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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 415 records · Page 23
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NASA NTRS1976

Petrography of isotopically-dated clasts in the Kapoeta howardite and petrologic constraints on the evolution of its parent body

Results are presented for petrographic and electron microprobe studies of the isotopically dated A, B, C, and rho basaltic rock fragments separated from the howardite Kapoeta. Other lithic clasts and numerous mineral fragments in thin sections of Kapoeta are investigated in order to outline the range in lithology and chemistry of the source materials from which the Kapoeta meteorite is derived. The data obtained are compared to those from other meteorite and lunar samples, with particular reference to the observational consequences for the evolution of the Kapoeta parent body. A major conclusion is that there is no clearcut evidence for young magmatism on the Kapoeta parent body. The observations preclude the interpretation that the Kapoeta is a simple mixture of eucrites and diogenites. In contrast to the moon, a source of anorthositic rocks does not appear to have been present on the Kapoeta parent body which involved chiefly pyroxene. The FeO-MnO relationships suggest that the source of the materials in the Kapoeta parent planet are fundamentally related.

Dymek, R. F.↗
NASA NTRS1976

Crystal growth from the vapour phase (ASTP experiment MA-085)

The positive effects of microgravity on crystal quality and fundamental properties of the vapor transport reaction were established by analyzing the results of three transport experiments on multi-component systems performed during the Apollo Soyuz Test Project (ASTP) mission. The systems employed were GeSe(0.99)Te(0.01) - GeI4 (A), GeS(0.98)Se(0.02) - GeCl4 (B), and GeS - GeCl4-Ar (C). The crystallographic analysis is based on a direct comparison of space and ground-based (prototype) crystals, employing X-ray diffraction, microprobe, microscopic, and chemical etching techniques. The results demonstrate a considerable improvement of the space-grown crystals in terms of chemical and crystalline homogeneity, surface morphology, and bulk perfection relative to ground specimens. The confirmation of greater mass transport rates than predicted for micro-gravity by present vapor transport models is of basic scientific and practical importance for the improvement of transport models and techniques on earth and for the development of a transport model for space conditions. The internal consistency and agreement between ASTP and Skylab results obtained for different compounds, transport agents, and temperature gradients strongly support the validity of these observations. The combined findings of improved crystal quality and high mass transport rates are of technological significance for space-processing applications.

Wiedemeier, H.↗
NASA NTRS1977

Oxidation in oxygen at 900 deg and 1000 deg C of four nickel-base cast superalloys: NASA-TRW VIA, B-1900, alloy 713C, and IN-738

The oxidation at 900 and 1,000 C of four nickel-base superalloys in 1 atmosphere of slowly flowing oxygen was investigated. Thermogravimetric rate data were obtained for periods to 100 hours. The morphology and composition of the oxide scales formed after 100 hours were studied by optical microscopy, X-ray diffraction, electron microprobe, scanning electron microscopy, and X-ray photoelectron spectroscopy (ESCA). Alloys B-1900 and VIA were found to be primarily alumina formers, though probably 25 percent of their surface was covered by CR2O3-containing oxides at 900 C. Alloys 713C and IN-738 were primarily chromia formers, though the surface of 713C at 1,000 C was covered with NiO, and the surface of IN-738 at both temperatures was covered with a thin layer of TiO2.

Fryburg, G. C.↗
NASA NTRS1977

Crystal growth from the vapor phase. Experiment MA-085

The positive effects of microgravity on crystal quality and the fundamental properties of the vapor transport reaction were established by analyzing the results of three transport experiments on multicomponent systems performed during the Apollo-Soyuz Test Project mission. The systems employed were GeSe0.99Te0.01-GeI4(A), GeS0.98Se0.02-GeCl4(B), and GeS-GeCl4-Ar (C). The crystallographic analysis is based on a direct comparison of space and ground-based (prototype) crystals employing X-ray diffraction, microprobe, microscopic, and chemical etching techniques. The results demonstrate a considerable improvement of the space-grown crystals in terms of chemical and crystalline homogeneity, surface morphology, and bulk perfection relative to ground specimens.

Wiedemeier, H.↗
NASA NTRS1977

Surface aspects of pitting and stress corrosion cracking

The pitting and stress corrosion cracking of a stable austenitic stainless steel in aqueous chloride environments were investigated using a secondary ion mass spectrometer as the primary experimental technique. The surface concentration of hydrogen, oxygen, the hydroxide, and chloride ion, magnesium or sodium, chromium and nickel were measured as a function of potential in both aqueous sodium chloride and magnesium chloride environments at room temperature and boiling temperatures. It was found that, under anodic conditions, a sharp increase in the chloride concentration was observed to occur for all environmental conditions. The increase may be associated with the formation of an iron chloride complex. Higher localized chloride concentrations at pits and cracks were also detected with an electron microprobe.

Truhan, J. S., Jr.↗
NASA NTRS1977

Analysis of ablation debris from natural and artificial iron meteorites

Artificial ablation studies were performed on iron and nickel-iron samples using an arc-heated plasma of ionized air. Experiment conditions simulated a meteoroid traveling about 12 km/sec at an altitude of 70 km. The artificially produced fusion crusts and ablation debris show features very similar to natural fusion crusts of the iron meteorites Boguslavka, Norfork, and N'Kandhla and to magnetic spherules recovered from Mn nodules. X-ray diffraction, electron microprobe, optical, and scanning electron microscope analyses reveal that important mineralogical, elemental, and textural changes occur during ablation. Some metal is melted and ablated. The outer margin of the melted rind is oxidized and recrystallizes as a discontinuous crust of magnetite and wustite. Adjacent to the oxidized metallic ablation zone is an unoxidized metallic ablation zone in which structures such as Widmannstatten bands are obliterated as the metal is transformed to unequilibrated alpha 2 nickel-iron. Volatile elements are vaporized and less volatile elements undergo fractionation.

Blanchard, M. B.↗
NASA NTRS1976

High-silica /greater than 60%/ lunar glasses in an Apollo 14 soil sample - Evidence for silicic lunar volcanism

The major-element compositions of 93 low-specific-gravity (less than 2.60) high-silica (greater than 60%) glass particles from a sample of lunar fines (14259,20) were determined by electron microprobe analyses. The size, shape, abundance, mineralogy, and major-element composition of more than 60% of the high-silica glasses is consistent with their being fragments of interstitial glass from mare basalts. However, one group of 30 glasses with between 72% and 78% SiO2 and an average of approximately 2.6% FeO can be distinguished from other high-silica glasses both chemically and petrographically. Glass particles with this composition do not contain crystalline inclusions and are fairly homogeneous not only within a single particle but also from particle to particle. The chemistry and petrology of these glasses suggest that they are not fragments of interstitial glass or shock-melted particles from a 'granitic' source rock. Rather, the homogeneity and lack of crystalline inclusions suggest that this group of high-silica glasses was the product of lunar acidic volcanism.

Glass, B. P.↗
NASA NTRS1976

Use of fractography and sectioning techniques to study fracture mechanisms

Recent investigations of the effect of microstructure on the fracture mechanisms and fracture toughness of steels, aluminum alloys, and titanium alloys have used standard fractographic techniques and a sectioning technique on specimens plastically deformed to various strains up to fracture. The specimens are prepared metallographically for observation in both optical and electron beam instruments. This permits observations to be made about the fracture mechanism as it occurs in thick sections and helps remove speculation from the interpretation of fractographic features. This technique may be used in conjunction with other standard techniques such as extraction replicas and microprobe analyses. Care must be taken to make sure that the microstructural features which are observed to play a role in the fracture process using the sectioning technique can be identified with fractography.

Van Stone, R. H.↗
NASA NTRS1977

Redetermination of the Fe-rich portion of the Fe-Ni-Co phase diagram

The iron rich portion of the Fe-Ni-Co ternary diagram was determined at four temperatures. The phase boundaries and tie-lines of the (alpha + gamma) phase field were measured by analyzing the alpha and gamma phases with an electron microprobe. Grain boundary allotrimorphs of the alpha phase were observed in the polished and etched sections of samples which were step cooled from the gamma phase into the (alpha + gamma) region. Widmanstaetten-type microstructures composed of gamma-precipitates were observed in samples which were directly heated from room temperature into the (alpha + gamma) region.

Widge, S.↗
NASA NTRS1977

The Del Rio ataxite, Texas

Basic data are presented on the Del Rio, Nordheim, and Monahans ataxites found in Texas. Results are reported for bulk-chemistry analysis, metallographic observations, and electron-microprobe analysis of the Del Rio meteorite. It is shown that Del Rio is distinctly different from the other two ataxites in terms of nickel, phosphorous, and carbon content, and is composed of at least three coarse grains in different crystallographic orientations. All the kamacite in Del Rio is found to have transformation structures that are probable shock products, and minor inclusions of daubreelite, schreibersite, and troilite are observed. It is concluded that Del Rio was apparently mildly shocked prior to its fall.

Henderson, E. P.↗
NASA NTRS1976

The Apollo 16 drill core - Modal petrology and characterization of the mineral and lithic component

A string of 59 polished thin sections covering the length of the Apollo 16 deep drill core has been examined. A modal analysis, involving the optical classification of 116,000 points was made, and over 500 mineral and lithic fragments from the core were chemically analyzed using an electron microprobe. These data were used to identify and characterize the source areas of the core material and to reconstruct the accumulation history of the core.

Vaniman, D. T.↗
NASA NTRS1976

Drive tube 60009 - A chemical study of magnetic separates of size fractions from five strata

Each bulk soil and both the magnetic and nonmagnetic components of the 90-150 micron and below 20 micron fractions of five soils from drive tube 60009 were analyzed. Samples were analyzed for FeO, Na2O, Sc, Cr, Co, Ni, Hf, Ta, Th, La, Ce, Sm, Eu, Tb, Yb, and Lu by neutron activation analysis. Several samples were fused and analyzed for major elements by electron microprobe analysis. Compositional variations are not systematically related to depth. The compositions of the five soils studied are well explained by a two-component mixing model whose end members are a submature Apollo 16-type soil and an extremely immature anorthositic material similar to 60025. There is evidence that the anorthositic component had received a small amount of exposure before these soils were mixed. After mixing, the soils received little exposure suggesting mixing and deposition on a rapid time scale.

Blanchard, D. P.↗
NASA NTRS1976

Carbides in lunar soils and rocks

Carbides and the surrounding metal of eight particles from Apollo 14, 16, and 17 soils were analyzed for C, Fe, Ni, and Co with the electron microprobe. In addition, carbide-containing metal particles in two Apollo 17 rocks were studied. Carbide-metal assemblages were found in anorthositic hornfels, melt rock, and agglutinate, but not in any primary igneous rocks. Carbon measurements show that cohenite is the carbide phase present in all the samples. Cohenite exsolves from the carbon-rich metal phase during cooling of the lunar metal particle in the host rocks or soil fragments. Measurements of two-phase interface compositions indicate equilibration for carbides and metal during cooling below 600 C and possibly below 500 C.

Goldstein, J. I.↗
NASA NTRS1976

Metal spherules in Wabar, Monturaqui, and Henbury impactites

The Fe, Ni, and Co contents of 450 spherules with diameters of 3 to 100 microns in impact glasses from three terrestrial meteorite craters are determined by electron microprobe analysis. The objects investigated include 250 spherules from Wabar (Saudi Arabia) impactite and 100 each from Monturaqui (Chile) and Henbury (Australia) impactites. The specimens and spherules are described, noting that the Wabar and Henbury craters were produced in sandstone while the Monturaqui crater was formed in siliceous igneous rocks and has an enigmatic sulfide abundance. It is found that the spherules are enriched in Ni and Co relative to the original meteorite Fe content and are enriched in Ni relative to Co for Ni contents greater than 50%. The results indicate that, on the average, Henbury spherules are more Ni-enriched than Monturaqui spherules, and Wabar spherules exhibit the least Ni-enrichment. It is suggested that the spherules could have formed without experiencing free flight and that instantaneous dissemination of meteoritic material at the meteorite-target contact was the major fractionation process.

Gibbons, R. V.↗
NASA NTRS1976

Shock metamorphic effects in lunar microcraters

Detailed petrographic descriptions and results of electron microprobe analyses are presented for impact glasses as well as shocked and unshocked minerals associated with individual lunar microcraters (diameters of 0.4 to 4.4 mm). Rocks of four typical lunar lithologies are studied: anorthosite, anorthositic norite, ophitic basalt, and polymict breccia. Textures, mineralogies, and chemical compositions are examined along a radial traverse through each microcrater; i.e., across the impact glasses lining the crater wall, the shock-metamorphosed zone immediately underlying the glass liner, and the unshocked host rock. The microcraters are discussed in a sequence of increasing mineralogical complexity of the host rock (from anorthosite to polymict breccia) in order to distinguish shock effects among mineral types. The shock metamorphic features observed are found to be comparable to those reported in shocked basalt from Lonar Crater, India, and are categorized into five shock-intensity classes with pressures experimentally calibrated.

Schaal, R. B.↗
NASA NTRS1976

Composition and origin of Luna 16 aluminous mare basalts

The mineralogy and petrology of 58 lithic fragments, 52 of which are basaltic, in the Luna 16 samples were studied, with textures, and mineral and bulk compositions determined by petrographic and electron microprobe techniques. These mare basalt fragments differ from other mare basalts in being aluminous (11-20%) which results in plagioclase and (olivine) microphenocrysts; moreover, they have very low-FeO and MgO and high-CaO, FeO/MgO, and normative diopside contents.

Kurat, G.↗
NASA NTRS1976

Compositional interrelationships of mare basalts from bulk chemical and melt inclusion studies

Petrographic and electron microprobe data (355 new analyses) are presented on melt inclusions and their host phases found in a reexamination of the Apollo thin section collection. In addition, occurrences of early armalcolite and ilmenite are described and new data are presented on quench-pyroxene compositions and melt inclusions in chromian ulvospinel. Compositional differences between mare basalt types and their melt inclusions are illustrated with plots of compositions normalized to a terrestrial lava composition, that of the 1965 Makaopuhi lava lake. The plots emphasize the fact that mare basalts are not significantly differentiated relative to the compositions that are possible as defined by the melt inclusion data. Distribution coefficients for Fe and Mg partitioning between trapped melt and host olivine and ilmenite are calculated and show a range about probable equilibrium values. It is suggested that the crystallization sequence olivine-ilmenite-plagioclase-pyroxene defined by the melt inclusion data may be the actual sequence which obtained generally for Apollo 11 and 17 mare basalts just prior to eruption.

Weiblen, P. W.↗
NASA NTRS1976

Meteorite-free Apollo 15 crystalline KREEP

Electron microprobe and petrographic analyses of an Apollo 15 sample, 15382, from the Apennine Front, have revealed KREEP chemistry and very low concentrations of the characteristic meteorite siderophile elements: Ir, Os, Re, Au, and Ni. It is a crystalline basalt, practically identical in texture and mineral zoning patterns to other lunar high-alumina basalts.

Dowty, S.↗