Search NASA⌕ Search

SEARCH · Search NASA

Results for “SEM data”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Enthalpies of formation of CaAl4O7 and CaAl12O19 (hibonite) by high temperature, alkali borate solution calorimetry

Enthalpies of formation were determined for two calcium aluminate phases, CaAl4O7 and CaAl12O19, using high-temperature alkali borate solution calorimetry. The aluminates were synthesized by multiple-cycle heating and grinding stoichiometric mixtures of CaCO3 and Al2O3, and the products were characteized by X-ray diffraction and SEM microbeam analysis. The data on impurities (CaAl4O7 was found to be about 89.00 percent pure by weight and the CaAl12O19 samples about 91.48 percent pure) were used to correct the heat of solution values of the synthetic products. The enthalpies of formation, at 1063 K, from oxides, were found to be equal to -(25.6 + or - 4.7) kJ/g.f.w. for CaAl4O7 and -(33.0 + or - 9.7) kJ/g.f.w. for CaAl12O19; the respective standard enthalpies of formation from elements, at 298 K, were estimated to be -4007 + or - 5.2 kJ/g.f.w. and -10,722 + or - 12 kJ/g.f.w.

Geiger, C. A.↗
NASA NTRS1992

Vacuum ultraviolet radiation/atomic oxygen synergism in fluorinated ethylene propylene Teflon erosion

A micrographic investigation is reported of samples of the fluorinated ethylene propylene (FEP) Teflon thermal-blanketing materials recovered from the Long-Duration Exposure Facility (LDEF) satellite. The samples are taken from the trailing edge and row 8 which correspond to exposures to vacuum UV (VUV) and VUV + atomic O, respectively. Data are taken from SEM and IR-spectra observations, and the LDEF leading-edge FEP shows a high degree of erosion, roughening, and sharp peaks angled in the direction of the flow of atomic O. The trailing edge sample influenced primarily by VUV shows a hard brittle layer and some cracked mosaic patterns. Comparisons to a reference sample suggest that the brittle layer is related to exposure to VUV and is removed by atomic-O impingement. Polymers that are stable to VUV radiation appear to be more stable in terms of atomic oxygen.

Stiegman, A. E.↗
NASA NTRSDate not supplied

Characterization of Novel Spacecraft Materials aboard the Materials International Space Station Experiment-Flight Facility (Preliminary Results)

This work will encompass the preflight characterization of 15 novel and heritage materials currently under observation on the Materials International Space Station Experiment-Flight Facility (MISSE-FF). MISSE-FF has been upgraded to perform active reflectance measurements of the materials. Images taken in RGB/IR colors are compared to results from an extensive ground testing campaign to obtain quantitative on-orbit material evolution data. Identical materials samples are to be flown on the ram, wake, and zenith faces of MISSE-FF, enabling deconvolution of the energetic electron, proton, atomic oxygen, and ultraviolet damage pathways. Energy deposition from the space environment leads to chemical changes in the material that in turn alter the optical properties. The same chemical damage that manifests as changes in optical reflectance and absorptance also leads to changes in myriad physical properties such as mechanical strength, electrical conductivity, and chemical reactivity. Therefore, flight materials are able to be characterized based on their unique reflectance spectra by comparing on-orbit measurements of optical reflectance with extensive terrestrial experiments, which help to correlate changes in reflectance with respect to changes in other material properties. The MISSE program has been a part of the International Space Station National Laboratory for many years and has been instrumental in understanding space weather modification of material properties. However, MISSE-FF has been limited to passive experiments with only pre/post flight material studies possible. In advance of the MISSE-16 experiment, the flight facility has received a major upgrade to provide daily spectral observations by way of a RGB/IR camera and a tunable light source. The MISSE-16 mission launched in February 2022 and carries 15 material samples for 6 months of the low Earth orbital exposure. Identical materials samples are to be flown on the ram, wake, and zenith faces of MISSE-FF, enabling deconvolution of the energetic electron, proton, atomic oxygen, and ultraviolet damage pathways. This paper discusses the MISSE-16 experiment, highlights the first use of the facility upgrades, and presents results from the extensive preflight material characterization that includes directional hemispherical reflectance, bidirectional reflectance, AFM, SEM, and electrical conductivity. Additionally, data showing the modification of these properties by ground-based exposure to space-like electron and atomic oxygen flux will be discussed. Finally, updates on deployment and initial check-out of the experiment on MISSE-FF will be presented. It is the ultimate goal of this program to provide validation for the development of ground based space weather simulation facilities and techniques.

Ryan Hoffman↗
NASA NTRS1988

Constraints on the origin of Archean trondhjemites based on phase relationships of Nuk gneiss with H2O at 15 kbar

Constraints on the origin of Archean trondhemites were investigated by studying the T-X(H2O) phase relationships, as a function of water content, of the trondhjemitic Nuk gneiss (the principal component of the second phase of Archean igneous activity in the Godthab region, Greenland) with water at 15-kbar pressure. High-pressure experiments were completed in a piston-cylinder apparatus wih samples enclosed in gold capsules, and phase assemblages exposed on polished surfaces of run products and analyzed using optical microscope, SEM, and electron microprobe. The data obtained were found to be consistent with the multistage development model for the Archean crust in Finland, developed by Jahn et al. (1984), which calls for at least three stages of crustal development.

Johnston, A. Dana↗
NASA NTRS1992

Effects of the LDEF environment on the Ag/FEP thermal blankets

This presentation was made by Francois Levadou at the NASA Langley Research Center LDEF materials workshop, November 19-22, 1991. It represents the results to date on the examination of silvered teflon thermal blankets primarily from the Ultra-heavy Cosmic Ray Experiment and also from the blanket from the Park Seed Company experiment. ESA/ESTEC and Boeing conducted a number of independent measurements on the blankets and in particular on the exposed fluorinated ethylene-propylene (FEP) layer of the blankets. Mass loss, thickness, and thickness profile measurements have been used by ESA, Boeing, and NASA LeRC to determine recession and average erosion yield under atomic oxygen exposure. Tensile strength and percent elongation to failure data, surface characterization by ESCA, and SEM images are presented. The Jet Propulsion Laboratory analysis of vacuum radiation effects is also presented. The results obtained by the laboratories mentioned and additional results from the Aerospace Corporation on samples provided by Boeing are quite similar and give confidence in the validity of the data.

Levadou, Francois↗
NASA NTRS1995

Space Experiment Module: A new low-cost capability for education payloads

The Space Experiment Module (SEM) concept is one of a number of education initiatives being pursued by the NASA Shuttle Small Payloads Project (SSPP) in an effort to increase educational access to space by means of Space Shuttle Small Payloads and associated activities. In the SEM concept, NASA will provide small containers ('modules') which can accommodate small zero-gravity experiments designed and constructed by students. A number, (nominally ten), of the modules will then be flown in an existing Get Away Special (GAS) carrier on the Shuttle for a flight of 5 to 10 days. In addition to the module container, the NASA carrier system will provide small amounts of electrical power and a computer system for controlling the operation of the experiments and recording experiment data. This paper describes the proposed SEM carrier system and program approach.

Goldsmith, Theodore C.↗
NASA NTRS2015

Microstructure-Sensitive Investigation of Fracture Using Acoustic Emission Coupled With Electron Microscopy

A novel technique using Scanning Electron Microscopy (SEM) in conjunction with Acoustic Emission (AE) monitoring is proposed to investigate microstructure-sensitive fatigue and fracture of metals. The coupling between quasi in situ microscopy with actual in situ nondestructive evaluation falls into the ICME framework and the idea of quantitative data-driven characterization of material behavior. To validate the use of AE monitoring inside the SEM chamber, Aluminum 2024-B sharp notch specimen were tested both inside and outside the microscope using a small scale mechanical testing device. Subsequently, the same type of specimen was tested inside the SEM chamber. Load data were correlated with both AE information and observations of microcracks around grain boundaries as well as secondary cracks, voids, and slip bands. The preliminary results are in excellent agreement with similar findings at the mesoscale. Extensions of the application of this novel technique are discussed.

Wisner, Brian↗
NASA NTRS2018

Effect of Thin-Film Adhesives on Mode I Interlaminar Fracture Toughness in Carbon Fiber Composites with Shape Memory Alloy Inserts

A single sheet of NiTi shape memory alloy (SMA) was introduced within a unidirectional HexPly® 8552/IM7 (Hexcel®) polymer matrix composite (PMC) panel in conjunction with multiple thin-film adhesives to promote the interfacial bond strength between the SMA and PMC. A double cantilever beam (DCB) test was performed in accordance with the ASTM D5528 method for evaluation of Mode I interlaminar fracture toughness of unidirectional fiber-reinforced PMCs. The modal acoustic emissions (MAEs) were monitored during testing with two acoustic sensors attached to the specimens. The composite panels were subjected to a C-scan before testing and examined using optical and scanning electron microscopy (SEM) techniques after part failure. The data were used in conjunction with modified beam theory (MBT), the compliance calibration (CC) method, and the modified compliance calibration (MCC) method. The Mode I interlaminar toughness (G(sub IC)) values for control specimens were higher than previously reported and are attributed to extensive fiber bridging during testing. The presence of adhesives with SMA inserts stabilized crack propagation during DCB testing. The results reveal a new phenomenon of SMA bridging, whereby crack propagation would switch from one side of the SMA insert to the other, thus increasing the load and G(sub IC) values of specimens containing SMA.

shape memory alloys↗
NASA NTRS1978

Scanning microscopy in microcircuit failure analysis

A three-phase microcircuit failure analysis procedure is presented. In the first phase, the device is nondestructively tested and the data obtained is correlated with the circumstances surrounding the failure event. The device is then subjected to a limited nondestructive analysis dominated by optical and scanning electron microscopy (SEM). Knowing that microcircuits usually fail from manufacturing defects or misuse, the analyst looks for one of the probable mechanisms. The SEM has two special operating modes that provide unique data for nondestructive analysis: voltage contrast and conductive current. These are used with other SEM modes and surface analysis techniques to analyze complicated microcircuits. The last phase includes the destructive procedures. The end product of these analyses is a corrective action that will yield a highly reliable system.

Nicolas, D. P.↗
NASA NTRS1993

The EET87513 clast N: A CM2 fragment in an HED polymict breccia

Xenoliths of material resembling carbonaceous chondrites have been found in several HED polymict breccias. Most workers concluded that these clasts are related to CM2 meteorites on the basis of texture, bulk composition, and mineralogy. Data on clast N, a carbonaceous chondrite fragment from the howardite EET87513 large enough (approximately 4x5mm on the surface of the slab from which it was separated) to extract bulk samples for INAA and oxygen isotope analysis and to provide a thin section for electron microprobe, SEM, and TEM analysis is reported. Preliminary data for this clast were previously reported. INAA was performed at Oregon State University and bulk oxygen isotopic composition was determined at the University of Chicago. These data confirm that EET87513 clast N is a fragment of CM2 material.

Buchanan, P. C.↗
NASA NTRS1984

Petrographic studies of refractory inclusions from the Murchison meteorite

Textural and mineral-chemical data on freeze-thaw disaggregated refractory inclusions from the Murchison meteorite are reported. The data were obtained with neutron activation analysis, SEM, and spectroscopy, the study revealed corundum-bearing inclusions, spinel-hibonite aggregates and spherules, and spinel-pyroxene and elivine-pyroxene inclusions. One of the three spinel-, pyroxene-, forsterite-rich inclusions had an amoeba-shaped spinel-pyroxene core, implying vapor-to-solid condensation and therefore crystallization from a melt. It is concluded that the meteorite formation encompassed diverse nebular materials, and that further studies of the meteorite will enhance the data base on the planetary nebular processes.

Macpherson, G. J.↗
NASA NTRS2005

The Space Shuttle Columbia Accident Investigation and Reconstruction: Two Years Later

The Space Shuttle Columbia was lost during re-entry over two years ago. Since the release of the official materials-related findings in August of 2003, additional testing and analysis of select pieces of debris has continued. Microanalytical techniques, including EMPA, ESCA, and x-ray elemental dot mapping, were employed during the initial investigation; the results related the microstructural characteristics of deposit layers to the breach location in the leading edge of the left wing. Such characteristics included deposition order, composition, and distribution. Subsequent to the original efforts, new analytical data and information, not available at the time of the primary investigation, has been generated. This data was obtained via a low-vacuum SEM, fitted not only with a light-element EDS detector, but an XRF tube as well. Essentially, for elements up to sodium, classic EDS was utilized; above sodium, XRF was used. Predominantly, the elements of interest were aluminum, titanium, chromium, iron, nickel, and copper. The findings of both old and new data are compared, and their application to the overall accident investigation detailed.

McDanels, Steven J.↗
NASA NTRS1994

Shape, size, and distribution of magnetic particles in Bjurbole chondrules

Chondrules from the Bjurbole chondritic meteorite (L4) exhibit saturation remanence magnetization (SIRM) values which vary over three orders of magnitude. REM values (Natural Remanence Magnetization/SIRM) for Allende (C3V) and Chainpur (LL3) are less than 0.01 but in Bjurbole some chondrules were found to have REM values greater than 0.1 with several greater than 0.2. REM values greater than 0.1 are abnormal and cannot be acquired during weak field cooling. If exposure to a strong field (whatever the source) during the chondrules' history is responsible for the high REM values, was such history associated with a different processing which might have resulted in different shape, size, and distribution of metal particles compared to chondrules having REM values of less than 0.01? Furthermore, magnetic hysteresis results show a broad range of magnetic hardness and other intrinsic magnetic properties. These features must be related to (1) size and amount of metal; and (2) properties of, and amount of, tetrataenite in the chondrules (all chondrules thus far subjected to thermomagnetic analysis show the presence of tetrataenite). A scanning electron microscopy (SEM) study is underway to determine the relationship between the shape, size, and distribution of metal particles within individual chondrules and the magnetic properties of these chondrules. Results from the SEM study in conjunction with magnetic property data may also help to discern effects from possible lightning strikes in the nebula prior to incorporation of the chondrules into the parent body.

Nava, David F.↗
NASA NTRS1996

Automated SEM Modal Analysis Applied to the Diogenites

Analysis of volume proportions of minerals, or modal analysis, is routinely accomplished by point counting on an optical microscope, but the process, particularly on brecciated samples such as the diogenite meteorites, is tedious and prone to error by misidentification of very small fragments, which may make up a significant volume of the sample. Precise volume percentage data can be gathered on a scanning electron microscope (SEM) utilizing digital imaging and an energy dispersive spectrometer (EDS). This form of automated phase analysis reduces error, and at the same time provides more information than could be gathered using simple point counting alone, such as particle morphology statistics and chemical analyses. We have previously studied major, minor, and trace-element chemistry of orthopyroxene from a suite of diogenites. This abstract describes the method applied to determine the modes on this same suite of meteorites and the results of that research. The modal abundances thus determined add additional information on the petrogenesis of the diogenites. In addition, low-abundance phases such as spinels were located for further analysis by this method.

Bowman, L. E.↗
NASA NTRS2002

Thermophysical ESEM Characterization of Carbon Fibers

Coefficients of thermal expansion (CTE) of carbon fibers create residual stresses in aggressive manufacturing and service environments. In this effort, environmental scanning electron microscope (ESEM) is used for in situ observations of a carbon fiber cross-section up to 1000 C in order to evaluate the much neglected transverse CTE. The perimeter of fiber cross-section is calculated with the Scion image processing program from images that were taken at every 100 C increments. CTE values are calculated by linear regression of the strain data based on the perimeter changes. Furthermore, through SEM, WDS and TEM observations, we are in the process of bringing an interactive rationale between CTE, crystallinity and surface roughness of carbon fibers.

Sue, Jiwoong↗