Search NASA⌕ Search

SEARCH · Search NASA

Results for “metallic hydrogen”

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.

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

At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Miniaturized Metal (Metal Alloy)/PdO(x)/SiC Hydrogen and Hydrocarbon Gas Sensors

A miniaturized Schottky diode hydrogen and hydrocarbon sensor and the method of making same is disclosed and claimed. The sensor comprises a catalytic metal layer, such as palladium, a silicon carbide substrate layer and a thin barrier layer in between the catalytic and substrate layers made of palladium oxide (PdO(x)). This highly stable device provides sensitive gas detection at temperatures ranging from at least 450 to 600 C. The barrier layer prevents reactions between the catalytic metal layer and the substrate layer. Conventional semiconductor fabrication techniques are used to fabricate the small-sided sensors. The use of a thicker palladium oxide barrier layer for other semiconductor structures such as a capacitor and transistor structures is also disclosed.

Hunter, Gary W.↗
NASA NTRS1987

Getter Capsules for Heat-Transport Systems

Metal absorbs hydrogen dissolved in heat-transfer fluids. Blockages by hydrogen gas in refrigerators, heat pipes, and other two-phase heat-transport systems eliminated by use of degassing metals or alloys called getters. Getter contained in getter capsule placed in series or in parallel with heat-transport loop. Gas-removal technique more specific and more reliable in solving problem of gas blockage than older procedures.

Seidenberg, Benjamin↗
NASA NTRS1994

Cryogenic Gellant and Fuel Formulation for Metallized Gelled Propellants: Hydrocarbons and Hydrogen with Aluminum

An experimental program to determine the viability of nanoparticulate gellant materials for gelled hydrocarbons and gelled liquid hydrogen was conducted. The gellants included alkoxides (BTMSE and BTMSH) and silica-based materials. Hexane, ethane, propane and hydrogen were gelled with the newly-formulated materials and their rheological properties were determined: shear stress versus shear rate and their attendant viscosities. Metallized hexane with aluminum particles was also rheologically characterized. The propellant and gellant formulations were selected for the very high surface area and relatively-high energy content of the gellants. These new gellants can therefore improve rocket engine specific impulse over that obtained with traditional cryogenic-fuel gellant materials silicon dioxide, frozen methane, or frozen ethane particles. Significant reductions in the total mass of the gellant were enabled in the fuels. In gelled liquid hydrogen, the total mass of gellant was reduced from 10-40 wt percent of frozen hydrocarbon particles to less that 8 wt percent with the alkoxide.

Wong, Wing↗
NASA NTRS1976

Interior models of Jupiter

Understanding the interior of Jupiter depends upon our knowledge of the thermodynamics and transport properties of hydrogen-helium mixtures at high pressures and temperatures. The current status of this knowledge is reviewed, and attention is given to the metallic-molecular hydrogen transition and the limited solubility of helium in hydrogen. Models of Jupiter are constructed which are consistent with all the observations to date, but which make various assumptions about the thermodynamics and composition of the interior. These models typically consist of a rocky core surrounded by a nearly-solar fluid mixture. In contrast to the models of Podolak and Cameron, a large enhancement of water or helium is not found to be essential. It is concluded that further progress in constructing interior models requires a better understanding of the thermodynamics of dense molecular hydrogen.

Stevenson, D. J.↗
NASA NTRS1973

The solubility of hydrogen in rhodium, ruthenium, iridium and nickel.

The temperature variation of the solubility of hydrogen in rhodium, ruthenium, iridium, and nickel in equilibrium with H2 gas at 1 atm pressure has been measured by a technique involving saturating the solvent metal with hydrogen, quenching, and analyzing in resultant solid solutions. The solubilities determined are small (atom fraction of H is in the range from 0.0005 to 0.00001, and the results are consistent with the simple quasi-regular model for dilute interstitial solid solutions. The relative partial enthalpy and excess entropy of the dissolved hydrogen atoms have been calculated from the solubility data and compared with well-known correlations between these quantities.

Mclellan, R. B.↗
NASA NTRS1993

An investigation of the effect of surface impurities on the adsorption kinetics of hydrogen chemisorbed onto iron

The goal of this program was to develop an understanding of heterogeneous kinetic processes for those molecular species which produce gaseous hydrogen degradation of the mechanical properties of metallic structural materials. Although hydrogen degradation of metallic materials is believed to result from dissolved protonic hydrogen, the heterogeneous hydrogen interface transport processes often dominate the kinetics of degradation. The initial step in the interface transport process is the dissociative chemisorption of the molecular species at the metal surface followed by hydrogen absorption into and transport through the bulk. The interaction of hydrogen with the surfaces of alpha-2(Ti3Al) titanium aluminide, gamma(TiAl) titanium aluminide, and beryllium were studied.

Shanabarger, Mickey R.↗
NASA NTRS1991

An investigation of the effect of surface impurities on the adsorption kinetics of hydrogen chemisorbed onto iron

The goal was to develop an understanding of heterogeneous kinetic processes for those molecular species which produce gaseous hydrogen degradation of the mechanical properties of metallic structural materials. Although hydrogen degradation of metallic materials is believed to result from dissolved protonic hydrogen, the heterogeneous hydrogen interface transport processes often dominate the kinetics of the degradation process. The initial step in the interface transport process is the dissociative chemisorption of the molecular species at the metal surface followed by hydrogen absorption into and transport through the bulk. Modern advanced aerospace applications often require the use of structural materials in high pressure hydrogen environments at temperatures which range from low cryogenic temperatures to very high temperatures (1300 K and greater). Materials proposed for these applications, such as the titanium aluminides, beta-titanium alloys, nickel- and cobalt-based superalloys, molybdenum-rhenium alloys, beryllium, and various beryllides, need to possess a high degree of immunity from hydrogen induced degradation of mechanical properties. In the present program, the interaction of hydrogen with the surfaces of alpha-2 (Ti3Al) titanium aluminide, gamma (TiAl) titanium aluminide, and beryllium were studied. The interaction of low pressure hydrogen with gamma titanium aluminide and beryllium was found to be relatively weak, in the sense that adsorption leads to a low surface concentration of dissociated hydrogen, i.e., the chemisorption process is reversible at room temperature (300 K) for gamma titanium aluminide and the sticking coefficient for chemisorption is extremely small for beryllium. Hydrogen was found to interact readily with alpha-2 titanium aluminide to form a stable surface hydride at 300 K. These results correlate well with other recent studies which show that the mechanical properties for alpha-2 titanium aluminide are readily degraded in hydrogen while gamma titanium aluminide exhibits less degradation and beryllium essentially no degradation. The interaction of oxygen with the surface of these materials has been studied, also, in the present program.

Shanabarger, Mickey R.↗
NASA NTRS1996

Kinetics of Hydrogen Diffusion in LaNi(sub 5-x)Sn(sub x) Alloys

Solid-state diffusion of hydrogen in metal hydride (MH) alloys is recognized as the rate determining step in the discharge of MH alloys in alkaline Ni-MH rechargeable cells. In our pursuit of new ternary solutes in LaNi(sub 5) for extended cycle lifetimes, we have observed noticeable improvement in the cycle life with small substitutions of Sn and Ge for Ni. Furthermore, these substituents also facilitate enhanced charge transfer kinetics for hydriding-dehydriding process. In this paper, we report our studies on the kinetics of hydrogen diffusion in LaNi(sub 5-x) Sn(sub x) alloys by electrochemical pulse techniques, chronoamperometry and chronocoulometry.

electrochemical cycling↗
NASA NTRSDate not supplied

Evaluation of Low-Energy Hydrogen Separation Method Using Metal-Organic Frameworks (MOFs) for Closed-Loop ECLSS Air Revitalization (CLEAR)

The State-of-the-Art (SOA) air revitalization architecture onboard the International Space Station (ISS) recovered approximately 50% of the oxygen (O 2 ) from metabolic carbon dioxide (CO 2 ) via the Sabatier process from 2011 to 2017. O 2 recovery is currently constrained by the limited availability of reactant hydrogen (H 2 ) preventing complete conversion of CO 2 to H 2 O. Increasing O 2 recovery within Closed-Loop ECLSS is essential to reducing resupply mass for long-duration manned missions; specifically focusing on water (H 2 O) which supplies H 2 for Sabatier via water electrolysis. Past ground test endeavors at Marshall Space Flight Center (MSFC) have attempted to recover H 2 from Sabatier-produced CH 4 using technologies such as carbon vapor deposition (CVD) and plasma pyrolysis. The byproducts of these technologies can act as a catalyst poison or reactor deadload to the Sabatier reactor. Hydrogen separation techniques must be utilized to maintain the Sabatier catalyst during gas recycling and must be scalable, non-energy intensive, and safe to operate in a habitation setting. Research indicated that metal-organic frameworks (MOFs) could meet these criteria and were tested for their capability to capture the various carbon-based gaseous products of CVD and plasma pyrolysis such as acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), ethane (C 2 H 6 ), and carbon monoxide (CO) which would purify the hydrogen gas stream passing through the MOF. A sub-scale adsorption column was developed by Marshall Space Flight Center to test three MOF candidates against a synthetic gas mixture comprised of process-relevant carbonous gases and hydrogen to evaluate the separation capability of the MOFs. The results of the hydrogen separation capability, isothermal desorption capability, and demonstrated cyclic reuse of the MOF are presented in this paper.

Kagen Crawford↗
NASA NTRS2005

The Fuel Cell Powered Club Car Carryall

The NASA Glenn Research Center initiated development of the Fuel Cell Powered Club Car Carryall as a way to reduce pollution in industrial settings, reduce fossil fuel consumption and reduce operating costs for transportation systems. The Club Car Carryall provides an inexpensive approach to advance the state of the art in electric vehicle technology in a practical application. The project transfers space technology to terrestrial use via non-traditional partners, and provides power system data valuable for future aeronautics and space applications. The work was done under the Hybrid Power Management (HPM) Program. The Carryall is a state of the art, dedicated, electric utility vehicle. Hydrogen powered proton exchange membrane (PEM) fuel cells are the primary power source. Ultracapacitors were used for energy storage as long life, maintenance free operation, and excellent low temperature performance is essential. Metal hydride hydrogen storage was used to store hydrogen in a safe and efficient low-pressure solid form. The report concludes that the Fuel Cell Powered Club Car Carryall can provide excellent performance, and that the implementation of fuel cells in conjunction with ultracapacitors in the power system can provide significant reliability and performance improvements.

Eichenberg, Dennis J.↗
NASA NTRS1985

Ultraviolet spectra and chromospheres of R stars

Long-wavelength IUE spectra of 13 normal R stars and two hydrogen-deficient R0 supergiants were obtained. Early R stars are noted to have line spectra and levels of flux in the ultraviolet characteristic of G5-K2 III stars, whereas late R stars were observed to have colors and line spectra similar to late K and M stars, but with greatly enhanced strength of low-lying multiplets of neutral metals. Hydrogen-deficient carbon stars show readily apparent differences from the normal early R stars, reflecting their luminosity and somewhat higher temperatures. The lines of neutral metals in these stars are weakened, while those of ionized metals are strengthened.

Eaton, J. A.↗
NASA NTRS1972

Effective thermal conductivities of four metal ceramic composite coatings in hydrogen-oxygen rocket firings

An experimental investigation was conducted to determine the effective conductivities of four plasma-arc-sprayed, metal-ceramic gradated coatings on hydrogen-oxygen thrust chambers. The effective thermal conductivities were not a function of pressure or oxidant-to-fuel ratio. The various materials that made up these composites do not seem to affect the thermal conductivity values as much as the differences in the thermal conductivities of the parent materials would lead one to expect. Contact resistance evolving from the spraying process seems to be the controlling factor. The thermal conductivities of all the composites tested fell in the range of 0.75 to 7.5 watts per meter kelvin.

Schacht, R. L.↗
NASA NTRS1988

The phase diagram of hydrogen with other elements, and applications to Jovian planet interiors

The physical properties of pure hydrogen are studied under conditions appropriate to the interiors of Jupiter and Saturn (pressure of about 10 Mbar, T of about 80,000 K), and of Uranus and Neptune (pressure of about 0.5 Mbar, T of about 5000 K). Metallization of hydrogen takes place in Jupiter and Saturn but not in Uranus and Neptune. Hydrogen will be in a strongly interacting liquid phase in the deep interiors of all of the Jovian planets. Consideration is given to cases of hydrogen mixed with cosmically abundant impurities such as helium, oxygen, and carbon. Observational results for abundances in Jovian planet atmospheres and their possible relation to processes in the deep interior and to flow measurements are discussed.

Hubbard, W. B.↗
NASA NTRS2006

Solid State NMR Studies of the Aluminum Hydride Phases

Several solid state NMR techniques including magic-angle-spinning (MAS) and multiple-quantum (MQ) MAS experiments have been used to characterize various AlH3 samples. MAS-NMR spectra for the 1H and 27Al nuclei have been obtained on a variety of AlH3 samples that include the (beta)- and (gamma)- phases as well as the most stable (alpha)-phase. While the dominant components in these NMR spectra correspond to the aluminum hydride phases, other species were found that include Al metal, molecular hydrogen (H2), as well as peaks that can be assigned to Al-O species in different configurations. The occurrence and concentration of these extraneous components are dependent upon the initial AlH3 phase composition and preparation procedures. Both the (beta)-AlH3 and (gamma)-AlH3 phases were found to generate substantial amounts of Al metal when the materials were stored at room temperature while the (alpha)-phase materials do not exhibit these changes.

phase compositions↗
NASA NTRS1976

Theoretical models of Beta Cephei stars constructed with new radiative opacities

Equilibrium models for the main-sequence and early post-main-sequence phases of evolution are constructed for stars of 10.9 and 15 solar masses with two different initial hydrogen and metals abundances. Carson's (1976) radiative opacities are used in the calculations. It is found that the models which lie off the zero-age main sequence have cooler effective temperatures than corresponding models based on other opacities and cross the observed Beta Cephei strip in the H-R diagram only during the main phase of core hydrogen burning. The stability of radial and nonradial pulsations is studied by applying linear nonadiabatic perturbations to the models. The results show that all the modes examined are stable and that the margin of stability decreases with advancing evolution. It is suggested that the closeness of the periods of the two lowest nonradial quadrupole p-modes may be responsible for the 'beat' phenomenon observed in many Beta Cephei stars, if these modes are somehow excited. Possible instability mechanisms are evaluated, particularly the ultimate ionization of CNO elements.

Stothers, R.↗
NASA NTRS1973

Helium excitation and structure of quiescent solar prominences

The theoretical and observed level populations are compared. These levels are: helium 2P3, hydrogen second, ionized helium fourth ones. The obtained results are as follows: (1) helium, hydrogen, and metals may be emitted by the same filaments; (2) bright quiescent prominence filaments have electron temperature and electron density in the line of sight near T sub e = 7000 deg, n sub e = 10 to the 12th power, alpha = 0.0001; (3) under these conditions the average effective thickness is 5 million hence quiescent prominences have a fine filamentary structure: (4) the conditions in the interfilament areas are T sub e = 20,000 to 70,000 deg, n sub e = 10 to the 10th power to 10 to the 11th power/cu cm.

Mordzhenko, N. N.↗