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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Advanced Aerogel Technology

The JPL Aerogel Laboratory has made aerogels for NASA flight missions, e.g., Stardust, 2003 Mars Exploration Rovers and the 2011 Mars Science Laboratory, as well as NASA research projects for the past 14 years. During that time it has produced aerogels of a range of shapes, sizes, densities and compositions. Research is ongoing in the development of aerogels for future sample capture and return missions and for thermal insulation for both spacecraft and scientific instruments. For the past several years, the JPL Aerogel Laboratory has been developing, producing and testing a new composite material for use as the high temperature thermal insulation in the Advanced Sterling Radioisotope Generator (ASRG) being developed by Lockheed Martin and NASA. The composite is made up of a glass fiber felt, silica aerogel, Titania powder, and silica powder. The oxide powders are included to reduce irradiative heat transport at elevated temperatures. These materials have thermal conductivity values that are the same as the best commercially produced high temperature insulation materials, and yet are 40% lighter. By greatly reducing the amount of oxide powder in the composite, the density, and therefore for the value of the thermal conductivity, would be reduced. The JPL Aerogel Laboratory has experimented with using glass fiber felt, expanded glass fiber felt and loose fibers to add structural integrity to silica aerogels. However, this work has been directed toward high temperature applications. By conducting a brief investigation of the optimal combination of fiber reinforcement and aerogel density, a durable, extremely efficient thermal insulation material for ambient temperature applications would be produced. If a transparent thermal insulation is desired, then aerogel is an excellent candidate material. At typical ambient temperatures, silica aerogel prevents the transport of heat via convection and conduction due to its highly porous nature. To prevent irradiative thermal transport, silica aerogel can be used in conjunction with a transparent polymeric material that blocks infrared radiation. The transparency of silica aerogel is typically greater than 90% for visible wavelengths from 500 nm to 900 nm for a 5 mm long path length.

reduce irradiative heat transport↗
NASA NTRS2003

Robust Extraction and Multi-Technique Analysis of Micrometeoroids Captured in Low Earth Orbit

The use of low-density silica aerogel as the primary capture cell technology for the NASA Discovery mission Stardust to Comet Wild-2 [1] is a strong motivation for researchers within the Meteoritics community to develop techniques to handle this material. The unique properties of silica aerogel allow dust particles to be captured at hypervelocity speeds and to remain partially intact. The same unique properties present difficulties in the preparation of particles for analysis. Using tools borrowed from microbiologists, we have developed techniques for robustly extracting captured hypervelocity dust particles and their residues from aerogel collectors[2-3]. It is important not only to refine these extraction techniques but also to develop protocols for analyzing the captured particles. Since Stardust does not return material to Earth until 2006, researchers must either analyze particles that are impacted in the laboratory using light-gasgun facilities [e.g. 41 or examine aerogel collectors that have been exposed in low-Earth orbit (LEO) [5]. While there are certainly benefits in laboratory shots, i.e. accelerating known compositions of projectiles into aerogel, the LEO capture particles offer the opportunity to investigate real particles captured under real conditions. The aerogel collectors used in this research are part of the NASA Orbital Debris Collection Experiment that was exposed on the MIR Space Station for 18 months [5]. We have developed the capability at the UCB Space Sciences Laboratory to extract tiny volumes of aerogel that completely contain each impact event, and to mount them on micromachined fixtures so that they can be analyzed with no interfering support (Fig.1). These aerogel keystones simultaneously bring the terminal particle and the particle track to within 10 m (15 g cm- ) of the nearest aerogel surface. The extracted aerogel wedges containing both the impact tracks and the captured particles have been characterized using the synchrotron total external reflection X-ray fluorescence (TXRF) microprobe at SSRL, the Nuclear Microprobe at LLNL, synchrotron infrared microscopy at the ALS facility at LBL and the NSLS at BNL, and the Total Reflection X-ray Fluorescence (TXRF) facility at SLAC.

Westphal, A. J.↗
NASA NTRS2010

Polyolefin-based aerogels

The present invention relates to cross-linked polyolefin aerogels in simple and fiber-reinforced composite form. Of particular interest are polybutadiene aerogels. Especially aerogels derived from polybutadienes functionalized with anhydrides, amines, hydroxyls, thiols, epoxies, isocyanates or combinations thereof.

Lee, Je Kyun↗
NASA NTRS2003

Simplified Waterproofing of Aerogels

A relatively simple silanization process has been developed for waterproofing or rewaterproofing aerogels, xerogels, and aerogel/tile composites, and other, similar low-density, highly microporous materials. Such materials are potentially attractive for a variety of applications especially for thermal-insulation panels that are required to be thin and lightweight. Unfortunately, such materials are also hydrophilic and tend to collapse after adsorbing water from the air. Hence, an effective means of waterproofing is necessary to enable practical exploitation of aerogels and the like. Older processes for waterproofing aerogels are time-consuming, labor-intensive, and expensive, relative to the present process. Each of the older processes includes a number of different chemical treatment steps, and some include the use of toxic halogenated surface-modifying compounds, pressures as high as hundreds of atmospheres, and/or temperatures as high as 1,000 C.

Hsu, Ming-Ta S.↗
DOE OSTI2021

Iodine capture with mechanically robust heat-treated Ag-Al-Si-O xerogel sorbents

Silver-loaded heat-treated aluminosilicate xerogels (Ag-HTX) were evaluated as sorbents for iodine [I2(g)] capture. The heat treatment step was performed to help increase the mechanical integrity of the gels. The synthesized xerogels were characterized using powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, gravimetric iodine loading, nanoindentation, and dynamic mechanical analysis. The structural and chemical analyses of Ag-HTX showed uniform distribution of Ag throughout the gel network after Ag-exchange. After I2(g) capture, the AgI crystallites were observed in the sorbent verifying chemisorption as the iodine capture mechanism. Iodine loading of this xerogel was 0.43 g g-1 at 150°C over 1 d and 0.52 g g-1 at 22°C over 33 d. The specific surface area of Ag-HTX was 202 m2 g-1 and decreased to 87 m2 g-1 after iodine loading. The hardness of the heat-treated xerogel was 160 times higher than heat-treated aerogel of the same composition. The heat-treatment process increased the modulus value to 40.77 MPa from 6.99 MPa of as-made xerogel, demonstrating the need for this added step in the synthesis process. These results show that Ag-HTX is a promising sorbent for I2(g) capture with good loading capacity and mechanical stability.

xerogels, aerogels, iodine capture, hardness testi↗
NASA NTRS2012

Coordinated Analyses of Diverse Components in Whole Stardust Cometary Tracks

Analyses of samples returned from Comet Wild-2 by the Stardust spacecraft have resulted in a number of surprising findings that show the origins of comets are more complex than previously suspected [1]. Stardust aerogel tracks show considerable compositional diversity and the degree of impact related thermal modification and destruction is also highly variable. We are performing systematic examinations of entire Stardust tracks to discern the representative mineralogy and origins of comet Wild 2 components and to search for well preserved fine grained materials. Previously, we used ultramicrotomy to prepare sequential thin sections of entire "carrot" and "bulbous" type tracks along their axis while preserving their original shapes [2]. This technique allows us to characterize the usually well-preserved terminal particle (TP), but also any associated, fine-grained fragments that were shed along the track pathway. This report focuses on coordinated analyses of surviving indigenous cometary materials (crystalline and amorphous) along the aerogel track walls, their interaction with aerogel during collection and comparisons with their TPs. We examined the distribution of fragments throughout the track from the entrance hole to the TP.

Nakamura-Messenger, K.↗
DOE OSTI2020

Gaseous Iodine Sorbents: A Comparison between Ag-Loaded Aerogel and Xerogel Scaffolds

The general properties of aluminosilicate aerogels and xerogels with silver nanoparticles as sorbents for capturing iodine gas [I2(g)] were investigated. The structures, morphologies, compositions, and pore structures of aerogel and xerogel were compared using powder X-ray diffraction (PXRD), scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, as well as specific surface area (SSA) and pore size analyses. The as-made aerogels, xerogels, and heat-treated aerogels were impregnated with Ag by aqueous ion exchange using AgNO3 solutions, and PXRD patterns showed the presence of nanocrystalline Ag0 after Ag-impregnation. Iodine loadings of aerogels and xerogels were 0.33–0.41 g g-1. The Ag-impregnated aerogels without heat-treatment showed an 8 mass% higher iodine loading than Ag-impregnated xerogels and 3 mass% higher than heat-treated Ag-impregnated aerogels. All gels after iodine uptake showed the presence of AgI, indicating chemisorption of iodine to silver. The SSA values of the as-made gels were 419–598 m2 g-1 but decreased significantly to 34–120 m2 g-1 after Ag-impregnation and iodine uptake processes. Overall, changes in physical and chemical properties of aerogels and xerogels after iodine uptake were similar, and the difference in iodine loading capacities of the aerogels and xerogels was not significant while the synthesis process of xerogel is more practical because it does not require supercritical drying.

aerogel, xerogel, iodine capture↗
NASA NTRS1998

High Performance Materials Applications to Moon/Mars Missions and Bases

Two classes of material processing scenarios will feature prominently in future interplanetary exploration- in situ production using locally available materials in lunar or planetary landings and high performance structural materials which carve out a set of properties for uniquely hostile space environments. To be competitive, high performance materials must typically offer orders of magnitude improvements in thermal conductivity or insulation, deliver high strength-to-weight ratios, or provide superior durability (low corrosion and/or ablative character, e.g. in heat shields). The space-related environmental parameters of high radiation flux, low weight and superior reliability limits many typical aerospace materials to a short list comprising high performance alloys, nanocomposites and thin-layer metal laminates (Al-Cu, Al-Ag) with typical dimensions less than the Frank-Reed-type dislocation source. Extremely light weight carbon-carbon composites and car on aerogels will be presented as novel examples which define broadened material parameters, particularly owing to their extreme thermal insulation (R-32-64) and low densities (less than 0.01 g/cc) approaching that of air itself. Even with these low weight payload additions, rocket thrust limits and transport costs will always place a premium on assembling as much structural and life support resources upon interplanetary, lunar or asteroid arrival. As an example for in situ lunar glass manufacture, solar furnaces reaching 1700 C for pure silica glass manufacture in situ are compared with sol-gel technology and acid-leached ultrapure (less than 0.1% FeO) silica aerogel precursors.

Noever, David A.↗
DOE OSTI2021

Bismuth-Functionalized Silica Aerogels for Iodine Capture

The U.S. Department of Energy is looking into alternative sorbents for the removal of radioiodine from off-gas streams in a used nuclear fuel reprocessing plant. One class of sorbents considered are bismuth-functionalized silica aerogels which offer an efficient capture of iodine from off-gas streams and are environmentally friendly and lower cost when compared to silver-functionalized sorbents. Two types of bismuth-functionalized silica aerogels were successfully manufactured using a hierarchical synthesis approach:1) The Bi 3+ -aerogel with bismuth oxide nitrate hydroxide hydrate particles and 2) Bi-aerogel with bismuth metal and bismuth sulfide nanoparticles. Both sorbents exhibited high sorption capacity for iodine. However, presence of particles of different composition, size, and distribution on aerogel support resulted in different iodine loadings. The Bi 3+ -aerogel exhibited sorption capacity of 289 mg/g. In contrast, Bi-aerogel exhibited more that 20% higher sorption capacity. The heat-treatment of Bi 3+ -aerogel at 225? under hydrogen atmosphere increased iodine loading capacity to 351 mg/g.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Extreme synthesis of crystalline aerogel materials from amorphous aerogel precursors

In one embodiment, a composition of matter includes a crystalline porous structure having a density in a range from about 30 to about 50 mg/cm 3 . In another embodiment, a kit includes an amorphous, porous material, an inert pressure medium, a heating source, and a sample chamber configured to withstand an applied pressure of at least about 20 GPa. Other aspects and embodiments of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention.

Pauzauskie, Peter J.↗
NASA NTRS2006

Chemical, Physical, and Mechanical Characterization of Isocyanate Cross-linked Amine-Modified Silica Aerogels

We describe a new mechanically strong lightweight porous composite material obtained by encapsulating the skeletal framework of amine-modified silica aerogels with polyurea. The conformal polymer coating preserves the mesoporous structure of the underlying silica framework and the thermal conductivity remains low at 0.041 plus or minus 0.001 W m(sup -1 K(sup -1). The potential of the new cross-linked silica aerogels for load-carrying applications was determined through characterization of their mechanical behavior under compression, three-point bending, and dynamic mechanical analysis (DMA). A primary glass transition temperature of 130 C was identified through DMA. At room temperature, results indicate a hyperfoam behavior where in compression cross-linked aerogels are linearly elastic under small strains (less than 4%) and then exhibit yield behavior (until 40% strain), followed by densification and inelastic hardening. At room temperature the compressive Young's modulus and the Poisson's ratio were determined to be 129 plus or minus 8 MPa and 0.18, respectively, while the strain at ultimate failure is 77% and the average specific compressive stress at ultimate failure is 3.89 x 10(exp 5) N m kg(sup -1). The specific flexural strength is 2.16 x 10(exp 4) N m kg(sup -1). Effects on the compressive behavior of strain rate and low temperature were also evaluated.

Katti, Atul↗
NASA NTRS2009

Polyimide-Foam/Aerogel Composites for Thermal Insulation

Composites of specific types of polymer foams and aerogel particles or blankets have been proposed to obtain thermal insulation performance superior to those of the neat polyimide foams. These composites have potential to also provide enhanced properties for vibration dampening or acoustic attenuation. The specific type of polymer foam is denoted "TEEK-H", signifying a series, denoted H, within a family of polyimide foams that were developed at NASA s Langley Research Center and are collectively denoted TEEK (an acronym of the inventors names). The specific types of aerogels include Nanogel aerogel particles from Cabot Corporation in Billerica, MA. and of Spaceloft aerogel blanket from Aspen Aerogels in Northborough, MA. The composites are inherently flame-retardant and exceptionally thermally stable. There are numerous potential uses for these composites, at temperatures from cryogenic to high temperatures, in diverse applications that include aerospace vehicles, aircraft, ocean vessels, buildings, and industrial process equipment. Some low-temperature applications, for example, include cryogenic storage and transfer or the transport of foods, medicines, and chemicals. Because of thermal cycling, aging, and weathering most polymer foams do not perform well at cryogenic temperatures and will undergo further cracking over time. The TEEK polyimides are among the few exceptions to this pattern, and the proposed composites are intended to have all the desirable properties of TEEK-H foams, plus improved thermal performance along with enhanced vibration or acoustic-attenuation performance. A composite panel as proposed would be fabricated by adding an appropriate amount of TEEK friable balloons into a mold to form a bottom layer. A piece of flexible aerogel blanket material, cut to the desired size and shape, would then be placed on the bottom TEEK layer and sandwiched between another top layer of polyimide friable balloons so that the aerogel blanket would become completely encased in an outer layer of TEEK friable balloons. Optionally, the process could be further repeated to produce multiple aerogel-blanket layers interspersed with and encased by TEEK friable balloons.

Williams, Martha↗
NASA NTRS2018

Aerogel-Based Insulation Materials for Cryogenic Applications

Many different aerogel-based materials are now being used in thermal insulation systems for cryogenic applications. These materials include flexible composite blankets, bulk-fill particles, and polymer composites in both evacuated and non-evacuated environments. In ambient environments, aerogels provide superior thermal performance compared to conventional polymeric foam and cellular glass insulations while offering unique advantages in solving problems with weathering, moisture, and mechanical damage. Aerogels are also used as spacer materials in multilayer insulation systems. These layered systems provide combined structural-thermal capability for cryogenic systems in either vacuum-jacketed or externally-applied insulation designs. Test data (effective thermal conductivity) include a wide range of both commercial and experimental aerogel materials. Testing was performed using laboratory cryostats and standard methods including full range vacuum (from ambient pressure to high vacuum) and boundary temperatures 293 K and 78 K. Examples of aerogel-based insulation systems are given for both evacuated and non-evacuated applications.

aerogel layered composites↗
NASA NTRS2000

Nanotechnology Concepts at MSFC: Engineering Directorate

Nanotechnology is the art and science of building materials and devices at the ultimate level of finesse: atom by atom. Our nation's space program has needs for miniaturization of components, minimization of weight and maximization of performance, and nanotechnology will help us get there. MSFC - Engineering Directorate (ED) is committed to developing nanotechnology that will enable MSFC missions in space transportation, space science and space optics manufacturing. MSFC-ED has a dedicated group of technologists who are currently developing high pay-off nanotechnology concepts. This poster presentation will outline some of the concepts being developed at this time including, nanophase structural materials, carbon nanotube reinforced metal and polymer matrix composites, nanotube temperature sensors and aerogels. The poster will outline these concepts and discuss associated technical challenges in turning these concepts into real components and systems.

Bhat, Biliyar↗
NASA NTRS2001

Nanotechnology Concepts at Marshall Space Flight Center: Engineering Directorate

Nanotechnology is the art and science of building materials and devices at the ultimate level of finesse: atom by atom. Our nation's space program has need for miniaturization of components, minimization of weight, and maximization of performance, and nanotechnology will help us get there. Marshall Space Flight Center's (MSFC's) Engineering Directorate is committed to developing nanotechnology that will enable MSFC missions in space transportation, space science, and space optics manufacturing. MSFC has a dedicated group of technologists who are currently developing high-payoff nanotechnology concepts. This poster presentation will outline some of the concepts being developed including, nanophase structural materials, carbon nanotube reinforced metal and polymer matrix composites, nanotube temperature sensors, and aerogels. The poster will outline these concepts and discuss associated technical challenges in turning these concepts into real components and systems.

Bhat, B.↗
NASA NTRS2012

Multi-Mission Radioisotope Thermoelectric Generator Heat Exchangers for the Mars Science Laboratory Rover

The addition of the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) to the Mars Science Laboratory (MSL) Rover requires an advanced thermal control system that is able to both recover and reject the waste heat from the MMRTG as needed in order to maintain the onboard electronics at benign temperatures despite the extreme and widely varying environmental conditions experienced both on the way to Mars and on the Martian surface. Based on the previously successful Mars landed mission thermal control schemes, a mechanically pumped fluid loop (MPFL) architecture was selected as the most robust and efficient means for meeting the MSL thermal requirements. The MSL heat recovery and rejection system (HRS) is comprised of two Freon (CFC-11) MPFLs that interact closely with one another to provide comprehensive thermal management throughout all mission phases. The first loop, called the Rover HRS (RHRS), consists of a set of pumps, thermal control valves, and heat exchangers (HXs) that enables the transport of heat from the MMRTG to the rover electronics during cold conditions or from the electronics straight to the environment for immediate heat rejection during warm conditions. The second loop, called the Cruise HRS (CHRS), is thermally coupled to the RHRS during the cruise to Mars, and provides a means for dissipating the waste heat more directly from the MMRTG as well as from both the cruise stage and rover avionics by promoting circulation to the cruise stage radiators. A multifunctional structure was developed that is capable of both collecting waste heat from the MMRTG and rejecting the waste heat to the surrounding environment. It consists of a pair of honeycomb core sandwich panels with HRS tubes bonded to both sides. Two similar HX assemblies were designed to surround the MMRTG on the aft end of the rover. Heat acquisition is accomplished on the interior (MMRTG facing) surface of each HX while heat rejection is accomplished on the exterior surface of each HX. Since these two surfaces need to be at very different temperatures in order for the fluid loops to perform efficiently, they need to be thermally isolated from one another. The HXs were therefore designed for high in-plane thermal conductivity and extremely low through-thickness thermal conductivity by using aluminum facesheets and aerogel as insulation inside a composite honeycomb core. Complex assemblies of hand-welded and uniquely bent aluminum tubes are bonded onto each side of the HX panels, and are specifically designed to be easily mated and demated to the rest of the RHRS in order to ease the integration effort.

Mastropietro, A. J.↗
NASA NTRS2010

Design and Preliminary Thermal Performance of the Mars Science Laboratory Rover Heat Exchangers

The challenging range of proposed landing sites for the Mars Science Laboratory Rover requires a rover thermal management system that is capable of keeping temperatures controlled across a wide variety of environmental conditions. On the Martian surface where temperatures can be as cold as -123 degrees Centigrade and as warm as 38 degrees Centigrade, the Rover relies upon a Mechanically Pumped Fluid Loop (MPFL) and external radiators to maintain the temperature of sensitive electronics and science instruments within a -40 degrees Centigrade to 50 degrees Centigrade range. The MPFL also manages significant waste heat generated from the Rover power source, known as the Multi Mission Radioisotope Thermoelectric Generator (MMRTG). The MMRTG produces 110 Watts of electrical power while generating waste heat equivalent to approximately 2000 Watts. Two similar Heat Exchanger (HX) assemblies were designed to both acquire the heat from the MMRTG and radiate waste heat from the onboard electronics to the surrounding Martian environment. Heat acquisition is accomplished on the interior surface of each HX while heat rejection is accomplished on the exterior surface of each HX. Since these two surfaces need to be at very different temperatures in order for the MPFL to perform efficiently, they need to be thermally isolated from one another. The HXs were therefore designed for high in-plane thermal conductivity and extremely low through-thickness thermal conductivity by using aerogel as an insulator inside composite honeycomb sandwich panels. A complex assembly of hand welded and uniquely bent aluminum tubes are bonded onto the HX panels and were specifically designed to be easily mated and demated to the rest of the Rover Heat Recovery and Rejection System (RHRS) in order to ease the integration effort. During the cruise phase to Mars, the HX assemblies serve the additional function of transferring heat from the Rover MPFL to the separate Cruise Stage MPFL so that heat generated deep inside the Rover can be dissipated via the Cruise Stage radiators. Significant fabrication challenges had to be overcome in order to make the HX design a reality. The cruise phase thermal performance of the Rover HXs was verified in the cruise phase system level thermal vacuum test that was performed at JPL in January of 2009. The Rover HXs were modeled in I-DEAS TMG and predictions are compared to actual data from the test.

Heat Rejection System↗