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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

The nature of surfaces and their influence in wear mechanisms

The wear of materials is strongly dependent upon the nature of the solid surfaces in contact, their properties and the nature of the films on them. Oxide films, orientation, crystal transformations, adhesive binding, crystal structure, hardness and the presence of alloying agents are all shown to effect one or more of the forms of wear. The three most common forms of wear, adhesive, abrasive, and corrosive, are discussed in terms of the way each is affected by various material properties. Results presented indicate how wear can be optimized by concern for properties of materials.

Buckley, D. H.↗
NASA NTRS1978

Boron trifluoride coatings for plastics

Tough, durable coatings of boron triflouride can be deposited on plastic optical components to protect them from destructive effects of abrasion, scratching, and environment. Coating material can be applied simultaneously with organic polymers, using plasma glow-discharge methods, or it can be used as base material for other coatings to increase adhesion.

Kubacki, R. M.↗
NASA NTRS1978

Protective coating for laser diodes

Coating for GaAs laser diodes should not alter optical and electrical properties. Borosilicate glass coating is easy to apply, breaks evenly when cleaved, and is abrasion and moisture resistant. Its low index of refraction makes thickness less critical when depositing half-wavelength coating.

Ladany, I.↗
NASA NTRS1978

Special weave for insulating fabrics

Special weave forms tight fabric for high-alumina-content alumina/boria/silica fibers, without leading to expensive filament fracture during weaving process. Resultant abrasion-resistant material is superior to conventional insulating materials at elevated temperatures.

Frye, J. A.↗
NASA NTRS1977

Large area Czochralski silicon

The overall cost effectiveness of the Czochralski process for producing large-area silicon was determined. The feasibility of growing several 12 cm diameter crystals sequentially at 12 cm/h during a furnace run and the subsequent slicing of the ingot using a multiblade slurry saw were investigated. The goal of the wafering process was a slice thickness of 0.25 mm with minimal kerf. A slice + kerf of 0.56 mm was achieved on 12 cm crystal using both 400 grit B4C and SiC abrasive slurries. Crystal growth experiments were performed at 12 cm diameter in a commercially available puller with both 10 and 12 kg melts. Several modifications to the puller hoz zone were required to achieve stable crystal growth over the entire crystal length and to prevent crystallinity loss a few centimeters down the crystal. The maximum practical growth rate for 12 cm crystal in this puller design was 10 cm/h, with 12 to 14 cm/h being the absolute maximum range at which melt freeze occurred.

Rea, S. N.↗
NASA NTRS1978

High temperature resistant cermet and ceramic compositions

High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.

Phillips, W. M.↗
NASA NTRS1977

Summary report of the Aircraft Design Committee

Meetings were held concerning aircraft design with considerable interest shown in aircraft operations. Topics covered were: (1) structural design for turbulence; (2) flight control; (3) data needs; and (4) lightning. Other factors discussed were temperature, rain, hail, icing, pressure, density, corrosives, and abrasives.

Woodcock, R. J.↗
NASA NTRS1978

Wide temperature range fiber optic cable: Cable design study

Factors considered in the design and fabrication of a single fiber optic cable intended for spacecraft applications in an environment of temperature extremes from -160 C to 125 C include: abrasion resistance, low temperature flexibility, small size, low weight, and overall temperature stability. Specific requirements were identified for fiber core and overall diameters, fiber loss and NA, and cable tensile load. The single fiber cable will be fabricated by using a chemical vapor step index fiber of .125 mm coated to .3 mm with RTV silicone and then extruded with a jacket of Teflon PFA to a diameter of .5 mm. Six yarns of 1420 denier unimpregnated Kevlar 49 with a helical lay of 1.3 inches will surround the jacketed fiber under an extrusion of PFA. The finished cable diameter will measure 1.8 mm, and the weight of one kilometer length will be approximately 4350grams.

Speed, E. U.↗
NASA NTRS1977

Impact cratering and regolith dynamics

The most recent models concerning mechanical aspects of lunar regolith dynamics related to impact cratering use probabilistic approaches to account for the randomness of the meteorite environment in both space and time. Accordingly the absolute regolith thickness is strictly a function of total bombardment intensity and absolute regolith growth rate in nonlinear through geologic time. Regoliths of increasing median thickness will have larger and larger proportions of more and more deep seated materials. An especially active zone of reworking on the lunar surface of about 1 mm depth has been established. With increasing depth, the probability of excavation and regolith turnover decreases very rapidly. Thus small scale stratigraphy - observable in lunar core materials - is perfectly compatible with regolith gardening, though it is also demonstrated that any such stratigraphy does not necessarily present a complete record of the regolith's depositional history. At present, the lifetimes of exposed lunar rocks against comminution by impact processes can be modeled; it appears that catastrophic rupture dominates over single particle abrasion.

Hoerz, F.↗
NASA NTRS1978

Wear of steel by rubber

Wear of a steel blade used as a scraper to abrade rubber surfaces has been found to take place much more rapidly on a cis-polyisoprene (natural rubber) surface than on a cis-polybutadiene surface, and much more rapidly in an inert atmosphere than in air. These observations are attributed to the direct attack upon steel of free-radical species generated by mechanical rupture of elastomer molecules during abrasion.

Gent, A. N.↗
NASA NTRS1980

Recirculating sprayer for fiber-filled paints

Recirculating paint sprayer applies spray of coarse filler in highly volatile solvent. Sprayer was developed for applying insulation material containing epxoy resin, glass fibers, and inert fillers suspended in chlorinated solvents. Sprayer resists abrasive action of fiberglass filler and chemical activity of solvent. Pump and position ensure more uniform pressure at spray gun without backpressure regulator, which tended to clog in old sprayer.

Major, R. K.↗
NASA NTRS1978

Development of aircraft lavatory compartments with improved fire resistance characteristics

The Boeing's participation in a NASA-funded program (FIREMEN) included developing materials for use as lavatory wall panels, sidewall panels, and ceiling panels possessing flammability, smoke, and toxicity (FS&T) characteristics superior to current materials of construction is described. A sandwich panel system is developed for improving FS&T characteristics and acceptable cost, processing requirements, aesthetic qualities, abrasion resistance, strain resistance, scuff resistance, and washability.

Anderson, R. A.↗
NASA NTRS1978

High temperature resistant cermet and ceramic compositions

Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

Phillips, W. M.↗
NASA NTRS1978

Testing and environmental exposure of parachute materials for the solid rocket booster decelerator subsystem

Static tests and evaluation of nonmetallic materials for use in parachutes for recovery of solid rocket boosters used in the space shuttle program are reported. Literature survey and manufacturer and vendor contacts led to the choice of nylon as the fabric most capable of withstanding the extreme loads and environmental conditions during repeated use. The material tests included rupture strength, elongation, abrasion resistance, shrinkage, environmental exposure, and degradation levels. Rinsing and drying procedures were also investigated and a salt-free level for nylon recommended in preparation for reuse. In all possible cases, worst-case conditions were used (e.g., inflation loads, seawater exposure for 3 days per drop-recovery, etc.).

Tannehill, B. K.↗
NASA NTRS1978

Engineering handbook on the atmospheric environmental guidelines for use in wind turbine generator development

The guidelines are given in the form of design criteria relative to wind speed, wind shear, turbulence, wind direction, ice and snow loading, and other climatological parameters which include rain, hail, thermal effects, abrasive and corrosive effects, and humidity. This report is a presentation of design criteria in an engineering format which can be directly input to wind turbine generator design computations. Guidelines are also provided for developing specialized wind turbine generators or for designing wind turbine generators which are to be used in a special region of the United States.

Frost, W.↗
NASA NTRS1979

Composite seal for turbomachinery

A gas path seal suitable for use with a turbine engine or compressor is provided. A shroud wearable or abradable by the abrasion of the rotor blades of the turbine or compressor protects the rotor blades. A compliant backing surrounds the shroud. The backing may be made of corrugated sheets or the like with adjacent layers having off-set corrugations, with axes of the folds parallel to the rotor axis. The sheets may be bonded together at points of contact by brazing, welding or the like. In another embodiment a compliant material is covered with a thin ductile layer. A mounting fixture surrounds the backing.

Bill, R. C.↗