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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Piezoelectric Actuation of Graphene-Coated Polar Structures

Ferroelectric materials based on lead zirconate titanate (PZT) are widely used as sensors and actuators because of their strong piezoelectric activity. However, their application is limited because of the high processing temperature, brittleness, lack of conformal deposition, and a limited possibility to be integrated with the microelectromechanical systems (MEMS). Recent studies on the piezoelectricity in the 2-D materials have demonstrated their potential in these applications, essentially due to their flexibility and integrability with the MEMS. In this work, we deposited a few layer graphene (FLG) on the amorphous oxidized Si 3 N 4 membranes and studied their piezoelectric response by sensitive laser interferometry and rigorous finite-element modeling (FEM) analysis. Modal analysis by FEM and comparison with the experimental results show that the driving force for the piezoelectric-like response can be a polar interface layer formed between the residual oxygen in Si 3 N 4 and the FLG. The response was about 14 nm/V at resonance and could be further enhanced by adjusting the geometry of the device. These phenomena are fully consistent with the earlier piezoresponse force microscopy (PFM) observations of the piezoelectricity of the graphene on SiO 2 and open up an avenue for using graphene-coated structures in the MEMS.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Experimental and Computational Investigation of Integrated Internal and Film Cooling Designs Incorporating a Thermal Barrier Coating

Abstract Few studies in the open literature have studied the effect of thermal barrier coatings (TBC) when used in combination with shaped hole film cooling and enhanced internal cooling techniques. The current study presents Reynolds-averaged Navier–Stokes (RANS) conjugate heat transfer simulations that identify trends in cooling design performance as well as experimental measurements of overall effectiveness using a flat-plate matched-Biot number model with a simulated TBC layer of 0.42D thickness, where D is the film cooling hole diameter. Coolant is fed to the film cooling holes in a co-flow configuration, and the results of both the smooth and rib-turbulated channels are compared. At a constant coolant flow rate, enhanced internal cooling was found to provide a 44% increase in spatially-averaged overall effectiveness, $\bar{\bar{\phi}}$, without a TBC. The results show that the addition of a TBC can raise $\bar{\bar{\phi}}$ on a film-cooled component surface by 47%. The optimum velocity ratio was found to decrease with the addition of enhanced cooling techniques and a TBC as the film provided minimal benefit at the expense of reduced internal cooling. While the computational results closely identified trends in overall system performance without a TBC, the model over-predicted effectiveness on the metal–TBC interface. The results of this study will inform turbine component design as material science advances increase the reliability of the TBC.

Engineering↗
DOE OSTI2022

Optical properties of Mo and amorphous MoOx, and application to antireflection coatings for metals

To form antireflection (AR) coatings to hide metal architecture in display technologies, we deposited thin films of metal Mo and oxide MoOx by sputtering targets of various compositions using pure Ar sputter gas. The optical constants [n,k] of these samples were measured by the direct numerical solution of reflectance and transmittance at each wavelength point measured. We find that 50 nm films are uniform in the growth direction, but for thicker 100 nm samples, evidence exists for nonuniform growth, where the top 20 nm appears to be metal rich. From these [n,k], negative Tauc bandgap energies show these oxides are semi-metals. We then identified the specific composition (x) that optimizes the AR response for a host of metals (Al, Cu, Ag, Au). Finally, two methods were used to understand why these MoOx materials function well as AR media, including (i) using phasor rays and (ii) developing a universal expression for the AR condition that applies to both dielectric and metal substrates. In (i), we find two characteristics for AR of metals: (a) its optical thickness should be roughly π3, not the π2 for dielectrics, since for MoOx, their [r^ij,t^ij] Fresnel phases differ from the usual [180°, 0°] of dielectrics; and (b) the medium incorporates a k-dominant strategy whose function is to absorb the energy that is reflected at the AR/metal interface. In (ii), the universal AR condition is found to be r^01+r^12z^=0. For dielectrics, this reduces to the well-known nAR=nairnsub condition. However, for metals, a concise analytic expression is lacking since this expression is highly nonlinear but is easily solved by numerical methods.

Tsu, David V. (ORCID:0000000295903418)↗
DOE OSTI2022

Facile Surface Coatings for Performance Improvement of NMC811 Battery Cathode Material

High nickel content layered oxide LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) is a promising cathode material with a high theoretical capacity of 200 mAh g -1 for use in high energy density lithium-ion batteries. However, its surface can easily get passivated by LiOH and Li 2 CO 3 due to its surface residual Li 2 O being reacting with ambient moisture and CO 2 . Herein, NMC811 was treated in a 3.0 M solution of lithium bis(fluorosulfonyl)imide (LiFSI) in dimethyl carbonate (DMC) at 60 °C for 8 h, 16 h and 24 h, respectively, resulting in coating of the NMC811 surface with LiF due to the basic nature of those residual lithium salts that react with LiFSI. The facile treatment of NMC811 in LiFSI/DMC not only improves the cycling stability but also enhances the capacity of the Li/NMC811 cells, mainly because of the thinning of the Li 2 CO 3 layer as suggested by cyclic voltammograms and impedance analyses. This method opens a new avenue for activation of passivated NMC811 particles for practical battery applications.

25 ENERGY STORAGE↗
DOE OSTI2022

All Solid-State Li/LLZO/LCO Battery Enabled by Alumina Interfacial Coating

Li 7 La 3 Zr 2 O 12 (LLZO) garnet-type lithium-ion conductors are being investigated as a promising solid electrolyte for solid-state lithium batteries. To enable a functional all-solid-state configuration intensive investigations are needed to reduce the cathode/electrolyte interfacial resistance which contributes the most to cell performance loss. Among the commercial cathode materials investigated so far, LiCoO 2 (LCO) is one of the most stable with garnet electrolytes as only a superficial reaction has been detected between the two materials. However, even this minor reaction would block the Li-ion transport through the interface, resulting in deteriorated cell performance. In this work, we demonstrate that a thin aluminum oxide layer (5 nm) can be an effective interlayer to impede the formation of a harmful interphase and enable facile Li-ion transfer between LCO and the LLZO garnet. Room-temperature-sputtered LCO thin films were employed to form an interface with the garnet electrolyte and annealed at 800 °C to reveal the effect of the interfacial reaction on the Li-ion transfer across the interface. An aluminum oxide layer was then introduced between LCO and the garnet electrolyte by sputtering a metallic aluminum layer which is then annealed together with the upper LCO layer in oxygen, or by direct atomic layer deposition of the oxide. Compared to the LCO/LLZO/Li cells without an aluminum oxide interlayer, those with the interlayer exhibited improved performance, i.e., a stable discharge capacity of up to 90 mAh/(g LCO) at a C/10 rate, a rate capability up to 1.68C and a stable galvanostatic cycling at 0.1C for over 100 cycles with a discharge capacity fade rate of 0.15% per cycle. It was determined that aluminum diffused into the LCO layer after preventing the initial detrimental reaction between LCO and the LLZO garnet from happening during high temperature annealing, suggesting that the coating does not have to remain a physically blocking layer during cycling to function.

Electrochemistry↗
DOE OSTI2023

Predictive Modeling of Electrodeposition in a Single Pore Flow-Through Electrode: From Electronucleation to Coating Thickness Uniformity

The emergence of advanced manufacturing methods capable of producing porous three-dimensional structures has expanded the design space for next-generation functional components. The ability to fabricate ordered 3D foams for use in electrocatalysis reactors has increased the need for controlled deposition of catalytic metals onto porous support materials, such as carbon. However, there is a lack of clear design guidelines for electrodeposition onto 3D substrates, due to the geometric complexity and multi-scale nature of the problem. Furthermore, electro-nucleation phenomena are often overlooked in macro-scale models of current distribution during deposition. Here, a graphite flow-through electrode (FTE) is used as a model system for copper deposition within a single pore. Potential distributions and electro-nucleation phenomena are coupled in a continuum level model by incorporating nucleation size and density as a function of overpotential, determined experimentally using in situ atomic force microscopy (AFM). The model predictions are validated by measuring the coating uniformity in the pore using micro-computed X-ray tomography (μCT). A scaling analysis comprising dimensionless parameters such as the Wagner number is presented. The simplified scaling relationship framework can guide the electrodeposition process and electrode design to optimize plating of porous substrates under fluid flow conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Micromechanical Properties of the SiC and Pyrolytic Carbon Layers in Tristructural-Isotropic Coated Particles

Tristructural isotropic (TRISO) coated particle fuel was initially developed for high temperature gas cooled reactors (HTGR) and has been proposed for several other advanced reactor concepts. The design of TRISO particles focuses on preventing the release of fission products in normal and off-normal reactor conditions. The particle design features an actinide bearing fuel kernel that is surrounded by three pyrolytic carbon (PyC) layers and a silicon carbide layer (SiC). The mechanical stability of the particle and fission product retention for both metallic and gaseous fission products depend on the SiC layer. Post irradiation examination (PIE) of TRISO fuel from the first two US DOE Advanced Gas Reactor Fuel Development and Qualification Program irradiation campaigns, AGR-1 and AGR-2, had identified a low rate of particles exhibiting cracking in the SiC layer that did not propagate across the SiC layer. While cracking in the SiC is rare for test conditions and particles associated with the AGR program, understanding the stress state and mechanical properties of the SiC and PyC layers related to particle architecture can aid predicting thermomechanical response of TRISO fuel under the prescribed operation envelope and beyond as well as aiding in the development of similar fuel concepts for other advanced reactors. The presented investigation shows the relationship of the mechanical properties and mechanical response (e.g., understanding crack propagation) of the SiC and PyC layers relative to position within the particle. Testing was conducted on the inner and outer PyC layers of TRISO particles to quantify differences in mechanical behavior.

Montoya, Katherine [ORNL] (ORCID:0000000326955086)↗
DOE OSTI2026

Nanosecond dual-wavelength irradiation effects on laser-induced damage in hafnia coatings

Nanosecond dual-wavelength laser-induced damage was investigated at 1064 nm (1ω) and 355 nm (3ω) on ion-beam-sputtered hafnia single-layer coatings. Single-wavelength 1-on-1 tests were first conducted to establish reference onset fluences. Dual-wavelength tests combined a primary beam with variable fluence at one wavelength and a background, secondary wavelength beam with fixed fluences set to several percentages of the corresponding onset fluence. When 1ω was used as the background irradiation, the perceived damage resistance at 3ω decreased gradually. Here, in contrast, 3ω background irradiation at as little as 10% of the onset fluence led to an ≈ 50% abrupt reduction in the perceived 1ω damage resistance, followed by modest changes upon further increases in 3ω background fluences. Scanning electron microscopy and conversion ratios indicate that 3ω light is the primary driver of damage onset in the case of dual wavelength irradiation. A two-step precursor generation and activation model reproduces the 3ω behavior (1ω as background), but not the strong initial 1ω reduction (3ω as background), suggesting additional 3ω-induced precursors that saturate at low fluence.

Optics and optical instruments↗
DOE OSTI2020

High efficiency Al/Sc-based multilayer coatings in the EUV wavelength range above 40 nanometers

In this Letter, we have developed new and highly efficient periodic multilayer mirrors Al/Sc, Al/Sc/SiC, and Mo/Al/Sc with optimized reflectance at wavelengths between 40 and 65 nm. We have reached record values in measured peak reflectance: 57.5% at 44.7 nm and 46.5% at 51 nm, with Al/Sc/SiC at near-normal incidence. Furthermore, to the best of our knowledge, we have achieved the largest reported bandwidth with Mo/Al/Sc at 57 nm and the narrowest bandwidth with Al/Sc at a 60 nm wavelength. These new and promising results demonstrate that Al/Sc-based multilayer coatings are excellent candidates for future generations of extreme ultraviolet (EUV) instruments for solar physics, EUV lasers, and attosecond science, in a wavelength range that has not been fully explored.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Probing rutile solid-phase crystallization of atomically mixed Mn-alloyed TiO 2 coatings through XANES analysis

Phase transformation via dopant introduction is an emerging strategy for tuning the electronic and catalytic properties of oxides. However, developing a general theory of ternary alloys and their microstructure evolution remains challenging due to the knowledge gaps in how point defects such as dopants lead to the formation of complex or metastable phases. We investigate the influence of Mn concentration and annealing temperature on the microstructure evolution of amorphous Mn-alloyed TiO 2 synthesized via Atomic Layer Deposition. In conclusion, our findings reveal a new crystallization pathway resulting in a direct amorphous TiO 2 to rutile transformation without an intermediate anatase phase and our multi-parameter thermal processing conditions show potential for AI-assisted data acquisition and analysis for studying complex oxide coatings.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Seeing through nuclear fuel: Three-dimensional, nondestructive X-ray microscopy and volumetric analyses of neutron-irradiated TRISO-coated fuel kernels

The three-dimensional (3D) characterization of nuclear fuel with X-ray microscopy has historically proven difficult, due to uranium’s high attenuation of easily accessible X-rays, both in a laboratory setting and at a synchrotron user facility. However, this imaging modality provides nondestructive information that can be used to investigate morphological changes arising from external stimuli (e.g., neutron irradiation, high-temperature testing). Using an appropriate X-ray energy spectrum and an adequate X-ray filter, suitable transmissions through properly sized nuclear fuel specimens can be achieved. Here, in this study, we present the methods and results of using a commercially available, laboratory-based X-ray microscope (XRM) to examine the extent of 3D morphological changes of tristructural isotropic (TRISO)-coated fuel particles, specifically uranium oxide/uranium carbide fuel kernels, after high-temperature neutron irradiation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

SBV: Characterization of Highly Reflective EUV Coatings (CRADA AWD00002394)

The overall goals were to support the development of new high efficiency EUV coatings which would dramatically reduce the energy needed in the semiconductor manufacturing lithography process as well as dramatically reducing the cost of future EUV lithography tools. The project was successful in the characterization of numerous samples generating many hundreds of datasets and critical feedback for the partner’s internal material development program.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Recipe for coating ceramic blades for ion trapping

The first batches of ion traps patterned and coated were processed per the standard 3-step clean, air fire, and metallization processes. The third or fourth lot using this process resulted in poorly adhering metallization. Up until this point, the standard process was used to metallize and pattern ceramic ion traps without fail. At about the 4th batch of parts something changed. After the 5th batch, the ceramic ion traps received generally came with some unknown contamination that does not come off in a standard 3-step clean (Lenium Vapor Degreaser, Acetone, IPA) and air fire (860C for 1 hour) for which this process removes the vast majority of all contamination for most ceramic metallization. This is highly unusual. Using HF + Boiling H 2 O 2 is extreme for cleaning the ceramic ion traps. The contamination was never identified and is stubborn to effectively clean. Standard as-fired ceramic should be very easy to clean as if s fired at temperatures greater than 1400°C and not much in terms of contamination should exist at these temperatures, so there must be an intermediate step/process which is imparting this contamination. It is likely a polishing compound or previous polishing contaminant, but also not easily visually distinguishable until after metallization. The halo marks observed on parts might be fingerprints (less likely) or potential polishing marks (more likely) as metallization typically doesn't cover/hide any damage or contamination, but rather quite clearly the opposite, it accentuates it. Blotchy appearances in the metallization usually indicated an adhesion issue. As a result of the fragility of the parts (yield loss due to handling) and difficulty in identifying the contamination during cleaning, we have taken a conservative approach of HF + H 2 O 2 cleaning for all batches after the contamination and adhesion issues were identified.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Scale-Up of Electrode Coating and Flow-Field for Commercial Hydrogen Peroxide Electrolyzer: Cooperative Research and Development Final Report, CRADA Number CRD-17-00687

Hydrogen peroxide is currently produced at central chemical plants via the anthraquinone oxidation process. This process produces environmental pollutants that are costly to remediate, requires hazardous long distance shipping of highly concentrated peroxide (50% or 70%), and necessitates extra handling costs related to storage and dilution. Peroxygen Systems, Inc. (PSi) is developing breakthrough technology for on-site hydrogen peroxide production. PSi’s on-site on-demand electrolyzer can reduce the cost of producing hydrogen peroxide by 50%, while also completely eliminating the cost and safety issues associated with shipping and handling of high concentration hydrogen peroxide. The challenge for PSi is scaling. To support the next step toward commercialization (customer pilot tests), scaling the prototype into larger single cells and 20-40 cell stacks is required. In addition to internal hardware and flow-field design efforts at PSi, NREL will address three critical problems for this scale-up effort: (1) demonstrating a large scale roll-to-roll (R2R) process to coat uniform electrode materials for 100 cm2 and 500 cm2 stack testing, (2) demonstrating an in-line diagnostic to achieve better electrode quality control, and (3) performing in situ cell/stack testing to better understand and optimize the performance of the flow field design.

28 EE - Advanced Manufacturing Office (EE-5A)↗
DOE OSTI2026

Performance of Quantum Dot Coatings for Luminescent Solar Concentrating Windows: Cooperative Research and Development Final Report, CRADA Number CRD-16-00640

The two major outcomes from this DOE supported collaboration between UbiQD and NREL were: 1) an expert analysis/modeling of the expected performance and cost of luminescent solar concentrating windows with quantum dot coatings, and 2) critical R&D characterization of materials and device performance analysis using equipment and processes that are too expensive for UbiQD to perform in-house. The latter also included third-party validation of the device performance with an NREL-certified conversion efficiency that was ultimately published. (see ACS Energy Lett. 2018 and recently ACS Appl. Energy Mater. 2020).

14 SOLAR ENERGY↗
DOE OSTI2021

Power Cylinder Friction Reduction Through Coatings, Surface Finish and Design

About 7-10% of the total energy input in a vehicle is lost due to mechanical friction, and in an engine, about 50% of the total frictional losses occur at the interface between the cylinder and pistons and piston rings. Therefore, this interface offers great opportunities for friction reduction. The goal of this proposed study is to demonstrate friction reduction potential using advanced coatings, surface finish, and design on power cylinder system containing cylinder bore, piston rings, crankshaft, and advanced engine oils. Experience through years of research in this area lead us to believe that full benefit potential can be realized only by considering a systems approach.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2021

Adhesion of Titanium Coatings on Additively Manufactured Stainless Steel [Slides]

Additive manufacturing can improve fuel cell development by increasing design development speed, enabling complex designs through more flexible fabrication, and reducing wasted excess material. The goal of the project is to develop a process for strongly adhering a coating of titanium to additively manufactured stainless steel.

36 MATERIALS SCIENCE↗