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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Replacement of corrosion protection chromate primers and paints used in cryogenic applications on the Space Shuttle with wire arc sprayed aluminum coatings

With the advent of new environmental laws restricting volatile organic compounds and hexavalent chrome emissions, 'environmentally safe' thermal spray coatings are being developed to replace the traditional corrosion protection chromate primers. A wire arc sprayed aluminum coating is being developed for corrosion protection of low pressure liquid hydrogen carrying ducts on the Space Shuttle Main Engine. Currently, this hardware utilizes a chromate primer to provide protection against corrosion pitting and stress corrosion cracking induced by the cryogenic operating environment. The wire are sprayed aluminum coating has been found to have good potential to provide corrosion protection for flight hardware in cryogenic applications. The coating development, adhesion test, corrosion test and cryogenic flexibility test results will be presented.

Daniel, R. L.↗
NASA NTRS2007

Weathering of Thermal Control Coatings

Spacecraft radiators reject heat to their surroundings. Radiators can be deployable or mounted on the body of the spacecraft. NASA's Crew Exploration Vehicle is to use body mounted radiators. Coatings play an important role in heat rejection. The coatings provide the radiator surface with the desired optical properties of low solar absorptance and high infrared emittance. These specialized surfaces are applied to the radiator panel in a number of ways, including conventional spraying, plasma spraying, or as an applique. Not specifically designed for a weathering environment, little is known about the durability of conventional paints, coatings, and appliques upon exposure to weathering and subsequent exposure to solar wind and ultraviolet radiation exposure. In addition to maintaining their desired optical properties, the coatings must also continue to adhere to the underlying radiator panel. This is a challenge, as new composite radiator panels are being considered as replacements for the aluminum panels used previously. Various thermal control paints, coatings, and appliques were applied to aluminum and isocyanate ester composite coupons and were exposed for 30 days at the Atmospheric Exposure Site of the Kennedy Space Center s Beach Corrosion Facility for the purpose of identifying their durability to weathering. Selected coupons were subsequently exposed to simulated solar wind and vacuum ultraviolet radiation to identify the effect of a simulated space environment on the as-weathered surfaces. Optical properties and adhesion testing were used to document the durability of the paints and coatings. The purpose of this paper is to present the results of the weathering testing and to summarize the durability of several thermal control paints, coatings, and appliques to weathering and postweathering environments.

Jaworske, Donald A.↗
NASA NTRS2000

Stable metallization for diamond and other materials

An adherent and metallurgically stable metallization system for diamond is presented. The big improvement in metallurgical stability is attributed to the use of a ternary, amorphous Ti--Si--N diffusion barrier. No diffusion between the layers and no delamination of the metallization was observed after annealing the schemes at 400.degree. C. for 100 hours and at 900.degree. C. for 30 minutes. Thermal cycling experiments in air from -65 to 155.degree. C. and adhesion tests were performed. Various embodiments are disclosed.

Bachli, Andreas↗
NASA NTRS2008

Optical Properties of Thermal Control Coatings After Weathering, Simulated Ascent Heating, and Simulated Space Radiation Exposure

Spacecraft radiators reject heat to their surroundings and coatings play an important role in this heat rejection. The coatings provide the combined optical properties of low solar absorptance and high infrared emittance. The coatings are applied to the radiator panel in a number of ways, including conventional spraying, plasma spraying, or as an applique. Not designed for a terrestrial weathering environment, the durability of spacecraft paints, coatings, and appliques upon exposure to weathering and subsequent exposure to ascent heating, solar wind, and ultraviolet radiation was studied. In addition to traditional aluminum panels, new isocyanate ester composite panels were exposed for a total of 90 days at the Atmospheric Exposure Site of Kennedy Space Center's (KSC) Beach Corrosion Facility for the purpose of identifying their durability to weathering. Selected panel coupons were subsequently exposed to simulated ascent heating, solar wind, and vacuum ultraviolet (UV) radiation to identify the effect of a simulated space environment on as-weathered surfaces. Optical properties and adhesion testing were used to document the durability of the paints, coatings, and appliques.

Jaworske, Donald A.↗
NASA NTRS2008

Failure Mechanisms and Life Prediction of Thermal and Environmental Barrier Coatings under Thermal Gradients

Ceramic thermal and environmental barrier coatings (TEBCs) will play an increasingly important role in gas turbine engines because of their ability to further raise engine temperatures. However, the issue of coating durability is of major concern under high-heat-flux conditions. In particular, the accelerated coating delamination crack growth under the engine high heat-flux conditions is not well understood. In this paper, a laser heat flux technique is used to investigate the coating delamination crack propagation under realistic temperature-stress gradients and thermal cyclic conditions. The coating delamination mechanisms are investigated under various thermal loading conditions, and are correlated with coating dynamic fatigue, sintering and interfacial adhesion test results. A coating life prediction framework may be realized by examining the crack initiation and propagation driving forces for coating failure under high-heat-flux test conditions.

Zju, Dongming↗
NASA NTRS2012

Synthesis, Characterization, Topographical Modification, and Surface Properties of Copoly(Imide Siloxane)s

Novel copoly(imide siloxane)s were synthesized from commercially available aminopropyl terminated siloxane oligomers, aromatic dianhydrides, and diamines. This synthetic approach produced copolymers with well-defined siloxane blocks linked with imide units in a random fashion. The copoly(amide acid)s were characterized by solution viscosity and subsequently used to cast thin films followed by thermal imidization in an inert atmosphere. Thin films were characterized using contact angle goniometry, attenuated total reflection Fourier transform infrared spectroscopy, confocal and optical microscopy, and tensile testing. Adhesion of micronsized particles was determined quantitatively using a sonication device. The polydimethylsiloxane (PDMS) moieties lowered the copolymer surface energy due to migration of siloxane moieties to the film s surface, resulting in a notable reduction in particle adhesion. A further reduction in particle adhesion was achieved by introducing topographical features on a scale of several to tens of microns by a laser ablation technique.

Wohl, Christopher J.↗
NASA NTRSDate not supplied

NASA Icing Update – May 2024

This presentation provides a status update on select NASA icing research activities for the SAE AC-9C Icing Technical Committee Meeting on May 6, 2024. The updates include the following topics: (1) Propulsion Systems Lab (PSL), (2) Adaptive Icing Tunnel (AIT), (3) Ice Adhesion / Deformed Skin Adhesion Test, (4) GlennICE, (5) Efficient Quiet Integrated Propulsor, (6) Icing Research Tunnel (IRT) CFD Characterization, and (7) Supercooled Large Droplet (SLD) Research.

Icing↗
NASA NTRS1956

Tests to Determine the Adhesive Power of Passenger-Car Tires

The concept of the adhesive power of a tire with respect to the road involves several properties which result from the purpose of the tire; namely, connecting link between vehicle and road: (1) The tire must transfer the tractive and braking forces acting in the direction of travel (tractive and braking adhesion); (2) The tire is to prevent lateral deviations of the vehicle from the desired direction of travel (track adhesion). Moreover, the rubber tire provides part of the springing of the vehicle. Above all, it has to level out the minor road irregularities; thus it smoothes, as it were, the road and simultaneously reduces the noise of driving. The springing properties of the tire affect the adhesive power. The tests described below comprise a determination of the braking and track adhesion of individual tires. The adhesion of driven wheels has not been investigated so far.

Foerster, B.↗
NASA NTRS1994

A test of the adhesion approximation for gravitational clustering

We quantitatively compare a particle implementation of the adhesion approximation to fully nonlinear, numerical 'N-body' simulations. Our primary tool, cross-correlation of N-body simulations with the adhesion approximation, indicates good agreement, better than that found by the same test performed with the Zel'dovich approximation (hereafter ZA). However, the cross-correlation is not as good as that of the truncated Zel'dovich approximation (TZA), obtained by applying the Zel'dovich approximation after smoothing the initial density field with a Gaussian filter. We confirm that the adhesion approximation produces an excessively filamentary distribution. Relative to the N-body results, we also find that: (a) the power spectrum obtained from the adhesion approximation is more accurate that that from ZA to TZA, (b) the error in the phase angle of Fourier components is worse that that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but that TZA is more accurate dynamically, in the sense of moving mass to the right place.

Melott, Adrian L.↗
NASA NTRS1993

A test of the adhesion approximation for gravitational clustering

We quantitatively compare a particle implementation of the adhesion approximation to fully non-linear, numerical 'N-body' simulations. Our primary tool, cross-correlation of N-body simulations with the adhesion approximation, indicates good agreement, better than that found by the same test performed with the Zel-dovich approximation (hereafter ZA). However, the cross-correlation is not as good as that of the truncated Zel-dovich approximation (TZA), obtained by applying the Zel'dovich approximation after smoothing the initial density field with a Gaussian filter. We confirm that the adhesion approximation produces an excessively filamentary distribution. Relative to the N-body results, we also find that: (a) the power spectrum obtained from the adhesion approximation is more accurate than that from ZA or TZA, (b) the error in the phase angle of Fourier components is worse than that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but that TZA is more accurate dynamically, in the sense of moving mass to the right place.

Melott, Adrian L.↗
NASA NTRS2018

Influence of Thin-Film Adhesives in Pullout Tests Between Nickel-Titanium Shape Memory Alloy and Carbon Fiber-Reinforced Polymer Matrix Composites

Strips of nickel-titanium (NiTi) shape memory alloy (SMA) and carbon fiber-reinforced polymer matrix composite (PMC) were bonded together using multiple thin film adhesives and their mechanical strengths were evaluated under pullout test configuration. Tensile and lap shear tests were conducted to confirm the deformation of SMAs at room temperature and to evaluate the adhesive strength between the NiTi strips and the PMC. Optical and scanning electron microscopy techniques were used to examine the interfacial bonding after failure. Simple equations on composite tensile elongation were used to fit the experimental data on tensile properties. ABAQUS models were generated to show the effects of enhanced bond strength and the distribution of stress in SMA and PMC. The results revealed that the addition of thin film adhesives increased the average adhesive strength between SMA and PMC while halting the room temperature shape memory effect within the pullout specimen.

Polymer Matrix Composites↗
NASA NTRS1997

Bonding and Sealing Evaluations for Cryogenic Tanks

Several different cryogenic tank concepts are being considered for reusable launch vehicles (RLV'S) . Though different tank concepts are being considered, many will require that the cryogenic insulation be evacuated and be bonded to a structure. In this work, an attempt was made to evaluate the effectiveness of maintaining a vacuum on a specimen where foam or honeycomb core was encased within Gr/Ep. In addition to these tests, flatwise adhesion pull off tests were performed at room temperature with PR 1664, EA 9394, FM-300, Crest 3170, and HT 435 adhesives. The materials bonded included Gr/Ep, Gr/BMI, Al, and stainless steel facesheets, and Ti honeycomb, Hexcel honeycomb, and Rohacell foam core materials.

Glass, David E.↗
NASA NTRS1984

Lightning protection guidelines and test data for adhesively bonded aircraft structures

The highly competitive marketplace and increasing cost of energy has motivated manufacturers of general aviation aircraft to utilize composite materials and metal-to-metal bonding in place of conventional fasteners and rivets to reduce weight, obtain smoother outside surfaces and reduce drag. The purpose of this program is protection of these new structures from hazardous lightning effects. The program began with a survey of advance-technology materials and fabrication methods under consideration for future designs. Sub-element specimens were subjected to simulated lightning voltages and currents. Measurements of bond line voltages, electrical sparking, and mechanical strength degradation were made to comprise a data base of electrical properties for new technology materials and basic structural configurations. The second hase of the program involved tests on full scale wing structures which contained integral fuel tanks and which were representative of examples of new technology structures and fuel systems. The purpose of these tests was to provide a comparison between full scale structural measurements and those obtained from the sub-element specimens.

Pryzby, J. E.↗
NASA NTRS1970

Nondestructive sonic testing of adhesive-bonded composites

System detects and determines the location, depth, and areas of crushed core or of breaks in bonding between core and adhesive, adhesive and face sheet, or face sheet and external doubler. It is applicable to honeycomb panels of metal and/or plastics and to metal-to-metal laminates.

Caustin, E. L.↗
NASA NTRS1992

Thread-Pull Test Of Curing Adhesive

Hardness (and degree of cure) of adhesive layer measured by pulling previously inserted thread out of layer. Strength of bond measured directly on assembly rather than on samples, which can be misleading.

Johnson, James A.↗
NASA NTRS1982

Mechanical properties of adhesive systems at cryogenic and other temperatures

This paper presents a summary of the National Transonic Facility (NTF) fan blade adhesive characterization tests. Data was obtained at -300 F, room temperature (RT) and 200 F. The adhesive characterization data was acquired using specimens fabricated from materials orientated to simulate the lay up of the fan blades. Specimen fabrication, characterization tests, test equipment, test data, results and concluding remarks are reported. Adhesive test results are presented for specimens of the following types: lap shear, double lap shear, butt, short beam shear, flexure, and differential strain.

Staton, W. L.↗