ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Other Sources  (147)
  • Nonmetallic Materials  (147)
  • 2010-2014
  • 1995-1999  (147)
  • 1985-1989
  • 1998  (147)
  • 101
    facet.materialart.
    Unknown
    Low Power Polysilicon Sources for IR Applications (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: We have designed and fabricated polysilicon thin film infrared (IR) sources by micromachining technology. These sources are made with a lightly doped middle region for light emission and heavy doping of the supporting legs. The sources are fabricated on a 10 mm thick, low temperature process parameters in the fabrication of these silicon dioxide layer. Different doping levels were used to achieve various source resistances. From the power requirement to reach the required light emission versus source resistance curve it is seen that there exists a resistance value which minimizes the necessary input power.
    Keywords: Nonmetallic Materials
    Type: ICSICT Conference on Solid State and Integrated Circuit Technology; Oct 21, 1998 - Oct 23, 1998; Beijing; China
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 102
    facet.materialart.
    Unknown
    Thermal Protection Materials Development (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The main portion of this contract year was spent on the development of materials for high temperature applications. In particular, thermal protection materials were constantly tested and evaluated for thermal shock resistance, high-temperature dimensional stability, and tolerance to hostile environmental effects. The analytical laboratory at the Thermal Protection Materials Branch (TPMB), NASA-Ames played an integral part in the process of materials development of high temperature aerospace applications. The materials development focused mainly on the determination of physical and chemical characteristics of specimens from the various research programs.
    Keywords: Nonmetallic Materials
    Type: NASA/CR-1998-208331 , NAS 1.26:208331
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 103
    facet.materialart.
    Unknown
    A Comparison of Space and Ground Based Facility Environmental Effects for FEP Teflon (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Fluorinated Ethylene Propylene (FEP) Teflon is widely used as a thermal control material for spacecraft, however, it is susceptible to erosion, cracking, and subsequent mechanical failure in low Earth orbit. One of the difficulties in determining whether FEP Teflon will survive during a mission is the wide disparity of erosion rates observed for this material in space and in ground based facilities. Each environment contains different levels of atomic oxygen, ions, and vacuum ultraviolet (VUV) radiation in addition to parameters such as the energy of the arriving species and temperature. These variations make it difficult to determine what is causing the observed differences in erosion rates. This paper attempts to narrow down which factors affect the erosion rate of FEP Teflon through attempting to change only one environmental constituent at a time. This was attempted through the use of a single simulation facility (plasma asher) environment with a variety of Faraday cages and VUV transparent windows. Isolating one factor inside of a radio frequency (RF) plasma proved to be very difficult. Two observations could be made. First, it appears that the erosion yield of FEP Teflon with respect to that of polyimide Kapton is not greatly affected by the presence or lack of VUV radiation present in the RF plasma and the relative erosion yield for the FEP Teflon may decrease with increasing fluence. Second, shielding from charged particles appears to lower the relative erosion yield of the FEP to approximately that observed in space, however it is difficult to determine for sure whether ions, electrons, or some other components are causing the enhanced erosion.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-207918/REV1 , E-11194/REV1 , NAS 1.15:207918/REV1 , Protection of Materials and Structures from LEO Space Environment; Apr 23, 1998 - Apr 24, 1998; Toronto; Canada
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 104
    facet.materialart.
    Unknown
    Nuclear Instruments and Methods in Physics Research (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Thermoset and thermoplastic polyimides have complementary physical/mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. It is expected that a combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPNs) of thermoset LaRC(Trademark)-RP46 and thermoplastic LARC(Trademark)-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0: 100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical/mechanical properties. As expected, positronium atoms are not formed in these samples. The second life time component has been used to infer the positron trap dimensions. The "free volume" goes through a minimum at about 50:50 ratio, suggesting that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples have been discussed in this paper.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-97-208212 , NAS 1.26:208212 , Nuclear Instruments and Methods in Physics Research, Section B: (ISSN 0168-583X); 134; 113-120
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 105
    facet.materialart.
    Unknown
    Monte Carlo Computational Modeling of the Energy Dependence of Atomic Oxygen Undercutting of Protected Polymers (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A Monte Carlo computational model has been developed which simulates atomic oxygen attack of protected polymers at defect sites in the protective coatings. The parameters defining how atomic oxygen interacts with polymers and protective coatings as well as the scattering processes which occur have been optimized to replicate experimental results observed from protected polyimide Kapton on the Long Duration Exposure Facility (LDEF) mission. Computational prediction of atomic oxygen undercutting at defect sites in protective coatings for various arrival energies was investigated. The atomic oxygen undercutting energy dependence predictions enable one to predict mass loss that would occur in low Earth orbit, based on lower energy ground laboratory atomic oxygen beam systems. Results of computational model prediction of undercut cavity size as a function of energy and defect size will be presented to provide insight into expected in-space mass loss of protected polymers with protective coating defects based on lower energy ground laboratory testing.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-207423 , NAS 1.15:207423 , E-11181 , Protection of Materials and Structures from the LEO Space Environment; Apr 23, 1998 - Apr 24, 1998; Toronto; Canada
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 106
    facet.materialart.
    Unknown
    Evaluation of Chemical Coating Processes for AXAF (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The need existed at MSFC for the development and fabrication of radioisotope calibration sources of cadmium 109 and iron 55 isotopes. This was in urgent response to the AXA-F program. Several issues persisted in creating manufacturing difficulties for the supplier. In order to meet the MSFC requirements very stringent control needed to be maintained for the coating quality, specific activity and thickness. Due to the difficulties in providing the precisely controlled devices for testing, the delivery of the sources was seriously delayed. It became imperative that these fabrication issues be resolved to avoid further delays in this AXA-F observatory key component. The objectives are: 1) Research and provide expert advice on coating materials and procedures. 2) Research and recommend solutions to problems that have been experienced with the coating process. 3) Provide recommendations on the selection and preparation of substrates. 4) Provide consultation on the actual coating process including the results of the qualification and acceptance test programs. 5) Perform independent tests at UAH or MSFC as necessary.
    Keywords: Nonmetallic Materials
    Type: NASA/CR-1998-207755 , NAS 1.26:207755
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 107
    facet.materialart.
    Unknown
    CVD Diamond, DLC, and c-BN Coatings for Solid Film Lubrication (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: When the main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1 and 10(exp -6) mm(exp 3)/N-m, respectively, carbon- and nitrogen-ion-implanted, fine-grain CVD diamond and DLC ion beam deposited on fine-grain CVD diamond met the requirements regardless of environment (vacuum, nitrogen, and air).
    Keywords: Nonmetallic Materials
    Type: NASA/TM-97-206314 , NAS 1.15:206314 , E-10693 , 1997 Joint Summer Meeting; Jun 29, 1997 - Jul 02, 1997; Evanston, IL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 108
    facet.materialart.
    Unknown
    Ground Laboratory Soft X-Ray Durability Evaluation of Aluminized Teflon FEP Thermal Control Insulation (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Metallized Teflon fluorinated ethylene propylene (FEP) thermal control insulation is mechanically degraded if exposed to a sufficient fluence of soft x-ray radiation. Soft x-ray photons (4-8 A in wavelength or 1.55 - 3.2 keV) emitted during solar flares have been proposed as a cause of mechanical properties degradation of aluminized Teflon FEP thermal control insulation on the Hubble Space Telescope (HST). Such degradation can be characterized by a reduction in elongation-to-failure of the Teflon FER Ground laboratory soft x-ray exposure tests of aluminized Teflon FEP were conducted to assess the degree of elongation degradation which would occur as a result of exposure to soft x-rays in the range of 3-10 keV. Tests results indicate that soft x-ray exposure in the 3-10 keV range, at mission fluence levels, does not alone cause the observed reduction in elongation of flight retrieved samples. The soft x-ray exposure facility design, mechanical properties degradation results and implications will be presented.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-207914 , E-11186 , NAS 1.15:207914 , May 31, 1998 - Jun 04, 1998; Anaheim, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 109
    facet.materialart.
    Unknown
    Heat Conduction in Ceramic Coatings: Relationship Between Microstructure and Effective Thermal Conductivity (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Analysis of the effective thermal conductivity of ceramic coatings and its relation to the microstructure continued. Results (obtained in Task 1) for the three-dimensional problem of heat conduction in a solid containing an inclusion (or, in particular, cavity - thermal insulator) of the ellipsoidal shape, were further advanced in the following two directions: (1) closed form expressions of H tensor have been derived for special cases of ellipsoidal cavity geometry: spheroid, crack-like spheroidal cavity and needle shaped spheroidal cavity; (2) these results for one cavity have been incorporated to construct heat energy potential for a solid with many spheroidal cavities (in the approximation of non-interacting defects). This problem constitutes a basic building block for further analyses.
    Keywords: Nonmetallic Materials
    Type: NASA/CR-1998-208200 , NAS 1.26:208200
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 110
    facet.materialart.
    Unknown
    Investigation of Thermal High Cycle and Low Cycle Fatigue Mechanisms of Thick Thermal Barrier Coatings (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Thick thermal barrier coating systems in a diesel engine experience severe thermal low cycle fatigue (LCF) and high cycle fatigue (HCF) during engine operation. In this paper, the mechanisms of fatigue crack initiation and propagation in a ZrO2-8wt.% Y2O3 thermal barrier coating, under simulated engine thermal LCF and HCF conditions, are investigated using a high power CO2 laser. Experiments showed that the combined LCF/HCF tests induced more severe coating surface cracking, microspallation and accelerated crack growth, as compared to the pure LCF test. Lateral crack branching and the ceramic/bond coat interface delaminations were also facilitated by HCF thermal loads, even in the absence of severe interfacial oxidation. Fatigue damages at crack wake surfaces, due to such phenomena as asperity/debris contact induced cracking and splat pull-out bending during cycling, were observed especially for the combined LCF/HCF tests. It is found that the failure associated with LCF is closely related to coating sintering and creep at high temperatures, which induce tensile stresses in the coating after cooling. The failure associated with HCF process, however, is mainly associated with a surface wedging mechanism. The interaction between the LCF, HCF and ceramic coating creep, and the relative importance of LCF and HCF in crack propagation are also discussed based on the experimental evidence.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-206633 , NAS 1.15:206633 , E-11091 , Thermal Barrier Coatings Workshop; May 19, 1997 - May 21, 1997; Fort Mitchell, KY; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 111
    facet.materialart.
    Unknown
    Development of Paper Products from Dried Sweetpotato Stems and Peanut Shells (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: One of the goals of NASA's Advanced Life Support Program (ALS) for sustaining human life in space is to achieve a closed system in plant production and usage. That all inedible plant parts should be recycled or used in some way. A Tuskegee University team researching sweetpotato and peanut for ALS has developed paper products from dried sweet-potato stems and peanut shells. In this study, the sweet-potato stems and peanut shells were soaked separately in water for 48 hours. After 48 hours, researchers manually separated the pulp and the unusable parts. To form the paper, 160 g of pulp and water mixture was poured through a 15.1 cm (diameter) filtration funnel and the pulp was trapped on 15 cm (diameter) filter paper. The filter paper and pulp were dried in an air oven, and the filter paper was removed, An examination under a scanning electron microscope showed that the sweet-potato paper was composed of "fibers", whereas the peanut shell paper was composed of "blocks". Results of physical testing showed that the sweet-potato stem paper was stronger than the peanut shell paper. It is anticipated that there may be other uses of these products such as writing paper, bags and packaging material. Because of its biodegradability, it can be incorporated into the resource recycling system at the end of its use.
    Keywords: Nonmetallic Materials
    Type: NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and Education; 2 and 3; 495-499; NONP-NASA-CD-1999011585
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 112
    facet.materialart.
    Unknown
    Rotating Pressure and Temperature Measurements on Scale Model Fans Using Luminescent Paints (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Pressure and temperature sensitive paint (PSP, TSP) technology is a rapidly developing measurement technique that is widely accepted in external aerodynamic wind tunnel measurements. Almost all quantitative full field measurements have been on stationary surfaces. Rotating pressure and temperature measurements were successfully acquired during scale-model fan tests in the NASA Lewis Research Center 9 foot by 15 foot low speed wind tunnel at speeds as high as 9500 RPM. The use of PSP and TSP on rotating surfaces presents additional challenges to data acquisition. This paper describes in detail the techniques used to acquire global rotating pressure and temperature measurements and overcome the problems associated with this type of measurement. These include illumination and detection problems associated with moving surfaces, temperature dependence of PSP and limited emitted light available from short duration illumination sources. Solutions to these problems as well as pressure and temperature results will be discussed.
    Keywords: Nonmetallic Materials
    Type: AIAA Paper 98-3452 , Joint Propulsion; Jul 13, 1998 - Jul 15, 1998; Cleveland, OH; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 113
    facet.materialart.
    Unknown
    Evaluation of HCFC AK 225 Alternatives for Precision Cleaning and Verification (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Maintaining qualified cleaning and verification processes are essential in an production environment. Environmental regulations have and are continuing to impact cleaning and verification processing in component and large structures, both at the Michoud Assembly Facility and component suppliers. The goal of the effort was to assure that the cleaning and verification proceeds unimpeded and that qualified, environmentally compliant material and process replacements are implemented and perform to specifications. The approach consisted of (1) selection of a Supersonic Gas-Liquid Cleaning System; (2) selection and evaluation of three cleaning and verification solvents as candidate alternatives to HCFC 225 (Vertrel 423 (HCFC), Vertrel MCA (HFC/1,2-Dichloroethylene), and HFE 7100DE (HFE/1,2 Dichloroethylene)); and evaluation of an analytical instrumental post cleaning verification technique. This document is presented in viewgraph format.
    Keywords: Nonmetallic Materials
    Type: NASA/CR-1998-208099 , NAS 1.26:208099 , Aerospace Environmental Technology Conference; Jun 01, 1998; Huntsville, Al; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 114
    facet.materialart.
    Unknown
    Evaluation of Alkaline Cleaner Materials (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Alkaline cleaners used to process aluminum substrates have contained chromium as the corrosion inhibitor. Chromium is a hazardous substance whose use and control are described by environmental laws. Replacement materials that have the characteristics of chromated alkaline cleaners need to be found that address both the cleaning requirements and environmental impacts. This report will review environmentally friendly candidates evaluated as non-chromium alkaline cleaner replacements and methods used to compare those candidates one versus another. The report will also list characteristics used to select candidates based on their declared contents. It will also describe and evaluate methods used to discriminate among the large number of prospective candidates.
    Keywords: Nonmetallic Materials
    Type: NASA/CR-1998-208098 , NAS 1.26:208098 , Aerospace Environmental Technology; Jun 01, 1998; Huntsville, AL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 115
    facet.materialart.
    Unknown
    On-Orbit Teflon(trademark) FEP Degradation (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon(trademark) FEP (fluorinated ethylene propylene), used as the outer layer of the multi-layer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon(trademark) FEP sample evaluation and additional testing of pristine Teflon(trademark) FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations, and that the damage increased with the combined total dose of electrons, protons, UV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the Teflon(trademark) FEP.
    Keywords: Nonmetallic Materials
    Type: Space Simulations; Oct 26, 1998 - Oct 29, 1998; Unknown
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 116
    facet.materialart.
    Unknown
    Sintering and Creep Behavior of Plasma-Sprayed Zirconia and Hafnia Based Thermal Barrier Coatings (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The sintering and creep of plasma-sprayed ceramic thermal barrier coatings under high temperature conditions are complex phenomena. Changes in thermomechanical and thermophysical properties and in the stress response of these coating systems as a result of the sintering and creep processes are detrimental to coating thermal fatigue resistance and performance. In this paper, the sintering characteristics of ZrO2-8wt%y2O3, ZrO2-25wt%CeO2-2.5wt%Y2O3, ZrO2-6w%NiO- 9wt%Y2O3, ZrO2-6wt%Sc2O3-2wt%y2O3 and HfO2-27wt%y2O3 coating materials were investigated using dilatometry. It was found that the HfO2-Y2O3 and baseline ZrO2-Y2O3 exhibited the best sintering resistance, while the NiO-doped ZrO2-Y2O3 showed the highest shrinkage strain rates during the tests. Higher shrinkage strain rates of the coating materials were also observed when the specimens were tested in Ar+5%H2 as compared to in air. This phenomenon was attributed to an enhanced metal cation interstitial diffusion mechanism under the reducing conditions. It is proposed that increased chemical stability of coating materials will improve the material sintering resistance.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-208406 , NAS 1.15:208406 , E-11239 , Metallurgical Coatings and Thin Films; Apr 27, 1998 - May 01, 1998; San Diego, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 117
    facet.materialart.
    Unknown
    Mechanical Properties Degradation of Teflon(Trademark) FEP Returned from the Hubble Space Telescope (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: After 6.8 years on orbit, degradation has been observed in the mechanical properties of second-surface metalized Teflon(Reg) FEP (fluorinated ethylene propylene) used on the Hubble Space Telescope (HST) on the outer surface of the multi-layer insulation (MLI) blankets and on radiator surfaces. Cracking of FEP surfaces on HST was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission (SM1) conducted 3.6 years after HST was put into orbit. Astronaut observations and photographs from the second servicing mission (SM2), conducted after 6.8 years on orbit, revealed severe cracks in the FEP surfaces of the MLI on many locations around the telescope. This paper describes results of mechanical properties testing of FEP surfaces exposed for 3.6 years and 6.8 years to the space environment on HST. These tests include tensile testing, surface micro-hardness testing, and bend testing.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-206618 , E-11051 , NAS 1.15:206618 , AIAA Paper 98-0895 , Aerospace Sciences Meeting and Exhibit; Jan 12, 1998 - Jan 15, 1998; Reno, NV; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 118
    facet.materialart.
    Unknown
    Method for Waterproofing Ceramic Materials (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by e.g., burning, the silica remains and the ceramic is easily rewaterproofed. An alumina containing TABI insulation which absorbs more that five times its weight of water, absorbs less than 10 wt. % water after being waterproofed according to the method of the invention.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 119
    facet.materialart.
    Unknown
    Room Temperature and Elevated Temperature Composite Sandwich Joint Testing (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Testing of composite sandwich joint elements has been completed to verify the strength capacity of joints designed to carry specified running loads representative of a high speed civil transport wing. Static tension testing at both room and an elevated temperature of 350 F and fatigue testing at room temperature were conducted to determine strength capacity, fatigue life, and failure modes. Static tension test results yielded failure loads above the design loads for the room temperature tests, confirming the ability of the joint concepts tested to carry their design loads. However, strength reductions as large as 30% were observed at the elevated test temperature, where all failure loads were below the room temperature design loads for the specific joint designs tested. Fatigue testing resulted in lower than predicted fatigue lives.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-208742 , L-17746 , NAS 1.15:208742
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 120
    facet.materialart.
    Unknown
    Affordable, Robust Ceramic Joining Technology (ARCJoinT) (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Joining is recognized as one of the enabling technologies for the application of silicon carbide-based ceramic and composite components in a number of demanding and high temperature applications in aerospace and ground-based systems. An affordable, robust ceramic joining technology (ARCJoinT) for joining of silicon carbide-based ceramics and fiber reinforced composites has been developed. This technique is capable of producing joints with tailorable thickness and composition. A wide variety of silicon carbide-based ceramics and composites, in different shapes and sizes, have been joined using this technique. These joints maintain their mechanical strength up to 1350 C in air. This technology is suitable for the joining of large and complex shaped ceramic and composite components and with certain modifications, can be applied to repair ceramic components damaged in service.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 121
    facet.materialart.
    Unknown
    Effect of Pigmentation in Particulate Formation from Fluoropolymer Thermodegradation in Microgravity (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-10
    Description: Fires aboard spacecraft have occurred as a result of overheated electrical wires and thermodegradation of their insulation, which is composed of fluoropolymers. The particulate products of polymer thermodegradation are only 20-50 run in diameter and are thought to play a role in "polymer fume fever". Therefore an experimental study of the particulates produced by intense ohmic heating of various fluoropolymer-insulated 20 AWG copper wire (representative of spacecraft materials) was undertaken in normal gravity and in microgravity. The 2.2 s drop facility at NASA LeRC and 1.5 s drop facility at the Colorado School of Mines were used to achieve low gravity conditions. Thermophoretic sampling was used for particulate collection. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to characterize the smoke particulates. It was found that the color of PTFE (Polytetrafluoroethylene) insulation has an overwhelming effect on the size, shape, morphology and, composition of the particulates. Size distributions and shape analyses using computerized image analysis showed that particle size distributions were also dependent on the pigment of the fluoropolymer insulation. The influence of pigment was observed in experiments under both normal and microgravity. Under microgravity conditions, owing to the lack of natural convective transport of particulates, much more particle aggregation was observed, and the nature of the aggregates was dependent on the color of the insulation.
    Keywords: Nonmetallic Materials
    Type: AIAA Paper 98-0814
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 122
    facet.materialart.
    Unknown
    Effect of X-Rays on the Mechanical Properties of Aluminized FEP Teflon(R) (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Pieces of the multilayer insulation (MLI) that is integral to the thermal control of the Hubble Space Telescope (HST) have been returned by two servicing missions after 3.6 and 6.8 years in orbit. They reveal that the outer layer, which is made from 5 mil (0.13 mm)thick aluminized fluorinated ethylene propylene(FEP) Teflon(R), has become severely embrittled. Although possible agents of this embrittlement include electromagnetic radiation across the entire solar spectrum, trapped particle radiation, atomic oxygen, and thermal cycling, intensive investigations have not yielded unambiguous causes. Previous studies utilizing monoenergetic photons in the 69-1900 eV range did not cause significant embrittlement, even at much higher doses than were experienced by the HST MLI. Neither did x-rays in the 3 to 10 keV range generated in a modified electron beam evaporator. An antidotal aluminized FEP sample that was exposed to an intensive dose from unfiltered Mo x-ray radiation from a rotating anode generator, however, did show the requisite embrittlement. Thus, a study was undertaken to determine the effects of x-ray exposure on the embrittlement of aluminized FEP in hopes that it might elucidate the HST MLI degradation mechanism. Tensile specimens of aluminized 5 mil thick FEP were exposed to a constant fluence of unfiltered x-ray radiation from a Mo target whose maximum energy ranged from 20-60 kV. Other samples were annealed, thermally cycled (100x) between 77-333 K, or cycled and irradiated. Tensile tests and density measurements were then performed on the samples. Only the samples which had been irradiated had the drastically reduced elongation-to-break, characteristic of the HST samples. Thermal cycling may accelerate the embrittlement, but the effect was near the scatter in the measurements. Annealing and thermal cycling had no apparent effect. Only the samples which had been irradiated and annealed showed significant density increases, likely implicating polymer chain scission and annealing.
    Keywords: Nonmetallic Materials
    Type: 20th Space Simulation Conference: The Changing Testing Paradigm; 211-222; NASA/CR-1998-208598-Preprint
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 123
    facet.materialart.
    Unknown
    Polyimide Fibers (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: A polyimide fiber having textile physical property characteristics and the process of melt extruding same from a polyimide powder. Polyimide powder formed as the reaction product of the monomers 3.4'-ODA and ODPA, and end- capped with phthalic anhydride to control the molecular weight thereof, is melt extruded in the temperature range of 340 C. to 360 C. and at heights of 100.5 inches. 209 inches and 364.5 inches. The fibers obtained have a diameter in the range of 0.0068 inch to 0.0147 inch; a mean tensile strength in the range of 15.6 to 23.1 ksi; a mean modulus of 406 to 465 ksi, and a mean elongation in the range of 14 to 103%.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 124
    facet.materialart.
    Unknown
    Ablation Resistant Zirconium and Hafnium Ceramics (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: High temperature ablation resistant ceramic composites have been made. These ceramics are composites of zirconium diboride and zirconium carbide with silicon carbide, hafnium diboride and hafnium carbide with silicon carbide and ceramic composites which contain mixed diborides and/or carbides of zirconium and hafnium. along with silicon carbide.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 125
    facet.materialart.
    Unknown
    Organopolysiloxane Waterproofing Treatment for Porous Ceramics (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Rigid and flexible porous ceramics, including thermal insulation of a type used on space vehicles, are waterproofed by a treatment which comprises applying an aqueous solution of an organopolysiloxane water-proofing agent having reactive silanol groups to the surface of the ceramic and then heating the treated ceramic to form a waterproofed ceramic. The organopolysiloxane is formed by the hydrolysis and partial condensation of di- and trialkoxyfunctional alkylalkoxysilanes having 1-10 carbon atom hydrocarbyl groups.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 126
    facet.materialart.
    Unknown
    Process for making silicon carbide reinforced silicon carbide composite (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A process comprising the steps of: a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C., b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbon c) providing a cover mix comprising: i) an alloy comprising a metallic infiltrant and the coating element, and ii) a resin, d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body, e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, and f) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 127
    facet.materialart.
    Unknown
    Method for Molding Structural Parts Utilizing Modified Silicone Rubber (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This invention improves upon a method for molding structural parts from preform material. Preform material to be used for the part is provided. A silicone rubber composition containing entrained air voids is prepared. The silicone rubber and preform material assembly is situated within a rigid mold cavity used to shape the preform material to die desired shape. The entire assembly is heated in a standard heating device so that the thermal expansion of the silicone rubber exerts the pressure necessary to force the preform material into contact with the mold container. The introduction of discrete air voids into the silicone rubber allows for accurately controlled pressure application on the preform material at the cure temperature.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 128
    facet.materialart.
    Unknown
    Microcapsules and Methods for Making (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Methods of forming multi-lamellar microcapsules having alternating layers of hydrophilic and hydrophobic immiscible liquid phases have been developed using different polymer/solvent systems. The methods use liquid-liquid diffusion and simultaneous lateral phase separation, controlled by proper timed-sequence exposures of immiscible phases and low shear mixing, to form narrow size distributions of spherical, multilamellar microcapsules. The use of special formulations of solubilized drugs, surfactants, and polymeric co-surfactants in aqueous vehicles which are dispersed in hydrocarbon solvents containing small quantities of oil, low molecular weight co-surfactants and glycerides that are aqueous insoluble enables the formation of unique microcapsules which can carry large amounts of pharmaceuticals in both aqueous and non-aqueous solvent compartments. The liquid microcapsules are quickly formed in a single step and can include a polymeric outer 'skin' which protects the microcapsules during physical manipulation or exposure to high shear forces. Water-in-oil and oil-in-water microcapsules have been formed both in 1 x g and in microgravity, which contain several types of drugs co-encapsulated within different fluid compartments inside the same microcapsule. Large, spherical multi-lamellar microcapsules have been formed including a cytotoxic drug co-encapsulated with a radiocontrast medium which has advantages for chemoembolization of vascular tumors. In certain cases, crystals of the drug form inside the microcapsules providing zero-order and first order, sustained drug release kinetics.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 129
    facet.materialart.
    Unknown
    Crack Branching and Fracture Mirror Data of Glasses and Advanced Ceramics (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The fracture mirror and crack branching constants were determined from three glasses and nine advanced ceramics tested under various loading and specimen configurations in an attempt to use the constants as a data base for fractography. The ratios of fracture mirror or crack branching constant to fracture toughness were found to be approximately two for most ceramic materials tested. A demonstration of how to use the two constants as a tool for verifying stress measurements was presented for silicon nitride disk specimens subjected to high-temperature, constant stress-rate biaxial flexure testing.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-206536 , NAS 1.15:206536 , E-11019
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 130
    facet.materialart.
    Unknown
    Analysis of Hard Thin Film Coating (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.
    Keywords: Nonmetallic Materials
    Type: NASA/CR-1998-205199 , NAS 1.26:205199
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 131
    facet.materialart.
    Unknown
    Monte Carlo Simulation of Endlinking Oligomers (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This report describes initial efforts to model the endlinking reaction of phenylethynyl-terminated oligomers. Several different molecular weights were simulated using the Bond Fluctuation Monte Carlo technique on a 20 x 20 x 20 unit lattice with periodic boundary conditions. After a monodisperse "melt" was equilibrated, chain ends were linked whenever they came within the allowed bond distance. Ends remained reactive throughout, so that multiple links were permitted. Even under these very liberal crosslinking assumptions, geometrical factors limited the degree of crosslinking. Average crosslink functionalities were 2.3 to 2.6; surprisingly, they did not depend strongly on the chain length. These results agreed well with the degrees of crosslinking inferred from experiment in a cured phenylethynyl-terminated polyimide oligomer.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-207649 , NAS 1.15:207649 , L-17710
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 132
    facet.materialart.
    Unknown
    Evaluation of Composite Honeycomb Sandwich Panels Under Compressive Loads at Elevated Temperatures (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Fourteen composite honeycomb sandwich panels were tested to failure under compressive loading. The test specimens included panels with both 8 and 24-ply graphite-bismaleimide composite facesheets and both titanium and graphite-polyimide core materials. The panels were designed to have the load introduced through fasteners attached to pairs of steel angles on the ends of the panels to simulate double shear splice joints. The unloaded edges were unconstrained. Test temperatures included room temperature, 250F, and 300F. For the room and 250F temperature tests, the 24-ply specimen failure strains were close to the unnotched allowable strain values and failure loads were well above the design loads. However, failure strains much lower than the unnotched allowable strain values, and failure loads below the design loads were observed with several of the 8-ply specimens. For each individual test temperature, large variations in the failure strains and loads were observed for the 8-ply specimens. Dramatic decreases in the failure strains and loads were observed for the 24-ply specimens as the test temperature was increased from 250F to 300F. All 8-ply specimens appeared to have failed in a facesheet strength failure mode for all test temperatures. The 24-ply specimens displayed appreciably greater amounts of bending prior to failure than the 8-ply specimens, and panel buckling occurred prior to facesheet strength failure for the 24-ply room and 250F temperature tests.
    Keywords: Nonmetallic Materials
    Type: NASA/TP-1998-207645 , L-17666 , NAS 1.60:207645
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 133
    facet.materialart.
    Unknown
    Tailoring Thin Film-Lacquer Coatings for Space Application (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Thin film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission's thermal control requirements, there is often a need for a variation of solar absorptance (Alpha(s)), emittance (epsilon) and/or highly specular surfaces. The utilization of thin film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of Alpha(s)/epsilon ratios. Thin film coatings' radiative properties can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin film application without the cost and difficulty associated with polishing.
    Keywords: Nonmetallic Materials
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 134
    facet.materialart.
    Unknown
    Design, Operation, and Modeling of a Vertical APCVD Reactor for Silicon Carbide Film Growth (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-10
    Description: An atmospheric pressure chemical vapor deposition (APCVD) reactor utilizing a unique vertical geometry which enables 3C-SiC films to be grown on two, 4-inch diameter Si wafers has been constructed. Contrary to expectations, 3C-SiC films grown in this reactor are thickest at the downstream end of the substrates. To better understand the reason for the thickness distribution on the wafers, an axisymmetric finite-element model of the gas flow in the reactor was constructed. The model uses the ANSYS53 Flowtran package and includes compressible and temperature-dependent fluid properties in laminar or turbulent flow. It does not include reaction chemistry or unsteady flow. The ANSYS53 results predict that the cool, inlet fluid falls through the inlet pipe and the warm, diffuser region like a jet. This jet impinges on top of the susceptor and gets diverted to the reactor side walls, where it flows to the bottom of the reactor, turns, and slowly rises along the face of the susceptor. This may explain why the SiC films are thickest at the downstream side of the wafers, as gas containing fresh reactants first passes over this region. Modeling results are presented for both one atmosphere and one half atmosphere reactor pressure.
    Keywords: Nonmetallic Materials
    Type: Journal of Chemical Vapor Deposition
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 135
    facet.materialart.
    Unknown
    Annealing Effects on Creep and Rupture of Polycrystalline Alumina-Based Fibers (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Continuous-length polycrystalline aluminum-oxide-based fibers are being considered as reinforcements for advanced high-temperature composite materials. For these fine-grained fibers, basic issues arise concerning grain growth and microstructural instability during composite fabrication and the resulting effects on the fiber's thermo-mechanical properties. To examine these issues, commercially available Nextel 610 (alumina) and Altex (alumina-silica) fibers were annealed at 1100 and 1300 C for up to 100 hr in air. Changes in fiber microstructure, fiber tensile creep, stress rupture, and bend stress relaxation (BSR) that occurred with annealing were then determined. BSR tests were also used to compare as-received and annealed fibers to other polycrystalline oxide fibers. Annealing was shown to have a significant effect, particularly on the Altex fiber, and caused it to have increased creep resistance.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-208841 , E-10021 , NAS 1.15:208841
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 136
    facet.materialart.
    Unknown
    Space Shuttle Pinhole Formation Mechanism Studies (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Pinholes have been observed to form on the wing leading edge of the space shuttle after about 10-15 flights. In this report we expand upon previous observations by Christensen (1) that these pinholes often form along cracks and are associated with a locally zinc-rich area. The zinc appears to come from weathering and peeling paint on the launch structure. Three types of experimental examinations are performed to understand this issue further: (A) Detailed microstructural examination of actual shuttle pinholes (B) Mass spectrometric studies of coupons containing, actual shuttle pinholes and (C) Laboratory furnace studies of ZnO/SiC reactions and ZnO/SiC protected carbon/carbon reaction. On basis of these observations we present a detailed mechanism of pinhole formation due to formation of a corrosive ZnO-Na-2-O-SiO2 ternary glass, which flows into existing cracks and enlarges them.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-208659 , NAS 1.15:208659 , E-11351
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 137
    facet.materialart.
    Unknown
    Microstructural, Chemical and Mechanical Characterization of Polymer-Derived Hi-Nicalon Fibers with Surface Coatings (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Room temperature tensile strengths of as-received Hi-Nicalon fibers and those having BN/SiC, p-BN/SiC, and p-B(Si)N/SiC surface coatings, deposited by chemical vapor deposition, were measured using an average fiber diameter of 13.5 microns. The Weibull statistical parameters were determined for each fiber. The average tensile strength of uncoated Hi-Nicalon on was 3.19 +/- 0.73 GPa with a Weibull modulus of 5.41. Strength of fibers coated with BN/SiC did not change. However, coat with p-BN/SiC and p-B(Si)N/SiC surface layers showed strength loss of approx. 10 and 35 percent, respectively, compared with as-received fibers. The elemental compositions of the fibers and the coatings were analyzed using scanning Auger microprobe and energy dispersive x-ray spectroscopy. The BN coating was contaminated with a large concentration of carbon and some oxygen. In contrast, p-BN, p-B(Si)N, and SiC coatings did not show any contamination. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction. Hi-Nicalon fiber consists of the P-SIC nanocrystals ranging in size from 1 to 30 nm embedded in an amorphous matrix. TEM analysis of the BN coating revealed four distinct layers with turbostatic structure. The p-BN layer was turbostratic and showed considerable preferred orientation. The p-B(Si)N was glassy and the silicon and boron were uniformly distributed. The silicon carbide coating was polycrystalline with a columnar structure along the growth direction. The p-B(Si)N/SiC coatings were more uniform, less defective and of better quality than the BN/SiC or the p-BN/SiC coatings.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-208502 , NAS 1.15:208502 , E-11304
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 138
    facet.materialart.
    Unknown
    Elevated Temperature Compressive Strength Properties of Oxide Dispersion Strengthened NiAl After Cryo-milling and Roasting in Nitrogen (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: In an effort to superimpose two different elevated temperature strengthening mechanisms in NiAl, several lots of oxide dispersion strengthened (ODS) NiAl powder have been cryo-milled in liquid nitrogen to introduce AlN particles at the grain boundaries. As an alternative to cryo-milling, one lot of ODS NiAl was roasted in nitrogen to produce AlN. Both techniques resulted in hot extruded AlN-strengthened, ODS NiAl alloys which were stronger than the base ODS NiAl between 1200 and 1400 K. However, neither the cryo-milled nor the N2-roasted ODS NiAl alloys were as strong as cryo-milled binary NiAl containing like amounts of AlN. The reason(s) for the relative weakness of cryo-milled ODS NiAl is not certain; however the lack of superior strength in N2-roasted ODS NiAl is probably due to its relatively large AlN particles.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-208399 , NAS 1.15:208399 , E-11168
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 139
    facet.materialart.
    Unknown
    NASA/Air Force/Environmental Protection Agency Interagency Depainting Study (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: Many popular and widely used paint stripping products have traditionally contained methylene chloride as their main active ingredient. However, the Environmental Protection Agency (EPA) has critically curved the allowable use of methylene chloride under the National Emission Standard for Hazardous Air Pollutants regulating Aerospace Manufacturing and Rework Facilities . Compliance with this rule was mandatory by September 1998 for affected facilities. An effort is underway to identify and evaluate alternative depainting technologies emphasizing those believed both effective and environmentally benign. On behalf of the EPA and in cooperation with the United States Air Force, the National Aeronautics and Space Administration is conducting a technical assessment of several alternative technologies ( i.e. : chemical stripping, two CO2 blasting processes, CO2 xenon lamp coating removal, CO2 Laser stripping, plastic media blasting, sodium bicarbonate wet stripping, high pressure water stripping, and wheat starch blasting). These depainting processes represent five removal method categories, namely abrasive, impact, cryogenic, thermal, and/or molecular bonding dissociation. This paper discusses the test plan and parameters for this interagency study. Several thicknesses of clad and non-clad aluminum substrates were used to prepare test specimens. Each depainting process has been assigned a specimen lot, all of which have completed three to five stripping cycles. Numerous metallurgical evaluations are underway to assess the impact of these alternative depainting processes upon the structural integrity of the substrate.
    Keywords: Nonmetallic Materials
    Type: Using Environmental Safety and Occupational Progress to Reduce Life Cycle Cost; Nov 11, 1998 - Nov 18, 1998; Morristown, NJ; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 140
    facet.materialart.
    Unknown
    Reciprocal Space Mapping of Macromolecular Crystals in the Laboratory (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The technique of reciprocal space mapping applied to the physical measurement of macromolecular crystals will be described. This technique uses a triple axis diffractometer setup whereby the monochromator is the first crystal, the sample is the second and the third crystal (of the same material as the monochromator) analyzes the diffracted beam. The geometry is such that it is possible to separate mosaic volume effects from lattice strain effects. The deconvolution of the instrument parameters will also be addressed. Results from measurements at Brookhaven National Synchrotron Radiation Source carried out on microgravity and ground-grown crystals will be presented. The required beam characteristics for reciprocal space mapping are also ideal for topographic studies and the first topographs ever recorded from microgravity protein crystal samples will be shown. We are now working on a system which will enable reciprocal space mapping, mosaicity and topography studies to be carried out in the home laboratory. This system uses a rotating anode X-ray source to provide an intense beam then a Bartels double crystal, four reflection monochromator to provide the spectral and geometric beam conditioning necessary such that the instrument characteristics do not mask the measurement. This is coupled to a high precision diffractometer and sensitive detector. Commissioning data and first results from the system will be presented.
    Keywords: Nonmetallic Materials
    Type: Crystallization of Biological Macromolecules; May 03, 1998; Granada; Spain
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 141
    facet.materialart.
    Unknown
    Fluorescence of Pentavalent Chromium in SiO2 Sol-Gel Glasses (1998)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: Chromium ions are very attractive to optical spectroscopy and laser physics. It is well known that the first laser in the history is a ruby laser activated with Cr(3+). It was found in early nineties that Cr(4+) was also an interesting lasing ion in the near infrared, and various Cr(4+) lasers have been developed. Very recently, it was reported that Cr(2+) doped in CdSe crystals showed lasing action in the infrared. The above achievement have stimulated an interest in searching for Cr(5+) and investigating its optical properties. Cr(5+) is isoelectronic with Ti(3+) and V(4+), having electron configuration 3d1. Ti(3+) is the active center of commercial cw and femtosecond sapphire lasers, tunable in the range 680-1100 nm. V(4+) doped in YAlO3 and Al2O3 showed broad band emission near 635 nm. Although EPR results of Cr(5+) were reported, the optical properties were less studied. Herren et al. reported an observation of luminescence from Cr doped in SiO2 sol-gel glass. The luminescence spectrum was assigned to pentavalent ions in their first paper, and later it was identified to be the emission from the charge transfer transition of Cr(6+). The first observation of photoluminescence from octahedrally coordinated Cr(5+) in BaCaMg aluminate glasses was reported very recently. In this work, we report luminescence results of Cr doped SiO2 sol-gel glasses. The fluorescence spectra are very different from Herrens' results, and we believe it originates from pentavalent Cr.
    Keywords: Nonmetallic Materials
    Type: NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and Education; 2 and 3; 639-643; NONP-NASA-CD-1999011585
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 142
    facet.materialart.
    Unknown
    Solid Lubrication Fundamentals and Applications. Properties of Clean Surfaces: Adhesion, Friction, and Wear (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This chapter presents the adhesion, friction, and wear behaviors of smooth, atomically clean surfaces of solid-solid couples, such as metal-ceramic couples, in a clean environment. Surface and bulk properties, which determine the adhesion, friction, and wear behaviors of solid-solid couples, are described. The primary emphasis is on the nature and character of the metal, especially its surface energy and ductility. Also, the mechanisms of friction and wear for clean, smooth surfaces are stated.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-107249/CH3 , NAS 1.15:107249-CH3 , E-9863-3
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 143
    facet.materialart.
    Unknown
    Solid Lubrication Fundamentals and Applications: Introduction and Background (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This chapter presents an introduction and historical background to the field of tribology, especially solid lubrication and lubricants and sets them in the perspective of techniques and materials in lubrication. Also, solid and liquid lubrication films are defined and described.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-107249/CH1-Rev1 , NAS 1.15:10749-Rev-1 , E-9863-1
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 144
    facet.materialart.
    Unknown
    Solid Lubrication Fundamentals and Applications (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This chapter describes powerful analytical techniques capable of sampling tribological surfaces and solid-film lubricants. Some of these techniques may also be used to determine the locus of failure in a bonded structure or coated substrate; such information is important when seeking improved adhesion between a solid-film lubricant and a substrate and when seeking improved performance and long life expectancy of solid lubricants. Many examples are given here and through-out the book on the nature and character of solid surfaces and their significance in lubrication, friction, and wear. The analytical techniques used include the late spectroscopic methods.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-107249/CH2 , E-9863/CH2 , NAS 1.15:107249/CH2
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 145
    facet.materialart.
    Unknown
    Properties Data for Adhesion and Surface Chemistry of Aluminum: Sapphire-Aluminum, Single-Crystal Couple (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: An investigation was conducted to examine the adhesion and surface chemistry of single-crystal aluminum in contact with single-crystal sapphire (alumina). Pull-off force (adhesion) measurements were conducted under loads of 0. I to I mN in a vacuum of 10(exp -1) to 10(exp -9) Pa (approx. 10(exp -10) to 10(exp -11) torr) at room temperature. An Auger electron spectroscopy analyzer incorporated directly into an adhesion-measuring vacuum system was primarily used to define the chemical nature of the surfaces before and after adhesion measurements. The surfaces were cleaned by argon ion sputtering. With a clean aluminum-clean -sapphire couple the mean value and standard deviation of pull-off forces required to separate the surfaces were 3015 and 298 micro-N, respectively. With a contaminated aluminum-clean sapphire couple these values were 231 and 241 micro-N. The presence of a contaminant film on the aluminum surface reduced adhesion by a factor of 13. Therefore, surfaces cleanliness, particularly aluminum cleanliness, played an important role in the adhesion of the aluminum-sapphire couples. Pressures on the order of 10(exp -8) to 10(exp -9) Pa (approx. 10(exp -10) to 10(exp -11) torr) maintained a clean aluminum surface for only a short time (less then 1 hr) but maintained a clean sapphire surface, once it was achieved, for a much longer time.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-1998-206638 , NAS 1.15:206638 , E-11105
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 146
    facet.materialart.
    Unknown
    Development of CST(registered) for a Solventless Sprayable Coating, MCC-1 (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: This paper discusses an innovative process called convergent spray technology (CST), as applied to the development and successful implementation of MCC-1 coating for the Shuttle/SRB as a primary Thermal Protection System (TPS). The session will illustrate the environmental and the process benefits of the MCC-1 technology, show the systematic steps taken for the development of the technology that included statistically conducted sensitivity studies of about 34 variables, and illustrate that the technology is "Field-proven" based on the process and post-flight successes on the Shuttle/SRB. The application of this technology to other aerospace and commercial programs will be introduced to illustrate the wide range of possibilities.
    Keywords: Nonmetallic Materials
    Type: Technology 2008; Nov 03, 1998 - Nov 05, 1998; Boston, MA; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 147
    facet.materialart.
    Unknown
    The Successful Transfer of Space Derived Convergent Spray: An Application for Industrial Roof Coatings and Interstate Bridge Repair (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: A partnership was formed between the National Aeronautics and Space Administration (NASA), the Environmental Protection Agency (EPA), and United Technologies USBI Company to develop, demonstrate, and evaluate a technology that uses a solventless spray process for depositing a lightweight, highly filled roof coating on low-sloped commercial roofs. Although the levels of volatile organic compound (VOC) emissions from industrial roof coating's and paint operations have been reduced in recent years, this partnership,was an effort to further reduce VOC emission levels and to also demonstrate the use of reclaimed automobile tire rubber as a filler material in roof coating systems. Different materials and coatings were evaluated and tested before the final selection used to coat the roofs of two small buildings at NASA's Marshall Space Flight Center during fiscal year 1997. The project successfully leveraged the investment of EPA, NASA and private sector resources to demonstrate a pre-commercial roofing coating process. This process utilizes the Convergent Spray Technologies process, which was initially developed by USBI to apply highly-filled, thermal protection coatings to the Space Shuttle Solid Rocket Boosters. A second partnership between the NASA, Federal Highway Administration, Alabama Department of Transportation and USBI Company was formed to develop and demonstrate the Convergent Spray Technology as a method of applying a skid resistant coating to interstate roads and concrete bridge decking's. Again, different materials and coatings were evaluated and tested before the final selection of ground flint and resin. Two field demonstrations were performed during fiscal year 1997 for the purpose of evaluating the coating system under actual highway conditions. These coatings were applied on Interstate 65 near Huntsville Alabama, and in the Mobile Bankhead tunnel. The system performed this task without the use of harmful solvents, and accomplished the process in a single application. This project successfully leveraged the investment of NASA, Federal Highway Administration, the Alabama Department of Transportation, and private sector funding.
    Keywords: Nonmetallic Materials
    Type: Aerospace Environmental Technology; Jun 01, 1998 - Jun 03, 1998; Huntsville, AL; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...