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Results for “Surface activation”

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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Luminescence induced by dehydration of kaolin - Association with electron-spin-active centers and with surface activity for dehydration-polymerization of glycine

Experimental data concerning emission of light upon dehydration as a function of preheating and pre-gamma-irradiation are correlated with reported studies of electron-spin resonance (ESR) activity after similar pretreatments. The effect of these pretreatments on the kaolin-promoted incorporation of glycine into peptide oligomers in a wet/cold, hot/dry fluctuating environment is compared to their effect on the ESR and luminescent signals. The existence of spectroscopically active centers appears to be loosely anticorrelated with reaction yield; these yields are increased by increasing the overall energy content of the material. It is concluded that some part of the chemical yield is produced by a mechanism involving intrinsic, excited electronic states of the clay crystal lattice. These states may be derived from thermally, interfacially, and/or mechanically induced charge reorganization within interspersed energy levels in the band structure of the material.

Coyne, L.↗
NASA NTRS1985

Method for measuring surface activity of silicon nitride powder

Amorphous, alpha-, and beta-Si3N4 powders were activated by vibration ball milling in purified MeOH, and the surface activity of ground powders was determined by the temperature programmed desorption (TPD) method using NH3 gas. The concentration of active sites with a potential energy equivalent to the peak temperature in the spectrum increased was markedly by ball milling the amorphous Si3N4. The alpha- and beta-Si3N4 also had active sites produced by ball milling. The concentration of active site increased with increased ball milling time. A method for measuring surface activity of ceramic raw materials by TPD is proposed.

Kanno, Y.↗
DOE OSTI2025

Enhancing surface activity and durability in triple conducting electrode for protonic ceramic electrochemical cells

With the material system operating at lower temperatures, protonic ceramic electrochemical cells (PCECs) can offer high energy efficiency and reliable performance for both power generation and hydrogen production, making them a promising technology for reversible energy cycling. However, PCEC faces technical challenges, particularly regarding electrode activity and durability under high current density operations. To address these challenges, we introduce a nano-architecture oxygen electrode characterized by high porosity and triple conductivity, designed to enhance catalytic activity and interfacial stability through a self-assembly approach, while maintaining scalability. Electrochemical cells incorporating this advanced electrode demonstrate robust performance, achieving a peak power density of 1.50 W cm −2 at 600 °C in fuel cell mode and a current density of 5.04 A cm −2 at 1.60 V in electrolysis mode, with enhanced stability on transient operations and thermal cycles. The underlying mechanisms are closely related to the improved surface activity and mass transfer due to the dual features of the electrode structure. Additionally, the enhanced interfacial bonding between the oxygen electrode and electrolyte contributes to increased durability and thermomechanical integrity. This study underscores the critical importance of optimizing electrode microstructure to achieve a balance between surface activity and durability.

Protonic Ceramic Electrochemical Cells↗
NASA NTRS1995

Dual Active Surface Heat Flux Gage Probe

A unique plug-type heat flux gage probe was tested in the NASA Ames Research Center 2x9 turbulent flow duct facility. The probe was fabricated by welding a miniature dual active surface heat flux gage body to the end of a hollow metal cylindrical bolt containing a metal inner tube. Cooling air flows through the inner tube, impinges onto the back of the gage body and then flows out through the annulus formed between the inner tube and the hollow bolt wall. Heat flux was generated in the duct facility with a Huels arc heater. The duct had a rectangular cross section and one wall was fabricated from 2.54 centimeter thick thermal insulation rigid surface material mounted onto an aluminum plate. To measure heat flux, the probe was inserted through the plate and insulating materials with the from of the gage located flush with the hot gas-side insulation surface. Absorbed heat fluxes measured with the probe were compared with absorbed heat fluxes measured with six water-cooled reference calorimeters. These calorimeters were located in a water-cooled metal duct wall which was located across from the probe position. Correspondence of transient and steady heat fluxes measured with the reference calorimeters and heat flux gage probe was generally within a satisfactory plus or minus 10 percent. This good correspondence was achieved even though the much cooler probe caused a large surface temperature disruption of 1000K between the metal gage and the insulation. However, this temperature disruption did not seriously effect the accuracy of the heat flux measurement. A current application for dual active surface heat flux gages is for transient and steady absorbed heat flux, surface temperature and heat transfer coefficient measurements on the surface of an oxidizer turbine inlet deflector operating in a space shuttle test bed engine.

Liebert, Curt H.↗
NASA NTRS1995

Meteorite organics in planetary environments: hydrothermal release, surface activity, and microbial utilization

Up to 50% of the organics in the Murchison meteorite, possibly including some of the polymer, is released in high temperature and pressure aqueous environments, to 350 degrees C and 250 bar, that simulate submarine volcanic, hydrothermal or impact-induced conditions. Meteorite organics of prebiotic significance, such as nonanoic acid, glycine, and pyrene survive the hydrothermal conditions. The released material is surface active with surface pressures up to 19.8 x 10(-3) N m-1, and exhibits an extended surface tension isotherm which suggests a mixture of amphiphilic components. One component, nonanoic acid, is shown to form vesicles. The materials extracted under mild conditions, at 120 degrees C, are nutrients for the humic acid bacterium Pseudomonas maltophilia and efficient nutrients for the oligotroph Flavobacterium oryzihabitans, demonstrating the capability of microorganisms to metabolize extraterrestrial organics.

NASA Program Exobiology↗
NASA NTRS1988

Control of the boundary layer separation about an airfoil by active surface heating

Application of active control to separated flow on the RC(6)-08 airfoil at high angle of attack by localized surface heating is numerically simulated by integrating the compressible two-dimensional nonlinear Navier-Stokes equations solver. Active control is simulated by local modification of the temperature boundary condition over a narrow strip on the upper surface of the airfoil. Both mean and perturbed profiles are favorably altered when excited with the same natural frequency of the shear layer by moderate surface heating for both laminar and turbulent separation. The shear layer is found to be very sensitive to localized surface heating in the vicinity of the separation point. The excitation field at the surface sufficiently altered both the local as well as the global circulation to cause a significant increase in lift and reduction in drag.

Maestrello, Lucio↗
NASA NTRS1955

Effect of Surface-active Additives on Physical Properties of Slurries of Vapor-process Magnesium

The presence of 3 to 5 percent surface-active additive gave the lowest Brookfield apparent viscosity, plastic viscosity, and yield value that were obtained for slurry fuels containing approximately 50 percent vapor-process magnesium in JP-1 fuel. The slurries settled little and were easily remixed. A polyoxyethylene dodecyl alcohol was the most effective of 13 additives tested in reducing the Brookfield apparent viscosity and the yield value of the slurry. The seven most effective additives all had a hydroxyl group plus an ester or polyoxethylene group in the molecule. The densities of some of the slurries were measured.

Pinns, Murray L↗
NASA NTRS1996

SonoPanel(TM) 1-3 Piezocomposite Panels for Active Surface Control

Materials Systems Inc. has developed a cost-effective technology for producing 1-3 piezoelectric ceramic/polymer composites for use in active surface control. MSI's 103 piezocomposite SonoPanel(TM) transducers consist of an array of piezoelectric ceramic rods arranged in a compliant polymer matrix. The standard SonoPanel(TM) composite consists of 15 volume percent PZT-5H rods 1.1 mm diameter x 6.3 mm long in a matrix of soft polyurethane. Stiff face plates are then bonded to the 1-3 composite sheet for stress amplification when used as a sensor and to enhance the surface response uniformity when used as an actuator. Many variations on this composite design have been produced for specific application requirements.

Gentilman, R.↗
NASA NTRSDate not supplied

Reference Surface Activities for Crewed Mars Mission Systems and Utilization

This presentation was made at the “COSPAR Planetary Protection Knowledge Gaps for Human Missions to Mars” virtual workshop. As the workshop title implies, the presentation is intended to explain basic features of current human Mars surface mission scenarios being analyzed by NASA. The specific scenario details described is documented in HEOMD-415 “Reference Surface Activities for Crewed Mars Mission Systems and Utilization.” Other workshop presentations will expand on details related to scientific investigations that could have planetary protection impacts.

Mars↗
NASA NTRS1964

Lunar surface activities

Possible excursions for typical 35-hour lunar surface exploration, experimental and recording instruments, sample collection, and photography

PHOTOGRAPHIC RECORDING↗
NASA NTRS1988

An application of active surface heating for augmenting lift and reducing drag of an airfoil

Application of active control to separated flow on the RC(6)-08 airfoil at high angle of attack by localized surface heating is numerically simulated by integrating the compressible 2-D nonlinear Navier-Stokes equation solver. Active control is simulated by local modification of the temperature boundary condition over a narrow strip of the upper surface of the airfoil. Both mean and perturbed profiles are favorably altered when excited with the same natural frequency of the shear layer by moderate surface heating for both laminar and turbulent separation. The shear layer is found to be very sensitive to localized surface heating in the vicinity of the separation point. The excitation field at the surface sufficiently altered both the local as well as the global circulation to cause a significant increase in lift and reduction in drag.

Maestrello, Lucio↗
NASA NTRSDate not supplied

Reference Surface Activities for Crewed Mars Mission Systems and Utilization

This paper describes the current reference being used by NASA for the surface exploration portion of a human Mars mission architecture, documented in HEOMD-415. (It is important to note that no decisions have been made by NASA regarding human Mars mission objectives, durations, or architectures, and this document is intended to aid in analysis of options.) The HEOMD-415 report details constraints and considerations in planning daily activity timelines for crewed exploration on Mars. This work was done for the purpose of estimating how much time during each martian sol might be available for exploration activities, (also referred to as utilization activities in this document), after accounting for time needed for crew and equipment care. The report describes activities, on a sol-by-sol basis, for a surface exploration mission with a total duration of 30 sols on the surface. At the conclusion of this description, the total amount of time used in the activities is presented, summarized into relevant mission planning categories. In addition, the amount of time used specifically for extravehicular activities (EVAs) is gathered in a tabular form, showing the amount of time by sol and by crewmember that resulted from this analysis. As future analyses related to this surface mission are conducted, these summary results will be updated and revisions of the document will be released.

Mars↗
DOE OSTI2025

Perovskite Catalysts for Pure-Water-Fed Anion-Exchange-Membrane Electrolyzer Anodes: Co-design of Electrically Conductive Nanoparticle Cores and Active Surfaces

Anion-exchange-membrane water electrolyzers (AEMWEs) are a possible low-capital-expense, efficient, and scalable hydrogen-production technology with inexpensive hardware, earth-abundant catalysts, and pure water. However, pure-water-fed AEMWEs remain at an early stage of development and suffer from inferior performance compared with proton-exchange-membrane water electrolyzers (PEMWEs). One challenge is to develop effective non-platinum-group-metal (non-PGM) anode catalysts and electrodes in pure-water-fed AEMWEs. We show how LaNiO3-based perovskite oxides can be tuned by cosubstitution on both A- and B-sites to simultaneously maintain high metallic electrical conductivity along with a degree of surface reconstruction to expose a stable Co-based active catalyst. The optimized perovskite, Sr0.1La0.9Co0.5Ni0.5O3, yielded pure-water AEMWEs operating at 1.97 V at 2.0 A cm-2 at 70 °C with a pure-water feed, thus illustrating the utility of the catalyst design principles.

Zhai, Tingting↗
NASA NTRS1973

Friction induced surface activity of some simple organic chlorides and hydrocarbons with iron.

Sliding friction studies were conducted on an iron surface with exposure of that surface to various hydrocarbons and organic chlorides. The hydrocarbons included ethane, ethylene, ethyl chloride, methyl chloride and vinyl chloride. Auger cylindrical-mirror analysis was used to follow interactions of the hydrocarbon and organic chlorides with the iron surface. Results with vinyl chloride indicate friction-induced surface reactivity, adsorption to surface oxides, friction sensitivity to concentration and polymerization. Variation in the loads employed influence adsorption and, accordingly, friction. Unlike results with ethyl and vinyl chloride, friction-induced surface reactivity was not observed with ethane and ethylene.

Buckley, D. H.↗
NASA NTRS1973

Friction-induced surface activity of some hydrocarbons with clean and oxide-covered iron

Sliding friction studies were conducted on a clean and oxide-covered iron surface with exposure of that surface to various hydrocarbons. The hydrocarbons included ethane, ethylene ethyl chloride, methyl chloride, and vinyl chloride. Auger cylindrical mirror analysis was used to follow interactions of the hydrocarbon with the iron surface. Results with vinyl chloride indicate friction induced surface reactivity, adsorption to surface oxides, friction sensitivity to concentration and polymerization. Variation in the loads employed influence adsorption and accordingly friction. In contrast with ethyl and vinyl chloride, friction induced surface reactivity was not observed with ethane and ethylene.

Buckley, D. H.↗
NASA NTRS1988

Mapping of surface activity on the W UMa-type system VW Cephei

After multifilter photometry of the W UMa-type contact binary VW Cep (P = 6.67 hr; G5V + K0V) in 1986/87 revealed large asymmetries in the light curves believed to be caused by large, cool starspot regions on the surface of the larger stars, in Apr. 1987 it was observed with IUE to study the chromospheres and transition regions of the components. During one complete orbital cycle, three SWP and four LWP low dispersion spectra were obtained, including and then excluding the suspected active region. Phase dependent TR line emission strengths were found, most notably C IV, which is 50 percent stronger when the spot region is most visible. The results could be important because VW Cep represents an extreme case for studying stellar dynamo theory and observations can play a crucial role in the unterstanding of magnetic fields and activity cycles in rapidly rotating solar-like stars.

Bradstreet, David H.↗