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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 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Mechanisms of Interfacial Mixing in the Blown Powder Deposition of Inconel 625 to Copper Alloy for Liquid Rocket Engine Applications

There is an increasing need for functional materials to support high heat flux applications and optimize weight by using bimetallic additive manufacturing (AM). While one promising fabrication technology is the use of blown powder directed energy deposition (DED) AM, challenges remain with bi-metallic combinations. Prominent among these challenges is the need to understand mixing of materials at the bimetallic interface for forming stronger, more durable and reliable joints to extend the versatility of AM into critical applications. One application is the manufacturing of combustion chambers with copper-alloy liners and Superalloy structural jackets. In this application, material combinations are selected for effective heat dissipation, using copper, and retention of strength at high temperatures using Inconel 625. Currently, the dominant problem with this configuration is the highly variable strength of the interface and its correlation with deposition parameters. In this study, samples were fabricated at several vendors with Inconel 625 deposited onto wrought C-18150 (Cu-Cr-Zr) to form a bimetallic interface. Characterization of the interfaces were achieved through optical and electron microscopy, mechanical testing of mini tensile specimens, and electron dispersion spectroscopy to understand diffusion and bulk mixing behaviors at the joint. A theoretical framework was constructed in the context of solidification and mixing mechanisms to explain the resulting differences in the interface. This qualitative approach utilized a fluid dynamics perspective to sum the order of magnitudes of the various acting forces on the weld pool during deposition to predict convection trends based off known parameters. The predicted trends for each vendor are compared to obtain a better understanding of how mixing in the molten pool varied based on deposition parameters.

Additive Manufacturing↗
DOE OSTI2019

Spall and re-compaction in OFHC copper under high velocity impact

Copper spall and re-compaction experiments were performed with a single stage large bore (76.2 mm) light gas gun capable of planar impacts at low impact velocity. The experiments used PDV to capture the velocity history of the back surface of the target and the projectile velocity (collimating probes). The tilts for these experiments typically range from 1–2 mrad. A re-compaction wave was clearly observed using Photon Doppler Velocimetry (PDV) on the back surface of the copper target as well as identified using Electron Backscatter Diffraction (EBSD) in the recovered samples. The spall and re-compaction data are similar until re-compaction occurs; the time-resolved data show clear evidence for spall damage in the first case and spall followed by re-compaction in the second case. For the initial spall signature, ringing consistent with half the thickness of the target is observed in all cases; after re-compaction, ringing is observed that is consistent with the full sample thickness. Samples recovered using the soft catch system were analyzed, and the cross-sectional view from the spalled target clearly showed a spall plane with voids, whereas the re-compaction target showed an area of plastic deformation. It is hypothesized that the voids formed by spall close during re-compaction and leave behind a deformed area.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Time-Resolved Radioluminescence of the Polynuclear Copper(I) Phosphor Cu4I6²–. Different Temporal responses to Photo, X-Ray, β-Ray and α-Particle Excitation

Described for the first time are the time-resolved radioluminescence (TRRL) properties of the highly luminescent copper(I) cluster Cu4I62– using X-ray, b-ray and a-particle excitation. The copper(I) phosphors are two crystalline salts of this anion, [Na2(18-crown-6)2(H2O)3][Cu4I6] (I) and [Li(benzo-15-crown-5)2(H2O)]2[Cu4I6] (II), that had been shown to display strong photoluminescence (PL) when excited with ultraviolet light. The integrated radioluminescence (RL) spectra observed when pulsed X-rays were used as the excitation source are virtually the same as the PL spectra under comparable conditions. These temporal RL spectra are invariant at all observation times indicating that the observed scintillation occurs from a common excited state (or set of excited states). When the TRRL is collected from excitation with a pulsed X-ray source, b-ray decay from 90Sr or a-decay from 244Cm, the longer components (>2 μs) of the TRRL displayed (in each case) lifetimes comparable to those of the strictly exponential PL decays recorded under pulsed laser UV excitation. However, at shorter observation times (< 500 ns), the RL decay deviated from the exponential model, indicating a markedly different temporal luminescence behavior when these materials were excited with pulsed high energy radiation. Furthermore, this effect was the most pronounced for the a-particle excitation. These results suggest that the absorption of a very high energy X-ray photon, b-ray or a-particle at a site within the crystalline solid leads to a high local density of electronic excited states and that coupling between these states provides an alternative channel for excited state decay. Given that the patterns observed

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2016

Prompt Neutron Decay Constants in a Highly Enriched Uranium-Lead Copper Reflected System

Rossi-{alpha} measurements were performed on highly enriched uranium (HEU)-lead copper reflected systems to determine the prompt neutron decay constants. These constants represent an eigenvalue characteristic of these particular critical configurations, which can be experimentally measured by the Rossi-a or pulse neutron source techniques and calculated by a deterministic or Monte Carlo method. In the measurements presented in this summary, highly enriched uranium interleaved with lead plates and reflected with copper were assembled to a high multiplication and the prompt neutron decay constants were determined by the Rossi-{alpha} technique. This research intended to benchmark the lead neutron cross sections; it was a collaboration between the Japanese Atomic Energy Agency (JAEA) Fast Critical Assembly Facility (FCA) in Tokai, Japan and the Los Alamos National Laboratory (LANL) in the U.S. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2024

Exploring the Performance and Reliability of Screen-Printable Fire-Through Copper Paste on PERC Solar Cells

For 40 TW of PV required to transition our planet to 100% renewables, the silver (Ag) should disappear from PV production. Advantages of copper (Cu) over silver (Ag) include 1) bulk Cu has a similar conductivity to Ag (1.7 mu O-cm for Cu, 1.6 mu O-cm for Ag) and 2) Cu is approximately 100 times cheaper than Ag, making it an excellent potential replacement. Problems associated with copper (Cu) contacts include 1) easy oxidation and 2) diffusion into the Si cell and recombination activity.

copper paste↗
DOE OSTI2011

Hyperfine field and hyperfine anomalies of copper impurities in iron

A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from experiments involving {beta}-NMR on oriented nuclei on {sup 59}Cu, {sup 69}Cu, and {sup 71}Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e., B{sub hf}(CuFe) = -21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be {sup 59{Delta}69}=0.15(9)% and {sup 71{Delta}69}=0.07(11)%.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Cysteine Mutants of the Major Facilitator Superfamily-Type Transporter CcoA Provide Insight into Copper Import

Copper (Cu) is a redox-active micronutrient that is both essential and toxic. Its cellular homeostasis is critical for supporting cuproprotein maturation while avoiding excessive oxidative stress. The Cu importer CcoA is the prototype of the widespread CalT subfamily of the MFS-type transporters. Hence, understanding its molecular mechanism of function is significant. Here, we show that CcoA undergoes a thiol:disulfide oxidoreduction cycle, which is important for its Cu import activity.

MFS-type transporters↗
DOE OSTI2017

Extreme Two‐Phase Cooling from Laser‐Etched Diamond and Conformal, Template‐Fabricated Microporous Copper

Abstract This paper reports the first integration of laser‐etched polycrystalline diamond microchannels with template‐fabricated microporous copper for extreme convective boiling in a composite heat sink for power electronics and energy conversion. Diamond offers the highest thermal conductivity near room temperature, and enables aggressive heat spreading along triangular channel walls with 1:1 aspect ratio. Conformally coated porous copper with thickness 25 µm and 5 µm pore size optimizes fluid and heat transport for convective boiling within the diamond channels. Data reported here include 1280 W cm −2 of heat removal from 0.7 cm 2 surface area with temperature rise beyond fluid saturation less than 21 K, corresponding to 6.3 × 10 5 W m −2 K −1 . This heat sink has the potential to dissipate much larger localized heat loads with small temperature nonuniformity (5 kW cm −2 over 200 µm × 200 µm with <3 K temperature difference). A microfluidic manifold assures uniform distribution of liquid over the heat sink surface with negligible pumping power requirements (e.g., <1.4 × 10 −4 of the thermal power dissipated). This breakthrough integration of functional materials and the resulting experimental data set a very high bar for microfluidic heat removal.

Palko, James W.↗
DOE OSTI2021

2D Copper Tetrahydroxyquinone Conductive Metal–Organic Framework for Selective CO 2 Electrocatalysis at Low Overpotentials

Abstract Metal–organic frameworks (MOFs) are promising materials for electrocatalysis; however, lack of electrical conductivity in the majority of existing MOFs limits their effective utilization in the field. Herein, an excellent catalytic activity of a 2D copper (Cu)‐based conductive MOF, copper tetrahydroxyquinone (CuTHQ), is reported for aqueous CO 2 reduction reaction (CO 2 RR) at low overpotentials. It is revealed that CuTHQ nanoflakes (NFs) with an average lateral size of 140 nm exhibit a negligible overpotential of 16 mV for the activation of this reaction, a high current density of ≈173 mA cm −2 at −0.45 V versus RHE, an average Faradaic efficiency (F.E.) of ≈91% toward CO production, and a remarkable turnover frequency as high as ≈20.82 s −1 . In the low overpotential range, the obtained CO formation current density is more than 35 and 25 times higher compared to state‐of‐the‐art MOF and MOF‐derived catalysts, respectively. The operando Cu K‐edge X‐ray absorption near edge spectroscopy and density functional theory calculations reveal the existence of reduced Cu (Cu + ) during CO 2 RR which reversibly returns to Cu 2+ after the reaction. The outstanding CO 2 catalytic functionality of conductive MOFs (c‐MOFs) can open a way toward high‐energy‐density electrochemical systems.

Majidi, Leily↗
DOE OSTI2019

Rb 2 CuX 3 (X = Cl, Br): 1D All-Inorganic Copper Halides with Ultrabright Blue Emission and Up-Conversion Photoluminescence

All-inorganic metal halides such as Cs 4 PbX 6 and CsPbX 3 (X = Cl, Br, and I) are attracting global attention owing to their promise in optoelectronic applications. However, the presence of the toxic heavy metal lead (Pb) in these materials is a major concern. In this work, a family of nontoxic high-efficiency blue-emitting all-inorganic halides Rb 2 CuX 3 (X = Br and Cl) is reported; the compounds exhibit 1D crystal structures featuring anionic $^1_∞[CuX_3]$ 2- ribbons separated by Rb + cations. The measured record high photoluminescence quantum yield values range from 64% to 100% for Rb 2 CuBr 3 and Rb 2 CuCl 3 , respectively. Furthermore, the measured emission linewidths are quite narrow with full width at half maximum values of 54 and 52 nm for Rb 2 CuBr 3 and Rb 2 CuCl 3 , respectively. Single crystals of Rb 2 CuCl 3 demonstrate an anti-Stokes photoluminescence signal, shown for the first time for Pb-free metal halides. The discovery of highly efficient narrow blue emitters based on a nontoxic and inexpensive metal copper paves a way for the consideration of low-cost and environmentally friendly copper halides for practical applications.

1D metal halide↗
DOE OSTI2022

Copper Complexes with Diazoolefin Ligands and their Photochemical Conversion into Alkenylidene Complexes

Abstract Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of Cu I complexes with N‐heterocyclic diazoolefin ligands. The complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature.

Kooij, Bastiaan↗
DOE OSTI2015

Lethal and sublethal measures of chronic copper toxicity in the eastern narrowmouth toad, Gastrophryne carolinensis

Abstract Many metals are acutely toxic to aquatic organisms at high concentrations and for some metals, such as copper (Cu), even low‐level chronic contamination may be cause for conservation concern. Amphibian susceptibility to Cu has been examined in only a few species, and susceptibility is highly variable. The lethal and sublethal effects were examined of chronic aqueous Cu exposure on embryonic and larval eastern narrowmouth toads, Gastrophryne carolinensis . Copper levels as low as 10 μg Cu/L reduced embryonic and larval survival. Embryonic survivorship varied within‐ and between‐source populations, with embryos derived from uncontaminated‐wetland parents having greater survival at lower Cu levels than embryos from parents from a metal‐contaminated constructed wetland. At 30 μg/L, embryos from the contaminated site had greater survival. Overall survival from oviposition to metamorphosis was 68.9% at 0 μg/L and 5.4% at 10 μg/L. Similarly, embryos exposed to ≥50 μg/L demonstrated developmental delays in transition from embryo to free‐swimming larva. These results demonstrate a negative population‐specific response to environmentally relevant levels of Cu. Environ Toxicol Chem 2015;34:575–582. © 2014 SETAC

Flynn, R. Wesley↗
DOE OSTI2018

Combined Mini-Cylex & Disk Acceleration Tests in Type K Copper

In this work, we combined the miniature cylinder expansion test (Mini-Cylex), with the Disk Acceleration Test (DAX) using Type K copper, Picatinny Liquid Explosive, and photonic Doppler velocimetry. We estimated the CJ state using plate reverberation methods at the test cap. We extracted velocities at 2, 7, and 10 volume expansions to fit Jones-Wilkins-Lee Equation of State and estimated Gurney velocity at the tube wall. The test also provides an additional method to estimate reaction products Hugoniot through knowledge of the copper test cap. Our experiments and simulations are within expected uncertainty. Lastly, the test and the analysis effectively reduce costs while keeping or increasing fidelity.

42 ENGINEERING↗
DOE OSTI2021

Time-Resolved Grazing Incidence X-Ray Absorption Spectroscopy for the In Situ Investigation of the Initial Stages of Sputter-Deposited Copper Thin Films

The sputter deposition and the growth of thin copper films on float glass substrates are in situ studied using grazing incidence, reflection mode X-ray absorption fine structure spectroscopy with subsecond time resolution. The experimental data are compared with model calculations, assuming the presence of crystalline, face-centered cubic metallic Cu nanostructures. From a detailed analysis of the measured spectra, the film thickness as well as the surface roughness is determined, leading to a detailed understanding of the films growth as a function of the sputter deposition time. In particular, different stages of film growth can clearly be distinguished from the fits of the experimental data. The results suggest the formation of isolated, approximately nm-sized copper clusters in the initial phase of the film deposition for the first few seconds, a coalescence phase with a nominal thickness of ≈1.5–2.8 nm, constant roughness of about 1.4 nm for the subsequent ≈5 s, and finally 3D growth of the Cu crystallites in the film for later stages of film growth. Further prospects of the methodology are given.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Electrochemically Dealloyed 3D Porous Copper Nanostructure as Anode Current Collector of Li-Metal Batteries

The commercialization of high-energy Li-metal batteries is impeded by Li dendrites formed during electrochemical cycling and the safety hazards it causes. Here, a novel porous copper current collector that can effectively mitigate the dendritic growth of Li is reported. This porous Cu foil is fabricated via a simple two-step electrochemical process, where Cu-Zn alloy is electrodeposited on commercial copper foil and then Zn is electrochemically dissolved to form a 3D porous structure of Cu. The 3D porous Cu layers on average have a thickness of ≈14 um and porosity of ≈72%. This current collector can effectively suppress Li dendrites in cells cycled with a high areal capacity of 10 mAh cm -2 and under a high current density of 10 mA cm -2 . This electrochemical fabrication method is facile and scalable for mass production. In conclusion, results of advanced in situ synchrotron X-ray diffraction reveal the phase evolution of the electrochemical deposition and dealloying processes.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Modification of Jet Velocities in an Explosively Loaded Copper Target with a Conical Cavity

Here, in this work, the design and execution of an experiment with the goal of demonstrating control over the evolution of a copper jet is described. Simulations show that when using simple multi-material buffers placed between a copper target with a conical cavity and a cylinder of high-explosive, a variety of jetting behaviors occur based on material placement, including both jet velocity augmentation and mitigation. A parameter sweep was performed to determine optimal buffer designs in two configurations. Experiments using the optimal buffer designs verified the effectiveness of the buffers at altering jet velocities. Similar trends were shown between the experimental results and the modeling.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Nanoscale conditions for ductile void nucleation in copper: vacancy condensation and the growth-limited microstructural state

Ductile rupture or tearing usually involves structural degradation from the nucleation and growth of voids and their coalescence into cracks. Although some materials contain preexisting pores, the first step in failure is often the formation of voids. Because this step can govern both the failure strain and the fracture mechanism, it is critical to understand the mechanisms of void nucleation and the enabling microstructural configurations which give rise to nucleation. To understand the role of dislocations during void nucleation, the present study presents ex-situ cross-sectional observations of interrupted deformation experiments revealing incipient, subsurface voids in a copper material containing copper oxide inclusions. The local microstructural state was evaluated using electron backscatter diffraction (EBSD), electron channeling contrast (ECC), transmission electron microscopy (TEM), and transmission kikuchi diffraction (TKD). Surprisingly, before substantial growth and coalescence had occurred, the deformation process had resulted in the nucleation of a high density of nanoscale (≈50 μm) voids in the deeply deformed neck region where strains were on the order of 1.5. Such a proliferation of nucleation sites immediately suggests that the rupture process is limited by void growth, not nucleation. With regard to void growth, analysis of more than 20 microscale voids suggests that dislocation boundaries facilitate the growth process. The present observations call into question prior assumptions on the role of dislocation pile-ups and provide new context for the formulation of revised ductile rupture models. While the focus of this study is on damage accumulation in a highly ductile metal containing small, well-dispersed particles, these results are also applicable to understanding void nucleation in engineering alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Transition in helium bubble strengthening of copper from quasi-static to dynamic deformation

Damage from low-temperature irradiation and the subsequent degradation of materials performance pose significant challenges for the storage of radioactive materials and for peripheral components in some nuclear reactor designs. Fully understanding the mechanical behavior of such materials requires test data for strain rates in both the quasi-static (< 10/s) and dynamic (>> 10/s) regimes. While dynamic testing has generally been avoided in the past for neutron irradiated (contamination concerns) and ion irradiated (insufficient volume) materials, surface-sensitive Richtmyer-Meshkov instability (RMI) tests were used in the present work to overcome these limitations. Here, nanopillar compression, nanoindentation, and RMI testing data from a helium implanted surface layer (~10 µm thick) were compiled to explore the effects of helium bubbles on the materials strength of high-purity copper at strain rates of 0.001/s – 10 8 /s. While nano-mechanical testing revealed increases in yield strength and hardness with increasing helium dose from 1000 to 4000 appm He, RMI indicated no significant changes in strength as compared to unimplanted copper. Here, this discrepancy in behavior was rationalized through a combination of recent literature and follow-on molecular dynamics (MD) simulations, leading to the conclusion that the nanoscale helium bubbles acting as dispersed barriers to dislocation motion at quasi-static strain rates collapse under shock loading and cease to be effective barriers at high strain rates.

36 MATERIALS SCIENCE↗