Search NASA⌕ Search

SEARCH · Search NASA

Results for “METAL COATING”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Hybrid Deployable Foam Antennas and Reflectors

Hybrid deployable radio antennas and reflectors of a proposed type would feature rigid narrower apertures plus wider adjoining apertures comprising reflective surfaces supported by open-cell polymeric foam structures (see figure). The open-cell foam structure of such an antenna would be compressed for compact stowage during transport. To initiate deployment of the antenna, the foam structure would simply be released from its stowage mechanical restraint. The elasticity of the foam would drive the expansion of the foam structure to its full size and shape. There are several alternatives for fabricating a reflective surface supported by a polymeric foam structure. One approach would be to coat the foam with a metal. Another approach would be to attach a metal film or a metal-coated polymeric membrane to the foam. Yet another approach would be to attach a metal mesh to the foam. The hybrid antenna design and deployment concept as proposed offers significant advantages over other concepts for deployable antennas: 1) In the unlikely event of failure to deploy, the rigid narrow portion of the antenna would still function, providing a minimum level of assured performance. In contrast, most other concepts for deploying a large antenna from compact stowage are of an "all or nothing" nature: the antenna is not useful at all until and unless it is fully deployed. 2) Stowage and deployment would not depend on complex mechanisms or actuators, nor would it involve the use of inflatable structures. Therefore, relative to antennas deployed by use of mechanisms, actuators, or inflation systems, this antenna could be lighter, cheaper, amenable to stowage in a smaller volume, and more reliable. An open-cell polymeric (e.g., polyurethane) foam offers several advantages for use as a compressible/expandable structural material to support a large antenna or reflector aperture. A few of these advantages are the following: 3) The open cellular structure is amenable to compression to a very small volume - typically to 1/20 of its full size in one dimension. 4) At a temperature above its glass-transition temperature (T(sub g)), the foam strongly damps vibrations. Even at a temperature below T(sub g), the damping should exceed that of other materials. 5) In its macroscopic mechanical properties, an open-cell foam is isotropic. This isotropy facilitates computational modeling of antenna structures. 6) Through chemical formulation, the T(sub g) of an open-cell polyurethane foam can be set at a desired value between about - 100 and about 0 C. Depending on the application, it may or may not be necessary to rigidify a foam structure after deployment. If rigidification is necessary, then the T(sub g) of the foam can be tailored to exceed the temperature of the deployment environment, in conjunction with providing a heater to elasticize the foam for deployment. Once deployed, the foam would become rigidified by cooling to below T(sub g). 7) Techniques for molding or machining polymeric foams (especially including open-cell polyurethane foams) to desired sizes and shapes are well developed.

Rivellini, Tommaso↗
NASA NTRS1986

Development of AC impedance methods for evaluating corroding metal surfaces and coatings

In an effort to investigate metal surface corrosion and the breakdown of metal protective coatings the AC Impedance Method was applied to zinc chromate primer coated 2219-T87 aluminum. The model 368-1 AC Impedance Measurement System recently acquired by the MSFC Corrosion Research Branch was used to monitor changing properties of coated aluminum disks immersed in 3.5% NaCl buffered at ph 5.5 over three to four weeks. The DC polarization resistance runs were performed on the same samples. The corrosion system can be represented by an electronic analog called an equivalent circuit that consists of transistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for resistances and capacities that can be assigned in the equivalent circuit following a least squares analysis of the data describe changes that occur on the corroding metal surface and in the protective coating. A suitable equivalent circuit was determined that predicts the correct Bode phase and magnitude for the experimental sample. The DC corrosion current density data are related to equivalent circuit element parameters.

Knockemus, Ward↗
NASA NTRS1987

Protective coatings for composite tubes in space applications

Protective coatings for graphite/epoxy (Gr/Ep) tubular structures for a Manned Space Station truss structure were evaluated. The success of the composite tube truss structure depends on its stability to long-term exposure to the Low Earth Orbit (LEO) environment with particular emphasis placed on atomic oxygen. Concepts for protectively coating Gr/Ep tubes include use of inorganic coated metal foils and electroplating. These coatings were applied to Gr/Ep tubes and then subjected to simulated LEO environmnet to evaluate survivability of coatings and coated tubes. Evaluation included: atomic oxygen resistance, changes in optical properties and adhesion, abrasion resistancem surface preparation required, coating uniformity, and formation of microcracks in the Gr/Ep tubes caused by thermal cycling. Program results demonstrated that both phosphoric and chromic acid anodized Al foil provided excellent adhesion to Gr/Ep tubes and exhibited stable optical properties when subjected to simulated LEO environment. The SiO2/Al coatings speuttered onto Al foils also resulted in an excellent protective coating. Electroplated Ni exhibited unaccepatble adhesion loss to Gr/Ep tubes during atomic oxygen exposure.

Dursch, Harry W.↗
NASA NTRS1987

Protective coatings for composite tubes in space applications

Protective coatings for graphite/epoxy (Gr/Ep) tubular structures for a manned Space Station truss structure were evaluated. The success of the composite tube truss structure depends on its stability to long-term exposure to the low earth orbit (LEO) environment, with particular emphasis placed on atomic oxygen. Concepts for protectively coating Gr/Ep tubes include use of inorganic coated metal foils and electroplating. These coatings were applied to Gr/Ep tubes and then subjected to simulated LEO environment to evaluate survivability of coatings and coated tubes. Evaluation included: atomic oxygen resistance, changes in optical properties and adhesion, abrasion resistance, surface preparation required, coating uniformity, and formation of microcracks in the Gr/Ep tubes caused by thermal cycling. Program results demonstrated that both phosphoric and chromic acid anodized Al foil provided excellent adhesion to Gr/Ep tubes and exhibited stable optical properties when subjected to simulated LEO environment. The SiO2/Al coatings sputtered onto Al foils also resulted in an excellent protective coating. Electroplated Ni exhibited unacceptable adhesion loss to Gr/Ep tubes during atomic oxygen exposure.

Dursch, Harry W.↗
NASA NTRS2010

Comparison of the Mineralogy of Comet Wild 2 Coma Grains to Other Astromaterials

We propose that Kuiper Belt samples (in this case comet coma grains from the Jupiter family comet Wild 2) are recognizably different from the bulk of materials in outer belt asteroids, because of their different formation positions and times in the early solar system. We believe this despite similarities found between some Wild 2 grains and components of carbonaceous chondrites (i.e. some CAI and chondrules). Kuiper Belt samples must preserve measurable mineralogical and compositional evidence of formation at unique positions and times in the early solar nebula, and these formational differences must have imparted recognizable special characteristics. We hypothesize that these characteristics include: (1) Unique major element compositional ranges of common astromaterial minerals, especially olivine and pyroxene; (2) Unique minor element compositions of major silicate phases, especially olivine and low-Ca pyroxene; (3) Degree and effects of radiation processing -- including amorphous rims, metal coatings, and Glass with Embedded Metal and Sulfides (GEMS); (4) Presence of abundant presolar silicate grains as recognized by anomalous oxygen in silicates; (5) Oxidation state of the mineral assemblage. We are working our way through all available Wild 2 samples, selecting 1-2 non-consecutive viable TEM grids from each possible extracted Wild 2 grain. We especially prefer TEM grids from grains for which complete mineralogical details have not been published (which is to say the majority of the extracted grains). We are performing a basic mineralogic survey by E-beam techniques, to establish the essential features of the extracted Wild 2 grains. We are making a particular effort to carefully and accurately measure minor elements of olivine and pyroxene, as these minerals are widespread in astromaterials, and comparisons of their compositions will serve to place the Wild 2 silicates in contact with asteroids, meteorites and chondritic interplanetary dust particles processing. We are also making a special effort to search for mineralogical products of aqueous alteration, since their presence would reveal that Wild 2 was once internally heated, a result with dramatic implications for models of early solar system primitive bodies. Thus far carbonates are the only potential evidence for aqueous alteration for Wild 2.

Frank, David↗
NASA NTRS2005

Solid Freeform Fabrication of Composite-Material Objects

Composite solid freeform fabrication (C-SFF) or composite layer manufacturing (CLM) is an automated process in which an advanced composite material (a matrix reinforced with continuous fibers) is formed into a freestanding, possibly complex, three-dimensional object. In CLM, there is no need for molds, dies, or other expensive tooling, and there is usually no need for machining to ensure that the object is formed to the desired net size and shape. CLM is a variant of extrusion-type rapid prototyping, in which a model or prototype of a solid object is built up by controlled extrusion of a polymeric or other material through an orifice that is translated to form patterned layers. The second layer is deposited on top of the first layer, the third layer is deposited on top of the second layer, and so forth, until the stack of layers reaches the desired final thickness and shape. The elements of CLM include (1) preparing a matrix resin in a form in which it will solidify subsequently, (2) mixing the fibers and matrix material to form a continuous pre-impregnated tow (also called "towpreg"), and (3) dispensing the pre-impregnated tow from a nozzle onto a base while moving the nozzle to form the dispensed material into a patterned layer of controlled thickness. When the material deposited into a given layer has solidified, the material for the next layer is deposited and patterned similarly, and so forth, until the desired overall object has been built up as a stack of patterned layers. Preferably, the deposition apparatus is controlled by a computer-aided design (CAD) system. The basic CLM concept can be adapted to the fabrication of parts from a variety of matrix materials. It is conceivable that a CLM apparatus could be placed at a remote location on Earth or in outer space where (1) spare parts are expected to be needed but (2) it would be uneconomical or impractical to store a full inventory of spare parts. A wide variety of towpregs could be prepared and stored on spools until needed. Long-shelf-life towpreg materials suitable for such use could include thermoplastic-coated carbon fibers and metal-coated SiC fibers. When a spare part was needed, the part could be fabricated by CLM under control by a CAD data file; thus, the part could be built automatically, at the scene, within hours or minutes.

Wang, C. Jeff↗
NASA NTRS1975

Growth defects in thick ion-plated coatings

Industrial ion plating conditions were selected to deposit metallic coatings such as copper, gold, and chromium 2 micrometer thick on metal and glass substrates. The surface finishes of 304 stainless steel, copper, and brass were utilized with mechanically and electrolytically polished surfaces. Nodular growth occurred in these coatings during ion plating as revealed by scanning electron microscopy. Surface irregularities such as scratches, steps, ledges, and so forth are responsible for outward growth, the typical cone type, whereas surface contaminants and loosely settled foreign particles are responsible for lateral growth; namely, the extreme localized surface outgrowths. These defect crystallographic features create porosity in the coatings when subjected to stresses and strains.

Spalvins, T.↗
NASA NTRS1988

Testing of materials for passive thermal control of space suits

An effort is underway to determine the coating material of choice for the AX-5 prototype hard space suit. Samples of 6061 aluminum have been coated with one of 10 selected metal coatings, and subjected to corrosion, abrasion, and thermal testing. Changes in reflectance after exposure are documented. Plated gold exhibited minimal degradation of optical properties. A computer model is used in evaluating coating thermal performance in the EVA environment. The model is verified with an experiment designed to measure the heat transfer characteristics of coated space suit parts in a thermal vacuum chamber. Details of this experiment are presented.

Squire, Bernadette↗
NASA NTRS2014

In-Situ Wire Damage Detection System

An in-situ system for detecting damage in an electrically conductive wire. The system includes a substrate at least partially covered by a layer of electrically conductive material forming a continuous or non-continuous electrically conductive layer connected to an electrical signal generator adapted to delivering electrical signals to the electrically conductive layer. Data is received and processed to identify damage to the substrate or electrically conductive layer. The electrically conductive material may include metalized carbon fibers, a thin metal coating, a conductive polymer, carbon nanotubes, metal nanoparticles or a combination thereof.

Williams, Martha K.↗
NASA NTRS2001

Surface Texturing Investigated for a High Solar Absorptance Low Infrared Emittance Solar Collector

The objective of this work was to design, build, and vacuum test a high solar absorptance, low infrared emittance solar collector for heat engine and thermal switching applications. Mini-satellites proposed by the Applied Physics Laboratory for operation in environments that are subject to radiation threat may utilize a heat engine for power and a thermal bus for thermal control. To achieve this goal, a surface having high solar absorptance and low infrared emittance is needed. At the NASA Glenn Research Center, one concept being pursued to achieve this goal is texturing high thermal conductivity graphite epoxy composites using a directed atomic oxygen beam and then coating the textured surface with a reflective metallic coating. Coupons were successfully textured, coated, and evaluated. A variety of texturing conditions were explored, and textures were documented by scanning electron microscopy. Copper, gold, silver, iridium, and aluminum coatings were applied, and the highest solar absorptance to infrared emittance ratio was found to be 1.3. A full-sized solar collector was manufactured with this ratio, and the amount of heat collected was observed using an Inconel calorimeter installed in a bench-top vacuum chamber equipped with a solar simulator. Results to date indicate good heat flow through the system, with 9 W of heat flow measured by the calorimeter.

Jaworske, Donald A.↗
NASA NTRS2017

Thermophysical Properties of Cold and Vacuum Plasma Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings: Electrical and Thermal Conductivity, Thermal Diffusivity, and Total Hemispherical Emissivity - Part 1

This two-part paper reports the thermophysical properties of several cold and vacuum plasma sprayed monolithic Cu and Ni-based alloy coatings. Part I presents the electrical and thermal conductivity, thermal diffusivity, and total hemispherical emissivity data while Part II reports the specific heat capacity data for these coatings. Metallic copper alloys, stoichiometric NiAl and NiCrAlY coatings were fabricated by either the cold sprayed or the vacuum plasma spray deposition processes for thermal property measurements between 77 and 1223 K. The temperature dependencies of the thermal conductivities, thermal diffusivities, electrical conductivities and total hemispherical emissivities of these cold and vacuum sprayed monolithic coatings are reported in this paper. The electrical and thermal conductivity data correlate reasonably well for Cu-8%Cr-1%Al, Cu-23%Cr-5%Al and NiAl in accordance with the Wiedemann-Franz (WF) law although a better fit is obtained using the Smith-Palmer relationship. The Lorentz numbers determined from the WF law are close to the theoretical value.

Raj, S. V.↗
NASA NTRS1982

Beam Splitter Intensities Are Preselected

New beam splitter is a block of optically clear material with two parallel polish faces. Some of area of one surface is coated with totally reflecting layer, which may be metal or dielectric. On opposite surface, a metal coating of stepped thickness offers a different reflectivity at each step. Width and spacing of reflecting zones are chosen to accommodate angle of spacing of incidence of input beam and desired spacing of ouput beams.

Campbell, W.↗
NASA NTRS1981

Progress in Protective Coatings for Aircraft Gas Turbines: A Review of NASA Sponsored Research

Problems associated with protective coatings for advanced aircraft gas turbines are reviewed. Metallic coatings for preventing titanium fires in compressors are identified. Coatings for turbine section are also considered, Ductile aluminide coatings for protecting internal turbine-blade cooling passage surface are also identified. Composite modified external overlay MCrAlY coatings deposited by low-pressure plasma spraying are found to be better in surface protection capability than vapor deposited MCrAlY coatings. Thermal barrier coating (TBC), studies are presented. The design of a turbine airfoil is integrated with a TBC, and computer-aided manufacturing technology is applied.

Merutka, J. P.↗