammonia at a temperature effecting nickel-catalyzed dissociation to effect conversion of the nickel oxide to the metal. The resulting nickel is then melted and separated as described. In another aspect nickel-fluoride-coated nickel containing actinide-metal fluorides is contacted with both steam and ammonia. The resulting nickel then is melted and separated as described. The invention is characterized by higher nickel recovery, efficient use of ammonia, a substantial decrease in slag formation and fuming, and a valuable increase in the service life of the furnace liners used for melting.

Research Advances on Pathways of Nickel-Induced Apoptosis

PubMed Central

Guo, Hongrui; Chen, Lian; Cui, Hengmin; Peng, Xi; Fang, Jing; Zuo, Zhicai; Deng, Junliang; Wang, Xun; Wu, Bangyuan

2015-01-01

High concentrations of nickel (Ni) are harmful to humans and animals. Ni targets a number of organs and produces multiple toxic effects. Apoptosis is important in Ni-induced toxicity of the kidneys, liver, nerves, and immune system. Apoptotic pathways mediated by reactive oxygen species (ROS), mitochondria, endoplasmic reticulum (ER), Fas, and c-Myc participate in Ni-induced cell apoptosis. However, the exact mechanism of apoptosis caused by Ni is still unclear. Understanding the mechanism of Ni-induced apoptosis may help in designing measures to prevent Ni toxicity. PMID:26703593

Herschel evidence for disk flattening or gas depletion in transitional disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keane, J. T.; Pascucci, I.; Espaillat, C.

Transitional disks are protoplanetary disks characterized by reduced near- and mid-infrared emission, with respect to full disks. This characteristic spectral energy distribution indicates the presence of an optically thin inner cavity within the dust disk believed to mark the disappearance of the primordial massive disk. We present new Herschel Space Observatory PACS spectra of [O I] 63.18 μm for 21 transitional disks. Our survey complements the larger Herschel GASPS program ({sup G}as in Protoplanetary Systems{sup )} by quadrupling the number of transitional disks observed with PACS in this wavelength. [O I] 63.18 μm traces material in the outer regions ofmore » the disk, beyond the inner cavity of most transitional disks. We find that transitional disks have [O I] 63.18 μm line luminosities ∼2 times fainter than their full disk counterparts. We self-consistently determine various stellar properties (e.g., bolometric luminosity, FUV excess, etc.) and disk properties (e.g., disk dust mass, etc.) that could influence the [O I] 63.18 μm line luminosity, and we find no correlations that can explain the lower [O I] 63.18 μm line luminosities in transitional disks. Using a grid of thermo-chemical protoplanetary disk models, we conclude that either transitional disks are less flared than full disks or they possess lower gas-to-dust ratios due to a depletion of gas mass. This result suggests that transitional disks are more evolved than their full disk counterparts, possibly even at large radii.« less

Studies of Circumstellar Disk Evolution

NASA Technical Reports Server (NTRS)

Hartmann, Lee W.

2004-01-01

Spitzer Space Telescope infrared data for our program on disk evolution has been taken (the main IRAC - 3-8 micron exposures; the 24 and 70 micron MIPS data are to come later). We now have deep maps in the four IRAC bands of the 3-Myr-old cluster Trumpler 37, and the 10-Myr-old cluster NGC 7160. Analysis of these data has now begun. We will be combining these data with our ground-based photometric and spectroscopic data to obtain a complete picture of disk frequency as a function of mass through this important age range, which spans the likely epoch of (giant) planet formation in most systems. Analysis of the SIRTF data, and follow-on ground-based spectroscopy on the converted MMT telescope using the wide-field, fiber-fed, multiobject spectrographs, Hectospec and Hectochelle, will be the major activity during the next year.Work was also performed on the following: protoplanetary disk mass accretion rates in very low-mass stars; the inner edge of T Tauri disks; accretion in intermediate-mass T Tauri stars (IMPS); and the near-infrared spectra of the rapidly-accreting protostellar disks FU Ori and V1057 Cyg.

Advanced Na-NiCl2 Battery Using Nickel-Coated Graphite with Core-Shell Microarchitecture.

PubMed

Chang, Hee-Jung; Canfield, Nathan L; Jung, Keeyoung; Sprenkle, Vincent L; Li, Guosheng

2017-04-05

Stationary electric energy storage devices (rechargeable batteries) have gained increasing prominence due to great market needs, such as smoothing the fluctuation of renewable energy resources and supporting the reliability of the electric grid. With regard to raw materials availability, sodium-based batteries are better positioned than lithium batteries due to the abundant resource of sodium in Earth's crust. However, the sodium-nickel chloride (Na-NiCl 2 ) battery, one of the most attractive stationary battery technologies, is hindered from further market penetration by its high material cost (Ni cost) and fast material degradation at its high operating temperature. Here, we demonstrate the design of a core-shell microarchitecture, nickel-coated graphite, with a graphite core to maintain electrochemically active surface area and structural integrity of the electron percolation pathway while using 40% less Ni than conventional Na-NiCl 2 batteries. An initial energy density of 133 Wh/kg (at ∼C/4) and energy efficiency of 94% are achieved at an intermediate temperature of 190 °C.

Magnetoplasmonic nanostructures based on nickel inverse opal slabs

NASA Astrophysics Data System (ADS)

Grunin, A. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Fedyanin, A. A.

2012-04-01

Nanostructured nickel surfaces representing periodically arranged spherical voids in a nickel film are obtained by electrochemical deposition through a self-assembled opaline template. Excitation of surface plasmon-polaritons (SPPs) on the surface of the sample is experimentally observed as the Wood's anomaly in the reflectance spectra. Transversal magneto-optical Kerr effect (TMOKE) spectra are measured at the different angles of incidence and azimuthal angles. The two- to-threefold enhancement of TMOKE caused by the excitation of mixed plasmons in two selected azimuthal configurations is observed.

THE SPITZER INFRARED SPECTROGRAPH SURVEY OF PROTOPLANETARY DISKS IN ORION A. I. DISK PROPERTIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, K. H.; Watson, Dan M.; Manoj, P.

2016-09-01

We present our investigation of 319 Class II objects in Orion A observed by Spitzer /IRS. We also present the follow-up observations of 120 of these Class II objects in Orion A from the Infrared Telescope Facility/SpeX. We measure continuum spectral indices, equivalent widths, and integrated fluxes that pertain to disk structure and dust composition from IRS spectra of Class II objects in Orion A. We estimate mass accretion rates using hydrogen recombination lines in the SpeX spectra of our targets. Utilizing these properties, we compare the distributions of the disk and dust properties of Orion A disks with thosemore » of Taurus disks with respect to position within Orion A (Orion Nebular Cluster [ONC] and L1641) and with the subgroups by the inferred radial structures, such as transitional disks (TDs) versus radially continuous full disks (FDs). Our main findings are as follows. (1) Inner disks evolve faster than the outer disks. (2) The mass accretion rates of TDs and those of radially continuous FDs are statistically significantly displaced from each other. The median mass accretion rate of radially continuous disks in the ONC and L1641 is not very different from that in Taurus. (3) Less grain processing has occurred in the disks in the ONC compared to those in Taurus, based on analysis of the shape index of the 10 μ m silicate feature ( F {sub 11.3}/ F {sub 9.8}). (4) The 20–31 μ m continuum spectral index tracks the projected distance from the most luminous Trapezium star, θ {sup 1} Ori C. A possible explanation is UV ablation of the outer parts of disks.« less

Physics-Based Spectra of Accretion Disks around Black Holes

NASA Technical Reports Server (NTRS)

Krolik, Julian H.

2005-01-01

The purpose of this grant was to begin the process of deriving the light output of accretion disks around black holes directly from the actual processes that inject heat into the accreting matter, rather than from guessed dependences of heating rate on physical parameters. At JHU, the effort has focussed so far on models of accretion onto "intermediate mass black holes", a possible class of black holes, examples of which may have recently been discovered in nearby galaxies. There, Krolik and his student (Yawei Hui) have computed stellar atmospheres for uniformly-heated disks around this class of black holes. Their models serve two purposes: they are the very first serious attempts to compute the spectrum from accreting black holes in this mass range; and a library of such models can be used later in this program as contrasts for those computed on the basis of real disk dynamics. The output from these local disk calculations has also been successfully coupled to a program that applies the appropriate relativistic transformations and computes photon trajectories in order to predict the spectrum received by observers located at different polar angles. The principal new result of these calculations is the discovery of potentially observable ionization edges of H-like C and O at frequencies near the peak in flux from these objects. Most of the grant money at UCSB was spent on supporting graduate student Shane Davis. In addition. some money was spent on supporting two other students: Ari Socrates (now a Hubble Fellow at Princeton), and Laura Melling. Davis spent the year constructing stellar atmosphere models of accretion disks appropriate for the high/soft (thermal) state of black hole X-ray binaries. As with AGN models published previously by our collaboration with NASA support. our models include a complete general relativistic treatment of both the disk structure and the propagation of photons from the disk to a distant observer. They also include all important

Lightweight nickel electrode for nickel hydrogen cells and batteries

NASA Technical Reports Server (NTRS)

Britton, D. L.

1986-01-01

The nickel electrode was identified as the heaviest component of the nickel hydrogen (NiH2) battery. The NASA Lewis Research Center is developing nickel electrodes for NiH2 battery devices which will be lighter in weight and have higher energy densities when cycled under a low Earth orbit regime at deep depths of discharge. Lightweight plaques are first exposed to 31 percent potassium hydroxide for 3 months to determine their suitability for use as electrode substrates from a chemical corrosion standpoint. Pore size distribution and porosity of the plaques are then measured. The lightweight plaques examined are nickel foam, nickel felt, nickel plastic and nickel plated graphite. Plaques are then electrochemically impregnated in an aqueous solution. Initial characterization tests of the impregnated plaques are performed at five discharge levels, C/2, 1.0 C, 1.37 C, 2.0C, and 2.74 C rates. Electrodes that passed the initial characterization screening test will be life cycle tested. Lightweight electrodes are approximately 30 to 50 percent lighter in weight than the sintered nickel electrode.

Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

NASA Technical Reports Server (NTRS)

Arakere, N. K.; Swanson, G.

2002-01-01

High cycle fatigue (HCF) induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Single crystal nickel turbine blades are being utilized in rocket engine turbopumps and jet engines throughout industry because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493, PWA 1484, RENE' N-5 and CMSX-4. These alloys play an important role in commercial, military and space propulsion systems. Single crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. The failure modes of single crystal turbine blades are complicated to predict due to the material orthotropy and variations in crystal orientations. Fatigue life estimation of single crystal turbine blades represents an important aspect of durability assessment. It is therefore of practical interest to develop effective fatigue failure criteria for single crystal nickel alloys and to investigate the effects of variation of primary and secondary crystal orientation on fatigue life. A fatigue failure criterion based on the maximum shear stress amplitude /Delta(sub tau)(sub max))] on the 24 octahedral and 6 cube slip systems, is presented for single crystal nickel superalloys (FCC crystal). This criterion reduces the scatter in uniaxial LCF test data considerably for PWA 1493 at 1200 F in air. Additionally, single crystal turbine blades used in the alternate advanced high-pressure fuel turbopump (AHPFTP/AT) are modeled using a large-scale three-dimensional finite element model. This finite element model is capable of accounting for material orthotrophy and variation in primary and secondary crystal orientation. Effects of variation in crystal orientation on blade stress response are studied based on 297

Effect of the Machining Processes on Low Cycle Fatigue Behavior of a Powder Metallurgy Disk

NASA Technical Reports Server (NTRS)

Telesman, J.; Kantzos, P.; Gabb, T. P.; Ghosn, L. J.

2010-01-01

A study has been performed to investigate the effect of various machining processes on fatigue life of configured low cycle fatigue specimens machined out of a NASA developed LSHR P/M nickel based disk alloy. Two types of configured specimen geometries were employed in the study. To evaluate a broach machining processes a double notch geometry was used with both notches machined using broach tooling. EDM machined notched specimens of the same configuration were tested for comparison purposes. Honing finishing process was evaluated by using a center hole specimen geometry. Comparison testing was again done using EDM machined specimens of the same geometry. The effect of these machining processes on the resulting surface roughness, residual stress distribution and microstructural damage were characterized and used in attempt to explain the low cycle fatigue results.

Modeling and Observations of Debris Disks

NASA Astrophysics Data System (ADS)

Moro-Martín, Amaya

2009-08-01

Debris disks are disks of dust observed around mature main sequence stars (generally A to K2 type). They are evidence that these stars harbor a reservoir of dust-producing plantesimals on spatial scales that are similar to those found for the small-body population of our solar system. Debris disks present a wide range of sizes and structural features (inner cavities, warps, offsets, rings, clumps) and there is growing evidence that, in some cases, they might be the result of the dynamical perturbations of a massive planet. Our solar system also harbors a debris disk and some of its properties resemble those of extra-solar debris disks. The study of these disks can shed light on the diversity of planetary systems and can help us place our solar system into context. This contribution is an introduction to the debris disk phenomenon, including a summary of debris disks main properties (§1-based mostly on results from extensive surveys carried out with Spitzer), and a discussion of what they can teach us about the diversity of planetary systems (§2).

Thin disk lasers: history and prospects

NASA Astrophysics Data System (ADS)

Speiser, Jochen

2016-04-01

During the early 1990s, collaboration between the German Aerospace Center and the University of Stuttgart started to work on the Thin Disk concept. The core idea behind the thin disk design is the use of a thin, disk-shaped active medium that is cooled through one of the flat faces of the disk. This ensures a large surface-to-volume ratio and therefore provides very efficient thermal management. Today, the thin disk concept is used in various commercial lasers - ranging from compact, efficient low power systems to multi-kW lasers, including cw lasers and also pulsed (femtosecond to nanosecond) oscillators and amplifiers. The whole development of the Thin Disk laser was and will be accompanied by numerical modeling and optimization of the thermal and thermo-mechanic behavior of the disk and also the heat sink structure, mostly based on finite element models. For further increasing the energy and efficiency of pulsed Thin Disk lasers, the effects of amplified spontaneous emission (ASE) are a core issue. Actual efforts are oriented towards short pulse and ultra-short pulse amplifiers with (multi-)kW average power or Joule-class Thin Disk amplifiers, but also on new designs for cw thin disk MOPA designs.

Vacuum Levels Needed to Simulate Internal Fatigue Crack Growth in Titanium Alloys and Nickel-Base Superalloys Thermaodynamic Conditioners (Preprint)

DTIC Science & Technology

2012-08-01

AFRL-RX-WP-TP-2012-0412 VACUUM LEVELS NEEDED TO SIMULATE INTERNAL FATIGUE CRACK GROWTH IN TITANIUM ALLOYS AND NICKEL - BASE SUPERALLOYS...LEVELS NEEDED TO SIMULATE INTERNAL FATIGUE CRACK GROWTH IN TITANIUM ALLOYS AND NICKEL - BASE SUPERALLOYS: THERMAODYNAMIC CONSIDERATIONS (PREPRINT) 5a...have examined fatigue growth of surface cracks in vacuum to simulate sub-surface growth in Ti- alloys and Ni - base superalloys. Even with the highest

A high-speed, large-capacity, 'jukebox' optical disk system

NASA Technical Reports Server (NTRS)

Ammon, G. J.; Calabria, J. A.; Thomas, D. T.

1985-01-01

Two optical disk 'jukebox' mass storage systems which provide access to any data in a store of 10 to the 13th bits (1250G bytes) within six seconds have been developed. The optical disk jukebox system is divided into two units, including a hardware/software controller and a disk drive. The controller provides flexibility and adaptability, through a ROM-based microcode-driven data processor and a ROM-based software-driven control processor. The cartridge storage module contains 125 optical disks housed in protective cartridges. Attention is given to a conceptual view of the disk drive unit, the NASA optical disk system, the NASA database management system configuration, the NASA optical disk system interface, and an open systems interconnect reference model.

Insight into the structure and mechanism of nickel-containing superoxide dismutase derived from peptide-based mimics.

PubMed

Shearer, Jason

2014-08-19

Nickel superoxide dismutase (NiSOD) is a nickel-containing metalloenzyme that catalyzes the disproportionation of superoxide through a ping-pong mechanism that relies on accessing reduced Ni(II) and oxidized Ni(III) oxidation states. NiSOD is the most recently discovered SOD. Unlike the other known SODs (MnSOD, FeSOD, and (CuZn)SOD), which utilize "typical" biological nitrogen and oxygen donors, NiSOD utilizes a rather unexpected ligand set. In the reduced Ni(II) oxidation state, NiSOD utilizes nitrogen ligands derived from the N-terminal amine and an amidate along with two cysteinates sulfur donors. These are unusual biological ligands, especially for an SOD: amine and amidate donors are underrepresented as biological ligands, whereas cysteinates are highly susceptible to oxidative damage. An axial histidine imidazole binds to nickel upon oxidation to Ni(III). This bond is long (2.3-2.6 Å) owing to a tight hydrogen-bonding network. All of the ligating residues to Ni(II) and Ni(III) are found within the first 6 residues from the NiSOD N-terminus. Thus, small nickel-containing metallopeptides derived from the first 6-12 residues of the NiSOD sequence can reproduce many of the properties of NiSOD itself. Using these nickel-containing metallopeptide-based NiSOD mimics, we have shown that the minimal sequence needed for nickel binding and reproduction of the structural, spectroscopic, and functional properties of NiSOD is H2N-HCXXPC. Insight into how NiSOD avoids oxidative damage has also been gained. Using small NiN2S2 complexes and metallopeptide-based mimics, it was shown that the unusual nitrogen donor atoms protect the cysteinates from oxidative damage (both one-electron oxidation and oxygen atom insertion reactions) by fine-tuning the electronic structure of the nickel center. Changing the nitrogen donor set to a bis-amidate or bis-amine nitrogen donor led to catalytically nonviable species owing to nickel-cysteinate bond oxidative damage. Only the amine

Plating Repair Of Nickel-Alloy Pressure Vessels

NASA Technical Reports Server (NTRS)

Ricklefs, Steve K.; Chagnon, Kevin M.

1989-01-01

Procedure for localized electrodeposition of nickel enables repair of small damaged nickel-based pressure vessels. Electrodeposition restores weakened areas of vessel wall to at least their former strength.

Moringa oleifera-based diet protects against nickel-induced hepatotoxicity in rats.

PubMed

Stephen Adeyemi, Oluyomi; Sokolayemji Aroge, Cincin; Adewumi Akanji, Musbau

2017-07-13

Multiple health-promoting effects have been attributed to the consumption of Moringa oleifera leaves, as part of diet without adequate scientific credence. This study evaluated the effect of M. oleifera-based diets on nickel (Ni) - induced hepatotoxicity in rats. Male rats assigned into six groups were given oral administration of 20 mg/kg body weight nickel sulfate in normal saline and either fed normal diet orM. oleifera-based diets for 21 days. All animals were sacrificed under anesthesia 24 hours after the last treatment. Ni exposure elevated the rat plasma activities of alanine transaminase, aspartate transaminase and alkaline phosphatase significantly. Ni exposure also raised the levels of triglyceride, total cholesterol and low-density lipoprotein cholesterol while depleting the high-density lipoprotein cholesterol concentration. Further, Ni exposure raised rat plasma malondialdehyde but depleted reduced glutathione concentrations. The histopathological presentations revealed inflammation and cellular degeneration caused by Ni exposure. We show evidence thatM. oleifera-based diets protected against Ni-induced hepatotoxicity by improving the rat liver function indices, lipid profile as well as restoring cellular architecture and integrity. Study lends credence to the health-promoting value ofM. oleifera as well as underscores its potential to attenuate hepatic injury.

Strainrange partitioning behavior of the nickel-base superalloys, Rene' 80 and in 100

NASA Technical Reports Server (NTRS)

Halford, G. R.; Nachtigall, A. J.

1978-01-01

A study was made to assess the ability of the method of Strainrange Partitioning (SRP) to both correlate and predict high-temperature, low cycle fatigue lives of nickel base superalloys for gas turbine applications. The partitioned strainrange versus life relationships for uncoated Rene' 80 and cast IN 100 were also determined from the ductility normalized-Strainrange Partitioning equations. These were used to predict the cyclic lives of the baseline tests. The life predictability of the method was verified for cast IN 100 by applying the baseline results to the cyclic life prediction of a series of complex strain cycling tests with multiple hold periods at constant strain. It was concluded that the method of SRP can correlate and predict the cyclic lives of laboratory specimens of the nickel base superalloys evaluated in this program.

Debris Disk Studies with the ngVLA

NASA Astrophysics Data System (ADS)

Wilner, David; Matthews, Brenda; Matra, Luca; Kennedy, Grant; Wyatt, Mark; Greaves, Jane

2018-01-01

We discuss the potential for the ngVLA to advance understanding of debris disks around main-sequence stars. Since the dust-producing planetesimals that replenish these disks through collisions persist only in stable regions like belts and resonances, their locations and physical properties encode essential information about the formation of exoplanetary systems and their dynamical evolution. Observations at long millimeter wavelengths can play a special role because the large grains that dominate the emission are faithful tracers of the dust-producing planetesimals, unlike small grains seen at shorter wavelengths that are rapidly redistributed by stellar radiation and winds. Sensitive observations of debris disks with the ngVLA can (1) reveal structures resulting from otherwise inaccessible planets on wide orbits, (2) test collisional models using spectral slopes to constrain mm/cm grain size distributions, and (3) for select sources, probe the water content of exocomets using the 21 cm HI line.

Life Prediction of Turbine Blade Nickel Base Superalloy Single Crystals.

DTIC Science & Technology

1986-08-01

mechanical properties between single crystals and the DS version of Mar-M200. Soon it was recognized again through the mechanical property - structure ... property achievements demonstrated by screening and simulated engine tests. 1 Single crystals are the results of extensive investigation on the mechanical ...behavior, (especially fatigue and creep) of, and the structure - property correlations in the equiaxed and directionally solidified (DS) nickel-base

The Effects of Protostellar Disk Turbulence on CO Emission Lines: A Comparison Study of Disks with Constant CO Abundance versus Chemically Evolving Disks

NASA Astrophysics Data System (ADS)

Yu, Mo; Evans, Neal J., II; Dodson-Robinson, Sarah E.; Willacy, Karen; Turner, Neal J.

2017-12-01

Turbulence is the leading candidate for angular momentum transport in protoplanetary disks and therefore influences disk lifetimes and planet formation timescales. However, the turbulent properties of protoplanetary disks are poorly constrained observationally. Recent studies have found turbulent speeds smaller than what fully-developed MRI would produce (Flaherty et al.). However, existing studies assumed a constant CO/H2 ratio of 10-4 in locations where CO is not frozen-out or photo-dissociated. Our previous studies of evolving disk chemistry indicate that CO is depleted by incorporation into complex organic molecules well inside the freeze-out radius of CO. We consider the effects of this chemical depletion on measurements of turbulence. Simon et al. suggested that the ratio of the peak line flux to the flux at line center of the CO J = 3-2 transition is a reasonable diagnostic of turbulence, so we focus on that metric, while adding some analysis of the more complex effects on spatial distribution. We simulate the emission lines of CO based on chemical evolution models presented in Yu et al., and find that the peak-to-trough ratio changes as a function of time as CO is destroyed. Specifically, a CO-depleted disk with high turbulent velocity mimics the peak-to-trough ratios of a non-CO-depleted disk with lower turbulent velocity. We suggest that disk observers and modelers take into account the possibility of CO depletion when using line profiles or peak-to-trough ratios to constrain the degree of turbulence in disks. Assuming that {CO}/{{{H}}}2={10}-4 at all disk radii can lead to underestimates of turbulent speeds in the disk by at least 0.2 km s-1.

Comparison of nickel release in solutions used for the identification of water-soluble nickel exposures and in synthetic lung fluids.

PubMed

Oller, Adriana R; Cappellini, Danielle; Henderson, Rayetta G; Bates, Hudson K

2009-04-01

Chemical speciation of workplace nickel exposures is critical because nickel-containing substances often differ in toxicological properties. Exposure matrices based on leaching methods have been used to ascertain which chemical forms of nickel are primarily associated with adverse respiratory effects after inhalation. Misjudgments in the relative proportion of each of the main fractions of nickel in workplace exposures could translate into possible misattributions of risk to the various forms of nickel. This preliminary study looked at the efficiency of the first step of the Zatka leaching method for accurately assessing the 'water-soluble' fraction of several substances present in nickel production operations, compared to leaching in synthetic lung fluid. The present results demonstrate that for nickel sulfate or chloride, the current Zatka solution is adequate to assess the 'water-soluble' fraction. However, when sparingly water-soluble compounds like nickel carbonates or water-insoluble substances like nickel subsulfide and fine metallic nickel powders are present, the first step of the Zatka method can greatly over estimate the amount of nickel that could be released in pure water. In contrast, the releases of nickel from nickel carbonate, nickel subsulfide, and nickel metal powders in pure water are consistent with their releases in synthetic lung fluid, indicating that deionized water is a better leaching solution to estimate the biologically relevant 'water-soluble' nickel fraction of workplace exposures. Exposure matrices relying mostly on the Zatka speciation method to estimate the main forms of nickel need to be re-evaluated to account for any possible misattributions of risk.

A new chromium carbide-based tribological coating for use to 900 C with particular reference to the Stirling engine

NASA Technical Reports Server (NTRS)

Sliney, Harold E.

1986-01-01

A new chromium carbide-based coating (PS 200) is described. This coating is shown to have good friction and wear properties over a wide temperature range. A nickel alloy-bonded chromium carbide coating was used as a baseline material for comparison with experimentally formulated coatings. Coatings were plasma sprayed onto metal disks, then diamond ground to a thickness of 0.025 cm. Friction and wear were determined using a pin on disk tribometer at temperatures from 25 to 900 C in hydrogen, helium, and air. Pin materials included several metallic alloys and silicon carbide. It was found that appropriate additions of metallic silver and of barium fluoride/calcium fluoride eutectic to the baseline carbide composition significantly reduced friction coefficients while preserving, and in some cases, even enhancing wear resistance. The results of this study demonstrate that PS 200 is a promising coating composition to consider for high temperature aerospace and advanced heat engine applications. The excellent results in hydrogen make this coating of particular interest for use in the Stirling engine.

Exploring Our Galaxy's Thick Disk

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-12-01

What is the structure of the Milky Ways disk, and how did it form? A new study uses giant stars to explore these questions.A View from the InsideSchematic showing an edge-on, not-to-scale view of what we think the Milky Ways structurelookslike. The thick disk is shown in yellow and the thin disk is shown in green. [Gaba p]Spiral galaxies like ours are often observed to have disks consisting of two components: a thin disk that lies close to the galactic midplane, and a thick disk that extends above and below this. Past studies have suggested that the Milky Ways disk hosts the same structure, but our position embedded in the Milky Way makes this difficult to confirm.If we can measure the properties of a broad sample of distant tracer stars and use this to better understand the construction of the Milky Ways disk, then we can start to ask additional questions like, how did the disk components form? Formation pictures for the thick disk generally fall into two categories:Stars in the thick disk formed within the Milky Way either in situ or by migrating to their current locations.Stars in the thick disk formed in satellite galaxies around the Milky Way and then accreted when the satellites were disrupted.Scientists Chengdong Li and Gang Zhao (NAO Chinese Academy of Sciences, University of Chinese Academy of Sciences) have now used observations of giant stars which can be detected out to great distances due to their brightness to trace the properties of the Milky Ways thick disk and address the question of its origin.Best fits for the radial (top) and vertical (bottom) metallicity gradients of the thick-disk stars. [Adapted from Li Zhao 2017]Probing OriginsLi and Zhao used data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) in China to examine a sample of 35,000 giant stars. The authors sorted these stars into different disk components halo, thin disk, and thick disk based on their kinematic properties, and then explored how the orbital and

Cyclic Oxidation and Hot Corrosion Behavior of Nickel-Iron-Based Superalloy

NASA Astrophysics Data System (ADS)

Chellaganesh, D.; Adam Khan, M.; Winowlin Jappes, J. T.; Sathiyanarayanan, S.

2018-01-01

The high temperature oxidation and hot corrosion behavior of nickel-iron-based superalloy are studied at 900 ° and 1000 °C. The significant role of alloying elements with respect to the exposed medium is studied in detail. The mass change per unit area was catastrophic for the samples exposed at 1000 °C and gradual increase in mass change was observed at 900 °C for both the environments. The exposed samples were further investigated with SEM, EDS and XRD analysis to study the metallurgical characteristics. The surface morphology has expressed the in situ nature of the alloy and its affinity toward the environment. The EDS and XRD analysis has evidently proved the presence of protective oxides formation on prolonged exposure at elevated temperature. The predominant oxide formed during the exposure at high temperature has a major contribution toward the protection of the samples. The nickel-iron-based superalloy is less prone to oxidation and hot corrosion when compared to the existing alloy in gas turbine engine simulating marine environment.

Amorphous nickel boride membrane on a platinum-nickel alloy surface for enhanced oxygen reduction reaction.

PubMed

He, Daping; Zhang, Libo; He, Dongsheng; Zhou, Gang; Lin, Yue; Deng, Zhaoxiang; Hong, Xun; Wu, Yuen; Chen, Chen; Li, Yadong

2016-08-09

The low activity of the oxygen reduction reaction in polymer electrolyte membrane fuel cells is a major barrier for electrocatalysis, and hence needs to be optimized. Tuning the surface electronic structure of platinum-based bimetallic alloys, a promising oxygen reduction reaction catalyst, plays a key role in controlling its interaction with reactants, and thus affects the efficiency. Here we report that a dealloying process can be utilized to experimentally fabricate the interface between dealloyed platinum-nickel alloy and amorphous nickel boride membrane. The coating membrane works as an electron acceptor to tune the surface electronic structure of the platinum-nickel catalyst, and this composite catalyst composed of crystalline platinum-nickel covered by amorphous nickel boride achieves a 27-times enhancement in mass activity relative to commercial platinum/carbon at 0.9 V for the oxygen reduction reaction performance. Moreover, this interactional effect between a crystalline surface and amorphous membrane can be readily generalized to facilitate the 3-times higher catalytic activity of commercial platinum/carbon.

Multiwavelength search for protoplanetary disks

NASA Technical Reports Server (NTRS)

Neuhaeuser, Ralph; Schmidt-Kaler, Theodor

1994-01-01

Infrared emission of circumstellar dust was observed for almost one hundred T Tauri stars. This dust is interpreted to be part of a protoplanetary disk orbiting the central star. T Tauri stars are young stellar objects and evolve into solar type stars. Planets are believed to form in these disks. The spectral energy distribution of a disk depends on its temperature profile. Different disk regions emit at different wavelengths. The disk-star boundary layer is hot and emits H(alpha) radiation. Inner disk regions at around 1 AU with a temperature of a few hundred Kelvin can be probed in near infrared wavelength regimes. Outer disk regions at around 100 AU distance from the star are colder and emit far infrared and sub-millimeter radiation. Also, X-ray emission from the stellar surface can reveal information on disk properties. Emission from the stellar surface and the boundary layer may be shielded by circumstellar gas and dust. T Tauri stars with low H(alpha) emission, i.e. no boundary layer, show stronger X-ray emission than classical T Tauri stars, because the inner disk regions of weak emission-line T Tauri stars may be clear of material. In this paper, first ROSAT all sky survey results on the X-ray emission of T Tauri stars and correlations between X-ray luminosity and properties of T Tauri disks are presented. Due to atmospheric absorption, X-ray and most infrared observations cannot be carried out on Earth, but from Earth orbiting satellites (e.g. IRAS, ROSAT, ISO) or from lunar based observatories, which would have special advantages such as a stable environment.

ALMA Survey of Lupus Protoplanetary Disks. II. Gas Disk Radii

NASA Astrophysics Data System (ADS)

Ansdell, M.; Williams, J. P.; Trapman, L.; van Terwisga, S. E.; Facchini, S.; Manara, C. F.; van der Marel, N.; Miotello, A.; Tazzari, M.; Hogerheijde, M.; Guidi, G.; Testi, L.; van Dishoeck, E. F.

2018-05-01

We present Atacama Large Millimeter/Sub-Millimeter Array (ALMA) Band 6 observations of a complete sample of protoplanetary disks in the young (∼1–3 Myr) Lupus star-forming region, covering the 1.33 mm continuum and the 12CO, 13CO, and C18O J = 2–1 lines. The spatial resolution is ∼0.″25 with a medium 3σ continuum sensitivity of 0.30 mJy, corresponding to M dust ∼ 0.2 M ⊕. We apply Keplerian masking to enhance the signal-to-noise ratios of our 12CO zero-moment maps, enabling measurements of gas disk radii for 22 Lupus disks; we find that gas disks are universally larger than millimeter dust disks by a factor of two on average, likely due to a combination of the optically thick gas emission and the growth and inward drift of the dust. Using the gas disk radii, we calculate the dimensionless viscosity parameter, α visc, finding a broad distribution and no correlations with other disk or stellar parameters, suggesting that viscous processes have not yet established quasi-steady states in Lupus disks. By combining our 1.33 mm continuum fluxes with our previous 890 μm continuum observations, we also calculate the millimeter spectral index, α mm, for 70 Lupus disks; we find an anticorrelation between α mm and millimeter flux for low-mass disks (M dust ≲ 5), followed by a flattening as disks approach α mm ≈ 2, which could indicate faster grain growth in higher-mass disks, but may also reflect their larger optically thick components. In sum, this work demonstrates the continuous stream of new insights into disk evolution and planet formation that can be gleaned from unbiased ALMA disk surveys.

Fabrication of tungsten wire reinforced nickel-base alloy composites

NASA Technical Reports Server (NTRS)

Brentnall, W. D.; Toth, I. J.

1974-01-01

Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

The protoplanetary disk of FT Tauri: multiwavelength data analysis and modeling

NASA Astrophysics Data System (ADS)

Garufi, A.; Podio, L.; Kamp, I.; Ménard, F.; Brittain, S.; Eiroa, C.; Montesinos, B.; Alonso-Martínez, M.; Thi, W. F.; Woitke, P.

2014-07-01

Context. Investigating the evolution of protoplanetary disks is crucial for our understanding of star and planet formation. There have been several theoretical and observational studies in past decades to advance this knowledge. The launch of satellites operating at infrared wavelengths, such as the Spitzer Space Telescope and the Herschel Space Observatory, has provided important tools for investigating the properties of circumstellar disks. Aims: FT Tauri is a young star in the Taurus star forming region that was included in a number of spectroscopic and photometric surveys. We investigate the properties of the star, the circumstellar disk, and the accretion/ejection processes and propose a consistent gas and dust model also as a reference for future observational studies. Methods: We performed a multiwavelength data analysis to derive the basic stellar and disk properties, as well as mass accretion/outflow rate from TNG/DOLoRes, WHT/LIRIS, NOT/NOTCam, Keck/NIRSpec, and Herschel/PACS spectra. From the literature, we compiled a complete spectral energy distribution. We then performed detailed disk modeling using the MCFOST and ProDiMo codes. Multiwavelength spectroscopic and photometric measurements were compared with the reddened predictions of the codes in order to constrain the disk properties. Results: We have determined the stellar mass (~ 0.3 M⊙), luminosity (~ 0.35 L⊙), and age (~ 1.6 Myr), as well as the visual extinction of the system (1.8 mag). We estimate the mass accretion rate (~ 3 × 10-8 M⊙/yr) to be within the range of accreting objects in Taurus. The evolutionary state and the geometric properties of the disk are also constrained. The radial extent (0.05 to 200 AU), flaring angle (power law with exponent =1.15), and mass (0.02 M⊙) of the circumstellar disk are typical of a young primordial disk. This object can serve as a benchmark for primordial disks with significant mass accretion rate, high gas content, and typical size. Based on

A new chromium carbide-based tribological coating for use to 900 deg C with particular reference to the Stirling engine

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1986-01-01

A new chromium carbide-based coating (PS 200) is described. This coating is shown to have good friction and wear properties over a wide temperature range. A nickel alloy-bonded chromium carbide coating was used as a baseline material for comparison with experimental formulated coatings. Coatings were plasma sprayed onto metal disks, then diamond ground to a thickness of 0.025 cm. Friction and wear were determined using a pin on disk tribometer at temperatures from 25 to 900 C in hydrogen, helium, and air. Pin materials included several metallic alloys and silicon carbide. It was found that appropriate additions of metallic silver and of barium fluoride/calcium fluoride eutectic to the baseline carbide composition significantly reduced friction coefficients while preserving, and in some cases, even enhancing wear resistance. The results of this study demonstrate that PS 200 is a promising coating composition to consider for high temperature aerospace and advanced heat engine applications. The excellent results in hydrogen make this coating of particular interest for use in the Stirling engine.

Physical Metallurgy of Rene 65, a Next-Generation Cast and Wrought Nickel Superalloy for use in Aero Engine Components

NASA Astrophysics Data System (ADS)

Wessman, Andrew Ezekiel

Advancements in the design of turbine engines are in large part made possible by advancements in the capability of nickel based superalloys. Greater temperature and stress capabilities in these materials allow for increased operating temperatures and speeds in the engines, which lead to increased fuel efficiency. Early jet engines were built using austenitic stainless steels, and moved to cast and wrought nickel alloys as higher temperatures were required. By the 1970s, the state of the art nickel superalloy was Inconel 718, which is strengthened by the Ni3Nb phase known as gamma double prime. This alloy performs well and is still in heavy use in turbine engines at temperatures up to approximately 650°C (1200°F), but at higher temperatures the main strengthening precipitate phase, gamma', is thermodynamically unstable, resulting in a loss of strength following exposure to high temperature. Further advancements in nickel superalloys generally involved alloys strengthened by the Ni3Al phase known as gamma'. This precipitate is stable at much higher temperatures, but due to compositional segregation in cast and wrought processing, these alloys were processed using powder metallurgy methods, at considerable economic cost. This study will examine the microstructure of a next generation cast and wrought nickel superalloy that can provide increased temperature capability relative to Inconel 718, at lower cost than powder metallurgy superalloys. The alloy chemistry is similar to that of the powder metallurgy superalloy Rene 88DT, with changes to make it better suited for cast and wrought processing and with a different processing route from billet processing through to final part heat treatment. It is a gamma prime strengthened superalloy. The alloy has been recently introduced into service in turbine engines by GE Aviation as the alloy Rene 65, the composition of which is shown below. In this work, the following has been shown: • Rene 65 gamma' precipitate structure

A nanometallic nickel-coated, glass-fibre-based structural health monitoring system for polymer composites

NASA Astrophysics Data System (ADS)

Balaji, R.; Sasikumar, M.

2017-09-01

Glass-fibre-reinforced polymer matrix composites are widely used in various industries because of their unique high strength to weight ratio. Unlike metals, strain-induced and damage states of composites are complicated to predict under real-time loading due to their anisotropic nature. With that focus, a piezoresistive nanomaterial-based structural health monitoring system for laminated polymer composites is proposed to measure the strain induced in the composite under real-time loading. Nanometallic nickel-coated glass fibres are embedded into the polymer composites to monitor the strain and damage induced in them. The nanometallic nickel is coated over the glass fibre by a dip coating technique using epoxy as the binding agent. A microcontroller-based electrical resistance measurement system is used to measure the piezoresistive variation in the coated glass fibre under real-time loading. Using the piezoresistance variation of the embedded nanometallic nickel-coated glass fibre, the real-time strain and damage induced in the composite can be correlated. The piezoresistive response of the coated glass fibre is descibed in two phases, the deformation phase and the failure phase, which clearly show the various states of strain and damage induced in the composites.

Transitional Disks Associated with Intermediate-Mass Stars: Results of the SEEDS YSO Survey

NASA Technical Reports Server (NTRS)

Grady, C.; Fukagawa, M.; Maruta, Y.; Ohta, Y.; Wisniewski, J.; Hashimoto, J.; Okamoto, Y.; Momose, M.; Currie, T.; McElwain, M.;

NICKEL PLATING PROCESS

DOEpatents

Hoover, T.B.; Zava, T.E.

1959-05-12

A simplified process is presented for plating nickel by the vapor decomposition of nickel carbonyl. In a preferred form of the invention a solid surface is nickel plated by subjecting the surface to contact with a mixture containing by volume approximately 20% nickel carbonyl vapor, 2% hydrogen sulfide and .l% water vapor or 1% oxygen and the remainder carbon dioxide at room temperature until the desired thickness of nickel is obtained. The advantage of this composition over others is that the normally explosive nickel carbonyl is greatly stabilized.

Lightweight fibrous nickel electrodes for nickel-hydrogen batteries

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1989-01-01

The NASA Lewis Research Center is currently developing nickel electrodes for nickel-hydrogen batteries. These electrodes are lighter in weight and have higher energy densities than the heavier state-of-the-art sintered nickel electrodes. Lightweight fibrous materials or plaques are used as conductive supports for the nickel hydroxide active material. These materials are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. Evaluation is performed in half cells structured in the bipolar configuration. Initial performance tests include capacity measurements at five discharge levels, C/2, 1.0C, 1.37C, 2.0C, and 2.74C. The electrodes that pass the initial tests are life cycle-tested in a low Earth orbit regime at 80 percent depth of discharge.

The AMBRE project: The thick thin disk and thin thick disk of the Milky Way

NASA Astrophysics Data System (ADS)

Hayden, M. R.; Recio-Blanco, A.; de Laverny, P.; Mikolaitis, S.; Worley, C. C.

2017-11-01

We analyze 494 main sequence turnoff and subgiant stars from the AMBRE:HARPS survey. These stars have accurate astrometric information from Gaia DR1, providing reliable age estimates with relative uncertainties of ±1 or 2 Gyr and allowing precise orbital determinations. The sample is split based on chemistry into a low-[Mg/Fe] sequence, which are often identified as thin disk stellar populations, and high-[Mg/Fe] sequence, which are often associated with thick disk stellar populations. We find that the high-[Mg/Fe] chemical sequence has extended star formation for several Gyr and is coeval with the oldest stars of the low-[Mg/Fe] chemical sequence: both the low- and high-[Mg/Fe] sequences were forming stars at the same time. We find that the high-[Mg/Fe] stellar populations are only vertically extended for the oldest, most-metal poor and highest [Mg/Fe] stars. When comparing vertical velocity dispersion for the low- and high-[Mg/Fe] sequences, the high-[Mg/Fe] sequence has lower vertical velocity dispersion than the low-[Mg/Fe] sequence for stars of similar age. This means that identifying either group as thin or thick disk based on chemistry is misleading. The stars belonging to the high-[Mg/Fe] sequence have perigalacticons that originate in the inner disk, while the perigalacticons of stars on the low-[Mg/Fe] sequence are generally around the solar neighborhood. From the orbital properties of the stars, the high-[Mg/Fe] and low-[Mg/Fe] sequences are most likely a reflection of the chemical enrichment history of the inner and outer disk populations, respectively; radial mixing causes both populations to be observed in situ at the solar position. Based on these results, we emphasize that it is important to be clear in defining what populations are being referenced when using the terms thin and thick disk, and that ideally the term thick disk should be reserved for purely geometric definitions to avoid confusion and be consistent with definitions in external

Recent developments in nickel electrode analysis

NASA Technical Reports Server (NTRS)

Whiteley, Richard V.; Daman, M. E.; Kaiser, E. Q.

1991-01-01

Three aspects of nickel electrode analysis for Nickel-Hydrogen and Nickel-Cadmium battery cell applications are addressed: (1) the determination of active material; (2) charged state nickel (as NiOOH + CoOOH); and (3) potassium ion content in the electrode. Four deloading procedures are compared for completeness of active material removal, and deloading conditions for efficient active material analyses are established. Two methods for charged state nickel analysis are compared: the current NASA procedure and a new procedure based on the oxidation of sodium oxalate by the charged material. Finally, a method for determining potassium content in an electrode sample by flame photometry is presented along with analytical results illustrating differences in potassium levels from vendor to vendor and the effects of stress testing on potassium content in the electrode. The relevance of these analytical procedures to electrode performance is reviewed.

Hubble and Spitzer Space Telescope Observations of the Debris Disk around the nearby K Dwarf HD 92945

NASA Astrophysics Data System (ADS)

Golimowski, D. A.; Krist, J. E.; Stapelfeldt, K. R.; Chen, C. H.; Ardila, D. R.; Bryden, G.; Clampin, M.; Ford, H. C.; Illingworth, G. D.; Plavchan, P.; Rieke, G. H.; Su, K. Y. L.

2011-07-01

albedo suggest a large population of submicron-sized grains. If grains smaller than a few microns are absent, then stellar radiation pressure may be the cause only if the dust is composed of highly absorptive materials like graphite. The dynamical causes of the sharply edged inner ring and outer disk are unclear, but recent models of dust creation and transport in the presence of migrating planets support the notion that the disk indicates an advanced state of planet formation around HD 92945. Based in part on guaranteed observing time awarded by the National Aeronautics and Space Administration (NASA) to the Advanced Camera for Surveys Investigation Definition Team and the Multiband Imaging Photometer for Spitzer Instrument Team.

Dwell Notch Low Cycle Fatigue Behavior of a Powder Metallurgy Nickel Disk Alloy

NASA Technical Reports Server (NTRS)

Telesman, J.; Gabb, T. P.; Yamada, Y.; Ghosn, L. J.; Jayaraman, N.

2012-01-01

A study was conducted to determine the processes which govern dwell notch low cycle fatigue (NLCF) behavior of a powder metallurgy (P/M) ME3 disk superalloy. The emphasis was placed on the environmentally driven mechanisms which may embrittle the highly stressed notch surface regions and reduce NLCF life. In conjunction with the environmentally driven notch surface degradation processes, the visco-plastic driven mechanisms which can significantly change the notch root stresses were also considered. Dwell notch low cycle fatigue testing was performed in air and vacuum on a ME3 P/M disk alloy specimens heat treated using either a fast or a slow cooling rate from the solutioning treatment. It was shown that dwells at the minimum stress typically produced a greater life debit than the dwells applied at the maximum stress, especially for the slow cooled heat treatment. Two different environmentally driven failure mechanisms were identified as the root cause of early crack initiation in the min dwell tests. Both of these failure mechanisms produced mostly a transgranular crack initiation failure mode and yet still resulted in low NLCF fatigue lives. The lack of stress relaxation during the min dwell tests produced higher notch root stresses which caused early crack initiation and premature failure when combined with the environmentally driven surface degradation mechanisms. The importance of environmental degradation mechanisms was further highlighted by vacuum dwell NLCF tests which resulted in considerably longer NLCF lives, especially for the min dwell tests.

Milky Way's thick and thin disk: Is there a distinct thick disk?

NASA Astrophysics Data System (ADS)

Kawata, D.; Chiappini, C.

2016-09-01

This article is based on our discussion session on Milky Way models at the 592 WE-Heraeus Seminar, Reconstructing the Milky Way's History: Spectroscopic Surveys, Asteroseismology and Chemodynamical Models. The discussion focused on the following question: "Are there distinct thick and thin disks?". The answer to this question depends on the definition one adopts for thin and thick disks. The participants of this discussion converged to the idea that there are at least two different types of disks in the Milky Way. However, there are still important open questions on how to best define these two types of disks (chemically, kinematically, geometrically or by age?). The question of what is the origin of the distinct disks remains open. The future Galactic surveys which are highlighted in this conference should help us answering these questions. The almost one-hour debate involving researchers in the field representing different modelling approaches (Galactic models such as TRILEGAL, Besançon and Galaxia, chemical evolution models, extended distribution functions method, chemodynamics in the cosmological context, and self-consistent cosmological simulations) illustrated how important is to have all these parallel approaches. All approaches have their advantages and shortcomings (also discussed), and different approaches are useful to address specific points that might help us answering the more general question above.

The HD 163296 Circumstellar Disk in Scattered Light: Evidence of Time-Variable Self-Shadowing

NASA Technical Reports Server (NTRS)

Wisniewski, John P.; Clampin, Mark; Grady, Carol A.; Ardila, David R.; Ford, Holland C.; Golimowski, David A.; Illingworth, Garth D.; Krist, John E.

2008-01-01

We present the first multi-color view of the scattered light disk of the Herbig Ae star HD 163296, based on coronagraphic observations from the Hubble Space Telescope Advanced Camera for Surveys (ACS). Radial profile fits of the surface brightness along the disk's semi-major axis indicates that the disk is not continuously flared, and extends to approx.540 AU. The disk's color (V-I)=1.1 at a radial distance of 3.5" is redder than the observed stellar color (V-I)=0.15. This red disk color might be indicative of either an evolution in the grain size distribution (i.e. grain growth) and/or composition, both of which would be consistent with the observed non-flared geometry of the outer disk. We also identify a single ansa morphological structure in our F435W ACS data, which is absent from earlier epoch F606W and F814W ACS data, but corresponds to one of the two ansa observed in archival HST STIS coronagraphic data. Following transformation to similar band-passes, we find that the scattered light disk of HD 163296 is 1 mag arcsec(sup -2) fainter at 3.5" in the STIS data than in the ACS data. Moreover, variations are seen in (i) the visibility of the ansa(e) structures, in (ii) the relative surface brightness of the ansa(e) structures, and in (iii) the (known) intrinsic polarization of the system. These results indicate that the scattered light from the HD 163296 disk is variable. We speculate that the inner disk wall, which Sitko et al. suggests has a variable scale height as diagnosed by near-IR SED variability, induces variable self-shadowing of the outer disk. We further speculate that the observed surface brightness variability of the ansa(e) structures may indicate that the inner disk wall is azimuthally asymmetric. Subject headings: circumstellar matter - stars: individual (HD 163296) - planetary systems: formation - planetary systems: protoplanetary disks

Radiotherapy supporting system based on the image database using IS&C magneto-optical disk

NASA Astrophysics Data System (ADS)

Ando, Yutaka; Tsukamoto, Nobuhiro; Kunieda, Etsuo; Kubo, Atsushi

1994-05-01

Since radiation oncologists make the treatment plan by prior experience, information about previous cases is helpful in planning the radiation treatment. We have developed an supporting system for the radiation therapy. The case-based reasoning method was implemented in order to search old treatments and images of past cases. This system evaluates similarities between the current case and all stored cases (case base). The portal images of the similar cases can be retrieved for reference images, as well as treatment records which show examples of the radiation treatment. By this system radiotherapists can easily make suitable plans of the radiation therapy. This system is useful to prevent inaccurate plannings due to preconceptions and/or lack of knowledge. Images were stored into magneto-optical disks and the demographic data is recorded to the hard disk which is equipped in the personal computer. Images can be displayed quickly on the radiotherapist's demands. The radiation oncologist can refer past cases which are recorded in the case base and decide the radiation treatment of the current case. The file and data format of magneto-optical disk is the IS&C format. This format provides the interchangeability and reproducibility of the medical information which includes images and other demographic data.

Materials for Advanced Turbine Engines. Volume 1; Power Metallurgy Rene 95 Rotating Turbine Engine Parts

NASA Technical Reports Server (NTRS)

Pfouts, W. R.; Shamblen, C. E.; Mosier, J. S.; Peebles, R. E.; Gorsler, R. W.

1979-01-01

An attempt was made to improve methods for producing powder metallurgy aircraft gas turbine engine parts from the nickel base superalloy known as Rene 95. The parts produced were the high pressure turbine aft shaft for the CF6-50 engine and the stages 5 through 9 compressor disk forgings for the CFM56/F101 engines. A 50% cost reduction was achieved as compared to conventional cast and wrought processing practices. An integrated effort involving several powder producers and a major forging source were included.

An improved turbine disk design to increase reliability of aircraft jet engines

NASA Technical Reports Server (NTRS)

Barack, W. N.; Domas, P. A.

1976-01-01

An analytical study was performed on a novel disk design to replace the existing high-pressure turbine, stage 1 disk on the CF6-50 turbofan engine. Preliminary studies were conducted on seven candidate disk design concepts. An integral multidisk design with bore entry of the turbine blade cooling air was selected as the improved disk design. This disk has the unique feature of being redundant such that if one portion of the disk would fail, the remaining portion would prevent the release of large disk fragments from the turbine system. Low cycle fatigue lives, initial defect propagation lives, burst speed, and the kinetic energies of probable disk fragment configurations were calculated, and comparisons were made with the existing disk, both in its current material, IN 718, and with the substitution of an advanced alloy, Rene 95. The design for redundancy approach which necessitated the addition of approximately 44.5 kg (98 lb) to the design disk substantially improved the life of the disk. The life to crack initiation was increased from 30,000 cycles to more than 100,000 cycles. The cycles to failure from initial defect propagation were increased from 380 cycles to 1564 cycles. Burst speed was increased from 126 percent overspeed to 149 percent overspeed. Additionally, the maximum fragment energies associated with a failure were decreased by an order of magnitude.

Nickel hydrogen bipolar battery electrode design

NASA Technical Reports Server (NTRS)

Puglisi, V. J.; Russell, P.; Verrier, D.; Hall, A.

1985-01-01

The preferred approach of the NASA development effort in nickel hydrogen battery design utilizes a bipolar plate stacking arrangement to obtain the required voltage-capacity configuration. In a bipolar stack, component designs must take into account not only the typical design considerations such as voltage, capacity and gas management, but also conductivity to the bipolar (i.e., intercell) plate. The nickel and hydrogen electrode development specifically relevant to bipolar cell operation is discussed. Nickel oxide electrodes, having variable type grids and in thicknesses up to .085 inch are being fabricated and characterized to provide a data base. A selection will be made based upon a system level tradeoff. Negative (hydrpogen) electrodes are being screened to select a high performance electrode which can function as a bipolar electrode. Present nickel hydrogen negative electrodes are not capable of conducting current through their cross-section. An electrode was tested which exhibits low charge and discharge polarization voltages and at the same time is conductive. Test data is presented.

Molecular Gas in Young Debris Disks

NASA Technical Reports Server (NTRS)

Moor, A.; Abraham, P.; Juhasz, A.; Kiss, Cs.; Pascucci, I.; Kospal, A.; Apai, D.; Henning, T.; Csengeri, T.; Grady, C.

2011-01-01

Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old > or approx.8 Myr), gaseous dust disks. From our results, neither primordia1 origin nor steady secondary production from icy planetesima1s can unequivocally explain the presence of CO gas in the disk ofHD21997.

Nickel on the Swedish market. Follow-up after implementation of the Nickel Directive.

PubMed

Lidén, Carola; Norberg, Kristina

2005-01-01

The Nickel Directive aims at the prevention of sensitization and elicitation of nickel dermatitis. It limits nickel release from, and nickel content in, certain items. The Directive came into full force by July 2001. The aim of this study was to investigate the frequency on the market of items that release nickel and of nickel content in piercing posts, 2 years after coming into force of the Directive. Of special interest was to study changes compared to the situation in 1999, when a baseline study had been carried out. Nickel release from 786 items covered by the Nickel Directive was tested with the dimethylglyoxime (DMG) test, and nickel content in 18 piercing posts was analysed. Nickel release was shown from 8% of items intended for direct and prolonged contact with the skin, and 17% of the piercing posts contained too much nickel, a decrease compared to 1999. There has been significant adaptation to the requirements of the Nickel Directive. The DMG test is useful for screening for nickel release and for monitoring the market. Provided there is further adaptation to the requirements, the risk of sensitization and elicitation of nickel dermatitis will be significantly reduced.

Simulations of polarization from accretion disks

NASA Astrophysics Data System (ADS)

Schultz, J.

2000-12-01

The Monte Carlo Method was used to estimate the level of polarization from axisymmetric accretion disks similar to those in low-mass X-ray binaries and some classes of cataclysmic variables. In low-mass X-ray binaries electron scattering is supposed to be the dominant opacity source in the inner disk, and most of the optical light is produced in the disk. Thompson scattering occuring in the disk corona produces linear polarization. Detailed theoretical models of accretion disks are numerous, but simple mathematical disk models were used, as the accuracy of polarization measurements does not allow distinction of the fine details of disk models. Stokes parameters were used for the radiative transfer. The simulations indicate that the vertical distribution of emissivity has the greatest effect on polarization, and variations of radial emissivity distribution have no detectable effect on polarization. Irregularities in the disk may reduce the degree of polarization. The polarization levels produced by simulations are detectable with modern instruments. Polarization measurements could be used to get rough constraints on the vertical emissivity distribution of an accretion disk, provided that a reasonably accurate disk model can be constructed from photometric or spectrosopic observations in optical and/or X-ray wavelengths. Mainly based on observations taken at the Observatoire de Haute-Provence, France, and on some observations obtained at the European Southern Observatory, Chile (ESO Prog. IDs: 57.C-0492, 59.C-0293, 61.C-0512).

Effect of key parameters on the selective acid leach of nickel from mixed nickel-cobalt hydroxide

NASA Astrophysics Data System (ADS)

Byrne, Kelly; Hawker, William; Vaughan, James

2017-01-01

Mixed nickel-cobalt hydroxide precipitate (MHP) is a relatively recent intermediate product in primary nickel production. The material is now being produced on a large scale (approximately 60,000 t/y Ni as MHP) at facilities in Australia (Ravensthorpe, First Quantum Minerals) and Papua New Guinea (Ramu, MCC/Highlands Pacific). The University of Queensland Hydrometallurgy research group developed a new processing technology to refine MHP based on a selective acid leach. This process provides a streamlined route to obtaining a high purity nickel product compared with conventional leaching / solvent extraction processes. The selective leaching of nickel from MHP involves stabilising manganese and cobalt into the solid phase using an oxidant. This paper describes a batch reactor study investigating the timing of acid and oxidant addition on the rate and extent of nickel, cobalt, manganese leached from industrial MHP. For the conditions studied, it is concluded that the simultaneous addition of acid and oxidant provide the best process outcomes.

Genotoxicity and carcinogenicity of cobalt-, nickel- and copper-based nanoparticles

PubMed Central

MAGAYE, RUTH; ZHAO, JINSHUN; BOWMAN, LINDA; DING, MIN

2012-01-01

The nanotechnology industry has matured and expanded at a rapid pace in the last decade, leading to the research and development of nanomaterials with enormous potential. The largest source of these nanomaterials is the transitional metals. It has been revealed that numerous properties of these nano-sized elements are not present in their bulk states. The nano size of these particles means they are easily transported into biological systems, thus, raising the question of their effects on the susceptible systems. Although advances have been made and insights have been gained on the effect of transitional metals on susceptible biological systems, there still is much ground to be covered, particularly with respect to our knowledge on the genotoxic and carcinogenic effects. Therefore, this review intends to summarize the current knowledge on the genotoxic and carcinogenic potential of cobalt-, nickel- and copper-based nanoparticles indicated in in vitro and in vivo mammalian studies. In the present review, we briefly state the sources, use and exposure routes of these nanoparticles and summarize the current literature findings on their in vivo and in vitro genotoxic and carcinogenic effects. Due to the increasing evidence of their role in carcinogenicity, we have also included studies that have reported epigenetic factors, such as abnormal apoptosis, enhanced oxidative stress and pro-inflammatory effects involving these nanoparticles. PMID:23170105

High strength nickel-base alloy with improved oxidation resistance up to 2200 degrees F

NASA Technical Reports Server (NTRS)

Freche, J. C.; Waters, W. J.

1968-01-01

Modifying the chemistry of the NASA TAZ-8 alloy and utilizing vacuum melting techniques provides a high strength, workable nickel base superalloy with improved oxidation resistance for use up to 2200 degrees F.

Elevated temperature deformation of TD-nickel base alloys

NASA Technical Reports Server (NTRS)

Petrovic, J. J.; Kane, R. D.; Ebert, L. J.

1972-01-01

Sensitivity of the elevated temperature deformation of TD-nickel to grain size and shape was examined in both tension and creep. Elevated temperature strength increased with increasing grain diameter and increasing L/D ratio. Measured activation enthalpies in tension and creep were not the same. In tension, the internal stress was not proportional to the shear modulus. Creep activation enthalpies increased with increasing L/D ratio and increasing grain diameter, to high values compared with that of the self diffusion enthalpy. It has been postulated that two concurrent processes contribute to the elevated temperature deformation of polycrystalline TD-nickel: (1) diffusion controlled grain boundary sliding, and (2) dislocation motion.

Protoplanetary disk observations in the ALMA era

NASA Astrophysics Data System (ADS)

Salyk, Colette

2018-06-01

In this talk, I’ll discuss how ALMA is advancing our understanding of protoplanetary disks with its unprecedented sensitivity and spatial resolution. In particular, I’ll focus on how ALMA is providing our first detailed view of gas-phase chemistry in giant planet forming regions, allowing us to test our ideas about how planets develop their diverse characteristics. Interpretation of these spectroscopic datasets requires sophisticated modeling tools and accurate laboratory data, as protoplanetary disks are ever-evolving environments that span a large range in density, temperature, and radiation field. I’ll discuss some recent results that highlight the important interplay between modeling and data analysis/interpretation, and suggest research directions that ALMA is likely to pursue going forward.

Deformation and Life Analysis of Composite Flywheel Disk and Multi-disk Systems

NASA Technical Reports Server (NTRS)

Arnold, S. M.; Saleeb, A. F.; AlZoubi, N. R.

2001-01-01

In this study an attempt is made to put into perspective the problem of a rotating disk, be it a single disk or a number of concentric disks forming a unit. An analytical model capable of performing an elastic stress analysis for single/multiple, annular/solid, anisotropic/isotropic disk systems, subjected to both pressure surface tractions, body forces (in the form of temperature-changes and rotation fields) and interfacial misfits is derived and discussed. Results of an extensive parametric study are presented to clearly define the key design variables and their associated influence. In general the important parameters were identified as misfit, mean radius, thickness, material property and/or load gradation, and speed; all of which must be simultaneously optimized to achieve the "best" and most reliable design. Also, the important issue of defining proper performance/merit indices (based on the specific stored energy), in the presence of multiaxiality and material anisotropy is addressed. These merit indices are then utilized to discuss the difference between flywheels made from PMC and TMC materials with either an annular or solid geometry. Finally two major aspects of failure analysis, that is the static and cyclic limit (burst) speeds are addressed. In the case of static limit loads, upper, lower, and out-of-plane bounds for disks with constant thickness are presented for both the case of internal pressure loading (as one would see in a hydroburst test) and pure rotation (as in the case of a free spinning disk). The results (interaction diagrams) are displayed graphically in designer friendly format. For the case of fatigue, a representative fatigue/life master curve is illustrated in which the normalized limit speed versus number of applied cycles is given for a cladded TMC disk application.

Isotopic Dichotomy among Meteorites and Its Bearing on the Protoplanetary Disk

NASA Astrophysics Data System (ADS)

Scott, Edward R. D.; Krot, Alexander N.; Sanders, Ian S.

2018-02-01

Whole rock Δ17O and nucleosynthetic isotopic variations for chromium, titanium, nickel, and molybdenum in meteorites define two isotopically distinct populations: carbonaceous chondrites (CCs) and some achondrites, pallasites, and irons in one and all other chondrites and differentiated meteorites in the other. Since differentiated bodies accreted 1–3 Myr before the chondrites, the isotopic dichotomy cannot be attributed to temporal variations in the disk. Instead, the two populations were most likely separated in space, plausibly by proto-Jupiter. Formation of CCs outside Jupiter could account for their characteristic chemical and isotopic composition. The abundance of refractory inclusions in CCs can be explained if they were ejected by disk winds from near the Sun to the disk periphery where they spiraled inward due to gas drag. Once proto-Jupiter reached 10–20 M ⊕, its external pressure bump could have prevented millimeter- and centimeter-sized particles from reaching the inner disk. This scenario would account for the enrichment in CCs of refractory inclusions, refractory elements, and water. Chondrules in CCs show wide ranges in Δ17O as they formed in the presence of abundant 16O-rich refractory grains and 16O-poor ice particles. Chondrules in other chondrites (ordinary, E, R, and K groups) show relatively uniform, near-zero Δ17O values as refractory inclusions and ice were much less abundant in the inner solar system. The two populations were plausibly mixed together by the Grand Tack when Jupiter and Saturn migrated inward emptying and then repopulating the asteroid belt with roughly equal masses of planetesimals from inside and outside Jupiter’s orbit (S- and C-type asteroids).

Upgrading nickel content of limonite nickel ore through pelletization, selective reduction and magnetic separation

NASA Astrophysics Data System (ADS)

Mayangsari, W.; Prasetyo, A. B.; Prasetiyo, Puguh

2018-04-01

Limonite nickel ore has potency to utilize as raw material for ferronickel or nickel matte, since it has low grade nickel content, thus process development is needed to find the acceptable process for upgrading nickel. The aim of this research is to determine upgrading of Ni content as result of selective reduction of limonite nickel pellet continued by magnetic separation as effect of temperature and time reduction as well as coal and CaSO4 addition. There are four steps to perform this research, such as preparation including characterization of raw ore and pelletization, selective reduction, magnetic separation and characterization of products by using AAS, XRD and SEM. Based on the result study, pellet form can upgrade 77.78% higher than powder form. Upgrading of Ni and Fe content was up to 3fold and 1.5fold respectively from raw ore used when reduced at 1100°C for 60 minutes with composition of coal and CaSO4, both 10%. The excess of CaSO4 addition caused fayalite formation. Moreover, S2 from CaSO4 also support to reach low melting point and enlardge particle size of metal formed.

Magnetically Induced Disk Winds and Transport in the HL Tau Disk

NASA Astrophysics Data System (ADS)

Hasegawa, Yasuhiro; Okuzumi, Satoshi; Flock, Mario; Turner, Neal J.

2017-08-01

The mechanism of angular momentum transport in protoplanetary disks is fundamental to understanding the distributions of gas and dust in the disks. The unprecedented ALMA observations taken toward HL Tau at high spatial resolution and subsequent radiative transfer modeling reveal that a high degree of dust settling is currently achieved in the outer part of the HL Tau disk. Previous observations, however, suggest a high disk accretion rate onto the central star. This configuration is not necessarily intuitive in the framework of the conventional viscous disk model, since efficient accretion generally requires a high level of turbulence, which can suppress dust settling considerably. We develop a simplified, semi-analytical disk model to examine under what condition these two properties can be realized in a single model. Recent, non-ideal MHD simulations are utilized to realistically model the angular momentum transport both radially via MHD turbulence and vertically via magnetically induced disk winds. We find that the HL Tau disk configuration can be reproduced well when disk winds are properly taken into account. While the resulting disk properties are likely consistent with other observational results, such an ideal situation can be established only if the plasma β at the disk midplane is β 0 ≃ 2 × 104 under the assumption of steady accretion. Equivalently, the vertical magnetic flux at 100 au is about 0.2 mG. More detailed modeling is needed to fully identify the origin of the disk accretion and quantitatively examine plausible mechanisms behind the observed gap structures in the HL Tau disk.

Factors Affecting Nickel-oxide Electrode Capacity in Nickel-hydrogen Cells

NASA Technical Reports Server (NTRS)

Ritterman, P. F.

1984-01-01

The nickel-oxide electrode common to the nickel hydrogen and nickel cadmium cell is by design the limiting or capacity determining electrode on both charge and discharge. The useable discharge capacity from this electrode, and since it is the limiting electrode, the useable discharge capacity of the cell as well, can and is optimized by rate of charge, charge temperature and additives to electrode and electrolyte. Recent tests with nickel hydrogen cells and tests performed almost 25 years ago with nickel cadmium cells indicate an improvement of capacity as a result of using increased electrolyte concentration.

Multilayer Disk Reduced Interlayer Crosstalk with Wide Disk-Fabrication Margin

NASA Astrophysics Data System (ADS)

Hirotsune, Akemi; Miyauchi, Yasushi; Endo, Nobumasa; Onuma, Tsuyoshi; Anzai, Yumiko; Kurokawa, Takahiro; Ushiyama, Junko; Shintani, Toshimichi; Sugiyama, Toshinori; Miyamoto, Harukazu

2008-07-01

To reduce interlayer crosstalk caused by the ghost spot which appears in a multilayer optical disk with more than three information layers, a multilayer disk structure which reduces interlayer crosstalk with a wide disk-fabrication margin was proposed in which the backward reflectivity of the information layers is sufficiently low. It was confirmed that the interlayer crosstalk caused by the ghost spot was reduced to less than the crosstalk from the adjacent layer by controlling backward reflectivity. The wide disk-fabrication margin of the proposed disk structure was indicated by experimentally confirming that the tolerance of the maximum deviation of the spacer-layer thickness is four times larger than that in the previous multilayer disk.

Encapsulation of sulfur with thin-layered nickel-based hydroxides for long-cyclic lithium–sulfur cells

PubMed Central

Jiang, Jian; Zhu, Jianhui; Ai, Wei; Wang, Xiuli; Wang, Yanlong; Zou, Chenji; Huang, Wei; Yu, Ting

2015-01-01

Elemental sulfur cathodes for lithium/sulfur cells are still in the stage of intensive research due to their unsatisfactory capacity retention and cyclability. The undesired capacity degradation upon cycling originates from gradual diffusion of lithium polysulfides out of the cathode region. To prevent losses of certain intermediate soluble species and extend lifespan of cells, the effective encapsulation of sulfur plays a critical role. Here we report an applicable way, by using thin-layered nickel-based hydroxide as a feasible and effective encapsulation material. In addition to being a durable physical barrier, such hydroxide thin films can irreversibly react with lithium to generate protective layers that combine good ionic permeability and abundant functional polar/hydrophilic groups, leading to drastic improvements in cell behaviours (almost 100% coulombic efficiency and negligible capacity decay within total 500 cycles). Our present encapsulation strategy and understanding of hydroxide working mechanisms may advance progress on the development of lithium/sulfur cells for practical use. PMID:26470847

Connecting the shadows: probing inner disk geometries using shadows in transitional disks

NASA Astrophysics Data System (ADS)

Min, M.; Stolker, T.; Dominik, C.; Benisty, M.

2017-08-01

Aims: Shadows in transitional disks are generally interpreted as signs of a misaligned inner disk. This disk is usually beyond the reach of current day high contrast imaging facilities. However, the location and morphology of the shadow features allow us to reconstruct the inner disk geometry. Methods: We derive analytic equations of the locations of the shadow features as a function of the orientation of the inner and outer disk and the height of the outer disk wall. In contrast to previous claims in the literature, we show that the position angle of the line connecting the shadows cannot be directly related to the position angle of the inner disk. Results: We show how the analytic framework derived here can be applied to transitional disks with shadow features. We use estimates of the outer disk height to put constraints on the inner disk orientation. In contrast with the results from Long et al. (2017, ApJ, 838, 62), we derive that for the disk surrounding HD 100453 the analytic estimates and interferometric observations result in a consistent picture of the orientation of the inner disk. Conclusions: The elegant consistency in our analytic framework between observation and theory strongly support both the interpretation of the shadow features as coming from a misaligned inner disk as well as the diagnostic value of near infrared interferometry for inner disk geometry.

Advanced characterization techniques in understanding the roles of nickel in enhancing strength and toughness of submerged arc welding high strength low alloy steel multiple pass welds in the as-welded condition

NASA Astrophysics Data System (ADS)

Sham, Kin-Ling

Striving for higher strength along with higher toughness is a constant goal in material properties. Even though nickel is known as an effective alloying element in improving the resistance of a steel to impact fracture, it is not fully understood how nickel enhances toughness. It was the goal of this work to assist and further the understanding of how nickel enhanced toughness and maintained strength in particular for high strength low alloy (HSLA) steel submerged arc welding multiple pass welds in the as-welded condition. Using advanced analytical techniques such as electron backscatter diffraction, x-ray diffraction, electron microprobe, differential scanning calorimetry, and thermodynamic modeling software, the effect of nickel was studied with nickel varying from one to five wt. pct. in increments of one wt. pct. in a specific HSLA steel submerged arc welding multiple pass weldment. The test matrix of five different nickel compositions in the as-welded and stress-relieved condition was to meet the targeted mechanical properties with a yield strength greater than or equal to 85 ksi, a ultimate tensile strength greater than or equal to 105 ksi, and a nil ductility temperature less than or equal to -140 degrees F. Mechanical testing demonstrated that nickel content of three wt. pct and greater in the as-welded condition fulfilled the targeted mechanical properties. Therefore, one, three, and five wt. pct. nickel in the as-welded condition was further studied to determine the effect of nickel on primary solidification mode, nickel solute segregation, dendrite thickness, phase transformation temperatures, effective ferrite grain size, dislocation density and strain, grain misorientation distribution, and precipitates. From one to five wt. pct nickel content in the as-welded condition, the primary solidification was shown to change from primary delta-ferrite to primary austenite. The nickel partitioning coefficient increased and dendrite/cellular thickness was

Advanced Models of Accretion Disk Atmospheres and Spectra for Close Binary Stars

NASA Technical Reports Server (NTRS)

Wade, Richard A.

1997-01-01

This work led to the development of code for fitting models to data, and to an understanding of the nature of the models which enabled a more rapid search of 'parameter space' for optimal fits to spectral data sets. The code was used to find optimal fits to IUE spectra of quiescent dwarf novae that have been reported to show evidence for the white dwarf. The models consisted of a white dwarf component and an accretion disk with boundary conditions appropriate for the choice of the white dwarf. The preliminary work has strengthened the initial impression that accretion disk spectra can mimic the appearance of white dwarf spectra in the short-wavelength ultraviolet, so that additional constraints (such as distance) are needed to distinguish to two cases.

An electrochemical acetylcholine sensor based on lichen-like nickel oxide nanostructure.

PubMed

Sattarahmady, N; Heli, H; Vais, R Dehdari

2013-10-15

Lichen-like nickel oxide nanostructure was synthesized by a simple method and characterized. The nanostructure was then applied to modify a carbon paste electrode and for the fabrication of a sensor, and the electrocatalytic oxidation of acetylcholine (ACh) on the modified electrode was investigated. The electrocatalytic efficiency of the nickel oxide nanostructure was compared with nickel micro- and nanoparticles, and the lichen-like nickel oxide nanostructure showed the highest efficiency. The mechanism and kinetics of the electrooxidation process were investigated by cyclic voltammetry, steady-state polarization curve and chronoamperometry. The catalytic rate constant and the charge transfer coefficient of ACh electrooxidation by the active nickel species, and the diffusion coefficient of ACh were reported. A sensitive and time-saving hydrodynamic amperometry method was developed for the determination of ACh. ACh was determined with a sensitivity of 392.4 mA M⁻¹ cm⁻² and a limit of detection of 26.7 μM. The sensor had the advantages of simple fabrication method without using any enzyme or reagent and immobilization step, high electrocatalytic activity, very high sensitivity, long-term stability, and antifouling surface property toward ACh and its oxidation product. Copyright © 2013 Elsevier B.V. All rights reserved.

Piercing mandrel strengthening by surfacing with nickel aluminide-based alloy

NASA Astrophysics Data System (ADS)

Zorin, I. V.; Dubtsov, Yu N.; Sokolov, G. N.; Artem'ev, A. A.; Lysak, V. I.; Elsukov, S. N.

2017-02-01

Electrode composite wire (CW) was used for argon-arc surfacing of a thermal-resisting nickel aluminide-based alloy (Ni-Al-Cr-W-Mo-Ta system) on the butt-end surface of the non-water-cooled piercing mandrel. It was shown that multipassing surfacing forms a defect-free deposited metal based on the γ’-Ni3Al phase of various structural origins. Using high-temperature sclerometry and thermal fatigue testing methods, the metal deposited with CW containing ultrafine particle of 0.3-0.4 % wt. WC carbide features increased resistance to thermal and force effects at temperatures up to 1200 °C.

Predicting the flow & noise of a rotor in a turbulent boundary layer using an actuator disk -- RANS approach

NASA Astrophysics Data System (ADS)

Buono, Armand C.

The numerical method presented in this study attempts to predict the mean, non-uniform flow field upstream of a propeller partially immersed in a thick turbulent boundary layer with an actuator disk using CFD based on RANS in ANSYS FLUENT. Three different configurations, involving an infinitely thin actuator disk in the freestream (Configuration 1), an actuator disk near a wall with a turbulent boundary layer (Configuration 2), and an actuator disk with a hub near a wall with a turbulent boundary layer (Configuration 3), were analyzed for a variety of advance ratios ranging from J = 0.48 to J =1.44. CFD results are shown to be in agreement with previous works and validated with experimental data of reverse flow occurring within the boundary layer above the flat plate upstream of a rotor in the Virginia Tech's Stability Wind Tunnel facility. Results from Configuration 3 will be used in future aero-acoustic computations.

Magnetically Induced Disk Winds and Transport in the HL Tau Disk

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasegawa, Yasuhiro; Flock, Mario; Turner, Neal J.

2017-08-10

The mechanism of angular momentum transport in protoplanetary disks is fundamental to understanding the distributions of gas and dust in the disks. The unprecedented ALMA observations taken toward HL Tau at high spatial resolution and subsequent radiative transfer modeling reveal that a high degree of dust settling is currently achieved in the outer part of the HL Tau disk. Previous observations, however, suggest a high disk accretion rate onto the central star. This configuration is not necessarily intuitive in the framework of the conventional viscous disk model, since efficient accretion generally requires a high level of turbulence, which can suppressmore » dust settling considerably. We develop a simplified, semi-analytical disk model to examine under what condition these two properties can be realized in a single model. Recent, non-ideal MHD simulations are utilized to realistically model the angular momentum transport both radially via MHD turbulence and vertically via magnetically induced disk winds. We find that the HL Tau disk configuration can be reproduced well when disk winds are properly taken into account. While the resulting disk properties are likely consistent with other observational results, such an ideal situation can be established only if the plasma β at the disk midplane is β {sub 0} ≃ 2 × 10{sup 4} under the assumption of steady accretion. Equivalently, the vertical magnetic flux at 100 au is about 0.2 mG. More detailed modeling is needed to fully identify the origin of the disk accretion and quantitatively examine plausible mechanisms behind the observed gap structures in the HL Tau disk.« less

Modeling of Residual Stress and Machining Distortion in Aerospace Components (PREPRINT)

DTIC Science & Technology

2010-03-01

John Gayda, “The Effect of Heat Treatment on Residual Stress and Machining Distortions in Advanced Nickel Base Disk Alloys,” NASA/TM-2001-210717. 2...Wei-Tsu Wu, Guoji Li, Juipeng Tang, Shesh Srivatsa, Ravi Shankar, Ron Wallis, Padu Ramasundaram and John Gayda, “A process modeling system for heat...Materials Processing Technology 98 (2000) 189-195. 6. M.A. Rist, S. Tin, B.A. Roder, J.A. James, and M.R. Daymond , “Residual Stresses in a

Quantification of the association between intervertebral disk calcification and disk herniation in Dachshunds.

PubMed

Jensen, Vibeke F; Beck, Sarah; Christensen, Knud A; Arnbjerg, Jens

2008-10-01

To quantify the association between intervertebral disk calcification and disk herniation in Dachshunds. Longitudinal study. 61 Dachshunds that had been radiographically screened for calcification of intervertebral disks at 2 years of age in other studies. Thirty-seven of the dogs had survived to the time of the present study and were > or = 8 years of age; 24 others had not survived. Radiographic examination of 36 surviving dogs was performed, and information on occurrence of disk calcification at 2 years of age were obtained from records of all 61 Dachshunds. Information on occurrence of disk herniation between 2 and 8 years of age was obtained from owners via questionnaire. Associations between numbers of calcified disks and disk herniation were analyzed via maximum likelihood logistic regression. Disk calcification at 2 years of age was a significant predictor of clinical disk herniation (odds ratio per calcified disk, 1.42; 95% confidence interval, 1.19 to 1.81). Number of calcified disks in the full vertebral column was a better predictor than number of calcified disks between vertebrae T10 and L3. Numbers of calcified disks at > or = 8 years of age and at 2 years of age were significantly correlated. Number of calcified disks at 2 years of age was a good predictor of clinical disk herniation in Dachshunds. Because of the high heritability of disk calcification, it is possible that an effective reduction in occurrence of severe disk herniation in Dachshunds could be obtained by selective breeding against high numbers of calcified disks at 2 years of age.

The Evolution of Spiral Disks

NASA Astrophysics Data System (ADS)

Bershady, Matthew A.; Andersen, David R.

We report on aspects of an observational study to probe the mass assembly of large galaxy disks. In this contribution we focus on a new survey of integral-field Hα velocity-maps of nearby, face on disks. Preliminary results yield disk asymmetry amplitudes consistent with estimates based on the scatter in the local Tully-Fisher relation. We also show how the high quality of integral-field echelle spectroscopy enables determinations of kinematic inclinations to i ~20 °. This holds the promise that nearly-face-on galaxies can be included in the Tully-Fisher relation. Finally, we discuss the prospects for measuring dynamical asymmetries of distant galaxies.

Hydrogen Cyanide In Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Walker, Ashley L.; Oberg, Karin; Cleeves, L. Ilsedore

2018-01-01

The chemistry behind star and planet formation is extremely complex and important in the formation of habitable planets. Life requires molecules containing carbon, oxygen, and importantly, nitrogen. Hydrogen cyanide, or HCN, one of the main interstellar nitrogen carriers, is extremely dangerous here on Earth. However, it could be used as a vital tool for tracking the chemistry of potentially habitable planets. As we get closer to identifying other habitable planets, we must understand the beginnings of how those planets are formed in the early protoplanetary disk. This project investigates HCN chemistry in different locations in the disk, and what this might mean for forming planets at different distances from the star. HCN is a chemically diverse molecule. It is connected to the formation for other more complex molecules and is commonly used as a nitrogen tracer. Using computational chemical models we look at how the HCN abundance changes at different locations. We use realistic and physically motivated conditions for the gas in the protoplanetary disk: temperature, density, and radiation (UV flux). We analyze the reaction network, formation, and destruction of HCN molecules in the disk environment. The disk environment informs us about stability of habitable planets that are created based on HCN molecules. We reviewed and compared the difference in the molecules with a variety of locations in the disk and ultimately giving us a better understanding on how we view protoplanetary disks.

Excessive nickel release from mobile phones--a persistent cause of nickel allergy and dermatitis.

PubMed

Jensen, Peter; Johansen, Jeanne D; Zachariae, Claus; Menné, Torkil; Thyssen, Jacob P

2011-12-01

Despite the political intention to limit nickel allergy and dermatitis in Europeans, nickel allergy remains frequent. There are several explanations for the persistence of nickel allergy and dermatitis, including the increasing use of mobile phones. Before regulation of nickel release from mobile phones, we showed that eight (19.5%) of 41 mobile phones marketed in Denmark between 2003 and 2007 released nickel in concentrations that may result in nickel allergy and dermatitis. In 2009, the EU Nickel Directive was revised to include nickel-releasing mobile phones. To investigate the proportion of mobile phones sold in Denmark that release nickel after regulation. Metallic parts from 50 randomly selected mobile phones currently for sale in Denmark were tested for nickel release by use of the dimethylglyoxime (DMG)-nickel spot test. Nine (18%) phones showed at least one positive DMG test reaction and two phones had more than one DMG test-positive spot. Apparently, the proportion of mobile phones with significant nickel release remains unchanged, despite the 2009 revision of the EU Nickel Directive. We encourage manufacturers to measure nickel release from metallic components used in the assembly of mobile phones to ensure safe products. © 2011 John Wiley & Sons A/S.

Temperature effect on nickel release in ammonium citrate.

PubMed

Oller, Adriana R; Cappellini, Danielle; Henderson, Rayetta G; Bates, Hudson K

2009-09-01

Leaching in ammonium citrate has been extensively used to assess the fraction of water-soluble nickel compounds present in nickel producing and using workplace aerosols. Leaching in ammonium citrate according to the first step of the Zatka protocol was found to overestimate the water-soluble nickel fraction by more than ten-fold compared to synthetic lung fluid (37 degrees C), when nickel carbonate and subsulfide were present. These results suggest that exposure matrices based on this method should be reexamined. Leaching studies of refinery particles are needed to further clarify this important issue.

Development of a micro-fiber nickel electrode for nickel-hydrogen cell

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1995-01-01

Development of a high specific energy nickel electrode is the main goal of the lightweight nickel electrode program at the NASA Lewis Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active material. Initial tests include activation and capacity measurements at different discharge levels followed by half-cell cycle testing at 80 percent depth-of-discharge in a low-Earth-orbit regime. The electrodes that pass the initial tests are life cycle-tested in a boiler plate nickel-hydrogen cell before flightweight designs are built and tested.

Formation of Warped Disks by Galactic Flyby Encounters. I. Stellar Disks

NASA Astrophysics Data System (ADS)

Kim, Jeonghwan H.; Peirani, Sebastien; Kim, Sungsoo; Ann, Hong Bae; An, Sung-Ho; Yoon, Suk-Jin

2014-07-01

Warped disks are almost ubiquitous among spiral galaxies. Here we revisit and test the "flyby scenario" of warp formation, in which impulsive encounters between galaxies are responsible for warped disks. Based on N-body simulations, we investigate the morphological and kinematical evolution of the stellar component of disks when galaxies undergo flyby interactions with adjacent dark matter halos. We find that the so-called "S"-shaped warps can be excited by flybys and sustained for even up to a few billion years, and that this scenario provides a cohesive explanation for several key observations. We show that disk warp properties are governed primarily by the following three parameters: (1) the impact parameter, i.e., the minimum distance between two halos; (2) the mass ratio between two halos; and (3) the incident angle of the flyby perturber. The warp angle is tied up with all three parameters, yet the warp lifetime is particularly sensitive to the incident angle of the perturber. Interestingly, the modeled S-shaped warps are often non-symmetric depending on the incident angle. We speculate that the puzzling U- and L-shaped warps are geometrically superimposed S-types produced by successive flybys with different incident angles, including multiple interactions with a satellite on a highly elongated orbit.

Dynamics of binary-disk interaction. 1: Resonances and disk gap sizes

NASA Technical Reports Server (NTRS)

Artymowicz, Pawel; Lubow, Stephen H.

1994-01-01

We investigate the gravitational interaction of a generally eccentric binary star system with circumbinary and circumstellar gaseous disks. The disks are assumed to be coplanar with the binary, geometrically thin, and primarily governed by gas pressure and (turbulent) viscosity but not self-gravity. Both ordinary and eccentric Lindblad resonances are primarily responsible for truncating the disks in binaries with arbitrary eccentricity and nonextreme mass ratio. Starting from a smooth disk configuration, after the gravitational field of the binary truncates the disk on the dynamical timescale, a quasi-equilibrium is achieved, in which the resonant and viscous torques balance each other and any changes in the structure of the disk (e.g., due to global viscous evolution) occur slowly, preserving the average size of the gap. We analytically compute the approximate sizes of disks (or disk gaps) as a function of binary mass ratio and eccentricity in this quasi-equilibrium. Comparing the gap sizes with results of direct simulations using the smoothed particle hydrodynamics (SPH), we obtain a good agreement. As a by-product of the computations, we verify that standard SPH codes can adequately represent the dynamics of disks with moderate viscosity, Reynolds number R approximately 10(exp 3). For typical viscous disk parameters, and with a denoting the binary semimajor axis, the inner edge location of a circumbinary disk varies from 1.8a to 2.6a with binary eccentricity increasing from 0 to 0.25. For eccentricities 0 less than e less than 0.75, the minimum separation between a component star and the circumbinary disk inner edge is greater than a. Our calculations are relevant, among others, to protobinary stars and the recently discovered T Tau pre-main-sequence binaries. We briefly examine the case of a pre-main-sequence spectroscopic binary GW Ori and conclude that circumbinary disk truncation to the size required by one proposed spectroscopic model cannot be due to

Photoevaporating Disks around Young Stars: Ultracompact HII Regions and Protoplanetary Disks.

NASA Astrophysics Data System (ADS)

Johnstone, Douglas Ian

1995-01-01

Newly formed stars produce sufficient Lyman continuum luminosity phi to significantly alter the structure and evolution of the accretion disk surrounding them. In the absence of a stellar wind, a nearly static, photoionized, 10^4 K, disk atmosphere, with a scale height that increases with disk radius varpi as varpi^{3/2 }, forms inside the gravitational radius varpig ~ 1014(M_*/ M_odot) cm where M _* is the mass of the central star. This ionized atmosphere is maintained by both the direct radiation from the central star and the diffuse field produced in the disk atmosphere by the significant fraction of hydrogen recombinations directly to the ground state. Beyond varpig the material evaporated from the disk is capable of escaping from the system and produces an ionized disk wind. The mass-loss due to this disk wind peaks at varpig . The inclusion of a stellar wind into the basic picture reduces the height of the inner disk atmosphere and introduces a new scale radius varpi_ {w} where the thermal pressure of the material evaporated from the disk balances the ram pressure in the wind. In this case the mass-loss due to the disk wind peaks at varpiw and is enhanced over the no-wind case. The photoevaporation of disks around newly formed stars has significance to both ultracompact HII regions and the dispersal of solar-type nebulae. High mass stars are intrinsically hot and thus yield sufficient Lyman luminosity to create, even without a stellar wind, disk mass-loss rates of order 2 times 10 ^{-5}phi_sp{49} {1/2} M_odotyr ^{-1}, where phi 49 = phi/(10 49 Lyman continuum photons s^{-1}). This wind, which will last until the disk is dispersed, ~ 10^5 yrs if the disk mass is M_ {d}~0.3M_*, yields sizes, emission measures and ages consistent with observations of ultracompact HII regions. The well-observed high mass star MWC 349 may be the best example to date of an evaporating disk around a high mass star. On the other end of the stellar scale, many newly formed low

Inner Structure in the TW Hya Circumstellar Disk

NASA Astrophysics Data System (ADS)

Akeson, Rachel L.; Millan-Gabet, R.; Ciardi, D.; Boden, A.; Sargent, A.; Monnier, J.; McAlister, H.; ten Brummelaar, T.; Sturmann, J.; Sturmann, L.; Turner, N.

2011-05-01

TW Hya is a nearby (50 pc) young stellar object with an estimated age of 10 Myr and signs of active accretion. Previous modeling of the circumstellar disk has shown that the inner disk contains optically thin material, placing this object in the class of "transition disks". We present new near-infrared interferometric observations of the disk material and use these data, as well as previously published, spatially resolved data at 10 microns and 7 mm, to constrain disk models based on a standard flared disk structure. Our model demonstrates that the constraints imposed by the spatially resolved data can be met with a physically plausible disk but this requires a disk containing not only an inner gap in the optically thick disk as previously suggested, but also some optically thick material within this gap. Our model is consistent with the suggestion by previous authors of a planet with an orbital radius of a few AU. This work was conducted at the NASA Exoplanet Science Institute, California Institute of Technology.

Disk mass determination through CO isotopologues

NASA Astrophysics Data System (ADS)

Miotello, Anna; Kama, Mihkel; van Dishoeck, Ewine

2015-08-01

One of the key properties for understanding how disks evolve to planetary systems is their overall mass, combined with their surface density distribution. So far, virtually all disk mass determinations are based on observations of the millimeter continuum dust emission.To derive the total gas + dust disk mass from these data involves however several big assumptions. The alternative method is to directly derive the gas mass through the detection of carbon monoxide (CO) and its less abundant isotopologues. CO chemistry is well studied and easily implemented in chemical models, provided that isotope-selective processes are properly accounted for.CO isotope-selective photodissociation was implemented for the first time in a full physical-chemical code in Miotello et al. (2014). The main result is that if isotope-selective effects are not considered in the data analysis, disk masses can be underestimated by an order of magnitude or more. For example, the mass discrepancy found for the renowned TW Hya disk may be explained or at least mitigated by this implementation. In this poster, we present new results for a large grid of disk models. We derive mass correction factors for different disk, stellar and grain properties in order to account for isotope-selective effects in analyzing ALMA data of CO isotopologues (Miotello et al., in prep.).

Multiple spiral patterns in the transitional disk of HD 100546

NASA Astrophysics Data System (ADS)

Boccaletti, A.; Pantin, E.; Lagrange, A.-M.; Augereau, J.-C.; Meheut, H.; Quanz, S. P.

2013-12-01

Context. Protoplanetary disks around young stars harbor many structures related to planetary formation. Of particular interest, spiral patterns were discovered among several of these disks and are expected to be the sign of gravitational instabilities leading to giant planet formation or gravitational perturbations caused by already existing planets. In this context, the star HD 100546 presents some specific characteristics with a complex gaseous and dusty disk that includes spirals, as well as a possible planet in formation. Aims: The objective of this study is to analyze high-contrast and high angular resolution images of this emblematic system to shed light on critical steps in planet formation. Methods: We retrieved archival images obtained at Gemini in the near IR (Ks band) with the instrument NICI and processed the data using an advanced high contrast imaging technique that takes advantage of the angular differential imaging. Results: These new images reveal the spiral pattern previously identified with Hubble Space Telescope (HST) with an unprecedented resolution, while the large-scale structure of the disk is mostly cancelled by the data processing. The single pattern to the southeast in HST images is now resolved into a multi-armed spiral pattern. Using two models of a gravitational perturber orbiting in a gaseous disk, we attempted to constrain the characteristics of this perturber, assuming that each spiral is independent, and drew qualitative conclusions. The non-detection of the northeast spiral pattern observed in HST allows putting a lower limit on the intensity ratio between the two sides of the disk, which if interpreted as forward scattering, yields a larger anisotropic scattering than is derived in the visible. Also, we find that the spirals are likely to be spatially resolved with a thickness of about 5-10 AU. Finally, we did not detect the candidate planet in formation recently discovered in the Lp band, with a mass upper limit of 16-18 MJ

Sea water Corrosion of Nickel based Plasma Spray Coating

NASA Astrophysics Data System (ADS)

Parida, M.; Nanda, S. P.; Bhuyan, S. K.; Mishra, S. C.

2018-03-01

Different types of erosion resistant coatings are applied/deposited on aero components, depending on the operating/working temperatures. Nickel based coating are applied on the air craft (compressor) components, which can sustain up to working temperature of 650°C. In the present investigation, to improve the compatibility between substrate (i.e. the machine component) and the top coat, application of bond coat is there. The application of Nickel based coating by thermal plasma spray technique has proven to be a satisfactory means of producing acceptable sealing surface with excellent abradability. Before the corrosion study, coated sample is subjected to hardness, thickness and porosity testing. Hence the result is being evaluated. The corrosion behavior of coating was studied by sea water immersion with a time period of 16 weeks. It is observed that, up to 9 weeks increase in weight of coating occurs in a sharp trend and then takes a decreasing trend. The weight gain of the samples has varied from 37.23% (with one week immersion in sea water) to a maximum of about 64.36% for six weeks immersion. Coating morphology and composition analysis of the coatings are studied using SEM and EDS. This behavior shows adsorption/deposition of the foreign particles with polygonal shape on the coating surface by sea water interaction. Foreign particles with polygonal shape deposited on the coating and with increase in immersion/treatment time, washing out of the deposited materials starts, which reflects the decreasing trend of weight gain of the specimen.

Radiative Transfer Modeling in Proto-planetary Disks

NASA Astrophysics Data System (ADS)

Kasper, David; Jang-Condell, Hannah; Kloster, Dylan

2016-01-01

Young Stellar Objects (YSOs) are rich astronomical research environments. Planets form in circumstellar disks of gas and dust around YSOs. With ever increasing capabilities of the observational instruments designed to look at these proto-planetary disks, most notably GPI, SPHERE, and ALMA, more accurate interfaces must be made to connect modeling of the disks with observation. PaRTY (Parallel Radiative Transfer in YSOs) is a code developed previously to model the observable density and temperature structure of such a disk by self-consistently calculating the structure of the disk based on radiative transfer physics. We present upgrades we are implementing to the PaRTY code to improve its accuracy and flexibility. These upgrades include: creating a two-sided disk model, implementing a spherical coordinate system, and implementing wavelength-dependent opacities. These upgrades will address problems in the PaRTY code of infinite optical thickness, calculation under/over-resolution, and wavelength-independent photon penetration depths, respectively. The upgraded code will be used to better model disk perturbations resulting from planet formation.

Nonlinear calculations of the time evolution of black hole accretion disks

NASA Technical Reports Server (NTRS)

Luo, C.

1994-01-01

Based on previous works on black hole accretion disks, I continue to explore the disk dynamics using the finite difference method to solve the highly nonlinear problem of time-dependent alpha disk equations. Here a radially zoned model is used to develop a computational scheme in order to accommodate functional dependence of the viscosity parameter alpha on the disk scale height and/or surface density. This work is based on the author's previous work on the steady disk structure and the linear analysis of disk dynamics to try to apply to x-ray emissions from black candidates (i.e., multiple-state spectra, instabilities, QPO's, etc.).

Coronagraphic Imaging of Debris Disks from a High Altitude Balloon Platform

NASA Technical Reports Server (NTRS)

Unwin, Stephen; Traub, Wesley; Bryden, Geoffrey; Brugarolas, Paul; Chen, Pin; Guyon, Olivier; Hillenbrand, Lynne; Kasdin, Jeremy; Krist, John; Macintosh, Bruce;

Coronagraphic Imaging of Debris Disks from a High Altitude Balloon Platform

NASA Technical Reports Server (NTRS)

Unwin, Stephen; Traub, Wesley; Bryden, Geoffrey; Brugarolas, Paul; Chen, Pin; Guyon, Olivier; Hillenbrand, Lynne; Krist, John; Macintosh, Bruce; Mawet, Dimitri;

The continuing battle against defects in nickel-base superalloys

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.

1986-01-01

In the six decades since the identification of age hardenable nickel-base superalloys their compositions and microstructures have changed markedly. Current alloys are tailored for specific applications. Thus their microstructures are defined for that application. This paper briefly reviews the evolution of superalloy microstructures and comments on the appearance and implications of microstructural defects in high performance superalloys. It is seen that new alloys and proceses have generated new types of defects. Thus as the industry continues to develop new alloys and processes it must remain vigilant toward the identification and control of new types of defects.

Process of welding gamma prime-strengthened nickel-base superalloys

DOEpatents

Speigel, Lyle B.; White, Raymond Alan; Murphy, John Thomas; Nowak, Daniel Anthony

2003-11-25

A process for welding superalloys, and particularly articles formed of gamma prime-strengthened nickel-base superalloys whose chemistries and/or microstructures differ. The process entails forming the faying surface of at least one of the articles to have a cladding layer of a filler material. The filler material may have a composition that is different from both of the articles, or the same as one of the articles. The cladding layer is machined to promote mating of the faying surfaces, after which the faying surfaces are mated and the articles welded together. After cooling, the welded assembly is free of thermally-induced cracks.

The influence of disk's flexibility on coupling vibration of shaft disk blades systems

NASA Astrophysics Data System (ADS)

Yang, Chia-Hao; Huang, Shyh-Chin

2007-03-01

The coupling vibrations among shaft-torsion, disk-transverse and blade-bending in a shaft-disk-blades unit are investigated. The equations of motion for the shaft-disk-blades unit are first derived from the energy approach in conjunction with the assumed modes method. The effects of disk flexibility, blade's stagger angle and rotational speed upon the natural frequencies and mode shapes are particularly studied. Previous studies have shown that there were four types of coupling modes, the shaft-blade (SB), the shaft-disk-blades (SDBs), the disk-blades (DB) and the blade-blade (BB) in such a unit. The present research focuses on the influence of disk flexibility on the coupling behavior and discovers that disk's flexibility strongly affects the modes bifurcation and the transition of modes. At slightly flexible disk, the BB modes bifurcate into BB and DB modes. As disk goes further flexible, SB modes shift into SDB modes. If it goes furthermore, additional disk-predominating modes are generated and DB modes appear before the SDB mode. Examination of stagger angle β proves that at two extreme cases; at β=0° the shaft and blades coupled but not the disk, and at β=90° the disk and blades coupled but not the shaft. In between, coupling exists among three components. Increasing β may increase or decrease SB modes, depending on which, the disk or shaft's first mode, is more rigid. The natural frequencies of DB modes usually decrease with the increase of β. Rotation effects show that bifurcation, veering and merging phenomena occur due to disk flexibility. Disk flexibility is also observed to induce more critical speeds in the SDBs systems.

Effects of Disk Warping on the Inclination Evolution of Star-Disk-Binary Systems

NASA Astrophysics Data System (ADS)

Zanazzi, J. J.; Lai, Dong

2018-04-01

Several recent studies have suggested that circumstellar disks in young stellar binaries may be driven into misalignement with their host stars due to secular gravitational interactions between the star, disk and the binary companion. The disk in such systems is twisted/warped due to the gravitational torques from the oblate central star and the external companion. We calculate the disk warp profile, taking into account of bending wave propagation and viscosity in the disk. We show that for typical protostellar disk parameters, the disk warp is small, thereby justifying the "flat-disk" approximation adopted in previous theoretical studies. However, the viscous dissipation associated with the small disk warp/twist tends to drive the disk toward alignment with the binary or the central star. We calculate the relevant timescales for the alignment. We find the alignment is effective for sufficiently cold disks with strong external torques, especially for systems with rapidly rotating stars, but is ineffective for the majority of star-disk-binary systems. Viscous warp driven alignment may be necessary to account for the observed spin-orbit alignment in multi-planet systems if these systems are accompanied by an inclined binary companion.

Production of High-Purity Anhydrous Nickel(II) Perrhenate for Tungsten-Based Sintered Heavy Alloys

PubMed Central

Leszczyńska-Sejda, Katarzyna; Benke, Grzegorz; Kopyto, Dorota; Majewski, Tomasz; Drzazga, Michał

2017-01-01

This paper presents a method for the production of high-purity anhydrous nickel(II) perrhenate. The method comprises sorption of nickel(II) ions from aqueous nickel(II) nitrate solutions, using strongly acidic C160 cation exchange resin, and subsequent elution of sorbed nickel(II) ions using concentrated perrhenic acid solutions. After the neutralization of the resulting rhenium-nickel solutions, hydrated nickel(II) perrhenate is then separated and then dried at 160 °C to obtain the anhydrous form. The resulting compound is reduced in an atmosphere of dissociated ammonia in order to produce a Re-Ni alloy powder. This study provides information on the selected properties of the resulting Re-Ni powder. This powder was used as a starting material for the production of 77W-20Re-3Ni heavy alloys. Microstructure examination results and selected properties of the produced sintered heavy alloys were compared to sintered alloys produced using elemental W, Re, and Ni powders. This study showed that the application of anhydrous nickel(II) perrhenate in the production of 77W-20Re-3Ni results in better properties of the sintered alloys compared to those made from elemental powders. PMID:28772808

HD 100453: An evolutionary link between protoplanetary disks and debris disks

NASA Astrophysics Data System (ADS)

Collins, Karen

2008-12-01

Herbig Ae stars are young stars usually surrounded by gas and dust in the form of a disk and are thought to evolve into planetary systems similar to our own. We present a multi-wavelength examination of the disk and environment of the Herbig Ae star HD 100453A, focusing on the determination of accretion rate, system age, and disk evolution. We show that the accretion rate is characterized by Chandra X-ray imagery that is inconsistent with strongly accreting early F stars, that the disk lacks the conspicuous Fe II emission and continuum seen in FUV spectra of actively accreting Herbig Ae stars, and that FUSE, HST, and FEROS data suggest an accretion rate below ˜ 2.5×10 -10 [Special characters omitted.] M⊙ yr -1 . We confirm that HD 100453B is a common proper motion companion to HD 100453A, with spectral type M4.0V - M4.5V, and derive an age of 14 ± 4 Myr. We examine the Meeus et al. (2001) hypothesis that Meeus Group I sources, which have a mid-IR bump which can be fitted by a black body component, evolve to Meeus Group II sources, which have no such mid-IR bump. By considering stellar age and accretion rate evidence, we find the hypothesis to be invalid. Furthermore, we find that the disk characteristics of HD 100453A do not fit the traditional definition of a protoplanetary disk, a transitional disk, or a debris disk, and they may suggest a new class of disks linking gas-rich protoplanetary disks and gas-poor debris disks.

Optical disk processing of solar images.

NASA Astrophysics Data System (ADS)

Title, A.; Tarbell, T.

The current generation of space and ground-based experiments in solar physics produces many megabyte-sized image data arrays. Optical disk technology is the leading candidate for convenient analysis, distribution, and archiving of these data. The authors have been developing data analysis procedures which use both analog and digital optical disks for the study of solar phenomena.

The effects of platinum on nickel electrodes in the nickel hydrogen cell

NASA Technical Reports Server (NTRS)

Zimmerman, Albert H.

1991-01-01

Interactions of platinum and platinum compounds with the nickel electrode that are possible in the nickel hydrogen cell, where both the nickel electrode and a platinum catalyst hydrogen electrode are in intimate contact with the alkaline electrolyte, are examined. Additionally, a mechanism of nickel cobalt oxyhydroxide formation in NiH2 cells is presented.

Bending Properties of Nickel Electrodes for Nickel-Hydrogen Batteries

NASA Technical Reports Server (NTRS)

Lerch, Brad A.; Wilson, Richard M.; Keller, Dennis; Corner, Ralph

1995-01-01

Recent changes in manufacturing have resulted in nickel-hydrogen batteries that fail prematurely by electrical shorting, This failure is believed to be a result of a blistering problem in the nickel electrodes. In this study the bending properties of nickel electrodes are investigated in an attempt to correlate the bending properties of the electrode with its propensity to blister. Nickel electrodes from three different batches of material were tested in both the as-received and impregnated forms. The effects of specimen curvature and position within the electrode on the bending strength were studied, and within-electrode and batch-to-batch variations were addressed. Two color-imaging techniques were employed to differentiate between the phases within the electrodes. These techniques aided in distinguishing the relative amounts of nickel hyroxide surface loading on each electrode, thereby relating surface loading to bend strength. Bend strength was found to increase with the amount of surface loading.

Nickel speciation in several serpentine (ultramafic) topsoils via bulk synchrotron-based techniques

USDA-ARS?s Scientific Manuscript database

Serpentine soils are extensively studied because of their unique soil chemical properties and flora. They commonly have high magnesium-to-calcium ratios and elevated concentrations of trace metals including nickel, cobalt, and chromium. Several nickel hyperaccumulator plants are native to serpenti...

Detoxification of rats subjected to nickel chloride by a biomaterial-based carbonated orthophosphate.

PubMed

Boulila, S; El Feki, A; Oudadesse, H; Kallel, C; El Feki, H

2014-09-01

Recently, the therapeutic approaches of the detoxification against the metals (nickel) in the body are the use of biomaterials such as carbonated hydroxyapatite. The aim of this study is therefore to analyze the physiological and physicochemical parameters of strain white rats "Wistar" receiving nickel chloride and to study the protective associative of apatite against adverse effects of this metal, and this in comparison with control rats. Our results showed that the nickel induced in rats an oxidative stress objectified by elevated levels of thiobarbituric acid-reactive substances and conjugated dienes associated with inhibition of the activity of the antioxidant defense system such as glutathione peroxidase, superoxide dismutase and catalase in the liver, kidney, spleen and erythrocyte. Disorders balances of ferric, phosphocalcic, a renal failure and a liver toxicity were observed in rats exposed to nickel. As well as a significant increase in the rate of nickel in the bones and microcytic anemia was revealed. However, the implantation of carbonated hydroxyapatite in capsule form protects rats intoxicated by the nickel against the toxic effects of this metal by lowering the levels of markers of lipid peroxidation and improving the activities of defense enzymes. Our implantation technique is effective to correct ferric balance and phosphocalcic equilibrium, to protect liver and kidney function, to reduce the rate of bone nickel and to correct anemia. They clearly explain the beneficial and protective of our biomaterial which aims the detoxification of rats receiving nickel by substituting cationic (Ca(2+) by Ni(2+)) and anionic (OH(-) by Cl(-)) confirmed by physicochemical characterization like the IR spectroscopy and X-ray diffraction. These techniques have shown on the one hand a duplication of OH(-) bands (IR) and on the other hand the increase of the volume of the apatite cell after these substitutions (X-ray diffraction). Copyright © 2014 Elsevier Masson

Recent development of disk lasers at TRUMPF

NASA Astrophysics Data System (ADS)

Schad, Sven-Silvius; Gottwald, Tina; Kuhn, Vincent; Ackermann, Matthias; Bauer, Dominik; Scharun, Michael; Killi, Alexander

2016-03-01

The disk laser is one of the most important laser concepts for today's industrial laser market. Offering high brilliance at low cost, high optical efficiency and great application flexibility the disk laser paved the way for many industrial laser applications. Over the past years power and brightness increased and the disk laser turned out to be a very versatile laser source, not only for welding but also for cutting. Both, the quality and speed of cutting are superior to CO2-based lasers for a vast majority of metals, and, most important, in a broad thickness range. In addition, due to the insensitivity against back reflections the disk laser is well suited for cutting highly reflective metal such as brass or copper. These advantages facilitate versatile cutting machines and explain the high and growing demand for disk lasers for applications besides welding applications that can be observed today. From a today's perspective the disk principle has not reached any fundamental limits regarding output power per disk or beam quality, and offers numerous advantages over other high power resonator concepts, especially over fiber lasers or direct diode lasers. This paper will give insight in the latest progress in kilowatt class cw disk laser technology at TRUMPF and will discuss recent power scaling results as well.

Modern fiber laser beam welding of the newly-designed precipitation-strengthened nickel-base superalloys

NASA Astrophysics Data System (ADS)

Naffakh Moosavy, Homam; Aboutalebi, Mohammad-Reza; Seyedein, Seyed Hossein; Goodarzi, Massoud; Khodabakhshi, Meisam; Mapelli, Carlo; Barella, Silvia

2014-04-01

In the present research, the modern fiber laser beam welding of newly-designed precipitation-strengthened nickel-base superalloys using various welding parameters in constant heat input has been investigated. Five nickel-base superalloys with various Ti and Nb contents were designed and produced by Vacuum Induction Melting furnace. The fiber laser beam welding operations were performed in constant heat input (100 J mm-2) and different welding powers (400 and 1000 W) and velocities (40 and 100 mm s-1) using 6-axis anthropomorphic robot. The macro- and micro-structural features, weld defects, chemical composition and mechanical property of 3.2 mm weldments were assessed utilizing optical and scanning electron microscopes equipped with EDS analysis and microhardness tester. The results showed that welding with higher powers can create higher penetration-to-width ratios. The porosity formation was increased when the welding powers and velocities were increased. None of the welds displayed hot solidification and liquation cracks in 400 and 1000 W welding powers, but liquation phenomenon was observed in all the heat-affected zones. With increasing the Nb content of the superalloys the liquation length was increased. The changing of the welding power and velocity did not alter the hardness property of the welds. The hardness of welds decreased when the Ti content declined in the composition of superalloys. Finally, the 400 and 1000 W fiber laser powers with velocity of 40 and 100 m ms-1 have been offered for hot crack-free welding of the thin sheet of newly-designed precipitation-strengthened nickel-base superalloys.

Brushing-Induced Surface Roughness of Two Nickel Based Alloys and a Titanium Based Alloy: A Comparative Study - In Vitro Study

PubMed Central

Acharya, B L Guruprasanna; Nadiger, Ramesh; Shetty, Bharathraj; Gururaj, G; Kumar, K Naveen; Darshan, D D

2014-01-01

be given to the selection of the toothbrushes and toothpastes with the medium abrasives in patients with these restorations. How to cite the article: Acharya BL, Nadiger R, Shetty B, Gururaj G, Kumar KN, Darshan DD. Brushing induced surface roughness of two nickel based alloys and a titanium based alloy: A comparative study - In vitro study. J Int Oral Health 2014;6(3):36-49. PMID:25083031

Confined surface plasmon sensors based on strongly coupled disk-in-volcano arrays.

PubMed

Ai, Bin; Wang, Limin; Möhwald, Helmuth; Yu, Ye; Zhang, Gang

2015-02-14

Disk-in-volcano arrays are reported to greatly enhance the sensing performance due to strong coupling in the nanogaps between the nanovolcanos and nanodisks. The designed structure, which is composed of a nanovolcano array film and a disk in each cavity, is fabricated by a simple and efficient colloidal lithography method. By tuning structural parameters, the disk-in-volcano arrays show greatly enhanced resonances in the nanogaps formed by the disks and the inner wall of the volcanos. Therefore they respond to the surrounding environment with a sensitivity as high as 977 nm per RIU and with excellent linear dependence on the refraction index. Moreover, through mastering the fabrication process, biological sensing can be easily confined to the cavities of the nanovolcanos. The local responsivity has the advantages of maximum surface plasmon energy density in the nanogaps, reducing the sensing background and saving expensive reagents. The disk-in-volcano arrays also possess great potential in applications of optical and electrical trapping and single-molecule analysis, because they enable establishment of electric fields across the gaps.

Herniated disk

MedlinePlus

... help support the spine. A brace may prevent injuries in people who lift heavy objects at work. But ... Cervical radiculopathy; Herniated intervertebral disk; Prolapsed intervertebral disk; Slipped ...

Complexation of Nickel Ions by Boric Acid or (Poly)borates.

PubMed

Graff, Anais; Barrez, Etienne; Baranek, Philippe; Bachet, Martin; Bénézeth, Pascale

2017-01-01

An experiment based on electrochemical reactions and pH monitoring was performed in which nickel ions were gradually formed by oxidation of a nickel metal electrode in a solution of boric acid. Based on the experimental results and aqueous speciation modeling, the evolution of pH showed the existence of significant nickel-boron complexation. A triborate nickel complex was postulated at high boric acid concentrations when polyborates are present, and the equilibrium constants were determined at 25, 50 and 70 °C. The calculated enthalpy and entropy at 25 °C for the formation of the complex from boric acid and Ni 2+ ions are respectively equal to (65.6 ± 3.1) kJ·mol -1 and (0.5 ± 11.1) J·K -1 ·mol -1 . The results of this study suggest that complexation of nickel ions by borates can significantly enhance the solubility of nickel metal and nickel oxide depending on the concentration of boric acid and pH. First principles calculations were investigated and tend to show that the complex is thermodynamically stable and the nickel cation in solution should interact more strongly with the [Formula: see text] than with boric acid.

Development of a Micro-Fiber Nickel Electrode for Nickel-Hydrogen Cell

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1996-01-01

The development of a high specific energy battery is one of the objectives of the lightweight nickel-hydrogen (NiH2) program at the NASA Lewis Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen fuel cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active materials. Initial tests include activation and capacity measurements at different discharge levels followed by half-cell cycle testing at 80 percent depth-of-discharge in a low Earth orbit regime. The electrodes that pass the initial tests are life cycle tested in a boiler plate nickel-hydrogen cell before flightweight designs are built and tested.

Gaseous Inner Disks

DTIC Science & Technology

2007-01-01

planetary systems (i.e., planetary masses, orbital radii, and eccentricities). For example, the lifetime of gas in the inner disk (limited by accretion onto...2002). Thus, understanding how inner disks dissipate may impact our understanding of the origin of planetary orbital radii. Similarly, residual gas...which the orbiting giant planet carves out a “ gap ” in the disk . Low column densities would also be characteristic of a dissipating disk . Thus, we should

Electrochemical impregnation and cycle life of lightweight nickel electrodes for nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1990-01-01

Development of a high specific energy nickel electrode is the main goal of the lightweight nickel electrode program at NASA-Lewis. The approach was to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen cell. Lightweight plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. The electrodes are life cycle tested in a low Earth orbit regime at 40 and 80 percent depths-of-discharge.

Electrochemical impregnation and cycle life of lightweight nickel electrodes for nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1990-01-01

Development of a high specific energy nickel electrode is the main goal of the lightweight nickel electrode program at NASA-Lewis. The approach was to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen cell. Lightweight plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. The electrodes are life cycle tested in a low earth orbit regime at 40 and 80 percent depths-of-discharge.

High-temperature, high-frequency fretting fatigue of a single crystal nickel alloy

NASA Astrophysics Data System (ADS)

Matlik, John Frederick

Fretting is a structural damage mechanism arising from a combination of wear, corrosion, and fatigue between two nominally clamped surfaces subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high-temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact that could potentially foster crack growth leading to component failure. These contact stresses drive crack nucleation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). To diagnose the threat that small and relatively undetectable fretting fatigue cracks pose to damage tolerance and the ensuing structural integrity of aerospace components, a strong motivation exists to develop a quantitative mechanics based understanding of fretting crack nucleation in advanced aerospace alloys. In response to this need, the objective of this work is to characterize the fretting behavior exhibited by a polycrystalline/single crystal nickel contact subjected to elevated frequency and temperature. The effort to meet this objective is two fold: (1) to develop a well-characterized experimental fretting rig to investigate fretting behavior of advanced aerospace alloys at high frequency and high temperature, and (2) to develop the associated contact modeling tools for calculating contact stresses given in-situ experimentally measured remote contact loads. By coupling the experimental results and stress analysis, this effort aims to correlate the fretting crack nucleation behavior with the local contact stresses calculated from the devised three dimensional, anisotropic, dissimilar material contact model. The experimental effort is first motivated by a survey of recent fretting issues and

Biotinylated lipid bilayer disks as model membranes for biosensor analyses.

PubMed

Lundquist, Anna; Hansen, Søren B; Nordström, Helena; Danielson, U Helena; Edwards, Katarina

2010-10-15

The aim of this study was to investigate the potential of polyethylene glycol (PEG)-stabilized lipid bilayer disks as model membranes for surface plasmon resonance (SPR)-based biosensor analyses. Nanosized bilayer disks that included 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[biotinyl(polyethylene glycol)(2000)] (DSPE-PEG(2000)-biotin) were prepared and structurally characterized by cryo-transmission electron microscopy (cryo-TEM) imaging. The biotinylated disks were immobilized via streptavidin to three different types of sensor chips (CM3, CM4, and CM5) varying in their degree of carboxymethylation and thickness of the dextran matrix. The bilayer disks were found to interact with and bind stably to the streptavidin-coated sensor surfaces. As a first step toward the use of these bilayer disks as model membranes in SPR-based studies of membrane proteins, initial investigations were carried out with cyclooxygenases 1 and 2 (COX 1 and COX 2). Bilayer disks were preincubated with the respective protein and thereafter allowed to interact with the sensor surface. The signal resulting from the interaction was, in both cases, significantly enhanced as compared with the signal obtained when disks alone were injected over the surface. The results of the study suggest that bilayer disks constitute a new and promising type of model membranes for SPR-based biosensor studies. Copyright 2010 Elsevier Inc. All rights reserved.

Hubble Views the Whirling Disk of NGC 4526

NASA Image and Video Library

2014-10-24

This neat little galaxy is known as NGC 4526. Its dark lanes of dust and bright diffuse glow make the galaxy appear to hang like a halo in the emptiness of space in this image from the NASA/ESA Hubble Space Telescope. Although this image paints a picture of serenity, the galaxy is anything but. It is one of the brightest lenticular galaxies known, a category that lies somewhere between spirals and ellipticals. It has hosted two known supernova explosions, one in 1969 and another in 1994, and is known to have a colossal supermassive black hole at its center that has the mass of 450 million suns. NGC 4526 is part of the Virgo cluster of galaxies. Ground-based observations of galaxies in this cluster have revealed that a quarter of these galaxies seem to have rapidly rotating disks of gas at their centers. The most spectacular of these is this galaxy, NGC 4526, and its spinning disk of gas, dust, and stars reaches out uniquely far from its heart, spanning some seven percent of the galaxy's entire radius. This disk is moving incredibly fast, spinning at more than 250 kilometers per second. The dynamics of this quickly whirling region were actually used to infer the mass of NGC 4526’s central black hole — a technique that had not been used before to constrain a galaxy’s central black hole. This image was taken with Hubble's Wide Field and Planetary Camera 2 and the Advanced Camera for Surveys. Credit: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt

Radiative Transfer in Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Graziani, L.; Aiello, S.; Belleni-Morante, A.; Cecchi-Pestellini, C.

2008-09-01

Abstract Protoplanetary disks are the precursors of planetary systems. All building materials needed to assembly the planetary systems are supplied by these reservoirs, including many organic molecules [1,2]. Thus, the physical and chemical properties in Protoplanetary disks set the boundary conditions for the formation and evolution of planets and other solar system bodies. In standard radiative scenario structure and chemistry of protoplanetary disks depend strongly on the nature of central star around which they formed. The dust temperature is manly set by the stellar luminosity, while the chemistry of the whole disk depends on the UV and X ray fluxes [3,4,6,8]. Therefore, a knowledge as accurate as possible of the radiative transfer (RT) inside disks is a prerequisite for their modelling. Actually, real disks are complex, stratified and inhomogeneous environments requiring a detailed dust mixture modelling and the ability to follow the radiation transfer across radial and vertical gradients. Different energetic processes as the mass accretion processes onto the star surface, the viscous dissipative heating dominating the midplane region, and the flared atmospheres radiation reprocessing, have a significant role in the disk structuring [4,5,8]. During the last 10 years many authors suggested various numerical and analytical techniques to resolve the disk temperature structure providing vertical temperature profiles and disk SED databases [4,6]. In this work we present the results of our semi analytical and numerical model solving the radiative transfer problem in two separate interesting disk regions: 1) Disk atmospheres at large radius, r > 10 AU. 2) Vertical disk structure over 1 < r < 10 AU and 10 < r < 100 AU. A simplified analytical approach based on P-N approximation [7] for a rectified disk surface (suitable for limited range of r) is compared and contrasted with a more accurate Monte Carlo integration [5]. Our code can handle arbitrary dust

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen flight cells - An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

THE KOZAI–LIDOV MECHANISM IN HYDRODYNAMICAL DISKS. II. EFFECTS OF BINARY AND DISK PARAMETERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G., E-mail: wf5@rice.edu

2015-07-01

Martin et al. showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions, binarymore » mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.« less

The Kozai-Lidov mechanism in hydrodynamical disks. II. Effects of binary and disk parameters

DOE PAGES

Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G.

2015-07-01

Martin et al. (2014b) showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions,more » binary mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.« less

Disk-based k-mer counting on a PC

PubMed Central

2013-01-01

Background The k-mer counting problem, which is to build the histogram of occurrences of every k-symbol long substring in a given text, is important for many bioinformatics applications. They include developing de Bruijn graph genome assemblers, fast multiple sequence alignment and repeat detection. Results We propose a simple, yet efficient, parallel disk-based algorithm for counting k-mers. Experiments show that it usually offers the fastest solution to the considered problem, while demanding a relatively small amount of memory. In particular, it is capable of counting the statistics for short-read human genome data, in input gzipped FASTQ file, in less than 40 minutes on a PC with 16 GB of RAM and 6 CPU cores, and for long-read human genome data in less than 70 minutes. On a more powerful machine, using 32 GB of RAM and 32 CPU cores, the tasks are accomplished in less than half the time. No other algorithm for most tested settings of this problem and mammalian-size data can accomplish this task in comparable time. Our solution also belongs to memory-frugal ones; most competitive algorithms cannot efficiently work on a PC with 16 GB of memory for such massive data. Conclusions By making use of cheap disk space and exploiting CPU and I/O parallelism we propose a very competitive k-mer counting procedure, called KMC. Our results suggest that judicious resource management may allow to solve at least some bioinformatics problems with massive data on a commodity personal computer. PMID:23679007

Oral bioaccessibility testing and read-across hazard assessment of nickel compounds.

PubMed

Henderson, Rayetta G; Cappellini, Danielle; Seilkop, Steven K; Bates, Hudson K; Oller, Adriana R

2012-06-01

In vitro metal ion bioaccessibility, as a measure of bioavailability, can be used to read-across toxicity information from data-rich, source substances to data-poor, target substances. To meet the data requirements for oral systemic toxicity endpoints under the REACH Regulation in Europe, 12 nickel substances underwent bioaccessibility testing in stomach and intestinal fluids. A read-across paradigm was developed based on the correlation between gastric bioaccessibility and in vivo acute oral toxicity. The oral LD₅₀ values were well predicted by nickel release (R² = 0.91). Samples releasing <48% available nickel (mgNi released/mg available Ni × 100) are predicted to have an LD₅₀ > 2000 mg/kg; while samples releasing > 76% available nickel are expected to have an LD₅₀ between 300 and 2000 mg/kg. The hazard classifications (European Regulation on Classification, Labelling and Packaging of Chemical Substances and Mixtures) for all oral systemic endpoints were evaluated based on read-across from three source nickel compounds (sulfate, subsulfide, oxide). Samples releasing < 48% available nickel were read-across from nickel oxides and subsulfide. Samples releasing > 76% Ni were read-across from nickel sulfate. This assessment suggests that nickel chloride and dihydroxide should be less stringently classified and nickel sulfamate should receive a more stringent classification for oral systemic endpoints than currently assigned. Copyright © 2012 Elsevier Inc. All rights reserved.

Platinum Nickel Nanowires as Methanol Oxidation Electrocatalysts

DOE PAGES

Alia, Shaun M.; Pylypenko, Svitlana; Neyerlin, Kenneth C.; ...

2015-08-27

We investigated platinum(Pt) nickel (Ni) nanowires (PtNiNWs) as methanol oxidation reaction (MOR) catalysts in rotating disk electrode (RDE) half-cells under acidic conditions. Pt-ruthenium (Ru) nanoparticles have long been the state of the art MOR catalyst for direct methanol fuel cells (DMFCs) where Ru provides oxophilic sites, lowering the potential for carbon monoxide oxidation and the MOR onset. Ru, however, is a precious metal that has long term durability concerns. Ni/Ni oxide species offer a potential to replace Ru in MOR electrocatalysis. PtNiNWs were investigated for MOR and oxygen annealing was investigated as a route to improve catalyst performance (mass activitymore » 65% greater) and stability to potential cycling. Our results presented show that PtNiNWs offer significant promise in the area, but also result in Ni ion leaching that is a concern requiring further evaluation in fuel cells.« less

Possible Rapid Gas Giant Planet Formation in the Solar Nebula and Other Protoplanetary Disks.

PubMed

Boss

2000-06-20

Gas giant planets have been detected in orbit around an increasing number of nearby stars. Two theories have been advanced for the formation of such planets: core accretion and disk instability. Core accretion, the generally accepted mechanism, requires several million years or more to form a gas giant planet in a protoplanetary disk like the solar nebula. Disk instability, on the other hand, can form a gas giant protoplanet in a few hundred years. However, disk instability has previously been thought to be important only in relatively massive disks. New three-dimensional, "locally isothermal," hydrodynamical models without velocity damping show that a disk instability can form Jupiter-mass clumps, even in a disk with a mass (0.091 M middle dot in circle within 20 AU) low enough to be in the range inferred for the solar nebula. The clumps form with initially eccentric orbits, and their survival will depend on their ability to contract to higher densities before they can be tidally disrupted at successive periastrons. Because the disk mass in these models is comparable to that apparently required for the core accretion mechanism to operate, the models imply that disk instability could obviate the core accretion mechanism in the solar nebula and elsewhere.

The strengthening mechanism of a nickel-based alloy after laser shock processing at high temperatures

PubMed Central

Li, Yinghong; Zhou, Liucheng; He, Weifeng; He, Guangyu; Wang, Xuede; Nie, Xiangfan; Wang, Bo; Luo, Sihai; Li, Yuqin

2013-01-01

We investigated the strengthening mechanism of laser shock processing (LSP) at high temperatures in the K417 nickel-based alloy. Using a laser-induced shock wave, residual compressive stresses and nanocrystals with a length of 30–200 nm and a thickness of 1 μm are produced on the surface of the nickel-based alloy K417. When the K417 alloy is subjected to heat treatment at 900 °C after LSP, most of the residual compressive stress relaxes while the microhardness retains good thermal stability; the nanocrystalline surface has not obviously grown after the 900 °C per 10 h heat treatment, which shows a comparatively good thermal stability. There are several reasons for the good thermal stability of the nanocrystalline surface, such as the low value of cold hardening of LSP, extreme high-density defects and the grain boundary pinning of an impure element. The results of the vibration fatigue experiments show that the fatigue strength of K417 alloy is enhanced and improved from 110 to 285 MPa after LSP. After the 900 °C per 10 h heat treatment, the fatigue strength is 225 MPa; the heat treatment has not significantly reduced the reinforcement effect. The feature of the LSP strengthening mechanism of nickel-based alloy at a high temperature is the co-working effect of the nanocrystalline surface and the residual compressive stress after thermal relaxation. PMID:27877617

Disk-based compression of data from genome sequencing.

PubMed

Grabowski, Szymon; Deorowicz, Sebastian; Roguski, Łukasz

2015-05-01

High-coverage sequencing data have significant, yet hard to exploit, redundancy. Most FASTQ compressors cannot efficiently compress the DNA stream of large datasets, since the redundancy between overlapping reads cannot be easily captured in the (relatively small) main memory. More interesting solutions for this problem are disk based, where the better of these two, from Cox et al. (2012), is based on the Burrows-Wheeler transform (BWT) and achieves 0.518 bits per base for a 134.0 Gbp human genome sequencing collection with almost 45-fold coverage. We propose overlapping reads compression with minimizers, a compression algorithm dedicated to sequencing reads (DNA only). Our method makes use of a conceptually simple and easily parallelizable idea of minimizers, to obtain 0.317 bits per base as the compression ratio, allowing to fit the 134.0 Gbp dataset into only 5.31 GB of space. http://sun.aei.polsl.pl/orcom under a free license. sebastian.deorowicz@polsl.pl Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

SIGNATURES OF GRAVITATIONAL INSTABILITY IN RESOLVED IMAGES OF PROTOSTELLAR DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Ruobing; Vorobyov, Eduard; Pavlyuchenkov, Yaroslav

2016-06-01

Protostellar (class 0/I) disks, which have masses comparable to those of their nascent host stars and are fed continuously from their natal infalling envelopes, are prone to gravitational instability (GI). Motivated by advances in near-infrared (NIR) adaptive optics imaging and millimeter-wave interferometry, we explore the observational signatures of GI in disks using hydrodynamical and Monte Carlo radiative transfer simulations to synthesize NIR scattered light images and millimeter dust continuum maps. Spiral arms induced by GI, located at disk radii of hundreds of astronomical units, are local overdensities and have their photospheres displaced to higher altitudes above the disk midplane; therefore,more » arms scatter more NIR light from their central stars than inter-arm regions, and are detectable at distances up to 1 kpc by Gemini/GPI, VLT/SPHERE, and Subaru/HiCIAO/SCExAO. In contrast, collapsed clumps formed by disk fragmentation have such strong local gravitational fields that their scattering photospheres are at lower altitudes; such fragments appear fainter than their surroundings in NIR scattered light. Spiral arms and streamers recently imaged in four FU Ori systems at NIR wavelengths resemble GI-induced structures and support the interpretation that FUors are gravitationally unstable protostellar disks. At millimeter wavelengths, both spirals and clumps appear brighter in thermal emission than the ambient disk and can be detected by ALMA at distances up to 0.4 kpc with one hour integration times at ∼0.″1 resolution. Collapsed fragments having masses ≳1 M {sub J} can be detected by ALMA within ∼10 minutes.« less

Electrochemical investigation of the voltammetric determination of hydrochlorothiazide using a nickel hydroxide modified nickel electrode.

PubMed

Machini, Wesley B S; David-Parra, Diego N; Teixeira, Marcos F S

2015-12-01

The preparation and electrochemical characterization of a nickel hydroxide modified nickel electrode as well as its behavior as electrocatalyst toward the oxidation of hydrochlorothiazide (HCTZ) were investigated. The electrochemical behavior of the modified electrode and the electrooxidation of HCTZ were explored using cyclic voltammetry. The voltammetric response of the modified electrode in the detection of HCTZ is based on the electrochemical oxidation of the Ni(II)/Ni(III) and a chemical redox process. The analytical parameters for the electrooxidation of HCTZ by the nickel hydroxide modified nickel electrode were obtained in NaOH solution, in which the linear voltammetric response was in the concentration range from 1.39×10(-5) to 1.67×10(-4)mol L(-1) with a limit of detection of 7.92×10(-6)mol L(-1) and a sensitivity of 0.138 μA Lmmol(-1). Tafel analysis was used to elucidate the kinetics and mechanism of HCTZ oxidation by the modified electrode. Copyright © 2015 Elsevier B.V. All rights reserved.

PROCESS OF COATING WITH NICKEL BY THE DECOMPOSITION OF NICKEL CARBONYL

DOEpatents

Hoover, T.B.

1959-04-01

An improved process is presented for the deposition of nickel coatings by the thermal decomposition of nickel carbonyl vapor. The improvement consists in incorporating a small amount of hydrogen sulfide gas in the nickel carbonyl plating gas. It is postulated that the hydrogen sulfide functions as a catalyst. i

Stability and Evolution of Supernova Fallback Disks

NASA Astrophysics Data System (ADS)

Menou, Kristen; Perna, Rosalba; Hernquist, Lars

2001-10-01

We show that thin accretion disks made of carbon or oxygen are subject to the same thermal ionization instability as hydrogen and helium disks. We argue that the instability applies to disks of any metal content. The relevance of the instability to supernova fallback disks probably means that their power-law evolution breaks down when they first become neutral. We construct simple analytical models for the viscous evolution of fallback disks to show that it is possible for these disks to become neutral when they are still young (ages of a few 103 to 104 yr), compact in size (a few 109 to 1011 cm) and generally accreting at sub-Eddington rates (M~a few 1014-1018 g s-1). Based on recent results on the nature of viscosity in the disks of close binaries, we argue that this time may also correspond to the end of the disk activity period. Indeed, in the absence of a significant source of viscosity in the neutral phase, the entire disk will likely turn to dust and become passive. We discuss various applications of the evolutionary model, including anomalous X-ray pulsars and young radio pulsars. Our analysis indicates that metal-rich fallback disks around newly born neutron stars and black holes become neutral generally inside the tidal truncation radius (Roche limit) for planets at ~1011 cm. Consequently, the efficiency of the planetary formation process in this context will mostly depend on the ability of the resulting disk of rocks to spread via collisions beyond the Roche limit. It appears easier for the merger product of a doubly degenerate binary, whether it is a massive white dwarf or a neutron star, to harbor planets because its remnant disk has a rather large initial angular momentum, which allows it to spread beyond the Roche limit before becoming neutral. The early super-Eddington phase of accretion is a source of uncertainty for the disk evolution models presented here.

Evaluation and Countermeasures on sustainable development of nickel resources in China

NASA Astrophysics Data System (ADS)

Lin, Zhifeng

2017-08-01

Nickel is an important strategic resource in China. With the gradual reduction of nickel re-sources and the increasing competition of the global mineral resources market, the safety of nickel resources in China has been seriously threatened. Therefore, it is very important to evaluate the sustainable develop-ment of nickel resources in China and put forward the corresponding countermeasures. In this paper, the concept and research situation of sustainable development are analyzed. Based on the specific development of nickel resources in China, this paper uses AHP to evaluate the safety of nickel resources in china. Finally, it puts forward the concrete measures to implement the sustainable development strategy of nickel resources in China.

Hot isostatically pressed manufacture of high strength MERL 76 disk and seal shapes

NASA Technical Reports Server (NTRS)

Eng, R. D.; Evans, D. J.

1982-01-01

The feasibility of using MERL 76, an advanced high strength direct hot isostatic pressed powder metallurgy superalloy, as a full scale component in a high technology, long life, commercial turbine engine were demonstrated. The component was a JT9D first stage turbine disk. The JT9D disk rim temperature capability was increased by at least 22 C and the weight of JT9D high pressure turbine rotating components was reduced by at least 35 pounds by replacement of forged Superwaspaloy components with hot isostatic pressed (HIP) MERL 76 components. The process control plan and acceptance criteria for manufacture of MERL 76 HIP consolidated components were generated. Disk components were manufactured for spin/burst rig test, experimental engine tests, and design data generation, which established lower design properties including tensile, stress-rupture, 0.2% creep and notched (Kt = 2.5) low cycle fatigue properties, Sonntag, fatigue crack propagation, and low cycle fatigue crack threshold data. Direct HIP MERL 76, when compared to conventionally forged Superwaspaloy, is demonstrated to be superior in mechanical properties, increased rim temperature capability, reduced component weight, and reduced material cost by at least 30% based on 1980 costs.

Observational constraints on black hole accretion disks

NASA Technical Reports Server (NTRS)

Liang, Edison P.

1994-01-01

We review the empirical constraints on accretion disk models of stellar-mass black holes based on recent multiwavelength observational results. In addition to time-averaged emission spectra, the time evolutions of the intensity and spectrum provide critical information about the structure, stability, and dynamics of the disk. Using the basic thermal Keplerian disk paradigm, we consider in particular generalizations of the standard optically thin disk models needed to accommodate the extremely rich variety of dynamical phenomena exhibited by black hole candidates ranging from flares of electron-positron annihilations and quasiperiodic oscillations in the X-ray intensity to X-ray novae activity. These in turn provide probes of the disk structure and global geometry. The goal is to construct a single unified framework to interpret a large variety of black hole phenomena. This paper will concentrate on the interface between basic theory and observational data modeling.

A FEM-based method to determine the complex material properties of piezoelectric disks.

PubMed

Pérez, N; Carbonari, R C; Andrade, M A B; Buiochi, F; Adamowski, J C

2014-08-01

Numerical simulations allow modeling piezoelectric devices and ultrasonic transducers. However, the accuracy in the results is limited by the precise knowledge of the elastic, dielectric and piezoelectric properties of the piezoelectric material. To introduce the energy losses, these properties can be represented by complex numbers, where the real part of the model essentially determines the resonance frequencies and the imaginary part determines the amplitude of each resonant mode. In this work, a method based on the Finite Element Method (FEM) is modified to obtain the imaginary material properties of piezoelectric disks. The material properties are determined from the electrical impedance curve of the disk, which is measured by an impedance analyzer. The method consists in obtaining the material properties that minimize the error between experimental and numerical impedance curves over a wide range of frequencies. The proposed methodology starts with a sensitivity analysis of each parameter, determining the influence of each parameter over a set of resonant modes. Sensitivity results are used to implement a preliminary algorithm approaching the solution in order to avoid the search to be trapped into a local minimum. The method is applied to determine the material properties of a Pz27 disk sample from Ferroperm. The obtained properties are used to calculate the electrical impedance curve of the disk with a Finite Element algorithm, which is compared with the experimental electrical impedance curve. Additionally, the results were validated by comparing the numerical displacement profile with the displacements measured by a laser Doppler vibrometer. The comparison between the numerical and experimental results shows excellent agreement for both electrical impedance curve and for the displacement profile over the disk surface. The agreement between numerical and experimental displacement profiles shows that, although only the electrical impedance curve is

Millimeter Studies of Nearby Debris Disks

NASA Astrophysics Data System (ADS)

MacGregor, Meredith Ann

2017-03-01

disk structure and dynamics, which can be explored further with a comparative study of a sample of the eight brightest debris disks around Sun-like stars within 20 pc (Chapter 9). This body of work has yielded the first resolved images of notable debris disks at millimeter wavelengths, and complements other ground- and space-based observations by providing constraints on these systems with uniquely high angular resolution and wavelength coverage. Together these results provide a foundation to investigate the dynamical evolution of planetary systems through multi-wavelength observations of debris disks.

Development of novel nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric.

PubMed

Bondar, Yuliia; Kuzenko, Svetlana; Han, Do-Hung; Cho, Hyun-Kug

2014-01-01

A nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric was synthesized for selective removal of Cs ions from contaminated waters by a two-stage synthesis: radiation-induced graft polymerization of acrylic acid monomer onto the nonwoven polypropylene fabric surface with subsequent in situ formation of potassium nickel hexacyanoferrate (KNiHCF) nanoparticles within the grafted chains. Data of scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy confirmed the formation of KNiHCF homogeneous phase on the fabric surface, which consisted of crystalline cubic-shaped nanoparticles (70 to 100 nm). The efficiency of the synthesized adsorbent for removal of cesium ions was evaluated under various experimental conditions. It has demonstrated a rapid adsorption process, high adsorption capacity over a wide pH range, and selectivity in Cs ion removal from model solutions with high concentration of sodium ions.

Evidence of carcinogenicity in humans of water-soluble nickel salts

PubMed Central

2010-01-01

Background Increased risks of nasal cancer and lung cancer in nickel refiners have been investigated scientifically and discussed since they were detected in the 1930s. Nickel compounds are considered to be the main cause of the cancer excess. Parts of the nickel producing industry and their consultants oppose the classification of water-soluble nickel salts as human carcinogens, and argue that the risk in exposed workers should be ascribed to other occupational exposures and smoking. Discussion Respiratory cancer risks in Welsh, Finnish, and Norwegian nickel refiners add to the evidence of carcinogenicity of water-soluble nickel. In Norwegian refiners, the first epidemiological study in 1973 identified high risks of lung cancer and nasal cancer among long-term electrolysis workers. Risk analyses based on exposure estimates developed in the 1980s supported the view that water-soluble nickel compounds were central in the development of cancer. Recently, new exposure estimates were worked out for the same cohort based on personal monitoring of total nickel and chemical determination of four forms of nickel. Additional data have been collected on life-time smoking habits, and on exposure to arsenic, asbestos, sulphuric acid mists, cobalt, and occupational lung carcinogens outside the refinery. After adjustment for these potential confounding exposures in case-control analyses, the risk pattern added to the evidence of an important role of water-soluble nickel compounds as causes of lung cancer. These Norwegian cancer studies rely on national Cancer Registry data, considered close to complete from 1953 onwards; and on National Population Register data continuously updated with mortality and emigration. Canadian mortality studies--perceived to offer the strongest support to the industry position not to recognise carcinogenicity of water-soluble nickel--appear to suffer from limitations in follow-up time, loss to follow-up, absence of risk analysis with individual

Non-blackbody Disks Can Help Explain Inferred AGN Accretion Disk Sizes

NASA Astrophysics Data System (ADS)

Hall, Patrick B.; Sarrouh, Ghassan T.; Horne, Keith

2018-02-01

If the atmospheric density {ρ }atm} in the accretion disk of an active galactic nucleus (AGN) is sufficiently low, scattering in the atmosphere can produce a non-blackbody emergent spectrum. For a given bolometric luminosity, at ultraviolet and optical wavelengths such disks have lower fluxes and apparently larger sizes as compared to disks that emit as blackbodies. We show that models in which {ρ }atm} is a sufficiently low fixed fraction of the interior density ρ can match the AGN STORM observations of NGC 5548 but produce disk spectral energy distributions that peak at shorter wavelengths than observed in luminous AGN in general. Thus, scattering atmospheres can contribute to the explanation for large inferred AGN accretion disk sizes but are unlikely to be the only contributor. In the appendix section, we present unified equations for the interior ρ and T in gas pressure-dominated regions of a thin accretion disk.

HST Observations of the Beta Pictoris Circumstellar Disk

NASA Astrophysics Data System (ADS)

Burrows, C. J.; Krist, J. E.; Stapelfeldt, K. R.; WFPC2 Investigation Definition Team

1995-12-01

The disk surrounding Beta Pictoris has been imaged with the Hubble Space Telescope Planetary Camera in the four photometric filters centered near 439, 555, 675 and 814 nm, and at a total of four different spacecraft roll angles. After masking the images to exclude the disk region, a composite PSF was constructed that enabled us to generate three statistically independent images of the disk for each filter. The images show the disk in reflected light from a radius of about 1.5 arcseconds to about 10 arcseconds. We have developed a full three dimensional simulation of the disk which reproduces the observed scattered light distribution and the known infrared photometry and direct imaging from IRAS and previous ground based investigations in a self-consistent manner. By least squares fitting all of the data we are able to derive geometric parameters of the disk and constrain the optical properties of its particles. The scattering is well described by small particles with a visible albedo of around 0.4 and a small scattering phase function variation. The inclination of the disk axis to the plane of the sky is only of order 1 degree. There is a relatively clear zone in the disk with the normal optical depth decreasing linearly within 40 AU from the star from a constant value of 0.005 between 40 and 100 AU. We find that the scale height of the disk is roughly constant within the inner 100 AU, while the outer disk has a linear scale height power law consistent with previous investigations. The disk density is not Gaussian in cross section, as might be expected for a Maxwellian distribution of similar particles, but exponential. We do not interpret this as evidence for pressure support, but rather as evidence for a particle mass spectrum. Several previously reported north-south disk asymmetries are evident in the data, but a significant new result is a rotationally symmetric warp in the inner disk. Detailed dynamical simulations based on the observed mass distribution and

Spitzer observations of NGC 2264: the nature of the disk population

NASA Astrophysics Data System (ADS)

Teixeira, P. S.; Lada, C. J.; Marengo, M.; Lada, E. A.

2012-04-01

Aims: NGC 2264 is a young cluster with a rich circumstellar disk population which makes it an ideal target for studying the evolution of stellar clusters. Our goal is to study the star formation history of NGC 2264 and to analyse the primordial disk evolution of its members. Methods: The study presented is based on data obtained with the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS) on board the Spitzer Space Telescope, combined with deep near-infrared (NIR) ground-based FLAMINGOS imaging and previously published optical data. Results: We build NIR dust extinction maps of the molecular cloud associated with the cluster, and determine it to have a mass of 2.1 × 103 M⊙ above an AV of 7 mag. Using a differential Ks-band luminosity function (KLF) of the cluster, we estimate the size of the population of NGC 2264, within the area observed by FLAMINGOS, to be 1436 ± 242 members. The star formation efficiency is ≥ ~25%. We identify the disk population and divide it into 3 groups based on their spectral energy distribution slopes from 3.6 μm to 8 μm and on the 24 μm excess emission: (i) optically thick inner disks, (ii) anaemic inner disks, and (iii) disks with inner holes, or transition disks. We analyse the spatial distribution of these sources and find that sources with thick disks segregate into sub-clusterings, whereas sources with anaemic disks do not. Furthermore, sources with anaemic disks are found to be unembedded (i.e., with AV < 3 mag), whereas the clustered sources with thick disks are still embedded within the parental cloud. Conclusions: NGC 2264 has undergone more than one star-forming event, where the anaemic and extincted thick disk population appear to have formed in separate episodes: the sources with anaemic disks are more evolved and have had time to disperse and populate a halo of the cluster. We also find tentative evidence of triggered star-formation in the Fox Fur Nebula. In terms of disk evolution

First Detection of Near-infrared Line Emission from Organics in Young Circumstellar Disks

NASA Astrophysics Data System (ADS)

Mandell, Avi M.; Bast, Jeanette; van Dishoeck, Ewine F.; Blake, Geoffrey A.; Salyk, Colette; Mumma, Michael J.; Villanueva, Geronimo

2012-03-01

We present an analysis of high-resolution spectroscopy of several bright T Tauri stars using the CRIRES spectrograph on the Very Large Telescope and NIRSPEC spectrograph on the Keck Telescope, revealing the first detections of emission from HCN and C2H2 in circumstellar disks at near-infrared wavelengths. Using advanced data reduction techniques, we achieve a dynamic range with respect to the disk continuum of ~500 at 3 μm, revealing multiple emission features of H2O, OH, HCN, and C2H2. We also present stringent upper limits for two other molecules thought to be abundant in the inner disk, CH4 and NH3. Line profiles for the different detected molecules are broad but centrally peaked in most cases, even for disks with previously determined inclinations of greater than 20°, suggesting that the emission has both a Keplerian and non-Keplerian component as observed previously for CO emission. We apply two different modeling strategies to constrain the molecular abundances and temperatures: we use a simplified single-temperature local thermal equilibrium (LTE) slab model with a Gaussian line profile to make line identifications and determine a best-fit temperature and initial abundance ratios, and we compare these values with constraints derived from a detailed disk radiative transfer model assuming LTE excitation but utilizing a realistic temperature and density structure. Abundance ratios from both sets of models are consistent with each other and consistent with expected values from theoretical chemical models, and analysis of the line shapes suggests that the molecular emission originates from within a narrow region in the inner disk (R < 1 AU). Based partially on observations collected at the European Southern Observatory Very Large Telescope under program ID 179.C-0151, program ID 283.C-5016, and program ID 082.C-0432 (P.I.: Pontopiddan).

Floppy disk utility user's guide

NASA Technical Reports Server (NTRS)

Akers, J. W.

1981-01-01

The Floppy Disk Utility Program transfers programs between files on the hard disk and floppy disk. It also copies the data on one floppy disk onto another floppy disk and compares the data. The program operates on the Data General NOVA-4X under the Real Time Disk Operating System (RDOS).

Optical Disk Technology.

ERIC Educational Resources Information Center

Abbott, George L.; And Others

1987-01-01

This special feature focuses on recent developments in optical disk technology. Nine articles discuss current trends, large scale image processing, data structures for optical disks, the use of computer simulators to create optical disks, videodisk use in training, interactive audio video systems, impacts on federal information policy, and…

Corrosion characteristics of nickel alloys. Citations from the International Aerospace Abstracts data base

NASA Technical Reports Server (NTRS)

Zollars, G. F.

1979-01-01

This bibliography cites 118 articles from the international literature concerning corrosion characteristics of nickel alloys. Articles dealing with corrosion resistance, corrosion tests, intergranular corrosion, oxidation resistance, and stress corrosion cracking of nickel alloys are included.

Solid-State Metalized Reduction of Magnesium-Rich Low-Nickel Oxide Ores Using Coal as the Reductant Based on Thermodynamic Analysis

NASA Astrophysics Data System (ADS)

Ma, Baozhong; Xing, Peng; Yang, Weijiao; Wang, Chengyan; Chen, Yongqiang; Wang, Hua

2017-08-01

The solid-state metalized reduction of magnesium-rich low-nickel oxide ore using coal as a reductant was studied based on thermodynamic analysis. The major constituent minerals of the ore were silicates and goethite. The former was the main nickel-bearing mineral, and the latter was the main iron-bearing mineral. Single factor tests were conducted to investigate the effects of reduction temperature, duration, and coal dosage on the beneficiation of nickel and iron such that optimal conditions were achieved. Considering the low recoveries of nickel and iron (Ni, 13.9 pct; Fe, 30.3 pct) under the obtained optimal conditions, an improved process, adding CaF2 before the reaction, was proposed to modify the solid-state metalized process. The results showed that the recoveries of nickel and iron reached to 96.5 and 73.4 pct, respectively, and that the grades of nickel and iron in the concentrate increased from 2.5 and 62.6 wt pct to 6.9 and 71.4 wt pct, respectively. Nickel and iron in the absence of CaF2 were metalized; nevertheless, the size of ferronickel particles was only 1 μm. Furthermore, alloys in the presence of CaF2 aggregated and exhibited bands with a length greater than 200 µm. These observations suggested that CaF2 could effectively reduce the surface tension of the newly generated alloy interface and promote the migration and polymerization of the alloy particles, which improves the beneficiation of nickel and iron by magnetic separation.

Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk Around PDS 70: Observations of the Disk

NASA Technical Reports Server (NTRS)

Hashimoto, J.; Dong, R.; Kudo, T.; Honda, M.; McClure, M. K.; Zhu, Z.; Muto, T.; Wisniewski, J.; Abe, L.; Brandner, W.;

Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk Around PDS 70: Observations of the Disk

NASA Technical Reports Server (NTRS)

Hashimoto, J.; Dong, R.; Kudo, T.; Honda, M.; Zhu, Z.; McClure, M. K.; Muto, T.; Wisniewski, J.; Abe, L.; Brandner, W.;

Biosensors Based on Urease Adsorbed on Nickel, Platinum, and Gold Conductometric Transducers Modified with Silicalite and Nanozeolites

NASA Astrophysics Data System (ADS)

Kucherenko, Ivan S.; Soldatkin, Oleksandr O.; Kasap, Berna Ozansoy; Kurç, Burcu Akata; Melnyk, Volodymir G.; Semenycheva, Lyudmila M.; Dzyadevych, Sergei V.; Soldatkin, Alexei P.

This work describes urease-based conductometric biosensors that were created using nontypical method of urease immobilization via adsorption on micro- and nanoporous particles: silicalite and nanocrystalline zeolites Beta (BEA) and L. Conductometric transducers with nickel, gold, and platinum interdigitated electrodes were used. Active regions of the nickel transducers were modified with microparticles using two procedures—spin coating and drop coating. Gold and platinum transducers were modified with silicalite using drop coating since it was more effective. Scanning electron microscopy was used to evaluate effectiveness of these procedures. The procedure of spin coating produced more uniform layers of particles (and biosensors had good reproducibility of preparation), but it was more complicated, drop coating was easier and led to formation of a bulk of particles; thus, biosensors had bigger sensitivity but worse reproducibility of preparation. Urease was immobilized onto transducers modified with particles by physical adsorption. Analytical characteristics of the obtained biosensors for determination of urea (calibration curves, sensitivity, limit of detection, linear concentration range, noise of responses, reproducibility of signal during a day, and operational stability during 3 days) were compared. Biosensors with all three particles deposited by spin coating showed similar characteristics; however, silicalite was a bit more effective. Biosensors based on nickel transducers modified by drop coating had better characteristics in comparison with modification by spin coating (except reproducibility of preparation). Transducers with gold electrodes showed best characteristics while creating biosensors, platinum electrodes were slightly inferior to them, and nickel electrodes were the worst.

Understanding Floppy Disks.

ERIC Educational Resources Information Center

Valentine, Pamela

1980-01-01

The author describes the floppy disk with an analogy to the phonograph record, and discusses the advantages, disadvantages, and capabilities of hard-sectored and soft-sectored floppy disks. She concludes that, at present, the floppy disk will continue to be the primary choice of personal computer manufacturers and their customers. (KC)

Lightweight, direct-radiating nickel hydrogen batteries

NASA Technical Reports Server (NTRS)

Metcalfe, J. R.

1986-01-01

Two battery module configurations were developed which, in addition to integrating cylindrical nickel hydrogen (NiH2) cells into batteries, provide advances in the means of mounting, monitoring and thermal control of these cells. The main difference between the two modules is the physical arrangement of the cells: vertical versus horizontal. Direct thermal radiation to deep space is accomplished by substituting the battery structure for an exterior spacecraft panel. Unlike most conventional nickel-cadmium (NiCd) and NiH2 batteries, the cells are not tightly packed together; therefore ancillary heat conducting media to outside radiating areas, and spacecraft deck reinforcements for high mass concentration are not necessary. Testing included electrical characterization and a comprehensive regime of environmental exposures. The designs are flexible with respect to quantity and type of cells, orbit altitude and period, power demand profile, and the extent of cell parameter monitoring. This paper compares the characteristics of the two battery modules and summarizes their performance.

Nature vs. Nurture: The influence of OB star environments on proto-planetary disk evolution.

NASA Astrophysics Data System (ADS)

Bouwman, Jeroen; Feigelson, Eric; Getman, Kostantin; Henning, Thomas; Lawson, Warrick; Linz, Hendrik; Luhman, Kevin; Roccatagliata, Veronica; Sicilia Aguilar, Aurora; Townsley, Leisa; Wang, Junfeng

2006-05-01

A natural approach for understanding the origin and diversity of planetary systems is to study the birth sites of planetary systems under varying environmental conditions. Dust grains in protoplanetary disks, the building blocks of planets, are structurally and chemically altered, and grow through coagulation into planetesimals. The disk geometry may change from a flaring to a more flattened structure, gaps may develop under the gravitational influence of protoplanets, and eventually the disk will dissipate, terminating the planet formation process. While the infrared properties of disks in quiet cloud environments have been extensively studied, investigations under the conditions of strong UV radiation and stellar winds in the proximity of OB stars have been limited. We propose a combined IRAC/IRS study of a large, well-defined and unbiased X-ray selected sample of pre-main-sequence stars in three OB associations: Pismis 24 in NGC 6357, NGC 2244 in the Rosette Nebula, and IC 1795 in the W3 complex. The samples are based on recent Chandra X-ray Observatory studies which reliably identify hundreds of cluster members and were carefully chosen to avoid high infrared nebular background. A new Chandra exposure of IC 1795 is requested, and an optical followup to characterise the host stars is planned. Modelling the Spitzer findings will provide the composition and size of dust present as well as the geometry, mass, and gaps in the global structure of the disk. As hundreds of cluster members will be covered with IRAC and dozens with IRS, good statistics on the disk evolution and dispersal as a function of location with respect to OB stars will be obtained. Comparison of disk properties within our sample and with existing Spitzer studies of quiescent star-forming regions should significantly advance the aim of characterising the influence of the environment on the evolution of protoplanetary disks. This effort relies on a powerful synergy between the Chandra and Spitzer

OT1_ipascucc_1: Understanding the Origin of Transition Disks via Disk Mass Measurements

NASA Astrophysics Data System (ADS)

Pascucci, I.

2010-07-01

Transition disks are a distinguished group of few Myr-old systems caught in the phase of dispersing their inner dust disk. Three different processes have been proposed to explain this inside-out clearing: grain growth, photoevaporation driven by the central star, and dynamical clearing by a forming giant planet. Which of these processes lead to a transition disk? Distinguishing between them requires the combined knowledge of stellar accretion rates and disk masses. We propose here to use 43.8 hours of PACS spectroscopy to detect the [OI] 63 micron emission line from a sample of 21 well-known transition disks with measured mass accretion rates. We will use this line, in combination with ancillary CO millimeter lines, to measure their gas disk mass. Because gas dominates the mass of protoplanetary disks our approach and choice of lines will enable us to trace the bulk of the disk mass that resides beyond tens of AU from young stars. Our program will quadruple the number of transition disks currently observed with Herschel in this setting and for which disk masses can be measured. We will then place the transition and the ~100 classical/non-transition disks of similar age (from the Herschel KP "Gas in Protoplanetary Systems") in the mass accretion rate-disk mass diagram with two main goals: 1) reveal which gaps have been created by grain growth, photoevaporation, or giant planet formation and 2) from the statistics, determine the main disk dispersal mechanism leading to a transition disk.

Floppy disk utility user's guide

NASA Technical Reports Server (NTRS)

Akers, J. W.

1980-01-01

A floppy disk utility program is described which transfers programs between files on a hard disk and floppy disk. It also copies the data on one floppy disk onto another floppy disk and compares the data. The program operates on the Data General NOVA-4X under the Real Time Disk Operating System. Sample operations are given.

Hydrodynamic Simulations of Protoplanetary Disks with GIZMO

NASA Astrophysics Data System (ADS)

Rice, Malena; Laughlin, Greg

2018-01-01

Over the past several decades, the field of computational fluid dynamics has rapidly advanced as the range of available numerical algorithms and computationally feasible physical problems has expanded. The development of modern numerical solvers has provided a compelling opportunity to reconsider previously obtained results in search for yet undiscovered effects that may be revealed through longer integration times and more precise numerical approaches. In this study, we compare the results of past hydrodynamic disk simulations with those obtained from modern analytical resources. We focus our study on the GIZMO code (Hopkins 2015), which uses meshless methods to solve the homogeneous Euler equations of hydrodynamics while eliminating problems arising as a result of advection between grid cells. By comparing modern simulations with prior results, we hope to provide an improved understanding of the impact of fluid mechanics upon the evolution of protoplanetary disks.

DVD - digital versatile disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaunt, R.

1997-05-01

:9 widescreen. MPEG-2 is the selected image compression format, with full ITU Rec. 601 video resolution (72Ox480). MPEG-2 and AC-3 are also part of the U.S. high definition Advance Television standard (ATV). DVD has an average video bit rate of 3.5 Mbits/sec or 4.69Mbits/sec for image and sound. Unlike digital television transmission, which will use fixed length packets for audio and video, DVD will use variable length packets with a maximum throughput of more than 1OMbits/sec. The higher bit rate allows for less compression of difficult to encode material. Even with all the compression, narrow-beam red light lasers are required to significantly increase the physical data density of a platter by decreasing the size of the pits. This allows 4.7 gigabytes of data on a single sided, single layer DVD. The maximum 17 gigabyte capacity is achieved by employing two reflective layers on both sides of the disk. To read the imbedded layer of data, the laser`s focal length is altered so that the top layer pits are not picked up by the reader. It will be a couple of years before we have dual-layer, double-sided DVDS, and it will be achieved in four stages. The first format to appear will be the single sided, single layer disk (4.7 gigabytes). That will allow Hollywood to begin releasing DVD movie titles. DVD-ROM will be the next phase, allowing 4.7 gigabytes of CD-ROM-like content. The third stage will be write-once disks, and stage four will be rewritable disks. These last stages presents some issues which have yet to be resolved. For one, copyrighted materials may have some form of payment system, and there is the issue that erasable disks reflect less light than today`s DVDS. The problem here is that their data most likely will not be readable on earlier built players.« less

Exploring Disks Around Planets

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-07-01

Giant planets are thought to form in circumstellar disks surrounding young stars, but material may also accrete into a smaller disk around the planet. Weve never detected one of these circumplanetary disks before but thanks to new simulations, we now have a better idea of what to look for.Image from previous work simulating a Jupiter-mass planet forming inside a circumstellar disk. The planet has its own circumplanetary disk of accreted material. [Frdric Masset]Elusive DisksIn the formation of giant planets, we think the final phase consists of accretion onto the planet from a disk that surrounds it. This circumplanetary disk is important to understand, since it both regulates the late gas accretion and forms the birthplace of future satellites of the planet.Weve yet to detect a circumplanetary disk thus far, because the resolution needed to spot one has been out of reach. Now, however, were entering an era where the disk and its kinematics may be observable with high-powered telescopes (like the Atacama Large Millimeter Array).To prepare for such observations, we need models that predict the basic characteristics of these disks like the mass, temperature, and kinematic properties. Now a researcher at the ETH Zrich Institute for Astronomy in Switzerland, Judit Szulgyi, has worked toward this goal.Simulating CoolingSzulgyi performs a series of 3D global radiative hydrodynamic simulations of 1, 3, 5, and 10 Jupiter-mass (MJ) giant planets and their surrounding circumplanetary disks, embedded within the larger circumstellar disk around the central star.Density (left column), temperature (center), and normalized angular momentum (right) for a 1 MJ planet over temperatures cooling from 10,000 K (top) to 1,000 K (bottom). At high temperatures, a spherical circumplanetary envelope surrounds the planet, but as the planet cools, the envelope transitions around 64,000 K to a flattened disk. [Szulgyi 2017]This work explores the effects of different planet temperatures and

The structure and properties of a nickel-base superalloy produced by osprey atomization-deposition

NASA Astrophysics Data System (ADS)

Bricknell, Rodger H.

1986-04-01

The production of a nickel-base superalloy, René* 80, by the Osprey atomization-deposition process has been investigated. Dense (>99 pct) material with a fine-grained equiaxed microstructure was deposited using either argon or nitrogen as the atomizing gas. Defects present in the material included a chill region at the collector plate interface, entrapped recirculated particles, porosity, and ceramic particles from the melting and dispensing system. In contrast to other rapid solidification techniques, low oxygen pick-ups are noted in the current technique. Tensile strengths above those displayed by castings are found in both nitrogen and argon atomized material, and in both the as-deposited and heat treated conditions. In addition, no profound mid-temperature ductility loss is displayed by this low oxygen material, in contrast to results on other rapidly solidified material with high oxygen contents. These results are explained in terms of oxygen embrittlement. In view of the excellent properties measured, the attractive economics of the process, and the fact that fine control of the gas/metal flow ratio is shown to be unnecessary, it is concluded that atomization-deposition presents an attractive potential production route for advanced alloys.

Nickel exposure and plasma levels of biomarkers for assessing oxidative stress in nickel electroplating workers.

PubMed

Tsao, Yu-Chung; Gu, Po-Wen; Liu, Su-Hsun; Tzeng, I-Shiang; Chen, Jau-Yuan; Luo, Jiin-Chyuan John

2017-07-01

The mechanism of nickel-induced pathogenesis remains elusive. To examine effects of nickel exposure on plasma oxidative and anti-oxidative biomarkers. Biomarker data were collected from 154 workers with various levels of nickel exposure and from 73 controls. Correlations between nickel exposure and oxidative and anti-oxidative biomarkers were determined using linear regression models. Workers with a exposure to high nickel levels had significantly lower levels of anti-oxidants (glutathione and catalase) than those with a lower exposure to nickel; however, only glutathione showed an independent association after multivariable adjustment. Exposure to high levels of nickel may reduce serum anti-oxidative capacity.

NICKEL COATED URANIUM ARTICLE

DOEpatents

Gray, A.G.

1958-10-01

Nickel coatings on uranium and various methods of obtaining such coatings are described. Specifically disclosed are such nickel or nickel alloy layers as barriers between uranium and aluminum- silicon, chromium, or copper coatings.

Multiwavelength interferometric observations and modeling of circumstellar disks

NASA Astrophysics Data System (ADS)

Schegerer, A. A.; Ratzka, T.; Schuller, P. A.; Wolf, S.; Mosoni, L.; Leinert, Ch.

2013-07-01

Aims: We investigate the structure of the innermost region of three circumstellar disks around pre-main sequence stars HD 142666, AS 205 N, and AS 205 S. We determine the inner radii of the dust disks and, in particular, search for transition objects where dust has been depleted and inner disk gaps have formed at radii of a few tenths of AU up to several AU. Methods: We performed interferometric observations with IOTA, AMBER, and MIDI in the infrared wavelength ranges 1.6-2.5 μm and 8-13 μm with projected baseline lengths between 25 m and 102 m. The data analysis was based on radiative transfer simulations in 3D models of young stellar objects (YSOs) to reproduce the spectral energy distribution and the interferometric visibilities simultaneously. Accretion effects and disk gaps could be considered in the modeling approach. Results from previous studies restricted the parameter space. Results: The objects of this study were spatially resolved in the infrared wavelength range using the interferometers. Based on these observations, a disk gap could be found for the source HD 142666 that classifies it as transition object. There is a disk hole up to a radius of Rin = 0.30 AU and a (dust-free) ring between 0.35 AU and 0.80 AU in the disk of HD 142666. The classification of AS 205 as a system of classical T Tauri stars could be confirmed using the canonical model approach, i.e., there are no hints of disk gaps in our observations. Based on observations made with telescopes of the European Organisation for Astronomical Research in the southern Hemisphere (ESO) at the Paranal Observatory, Chile, under the programs 073.A-9014, 075.C-0014, 075.C-0064, 075.C-0253, 077.C-0750, 079.C-0101, and 079.C-0595.Appendix A is available in electronic form at http://www.aanda.org

Ferrous sulfate based low temperature synthesis and magnetic properties of nickel ferrite nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tejabhiram, Y., E-mail: tejabhiram@gmail.com; Pradeep, R.; Helen, A.T.

2014-12-15

Highlights: • Novel low temperature synthesis of nickel ferrite nanoparticles. • Comparison with two conventional synthesis techniques including hydrothermal method. • XRD results confirm the formation of crystalline nickel ferrites at 110 °C. • Superparamagnetic particles with applications in drug delivery and hyperthermia. • Magnetic properties superior to conventional methods found in new process. - Abstract: We report a simple, low temperature and surfactant free co-precipitation method for the preparation of nickel ferrite nanostructures using ferrous sulfate as the iron precursor. The products obtained from this method were compared for their physical properties with nickel ferrites produced through conventional co-precipitationmore » and hydrothermal methods which used ferric nitrate as the iron precursor. X-ray diffraction analysis confirmed the synthesis of single phase inverse spinel nanocrystalline nickel ferrites at temperature as low as 110 °C in the low temperature method. Electron microscopy analysis on the samples revealed the formation of nearly spherical nanostructures in the size range of 20–30 nm which are comparable to other conventional methods. Vibrating sample magnetometer measurements showed the formation of superparamagnetic particles with high magnetic saturation 41.3 emu/g which corresponds well with conventional synthesis methods. The spontaneous synthesis of the nickel ferrite nanoparticles by the low temperature synthesis method was attributed to the presence of 0.808 kJ mol{sup −1} of excess Gibbs free energy due to ferrous sulfate precursor.« less

Interaction of nickel-based SOFC anodes with trace contaminants from coal-derived synthesis gas

NASA Astrophysics Data System (ADS)

Hackett, Gregory Allen

New and efficient methods of producing electrical energy from natural resources have become an important topic for researchers. Integrated gasification and fuel cell (IGFC) systems offer a fuel-flexible, high-efficiency method of energy generation. Specifically, in coal gasification processes, coal can be changed into a high-quality gaseous fuel suitable for feeding solid oxide fuel cells (SOFCs). However, trace species found in coal synthesis gas (syngas) may have a deleterious effect on the performance of nickel-based SOFC anodes. Generally, the cost of removing these species down to parts per million (ppm) levels is high. The purpose of this research is to determine the highest amount of contaminant that results in a low rate (˜1% per 1000 h) of cell performance degradation, allowing the SOFC to produce usable power for 40,000 hours. The cell performance degradation rate was determined for benzene, naphthalene, and mercury-doped syngas based on species concentration. Experimental data are fitted with degradation models to predict cell lifetime behavior. From these results, the minimum coal syngas cleanup required for these trace materials is determined. It is found that for a final cell voltage of 0.6 V, naphthalene and benzene must be cleaned to 360 ppm and less than 150 ppm, respectively. No additional cleaning is required for mercury beyond established environmental standards. Additionally, a detailed attack and recovery mechanism is proposed for the hydrocarbon species and their interaction with the fuel cell. This mechanism is proposed by considering the type of degradation models predicted and how carbon would interact with the Ni-YSZ anode to justify those models. The mechanism postulates that carbon is diffusing into the nickel structure, creating a metal solution. Once the nickel is saturated, the carbon begins to deposit on the nickel surface, reducing the electrode active area. The formation of metal solutions and the deposition of carbon results in

High-temperature characteristics of advanced Ni-MH batteries using nickel electrodes containing CaF 2

NASA Astrophysics Data System (ADS)

Zhang, Xuezeng; Gong, Zhixin; Zhao, Shumei; Geng, Mingming; Wang, Yan; Northwood, Derek O.

The high-temperature charge acceptance of Ni-MH batteries has been improved through the addition of calcium fluoride to the pasted nickel hydroxide electrode made using spherical Co(OH) 2-coated nickel hydroxide powder. The charge acceptance of the Ni-MH battery at 60 °C is over 95% at 1 C charge/discharge rates. The charge acceptance at 60 °C remains at over 90% through 10 cycles. The use of Co(OH) 2-coated Ni(OH) 2 plus a CaF 2 addition to the positive electrode also significantly improved the high-temperature stability in terms of reduced gas evolution.

Mechanisms of nickel toxicity in microorganisms

PubMed Central

Macomber, Lee

2014-01-01

Summary Nickel has long been known to be an important human toxicant, including having the ability to form carcinomas, but until recently nickel was believed to be an issue only to microorganisms living in nickel-rich serpentine soils or areas contaminated by industrial pollution. This assumption was overturned by the discovery of a nickel defense system (RcnR/RcnA) found in microorganisms that live in a wide range of environmental niches, suggesting that nickel homeostasis is a general biological concern. To date, the mechanisms of nickel toxicity in microorganisms and higher eukaryotes are poorly understood. In this review, we summarize nickel homeostasis processes used by microorganisms and highlight in vivo and in vitro effects of exposure to elevated concentrations of nickel. On the basis of this evidence we propose four mechanisms of nickel toxicity: 1) nickel replaces the essential metal of metalloproteins, 2) nickel binds to catalytic residues of non-metalloenzymes; 3) nickel binds outside the catalytic site of an enzyme to inhibit allosterically, and 4) nickel indirectly causes oxidative stress. PMID:21799955

THE STELLAR SPHEROID, THE DISK, AND THE DYNAMICS OF THE COSMIC WEB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Domínguez-Tenreiro, R.; Obreja, A.; Brook, C. B.

Models of the advanced stages of gravitational instability predict that baryons that form the stellar populations of current galaxies at z = 0 displayed a web-like structure at high z, as part of the cosmic web (CW). We explore details of these predictions using cosmological hydrodynamical simulations. When the stellar populations of the spheroid and disk components of simulated late-type galaxies are traced back separately to high zs we found CW-like structures where spheroid progenitors are more evolved than disk progenitors. The distinction between the corresponding stellar populations, as driven by their specific angular momentum content j, can be explainedmore » in terms of the CW evolution, extended to two processes occurring at lower z. First, the spheroid progenitors strongly lose j at collapse, which contrasts with the insignificant j loss of the disk progenitors. The second is related to the lack of alignment, at assembly, between the spheroid-to-be material and the already settled proto-disk, in contrast to the alignment of disk-to-be material, in some cases resulting from circumgalactic, disk-induced gravitational torques. The different final outcomes of these low-z processes have their origins in the different initial conditions driven by the CW dynamics.« less

Development of novel nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric

PubMed Central

2014-01-01

A nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric was synthesized for selective removal of Cs ions from contaminated waters by a two-stage synthesis: radiation-induced graft polymerization of acrylic acid monomer onto the nonwoven polypropylene fabric surface with subsequent in situ formation of potassium nickel hexacyanoferrate (KNiHCF) nanoparticles within the grafted chains. Data of scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy confirmed the formation of KNiHCF homogeneous phase on the fabric surface, which consisted of crystalline cubic-shaped nanoparticles (70 to 100 nm). The efficiency of the synthesized adsorbent for removal of cesium ions was evaluated under various experimental conditions. It has demonstrated a rapid adsorption process, high adsorption capacity over a wide pH range, and selectivity in Cs ion removal from model solutions with high concentration of sodium ions. PMID:24725367

Disk MHD generator study

NASA Technical Reports Server (NTRS)

Retallick, F. D.

1980-01-01

Directly-fired, separately-fired, and oxygen-augmented MHD power plants incorporating a disk geometry for the MHD generator were studied. The base parameters defined for four near-optimum-performance MHD steam power systems of various types are presented. The finally selected systems consisted of (1) two directly fired cases, one at 1920 K (2996F) preheat and the other at 1650 K (2500 F) preheat, (2) a separately-fired case where the air is preheated to the same level as the higher temperature directly-fired cases, and (3) an oxygen augmented case with the same generator inlet temperature of 2839 (4650F) as the high temperature directly-fired and separately-fired cases. Supersonic Mach numbers at the generator inlet, gas inlet swirl, and constant Hall field operation were specified based on disk generator optimization. System pressures were based on optimization of MHD net power. Supercritical reheat stream plants were used in all cases. Open and closed cycle component costs are summarized and compared.

Probabilistic Analysis of Aircraft Gas Turbine Disk Life and Reliability

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Zaretsky, Erwin V.; August, Richard

1999-01-01

Two series of low cycle fatigue (LCF) test data for two groups of different aircraft gas turbine engine compressor disk geometries were reanalyzed and compared using Weibull statistics. Both groups of disks were manufactured from titanium (Ti-6Al-4V) alloy. A NASA Glenn Research Center developed probabilistic computer code Probable Cause was used to predict disk life and reliability. A material-life factor A was determined for titanium (Ti-6Al-4V) alloy based upon fatigue disk data and successfully applied to predict the life of the disks as a function of speed. A comparison was made with the currently used life prediction method based upon crack growth rate. Applying an endurance limit to the computer code did not significantly affect the predicted lives under engine operating conditions. Failure location prediction correlates with those experimentally observed in the LCF tests. A reasonable correlation was obtained between the predicted disk lives using the Probable Cause code and a modified crack growth method for life prediction. Both methods slightly overpredict life for one disk group and significantly under predict it for the other.

Equilibrium configuration of a stratus floating above accretion disks: Full-disk calculation

NASA Astrophysics Data System (ADS)

Itanishi, Yusuke; Fukue, Jun

2017-06-01

We examine floating strati above a luminous accretion disk, supported by the radiative force from the entire disk, and calculate the equilibrium locus, which depends on the disk luminosity and the optical depth of the stratus. Due to the radiative transfer effect (albedo effect), the floating height of the stratus with a finite optical depth generally becomes high, compared with the particle case. In contrast to the case of the near-disk approximation, moreover, the floating height becomes yet higher in the present full-disk calculation, since the intense radiation from the inner disk is taken into account. As a result, when the disk luminosity normalized by the Eddington luminosity is ˜0.3 and the stratus optical depth is around unity, the stable configuration disappears at around r ˜ 50 rg, rg being the Schwarzschild radius, and the stratus would be blown off as a cloudy wind consisting of many strati with appropriate conditions. This luminosity is sufficiently smaller than the Eddington one, and the present results suggest that the radiation-driven cloudy wind can be easily blown off from the sub-Eddington disk, and this can explain various outflows observed in ultra-fast outflow objects as well as in broad-absorption-line quasars.

Glass rupture disk

DOEpatents

Glass, S. Jill; Nicolaysen, Scott D.; Beauchamp, Edwin K.

2002-01-01

A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

Tungsten wire-nickel base alloy composite development

NASA Technical Reports Server (NTRS)

Brentnall, W. D.; Moracz, D. J.

1976-01-01

Further development and evaluation of refractory wire reinforced nickel-base alloy composites is described. Emphasis was placed on evaluating thermal fatigue resistance as a function of matrix alloy composition, fabrication variables and reinforcement level and distribution. Tests for up to 1,000 cycles were performed and the best system identified in this current work was 50v/o W/NiCrAlY. Improved resistance to thermal fatigue damage would be anticipated for specimens fabricated via optimized processing schedules. Other properties investigated included 1,093 C (2,000 F) stress rupture strength, impact resistance and static air oxidation. A composite consisting of 30v/o W-Hf-C alloy fibers in a NiCrAlY alloy matrix was shown to have a 100-hour stress rupture strength at 1,093 C (2,000 F) of 365 MN/square meters (53 ksi) or a specific strength advantage of about 3:1 over typical D.S. eutectics.

Oxidation and thermal fatigue of coated and uncoated NX-188 nickel-base alloy in a high velocity gas stream

NASA Technical Reports Server (NTRS)

Johnson, J. R.; Young, S. G.

1972-01-01

A cast nickel-base superalloy, NX-188, coated and uncoated, was tested in a high-velocity gas stream for resistance to oxidation and thermal fatigue by cycling between room temperature and 980, 1040, and 1090 C. Contrary to the behavior of more conventional nickel-base alloys, uncoated NX-188 exhibited the greatest weight loss at the lowest test temperature. In general, on the basis of weight change and metallographic observations a coating consisting of vapor-deposited Fe-Cr-Al-Y over a chromized substrate exhibited the best overall performance in resistance to oxidation and thermal fatigue.

Inner Disk Structure and Transport Mechanisms in the Transitional Disk around T Cha

NASA Astrophysics Data System (ADS)

Brown, Alexander

2017-08-01

To better understand how Earth-like planets form around low-mass stars, we propose to study the UV (HST), X-ray (XMM), and optical (LCOGT) variability of the young star T Cha. This variability is caused by obscuration of the star by clumpy material in the rim of its inner disk. Changing sight lines through the disk allow measurement of the temperature and column density of both molecular and atomic gas and the physical properties of the dust grains in the well-mixed inner disk, as well as determining the gas-to-dust ratio. The gas-to-dust ratio affects planetesimal growth and disk stability but is difficult to measure in local regions of disks. Three 5 orbit visits, separated by 3-7 days, are required for use of analysis techniques comprising both differential pair-method comparison of spectra with differing A_v (particularly important for determining the dust extinction curve, A_lambda, where removal of the foreground extinction requires multiple epochs) and detailed spectral fitting of gas absorption features at each epoch. The inner disk of T Cha is particularly interesting, because T Cha has a transitional disk with a large gap at 0.2-15 AU in the dust disk and allows study of the gas and dust structure in the terrestrial planet formation zone during this important rapid phase of protoplanetary disk evolution. Characterizing the high energy (UV/X-ray) radiation field is also essential for in-depth studies of the disk in other spectral regions. Results from these observations will have wide relevance to the modeling and understanding of protoplanetary disk structure and evolution, and the complex gas and dust physics and chemistry in disk surface layers.

Infrared interferometric observations of nearby exozodiacal disks: current status and perspectives

NASA Astrophysics Data System (ADS)

Defrère, D.; Absil, O.; di Folco, E.; Coudé du Foresto, V.; Mérand, A.; Augereau, J.-C.

2010-10-01

Directly detecting exozodiacal dust in the inner part of extrasolar planetary systems is nowadays feasible thanks to the advance of high-precision near-infrared interferometry. Investigating this region around nearby stars provides unique information to understand the global architecture of planetary systems and to define the population of stars suitable for future exo-Earth characterization missions. Over the last few years, a survey of nearby main-sequence stars has been ongoing at the CHARA array using the FLUOR beam combiner. The goal of this survey is to directly probe the inner part of circumstellar disks in order to detect the signature of hot dust accounting for about 1% of the near-infrared stellar flux. In this paper, we present the status of this survey and provide the first statistical results about the occurrence of bright exozodiacal disks around nearby main-sequence stars. We also report on the first H-band interferometric observations of the exozodiacal disk around Vega which have been obtained with IOTA/IONIC, and discuss the implications on the disk properties.

Evolution of protoplanetary disks with dynamo magnetic fields

NASA Technical Reports Server (NTRS)

Reyes-Ruiz, M.; Stepinski, Tomasz F.

1994-01-01

The notion that planetary systems are formed within dusty disks is certainly not a new one; the modern planet formation paradigm is based on suggestions made by Laplace more than 200 years ago. More recently, the foundations of accretion disk theory where initially developed with this problem in mind, and in the last decade astronomical observations have indicated that many young stars have disks around them. Such observations support the generally accepted model of a viscous Keplerian accretion disk for the early stages of planetary system formation. However, one of the major uncertainties remaining in understanding the dynamical evolution of protoplanetary disks is the mechanism responsible for the transport of angular momentum and subsequent mass accretion through the disk. This is a fundamental piece of the planetary system genesis problem since such mechanisms will determine the environment in which planets are formed. Among the mechanisms suggested for this effect is the Maxwell stress associated with a magnetic field treading the disk. Due to the low internal temperatures through most of the disk, even the question of the existence of a magnetic field must be seriously studied before including magnetic effects in the disk dynamics. On the other hand, from meteoritic evidence it is believed that magnetic fields of significant magnitude existed in the earliest, PP-disk-like, stage of our own solar system's evolution. Hence, the hypothesis that PP disks are magnetized is not made solely on the basis of theory. Previous studies have addressed the problem of the existence of a magnetic field in a steady-state disk and have found that the low conductivity results in a fast diffusion of the magnetic field on timescales much shorter than the evolutionary timescale. Hence the only way for a magnetic field to exist in PP disks for a considerable portion of their lifetimes is for it to be continuously regenerated. In the present work, we present results on the self

NASA Lewis Helps Develop Advanced Saw Blades for the Lumber Industry

NASA Technical Reports Server (NTRS)

1998-01-01

NASA Lewis Research Center's Structures and Material Divisions are centers of excellence in high-temperature alloys for aerospace applications such as advanced aircraft and rocket engines. Lewis' expertise in these fields was enlisted in the development of a new generation of circular sawblades for the lumber industry to use in cutting logs into boards. The U.S. Department of Agriculture's (USDA) Forest Products Laboratory and their supplier had succeeded in developing a thinner sawblade by using a nickel-based alloy, but they needed to reduce excessive warping due to residual stresses. They requested assistance from Lewis' experts, who successfully eliminated the residual stress problem and increased blade strength by over 12 percent. They achieved this by developing an innovative heat treatment based on their knowledge of nickel-based superalloys used in aeropropulsion applications.

Redox polymer electrodes for advanced batteries

DOEpatents

Gregg, Brian A.; Taylor, A. Michael

1998-01-01

Advanced batteries having a long cycle lifetime are provided. More specifically, the present invention relates to electrodes made from redox polymer films and batteries in which either the positive electrode, the negative electrode, or both, comprise redox polymers. Suitable redox polymers for this purpose include pyridyl or polypyridyl complexes of transition metals like iron, ruthenium, osmium, chromium, tungsten and nickel; porphyrins (either free base or metallo derivatives); phthalocyanines (either free base or metallo derivatives); metal complexes of cyclams, such as tetraazacyclotetradecane; metal complexes of crown ethers and metallocenes such as ferrocene, cobaltocene and ruthenocene.

The CDF Run II disk inventory manager

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paul Hubbard and Stephan Lammel

2001-11-02

The Collider Detector at Fermilab (CDF) experiment records and analyses proton-antiproton interactions at a center-of-mass energy of 2 TeV. Run II of the Fermilab Tevatron started in April of this year. The duration of the run is expected to be over two years. One of the main data handling strategies of CDF for Run II is to hide all tape access from the user and to facilitate sharing of data and thus disk space. A disk inventory manager was designed and developed over the past years to keep track of the data on disk, to coordinate user access to themore » data, and to stage data back from tape to disk as needed. The CDF Run II disk inventory manager consists of a server process, a user and administrator command line interfaces, and a library with the routines of the client API. Data are managed in filesets which are groups of one or more files. The system keeps track of user access to the filesets and attempts to keep frequently accessed data on disk. Data that are not on disk are automatically staged back from tape as needed. For CDF the main staging method is based on the mt-tools package as tapes are written according to the ANSI standard.« less

The effect of alloying on gamma and gamma prime in nickel-base superalloys

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.; Wallace, J. F.

1972-01-01

An investigation was conducted to determine the compositional limits of gamma and gamma prime phases in nickel-base superalloys. Fifty-one nickel-base alloys were melted under vacuum and heat treated for 4 hours at 1190 C followed by 1008 hours at 850 C. The alloys had the following composition ranges: A1 4.0 to 13 atomic percent, Cr 6.5 to 20.5 percent, Ti 0.25 to 4.75 percent, Mo 0.0 to 6.0 percent, and W 0.0 to 4.0 percent. The residues from the ammonium sulfate electrolytic extraction for the two-phase alloys were analyzed chemically and by X-ray diffraction. The results of the investigation were used to assemble a mathematical model of the gamma-gamma prime region of the Ni-Al-Cr-Ti-Mo-W system. A computer program was written to analyze the model of the phase diagram. Some of these results are also presented graphically. The resulting model is capable of satisfactorily predicting the compositions of conjugate gamma-gamma prime phases in the alloys investigated and twelve of fifteen commercial superalloys studied.

Disk Detective Follow-Up Program

NASA Astrophysics Data System (ADS)

Kuchner, Marc

As new data on exoplanets and young stellar associations arrive, we will want to know: which of these planetary systems and young stars have circumstellar disks? The vast allsky database of 747 million infrared sources from NASA's Wide-field Infrared Survey Explorer (WISE) mission can supply answers. WISE is a discovery tool intended to find targets for JWST, sensitive enough to detect circumstellar disks as far away as 3000 light years. The vast WISE archive already serves us as a roadmap to guide exoplanet searches, provide information on disk properties as new planets are discovered, and teach us about the many hotly debated connections between disks and exoplanets. However, because of the challenges of utilizing the WISE data, this resource remains underutilized as a tool for disk and planet hunters. Attempts to use WISE to find disks around Kepler planet hosts were nearly scuttled by confusion noise. Moreover, since most of the stars with WISE infrared excesses were too red for Hipparcos photometry, most of the disks sensed by WISE remain obscure, orbiting stars unlisted in the usual star databases. To remedy the confusion noise problem, we have begun a massive project to scour the WISE data archive for new circumstellar disks. The Disk Detective project (Kuchner et al. 2016) engages layperson volunteers to examine images from WISE, NASA's Two Micron All-Sky Survey (2MASS) and optical surveys to search for new circumstellar disk candidates via the citizen science website DiskDetective.org. Fueled by the efforts of > 28,000 citizen scientists, Disk Detective is the largest survey for debris disks with WISE. It has already uncovered 4000 disk candidates worthy of follow-up. However, most host stars of the new Disk Detective disk candidates have no known spectral type or distance, especially those with red colors: K and M stars and Young Stellar Objects. Others require further observations to check for false positives. The Disk Detective project is supported by

Optical Disks.

ERIC Educational Resources Information Center

Gale, John C.; And Others

1985-01-01

This four-article section focuses on information storage capacity of the optical disk covering the information workstation (uses microcomputer, optical disk, compact disc to provide reference information, information content, work product support); use of laser videodisc technology for dissemination of agricultural information; encoding databases…

Separation and Precipitation of Nickel from Acidic Sulfate Leaching Solution of Molybdenum-Nickel Black Shale by Potassium Nickel Sulfate Hexahydrate Crystallization

NASA Astrophysics Data System (ADS)

Deng, Zhigan; Wei, Chang; Fan, Gang; Li, Xingbin; Li, Minting; Li, Cunxiong

2018-02-01

Nickel was separated and precipitated with potassium nickel sulfate hexahydrate [K2Ni(SO4)2·6H2O] from acidic sulfate solution, a leach solution from molybdenum-nickel black shale. The effects of the potassium sulfate (K2SO4) concentration, crystallization temperature, solution pH, and crystallization time on nickel(II) recovery and iron(III) precipitation were investigated, revealing that nickel and iron were separated effectively. The optimum parameters were K2SO4 concentration of 200 g/L, crystallization temperature of 10°C, solution pH of 0.5, and crystallization time of 24 h. Under these conditions, 97.6% nickel(II) was recovered as K2Ni(SO4)2·6H2O crystals while only 2.0% of the total iron(III) was precipitated. After recrystallization, 98.4% pure K2Ni(SO4)2·6H2O crystals were obtained in the solids. The mother liquor was purified by hydrolysis-precipitation followed by cooling, and more than 99.0% K2SO4 could be crystallized. A process flowsheet was developed to separate iron(III) and nickel(II) from acidic-sulfate solution.

Synthesis, crystal structure, fluorescence and electrochemical studies of a new tridentate Schiff base ligand and its nickel(II) and palladium(II) complexes

NASA Astrophysics Data System (ADS)

Shafaatian, Bita; Soleymanpour, Ahmad; Kholghi Oskouei, Nasim; Notash, Behrouz; Rezvani, Seyyed Ahmad

2014-07-01

A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1 M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1 M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s-1 scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, 1H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction.

Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

ME Petrichek

2005-12-16

Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel basemore » alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should

Laser Optical Disk: The Coming Revolution in On-Line Storage.

ERIC Educational Resources Information Center

Fujitani, Larry

1984-01-01

Review of similarities and differences between magnetic-based and optical disk drives includes a discussion of the electronics necessary for their operation; describes benefits, possible applications, and future trends in development of laser-based drives; and lists manufacturers of laser optical disk drives. (MBR)

Nickel allergy in a Danish population 25 years after the first nickel regulation.

PubMed

Ahlström, Malin G; Menné, Torkil; Thyssen, Jacob P; Johansen, Jeanne D

2017-06-01

Nickel in metallic items has been regulated in Denmark since 1990; however, 10% of young Danish women are still sensitized to nickel. There is a need for continuous surveillance of the effect of regulation. To identify current self-reported metallic exposures leading to dermatitis in nickel-allergic patients, and the minimum contact time needed for dermatitis to occur. A questionnaire was sent to all patients who reacted positively to nickel sulfate 5% pet. within the last 5 years at the Department of Dermatology and Allergy, Gentofte Hospital. The response rate was 63.2%. Earrings were the foremost cause of dermatitis after the EU Nickel Directive had been implemented, followed by other jewellery, buttons on clothing, belt buckles, and wrist watches. Dermatitis reactions within 10 min of contact were reported by 21.4% of patients, and dermatitis reactions within 30 min of contact were reported by 30.7% of patients. Nickel exposures that led to the implementation of a nickel regulation seem to persist. The durations of contact with metallic items to fall under the current REACH regulation of nickel correspond well with the results of this study. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Status of nickel/zinc and nickel/iron battery technology for electric vehicle applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, N.P.; Christianson, C.C.; Elliott, R.C.

1980-01-01

Significant progress in nickel/zinc and nickel/iron technology has been made towards achieving the battery technical performance goals necessary for widespread use of these battery systems in electric vehicle applications. This progress is reviewed. Nickel/zinc module test data have shown a specific energy of nearly 70 Whr/kg and a specific power of 130 W/kg. However, cycle life improvements are still needed (presently demonstrated capability of 120 cycles) and are expected to be demonstrated during 1980. Nickel/iron modules have demonstrated a specific energy of nearly 50 Wh/kg and a specific power of 100 W/kg. Indications are that improved performance in these areasmore » can be shown during 1980. Nickel/iron modules cycle lives of 300 have been achieved during early 1980 and testing continues. Energy efficiency has been improved from less than 50% to over 65%. Cost reduction (both initial and operating) continues to receive major emphasis at developers of both nickel/zinc and nickel/iron batteries in order to achieve the lowest possible life cycle cost to the battery user.« less

Investigation of selected disk systems

NASA Technical Reports Server (NTRS)

1976-01-01

The large disk systems offered by IBM, UNIVAC, Digital Equipment Corporation, and Data General were examined. In particular, these disk systems were analyzed in terms of how well available operating systems take advantage of the respective disk controller's transfer rates, and to what degree all available data for optimizing disk usage is effectively employed. In the course of this analysis, generic functions and components of disk systems were defined and the capabilities of the surveyed disk system were investigated.

Young stars in ɛ Chamaleontis and their disks: disk evolution in sparse associations

NASA Astrophysics Data System (ADS)

Fang, M.; van Boekel, R.; Bouwman, J.; Henning, Th.; Lawson, W. A.; Sicilia-Aguilar, A.

2013-01-01

ɛ Cha members with 10 μm features detected in their IRS spectra. We combine the dust properties derived in the ɛ Cha sample with those found using identical or similar methods in the MBM 12, Coronet, η Cha associations, and in the cores-to-disks legacy program. We find that disks around low-mass young stars show a negative radial gradient in the mass-averaged grain size and mass fraction of crystalline silicates. A positive correlation exists between the mass-averaged grain sizes of amorphous silicates and the accretion rates if the latter is above ~10-9 M⊙ yr-1, possibly indicating that those disks are sufficiently turbulent to prevent grains of several microns in size to sink into the disk interior. Based on observations performed at ESO's La Silla-Paranal observatory under programme 076.C-0470.

ADVANCED MANUFACTURING TEAM

NASA Image and Video Library

2016-03-17

KEN COOPER, TEAM LEAD OF MSFC’S ADVANCED MANUFACTURING TEAM, WITH NICKEL ALLOY 718 PARTS FABRICATED USING THE M1 SELECTIVE LASER MELTING SYSTEM. THE M1 MACHINE IS DEDICATED TO BUILDING QUALIFICATION SAMPLES AND HARDWARE DEMONSTRATORS FOR THE RS25 ENGINE PROJECT.

Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk around PDS 70: Observations of the Disk

NASA Technical Reports Server (NTRS)

Hashimoto, J.; Hayashi, M.; Iye, M.; Kandori, R.; Kusakabe,N.; Morino, J.-I.; Suto, H.; Suzuki, R.; Tamura, M.; Serabyn, G.;

Fiber laser welding of nickel based superalloy Inconel 625

NASA Astrophysics Data System (ADS)

Janicki, Damian M.

2013-01-01

The paper describes the application of single mode high power fiber laser (HPFL) for the welding of nickel based superalloy Inconel 625. Butt joints of Inconel 625 sheets 0,8 mm thick were laser welded without an additional material. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The quality and mechanical properties of the joints were determined by means of tensile and bending tests, and micro hardness tests, and also metallographic examinations. The results showed that a proper selection of laser welding parameters provides non-porous, fully-penetrated welds with the aspect ratio up to 2.0. The minimum heat input required to achieve full penetration butt welded joints with no defect was found to be 6 J/mm. The yield strength and ultimate tensile strength of the joints are essentially equivalent to that for the base material.

Lightweight Electrode For Nickel/Hydrogen Cell

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1994-01-01

Improved substrate for nickel electrode increases specific energy of nickel/hydrogen cell. Consists of 50 percent by weight nickel fiber, 35 percent nickel powder, and 15 percent cobalt powder. Porosity and thickness of nickel electrodes affect specific energy, initial performance, and cycle life of cell. Substrate easily manufactured with much larger porosities than those of heavy-sintered state-of-art nickel substrate.

Identification of transitional disks in Chamaeleon with Herschel

NASA Astrophysics Data System (ADS)

Ribas, Á.; Merín, B.; Bouy, H.; Alves de Oliveira, C.; Ardila, D. R.; Puga, E.; Kóspál, Á.; Spezzi, L.; Cox, N. L. J.; Prusti, T.; Pilbratt, G. L.; André, Ph.; Matrà, L.; Vavrek, R.

2013-04-01

Context. Transitional disks are circumstellar disks with inner holes that in some cases are produced by planets and/or substellar companions in these systems. For this reason, these disks are extremely important for the study of planetary system formation. Aims: The Herschel Space Observatory provides an unique opportunity for studying the outer regions of protoplanetary disks. In this work we update previous knowledge on the transitional disks in the Chamaeleon I and II regions with data from the Herschel Gould Belt Survey. Methods: We propose a new method for transitional disk classification based on the WISE 12 μm - PACS 70 μm color, together with inspection of the Herschel images. We applied this method to the population of Class II sources in the Chamaeleon region and studied the spectral energy distributions of the transitional disks in the sample. We also built the median spectral energy distribution of Class II objects in these regions for comparison with transitional disks. Results: The proposed method allows a clear separation of the known transitional disks from the Class II sources. We find six transitional disks, all previously known, and identify five objects previously thought to be transitional as possibly non-transitional. We find higher fluxes at the PACS wavelengths in the sample of transitional disks than those of Class II objects. Conclusions: We show the Herschel 70 μm band to be a robust and efficient tool for transitional disk identification. The sensitivity and spatial resolution of Herschel reveals a significant contamination level among the previously identified transitional disk candidates for the two regions, which calls for a revision of previous samples of transitional disks in other regions. The systematic excess found at the PACS bands could be either a result of the mechanism that produces the transitional phase, or an indication of different evolutionary paths for transitional disks and Class II sources. Herschel is an ESA

Progress in the Development of Lightweight Nickel Electrode for Nickel-Hydrogen Cell

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1999-01-01

Development of a high specific energy battery is one of the objectives of the lightweight nickel-hydrogen (Ni-H2) program at the NASA Glenn Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a lighter weight electrode for the nickel-hydrogen cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active material. Initial tests include activation and capacity measurements at five different discharge levels, C/2, 1.0 C, 1.37 C, 2.0 C, and 2.74 C. The electrodes are life cycle tested using a half-cell configuration at 40 and 80% depths-of-discharge (DOD) in a low-Earth-orbit regime. The electrodes that pass the initial tests are life cycle-tested in a boiler plate nickel-hydrogen cell before flight weight design are built and tested.

Observability of characteristic binary-induced structures in circumbinary disks

NASA Astrophysics Data System (ADS)

Avramenko, R.; Wolf, S.; Illenseer, T. F.

2017-07-01

Context. A substantial fraction of protoplanetary disks form around stellar binaries. The binary system generates a time-dependent non-axisymmetric gravitational potential, inducing strong tidal forces on the circumbinary disk. This leads to a change in basic physical properties of the circumbinary disk, which should in turn result in unique structures that are potentially observable with the current generation of instruments. Aims: The goal of this study is to identify these characteristic structures, constrain the physical conditions that cause them, and evaluate the feasibility of observing them in circumbinary disks. Methods: To achieve this, first we perform 2D hydrodynamic simulations. The resulting density distributions are post-processed with a 3D radiative transfer code to generate re-emission and scattered light maps. Based on these distributions, we study the influence of various parameters, such as the mass of the stellar components, mass of the disk, and binary separation on observable features in circumbinary disks. Results: We find that the Atacama Large (sub-)Millimetre Array (ALMA) as well as the European Extremely Large Telescope (E-ELT) are capable of tracing asymmetries in the inner region of circumbinary disks, which are affected most by the binary-disk interaction. Observations at submillimetre/millimetre wavelengths allow the detection of the density waves at the inner rim of the disk and inner cavity. With the E-ELT one can partially resolve the innermost parts of the disk in the infrared wavelength range, including the disk's rim, accretion arms, and potentially the expected circumstellar disks around each of the binary components.

Water vapor distribution in protoplanetary disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Fujun; Bergin, Edwin A., E-mail: fdu@umich.edu

Water vapor has been detected in protoplanetary disks. In this work, we model the distribution of water vapor in protoplanetary disks with a thermo-chemical code. For a set of parameterized disk models, we calculate the distribution of dust temperature and radiation field of the disk with a Monte Carlo method, and then solve the gas temperature distribution and chemical composition. The radiative transfer includes detailed treatment of scattering by atomic hydrogen and absorption by water of Lyα photons, since the Lyα line dominates the UV spectrum of accreting young stars. In a fiducial model, we find that warm water vapormore » with temperature around 300 K is mainly distributed in a small and well-confined region in the inner disk. The inner boundary of the warm water region is where the shielding of UV field due to dust and water itself become significant. The outer boundary is where the dust temperature drops below the water condensation temperature. A more luminous central star leads to a more extended distribution of warm water vapor, while dust growth and settling tends to reduce the amount of warm water vapor. Based on typical assumptions regarding the elemental oxygen abundance and the water chemistry, the column density of warm water vapor can be as high as 10{sup 22} cm{sup –2}. A small amount of hot water vapor with temperature higher than ∼300 K exists in a more extended region in the upper atmosphere of the disk. Cold water vapor with temperature lower than 100 K is distributed over the entire disk, produced by photodesorption of the water ice.« less

Effect of NASA advanced designs on thermal behavior of Ni-H2 cells

NASA Technical Reports Server (NTRS)

Gonzalez-Sanabria, Olga D.

1987-01-01

As part of an overall effort to advance the technology of nickel-hydrogen batteries for low Earth orbit (LEO) applications, advanced designs for individual pressure vessel (IPV) nickel-hydrogen cells have been conceived. These designs incorporate alternative methods of oxygen recombination which affect the thermal behavior of the cells. The effect of these oxygen recombination methods on the cell temperature profiles is examined.

In situ coating nickel organic complexes on free-standing nickel wire films for volumetric-energy-dense supercapacitors.

PubMed

Hong, Min; Xu, Shusheng; Yao, Lu; Zhou, Chao; Hu, Nantao; Yang, Zhi; Hu, Jing; Zhang, Liying; Zhou, Zhihua; Wei, Hao; Zhang, Yafei

2018-07-06

A self-free-standing core-sheath structured hybrid membrane electrodes based on nickel and nickel based metal-organic complexes (Ni@Ni-OC) was designed and constructed for high volumetric supercapacitors. The self-standing Ni@Ni-OC film electrode had a high volumetric specific capacity of 1225.5 C cm -3 at 0.3 A cm -3 and an excellent rate capability. Moreover, when countered with graphene-carbon nanotube (G-CNT) film electrode, the as-assembled Ni@Ni-OC//G-CNT hybrid supercapacitor device delivered an extraordinary volumetric capacitance of 85 F cm -3 at 0.5 A cm -3 and an outstanding energy density of 33.8 at 483 mW cm -3 . Furthermore, the hybrid supercapacitor showed no capacitance loss after 10 000 cycles at 2 A cm -3 , indicating its excellent cycle stability. These fascinating performances can be ascribed to its unique core-sheath structure that high capacity nano-porous nickel based metal-organic complexes (Ni-OC) in situ coated on highly conductive Ni wires. The impressive results presented here may pave the way to construct s self-standing membrane electrode for applications in high volumetric-performance energy storage.

Release of nickel and chromium ions from orthodontic wires following the use of teeth whitening mouthwashes.

PubMed

Mirhashemi, AmirHossein; Jahangiri, Sahar; Kharrazifard, MohammadJavad

2018-02-05

Corrosion resistance is an important requirement for orthodontic appliances. Nickel and chromium may be released from orthodontic wires and can cause allergic reactions and cytotoxicity when patients use various mouthwashes to whiten their teeth. Our study aimed to assess the release of nickel and chromium ions from nickel titanium (NiTi) and stainless steel (SS) orthodontic wires following the use of four common mouthwashes available on the market. This in vitro, experimental study was conducted on 120 orthodontic appliances for one maxillary quadrant including five brackets, one band and half of the required length of SS, and NiTi wires. The samples were immersed in Oral B, Oral B 3D White Luxe, Listerine, and Listerine Advance White for 1, 6, 24, and 168 h. The samples immersed in distilled water served as the control group. Atomic absorption spectroscopy served to quantify the amount of released ions. Nickel ions were released from both wires at all time-points; the highest amount was in Listerine and the lowest in Oral B mouthwashes. The remaining two solutions were in-between this range. The process of release of chromium from the SS wire was the same as that of nickel. However, the release trend in NiTi wires was not uniform. Listerine caused the highest release of ions. Listerine Advance White, Oral B 3D White Luxe, and distilled water were the same in terms of ion release. Oral B showed the lowest amount of ion release.

Disk Detective: Discovery of New Circumstellar Disk Candidates through Citizen Science

NASA Astrophysics Data System (ADS)

Kuchner, Marc J.; Silverberg, Steven M.; Bans, Alissa S.; Bhattacharjee, Shambo; Kenyon, Scott J.; Debes, John H.; Currie, Thayne; García, Luciano; Jung, Dawoon; Lintott, Chris; McElwain, Michael; Padgett, Deborah L.; Rebull, Luisa M.; Wisniewski, John P.; Nesvold, Erika; Schawinski, Kevin; Thaller, Michelle L.; Grady, Carol A.; Biggs, Joseph; Bosch, Milton; Černohous, Tadeáš; Durantini Luca, Hugo A.; Hyogo, Michiharu; Wah, Lily Lau Wan; Piipuu, Art; Piñeiro, Fernanda; Disk Detective Collaboration

2016-10-01

The Disk Detective citizen science project aims to find new stars with 22 μm excess emission from circumstellar dust using data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission. Initial cuts on the AllWISE catalog provide an input catalog of 277,686 sources. Volunteers then view images of each source online in 10 different bands to identify false positives (galaxies, interstellar matter, image artifacts, etc.). Sources that survive this online vetting are followed up with spectroscopy on the FLWO Tillinghast telescope. This approach should allow us to unleash the full potential of WISE for finding new debris disks and protoplanetary disks. We announce a first list of 37 new disk candidates discovered by the project, and we describe our vetting and follow-up process. One of these systems appears to contain the first debris disk discovered around a star with a white dwarf companion: HD 74389. We also report four newly discovered classical Be stars (HD 6612, HD 7406, HD 164137, and HD 218546) and a new detection of 22 μm excess around the previously known debris disk host star HD 22128.