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DOE OSTI2021

Potential Dependent Mn Oxidation and Its Role in Passivation of Ni 38 Fe 20 Cr 22 Mn 10 Co 10 Multi-Principal Element Alloy Using Multi-Element Resolved Atomic Emission Spectroelectrochemistry

The identity of passivating oxides on multi-principal element alloys is of great interest as their optimization offers the potential for exceptional corrosion resistance in aqueous solutions over a broad range of potential and pH. This study focuses on a non-equiatomic Ni 38 Fe 20 Cr 22 Mn 10 Co 10 solid solution alloy and tracks the fate of each alloying element during linear sweep voltammetry, low and intermediate potential holds in the passive potential domain as well as during open circuit relaxation after anodic polarization in slightly acidified Cl − solution. Ni dissolves at all potentials investigated in this work, Fe and Co are incorporated into oxides or hydroxides in low concentrations whilst Cr and Mn are enriched at passive potentials. At low passivating potentials, Mn(II) dissolves and is incorporated in minor amounts in oxides containing large concentrations of Cr(III). Considerable enrichment in Mn(II)-species occurs relative to Cr(III) in the oxide at 0.1 V vs SCE. Electrochemical impedance spectroscopy suggests the presence of layered oxides with marginal passivation at high Mn(II) levels. The formation of these oxides depends on a combination of thermodynamic and kinetic factors as well as the sequence of passivation.

Han, Junsoo (ORCID:0000000192952954)↗

DOE OSTI2020

Aqueous passivation of multi-principal element alloy Ni 38 Fe 20 Cr 22 Mn 10 Co 10 : Unexpected high Cr enrichment within the passive film

The aqueous passivation of a non-equiatomic Ni 38 Fe 20 Cr 22 Mn 10 Co 10 - at.% (Ni 40 Fe 20 Cr 20 Mn 10 Co 10 - wt.%) multi-principal element alloy (MPEA) was investigated in 0.1 M NaCl at pH 4 and compared to a conventional binary Ni 76 Cr 24 – at.% (Ni 78 Cr 22 – wt.%) alloy. The electrochemical behavior and oxide film characteristics were explored utilizing in-situ electrochemical and ex-situ surface-sensitive techniques. The passive film composition, thickness, and elemental valence states, as well as, the fate of each element were studied by in-situ atomic emission spectro-electrochemistry, ex-situ X-ray photoelectron spectroscopy, and atom probe tomography. The Ni 38 Fe 20 Cr 22 Mn 10 Co 10 MPEA demonstrated slightly better corrosion resistance compared to the binary Ni 76 Cr 24 , alloy. Passive films on the MPEA contained primarily Cr, and small amounts of Ni, Fe, Co and Mn, while dissolution of Ni, Fe, Co was observed. Ni 0 was enriched at the oxide/metal interface while Cr was depleted. Enrichment of Cr in the passive film occurred to a greater extent in the MPEA than for the Ni-Cr binary alloy. As a result, enrichment factors were determined and the origins of enrichment are discussed.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Efficient Modeling of Structural, Electronic, and Optical Properties of Silver and Gold Metal Nanoclusters and Alloys Using Optimized SCC-DFTB Parameters

Computation of optical properties using conventional time-dependent density functional theory (TD-DFT) is time-consuming and memory-intensive. In this study, we investigate the accuracy and efficiency of the density functional tight binding (DFTB) framework with newly optimized Slater–Koster (SK) parameters for modeling the structural, electronic properties, and absorption spectra of silver and gold nanoclusters and their alloys. Our investigation of the ground state (GS) properties demonstrates that the newly developed GS-SK parameters enable DFTB to closely approximate DFT-calculated bond lengths for octahedron, tetrahedron, icosahedra, and truncated octahedron with sizes Ag n /Au n (n = 19, 20, 38, 55), nanoclusters and Ag 20 /Au 20 nanoalloys, with a maximum deviation of approximately 0.15 Å. Formation energy results indicate that the GS-SK parameters can closely estimate changes in formation energies with alloy composition, and the comparison of electronic structures for Ag 20 , Au 20 , and AgAu alloy nanoclusters using the DFTB approximation reveals good agreement in the projected density of states (DOS) profiles and energy levels. A second set of SK parameters, ES-SK, has been developed to describe excited state (ES) properties, including the absorption spectra of silver octahedron Ag 19 , tetrahedral Ag n (n = 20, 56, 84), truncated octahedron Ag 38 , and icosahedra Ag 55 closed-shell clusters and their gold and alloy counterparts over a broad range of alloy compositions. This parametrization uses TD-DFTB calculations and fine-tunes the d and p eigenvalues by comparing them to reference absorption spectra from first-principles TD-DFT. This enables the generation of absorption spectra that closely match the reference spectra when plasmon excitation is dominant, as demonstrated by studying the plasmonic properties of icosahedral Ag n and Au n (n = 309 and 561) nanoparticles. This includes the rapid loss in plasmon quality when Au partially replaces Ag in alloy clusters. Furthermore, these results provide a foundation for addressing computational bottlenecks in plasmonics and with new prospects for applications in the quantum plasmonics for bimetallic alloys.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Materials Data on Sm3Ta17O47 by Materials Project

Sm3Ta17O47 crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Sm–O bond distances ranging from 2.43–2.58 Å. In the second Sm3+ site, Sm3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Sm–O bond distances ranging from 2.42–2.73 Å. There are nine inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 20–36°. There are a spread of Ta–O bond distances ranging from 1.92–2.11 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 1–32°. There are a spread of Ta–O bond distances ranging from 1.88–2.18 Å. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 3–40°. There are a spread of Ta–O bond distances ranging from 1.94–2.18 Å. In the fourth Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 1–39°. There are a spread of Ta–O bond distances ranging from 1.89–2.19 Å. In the fifth Ta5+ site, Ta5+ is bonded to seven O2- atoms to form TaO7 pentagonal bipyramids that share corners with two equivalent TaO7 pentagonal bipyramids and edges with five TaO6 octahedra. There are a spread of Ta–O bond distances ranging from 1.96–2.15 Å. In the sixth Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with six TaO6 octahedra and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 21–36°. There are a spread of Ta–O bond distances ranging from 1.85–2.16 Å. In the seventh Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with six TaO6 octahedra and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 20–38°. There are a spread of Ta–O bond distances ranging from 1.85–2.12 Å. In the eighth Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with six TaO6 octahedra and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 16–40°. There are a spread of Ta–O bond distances ranging from 1.90–2.07 Å. In the ninth Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–30°. There are a spread of Ta–O bond distances ranging from 1.96–2.03 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Sm3+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded to two equivalent Sm3+ and two Ta5+ atoms to form a mixture of distorted edge and corner-sharing OSm2Ta2 tetrahedra. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to one Sm3+ and two equivalent Ta5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to three Ta5+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the eighth O2- site, O2- is bonded in a linear geometry to two equivalent Ta5+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the tenth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sm3+ and two Ta5+ atoms. In the eleventh O2- site, O2- is bonded in a distorted T-shaped geometry to three Ta5+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Sm3+ and two Ta5+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Sm3+ and two equivalent Ta5+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the fifteenth O2- site, O2- is bonded in a linear geometry to two equivalent Ta5+ atoms. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to one Sm3+ and two equivalent Ta5+ atoms. In the eighteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the nineteenth O2- site, O2- is bonded to two equivalent Sm3+ and two Ta5+ atoms to form distorted corner-sharing OSm2Ta2 tetrahedra. In the twentieth O2- site, O2- is bonded in a 3-coordinate geometry to one Sm3+ and two equivalent Ta5+ atoms. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to three Ta5+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the twenty-third O2- site, O2- is bonded in a 2-coordinate geometry to one Sm3+ and two equivalent Ta5+ atoms. In the twenty-fourth O2- site, O2- is bonded in a linear geometry to two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on CsMo2P3O13 by Materials Project

CsMo2P3O13 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Cs–O bond distances ranging from 3.09–3.72 Å. In the second Cs1+ site, Cs1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cs–O bond distances ranging from 2.98–3.23 Å. There are four inequivalent Mo5+ sites. In the first Mo5+ site, Mo5+ is bonded to six O2- atoms to form distorted MoO6 octahedra that share corners with five PO4 tetrahedra. There are a spread of Mo–O bond distances ranging from 1.70–2.26 Å. In the second Mo5+ site, Mo5+ is bonded to six O2- atoms to form distorted MoO6 octahedra that share corners with five PO4 tetrahedra. There are a spread of Mo–O bond distances ranging from 1.70–2.22 Å. In the third Mo5+ site, Mo5+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five PO4 tetrahedra. There are a spread of Mo–O bond distances ranging from 1.70–2.17 Å. In the fourth Mo5+ site, Mo5+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five PO4 tetrahedra. There are a spread of Mo–O bond distances ranging from 1.70–2.20 Å. There are six inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three MoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 24–40°. There are a spread of P–O bond distances ranging from 1.53–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four MoO6 octahedra. The corner-sharing octahedra tilt angles range from 27–50°. There are a spread of P–O bond distances ranging from 1.53–1.56 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three MoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–44°. There are a spread of P–O bond distances ranging from 1.52–1.62 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three MoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–38°. There are a spread of P–O bond distances ranging from 1.51–1.63 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four MoO6 octahedra. The corner-sharing octahedra tilt angles range from 18–47°. There is three shorter (1.54 Å) and one longer (1.55 Å) P–O bond length. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three MoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–39°. There are a spread of P–O bond distances ranging from 1.52–1.64 Å. There are twenty-six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mo5+ and one P5+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Cs1+ and one Mo5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo5+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Mo5+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mo5+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mo5+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to one Mo5+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to two Cs1+, one Mo5+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Mo5+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Mo5+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Mo5+, and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cs1+ and two P5+ atoms. In the eighteenth O2- site, O2- is bonded in a single-bond geometry to one Mo5+ atom. In the nineteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the twentieth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mo5+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a distorted single-bond geometry to one Cs1+ and one Mo5+ atom. In the twenty-third O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Mo5+, and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Mo5+, and one P5+ atom. In the twenty-sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mo5+ and one P5+ atom.

36 MATERIALS SCIENCE↗

NASA NTRS1985

A piston-driven shock in the solar corona

A solar flare that occurred on the west limb at 20:38 UT on Mar. 25, 1981 generated a massive, rapidly expanding optical coronal transient, which moved outward with an approximately constant velocity of 800 km/s. An associated magnetohydrodynamic shock traveled out ahead of the transient with a velocity estimated to be approximately 1000 km/s. The optical and radio data on the transient and shock fit well with general theories concerning piston-driven shocks and with current MHD models for propagation of such shocks through the solar corona.

Maxwell, A.↗

NASA NTRS1996

Summary Report of Mission Acceleration Measurements for STS-73, Launched October 20, 1995

The microgravity environment of the Space Shuttle Columbia was measured during the STS-73 mission using accelerometers from five different instruments: the Orbital Acceleration Research Experiment, the Space Acceleration Measurement System, the Three-dimensional Microgravity Accelerometer, the Microgravity Measuring Device, and Suppression of Transient Accelerations by Levitation Evaluation System. The Microgravity Analysis Workstation quasi-steady environment calculation and comparison of this calculation with Orbital Acceleration Research Experiment data was used to assess how appropriate a planned attitude was expected to be for one Crystal Growth Facility experiment sample. The microgravity environment related to several different Orbiter, crew, and experiment operations is presented and interpreted in this report. Data are examined to show the effects of vernier reaction control system jet firings for Orbiter attitude control. This is compared to examples of data when no thrusters were firing, when the primary reaction control system jets were used for attitude control, and when single vernier jets were fired for test purposes. In general, vernier jets, when used for attitude control, cause accelerations in the 3 x 10(exp -4) g to 7 x 10(exp -4) g range. Primary jets used in this manner cause accelerations in the 0.01 to 0.025 g range. Other significant disturbance sources characterized are water dump operations, with Y(sub b) axis acceleration deviations of about 1 x 10(exp -6) g; payload bay door opening motion, with Y(sub o) and Z(sub o) axis accelerations of frequency 0.4 Hz; and probable Glovebox fan operations with notable frequency components at 20, 38, 43, 48, and 53 Hz. The STS-73 microgravity environment is comparable to the environments measured on earlier microgravity science missions.

Rogers, Melissa J. B.↗

NASA NTRS2002

A IAB-Complex Iron Meteorite Containing Low-Ca Clinopyroxene: Northwest Africa 468 and its Relationship to Iodranites and Formation by Impact Melting

Northwest Africa 468 (NWA 468) is a new ungrouped, silicate-rich member of the IAB complex of nonmagmatic iron meteorites. The silicates contain relatively coarse (approximately 300 micron-size) grains of low-Ca clinopyroxene with polysynthetic twinning and inclined extinction. Low-Ca clinopyroxene is indicative of quenching from high temperatures (either from protoenstatite in a few seconds or high-temperature clinoenstatite in a few hours). It seems likely that NWA 468 formed by impact melting followed by rapid cooling to less than or equal to 660 C. After the loss of a metal-sulfide melt from the silicates, sulfide was reintroduced, either from impact-mobilized FeS or as an S2 vapor that combined with metallic Fe to produce FeS. The O-isotopic composition (delta O-17 = -1.39 %) indicates that the precursor material of NWA 468 was a metal-rich (e.g., CR) carbonaceous chondrite. Lodranites are similar in bulk chemical and O-isotopic composition to the silicates in NWA 468; the MAC 88177 lodranite (which also contains low-Ca clinopyroxene) is close in bulk chemical composition. Both NWA 468 and MAC 88177 have relatively low abundances of REE (rare earth elements) and plagiophile elements. Siderophiles in the metal-rich areas of NWA 468 are similar to those in the MAC 88177 whole rock; both samples contain low Ir and relatively high Fe, Cu and Se. Most unweathered lodranites contain approximately 20 - 38 wt. % metallic Fe-Ni. These rocks may have formed in an analogous manner to NWA 468 (i.e., by impact melting of metal-rich carbonaceous-chondrite precursors) but with less separation of metal-rich melts from silicates.

Rubin, Alan E.↗

DOE OSTI2021

Understanding Superatomic Ag Nanohydrides

Abstract Bulk Ag hydrides are extremely challenging to make even at very high pressures, but they may become stable as the particle size shrinks to the nanometer regime. Here, the formation and electronic structure of Ag nanohydrides are investigated from a superatomic perspective by density functional theory. It is found that as the coverage increases, adsorption energy of hydrogen atoms on Ag 38 cluster to form Ag 38 H 2 n nanohydride ( n is from 1 to 15) can be energetically favorable with respect to bare Ag 38 and H 2 . Furthermore, the adsorbed hydrogen atoms contribute their 1s electrons to the superatom electron count and behave as a metal instead of a ligand. The electronic structure of the silver nanohydrides follows the superatomic complex model, leading to magic or relatively more stable compositions such as Ag 38 H 2 , Ag 38 H 20 , and Ag 38 H 30 , which correspond to 40‐electron, 58‐electron, and 68‐electron shell closings, respectively. Angular momentum analyses of the superatomic orbitals suggest a convoluted interaction of geometry, symmetry, and orbital splitting.

He, Xiang↗

DOE OSTI2020

Localized Corrosion Behavior of Non-Equiatomic NiFeCrMnCo Multi-Principal Element Alloys

A series of single phase Ni 38 Fe 20 Cr x Mn 21–0.5x Co 21–0.5x multi-principal element alloys (MPEAs) were fabricated and their localized corrosion behavior was tested in 0.6 M NaCl solution. These MPEAs were found to be susceptible to localized corrosion, exhibiting pitting at room temperature, as indicated by positive hysteresis loops and low repassivation potentials observed in cyclic potentiodynamic polarization experiments. The pitting resistance increased with increasing Cr content. Interestingly, even the MPEAs with low chromium content, Ni 38 Fe 20 Cr 6 Mn 18 Co 18 and Ni 38 Fe 20 Cr 10 Mn 16 Co 16 , exhibited passivity and localized corrosion. Here, the passivity observed in these low chromium MPEAs is likely derived from their relatively high nickel content. Crystallographic pit morphology was observed in most of these MPEAs, suggesting the absence of a salt film on the dissolving pit surface. Such crystallographic pit morphology indicates that the pit growth in most of these MPEAs was under charge-transfer/ohmic control.

36 MATERIALS SCIENCE↗

NASA NTRS1983

Radiative properties of advanced spacecraft heat shield materials

Experimental results are presented to show the effects of simulated reentry exposure by convective heating and by radiant heating on spectral and total emittance of statically oxidized Inconel 617 and Haynes HS188 superalloys to 1260 K and a silicide coatea (R512E) columbium 752 alloy to 1590 K. Convective heating exposures were conducted in a supersonic arc plasma wind tunnel using a wedge-shaped specimen configuration. Radiant tests were conducted at a pressure of .003 atmospheres of dry air at a flow velocity of several meters per second. Convective heating specimens were subjected to 8, 20, and 38 15-min heating cycles, and radiant heating specimens were tested for 10, 20, 50, and 100 30-min heating cycles. Changes in radiative properties are explained in terms of changes in composition resulting from simulated reentry tests. The methods used to evaluate morphological, compositional and crystallographic changes include: Auger electron spectroscopy; scanning electron microscopy; X-ray diffraction analysis; and electron microprobe analysis.

Cunnington, G. R.↗

NASA NTRS1982

Radiative properties of a nickel based superalloy: Inconel 617 - After simulated earth reentry

Experimental results are presented to show the effect of environmental simulation exposures of convective heating and of radiant heating on the spectral (1.0 to 14 micrometers) and total emittance of oxidized Inconel 617. Convective heating exposures were conducted in an arc heated supersonic wind tunnel using a wedge-shaped specimen configuration. Radiant tests were conducted in dry air at a flow velocity of several meters per second. Convective heating specimens were subjected to 8, 20 and 38 heating cycles of 15-minutes duration and radiant heating specimens were tested for 10, 20, 50 and 100 one-half hour heating cycles. Changes in radiative properties are discussed in terms of changes in composition and morphology resulting from the exposure tests. Total normal emittance did not significantly change from the statically oxidized condition after either type of exposure, and it remained above 0.80 at 1260K for all cases. Although spectral changes were observed on post exposure specimens at wavelengths less than 2.0 micrometers and greater than 15 micrometers, these changes have no influence on total emittance at 1260K.

Cunnington, G. R.↗

NASA NTRS1987

Performance and power regulation characteristics of two aileron-controlled rotors and a pitchable tip-controlled rotor on the Mod-O turbine

Tests were conducted on the DOE/NASA mod-0 horizontal axis wind turbine to compare and evaluate the performance and the power regulation characteristics of two aileron-controlled rotors and a pitchable tip-controlled rotor. The two aileron-controlled rotor configurations used 20 and 38 percent chord ailerons, while the tip-controlled rotor had a pitchable blade tip. The ability of the control surfaces to regulate power was determined by measuring the change in power caused by an incremental change in the deflection angle of the control surface. The data shows that the change in power per degree of deflection angle for the tip-controlled rotor was four times the corresponding value for the 2- percent chord ailerons. The root mean square power deviation about a power setpoint was highest for the 20 percent chord aileron, and lowest for the 38 percent chord aileron.

Corrigan, Robert D.↗

DOE OSTI2025

Climate change and federal aid disbursements after Hurricane Harvey: an extreme event attribution analysis

The role climate change plays in increasing the burden placed on governments and insurers to pay for recovery has not been extensively explored and is the focus of this study. This study examines the impacts of climate change attributed flooding on federal disaster aid disbursement in Harris County, Texas following Hurricane Harvey in 2017. Our approach uses flood models to estimate the amount of flood damages attributable and not attributable to climate change under two climate change attribution scenarios from peer reviewed studies: 20% and 38% increases in rainfall associated with the hurricane due to climate change. These estimates are combined with census tract-level disbursement data for FEMA’s National Flood Insurance Program (NFIP) and the Individual Assistance (IA) part of the Individuals and Households Program. We employ spatial lag regression models with direct and spatial spillover effects to analyze the relationship between a tract’s flood damages—both attributed and not attributed to climate change—and federal disaster aid. We find that both types of flood damage shape federal aid disbursements, but that climate change attributed damages tend to have larger effect sizes (elasticities) especially for IA. Specifically, for a 1% increase in additional climate change attributed damages per household in a census tract (under the 20% scenario), expected NFIP levels in that census tract are 0.26% higher and IA levels are 0.3% higher. Implications center on federal funding in an era of climate change.

FEMA↗

DOE OSTI2026

Wind lidar operations and observations from Tundra Pigeon

Lawrence Livermore National Laboratory brought a ZX-300 profiling lidar to the Tundra Pigeon experiment for the purpose of collecting wind measurements in the lower atmospheric boundary layer. The ZX-300 lidar is a portable Doppler lidar which uses light to track naturally occurring aerosols across a measurement cone, thereby deriving wind speed (horizontal and vertical) and wind direction. The ZX-300 is programable between the heights of 10 m and 300 m above ground level and additionally has a 1 m onboard meteorological sensor for collecting measurements of air temperature, relative humidity, air pressure and wind at 1 m height. We programmed the ZX-300 to target altitudes of most interest to the tracer experiment. These heights were 10, 15, 20, 30, 38, 50, 75, 100, 125, 150 and 200 m. Note that the 38 m level is a fixed calibration height and cannot be changed. This measurement strategy prioritized winds close to the surface while ensuring that we’d also collect information about the winds aloft. The wind measurements are collected directly over the lidar instrument and represent a vertical profile of the winds over that location. However, given that there were minimal terrain and vegetation differences in the area, we’d expect these wind conditions to be representative of a larger volume area, discussed in more detail below.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1981

Cyclic nucleotides in tissues during long-term hypokinesia

Male Wistar rates were kept hypokinetic by placing them in small containers for 22 days. Blood plasma cAMP content was subsequently found increased, and cGMP content decreased, in the experimental animals. Liver and thymus cAMP content was similar in the control and experimental animals. There was a 20 and 38% decrease of cAMP content in the kidneys and spleen, respectively. Hypokinesia's reduction of cyclic nucleotides seems to inhibit RNA and protein synthesis.

Makeyeva, V. F.↗

NASA NTRS1984

Aileron controls for wind turbine applications

Horizontal axis wind turbines which utilize partial or full variable blade pitch to regulate rotor speed were examined. The weight and costs of these systems indicated a need for alternate methods of rotor control. Aileron control is an alternative which has potential to meet this need. Aileron control rotors were tested on the Mod-O wind turbine to determine their power regulation and shutdown characteristics. Test results for a 20 and 38% chord aileron control rotor are presented. Test is shown that aileron control is a viable method for safety for safely controlling rotor speed, following a loss of general load.

Miller, D. R.↗

NASA NTRS1984

Aileron controls for wind turbine applications

Horizontal axis wind turbines which utilize partial or full variable blade pitch to regulate rotor speed were examined. The weight and costs of these systems indicated a need for alternate methods of rotor control. Aileron control is an alternative which has potential to meet this need. Aileron control rotors were tested on the Mod-O wind turbine to determine their power regulation and shutdown characteristics. Test results for a 20 and 38 percent chord aileron control rotor are presented. Test is shown that aileron control is a viable method for safety for safely controlling rotor speed, following a loss of general load.

Miller, D. R.↗