Sulfur prevails in coatings on glass droplets - Apollo 15 green and brown glasses and Apollo 17 orange and black /devitrified/ glasses
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Butler, J., Jr.↗
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Evaluation of glass resin coatings for solar cell applications
Using a variety of non-vacuum deposition techniques coatings were implemented on silicon solar cells and arrays of cells interconnected on Kapton substrates. The coatings provide both antireflection optical matching and environmental protection. Reflectance minima near 2% was achieved at a single wavelength in the visible. Reflectance averaging below 5% across the useful collection range was demonstrated. The coatings and methods of deposition were: (1) Ta2O5 spun, dipped or sprayed; (2) Ta2O5.SiO2 spun, dipped or sprayed; (3) GR908 (SiO2) spun, dipped, or sprayed. Total coating thickness were in the range of 18 microns to 25 microns. The coatings and processes are compatible with single cells or cells mounted on Kapton substrates.
Field, M. B.↗
Development of optical coatings for cos thin film solar cells third quarterly report, jun. 1 - aug. 1, 1965
Sputtering of glass coatings on cadmium sulfide thin film solar cells
GLASS COATING↗
Study of recrystallization and devitrification of lunar glass
The technique of differential thermal analysis (DTA) was applied to the study of the Apollo 17 orange soil (74220,63) and the Apollo 16 glass coated anorthite (64455,21). These glasses show accentuated exotherms of strain relief in the annealing range which is indicative of rapid cooling. These are amenable to interpretation by comparison to the known history of synthetic glasses. Synthetic glasses were prepared whose similarity in behavior between the lunar glasses and their synthetic analogs is striking. Approximate rates of cooling of the lunar glasses were determined from comparative DTA of lunar and synthetic glasses and from the determination of the relation of strain relief in the annealing range to quench rate. At higher temperatures the glasses show exotherms of crystallization. The crystallization products associated with the exothermic reactions have been identified by X-ray diffraction and the surface morphologies developed by strain relief and crystallization have been characterized with scanning electron microscopy.
Ulrich, D. R.↗
Low-temperature deposition of low resistivity ZnSe films by reactive sputtering
The use of reactive dc magnetron cosputtering of Zn and the dopant In in an H2Se/Ar gaseous mixture is described. It is observed that initial deposition using pure Zn targets produced yellowish transparent ZnSe films on glass with a film resistivity of 10 to the 8th ohms cm and deposition using a Zn target doped with a fixed 1 percent of In produced ZnSe films with resistivities of about 10,000 ohms cm. The improvement of film conductivity by optimizing the In content in the ZnSe films is discussed; the ZnSe resistivity dependence on In flux is studied. Optical absorption/transmission measurements reveal a photon energy band gap of 2.65 eV at room temperature and X-ray diffraction show highly oriented polycrystalline films on glass with the c axis parallel to the plane of the film. Compositional analysis was performed and the Zn/Se ratio is measure as 48.8/49.0 with an In concentration of 1.16 percent. ZnSe films deposited on glass and conducting SnO2-coated glass substrates with a resistance of 20 ohms cm and a substrate temperature of 120 C have been fabricated.
Stirn, R. J.↗
Highly conducting ZnSe films by reactive magnetron sputtering
This paper presents the results of an effort to deposit high-conductivity ZnSe on glass and conducting SnO2-coated glass substrates by reactive magnetron sputter deposition, using pure metal sputter targets of Zn and dopants such as In, Ga, and Al. Clear yellow ZnSe films were successfully obtained. By using substrate temperatures as low as 150 C, cosputtered dopants, and sputter parameters and H2Se injection rates which maximize the Zn-to-Se ratio in the films, ZnSe bulk resistivities have been lowered by up to seven orders of magnitude, reaching values as low as 20 ohm cm. The most effective dopant to data has been In, cosputtered with Zn in amounts leading to In atomic concentrations as high as 1.4 percent. Atomic-absorption measurements show an average 49.9/48.9 ratio of Zn to Se.
Nouhi, A.↗
CuInSe2/ZnSe solar cells using reactively sputter-deposited ZnSe
Results on CuInSe2/ZnSe thin-film heterojunction photovoltaic devices are presented. By the use of reactive magnetron cosputtering of Zn and In dopant in Ar/H2Se, ZnSe thin films have been deposited on glass and conducting SnO2-coated glass substrates with resistivity as low as 20 ohm-cm at deposition temperatures as low as 120 C. Preliminary ZnSe depositions onto CuInSe2 films supplied by industrial laboratories are encouraging. Reactive-sputter-deposition parameters for ZnSe have yet to be optimized for CuInSe2 substrates; however, open-circuit voltages as high as 430 mV were obtained. The highest short-circuit current density, as determined by spectral response weighted for AM1.5 global insulation, was 37.4 mA/sq cm. In all cases, a highly conductive ZnO film was overcoated onto the ZnSe to reduce the overall sheet resistance.
Nouhi, A.↗
Low-Cost Electrically-Heated Glass Panels
Inexpensive process converts architectural reflective-coated glass into electrically heated panels. Technique utilizes reflective layer as heating element in ordinary glass. Panels have many applications, including automobile windows, home-heating panels, temperature-controlled windows or containers, and food warming trays.
Shlichta, P. J.↗
Anti-reflection coatings on large area glass sheets
Antireflective coatings which may be suitable for use on the covers of photovoltaic solar modules can be easily produced by a dipping process. The coatings are applied to glass by drawing sheets of glass vertically out of dilute aqueous sodium silicate solutions at a constant speed, allowing the adherent liquid film to dry, then exposing the dried film to concentrated sulfuric acid, followed by a water rinse and dry. The process produces coatings of good optical performance (96.7 percent peak transmission at 0.540 mu M wavelength) combined with excellent stain and soil resistance, and good resistance to abrasion. The process is reproduceable and easily controlled.
Pastirik, E.↗
Battery plate containing filler with conductive coating
The plate (10) comprises a matrix or binder resin phase (12) in which is dispersed particulate, conductive tin oxide such as tin oxide coated glass fibers (14). A monopolar plate (11) is prepared by coating a layer (18) of electrolytically active material onto a surface of the plate (10). Tin oxide is prevented from reduction by coating a surface of the plate (10) with a conductive, impervious layer resistant to reduction such as a thin film (22) of lead adhered to the plate with a layer (21) of conductive adhesive. The plate (10) can be formed by casting a molten dispersion from mixer (36) onto a sheet (30) of lead foil or by passing an assembly of a sheet (41) of resin, a sheet (43) of fiberglass and a sheet (45) of lead between the nip of heated rollers (48, 50).
Rowlette, John J.↗
Battery plate containing filler with conductive coating
The plate (10) comprises a matrix or binder resin phase (12) in which is dispersed particulate, conductive tin oxide such as tin oxide coated glass fibers (14). A monopolar plate (11) is prepared by coating a layer (18) of electrolytically active material onto a surface of the plate (10). Tin oxide is prevented from reduction by coating a surface of the plate (10) with a conductive, impervious layer resistant to reduction such as a thin film (22) of lead adhered to the plate with a layer (21) of conductive adhesive. The plate (10) can be formed by casting a molten dispersion from mixer (36) onto a sheet (30) of lead foil or by passing an assembly of a sheet (41) of resin, a sheet (43) of fiberglass and a sheet (45) of lead between the nip of heated rollers (48, 50).
Rowlette, John J.↗
Formation of Leading-Edge Pinholes in the Space Shuttle Wings Investigated
The space shuttle wing leading edge and nose cap are composed of a carbon/carbon composite that is protected by silicon carbide. The coefficient of thermal expansion mismatch leads to cracks in the silicon carbide. The outer coating of the silicon carbide is a sodium-silicate-based glass that becomes fluid at the shuttles high reentry temperatures and fills these cracks. Small pinholes roughly 0.1 mm in diameter have been observed on these materials after 12 or more flights. These pinholes have been investigated by researchers at the NASA Johnson Space Center, Rockwell International, the Boeing Company, Lockheed Martin Corporation, and the NASA Glenn Research Center at Lewis Field to determine the possible sources and the extent of damage. A typical pinhole is illustrated in the photomicrographs. These pinholes are found primarily on the wing leading edges and not on the nose cap, which is covered when the orbiter is on the launch pad. The pinholes are generally associated with a bead of zincrich glass. Examination of the orbiter and launch structure indicates that weathering paint on the launch structure leads to deposits of zinc-containing paint flakes on the wing leading edge. These may become embedded in the crevices of the wing leading edge and form the observed zinc-rich glass. Laboratory experiments indicate that zinc oxide reacts vigorously with the glass coating on the silicon carbide. Thus, it is likely that this is the reaction that leads to pinhole formation (Christensen, S.V.: Reinforced Carbon/Carbon Pin Hole Formation Through Zinc Oxide Attack. Rockwell International Internal Letter, RDW 96 057, May 1996). Cross-sectional examination of pinholes suggests that they are enlarged thermal expansion mismatch cracks. This is illustrated in the photomicrographs. A careful microstructural analysis indicates that the pinhole walls consist of layers of zinc-containing glass. Thus, pinholes are likely formed by zinc oxide particles lodging in crevices and forming a corrosive zinc-rich glass that enlarges existing cracks. Having established the likely source of the pinholes, we next needed to model the damage. Our concern was that if a pinhole went through the silicon carbide to the carbon/carbon substrate, oxygen would have a clear path to oxidize the carbon at high temperatures. This possibility was examined with studies in a laboratory furnace. An ultrasonic drill was used to make artificial pinholes in a sample of protected carbon/carbon. After exposure, the specimens were weighed and cross-sectioned to quantify the extent of oxidation below the pinhole. The results at higher temperatures showed good agreement with a simple diffusion-control model. This model is based on the two-step oxidation of carbon to carbon monoxide and carbon dioxide. The fluxes are illustrated in the final figure. The model indicates a strong dependence on pinhole diameter. For smaller diameters and short times, the oxidation of carbon is very limited.
Jacobson, Nathan S.↗
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.↗
Petrographic and petrological studies of lunar rocks
Clasts, rind glass, matrix glass, and matrix minerals from five Apollo 15 glass-coated breccias (15255, 15286, 15465, 15466, and 15505) were studied optically and with the SEM/microprobe. Rind glass compositions differ from sample to sample, but are identical, or nearly so, to the local soil, suggesting their origin by fusion of that soil. Most breccia samples contain green or colorless glass spheres identical to the Apollo 15 green glasses. These glasses, along with other glass shards and fragments, indicate a large soil component is present in the breccias. Clast populations include basalts and gabbros containing phases highly enriched in iron, indicative of extreme differentiation or fractional crystallization. Impact melts, anorthosites, and minor amounts of ANT suite material are also present among the clasts. Tektite glasses, impact melts, and breccias from the Zhamanshin structure, USSR, were also studied. Basic tektite glasses were found to be identical in composition to impact melts from the structure, but no satisfactory parent material has been identified in the limited suite of samples available.
Winzer, S. R.↗
Design application and development of spacecraft in LEO utilizing LDEF results
In general, the results from the Long Duration Exposure Facility (LDEF) have provided much useful information on material sensitivity in the low-Earth orbit (LEO) environment. This is particularly true for selected materials such as thermal control coatings, composites, polymers, fasteners and solar cells. However, LDEF material sensitivity data for other materials like glasses, glass coatings, lubricants, adhesives and seal materials were limited. Some of this important LDEF material sensitivity data has not yet been addressed in detail at the LDEF meetings. The type of material information needed in the design and development of a new spacecraft in LEO depends to a large extent on program phase. In early program phases it is only necessary to have material sensitivity data to determine what materials may or may not work. Later program phases require details on the material strength, optical properties, and/or other long term survivability requirements for materials in LEO. Unfortunately, documentation of exposure results for many materials sensitivity experiments that flew on LDEF has not yet been summarized in a convenient form for use by multiple users. Documentation of this data in a form convenient for scientists, engineers as well as technicians remains a significant area of concern for the aerospace industry. Many of the material experiments that flew on LDEF were only designed to measure material sensitivity for one year in an LEO environment. However, some materials expected to survive one year simply did not survive the 5.8 years that LDEF eventually remained in orbit. Therefore the survivability of several materials in an LEO environment was determined by default. Most of the LDEF materials experiments were not designed to establish long term material survivability data. This long term material survivability data is particularly useful in later program phases of spacecraft development. The lack of more controlled materials experiments to determine long term material survivability was one of the major limitations of many LDEF experiments. The identified need for this critical information on the long term survivability offers a challenge to possible future LDEF type experiments.
Rauch, George B., Jr.↗
Atomic-Oxygen-Durable Microsheet Glass Reflector
Advanced solar dynamic concentrator concepts being considered by the NASA Lewis Research Center for space power systems include one utilizing microsheet glass coated with silver. For this material, a 5000-angstrom layer of silver is deposited on the back side of a contoured piece of microsheet glass, 0.2-mm thick. The silvered side is then bonded to a contoured aluminum, magnesium, or graphite epoxy face sheet with a space-qualified, pressure-sensitive thin-film adhesive. Experience gained from the development of this technology suggests that this material may reduce the cost and improve the performance of solar dynamic concentrators. This microsheet glass technology provides an effective barrier to atomic oxygen attack and provides the opportunity to utilize silver-reflective coatings in low-Earth-orbit solar dynamic applications.
Source record↗
Advanced Porous Coating for Low-Density Ceramic Insulation Materials
The need for improved coatings on low-density reusable surface insulation (RSI) materials used on the space shuttle has stimulated research into developing tougher coatings. The processing of a new porous composite "coating" for RST called toughened unipiece fibrous insulation Is discussed. Characteristics including performance in a simulated high-speed atmospheric entry, morphological structure before and after this exposure, resistance to Impact, and thermal response to a typical heat pulse are described. It is shown that this coating has improved impact resistance while maintaining optical and thermal properties comparable to the previously available reaction-cured glass coating.
Leiser, Daniel B.↗
Glass in the bottom of small lunar craters - An observation from Apollo 15.
The origin of glazed rock fragments and glassy splatter in the bottom of fresh, 0.5- to 3.0-m-diameter lunar craters has been the subject of much debate. Evidence presented from Apollo 15 data indicates that one such crater, with an associated glass-coated projectile, is of low velocity, 'secondary' origin. It is shown that, for the crater examined, the glassy material cannot have been formed in situ by impact fusion due to the low energy involved. It is suggested that the glass in many such craters may be carried as a semi-liquid or solidified coating on incoming rock projectiles ejected from local primary impact craters of larger size.
Schaber, G. G.↗