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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Layer thickness dependent strain rate sensitivity of Cu/amorphous CuNb multilayer

We report strain rate sensitivity of crystalline materials is closely related to dislocation activity. In the absence of dislocations, amorphous alloys are usually considered to be strain rate insensitive. However, the strain rate sensitivity of crystalline/amorphous composites is rarely studied, especially at nanoscale. In this study, we show that the strain rate sensitivity of Cu/amorphous CuNb multilayers is layer thickness dependent. At small layer thickness (below 50 nm), the multilayers demonstrate limited strain rate sensitivity; at relatively large layer thickness (above 100 nm), the strain rate sensitivity of multilayers is close to that of the single layer Cu film. Finally, mechanisms that lead to size dependent variation of strain rate sensitivity in these multilayers are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Spontaneous formation of highly periodic nano-ripples in inclined deposition of Mo/Si multilayers

We investigated the growth of Mo/Si multilayers (ML) deposited using a highly collimated flux of ion-beam sputtered particles for a wide range of deposition angles. Growth of the multilayers at normal and moderately inclined deposition is dominated by surface relaxation resulting in smooth interfaces of the multilayer stack. The first signs of interface roughening are observed at a deposition angle of 45° with respect to the normal to the substrate surface. At an oblique angle of 55°, the ML interfaces undergo fast progressive roughening from the substrate to the top of the ML stack, leading to the formation of ripples which are perpendicular to the deposition flux direction. Deposition of the multilayer at an angle of 65° results in a highly periodic lateral ripple structure with a period of 10 nm. The mature ripple pattern forms during growth of only the first few layers and then stabilizes. The ripples propagate through the whole ML stack with almost no changes in frequency and amplitude, resulting in a highly periodic bulk array composed of silicon and molybdenum nano-rods closely packed in a 6-fold symmetric lattice. Here, we present a simple model for the ripple growth, which gives results that are in good agreement with experimental data.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A diffusion-limited reaction model for self-propagating Al/Pt multilayers with quench limits

A diffusion-limited reaction model was calibrated for Al/Pt multilayers ignited on oxidized silicon, sapphire, and tungsten substrates, as well as for some Al/Pt multilayers ignited as free-standing foils. The model was implemented in a finite element analysis code and used to match experimental burn front velocity data collected from several years of testing at Sandia National Laboratories. Moreover, both the simulations and experiments reveal well-defined quench limits in the total Al + Pt layer (i.e., bilayer) thickness. At these limits, the heat generated from atomic diffusion is insufficient to support a self-propagating wave front on top of the substrates. Quench limits for reactive multilayers are seldom reported and are found to depend on the thermal properties of the individual layers. Here, the diffusion-limited reaction model is generalized to allow for temperature- and composition-dependent material properties, phase change, and anisotropic thermal conductivity. Utilizing this increase in model fidelity, excellent overall agreement is shown between the simulations and experimental results with a single calibrated parameter set. However, the burn front velocities of Al/Pt multilayers ignited on tungsten substrates are over-predicted. Finally, possible sources of error are discussed and a higher activation energy (from 41.9 kJ/mol.at. to 47.5 kJ/mol.at.) is shown to bring the simulations into agreement with the velocity data observed on tungsten substrates. Finally, this higher activation energy suggests an inhibited diffusion mechanism present at lower heating rates.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Design of multilayer-based diagnostics for measurement of high energy x rays and gamma rays

We investigate several possible multilayer-based optic designs for future hard x-ray and gamma ray diagnostics, including the detection and measurement of the positron annihilation radiation at 511 keV. The focus is set on increasing the photon efficiency and signal-to-noise ratio, compared to a previous multilayer-based system that was successfully employed to measure spectra in the 55 keV–100 keV range. Several possible designs using multilayer coatings are discussed, including mirror-based optics and multilayer Laue lenses.

Burcklen, C. (ORCID:0000000271566357)↗
DOE OSTI2023

Effects of diffusion barriers on reaction wave stability in Co/Al reactive multilayers

Bimetallic, reactive multilayers are uniformly structured materials composed of alternating sputter-deposited layers that may be ignited to produce self-propagating mixing and formation reactions. These nanolaminates are most commonly used as rapid-release heat sources. The specific chemical composition at each metal/metal interface determines the rate of mass transport in a mixing and formation reaction. The inclusion of engineered diffusion barriers at each interface will not only inhibit solid-state mixing but also may impede the self-propagating reactions by introducing instabilities to wavefront morphology. Here, this work examines the effect of adding diffusion barriers on the propagation of reaction waves in Co/Al multilayers. The Co/Al system has been shown to exhibit a reaction propagation instability that is dependent on the bilayer thickness, which allows for the occurrence of unstable modes in otherwise stable designs from the inclusion of diffusion barriers. Based on the known stability criteria in the Co/Al multilayer system, the way in which the inclusion of diffusion barriers changes a multilayer's heat of reaction, thermal conductivity, and material mixing mechanisms can be determined. These factors, in aggregate, lead to changes in the wavefront velocity and stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Measurements of the inert Hugoniot and observation of mechanical ignition in Ni(V) + Al reactive multilayers via x-ray diffraction

This study investigates the inert Hugoniot response, mechanical ignition, and reaction dynamics of Ni(V)+Al multilayers during longitudinal, laser-driven shock compression experiments. Ni(V)+Al multilayers, known for their self-propagating exothermic reactions, were subjected to longitudinal stresses exceeding 50 GPa using the laser shock facility within the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS). In situ x-ray diffraction (XRD) revealed that Ni(V) and Al were not in equilibrium during compression, with stress discrepancies attributed to twinning, grain structure effects, and/or dislocation density. However, the measured inert Hugoniot closely matched prior experimental and computational studies, confirming the utility of XRD for measuring the equation of state of thin, complex materials. Additionally, reaction was observed at significantly higher stresses than reported previously using laser-launched flyers. This discrepancy suggests a strong influence of externally imposed shear stress on reaction thresholds, which likely arose from deviations in flyer planarity during past experiments. Full reaction of the multilayer occurred within 40 ns after shock-wave passage, evidenced by complete melting of the constituents. Eulerian hydrocode simulations replicated experimental conditions, providing insights into equilibrium dynamics and experimental artifacts. The results highlight how even small shear forces facilitate ignition in Ni(V)+Al multilayers at lower stresses.

Crystallography↗
DOE OSTI2020

Features of multilayer mirror application for focusing and collimating X-rays from inverse Compton scattering sources

We have analysed the use of X-ray interference multilayer mirrors as the elements of a focusing scheme for a compact source based on inverse Compton scattering. An algorithm is proposed for selecting mirror parameters, which takes into account the properties of the radiation source. The dependence of wavelength on the viewing angle and the energy line broadening for a fixed viewing angle are found to be the main limitations in the use of multilayer mirrors. Efficient radiation collection calls for the application of broadband mirrors. It is shown that the efficiency of multilayer mirrors in a Kirkpatrick – Baez X-ray focusing setup exceeds that of total external reflection mirrors by an order of magnitude, and that stack multilayer mirrors offer a small advantage over the periodic ones. The overall efficiency of source radiation collection in the photon energy range ΔE = 10 – 12 keV amounts to 12 % for the two-mirror Kirkpatrick – Baez setup. For a spectral region with a bandwidth ΔE/E = 3 %, the efficiency ranges up to 69 %. (paper)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

Limiting spectral and angular characteristics of multilayer relief – phase diffraction microstructures

Methods for estimating the parameters of relief – phase diffraction microstructures (local and integral Q-factors) are extended to the case of multilayer double-relief sawtooth microstructures, which makes it possible to select the best combinations of optical materials for multilayer microstructures at a very low computational burden. An approach to the study of multilayer microstructures is proposed, based on the combined use of Q-factors and the method of rigorous analysis of coupled waves, which allows one to estimate the limiting spectral and angular characteristics of multilayer microstructures of various types. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Evolution of topological skyrmions across the spin reorientation transition in Pt/Co/Ta multilayers

Magnetic skyrmions in multilayers are particularly appealing as next generation memory devices due to their topological compact size, the robustness against external perturbations, the capability of electrical driving and detection, and the compatibility with the existing spintronic technologies. To date, Néel-type skyrmions at room temperature (RT) have been studied mostly in multilayers with easy-axis magnetic anisotropy. Here in this paper, we systematically broadened the evolution of magnetic skyrmions with sub-50-nm size in a series of Pt/Co/Ta multilayers where the magnetic anisotropy is tuned continuously from easy axis to easy plane by increasing the ferromagnetic Co layer thickness. The existence of nontrivial skyrmions is identified via the combination of in situ Lorentz transmission electron microscopy (L-TEM) and Hall transport measurements. A high density of magnetic skyrmions over a wide temperature range is observed in the multilayers with easy-plane anisotropy, which will stimulate further exploration for new materials and accelerate the development of skyrmion-based spintronic devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Multilayer, Multimaterial Thermal Barrier Coating Systems: Design, Synthesis, and Performance Assessment

Thermal barrier coatings ( TBC s) are increasingly playing a vital role in enhancing efficiency and performance of gas turbine engines. As engine operating temperatures rise, yttria‐stabilized zirconia ( YSZ ), the currently principal TBC material, reaches its operational limits. Gadolinium Zirconate ( GDZ )‐based pyrochlore oxides are now emerging contenders, not only due to their lower thermal conductivity, but also their ability to resist attack by silicate deposits. However, GDZ cannot be directly substituted for YSZ due to its incompatibility with the thermally grown alumina layer, therefore requiring to be a component of multilayer system. Although industry has already adopted these materials in various applications, a number of fundamental issues arise with respect to layered‐coating design, their properties and processing dependence. In this study several multilayer architectures, based on the YSZ – GDZ system, have been developed and tested for durability under furnace thermal cycling conditions. Coating designs considered optimization of microstructure and properties of individual layers based on their location within the top‐coat thickness to address competing interests of thermal conductivity, compliance, and resistance to silicates. A large variance in durability was observed in coatings made with different multilayer designs. The results and the associated failure mechanisms are rationalized through preliminary evaluation of elastic energies at the failure locations and corresponding energy release rates. The results point to new strategies in the design and manufacturing of optimal multilayer coatings.

Viswanathan, Vaishak↗
DOE OSTI2019

Impact of high refractive coating material on the nodular-induced electric field enhancement for near infrared multilayer mirrors

Electric field enhancement due to nodular defects within quarter-wave optical thickness multilayer mirrors is impacted by the inclusion diameter, inclusion depth, inclusion composition, nodular shape, multilayer angular bandwidth, multilayer coating materials, number of layers, angle of incidence, and polarization. In this study, the electric field enhancement for surface inclusions with diameters up to 2 µm irradiated at 1064 nm at either normal or 45 deg incidence is calculated for high refractive index materials over a refractive index range of 1.7–2.3 for oxide materials commonly used in the near infrared. The thicknesses of the multilayer mirror thin films are determined for each high refractive index material by a requirement to meet a 99.5% reflection. The refractive index was found to have a significant impact on the electric field enhancement, which may offer some insight into the optimal material choice to produce high laser damage threshold mirrors.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Fabrication of wedged multilayer Laue lenses

We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack. This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.

42 ENGINEERING↗
DOE OSTI2019

Advanced Multilayer Coatings for National Security

This project advanced the state-of-the-art in multilayer interference coatings with customtailored properties for national security applications, by understanding and overcoming limitations in the physical properties of these coatings. We focused on improving the properties of two major types of multilayers: the reflectance of hard x-ray aperiodic multilayer coatings (MLs) and the laser damage resistance of dielectric multilayer coatings (MLDs). We developed a new class of hard x-ray MLs for imaging in the 17 – 59 keV photon energy range for applications including target diagnostics and astrophysics. We elucidated the physical and chemical properties of nanoscale layers of ML materials and their interfaces and developed generalized protocols for aperiodic ML design and deposition. We revealed the origin of important laser damage-prone precursors and the underlying mechanism upon exposure to high energy and intensity nanosecond (ns) lasers in the ultraviolet (UV) region. In both ML and MLD coatings, we investigated the relationships between deposition conditions and performance. We then applied deposition process modifications specific to each type of ML and MLD coatings to dramatically improve the ML reflective performance and the MLD laser-damage resistance.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Multilayer Architecture Barriers for High Temperature Nuclear Applications

Innovative thin film multilayer metal/ceramic barrier coatings have been developed by Argonne National Laboratory to protect fuel cladding against different phenomena that can be encountered under the harsh operating conditions of advanced nuclear reactors. One phenomenon is Fuel-Cladding Chemical Interaction (FCCI), which can represent a challenge to the performance of steel-clad metallic fuels in sodium-cooled fast reactors (SFRs), especially when operating to high burnups at elevated cladding temperatures, and long fuel residence time. Another phenomenon is the corrosion of zirconium-based cladding under prototypic boiling water reactor (BWR) conditions and associated cladding during off normal conditions, including loss of coolant accidents (LOCA). This work provides details of the development and testing of a thin film (few microns) multilayer metal/ceramic (CrY/Y 2 O 3 ) coatings on steel cladding and its performance against FCCI. The coating architecture evolved through systematic mechanical testing, radiation tolerance assessments, and high-temperature diffusion studies from a preliminary multilayer concept to an optimized high-performance design. The optimized structure leverages stoichiometric Y 2 O 3 for its exceptional radiation stability, chemical inertness, and ultra-low fission product diffusivity (e.g., Ce diffusivity ~10 -20 m 2 /s in irradiated Y 2 O 3 at 650 °C). This is paired with ductile chromium-rich interlayers (Cr 95 Y 5 ), which significantly enhance fracture toughness and mechanical resilience. Design refinements, including increased ceramic layer thickness and optimized Cr–Y interlayer composition, eliminated fracture propagation and preserved coating integrity under extreme mechanical stress (>10× typical reactor conditions) and prolonged radiation exposure (~300 dpa). Those conditions are well beyond expected conditions during normal operations in SFR, and cover some of the transient conditions as well. In addition, the coating deposition was demonstrated to be applied uniformly to the inner surface of steel tubes representing prototypic SFR cladding. Another phenomenon under consideration in this work is the corrosion of zirconium-based cladding under prototypic boiling water reactor (BWR) conditions and associated off normal conditions including loss of coolant accident (LOCA). Another multilayer thin film coating is considered for mitigation of this phenomenon, where a coating of yttrium aluminum and yttrium aluminum ceramic/metal thin film coating. Preliminary results on the coating performance during high temperature thermal cycling (up to 1000 C) have shown promising performance of the coating. On-going optimization of the coating will continue in FY26.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1974

Design guidelines for advanced LSI microcircuit packaging using thick film multilayer technology

Ceramic multilayer circuitry results from the sequential build-up of two or more layers of pre-determined conductive interconnections separated by dielectric layers and fired at an elevated temperature to form a solidly fused structure. The resultant ceramic interconnect matrix is used as a base to mount active and passive devices and provide the necessary electrical interconnection to accomplish the desired electrical circuit. Many methods are known for developing multilevel conductor mechanisms such as multilayer printed circuits, welded wire matrices, flexible copper tape conductors, and thin and thick-film ceramic multilayers. Each method can be considered as a specialized field with each possessing its own particular set of benefits and problems. This design guide restricts itself to the art of design, fabrication and assembly of ceramic multilayer circuitry and the reliability of the end product.

Peckinpaugh, C. J.↗
NASA NTRS1979

Release-rate calorimetry of multilayered materials for aircraft seats

Multilayered samples of contemporary and improved fire resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire blocking layer, and cushion reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass fiber block cushion were evaluated to determine which materials based on their minimum contributions to the total heat release of the multilayered assembly may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicone adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers.

Fewell, L. L.↗
NASA NTRS1980

Release-rate calorimetry of multilayered materials for aircraft seats

Multilayered samples of contemporary and improved fire-resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire-blocking layer, and cushion-reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat-release rate of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicon adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis.

Fewell, L. L.↗
NASA NTRS1986

Computer simulation of thin-film nucleation and growth - The multilayer mode

The computer simulation of thin-film nucleation and growth, which was previously performed for the case of single monolayer, has been extended to the case of multilayer growth. The simulation results show that the kinetics of multilayer growth is nearly identical to that of monolayer growth. The cluster density resulting from the multilayer mode is similar to that resulting from the monolayer mode at low coverage. At high coverage, multilayer growth results in substantially higher cluster density than that resulting from monolayer growth.

Salik, J.↗