FEP plug protects H2 masers
Lifetime of hydrogen-maser bulb is increased by replacing beam stop plate with thick fluorinated ethylene-propylene (FEP) plug inserted in hole opposite beam entrance stem of bulb.
Deluca, J. J.↗
SEARCH · Engineering Papers
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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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VUV-induced degradation of FEP Teflon aboard LDEF
Examination of fluorinated ethylene propylene (FEP) copolymer materials recovered from the Long Duration Exposure Facility (LDEF) reveals differing damage characteristics on leading edge (ram-facing) versus trailing edge (wake-facing surfaces). Silver/Teflon (Ag/FEP) thermal control materials on ram facing surfaces of the LDEF exhibited obvious degradation, with an apparent increase in diffuse light scattering, whereas identical materials on the wake facing surfaces showed little apparent damage with cursory inspection. Microscopic examination of both types of surfaces reveals the nature and extent of environment induced degradation of materials. The ram facing surfaces were clearly eroded by atomic oxygen impingement, while the wake facing material developed a thin, highly embrittled surface layer.
Brinza, David E.↗
An analysis of LDEF-exposed silvered FEP teflon thermal blanket material
The characterization of selected silvered fluorinated ethylene propylene (FEP) teflon thermal blanket material which received 5 years and 9 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. X-ray photoelectron spectroscopy, infrared, and thermal analyses did not detect a significant change at the molecular level as the result of this exposure. However, various microscopic analyses revealed a roughening of the coating surface due to atomic oxygen erosion which resulted in some materials changing from specular reflectors of visible radiation to diffuse reflectors. The potential effect of silicon-containing molecular contamination on these materials is addressed.
Young, Philip R.↗
Recession of FEP specimens from trays D11 and B7
We report work done at Boeing Defense and Space Group on analysis of silvered teflon specimens taken from selected locations of the Long Duration Exposure Facility under support from a contract provided by NASA LaRC. The samples discussed in this presentation were taken from the unexposed side of D11 and extended through the folded area of this blanket into the exposed area. Two similar areas were cut from blanket B7, one from the edge of the blanket near row six and one from the edge of the blanket near row eight and within a few centimeters of the copper grounding strap for B7. The specimens were each divided into three sections by cutting with a scapel. Two of the sections were mounted in a potting compound, which was cut and polished such that the cross-sectional thickness of each was exposed. One piece was mounted straight and the other was mounted in an attempt to configure the specimens such that it was bent with a radius of curvature similar to the on-orbit configuration. The third portion of each specimen was used for SEM images to help define the angle of exposure with respect to the ram at each location on the specimen. Photomicrographs were taken in cross section from the edge of the blanket through the curved transition region into the exposed area of the blanket. The thickness of the Fluorinated Ethylene Propylene (FEP) layer was determined at known distances from the edge of the blanket. SEM images were obtained at known distances to help define the angle with respect to ram and therefore establish the atomic oxygen fluence on each location and correlate this exposure with thickness. Thickness measurements made with a two to three centimeter distance minimized the uncertainty arising from variations in the as-manufactured thickness of each blanket. The nominal angle from ram of the exposed portion of each blanket, and the fact that the unexposed edge portions are approximately at right angles to the exposed portion were also used to help define the angles. Thickness measurements were taken at specified locations. An average thickness for the unexposed portion of the blanket was determined. Changes in thickness were then determined by difference.
Pippin, H. Gary↗
Ground-based simulation of LEO environment: Investigations of a select LDEF material: FEP Teflon (trademark)
The Long Duration Exposure Facility (LDEF) has produced a wealth of data on materials degradation in the low earth orbit (LEO) space environment and has conclusively shown that surface chemistry (as opposed to surface physics-sputtering) is the key to understanding and predicting the degradation of materials in the LEO environment. It is also clear that materials degradation and spacecraft contamination are closely linked and that the fundamental mechanisms responsible for this linking are in general not well understood especially in the area of synergistic effects. The study of the fundamental mechanisms underlying materials degradation in LEO is hampered by the fact that the degradation process itself is not observed during the actual exposure to the environment. Rather the aftermath of the degradation process is studied, i.e., the material that remains after exposure is observed and mechanisms are proposed to explain the observed results. The EOIM-3 flight experiment is an attempt to bring sophisticated diagnostic equipment into the space environment and monitor the degradation process in real time through the use of mass spectrometry. More experiments of this nature which would include surface sensitive diagnostics (Auger and photoelectron spectroscopes) are needed to truly unravel the basic chemical mechanisms involved in the materials degradation process. Since these in-space capabilities will most likely not be available in the near future, ground-based LEO simulation facilities employing sophisticated diagnostics are needed to further advance the basic understanding of the materials degradation mechanisms. The LEO simulation facility developed at Los Alamos National Laboratory has been used to investigate the atomic oxygen/vacuum ultraviolet (AO/VUV) enhanced degradation of FEP Teflon. The results show that photo-ejection of polymer fragments occur at elevated temperature (200 C), that VUV synergistic rare gas sputtering of polymer fragments occur even at 25 C, and that combined OA/VUV interaction produces a wide variety of gas phase reaction products.
Cross, Jon B.↗
Materials Data on Eu(FeP)2 by Materials Project
EuFe2P2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All Eu–P bond lengths are 3.13 Å. Fe2+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing FeP4 tetrahedra. All Fe–P bond lengths are 2.20 Å. P3- is bonded in a 4-coordinate geometry to four equivalent Eu2+ and four equivalent Fe2+ atoms.
36 MATERIALS SCIENCE↗
Materials Data on Ba(FeP)2 by Materials Project
BaFe2P2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba2+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All Ba–P bond lengths are 3.36 Å. Fe2+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing FeP4 tetrahedra. All Fe–P bond lengths are 2.21 Å. P3- is bonded in a 4-coordinate geometry to four equivalent Ba2+ and four equivalent Fe2+ atoms.
36 MATERIALS SCIENCE↗
Materials Data on Ca(FeP)2 by Materials Project
CaFe2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca2+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All Ca–P bond lengths are 3.05 Å. Fe2+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing FeP4 tetrahedra. All Fe–P bond lengths are 2.20 Å. P3- is bonded in a 4-coordinate geometry to four equivalent Ca2+ and four equivalent Fe2+ atoms.
36 MATERIALS SCIENCE↗
Materials Data on La(FeP)2 by Materials Project
LaFe2P2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. La2+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All La–P bond lengths are 3.16 Å. Fe2+ is bonded to four equivalent P3- atoms to form a mixture of corner and edge-sharing FeP4 tetrahedra. All Fe–P bond lengths are 2.20 Å. P3- is bonded in a 4-coordinate geometry to four equivalent La2+ and four equivalent Fe2+ atoms.
36 MATERIALS SCIENCE↗
Materials Data on Ce(FeP)2 by Materials Project
CeFe2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight equivalent Fe and eight equivalent P atoms. All Ce–Fe bond lengths are 3.18 Å. All Ce–P bond lengths are 3.06 Å. Fe is bonded to four equivalent Ce and four equivalent P atoms to form a mixture of distorted face, edge, and corner-sharing FeCe4P4 tetrahedra. All Fe–P bond lengths are 2.20 Å. P is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Fe atoms.
36 MATERIALS SCIENCE↗
Materials Data on FeP(H2O3)2 by Materials Project
Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
36 MATERIALS SCIENCE↗
Materials Data on FeP(H2O3)2 by Materials Project
Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
36 MATERIALS SCIENCE↗
Materials Data on FePS by Materials Project
FeSP is Spinel-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Fe3+ is bonded to three equivalent P1- and three equivalent S2- atoms to form FeP3S3 octahedra that share corners with eight equivalent FeP3S3 octahedra, corners with three equivalent PFe3S tetrahedra, corners with three equivalent SFe3P tetrahedra, and edges with two equivalent FeP3S3 octahedra. The corner-sharing octahedra tilt angles range from 54–62°. There are one shorter (2.28 Å) and two longer (2.30 Å) Fe–P bond lengths. There are two shorter (2.20 Å) and one longer (2.21 Å) Fe–S bond lengths. P1- is bonded to three equivalent Fe3+ and one S2- atom to form PFe3S tetrahedra that share corners with three equivalent FeP3S3 octahedra, corners with four equivalent PFe3S tetrahedra, corners with nine equivalent SFe3P tetrahedra, and an edgeedge with one PFe3S tetrahedra. The corner-sharing octahedra tilt angles range from 68–72°. The P–S bond length is 2.25 Å. S2- is bonded to three equivalent Fe3+ and one P1- atom to form SFe3P tetrahedra that share corners with three equivalent FeP3S3 octahedra, corners with four equivalent SFe3P tetrahedra, corners with nine equivalent PFe3S tetrahedra, and an edgeedge with one SFe3P tetrahedra. The corner-sharing octahedra tilt angles range from 75–77°.
36 MATERIALS SCIENCE↗
Materials Data on FeP(HO2)2 by Materials Project
FeH2PO4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four hydrogen molecules and one FeHPO4 framework. In the FeHPO4 framework, Fe3+ is bonded to one H and four O2- atoms to form distorted FeHO4 trigonal bipyramids that share corners with four equivalent PO4 tetrahedra. The Fe–H bond length is 1.62 Å. There are a spread of Fe–O bond distances ranging from 1.89–1.92 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent FeHO4 trigonal bipyramids. There is one shorter (1.53 Å) and three longer (1.55 Å) P–O bond length. H is bonded in a distorted single-bond geometry to one Fe3+ atom. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe3+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Fe3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Fe3+ and one P5+ atom.
36 MATERIALS SCIENCE↗
Self-adaptive FeP@C nanocages for reversible and long-term lithium-ion batteries
Abstract not provided
Zhou, Peng↗
Lattice dynamics in the double-helix antiferromagnet FeP
Not Available
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Emergent Magnetic Phases in Pressure-Tuned van der Waals Antiferromagnet FePS 3
Not Available
2-dimensional systems↗
Results of Re-evaluation of FEPs Related to Implementing the ABD Glass Program
The Savannah River Site plans to reprocess defense spent nuclear fuel currently stored in their L-Basin via the Accelerated Basin Deinventory (ABD) Program. The previous plan for the L-Basin spent nuclear fuel was to dispose of it directly in the federal repository without reprocessing. Implementing the ABD Program will result in final disposal of approximately 900 fewer canisters of defense spent nuclear fuel and the production of approximately 521 more canisters of vitrified high-level waste glass with some specific differences from the planned high-level waste glass. Because the 235U in the L-Basin spent nuclear fuel is not intended to be recovered, the fissile mass loading of the vitrified high-level glass waste form to be produced must be increased above the current value of 897 g/m 3 to a maximum of 2,500 g/m 3 . Therefore, implementing the ABD Program would produce a variant of high-level waste glass—the ABD glass—that needs to be evaluated for future repository licensing, which includes both preclosure safety and postclosure performance. This report describes the approach to and summarizes the results of an evaluation of the potential effects of implementing the ABD Program at the Savannah River Site on the technical basis for future repository licensing for a generic repository that is similar to Yucca Mountain and for one that is fully generic. This evaluation includes the effects on preclosure safety analyses and postclosure performance assessment for both repository settings. The license application for the proposed Yucca Mountain repository (DOE 2008), which is serving as a framework for this evaluation, concluded that the proposed Yucca Mountain repository would meet all applicable regulatory requirements. The evaluation documented in this report found that implementing the ABD Program is not expected to change that conclusion for a generic repository similar to Yucca Mountain or for a generic repository with respect to the preclosure safety analyses. With respect to the postclosure performance of a generic repository, no concerns were identified.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗