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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

High performance aluminum-air flow batteries through double-face architecture and laser-modified and friction-stir processed 3D anode

Aluminum-air batteries (AAB) are regarded as one of the most promising beyond-lithium high-energy-density storage candidates. Here, this paper introduces a three-dimensional (3D) Al 7075 anode enabled by femtosecond laser and friction-stir process which, along with a special double-face anode architecture provides world-class performance. Electrochemical characterizations prove that the corrosion resistance of the modified 3D Al 7075 FSP anode was enhanced, and electrochemically active surface area (ECSA) was increased compared with that of normal Al 7075 anode. Friction-stir processing reduced the mean grain size from 30 μm to 3 μm. The discharge performance of 3D Al 7075 FSP anode is shown to be quite stable, and the average values of energy density are significantly increased from 2256 mWh g –1 to 2941 mWh g –1 at 100 mA cm –2 . In a double-face flowing Al-air battery system, the 3D Al 7075 FSP anode exhibited significantly better electrocatalytic performance (discharge voltage of 0.76 V at 400 mA cm –2 , and power density of 337.8 mW cm –2 ) than that of a commercial Al 7075 anode.

25 ENERGY STORAGE↗
DOE OSTI2015

Friction stir processing of an aluminum-magnesium alloy with pre-placing elemental titanium powder: In-situ formation of an Al{sub 3}Ti-reinforced nanocomposite and materials characterization

A fine-grained Al–Mg/Al{sub 3}Ti nanocomposite was fabricated by friction stir processing (FSP) of an aluminum-magnesium (AA5052) alloy with pre-placed titanium powder in the stirred zone. Microstructural evolutions and formation of intermetallic phases were analyzed by optical and electron microscopic techniques across the thickness section of the processed sheets. The microstructure of the nanocomposite consisted of a fine-grained aluminum matrix (1.5 µm), un-reacted titanium particles (<40 µm) and reinforcement particles of Al{sub 3}Ti (<100 nm) and Mg{sub 2}Si (<100 nm). Detailed microstructural analysis indicated solid-state interfacial reactions between the aluminum matrix and micro-sized titanium particles to form Al{sub 3}Ti intermetallic phase. The hard inclusions were then fractured and re-distributed in the metal matrix by the severe thermo-mechanical conditions imposed by FSP. Evaluation of mechanical properties by hardness measurement and uniaxial tensile test determined significant enhancement in the mechanical strength (by 2.5 order of magnetite) with a high ductility (~22%). Based on a dislocation-based model analysis, it was suggested that the strength enhancement was governed by grain refinement and the presence of hard inclusions (4 vol%) in the metal matrix. Fractographic studies also showed a ductile-brittle fracture mode for the nanocomposite compared with fully ductile rupture of the annealed alloy as well as the FSPed specimen without pre-placing titanium particles. - Highlights: • FSP was employed to fabricate in situ nanocomposite. • The AA5052 Al alloy with pre-placed micro-sized Ti particles were utilized. • The structural analysis was revealed that the in situ formation of Al{sub 3}Ti nanophase. • The SZ grain structure was refined by PSN and ZHP mechanisms during DRX. • Hardness and tensile strength were improved up to ~2.5 times with a good ductility.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Influence of surface morphology and UFG on damping and mechanical properties of composite reinforced with spinel MgAl{sub 2}O{sub 4}-SiC core-shell microcomposites

Interface between ceramic particulate and matrix is known to control the response of the materials and functionality of the composite. Among numerous physical properties, grain structure of the materials has also played a significant role in defining the behaviour of metal matrix composites. Usually, silicon carbide (SiC) particles show poor interfacial wettability in aluminium melt. Herein, we were successfully synthesized magnesium oxide (MgO) and nanocrystalline magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel coated silicon carbide (SiC) core-shell micro-composites through sol-gel technique to improve the wettability of dispersoids. Core-shell structures of submicron size were thoroughly investigated by various characterization techniques. Further, aluminium matrix composites incorporated with pristine SiC, MgO grafted SiC and MgAl{sub 2}O{sub 4} grafted SiC particles were fabricated by stir casting technique, respectively. Additionally, as-cast composites were processed via friction stir processing (FSP) technique to observe the influence of grain refinement on mechanical and damping properties. Electron back scattered diffraction (EBSD), Field emission scanning electron microscopy (FE-SEM) and X-ray energy dispersion spectroscopy (EDX) analysis were conducted for investigating grain size refinement, adequate dispersion, stability and de-agglomeration of encapsulated SiC particles in aluminium matrix. The mechanical as well as thermal cyclic (from − 100 to 400 °C) damping performance of the as-cast and friction stir processed composites were studied, respectively. Finally, the enhanced properties were attributable to reduced agglomeration, stabilization and proper dispersion of the tailored SiC particles Al matrix. - Highlights: •Synthesizing a novel coating layer of MgO and MgAl{sub 2}O{sub 4} spinel onto SiC particles •Significant improvement in UTS and hardness by reinforcing tailored SiC in Al •Significant grain refinements were obtained through FSP •SiC/MgAl{sub 2}O{sub 4}/Al exhibits ~ 61% higher storage modulus as compare to pure Al after FSP.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Evaluation of the microstructure and mechanical properties of WC particle reinforced aluminum matrix composites fabricated by friction stir processing

Highlights: • FSP was used for the preparation of aluminum matrix composites reinforced with WC particle. • WC particles were uniformly distributed in the composite. • WC particles refined the grains of aluminum matrix. • WC particles enhanced the hardness and tensile strength, but decreased the ductility. - Abstract: Tungsten carbide (WC) is an attractive reinforcing material for aluminum and its alloys. However, it is technically challenging to fabricate WC particle reinforced aluminum matrix composites (AMCs) with homogeneous distribution of WC particles by liquid state processing techniques because of large density gradient. The present work aim to produce WC particle reinforced aluminum matrix composites (AMCs) through friction stir processing (FSP) and analyze the effect of its volume fraction on the microstructural features and the mechanical behavior of the developed AMCs. Microstructural evaluation was conducted on the cross-sections of the samples by optical microscopy (OM), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). Microhardness testing was conducted across the cross-sections of FSPed samples to obtain hardness profiles and tensile test was conducted on as-received Al and FSPed samples. The fabricated AMCs exhibited the homogeneous distribution of WC particle with no obvious particle clustering in the stir zone, irrespective of position and WC particle volume fraction. Excellent WC/Al interfacial bonding was obtained in all FSPed AMCs with obviously refined grains. The average size of WC particles after FSP was slightly reduced with the increased volume fraction. It was also found that increasing the volume fraction of WC particles favored the grain refinement, improved the hardness and strength, but decreased the ductility. This improvement in the hardness and strength was attributed to the grain refinement strengthening and homogeneous distribution of WC particles. The decreased ductility resulted from the introduction of more WC particles. Increasing the volume fraction of WC particles caused the nature of fracture to move towards brittle nature.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effect of temperature on the fatigue cracking mechanisms in A356 Al alloy

This work builds on our previous investigation of the room temperature fatigue cracking mechanisms of an A356 Al alloy. Here, we analyze the elevated temperature fatigue cracking mechanisms in cast and friction stir processed (FSP) A356, and contrast them with the room temperature behavior. Two sets of FSP parameters were used to modify the microstructure of the cast alloy. After heat treatment, both the FSPed microstructures exhibited severe abnormal grain growth (AGG) leading to a very wide grain size distribution (from a few microns to a few millimeters). During room temperature fatigue tests, the FSP conditions exhibited significant improvements in fatigue lives, even up to an order of magnitude. However, with increasing temperature, the difference in the performance of the FSPed and Cast microstructures decreased until, at 200 °C, all three microstructural conditions exhibited similar fatigue response. Detailed electron back scattered diffraction (EBSD) imaging of failed fatigue specimens was used to study crack behavior. At room temperature, cracks initiated at defect sites or along persistent slip bands (PSBs) and propagated transgranularly. The grain boundaries acted as barriers to crack growth. At elevated temperatures, there was a complete role reversal of the grain boundaries. Cracks initiated along grain boundaries and propagated intergranularly in all microstructures. Below, we explore this transition of the cracking mechanism in detail.

Nelaturu, Plalgun↗
DOE OSTI2026

Use of friction stir processing to synthesize nanocrystalline, grain boundary segregating Fe-Ti alloys

Grain boundary segregating alloys, a class of alloys designed such that nanocrystalline grain sizes are thermodynamically stabilized by the presence of high segregation energy solutes at the grain boundaries, are typically produced through geometrically limited processing techniques such as equal channel angular extrusion or thin film sputtering. Here, this study explores the use of friction stir processing (FSP) as a novel means of studying and producing these alloys using a test system of Fe-6at%Ti. Spot FSPs with a range of processing parameter sets were produced on bulk, coarse grained bars of material and optimal parameters were identified. Microscopy identified a range of processed materials which achieved nanocrystalline grains on the order of 100 nm, delineating a critical window of processing parameters which limit heat input while inducing sufficient plastic deformation for grain refinement. The finest grained nanocrystalline Fe-Ti achieved a hardness of 7.68 GPa, a significant increase in hardness over pure Fe with a similar microstructure due to increased dislocation density from FSP as well as several strengthening mechanisms produced through the presence and segregation of Ti. These results demonstrated the feasibility of using FSP to produce nanocrystalline grain boundary segregating alloys.

Fe alloys↗
NASA NTRS1982

Fire Resistant Materials

Fire hazard is greater in atmospheres containing a high percentage of oxygen under pressure. NASA intensified its fire safety research after a 1967 Apollo fire. A chemically treated fabric called Durette developed by Monsanto Company, which will not burn or produce noxious fumes, was selected as a material for Apollo astronaut garments. Monsanto sold production rights for this material to Fire Safe Products (FSP). Durette is now used for a wide range of applications such as: sheets, attendants' uniforms in hyperbaric chambers; crew's clothing, furniture and interior walls of diving chambers operated by the U.S. Navy and other oceanographic companies and research organizations. Pyrotect Safety Equipment, Minneapolis, MN produces Durette suits for auto racers, refuelers and crew chiefs from material supplied by FSP. FSP also manufactures Durette bags for filtering gases and dust from boilers, electric generators and similar systems. Durette bags are an alternative to other felted fiber capable of operating at high temperature that cost twice as much.

Source record↗
NASA NTRS2007

Testing in Support of Fission Surface Power System Qualification

The strategy for qualifying a FSP system could have a significant programmatic impact. The US has not qualified a space fission power system since launch of the SNAP-10A in 1965. This paper explores cost-effective options for obtaining data that would be needed for flight qualification of a fission system. Qualification data could be obtained from both nuclear and non-nuclear testing. The ability to perform highly realistic nonnuclear testing has advanced significantly throughout the past four decades. Instrumented thermal simulators were developed during the 1970s and 1980s to assist in the development, operation, and assessment of terrestrial fission systems. Instrumented thermal simulators optimized for assisting in the development, operation, and assessment of modern FSP systems have been under development (and utilized) since 1998. These thermal simulators enable heat from fission to be closely mimicked (axial power profile, radial power profile, temperature, heat flux, etc.) and extensive data to be taken from the core region. For transient testing, pin power during a transient is calculated based on the reactivity feedback that would occur given measured values of test article temperature and/or dimensional changes. The reactivity feedback coefficients needed for the test are either calculated or measured using cold/warm zero-power criticals. In this way non-nuclear testing can be used to provide very realistic information related to nuclear operation. Non-nuclear testing can be used at all levels, including component, subsystem, and integrated system testing. FSP fuels and materials are typically chosen to ensure very high confidence in operation at design burnups, fluences, and temperatures. However, facilities exist (e.g. ATR, HFIR) for affordably performing in-pile fuel and materials irradiations, if such testing is desired. Ex-core materials and components (such as alternator materials, control drum drives, etc.) could be irradiated in university or DOE reactors to ensure adequate radiation resistance. Facilities also exist for performing warm and cold zero-power criticals.

Houts, Mike↗
NASA NTRS2008

Space Nuclear Power and Propulsion: Materials Challenges for the 21st Century

The current focus of NASA s space fission effort is Fission Surface Power (FSP). FSP systems could be used to provide power anytime, anywhere on the surface of the Moon or Mars. FSP systems could be used at locations away from the lunar poles or in permanently shaded regions, with no performance penalty. A potential reference 40 kWe option has been devised that is cost-competitive with alternatives while providing more power for less mass. The potential reference system is readily extensible for use on Mars. At Mars the system could be capable of operating through global dust storms and providing year-round power at any Martian latitude. To ensure affordability, the potential near-term, 40 kWe reference concept is designed to use only well established materials and fuels. However, if various materials challenges could be overcome, extremely high performance fission systems could be devised. These include high power, low mass fission surface power systems; in-space systems with high specific power; and high performance nuclear thermal propulsion systems. This tutorial will provide a brief overview of space fission systems and will focus on materials challenges that, if overcome, could help enable advanced exploration and utilization of the solar system.

Houts, Mike↗
NASA NTRS2010

Recent Advances in Power Conversion and Heat Rejection Technology for Fission Surface Power

Under the Exploration Technology Development Program, the National Aeronautics and Space Administration (NASA) and the Department of Energy (DOE) are jointly developing Fission Surface Power (FSP) technology for possible use in human missions to the Moon and Mars. A preliminary reference concept was generated to guide FSP technology development. The concept consists of a liquid-metal-cooled reactor, Stirling power conversion, and water heat rejection, with Brayton power conversion as a backup option. The FSP project has begun risk reduction activities on some key components with the eventual goal of conducting an end-to-end, non-nuclear, integrated system test. Several power conversion and heat rejection hardware prototypes have been built and tested. These include multi-kilowatt Stirling and Brayton power conversion units, titanium-water heat pipes, and composite radiator panels.

Mason, Lee↗
DOE OSTI2016

Recent Upgrades at the Safety and Tritium Applied Research Facility

This paper gives a brief overview of the Safety and Tritium Applied Research (STAR) facility operated by the Fusion Safety Program (FSP) at the Idaho National Laboratory (INL). FSP researchers use the STAR facility to carry out experiments in tritium permeation and retention in various fusion materials, including wall armor tile materials. FSP researchers also perform other experimentation as well to support safety assessment in fusion development. This lab, in its present two-building configuration, has been in operation for over ten years. The main experiments at STAR are briefly described. This paper discusses recent work to enhance personnel safety at the facility. The STAR facility is a Department of Energy less than hazard category 3 facility; the personnel safety approach calls for ventilation and tritium monitoring for radiation protection. The tritium areas of STAR have about 4 to 12 air changes per hour, with air flow being once through and then routed to the facility vent stack. Additional radiation monitoring has been installed to read the laboratory room air where experiments with tritium are conducted. These ion chambers and bubblers are used to verify that no significant tritium concentrations are present in the experiment rooms. Standby electrical power has been added to the facility exhaust blower so that proper ventilation will now operate during commercial power outages as well as the real-time tritium air monitors.

tritium facility upgrades↗
DOE OSTI2019

Modulating Activity through Defect Engineering of Tin Oxides for Electrochemical CO 2 Reduction

Abstract The large‐scale application of electrochemical reduction of CO 2 , as a viable strategy to mitigate the effects of anthropogenic climate change, is hindered by the lack of active and cost‐effective electrocatalysts that can be generated in bulk. To this end, SnO 2 nanoparticles that are prepared using the industrially adopted flame spray pyrolysis (FSP) technique as active catalysts are reported for the conversion of CO 2 to formate (HCOO − ), exhibiting a FE HCOO − of 85% with a current density of −23.7 mA cm −2 at an applied potential of −1.1 V versus reversible hydrogen electrode. Through tuning of the flame synthesis conditions, the amount of oxygen hole center (OHC; SnO●) is synthetically manipulated, which plays a vital role in CO 2 activation and thereby governing the high activity displayed by the FSP‐SnO 2 catalysts for formate production. The controlled generation of defects through a simple, scalable fabrication technique presents an ideal approach for rationally designing active CO 2 reduction reactions catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Simultaneous Independent Control of Tool Axial Force and Temperature in Friction Stir Processing

Maintaining consistent tool depth relative to the part surface is a critical requirement for many Friction stir processing (FSP) applications. Force control is often used with the goal of obtaining a constant weld depth. When force control is used, if weld temperature decreases, flow stress increases and the tool is pushed up. If weld temperature increases, flow stress decreases and the tool dives. These variations in tool depth and weld temperature cause various types of weld defects. Robust temperature control for FSP maintains a commanded temperature through control of the spindle axis only. Robust temperature control and force control are completely decoupled in control logic and machine motion. This results in stable temperature, force and tool depth despite the presence of geometric and thermal disturbances. Performance of this control method is presented for various weld paths and alloy systems.

force control↗
DOE OSTI2019

In Situ Observation of Acicular Ferrite Nucleation and Growth at Different Cooling Rate in Ti-Zr Deoxidized Steel

The effects of cooling rate on acicular ferrite (AF) nucleation, growth, and inclusion characteristics in Ti-Zr deoxidation steel were studied by utilizing the high temperature confocal laser scanning microscope (HT-CLSM). The results indicated that with the increase of cooling rate, the ferrite start nucleation temperature decreased, and the difference of first nucleation temperature between AF and ferrite side plate (FSP) reduced. When the cooling rate increased to 10.0 °C/s, AF and FSP simultaneously nucleated at 564.5 °C. In addition, the AF actual growth rate rose with the increase of cooling rate and reached 30.13 µm/s at 10.0 °C/s cooling rate. The AF ratio in microstructure increased first and then decreased with the cooling rate increase and was up to the maximum 45.83 pct at 1.0 °C/s cooling rate. For inclusion characteristics, cooling rates had no obvious effect on inclusion types, but had a great influence on inclusions size distribution. With the cooling rate increase, the inclusion average diameter reduced, and diminished to 1.39 µm at 10.0 °C/s cooling rate. Finally, the AF nucleation on the Ti-Zr-Mn-O-S + TiN inclusion could be explained by the low lattice misfit between ferrite and TiN that precipitated on the Ti-Zr-Mn-O-S inclusion surface.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Surface Modification by Friction Stir Processing of Low-Carbon Steel: Microstructure Investigation and Wear Performance

A low-carbon steel sheet with a thickness of 5 mm was subjected to friction stir processing (FSP) by one to four different passes. The microstructures of different regions were characterized using the optical microscopy and electron backscatter diffraction. The Vickers micro-harness was measured at the distance of 200 μm below the processed surfaces. The influence of pass numbers (PNs) on wear resistance was studied in terms of coefficients of friction (CoFs), weight losses and wear rates. SEM topographies of the worn surfaces were also studied to evaluate the wear mechanisms. Microstructure observations showed that Widmänstatten ferrite plates were formed in stir zones (SZs) and heat affected zones. As PN increased, these grains were widened due to the increment of the carbon diffusivity and lengthened because of the high heat input and microstructure anisotropy. Besides, increasing the PN causes increasing of the hardness and wear resistance, simultaneously. Specifically, the wear rate in the SZ was reduced from 2.8 × 10{sup −2} mm{sup 3} m{sup −1} in base metal to 0.3 × 10{sup −2} mm{sup 3} m{sup −1} in sample which was subjected to 4 FSP passes. However, variation in PN had no considerable effect on CoFs. Oxidative wear mechanism was observed on the worn surface of the steel and the FSPed samples while more debris was formed by increasing the PNs.

36 MATERIALS SCIENCE↗
DOE OSTI2014

NO{sub 2} gas sensing of flame-made Pt-loaded WO{sub 3} thick films

Unloaded WO{sub 3} and 0.25–1.0 wt% Pt-loaded WO{sub 3} nanoparticles for NO{sub 2} gas detection were synthesized by flame spray pyrolysis (FSP) and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The BET surface area (SSA{sub BET}) of the nanoparticles was measured by nitrogen adsorption. The NO{sub 2} sensing properties of the sensors based on unloaded and Pt-loaded WO{sub 3} nanoparticles were investigated. The results showed that the gas sensing properties of the Pt-loaded WO{sub 3} sensors were excellent to those of the unloaded one. Especially, 0.25 wt% Pt-loaded WO{sub 3} sensor showed highest response to NO{sub 2} than the others at low operating temperature of 150 °C. - Graphical abstract: The response of 0.25 wt% Pt-loaded WO3 sensor was 637 towards NO{sub 2} concentration of 10 ppm at 150 °C. - Highlights: • Unloaded and Pt-loaded WO{sub 3} nanoparticles for NO{sub 2} gas detection were synthesized by flame spray pyrolysis (FSP). • Gas sensing properties of the Pt-loaded WO{sub 3} sensors were excellent to those of the unloaded one. • 0.25 wt% Pt-loaded WO{sub 3} sensor showed highest response to NO{sub 2} at low operating temperature of 150 °C.

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

Flame-made TiO2(B)

Highlights: • Flame-made titania can contain up to 27% TiO{sub 2}(B). • TiO{sub 2}(B) is present due to quenching. • The fraction of TiO{sub 2}(B) depends on residence time at high temperature. • Flame-made titania containing TiO{sub 2}(B) photocure epoxy more efficiently than P25. - Abstract: Titania nanoparticles containing both monoclinic (TiO{sub 2}(B) – a promising battery material and catalyst) and anatase crystal phases are synthesized with a low-cost, scalable flame spray pyrolysis (FSP) process, as confirmed by X-ray diffraction, transmission electron microscopy and Raman spectroscopy. The latter reveals TiO{sub 2}(B) contents of up to 27% in the crystalline phase fraction. The amount of TiO{sub 2}(B) increases as the time for nanoparticle growth in the flame decreases through quenching with ambient air. It can be controlled by varying the flow rates of precursor solution and dispersion oxygen into the flame. The FSP-made titania outperforms commercial titania P25 in the photocuring of epoxy, indicating its potential as a photocatalyst.

77 NANOSCIENCE AND NANOTECHNOLOGY↗