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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Tailored plasma sprayed MCrAlY coatings for aircraft gas turbine applications

Eighteen plasma sprayed coating systems, nine based on the NiCoCrAly chemistry and nine based on the CoCrAly composition, were evaluated to identify coating systems which provide equivalent or superior life to that shown by the electron beam physical vapor deposited NiCoCrAly and CoCrAly coatings respectively. NiCoCrAly type coatings were examined on a single crystal alloy and the CoCrAly based coatings were optimized on the B1900+ Hf alloy. Cyclic burner rig oxidation and hot corrosion and tensile ductility tests used to evaluate the various coating candidates. For the single crystal alloy, a low pressure chamber plasma sprayed NiCoCrAly + Si coating exhibited a 2x oxidation life improvement at 1394 K (2050 F) over the vapor deposited NiCoCrAly material while showing equivalent tensile ductility. A silicon modified low pressure chamber plasma sprayed CoCrAly coating was found to be more durable than the baseline vapor deposited CoCrAly coating on the B1900+ Hf alloy.

Pennisi, F. J.↗
NASA NTRS1981

Improved plasma sprayed MCrAlY coatings for aircraft gas turbine applications

Eighteen plasma sprayed coating systems, nine based on the NiCoCrAlY chemistry and nine based on the CoCrAlY composition, were evaluated to identify coating systems which will provide equivalent or superior life to that shown by the electron beam physical vapor deposited NiCoCrAlY and CoCrAlY coatings respectively. NiCoCrAlY-type coatings were examined on a single crystal alloy and the CoCrAlY based coatings were optimized on the B1900 + Hf alloy. Cyclic burner rig oxidation and hot corrosion and tensile ductility tests were used to evaluate the various coating candidates. For the single crystal alloy, a low pressure chamber plasma sprayed NiCoCrAlY + Si coating exhibited a 2X oxidation life improvement at 1121 C (2050 F) over the vapor deposited NiCoCrAlY material while showing equivalent tensile ductility. A silicon modified low pressure chamber plasma sprayed CoCrAlY coating was found to be more durable than the baseline vapor deposited CoCrAlY coating on the B1900 + Hf alloy.

Pennisi, F. J.↗
NASA NTRS2000

Chemical vapor deposition coating of fibers using microwave application

Chemical vapor deposition coating is carried out in a cylindrical cavity. The fibers are heated by a microwave source that is uses a TM0N0 mode, where O is an integer, and produces a field that depends substantially only on radius. The fibers are observed to determine their heating, and their position can be adjusted. Once the fibers are uniformly heated, a CVD reagent is added to process the fibers.

Barmatz, Martin B.↗
NASA NTRS1995

Organic matrix composite protective coatings for space applications

Successful use of composites in low earth orbit (LEO) depends on their ability to survive long-term exposure to atomic oxygen (AO), ultraviolet radiation, charged particle radiation, thermal cycling, and micrometeoroid and space debris. The AO environment is especially severe for unprotected organic matrix composites surfaces in LEO. Ram facing unprotected graphite/epoxy flown on the 69-month Long Duration Exposure Facility (LDEF) mission lost up to one ply of thickness (5 mils) resulting in decreased mechanical properties. The expected AO fluence of the 30 year Space Station Alpha mission is approximately 20 times that seen on LDEF. This exposure would result in significant material loss of unprotected ram facing organic matrix composites. Several protective coatings for composites were flown on LDEF including anodized aluminum, vacuum deposited coatings, a variety of thermal control coatings, metalized Teflon, and leafing aluminum. Results from the testing and analysis of the coated and uncoated composite specimens flown on LDEF's leading and trailing edges provide the baseline for determining the effectiveness of protectively coated composites in LEO. In addition to LDEF results, results from shuttle flight experiments and ground based testing will be discussed.

Dursch, Harry W.↗
NASA NTRS1974

Development for application of parylene coatings

A practical method of applying a parylene (paraxylene) coating to hybrid microcircuit devices was developed for the prevention of circuit malfunctions existing prior to package sealing or formed upon exposure to the service environment. It was found that paralene and an associated primer (if used) had generally little or no adverse effect on the active and passive elements of typical hybrid microcircuits. Exceptions were related to high frequency circuitry, low resistivity thick film resistors, and highly sensitive PIN diodes. Advantages of the use of the coating included increased dielectric strength and increased interconnection bond strength. Coating service life in nitrogen or nitrogen with low levels of oxygen as a contaminant is shown to be in excess of 1000 hours at 150 C and can be projected to be in excess of 5000 hours at 125 C.

Oberin, F. W.↗
NASA NTRS1986

Environmentally stable polymers and coatings for space application: CH-5, supplement 10

High molecular weight, randomly coupled poly(imide siloxane) soluble block copolymers were synthesized from bis(amino propyl) polydimethylsiloxane equilibrates of various molecular weights, aromatic metalinked diamines, and 3,3'-4,4'-benzophenone tetracarboxylic dianhydride (BTDA). Two synthetic procedures were successfully used to synthesize the poly(amic acid siloxane) intermediates. For both synthetic procedures, a cosolvent system was employed to achieve complete solvation of all components throughout the polymerization. Physical property characterization is continuing.

Sykes, G.↗
NASA NTRS1993

X Ray, Far, and Extreme Ultraviolet Coatings for Space Applications

The idea of utilizing imaging mirrors as narrow band filters constitutes the basis of the design of extreme ultraviolet imagers operating at 58.4 nm and 83.4 nm. The net throughput of both imaging-filtering systems is better than 20 percent. The superiority of the EUV self-filtering camera/telescope becomes apparent when compared to previously theoretically designed 83.4-nm filtering-imaging systems, which yielded transmissions of less than a few percent and therefore less than 0.1 percent throughput when combined with at least two imaging mirrors. Utilizing the self-filtering approach, instruments with similar performances are possible for imaging at other EUV wavelengths, such as 30.4 nm. The self-filtering concept is extended to the X-ray region where its application can result in the new generation of X-ray telescopes, which could replace current designs based on large and heavy collimators.

Zukic, M.↗
NASA NTRS1953

Relative Importance of Various Sources of Defect-Producing Hydrogen Introduced into Steel During Application of Vitreous Coatings

When porcelain enamels or vitreous-type ceramic coatings are applied to ferrous metals, there is believed to be an evolution of hydrogen gas both during and after the firing operation. At elevated temperatures rapid evolution may result in blistering while if hydrogen becomes trapped in the steel during the rapid cooling following the firing operation gas pressures may be generated at the coating-metal interface and flakes of the coating literally blown off the metal. To determine experimentally the relative importance of the principal sources of the hydrogen causing the defects, a procedure was devised in which heavy hydrogen (deuterium) was substituted in turn for regular hydrogen in each of five possible hydrogen-producing operations in the coating process. The findings of the study were as follows: (1) the principal source of the defect-producing hydrogen was the dissolved water present in the enamel frit that was incorporated into the coating. (2) the acid pickling, the milling water, the chemically combined water in the clay, and the quenching water were all minor sources of defect-producing hydrogen under the test conditions used. Confirming experiments showed that fishscaling could be eliminated by using a water-free coating.

Moore, Dwight G↗
NASA NTRS2003

Increased Surface Fatigue Lives of Spur Gears by Application of a Coating

Hard coatings have potential for increasing gear surface fatigue lives. Experiments were conducted using gears both with and without a metal-containing, carbonbased coating. The gears were case-carburized AISI 9310 steel spur gears. Some gears were provided with the coating by magnetron sputtering. Lives were evaluated by accelerated life tests. For uncoated gears, all of fifteen tests resulted in fatigue failure before completing 275 million revolutions. For coated gears, eleven of the fourteen tests were suspended with no fatigue failure after 275 million revolutions. The improved life owing to the coating, approximately a six-fold increase, was a statistically significant result.

Krantz, Timothy L.↗
NASA NTRS2003

High Resistivity Transparent/Conductive Coatings for Space Applications: Problems and Possible Improvements

We have prepared transparent films with a sheet relativity of 10(exp 1) to 10(exp 12) ohm/square by co-depositing a transparent conducting oxide (TCO) with magnesium fluoride, using two independently controlled RF magnetron sputter guns to facilitate adjustment of the film composition, Co-deposited indium tin oxide (ITO) and MgF2 on quartz and flexible polymeric substrate exhibited reasonably stable sheet resistivity over several months' time, with substantially lower optical reflectance than that of pure ITO. However, exposure to low-intensity blue light reduces sheet resistivity by as much as two orders of magnitude. Our results suggest this photoconductivity effect may be present in all InO(x)-based materials. We find that sheet resistivity can by "tuned" by admitting a small amount of high-purity air during deposition offering the possibility of closed loop process control.

Cashman, Thomas↗
NASA NTRS1986

Electrically conductive, black thermal control coatings for space craft application. II - Silicone matrix formulation

Five black electrically conductive thermal-control coatings have been formulated and tested for application on the Galileo spacecraft. The coatings consisted of organic and inorganic systems applied on titanium and aluminum surfaces. The coatings were tested under simulated space environment conditions. Coated specimens were subjected to thermal radiation and convective and conductive heating from -196 to 538 C. Mechanical, physical, thermal, electrical, and optical characteristics, formulation, mixing, application, surface preparation of substrates, and a method of determining electrical resistance are presented for the silicone matrix formulation designated as GF-580.

Hribar, V. F.↗
NASA NTRS1988

Current status and future trends in turbine application of thermal barrier coatings

This paper provides an overview of the current status and future trends in application of thermal barrier coatings (TBC) to turbine components, and in particular to high turbine airfoils. Included are descriptions of the favorable results achieved to date with bill-of-material applications of plasma deposited TBC, and recent experience with developmental coatings applied by electron beam-physical vapor deposition.

Sheffler, Keith D.↗
NASA NTRS1992

An 834 A reflective coating for magnetospheric imagery applications

We have designed a multiple-layer coating which selectively reflects 834 A radiation and suppresses 1025 A and 1216 A radiation. The structure of the coating material consists of a very thin (50-150 A) metal (nickel) layer, on top of a semitransparent dielectric material (magnesium fluoride), over an aluminum substrate. Three such coatings were produced at NASA Goddard Space Flight Center using an existing coating facility which is not optimized for thin coatings. In spite of such fabrication difficulties, we have obtained encouraging results.

Chakrabarti, Supriya↗
NASA NTRS2001

Testing of Environmentally Preferable Aluminum Pretreatments and Coating Systems for Use on Space Shuttle Solid Rocket Boosters (SRB)

The solid rocket booster (SRB) has historically used a chromate conversion coating prior to protective finish application. After conversion coating, an organic paint system consisting of a chromated epoxy primer and polyurethane topcoat is applied. An overall systems approach was selected to reduce waste generation from the coatings application and removal processes. While the most obvious waste reduction opportunity involved elimination of the chromate conversion coating, several other coating system configurations were explored in an attempt to reduce the total waste. This paper will briefly discuss the use of a systems view to reduce waste generation from the coating process and present the results of the qualification testing of nonchromated aluminum pretreatments and alternate coating systems configurations.

Clayton, C.↗