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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Analysis, design and testing of high pressure waterjet nozzles

The Hydroblast Research Cell at MSFC is both a research and a processing facility. The cell is used to investigate fundamental phenomena associated with waterjets as well as to clean hardware for various NASA and contractor projects. In the area of research, investigations are made regarding the use of high pressure waterjets to strip paint, grease, adhesive and thermal spray coatings from various substrates. Current industrial methods of cleaning often use ozone depleting chemicals (ODC) such as chlorinated solvents, and high pressure waterjet cleaning has proven to be a viable alternative. Standard methods of waterjet cleaning use hand held or robotically controlled nozzles. The nozzles used can be single-stream or multijet nozzles, and the multijet nozzles may be mounted in a rotating head or arranged in a fan-type shape. We consider in this paper the use of a rotating, multijet, high pressure water nozzle which is robotically controlled. This method enables rapid cleaning of a large area, but problems such as incomplete coverage (e.g. the formation of 'islands' of material not cleaned) and damage to the substrate from the waterjet have been observed. In addition, current stripping operations require the nozzle to be placed at a standoff distance of approximately 2 inches in order to achieve adequate performance. This close proximity of the nozzle to the target to be cleaned poses risks to the nozzle and the target in the event of robot error or the striking of unanticipated extrusions on the target surface as the nozzle sweeps past. Two key motivations of this research are to eliminate the formation of 'coating islands' and to increase the allowable standoff distance of the nozzle.

Mazzoleni, Andre P.↗
NASA NTRS1993

Preparation of particle-dispersion alloys (M-6)

A particle dispersion alloy is one type of metal-ceramic composite material, and is used as heat resistance material, wear resistance material, and electrical material. This material consists of a metal matrix and dispersed particles, and for its unique structure it has both tenacity as a metal and hardness as a ceramic. Its properties improve when the particles become finer and disperse more uniformly. Most of the particle dispersion alloys are produced by the powder metallurgical process. This process is favorable for uniform dispersion of particles, but it consists of complicated techniques such as mechanical alloying and hot extrusion, and has the following drawbacks: (1) it is difficult to fabricate large-sized products; (2) the amount of particles is limited to a few percent; and (3) the process is complicated and expensive. To overcome these drawbacks, recently special attention has been paid to conventional melting process. However, under terrestrial conditions, dispersions separate immediately due to the different specific gravities of the metal matrix and the particles and thermal convection effects. The microgravity environment is, therefore, considered to be an attractive place for fabricating the dispersion alloy. This space experiment is carried out to clarify the influence of microgravity on the properties of the particle dispersion alloy and to obtain a deeper understanding of the experiment under the microgravity environment.

Muramatsu, Yuji↗
NASA NTRS1972

The Apollo 15 lunar samples - A preliminary description.

Samples returned from the Apollo 15 site consist of mare basalts and breccias with a variety of premare igneous rocks. The mare basalts are from at least two different lava flows. The bulk chemical compositions and textures of these rocks confirm the previous conclusion that the lunar maria consist of a series of extrusive volcanic rocks that are rich in iron and poor in sodium. The breccias contain abundant clasts of anorthositic fragments along with clasts of basaltic rocks much richer in plagioclase than the mare basalts. These two rock types also occur as common components in soil samples from this site. The rocks and soils from both the front and mare region exhibit a variety of shock characteristics that can best be ascribed to ray material from the craters Aristillus or Autolycus.

Source record↗
NASA NTRS1979

Further development and application of polycrystalline metal whiskers

High strength metal whiskers have a larger versatile field of application than monocrystalline whiskers. Although polycrystalline metal whiskers can be used for composites, preferably by extrusion in thermoplastics or by infiltration of resins or metals into whisker networks, the chief application at present may be the production and various use of whisker networks. Such networks can be produced up to high degrees of porosity and besides high mechanical strength, they have high inside surfaces and high electric conductivity. There are for instance, applications concerning construction of electrodes for batteries and fuel cells, catalysts and also new heat-exchanger material, capable of preparing fuel oil and gasoline in order to assist a high-efficiency combustion. The technical application of polycrystalline metal whiskers require their modification as well as the construction of a pilot production unit.

Schladitz, H. J.↗
NASA NTRS1990

Right-lateral shear and rotation as the explanation for strike-slip faulting in eastern Tibet

Bounds are placed here on the rate of rotation proposed by Cobbold and Davy (1988) for the major strike-slip faults in the eastern Tibetan Plateau. It is also concluded here that the image of lateral transport on such faults, known also as continental escape, extrusion, or expulsion, is an illusion, and that instead the left-lateral slip on east-striking plates in eastern Tibet is a manifestation of north-striking right-lateral simple shear. If this conclusion is correct, the east-striking left-lateral faults and the crustal blocks between them are rotating clockwise at 1-2 deg/Myr, the east-west dimension of eastern Tibet is shortening at 10-20 mm/yr, and little material is moving eastward out of India's path into Eursasia by left-lateral simple shear.

England, Philip↗
NASA NTRS2019

Multifunctional Polymers and Composites for Aerospace Applications

System needs and challenges for commercial aviation and space exploration are constantly changing. Multifunctional materials are ideal for aerospace applications because their integration into structural components has potential to not only improve efficiency, but it can also increase payload and mission capabilities without the burden of significant additions to mass and volume. Multi-constituent materials will play an important role in enabling structures with the potential to demonstrate true multi-functionality; however, modifications to many mature polymer processing methods may be necessary. This presentation will cover multifunctional materials development efforts underway at the NASA Glenn Research Center related to formulating and characterizing novel electrical insulation for high voltage aircraft. Incorporating functionality into the reinforcement material is another materials development technique that will be discussed, which includes braiding with hybrid fibers to enhance toughness in composite structures, stitching with carbon nanotube yarns to make durable electrically conductive textiles, and treating fabrics with shear thickening fluid suspensions to produce impact-resistant inflatable habitats.

multi-functional composites↗
NASA NTRS1977

Imaging natural materials with a quasi-microscope

A Viking lander camera with auxilliary optics mounted inside the dust post was evaluated to determine its capability for imaging the inorganic properties of granular materials. During mission operations, prepared samples would be delivered to a plate positioned within the camera's field of view and depth of focus. The auxiliary optics would then allow soil samples to be imaged with an 11 pm pixel size in the broad band (high resolution, black and white) mode, and a 33 pm pixel size in the multispectral mode. The equipment will be used to characterize: (1) the size distribution of grains produced by igneous (intrusive and extrusive) processes or by shock metamorphism, (2) the size distribution resulting from crushing, chemical alteration, or by hydraulic or aerodynamic sorting; (3) the shape and degree of grain roundness and surface texture induced by mechanical and chemical alteration; and (4) the mineralogy and chemistry of grains.

Bragg, S.↗
NASA NTRS1980

Sintered silicon nitrode recuperator fabrication

The preliminary design and a demonstration of the feasibility of fabricating submodules of an automotive Stirling engine recuperator for waste heat recovery at 370 C are described. Sinterable silicon nitride (Sialon) tubing and plates were fabricated by extrusion and hydrostatic pressing, respectively, suitable for demonstrating a potential method of constructing ceramic recuperator-type heat exchangers. These components were fired in nitrogen atmosphere to 1800 C without significant scale formation so that they can be used in the as-fired condition. A refractory glass composition (Al2O3 x 4.5 CaO.MgO x 11SiO2) was used to join and seal component parts by a brazing technique which formed strong recuperator submodules capable of withstanding repeated thermal cycling to 1370 C. The corrosion resistance of these materials to Na2SO4 + NaCl carbon mixtures was also assessed in atmospheres of air, hydrogen and CO2-N2-H2O mixtures at both 870 C and 1370 C for times to 1000 hours. No significant reaction was observed under any of these test conditions.

Gatti, A.↗
NASA NTRS2000

Validated Feasibility Study of Integrally Stiffened Metallic Fuselage Panels for Reducing Manufacturing Costs

The continual need to reduce airframe cost and the emergence of high speed machining and other manufacturing technologies has brought about a renewed interest in large-scale integral structures for aircraft applications. Applications have been inhibited, however, because of the need to demonstrate damage tolerance, and by cost and manufacturing risks associated with the size and complexity of the parts. The Integral Airframe Structures (IAS) Program identified a feasible integrally stiffened fuselage concept and evaluated performance and manufacturing cost compared to conventional designs. An integral skin/stiffener concept was produced both by plate hog-out and near-net extrusion. Alloys evaluated included 7050-T7451 plate, 7050-T74511 extrusion, 6013-T6511 extrusion, and 7475-T7351 plate. Mechanical properties, structural details, and joint performance were evaluated as well as repair, static compression, and two-bay crack residual strength panels. Crack turning behavior was characterized through panel tests and improved methods for predicting crack turning were developed. Manufacturing cost was evaluated using COSTRAN. A hybrid design, made from high-speed machined extruded frames that are mechanically fastened to high-speed machined plate skin/stringer panels, was identified as the most cost-effective manufacturing solution. Recurring labor and material costs of the hybrid design are up to 61 percent less than the current technology baseline.

Pettit, R. G.↗
NASA NTRS1984

Fabrication development for ODS-superalloy, air-cooled turbine blades

MA-600 is a gamma prime and oxide dispersion strengthened superalloy made by mechanical alloying. At the initiation of this program, MA-6000 was available as an experimental alloy only and did not go into production until late in the program. The objective of this program was to develop a thermal-mechanical-processing approach which would yield the necessary elongated grain structure and desirable mechanical properties after conventional press forging. Forging evaluations were performed to select optimum thermal-mechanical-processing conditions. These forging evaluations indicated that MA-6000 was extremely sensitive to die chilling. In order to conventionally hot forge the alloy, an adherent cladding, either the original extrusion can or a thick plating, was required to prevent cracking of the workpiece. Die design must reflect the requirement of cladding. MA-6000 was found to be sensitive to the forging temperature. The correct temperature required to obtain the proper grain structure after recrystallization was found to be between 1010-1065 C (1850-1950 F). The deformation level did not affect subsequent crystallization; however, sharp transition areas in tooling designs should be avoided in forming a blade shape because of the potential for grain structure discontinuities. Starting material to be used for forging should be processed so that it is capable of being zone annealed to a coarse elongated grain structure as bar stock. This conclusion means that standard processed bar materials can be used.

Moracz, D. J.↗
NASA NTRS1984

High temperature properties of equiatomic FeAl with ternary additions

The aluminide intermetallic compounds are considered potential structural materials for aerospace applications. The B2 binary aluminide FeAl has a melting point in excess of 1500 K, is of simple cubic structure, exits over a wide range of composition with solubility for third elements and is potentially self-protecting in extreme environments. The B2 FeAl compound has been alloyed with 1 to 5 at % ternary additions of Si, Ti, Zr, Hf, Cr, Ni, Co, Nb, Ta, Mo, W, and Re. The alloys were prepared by blending a third elemental powder with prealloyed binary FeAl powder. Consolidation was by hot extrusion at 1250 K. Annealing studies on the extruded rods showed that the third element addition can be classified into three categories based upon the amount of homogenization and the extent of solid solutioning. Constant strain rate compression tests were performed to determine the flow stress as a function of temperature and composition. The mechanical strength behavior was dependent upon the third element homogenization classification.

Titran, R. H.↗
NASA NTRS1991

Elevated temperature cracking of RSP aluminum alloy 8009 - Characterization of the environmental influence

Degradation of the material properties of the Al alloy is examined to determine the effects of moist air and predissolved hydrogen on elevated-temperature fatigue and fracture resistance. Experiments are conducted at 175 C in both moist air and high vacuum with as-processed specimens and specimens that are vacuum-heat-treated. Fracture mechanics characterizations are made for initiation and propagation fracture toughnesses during rising load, fatigue-crack propagation kinetics, and sustained-load crack-growth rates. Time-dependent embrittlement at intermediate temperatures is identified in both plate and extrusion samples of the Al-Fe-Si-V alloy 8009. Intermediate temperature cracking is found to be the same for each case in both vacuum and moist air, and the vacuum heat treatment does not significantly affect the results.

Porr, William C., Jr.↗
NASA NTRS1972

Study of a columnar grain structure produced in a superalloy by gradient-annealing prealloyed powder extrusions

Annealing in a temperature gradient was used to produce a structure of continuous columnar grains in alloy 713 C made by extrusion of prealloyed powder. The columnar-grained specimens had tensile strengths within plus or minus 5 percent of those of the as-cast alloy at 760 C and 980 C but were significantly stronger at room temperature. Stress-rupture tests at 760 C and 980 C showed lives scattered from 17 to 376 percent of those of as-cast 713 C tested under the same conditions. X-ray diffraction studies showed the large grains formed upon annealing to have a well-defined texture, although the as-extruded material had none.

Miner, R. V., Jr.↗
NASA NTRS1985

High temperature properties of equiatomic FeAl with ternary additions

The aluminide intermetallic compounds are considered potential structural materials for aerospace applications. The B2 binary aluminide FeAl has a melting point in excess of 1500 K, is of simple cubic structure, exists over a wide range of composition with solubility for third elements and is potentially self-protecting in extreme environments. The B2 FeAl compound has been alloyed with 1 to 5 at. pct ternary additions of Si, Ti, Zr, Hf, Cr, Ni, Co, Nb, Ta, Mo, W, and Re. The alloys were prepared by blending a third elemental powder with pre-alloyed binary FeAl powder. Consolidation was by hot extrusion at 1250 K. Annealing studies on the extruded rods showed that the third element addition can be classified into three categories based upon the amount of homogenization and the extent of solid solutioning. Constant strain rate compression tests were performed to determine the flow stress as a function of temperature and composition. The mechanical strength behavior was dependent upon the third element homogenization classification.

Titran, R. H.↗
NASA NTRS1993

Status of the NASA Balloon Program

The NASA Balloon Program (BP) is examined in an overview of design philosophy, R&D activities, flight testing, and the development of a long-duration balloon for Antarctic use. The Balloon Recovery Program was developed to qualify the use of existing films and to design improved materials and seals. Balloon flights are described for studying the supernova SN1987a, and systems were developed to enhance balloon campaigns including mobile launch vehicles and tracking/data-acquisition systems. The technical approach to long-duration ballooning is reviewed which allows the use of payloads of up to 1350 kg for two to three weeks. The BP is responsible for the development of several candidate polyethylene balloon films as well as design/performance standards for candidate balloons. Specific progress is noted in reliability and in R&D with respect to optimization of structural design, resin blending, and extrusion.

Needleman, H. C.↗
NASA NTRS1996

Effects of thermomechanical processing on the microstructure and mechanical properties of Nb-1Zr-C alloys

A systematic study to evaluate the effects of thermomechanical processing on the microstructure and mechanical properties of Nb-1Zr alloy sheet containing 0.06 and 0.1 wt.%C (PWC-11) was conducted and compared to the results of Nb-1Zr. Coarse orthorhombic Nb2C precipitates were present in all the cast, extruded and cold rolled Nb-Zr samples containing C. After high temperature (greater than 0.5 T(sub m)) exposure (with or without applied stress), the Nb2C transforms to very fine and extremely stable FCC (Zr, Nb)C dispersoid, resulting in a highly creep resistant material. Only ZrO2 precipitates were found in Nb-1Zr. The creep strength of the 0.06C and the 0.1C carbide strengthened alloys were much superior to Nb-1Zr. At 1350 K the strength of the 0.06C alloy was about three times that of Nb-1Zr, while the 0.1C alloy had about five times the creep stress capability of Nb-1Zr. The tensile strength, long term creep strength, and stability of the microstructure of the PWC-11 sheet appear to be independent of the number of 1900 K extrusions performed prior to cold rolling. The microhardness of these single, double and triple extnided PWC-11 sheets also were comparable. The tensile strength of PWC-11 and Nb-1Zr at room temperature and 1350 K were comparable.

Titran, Robert H.↗
NASA NTRS1993

Venusian pancake domes: Insights from terrestrial voluminous silicic lavas and thermal modeling

The so-called 'pancake' domes, and several other volcanoes on Venus, appear to represent large extrusions of silicic lava. Similar voluminous rhyolite lava flows, often associated with mantle plumes, are known on Earth. Venus' high ambient temperature, and insulation by the dome's brecciated carapace, both act to prolong cooling of a dome's interior, allowing for episodic lava input over an extended period of time. Field relations and aspect ratios of terrestrial voluminous rhyolite lavas imply continuous, non-episodic growth, reflecting tapping of a large volume of dry, anatectic silicic magma. Petrogenetically, the venusian domes may be analogous to chains of small domes on Earth, which represent 'leakage' of evolved material from magma bodies fractionating from much more mafic liquids.

Manley, Curtis R.↗
NASA NTRS2016

Irregular Mare Patches (IMPs): 100 Ma or 3 Ga?

IMPs exhibit a perplexing combination of characteristics that are consistent with either an approximately 100 Ma or 3 Ga formation. Dozens of small-area IMPs have crisp morphologies and crater size-frequency distributions (SFDs) that denote relatively recent geologic activity (less than 100 Ma); however, the apparently well-developed regolith on portions of the IMPs are in conflict with such a young age [1]. To test possible formation hypotheses (e.g., [1-5]), which range from ancient volcanism to contemporary outgassing, we examined IMP morphology at the meter-scale with LROC NAC images and derived elevation models. We focused on the largest IMPs (Ina, Sosigenes, Cauchy, Maskelyne, and Nubium), where contacts between deposits are best developed. Most of our observations are consistent with multiple generations of inflation and breakouts (or squeeze-ups) of basaltic lavas that were affected by local slopes. Some of the extrusions coalesced into larger mounds or filled pre-existing craters. We did not observe evidence of large-scale void space (e.g., fissures, fractures, linear depressions, or pits) within or beneath the mounds or rougher deposits (e.g., [5]). But, small-scale voids may be signified by isolated pitted textures. We also did not detect evidence of the cooling fractures or lava plates expected in young lava flows and observed in lunar impact melt deposits. The smooth texture of the mounds is enigmatic. Block-less craters suggest at least 5 m of friable or poorly-cohesive material (such as regolith), yet mound margins exhibit slopes greater than 30 deg requiring significant material strength. Blocks are not common on the mounds, but are sometimes excavated by impacts (usually excavated from beneath the mounds). The uneven deposits are equally enigmatic and texturally varied (blocky, pitted, and crenulated). They are deficient in superposed craters compared to the mounds. If the mounds are indeed of similar age to the rougher units, then their different superposed crater morphologies and SFDs need to be explained by factors other than their ages. Any mounds originally composed of friable surface materials would evolve differently from more coherent deposits (e.g., [6-7]).

Stopar, Julie↗