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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1921

Moisture Resistant Finishes for Airplane Woods

This report describes briefly a series of experiments made at the Forest Products Laboratory, Madison, Wisconsin, to determine the comparative moisture resistance of linseed oil, impregnation treatments, condensation varnishes, oil varnishes, enamels, cellulose varnishes, rubber, electroplated and sprayed metal coatings, and metal-leaf coatings when applied to wood. All coatings except rubber and electroplated metal coatings, which were not developed sufficiently to make them practical, admitted moisture in varying degrees. The most effective and most practical coating was found to be that of aluminum leaf.

Dunlap, M E↗
NASA NTRS1996

Geomorphic Processes and Remote Sensing Signatures of Alluvial Fans in the Kun Lun Mountains, China

The timing of alluvial deposition in arid and semiarid areas is tied to land-surface instability caused by regional climate changes. The distribution pattern of dated deposits provides maps of regional land-surface response to past climate change. Sensitivity to differences in surface roughness and composition makes remote sensing techniques useful for regional mapping of alluvial deposits. Radar images from the Spaceborne Radar Laboratory and visible wavelength images from the French SPOT satellite were used to determine remote sensing signatures of alluvial fan units for an area in the Kun Lun Mountains of northwestern China. These data were combined with field observations to compare surface processes and their effects on remote sensing signatures in northwestern China and the southwestern United States. Geomorphic processes affecting alluvial fans in the two areas include aeolian deposition, desert varnish, and fluvial dissection. However, salt weathering is a much more important process in the Kun Lun than in the southwestern United States. This slows the formation of desert varnish and prevents desert pavement from forming. Thus the Kun Lun signatures are characteristic of the dominance of salt weathering, while signatures from the southwestern United States are characteristic of the dominance of desert varnish and pavement processes. Remote sensing signatures are consistent enough in these two regions to be used for mapping fan units over large areas.

Farr, Tom G.↗
NASA NTRS1999

Atomic Oxygen Treatment as a Method of Recovering Smoke Damaged Paintings

A noncontact technique is described that uses atomic oxygen, generated under low pressure in the presence of nitrogen, to remove soot and charred varnish from the surface of a painting. The process, which involves surface oxidation, permits control of the amount of surface material removed. The effectiveness of the process was evaluated by reflectance measurements from selected areas made during the removal of soot from acrylic gesso, ink on paper, and varnished oil paint substrates. For the latter substrate, treatment also involved the removal of damaged varnish and paint binder from the surface.

Rutledge, Sharon K.↗
NASA NTRS1973

A study to explore the use of orbital remote sensing to determine native arid plant distribution

The author has identified the following significant results. Ground truth spectral signature data for various types of scenes, including ground with and without annuals, and various shrubs, were collected. When these signature data are plotted with infrared (MSS band 6 or 7) reflectivity on one axis and red (MSS band 5) reflectivity on the other axis, clusters of data from the various types of scenes are distinct. This method of expressing spectral signature data appears to be more useful for distinguishing types of scenes than a simple infrared to red reflectivity ration. Large areas of varnished desert pavement are visible and mappable on ERTS-1 and high altitude aircraft imagery. A large scale vegetation pattern was found to be correlated with the presence of the desert pavement. The large scale correlation was used in mapping the vegetation of the area. It was found that a distinctive soil type was associated with the presence of the varnished desert pavement. The high salinity and exchangeable sodium percentage of this soil type provide a basis for the explanation of both the large scale and small scale vegetation pattern.

Mcginnies, W. G.↗
NASA NTRS1980

Accelerated Alpha-s deterioration in a geostationary orbit

Between the Teflon substrate and the interference filter a 2 micron varnish layer was sandwiched in. The bending radius of the SSM, measured on a cone, decreased from about 13 mm to 6 mm prior to interference filter fracture, due to increased tensile strength of its substrate. These samples, and for comparison samples of the same make but without varnish and a conductive layer were included in the test. Additionally 2 Teflon FEP samples without the protective interference filter, one of them with a conductive layer, were tested. The sample substrate was 125 micron Teflon FEP, with vapor deposited silver reflector and a thin Inconel film for corrosion protection.

Husmann, O. K.↗
NASA NTRS1987

Nature and origin of mineral coatings on volcanic rocks of the Black Mountain, Stonewall Mountain and Kane Springs wash volcanic centers, southern Nevada

Mineral coatings, including desert varnish on volcanic rocks of the semi-arid Basin and Range province are composted of amorphous, translucent films of Fe, Mn, Si, and Al rich compounds. Coatings are chiefly thin films that impregnate intergranularly to depths of about 0.1 to 0.3 mm, rarely deeper. Sixteen coating sections and subsurface interiors were probed by SEM; 20 samples were scanned by infrated spectrometry; 10 samples were scanned for visible-near IR spectra; inductin coupling plasma analyses were collected on 34 samples; 2 desert varnish surgaces were investigated by optical density slice imagery; a few XRD analyses were conducted in addition to the 50 reported in the last period; thin section observation continued; and imagery processing focused on classification techniques. In late May, approximately 10 field days were spent at the Stonewall and Black Mountain study sited conducting more detailed mapping and observation base on imagery results and collecting spectra with the Collins Field Spectrometer. Approximately 100 spectral analyses were collected and are currently being processed.

Taranik, James V.↗
NASA NTRS1989

Nature and origin of secondary mineral coatings on volcanic rocks of the Black Mountain, Stonewall Mountain, and Kane Springs Wash volcanic centers, southern, Nevada

The following subject areas are covered: (1) genetic, spectral, and LANDSAT Thematic Mapper imagery relationship between desert varnish and tertiary volcanic host rocks, southern Nevada; (2) reconnaissance geologic mapping of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada, using multispectral thermal infrared imagery; (3) interregional comparisons of desert varnish; and (4) airborne scanner (GERIS) imagery of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada.

Taranik, James V.↗
NASA NTRS1999

Recovery of a Charred Painting Using Atomic Oxygen Treatment

A noncontact method is described which uses atomic oxygen to remove soot and char from the surface of a painting. The atomic oxygen was generated by the dissociation of oxygen in low pressure air using radio frequency energy. The treatment, which is an oxidation process, allows control of the amount of material to be removed. The effectiveness of char removal from half of a fire-damaged oil painting was studied using reflected light measurements from selected areas of the painting and by visual and photographic observation. The atomic oxygen was able to effectively remove char and soot from the treated half of the painting. The remaining loosely bound pigment was lightly sprayed with a mist to replace the binder and then varnish was reapplied. Caution should he used when treating an untested paint medium using atomic oxygen. A representative edge or corner should he tested first in order to determine if the process would be safe for the pigments present. As more testing occurs, a greater knowledge base will be developed as to what types of paints and varnishes can or cannot be treated using this technique. With the proper precautions, atomic oxygen treatment does appear to be a technique with great potential for allowing very charred, previously unrestorable art to be salvaged.

Rutledge, Sharon K.↗
NASA NTRS1960

DETERMINATION OF EMISSIVITY OF MATERIALS.

During the third quarter of the contractual year of Contract NASW-104 for the determination of emissivity of materials, the emittance of nine specimens was measured at temperatures ranging up to 2200F and at pressures averaging 10(exp -8) mm Hg. The materials tested included columbium, columbium with an oxidized surface, molybdenum, graphite varnish on Type 310 stainless steel, stainless steel with an oxidized surface, and platinum black. In the spectral emittance rig, spectral as well as total emittance was measured on three specimens and total emittance only was measured on a fourth. In the total emittance rig, total emittance data was obtained on five specimens. Two of the specimens were endured. Investigations were made concerning the operational characteristics of both rigs in order to eliminate possible sources of error in the data. On the spectral emittance rig, tests were conducted to determine the exact magnitude of any error introduced in the spectral emittance values by beam intermixing resulting from imperfections in the optical system. On the total emittance rig, work was concentrated on the determination of the relative accuracy of the chromel-alumel and platinum-platinum 10% rhodium thermocouples used to measure the temperature of the specimen.

Emission↗
NASA NTRS1972

Lubricating characteristics of polyimide bonded graphite fluoride and polyimide thin films

A friction and wear life study was conducted on the use of a polyimide (PI) varnish as a binder for the solid lubricant, graphite fluoride (CF(1.1))N. Also studied were the lubricating properties of PI thin films with no solid lubricant additives. For comparison, similar experiments on PI-bonded MoS2 and burnished films of MoS2 or (CF(li))N were conducted. The best results were obtained with the PI-bonded (CF(1.1))N films. The polyimide thin films (with no solid lubricant additives) did not lubricate well at 25 C; however, when heated to 100 C, low friction and long wear lives were obtained.

Fusaro, R. L.↗
NASA NTRS1972

Lubricating characteristics of polyimide bonded graphite fluoride and polyimide thin films.

A friction and wear life study was conducted on the use of a polyimide (PI) varnish as a binder for the solid lubricant, graphite fluoride (CF sub 1.1) sub n. Also studied were the lubricating properties of PI thin films with no solid lubricant additives. For comparison, similar experiments on PI-bonded MoS2 and burnished films of MoS2 or (CF sub 1.1) sub n were conducted. The best results were obtained with the PI-bonded (CF sub 1.1) sub n films. The polyimide thin films (with no solid lubricant additives) did not lubricate well at 25 C; however, when heated to 100 C, low friction and long wear lives were obtained.

Fusaro, R. L.↗
NASA NTRS1974

Resin/graphite fiber composites

Techniques were developed that provided thermo-oxidatively stable A-type polyimide/graphite fiber composites using the approach of in situ polymerization of monomeric reactants directly on reinforcing fibers, rather than employing separately prepared prepolymer varnish. This was accomplished by simply mixing methylene dianiline and two ester-acids and applying this solution to the fibers for subsequent molding. Five different formulated molecular weight resins were examined, and an optimized die molding procedure established for the 1500 formulated molecular weight system. Extensive ultrasonic inspection of composites was successfully utilized as a technique for monitoring laminate quality. Composite mechanical property studies were conducted with this polyimide resin at room temperature and after various time exposures in a thermo-oxidative environment at 561 K (550 F), 589 K (600 F) and 617 K (650 F). It was determined that such composites have a long term life in the temperature range of 561 K to 589 K. The final phase involved the fabrication and evaluation of a series of demonstration airfoil specimens.

Cavano, P. J.↗
NASA NTRS1974

Polyimide resin composites via in situ polymerization of monomeric reactants

Thermo-oxidatively stable polyimide/graphite-fiber composites were prepared using a unique in situ polymerization of monomeric reactants directly on reinforcing fibers. This was accomplished by using an aromatic diamine and two ester-acids in a methyl alcohol solvent, rather than a previously synthesized prepolymer varnish, as with other A-type polyimides. A die molding procedure was developed and a composite property characterization conducted with high modulus graphite fiber tow. Flexure, tensile, compressive, and shear tests were conducted at temperatures from 72 to 650 F on laminates before and after exposures at the given temperatures in an air environment for times up to 1000 hours. The composite material was determined to be oxidatively, thermally, and hydrolytically stable.

Cavano, P. J.↗
NASA NTRS1974

Development of autoclavable polyimides

A poly(Diels-Alder) (PDA) resin approach was investigated as a means to achieve autoclavability of high temperature resistant resin/fiber composites under mild fabrication procedures. Low void content Type A-S graphite reinforced composites were autoclave fabricated from a PDA resin/fiber prepared from an acetone:methanol:dioxane varnish. Autoclave conditions were 477K (400F) and 0.7 MN/sq m (100 psi) for up to two hours duration. After postcure at temperatures up to 589K (600F), the composites demonstrated high initial mechanical properties at temperatures up to 561K (550F). The results from isothermal aging studies in air for 1000 hours indicated potential for long-term ( 1000 hours) use at 533K (500F) and shorter-term (up to 1000 hours) at 561K (550F).

Orell, M. K.↗
NASA NTRS1974

Resin/graphite fiber composites

Processing techniques were developed for the fabrication of both polyphenylquinoxaline and polyimide composites by the in situ polymerization of monomeric reactants directly on the graphite reinforcing fibers, rather than using previously prepared prepolymer varnishes. Void-free polyphenylquinoxaline composites were fabricated and evaluated for room and elevated flexure and shear properties. The technology of the polyimide system was advanced to the point where the material is ready for commercial exploitation. A reproducible processing cycle free of operator judgment factors was developed for fabrication of void-free composites exhibiting excellent mechanical properties and a long time isothermal life in the range of 288 C to 316 C. The effects of monomer reactant stoichiometry and process modification on resin flow were investigated. Demonstration of the utility and quality of this polyimide system was provided through the successful fabrication and evaluation of four complex high tip speed fan blades.

Cavano, P. J.↗
NASA NTRS1974

Imparting strength and toughness to brittle composites

Appropriate intermittent coatings of fibers can produce areas of low and high toughness in brittle composites. Experiments using silicon vacuum grease (SVG) and polyurethane varnish (PUV) coatings that achieve weakly and strongly bonded interfaces are described. Tensile strength and edge-crack fracture toughness for both SVG and PUV coatings were plotted against the percentage coating (C). Both coating materials maintain tensile strengths in the order of the rule of mixture strength values up to a large C. It is suggested that both materials produce similar coated interfacial shear strengths while producing different effects on toughness.

Atkins, A. G.↗