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  • Other Sources  (178)
  • NONMETALLIC MATERIALS  (178)
  • 1980-1984  (178)
  • 1950-1954
  • 1925-1929
  • 1983  (178)
  • 1
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    Surface crystallization of a fluoride glass (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Growth of crystals on the surface of a Zr-Ba-La fluoride glass was observed by optical and scanning electron microscopy. Small, dark crystal nucleated rapidly and grew to a size of about 10 microns; then they stopped growing, and wrinkled regions emerged, covering the entire crystal surface.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society, Communications (ISSN 0002-7820); 66; C-132
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  • 2
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    Thermal oxidative degradation reactions of linear perfluoroalkyl ethers (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Thermal and thermal oxidative stability studies were performed on linear perfluoroalkyl ether fluids. The effect on degradation by metal catalysts and degradation inhibitors is reported. The linear perfluoroalkyl ethers are inherently unstable at 316 C in an oxidizing atmosphere. The metal catalysts greatly increased the rate of degradation in oxidizing atmospheres. In the presence of these metals in an oxidizing atmosphere, the degradation inhibitors were highly effective in arresting degradation at 288 C. However, the inhibitors had only limited effectiveness at 316 C. The metals promote degradation by chain scission. Based on elemental analysis and oxygen consumption data, the linear perfluoroalkyl ether fluids have a structural arrangement based on difluoroformyl and tetrafluoroethylene oxide units, with the former predominating. Previously announced in STAR as N82-26468
    Keywords: NONMETALLIC MATERIALS
    Type: I&EC - Industrial and Engineering Chemistry, Product Research and Development (ISSN 0196-4321); 22; 166-170
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  • 3
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    Fracture mechanics of cellular glass (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solar concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses. Previously announced in STAR as N82-11209
    Keywords: NONMETALLIC MATERIALS
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  • 4
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    Simulated space radiation effects on dielectrics and coatings (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Simulation tests of space radiation have been performed for specific organic and inorganic materials. The test results for fifteen materials exposed to protons and five exposed to electrons are presented.
    Keywords: NONMETALLIC MATERIALS
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-30; 4090-409
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  • 5
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    The effect of annealing on the creep of plasma-sprayed ceramics (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The creep of plasma sprayed ZrO2-8Y2O3 was measured at temperatures from 98 to 1250 C (180 to 220 F), and compared to creep of identical samples after annealing at temperatures from 98 to 1316 C (1800 to 2400 F). Loads and temperatures which produced significant creep of as sprayed ceramics produced no creep after annealing. Previously announced in STAR as N83-24799
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 819-827
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  • 6
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    Residual stress in plasma-sprayed ceramic turbine tip and gas-path seal specimens (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The residual stresses in a ceramic sheet material used for turbine blade tip gas path seals, were estimated. These stresses result from the plasma spraying process which leaves the surface of the sheet in tension. To determine the properties of plasma sprayed ZrO2-Y2O3 sheet material, its load deflection characteristics were measured. Estimates of the mechanical properties for sheet materials were found to differ from those reported for plasma sprayed bulk materials. Previously announced in STAR as N83-28380
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 802-809
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  • 7
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    Correlation of compressive and shear stress with spalling of plasma-sprayed ceramic materials (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Ceramics on metal substrates for potential use as high temperature seals or other applications are exposed to forces originating from differences in thermal expansion between the ceramic and the metal substrate. This report develops a relationship between the difference in expansion of the ceramic and the substrate, defines conditions under which shear between the ceramic and the substrate occurs, and those under which bending forces are produced in the ceramic. The off-axis effect of compression forces resulting from high temperature plastic flow of the ceramic producing buckling of the ceramic is developed. Shear is associated with the edge or boundary stresses on the component while bending is associated with the distortion of an interior region. Both modes are significant in predicting life of the ceramic. Previously announced in STAR as N83-27016
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 810-818
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  • 8
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    Ultrasonic mixing of epoxy curing agents (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new technique for mixing solid curing agents into liquid epoxy resins using ultrasonic energy was developed. This procedure allows standard curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents with very high melt temperatures such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents with very high melt temperatures such as 4,4 prime-diaminobenzophenone (4,4 prime-DABP) (242 C) to be mixed without premature curing. Four aromatic diamines were ultrasonically blended into MY-720 epoxy resin. These were 4, 4 prime-DDS; 3,3 prime-DDA; 4, 4 prime-DABP and 3,3 prime-DABP. Unfilled moldings were cast and cured for each system and their physical and mechanical properties compared. Previously announced in STAR as N83-27018
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Quarterly (ISSN 0036-0821); 14; 46-50
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  • 9
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    Hardness of dense beta-Si3N4 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The effects of small changes in the concentration of an oxygen content densification aid on the room temperature microhardness of hot isostatically pressed and sintered beta-Si3N4 ceramics are studied. The compositions studied were Si3N4 containing 7 wt. pct BeSiN2, a fixed nonoxide densification aid, and 1.9-3.7 wt. pct oxygen as a second, variable densification aid. A proportional relationship between high density and high oxygen content, regardless of heat treatment type, is noted.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Materials Science Letters (ISSN 0261-8028); 2; 657-659
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  • 10
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    Stability of silica heat shield materials in the Space Shuttle environment (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Sample tiles of Space Shuttle reusable surface insulation (RSI) and fibrous refractory composite insulation (FRCI) have been alternately exposed to simulated mission heating and the Kennedy Space Center launch-pad environment for up to 50 cycles. The two types of tiles were coated with an identical glass composition. The coating on RSI tiles was prone to cracking in the test environment while the same coating on FRCI was not. Absorption of water contaminated with environmental deposits resulted in accelerated devitrification in the RSI tiles. Devitrification in FRCI tiles was significantly less. The rate of environmental degradation of tiles appeared to be dependent on the amount of water absorption.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 564-577
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  • 11
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    Surface chemistry, friction, and wear of Ni-Zn and Mn-Zn ferrites in contact with metals (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: X-ray photoelectron and Auger electron spectroscopy analysis were used in sliding friction experiments. These experiments were conducted with hot-pressed polycrystalline Ni-Zn and Mn-Zn ferrites, and single-crystal Mn-Zn ferrite in contact with various transition metals at room temperature in both vacuum and argon. The results indicate that Ni2O3 and Fe3O4 were present on the Ni-Zn ferrite surface in addition to the nominal bulk constituents, while MnO2 and Fe3O4 were present on the Mn-Zn ferrite surface in addition to the nominal bulk constituents. The coefficients of friction for the ferrites in contact with metals were related to the relative chemical activity of these metals. The more active the metal, the higher is the coefficient of friction. The coefficients of friction for the ferrites were correlated with the free energy of formation of the lowest metal oxide. The interfacial bond can be regarded as a chemical bond between the metal atoms and the oxygen anions in the ferrite surfaces. The adsorption of oxygen on clean metal and ferrite does strengthen the metal-ferrite contact and increase the friction. The ferrites exhibit local cracking and fracture with sliding under adhesive conditions. All the metals transferred to the surfaces of the ferrites in sliding. Previously announced in STAR as N83-19901
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 674-693
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  • 12
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    Shrinkage of amorphous silica fibers (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: By the application of a new technique, the viscosity of amorphous silica fibers was determined in the 1100-1350 C temperature range. An equation was derived that describes the kinetics of shrinkage of the fibers in terms of their radius, viscosity, and surface tension.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 492-501
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  • 13
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    Phase distributions in plasma-sprayed zirconia-yttria (1983)
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    Publication Date: 2011-08-18
    Description: The distribution of phases in plasma-sprayed zirconia-yttria has been determined over a range of yttria levels from 0 to 26.1 molpct YO(1.5) using room temperature X-ray diffractometry. Pure, plasma-sprayed zirconia is composed almost entirely of the monoclinic phase. At levels of yttria between 4 and 10 percent, a quenched-in tetragonal phase predominates, and at higher levels the cubic phase predominates. The phase distributions are compared with previously reported test lives of thermal barrier coatings formed from these materials. Regions of optimal lives were found to correlate with regions having high amounts of the tetragonal phase, small but nonzero amounts of the monoclinic phase, and little or none of the cubic phase. Possible relationships between phase composition and coating performance are discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society Bulletin (ISSN 0002-7812); 62; 1355-135
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  • 14
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    Development of plane strain fracture toughness test for ceramics using Chevron notched specimens (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Chevron-notched four-point-bend and short-bar specimens have been used to determine the fracture toughness of sintered aluminum oxide and hot-pressed silicon nitride ceramics. The fracture toughness for Si3N4 is found to be essentially independent of the specimen size and chevron notch configuration, with values ranging from 4.6 to 4.9 MNm exp -3/2. In contrast, significant specimen size and notch geometry effects have been observed for Al2O3, with the fracture toughness ranging from 3.1 to 4.7 MNm exp -3/2. These effects are attributed to a rising crack growth resistance curve for the Al2O3 tested.
    Keywords: NONMETALLIC MATERIALS
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  • 15
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    Microstructural characterization of SiC (SCS) filaments (1983)
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    Publication Date: 2011-08-18
    Description: Microstructural features of SiC('SCS') fibers demonstrating growth properties have been investigated using scanning and transmission electron microscopy. An etchant of fused KOH:KNO3 was developed which adequately brought out previously undetermined features.
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Quarterly (ISSN 0036-0821); 14; 39-45
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  • 16
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    Study of molecular deformation mechanisms in the glassy state. I - Temperature effect on stress-birefringence and strain-birefringence responses of poly(methyl methacrylate) (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Polymer Science: Polymer Physics Edition (ISSN 0098-1273); 21; 1647-166
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  • 17
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    Electrically conductive black optical paint (1983)
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    Publication Date: 2011-08-18
    Description: An electrically conductive flat black paint has been developed for use on the Galileo spacecraft which will orbit Jupiter in the late 1980s. The paint, designed for equipment operating in high-energy radiation fields, has multipurpose functions. Its electrical conductivity keeps differential charging of the spacecraft external surfaces and equipment to a minimum, preventing the buildup of electrostatic fields and arcing. Its flat black aspect minimizes the effects of stray light and unwanted reflectances, when used in optical instruments and on sunshades. Its blackness is suitable, also, for thermal control, when the paint is put on spacecraft surfaces. The paint has good adherence properties, as measured by tape tests, when applied properly to a surface. The electrically conductive paint which was developed has the following characteristics: an electrical resistivity of 5 x 10 to the 7th ohms per square; a visual light total reflectance of approximately 5 percent; an infrared reflectance of 0.13 measured over a spectrum from 10 to the (-5.5) power to 0.001 meter; a solar absorptivity, alpha-s, of 0.93, and a thermal emissivity, epsilon, of 0.87, resulting in an alpha-s/epsilon of 1.07. The formula for making the paint and the process for applying it are described.
    Keywords: NONMETALLIC MATERIALS
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  • 18
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    Characteristics of Si3N4-SiO2-Ce2O3 compositions sintered in high-pressure nitrogen (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Full-density Si3N4-SiO2-Ce2O3 compositions were prepared by sintering with 2.5 MPa nitrogen pressure at temperatures of 1900 and 2090 C. Room-temperature flexural strengths near 700 MPa for sintered material compared favorably with the strength of hot-pressed material. At 1370 C, where flexural strengths as high as 363 MPa were obtained, it was observed that the coarsest structure was the strongest and the finest structure was the weakest. One of the compositions tested, Si3N4-8.7 wt pct SiO2-8.3 wt pct-Ce2O3, was found to have excellent 200-h oxidation resistance at 700, 1000, and 1370 C, without incidence of 700 to 1000 C phase instability and cracking.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society, Journal (ISSN 0002-7820); 66; 835-841
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  • 19
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    Molecular deformation and stress-strain behavior of poly(bisphenol-A-diphenyl sulfone) (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The strain-birefringence response of poly(bisphenol-A-diphenyl sulfone) is found to be independent of temperature at temperatures below -100 C; at higher temperatures, the response becomes slightly dependent on temperature, with lower birefringence seen at higher temperatures. The stress-strain behavior and the stress-birefringence response both depend on temperature over the entire testing temperature range (-179 C to 150 C) studied; this dependence, however, is not pronounced. The evidence is seen as suggesting that the polymer molecules respond to deformation by undergoing conformational rearrangements; the mode of the molecular deformation remains unchanged for temperatures of -100 C or lower. At higher temperatures, the average length of the chain segments involved in the rearrangement increases. The stress-strain response is attributed mainly to chain orientation. The entropic contribution deriving from chain orientation at temperatures below -100 C is still substantial. The modest temperature dependence of the stress-strain response suggests that the energy barriers for the chain segments involved in the rearrangement are relatively low.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Applied Physics (ISSN 0021-8979); 54; Oct. 198
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  • 20
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    Photothermal degradation of ethylene/vinylacetate copolymer (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Photothermal degradation studies were conducted on a 'stabilized' formulation of ethylene/vinyl acetate copolymer (EVA) in the temperature range 25-105 C under three different oxygen environments (in open air, with limited access to O2, and in a dark closed stagnant oven). These studies were performed in order to evaluate the utility of EVA as an encapsulation material for photovoltaic modules. Results showed that at low temperature (25 C), slow photooxidation of the polymer occurred via electronic energy transfer involving the UV absorber incorporated in the polymer. However, no changes in the physical properties of the bulk polymer were detected up to 1500 hours of irradiation. At elevated temperatures, leaching and evaporation of the additives occurred, which ultimately resulted in the chemical crosslinking of the copolymer and the formation of volatile photoproducts such as acetic acid.
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  • 21
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    The structure of boron in boron fibres (1983)
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    Publication Date: 2011-08-18
    Description: The structure of noncrystalline, chemically vapour-deposited boron fibres was investigated by computer modelling the experimentally obtained X-ray diffraction patterns. The diffraction patterns from the models were computed using the Debye scattering equation. The modelling was done utilizing the minimum nearest-neighbour distance, the density of the model, and the broadening and relative intensity of the various peaks as boundary conditions. The results suggest that the fibres consist of a continuous network of randomly oriented regions of local atomic order, about 2 nm in diameter, containing boron atoms arranged in icosahedra. Approximately half of these regions have a tetragonal structure and the remaining half a distorted rhombohedral structure. The model also indicates the presence of many partial icosahedra and loose atoms not associated with any icosahedra. The partial icosahedra and loose atoms indicated in the present model are in agreement with the relaxing sub-units which have been suggested to explain the anelastic behavior of fibre boron and the loosely bound boron atoms which have been postulated to explain the strengthening mechanism in boron fibres during thermal treatment.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Materials Science (ISSN 0022-2461); 18; Sept
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  • 22
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    Lower-curing-temperature PMR polyimides (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Partial substitution of a p-aminostyrene end-cap for the monomethyl ester of 5-norbornene-2, 3-dicarboxylic acid lowered the final cure temperature of typical PMR resins from 600 F to 500 F. The weight loss characteristics of neat resins and graphite fiber composites prepared by using the mixed end-cap approach were determined at 600 F. The room temperature and short-time elevated temperature mechanical properties of the composites at 550 F and 600 F were determined. The mechanical property retention characteristics of the composites at 550 F and 600 F are discussed. Previously announced in STAR as N83-10118
    Keywords: NONMETALLIC MATERIALS
    Type: Polymer Composites (ISSN 0272-8397); 4; July 198
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  • 23
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    Dynamic fatigue of a machinable glass-ceramic (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: To assess the stress-corrosion susceptibility of a machinable glass-ceramic, its dynamic fatigue behavior was investigated by measuring its strength as a function of stress rate. Fracture mechanics techniques were used to analyze the results for the purpose of making lifetime predictions for components of this material. This material was concluded to have only moderate resistance (N = 30) to stress corrosion in ambient conditions. The effects of specimen size on strength were assessed for the material used in this study; it was concluded that the Weibull edge-flaw scaling law adequately describes the observed strength-size relation.
    Keywords: NONMETALLIC MATERIALS
    Type: (ISSN 0002-7820)
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  • 24
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    Experimental determination of vapor species from laser-ablated carbon phenolic composites (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previosuly cited in issue 17, p. 2910, Accession no. A81-39069
    Keywords: NONMETALLIC MATERIALS
    Type: (ISSN 0001-1452)
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  • 25
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    Surface analyses of carbon fibers produced from polyacrylonitrile fibers at low carbonization temperatures (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A process for producing carbon fibers from polyacrylonitrile at low carbonization temperatures was studied. The bulk and surface properties of fibers obtained after reaction with benzoic acid, air and carbonizing in nitrogen or a dilute acetylene atmosphere are discussed. All fiber products had different surface and internal compositions. Samples produced at temperatures up to 950 C and carbonized in nitrogen contained substantial quantities of nitrogen and oxygen at the surface. During carbonization, the surface nitrogen converted into two new forms, possibly nitrile and an azo or a new carbon-nitrogen bond. Samples carbonized in acetylene contained a carbon-rich surface stable to oxidation.
    Keywords: NONMETALLIC MATERIALS
    Type: Textile Research Journal (ISSN 0040-5175); 53; July 198
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  • 26
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    Cavitation erosion characteristics of poly(methyl methacrylate) in a rotating disk device (1983)
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    Publication Date: 2011-08-18
    Description: The cavitation erosion behavior including the initiation, dynamics and mechanism of damage process on perspex and epoxy resin specimens tested in a rotating disk device were discussed with respect to exposure time. The inception of erosion always took place at the location nearest to the center of rotation of the disk. Subsequently, as exposure time increased, erosion initiated at other locations as well. Light optical photographs and scanning electron micrographs clearly indicate that most of the material loss appears to occur form the networks of cracks due to their interaction and pits indicate particle debris. The optical degradation (loss of transmittance) on perspex was observed to be more on the rear side than on the front side. Previously announced in STAR as N83-11329
    Keywords: NONMETALLIC MATERIALS
    Type: (ISSN 0043-1648)
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  • 27
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    Ultrahigh Molecular Weight Aromatic Siloxane Polymers (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: Silphenylene-siloxane polymers can be prepared by a condensation reaction of a diol 1,4-bis(hydroxydimethylsilyl)benzene and a silane bis(dimethylamino)dimethylsilane. Using a stepwise condensation technique, a polymer (R=CH3) with a molecular weight in excess of 1.0 x 1 million has been produced. The polymer exhibits increased thermal stability, compared to a methyl siloxane polymer without the aromatic phenyl ring in the backbone. The use of bis(dimethylamino)methylvinylsilane should allow for ready crosslinking at the vinyl sites (R=-CH=CH2) introduced into the backbone. However, under the conditions of the reaction system a high molecular weight polymer was not obtained or the polymer underwent a crosslinking process during the synthesis.
    Keywords: NONMETALLIC MATERIALS
    Type: Alabama Univ. Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 13 p
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  • 28
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    Fire- and heat-resistant laminating resins based on maleimido-substituted aromatic cyclotriphosphazenes (1983)
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    Publication Date: 2011-08-18
    Description: A novel class of flame- and heat-resistant polymers has been synthesized by the thermal polymerization of maleimido-substituted aromatic cyclotriphosphazenes. The polymer obtained from tris-(aminophenoxy)tris(maleimidophenoxy)cyclotriphosphazene has good thermal stability and is noteworthy for its high char yield, viz., 82 percent at 800 C in nitrogen and 81 percent at 700 C in air. Graphite-fabric laminates prepared with this polymer did not burn in pure oxygen, even at 300 C, and were tested for mechanical properties. Hexakis(4-maleimidophenoxy)cyclotriphosphazene and some fluorine-containing monomers have also been synthesized. The structures of these cyclic phosphazene precursors and polymers were characterized by FT IR spectrophotometry, H-1 NMR, F-19 NMR, and P-31 solid-state magic angle spinning NMR spectroscopy, and mass spectrometry. The curing behavior of the polymer precursors and the thermal stabilities of the polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA).
    Keywords: NONMETALLIC MATERIALS
    Type: Macromolecules (ISSN 0024-9297); 16; 8, 19
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  • 29
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    Thermal response of advanced high temperature ceramic-composite insulation to a convectively heated environment (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The Space Shuttle uses currently fibrous high temperature, reusable surface insulation (HRSI) as a Thermal Protection System (TPS) at 1260 C for normal-design mission operation. Higher density material of a similar type extended the maximum temperature to 1480 C. However, a surface temperature capability exceeding 1540 C is desired for future space vehicles, such as the Orbital Transfer Vehicle (OTV). A TPS providing such a capability would permit future entry vehicles to enter the atmosphere at a much higher velocity than the Space Shuttle. The present investigation is concerned with arc-jet test data obtained from a family of fibrous refractory-composite insulation (FRCI) materials developed to meet the future TPS requirements. FRCI materials containing between 20 and 80 percent aluminoborosilicate fibers with the balance composed of silica fibers were studied.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 533-550
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  • 30
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    Fire resistant films for aircraft applications (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Alternative sandwich panel decorative films were investigated as replacements for the polyvinyl fluoride currently used in aircraft interiors. Candidate films were studied for flammability, smoke emission, toxic gas emission, flame spread, and suitability as a printing surface for the decorative acrylic ink system. Several of the candidate films tested were flame modified polyvinyl fluoride, polyvinylidene fluoride, polyimide, polyamide, polysulfone, polyphenylsulfone, polyethersulfone, polybenzimidazole, polycarbonate, polyparabanic acid, polyphosphazene, polyetheretherketon, and polyester. The films were evaluated as pure films only, films silk-screened with an acrylic ink, and films adhered to a phenolic fiberglass substrate. Films which exhibited the highest fire resistant properties included PEEK polyetheretherketon, Aramid polyamide, and ISO-BPE polyester. Previously announced in STAR as N83-22320
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Fire Sciences (ISSN 0734-9041); 1; 200-220
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  • 31
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    A basic design fault in ceramic flat packs (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Recent moisture resistance tests of various multilayer top brazed ceramic flat packs and leaded and unleaded chip carriers has revealed a serious design defect. These packages, which utilize a tungsten interconnect system, in the presence of high humidity, suffer a galvanic corrosion which anodically consumes the tungsten. This process can continue until the package suffers an open circuit. The test results indicate that the lead plating system does not adequately seal off the interface area where the tungsten stripe egresses from the inside of the package. Leaded and leadless chip carrier packages were also subjected to the moisture resistance test. The familiar red and green corrosion products were visible after the test was completed. Careful sectioning of the chip carriers has revealed that the tungsten interconnect stripe instead of exiting under the castellations, exits at the top of the castellation and is thus vulnerable to the attack of moisture. These basic design faults severely impact the reliability of these packages.
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  • 32
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    Resin characterization in cured graphite fiber reinforced composites using diffuse reflectance-FTIR (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The feasibility of using diffuse reflectance in combination with Fourier transform infrared spectroscopy to obtain information on cured graphite fiber reinforced polymeric matrix resin composites was investigated. Several graphite/epoxy, polysulfone, and polyimide composites exposed to thermal or radiation environments were examined. An experimental polyimide-sulfone adhesive tape was also studied during processing. In each case, significant changes in resin molecular structure was observed due to environmental exposure. These changes in molecular structure were correlated with previously observed changes in material properties providing new insights into material behavior.
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  • 33
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    Acetylene-terminated polyimide adhesives (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The nadic-encapped LARC-43 addition polyimide exhibits excellent flow, is easy to process, and can be utilized for short terms at temperatures up to 593 C. It retains good lap shear strength as an adhesive for titanium after aging in air up to 125 hours at 316 C; but lap shear strength degrades with longer exposures at that temperature. Thermid 600, an addition polyimide that is acetylene encapped, exhibits thermomechanical properties even after long term exposure in at air at 316 C. An inherent drawback of this system is that it has a narrow processing window. An acetylene encapped, addition polyimide which is a hybrid of these two systems was developed. It has good retention of strength after long term aging and is easily processed. The synthesis and characterization of various molecular weight oligomers of this system are discussed as well as the bonding, aging, and testing of lap shear adhesive samples. Previously announced in STAR as N83-18910
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  • 34
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    Maleimido substituted cyclotriphosphazene resins for fire and heat resistant composites (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A new class of fire- and heat-resistant matrix resins have been synthesized by the thermal polymerization of maleimido substituted phenoxycyclotriphosphazenes. The resins have exhibited a char yield of 82 percent at 800 C in nitrogen and 81 percent at 700 C in air. Graphite-fabric laminates based on a resin of this class have shown a limiting oxygen index of 100 percent even at 300 C. Details of the fabrication of the resins and the composites and testing procedures are discussed.
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  • 35
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    A basic design fault in ceramic flat packs (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Recent moisture resistance tests of various multilayer top brazed ceramic flat packs and leaded and unleaded chip carriers has revealed a serious design defect. These packages, which utilize a tungsten interconnect system, in the presence of high humidity, suffer a galvanic corrosion which anodically consumes the tungsten. This process can continue until the package suffers an open circuit. The test results indicate that the lead plating system does not adequately seal off the interface area where the tungsten strips egresses from the inside of the package.
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Quarterly (ISSN 0036-0821); 14; 28-32
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  • 36
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    Kinetics of crystallization of ZrF4-BaF2-LaF3 glass by differential scanning calorimetry (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society, Journal (ISSN 0002-7820); 66; April 19
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  • 37
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    Tribological properties of sintered polycrystalline and single-crystal silicon carbide (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previously announced in STAR as N82-24343
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society Bulletin (ISSN 0002-7812); 62; April 19
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  • 38
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    Strength and fracture toughness of reaction-bonded Si3N4 (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Fracture strength and fracture toughness measurements were made on reaction-bonded Si3N4 materials with a range of alpha/beta ratios. The results do not indicate any clear relation between the modulus of rupture and the alpha/beta ratio over the range 1.5-9. Values for the modulus of rupture range from 219 to 290 MN per sq m, with an overall average of 238 MN per sq m. The notched beam fracture toughness is found to be constant over the range of microstructures produced, indicating that of the various microstructural features (e.g., alpha/beta ratio and pore size and distribution) no single element has a controlling influence over fracture toughness and the fracture surface energy.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society Bulletin (ISSN 0002-7812); 62; April 19
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  • 39
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    Experimental studies of the vapor phase nucleation of refractory compounds. II - The condensation of an amorphous magnesium silicate (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Chemical Physics; 78; Feb. 1
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  • 40
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    Glass formation - A contemporary view (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The process of glass formation is discussed from several perspectives. Particular attention is directed to kinetic treatments of glass formation and to the question of how fast a given liquid must be cooled in order to form a glass. Specific consideration is paid to the calculation of critical cooling rates for glass formation, to the effects of nucleating heterogeneities and transients in nucleation on the critical cooling rates, to crystallization on reheating a glass, to the experimental determination of nucleation rates and barriers to crystal nucleation, and to the characteristics of materials which are most conducive to glass formation.
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  • 41
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    Glass research in space (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Opportunities and problems associated with conducting containerless glass experiments in a microgravity environment are examined. Particular aspects of gel-derived glasses for space processing research are discussed, along with current space-related research activities in areas of amorphous phase separation, crystallization, and heterogeneous and homogeneous crystal nucleation.
    Keywords: NONMETALLIC MATERIALS
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  • 42
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    Gels and gel-derived glasses in the system Na2O-B2O3-SiO2 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The containerless melting of high-purity multicomponent homogeneous gels and gel monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the system Na2O-B2O3-SiO2 are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures was found to be significantly different. Infrared absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel monoliths to transparent 'glass' without melting are described.
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  • 43
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    Effects of long duration exposure to simulated space environment on nonmetallic materials properties (1983)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Nonmetallic materials specimens from the Viking program were tested in situ invacuo after continuous thermal vacuum exposure from 1971/1972 to the present. Eleven tests were done on appropriate specimens of 30 materials; however, no single material received all the tests. Some specimens also were exposed to 1 or 2.5 MeV electrons at differing fluences before testing. Baseline exposure data is reported for graphite/epoxy specimens that were exposed to vacuum since 1974. These materials were transferred to the thermal vacuum storage facility for future in situ testing and irradiation. Thin G/E specimens were tensile tested after thermal-vacuum cycling exposure. Photomicrographic examinations and SEM analyses were done on the failed specimens.
    Keywords: NONMETALLIC MATERIALS
    Type: AGARD Environ. Effects on Mater. for Space Appl.; 14 p
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  • 44
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    Synthesis of N-Substituted Silaneamines: Monomeric Precursors of Silicon Carbide-Nitride Fibers (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-10
    Description: Silanetriamines are prepared by the condensation of methyl or phenyl trichlorosilane with a primary amine. The amines used were methyl, n-propyl, n-butyl and allyl. The silaneamines were prepared by adding the chlorosilane to a solution of the amine in either petroleum ether or toluene. The compounds were purified by distillation and characterized by infrared and nuclear magnetic resonance spectroscopy.
    Keywords: NONMETALLIC MATERIALS
    Type: Alabama Univ. Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 21 p
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  • 45
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    Partial Analysis of Insta-Foam (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-12
    Description: Insta-Foam, used as a thermal insulator for the non-critical area of the external tank during the prelaunch phase to minimize icing, is a two-component system. Component A has polyisocyanates, blowing agents, and stabilizers; Component B has the polyols, catalysts, blowing agents, stabilizers and fire retardant. The blowing agents are Freon 11 and Freon 12, the stabilizers are silicone surfactants, the catalysts are tertiary amines, and the fire retardant is tri-(beta-chloro-isopropyl) phosphate (PCF). High performance liquid chromatography (HPLC) was quantitatively identified polyols and PFC.
    Keywords: NONMETALLIC MATERIALS
    Type: Alabama Univ. Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 30 p
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  • 46
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    Improved high temperature resistant matrix resins (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The objective was to develop organic matrix resins suitable for service at temperatures up to 644 K (700 F) and at air pressures up to 0.4 MPa (60 psia) for time durations of a minimum of 100 hours. Matrix resins capable of withstanding these extreme oxidative environmental conditions would lead to increased use of polymer matrix composites in aircraft engines and provide significant weight and cost savings. Six linear condensation, aromatic/heterocyclic polymers containing fluorinated and/or diphenyl linkages were synthesized. The thermo-oxidative stability of the resins was determined at 644 K and compressed air pressures up to 0.4 MPa. Two formulations, both containing perfluoroisopropylidene linkages in the polymer backbone structure, exhibited potential for 644 K service to meet the program objectives. Two other formulations could not be fabricated into compression molded zero defect specimens.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-168210 , NAS 1.26:168210 , REPT-38945-6012-UT-00
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  • 47
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    MEA/A-1 experiment 81F01 conducted on STS-7 flight, June 1983. Containerless processing of glass forming melts (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The space processing of containerless, glassforming melts on board the space shuttle flight STS-7 is investigated. Objectives include; (1) obtain quantitative evidence for the supression of heterogeneous nucleation/crystallization, (2) study melt homogenization without gravity driven convection, (3) procedural development for bubble free, high purity homogeneous melts inmicro-g, (4) comparative analysis of melts on Earth and in micro g, and (5) assess the apparatus for processing multicomponent, glass forming melts in a low gravity environment.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-171048 , NAS 1.26:171048
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  • 48
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    Ablation of carbonaceous materials in a hydrogen-helium arc-jet flow (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The stagnation-point ablation rates of a graphite, a carbon-carbon composite, and four carbon-phenolic materials are measured in an arc-jet wind tunnel with a 50 percent hydrogen-50 percent helium mixture as the test gas. Flow environments are determined through measurements of static and impact pressures, heat-transfer rates to a calorimeter, and radiation spectra, and through numerical calculation of the flow through the wind tunnel, spectra, and heat-transfer rates. The environments so determined are: impact pressure approximately equal to 3 atm, Mach number approximately equal to 2.1, convective heat-transfer rate approximately equal to 14 kW/sq cm, and radiative heat-transfer rate approximately equal to 7 kW/sq cm in the absence of ablation. Ablation rates are determined from the measured rates of mass loss and recession of the ablation specimens. Compared with the predicted ablation rates obtained by running RASLE and CMA codes, the measured rates are higher by about 15 percent for all tested materials.
    Keywords: NONMETALLIC MATERIALS
    Type: AIAA PAPER 83-1561
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  • 49
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    Elastomeric binders for electrodes (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The poor mechanical integrity of the cathode represents an important problem which affects the performance of ambient temperature secondary lithium cells. Repeated charge of a TiS2 cathode may give rise to stresses which disturb the electrode structure and can contribute to capacity loss. An investigation indicates that the use of an inelastic binder material, such as Teflon, aggravates the problem, and can lead to electrode disruption and poor TiS2 particle-particle contact. The feasibility of a use of elastomers as TiS2 binder materials has, therefore, been explored. It was found that elastomeric binders provide an effective approach for simplifying rechargeable cathode fabrication. A pronounced improvement in the mechanical integrity of the cathode structure contributes to a prolonged cycle life.
    Keywords: NONMETALLIC MATERIALS
    Type: Electrochemical Society, Journal (ISSN 0013-4651); 130; May 1983
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  • 50
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    A probabilistic analysis of silicon cost (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Silicon materials costs represent both a cost driver and an area where improvement can be made in the manufacture of photovoltaic modules. The cost from three processes for the production of low-cost silicon being developed under the U.S. Department of Energy's (DOE) National Photovoltaic Program is analyzed. The approach is based on probabilistic inputs and makes use of two models developed at the Jet Propulsion Laboratory: SIMRAND (SIMulation of Research ANd Development) and IPEG (Improved Price Estimating Guidelines). The approach, assumptions, and limitations are detailed along with a verification of the cost analyses methodology. Results, presented in the form of cumulative probability distributions for silicon cost, indicate that there is a 55% chance of reaching the DOE target of $16/kg for silicon material. This is a technically achievable cost based on expert forecasts of the results of ongoing research and development and do not imply any market prices for a given year.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-173461 , JPL-5101-246 , JPL-PUB-83-94 , DOE/JPL-1012/93 , NAS 1.26:173461
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  • 51
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    Shock temperatures in anorthite glass (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Temperatures of CaAl2Si2O8 (anorthite glass) shocked to pressures between 48 and 117 GPa were measured in the range from 2500 to 5600 K, using optical pyrometry techniques. The pressure dependence of the shock temperatures deviates significantly from predictions based on a single high pressure phase. At least three phase transitions, at pressures of about 55, 85, and 100 GPa and with transition energies of about 0.5 MJ/kg each (approximately 1.5 MJ/kg total) are required to explain the shock temperature data. The phase transition at 100 GPa can possibly be identified with the stishovite melting transition. Theoretical models of the time dependence of the thermal radiation from the shocked anorthite based on the geometry of the experiment and the absorptive properties of the shocked material yields good agreement with observations, indicating that it is not necessary to invoke intrinsic time dependences to explain the data in many cases.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-173364 , NAS 1.26:173364
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  • 52
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    Consolidation of Si3N4 without additives (by hot isostatic pressing) (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The potential of using hot isostatic pressing (HIP'ing) technique to produce dense silicon nitride materials without or with a reduced amount of additives (much less than 5 w/o) was investigated. Hot isostatic pressing technique can provide higher pressure and temperature than hot pressing can, thus has the potential of requiring less densification aids to consolidate Si3N4 materials. It was anticipated that if such dense materials could be fabricated, the high temperature strength of the material should be improved significantly. Observations on the phase transformation, densification behavior, and microstructures of the samples are also documented. Density, microhardness, four point bend strength (room temperature and 1370 C) were measured on selected densified materials.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-173279 , NAS 1.26:173279
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  • 53
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    Energy absorption by polymer crazing (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: During the past thirty years, a tremendous amount of research was done on the development of crazing in polymers. The phenomenon of crazing was recognized as an unusual deformation behavior associated with a process of molecular orientation in a solid to resist failure. The craze absorbs a fairly large amount of energy during the crazing process. When a craze does occur the surrounding bulk material is usually stretched to several hundred percent of its original dimension and creates a new phase. The total energy absorbed by a craze during the crazing process in creep was calculated analytically with the help of some experimental measurements. A comparison of the energy absorption by the new phase and that by the original bulk uncrazed medium is made.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-173275 , NAS 1.26:173275
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  • 54
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    Nonlinear viscoelastic characterization of structural adhesives (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Measurements of the nonliner viscoelastic behavior of two adhesives, FM-73 and FM-300, are presented and discussed. Analytical methods to quantify the measurements are given and fitted into a framework of an accelerated testing and analysis procedure. The single integral model used is shown to function well and is analogous to a time-temperature stress-superposition procedure (TTSSP). Advantages and disadvantages of the creep power law method used in this study are given.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-172279 , NAS 1.26:172279
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  • 55
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    Hot melt recharge system (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A package assembly is described for pecisely positioning a charge of hot melt adhesive onto an attachment pad or point of use. The adhesive is heated to softening or melt temperature (280 F to 325 F) and thereafter cooled to resolidifying temperature. A single sided pressure sensitive polyimide film tape serves with another film strip to protect a sandwiched adhesive strip until use and to hold the adhesive in precise position until thermally bonded to its point of use. Tab ends serve as aids in stripping tapes and from the adhesive charge.
    Keywords: NONMETALLIC MATERIALS
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  • 56
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    Heat sealable, flame and abrasion resistant coated fabric (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.
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  • 57
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    Elastomer-modified phosphorus-containing imide resins (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Phosphine oxide-containing polyimide resins modified by elastomers, are disclosed which have improved mechanical properties. These products are particularly useful in the production of fiber or fabric-reinforced composites or laminates.
    Keywords: NONMETALLIC MATERIALS
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  • 58
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    Development of strain tolerant thermal barrier coating systems, tasks 1 - 3 (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Insulating ceramic thermal barrier coatings can reduce gas turbine airfoil metal temperatures as much as 170 C (about 300 F), providing fuel efficiency improvements greater than one percent and durability improvements of 2 to 3X. The objective was to increase the spalling resistance of zirconia based ceramic turbine coatings. To accomplish this, two baseline and 30 candidate duplex (layered MCrAlY/zirconia based ceramic) coatings were iteratively evaluated microstructurally and in four series of laboratory burner rig tests. This led to the selection of two candidate optimized 0.25 mm (0.010 inch) thick plasma sprayed partially stabilized zirconia ceramics containing six weight percent yttria and applied with two different sets of process parameters over a 0.13 mm (0.005 inch) thick low pressure chamber sprayed MCrAlY bond coat. Both of these coatings demonstrated at least 3X laboratory cyclic spalling life improvement over the baseline systems, as well as cyclic oxidation life equivalent to 15,000 commercial engine flight hours.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-168251 , NAS 1.26:168251 , PWA-5777-29
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  • 59
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    Material characterization of structural adhesives in the lap shear mode (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A general method for characterizing structural adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semi-empirical and theoretical approaches are used. The semi-empirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Three different model adhesives are used in the simple lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-172237 , NAS 1.26:172237
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  • 60
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    Theory of nuclear magnetic relaxation (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A theory of nuclear magnetic interaction is based on the study of the stochastic rotation operator. The theory is applied explicitly to relaxation by anisotropic chemical shift and to spin-rotational interactions. It is applicable also to dipole-dipole and quadrupole interactions.
    Keywords: NONMETALLIC MATERIALS
    Type: AD-P003911 , Trinity Coll. Nucl. Magnetic Resonance of Polymeric Mater.; 16 p
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  • 61
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    13C and 1H NMR (Nuclear Magnetic Resonance) studies of solid polyolefines (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The basis of H-1 and C-13 high-resolution NMR investigations of solid polymers is outlined. The C-13 NMR spectra of solid syndiotactic and isotactic polypropene are discussed and their interpretation in terms of conformation and chain-packing effects are reviewed. The effects of decreasing temperature on the C-13 high-resolution spectrum of an annealed sample of isotactic polypropene is described and interpreted in terms of the crystal structure. The question of the proportion of the sample giving rise to C-13 signals is addressed and some results reported. The main cause for observing only part of the total sample is shown to be the H-1 rotating frame spin-lattice relaxation behavior. The H-1 spin-lattice relaxation and spectral characteristics of a number of polyolefin samples are summarized and the role of spin-diffusion discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: AD-P003909 , Trinity Coll. Nucl. Magnetic Resonance of Polymeric Mater.; 32 p
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  • 62
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    Deuteron NMR (Nuclear Magnetic Resonance) in relation to the glass transition in polymers (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: H-2NMR is introduced as a tool for investigating slow molecular motion in the glass transition region of amorphous polymers. In particular, we compare H-2 spin alignment echo spectra of chain deuterated polystyrene with model calculations for restricted rotational Brownian motion. Molecular motion in the polyztyrene-toluene system has been investigated by analyzing H-2NMR of partially deuterated polystyrene and toluene, respectively. The diluent mobility in the mixed glass has been decomposed into solid and liquid components where the respective average correlation times differ by more than 5 decades.
    Keywords: NONMETALLIC MATERIALS
    Type: AD-P003910 , Trinity Coll. Nucl. Magnetic Resonance of Polymeric Mater.; 21 p
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  • 63
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    Development of an improved protective cover/light block for multilayer insulation (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The feasibility of using a scrim-reinforced, single metallized, 4-mil Tedlar film as a replacement for the Teflon coated Beta-cloth/single metallized 3-mil Kapton film presently used as the protective cover/light block for multilayer insulation (MLI) on the Orbiter, Spacelab, and other space applications was demonstrated. The proposed Tedlar concept is lighter and potentially lower in cost. Thermal analysis with the proper concept was much simpler than with the present system. Tests have already demonstrated that white Tedlar has low alpha (adsorption) degradation in space from U.V. The proposed concept was 4400 percent cheaper with nominal weight savings of 50 percent.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-82563 , NAS 1.15:82563
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  • 64
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    Synthesis and characterization of bisimide amines and bisimide amine-cured epoxy resins (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An attempt is made to develop tough, moisture resistant, high char yield epoxy resins by means of novel bisimide amine (BIA) hardener curing agents and a state-of-the-art epoxy resin system. The BIAs are isolated as mixtures containing monomer, oligomer, and polymeric species, and then characterized by elemental analysis and high pressure liquid chromatography. The bisimide amine-cured epoxies (IMEs) were characterized with respect to moisture absorption, thermal properties, and physical and mechanical properties, as well as in the role of matrices in Celion 6000/IME composites. The relative toughness characteristics of each IME formulation was measured by the 10 deg off-axis tensile test, measuring the uniaxial tensile strength, shear strength, and shear-strain-to-failure of the composite systems.
    Keywords: NONMETALLIC MATERIALS
    Type: Polymer Composites (ISSN 0272-8397); 4; July 198
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  • 65
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    Fracture toughness/Young's modulus correlation for low-density fibrous silica bodies (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Fracture toughness and static Young's modulus were measured for the low-density silic fiber materials used as tiles in the thermal protection system of the Space Shuttle. The fracture behavior was found to be in excellent agreement with a previously formulated micromechanical model and allowed both (density) classes of tile material to be correlated to a single function. A similar correlation was also found between strength and Young's modulus, which is the basis of a nondestructive evaluation test for these materials. It was shown that the value of Young's modulus determined from a dynamic test can be substantially greater than that determined in a static mechanical test. This effect must be taken into account in the correlation. Finally, it was also determined that these materials have significant variations in Kc, both within and between production units, so that the strength variability in these materials is dependent on both fracture toughness and flaw-size variations.
    Keywords: NONMETALLIC MATERIALS
    Type: (ISSN 0002-7820)
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  • 66
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    Photooxidative degradation of clear ultraviolet absorbing acrylic copolymer surfaces (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Photodegradation of copolymer of methyl methacrylate and 2(2'-hydroxy 5'vinyl-phenyl) 2H-benzotriazole has been investigated in order to determine the changes in the chemical composition of the surface of the copolymer on photooxidation. An electronic energy transfer mechanism has been postulated in order to interpret the observed photochemical changes in the polymer. Preliminary examination of the photophysical properties of the chromophore provides support for such a mechanism.
    Keywords: NONMETALLIC MATERIALS
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  • 67
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    Dynamic fracture toughnesses of reaction-bonded silicon nitride (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The room-temperature dynamic fracture response of reaction-bonded silicon nitride is investigated using a hybrid experimental-numerical procedure. In this procedure, experimentally determined crack velocities are utilized to drive a dynamic finite-element code or dynamic finite-difference code in its generation mode in order to extract numerically the dynamic stress intensity factor of the fracturing specimen. Results show that the dynamic fracture toughness vs crack velocity relations of the two reaction-bonded silicon nitrides do not follow the general trend in those relations of brittle polymers and steel. A definite slow crack velocity during the initial phase of dynamic crack propagation is observed in reaction-bonded silicon nitride, which results in a nonunique dynamic fracture toughness vs crack velocity relation. In addition, it is found that a propagating crack will continue to propagate under a static stress intensity factor substantially lower than K(IC).
    Keywords: NONMETALLIC MATERIALS
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  • 68
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    Elevation of liquidus temperature in a gel-derived Na2O-SiO2 glass (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The liquidus temperatures of a 19 wt% soda-silica glass prepared by gel and conventional techniques were determined. X-ray diffraction measurements of the glasses which were heat-treated at several temperatures were used to experimentally determine the liquidus temperatures. It was found that the gel-derived glass has an elevated liquidus. This result is discussed in relation to the previous discovery that the immiscibility temperature of this gel-derived glass is elevated
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 66
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  • 69
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    Phosphorus-containing imide resins (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Bis- and tris-imides derived from tris (m-aminophenyl) phosphine oxides by reaction with maleic anhydride or its derivatives, and addition polymers of such imides, including a variant in which a mono-imide is condensed with a dianhydride and the product is treated with a further quantity of maleic anhydride. Such monomers or their oligomes may be used to impregnate fibers and fabrics which when cured, are flame resistant. Also an improved method of producing tris (m-aminophenyl) phosphine oxides from the nitro analogues by reduction with hydrazine hydrate using palladized charcoal or Raney nickel as the catalyst is described.
    Keywords: NONMETALLIC MATERIALS
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  • 70
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    Evaluation of ceramics for stator applications: Gas turbine engines interim report. Stator fabrication and evaluation (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The objective was to assess current ceramic materials, fabrication processes, reliability prediction, and stator durability when subjected to simulated automotive gas turbine engine operating conditions. Ceramic one-piece stators were fabricated of two materials, silicon nitride and silicon carbide, using two near-net-shape processes, slip casting and injection molding. Non-destructive evaluation tests were conducted on all stators identifying irregularities which could contribute to failures under durability testing. Development of the test rig and automatic control system for repeatably controlling air flow rate and temperature over a highly transient durability duty cycle is discussed. Durability results are presented for repeated thermal cycle testing of the ceramic one-piece stators. Two duty cycles were used, encompassing the temperature ranges of 704 to 1204 C (1300 to 2200 F) and 871 to 1371 C (1600 to 2500 F). Tests were conducted on 28 stators, accumulating 135,551 cycles in 2441 hours of hot testing. Cyclic durability for the ceramic one-piece stator was demonstrated to be in excess of 500 hours, accumulating over 28,850 thermal cycles. Ceramic interface forces were found to be the significant factor in limiting stator life rather than the scatter in material strength properties or the variation in component defects encountered.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-168140 , DOE/NASA/0019-83/1 , NAS 1.26:168140
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  • 71
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    NASA interdisciplinary collaboration in tribology. A review of oxidational wear (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An in-depth review of oxidational wear of metals is presented. Special emphasis is given to a description of the concept of oxidational wear and the formulation of an Oxidational Wear Theory. The parallelism between the formation of an oxide film for dry contact conditions and the formation of other surface films for a lubricated contact is discussed. The description of oxidational wear is prefaced with a unification of wear modes into two major classes of mild and severe wear including both lubricated and dry contacts. Oxidational wear of metals is a class of mild wear where protective oxide films are formed at real areas of contact and during the time of contact at temperataure T sub c. When the oxide reaches a critical thickness, frequently in the range of 1 to 3 microns, the oxide breaks up and eventually appears as a wear particle. These oxides are preferentially formed on plateaux which alternately carry the load as they reach their critical thickness and are removed. If the system is operated at elevated temperatures, thick oxides can form both out of contact and between the plateaux. Temperature is important in determining the structure of the oxide film present. Spinel oxide (Fe3O4) which forms above 300 C is more protective than the lower temperature rhomobohedral (alpha-Fe2O3) oxide which is abrasive. An Oxidational Wear Theory is derived using a modified Archard wear law expressed in terms of activation energy (Qp) and Arrhenius constant (Ap).
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-3686 , E-1573 , NAS 1.26:3686
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  • 72
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    Slow crack growth in spinel in water (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Magnesium aluminate spinel was tested in a water environment at room temperature to establish its slow crack-growth behavior. Ring specimens with artificial flaws on the outside surface were loaded hydraulically on the inside surface. The time to failure was measured. Various precracking techniques were evaluated and multiple precracks were used to minimize the scatter in the static fatigue tests. Statistical analysis techniques were developed to determine the strength and crack velocities for a single flaw. Slow crack-growth rupture was observed at stress intensities as low as 70 percent of K sub c. A strengthening effect was observed in specimens that had survived long-time static fatigue tests.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-85644 , NAS 1.15:85644
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  • 73
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    Metallized coatings for corrosion control of Naval ship structures and components (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In attempting to improve corrosion control, the U.S. Navy has undertaken a program of coating corrosion-susceptible shipboard components with thermally sprayed aluminum. In this report the program is reviewed in depth, including examination of processes, process controls, the nature and properties of the coatings, nondestructive examination, and possible hazards to personnel. The performance of alternative metallic coating materials is also discussed. It is concluded that thermally sprayed aluminum can provide effective long-term protection against corrosion, thereby obviating the need for chipping of rust and repainting by ship personnel. Such coatings are providing excellent protection to below-deck components such as steam valves, but improvements are needed to realize the full potential of coatings for above-deck service. Several recommendations are made regarding processes, materials, and research and development aimed at upgrading further the performance of these coatings.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-170363 , NAS 1.26:170363 , AD-A125600 , NMAB-409
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  • 74
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    Elastomer toughened polyimide adhesives (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A rubber-toughened addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state, and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride was mixed, and utilizing solvent or mixture of solvents for the reaction.
    Keywords: NONMETALLIC MATERIALS
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  • 75
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    Double layered tailorable advanced blanket insulation (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An advanced flexible reusable surface insulation material for future space shuttle flights was investigated. A conventional fly shuttle loom with special modifications to weave an integral double layer triangular core fabric from quartz yarn was used. Two types of insulating material were inserted into the cells of the fabric, and a procedure to accomplish this was developed. The program is follow up of a program in which single layer rectangular cell core fabrics are woven and a single type of insulating material was inserted into the cells.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-166600 , NAS 1.26:166600
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  • 76
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    Absorbable-susceptor joining of ceramic surfaces (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An assembly of ceramic surfaces particularly refractory metal oxides and carbides, abutting a thin sheet of metal susceptor material are placed in a chamber of an enclosure containing inert gas. An RF coil is activated by power supply to melt the susceptor and adjacent zones of the ceramic. Reactive gas such as oxygen or a carbonizing gas is then fed to the chamber and reacts with the susceptor to form compounds which disperse and dissolve in the zones. On cooling, a strong joint is formed. The susceptor may contain inner perforations and outer perforations to aid in distribution of heat.
    Keywords: NONMETALLIC MATERIALS
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  • 77
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    Fracture behavior of the Space Shuttle thermal protection system (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Stable crack-growth and fracture-toughness experiments were conducted using precracked specimens machined from LI-900 reusable surface insulation (RSI) tiles of the Space Shuttle thermal protection system (TPS) at room temperature. Similar fracture experiments were conducted on fracture specimens with preexisting cracks at the interface of the tile and the strain isolation pad (SIP). Stable crack growth was not observed in the LI-900 tile fracture specimens which had a fracture toughness of 12.0 kPa sq rt of m. The intermittent subcritical crack growth at the tile-pad interface of the fracture specimens was attributed to successive local pull-outs due to tensile overload in the LI-900 tile and cannot be characterized by linear elastic fracture mechanics. No subcritical interfacial crack growth was observed in the fracture specimens with densified LI-900 tiles where brittle fracture initiated at an interior point away from the densification.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society, Journal (ISSN 0002-7820); 66; Sept
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  • 78
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    Propagation of crazing in viscoelastic media (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The way in which the craze growth behavior is affected by the craze density surrounding the craze is investigated. The craze density is defined as the total number of crazes per unit surface area. It is noted that heretofore the growth rate of a craze has been considered either constant or inversely proportional to time. By allowing for the effect of the surrounding population of crazes, it is found that the craze growth rate is influenced by the local effective stress acting in the vicinity of the craze. It is found that measured data of craze length as a function of time are greatly affected by local interactions. With regard to the craze number, it is found that at high stresses a large number of small crazes becomes visible after a relatively short time, whereas under small stresses a large number of large crazes becomes visible after a long loading time.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Applied Physics (ISSN 0021-8979); 54; Oct. 198
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  • 79
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    Siloxanes, silanes, and silazanes in the preparation of ceramics and glasses (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The use of selected organosilicon compounds for the preparation of silicon based ceramic materials is discussed in terms of processing microstructure-property relationships. The mechanisms operative in the formation of gel derived silicate glasses and glass ceramics are reasonably well understood, but this is not true for silicon carbide/nitride based ceramics. The properties of organosilicon precursors and the mechanism of pyrolysis affect the microstructural features of the ceramic. Reaction mechanisms are proposed and the microstructural features and properties of organosilazane derived ceramics discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: ACS PAPER 17-B-81 , (ISSN 0002-7812)
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  • 80
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    Laboratory degradation of Kapton in a low energy oxygen ion beam (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An atomic oxygen ion beam, accelerated from a tunable microwave resonant cavity, was used at Lewis Research Center to bombard samples of the widely used polyimide Kapton. The Kapton experienced degradation and mass loss at high rates, which may be comparable to those found in Space Shuttle operations if the activation energy supplied by the beam enabled surface reactions with the ambient oxygen. The simulation reproduced the directionality (ram-wake dependence) of the degradiation, the change in optical properties of the degraded materials, and the structure seen in scanning electron micrographs of samples returned on the Shuttle Trails with a substituted argon ion beam produced no rapid degradation. Energy Dispersive X-ray Analysis (EDAX) showed significant surface composition changes in all bombarded samples. Mass loss rates and surface composition changes are discussed in terms of the possible oxidation chemistry of the interaction. Finally, the question of how the harmful degradation of materials in low earth orbit can be minimized is addressed.
    Keywords: NONMETALLIC MATERIALS
    Type: AIAA PAPER 83-2658
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  • 81
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    Polycrystalline silicon material availability and market pricing outlook study for 1980 to 88: January 1983 update (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Photovoltaic solar cell arrays which convert solar energy into electrical energy can become a cost effective, alternative energy source provided that an adequate supply of low priced materials and automated fabrication techniques are available. Presently, silicon is the most promising cell material for achieving the near term cost goals of the Photovoltaics Program. Electronic grade silicon is produced primarily for the semiconductor industry with the photovoltaic industry using, in most cases, the production rejects of slightly lower grade material. Therefore, the future availability of adequate supplies of low cost silicon is one of the major concerns of the Photovoltaic Program. The supply outlook for silicon with emphasis on pricing is updated and is based primarily on an industry survey conducted by a JPL consultant. This survey included interviews with polycrystalline silicon manufacturers, a large cross section of silicon users and silicon solar cell manufacturers.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-173123 , DOE/JPL-1012-79A , JPL-PUB-83-9 , JPL-5230-10 , NAS 1.26:173123
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  • 82
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    Sintering of reaction bonded silicon nitride (1983)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: A process to produce sintered reaction-bonded Si3N4 (SRBSN) articles has been developed. This process consists of the addition of an appropriate sintering aid to reaction-bonded Si3N4 followed by sintering between 1780 and 2000 C, using an over pressure of nitrogen. The principal advantage of this process is the low sintering shrinkages of 5 to 10 percent. The properties and microstructure of two SRBSN systems sintered with MgO and Y2O3 additives are described and were found to be comparable to corresponding hot-pressed Si3N4 systems. Examples of applications of both systems are illustrated, demonstrating near net shape fabrication capability of the process.
    Keywords: NONMETALLIC MATERIALS
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  • 83
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    Polymers in solar energy utilization (1983)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: A laser photoacoustic technique (LPAT) has been verified for performing accelerated life testing of outdoor photooxidation of polymeric materials used in solar energy applications. Samples of the material under test are placed in a chamber with a sensitive microphone, then exposed to chopped laser radiation. The sample absorbs the light and converts it to heat by a nonradiative deexcitation process, thereby reducing pressure fluctuations within the cell. The acoustic signal detected by the microphone is directly proportional to the amount of light absorbed by the specimen. Tests were performed with samples of ethylene/methylacrylate copolymer (EMA) reprecipitated from hot cyclohexane, compressed, and molded into thin (25-50 microns) films. The films were exposed outdoors and sampled by LPAT weekly. The linearity of the light absorbed with respect to the acoustic signal was verified.Correlations were established between the photoacoustic behavior of the materials aged outdoors and the same kinds of samples cooled and heated in a controlled environment reactor. The reactor tests were validated for predicting outdoor exosures up to 55 days.
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  • 84
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    The effect of silicon particle size on the nitriding behaviour of reaction bonded Si3N4 compacts (1983)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Keywords: NONMETALLIC MATERIALS
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  • 85
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    NMR (Nuclear Magnetic Resonance) and macromolecular migration in a melt or in concentrated solutions (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The purpose of this paper is to analyze the migration process of long polymer molecules in a melt or in concentrated solutions as it may be observed from the dynamics of the transverse magnetization of nuclear spins linked to these chains. The low frequency viscoelastic relaxation of polymer systems is known to be mainly controlled by the mechanism of dissociation of topological constraints excited on chains and which are called entanglements. This mechanism exhibits a strong dependence upon the chain molecular weight. These topological constraints also govern the diffusion process of polymer chains. So, the accurate description of the diffusion motion of a chain may be a convenient way to characterize disentanglement processes necessarily involved in any model proposed to explain viscoelastic effects.
    Keywords: NONMETALLIC MATERIALS
    Type: AD-P003908 , Trinity Coll. Nucl. Magnetic Resonance of Polymeric Mater.; 22 p
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  • 86
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    NMR (Nuclear Magnetic Resonance) of solid biopolymers (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: It has been possible through the study of proton relaxation in solid proteins and related molecules to identify and characterize the following molecular motions which contribute to relaxation: (1) methyl group reorientation; (2) segmental motion; (3) side chain motion; (4) proline ring puckering; and (5) water molecule reorientation.
    Keywords: NONMETALLIC MATERIALS
    Type: AD-P003912 , Trinity Coll. Nucl. Magnetic Resonance of Polymeric Mater.; 10 p
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  • 87
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    Thermoelectric properties of non-stoichiometric lanthanum sulfides (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The lanthanum sulfides are promising candidate materials for high-efficiency thermoelectric applications at temperatures up to 1300 C. The non-stoichiometric lanthanum sulfides (LaS(x), where x is in the range 1.33-1.50) appear to possess the most favorable thermoelectric properties. The Seebeck coefficient and resistivity vary significantly with composition, so that an optimum value of alpha sq/rho (where alpha is the Seebeck coefficient and rho is the resistivity) can be chosen. The thermal conductivity remains approximately constant with stoichiometry, so a material with an optimum value of alpha sq/rho should possess the optimum figure-of-merit. Data for the Seebeck coefficient and electrical resistivity of non-stoichiometric lanthanum sulfides will be pressed, together with structural properties of these materials.
    Keywords: NONMETALLIC MATERIALS
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  • 88
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    Present state of boron-carbon thermoelectric materials (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Boron-carbon p-type thermoelectric materials show promise for use in advanced thermal-to-electric space power conversion systems. Here, recent data on the thermoelectric properties of boron-carbon materials, such as B9C, B13C2, B15C2, and B4C, are reviewed. In particular, attention is given to the effect of the compositional homogeneity and residual impurity content on the Seeback coefficient, electrical resistivity, and thermal conductivity of these materials. The effect of carbon content for a given level of impurity and degree of homogeneity is also discussed.
    Keywords: NONMETALLIC MATERIALS
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  • 89
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    Variation in radical decay rates in epoxy as a function of crosslink density (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A study was made of the behavior of radicals generated by Co-60 gamma radiation in the epoxy system tetraglycidyl-4,4'-diaminodiphenyl methane (TGDDM) cured with 4,4'-diaminodiphenyl sulfone (DDS). The molar ratio of TGDDM to DDS was varied in the epoxy samples, and they were prepared under the same curing conditions to obtain various extents of crosslinking. ESR spectrometry data suggest that the rate of decay of radicals is related to inhomogeneities in the resin, with radicals in the highly crosslinked regions having long decay times. The inhomogeneities are thought to be due to statistical variation associated with the complex crosslinking reactions or to difficulties in mixing the reactants.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Applied Polymer Science (ISSN 0021-8995); 28; 3301-330
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  • 90
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    Liquid chromatographic analysis of a formulated ester from a gas-turbine engine test (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Size exclusion chromatography (SEC) utilizing mu-Bondagel and mu-Styragel columns with a tetrahydrofuran mobile phase was used to determine the chemical degradation of lubricant samples from a gas-turbine engine test. A MIL-L-27502 candidate, ester-based lubricant was run in a J57-29 engine at a bulk oil temperature of 216 C. In general, the analyses indicated a progressive loss of primary ester, additive depletion, and formation of higher molecular weight material. An oil sample taken at the conclusion of the test showed a reversal of this trend because of large additions of new oil. The high-molecular-weight product from the degraded ester absorbed strongly in the ultraviolet region at 254 nanometers. This would indicate the presence of chromophoric groups. An analysis of a similar ester lubricant from a separate high-temperature bearing test yielded qualitatively similar results.
    Keywords: NONMETALLIC MATERIALS
    Type: ASLE PREPRINT 83-LC-1A-1
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  • 91
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    New black paint for cryogenic infrared applications (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A black paint has been developed and tested for cryogenic applications involving wavelengths beyond 10 microns. The paint has been used extensively for liquid helium cooled applications in a variety of instruments operating between 10 and 120 microns. The material is applied by brush over a spray or brush applied primer coat. A final covering is applied by either brush or spray. The composition and preparation of the paint are described, as are data about its outgassing properties. Infrared reflection and scattering data obtained by other groups which compare this material to other commercially available surface preparations are presented.
    Keywords: NONMETALLIC MATERIALS
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  • 92
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    Unknown
    Evaluation of spacecraft materials and processes for optical degradation potential (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A Wide Field Planetary Camera instrument with wide wavelength sensitive Charged Coupled Device detectors has been designed and built for employment in space. The contamination potential of the spacecraft hardware is determined by the outgassing characteristics of the selected materials and the effect of the performed processing procedures. An investigation was conducted to provide for more selective material screening with respect to contamination potential and to develop an optical effects data base. In the investigation, a series of thermogravimetric, residual gas, Micro-Volatile Condensible Material (VCM), and Vacuum Optical Degradation tests were performed. The results of the Micro-VCM testing of four epoxy adhesive systems are presented in tables.
    Keywords: NONMETALLIC MATERIALS
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  • 93
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    Dynamic fracture toughness of glass (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Experimentally determined dynamic crack propagation histories in wedge-loaded, modified tapered, and rectangular double cantilever beam specimens were used to drive a dynamic finite element code in its generation phase. The resultant dynamic fracture toughness versus crack velocity relation, during the initial crack acceleration phase of these dynamic fracture specimens, was erratic but followed the standard Gamma-shaped curves of brittle polymers and metals during subsequent crack propagation at terminal velocity and crack deceleration phases. The distinct initiation phase of dynamic crack propagation, which was not observed in dynamic fracture of brittle polymer and metal specimens, is attributed to the lower stored energy in the glass specimen.
    Keywords: NONMETALLIC MATERIALS
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  • 94
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    Thermal stress fracture of ceramic coatings (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Thermal stress failures of ceramic coatings are discussed in terms of fracture mechanics concepts. The effects of transient and residual stresses on single and multiple cycle failure mechanisms are considered. A specific example of a zirconia thermal barrier coating is presented and its endurance calculated using the proposed relationships.
    Keywords: NONMETALLIC MATERIALS
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  • 95
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    Compositional effects on Si3N4 fracture surfaces (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Surface analysis techniques (X-ray, infrared reflection spectroscopy, Auger electron spectroscopy) applied to the same samples reveal that fracture surfaces of Si3N4 with Y2O3 densification aids possess a higher concentration of oxygen than the bulk. The oxide densification aids thus concentrate in the grain boundaries, and even low-temperature fracture is seen as occurring preferentially within the oxygen-enriched grain boundaries. It is found that increasing the concentrations of Y2O3 and Al2O3 increases the oxygen content of the fracture surface. A range of 13-15 percent Y2O3 + 6 percent Al2O3 gives an amorphous grain-boundary phase that is resistant to devitrification. Fracture occurs through the amorphous phase, and heat treatment at 1000 C has little effect on the amorphous phase.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 907-917
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  • 96
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    Grain-boundary phases in hot-pressed silicon nitride containing Y2O3 and CeO2 additives (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Auger electron spectroscopy in conjunction with X-ray powder diffraction and scanning electron microscopy is used to analyze the grain-boundary phases of Y2O3- and CeO2-doped Si3N4 hot-pressed materials in order to demonstrate that the additives concentrate predominantly in the grain boundaries of Si3N4 in the form of various oxynitride phases. A high oxygen content observed in sample fracture surfaces was found to be consistent with the existence of an oxygen-enriched phase in the grain boundaries. The presence of yttrium and cerium in the fracture surfaces and an overall increase in the O/N ratio imply that the additive oxides are predominantly concentrated in the intergranular phases.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 901-906
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  • 97
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    Mechanical and physical properties of plasma-sprayed stabilized zirconia (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Physical and mechanical properties were determined for plasma-sprayed MgO- or Y2O3-stabilized ZrO2 thermal barrier coatings. Properties were determined for the ceramic coating in both the freestanding condition and as-bonded to a metal substrate. The properties of the NiCrAlY bond coating were also investigated.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 828-840
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  • 98
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    Analysis of grain boundary phase devitrification of Y2O3- and Al2O3-doped Si3N4 (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The present study has the objective to show that a Fourier Transform IR (FTIR) spectrometer in a single-beam reflection mode can be used for direct comparison of fractured vs nonfractured Si3N4 surfaces. This can be done because the FTIR method permits a digital summation of nearly 1000 scans of the fracture surface. Commercial-grade Si3N4, Y2O3, and Al2O3 were used in the study. The samples were heat treated in a vacuum induction heating furnace at either 1000 C for 10 h or 1200 C for 10 h each. Use of Fourier transform IR reflection spectroscopic analysis and X-ray diffraction shows that 10 h at 1200 C is sufficient to devitrify the amorphous grain boundary phase of Si3N4 containing 15 percent Y2O3 + 2 percent Al2O3 densification aids.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 896-898
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  • 99
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    Anisotropic thermal expansion effects in plasma-sprayed ZrO2-8 percent Y2O3 coatings (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The thermal expansion properties of plasma-sprayed ZrO2-8-wt pct Y2O3 coatings, detached from the substrate, have been examined. Coatings were heat-treated in air or in argon. Anisotropic effects in the longitudinal (planar to the substrate surface) and transverse (perpendicular to the substrate surface) directions were measured and related to the coating structure. The thermal expansion coefficient of the coating is discussed in terms of the material's properties, such as the crack network and interlamellar boundary distribution. A precise model for the expansion behavior of coatings still needs attention, since no description of all of the contributing variables exists. A quantitative analysis of thermal properties of coatings will aid in future design and modeling of coating systems.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 792-801
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  • 100
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    Phase analysis of plasma-sprayed zirconia-yttria coatings (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Phase analysis of plasma-sprayed 8 wt pct-yttria-stabilized zirconia (YSZ) thermal barrier coatings and powders was carried out by X-ray diffraction. Step scanning was used for increased peak resolution. Plasma spraying of the YSZ powder into water or onto a steel substrate to form a coating reduced the cubic and monoclinic phases with a simultaneous increase in the tetragonal phase. Heat treatment of the coating at 1150 C for 10 h in an Ar atmosphere increased the amount of cubic and monoclinic phases. The implications of these transformations on coating performance and integrity are discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 784-787
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