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  • Other Sources  (484)
  • NONMETALLIC MATERIALS  (484)
  • 1980-1984  (484)
  • 1950-1954
  • 1984  (201)
  • 1982  (160)
  • 1981  (123)
  • 1
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    An atomic oxygen facility for studying polymer materials for spacecraft applications (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A nozzle beam facility utilizing microwave discharge on a helium carrier gas seeded with oxygen to produce atomic oxygen fluxes of the order of 10 to the 15th power atoms/cu cm/sec is described. In addition, limited test results obtained from exposing a graphite/epoxy composite and Kapton (H) film are presented in terms of mass loss measurements and changes in surface morphology.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Goddard Space Flight Center 13th Space Simulation Conf.; p 169-192
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  • 2
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    Thermal control coatings experiment (A0138-6) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objectives of this LDEF experiment are to verify the validity of space environment simulation performed in the laboratory in order to measure the stability of the thermo-optical properties of thermal control coatings, and to compare the behavior in space of some materials for which the available ultraviolet solar simulation is inadequate (especially in the far ultraviolet). The experimental approach is to passively expose samples of the thermal coatings of interest. These coatings include black paint, aluminum paint, white paint, a solar absorber, an optical surface reflector, second surface mirrors, metal coatings, and silica fabrics. Preflight and postflight measurements of thermo-optical properties will be compared to determine the effects of space environment exposure.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 52-53
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  • 3
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    Atomic-oxygen stimulated outgassing (A0034) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objective of this experiment is to determine if the impingement of atomic oxygen in near-Earth orbit is a major factor in producing optically damaging outgassed products. The expected results will be to obtain samples which have been exposed to atomic oxygen for long durations. Analysis of these samples will determine if the impingement of atomic oxygen on the thermal control surfaces stimulates a significant amount of outgassed products. This experiment will give a clearer picture of the contamination problem and will assist in assuring that future Shuttle payloads, such as the Space Telescope and High-Energy Astronomy Observatory, will not experience Skylab contamination levels. Selected thermal control surfaces will be exposed to the atomic oxygen in near-Earth orbit. Passive collecting samples will collect any induced outgassing resulting from oxygen impingement. The optical condition of the passive samples will be measured using a ground-based integrating sphere reflectometer and a directional reflectometer.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 11-13
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  • 4
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    Shuttle tile environments and loads (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The Shuttle tile ascent environments are discussed and the procedures used to convert these environments into tile loads are outlined. Testing which was performed to quantify or verify the loads are discussed, along with the load combination rationale which was used. The discussion of the ascent environment is limited to the transonic/supersonic portion of the mission since mechanical design loads occur during this time, and to specific regions of the vehicle, in particular those regions in which undensified critical (black) tiles are located.
    Keywords: NONMETALLIC MATERIALS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., No. 52. Part 2; p 111-125
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  • 5
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    Structural characteristics of the shuttle orbiter ceramic thermal protection system (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The thermal protection system (TPS) of the Space Shuttle Orbiter is described as well as the results of dynamic reponse studies conducted in support of the efforts to certify the TPS for flight. The ceramic Thermal Protection System consists of ceramic tiles bonded to felt pads which are in turn bonded to the Orbiter substructure to protect the aluminum substructure from the heat of reentry.
    Keywords: NONMETALLIC MATERIALS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., No. 52. Part 2; p 101-110
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  • 6
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    Fibrous ceramic insulation (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: Some of the reusable heat shielding materials used to protect the Space Shuttles, their manufacturing processes, properties, and applications are discussed. Emphases is upon ceramic materials. Space Shuttle Orbiter tiles are discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Advan. Mater. Technol.; p 261-274
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  • 7
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    Polymer research at NASA Langley Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: Polymer synthesis programs involve the development of Novel thermoplastics, pseudothermoplastics, and thermosets. These systems are prepared to elucidate structure-property relationships involving thermal capabilities, toughness, processability and environmental stability. Easily processable polyimides, solvent-resistant polysulfones and polyphenylquinoxalines, and tougher high and intermediate temperature polymers were developed. Characterization efforts included high pressure liquid chromatography methodology, the development of toughness tests for fiber reinforced composites, a study of electrical properties of metal ion filled polyimides, and a study of the mutagenicity of aromatic diamines. Also the mechanism of cure/degradation of experimental polymers was studied by rheology, mechanical behavior, separation techniques and spectroscopy. The degradative crosslinking of alkyl-containing polyimides, the separation and identification of crosslinked phenylquinoxalines, the rheological behavior of hot-melt polyimides, and the elucidation of the cure of norbornene endcapped imides were also studied.
    Keywords: NONMETALLIC MATERIALS
    Type: Advan. Mater. Technol.; p 29-48
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  • 8
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    Polymer materials research at NASA Ames Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: Polymers that provide significant improvements in both efficiency and safety for civilian transport aircraft and military combat aircraft were developed. High strength to weight structures such as carbon fiber composites with long term durability are requirements common to both classes of aircraft. Aircraft safety improvements in fire resistance and crashworthiness of primary and secondary structures are long term objectives for transport aircraft. Void filler ballistic foams, intumescent coatings, and radiation-resistant transparent plastics contribute to vulnerability reduction in combat military aircraft. Low and high velocity impact tolerance, fire resistance, thermal stability, and long term durability of polymers and components are emphasized.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Advan. Mater. Technol.; p 49-64
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  • 9
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    Corrosion properties of second-generation conductive materials (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Since the introduction of silver-filled epoxy adhesives and silver-filled nitrocellulose lacquer as RFI control materials, a number of new materials have been introduced. The resin carriers have been changed in an effort to make the materials more usable or more EPA acceptable and the fillers have been varied in an effort to make the materials less costly. The corrosion-related properties of second-generation materials were assessed, including adhesives, caulks, and greases. Aluminum 2024 was used as the only substrate material. Ten days of salt fog was used as the corrosive environment. If a noble material such as silver, nickel, or carbon is sandwiched with aluminum an increase in dc resistance results given enough time. If this is unsatisfactory electrically it should either not be used or have all corrosive environments excluded.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 7 p
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  • 10
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    Synthesis of aminosilane and aromatic diamine intermediates for polymerization (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The preparation of monomers for use in a study to improve properties of epoxy polymers and silicone elastomers is described. Various approaches to the solution of the synthesis of aminosilane and diamine curing agents were examined. Ortho-, meta-, and para-substituted diamines where X is CH2, C(CH3)2, O, S, NH, or SO2 and n = 0, 1, 2, and 3 were investigated.
    Keywords: NONMETALLIC MATERIALS
    Type: The 1981 NASA(ASEE Summer Fac. Fellowship Program; 9 p
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  • 11
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    Development of high strength, high temperature ceramics (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Improvement in the high-pressure turbopumps, both fuel and oxidizer, in the Space Shuttle main engine were considered. The operation of these pumps is limited by temperature restrictions of the metallic components used in these pumps. Ceramic materials that retain strength at high temperatures and appear to be promising candidates for use as turbine blades and impellers are discussed. These high strength materials are sensitive to many related processing parameters such as impurities, sintering aids, reaction aids, particle size, processing temperature, and post thermal treatment. The specific objectives of the study were to: (1) identify and define the processing parameters that affect the properties of Si3N4 ceramic materials, (2) design and assembly equipment required for processing high strength ceramics, (3) design and assemble test apparatus for evaluating the high temperature properties of Si3N4, and (4) conduct a research program of manufacturing and evaluating Si3N4 materials as applicable to rocket engine applications.
    Keywords: NONMETALLIC MATERIALS
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 11 p
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  • 12
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    Development of toughened epoxy polymers for high performance composite and ablative applications (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A survey of current procedures for the assessment of state of cure in epoxy polymers and for the evaluation of polymer toughness as related to nature of the crosslinking agent was made to facilitate a cause-effect study of the chemical modification of epoxy polymers. Various conformations of sample morphology were examined to identify testing variables and to establish optimum conditions for the selected physical test methods. Dynamic viscoelasticity testing was examined in conjunction with chemical analyses to allow observation of the extent of the curing reaction with size of the crosslinking agent the primary variable. Specifically the aims of the project were twofold: (1) to consider the experimental variables associated with development of "extent of cure" analysis, and (2) to assess methodology of fracture energy determination and to prescribe a meaningful and reproducible procedure. The following is separated into two categories for ease of presentation.
    Keywords: NONMETALLIC MATERIALS
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 17 p
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  • 13
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    Effects of solar radiation on glasses (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The effects of solar radiation and space environment on glasses in space flight by exposing glass specimens to the space environment was determined. The occurrence of optical, mechanical, and chemical property changes was analyzed. The property changes of samples receiving differing cumulative solar radiation exposure are compared.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 170-172
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  • 14
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    Ion-beam-textured and coated surfaces experiment (S1003) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objective of this LDEF experiment is to measure the effects of exposure to the shuttle launch and near Earth space environments on the optical properties of ion beam textured high absorptance solar thermal control surfaces, the optical and electrical properties of ion beam sputtered conductive solar thermal control surfaces, and the weight loss of ion beam deposited oxide polymer films. The various types of surfaces to be tested include six major categories: (1) ion beam textured surfaces suitable for space solar thermal (solar concentration) application; (2) painted and/or state of the art solar thermal surfaces; (3) ion beam sputtered conductive coatings for thermal and space charge control (e.g., indium-oxide coated metalized FEP Teflon); (4) ion beam sputtered conductive coated solar sail materials for space charge control and cooling through emittance; (5) micrometeoroid sensitive samples whose optical properties change only as a result of micrometeoroid impact; and (6) Kapton coated with oxide polymer films to minimize oxygen degradation at near Earth orbit altitudes.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 62-65
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  • 15
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    Thermal control surface experiment (S0069) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objectives of this LDEF experiment are to determine the effects of the near Earth orbital environment and the Shuttle induced environment in spacecraft thermal control surfaces. Spectral reflectance measurements will be obtained and used to differentiate between different solid state damage mechanisms of environmental damage to separate the effects of contamination from those of natural environment damage, and for comparison and correlation with laboratory test data.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 57-61
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  • 16
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    Exposure of spacecraft coatings (S0010) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objectives of this LDEF experiment are to determine the effects of both the Shuttle-induced environment and the space radiation environment on selected sets of spacecraft thermal control coatings. The experimental approach is to passively expose samples of thermal control coatings to Shuttle-induced and space radiation environments and to return the samples for postflight evaluation and comparison with preflight measurements to determine the effects of the environmental exposure. Optical measurements of the samples will include total normal emittance and spectral reflectance. The experiment will utilize a 6 in. deep peripheral tray and an experiment exposure control canister (EECC). The EECC will provide protection for some of the samples against exposure to the launch and reentry environments. The EECC will be programmed to open about 2 weeks after LDEF deployment and close pior to LDEF retrieval by the Shuttle and reentry. Some samples will not be housed in the EECC and will be exposed to the Shuttle-induced environment during launch and reentry. Comparison of the data from these samples with data from samples in the EECC will yield information about possible contamination induced degradation effects.
    Keywords: NONMETALLIC MATERIALS
    Type: Long Duration Exposure Facility (LDEF); p 54-56
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  • 17
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    Balloon materials degradation (S1006) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objective of this experiment is to assess the effects of long-term exposure of candidate balloon films, tapes, and lines to the hostile environment above the Earth's atmosphere. Degradation of mechanical and radiometric properties will be observed by a series of tests on exposed materials. The experiment is passive and will test candidate balloon films, tapes, and lines. The experiment will occupy one-third of a 3-in.-deep peripheral tray. Two additional identical sets of material will be prepared. The first set will be tested immediately and the second will be held in a controlled environment until the recovery of the samples placed on orbit. Tests will then be performed on this second set to determine any effects of aging. The specimens that are recovered from the Long Duration Exposure Facility will also be tested and the effects of long-duration exposure noted. In addition to these specimens, another set of specimens will be exposed at an accelerated exposure facility and the results will be compared with those of specimens exposed in situ.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 49-51
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  • 18
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    Polymer matrix composites research at NASA Lewis Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: The in situ polymerization of monomer reactants (PMR) approach was demonstrated to be a powerful approach for solving many of the processing difficulties associated with the use of high temperature resistant polymers as matrix resins in high performance composites. The PMR-15 polyimide provides the best overall balance of processing characteristics and elevated temperature properties. The excellent properties and commercial availability of composite materials based on PMR-15 led to their acceptance as viable engineering materials. The PMR-15 composites are used to produce a variety of high quality structural components.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Advan. Mater. Technol.; p 65-90
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  • 19
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    Corrosion protection coating (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Technol. Appl. Team; p 40
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  • 20
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    Crystallization of fluorozirconate glasses (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The crystallization of a number of glasses of the fluorozirconate family has been studied (using powder X-ray diffraction and DSC) as a function of time and temperature of heating. The main crystalline phases were beta BaZrF6 and beta BaZr2F10. Stable and metastble transformations to the low-temperature alpha phases were also investigated. The size of crystallites in fully devitrified glasses was calculated (from line broadening of the X-ray diffraction peaks) to be about 60 nm.
    Keywords: NONMETALLIC MATERIALS
    Type: Materials Research Bulletin (ISSN 0025-5408); 19; 5, 19; 577-590
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  • 21
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    Ion beam deposition of amorphous carbon films with diamond like properties (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Carbon films were deposited on silicon, quartz, and potassium bromide substrates from an ion beam. Growth rates were approximately 0.3 micron/hour. The films were featureless and amorphous and contained only carbon and hydrogen in significant amounts. The density and carbon/hydrogen ratio indicate the film is a hydrogen deficient polymer. One possible structure, consistent with the data, is a random network of methylene linkages and tetrahedrally coordinated carbon atoms.
    Keywords: NONMETALLIC MATERIALS
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  • 22
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    Siloxane containing addition polyimides (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Addition polyimide oligomers have been synthesized from bis(gamma-aminopropyl) tetramethyldisiloxane and 3, 3', 4, 4'-benzophenonetetracarboxylic dianhydride using a variety of latent crosslinking groups as endcappers. The prepolymers were isolated and characterized for solubility (in amide, chlorinated and ether solvents), melt flow and cure properties. The most promising systems, maleimide and acetylene terminated prepolymers, were selected for detailed study. Graphite cloth reinforced composites were prepared and properties compared with those of graphite/Kerimid 601, a commercially available bismaleimide. Mixtures of the maleimide terminated system with Kerimid 601, in varying proportions, were also studied.
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Quarterly (ISSN 0036-0821); 15; 24-30
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  • 23
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    Thermoplastic composite matrices with improved solvent resistance (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: In order to improve solvent resistance of aromatic thermoplastic polymers, ethynyl-terminated aromatic sulfone polymers (ETS), sulfone/ester polymers (SEPE) containing pendent ethynyl groups, and phenoxy resin containing pendent ethynyl groups are synthesized. Cured polysulfones and phenoxy resins containing ethynyl groups on the ends or pendent on the molecules exhibited systematic behavior in solvent resistance, film flexibility, and toughness as a function of crosslink density. The film and composite properties of a cured solvent-resistant ETS were better than those of a commercially available solvent sensitive polysulfone. The study was part of a NASA program to better understand the trade-offs between solvent resistance, processability and mechanical properties which may be useful in designing composite structures for aerospace vehicles.
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Journal (ISSN 0091-1062); 20; 18-23
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  • 24
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    Polyimides formulated from a partially fluorinated diamine for aerospace tribological applications (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Preliminary pribological studies on polyimides formulated from the diamine 2,2-bis 4-(4-aminophenoxy)phenyl hexafluoropane (4-BDAF) indicate that polyimides formulated from this diamine have excellent potential for high temperature tribological applications. The dianhydrides used to make the polyimides were pyromellitic (PMDA) and benzophenonetetracarboxylic acid (BTDA). Friction and wear studies at 25 and 200 C indicate that polyimides formulated using 50 mole percent of the PMDA dianhydride and 50 mole percent of the BTDA dianhydride perform better than polyimides formulated solely with the BTDA dianhydride. Graphite fiber reinforced polyimide composites were formulated with the polyimide made from the BTDA dianhydride and both graphitic and non-graphitic fibers were evaluated. Graphitic fibers produced better tribological results, since thin, flowing, 'layer-like' transfer films were produced which did not build up with long sliding durations. Non-graphitic fibers did not produce this type of transfer. Previously announced in STAR as N83-22423
    Keywords: NONMETALLIC MATERIALS
    Type: ASLE Transactions; 27; 189-196
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  • 25
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    Ceramic-coated metals can survive contact with hot working fluid (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Thermal barrier coatings (TBCs) have been developed as a means of protecting turbine blades and other engine hot section components whose surfaces are exposed to the most extreme operating conditions. By adding a thin, insulating ceramic oxide layer to an air-cooled turbine blade, the difference between the gas temperature and the metal temperature is further increased as a function of ceramic coating thickness, heat flux, and oxide thermal conductivity. An 0.04-cm thick ceramic layer can typically yield a 100-300 C temperature drop. Of the various techniques available for the deposition of thermal barrier coatings, the most common is that of plasma spraying. Significant improvements have been made in TBC durability through the use of bond coat compositions with increased oxidation resistance.
    Keywords: NONMETALLIC MATERIALS
    Type: Research and Development (ISSN 0160-4074); 26; 122-125
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  • 26
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    New phosphorus-containing bisimide resins (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Phosphorus-based flame retardants have been effectively used in a wide variety of polymeric materials. Such additives, however, may either influence the decomposition reaction in polymers or lack durability due to a tendency to be leached out by solvents. Attention is given to the synthesis, characterization, thermal stability and degradation mechanisms of bisimide resins, and an evaluation is conducted of the flammability and mechanical properties of graphite cloth-reinforced laminates fabricated from one of the six phosphorus-containing bisimide resins considered.
    Keywords: NONMETALLIC MATERIALS
    Type: IN: Contemporary topics in polymer science. Volume 4. New York; 115-139
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  • 27
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    Large-area silicon sheet technology status in United States' Department of Energy photovoltaics programs (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Solar Energy (ISSN 0142-5919); 2; 171-187
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  • 28
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    Life modeling of atmospheric and low pressure plasma-sprayed thermal-barrier coating (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The cycles-to-failure vs cycle duration data for three different thermal barrier coating systems, which consist of atmospheric pressure plasma-sprayed ZrO2-8 percent Y2O3 over similarly deposited or low pressure plasma sprayed Ni-base alloys, are presently analyzed by means of the Miller (1980) oxidation-based life model. Specimens were tested at 1100 C for heating cycle lengths of 1, 6, and 20 h, yielding results supporting the model's value.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 5; 470-478
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  • 29
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    Mechanical property measurements of plasma-sprayed thermal-barrier coatings subjected to oxidation (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Techniques have been developed for measuring the tensile properties of plasma-sprayed coatings which are used in thermal barrier applications. The measurements have included the average Young's modulus, bond strength and elongation at failure. The oxidation behavior of the bond coat plays an important role in the integrity and adhesion of plasma-sprayed thermal barrier coatings. This work studies the nature of the high temperature degradation on the mechanical properties of the coating. Furnace tests have been carried out on U-700 alloy with bond coats of NiCrAlY or NiCrAlZr and an overlay of ZrO2-8 percent Y2O3. Weight gain measurements on the coatings have been examined with relation to the adhesion strength and failure observations. The results from an initial study are reported in this work.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 5; 479-490
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  • 30
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    Ethynyl-terminated polyarylates - Synthesis and characterization (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Hydroxy-terminated polyarylates (HTPA) with number-average molecular weights of approximately 2500, 5000, 7500, and 10,000 were synthesized and converted to corresponding 4-ethynylbenzoyloxy-terminated polyarylates (ETPA) by reaction with 4-ethynylbenzoyl chloride. The terminal ethynyl groups were thermally reacted to provide chain extension and crosslinking. The cured ETPA exhibited higher glass transition temperatures (Tg) and better solvent resistance than a high molecular weight linear polyarylate. Solvent resistance was further improved by curing 2,2-bis(4-ethynylbenzoyloxy-4-prime-phenyl) propane, a coreactant, with ETPA at concentrations of approximately 10 percent (w/w).
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Polymer Science: Polymer Chemistry Edition (ISSN 0360-6376); 22; 3011-302
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  • 31
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    The development of aerospace polyimide adhesives (1984)
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    Publication Date: 2011-08-19
    Description: Few materials are available which can be used as aerospace adhesives at temperatures in the range of 300 C. The Materials Division at NASA-Langley Research Center developed several high temperature polyimide adhesives to fulfill the stringent needs of current aerospace programs. These adhesives are the result of a decade of basic research studies on the structure property relationships of both linear and addition aromatic polyimides. The development of both in house and commercially available polyimides is reviewed with regards to their potential for use as aerospace adhesives.
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  • 32
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    Polyimides - Tribological properties and their use as lubricants (1984)
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    Publication Date: 2011-08-19
    Description: Friction, wear, and wear mechanisms of several different polyimide films, solid bodies, composites, and bonded solid lubricant films are compared and discussed. In addition, the effect of such parameters as temperatures, type of atmosphere, contact stress, and specimen configuration are investigated. A friction and wear transition occurs in some polyimides at elevated temperatures and this transition is related to molecular relaxations that occur in polyimides. Friction and wear data from an accelerated test (pin-on-disk) are compared to similar data from an end use test device (plain spherical bearing), and to other polymers investigated in a similar geometry.
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  • 33
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    Polyimide characterization studies - Effect of pendant alkyl groups (1984)
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    Publication Date: 2011-08-19
    Description: The effect on selected polyimide properties when pendant alkyl groups were attached to the polymer backbone was investigated. A series of polymers were prepared using benzophenone tetracarboxylic acid dianhydride (BTDA) and seven different p-alkyl-m,p'-diaminobenzophenone monomers. The alkyl groups varied in length from C(1) (methyl) to C(9) (nonyl). The polyimide prepared from BTDA and m,p'-diaminobenzophenone was included as a control. All polymers were characterized by various chromatographic, spectroscopic, thermal, and mechanical techniques. Increasing the length of the pendant alkyl group resulted in a systematic decrease in glass transition temperature (Tg) for vacuum cured films. A 70 C decrease in Tg to 193 C was observed for the nonyl polymer compared to the Tg for the control. A corresponding systematic increase in Tg indicative of crosslinking, was observed for air cured films. Thermogravimetric analysis revealed a slight sacrifice in thermal stability with increasing alkyl length. No improvement in film toughness was observed.
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  • 34
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    Rheological characterization of addition polyimide matrix resins and prepregs (1984)
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    Publication Date: 2011-08-19
    Description: Although graphite-reinforced polyimide matrix composites offer outstanding specific strength and stiffness, together with high thermal oxidative stability, processing problems connected with their rheological behavior remain to be addressed. The present rheological studies on neat polyimide resin systems encountered outgassing during cure. A staging technique has been developed which can successfully handle polyimide samples, and novel methods were applied to generate rheological curves for graphite-reinforced prepregs. The commercial graphite/polyimide systems studied were PRM 15, LARC 160, and V378A.
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  • 35
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    A thermoplastic polyimidesulfone (1984)
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    Publication Date: 2011-08-19
    Description: A polymer system has been prepared which has the excellent thermoplastic properties generally associated with polysulfones, and the solvent resistance and thermal stability of aromatic polyimides. This material, with improved processability over the base polyimide, can be processed in the 260-325 C range in such a manner as to yield high quality, tough unfilled moldings; strong, high-temperature-resistant adhesive bonds; and well consolidated, graphite-fiber-reinforced moldings (composites). The unfilled moldings have physical properties that are similar to aromatic polysulfones which demonstrates the potential as an engineering thermoplastic. The adhesive bonds exhibit excellent retention of initial strength levels even after thermal aging for 5000 hours at 232 C. The graphite-fiber-reinforced moldings have mechanical properties which makes this polymer attractive for the fabrication of structural composites.
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  • 36
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    Spherical microglass particle impingement studies of thermoplastic materials at normal incidence (1984)
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    Publication Date: 2011-08-19
    Description: Light optical and scanning electron microscope studies were conducted to characterize the erosion resistance of polymethyl methacrylate (PMMA), polycarbonate (PC), polytetrafluoroethylene (PTFE) and ultra-high-molecular-weight-polyethylene (UHMWPE). Erosion was caused by a jet of spherical micro-glass beads at normal impact. During the initial stages of damage, the surfaces of these materials were studied using a profilometer. Material buildup above the original surface was observed on PC and PMMA. As erosion progressed, this buildup disappeared as the pit became deeper. Little or no buildup was observed on PTFE and on UHMWPE. UHMWPE and PTFE are the most resistant materials and PMMA the least. Favorable properties for high erosion resistance seem to be high values of ultimate elongation, and strain energy and a low value of the modulus of elasticity. Erosion-rate-versus-time curves of PC and PTFE exhibit incubation, acceleration and steady state periods. A continuously increasing erosion rate period was observed however for PMMA instead of a steady state period. At early stages of damage and at low impact pressure material removal mechanisms appear to be similar to those for metallic materials.
    Keywords: NONMETALLIC MATERIALS
    Type: ASLE Transactions; 27; 373-379
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  • 37
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    Thermogravimetric analysis of silicon carbide-silicon nitride polycarbosilazane precursor during pyrolysis from ambient to 1000 C (1984)
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    Publication Date: 2011-08-19
    Description: Thermogravimetric analysis data are presented on the unmeltable polycarbosilazane precursor of silicon carbide-silicon nitride fibers, over the room temperature-1000 C range in a nitrogen atmosphere, in order to establish the weight loss at various temperatures during the precursor's pyrolysis to the fiber material. The fibers obtained by this method are excellent candidates for use in applications where the oxidation of carbon fibers (above 400 C) renders them unsuitable.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Materials Science Letters (ISSN 0261-8028); 3; 802-804
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  • 38
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    Dynamic and static fatigue of a machinable glass ceramic (1984)
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    Publication Date: 2011-08-19
    Description: The dynamic and static fatigue behavior of a machinable glass ceramic was investigated to assess its susceptibility to stress corrosion-induced delayed failure. Fracture mechanics techniques were used to analyze the results so that lifetime predictions for components of this material could be made. The resistance to subcritical crack growth of this material was concluded to be only moderate and was found to be dependent on the size of its microstructure.
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  • 39
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    Friction and wear of ceramics (1984)
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    Publication Date: 2011-08-19
    Description: The adhesion, friction, wear and lubricated behaviors of both oxide and non-oxide ceramics are reviewed. Ceramics are examined in contact with themselves, other harder materials and metals. Elastic, plastic and fracture behavior of ceramics in solid state contact is discussed. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as with metals. Grit size effects in two- and three-body abrasive wear are observed for ceramics. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Surface contaminants affect friction and adhesive wear. For example, carbon on silicon carbide and chlorine on aluminum oxide reduce friction while oxygen on metal surfaces in contact with ceramics increases friction. Lubrication increases the critical load necessary to initiate fracture of ceramics both in indentation and with sliding or rubbing.
    Keywords: NONMETALLIC MATERIALS
    Type: Wear (ISSN 0043-1648); 100; 333-353
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  • 40
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    Synthesis and characterization of a melt processable polyimide (1984)
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    Publication Date: 2011-08-19
    Description: A melt processable polyimide which contains sulfur and oxygen bridges between the aromatic rings (BDSDA/APB) was synthesized and characterized. Its physical, mechanical, thermal and flow properties were determined as was its resistance to some of the more commonly used solvents. The melt flow properties were measured for the temperature range 250 C - 350 C and under the conditions (stress/strain) encountered in commercial processes.
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  • 41
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    Effects of intermediate-energy electrons on mechanical and molecular properties of a polyetherimide (1984)
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    Publication Date: 2011-08-19
    Description: An experiment, using 100-keV electrons and 10 to the 9th -rad doses, was conducted on Ultem polyetherimide film. Mechanical, electron paramagnetic resonance, and infrared spectroscopic data suggested that the radiation produced crosslinking and embrittlement of the material.
    Keywords: NONMETALLIC MATERIALS
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-31; 1293-129
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  • 42
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    Performance of thermal barrier coatings in high heat flux environments (1984)
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    Publication Date: 2011-08-19
    Description: Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8 percent Y2O3 specimens survived 3000 of the 0.5 sec cycles with falling. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 1 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12 percent Y2O3 or ZrO2-2O percent Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.
    Keywords: NONMETALLIC MATERIALS
    Type: Thin Solid Films (ISSN 0040-6090); 119; 195-202
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  • 43
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    Surface tension of ZrF4-BaF2-LaF3 glass (1984)
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    Publication Date: 2011-08-19
    Description: A solidified pendant drop technique is presently used in the measurement of surface tension of a 62 mol pct ZrF4, 33 mol pct BaF2, 5 mol pct LaF3 heavy metal-fluoride glass, in keeping with a requirement from a comparison experiment planned for microgravity conditions aboard the Space Shuttle. The surface tension at 550 C is 0.174 + or - 0.005 J/sq m.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society, Communications (ISSN 0002-7820); 67; C-197
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  • 44
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    Siloxane containing addition polyimides. II - Acetylene terminated polyimides (1984)
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    Publication Date: 2011-08-19
    Description: Acetylene terminated polyimide oligomers having a range of molecular weights have been synthesized by reacting bis (gamma-aminopropyl) tetramethyldisiloxane, aminophenylacetylene and 3, 3', 4, 4' benzophenonetetracarboxylic dianhydride in different molar ratios. The prepolymers were isolated and characterized for melt flow and cure properties. They show promise as adhesives for bonding titanium to titanium and as matrix resins for graphite cloth reinforced composites. The most promising system has been blended in varying proportions with Thermid 600, a commercially available acetylene terminated polyimide oligomer, and the mixtures have been tested for application as composite matrix resins.
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Quarterly (ISSN 0036-0821); 16; 6-12
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  • 45
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    Preparation and properties of silane-endcapped polyimide adhesives (1984)
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    Publication Date: 2011-08-19
    Description: Silane-endcapped polyimide high temperature adhesive formulations were prepared by reacting anhydride-terminated poly(amic acid), obtained from benzophenonetetracarboxylic dianhydride and a diamine (3,3'-, 3,4'- or 4,4'-diaminodiphenylmethane and 3,3', 3,4'- or 4,4'-diaminobenzophenone) with varying amounts of gama-aminopropyltriethoxysilane in dimethylacetamide. Resin properties were evaluated by torsional braid analysis and thermogravimetric analysis. Lap shear strengths of some of the adhesive bonds were determined at room temperature and at 177 C before and after ageing at 200 C for 2500 h and after boiling in water for 72 h.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Adhesion and Adhesives (ISSN 0143-7496); 4; 129-132
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  • 46
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    Demonstration of a silicon nitride attrition mill for production of fine pure Si and Si3N4 powders (1984)
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    Publication Date: 2011-08-19
    Description: To avoid metallic impurities normally introduced by milling ceramic powders in conventional steel hardware, an attrition mill (high-energy stirred ball mill) was constructed with the wearing parts (mill body, stirring arms, and media) made from silicon nitride. Commercial silicon and Si3N4 powders were milled to fine uniform particles with only minimal contamination - primarily from wear of the sintered Si3N4 media.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society Bulletin (ISSN 0002-7812); 63; 1176-117
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  • 47
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    Recycling used lubricating oil at the deep space stations (1981)
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    Publication Date: 2011-08-18
    Description: A comparison is made of the lubricating oil recycling methods used in the Deep Space Station 43 test and the basic requirements which could favor recycling of oil for continuous reuse. The basic conditions for successful recycling are compared to the conditions that exist in the Deep Space Network (DSN). This comparison shows that to recycle used oil in the DSN would not only be expensive but also nonproductive.
    Keywords: NONMETALLIC MATERIALS
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 239-246
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  • 48
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    Morphological and frictional behavior of sputtered MoS2 films (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-22387)
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  • 49
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    Phase stability in plasma-sprayed, partially stabilized zirconia-yttria (1981)
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    Publication Date: 2011-08-18
    Keywords: NONMETALLIC MATERIALS
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  • 50
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    Novel improved PMR polyimides (1981)
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    Publication Date: 2011-08-18
    Description: The development of a class of high-temperature-resistant resins known as PMR polyimides has been reported by Serafini et al. (1972). Serafini and Vannucci (1975) found that the lower formulated molecular weight (FMW) compositions exhibited increased resin flow, but with some sacrifice in elevated temperature thermo-oxidative stability. Vannucci (1977) reported that the resin flow characteristics of the PMR composition having an FMW of 1500 could be varied by controlling the degree of resin advancement or imidization. The current investigation is concerned with an alternative approach to obtain improved flow PMR polyimides without sacrificing the desirable thermo-oxidative characteristics. The new approach is based on the utilization of a chemically compatible flow modifying agent. This agent is N-phenylnadimide (PN). The determination of the processing characteristics and properties of PN modified PMR/Celion 6000 composites is discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Journal; 17; Nov
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  • 51
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    Behavior of bubbles in glassmelts. III - Dissolution and growth of a rising bubble containing a single gas (1981)
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    Publication Date: 2011-08-18
    Description: Finite difference solutions of the mass transport equations governing the dissolution (growth) of a rising gas bubble, containing a single gas, in a glassmelt were obtained. These solutions were compared with those obtained from an approximate procedure for a range of the controlling parameters. Applications were made to describe various aspects of O2 and CO2 gas-bubble behavior in a soda-lime-silicate melt.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 64
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  • 52
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    The generation and morphology of single-crystal silicon carbide wear particles under adhesive conditions (1981)
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    Publication Date: 2011-08-18
    Description: Sliding friction experiments were performed in vacuum at room temperature on a plane-type SiC surface in contact with iron-based binary alloys. Multiangular and spherical wear particles were found to form as a result of multipass sliding. The multiangular particles were produced by primary and secondary cracking of the 0001, 10(-)10, and 11(-)20 plane-type cleavage planes under the Hertzian stress field or local inelastic deformation zone. When alloy surfaces are in contact with silicon carbide under a load of 0.2 N, the alloy around the contact area is subjected to stresses that are close to the elastic limit in the elastic deformation region and/or exceed it. It was also found that spherical wear particles may be produced by two mechanisms: a penny-shaped fracture along the circular stress trajectories under the local inelastic deformation zone, and the attrition and fatigue of wear particles.
    Keywords: NONMETALLIC MATERIALS
    Type: Wear; 67; Apr. 1
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  • 53
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    Effect of CeO2, MgO and Y2O3 additions on the sinterability of a milled Si3N4 with 14.5 wt% SiO2 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The sinterability of alpha Si3N4 with 0-5.07 equivalent per cent of CeO2, MgO, or Y2O3 has been studied in the temperature range 1650-1820 C by density measurements and X-ray diffraction analysis. Maximum densities were obtained in the range 1765-1820 C and were 99.6% of theoretical with 2.5% CeO2; 98.5% of theoretical with 1.24 to 1.87% MgO, and 99.2% of theoretical with 2.5% Y2O3. Densities 94% or more of theoretical value were obtained with as little as 0.62 equivalent per cent additive.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Materials Science; 16; Mar. 198
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  • 54
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    Physical aging of linear and network epoxy resins (1981)
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    Publication Date: 2011-08-18
    Description: Network and linear epoxy resins principally based on the diglycidyl ether of bisphenol-A and its oligomers are prepared and studied using diamine and anhydride crosslinking agents. Rubber modified epoxies and a carbon fiber reinforced composite are also investigated. All materials display time-dependent changes when stored at temperatures below the glass transition temperature after quenching (sub-T/g/ annealing). Solvent sorption experiments initiated after different sub-T(g) annealing times demonstrate that the rate of solvent uptake can be indirectly related to the free volume of the epoxy resins. Residual thermal stresses and water are found to have little effect on the physical aging process, which affects the sub-T(g) properties of uniaxial carbon fiber reinforced epoxy material. Finally, the importance of the recovery phenomenon which affects the durability of epoxy glasses is considered.
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  • 55
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    An overview of the nonequilibrium behavior of polymer glasses (1981)
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    Publication Date: 2011-08-18
    Description: It is pointed out that research efforts are at present being directed in two areas, one comprising experimental studies of this phenomenon in various glassy polymer systems and the other involving the development of a quantitative theory capable of satisfactorily predicting aging behavior for a variety of polymer materials under different conditions. Recent work in both these areas is surveyed. The basic principles of nonequilibrium behavior are outlined, with emphasis placed on changes in material properties with annealing below the glass transition temperature. Free volume theory and thermodynamic theory are discussed.
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  • 56
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    Effect of gamma irradiation on the friction and wear of ultrahigh molecular weight polyethylene (1981)
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    Publication Date: 2011-08-18
    Description: The effect of sterilization gamma irradiation on the friction and wear properties of ultrahigh molecular weight polyethylene (UHMWPE) sliding against stainless steel 316L in dry air at 23 C is investigated, the results to be used in the development of artificial joints which are to surgically replace diseased human joints. A pin-on-disk sliding friction apparatus is used, a constant sliding speed in the range 0.061-0.27 m/s is maintained, a normal load of 1 kgf is applied with dead weight, and the irradiation dose levels are: 0, 2.5, and 5.0 Mrad. Wear and friction data and conditions for each of the ten tests are summarized, and include: (1) wear volume as a function of the sliding distance for the irradiation levels, (2) incremental wear rate, and (3) coefficient of friction as a function of the sliding distance. It is shown that (1) the friction and wear properties of UHMWPE are not significantly changed by the irradiation doses of 2.5 and 5.0 Mrad, (2) the irradiation increases the amount of insoluble gel as well as the amount of low molecular weight material, and (3) after run-in the wear rate is either steady or gradually decreases as a function of the sliding distance.
    Keywords: NONMETALLIC MATERIALS
    Type: Wear; 70; July 15
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  • 57
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    Sinterability, strength and oxidation of alpha silicon carbide powders (1984)
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    Publication Date: 2011-08-18
    Description: An investigation is made of pressureless sintering of commercially available alpha-SiC powders at temperatures between 1900 and 2150 C for periods of 10 to 240 min under one atmosphere of argon pressure. It is found that alpha-SiC powder containing boron and carbon sintering aids is sinterable at 2150 C for a period of 30 min to a high final density (greater than 96 percent of theoretical). In alpha-SiC powder containing aluminum and carbon sintering aids, the final density achieved is only about 80 percent of theoretical. Determinations are made of room temperature and high temperature (1370 C) flexure strength and oxidation resistance on sintered high density (more than 96 percent of theoretical) alpha-SiC (boron, carbon) material. It is found that both the strength and the resistance to oxidation are equivalent and comparable to those of the sintered alpha-SiC which represents the state of the art.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Materials Science (ISSN 0022-2461); 19; 1307-131
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  • 58
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    Performance of laser-glazed zirconia thermal barrier coatings in cyclic oxidation and corrosion burner rig tests (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-22346)
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  • 59
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    Some properties of r.f.-sputtered hafnium nitride coatings (1982)
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-21331)
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  • 60
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    Sputtered silicon nitride coatings for wear protection (1982)
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-20314)
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  • 61
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    The combined effects of Fe and H2 on the nitridation of silicon (1982)
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    Publication Date: 2011-08-18
    Description: In view of the support offered by previous work for the suggestion that Fe may affect alpha-Si3N4 formation and microstructural development, a two-part study was conducted to differentiate the effects of H2 and Fe in, first, the nitridation of pure and of Fe-containing powder in N2 and N2-4% H2, and then the nitridation of (1 1 1) Si single crystal wafers with and without Fe powder on the surface. The degree of nitridation is most strongly affected by H2 at 1200 C, but by Fe at 1375 C, where Fe-containing samples in either atmosphere were almost completely nitrided. While neither H2 nor Fe alone changed the ratio of alpha-Si3N4 to beta-Si3N4, the combination of H2 and Fe increased it at both temperatures.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Materials Science Letters; 1; Aug. 198
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  • 62
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    Experimental studies of the vapor phase nucleation of refractory compounds. I - The condensation of SiO (1982)
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    Publication Date: 2011-08-18
    Description: The critical partial pressure of SiO necessary to initiate avalanche nucleation in the SiO-H2 system is measured as a function of the ambient temperature in the range 750-1000 K. Results show that the condensate produced at low temperatures is Si2O3, while a mixture of Si2O3 and amorphous SiO2 is produced at high temperatures. A surface energy of approximately 500 ergs/sq cm for the particles is found by analyzing the critical partial pressure vs temperature using classical nucleation theory. It is concluded that classical nucleation theory is not applicable to this system, because several inconsistencies in the thermodynamic analysis are demonstrated, and it is suggested that a kinetic theory of nucleation may be the preferential way to describe the condensation process.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Chemical Physics; 77; Sept. 1
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  • 63
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    Infrared spectroscopic analysis of the effects of simulated space radiation on a polyimide (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Infrared spectroscopic techniques have been used to study the effects of electron radiation on the polyimide PMDA-p,p-prime- ODA. The radiation exposures were made at various dose rates, for a total dose approximately equal to that for 30 years of exposure to electron radiation in geosynchronous earth orbit. At high dose rates the major effect was probably the formation of a polyisoimide or a charged quaternary amine, and at the low dose rates the effect was a reduction in the amount or aromatic ether linkage. In addition, the effects of dose rate for a small total dose were studied. Elevated temperatures occurred at high dose rates and were, in part, probably the cause of the radiation product. The data suggest that dose rates for accelerated simulations of the space environment should not exceed 100,000 rads/sec.
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  • 64
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    Adhesive and composite evaluation of acetylene-terminated phenylquinoxaline resins (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A series of acetylene-terminated phenylquinoxaline (ATPQ) oligomers of various molecular weights were prepared and subsequently chain extended by the thermally induced reaction of the ethynyl groups. The processability and thermal properties of these oligomers and their cured resins were compared with that of a relatively high molecular weight linear polyphenylquinoxaline (PPQ) with the same chemical backbone. The ATPQ oligomers exhibited significantly better processability than the linear PPQ but the PPQ displayed substantially better thermooxidative stability. Adhesive (Ti/Ti) and composite (graphite filament reinforcement) work was performed to evaluate the potential of these materials for structural applications. The PPQ exhibited better retention of adhesive and laminate properties than the ATPQ resins at 260 C after aging for 500 hr at 260 C in circulating air.
    Keywords: NONMETALLIC MATERIALS
    Type: Polymer Engineering and Science; 21; 16, N; Nov. 198
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  • 65
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    Compliance calibration of the short rod chevron-notch specimen for fracture toughness testing of brittle materials (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The short rod chevron-notch specimen has the advantages of (1) crack development at the chevron tip during the early stage of test loading, and (2) convenient calculation of plane-strain fracture toughness from the maximum test load and from a calibration factor which depends only on the specimen geometry and manner of loading. For generalized application, calibration of the specimen over a range of specimen proportions and chevron-notch configurations is necessary. Such was the objective of this investigation, wherein calibration of the short rod specimen was made by means of experimental compliance measurements converted into dimensionless stress intensity factor coefficients.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Fracture; 18; Feb. 198
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  • 66
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    Short-term stability of high-silica glasses (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The devitrification characteristics of high-silica (70-90%) glasses for use in potential higher temperature coatings on advanced insulation systems for space vehicles were determined at 1260 C after 24 h. These data indicate that additives can be used to maintain the stability of these coatings relative to cristobalite formation.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings; 2; July-Aug
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  • 67
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    Dynamics of solid dispersions in oil during the lubrication of point contacts. II - Molybdenum disulfide (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-20275)
    Keywords: NONMETALLIC MATERIALS
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  • 68
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    Test methodology for evaluation of fireworthy aircraft seat cushions (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Aircraft seat materials were evaluated in terms of their thermal performance. The materials were evaluated using (a) thermogravimetric analysis, (b) differential scanning calorimetry, (c) a modified NBS smoke chamber to determine the rate of mass loss and (d) the NASA T-3 apparatus to determine the thermal efficiency. In this paper, the modified NBS smoke chamber will be described in detail since it provided the most conclusive results. The NBS smoke chamber was modified to measure the weight loss of materials when exposed to a radiant heat source over the range of 2.5 to 7.5 W/cm sq. This chamber has been utilized to evaluate the thermal performance of various heat blocking layers utilized to protect the polyurethane cushioning foam used in aircraft seats. Various kinds of heat blocking layers were evaluated by monitoring the weight loss of miniature seat cushions when exposed to the radiant heat. The effectiveness of aluminized heat blocking systems was demonstrated when compared to conventional heat blocking layers such as neoprene. All heat blocking systems showed good fire protection capabilities when compared to the state-of-the-art, i.e., wool-nylon over polyurethane foam.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Fire and Flammability; 13; Jan. 198
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  • 69
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    The failure strengths of perfect diamond crystals (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Finite elasticity analysis is extended to the 110 direction, where off axis strain symmetry is not present, and the third order elastic data are obtained for diamond. The compressive yield strengths of perfect diamond crystals loaded in the 100, 110, and 111 directions are predicted to be 2.2, 5.6, and 2.8 Mbars, respectively, while the corresponding tensile fracture strengths are 1.0, 0.5, and 0.5 Mbars. From these results and from Hertz theory it is predicted that ring fracture of spherically tipped diamonds pressed against a flat will occur at pressures of 1.8-1.9 Mbars, substantially below the yield pressure (above 3 Mbars). Modification of the tip shape leads to a predicted increase in the pressure at which fracture occurs.
    Keywords: NONMETALLIC MATERIALS
    Type: Scripta Metallurgica; 15; May 1981
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  • 70
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    Microstructure and property characterization of sintered Si3N4, SiC, and SiAlON (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Commercially-produced, pressureless sintered Si3N4, SiC, and SiAlON were characterized with respect to density, phases present, bend strength, and oxidation resistance. The room-temperature bend strengths of sintered Si3N4, SiC, and SiAlON are comparable. However, the room-temperature strengths are much lower (approximately 40 to 50%) than the room-temperature strength of hot-pressed Si3N4 (NC-132). The strength loss in Si3N4 and SiAlON materials at high temperature was attributed to a viscous grain-boundary phase, retained during cooling from the sintering temperature. The oxidation resistance of sintered alpha-SiC was the best of any materials tested.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 65
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  • 71
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    A new brominated polymeric additive for flame retardant glass-filled polybutylene terephthalate (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Attention is called to the undesirable effects (poor ultraviolet light stability and blooming) sometimes introduced by brominated flame retarders. A brominated polymeric additive (BPA) with little or none of these undesirable side effects is compared with decabromobiphenyl oxide (DBBPO). The additive bears the product name F-2300. It is found to be more easily dispersed than DBBPO. The F-2300 is as effective as the DBBPO in the oxygen index test. The improved efficiency of the F-2300 may be explained by its better dispersion in polybutylene terephthalate (PBT). Glass-filled PBT containing F-2300 is found to be more resistant to UV degradation than DBBPO-containing formulas. Formulations with F-2300 therefore have a longer useful outdoor life. F-2300 is a diglycidyl-type polymer containing 50 percent aromatically bound bromine. Its melting point is 112 C, and it is stable up to 372 C. It is pointed out that since its melts at a relatively low temperature, it can be introduced into the formulation as a large agglomerate and still be dispersed evenly throughout the polymer.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Fire Retardant Chemistry; 9; Aug. 198
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  • 72
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    XPS, AES and friction studies of single-crystal silicon carbide (1982)
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    Publication Date: 2011-08-18
    Description: The surface chemistry and friction behavior of a single crystal silicon carbide surface parallel to the 0001 plane in sliding contact with iron at various temperatures to 1500 C in a vacuum of 3 x 10 nPa are investigated using X-ray photoelectron and Auger electron spectroscopy. Results show that graphite and carbide-type carbon are seen primarily on the silicon carbide surface in addition to silicon at temperatures to 800 C by both types of spectroscopy. The coefficients of friction for iron sliding against a silicon carbide surface parallel to the 0001 plane surface are found to be high at temperatures up to 800 C, with the silicon and carbide-type carbon at maximum intensity in the X-ray photoelectron spectroscopy at 800 C. The concentration of the graphite increases rapidly on the surface as the temperature is increased above 800 C, while the concentrations of the carbide-type carbon and silicon decrease rapidly and this presence of graphite is accompanied by a significant decrease in friction. Preheating the surfaces to 1500 C also gives dramatically lower coefficients of friction when reheating in the sliding temperature range of from room temperature to 1200 C, with this reduction in friction due to the graphite layer on the silicon carbide surface.
    Keywords: NONMETALLIC MATERIALS
    Type: Applications of Surface Science (ISSN 0378-5963); 10; 1982
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  • 73
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    Introduction to life modeling of thermal barrier coatings (1984)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Thermal barrier coatings may be applied to air-cooled turbine section airfoils to insulate such components from hot gases in the engine. The coatings, which typically consist of about 0.01 to 0.04 cm of zirconia-yttria ceramic over about 0.01 cm of NiCrAlY or NiCrAlZr alloy bond coat, allow increased gas temperatures or reduced cooling air flows. This, in turn, leads to marked improvements in engine efficiency and performance. However, certain risks are associated with designing for maximum benefits, and eventually a point is reached where coating loss would immediately jeopardize the underlying component. Therefore, designers must be able to accurately predict the life of a given bill-of-material coating in any particular design. The results of an in-house aeronautics, base research and technology program which is designed to provide the first steps towards developing mission-capable life-prediction models are outlined.
    Keywords: NONMETALLIC MATERIALS
    Type: Turbine Engine Hot Section Technology, 1984; 6 p
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  • 74
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    Preparation of large-particle-size monodisperse latexes in space: The STS-3, STS-4, and STS-7 mission results (1984)
    In:  Other Sources
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    Publication Date: 2016-06-07
    Description: Large-particle-size monodisperse latexes were prepared on four STS missions of the space shuttles Columbia and Challenger using flight hardware comprising four automated 100 cm(3) polymerization reactors. Seven polymerizations carried out on the March 1982 STS-3 mission of the Columbia, and the April 1983 STS-6 and June 1983 STS-7 missions of the Challenger, gave monodisperse latexes of 5 to 18 micron diameter with narrower particle size distributions than the corresponding ground-based control polymerizations. The rates of polymerization in microgravity were the same as on Earth. The results of these experiments are reviewed, and the prospects of the development of a space production process are discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: 2nd Symp. on Space Industrialization; p 75
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  • 75
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    Support of Oil Lubrication by Bonded Coatings (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: A new generation of lubricating lacquers for treatment of metal surfaces has been developed. These coatings have proved to be oil-compatible and are used in oil-lubricated systems. The oil lubrication is supported thereby through reduction of friction and increase of load-carrying capacity during boundary conditions. For difficult tribological systems, the problem-solving lubricating concept has proved to be the beneficial combination of lubricating oil and bonded coatings. A number of practical applications are presented.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's, vol. 2; p 709-721
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  • 76
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    Practical Applications and Uses of Solid Lubricant Films (1984)
    In:  CASI
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    Publication Date: 2014-09-11
    Description: Practical applications are illustrated with discussions covering the reasons for use of solid lubricants, required performance, lubricant selection, and results obtained for the various examples shown. The applications described cover a broad range of solid lubricants. Included are soft lamellar compounds, organic polymers, soft elemental metals, oxides and compounds for high temperature use. The illustrations selected cover a broad range of lubricant application techniques delineating the reasons for the different processing procedures which include bonded films, plasma spraying, sputtering, ion plating and electrodeposition.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's, vol. 2; p 681-702
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  • 77
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    Status and New Directions for Solid Lubricant Coatings and Composite Materials (1984)
    In:  CASI
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    Publication Date: 2014-09-11
    Description: At one time, solid lubricants were used almost entirely in aerospace applications. Today there is a pronounced trend to use them over a much broader range of applications. For example, self-lubricating polymer-based composites have displaced traditional oil-lubricated, metallic composites for many journal bearings and thrust washers in applications as diverse as earth-moving machinery and snow blowers to aircraft applications. For moderate temperatures below 200 C, glass filament-wound epoxy bearings with PTFE lubricating liners are usefl; for temperatures up to 350 C, graphite fiber reinforced polyimide bearing materials are finding applications. Advanced technology engines have severe lubrication and wear problems at temperatures beyond the capabilities of any of these lubricants. Here, self-lubricating ceramics and inorganic composites for use at 1000 C or higher are of interest. However, perhaps the most significant new direction for solid lubricant coatings and self-lubricating composites is their steadily increasing use in dry bearings for large volume, moderate temperature applications. This can be attributed to their simplicity of use (no supporting lubricant system needed), light weight, convenience, and general cost effectiveness.
    Keywords: NONMETALLIC MATERIALS
    Type: Tribology in the 80's, vol. 2; p 665-680
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  • 78
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    What's so Hot About Formulated Synthetics? (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: The development of synthetic automotive engine oil is discussed. The history of synthetic lubricants, and of the additives required to compete in a market which developed by and for petroleum oils. Some examples of real data, and enlarged using heat transfer properties obtained by chemical engineering thermodynamic methods are shown. The prospects for future successes and ideas on the additives that would most help to bring them about are also presented.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's. Vol. 1; p 477-488
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  • 79
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    Thermal and Oxidative Stabilities of Liquid Lubricants (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: The fundamental processes which occur during the thermal and oxidation degradation of hydrocarbons is reviewed. Various classes of liquid lubricants such as mineral oils, esters, polyphenyl ethers, C-ethers, and fluorinated polyethers are emphasized. Techniques to determine thermal and oxidative stabilities of lubricants are discussed. The role of inhibitors and catalysis is examined.
    Keywords: NONMETALLIC MATERIALS
    Type: Tribology in the 80's. Vol. 1; p 419-455
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  • 80
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    Behaviors of Polymer Additives Under EHL and Influences of Interactions Between Additives on Friction Modification (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: Polymer additives have become requisite for the formulation of multigrade engine oils. The behavior of polymethacrylate (PMA)-thickened oils as lubricants in concentrated contacts under nominal rolling and pure sliding conditions was investigated by conventional optical interferometry. The PMA thickened oils behaved differently from the base oil in the formation of elastohydrodynamic (EHL) films. The higher the elastohydrodynamic molecular weight of the PMA contained in the lubricant, the thinner was the oil film under EHL conditions. The film thickness of shear-degraded PMA-thickened oils was also investigated. The behavior of graphite particles dispersed in both the base oil and the PMA-thickened oil was studied under pure sliding by taking photomicrographs. Many kinds of additives are contained in lubricating oil and the interactions between additives are considered. The interactions of zinc-organodithiophosphates (ZDP) with other additives is discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's. Vol. 1; p 459-475
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  • 81
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    Status of New Direction of Liquid Lubricants (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: The status of liquid lubricants is discussed. Liquid lubricants which continue to be the predominant form of lubrication for machinery are discussed. Petroleum base lubricants comprise a very high percentage of the liquid lubricants in use today. There is a significant movement toward synthetic lubricants driven by crude oil problems coupled with improved additive response, and low temperature performance for the synthetics. Lubricant degradation mechanisms are included for guidance in the selection of lubricant and additive types.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's. Vol. 1; p 367-389
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  • 82
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    Structures and Properties of Polymers Important to Their Wear Behavior (1984)
    In:  CASI
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    Publication Date: 2014-09-11
    Description: The wear and transfer of various semicrystalline polymers sliding against smooth steel or glass surfaces were examined. The effects of structures, and properties of polymers on their wear behavior are discussed. It is found that the high wear characteristics of PTFE is due to the easy destruction of the banded structure of PTFE. The size of spherulites and the molecular profile are closely related to the magnitude of wear rates of typical semicrystalline polymers. The effects of these factors on the wear rate on the basis of the destruction or melting of spherulites at the frictional surface are discussed. Although the fatigue theory of wear indicates that some mechanical properties are important to wear behavior, it is shown that the theory does not always explain the experimental result obtained on a smooth surface.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's. Vol. 1; p 253-285
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  • 83
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    Future Direction of Research in Wear and Wear Resistant Materials. Status of Understanding (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: The adhesion of materials is one of the most popular interactions occuring between mating solid surfaces in contact, and was regarded as a key factor in wear process. However, because the adhesion is not a separation factor but a joining factor for mating materials, it is not easy to show a general plot of the formation process of wear particle through adhesion. A new idea on the mechanism of formation of wear particles in adhesive wear is shown. The wear particles are not separated from their mother surfaces directly as their final form, but minute adhered fragments are assembled and piled up to form a big particle which should be called as a wear particle after it is removed out of the rubbing system. From this proposed mechanism many other phenomena related to wear are interpreted.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's. Vol. 1; p 197-218
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  • 84
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    The Influence of Surface Topography on Polymer Friction (1984)
    In:  CASI
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    Publication Date: 2014-09-11
    Description: Current friction models for polymers are examined to determine their applicability in predicting the effects of roughness on friction. The two component, adhesion deformation model of friction predicts the variation of friction with the change in the sliding direction with respect to the lay direction on anisotropic rough surfaces. The two component model does not predict the change in friction with changes in roughness. A combination of an energy based model and a slip line deformation model may provide a friction model which could better represent measured friction.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Lewis Research Center Tribology in the 80's. Vol. 1; p 177-186
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  • 85
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    Importance and Definition of Materials in Tribology. Status of Understanding (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-10
    Description: In general, tribological systems consist of three basic components: the material surfaces in contact, the lubricant, and the environment. The materials in contact and the influence of both bulk and surface properties, indicating the importance of material characterization, on tribological behavior are addressed. Since metals and metallic alloys are the most widely used class of materials in practical devices, attention is focused principally on them. With respect to surface behavior, the effect of contaminants both from within the material and from the environment on adhesive behavior is addressed. The various surface events that alter adhesion, friction, and wear are discussed. These include surface reconstruction, segregation, chemisorption, and compound formation. Examples of these events are presented. Minor nuances in the structure of the outermost layers of solids have a pronounced effect on tribological properties. The importance of characterizing the materials of solids in contact in order to achieve a fundamental understanding of adhesion, friction, and wear and accordingly of methods for their control are addressed.
    Keywords: NONMETALLIC MATERIALS
    Type: Tribology in the 80's. Vol. 1; p 19-44
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  • 86
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    Charging and discharging characteristics of dielectric materials exposed to low- and mid-energy electrons (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Charging and discharging characteristics of dielectric samples exposed to 1-25 keV and 25-100 keV electrons in a laboratory environment are reported. The materials examined comprised OSR, Mylar, Kapton, perforated Kapton, and Alphaquartz, serving as models for materials employed on spacecraft in geosynchronous orbit. The tests were performed in a vacuum chamber with electron guns whose beams were rastered over the entire surface of the planar samples. The specimens were examined in low-impedance-grounded, high-impedance-grounded, and isolated configurations. The worst-case and average peak discharge currents were observed to be independent of the incident electron energy, the time-dependent changes in the worst case discharge peak current were independent of the energy, and predischarge surface potentials are negligibly dependent on incident monoenergetic electrons.
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  • 87
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    Mechanisms of photodegradation of ultraviolet stabilizers and stabilized polymers (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: NONMETALLIC MATERIALS
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  • 88
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    Dissolution of bulk specimens of silicon nitride (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An accurate chemical characterization of silicon nitride has become important in connection with current efforts to incorporate components of this material into advanced heat engines. However, there are problems concerning a chemical analysis of bulk silicon nitride. Current analytical methods require the pulverization of bulk specimens. A pulverization procedure making use of grinding media, on the other hand, will introduce contaminants. A description is given of a dissolution procedure which overcomes these difficulties. It has been found that up to at least 0.6 g solid pieces of various samples of hot pressed and reaction bonded silicon nitride can be decomposed in a mixture of 3 mL hydrofluoric acid and 1 mL nitric acid overnight at 150 C in a Parr bomb. High-purity silicon nitride is completely soluble in nitric acid after treatment in the bomb. Following decomposition, silicon and hydrofluoric acid are volatilized and insoluble fluorides are converted to a soluble form.
    Keywords: NONMETALLIC MATERIALS
    Type: Analytical Chemistry; June 198
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  • 89
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    Addition polyimide adhesives containing ATBN and silicone elastomers (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A study was conducted to determine the effects of added elastomers on the thermal stability, adhesive strength, and fracture toughness of LARC-13, a high-temperature addition polyimide adhesive. Various butadiene/acrylonitrile and silicon elastomers were incorporated into the polyimide resin either as physical polyblends, or by chemically reacting the elastomers with the polyimide backbone. Adhesive single lap-shear and T-peel strengths were measured before and after ageing at elevated temperature. A tapered double-cantilever beam specimen was used to determine the fracture toughness of the elastomer-modified polyimide adhesives.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Adhesion and Adhesives; 1; July 198
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  • 90
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    Long-time stress relaxation of a filled elastomer in vacuum environments (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Samples of a filled elastomeric ablative material were stored at 45 C and 10 to the -6th torr for 7 months. Their tensile stress-relaxation modulus at constant strain was measured throughout the 7 months. Results of the testing are discussed primarily by comparisons of the data to atmospheric-pressure moduli (determined in this work for shorter periods of time) and with moduli predicted from short-time testing. Confirmation of the strengthening effects of vacuum on this composite was obtained. The use of time-temperature superposition techniques as an approximate accelerated testing procedure for this material under these conditions was also verified.
    Keywords: NONMETALLIC MATERIALS
    Type: Polymer Engineering and Science; 21; 11, A; Aug. 198
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  • 91
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    Water vapor resistance of plasma-polymerized coatings on potassium bromide windows (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Plasma-polymerized tetrafluoroethylene (PPTFE) coated potassium bromide IR window are shown to possess better resistance to moisture than either ethylene or chlorotrifluoroethylene. The PPTFE-coated windows tolerated an upper limit relative humidity of about 80% at 297 K, without visible damage to either window or coating, over a period of 24 hours. Elemental analysis of the bulk, and photoelectron spectroscopy of the coating surface, showed that PPTFE coatings deposited downstream of the internal plasma reactor electrodes contained less atmospheric oxygen than coatings deposited between the electrodes; perhaps accounting for the improved moisture resistance.
    Keywords: NONMETALLIC MATERIALS
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  • 92
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    Laser processing (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Progress in the Progress ceramic materials is reported. Experiments and models for sintering and microstructure evolution are described. Models and data for understanding the kinetics of grain boundary motion and of pore coarsening and new materials for fuel cells and batteries; are developed. New experimental techniques using lasers for forming fine, monosized powders and for forming stable and metastable structures from liquids, and solar materials research are also developed. Colloidal science and ceramics processing are explored; and research programs on the presintering science necessary for controlled green microstructures are outlined.
    Keywords: NONMETALLIC MATERIALS
    Type: The Mater. Process. Res. Base of the Mater. Process. Center; p 198-209
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  • 93
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    Evaluation of waveguide coating materials (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Waveguide coating materials were tested at 8470 MHz for insertion loss. Samples of these coatings on waveguide pieces without flanges were tested in an environmental chamber to simulate the effects of high power microwave heating. Test results indicated that three types of coating materials are acceptable with regard to insertion loss. However, simulated microwave heating caused debonding of Metcot 7 and BD-991 coatings, resulting in peelings in the waveguide. The higher cost Chemglaze R104 does not exhibit this problem.
    Keywords: NONMETALLIC MATERIALS
    Type: The Telecommun. and Data Acquisition Rept.; p 68-71
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  • 94
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    Numerical modeling and optimization of polymer melt processing operations (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The application of finite element computer analyses to polymer flows of the type encountered in melt processing operations is described. A code capable of predicting values of fluid veleocity, pressure, shear stress, and temperature at any point within the flow field was developed. As such, is is of value in diagnosing such processing problems as regions of fluid stagnation at which thermal degradation may occur, or regions of excessive shear deformation which lead to thermomechanical damage. It is further able to generate predictions of the forces which must be applied to the melt to achieve the desired flow, and this information is of value in designing processing equipment of optimal efficiency and minimum energy consumption.
    Keywords: NONMETALLIC MATERIALS
    Type: The Mater. Process. Res. Base of the Mater. Process. Center; p 117-119
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  • 95
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    Rapid quenching effects in glassy polymers (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Using a specially constructed microbalance for hydrostatic weighing, density changes in PVC thin film due to rapid quenching through the glass transition temperature were observed. The more severe the quench, the greater the free volume content. Isobaric volume recovery of PVC was also studied by volume dilatometry. Both show aging of relaxing molecular rearrangements taking place as a linear function of logarithmic aging time at room temperature. Distribution of retardation times and Primak's distributed activation energy spectra were applied to the volume recovery data. The concomitant changes in mechanical properties of PVC after quenching were monitored by tensile creep stress-stran to failure rates. All reflect the presence of excess free volume content due to rapid quenching.
    Keywords: NONMETALLIC MATERIALS
    Type: The Mater. Process. Res. Base of the Mater. Process. Center; p 79-89
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  • 96
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    Detection of strength limiting defects in cellular glasses by dielectric measurements (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The foamed glasses that are being considered for structural support in solar thermal energy system silvered glass concentrator mirrors are assessed for strength-limiting defects by a nondestructive technique which measures the capacitance of well defined regions. The feasibility of locating large defects is demonstrated for the case of one type of cellular mass. Observed capacitance variations are believed to be due to small voids or other irregularities in the material. If the defects are equal to or greater than approximately 20 times the glass matrix pore size, they can be resolved with sufficient accuracy to delineate their spatial extent.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Nondestructive Evaluation; 2; June 198
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  • 97
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    Viscoelastic modelling of epoxy-resins for adhesive and composite applications (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Nonlinear viscoelastic and thermoelastic characterization procedures were applied to a rubber toughened adhesive that is commercially available as FM-300. Long time (accelerated testing) predictions on the basis of stress-time-superposition and time-temperature-superposition were compared with actual long term data. Good verification was obtained.
    Keywords: NONMETALLIC MATERIALS
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  • 98
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    Composition and properties of the so-called 'diamond-like' amorphous carbon films (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The composition of amorphous 'diamond-like' films made by direct low energy ion beam deposition, R.F. discharge and sputtering was determined by nuclear reaction analysis, IR spectroscopy and microcombustion chemical analysis. The nuclear reaction analysis showed very similar hydrogen depth profiles for all three types of samples. The atomic ratio of hydrogen to carbon was approximately 0.2 at the film surface and rose to approximately 1.0 at a depth of 500 A. The integrated intensity of the C-H stretching band at about 2900 per cm indicates that the amount of chemically bonded hydrogen is less than the total hydrogen content. Combustion analysis confirmed the overall atomic ratio of hydrogen to carbon determined by nuclear reaction analysis. The chemical state of the non-bonded hydrogen was not determined; however, the effective diffusion coefficient computed from the hydrogen depth profile was extremely low. This indicates either that the films are exceedingly impermeable or that the non-bonded hydrogen requires an additional activated step to leave the films, e.g., desorption or chemical reaction.
    Keywords: NONMETALLIC MATERIALS
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  • 99
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    Deposition stress effects on the life of thermal barrier coatings on burner rigs (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.
    Keywords: NONMETALLIC MATERIALS
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  • 100
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    Evaluation of high temperature structural adhesives for extended service (1984)
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    Publication Date: 2011-08-19
    Description: The preliminary evaluation of crosslinked polyphenyl quinoxaline (X-PPQ), LARC-TPI, ethyl terminated polysulfone (ETPS), and crosslinked polyimide (X-PI) as adhesives is presented. Lap shear strength stability under thermal, combined thermal/humidity, and stressed and unstressed Skydrol exposure was determined. The X-PPQ, LARC-TPI, and X-PI exhibited good adhesive performance at 505K (450 F) after 1000 hours at 505K. These three polymers also performed well after exposure to combined elevated temperature/high humidity, as well as, to Skydrol while under stress. The ETPS exhibited good ambient temperature adhesive properties, but performed poorly under all other exposure conditions, presumably due to inadequate chain extension and crosslinking.
    Keywords: NONMETALLIC MATERIALS
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