SEARCH · Search NASA

Results for “METALS - INCONEL”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23

All sources NASA NTRS DOE OSTI

NASA NTRS1988

Heavy metal toxicity as a kill mechanism in impact caused mass extinctions

Heavy metals that are known to be toxic exist in carbonaceous chrondrites at abundances considerably in excess to that of the terrestrial crust. An impactor of relatively undifferentiated cosmic matter would inject into the terrestrial environment large quantities of toxic elements. The abundances of toxic metals found in the Allende CV carbonaceous chondrite and the ratio of meteoritic abundance to crustal abundance are: Cr, 3630 PPM, 30X; Co, 662 PPM, 23X; ni, 13300 PPm, 134X; se, 8.2 PPM, 164X; Os, 0.828 PPM, 166X. The resulting areal density for global dispersal of impactor derived heavy metals and their dilution with terrestrial ejecta are important factors in the determination of the significance of impactor heavy metal toxicity as a kill mechanism in impact caused mass extinctions. A 10 km-diameter asteroid having a density of 3 gram per cu cm would yield a global areal density of impact dispersed chondritic material of 3 kg per square meter. The present areal density of living matter on the terrestrial land surface is 1 kg per square meter. Dilution of impactor material with terrestrial ejecta is determined by energetics, with the mass of ejecta estimated to be in the range of 10 to 100 times that of the mass of the impactor. Because a pelagic impact would be the most likely case, the result would be a heavy metal rainout.

Wdowiak, T. J.↗

NASA NTRS1988

Metal with anomalously low Ni and Ge concentrations in the Allan Hills A77081 winonaite

The Ge content of metal in the Allan Hills A77081 winonaite was determined by high-sensitivity electron microprobe analysis. By optimizing analytical conditions for Ge determination, a detection limit of about 75 ppm could be achieved. In A77081 some small kamacite grains contain less Ni and Ge and more Co than coarse-grained metal. These small grains are always associated with sulfide, raising the possibility that anomalous metal is related to eutectic melting. However, when published partition coefficients for Ni and Ge in the Fe-Ni-S system are used to model fractionation of these elements during eutectic melting, one finds that secondary metal should be enriched in Ni and depleted in Ge. Thus, the positive Ni-Ge correlation found in this study is the opposite of the expected trend. No explanation for this discrepancy has yet been found. Nonetheless, the existence of anomalous metal is an indication that A77081, and probably other winonaites as well, have undergone some fractionation. This supports the notion that the high-temperature history of winonaites is related to the formation of IAB iron meteorites, whose silicate inclusions are very similar to winonaites.

Kracher, Alfred↗

NASA NTRS1989

Process for making a noble metal on tin oxide catalyst

A quantity of reagent grade tin metal or compound, chloride-free, and high-surface-area silica spheres are placed in deionized water, followed by deaerating the mixture by boiling and adding an oxidizing agent, such as nitric acid. The nitric acid oxidizes the tin to metastannic acid which coats the spheres because the acid is absorbed on the substrate. The metastannic acid becomes tin oxide upon drying and calcining. The tin-oxide coated silica spheres are then placed in water and boiled. A chloride-free precious metal compound in aqueous solution is then added to the mixture containing the spheres, and the precious metal compound is reduced to a precious metal by use of a suitable reducing agent such as formic acid. Very beneficial results were obtained using the precious metal compound tetraammine platinum(II) hydroxide.

Upchurch, Billy T.↗

NASA NTRS1990

Seamless metal-clad fiber-reinforced organic matrix composite structures and process for their manufacture

A metallic outer sleeve is provided which is capable of enveloping a hollow metallic inner member having continuous reinforcing fibers attached to the distal end thereof. The inner member is then introduced into outer sleeve until inner member is completely enveloped by outer sleeve. A liquid matrix member is then injected into space between inner member and outer sleeve. A pressurized heat transfer medium is flowed through the inside of inner member, thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. The novelty of this invention resides in the development of a efficient method of producing seamless metal clad fiber reinforced organic matrix composite structures.

Bluck, Raymond M.↗

NASA NTRS1989

The binding energies of one and two water molecules to the first transition-row metal positive ions

The bonding of water to the transition metal positive ions is electrostatic in origin. The electrostatic bonding is enhanced by a variety of mechanisms: mixing in 4p character, 4s-3d hybridization, and 4s promotion into the compact 3d orbital. The importance of these effects varies between the different metal ions due to changes in the separation of the metal ion atomic states. Furthermore, the change in the metal-water repulsion when a second water is added also changes the relative importance of the different metal asymptotes. The second water binding energy varies from being 11 kcal/mol smaller than the first for Mn(+) to 3 kcal/mol larger for V(+) and Fe(+).

Rosi, Marzio↗

NASA NTRS1990

Metal silicate mixtures - Spectral properties and applications to asteroid taxonomy

The reflectance spectra of combinations of olivine, orthopyroxene, and iron meteorite metal are experimentally studied, and the obtained variations in spectral properties are used to constrain the physical and chemical properties of the assemblages. The presence of metal most noticeably affects band area ratios, peak-to-peak and peak-to-minimum reflectance ratios, and band widths. Band width and band areas are useful for determining metal abundance in olivine and metal and orthopyroxene and metal assemblages, respectively. Mafic silicate grain size variations are best determined using band depth criteria. Band centers are most useful for determining mafic silicate composition. An application of these parameters to the S-class asteroid Flora is presented.

Cloutis, Edward A.↗

NASA NTRS1990

Critical behavior in the hydrogen insulator-metal transition

The vibrational Raman spectrum of solid hydrogen has been measured from 77 to 295 K in the vicinity of the recently observed insulator-metal transition and low-temperature phase transition at 150 gigapascals. The measurements provide evidence for a critical point in the pressure-temperature phase boundary of the low-temperature transition. The result suggests that below the critical temperature the insulator-metal transition changes from continuous to discontinuous, consistent with the general criteria originally proposed by Mott (1949) for metallization by band-gap closure. The effect of temperature on hydrogen metallization closely resembles that of the lower-pressure insulator-metal transitions in doped V2O3 alloys.

Hemley, R. J.↗

NASA NTRS1990

Synthesis and structures of metal chalcogenide precursors

The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

Hepp, Aloysius F.↗

NASA NTRS1991

Design issues for propulsion systems using metallized propellants

Metallized propellants are liquid propellants that contain metal particles. These particles are suspended in a gelled fuel or oxidizer. Aluminum is used as the metal additive. The addition of metal to conventional propellants can increase their specific impulse and their density over conventional propellants, and consequently, the payload delivered on Mars and lunar transportation vehicles, Earth-to-Orbit vehicles and upper stages for robotic planetary missions. Gelled fuels also provide increased safety during accidental propellant leakage or spills. To take full advantage of these potential performance increases, there are changes that must be made to the vehicle design. The differences are discussed between metallized propellant and traditional liquid propellants and their effect on the propulsion system design. These differences include the propellant density, mixture ratio, engine performance, and propellant rheology. Missions related to the Space Exploration Initiative are considered as design examples to illustrate these issues.

Palaszewski, Bryan↗

NASA NTRS1991

Alternate cathodes for sodium-metal chloride batteries

Various metal chlorides were tested as possible cathode materials for sodium-metal batteries (in addition to Fe and Ni chlorides, which have been already developed to a stage of commercialization), using an electrochemical cell consisting of a pyrex tube, heated to 250 C, with the metal wire as working electrode, concentric Ni foil as counterelectrode, and high-purity Al as reference electrode. In particular, the aim of this study was to identify metal chlorides insoluble even in neutral melts, possible at the interface during overcharge, in order to eliminate the failure mode of the cell through a cationic exchange of the dissolved metal ions with sodium beta-double-prime alumina solid electrolyte. Results indicate that Mo and Co are likely alternatives to FeCl2 and NiCl2 cathodes in sodium batteries. The open circuit voltages of Na/CoCl(x) and Na/MoCl(x) cells at 250 C would be 2.55 V and 2.64 V, respectively.

Ratnakumar, B. V.↗

NASA NTRS1990

Fundamental considerations in adhesion, friction and wear for ceramic-metal contacts

Fundamental studies of friction, wear and adhesion of ceramics in contact with metals are evaluated. It is shown that friction and adhesion are strongly dependent on the ductility of the metals. The surface energy, friction, adhesion and hardness of a metal are related to its Young's modulus and shear modulus, which have a marked dependence on the electron configuration of the metal. Generally, the greater the sheer modulus, the less metal transfer there is to the ceramic.

Miyoshi, Kazuhisa↗

NASA NTRS1991

Fabrication of cast particle-reinforced metals via pressure infiltration

A new casting process for fabrication of particle-reinforced metals is presented whereby a composite of particulate reinforcing phase in metal is first produced by pressure infiltration. This composite is then diluted in additional molten metal to obtain the desired reinforcement volume fraction and metal composition. This process produces a pore-free as-cast particulate metal-matrix composite. This process is demonstrated for fabrication of magnesium-matrix composites containing SiC reinforcements of average diameter 30, 10 and 3 microns. It is compared with the compocasting process, which was investigated as well for similar SiC particles in Mg-10 wt pct Al, and resulted in unacceptable levels of porosity in the as-cast composite.

Klier, E. M.↗

NASA NTRS1991

Design issues for propulsion systems using metallized propellants

Palaszewski, Bryan↗

NASA NTRS1992

The evolution of high-metallicity horizontal-branch stars and the origin of the ultraviolet light in elliptical galaxies

Evolutionary calculations of high-metallicity horizontal-branch stars show that for the relevant masses and helium abundances, post-HB evolution in the HR diagram does not proceed toward and along the AGB, but rather toward a 'slow blue phase' in the vicinity of the helium-burning main sequence, following the extinction of the hydrogen shell energy source. For solar and twice solar metallicity, the blue phase begins during the helium shell-burning phase (in agreement with the work of Brocato and Castellani and Tornambe); for 3 times solar metallicity, it begins earlier, during the helium core-burning phase. This behavior differs from what takes place at lower metallicities. The implications for high-metallicity old stellar populations in the Galactic bulge and for the integrated colors of elliptical galaxies are discussed.

Horch, E.↗

NASA NTRS1993

Process for bonding elastomers to metals

A process for bonding elastomeric material to a metal part includes coating a heat curable adhesive on the surfaces of the metal part to be bonded. The metal part is placed in a mold, a bottom plate and an upper transfer pot of a transfer molding machine is preheated to a predetermined cure temperature. A predetermined quantity of uncured elastomeric material is loaded into the transfer pot. The mold containing the adhesive coated metal part is clamped to the bottom plate, and almost contemporaneously, the uncured elastomeric material is pressed into the mold while maintaining heat and pressure in the mold for a time sufficient to vulcanize and thereby cure the elastomeric material simultaneously with the adhesive, whereby contacting surfaces of the metal part are strongly bonded to the vulcanized elastomeric material.

Dickerson, George E.↗

NASA NTRS1993

Star trapping and metallicity enrichment in quasars and active galactic nuclei

Recent observational evidence suggests that the metallicity in quasars within a wide range of redshifts, in particular in gas flowing out of the nuclear regions, may be approximately redshift-independent and comparable with or larger than solar. It is plausible that the nuclear metallicity can be internally generated and maintained at approximately time-stationary values in quasars. We identify and estimate efficiency of a mechanism for rapid metallicity enrichment of quasar nuclear gas (in general, in active galactic nuclei) based on star-gas interactions and equivalent to an unusual mode of massive star formation. The mechanism involves capture of low-mass stars from the host galaxy's nucleus by the assemblages of clouds or by accretion disks orbiting the central massive objects (e.g., black holes). Trapping of stars within gaseous disks/clouds occurs through resonant density and bending wave excitation, as well as by hydrodynamical drag. The time scale for trapping stars with total mass equal to that of disk fragment/cloud is of order Hubble time and is remarkably model-independent. Our results show that the described mechanism can produce features suggested by observations, for example, the (super) solar gas metallicity in the nucleus. Thus the observed metallicities in high-redshift quasars do not necessarily imply that global star formation and efficient chemical changes have occurred in their host galaxies at very early cosmological epochs.

Artymowicz, Pawel↗

NASA NTRS1994

Ignition and combustion of bulk metals in a microgravity environment

Knowledge of the oxidation, ignition, and combustion of bulk metals is important for fire safety in the production, management, and utilization of liquid and gaseous oxygen for ground based and space applications. This report summarizes research under NASA support to investigate the ignition and combustion characteristics of bulk metals under varying gravity conditions. Metal ignition and combustion have not been studied previously under these conditions and the results are important not only for improved fire safety but also to increase knowledge of basic ignition and combustion mechanisms. The studies completed to date have led to the development of a clean and reproducible ignition source and diagnostic techniques for combustion measurements and have provided normal gravity combustion data on ten different pure metals. Metal specimens were ignited using a xenon short-arc lamp and measurements were made of the radiant energy flux, surface temperature history, spectroscopy of surface and gas products, and surface morphology and chemistry. Elevated gravity was provided by the University of Colorado Geotechnical Centrifuge.

Branch, Melvyn C.↗

NASA NTRS1994

Siderophile elements and metal-silicate fractionation in the solar nebula

The most important nebular fractionation affecting the siderophile elements is the metal-silicate fractionation process and its relationship to the chondrule formation process is poorly understood. Understanding these processes is important in terms of understanding the expected compositional range for planetary building blocks. In a general way the composition of chondrites can be derived from the composition of the CI chondrites by addition or subtraction of a refractory component similar to CAI's (in some cases with a Mg2SiO4 component) and by addition or subtraction of Fe metal. Thus normalization to Fe produces the least spread in the normalized abundances of most siderophile elements relative to CI abundances. Detailed bulk chemical studies of chondrules have shown that their siderophile elements have refractory-element siderophile-element signatures (for example, Ir/Ni) that are similar to the bulk meteorites, but distinct among the different chondrite groups. This data suggests that the chondrules were not supplied to the chondrule groups from a single homogeneous source, and that each chondrite group's characteristic siderophile-element signature was established before chondrule formation. These authors make a further inference that all siderophile-lithophile-element fractionation occurred before chondrule formation, but recent discoveries and observations suggest this is not true. The discovery of the metal-rich CH meteorites, the recognition of the role of aerodynamic forces in the solar nebula, and the possible role of metal-silicate segregation during the chondrule formation process suggests that metal-silicate fractionation occurred before, during and after chondrule formation.

Newsom, H. E.↗