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  • 1
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    Microgravity Experiments Being Developed for Microscopic Study of Colloidal Spheres (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Microscopic spheres suspended in liquid become highly ordered under the proper conditions. Such collections of particles, called colloidal suspensions or colloids, are the subject of a series of ongoing microgravity experiments at the NASA Lewis Research Center. By studying the way these colloidal suspensions order themselves, scientists can better understand how atoms of a liquid become ordered to form a solid. In addition, highly ordered colloids have special properties that may make them useful in future hightech applications. Work is underway at Lewis to develop an optical microscope to view these colloidal suspensions sphere by sphere in microgravity.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
    Format: application/pdf
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  • 2
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    Laser Light Scattering, from an Advanced Technology Development Program to Experiments in a Reduced Gravity Environment (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Recent advancements in laser light scattering hardware are described. These include intelligent single card correlators; active quench/active reset avalanche photodiodes; laser diodes; and fiber optics which were used by or developed for a NASA advanced technology development program. A space shuttle experiment which will employ aspects of these hardware developments is previewed.
    Keywords: LASERS AND MASERS
    Type: NASA-TM-110496 , NAS 1.15:110496 , PAPER-2210-21 , E-9830 , International Symposium on Space Optics; Apr 18, 1994 - Apr 22, 1994; Garmisch-Partenkirchen; Germany
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  • 3
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    A preview of a modular surface light scattering instrument with autotracking optics (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA's Advanced Technology Development (ATD) program is sponsoring the development of a new generation of surface light scattering hardware. This instrument is designed to non-invasively measure the surface response function of liquids over a wide range of operating conditions while automatically compensating for a sloshing surface. The surface response function can be used to compute surface tension, properties of monolayers present, viscosity, surface tension gradient and surface temperature. The instrument uses optical and electronic building blocks developed for the laser light scattering program at NASA Lewis along with several unique surface light scattering components. The emphasis of this paper is the compensation for bulk surface motion (slosh). Some data processing background information is also included.
    Keywords: OPTICS
    Type: NASA-TM-110495 , NAS 1.15:110495 , PAPER-2210-29 , International Symposium on Space Optics; Apr 18, 1994 - Apr 22, 1994; Garmisch-Partenkirchen; Germany
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  • 4
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    The Effectiveness of a NiCrY-Coating on a Powder Metallurgy Disk Superalloy (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Protective ductile coatings could be necessary to mitigate oxidation and corrosion attack on superalloy disks in some turbine engine applications. However, the effects of coatings on fatigue life of the disk during service are an important concern. The objective of this study was to investigate how such a coating could perform after varied post-coating processing. Cylindrical gage fatigue specimens of powder metallurgy-processed disk superalloy LSHR were coated with a NiCrY coating, shot peened, preparation treated, exposed, and then subjected to fatigue at high temperature. The effects of varied shot peening, preparation treatment, and exposures on fatigue life with and without the coating were compared. Each of these variables and several of their interactions significantly influenced fatigue life.
    Keywords: Chemistry and Materials (General)
    Type: NASA/TM-2018- 219885 , E-19507 , GRC-E-DAA-TN54306
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  • 5
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    Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk Superalloy (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Protective ductile coatings will be necessary to mitigate oxidation and corrosion attack on superalloy disks exposed to increasing operating temperatures in some turbine engine environments. However, such coatings must be resistant to harmful surface cracking during service. The objective of this study was to investigate how residual stresses evolve in such coatings. Cylindrical gage fatigue specimens of powder metallurgy-processed disk superalloy LSHR were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of shot peening and fatigue cycling on average residual stresses and other aspects of the coating were assessed. Shot peening did induce beneficial compressive residual stresses in the coating and substrate. However, these stresses became more tensile in the coating with subsequent heating and contributed to cracking of the coating in long intervals of cycling at 760 C. Substantial compressive residual stresses remained in the substrate adjacent to the coating, sufficient to suppress fatigue cracking. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating.
    Keywords: Metals and Metallic Materials
    Type: NASA/TM-2017-219514 , E-19376 , GRC-E-DAA-TN42671
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  • 6
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    Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Sodium fluoride (NaF) was used as an activation agent to successfully intercalate ferric chloride (FeCl3) into hexagonal boron nitride (hBN). This reaction caused the hBN mass to increase by approx.100 percent, the lattice parameter c to decrease from 6.6585 to between 6.6565 and 6.6569 , the x-ray diffraction (XRD) (002) peak to widen from 0.01deg to 0.05deg of the full width half maximum value, the Fourier transform infrared (FTIR) spectrum's broad band (1277/cm peak) to change shape, and new FTIR bands to emerge at 3700 to 2700 and 1600/cm. This indicates hBN's structural and chemical properties are significantly changed. The intercalated product was hygroscopic and interacted with moisture in the air to cause further structural and chemical changes (from XRD and FTIR). During a 24-h hold at room temperature in air with 100 percent relative humidity, the mass increased another 141 percent. The intercalated product, hydrated or not, can be heated to 750 C in air to cause exfoliation. Exfoliation becomes significant after two intercalation-air heating cycles, when 20-nm nanosheets are commonly found. Structural and chemical changes indicated by XRD and FTIR data were nearly reversed after the product was placed in hydrochloric acid (HCl), resulting in purified, exfoliated, thin hBN products.
    Keywords: Inorganic, Organic and Physical Chemistry; Nonmetallic Materials; Chemistry and Materials (General)
    Type: NASA/TM-2014-218125 , E-18825-1
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  • 7
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    Motorized Beam Alignment of a Commercial X-ray Diffractometer (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: X-ray diffraction (XRD) is a powerful analysis method that allows researchers to noninvasively probe the crystalline structure of a material. This includes the ability to determine the crystalline phases present, quantify surface residual stresses, and measure the distribution of crystallographic orientations. The Structures and Materials Division at the NASA Glenn Research Center (GRC) heavily uses the on-site XRD lab to characterize advanced metal alloys, ceramics, and polymers. One of the x-ray diffractometers in the XRD lab (Bruker D8 Discover) uses three different x-ray tubes (Cu, Cr, and Mn) for optimal performance over numerous material types and various experimental techniques. This requires that the tubes be switched out and aligned between experiments. This alignment maximizes the x-ray tube s output through an iterative process involving four set screws. However, the output of the x-ray tube cannot be monitored during the adjustment process due to standard radiation safety engineering controls that prevent exposure to the x-ray beam when the diffractometer doors are open. Therefore, the adjustment process is a very tedious series of blind adjustments, each followed by measurement of the output beam using a PIN diode after the enclosure doors are shut. This process can take up to 4 hr to perform. This technical memorandum documents an in-house project to motorize this alignment process. Unlike a human, motors are not harmed by x-ray radiation of the energy range used in this instrument. Therefore, using motors to adjust the set screws will allow the researcher to monitor the x-ray tube s output while making interactive adjustments from outside the diffractometer. The motorized alignment system consists of four motors, a motor controller, and a hand-held user interface module. Our goal was to reduce the alignment time to less than 30 min. The time available was the 10-week span of the Lewis' Educational and Research Collaborative Internship Project (LERCIP) summer internship program and the budget goal was $1200. In this report, we will describe our motorization design and discuss the results of its implementation.
    Keywords: Electronics and Electrical Engineering
    Type: NASA/TM-2013-217853 , E-18641
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  • 8
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    Microstructural Characterization and Modeling of SLM Superalloy 718 (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Superalloy 718 is an excellent candidate for selective laser melting (SLM) fabrication due to a combination of excellent mechanical properties and workability. Predicting and validating the microstructure of SLM-fabricated Superalloy 718 after potential post heat-treatment paths is an important step towards producing components comparable to those made using conventional methods. At present, obtaining accurate volume fraction and size measurements of gamma-double-prime, gamma-prime and delta precipitates has been challenging due to their size, low volume fractions, and similar chemistries. A technique combining high resolution distortion corrected SEM imaging and with x-ray energy dispersive spectroscopy has been developed to accurately and independently measure the size and volume fractions of the three precipitates. These results were further validated using x-ray diffraction and phase extraction methods and compared to the precipitation kinetics predicted by PANDAT and JMatPro. Discrepancies are discussed in context of materials properties, model assumptions, sampling, and experimental errors.
    Keywords: Structural Mechanics; Metals and Metallic Materials
    Type: GRC-E-DAA-TN47440 , Materials Science and Technology 2017; Oct 08, 2017 - Oct 12, 2017; Pittsburgh, PA; United States
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  • 9
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    Investigation of Alpha Silicon Carbide / Carbon Fiber Proposed (2H & 6H-SiC) / C (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A commercially available alpha silicon carbide coated carbon 12k fiber tow was subjected to rigorous inspection and testing. The pyrolized polyacrylonitrile (PAN) fiber had gone through a conversion process that resulted in a thin layer of SiC forming on the exterior of the fiber. The fibers? surface was characterized by x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Powdered x-ray diffraction (XRD) examined the bulk material properties. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) examined the crystallinity of the SiC. A number of pristine samples were used to determine elongation rate and tensile strength.
    Keywords: Composite Materials
    Type: GRC-E-DAA-TN49977 , Annual Conference on Composites, Materials, and Structures; Jan 22, 2018 - Jan 25, 2018; Cocoa Beach, FL; United States
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  • 10
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    An Automatic Phase-Change Detection Technique for Colloidal Hard Sphere Suspensions (2005)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: Colloidal suspensions of monodisperse spheres are used as physical models of thermodynamic phase transitions and as precursors to photonic band gap materials. However, current image analysis techniques are not able to distinguish between densely packed phases within conventional microscope images, which are mainly characterized by degrees of randomness or order with similar grayscale value properties. Current techniques for identifying the phase boundaries involve manually identifying the phase transitions, which is very tedious and time consuming. We have developed an intelligent machine vision technique that automatically identifies colloidal phase boundaries. The algorithm utilizes intelligent image processing techniques that accurately identify and track phase changes vertically or horizontally for a sequence of colloidal hard sphere suspension images. This technique is readily adaptable to any imaging application where regions of interest are distinguished from the background by differing patterns of motion over time.
    Keywords: Life Sciences (General)
    Type: NASA/TM-2005-213989 , E-15313
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