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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Effects of material mixing on planetary gamma ray spectroscopy

The effect of mixing of rocks and soil on the gamma-ray signal emitted by Martian surface was investigated with special consideration given to the effect of the geometry of mixing. It is shown that, under certain circumstances, this scale can have a significant effect on the gamma-ray spectrum observed. The techniques that can be used to address this problem are discussed, showing that, using these techniques, rock compositions can be inferred from the signal produced by a rock-soil mixtures of unknown rock concentration and mixing geometry.

Squyres, Steven W.↗
NASA NTRS2015

Particle Morphology and Elemental Composition of Smoke Generated by Overheating Common Spacecraft Materials

Fire safety in the indoor spacecraft environment is concerned with a unique set of fuels which are designed to not combust. Unlike terrestrial flaming fires, which often can consume an abundance of wood, paper and cloth, spacecraft fires are expected to be generated from overheating electronics consisting of flame resistant materials. Therefore, NASA prioritizes fire characterization research for these fuels undergoing oxidative pyrolysis in order to improve spacecraft fire detector design. A thermal precipitator designed and built for spacecraft fire safety test campaigns at the NASA White Sands Test Facility (WSTF) successfully collected an abundance of smoke particles from oxidative pyrolysis. A thorough microscopic characterization has been performed for ten types of smoke from common spacecraft materials or mixed materials heated at multiple temperatures using the following techniques: SEM, TEM, high resolution TEM, high resolution STEM and EDS. Resulting smoke particle morphologies and elemental compositions have been observed which are consistent with known thermal decomposition mechanisms in the literature and chemical make-up of the spacecraft fuels. Some conclusions about particle formation mechanisms are explored based on images of the microstructure of Teflon smoke particles and tar ball-like particles from Nomex fabric smoke.

Smoke↗
NASA NTRSDate not supplied

Development of Additive Manufacturing Technologies for 3D Printing of Spacecraft Heat Shields

Introduction: Ablative heat shields are an enabling technology for entry into planetary atmospheres. From the PICA heatshields used for several Mars rovers to the carbon phenolic material used for Galileo’s Jupiter entry probe, the heat shield manages the heat load transferred to the payload, protecting the sensitive scientific instruments carried on entry probes. The Additive Manufacturing of Thermal Protection Systems (AMTPS) project, an Early Career Initiative (ECI) funded by NASA’s Space Technology Mission Directorate and led by NASA Johnson Space Center, seeks to develop materials and processes for 3D printing ablative heat shields for spacecraft. Current methods for producing ablative heat shields are extremely labor intensive and re-quire extensive hands-on processes and quality control characterization. Additive manufacturing (AM) offers the possibility of reduced production times, improved reliability, and enhanced performance via graded compositions. Costs will also be reduced by reducing the time and labor required for heat shield production. Direct integration of the heat shield onto the structure during processing simplifies integration and reduces risk. Material Development: A critical challenge for the project is development of a material system that can (1) be printed in a near-net shape process and (2) perform well as an ablator. Achieving printability requires the material to flow under applied pressure, but maintain its shape once extruded from the printer nozzle. Ablative performance is measured by a multitude of markers, including char yield, char strength, thermal conductivity, and recession rate. Furthermore, there are several mechanical and thermal property considerations for vehicle integration including coefficient of thermal expansion (CTE) and residual stress. AM technology will be leveraged to grade the material formulation and properties through the thickness of the heat shield, an architecture not possible with current manufacturing processes. To this end, “robust” material formulations have been pre-pared with higher density for use on the surface where most ablation will occur. “Insulative” material formulations, with lower density and lower thermal conductivity, are prepared for use in the depth of the heat shield. This graded architecture will re-duce the overall mass of the heat shield and reduce costs and/or increase scientific payload capacities. To achieve a material system with the required properties, multiple resins have been investigated in collaboration with NASA Ames Research Center. To tune printability and performance, resin additives were studied to improve flexibility of the cured material while maintaining acceptable ablative performance. Material coupons were printed and studied via a suite of mechanical and thermal characterization methods. Arc jet testing was conducted at NASA Ames Research Center to evaluate ablative performance and thermal protection under conditions expected in atmospheric entry. Manufacturing Scale-Up: A partnership with Oak Ridge National Laboratory (ORNL) aims to enable full-scale fabrication of a 3D printed heat shield. Leveraging expertise in manufacturing and 3D printing at ORNL, a mid-scale manufacturing demonstration unit will be built and tested, using a dual-layer ablative system printed directly onto the titanium structure. Work on robotic system integration is ongoing and efforts to scale up material mixing with a material compound will ensure accurate and homogenous composition. Flight Test: A hypersonic sub-orbital flight test will provide a rigorous test of material performance ranging from ablation, thermal management, and mechanical integrity. Design of the capsule has taken place in collaboration with the University of Kentucky. Data collected from the flight will inform future design efforts in material formulation, printing methodology, and heat shield-capsule integration.

additive manufacturing↗
NASA NTRS1996

Mixed composition materials suitable for vacuum web sputter coating

Ion beam sputter deposition techniques were used to investigate simultaneous sputter etching of two component targets so as to produce mixed composition films. Although sputter deposition has been largely confined to metals and metal oxides, at least one polymeric material, poly-tetra-fluorethylene, has been demonstrated to produce sputtered fragments which repolymerize upon deposition to produce a highly cross-linked fluoropolymer resembling that of the parent target Fluoropolymer-filled silicon dioxide and fluoropolymer-filled aluminum oxide coatings have been deposited by means of ion beam sputter coat deposition resulting in films having material properties suitable for aerospace and commercial applications. The addition of fluoropolymer to silicon dioxide films was found to increase the hydrophobicity of the resulting mixed films; however, adding fluoropolymer to aluminum oxide films resulted in a reduction in hydrophobicity, thought to be caused by aluminum fluoride formation.

Banks, Bruce A.↗
NASA NTRS1974

Apparatus for remote handling of materials

Apparatus for remote handling of materials are described. A closed housing is provided with first and second containers and first and second reservoirs for holding materials to be mixed. The materials are transferable from the reservoirs to the first container where they are mixed. The mixed materials are then conveyed from the first container to the second container preferably by dumping the mixed materials into a funnel positioned over the second container. The second container is then moved to a second position for analysis of the mixed materials. For example, the materials may be ignited and the flame analyzed. Access, such as a sight port, is provided in the housing at the analysis position. The device provides a simple and inexpensive apparatus for safely mixing a pyrophoric material and an oxidizer which together form a thermite type mixture that burns to produce a large quantity of heat and light.

Kimball, R. B.↗
NASA NTRS1989

Radial mixing of material in the asteroidal zone

The asteroid belt shows radial zoning of compositional structure. The most abundant types are successively S, C, and P types from the inner to the outer parts of the main belt, and D type in the Trojan clouds. This paper examines processes for producing this structure before, during, and after the accretion of asteroids. The initial structure is established by temperature and composition gradients in the turbulent solar nebula during the collapse of the presolar cloud. The radial scale of the zoning, comparable to the disk thickness, favors disk models with relatively low turbulent viscosity. Radial decay of solid bodies due to gas drag during settling to the central plane and planetesimal formation probably causes only a small degree of mixing, due to the systematic nature of drag-induced motions. The formation of Jupiter causes scattering of massive planetesimals from that planet's zone through the asteroid zone. The present random velocities of asteroids resulting from that stirring process are consistent with the radial scale of transitions between compositional types.

Ruzmaikina, T. V.↗
NASA NTRS1998

Crystal Growth of Mixed Optical Materials With the Automatic Czochralski Puller

Most of optical and semiconductor single crystalline materials produced in the electronic industry is grown with the Czochralski technique. This is the only technique capable of producing large high quality single crystals in a reasonable amount of time. The technique originated, and took its name, from pioneering work by Polish engineer J. Czochralski in 1917, who pulled single crystal wires (fibers) of low melting point metals from the melt in order to determine the maximum speeds at which they could be crystallized. The technique has been modified and its application has been extended first to the growth of silicon and later to a very wide range of compound semiconductors, metals, oxides and halides. It is now the dominant technique for the wide range of materials in the electronic industries. Czochralski growth is initiated by dipping a seed crystal of a chosen crystallographic orientation onto the surface of a melt contained in the heated crucible. The seed is then slowly withdrawn, solidifying the adherent column of the melt in steady state at an average rate given by the sum of the pulling rate and the rate of lowering the solid-liquid interface due to the depletion of the melt in the crucible. The control of the desired crystal diameter is achieved by closely controlling the heat balance at the solid-liquid interface.

Loutts, George B.↗
NASA NTRS2018

Additive Construction with Mobile Emplacement (ACME) / Automated Construction of Expeditionary Structures (ACES) Materials Delivery System (MDS)

The purpose of the Automated Construction of Expeditionary Structures, Phase 3 (ACES 3) project is to incorporate the Liquid Goods Delivery System (LGDS) into the Dry Goods Delivery System (DGDS) structure to create an integrated and automated Materials Delivery System (MDS) for 3D printing structures with ordinary Portland cement (OPC) concrete. ACES 3 is a prototype for 3-D printing barracks for soldiers in forward bases, here on Earth. The LGDS supports ACES 3 by storing liquid materials, mixing recipe batches of liquid materials, and working with the Dry Goods Feed System (DGFS) previously developed for ACES 2, combining the materials that are eventually extruded out of the print nozzle. Automated Construction of Expeditionary Structures, Phase 3 (ACES 3) is a project led by the US Army Corps of Engineers (USACE) and supported by NASA. The equivalent 3D printing system for construction in space is designated Additive Construction with Mobile Emplacement (ACME) by NASA.

Mueller, R. P.↗
NASA NTRS2011

Laboratory Studies of Fischer-Tropsch-Type Reactions and Their Implications for Organics in Asteroids and Comets

We have been studying Fischer-Tropsch type (FTT) reactions as a source for organic materials both in the gas phase of the solar nebula and incorporated into primitive comets and asteroids for almost 10 years, and over this time our concept has evolved greatly from the standard "catalytic" model to a much more robust chemical scenario. Our simulations have been conducted at temperatures that are much higher than we like, primarily for practical reasons such as the timescale of individual reactions, and we are just starting a series of measurements to allow us to measure reaction rates at temperatures from 873K down to as low as 373K. We have preliminary data on the carbon (d13C = -50) & nitrogen (d15N = +9.5) isotopic fractionation at 873K, but not on materials produced at lower temperature. Isotope values are on the VPDB scale for carbon and vs. Air for nitrogen. We have also investigated the noble gas trapping efficiency of the FTT process by adding a small amount of a noble gas mix to our standard synthesis mix. The noble gas ratio is 49:49:1:1::Ne:Ar:Kr:Xe. Xe and Kr are trapped at 873K and are more efficiently trapped at 673K with no isotopic fractionation at either temperature. Ar trapping is detected at 673K, but not at 873K. Ne has not yet been observed in our samples. The solar nebula was an extremely complex system, mixing materials from the innermost regions out to well into the zones where comets formed and thus mixing highly processed nebular materials with grains and coatings formed before the nebula began to collapse. Laboratory studies may provide the means to separate such diverse components based on carbon or nitrogen isotopic fractionation or the quantities of noble gases trapped in grain coatings and their thermal release patterns, among other observables. The ultimate goal of laboratory synthesis of nebular analogs is to provide the means to identifY the conditions under which natural samples were formed and the signatures of subsequent metamorphic events.

Nuth, Joseph↗
NASA NTRS1978

Silicone azide fireproof material

Finely powdered titanium oxide was added to silicone azide as the sintering agent to produce a nonflammable material. Mixing proportions, physical properties, and chemical composition of the fireproofing material are included.

Source record↗
NASA NTRS1977

Chemical stratigraphy of the Apollo 17 deep drill cores 70009-70007

A description is presented of an analysis of a total of 26 samples from three core segments (70009, 70008, 70007) of the Apollo 17 deep drill string. The deep drill string was taken about 700 m east of the Camelot Crater in the Taurus-Littrow region of the moon. Three core segments have been chemically characterized from the mainly coarse-grained upper portion of the deep drill string. The chemical data suggest that the entire 70007-70009 portion of the deep drill string examined was not deposited as a single unit, but was formed by several events sampling slightly different source materials which may have occurred over a relatively short period of time. According to the data from drill stem 70007, there were at least two phases of deposition. Core segment 70009 is probably derived from somewhat different source material than 70008. It seems to be a very well mixed material.

Ehmann, W. D.↗
NASA NTRS1992

The Martian surface layer

The global characteristics of the Martian surface layer are discussed on the basis of thermal, albedo, color, and radar data for the region between approximately 60 deg S and 60 deg N. Thermal data reveal the presence of large low- and high-inertia regions of the northern hemisphere, with much of the south covered by material of moderate inertia. There is a strong anticorrelation between inertia and albedo, a correlation between inertia and rock abundance, and, over much of the planet, a correlation of radar-derived density with inertia. Viking Orbiter color data indicate the presence of three major surface materials: low-inertia, bright-red material that is presumably dust; high-inertia, dark-grey material interpreted to be lithic material mixed with palagonitelike dust; and moderate-inertia, dark-red material that is rough at subpixel scales and interpreted to be indurated. Observations from the Viking landing sites show rocks, fines of varying cohesion and crusts. These sites have indications of aeolian erosion and deposition in the recent past.

Christensen, Philip R.↗
NASA NTRS2017

Chemical, Mineralogical, and Physical Properties of Martian Dust and Soil

Global and regional dust storms on Mars have been observed from Earth-based telescopes, Mars orbiters, and surface rovers and landers. Dust storms can be global and regional. Dust is material that is suspended into the atmosphere by winds and has a particle size of 1-3 micrometer. Planetary scientist refer to loose unconsolidated materials at the surface as "soil." The term ''soil'' is used here to denote any loose, unconsolidated material that can be distinguished from rocks, bedrock, or strongly cohesive sediments. No implication for the presence or absence of organic materials or living matter is intended. Soil contains local and regional materials mixed with the globally distributed dust by aeolian processes. Loose, unconsolidated surface materials (dust and soil) may pose challenges for human exploration on Mars. Dust will no doubt adhere to spacesuits, vehicles, habitats, and other surface systems. What will be the impacts on human activity? The objective of this paper is to review the chemical, mineralogical, and physical properties of the martian dust and soil.

Ming, D. W.↗
NASA NTRS1989

Making Multicore, Multishell Microspheres

Multiple streams of fluids combined to produce various structures. Spherical or nearly spherical micro-shells containing two or more discrete inclusions produced by proposed technique. Pairs of coaxial nozzles combined in arrays of two or more. Each pair of nozzles generate inner jet surrounded by sheath of fluid. Multiple jets combined to form droplets composed of shells and cores. Spheres designed so cores combine to mix or react only after leaving shell generator. Similarly, two or more shell-wall materials mix or react after leaving generator.

Morrison, Andrew D.↗
NASA NTRS1980

"Foreign material" to verify root fusion in welded joints

Foil or thin wire at weld root is used to verify weld penetration. When weld is adequate, material mixes with weld and traces of it diffuse to weld crown. Spectroscopic analysis of samples identifies foreign material and verifies root has fused. Weld roots are usually inaccessible to visual inspection, and X-ray and ultrasonic inspection techniques are not always reliable. Good results are obtained with use of gold/nickel alloy.

Kleint, R. E.↗
NASA NTRS1974

Impact resistance of composite fan blades

Results are presented of a program to determine the impact resistance of composite fan blades subjected to foreign object damage (FOD) while operating under conditions simulating a short take-off and landing (STOL) engine at takeoff. The full-scale TF39 first-stage fan blade was chosen as the base design for the demonstration component since its configuration and operating tip speeds are similar to a typical STOL fan blade several composite configurations had already been designed and evaluated under previous programs. The first portion of the program was devoted toward fabricating and testing high impact resistant, aerodynamically acceptable composite blades which utilized only a single material system in any given blade. In order to increase the blade impact capability beyond this point, several mixed material (hybrid) designs were investigated using S-glass and Kevlar as well as boron and graphite fibers. These hybrid composite blades showed a marked improvement in resistance to bird impact over those blades made of a single composite material. The work conducted under this program has demonstrated substantial improvement in composite fan blades with respect to FOD resistance and has indicated that the hybrid design concept, which utilizes different types of fibers in various portions of a fan blade design depending on the particular requirements of the different areas and the characteristics of the different fibers involved, shows a significant improvement over those designs utilizing only one material system.

Source record↗
NASA NTRS1988

Crystallography, chemistry and structural disorder in the new high-Tc Bi-Ca-Sr-Cu-O superconductor

Diffraction experiments are reported which indicate that the new Bi-Ca-Sr-Cu-O layer-structure superconductor possesses a primitive orthorhombic unit cell with probable space group Pnnn. The material exhibits severe structural disorder which is primarily related to stacking within the layers. The apparent orthorhombic structure is an average resulting from orthorhombic material mixed with monoclinic domains in two twinned orientations. Two distinct types of structural disorder that are common in materials synthesized to date are also described. This disorder complicates the crystallographic analysis and suggests that X-ray and neutron diffraction methods may yield only an average structure.

Veblen, D. R.↗
NASA NTRS2011

Mount Protects Thin-Walled Glass or Ceramic Tubes from Large Thermal and Vibration Loads

The design allows for the low-stress mounting of fragile objects, like thin walled glass, by using particular ways of compensating, isolating, or releasing the coefficient of thermal expansion (CTE) differences between the mounted object and the mount itself. This mount profile is lower than true full kinematic mounting. Also, this approach enables accurate positioning of the component for electrical and optical interfaces. It avoids the higher and unpredictable stress issues that often result from potting the object. The mount has been built and tested to space-flight specifications, and has been used for fiber-optic, optical, and electrical interfaces for a spaceflight mission. This mount design is often metal and is slightly larger than the object to be mounted. The objects are optical or optical/electrical, and optical and/or electrical interfaces are required from the top and bottom. This requires the mount to be open at both ends, and for the object s position to be controlled. Thin inside inserts at the top and bottom contact the housing at defined lips, or edges, and hold the fragile object in the mount. The inserts can be customized to mimic the outer surface of the object, which further reduces stress. The inserts have the opposite CTE of the housing material, partially compensating for the CTE difference that causes thermal stress. A spring washer is inserted at one end to compensate for more CTE difference and to hold the object against the location edge of the mount for any optical position requirements. The spring also ensures that any fiber-optic or optic interface, which often requires some pressure to ensure a good interface, does not overstress the fragile object. The insert thickness, material, and spring washer size can be traded against each other to optimize the mount and stresses for various thermal and vibration load ranges and other mounting requirements. The alternate design uses two separate, unique features to reduce stress and hold the object. A release agent is applied to the inside surface of the mount just before the binding potting material is injected in the mount. This prevents the potting material from bonding to the mount, and thus prevents stress from being applied, at very low temperatures, to the fragile object being mounted. The potting material mixing and curing is temperature- and humidity-controlled. The mount has radial grooves cut in it that the potting material fills, thus controlling the vertical position of the mounted object. The design can easily be used for long and thin objects, short and wide objects, and any shape in between. The design s advantages are amplified for long and thin fragile objects. The general testing range was 45 to +45 C, but multiple mounts were successfully tested down to 60 and up to 50 C and the design can be adjusted for larger ranges.

Amato, Michael↗