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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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50 records · Page 3

Nonmetallic Material Compatibility with Liquid Fluorine

Static tests were made on the compatibility of liquid fluorine with several nonmetallic materials at -3200 F and at pressures of 0 and 1500 pounds per square inch gage. The results are compared with those from previous work with gaseous fluorine at the same pressures, but at atmospheric temperature. In general, although environmental effects were not always consistent, reactivity was least with the low-temperature, low-pressure liquid fluorine. Reactivity was greatest with the warm, high-pressure gaseous fluorine. None of the liquids and greases tested was found to be entirely suitable for use in fluorine systems. Polytrifluorochloroethylene and N-43, the formula for which is (C4F9)3N, did not react with liquid fluorine at atmospheric pressure or 1500 pounds per square inch gage under static conditions, but they did react when injected into liquid fluorine at 1500 pounds per square inch gage; they also reacted with gaseous fluorine at 1500 pounds per square inch gage. While water did not react with liquid fluorine at 1500 pounds per square inch gage, it is known to react violently with fluorine under other conditions. The pipe-thread lubricant Q-Seal did not react with liquid fluorine, but did react with gaseous fluorine at 1500 pounds per square inch gage. Of the solids, ruby (Al2O3) and Teflon did not react under the test conditions. The results show that the compatibility of fluorine with nonmetals depends on the state of the fluorine and the system design.

Price, Harold G , Jr↗

Materials, processes, and environmental engineering network

The Materials, Processes, and Environmental Engineering Network (MPEEN) was developed as a central holding facility for materials testing information generated by the Materials and Processes Laboratory. It contains information from other NASA centers and outside agencies, and also includes the NASA Environmental Information System (NEIS) and Failure Analysis Information System (FAIS) data. Environmental replacement materials information is a newly developed focus of MPEEN. This database is the NASA Environmental Information System, NEIS, which is accessible through MPEEN. Environmental concerns are addressed regarding materials identified by the NASA Operational Environment Team, NOET, to be hazardous to the environment. An environmental replacement technology database is contained within NEIS. Environmental concerns about materials are identified by NOET, and control or replacement strategies are formed. This database also contains the usage and performance characteristics of these hazardous materials. In addition to addressing environmental concerns, MPEEN contains one of the largest materials databases in the world. Over 600 users access this network on a daily basis. There is information available on failure analysis, metals and nonmetals testing, materials properties, standard and commercial parts, foreign alloy cross-reference, Long Duration Exposure Facility (LDEF) data, and Materials and Processes Selection List data.

White, Margo M.↗

Near-net-shape manufacturing: Spray-formed metal matrix composites and tooling

Spray forming is a materials processing technology in which a bulk liquid metal is converted to a spray of fine droplets and deposited onto a substrate or pattern to form a near-net-shape solid. The technology offers unique opportunities for simplifying materials processing without sacrificing, and oftentimes substantially improving, product quality. Spray forming can be performed with a wide range of metals and nonmetals, and offers property improvements resulting from rapid solidification (e.g. refined microstructures, extended solid solubilities and reduced segregation). Economic benefits result from process simplification and the elimination of unit operations. The Idaho National Engineering Laboratory is developing a unique spray-forming method, the Controlled Aspiration Process (CAP), to produce near-net-shape solids and coatings of metals, polymers, and composite materials. Results from two spray-accompanying technical and economic benefits. These programs involved spray forming aluminum strip reinforced with SiC particulate, and the production of tooling, such as injection molds and dies, using low-melting-point metals.

Mchugh, Kevin M.↗

An Investigation of High-Velocity Impact Cratering into Nonmetallic Targets and Correlation of Penetration Data for Metallic and Nonmetallic Targets

Experimental results have been obtained on the cratering of metals and nonmetals at velocities varying from 500 feet per second to 20,000 feet per second with various combinations of metallic and nonmetallic targets and projectiles. Materials investigated include nylon, graphite, laminated phenolic resin, and aluminum. From a study of nonmetallic targets after impact, it is indicated that the craters were formed by the crushing of and displacement of the target material. An equation for the relationship between penetration and momentum per unit area has been modified to predict the penetration of target materials tested within the range of this investigation.

Kinard, William H.↗

Development and Progress in Enabling the Photocatalyst Ti02 Visible-Light-Active

Photocatalytic oxidation (PCO) of organic contaminants is a promising air and water quality management approach which offers energy and cost savings compared to thermal catalytic oxidation (TCO). The most widely used photocatalyst, anatase TiO2, has a wide band gap (3.2 eV) and is activated by UV photons. Since solar radiation consists of less than 4% UV, but contains 45% visible light, catalysts capable of utilizing these visible photons need to be developed to make peo approaches more efficient, economical, and safe. Researchers have attempted various approaches to enable TiO2 to be visible-light-active with varied degrees of success'. Strategies attempted thus far fall into three categories based on their electrochemical' mechanisms: 1) narrowing the band gap of TiO2 by implantation of transition metal elements or nonmetal elements such as N, S, and C, 2) modifying electron-transfer processes during PCO by adsorbing sensitizing dyes, and 3) employing light-induced interfacial electron transfer in the heteronanojunction systems consisting of narrow band gap semiconductors represented by metal sulfides and TiO2. There are diverse technical approaches to implement each of these strategies. This paper presents a review of these approaches and results of the photocatalytic activity and photonic efficiency of the end .products under visible light. Although resulting visible-light-active (VLA) photocatalysts show promise, there is often no comparison with unmodified TiO2 under UV. In a limited number of studies where such comparison was provided, the UV-induced catalytic activity of bare TiO2 is much greater than the visible-light-induced catalytic activity of the VLA catalyst. Furthermore, VLA-catalysts have much lower quantum efficiency compared to the approx.50% quantum efficiency of UV-catalysts. This stresses the need for continuing research in this area.

Levine, Lanfang H.↗

NASA-STD-6001B Test 7: Impact of Test Methodology and Detection Advancements on the Obsolescence of Historical Offgas Data

NASA-STD-6001B states "all nonmetals tested in accordance with NASA-STD-6001 should be retested every 10 years or as required by the responsible program/project." The retesting of materials helps ensure the most accurate data are used in material selection. Manufacturer formulas and processes can change over time, sometimes without an update to product number and material information. Material performance in certain NASA-STD-6001 tests can be particularly vulnerable to these changes, such as material offgas (Test 7). In addition, Test 7 analysis techniques at NASA White Sands Test Facility were dramatically enhanced in the early 1990s, resulting in improved detection capabilities. Low level formaldehyde identification was improved again in 2004. Understanding the limitations in offgas analysis data prior to 1990 puts into question the validity and current applicability of that data. Case studies on Super Koropon (Registered trademark) and Aeroglaze (Registered trademark) topcoat highlight the importance of material retesting.

Buchanan, Vanessa D.↗

History of NASA's Determination of Offgassed Products (Test 7)

NASA's Determination of Offgassed Products (Test 7) from materials and assembled articles for spaceflight has evolved since the Apollo program for over 50 years to meet various habitable spacecraft nonmetallic programmatic requirements. Now mandated by NASA STD-6016A, Standard Materials and Processes Requirements for Spacecraft, all nonmetallic materials used in habitable flight compartments, with the exception of ceramics, metal oxides, inorganic glasses, and materials used in sealed containers, must meet the offgassing requirements in NASA-STD-6001B Test 7. This manuscript presents the history of Test 7, beginning with the Apollo spacecraft nonmetallic materials selection guidelines and test requirements in 1967, in which tests were performed in mostly oxygen atmospheres. It progresses through Skylab, Space Shuttle, International Space Station nonmetals testing, and acceptance requirements with milder test environments. This review of the history of Test 7 presents the reader with a perspective on the development and changes undergone since inception to the present. Related NASA standard tests (some now former, discontinued, combined, or supplemental) including Test 6, Odor Assessment, Test 16, Determination of Offgassed Products from Assembled Articles, and Test 12, Total Spacecraft Cabin Offgassing, are discussed in context

Greene, Benjamin↗

History of NASA’s Odor Assessment (Test 6)

NASA's Odor Assessment (Test 6) for nonmetallic materials and assembled articles for spacecraft has evolved since the Apollo program in 1966 to meet various habitable spacecraft nonmetallic programmatic requirements. The purpose of Test 6 is to determine if the odor from a material or assembled article is objectionable or revolting on an odor-characteristic scale of 0 to 4. Samples of the toxicity-screened test atmosphere from a conditioned specimen container are administered to an Odor Panel of qualified human research subject volunteers using a syringe and mask, and are assigned a scored odor characteristic of undetectable (0), barely detectable (1), easily detectable (2), objectionable (3), or revolting (4). The odor from a material or assembled article is objectionable or revolting if an average rating of 2.5 or higher is assigned by an Odor Panel. This manuscript presents the history of Test 6, beginning with the Apollo spacecraft nonmetallic materials selection guidelines and test requirements from 1966, in which tests were performed in oxygen atmospheres, and follows the odor test through Skylab, Space Shuttle, International Space Station, and Orion nonmetals testing, and acceptance requirements.

Benjamin Greene↗

Optical Pathlength Control Experiment on JPL Phase B Testbed

An experimental implementation of a nanometer level optical pathlength control for large baseline space interferometry is presented. The pathlength compensation system is installed on a large flexible experimental truss, thus structural motions play a dominant role in the control system design. The associated control structure interaction problem is addressed to maintain the optical pathlength within the prescribed variation of 10-15 nanometer rms. By a successful blend of a structural control for damping augmentation and a direct pathlength control for the pathlength compensation, the optical pathlength variation has been maintained within 6 nonometer rms under the laboratory ambient disturbance and within 9 nonmeter rms under a severe forced resonant disturbance.

interferometry↗

Preliminary Investigation of Fretting

An experimental investigation, using microscopic observation and color motion photomicrographs of the action, was conducted to determine the cause of fretting. Glass and other noncorrosive materials, as well as metals, were used as specimens. A very simple apparatus vibrated convex surfaces in contact with stationary flat surfaces at frequencies of 120 cycles or less than one cycle per second, an amplitude of 0.001 inch, and a load of 0.2 pound. The observations and analysis led to the conclusions that fretting was initiated by the loosening, due to the inherent adhesive forces, of finely divided and apparently virgin material, and that its initiation is independent of vibratory motion or high sliding speeds. The fretting of platinum, glass, quartz, ruby, and mica relegated the role of oxidation as a cause to that of a secondary factor. Fretting occurred to clean nonmetals and metals readily, and glass microscope slides and steel balls provide excellent method for visual studies. Video run time 9:54, color and sound (mp4). Available for download for best viewing. Document indicated in video is related in the repository and can also be downloaded for use at https://ntrs.nasa.gov/citations/19930083206.

fretting↗

Non-metallic materials

Nonmetallic materials development - cryogenic insulation, adhesives research, and membrane diffusion theory

NONMETAL↗