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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Particle impact and optical property analysis of the surfaces of Surveyor 3 materials

As part of the investigation of Surveyor 3 materials, a study was conducted to determine the effect of the lunar environment on some of the painted and unpainted exterior surfaces. Examination of the camera parts and tube sections was conducted using three techniques: (1) optical and scanning electron microscopy, (2) energy dispersive X-ray probe analysis, and (3) spectral reflectance measurements.

Anderson, D. L.↗
NASA NTRS1971

Methods of analyzing microsize particulate aerosols and contaminants.

Methods for analyzing atmospheric aerosols and particulate contaminants from natural and industrial sources are briefly described. Their development was spurred by interest in cosmic dust investigations. These methods make it possible to analyze individual particles ranging in size from 0.01 to 1000 microns for elemental and mineralogical content. The described methods include transmission electron microscopy, scanning electron microscopy, electron probe microanalysis, X-ray diffraction, optical mineralogy, and density measurement.

Blanchard, M. B.↗
NASA NTRS1974

Equilibria bearing on the behavior of titanate phases during crystallization of iron silicate melts under strongly reducing conditions

Titanate phase relations at liquidus temperatures are determined for the CaAl2Si2O8-Fe2TiO4-FeTi2O5 system in contact with metallic iron by reflected- and transmitted-light microscopy, electron microprobe, and X-ray diffraction analyses. Results of critical equilibration runs are presented, various primary phase areas and liquidus isotherms are illustrated, and the geometry of the system is described. Three piercing points are determined, and it is noted that the compositional interrelations among coexisting crystalline and liquid phases as well as the sequence of the various titanate phases are indicative of the significant effects of the various cations on the relative stability of these phases. It is found that Al2O3 exerts a strong stabilizing effect on the phase assemblage of ulvospinel plus ferropseudobrookite relative to ilemite.

Lipin, B. R.↗
NASA NTRS2026

Thermal Inspection for the Assessment of Adhesively Bonded Metal Adherents

Certification of adhesively bonded structures is currently a challenge for aircraft manufacturers. The ability to certify bonds in primary structure can reduce dependence on fasteners and this will enable more efficient manufacturing. For example, drilling holes and installing fasteners in bonded joints can be a potentially significant bottleneck in airframe manufacturing. In addition, fasteners increase the airframe weight and can add stress concentration areas. Reducing fastener count can accelerate manufacturing and improve aircraft performance. NASA is currently investigating nondestructive evaluation (NDE) techniques to assess bond integrity. For example, bond thickness influences bond strength and therefore NDE techniques are being investigated to determine bond thickness. For bonded metal structures, there is a large difference in the thermal diffusivity between the 7075 aluminum alloy metal adherends and aircraft grade adhesive. Multi-layered thermal models show a large variation in the thermal response for bondline adhesive thicknesses that vary from 100 to 300 microns for adherend thicknesses of 0.163 cm. Experimental through-transmission thermal measurements reveal promise to quantitatively characterize the bondline thickness. Results were validated with X-ray computed tomography and optical microscopy measurements, and influence of porosity on the thermal model and measurements are investigated.

bondline thickness↗
NASA NTRS2026

Thermal Inspection for the Assessment of Adhesively Bonded Metal Adherends

Certification of adhesively bonded structures is currently a challenge for aircraft manufacturers. The ability to certify bonds in primary structure can reduce dependence on fasteners and this will enable more efficient manufacturing. For example, drilling holes and installing fasteners in bonded joints can be a potentially significant bottleneck in airframe manufacturing. In addition, fasteners increase the airframe weight and can add stress concentration areas. Reducing fastener count can accelerate manufacturing and improve aircraft performance. NASA is currently investigating nondestructive evaluation (NDE) techniques to assess bond integrity. For example, bond thickness influences bond strength and therefore NDE techniques are being investigated to determine bond thickness. For bonded metal structures, there is a large difference in the thermal diffusivity between the 7075 aluminum alloy metal adherends and aircraft grade adhesive. Multi-layered thermal models show a large variation in the thermal response for bondline adhesive thicknesses that vary from 100 to 300 microns for adherend thicknesses of 0.163 cm. Experimental through-transmission thermal measurements reveal promise to quantitatively characterize the bondline thickness. Results were validated with X-ray computed tomography and optical microscopy measurements, and influence of porosity on the thermal model and measurements are investigated.

X-ray computed tomography↗
NASA NTRS1971

Morphology of poly-p-xylylene crystallized during polymerization.

The morphology of as-polymerized poly-p-xylylene grown between -17 and 30 C is found to consist of lame llar alpha crystals oriented with the (010) plane parallel to the support surface. The crystallinity decreases with decreasing polymerization temperature. Spherulitic and nonspherulitic portions of the polymer film consist of folded chain lamellas with the chain axis parallel to the support surface. The results were obtained by small- and wide-angle X-ray measurements, electron and optical microscopy, and differential thermal analysis.

Kubo, S.↗
NASA NTRS1972

Quantitative micro-luminescence and related studies of fine and/or glassy lunar surface materials

Papers on Raman and soft X-ray spectroscopy of lunar glasses and electron microscopy of lunar fines are presented. Individual particles of glasses from Apollo 11, 12, 14, and 15 samples were analyzed separately. Silicon emission shifts vary between parent rock types and can be interpreted as a range of Si-O distances from 1.612 to 1.637 A. Aluminum emission shifts relate to the amount of 4- and 6-coordinated Al in the glass. Raman spectra show broadened bands. Certain bands recur in many specimens and relate to the main normative minerals for the glass bulk composition, olivine, pyroxene, and anorthite. Quantitative size and shape analyses were carried out on six Apollo 14 and 15 samples of fines by computer evaluation of scanning electron microspace images. For the size range of 0.50 to 30 micron diameter, the distributions are log-normal on a number count basis. Aspect ratios range from 0.1 to 1.0 with an average value of about 0.6. The aspect ratios and a shape complexity factor vary only slightly among the samples.

Roy, R.↗
NASA NTRS1947

Changes Found on Run-In and Scuffed Surfaces of Steel Chrome Plate, and Cast Iron

A study was made of run-in and scuffed steel, chrome-plate, and cast-iron surfaces. X-ray and electron diffraction techniques, micro-hardness determinations, and microscopy were used. Surface changes varied and were found to include three classes: chemical reaction, hardening, and crystallite-size alteration. The principal chemical reactions were oxidation and carburization.

IRON, CAST - WEAR RESISTANCE↗
NASA NTRS1972

Investigation of the plastic fracture of high strength steels

This investigation deals in detail with the three recognized stages of plastic fracture in high strength steels, namely, void initiation, void growth, and void coalescence. The particular steels under investigation include plates from both commercial purity and high purity heats of AISI 4340 and 18 Ni, 200 grade maraging steels. A scanning electron microscope equipped with an X-ray energy dispersive analyzer, together with observations made using light microscopy, revealed methods of improving the resistance of high strength steels to plastic fracture.

Cox, T. B.↗
NASA NTRS1973

Shock history of mesosiderites.

The (still largely incomplete) shock histories of 18 stony-iron meteorites (classified as mesosiderites) are studied. The crystallographic character of kamacite in each (polished and etched) sample was determined by a back-reflection X-ray diffraction technique. All specimens were studied metallographically, and some by reflected light microscopy. The shock history of each sample is determined in kbar.

Jain, A. V.↗
NASA NTRS1971

Stress corrosion in titanium alloys and other metallic materials

Multiple physical and chemical techniques including mass spectroscopy, atomic absorption spectroscopy, gas chromatography, electron microscopy, optical microscopy, electronic spectroscopy for chemical analysis (ESCA), infrared spectroscopy, nuclear magnetic resonance (NMR), X-ray analysis, conductivity, and isotopic labeling were used in investigating the atomic interactions between organic environments and titanium and titanium oxide surfaces. Key anhydrous environments studied included alcohols, which contain hydrogen; carbon tetrachloride, which does not contain hydrogen; and mixtures of alcohols and halocarbons. Effects of dissolved salts in alcohols were also studied. This program emphasized experiments designed to delineate the conditions necessary rather than sufficient for initiation processes and for propagation processes in Ti SCC.

Harkins, C. G.↗
NASA NTRS2026

Thermochemical Stability of Ca2Yb8(SiO4)6O2 Apatite in Presence of Molten Calcium-Magnesium-Aluminosilicate (CMAS)

Thermochemical stability of ytterbium silicon oxyapatite Ca 2 Yb 8 (SiO 4 ) 6 O 2 (CYbS) in the presence of molten calcium-magnesium aluminosilicate (CMAS) has been investigated at elevated temperatures for consideration as a thermal and environmental barrier coating (T/EBC) material. CYbS apatite powder was synthesized from the constituent oxides via a solid-state reaction method. Hot-pressed apatite substrates were exposed to molten CMAS at 1200, 1300, and 1400 °C for 1, 10, and 50 h. Development of phases in the interaction region of the heat-treated specimens was monitored using scanning electron microscopy, transmission electron microscopy, high-angle annular dark-field imaging, selected area electron diffraction, and energy dispersive x-ray spectroscopy. Monoclinic cyclosilicate Ca 3 Yb 2 (Si 3 O 9 ) 2 formed from interaction of CYbS apatite with CaO in the CMAS melt at the apatite-CMAS reaction front and continued to nucleate and grow within the residual CMAS in diffusion couples annealed for 1 to 50 h at 1200 °C as well as in those heat treated at 1300 °C for 1 h. Residual CMAS was depleted of Ca when cyclosilicate was present. Dendritic wollastonite (CaSiO3) was observed within the residual CMAS in couples annealed at 1200 and 1300 °C. Ingress of molten CMAS, because of its exponential decrease in viscosity, occurred through open pores and along the grain boundaries of the apatite substrates without any detectable chemical reaction at 1300 and 1400 °C. Results of this study indicate that Ca 2 Yb 8 (SiO 4 ) 6 O 2 apatite has the potential to mitigate the CMAS corrosion up to about 1200 °C but not at higher temperatures.

Narottam P Bansal↗
NASA NTRS1974

Study of recrystallization and devitrification of lunar glass

The technique of differential thermal analysis (DTA) was applied to the study of the Apollo 17 orange soil (74220,63) and the Apollo 16 glass coated anorthite (64455,21). These glasses show accentuated exotherms of strain relief in the annealing range which is indicative of rapid cooling. These are amenable to interpretation by comparison to the known history of synthetic glasses. Synthetic glasses were prepared whose similarity in behavior between the lunar glasses and their synthetic analogs is striking. Approximate rates of cooling of the lunar glasses were determined from comparative DTA of lunar and synthetic glasses and from the determination of the relation of strain relief in the annealing range to quench rate. At higher temperatures the glasses show exotherms of crystallization. The crystallization products associated with the exothermic reactions have been identified by X-ray diffraction and the surface morphologies developed by strain relief and crystallization have been characterized with scanning electron microscopy.

Ulrich, D. R.↗
NASA NTRS1974

Surface topographical effects on the structural growth of thick sputtered metal and alloy coatings

Thick sputtered S-Monel, silver, and 304 stainless steel coatings were deposited on mica and metal substrates with various surface finishes to investigate the structural growth of the coating by scanning electron microscopy. The geometry and the surface structure of the nodules are characterized. Compositional changes within the coating were analyzed by X-ray dispersion miscroscopy. Defects in the surface finish act as preferential nucleation sites and form isolated and complex nodules and various surface overgrowths in the coating. The nodule boundaries are very vulnerable to chemical etching, and these nodules do not disappear after full annealing. Further, they have undesirable effects on mechanical properties; cracks are initiated at the nodules when the coating is stressed by mechanical forces.

Spalvins, T.↗
NASA NTRS1974

Nodular growth in thick-sputtered metallic coatings

Thick-sputtered S-Monel, silver, and 304 stainless steel coatings were deposited on mica and metal substrates with various surface finishes to investigate the nodular growth in the coating by scanning electron microscopy. The geometry and the surface structure of the nodules are characterized. Compositional changes within the coating were analyzed by energy dispersive X-ray analysis. Defects in the surface finish (i.e., scratches, inclusions, etc.), act as preferential nucleation sites and form isolated and complex nodules and various surface overgrowths in the coating. The nodule boundaries are very vulnerable to chemical etching and these nodules do not disappear after full annealing. Further, they have undesirable effects on mechanical properties; cracks are initiated at the nodules when the coating is stressed by mechanical forces. These effects are illustrated by micrographs. Nodular growth within a coating can be minimized or eliminated by increasing the surface smoothness.

Spalvins, T.↗
NASA NTRS1971

Electron microscopy and diffraction of layered, superconducting intercalation complexes.

Several layered, transition metal dichalcogenide intercalation complexes with unique superconducting properties have been examined by high-resolution electron microscopy and electron diffraction. Details of the crystalline lattice and of the lattice imperfections have been directly resolved. The results can be correlated with the available X-ray diffraction and chemical data, and they confirm and extend the postulated models.

Fernandez-Moran, H.↗
NASA NTRS1973

An exploratory study of the microstructure of mullite fibers

Mullite fibers of three compositions, ranging from SiO2-rich to Al2O3-rich, were investigated by a number of transmission electron microscopy (TEM) techniques. The fibers were examined in the as-received condition and after subjecting them to thermal exposures as high as 142 C. The investigative techniques used included direct TEM of microtomed sections of mounted fibers and TEM of replicas of polished, chemically etched, and cathodically etched fibers. In addition, X-ray diffraction line broadening analyses was used for determining average crystallite size. A preliminary description of the microstructure of mullite fibers is given.

Santoro, G. J.↗