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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Measurement of Localized Corrosion Rates at Inclusion Particles in AA7075 by In Situ Three Dimensional (3D) X-ray Synchrotron Tomography

In situ X-ray synchrotron tomography was used to measure the localized corrosion rate of Mg2Si particles present in 7075 aluminum alloys in deionized ultra-filtered (DIUF) water. The evolution of hydrogen bubbles was captured as a function of time and the measured volume was used to calculate the local corrosion rate of Mg2Si particles. It was shown that in the absence of chloride ions, stress was needed to create fresh particle surfaces, either by fracture or debonding, to initiate corrosion at the particles.

A. Aluminum alloys↗
DOE OSTI2018

Homogenization of Al x CoCrFeNi high-entropy alloys with improved corrosion resistance

The present work investigates the homogenization effect of 1250 °C heat treatment on the Al x CoCrFeNi high-entropy alloys (HEAs). The multi-phase microstructures with chemical segregations are inevitable with the increased Al content in the alloys, which cause work function variations and localized corrosion. After heat treatment, the homogenization effect revealed by the microstructure simplification and chemical-segregation reduction leads to the decreased work function variations and the improved corrosion resistance. Furthermore, thermodynamic calculations that are reliable to predict the phase transformations of the Al x CoCrFeNi HEAs, indicates a further enhancement in corrosion resistance through annealing could be guided for many other HEAs systems.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Uranium hydride corrosion. I New insights into the Condon-Kirkpatrick model of uranium hydride formation rate

An analytic solution to the uranium hydride formation rate equation of Condon and Kirkpatrick (CK) has been developed, which is directly solved via algebraic operations and requires only gaseous hydrogen (H 2 ) pressure and temperature as inputs. The solution does not depend on the specific functional forms of the hydriding and dehydriding rate constants, nor of key physical parameters. Furthermore, a modified form of the CK model has also been developed, where replacement of the hydrogen solubility function results in an improved fit to published experimental data as H 2 pressure decreases toward the corrosion threshold value.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electrochemical noise studies on localized corrosion of Ni and Ni-20Cr in molten ZnCl 2

The electrochemical noise (ECN) technique was employed to study corrosion of two model systems, i.e. pure Ni and a binary Ni-20 wt%Cr (Ni20Cr) alloy in molten ZnCl 2 at 623 K. Here we measured ECN transients in current and open-circuit potential from two nominally identical Ni-Ni and Ni20Cr-Ni20Cr electrodes and one galvanic Ni-Ni20Cr electrode pair. The behavior of ECN is quite distinct among the three-electrode systems, and it is correlated with the various microscopic observations of micro- and nano-scale morphological features. Based on the ECN study coupled with the microstructural analysis, the origins of ECN in the molten salt environment as well as the mechanisms of localized corrosion in the three systems are discussed.

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

Correlation between corrosion resistance, anodic hydrogen evolution and microhardness in friction stir weldment of AA2198 alloy

Highlights: • There is a relationship between hardness, corrosion and H{sub 2} evolution in AA2198-T851 alloy friction stir weldment • Variation in the population density of T1 particles is the correlating factor for the relationship • The parent material is the region that is most susceptible to corrosion. • The weld zones of AA2198-T851 alloy friction stir weldment exhibit different forms of corrosion. - Abstract: Correlation between corrosion resistance, anodic hydrogen evolution and microhardness in the friction stir weldment of AA2198-T851 alloy has been investigated. Different microscopy techniques, scanning vibrating electrode technique (SVET) and potentiodynamic polarization tests were employed in the investigation. Unlike other 3rd generation Al-Cu-Li alloys where the regions that are most susceptible to corrosion are always within the weld region, the results reveal that the parent material is the most susceptible in this case. There is a direct correlation between corrosion resistance, anodic hydrogen evolution and microhardness in the weldment, and the T{sub 1} phase is associated with the direct correlation.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Colloidal nanocrystals for heterogeneous catalysis

Catalytic materials are an essential component of the chemical industry. They find applications in everything from fine chemical manufacturing to greenhouse gas mitigation. They are indispensable for developing a sustainable future. Their development has been continuous, from early trial and error efforts to the first fundamental insights gained through surface science, to modern in-situ characterization and computational predictions. The accumulation of knowledge on the working principles of catalytic surfaces allowed designing and producing better systems with improved performance. Even though tremendous progress has been made thanks to surface science techniques, these studies are usually performed under ultra-high vacuum and are therefore limited in their applicability to more relevant industrial conditions. The control over size, shape and composition in colloidal nanocrystals makes them formidable precursors for model heterogeneous catalysts. These model systems enable linking the insights from surface science studies via in-situ and operando studies to realistic catalytic reaction conditions. In this review, colloidal nanocrystals are presented as powerful building blocks for catalytic materials in the quest for fundamental understanding. A review of the principal methods to produce colloidal nanocrystals with a high level of control is reported, complemented by procedures for how to prepare active catalysts from these particles. Examples and guidelines for the catalytic applications of these materials revolve around the three guiding objectives in catalysis science: activity, selectivity and stability. This work will be limited to examples of this colloidal approach in the areas of thermal, electro- and photocatalysis. In conclusion, the exposed approaches can be used and extended to many other areas of catalysis science, thus providing a new avenue to explore fundamentals and applications of catalytic materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Modular Pd/Zeolite Composites Demonstrating the Key Role of Support Hydrophobic/Hydrophilic Character in Methane Catalytic Combustion

Complete catalytic oxidation of methane in the presence of steam at low temperatures (T < 400 °C) is a crucial reaction for emission control, yet it presents profound challenges. The activation of the strong C–H bond of methane at low temperature is difficult, and the water present in any realistic application poisons the active surface and promotes sintering of Pd particles during the reaction. Finding materials that can deliver high reaction rates while being more resistant to the presence of water is imperative for advancing several technological applications of natural gas-based systems. However, methods to fairly compare the activity of Pd catalysts (the most active metal for methane combustion) are needed in order to perform useful structure–property relationship studies. Here in this paper, we report a method to study how zeolite hydrophobicity affects the activity of Pd nanoparticles in the reaction, which led to a significant improvement in the water resistance. Mesoporous zeolites were synthesized starting from commercially available microporous zeolites. In this way, a variety of hierarchically porous zeolites, with different hydrophobic/hydrophilic character, were prepared. Preformed colloidal Pd nanoparticles could be deposited within mesostructured zeolites. This approach enabled the systematic study of key parameters such as zeolite framework, Al content, and the Pd loading while maintaining the same Pd particle size and structure for all the samples. Detailed catalytic studies revealed an optimum hydrophobic/hydrophilic character, and a promising steam-resistant catalyst, namely, 3.2 nm Pd particles supported on mesoporous zeolite beta or USY with a Si/Al ratio of 40, emerged from this multiparametric study with a T 50 of 355 °C and T 90 of 375 °C (where T 50 and T 90 are temperature values at which the samples reach 50% and 90% methane conversion, respectively) in steam-containing reaction conditions. Finally, we verified that the designed catalysts were stable by in-depth postcatalysis characterization and operando diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS) analyses confirming that water adsorbs less strongly on the active PdO surface due to interaction with the zeolite acid sites. This method can be of general use to study how zeolite supports affect the reactivity of supported metals in several catalytic applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Deep Learning for Subgrid‐Scale Turbulence Modeling in Large‐Eddy Simulations of the Convective Atmospheric Boundary Layer

Abstract In large‐eddy simulations, subgrid‐scale (SGS) processes are parameterized as a function of filtered grid‐scale variables. First‐order, algebraic SGS models are based on the eddy‐viscosity assumption, which does not always hold for turbulence. Here we apply supervised deep neural networks (DNNs) to learn SGS stresses from a set of neighboring coarse‐grained velocity from direct numerical simulations of the convective boundary layer at friction Reynolds numbers Re τ up to 1243 without invoking the eddy‐viscosity assumption. The DNN model was found to produce higher correlation between SGS stresses compared to the Smagorinsky model and the Smagorinsky‐Bardina mixed model in the surface and mixed layers and can be applied to different grid resolutions and various stability conditions ranging from near neutral to very unstable. The DNN model can capture key statistics of turbulence in a posteriori (online) tests when applied to large‐eddy simulations of the atmospheric boundary layer.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

The Forward Physics Facility at the High-Luminosity LHC

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF’s physics potential.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Effect of V Content on Corrosion Behavior of Al-V Alloys Produced by Mechanical Alloying and Subsequent Spark Plasma Sintering

Al-V alloys produced via high-energy ball milling have been reported to show simultaneous improvement of corrosion resistance and mechanical properties compared to traditional Al alloys. In these alloys, V content plays a crucial role in increasing or decreasing the corrosion resistance. Therefore, the effect of V and microstructure on corrosion of high-energy ball milled and subsequently spark plasma sintered Al-xV alloys (x = 2, 5, 10 at%) has been studied. Cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopic analysis revealed the increment of V content up to 5 at% enhanced the corrosion resistance of the alloy. However, highly heterogeneous microstructure in Al-10 at%V resulted in significant localized corrosion over the immersion time. The electrochemical impedance spectroscopy studies over 14 days of immersion revealed underlying corrosion mechanisms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Impact of W and Z Production Data and Compatibility of Neutrino DIS Data in Nuclear Parton Distribution Functions

Vector boson production and neutrino deep-inelastic scattering (DIS) data are crucial for constraining the strange quark parton distribution function (PDF) and more generally for flavor decomposition in PDF extractions. We extend the nCTEQ15 nuclear PDFs (nPDFs) by adding the recent W and Z production data from the LHC in a global nPDF fit. The new nPDF set, referred to as nCTEQ15WZ, is used as a starting point for a follow-up study in which we assess the compatibility of neutrino DIS data with charged lepton DIS data. Specifically, we re-analyze neutrino DIS data from NuTeV, Chorus, and CDHSW, as well as dimuon data from CCFR and NuTeV. To scrutinize the level of compatibility, different kinematic regions of the neutrino data are investigated. Fits to the neutrino data alone and a preliminary global fit are performed and compared to nCTEQ15WZ.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Constraining the nuclear gluon PDF with inclusive hadron production data

The nuclear parton distribution functions (nPDFs) of gluons are known to be difficult to determine with fits of deep inelastic scattering (DIS) and Drell-Yan (DY) data alone. Therefore, the nCTEQ15 analysis of nuclear PDFs added inclusive neutral pion production data from RHIC to help in constraining the gluon. In this analysis, we present a new global analysis of nuclear PDFs based on a much larger set of single inclusive light hadron data from RHIC and the LHC. Using our new nCTEQ code (nCTEQ++) with an optimized version of INCNLO we study systematically the limitations of the theory and the impact of the fragmentation function uncertainty.

Duwentäster, Pit↗
DOE OSTI2015

Oxide production program monthly report - December 2014

A summary of the major activities, accomplishments, milestones, financial summary, project performance and issues facing the ARIES Oxide Production Program for the month of December 2014 is presented in this Executive Summary.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Scale up production of carbon fibers from petroleum mesophase pitch

This work investigates the scale-up of pitch precursors for the carbon fiber market using mesophase pitch formulated and produced by Advanced Carbon Products Technologies’ (ACPT’s) patented mesophase pitch processing technology. Through use of its patented process, ACPT developed strategic materials by converting petroleum-based pitch into a high-value, low-cost, carbon-rich feedstock for carbon fiber and other materials critical to our national security. The team successfully developed processing criteria for the tailored mesophase pitch material that can be processed further into precursor and carbon fiber. Processability of the mesophase pitch into precursor and carbon fiber was demonstrated at scale. The resulting materials sequester the carbon that would otherwise be burned and released into the atmosphere, making this an environmentally friendly way to produce these materials in the United States.Pitch-based carbon fibers offer a promising pathway toward cost-effective, high-performance materials for structural and high-modulus composite applications; however, adoption has been limited by challenges in precursor processability and scale-up. In this work, tailored isotropic and mesophase petroleum-derived pitch materials were developed and evaluated for precursor and carbon fiber production through a collaborative effort between Oak Ridge National Laboratory (ORNL) and ACPT. Processing conditions were established at ORNL’s Carbon Fiber Technology Facility to enable stable melt-blowing of pitch-based precursors under continuous operation. Mesophase pitch precursor fibers were produced following oxidation and carbonization, corresponding to a diameter shrinkage of approximately 12%–13% and an estimated mass yield of about 75%–80%. Continuous melt-blowing steady-state operation was demonstrated over time, indicating robust process stability. Melt-blowing was achieved at throughput rates of approximately 20 lb/h⁻¹, validating the commercial viability of petroleum-derived pitch feedstocks for fiber production. Further studies are required to tailor carbon fiber microstructure and properties for specific composite applications.

99 GENERAL AND MISCELLANEOUS↗