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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Experimental investigation on the effects of fabric architectures on mechanical and damage behaviors of carbon/epoxy woven composites

The mechanical behaviors and damage evolutions of carbon/epoxy woven fabric composites with three different geometries, i.e., one plain weave and two twill weave patterns with different areal densities, are studied under tensile loading. The effects of weave patterns on mechanical properties are investigated by monotonic and cyclic tension tests. Remarkable variations in stress–strain curve, Poisson’s ratio, residual strain and strain map exist in the three composites. Crimp ratio is found to be a critical factor to govern the mechanical properties. With smaller crimp ratio, a quasi-linear stress–strain curve with higher elastic modulus and strength is observed. The stress–strain curves of composites with higher crimp ratio contain transition stages with significant tangent modulus degradation. Elastic modulus, strength and damage initiation are all correlated with the crimp ratio linearly regardless of the fabric pattern. Dramatic nonlinear evolution in Poisson’s ratio occurs in the composite with higher crimp ratio. Cyclic tension results indicate that the residual strain is a more appropriate damage indicator than the unloading elastic modulus. Microstructure examination shows that damage developments are essentially related to the fabric geometry, and result in various mechanical behaviors. This work provides important insights into the geometry-deformation mechanism-mechanical property relationship of the woven composites.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Bifunctional Asymmetric Fabric with Tailored Thermal Conduction and Radiation for Personal Cooling and Warming

Personal thermal management is emerging as a promising strategy to provide thermal comfort for the human body while conserving energy. By improving control over the heat dissipating from the human body, personal thermal management can provide effective personal cooling and warming. Here, we propose a facile surface modification approach to tailor the thermal conduction and radiation properties based on commercially available fabrics, to realize better management of the whole heat transport pathway from the human body to the ambient. Additionally, a bifunctional asymmetric fabric (BAF) offering both a cooling and a warming effect is demonstrated. Due to the advantages of roughness asymmetry and surface modification, the BAF demonstrates an effective cooling effect through enhanced heat conduction and radiation in the cooling mode; in the warming mode, heat dissipation along both routes is reduced for personal warming. As a result, a 4.6 °C skin temperature difference is measured between the cooling and warming BAF modes, indicating that the thermal comfort zone of the human body can be enlarged with one piece of BAF clothing. We expect this work to present new insights for the design of personal thermal management textiles as well as a novel solution for the facile modification of available fabrics for both personal cooling and warming.

42 ENGINEERING↗
DOE OSTI2016

Large-scale fabrication of linear low density polyethylene/layered double hydroxides composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties

Novel LDH intercalated with organic aliphatic long-chain anion was large-scale synthesized innovatively by high-energy ball milling in one pot. The linear low density polyethylene (LLDPE)/layered double hydroxides (LDH) composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties were fabricated by melt blending and blowing process. FT IR, XRD, SEM results show that LDH particles were dispersed uniformly in the LLDPE composite films. Particularly, LLDPE composite film with 1% LDH exhibited the optimal performance among all the composite films with a 60.36% enhancement in the water vapor barrier property and a 45.73 °C increase in the temperature of maximum mass loss rate compared with pure LLDPE film. Furthermore, the improved infrared absorbance (1180–914 cm{sup −1}) of LLDPE/LDH films revealed the significant enhancement of heat retention. Therefore, this study prompts the application of LLDPE/LDH films as agricultural films with superior heat retention. - Graphical abstract: The fabrication process of LLDPE/LDH composite films. - Highlights: • LDH with basal spacing of 4.07 nm was synthesized by high-energy ball milling. • LLDPE composite films with homogeneous LDH dispersion were fabricated. • The properties of LLDPE/LDH composite films were improved. • LLDPE/LDH composite films show superior heat retention property.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Fabrication of superhydrophobic Pt{sub 3}Fe/Fe surface for its application

Well-defined Pt{sub 3}Fe/Fe superhydrophobic materials on iron sheet with special properties, such as corrosion resistance, superhydrophobicity and superoleophilicity, was fabricated. The fabrication process involved etching in hydrochloric acid aqueous solution and simple replacement deposition process without using any seed and organic solvent, and then annealing. The electrochemical measurements show that the resultant surface in 3.5% sodium chloride solution displays good corrosion resistance. Also, it is proved that the obtained surface has better mechanical abrasion resistance via scratch test. The superoleophilicity and low water adhesion force of the obtained surface endow it high oil/water separation capacity. The as-prepared nanocomposites display enhanced catalytic activity and kinetics toward degradation of methyl orange. In particular, it possesses the most efficient degradation capacity (95%) towards methyl orange at a high concentration (17.5 mg/L) in 80 min. The improved stability and excellent catalytic activity of the Pt{sub 3}Fe/Fe nanocomposites promise new opportunities for the development of waste water treatment. - Graphical abstract: The illustration of application of superhydrophobic Pt{sub 3}Fe/Fe surface Display Omitted - Highlights: • Superhydrophobic Pt{sub 3}Fe/Fe composed was fabricated on iron sheet. • The growth process is without using any seed and organic solvent. • Superhydrophobic Pt{sub 3}Fe/Fe composed show superior oil/water separation capacity. • Superhydrophobic Pt{sub 3}Fe/Fe composed show high photocatalytic activity.

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

Organosilane-assisted selective etching strategy for fabrication of hollow/rattle-type mesoporous organosilica nanospheres

Highlights: • Effective fabrication of organic hollow/rattle-type mesoporous organosilica. • The addition of CTES could increase the porosity of the materials. • Pore-making agent (CTES) could be removed by alkali treatment without additional step. - Abstract: A facile strategy to fabricate hollow or rattle-type mesoporous silica nanospheres (HMSNs or RMSNs) with organic functional groups and porous shell was developed. Herein, thiol-HMSNs were obtained via treating vinyl-SiO{sub 1.5} @cyano&thiol-SiO{sub 1.5} prepared by using 3-mercaptopropyltrimethoxysilane (MPTMS) as organosilane precursor, vinyltriethoxysilane (VTES) as sacrificial template precursor and cyanoethyltriethoxysilane (CTES) as pore-making agent. In this method, CTES was co-condensed with MPTMS to form hybrid shell and played an important role in the formation of pore structures. When the volume ratio of MPTMS to CTES was 1:1, well-defined thiol-HMSNs with a specific surface area of 295.6 m{sup 2} g{sup −1} and pore volume of 0.51 cm{sup 3} g{sup −1} could be obtained. Moreover, [email protected] could also be synthesized through this method from three-layered structures (thiocyanato-SiO{sub 1.5} @vinyl-SiO{sub 1.5} @cyano&thiol-SiO{sub 1.5}). The as-prepared RMSNs presented good performance for the adsorption of 2, 4-dichloropheno in water. And this selective etching strategy was versatile and might be extended to fabricate more valuable organic hollow/rattle-type composites for different applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Fabrication of nanofibrous A- or B-sites substituted LaCoO{sub 3} perovskites with macroscopic structures and their catalytic applications

Graphical abstract: Fabrication of nanofibrous La{sub 1−x}Ce{sub x}CoO{sub 3} (x = 0.05, 0.1, 0.2) and LaMn{sub x}Co{sub 1−x}O{sub 3} (x = 0.2, 0.5, 0.8) perovskite-type oxides with macroscopic structures can be successfully achieved by using carbon nanofibers (CNFs) as templates. Furthermore, their application for the combustion of carbon black (CB), which is a model of particulate matter exhausted from diesel engines, was demonstrated. - Highlights: • Nanofibrous perovskites with macroscopic shapes were successfully obtained. • CNFs template method used here is facile, effective and reproducible. • This method might be applicable to other novel material fabrication. • The obtained materials show superior catalytic activity in soot combustion. - Abstract: Fabrication of nanofibrous La{sub 1−x}Ce{sub x}CoO{sub 3} (x = 0.05, 0.1, 0.2) and LaMn{sub x}Co{sub 1−x}O{sub 3} (x = 0.2, 0.5, 0.8) perovskite-type oxides with macroscopic structures can be successfully achieved by using carbon nanofibers (CNFs) as templates. Field emission scanning electron microscopy (FE-SEM), coupled with X-ray diffraction (XRD) analysis confirmed the template effect and formation of the perovskite-type oxides on the macroscopic substrate. It turned out that this facile method can ensure the desired single-phase perovskite-type oxides formation by controlling the corresponding metal ratio during the preparation procedure. In addition, the immobilized nanofibrous La{sub 1−x}Ce{sub x}CoO{sub 3} (x = 0.05) and LaMn{sub x}Co{sub 1−x}O{sub 3} (x = 0.5) perovskite-type oxides can greatly decrease the combustion temperature of nanosized carbon black particles, which has the high potential application prospects in the treatment of diesel soot particles.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Fabrication of high quality copper indium disulphide absorbers by bell-like wave modulated electrodeposition

Highlights: • Cu/In bilayer was fabricated by BMSMW deposition technique. • High quality CIS film was successfully fabricated. • A preferable ratio of Cu:In:S close to 1:1:2 was approached. • The SPV response as high as 6 mV was achieved. - Abstract: High-quality CuInS{sub 2} (CIS) thin films have been fabricated by sulfurization of electrodeposited copper–indium bilayer. A novel bell-like wave modulated square wave (BWMSW) electrodeposition technique is employed for the deposition of copper thin film. Three independent parameters (current or potential, frequency, duty cycle) are available for the BWMSW electrodeposition, which is different from the traditional electrodeposition technique with only one adjustable parameter (current or potential). The influences of deposition parameters such as frequency, duty cycle and the concentration of complexing agent are investigated. Benefited from the high quality copper film obtained by the BWMSW technique, the indium film is electrodeposited successfully on the copper layer to form a compact copper–indium alloy bilayer. After sulfurized at 600 °C for 60 min, the phase pure CIS film is obtained with better crystallinity. The structures, morphologies and optoelectronic properties of the CIS film are also characterized.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Direct ink write fabrication of transparent ceramic gain media

Solid-state laser gain media based on the garnet structure with two spatially distinct but optically contiguous regions have been fabricated. Transparent gain media comprised of a central core of Y 2.97 Nd 0.03 Al 5.00 O 12.00 (Nd:YAG) and an undoped cladding region of Y 3 Al 5 O 12 (YAG) were fabricated by direct ink write and transparent ceramic processing. Direct ink write (DIW) was employed to form the green body, offering a general route to preparing functionally structured solid-state laser gain media. Lastly, fully-dense transparent optical ceramics in a “top hat” geometry with YAG/Nd:YAG have been fabricated by DIW methods with optical scatter at 1064 nm of <3%/cm.

(140.3580) Lasers↗
DOE OSTI2026

Advancing the Performance of Anion Exchange Membrane Electrolysis by Employing a Powder-Based Ionomer during Anode Catalyst Layer Fabrication

The performance of anion exchange membrane water electrolysis (AEMWE) can be significantly improved by utilizing powdered ionomers during the fabrication of the anode catalyst layer (CL) to modify the CL properties. When comparing powdered ionomers to dispersed ionomers across various catalysts including cobalt oxide (Co 3 O 4 ), nickel−iron oxide (NiFe 2 O 4 ), and iridium oxide (IrO 2 ) the anode fabricated with powdered ionomers demonstrates improved performance in polarization curves, enhanced charge transfer kinetics, and reduced ohmic and transport losses, as evidenced by voltage breakdown and electrochemical impedance spectroscopy analyses. Optimal performance is achieved using a Co 3 O 4 catalyst with a 10 wt % powdered ionomer via the catalystcoated substrate method. Microscopy analyses reveal that electrodes formed with powdered ionomers during fabrication exhibit a more uniform catalyst and ionomer distribution, increased porosity with smaller pore areas, improved electronic conduction with less catalyst agglomeration isolated by a nonconductive ionomer, and enhanced interfacial contact with the membrane and transport layer. These findings highlight that ionomers in a powdered form can promote beneficial properties and are a promising approach to improving AEMWE efficiency.

08 HYDROGEN↗
DOE OSTI2013

λ/26 silver nanodots fabricated by direct laser writing through highly sensitive two-photon photoreduction

We demonstrated an approach to break the diffraction limit and realise deep-subwavelength two-photon direct laser writing by employing a highly sensitive photoreduction process. The photoreduction photosensitivity increased by at least 4 times while the wavelength of the fabrication laser beam was tuned from 800 nm to 580 nm. The increase of the photosensitivity resulted in improved resolution for the silver dot fabrication. By developing the photoreduction material with adding electron donors, the photosensitivity further increased and enabled the realisation of a single silver dot at 22 nm which is λ/26 for the wavelength of the fabrication laser beam.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2013

Femtosecond laser fabrication of micro and nano-disks in single layer graphene using vortex Bessel beams

We report the fabrication of micro and nano-disks in single layer chemical vapor deposition graphene on glass substrate using femtosecond laser ablation with vortex Bessel beams. The fabricated graphene disks with diameters ranging from 650 nm to 4 μm were characterized by spatially resolved micro-Raman spectroscopy. The variation of ablation threshold was investigated as a function of the number of pulses showing an incubation effect. A very high degree of size control of the fabricated graphene disks is enabled using a sequence of femtosecond pulses with different vortex orders.

36 MATERIALS SCIENCE↗
DOE OSTI2014

New route to the fabrication of nanocrystalline diamond films

Nanocrystalline diamond (NCD) thin films offer applications in various fields, but the existing synthetic approaches are cumbersome and destructive. A major breakthrough has been achieved by our group in the direction of a non-destructive, scalable, and economic process of NCD thin-film fabrication. Here, we report a cheap precursor for the growth of nanocrystalline diamond in the form of paraffin wax. We show that NCD thin films can be fabricated on a copper support by using simple, commonplace paraffin wax under reaction conditions of Hot Filament Chemical Vapor Deposition (HFCVD). Surprisingly, even the presence of any catalyst or seeding that has been conventionally used in the state-of-the-art is not required. The structure of the obtained films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectroscopy and electron energy-loss spectroscopy recorded at the carbon K-edge region confirm the presence of nanocrystalline diamond. The process is a significant step towards cost-effective and non-cumbersome fabrication of nanocrystalline diamond thin films for commercial production.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

High quality SiC microdisk resonators fabricated from monolithic epilayer wafers

The exquisite mechanical properties of SiC have made it an important industrial material with applications in microelectromechanical devices and high power electronics. Recently, the optical properties of SiC have garnered attention for applications in photonics, quantum information, and spintronics. This work demonstrates the fabrication of microdisks formed from a p-N SiC epilayer material. The microdisk cavities fabricated from the SiC epilayer material exhibit quality factors of as high as 9200 and the approach is easily adaptable to the fabrication of SiC-based photonic crystals and other photonic and optomechanical devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Fabrication of sub-12 nm thick silicon nanowires by processing scanning probe lithography masks

Silicon nanowires are key elements to fabricate very sensitive mechanical and electronic devices. We provide a method to fabricate sub-12 nm silicon nanowires in thickness by combining oxidation scanning probe lithography and anisotropic dry etching. Extremely thin oxide masks (0.3–1.1 nm) are transferred into nanowires of 2–12 nm in thickness. The width ratio between the mask and the silicon nanowire is close to one which implies that the nanowire width is controlled by the feature size of the nanolithography. This method enables the fabrication of very small single silicon nanowires with cross-sections below 100 nm{sup 2}. Those values are the smallest obtained with a top-down lithography method.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2014

Ion traps fabricated in a CMOS foundry

We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size. This demonstration of scalable quantum computing hardware utilizing a commercial CMOS process opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Design and fabrication of a MEMS chevron-type thermal actuator

This paper presents the design and fabrication of a MEMS chevron-type thermal actuator. The device was designed for fabrication in the standard MEMS technology, where the topography of the upper layers depends on the patterns of structural and sacrificial layers underneath. The proposed actuator presents some advantages over usual thermal vertical chevron actuators by means of low operating voltages, high output force and linear movement without deformation of the shaft. The device simulations were done using COVENTOR software. The movement obtained by simulation was 12 μm, for a voltage of 0.2 V and the current intensity of 257 mA. The design optimizes the in-plane displacement by fixed anchors and beam inclination angle. Heating is provided by Joule dissipation. The material used for manufacture of chevron-based actuator was aluminum due to its thermal and mechanical properties. The release of the movable part was performed using isotropic dry etching by Reactive Ion Etching (RIE). A first inspection was achieved using Scanning Electron Microscope (SEM). In order to obtain the in-plane displacement we carried out electrical measurements. The thermal actuator can be used for a variety of optical and microassembling applications. This kind of thermal actuator could be integrated easily with other micro devices since its fabrication is compatible with the general semiconductor processes.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Direct fabrication of thin layer MoS{sub 2} field-effect nanoscale transistors by oxidation scanning probe lithography

Thin layer MoS{sub 2}-based field effect transistors (FET) are emerging candidates to fabricate very fast and sensitive devices. Here, we demonstrate a method to fabricate very narrow transistor channel widths on a single layer MoS{sub 2} flake connected to gold electrodes. Oxidation scanning probe lithography is applied to pattern insulating barriers on the flake. The process narrows the electron path to about 200 nm. The output and transfer characteristics of the fabricated FET show a behavior that is consistent with the minimum channel width of the device. The method relies on the direct and local chemical modification of MoS{sub 2}. The straightforward character and the lack of specific requirements envisage the controlled patterning of sub-100 nm electron channels in MoS{sub 2} FETs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Highly efficient and controllable method to fabricate ultrafine metallic nanostructures

We report a highly efficient, controllable and scalable method to fabricate various ultrafine metallic nanostructures in this paper. The method starts with the negative poly-methyl-methacrylate (PMMA) resist pattern with line-width superior to 20 nm, which is obtained from overexposing of the conventionally positive PMMA under a low energy electron beam. The pattern is further shrunk to sub-10 nm line-width through reactive ion etching. Using the patter as a mask, we can fabricate various ultrafine metallic nanostructures with the line-width even less than 10 nm. This ion tailored mask lithography (ITML) method enriches the top-down fabrication strategy and provides potential opportunity for studying quantum effects in a variety of materials.

36 MATERIALS SCIENCE↗