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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Technology development of a biowaste resistojet, volume 1

The materials research effort conducted in support of a NASA-sponsored biowaste resistojet development program is summarized. The resistojet concept under development is the concentric tube design wherein the final pass of the gases through the thruster is through the resistance heated center tube. To produce high specific impulses, this center tube must operate at very high temperatures and it is this element that is most critical in the design. Because of the corrosive nature of the biowaste gases at high temperature, and because of the limited data available for many potential materials, the subject materials study was conducted.

Phillips, D. G.↗
NASA NTRS1971

Oxidation screening at 1204 C /2200 F/ of candidate alloys for the space shuttle thermal protection system.

Evaluation of the oxidation resistance of 15 alloys under some of the environmental conditions that might be encountered by the shuttle thermal protection system. The alloys included nickel-, iron-, and cobalt-base wrought alloys. Specimens were self-resistively heated to 1204 C (2200 F) in a 10-torr still-air environment for 100 thirty-minute cycles. Specimen weight, thickness, and microstructural changes were noted, and surface scales were identified by room-temperature X-ray diffraction. Based on these observations, the behavior of the alloys was evaluated in terms of overall amount of metal consumption due to oxide formation and relative tendency toward oxide spalling and scale vaporization.

Sanders, W. A.↗
NASA NTRS1971

Low-pressure oxidation of Cb-1Zr alloy.

Resistively heated strip specimens of Cb-1Zr alloy were exposed at 927 C in a vacuum chamber at various levels of total pressure in the 1-microtorr range and at various oxygen partial pressures in the .1-microtorr range. Oxygen reaction rates (sticking probabilities) were found to depend on whether or not the specimens were annealed immediately before the test exposure. It is shown that a normally undetectable oxide film exists on the Cb-1Zr surface as a result of oxidation by ambient air, and this film reduces the sticking probability as compared with a clean metal surface. The alloy is considerably strengthened by addition of oxygen to a level of about 6000 ppm, while still maintaining reasonably good room temperature ductility.

Lyon, T. F.↗
NASA NTRS1971

NASA research on refractory compounds.

The behavior and properties of the refractory carbides, nitrides, and borides are being investigated by NASA as part of its research aimed at developing superior heat resistant materials for aerospace applications. Studies of the zirconium-carbon-oxygen system show that zirconium oxycarbides of different compositions and lattice parameters can be formed between 1500 C and 1900 C and are stable below 1500 C. More applied studies show that hot working generally improves the microstructure and therefore the strength of TiC and NbC. Sintering studies on UN indicate that very high densities can be achieved. Hot pressing of cermets of HfN and HfC produces good mechanical properties for high temperature bearing applications. Attempts to improve the impact resistance of boride composites by the addition of a nickel or carbon yarn were not overly successful.

Gangler, J. J.↗
NASA NTRS1971

NASA research on refractory compounds.

The behavior and properties of the refractory carbides, nitrides, and borides are being investigated by NASA as part of its research aimed at developing superior heat resistant materials for aerospace applications. Fundamental studies on the electronic and defect structures of the carbides indicate that there is promise for improving the strength and ductility of these materials. Studies of the zirconium-carbon-oxygen system show that zirconium oxycarbides of different compositions and lattice parameters can be formed between 1500 and 1900 C and are stable below 1500 C. More applied studies show that hot working generally improves the microstructure and therefore the strength of TiC and NbC. Sintering studies on UN indicate that very high densities can be achieved. Hot pressing of cermets of HfN and HfC produces good mechanical properties for high temperature bearing applications.

Gangler, J. J.↗
NASA NTRS1973

Lightweight inflatable material with low permeability

Material features combination of Mylar, for strength, and Saran, for impermeable qualities. Second lamination of Mylar prevents blocking, adds strength, and increases barrier rating. Different combinations of laminations produce variety of thicknesses and barrier ratings. Material can be metallized for increased barrier reliability and radar reflectivity, and can be treated with a heat-resistant coating.

White, E. C.↗
NASA NTRS1972

NASA technology utilization survey on composite materials

NASA and NASA-funded contractor contributions to the field of composite materials are surveyed. Existing and potential non-aerospace applications of the newer composite materials are emphasized. Economic factors for selection of a composite for a particular application are weight savings, performance (high strength, high elastic modulus, low coefficient of expansion, heat resistance, corrosion resistance,), longer service life, and reduced maintenance. Applications for composites in agriculture, chemical and petrochemical industries, construction, consumer goods, machinery, power generation and distribution, transportation, biomedicine, and safety are presented. With the continuing trend toward further cost reductions, composites warrant consideration in a wide range of non-aerospace applications. Composite materials discussed include filamentary reinforced materials, laminates, multiphase alloys, solid multiphase lubricants, and multiphase ceramics. New processes developed to aid in fabrication of composites are given.

Leeds, M. A.↗
NASA NTRS1972

The development of an inert simulant for HNS/teflon explosive

The report describes the development and evaluation of an inert simulant for the thermally stable, heat-resistant plastic-bonded explosive HNS/Teflon. The simulant is made by dry blending vinylidene fluoride, melamine and Teflon which when compared has a pressed density and thermal properties corresponding closely to the explosive. In addition, the machinability and handling characteristics of the simulant are similar to the explosive.

Elban, W. L.↗
NASA NTRS1973

Scientific and technical services directed toward the development of planetary quarantine measures for automated spacecraft

Planetary quarantine requirements and parameters are evaluated for their effects upon automated spacecraft flights data describing the heat resistance of naturally occuring microorganisms and sterilization requirements are analyzed and a possible method for assessment of these data is developed. Pertinent data from planetary mission microbial contamination logs are compiled and maintained in the quarantine document system.

Source record↗
NASA NTRS1973

Black silicate paints: Formulation and performance data on OSO-H

Formulations and general procedures are given for making and applying space environmentally, as well as atmospherically stable black silicate paints. Compositions are given which meet spacecraft self-contamination requirements, have excellent heat resistance, and are strongly semiconductive.

Schutt, J. B.↗
NASA NTRS1973

Energy distribution in parallel plate plasma accelerators

A parallel plate accelerator operated in the quasi-steady regime of argon mass flow discharges permits, on account of its geometry, the appraisal of the initial ratio of energy disposition into the kinetic and thermal modes of the plasma while retaining the essential features of coaxial high power self-field MPD accelerators. The energy disposition ratio, calculated as the ratio of kinetic energy to enthalpy in the exhaust flow, shows reasonable agreement with the ratio of the induced emf in the accelerator to resistive voltage drop. Both these ratios indicate that the discharge imparts more energy to the flow by resistive heating than by direct body force acceleration. This is turn suggests that other acceleration mechanisms must be responsible for the high performance of conventional MPD arcs.

Dicapua, M. S.↗
NASA NTRS1973

Friction behavior of glass and metals in contact with glass in various environments

Sliding friction experiments have been conducted for heat-resistant glass and metals in contact with glass. These experiments were conducted in various environments including vacuum, moist air, dry air, octane, and stearic acid in hexadecane. Glass exhibited a higher friction force in moist air than it did in vacuum when in sliding contact with itself. The metals, aluminum, iron, and gold, all exhibited the same friction coefficient when sliding on glass in vacuum as glass sliding on glass. Gold-to-glass contacts were extremely sensitive to the environment despite the relative chemical inertness of gold.

Buckley, D. H.↗
NASA NTRS1974

Oxidative vaporization kinetics of chromium (III) oxide in oxygen from 1270 to 1570 K

Rates of oxidative vaporization of Cr2O3 on preoxidized resistively heated chromium were determined in flowing oxygen at 0.115 torr for temperatures from 1270 to 1570 K. Reaction controlled rates were obtained from experimental rates by a gold calibration technique. These rates were shown to agree with those predicted by thermochemical analysis. The activation energy obtained for the oxidative vaporation reaction corresponded numerically with the thermochemical enthalpy of the reaction. A theoretical equation is given for calculating the rate from thermodynamic data by using boundary layer theory.

Stearns, C. A.↗
NASA NTRS1972

Extended electrode technique

The extended electrode technique is a unique welding process which utilizes manual gas-metal-arc (GMAW) semi-automatic equipment and close, square butt joints to effectively produce a weld. The technique takes advantage of the resistance heating of the electode extension to effect the root pass. Weldments as large as 72-X30-X2-inch have been fabricated with this technique under normal shipyard welding conditions. Mechanical properties and explosion bulge tests indicate that satisfactory results are obtained with this process. Potential savings of approximately 50 percent can be achieved in flat welding and repair of heavy structural steel members.

Schaper, V. D.↗
NASA NTRS1973

Examination of oxide scales in the SEM using backscattered electron images

The complementary use of the scanning electron microscope in the backscattered electron mode with the more usual secondary electron mode results in a significant increase in the versatility of the instrument, since regions of different chemical composition can be readily detected, and their morphology examined. The use of this technique to examine complex oxide scales formed on heat-resistant alloys is described, and in particular the location of thoria particles in the scale formed on a Ni-20 wt pct Cr-2.3 wt pct ThO2 alloy, and the examination of the behavior of yttrium during the high-temperature oxidation of a Co-Cr-Al-Y alloy are discussed.

Price, C. W.↗
NASA NTRS1974

Oxidative vaporization kinetics of Cr2O3 in oxygen from 1000 to 1300 C

Rates of oxidative vaporization of Cr2O3 on preoxidized resistively heated chromium were determined in flowing oxygen at a pressure of 0.115 Torr for temperatures from 1000 to 1300 C. Reaction controlled rates were obtained from experimental rates by a gold calibration technique, and these rates were shown to agree with those predicted by thermochemical analysis. The activation energy obtained for the oxidative vaporization reaction corresponded numerically with the thermochemical enthalpy of the reaction. A theoretical equation is given for calculating the rate from thermodynamic data using boundary-layer theory.

Stearns, C. A.↗
NASA NTRS1975

Storage stability and improvement of intermediate moisture foods, phase 2

Methods for improvement of shelf-life stability of intermediate moisture foods are considered. It was found that vitamin C is the most limiting vitamin from a nutritional standpoint with its rate of destruction increasing with a sub w. Techniques for microbial challenge studies were developed. It was shown that organisms have a higher growth a sub w limit if the IMF is prepared by the adsorption process and long times are needed for challenge studies. Several alternative antimycotic systems were found. It was also found that the vegetative cells of pathogens have a maximum heat resistance in the IMF a sub w range. If glycols are in the formula, the IMF should have as high an a sub w as possible. The reverse is true if lipid oxidation occurs. In addition, to prevent rancidity, antioxidants and a low O2 atmosphere are necessary. The package also must be a good moisture barrier.

Labuza, T. P.↗
NASA NTRS1975

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

A series of experiments was conducted to determine the dry heat resistance of microorganisms in soil obtained from Denver Colorado, Pasadena California, Kennedy Space Center Florida, and Cincinnati Ohio. The results of the KSC terminal sterilization cycle experiment are given in graphs. The average number of viable organisms per m1 was calculated for 18 replicate soil samples for each sample area and points plotted equivalent to 30 hr exposure at 112 C. The result showed a reduction of 3 logs from the initial population for both KSC and Cincinnati soil samples. Results from other areas are given in graphs.

Reyes, A. L.↗