Search NASA⌕ Search

SEARCH · Search NASA

Results for “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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Hydrogen adsorption and diffusion, and subcritical-crack growth in high strength steels and nickel base alloys

Embrittlement, or the enhancement of crack growth by gaseous hydrogen in high strength alloys, is of primary interest in selecting alloys for various components in the space shuttle. Embrittlement is known to occur at hydrogen gas pressures ranging from fractions to several hundred atmospheres, and is most severe in the case of martensitic high strength steels. Kinetic information on subcritical crack growth in gaseous hydrogen is sparse at this time. Corroborative information on hydrogen adsorption and diffusion is inadequate to permit a clear determination of the rate controlling process and possible mechanism in hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Therefore, coordinated studies of the kinetics of crack growth, and adsorption and diffusion of hydrogen, using identical materials, have been initiated. Comparable conditions of temperature and pressure will be used in the chemical and mechanical experiments. Inconel 718 alloy and 18Ni(200) maraging steel have been selected for these studies. Results from these studies are expected to provide not only a better understanding of the gaseous hydrogen embrittlement phenomenon itself, but also fundamental information on hydrogen adsorption and diffusion, and crack growth information that can be used directly for design.

Wei, R. P.↗
NASA NTRS1973

A hydrogen energy carrier. Volume 2: Systems analysis

A systems analysis of hydrogen as an energy carrier in the United States indicated that it is feasible to use hydrogen in all energy use areas, except some types of transportation. These use areas are industrial, residential and commercial, and electric power generation. Saturation concept and conservation concept forecasts of future total energy demands were made. Projected costs of producing hydrogen from coal or from nuclear heat combined with thermochemical decomposition of water are in the range $1.00 to $1.50 per million Btu of hydrogen produced. Other methods are estimated to be more costly. The use of hydrogen as a fuel will require the development of large-scale transmission and storage systems. A pipeline system similar to the existing natural gas pipeline system appears practical, if design factors are included to avoid hydrogen environment embrittlement of pipeline metals. Conclusions from the examination of the safety, legal, environmental, economic, political and societal aspects of hydrogen fuel are that a hydrogen energy carrier system would be compatible with American values and the existing energy system.

Savage, R. L.↗
NASA NTRS1974

Testing for hydrogen environment embrittlement - Experimental variables

Hydrogen embrittlement is classified into three types: internal reversible hydrogen embrittlement, hydrogen reaction embrittlement, and hydrogen environment embrittlement. Characteristics of and materials embrittled by these types of hydrogen embrittlement are discussed. Hydrogen environment embrittlement is reviewed in detail. Factors involved in standardizing test methods for detecting the occurrence of and evaluating the severity of hydrogen environment embrittlement are considered. The effects of test technique, hydrogen pressure, gas purity, strain rate, stress concentration factor, and test temperature are discussed.

Gray, H. R.↗
NASA NTRS1976

Fluidic hydrogen detector production prototype development

A hydrogen gas sensor that can replace catalytic combustion sensors used to detect leaks in the liquid hydrogen transfer systems at Kennedy Space Center was developed. A fluidic sensor concept, based on the principle that the frequency of a fluidic oscillator is proportional to the square root of the molecular weight of its operating fluid, was utilized. To minimize sensitivity to pressure and temperature fluctuations, and to make the sensor specific for hydrogen, two oscillators are used. One oscillator operates on sample gas containing hydrogen, while the other operates on sample gas with the hydrogen converted to steam. The conversion is accomplished with a small catalytic converter. The frequency difference is taken, and the hydrogen concentration computed with a simple digital processing circuit. The output from the sensor is an analog signal proportional to hydrogen content. The sensor is shown to be accurate and insensitive to severe environmental disturbances. It is also specific for hydrogen, even with large helium concentrations in the sample gas.

Roe, G. W.↗
NASA NTRS1976

Onboard hydrogen generation for automobiles

Problems concerning the use of hydrogen as a fuel for motor vehicles are related to the storage of the hydrogen onboard a vehicle. The feasibility is investigated to use an approach based on onboard hydrogen generation as a means to avoid these storage difficulties. Two major chemical processes can be used to produce hydrogen from liquid hydrocarbons and methanol. In steam reforming, the fuel reacts with water on a catalytic surface to produce a mixture of hydrogen and carbon monoxide. In partial oxidation, the fuel reacts with air, either on a catalytic surface or in a flame front, to yield a mixture of hydrogen and carbon monoxide. There are many trade-offs in onboard hydrogen generation, both in the choice of fuels as well as in the choice of a chemical process. Attention is given to these alternatives, the results of some experimental work in this area, and the combustion of various hydrogen-rich gases in an internal combustion engine.

Houseman, J.↗
NASA NTRS1979

Dedicated nuclear facilities for electrolytic hydrogen production

An advanced technology, fully dedicated nuclear-electrolytic hydrogen production facility is presented. This plant will produce hydrogen and oxygen only and no electrical power will be generated for off-plant use. The conceptual design was based on hydrogen production to fill a pipeline at 1000 psi and a 3000 MW nuclear base, and the base-line facility nuclear-to-shaftpower and shaftpower-to-electricity subsystems, the water treatment subsystem, electricity-to-hydrogen subsystem, hydrogen compression, efficiency, and hydrogen production cost are discussed. The final conceptual design integrates a 3000 MWth high-temperature gas-cooled reactor operating at 980 C helium reactor-out temperature, direct dc electricity generation via acyclic generators, and high-current density, high-pressure electrolyzers based on the solid polymer electrolyte approach. All subsystems are close-coupled and optimally interfaced and pipeline hydrogen is produced at 1000 psi. Hydrogen costs were about half of the conventional nuclear electrolysis process.

Foh, S. E.↗
NASA NTRS1985

Measuring Hydrogen Concentrations in Metals

Commercial corrosion-measurement system adapted to electrochemical determination of hydrogen concentrations in metals. New technique based on diffusion of hydrogen through foil specimen of metal. In sample holder, hydrogen produced on one side of foil, either by corrosion reaction or by cathodic current. Hydrogen diffused through foil removed on other side by constant anode potential, which leads to oxidation of hydrogen to water. Anode current is measure of concentration of hydrogen diffusing through foil. System used to study hydrogen uptake, hydrogen elimination by baking, effect of heat treatment, and effect of electroplating on high-strength steels.

Danford, M. D.↗
NASA NTRS1985

Use of low energy hydrogen ion implants in high efficiency crystalline silicon solar cells

This program is a study of the use of low energy hydrogen ion implantation for high efficiency crystalline silicon solar cells. The first quarterly report focuses on two tasks of this program: (1) an examination of the effects of low energy hydrogen implants on surface recombination speed; and (2) an examination of the effects of hydrogen on silicon regrowth and diffusion in silicon. The first part of the project focussed on the measurement of surface properties of hydrogen implanted silicon. Low energy hydrogen ions when bombarded on the silicon surface will create structural damage at the surface, deactivate dopants and introduce recombination centers. At the same time the electrically active centers such as dangling bonds will be passivated by these hydrogen ions. Thus hydrogen is expected to alter properties such as the surface recombination velocity, dopant profiles on the emitter, etc. In this report the surface recombination velocity of a hydrogen emplanted emitter was measured.

Fonash, S. J.↗
NASA NTRS1985

Lunar regolith fines - A source of hydrogen

The theoretical evaluation of the lunar regolith fines as a primary source of hydrogen reveals that a minimum order of magnitude increase in hydrogen content is possible in beneficiated fines because both particle size and particle shape play a significant role in the relationship of volume percent of surface coating to grain size. The lunar regolith fines meet the basic requirement for beneficiation because a major portion (minimum two-thirds) of the hydrogen occurs in the less than 20-micron-size fraction, a relatively small part of the fines. Beneficiation should be accomplished by a combination of vibratory screening followed by cyclone and/or possibly electrostatic separation. Early exploitation of the lunar regolith fines for hydrogen probably will be limited to hydrogen obtained as a by-product or co-product from the mining and processing for other elements or materials because a minimum of about 13,600 tons to about 19,600 tons of 100 ppm hydrogen-bearing lunar regolith fines will have to be processed with about 3,100 tons to about 4,500 tons, respectively, of concentrate heated to supply 1 ton of hydrogen, yielding a recovery of about 74 percent to about 51 percent respectively, of the hydrogen.

Carter, J. L.↗
NASA NTRS1985

Hydrogen production from salt water by Marine blue green algae and solar radiation

Two marine bluegreen algae, Oscillatoria sp. Miami BG 7 and Synechococcus sp Miami 041511 have been selected as the result of over 10 years continuous and intensive effort of isolation, growth examination, and the screening of hydrogen photoproduction capability in this laboratory. Both strains photoproduced hydrogen for several days at high rates and a quantity of hydrogen was accumulated in a closed vessel. Overall hydrogen donor substance of the hydrogen photoproduction was found to be salt water. Using strain Miami BG 7, a two step method of hydrogen photoproduction from salt water was successfully developed and this was recycled several times over a one month period using both free cells and immobilized cells in both indoor and outdoor under natural sunlight. According to these experiments, a prototype floating hydrogen production system was designed for further development of the biosolar hydrogen production system.

Mitsui, A.↗
NASA NTRS1986

New vistas in the determination of hydrogen in aerospace engine metal alloys

The application of diffusion theory to the analysis of hydrogen desorption data has been studied. From these analyses, important information concerning hydrogen solubilities and the nature of the hydrogen distributions in the metal has been obtained. Two nickel base alloys, Rene' 41 and Waspaloy, and one ferrous alloy, 4340 steel, were studied in this work. For the nickel base alloys, it was found that the hydrogen distributions after electrolytic charging conformed closely to those which would be predicted by diffusion theory. The hydrogen distributions in electrolytically charged 4340 steel, on the other hand, were essentially uniform in nature, which would not be predicted by diffusion theory. Finally, it has been found that the hydrogen desorption is completely explained by the nature of the hydrogen distribution in the metal, and that the 'fast' hydrogen is not due to surface and subsurface hydride formation, as was originally proposed.

Danford, M. D.↗
NASA NTRS1988

Lunar hydrogen: A resource for future use at lunar bases and space activities

Hydrogen abundances were determined for grain size separates of five lunar soils and one soil breccia. The hydrogen abundance studies have provided important baseline information for engineering models undergoing study at the present time. From the studies is appears that there is sufficient hydrogen present in selected lunar materials which could be recovered to support future space activities. It is well known that hydrogen can be extracted from lunar soils by heating between 400 and 800 C. Recovery of hydrogen for regolith materials would involve heating with solar mirrors and collecting the released hydrogen. Current baseline models for the lunar base are requiring the production of 1000 metric tons of oxygen per year. From this requirement it follows that around 117 metric tons per year of hydrogen would be required for the production of water. The ability to obtain hydrogen from the lunar regolith would assist in lowering the operating costs of any lunar base.

Gibson, Everett K., Jr.↗
NASA NTRS1990

The effect of hydrogen and microstructure on the deformation and fracture behavior of a single crystal nickel-base superalloy

A study was conducted on the effects of internal hydrogen and microstructure on the deformation and fracture of a single crystal nickel-base superalloy. In particular, room temperature plane strain fracture toughness and tensile tests were performed on hydrogen-free and hydrogen charged samples of PWA 1480. The role of microstructure was incorporated by varying the levels of porosity and eutectic gamma/gamma prime through hot isostatic pressing and heat treatment. The room temperature behavior of PWA 1480 was unusual because precipitate shearing was not the primary deformation mechanism at all strains. At strains over 1 percent, dislocations were trapped in the gamma matrix and an attempt was made to relate this behavior to compositional differences between PWA 1480 and other superalloys. Another unique feature of the tensile behavior was cleavage of the eutectic gamma/gamma prime, which is believed to initiate the failure process. Fracture occurred on (111) planes and is likely a result of shear localization along these planes. Elimination of the eutectic gamma/gamma prime greatly improved the tensile ductility, but pososity had no effect on tensile properties. Large quantities of hydrogen (1.74 at. percent) were gas-phase charged into the material, but surprisingly this was not a function of the amount of porosity or eutectic gamma/gamma prime present. Desorption experiments suggest that the vast majority of hydrogen is at reversible lattice trapping sites. This large, uniform concentration of hydrogen dramatically reduced the tensile strain to failure, but only slightly affected the reduction in area. Available hydrogen embrittlement models were examined in light of these results and it was found that the hydrogen enhanced localized plasticity model can explain much of the tensile behavior. K(IC) fracture toughness tests were conducted, but it was necessary to also perform J(IC) tests to provide valid data.

Walston, William S.↗
NASA NTRS1993

Hydrogen tolerance of a Ti3Al-based alloy

The Ti-24Al-11Nb (Ti-24-11) alloy heat-treated to the fine basketweave microstructure was shown previously to be hydrogen-tolerant. In order to assess its limit of hydrogen tolerance, the tensile, creep, fracture toughness, and sustained-load crack growth behaviors of this alloy were studied as a function of hydrogen content. The mechanical test results indicated that the fine basketweave microstructure was tolerant to hydride embrittlement for hydrogen contents up to about 1500 wppm. On the other hand, hydrogen charging experiments indicated that the Ti-24-11 alloy was severely cracked and pulverized under zero load when the hydrogen content exceeded 3000 wppm. X-ray diffraction results revealed that the dichotomous behaviors might be due to the formation of face-centered cubic (fcc) delta-type hydrides at higher hydrogen contents but face-centered tetragonal (fct) gamma-type hydrides at lower hydrogen contents.

Chan, Kwai S.↗
NASA NTRS1953

Relative Importance of Various Sources of Defect-Producing Hydrogen Introduced into Steel During Application of Vitreous Coatings

When porcelain enamels or vitreous-type ceramic coatings are applied to ferrous metals, there is believed to be an evolution of hydrogen gas both during and after the firing operation. At elevated temperatures rapid evolution may result in blistering while if hydrogen becomes trapped in the steel during the rapid cooling following the firing operation gas pressures may be generated at the coating-metal interface and flakes of the coating literally blown off the metal. To determine experimentally the relative importance of the principal sources of the hydrogen causing the defects, a procedure was devised in which heavy hydrogen (deuterium) was substituted in turn for regular hydrogen in each of five possible hydrogen-producing operations in the coating process. The findings of the study were as follows: (1) the principal source of the defect-producing hydrogen was the dissolved water present in the enamel frit that was incorporated into the coating. (2) the acid pickling, the milling water, the chemically combined water in the clay, and the quenching water were all minor sources of defect-producing hydrogen under the test conditions used. Confirming experiments showed that fishscaling could be eliminated by using a water-free coating.

Moore, Dwight G↗
NASA NTRS1994

Microfabricated Hydrogen Sensor Technology for Aerospace and Commercial Applications

Leaks on the Space Shuttle while on the Launch Pad have generated interest in hydrogen leak monitoring technology. An effective leak monitoring system requires reliable hydrogen sensors, hardware, and software to monitor the sensors. The system should process the sensor outputs and provide real-time leak monitoring information to the operator. This paper discusses the progress in developing such a complete leak monitoring system. Advanced microfabricated hydrogen sensors are being fabricated at Case Western Reserve University (CWRU) and tested at NASA Lewis Research Center (LeRC) and Gencorp Aerojet (Aerojet). Changes in the hydrogen concentrations are detected using a PdAg on silicon Schottky diode structure. Sensor temperature control is achieved with a temperature sensor and heater fabricated onto the sensor chip. Results of the characterization of these sensors are presented. These sensors can detect low concentrations of hydrogen in inert environments with high sensitivity and quick response time. Aerojet is developing the hardware and software for a multipoint leak monitoring system designed to provide leak source and magnitude information in real time. The monitoring system processes data from the hydrogen sensors and presents the operator with a visual indication of the leak location and magnitude. Work has commenced on integrating the NASA LeRC-CWRU hydrogen sensors with the Aerojet designed monitoring system. Although the leak monitoring system was designed for hydrogen propulsion systems, the possible applications of this monitoring system are wide ranged. Possible commercialization of the system will also be discussed.

Hunter, Gary W.↗
NASA NTRS1994

Influence of high pressure hydrogen environment on creep deformation of Mo-Re, Haynes 188, and NARloy-Z alloys

The present study focuses on the investigation of the influence of hydrogen on the mechanical properties of three types of alloys at elevated temperatures. The reasons for the consideration of hydrogen effects are the potential use of hydrogen as a coolant in gas-cooled reactors and fuel in advanced hypersonic vehicles. The materials used in hydrogen atmosphere must not be embrittled by hydrogen at ambient temperature and should have good strength in hydrogen atmosphere at elevated temperature. The paucity of information concerning the mechanical performance in hydrogen atmosphere at elevated temperature has been a limiting factor in the selection and design of structural components for operation in hydrogen environment.

Sastry, S. M. L.↗
NASA NTRS1995

A Summary of the Slush Hydrogen Technology Program for the National Aero-Space Plane

Slush hydrogen, a mixture of solid and liquid hydrogen, offers advantages of higher density (16 percent) and higher heat capacity (18 percent) than normal boiling point hydrogen. The combination of increased density and heat capacity of slush hydrogen provided a potential to decrease the gross takeoff weight of the National Aero-Space Plane (NASP) and therefore slush hydrogen was selected as the propellant. However, no large-scale data was available on the production, transfer and tank pressure control characteristics required to use slush hydrogen as a fuel. Extensive testing has been performed at the NASA Lewis Research Center K-Site and Small Scale Hydrogen Test Facility between 1990 and the present to provide a database for the use of slush hydrogen. This paper summarizes the results of this testing.

Mcnelis, Nancy B.↗