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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Evolution of the lithium morphology from cycling of thin film solid state batteries

Thin film batteries with a Lipon electrolyte and Li metal anode can be cycled thousands of times. During this time there is a gradual redistribution of the lithium at the top surface; the morphology that develops depends on a number of factors but is largely driven by dewetting. In this work, this redistribution is characterized as functions of the cycle number, duty cycle, cathode composition, and protective coating over the lithium. Observations of wrinkled and pitted surfaces are discussed considering the effects of defects and diffusion in the lithium and influences of film stresses and surface energy. In conclusion, similar processes may impact solid state lithium batteries with higher energy per active area.

25 ENERGY STORAGE↗
DOE OSTI2018

Degradation of Polyester Polyurethane by Aspergillus sp. Strain S45 Isolated from Soil

A polyurethane (PU)-degrading fungus designated as strain S45 was isolated from a solid waste-dumping site in Islamabad, Pakistan. Strain S45 was identified as Aspergillus sp. through microscopic, morphologic as well as 18S rRNA sequencing (99% similarity with Aspergillus fumigatus). The degradation ability of strain S45, was analyzed through measurement of weight loss and evolution of CO{sub 2} as a result of breakdown of PU film. The degradation was confirmed through scanning electron microscopy, fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). Surface changes like pits, cracks and holes were observed in scanning electron micrographs upon degradation of PU film by strain S45. FTIR spectra were carefully examined, changes were observed in various peaks at different wavelength ranges that also correspond to degradation of PU film. Differential scanning calorimetric technique was used to measure the melting temperature of PU film pieces before and after incubation with strain S45. DSC curve indicated an increase in melting temperature of PU from 191 to 196 °C that might be due to increase in crystallinity of the exposed PU after degradation of amorphous soft segment. A gradual increase in specific activity of esterase was observed up to the maximum of 15th day of incubation with PU film in mineral salt medium. Enzyme activity was further confirmed by tween 20 agar plates, demonstrated by formation of calcium complex. It is concluded from the results that Aspergillus sp. strain S45 might be applied for the treatment of plastics-contaminated environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Preparation of Nb{sub 3}Al Superconducting Tapes by a Powder-in-Tube Method Combined with Hot-Pressed Sintering

The precursors of Nb-Al tape were fabricated by a powder-in-tube (PIT) technique. Supersaturated solid solutions of Nb-Al powder were obtained by high-energy ball milling, followed by a powder-in-tube process to prepare series of Nb{sub 3}Al precursor tapes. Compared with sintering under normal pressure, the hot-pressing sintering greatly increased the critical current density of the tapes. The results showed that the Nb{sub 3}Al tapes prepared via the powder-in-tube method and hot-pressed sintering could significantly improve the J{sub c} performance, and the value of J{sub c} (8 K, 0 T) was higher than 6 × 10{sup 5} A/cm{sup 2}. The Nb{sub 3}Al tapes after pressing under the pressure of 20 MPa and sintering at 950 {sup ∘}C for 3 h had the best magnetic flux pinning performance, and the sample reached the maximum flux pinning force (F{sub p,max}) of 3.28109 N/m{sup 3} in the magnetic field of 2.2 T.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Optimization of FeSe Superconducting Tapes with Different Sheath Materials and Precursor Powders

FeSe superconducting tapes with different sheath materials of Nb/Cu composite, Ag, and Fe have been fabricated with a traditional in situ powder-in-tube (PIT) process, respectively. With the same cold working process and heat treatment, the influences of different sheath materials on the phase composition and microstructures of FeSe filaments have been analyzed. Due to the reaction between Nb-Se and Ag-Se, Nb{sub 2}Se and Ag{sub 2}Se particles can be clearly observed embedded in the filaments. Therefore, it is necessary to introduce a new method for the fabrication of Ag or Nb sheath FeSe wires in order to avoid the introduction of metal Fe in magnet system during practical applications. Based on our previous study, a high-energy ball milling process has been performed to achieve precursor powders with amorphous FeSe binary compound instead of elemental Se. The formation of Ag-Se compounds has been successfully avoided and the superconducting tapes with high superconducting FeSe critical temperature of 9.0 K have been obtained.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Effects of Rolling Passes on the Transport Properties of 37-Filamentary AgAu-Sheathed Bi-2223 Tapes

Thirty-seven-filamentary AgAu-sheathed Bi-2223 tapes were fabricated by a powder-in-tube (PIT) process. And, the round wires (ϕ 1.86 mm) were rolled to 0.35-mm tapes with 12, 7, 5, and 4 rolling passes through flat rolling, respectively. The influences of different rolling passes on the core density, deformation, and transport properties of Bi-2223/AgAu tapes were systematically investigated. It was noticed that after rolling, the Vickers microhardness of the superconducting core and deform homogeneity along both the horizontal and vertical directions on the cross section of seven-pass rolled tape were better than those on the tapes with other passes, which proved the larger core density and uniform deformation with the seven-pass rolling process. Meanwhile for the wires with 12 and 7 passes, the AgAu/superconducting core interfaces were much flatter. With the rolling passes decreasing from 12 to 4, the critical current density (J{sub c}) first increased and then decreased. Due to the better homogeneity and flatter interfaces, J{sub c} reached the maximum value of 17.3 kA/cm{sup 2} on the seven-pass sample. Meanwhile, the enhancement of current capacities in magnetic field applied parallel to the Bi-2223/AgAu tape surface could also be recognized as the evidence of improving intergrain connections due to the higher density in seven-pass rolled tapes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Influence of Packing Atmosphere on the Microstructures and Transport Properties of Bi-2223/AgAu Tapes

Oxygen partial pressure was the key factor to tune the phase evolution mechanism of Bi-2223 system. In order to investigate the influence of packing atmosphere on the phase formation rate of Bi-2223, microstructures‚ and the current capacity of final tapes‚ 37-filamentary Bi-2223/AgAu tapes were fabricated by powder-in-tube (PIT) process, and the powder packing process operated in the glove box under different atmosphere of pure O{sub 2}‚ air, and N{sub 2}–7.5%O{sub 2}, with the oxygen partial pressure of 100%‚ 25%, and 7.5%, respectively. With different packing atmosphere, the phase formation rate of Bi-2223 increased obviously during the first heat treatment process (HT1). While, based on the same HT1 process, the maximum Bi-2223 phase content was obtained in the tapes with packing atmosphere of N{sub 2}–7.5%O{sub 2}‚ which should be attributed to the suitable Bi-2223 content and distribution. Due to the improvement of superconducting phase content and better texture structure, the critical current density increased with decreasing oxygen partial pressure of packing atmosphere and the maximum value of 19.9 kA/cm{sup 2} was reached. Moreover‚ the in-field current capacities of these Bi-2223/AgAu tapes have also been enhanced with low oxygen partial pressure in packing atmosphere, attributed to the improvements of intergrain connectivity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Estimation of soil classes and their relationship to grapevine vigor in a Bordeaux vineyard: advancing the practical joint use of electromagnetic induction (EMI) and NDVI datasets for precision viticulture

Working within a vineyard in the Pessac Léognan Appellation of Bordeaux, France, this study documents the potential of using simple statistical methods with spatially-resolved and increasingly available electromagnetic induction (EMI) geophysical and normalized difference vegetation index (NDVI) datasets to accurately estimate Bordeaux vineyard soil classes and to quantitatively explore the relationship between vineyard soil types and grapevine vigor. First, co-located electrical tomographic tomography (ERT) and EMI datasets were compared to gain confidence about how the EMI method averaged soil properties over the grapevine rooting depth. Then, EMI data were used with core soil texture and soil-pit based interpretations of Bordeaux soil types (Brunisol, Redoxisol, Colluviosol and Calcosol) to estimate the spatial distribution of geophysically-identified Bordeaux soil classes. A strong relationship (r = 0.75, p < 0.01) was revealed between the geophysically-identified Bordeaux soil classes and NDVI (both 2 m resolution), showing that the highest grapevine vigor was associated with the Bordeaux soil classes having the largest clay fraction. The results suggest that within-block variability of grapevine vigor was largely controlled by variability in soil classes, and that carefully collected EMI and NDVI datasets can be exceedingly helpful for providing quantitative estimates of vineyard soil and vigor variability, as well as their covariation. The method is expected to be transferable to other viticultural regions, providing an approach to use easy-to-acquire, high resolution datasets to guide viticultural practices, including routine management and replanting.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Wetting Behavior of Calcium Ferrite Slags on Cristobalite Substrates

Calcium ferrite (CF) is a significant intermediate adhesive phase in high-basicity sinters. The wettability between calcium ferrite (CF) and gangue plays an important role in the assimilation process. The wettability of CF-based slags, in which a constant amount (2 mass pct.) of Al{sub 2}O{sub 3}, MgO, SiO{sub 2}, and TiO{sub 2} was added, on solid SiO{sub 2} (cristobalite) substrates at 1523 K (1250 °C) was investigated. The interfacial microstructure and spreading mechanisms were discussed for each sample. All the tested slag samples exhibited good wettability on the SiO{sub 2} substrate. The initial apparent contact angles were in the range of 20 to 50 deg, while the final apparent contact angles were ~ 5 deg. The wetting process could be divided into three stages on the basis of the change in diameter, namely the “linear spreading” stage, “spreading rate reduction” stage, and “wetting equilibrium” stage. It was found that the CF-SiO{sub 2} wetting system exhibits dissolutive wetting and the dissolution of SiO{sub 2} into slag influences its spreading process. The spreading rate increases with a decrease in the ratio of viscosity to interfacial tension, which is a result of the addition of Al{sub 2}O{sub 3}, MgO, SiO{sub 2}, and TiO{sub 2}. After cooling, a deep corrosion pit was formed in the substrate and a diffusion layer was generated in front of the residual slag zone; further, some SiO{sub 2} and Fe{sub 2}O{sub 3} solid solutions precipitated in the slag.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Influences of Quench Cooling Rate on Microstructure and Corrosion Resistance of Al-Cu-Mg Alloy Based on the End-Quenching Test

To investigate the effects of the quench cooling rate on corrosion resistance of Al-Cu-Mg alloy, an end-quenching test was conducted and the microstructures at different cooling rates were observed by SEM and TEM. Additionally, the corrosion resistance was characterized by an intergranular corrosion test and electrochemical test. Moreover, the finite element method was applied to simulate the end quenching process. The results indicate that the actual end quenching process can be approximated as one-dimensional heat transfer, and the cooling rate varies at different cooling distances. By affecting the microstructures, decreasing the cooling rate leads to a decline in the corrosion properties. Low cooling rates coarsen the constituent particles and grain boundary particles, resulting in a wide precipitation-free zone and an increase in the intensity of corrosion reactions. A high cooling rate concentrates on the intragranular precipitant, which can reduce the pitting depth and represents a conversion from localized corrosion to general corrosion.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Corrosion and Fatigue Behavior of High-Strength Steel Treated with a Zn-Alloy Thermo-diffusion Coating

High and low cycle fatigue tests were conducted on high-strength steel using four-point bending. The materials tested were ASTM A723 steel in the as-machined condition, grit-blasted condition, MIL-DTL-16232 heavy manganese phosphate-coated condition, and ASTM A1059 Zn-alloy thermo-diffusion coated (Zn-TDC). The ASTM A723 steel base material exhibits a yield strength of ~1000 MPa. The effects of the surface treatments versus uncoated steel were examined. The fatigue life of the Zn-TDC specimens was generally reduced on as-coated specimens versus uncoated or phosphate-coated specimens. Several mechanisms are examined including the role of compressive residual stress relief with the Zn-TDC process as well as fatigue crack initiation from the hardened Zn-Fe alloy surface layer produced in the gas-metal reaction. Additionally, the effects of corrosion pitting on the fatigue life of coated specimens are explored as the Zn-TDC specimens exhibit significantly improved corrosion resistance over phosphate-coated and oiled specimens.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Corrosion Behavior of Candidate Materials Used for Urea Hydrolysis Equipment in Coal-Fired Selective Catalytic Reduction Units

Corrosion tests were performed in the laboratory in order to assess the corrosion resistance of candidate materials used in urea hydrolysis equipment. The materials to be evaluated were exposed at 145 °C for 1000 h. Alloys 316L, 316L Mod., HR3C, Inconel 718, and TC4 were evaluated. Additionally, aluminide and chromate coatings applied to a 316L substrate were examined. After exposure, the mass changes in the test samples were measured by a discontinuous weighing method, and the morphologies, compositions, and phases of the corrosion products were analyzed using scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Results indicated that continuous pitting and dissolution corrosion were the main failure modes for 316L stainless steel. 316L Mod. and HR3C alloy showed better corrosion resistance than 316L due to their relatively high Cr contents, but HR3C exhibited a strong tendency toward intergranular corrosion. Inconel 718, TC4, and aluminide and chromate coating samples showed similar corrosion processes: only depositions formed by hydrothermal reactions were observed. Based on these results, a possible corrosion process in the urea hydrolysis environment was discussed for these candidate materials and questions to be clarified were proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Influences of Processing and Fatigue Cycling on Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk Superalloy

Oxidation and corrosion can attack superalloy disk surfaces exposed to increasing operating temperatures in some turbine engine environments. Any potential protective coatings must also be resistant to harmful fatigue cracking during service. The objective of this study was to investigate how residual stresses evolve in one such coating. Fatigue specimens of a powder metallurgy-processed disk superalloy were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of this processing and fatigue cycling on axial residual stresses and other aspects of the coating were assessed. While shot peening did induce beneficial compressive residual stresses in the coating and substrate, these stresses relaxed in the coating with subsequent heating. Several cast alloys having compositions near the coating were subjected to thermal expansion and tensile stress relaxation tests to help explain this response of residual stresses in the coating. For the coated fatigue specimens, this response contributed to earlier cracking of the coating than for the uncoated surface during long intervals of cycling at 760 °C. Yet, substantial compressive residual stresses still remained in the substrate adjacent to the coating, which were sufficient to suppress fatigue cracking there. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Passive and Semiconducting Properties Assessment of Commercially Pure Tantalum in Hank’s Physiological Solution

In this study, various electrochemical measurements were used to evaluate the passive and semiconducting properties of commercially pure tantalum (Ta) in Hank’s physiological solution at 310 K (37 °C). Potentiodynamic polarization and electrochemical impedance spectroscopy results show that the passivation of pure Ta immersed in Hank’s physiological solution improves over time. Mott–Schottky (M–S) tests indicate that the passive layers of pure Ta in Hank’s physiological solution behave as n-type semiconductors and longer immersion times do not lead to any inversion of semiconducting behavior. Additionally, M–S tests show that as the immersion time increases, the donor density of the passive layer decreases. Finally, scanning electron microscope micrographs and energy-dispersive spectroscopy results reveal that Ta is less likely to experience significant pitting or buildup of undesirable corrosion products after longer immersion times in this physiological solution.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Improving Corrosion Resistance and Corrosive Wear Resistance of Aluminum Alloy Drill Pipe by Surface Nanocrystallization and Micro-arc Oxidation

To improve the corrosion and wear resistance performance of aluminum alloy drill pipes in geological and petroleum drilling applications, a strengthening coating was prepared on the surface of the 2618 aluminum alloy by combining treatment with ultrasonic cold forging technology (UCFT) and micro-arc oxidation (MAO). The effects of the strengthening coating on the corrosion and wear resistance of the aluminum alloy were evaluated by electrochemical and tribological tests. The results demonstrated that the corrosion and wear resistance of the aluminum alloy were improved by the UCFT and MAO technologies, especially the salt corrosion resistance. The corrosion morphology of the strengthening coating primarily included pitting, micro-cracks and NaCl attachment. In addition, the UCFT + MAO composite coating exhibited the best wear performance. The wear rate of the UCFT + MAO composite coating was lower than that of the aluminum alloy by 94%. The results provided support for this excellent surface treatment technology for the corrosion and wear resistance of aluminum alloy drill pipes, and they also present a feasible evaluation method for drill pipes.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Electrochemical Corrosion Behavior of Plasma-Sprayed FeCrNiMoCBSi Amorphous/Nanocrystalline Coatings in Simulated Seawater Medium

A novel FeCrNiMoCBSi coating was fabricated on F22 marine steel by plasma spraying. The coating microstructure and composition were characterized by scanning electron microscope, transmission electron microscope, x-ray diffraction, differential scanning calorimetry, and x-ray photoelectron spectroscopy. The results showed that the coating consisted of amorphous and nanocrystalline phases. Additionally, the corrosion resistance in simulated seawater was evaluated by electrochemical corrosion methods. It was found that the coating exhibited an excellent resistance to pitting corrosion. For long-time immersion tests, the corrosion resistance was gradually decreased with the increasing through-porosity due to the permeation of the corrosive solution into the coating. The coating lost its efficacy through three stages, namely the protection stage, the permeation stage, and the failure stage.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microstructural Characterization and Electrochemical Behavior of AA2014 Al-Cu-Mg-Si Alloy of Various Tempers

AA2014 Al-Cu-Mg-Si alloy is subjected to aging heat treatment, and microstructural features and electrochemical behavior of the AA2014 Al-Cu-Mg-Si alloy of various tempers have been characterized. Hardness measurement of the alloy of different tempers showed typical age hardening behavior. X-ray diffraction and transmission electron microscopy studies revealed the presence of characteristic phases. Differential scanning calorimetry study displayed the sequence of solid-state precipitation and dissolution reactions in the AA2014 alloy of various tempers. Electrochemical behavior was assessed by measurement of variation of open-circuit voltage with time, potentiodynamic polarization and potentiodynamic cyclic polarization of the AA2014 alloy of various tempers in 3.5 wt.% NaCl solution at near neural (pH ~ 7) and at alkaline (pH 12) conditions. Potentiodynamic polarization studies of different tempers in 3.5 wt.% NaCl solution at pH ~ 7 showed that the corrosion potential (E{sub corr}) value has shifted toward more negative (active) direction with increasing aging time. The cyclic polarization in 3.5 wt.% NaCl solution at pH ~ 7 displayed active–passive behavior and also showed a large hysteresis loop indicating high pit growth damage.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Defect Characterization Through Automated Laser Track Trace Identification in SLM Processes Using Laser Profilometer Data

This paper presents recent developments in statistical image processing to demonstrate feasibility of layer-by-layer nondestructive inspection for selective laser melting (SLM) of metallic parts. A matrix of 10 mm × 10 mm stainless 316 squares was deposited with the first row consisting of just the sintered surface, Row 2 a single layer, Row 3 with 2 layers and so on. These layers were scanned to emulate the layer-by-layer collection of top surface geometry using a laser sensor. The resultant data were utilized to generate ISO 25718 roughness parameters and subsequently to perform track identification. This calculation consisted of two salient steps: (1) computing the gradients of surface roughness, which vanish at the peaks and pits, and (2) extracting the scanning direction by taking Hough transform of the geometry. This algorithm was repeated for all layers, and the alignment of the roughness with the rotating scan was observed to be persistent for all layers. Correlation between surface properties obtained along various scan directions and defect probability is explored.

36 MATERIALS SCIENCE↗